Journal of Organometallic Chemistry - Aktuelle Forschungsartikel
Aktuelle Forschungsartikel: Metallorganik
Die Urheberrechte und Veröffentlichungsrechte der in der nachfolgenden Liste aufgeführten Fachartikel liegen bei den jeweiligen Verlagen, die am Ende des jeweiligen Artikels als Quelle genannt werden. Diese sind auch für die Inhalte verantwortlich.
Weitere aktuelle Fachartikel von Chemiezeitschriften ähnlicher Thematik finden Sie im Navigationsmenue links.
Hinweise zur Veröffentlichung Ihrer Pressemitteilung unter Internetchemie.Info entnehmen Sie bitte der entsprechenden Info-Seite.
Diese Seite können Sie mit folgender Tastenkombination nach Stichwörtern durchsuchen: <STRG> und <F>.
Hier aufgeführte Forschungsartikel:
Journal of Organometallic Chemistry - Verlag: Elsevier
Die Zeitschrift hat eine lange Tradition in der Veröffentlichung von Originalarbeiten zu theoretischen Aspekten, Strukturchemie, Synthese, physikalische und chemische Eigenschaften einschließlich Reaktionsmechanismen und praktische Anwendungen von metallorganischen Verbindungen.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 711 Timothy P. Curran, Whitney E. Smith, Peter C. Hendrickson A series of N-protected amino acid alkynylesters were prepared by reaction of the amino acid carboxylate group with either propargyl alcohol (to yield the asymmetric esters 2a–c) or with 1, 4-but-2-yne diol (to yield the symmetric esters 3a–d). The alkynylesters were reacted with W(CO)3(dmtc)2 to yield monoalkyne complexes having the general formula W(CO)(dmtc)2(alkynyl ester). The monoalkyne complexes 6a–f were unstable in the presence of oxygen and had to be kept under an inert atmosphere. Analysis of the NMR spectra of the monoalkyne complexes showed that two diastereomers were formed in the synthesis, and that there was rapid rotation of the alkyne about the tungsten center at 23 °C and above with both diastereomers. At lower temperatures alkyne rotation is significantly slowed. Symmetric alkynylesters of a dipeptide (4) and tripeptide (5) were also prepared and reacted with W(CO)3(dmtc)2 to yield monoalkyne complexes. The resulting complexes (6g and 6h) also formed two diastereomers and displayed rapid rotation of the alkyne about the tungsten center at 23 °C and above, and slow rotation at lower temperatures. The amide NH protons in 6g and 6h were probed by DMSO titration to see if they were involved in intramolecular hydrogen bonds; they were not, which indicates that the peptide portions of 6g and 6h adopt an extended conformation in solution.
Graphical abstract
Graphical abstractHighlights
Two peptides linked together via ester bonds to 1,4-dihydroxy-2-butyne coordinate to a tungsten center and adopt an extended conformation.? Alkynylpeptides were synthesized and were reacted with tungsten to form monoalkyne complexes. ? The resulting monoalkyne complexes display relatively rapid rotation about the tungsten-alkyne bond. ? The peptides in a series of symmetrical alkynylpeptides adopt an extended conformation in solution.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volumes 708–709 Sze Tat Tan, Yew Chin Teo, Wai Yip Fan The addition of pyrroles onto alkynes has been catalyzed by a dinuclear ruthenium complex, Ru2(CO)4(PPh3)2Br4, resulting in the formation of geminal 2-vinylpyrroles in high yields under mild conditions. Further functionalization with pyrroles or alkynes to afford dipyrrolmethanes or 2,5-bis(vinyl)pyrroles via the vinyl functional group can readily be achieved. A mechanism involving cationic ruthenium complexes was proposed based on the product regioselectivity, deuteration and infrared spectroscopic studies carried out on the catalytic process.
Graphical abstract
Graphical abstractHighlights
In this work, we report the ability of Ru(CO)4L2Br4 (where L = CO or PPh3) to catalyze the hydroarylation reaction of pyrroles and terminal alkynes. The unprecedented bis(vinyl)pyrroles and mixed pyrrole double addition product was formed in the process..? Pyrrole addition onto alkynes has been catalyzed by Ru2(CO)4(PPh3)2Br4. ? Formation of exclusively geminal 2-vinylpyrrole product in high yields. ? Further addition to give dipyrrolmethanes or 2,5-bis(vinyl)pyrroles is possible. ? A mechanism involving cationic ruthenium complexes was proposed.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 711 Diana V. Aleksanyan, Vladimir A. Kozlov, Nikolay E. Shevchenko, Valentine G. Nenajdenko, Andrei A. Vasil’ev, Yulia V. Nelyubina, Ivan V. Ananyev, Pavel V. Petrovskii, Irina L. Odinets A series of novel hybrid pincer ligands bearing thiophosphoryl and imino groups as donating arms was obtained by the condensation of 3-diphenylthiophosphorylbenzaldehyde with RNH2 (R = Ph, tBu) to afford aldimine derivatives 2a, b or by the reaction of lithiated 3-(thiophosphoryl)bromobenzene with an appropriate substituted lactam yielding their ketimine analogs 2c–e with 5–7-membered azacycloalkene moieties. The direct cyclopalladation of the ligands with (PhCN)2PdCl2 in MeCN under reflux led to ?3-NCS pincer complexes 3b–e with two five-membered fused metallacycles, isolated in low to moderate yields (12–53%); their structures were confirmed by multinuclear NMR and X-ray diffraction study. The palladacycles demonstrated high activity as (pre)catalysts for the Suzuki cross-coupling of phenylboronic acid with aryl bromides, which was found to increase in the series 3e ? 3d <3c< 3b, i.e. passing from ketimine derivatives 3d, e with larger azacycloalkene to their analog with smaller five-membered cyclic imine moiety and further to benzaldimine complex 3b. The tendency observed was explained by the controlled release of Pd(0) catalytically active species in the case of less sterically hindered complexes.
Graphical abstract
Graphical abstractHighlights
A series of novel hybrid pincer ligands bearing thiophosphoryl and aldimine or ketimine groups as donating arms and their ?3-NCS palladium complexes active as (pre)catalysts in the Suzuki cross-coupling was obtained and characterized.? The synthetic routes to novel pincer ligands of NCS type were developed. ? The ligands bear thiophosphoryl and aldimine or ketimine donating arms. ? Synthesis and characterization of ?3-NCS palladium pincer complexes. ? The complexes demonstrate high activity as (pre)catalysts in the Suzuki reaction. ? The effect of the ligand structure on the catalytic performance was elucidated.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 711 Grzegorz Wesela-Bauman, Lech Jastrz?bski, Pawe? Kurach, Sergiusz Luli?ski, Janusz Serwatowski, Krzysztof Wo?niak The simple one-pot approach to functionalized diarylborinic 8-oxyquinolates has been developed starting with selected dihalobenzenes (Hal = Br, I) and (dialkoxy)phenylboranes PhB(OR)2 (R = Me, Et). The initial step results in halogenated diarylborinic “ate” complexes which are prone to halogen–lithium exchange when treated with t-BuLi. The resultant dianionic lithiated diarylborinic “ate” complexes of the type [(LiAr)PhB(OR)2]Li were reacted with selected electrophiles followed by hydrolysis to give unsymmetrically substituted diarylborinic acids isolated in the form of respective 8-hydroxyquinoline complexes as the final products in moderate to good yields. The crystal structure of (2-fluoro-4-formylphenyl)(phenyl)borinic 8-oxyquinolinate has been determined by X-ray diffraction. The alternative method involving the lithiation of B-protected bis(halophenyl)borinic N,N-dimethylethanolamine esters followed by the quench with electrophiles has also been investigated.
Graphical abstract
Graphical abstractHighlights
The useful one-pot approach to unsymmetrical diarylborinic 8-oxyquinolates has been developed.? One-pot synthesis of new unsymmetrical diarylborinic 8-oxyquinolinates. ? Structures verified using NMR (1H, 11B, 13C) spectroscopy and elemental analysis. ? Single crystal X-ray structure of (2-fluoro-4-formylphenyl)(phenyl)borinic 8-oxyquinolinate.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 711 Rafael Fernández-Galán, Antonio Antiñolo, Fernando Carrillo-Hermosilla, Isabel López-Solera, Antonio Otero, Amparo Serrano-Laguna, Elena Villaseñor The guanidines (HNi-Pr)2CNAr (Ar = 4-t-BuC6H41, 4-BrC6H42 and 2,4,6-Me3C6H23) have been used in the synthesis of the lithium salts [Li{i-PrN(HNiPr)CNAr}(THF)]24–6 and [Li2{(Ni-Pr)2CNAr}] 7–9. Complexes [Zr{?2,N,N?-(Ni-Pr)(NAr)CNH(i-Pr)}2Cl2] (Ar = 4-t-BuC6H410, 4-BrC6H411, 2,4,6-Me3C6H212), which contain an asymmetrical monoanionic guanidinate ligand coordinated to the zirconium atom, were obtained by protonolysis of 1–3 in the presence of NEt3 or by a metathesis reaction of 4–6 with ZrCl4. The zirconocene complexes [Zr(?5-C5H5)2{?2,N,N?-(Ni-Pr)(NAr)CNH(i-Pr)}Cl] (Ar = 4-t-BuC6H413, 4-BrC6H414, 2,4,6-Me3C6H215) and [Zr(?5-C5H5)2{?2,N,N?-(Ni-Pr)2CNAr}] (Ar = 4-t-BuC6H416, 4-BrC6H417, 2,4,6-Me3C6H218) were synthesized by metathesis reactions of the corresponding lithium salts and Zr(?5-C5H5)2Cl2. Complexes 16–18 exhibit dynamic behavior in solution and this was studied by variable-temperature NMR experiments. The molecular structures of 4 and 10 were determined by single-crystal X-ray diffraction.
