Crystallization of cesium complex containing bis(2-propyloxy)calix[4]crown-6 and bis[(trifluoromethyl)sulfonyl]imide

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Taoxiang Sun, Zheming Wang, Xinghai Shen

A complex of Cs⁺ with the calixcrown bis(2-propyloxy)calix[4]crown-6 (BPC6) and bis[(trifluoromethyl)sulfonyl]imide (NTf2 ^?), an anion of ionic liquid (IL), was crystallized in the interface region between n-octanol and water. The compound was characterized by single crystal X-ray diffraction, ESI-MS, FT-IR, TGA and PXRD. Cs⁺ is coordinated with BPC6 by both the six oxygen atoms of the crown and the cation–? interactions, and with the anion NTf2 ^? via one oxygen atom of the sulfonyl group. This single crystal explains the good extraction ability of BPC6 to Cs⁺ and reflects a coordinating interaction of NTf2 ^? with the deficient complex [Cs·BPC6]⁺ during the extraction with an IL as diluent.

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Posted on 26 May 2012 | 4:34 am

Prelim v-xii contents (synopsis and pictogram)

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Posted on 26 May 2012 | 4:34 am

The structure and properties of a 3D pillared-layered metal organic framework Cu(II)-diphosphonate

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Xiao-Min Zhao, Kui-Rong Ma, Yu Zhang, Xiao-Jing Yang, Ming-Hui Cong

By introducing the second bridging ligand, 4,4?-bipyridyl (4,4?-bipy), the first 3D example of a Cu(II)-diphosphonate-4,4?-bipy metal organic framework (MOF), [Cu3(L)(4,4-bipy)(OH)2] 1 (H4L=H2O3P(C6H4)2PO3H2) was hydrothermally obtained and characterized through powder X-ray diffraction, elemental analysis, IR, and TG-DSC. Single-crystal X-ray diffraction revealed that compound 1 has a 3D MOF structure which is created by a 2D inorganic layer [Cu3O6P2] n through 4,4?-bipy and an organic biphenyl moiety of H4L linkages. In the structure, an inorganic layer and two organic pillars were alternately arranged. The results of fluorescence measurements revealed two decayed emission bands centered at 442 and 374nm (? ex =236nm) may be caused by the intraligand ?^?–? emission states of the 4,4?-bipy ligand (? em =442 and 381.5nm, ? ex =236nm). Magnetism analysis indicated antiferromagnetic interactions between the metal centers within the 1D magnetic chain {–Cu(1)–Cu(2)–Cu(2)–Cu(1)–} n .

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Posted on 26 May 2012 | 4:34 am

Chalcogen–chalcogen interactions in trichalcogenaferrocenophanes. Crystal structure of 2-selena-1,3-ditellura[3]ferrocenophane [Fe(C5H4Te)2Se]

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Minna M. Karjalainen, Raija Oilunkaniemi, Risto S. Laitinen

The preparation, ⁷⁷Se and ¹²⁵Te NMR spectroscopic characterization, and crystal structure of 2-selena-1,3-ditellura[3]ferrocenophane [Fe(C5H4Te)2Se] have been reported. The complex crystallizes in a triclinic crystal system with the space group $P\overline{1}$. The comparison of the X-ray structure of [Fe(C5H4Te)2Se] with those of other members in the [Fe(C5H4E)2E?] (E, E?=S, Se, Te) series shows that the intermolecular chalcogen–chalcogen interactions are weak in case of sulfur or selenium, but become significant for interactions involving tellurium. This is consistent with the concept of secondary bonding interactions between the atoms of heavy main group elements.

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Posted on 26 May 2012 | 4:34 am

Two zinc(II) and cadmium(II) complexes based on the V-shaped ligand 2,6-bis(2-benzimidazolyl)pyridine: Synthesis, crystal structure, DNA-binding properties and antioxidant activities

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Hui-Lu Wu, Jing-Kun Yuan, Xing-Cai Huang, Fan Kou, Bin Liu, Fei Jia, Kai-Tong Wang, Ying Bai

Two zinc(II) and cadmium(II) complexes based on a V-shaped ligand 2,6-bis(2-benzimidazolyl)pyridine (bbp) have been synthesized and characterized by elemental analysis, molar conductivities, IR, UV–Vis spectra and X-ray single crystal diffraction. Zn(II) and Cd(II) ions are six-coordinated in the structures of [Zn(bbp)2](pic)2·2DMF (1) and [Cd(bbp)2](pic)2·2DMF (2) (pic=picrate), and forming a distorted octahedron. The DNA-binding properties of the complexes were investigated by spectrophotometric methods and viscosity measurements. The experimental results suggest the complexes bind to DNA in an intercalation mode, and DNA-binding affinity of the Zn(II) complex is stronger than that of the Cd(II) complex owning to the different V-shaped angle (?V). Antioxidant assay in vitro shows that both two complexes possess significant hydroxyl radical scavenging activity, and the Zn(II) complex also reveal potent superoxide radical scavenging activity.

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Posted on 26 May 2012 | 4:34 am

Construction and property investigation of inorganic–organic hybrid materials based on metal–salens and Keggin polyoxometalates

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Xing Meng, Hai-Ning Wang, Xin-Long Wang, Guang-Sheng Yang, Shuang Wang, Kui-Zhan Shao, Zhong-Min Su

Four hybrid materials based on the Keggin polyanions and metal–salens, namely, [Mn(salen)(CH3OH)2]4[SiW12O40] (1), [Mn(salen)(H2O)]2[Mn(salen)(H2O)][PW12O40] (2), [NH(CH2CH3)3]2[Mn(salen)(CH3OH)]2[SiW12O40]·2CH3OH (3), and [(Cu(salen))2Cu(H2O)]2[SiW12O40] (4) (H2salen=N,N?-ethylenebis(salicylideneimine)) have been successfully synthesized. All the compounds are characterized by X-ray single-crystal diffractions, elemental analyses, IR spectra, and thermogravimetric analyses (TGA). Crystal structure analysis reveals that compound 1 exhibits a supramolecular structure containing one Keggin-type [SiW12O40]^4? heteropolyanion and four Mn^III–salen units. In compound 2, the [PW12O40]^3? polyoxoanions and Mn^III–salen complex cations are regularly arranged along the c-axis showing an alternating packing arrangement of anionic and cationic layers. While in compound 3, the polyoxoanion [SiW12O40]^4? is covalently decorated by two [Mn(salen)(CH3OH)]⁺ fragments via two terminal oxygen atoms in the opposite sites, giving birth to an unusual Keggin anion supporting transition metal–salen complexes. Compound 4 represents the first example that POM supports trinuclear copper–salen complexes. Photocatalytic experiments of 1–4 indicate that they possess high catalytic activity for photodegradation of RhB under UV irradiation. In addition, the electrochemical behaviors of 1 and 2 are well investigated.

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Posted on 26 May 2012 | 4:34 am

Syntheses, characterization of N-functionalized benzyl zinc, cadmium and manganese (II) compounds

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Bin Jia, Xuehong Wei, Hongbo Tong, Meisu Zhou, Diansheng Liu

Treatment of [LiL·TMEDA] (1) {L =[2-Me2NCH2C6H4CH(SiMe3)]^?} with half equivalent of ZnCl2, CdCl2 or MnCl2 in diethyl ether gave the crystalline compound [ML 2] {M=Zn (2), Cd (3) and Mn (4)}, respectively. Reaction of 1 with one equivalent of ZnCl2 in diethyl ether afforded the crystalline compound [Zn(Cl)L·TMEDA] (5) in good yield. An eight-membered cyclic homoleptic binuclear compound [ZnL?]2 (6) {L?=[(2-Me2NCH2C6H4CH)2SiMe2]^2?} was prepared from the reaction of (2-Me2NCH2C6H4CH2)2SiMe2 (B?) with two equivalents of n-BuLi and one equivalent of ZnCl2. All of the crystalline compounds 1–6 were well characterized by ¹H NMR, ¹³C NMR spectroscopy, elemental analyses and single crystal X-ray crystallography. In addition, moderate activity for the polymerization of rac-lactide to poly(lactic acid) (PLA) was found in compounds 2 and 5, and all the resulting polylactides are most predominantly heterotactic-rich.

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Posted on 26 May 2012 | 4:34 am

Molecular complex from two different binuclear copper 1,4,5,8-naphthalenetetracarboxylate complexes

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Devendra Singh, Jubaraj B. Baruah

Two different binuclear copper complexes [Cu2(Phen)4(NTC)] (A) and [Cu2(Phen)2(NTC)(H2O)4] (B) form a stable molecular complex having a composition [Cu4(Phen)6(NTC)2(H2O)4·22H2O] (1) (where Phen=1,10 phenanthroline and H4NTC=1,4,5,8-naphthalenetetracarboxylic acid). Different ?-interactions as well as intermolecular hydrogen bonding interactions between the two complexes A and B result in the formation of 3D channel like structures of approximate 18×14Å dimension are filled by lattice water molecules. Moreover, 3D network of complex A itself makes the required space in the crystal lattice to accommodate 1D zigzag chains of complex B.