Graphical abstract
Graphical abstractHighlights
The molecular structure of lithium salts [Li{i-PrN(HNiPr)C=N(4-t-BuC6H4)}(THF)]2 were determined by single-crystal X-ray diffraction. Changes from asymmetrical monoanionic guanidinate ligands to symmetrical dianionic guanidinate ligands have been observed. A notable fact in this process is the intermolecular interactions. Asymetrical guanidinate-supported zirconocene complexes exhibit dynamic behavior in solution.? The X-ray structure of a lithium monoanionic guanidinate compound is reported. ? Change in the coordination modes of guanidinate complexes in solution is proposed. ? Evolution should be explained by a decoordination and intermolecular interaction. ? Fluxional behavior was studied for the guanidinate zirconocene complexes.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 712 Dariusz Bia?ek, Konrad Kowalski, Jacek ?cianowski, Zbigniew Rafi?ski, Andrzej Wojtczak We report the synthesis of chiral ferrocenyl selenides of general formula: Fe(C5H4SeR*)(C5H5) and Fe(C5H4SeR*)2 where R* = neomenthyl and cis-myrtanyl. The title compounds have been obtained by the straightforward reaction of 1,1?-dilithioferrocene-TMEDA adduct with either (+)-dineomenthyl diselenide or (?)-bis(cis-myrtanyl) diselenide. We also report herein on the X-ray crystal structure of known 1,1?-bis(phenylseleno)ferrocene, Fe(C5H4SePh)2. All newly-obtained derivatives were characterized by 1H and 13C NMR, mass spectra and elemental analyses.
Graphical abstract
Graphical abstractHighlights
Synthesis and characterization of chiral ferrocenyl selenides via straightforward reaction of 1,1?-dilithioferrocene with optically active terpene dialkyl diselenides is described. Obtained compounds constitute an entirely new class of chiral ferrocenyl selenides. The X-ray crystal structure of known 1,1?-bis(phenylseleno)ferrocene is reported.? New chiral ferrocenyl selenides. ? Utilization of optically active terpene dialkyl diselenides toward ferrocene functionalization. ? X-ray diffraction studies on 1,1?-bis(phenylseleno)ferrocene.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 711 Javier A. Cabeza, Marina Damonte, M. Guadalupe Hernández-Cruz The tetraruthenium carbonyl cluster complexes [Ru4(?-H)4(?2-Ln)(CO)10], which contain a ditopic ligand (Ln) in which an N-heterocyclic carbene moiety is combined with a thioether (L1), a phosphine (L2 and L3), an NHC (L4), or a pyridine (L5 and L6) fragment, have been prepared by treating [Ru4(?-H)4(CO)12] with the corresponding ligand. In these compounds, the ditopic ligand chelates a ruthenium atom that is also attached to three hydrides. In the reactions involving L1, L2 and L3, an ionic species, identified as [HLn]+ [Ru4(?-H)3(CO)12]?, has been recognized as a reaction intermediate.
Graphical abstract
Graphical abstractHighlights
Tretraruthenium carbonyl cluster complexes containing a ditopic ligand in which an N-heterocyclic carbene moiety is combined with a thioether, a phosphine, an NHC, or a pyridine fragment have been prepared by treating [Ru4(?-H)4(CO)12] with the corresponding ligand.? Reactions of [Ru4(?-H)4(CO)12] with ditopic ligands. ? Thioether-, phosphine-, NHC- and pyridine-functionalized ditopic NHC ligands. ? CO-substitution reactions in [Ru4(?-H)4(CO)12]. ? Detection of ionic reaction intermediates.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 Alexey N. Egorochkin, Olga V. Kuznetsova, Nadiya M. Khamaletdinova, Lada G. Domratcheva-Lvova The literature data on substituent influence on the isomer shifts ? and quadrupole splittings ? in Mössbauer spectra for 32 series of iron, tin, antimony, and gold compounds have been considered using the correlation analysis. It has been established for the first time that the ? and ? values depend not only on the inductive and resonance effect but also on the polarizability of substituents; besides, in many cases these values vary under the action of steric effects of substituents. The polarizability effect consists in an electrostatic attraction between the partial charge on the Mössbauer atoms (57Fe, 119Sn, 121Sb, 197Au) and the dipole moments induced by this charge in the substituents. The polarizability contribution ranges up to about 60%.
Graphical abstract
Highlights
The isomer shifts ? and quadrupole splittings ? in Mössbauer spectra for 32 series of iron, tin, antimony, and gold compounds depend on joint influence of the inductive, resonance, and polarizability effects of X substituents.? Mössbauer spectra for 32 series of iron, tin, antimony, and gold compounds. ? Isomer shifts ?(57Fe, 119Sn, 121Sb, 197Au) and quadrupole splittings ?(57Fe, 119Sn, 121Sb, 197Au). ? The influence of the inductive, resonance, polarizability, and steric effects of substituents.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 Izabela B?aszczyk, Andrzej Gniewek, Anna M. Trzeciak A series of trimeric palladium complexes of the [Pd3(?-Cl)4(P–C)2] (P–C = orthometallated aryl phosphite) formula have been prepared and structurally characterized using 31P NMR and ESI-MS methods. The structure of [Pd3(?2-Cl)4{k2-P,C–P(O–o-CH3C6H3)(O–o-CH3C6H4)2}2], 1c, was determined by X-ray diffraction. It is compared with the structure of the dimeric complex [Pd2(?-Cl)2{k2-P,C–P(O–m-CH3C6H3)(O–m-CH3C6H4)2}2], 3b. The trimeric palladium complexes very efficiently catalyzed the Suzuki–Miyaura and Hiyama reactions in ethane-1,2-diol and the Sonogashira cross-coupling in ionic liquids. The mercury test confirmed the homogeneous pathway of the Suzuki–Miyaura reaction, although Pd(0) nanoparticles were observed by TEM in the post-reaction mixture.
Graphical abstract
Highlights
Synthesis and structural characterization of trimeric orthometallated palladium phosphito complexes of the type [Pd3(?-Cl)4(P-C)2]. The trimeric palladium complexes act as very efficient catalysts of Suzuki-Miyaura and Hiyama reactions in ethane-1,2-diol. High catalytic activity of trimeric palladium complexes in Sonogashira cross-coupling in ionic liquids was evidenced. The homogeneous pathway of the Suzuki-Miyaura reaction was confirmed by the Hg(0) test, although Pd(0) nanoparticles were formed at the end of the catalytic process.? Synthesis of new palladium trimeric complexes. ? Efficient catalysts for Suzuki–Miyaura and Hiyama reactions. ? Catalysts for Sonogashira reaction in ionic liquids. ? Homogeneous pathway of the catalytic reaction.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 712 Pradeep Mathur, Badrinath Jha, Abhinav Raghuvanshi, Raj Kumar Joshi, Shaikh M. Mobin At 0 °C, photolysis of a hexane solution containing Fe(CO)5 and 2-(phenylethynyl)benzaldehyde (1) affords a mixture of mononuclear (tricarbonyliron-2-phenylindenone, (2) and binuclear acetylene coupled iron carbonyl complexes [Fe(CO)3{?4-2,4–(C6H4CHO)2–3,5-(C6H5)2C4}Fe(CO)3], 3, [Fe(CO)3{ ?4-2-(?1–C6H4CHO)–4–(C6H4CHO)–3,5-(C6H5)2C4}Fe(CO)2], 4 and [Fe(CO)3{ ?4-4-(?1-2–C6H4CHO)–2–(C6H4CHO)–3,5-(C6H5)2 C4}Fe(CO)2], 5. In compounds 4 and 5, the exocyclic iron atom is ?4-bonded with the ferracyclopentadiene unit, and it bears two terminal carbonyls. Its 18 electron count is completed by virtue of the aldehydic oxygen atom coordinating to the iron atom. Photolysis of 2-(ferrocenylethynyl)benzaldehyde (6) under similar condition leads to the formation of tricarbonyliron-2-ferrocenylindenone (7) and tetracarbonyl(2-ferrocenyl-3-(2-formylphenyl)maleoyl)iron (8) predominantly.
Graphical abstract
Graphical abstractHighlights
Photolysis of a hexane solution of 2-(phenylethynyl)benzaldehyde and Fe(CO)5 at 0 °C results in a mixture of mononuclear (tricarbonyliron-2-phenylindenone) and binuclear ironcarbonyl complexes. Interestingly, in some of the binuclear complexes one of the aldehydic oxygen atoms is coordinated to the exocyclic iron.? Synthesis of phenyl and ferrocenyl substituted tricarbonylironindenone complexes. ? Formation of chelated ironcarbonyl complexes. ? Conversion of tricarbonylironindenone complexes to respective indenones. ? Phenyl substituted reactant prefer intermolecular coupling.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 711 Kevin P. McGowan, Adam S. Veige Trianionic pincer ligands are a new class of ligands that constrain three anionic metal–ligand bonds to the meridional plane and are capable of supporting highly reactive metal species exploitable for alkene polymerization. The previously reported NCN3- trianionic pincer CrIV–Me complex [2,6-iPrNCN]CrIV(Me)THF (1), upon activation by triisobutylaluminum (TIBA), catalyzes the polymerization of ethylene. Complex 1 (1 ?mol) in the presence of 35 equiv. of TIBA polymerizes ethylene with an activity of 7.02 × 106 g PE(molCr)?1 h?1 (75 °C).