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Posted on 26 May 2012 | 4:34 am

Synthesis, characterization and X-ray studies of new six–seven membered rings [4.5.0] heterobicyclic system of monomeric boronates

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

José María Rivera, Enrique Méndez, Raúl Colorado-Peralta, Susana Rincón, Norberto Farfán, Rosa Santillán

Different tridentate ligands derived from ethanolamines and 2-hydroxyacetophenone, 2-hydroxybenzophenone and salicylaldehyde were reacted with two equivalents of phenylboronic acid to obtain compounds 6a – 6f which are [4.5.0] heterobicyclic systems with a B?O?B structural unit. The boronates were fully characterized and two heterobicyclic [4.5.0] structures have been analyzed by X-ray crystallography, where a series of parameters such as bond distances, bond angles, torsion angles, tetrahedral character at the boron atom and deviation of the boron atom from the mean plane have been evaluated.

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Posted on 26 May 2012 | 4:34 am

Copper(II) complexes of aliphatic tridentate amine/dithioether ligands – Synthesis and molecular structures

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Marc Blomenkemper, Henning Schröder, Tania Pape, F. Ekkehardt Hahn

Three new tridentate ligands (1–3) featuring a central secondary amine linked by ethylene bridges to two thioether donor functions with S-methyl or S-benzyl substituents have been synthesized and reacted with copper(II) chloride or copper(II) nitrate. The resulting complexes of type [CuX2(L)] (L=amine-dithioether ligand) 6, 7, and 9 exhibit a square-pyramidal coordination geometry with the nitrogen and sulfur donor groups of the tridentate ligand occupying three of the basal binding sites at the metal ion. Two chloro (6 and 7) or a nitrato ligand (9) originating from the metal precursor salt complete the coordination sphere of the copper(II) ion. The apical donors are bonded with significantly longer bond distances compared to identical donors in the basal plane. The weakly bound apical chloro ligand of 6 can be abstracted with silver(I) nitrate effecting the formation of the dinuclear complex 10 featuring a nitrato ligand coordinated to two copper(II) centers in a bridging fashion. For all copper(II) complexes the observed Cu–S bond distances are very similar and not significantly influenced by alteration of the alkyl group at the thioether donor function.

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Posted on 26 May 2012 | 4:34 am

Structures and luminescent properties of Tb(III) and Tb(III)–Ni(II) coordination polymers based on pyridyl dicarboxylate

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Jing Huang, Hongmiao Li, Jianyong Zhang, Long Jiang, Cheng-Yong Su

The N,O ligand, namely 5-(pyridin-4-yl)isophthalic acid (LH2), with carboxylic acid groups and pyridyl group separated, prefers to act as a bridging ligand. Its Tb(III) coordination polymer, [TbL(LH)(H2O)2]?·xH2O (1), and heterometallic Tb(III)–Ni(II) coordination polymer, [TbNiL2(LH)(H2O)]?·xH2O (2), have been successfully prepared. Complex 1 exhibits a two-dimensional layered structure with (4,4) network leaving all the pyridyl N-donors uncoordinated, while complex 2 has a three-dimensional structure due to coordination of Ni(II) to part of pyridyl N-donors. Both the complexes were characterized by single-crystal X-ray diffraction, X-ray powder diffraction, FT-IR spectroscopy and thermogravimetry analysis. The ligand is capable of sensitizing the Tb(III) ion, and both the complexes emit characteristic visible green luminescence of Tb(III).