Graphical abstract
Graphical abstractHighlights
A rare organometallic Cr(IV)–Me complex supported by an NCN3? trianionic pincer ligand is employed as a precatalyst in ethylene polymerization. The activity is high (7.02 × 106 g PE(molCr)?1 h?1) and only requires 10–35 equiv of inexpensive cocatalyst TIBA.? A trianionic pincer Cr(IV) precatalyst is employed in polyethylene synthesis. ? High polymerization activity 7.02 × 106 g PE(molCr)?1 h?1. ? Catalyst requires small cocatalyst loading (10–35 equiv). ? An optimal ratio of cocatalyst:catalyst is required to achieve maximum activity.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 Kiran Kumar Varma Chakrahari, Arunabha Thakur, Bijan Mondal, Rajendra Singh Dhayal, V. Ramkumar, Sundargopal Ghosh The reaction of an intermediate, generated from [Cp#MoCl4] [Cp# = Cp or Cp?; Cp = (?5-C5H5), Cp? = (?5-C5Me5)] and LiBH4.thf, with different chalcogen ligands yielded trimolybdaborane clusters 1–3, [(Cp#Mo)3(?-H)B8H6X2], (1: Cp# = Cp, X = H; 2: Cp# = Cp?, X = H; 3: Cp# = Cp?, X = Cl). Compounds 1–3 constitute an example of an unsaturated (n-4) sep cluster having very close structural similarities. These clusters represent 11-vertex boron-rich metallaboranes containing 66 cluster valence electrons (cve). All the compounds were fully characterized by various spectroscopic techniques, elemental analysis and the solid state structures were unequivocally established by X-ray diffraction analysis of 1–3.
Graphical abstract
Highlights
Reaction of [Cp#MoCl4] (Cp# = Cp, Cp?) with excess of LiBH4, followed by thermolysis with different chalcogenide ligands in toluene afforded closo 11-vertex molybdaborane clusters 1–3, [(Cp#Mo)3(?-H)B8H6X2], (1: Cp# = Cp, X = H; 2: Cp# = Cp?, X = H; 3: Cp# = Cp?, X = Cl).? The11-vertex boron-rich metallaborane has been isolated and structurally characterized. ? We observed trimolybdaboranes with low electron count, (n-4) sep. ? The dimolybdaheteroboranes have also been isolated in the reaction.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 711 Elizabeth S. Donovan, Greg A.N. Felton Four organometallic compounds of the type [Cp2M2(CO)n] (M = Fe, Ru, Mo, W) were evaluated electrochemically to probe the impact of variations in metal composition on ability to catalyze the deprotonation of weak acids, for the evolution of molecular hydrogen. The tungsten and molybdenum complexes undergo a less negative initial reduction, but provide no improvement for overpotential of dihydrogen evolution compared to iron when using 4-tert-butylphenol (pKa = 27.5) as a proton source Catalysis is thought to occur via protonation of the anions formed from the reduction of the dimers studied. The W-based anion catalyst represents the first example of a W-based organometallic hydrogen-producing electrocatalyst.
Graphical abstract
Graphical abstractHighlights
The structures of the four catalyst anions studied are shown over the periodic table, with the elements highlighted. Example cyclic voltammograms of the four parent dimers is shown above the periodic table.? Electrochemical comparison of Cp metal carbonyl species with varied metals. ? Hydrogen-generation from weak acid sources. ? Organometallic tungsten electrocatalyst.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 712 Ali Rahmatpour A new and environmentally benign method for the preparation of N-substituted pyrroles from one-pot condensation reaction of 2,5-hexanedione with amines and diamines in the presence of polystyrene-supported gallium trichloride (PS/GaCl3) as a highly active and reusable heterogeneous Lewis acid catalyst is presented. This new protocol has the advantages of easy availability, stability, reusability and eco-friendly of the catalyst, high to excellent yields, simple experimental and work-up procedure.
Graphical abstract
Graphical abstractHighlights
A new and environmentally benign method for the preparation of N-substituted pyrroles from one-pot condensation reaction of 2,5-hexanedione with amines and diamines using polystyrene-supported gallium trichloride (PS/GaCl3) as a highly active heterogeneous Lewis acid catalyst is presented. This protocol has the advantages of easy availability, stability, reusability and eco-friendly of the catalyst, high to excellent yields, simple experimental and work-up procedure.? Cross-linked polystyrene/GaCl3 complex was used as an efficient catalyst for the preparation of N-substituted pyrroles. ? The heterogeneous Lewis acid catalyst can be easily recycled and reused without significant loss of activity. ? Polystyrene-supported GaCl3 as catalyst leads to short reaction time, high yields of the products.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 711 Carmen Racles, Mihaela Silion, Nicolae Stanica, Maria Cazacu, Constantin Turta New complexes of the composition: {Fe3O(OOCR1COO)3}+ and {Fe3O(R2COO)6}+, where R1 = –(CH2)3–Si(CH3)2–O–Si(CH3)2–(CH2)3– or –(CH2)8–COO–CH2–Si(CH3)2–O–Si(CH3)2–CH2–COO–(CH2)8–; R2 = Si(CH3)3–O–Si(CH3)2–CH2–COO–(CH2)8–, were synthesized by direct synthesis using siloxane carboxylic salts and iron nitrate or by ligand exchange in ?3-oxo trinuclear iron(III) acetoxy-cluster with siloxane carboxylic acids. The obtained compounds have been characterized by elemental analysis, FT–IR and UV–Vis spectroscopy, mass spectrometry (ESI–MS), thermal analysis, Mössbauer spectroscopy, and magnetic measurements. By ESI–MS, in the starting iron acetate dodecanuclear cluster was detected besides the trinuclear compound. The new siloxane-containing iron(III) clusters showed a bathochromic shift in UV–Vis spectra compared to the acetate. The thermal decomposition starts above 200 °C and higher thermal stability was observed for the clusters with sebaco-siloxane diacid. The Mössbauer spectroscopy data indicate the presence of iron(III) in a high spin state. By using a potassium salt of sebacomethylpentamethyldisiloxane as a reactant and stabilizer, iron cluster nanoparticles were obtained, both by direct synthesis and ligand exchange. According to all our data, the direct synthesis is a more convenient reaction path, in terms of reaction conditions and purity of the final products.
Graphical abstract
Graphical abstractHighlights
New complexes of the composition: {Fe3O(OOCR1COO)3}+ and {Fe3O(R2COO)6}+, where R1 = –(CH2)3–Si(CH3)2–O–Si(CH3)2–(CH2)3– or –(CH2)8–COO–CH2–Si(CH3)2–O–Si(CH3)2–CH2–COO–(CH2)8–; R2 = Si(CH3)3–O–Si(CH3)2–CH2–COO–(CH2)8–, were synthesized and characterized.? New siloxane carboxylates iron (III) clusters were synthesized. ? ESI–MS was used to characterize the iron acetate and the reaction products. ? The presence of iron in high spin state was proved by Mössbauer spectroscopy and magnetic measurements. ? Iron cluster nano and submicron particles were also obtained.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volumes 708–709 Kioumars Aghapoor, Leila Ebadi-Nia, Farshid Mohsenzadeh, Mina Mohebi Morad, Yadollah Balavar, Hossein Reza Darabi Silica-supported bismuth(III) chloride (BiCl3/SiO2) acts as as a highly efficient heterogeneous Lewis acid catalyst for the Paal–Knorr pyrrole synthesis in hexane at room temperature. The catalyst exhibited remarkable reusable activity and higher catalytic performance than homogeneous BiCl3. A plausible mechanism for the catalytic action of BiCl3/SiO2 has been introduced.
Graphical abstract
Graphical abstractHighlights
Silica-supported bismuth(III) chloride (BiCl3/SiO2) acts as as a highly efficient heterogeneous Lewis acid catalyst for the Paal–Knorr pyrrole synthesis in hexane at room temperature. The catalyst exhibited remarkable reusable activity and higher catalytic performance than homogeneous BiCl3. A plausible mechanism for the catalytic action of BiCl3/SiO2 has been introduced.? Immobilization of Bi(III) ion onto silica surface. ? Formation of O–BiOCl as stable Lewis acid sites. ? Heterogeneous pyrrole synthesis applicable to a wide range of aniline substrates. ? Low catalyst loading with high activity. ? Catalyst recycled several times due to negligible leaching of the metal.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 711 Qiuping Ding, Huafang Ji, Dan Wang, Yuqing Lin, Weihua Yu, Yiyuan Peng A novel and efficient method for the arylation of 2-arylbenzothiazoles is described via C–H activation. The desired CAr–CAr bond formation proceeded efficiently with good functional-group tolerance and high regioselectivity. Proposed mechanism for the arylation of 2-arylbenzothiazole is depicted.
Graphical abstract
Graphical abstractHighlights
A novel and efficient method for the arylation of 2-arylbenzothiazoles is described via C–H activation. The desired CAr–CAr bond formation proceeded efficiently with good functional-group tolerance and high regioselectivity. Proposed mechanism for the arylation of 2-arylbenzothiazole is depicted.? Novel arylation of 2-arylbenzothiazoles is described via palladium-catalyzed C–H activation. ? CAr–CAr bond formation proceeded efficiently with good functional-group tolerance and high regioselectivity. ? Proposed mechanism for the arylation of 2-arylbenzothiazole is depicted.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 712 Trirup Dutta Choudhury, Yongqiang Shen, Nandiraju V.S. Rao, Noel A. Clark The synthesis, characterization and mesomorphic properties of a new series of acetate and chloro-bridged dinuclear orthopalladated complexes derived from azobenzene with terminal groups of hexadecyloxy moiety at one end and different polar groups (Me, Cl, F, NO2, CN) at the other end are described. The mesomorphic properties of both the ligands and complexes were investigated by polarizing optical microscopy and X-ray studies to understand the effect of polar group in the nature of mesophase produced. Among the complexes, all chloro-bridged complexes predominantly exhibited SmA phase. However the rare phenomenon of observing mesomorphism in acetato-bridged palladium (II) complexes due its typical open book shape had been realized in substituted acetato-bridged complexes with fluoro and cyano substituents in the ligands. Nitro and cyano substituted ligands only exhibited monotropic Smectic A phase. Model molecular arrangement based on X-ray studies is presented.
Graphical abstract
Graphical abstractHighlights
Open book-shaped acetate bridged cyclopalladated complexes with polar groups at one end exhibiting rare mesomorphism are presented.? Mesomorphic azo compounds with polar end groups are designed and synthesized. ? Designed and synthesized rare mesomorphic binuclear cyclopalladated azo compounds. ? Influence of bridging group and Nematic, SmA and SmE phases are discussed. ? Model molecular arrangement based on X-ray studies is presented.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 E.A. Goreshnik, A.A. Vakulka, Yu. I. Slyvka, M.G. Mys'kiv The alternating current electrochemical synthesis starting from ethanol solution of Cu(ClO4)2·6H2O, CuSO4·5H2O and Cu(BF4)2·6H2O with the equimolar mixture of 1- and 2-allylbenzotriazole (all-bta) has led to a formation of Cu[2-all-bta]ClO4 (I), Cu[2-all-bta]HSO4 (II) and Cu[2-all-bta]BF4·H2O (III) compounds. The direct interaction between Cu(ClO4)2·6H2O and the mixture of 1- and 2-allylbenzotriazole in ethanol solution results in an appearance of Cu[(1-all-bta)(2-all-bta)]ClO4 (IV) compound. These results are strikingly different from earlier performed syntheses using the same ligands mixture and copper(II) halides, and producing coordination compounds with 1-allylbenzotriazole only. Compounds I and II are isotypical and crystallize in a monoclinic space group Cc. I: a = 9.5413(10) Å, b = 12.3171(9) Å, c = 10.3264(10) Å, ? = 111.155(4)°, V = 1131.78(18) Å3, Z = 4. II: a = 9.1707(17) Å, b = 13.6639(17) Å, c = 9.4543(17) Å, ? = 105.555(7)°, V = 1141.3(3) Å3, Z = 4. The main feature of structures I and II is a chelate-bridging role of the ligand moiety, bonded to one copper ion via CC-bond of the allyl group and nitrogen atom of the triazole core, and to the second Cu+ centre by another N atom. Trigonal-pyramidal copper environment comprises of two nitrogen atoms from different ligand units, CC-bond and oxygen atom at the apical position. The bridging function of both Cu+ cations and 2-all-bta molecules results in the formation of infinite chains. High affinity of BF4? anion to the H2O leads to a formation of compound III including water molecule. It crystallizes in an orthorhombic Pbca space group, a = 13.502(8) Å b = 11.299(5) Å c = 16.124(8) Å, V = 2460(2) Å3, Z = 8. The ligand moiety plays the same as in I and II chelate-bridging function, but Cu+, being also bonded to CC group and to two N atoms, is connected with the disordered BF4? anion through the water bridge. In the crystal structure IV the metal ion possesses mixed-isomer surrounding, being bound to N-atom and CC-bond of 2-all-bta molecule, N-atom of 1-all-bta-moiety and O(ClO4?) atom at apical position. IR spectra confirm rather effective Cu–(CC) bonding.
Graphical abstract
Highlights
The Cu[2-all-bta]ClO4 (I), Cu[2-all-bta]HSO4 (II), Cu[2-all-bta]BF4·H2O (III) and Cu[(1-all-bta)(2-all-bta)]ClO4 (IV) compounds (1-all-bta and 2-all-bta are 1- and 2-allylbenzotriazoles respectively) have been obtained and characterized by single crystal X-ray diffraction and IR spectroscopy.? A mixture of 1- and 2-allylbenzotriazoles has been used as a ligand. ? CuI ionic salts selectively form complexes with 2-allylbenzotriazole. ? 2-Allylbenzotriazole demonstrates chelate-bridging coordination mode. ? Changing synthetic conditions results in a mixed-isomer complex. ? The first known CuHSO4 ?-complex has been obtained and characterized.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 712 Ning Zhao, Liang Chen, Wenshan Ren, Haibin Song, Guofu Zi Three new trinuclear organozinc complexes (4H)2Zn3Et2 (7), (5H)2Zn3Et2 (8) and (6H)2Zn3Et2 (9) have been prepared in good yields by alkane elimination between ZnEt2 and chiral biaryl-based NO2 ligands, (S)-2-(4,6-di-tert-butylhydroxyphenyl-2-methylamino)-2?-hydroxy-1,1?-binaphthyl (4H3), (S)-5,5?,6,6?,7,7?,8,8?-octahydro-2-(4,6-di-tert-butylhydroxyphenyl-2-methylamino)-2?-hydroxy-1,1?-binaphthyl (5H3) and (S)-2-(6-tert-butylhydroxyphenyl-2-methylamino)-2?-hydroxy-6,6?-dimethyl-1,1?-biphenyl (6H3), which are derived from (S)-2-amino-2?-hydroxy-1,1?-binaphthyl or (S)-2-amino-2?-hydroxy-6,6?-dimethyl-1,1?-biphenyl, respectively. Complexes 7–9 have been characterized by various spectroscopic techniques, elemental analyses, and X-ray diffraction analyses. Complex 7 derived from 4H3, has a C2v quasi-symmetric EtZnO2ZnN2(OPh)2ZnEt core structure, while complexes 8 and 9 derived from 5H3 or 6H3, adopt a C2 symmetric/quasi-symmetric EtZnO(OPh)ZnN2O(OPh)ZnEt core structure, indicating that the steric effect of the ligand plays an important role in the complex formation. Complexes 7–9 are active catalysts for the polymerization of rac-lactide, leading to the heterotactic-rich polylactides.
Graphical abstract
Graphical abstractHighlights
A new series of organozinc complexes have been prepared from chiral biaryl-based NO2 ligands. The organozinc complexes are active catalysts for the polymerization of rac-lactide, leading to the heterotactic-rich polylactides.? Three chiral organozinc complexes have been prepared and structurally characterized. ? The steric effect of the ligand plays an important role in the complex formation. ? The organozinc complexes are active catalysts for the polymerization of rac-lactide.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 Krishna K. Pandey Electronic, molecular structures and bonding analysis of the terminal neutral dimethylgallyl complexes of cobalt, rhodium and iridium [Me(PMe3)2(Me3GaCl)M(GaMe2)] (M = Co, Rh, Ir) and [Me(PMe3)2ClIr(GaMe2)] were investigated at the DFT/BP86/TZ2P/ZORA level of theory. The calculated geometry of dimethylgallyl iridium complex [Me(PMe3)2(Me3GaCl)M(GaMe2)] is in excellent agreement with structurally characterized iridium complex. Mayer bond order of the optimized structures shows that the M–Ga bonds in these complexes are essentially M–Ga single bond, which is also supported by the performed energy decomposition analysis. The orbital interactions between the metal and gallium arise mainly from M ? GaMe2 ? donation. In all complexes, the ?-bonding contribution is relatively smaller. The absolute values of the ?EPauli, ?Eint and ?Eelstat contributions to the M–Ga bonds increase according to M = Co < Rh < Ir.
Graphical abstract
Highlights
Theoretical calculations have been performed for the terminal dimethylgallyl complexes [Me(PMe3)2(Me3GaCl)M(GaMe2] (M = Co, Rh, Ir) and [Me(PMe3)2ClIr(GaMe2] using the exchange correlation functionals BP86/TZ2P. The absolute values of the ?Eint to the M–Ga bonds increase according to M = Co < Rh < Ir.? Theoretical investigation of dimethylgallyl complexes of Co, Rh, Ir. ? The M–Ga bonds in the studied complexes are nearly M–Ga single bond. ? Bond dissociation energy of the M–Ga bonds increases as Co < Rh < Ir. ? Electrostatic interactions are significantly larger than the covalent bonding. ? [GaMe2] ligand behaves predominantly as an ?-donor.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 Michinori Sumimoto, Takaaki Kuroda, Daisuke Yokogawa, Hidetoshi Yamamoto, Kenji Hori The formation process of an active species for the Pd(II)-catalyzed Mizoroki–Heck reaction between bromobenzene and ethylene was investigated theoretically using the DFT(B3PW91) method. In this mechanism, one need not consider the dissociation of the chloride ion from the PdCl2(dppe) complex. It was confirmed that the ethylene insertion into the Pd–Cl bond (Path A) occurs more easily than the C–Br oxidative addition (Path B) and the Cl? dissociation (Path Z) for the PdCl2(dppe) complex. In the next step, the C6H5Br approaches the Pd center of the complex with ethylene via the C–Br oxidative addition, followed by the ethylene insertion into the Pd–Cl bond (Path D) to form a six-coordinate complex, PdBrCl(C2H4Cl)(C6H5)(dppe). In the final step, a C–Cl elimination proceeds from the complex to give a four-coordinate complex, PdBr(C6H5)(dppe). The rate-determining step of Path D is the C–Cl reductive elimination, and the energy difference between reactant and TS was calculated to be 30.4 kcal/mol. Similar mechanisms releasing Cl–C4H8–Cl (Path E and F) are also acceptable, since those barrier heights were calculated to be 32.3 and 17.6 kcal/mol. Path D, E and F are plausible candidates to form the PdBr(C6H5)(dppe) complex as a starting complex of the catalytic cycle. The rate-determining step of the entire catalytic reaction using the PdBr(C6H5)(dppe) complex is the ?–H abstraction about the electronic energy of solute in solution and the free energy in solution, and those barrier heights were calculated to be 26.4 and 24.9 kcal/mol, respectively. As a result, the first step of the catalytic reaction mechanism is not the Cl? dissociation from the PdCl2(dppe) complex. Instead, the ethylene insertion into the Pd–Cl bond first proceeds to produce an active species, and next the PdBr(C6H5)(dppe) complex forms through Path D, E or F. It is concluded that the catalytic cycle of the Mizoroki–Heck reaction starts from PdBr(C6H5)(dppe).
Graphical abstract
Highlights
We investigated the starting complex of the Pd-catalyzed Mizoroki–Heck reaction between bromobenzene and ethylene using the DFT method. We examined the formation process of an active species without dissociation of the chloride ion from PdCl2(dppe) complex.? New active species for the Mizoroki-Heck reaction was investigated using DFT method. ? We examined the formation of an active species without dissociation of a chloride ion. ? It is concluded that the catalytic cycle starts from PdBr(C6H5)(dppe).
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 Ji?í Pinkas, Ivana Císa?ová, Jind?ich Karban, Jan Schraml, Jan Sýkora The products of phenylsilane dehydrocoupling were analyzed by means of advanced NMR techniques including LC–NMR. Attention was paid to the –SiPh– units not containing Si–H bonds. These units were observed in the 29Si NMR spectra reported previously. The 1J and 2J29Si INADEQUATE experiments were used to reveal the connectivities within oligosilane chains. The presence of the branched oligophenylsilanes was confirmed in the reaction catalyzed by Cp2Ti(OAr)2, Ar = (2,6-(iPr)2C6H3). Furthermore, the formation of silyl-substituted cyclic oligomers and the presence of branched oligophenylsilanes in the catalytic systems studied by other authors were discussed. The LC–NMR and INADEQUATE experiments were optimized using the linear and low oligomeric products which were obtained by other catalysts. Some of these results are also presented.
Graphical abstract
Highlights
The presence of the branched oligophenylsilanes in the metallocene catalyzed dehydrocoupling polymerization of phenylsilane is demonstrated on the reaction catalyzed by Cp2Ti(OAr)2, Ar = (2,6-(iPr)2C6H3).? The presence of branched silanes in dehydrocoupling reaction is shown. ? The signal of the branched tetramer and pentamer was assigned in 29Si NMR spectrum. ? The typical region (??56 ppm) of the terminating unit PhSiH2–SiPh< was identified.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 712 James Berstler, Annycardeli Lopez, Danièle Ménard, William G. Dougherty, W. Scott Kassel, Andrew Hansen, Amin Daryaei, Pearl Ashitey, Michael J. Shaw, Natalie Fey, Chip Nataro The oxidative electrochemistry of group VI and group VII metal carbonyl compounds containing 1,1?-bis(phosphino)ferrocene ligands with the general formula [M(CO)4(P?P)] (M = Cr, Mo, or W, P?P = 1,1?-bis(diisopropylphosphino)ferrocene (dippf) or 1,1?-bis(dicyclohexylphosphino)ferrocene (dcpf)) and [M(CO)3Br(P?P)] (M = Mn, P?P = 1,1?-bis(diphenylphosphino)ferrocene (dppf) or dippf; M = Re, P?P = dppf, dippf or dcpf) was investigated. Two reversible waves were observed in the electrochemistry of the Cr compounds, while the other compounds exhibited one wave with varying reversibility. The compounds were examined using spectroelectrochemistry, which was particularly useful in assigning the two waves in the Cr species. In addition, the X-ray structures of [Cr(CO)4(dippf)], [Cr(CO)4(dcpf)] and [Mn(CO)3Br(dippf)] were determined. The %Vbur values for dippf, dcpf and other bidentate phosphines have been calculated for these pseudo-octahedral Cr and Mn compounds and these structural studies have been supplemented by DFT optimized geometries for the Cr complexes.
Graphical abstract
Graphical abstractHighlights
The synthesis, X-ray crystal structures, electrochemistry and spectroelectrochemistry of several metal carbonyl compounds containing 1,1?-bis(phosphino)ferrocene ligands was investigated. The structural parameters of these octahedral compounds were compared to related square planar compounds. Spectroelectrochemistry was used to further examine the oxidative electrochemistry of these compounds.? Synthesis and structure analysis of metal carbonyl compounds. ? Comparison of structural parameters of bidentate phosphines. ? Electrochemistry of phosphinoferrocene compounds was examined. ? Spectroelectrochemistry used to examine site of oxidation.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 Fei Chen, Gao-Feng Wang, Yi-Zhi Li, Xue-Tai Chen, Zi-Ling Xue A series of iridium(I) and rhodium(I) carbonyl phosphine complexes bearing bis(N-heterocyclic carbene)borate ligands [H2B(ImtBu)2]Rh(CO)(PPh3) (5), [F2B(ImtBu)2]Rh(CO)(PPh3) (6), [F2B(ImtBu)2]Ir(CO)(PPh3) (7), [H2B(ImtBu)2]Rh(CO)(PCy3) (8), [F2B(ImtBu)2]Rh(CO)(PCy3) (9), and [F2B(ImtBu)2]Ir(CO)(PCy3) (10) (H2B(ImtBu)2 = dihydrobis(3-tert-butylimidazol-2-ylidene)borate; F2B(ImtBu)2 = difluorobis(3-tert-butylimidazol-2-ylidene)borate) have been prepared and characterized. IR stretching values of the CO ligands, the values of NMR coupling constants JRh–P, and electrochemical data are rationalized by the electronic effects of the bis(3-tert-butylimidazol-2-ylidene)borate and phosphine ligands. The results show that the ? donor capacity of bis(3-tert-butylimidazol-2-ylidene)borate is stronger than those of the analogous isoelectronic bis(pyrazolyl)borate (Bp?) and acetylacetonato (acac?) ligands. The molecular structures of complexes 6–10 have been determined by single-crystal X-ray diffraction, which showed square-plane geometries around the metal centers.
Graphical abstract
Highlights
Six iridium(I) and rhodium(I) carbene complexes have been prepared and characterized by IR spectroscopy, CV measurement and X-ray crystallography. The results support that the ? donor capacity of bis(3-tert-butylimidazol-2-ylidene)borate is stronger than isoelectronic bidentate Bp? and acac? ligands.? Six iridium(I) and rhodium(I) carbene complexes were synthesized and characterized. ? Molecular structures of five complexes have been determined by X-ray crystallography. ? IR, NMR and electrochemical properties were rationalized by the ligands electronic effects.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 Hiroshi Yamashita, Yoshitada Suzuki, Tumula Venkateshwar Rao, Yuko Uchimaru Polycarbosilanes with silylene–vinylene–phenylene–vinylene backbones and triphenylamine or carbazole unit-containing side chains were conveniently prepared by Pd-catalyzed one-pot reactions of a trihydrosilane (phenylsilane) with aromatic diynes (p- and m-diethynylbenzene) and triphenylamine or carbazole-unit containing acetylenes. Cyclic voltammetry of these polycarbosilanes suggested that dimerization processes of the pendant units took place during the electrochemical oxidation steps. In UV/vis absorption and emission spectra, the p-phenylene or triphenylamine unit-containing polymers showed ?max peaks at longer wavelength regions than the corresponding m-phenylene or carbazole unit-containing polymers. An energy transfer process from the backbone to the side chain was suggested in the polycarbosilane possessing m-phenylene and triphenylamine units. Photoluminescence quantum yields of these polymers ranged from 0.16 to 0.34 with the m-phenylene and triphenylamine units-containing polymer exhibiting the highest value. DSC analyses revealed that the p-phenylene polymers showed higher glass transition points (148–180 °C) than the corresponding m-phenylene polymers (129–158 °C). In TGA, the 5% weight loss temperatures were in the range of 382–444 °C, suggesting considerably high thermal stability of these polycarbosilanes. Ionization potentials were estimated by atmospheric photoelectron spectroscopy at 5.6–5.9 eV with the values of carbazole polymers being higher than those of the triphenylamine polymers.
Graphical abstract
Highlights
Pd-catalyzed one-pot reactions of a trihydrosilane with diynes and functional acetylenes efficiently provided silylene–vinylene–phenylene–vinylene polycarbosilanes with pendant triphenylamine or carbazole units. The resulting polymers exhibited unique electrochemical, optical, and thermal properties, depending on the natures of the main chain and pendant units.? Pd-catalyzed one-pot reactions efficiently provided functionalized polycarbosilanes. ? A resulting polymer exhibited unique photoluminescence via energy transfer. ? The polycarbosilanes showed considerably high thermal stability in DSC and TGA.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 Kwang-Hoi Lee, Joji Ohshita, Daiki Tanaka, Yuta Tominaga, Atsutaka Kunai Spiro-condensed dithienometalloles (metal = Si, Ge) and dithienothiametallines (metal = Si, Ge, Sn) were prepared by the ring closure reactions of dilithiated bithiophene and dithienyl sulfide with metal tetrachlorides, and their optical properties were studied with respect to the UV absorption and emission spectra. The absorption and emission maxima of them moved to higher energies by increasing the size of the center metal from Si to Ge and Sn, and stepwise oxidation of the ring sulfur atom in the dithienothiasiline system forming sulfoxide and sulfone linkages, making the fine tuning of the electronic states possible.
Graphical abstract
Highlights
Spiro-condensed dithienometalloles (metal = Si and Ge) and dithienothiametallines (metal = Si, Ge, and Sn) were prepared. The optical studies indicated that their electronic states could be finely tuned by changing the center elements and step-by-step oxidation of the bridging sulfur atom in spirobi(dithienothiasiline).? We prepared spiro-condensed dithienometalloles and dithienothiametallines. ? The optical properties were investigated. ? The electronic states could be finely tuned by structural modification.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 712 Fan He, Xiang Hao, Xiaoping Cao, Carl Redshaw, Wen-Hua Sun Nickel halide complexes of the type L2NiX2 (Ni1–Ni6, X = Cl; Ni7–Ni12, X = Br) bearing 2-benzimidazolyl-N-arylquinoline-8-carboxamide derived ligands have been synthesized and characterized by IR spectroscopy and elemental analysis. The molecular structures of the representative nickel complexes Ni8 and Ni11 revealed a distorted octahedral geometry at the nickel center. Upon activation with Et2AlCl, all such nickel pre-catalysts exhibited high activities for ethylene oligomerization. Furthermore, in the presence of MAO, they were shown to perform with good activities for the vinyl polymerization of norbornene.
Graphical abstract
Graphical abstractHighlights
Nickel halide complexes of the type L2NiX2 bearing 2-benzimidazolyl-N->arylquinoline-8-carboxamide ligands exhibited good to high activities in ethylene oligomerization upon activation with Et2AlCl, and performed with good activities for the vinyl polymerization of norbornene in the presence of MAO.? Bis(tridentate ligated) nickel dihalides of the type L2NiX2. ? 2-Benzimidazolyl-N-aryylquinoline-8-carboxamide tridentate ligands. ? Distorted octahedral geometry around cationic nickel. ? Nickel pre-catalysts exhibited good activities in ethylene oligomerization. ? Nickel pre-catalysts for the vinyl polymerization of norbornene.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 Roman D. Savka, Herbert Plenio The reaction of amino hexahydro-s-indacene with glyoxal, reduction of the diimine to the diamine and cyclization with HC(OEt)3 yields the new 1,3-bis(1,2,3,5,6,7-hexahydro-s-indacen-4-yl)-4,5-dihydro-1H-imidazol-3-ium chloride 3· HCl with conformationally restricted alkyl groups ortho to the heterocyclic substituent. Reaction of 3· HCl with Ag2O gave the respective silver NHC complex (yield 78%), which was used to synthesize the respective (3)IrCl(cod) (yield 86%), whose reaction with CO gave (3)IrCl(CO)26 (yield 98%). The Grubbs II type complex [(3)RuCl2(PCy3)(3-phenyl-indenylid-1-ene)] was synthesized (yield 68%) and converted into [(3)RuCl2(py)(3-phenyl-indenylid-1-ene)] (yield 78%) in pyridine solvent. With this complex the respective Grubbs–Hoveyda species (yield 68%) and two bisNHC complexes [(3)(NHCewg)RuCl2(3-phenyl-indenylid-1-ene)] (yield 87%, 89%) were obtained. The stereoelectronic properties of the new NHC ligand were determined employing IR spectroscopy, cyclic voltammetry and buried-volume analysis based on the crystal structure of complex 6. The activity of the ruthenium complexes in RCM reactions of sterically hindered substrates was tested.
Graphical abstract
Highlights
A new hexahydro-s-indacene based NHC ligand used for the synthesis of ruthenium-based olefin metathesis catalysts for sterically demanding RCM reactions is reported.? Synthesis of a new NHC ligand. ? Synthesis of new metal NHC complexes with Ag, Ir and Ru. ? Stereoelectronic properties of new NHC ligand. ? Olefin metathesis activity in RCM reactions of sterically demanding substrates.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 Paolo Coppo, Tommaso Marcelli A combination of computational techniques was used to study the phosphorescent emission of complexes with general formula [Cu3(?-dppm)3(?3-?1-C?CAr)2]BF4, with Ar = aryl. The calculated S0–T1 transition energies are in good agreement with the experimental emission maxima. Natural Transition Orbital analysis of the lowest triplet states indicates that the emission largely originates from a ? ? ?* excitation on one of the two acetylide ligands with only a marginal participation of the trinuclear copper(I) cluster, unlike previously proposed.
Graphical abstract
Highlights
The emission of complexes with general formula [Cu3(?-dppm)3(?3-?1-C?CAr)2]+ (with Ar = aryl) originates from a ? ? ?* transition on one of the two arylacetilide ligands, with only a marginal involvement of the copper atoms.? The phosphorescent emission of eight complexes has been studied by computational techniques. ? Both DFT and TD-DFT calculations satisfactorily predict the emission maxima. ? The phosphorescent emission originates from a ? ? ?* transition on one of the two arylacetilide ligands.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 710 Bin-Qiu Liu, Peng-Fei Yan, Ju-Wen Zhang, Guang-Ming Li A series of four m-ferrocenylbenzoate [m-ferrocenylbenzoate = Na(m-OOCH4C6Fc), Fc = (?5-C5H5)Fe(?5-C5H4)] copper(II) complexes Cu2(?2-OOCH4C6Fc)4(CH3OH)2 (1), Cu(?2-OOCH4C6Fc)2(2,2?-bpy) (2), Cu(?2-OOCH4C6Fc)2(1,10-phen) (3) and [Cu(?2-OOCH4C6Fc)2(4,4?-bpy)]n (4) (bpy = bipyridine, 1,10-phen = 1,10-phenanthroline) have been synthesized by reactions of Cu(CH3COO)2·H2O with Na(m-OOCH4C6Fc) and three types of N-donor ligands, respectively. X-ray diffraction analysis reveals that 1 shows a dimeric structure with a Cu?Cu distance of 2.5872(16) Å. 2 and 3 exhibit a mononuclear structure. The adjacent mononuclear molecules are packed into a one-dimensional (1D) chain through the ?–? interactions between the bpy rings in 2 or phen rings in 3. 4 displays a 1D zigzag chain structure. In 1, the m-OOCH4C6Fc anion adopts the bidentate-bridging coordination mode, whereas it adopts the bidentate-chelating coordination mode in 2–4. Magnetic study indicates that an antiferromagnetic interaction between the CuII ions exists in 1.
Graphical abstract
Highlights
A series of m-ferrocenylbenzoate [m-ferrocenylbenzoate = Na(m-OOCH4C6Fc), Fc = (?5-C5H5)Fe(?5-C5H4)] copper(II) complexes Cu2(?2-OOCH4C6Fc)4(CH3OH)2 (1), Cu(?2-OOCH4C6Fc)2(2,2?-bpy) (2), Cu(?2-OOCH4C6Fc)2(1,10-phen) (3) and [Cu(?2-OOCH4C6Fc)2(4,4?-bpy)]n (4) (bpy = bipyridine, 1,10-phen = 1,10-phenanthroline) have been synthesized and structurally characterized. Magnetic properties of 1 have been discussed.? Four copper(II) complexes constructed from the m-ferrocenylbenzoate and three types of N-donor ligands have been synthesized. ? The structures of N-donor ligands dominate the structures of four copper(II) complexes. ? The dinuclear m-ferrocenylbenzoate copper(II) complex possesses an antiferromagnetic property.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 712 Vitor Rosa, Sara Realista, Ana Mourato, Luisa Maria Abrantes, João Henriques, Maria José Calhorda, Teresa Avilés, Michael G.B. Drew, Vitor Félix Reaction of [Co(?5-C5H5)(CO)2], 1, with 1,1?-bis(diphenylphosphino)ferrocene (dppf) yields the new trinuclear complex [Co(?5-C5H5)(CO)]2(?-dppf), 2, which was structurally characterised by single crystal X-ray diffraction and showed two Co(?5-C5H5)(CO) moieties covalently linked by a dppf bridge. Electrochemical studies in dichloromethane revealed that both Co(I) and Fe(II) in the precursors were oxidized to Co(II)/Co(III) and Fe(III), respectively. On the other hand, in 2 the two first oxidation waves were assigned to Co, the Fe(II) centre requiring a higher potential than in free dppf. DFT calculations showed that the HOMOs of 2 were localised in the Co fragments, owing to the destabilisation of the Co(?5-C5H5)(CO) orbitals after binding dppf.
Graphical abstract
Graphical abstractHighlights
[Co(?5-C5H5)(CO)2] reacts with dppf to form the trinuclear [Co(?5-C5H5)(CO)]2(?-dppf). This complex oxidizes at Co(I), as reflected in the HOMO shown in the picture.? Formation of a trinuclear complex with dppf bridging two Co(I) centres. ? Electrochemistry studies show several oxidation processes. ? DFT calculations show the localisation of the HOMO in cobalt.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volumes 708–709 Wojciech P. Oziminski Structure of M(?5-C6H6)2 complexes, where M=(Be, Ma, Ca, Sr, Ba), and C6H6 is the pentafulvene, was optimized at the B3LYP/6–311++G(d,p)/ECP level of theory. Two types of complexes were found: (cis-) singlet ansa-metallocenes with the cis-arrangement of two pentafulvene rings and (trans-) triplet sandwich type pentafulvene complexes of trans-where two pentafulvene molecules are rotated in respect to each other by various degrees. All metals except beryllium are bonded in ?5-mode of coordination. The charge transfer of 1.6–1.8 e from the metal atom to the pentafulvene ring estimated by Natural Population Analysis results in aromatization of the fulvene rings, which is documented by three aromaticity indices: electronic pEDA, geometric HOMA and magnetic NICS(1)ZZ. For sandwich complexes pEDA and NICS(1)ZZ are linearly correlated. Bonding situation in systems under study was analyzed by Energy Decomposition Analysis at the B3LYP/TZP/ZORA level. The electrostatic contribution is dominant, especially in the case of cis-complexes, however the covalent contribution is substantial, especially for beryllium complex. Exceptionally low dissociation energy of magnesium complex can be explained by the fact that the electrostatic and orbital contributions are not fully compensating the high Pauli repulsion term.
Graphical abstract
Graphical abstractHighlights
The graphical abstract presents the trans-triplet calcium–pentafulvene complex optimized at the B3LYP/6–311++G(d,p) level of theory by using Gaussian 03 program.? Structure of alkaline earth metal complexes with pentafulvene were determined. ? Almost 2 e of charge transferred to the rings. ? HOMA, pEDA and NICS(1)ZZ suggest high aromatization of the rings. ? Bonding is more electrostatic than covalent. ? Magnesium complex has very low stability.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volumes 708–709 Andrea M. Geyer, Michael J. Holland, Robyn L. Gdula, Joel E. Goodman, Marc J.A. Johnson, Jeff W. Kampf Nitride complex NMo(OCMe2CF3)3 is synthesized in 78% yield on a multigram scale. Although the irreversible but sluggish conversion of terminal molybdenum–nitride complexes NMo(OCMe(CF3)2)3 (1) and NMo(OC(CF3)3)3(NCMe) (2) to their propylidyne analogs EtCMo(OR)3(DME) (OCMe(CF3)2 (3), OC(CF3)3 (4)) via metathesis with 3-hexyne occurs, the analogous reaction with NMo(OR)3 (OROCMe2CF3 (5), OCMe3 (6)) complexes does not occur under similar reaction conditions. However, the kinetic barrier to alkylidyne formation from 5 and 6 with internal alkynes can be overcome through the addition of simple Lewis acids, including MgBr2, MgI2 and BPh3 in specific instances. Although this typically leads to accelerated decomposition of the alkylidyne complex so formed, the combination of metal–nitride complex plus exogenous Lewis acid frequently leads to alkyne metathesis of the test substrates 1-phenyl-1-propyne and 1-phenyl-1-butyne under milder conditions than possible in the absence of Lewis acid, in some cases at room temperature. The interaction of solvent, ancillary alkoxide ligands, and Lewis acid is complex and was not predicted a priori. New benzylidyne complexes 4-MeOC6H4CMo(OC(CF3)3)3(MeOC6H4CN) (22%), 4-Ph–C6H4CMo(OC(CF3)3)3(4-PhC6H4CN) (46%) were isolated in low yield via the nitride-to-alkylidyne route upon reaction with suitable diarylalkynes. Several related alkylidyne complexes were formed but could not be separated cleanly from the alkyne reagents used.
Graphical abstract
Graphical abstractHighlights
Molybdenum–nitride complexes NMo(OC(CF3)nMe3?n)3 (n = 0–3) are pre-catalysts for metathesis of simple alkynes. Simple Lewis acids can accelerate the rate of alkyne metathesis dramatically, depending on the identities of the solvent, Lewis acid, and alkoxide ligands. In some cases (n = 2, 3) metal–alkylidyne complexes can be isolated. ? Molybdenum–nitride complexes react with alkynes to form alkylidyne analogs. ? Molybdenum–nitride complexes are pre-catalysts for alkyne metathesis. ? Alkyne metathesis catalyzed by nitride complexes is accelerated by Lewis acids.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volume 712 R?za Bayrak, Kaan Karao?lu, Yasemin Ünver, Kemal Sancak, Fatih Dumluda?, ?smail De?irmencio?lu The substituted [1,2,4]triazole 3 was obtained from the reaction between compound 1 and compound 2. Novel substituted phthalonitrile 5 was prepared by the substitution of the nitro group of 4-nitrophthalonitrile 4 with triazole moiety 3. The synthesis of metal-free, zinc, nickel, cobalt and copper phthalocyanines with four substituted [1,2,4]triazole groups on peripheral position were performed from cyclotetramerization of novel substituted dinitrile compound 5. Metal-free phthalocyanine 6 and its Zn-, Ni-, Co- and Cu- complexes 7–10 were prepared in DMAE at reflux temperature. All new compounds were characterized by a combination of elemental analyses, IR, 1H/13C NMR, MS and UV–vis spectroscopy. Aggregation behaviors of NiPc 8 and CuPc 10 were also investigated. While NiPc 8 was aggregated in acetone, DMF, DMSO, THF, ethylacetate and toluene and non-aggregated in dichloromethane and pyridine at 10 × 10?6 mol dm?3 concentration, CuPc 10 showed monomeric behavior in dichloromethane, DMSO, DMF, pyridine, THF and showed aggregation in acetone, ethylacetate and toluene at 14 × 10?6 mol dm?3 concentration. On the other hand, substituted NiPc 8 and CuPc 10 did not show aggregation behavior between 4 × 10?6–14 × 10?6 mol dm?3 concentration range in chloroform. Dc and ac conductivity and Impedance Spectroscopy (IS) studies were also done on thin films of compounds 6, 7, 8, 9 and 10 as a function of temperature (295–523 K) and frequency (40–105 Hz) under vacuum (?2 × 10?3 mbar) in dark. The compounds 7, 8, 9 and 10 showed nearly same dc conductivity values in the measured temperature range. Variation of dc conductivity of 6, 7, 8, 9 and 10 with temperature exhibited the semiconducting behavior. Variation of ac conductivity of the films with frequency represented by the function ?ac = A?s. The results indicated that charge transport mechanism of the films can be explained by hopping and small polaron tunneling model for 6, 7, 8, 9 and 10 depending on temperature and frequency region. Results of the impedance spectra measurements showed that, at high temperatures, depressed semicircles with different radius indicate deviation from Debye dispersion relation.
Graphical abstract
Graphical abstractHighlights
Substituted [1,2,4]triazole containing metal free and metallophthalocyanines synthesized. Aggregation behaviors of NiPc and CuPc have been investigated. Dc and ac conductivity and Impedance Spectroscopy (IS) studies have been done on thin films of metal-free and metallophthalocyanines as a function of temperature and frequency in dark.? The preparation of the substituted triazole 3 and the substituted phthalonitrile 5. ? Synthesis and characterization of metal-free 6 and metallophthalocyanines 7–10. ? Investigation of aggregation behaviors of the compounds 8 and 10. ? Dc and ac conductivity and Impedance Spectroscopy (IS) studies of compounds 6–10.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volumes 708–709 Devaraj Pandiarajan, Rengan Ramesh The reaction of [PdCl2(PPh3)2] and substituted pyridoxal hydrazone ligands (H2L) in methanol under reflux afford a series of palladium ONO coordinated complexes with general formula [Pd(PPh3)L] (where, L = dianionic terdentate pyridoxal hydrazones). All the palladium complexes are air stable and fully characterized by elemental analysis, spectral and X-ray diffraction methods. In chloroform solution all the metal complexes exhibit characteristic metal to ligand charge transfer (MLCT) absorptions and ligand based transitions. Molecular structure of one of the complexes (3) has been determined by X-ray crystallography indicates that the pyridoxal hydrazone ligands are coordinated to the palladium as a terdentate O, N, O donor and a distorted square-planar geometry is observed around palladium(II) metal center. Further, palladium-catalyzed protocol for Suzuki–Miyaura cross-coupling reactions by the complex (3) has been developed, enabling to obtain biaryl products in good to excellent conversions.
Graphical abstract
Graphical abstractHighlights
Five new palladium(II) pyridoxal hydrazones complexes have been synthesized and characterized. The single crystal X-ray analysis of complex (3) shows a square-planar geometry around palladium metal. The catalytic activity of one of the complexes in Suzuki–Miyaura cross-coupling of aryl bromides has been studied and was found to be an efficient catalyst.? Five new palladium(II) pyridoxal hydrazone complexes with PPh3 have been synthesized. ? Single crystal X-ray structure evidenced a square-planar geometry. ? The catalytic efficiency of Pd(II) complex was explored for S–M cross coupling.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volumes 708–709 Elena I. Klimova, Jessica J. Sanchez García, Tatiana Klimova, Teresa Ramírez Apan, Eduardo A. Vázquez López, Marcos Flores-Alamo, Marcos Martínez García Reactions of ethyl 2-acyl-3-ferrocenylacrylates (acyl = acetyl, benzoyl, p-nitrobenzoyl) with guanidine and 1,1-dimethylguanidine furnish ethyl 2-amino-6-ferrocenyl-4-methyl(aryl)-1,6-dihydropyrimidine-5-carboxylates. Their oxidative dehydrogenation with PhI(OAc)2 results in the corresponding ethyl 2-amino-6-ferrocenyl-4-methyl(aryl)pyrimidine-5-carboxylates. The structures of the synthesized compounds were established on the basis of the data from 1H and 13C NMR spectroscopy and confirmed by X-ray diffraction analysis. All compounds were tested in vitro against six human tumor cell lines U-251, PC-3,K-562, HCT-15, MCF-7 and SKLU-1 to assess their in vitro antitumor activity. The results suggest biological specificity towards PC-3 and K-562 cells for compounds 4a–c at doses 50 ?M, which are lower than cis-platin IC50's in the two cell lines. Additionally, peritoneal mouse macrophages (M?) were also evaluated for compounds 4a–f and 5a–f.
Graphical abstract
Graphical abstractHighlights
Reactions of ethyl 2-acyl-3-ferrocenylacrylates with guanidines furnish ethyl 2-amino-6-ferrocenyl-4-methyl(aryl)-1,6-dihydropyrimidine-5-carboxylates and ethyl 2-amino-6-ferrocenyl-4-methyl(aryl)pyrimidine-5-carboxylates. All compounds were tested in vitro against six human tumor cell lines U251, PC-3,K-562, HCT-15, MCF-7 and SKLU-1 to assess their in vitro antitumor activity.? Synthesis of novel ferrocenyl(dihydro)pyrimidines and aromatic pyrimidines. ? Ethyl 2-amino-6-ferrocenyl-1,6-dihydropyrimidine-5-carboxylates. ? Ethyl 2-amino-6-ferrocenylpyrimidine-5-carboxylates. ? Determination of antitumoral activity of ferrocenylpyrimidines.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volumes 708–709 Yue-Jian Lin, Ying-Feng Han, Guo-Xin Jin Treatment of binuclear complex [Cp*2Ir2(?-dhaq)Cl2] (H2dhaq = 1,5-dihydroxy-9,10-anthraquinone) with pyrazine or bifuncational pyridyl-based ligands (4,4?-bipyridine (bpy), E-1,2-bis(4?-pyridyl)ethene (bpe), and 2,5-bis(4?-pyridyl)- 1,3,4-oxadiazole (bpo)) in the presence of AgOTf (OTf = CF3SO3) in CH3OH, gave the corresponding tetranuclear complexes, with a general formula of [Cp*4Ir4(?-dhaq)2(?-L)2](OTf)4 (2a–2d), respectively. The molecular structure of [Cp*4Ir4(?-dhaq)2(?-pyrazine)2](OTf)4 (2a) has been determined by single-crystal X-ray analysis, revealing that the metal centers were connected by pyrazine and bis-bidentate dhaq2? ligands to construct a “slope” rectangular cavity with the dimension of 7.4 × 8.8 × 6.9 Å. 2a also exhibited unique properties in host–guest behavior.
Graphical abstract
Graphical abstractHighlights
Binuclear complex [Cp*2Ir2(?-dhaq)Cl2] (1) and tetranuclear complexes [Cp*4Ir4(?-dhaq)2(?-L)2](OTf)4 (2a–2d) (L = pyrazine, 4,4?-bipyridine, E-1,2-bis(4?-pyridyl)ethene and 2,5-bis(4?-pyridyl)-1,3,4-oxadiazole) are reported. Crystal structure and host–guest behavior of 2a have been investigated.? Novel half-sandwich iridium metallarectangles were synthesized. ? Structure of these metallarectangles was confirmed by X-ray crystallography. ? Such metallarectangles could display interesting host–guest properties.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volumes 708–709 Masafumi Hirano, Yumiko Sakate, Haruka Inoue, Yasutomo Arai, Nobuyuki Komine, Sanshiro Komiya, Xian-qi Wang, Martin A. Bennett The naphthalene complex of zerovalent ruthenium, [Ru(?6-C10H8)(?4-1,5-COD)] (1), readily reacts with 1,3-dienes in the presence of a ligand (L) to produce complexes [Ru(?4-cisoid-1,3-diene)(?4-1,5-COD)(L)] [1,3-diene = butadiene, 2,3-dimethylbutadiene, isoprene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-cyclohexadiene; L = MeCN, tBuCN, PhCN, NCC6H4CN, CO, tBuNC, pyridine, P(OMe)3, P(OPh)3, PMe3, PEt3, PPh3, PCy3]. The single-crystal X-ray structures of [Ru(?4-cisoid-1,3-butadiene)(?4-1,5-COD)(MeCN)] (2a) and [Ru{?4-(E)-cisoid-1.3-pentadiene}(?4-1,5-COD)(PPh3)}] (E-5l) show the expected, approximately square pyramidal geometry about the metal atom, with the auxiliary ligand occupying the axial site. [Ru{?4-(Z)-cisoid-1,3-pentadiene}(?4-1,5-COD)(PPh3)] (Z-5l) irreversibly isomerises to E-5l in benzene-d6 at 30 °C, the reaction obeying a first-order rate law [k = (2.89 ± 0.06) × 10?4 s?1]. This reaction is significantly retarded by addition of PPh3 suggesting that a vacant site is required for the E/Z isomerisation.
Graphical abstract
Graphical abstractHighlights
The naphthalene complex of zerovalent ruthenium, [Ru(?6-C10H8)(?4-1,5-COD)] (1), readily reacts with 1,3-dienes in the presence of a ligand (L) to produce complexes [Ru(?4-cisoid-1,3-diene)(?4-1,5-COD)(L)].? A series of Ru(?4-cisoid-conjugated diene)(1,5-COD)L have been prepared. ? The 1,5-hydrogen shift reaction takes place at the endo-methyl group in the coordinated conjugated diene ligand. ? Z to E isomerisation of 1,3-pentadiene has occurred via 16e species.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volumes 708–709 Ashok K.S. Chauhan, Swami N. Bharti, Ramesh C. Srivastava, Ray J. Butcher, Andrew Duthie Chlorotelluration of terminal acetylenes, RCHCH (R = Ph, 1; 4-MeC6H4, 2; t-Bu, 3) with aryltellurium trichlorides and TeCl4 in refluxing toluene affords (2-chloro-2-organylvinyl)tellurium(IV) dichlorides, Ar[R(Cl)CCH]TeCl2 (Ar = 1-C10H7, 1Aa–3Aa; 2,4,6-Me3C6H2, 1Ba–3Ba; 4-MeOC6H4, 1Ca) and [t-Bu(Cl)CCH]2TeCl2, 3a respectively. These Te(IV) derivatives on reduction with Na2S2O5 give the corresponding vinyltellurides as oils, except (2,4,6-Me3C6H2)[Ph(Cl)CCH]Te (1B) which is a crystalline solid. The dibromides (1Ab–3Ab, 1Bb–3Bb, 3b) and diiodides (1Ac–3Ac, 1Bc–3Bc, 1Cc) were obtained by the oxidative addition of dihalogens to the tellurides. The stereochemistry of the products has been established with the help of X-ray diffraction studies of 1Aa, 1Ba, 1Bc, 1Cc, 3Aa, 3a and 1B. Intramolecular Te?Cl attractive interactions appear to favor the (Z) conformation adopted by the 2-chloro-2-organylvinyltellurium group irrespective of the steric demand of the aryl ligand of the Te(IV) electrophile and the terminal acetylene substituent. The intermolecular Te?X secondary bonding interactions give rise to dimeric units in the lattices of 1-naphthyl- and anisyltellurium(IV) derivatives, but are absent among the mesityl analogues, consistent with the larger steric requirement of the latter ligand.
Graphical abstract
Graphical abstractHighlights
The products of chlorotelluration of terminal acetylenes in toluene adopt (Z) conformation irrespective of the steric demand of the substituent R or Ar.? Terminal acetylenes insert into TeIV–Cl bond to give vinyltellurium(IV) dichlorides. ? The vinyl group adopts Z-conformation irrespective of the bulky aryl group at Te. ? Retention of conformation on exchange or removal of the halo ligands. ? Intramolecular Te?Cl interaction favors the Z conformation of the vinyl group. ? Steric bulk of the aryl ligands affects the self assembly via Te?Cl interactions.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volumes 708–709 ?rfan Acar, Zekeriya B?y?kl?o?lu, Mahmut Durmu?, Halit Kantekin In this study, the novel peripherally and non-peripherally tetra-substituted zinc(II) phthalocyanines were synthesized for the first time by cyclotetramerization reactions of corresponding four different phthalonitriles. All of these new zinc phthalocyanines were characterized by the spectral data (IR, 1H NMR, 13C NMR, UV–Vis and mass spectroscopies) as well as elemental analysis. These new zinc(II) phthalocyanines showed excellent solubility in many organic solvents. Surprisingly, the non-peripherally substituted zinc (II) phthalocyanine complexes (9 and 10) formed J-aggregates in non-coordinating solvents such as chloroform, dichloromethane and toluene. The formation of the J-aggregation was proved by UV–Vis and MALDI-TOF mass spectra of these complexes. The photophysical and photochemical properties of zinc phthalocyanine complexes were also investigated in DMSO. The investigation of the photophysical and photochemical properties of photosensitizers is very useful for photodynamic therapy (PDT) applications.
Graphical abstract
Graphical abstractHighlights
The novel peripherally and non-peripherally tetra-substituted zinc(II) phthalocyanines were synthesized for the first time by cyclotetramerization reactions of corresponding four different phthalonitrile. These new zinc(II) phthalocyanines showed excellent solubility in many organic solvents. The photophysical and photochemical properties of zinc phthalocyanine complexes were investigated in DMSO.? Synthesis and characterization of peripherally and non-peripherally tetra-substituted zinc(II) phthalocyanines. ? Photophysical and photochemical properties in DMSO solution. ? Photodynamic therapy studies.
Publication year: 2012 Source:Journal of Organometallic Chemistry, Volumes 708–709 Petr Švec, Roman Olejník, Zde?ka Pad?lková, Aleš R?ži?ka, Laurent Plasseraud C,N-chelated tri- and diorganotin(IV) halides react with 1 or 2molequiv of silver trifluoromethanesulfonate (triflate, AgOTf, OTf=OSO2CF3?) to give corresponding C,N-chelated organotin(IV) triflates. The triorganotin(IV) triflates of general formula LCNR2SnOTf (R=n-Bu (1), Ph (2)) are presumably more stable towards hydrolysis than the diorganotin(IV) triflates LCNRSn(OTf)2 (R=n-Bu (3), Ph (4)). All prepared organotin(IV) triflates bearing the LCN ligand (where LCN is 2-(N,N-dimethylaminomethyl)phenyl-) were characterized by multinuclear NMR spectroscopy and elemental analysis. In addition, the structure of 3 was determined by the X-ray diffraction analysis. The catalytic activity of 1, 2 and 3 in the direct synthesis of dimethyl carbonate (DMC) from CO2 and methanol was investigated showing promising yield of DMC in the case of reaction promoted by 1.
Graphical abstract
Graphical abstractHighlights
C,N-chelated tri- and diorganotin(IV) trifluoromethanesulfonates were prepared and structurally characterized by XRD and NMR techniques. One of compounds shows promising activity in synthesis of dimethyl carbonate from CO2 and methanol.? C,N-chelated tri- and diorganotin(IV) trifluoromethanesulfonates were prepared. ? Structure was investigated by XRD and NMR techniques. ? Activity in synthesis of dimethyl carbonate from CO2 and methanol was tested.
Posted on 27 May 2012 | 1:18 am
Sonstige Hinweise:
Seiteninfo:
Die Urheberrechte sowie die Verantwortung fuer den Inhalt der verlinkten Artikel hat der in der Quelle genannte Anbieter.
Sie möchten Ihre überwiegend mit fachlichen Inhalten zur Chemie, Biochemie etc. ausgestattete Internetseite hier aufgeführt sehen: eMail genügt! Nach Prüfung des Inhalts Ihrer
Chemieseite entscheiden wir über eine eventuelle Aufnahme (kostenlos, ohne Bedingungen). Für einfache Einträge nutzen Sie bitte das Registrierungsformular!