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Posted on 26 May 2012 | 4:34 am

Synthesis, characterization and supramolecular structure of three new Cu(II) and Ni(II) complexes with the potentially bidentate ligand 2-amino-6-methylpyrimidin-4(1H)-one (AMPO)

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

K. Kaabi, M. Zeller, V. Ferretti, P.S. Pereira Silva, C. Ben Nasr

Three binuclear Cu(II) and Ni(II) perchlorate complexes with the potentially bidentate ligand 2-amino-6-methylpyrimidin-4(1H)-one (AMPO) [Cu(AMPO)4][Cu(H2O)5](ClO4)4·6H2O (1), [Cu2(AMPO)4(H2O)3](ClO4)4·½H2O (2) and[Ni(AMPO)4][Ni(H2O)6](ClO4)4·5H2O (3), have been prepared and were characterized by single crystal X-ray diffraction, IR spectroscopy and elemental analysis. Structural and IR data indicate that the ligand is present in its tautomeric form protonated at nitrogen in position one and metal coordinated at position three. The basic coordination pattern of the AMPO coordinated metal cations in all three complexes is square planar by four pyrimidyl nitrogen atoms of four different AMPO ligands. The coordination sphere is augmented by weak M?O interactions between the metal centers and AMPO keto oxygen atoms. Bond valence calculations indicate the M?O interactions to be most pronounced for nickel compound (3), and least for copper complex (2). The structural and geometrical differences between compounds (1) and (3) on the one hand and compound (2) on the other can to a large part be traced back to the lack of available water in the crystallization solvent in (2) which starves the cation not coordinated to AMPO nitrogen atoms of water molecules to saturate its coordination sphere, thus forcing two of the AMPO ligands in (2) to act as a bridging ligands, while the other AMPO ligands in the three structures are mostly monodentate with the coordination mode of the AMPO ligand being completed by weak secondary chelating M?O interactions.

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Posted on 26 May 2012 | 4:34 am

Dinuclear iridium complexes with unsupported Ir–Cl–Ir bridges

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Joseph S. Merola, Trang Le Husebo, Henry E. Selnau

Two unusual dinuclear iridium complexes are reported with unsupported bridging chloride ligands. The first comes from an aqueous solution of H2ClIr(PMe3)3 by the addition of KPF6. The second is formed in the reaction between H(C6H5)ClIr(PMe3)3 and TlPF6 in dichloromethane. Single crystal X-ray structures are provided for both ?-chlorodiiridium complexes.

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Posted on 26 May 2012 | 4:34 am

Direct assembly of a metallodendrimer encompassing seven triruthenium clusters units

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Sergio H. Toma, Jonnatan J. Santos, Sofia Nikolaou, Koiti Araki, Henrique E. Toma

A general strategy for the assembly of dendrimeric metallo-cluster species based on tritopic trinuclear ruthenium acetate complexes is demonstrated. First, a central core consisting of a [Ru3O(CH3COO)6(TPEB)3]PF6 complex (G0), where TPEB is the tripodal 1,3,5-tri-4-pyridyl-1,2-ethenylbenzene ligand, was synthesized and then reacted with the end-capping complex [Ru3O(CH3COO)6(py)2(MeOH)]PF6, thus composing the first generation shell of a dendrimer encompassing twenty-one ruthenium ions (G1). The core and dendrimeric complexes were characterized by elemental analysis, UV–Vis, ¹H NMR, ESI-MS spectrometry and Differential pulse voltammetry. All results were consistent with the structure of that multinuclear cationic dendrimeric species. The isotopologic profile of daughter fragments and the strength of the metal–ligand bonds were carefully investigated providing the fragmentation pathway for the metallo-dendrimer upon ESI-MS dissociation conditions.

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Posted on 26 May 2012 | 4:34 am

Mechanistic studies on the intra-molecular electron transfer in the adduct species of some oxo-centred trinuclear iron(III)/chromium(III) cations and l-ascorbic acid in aqueous acetate buffer

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Mark A.W. Lawrence, Paul T. Maragh, Tara P. Dasgupta

The kinetics of the intra-molecular electron transfer of the adduct of l-ascorbic acid and a series of mixed metal Cr2Fe oxo-centred trinulear complexes, of the general formula [Cr2Fe(?3-O)(?2-RCO2)6(H2O)3]⁺ (where R=H, CH3, CH3CH2 and (CH3)2CH) were investigated spectrophotometrically, in aqueous carboxylate buffer. The reactions were studied over the ranges 2.34?pH?4.45, 25.0? ? ?35.0°C at an ionic strength of 0.50moldm^?3 (NaClO4). The reaction involves an equilibrium step between both triaqua and diaquahydroxo species of the complex cations and l-ascorbic acid, resulting in the formation of an adduct. These equilibrium steps are followed by a slower one-electron oxidation step, corresponding to the reduction of the iron(III) centre(s) which is proceeded by rapid decomposition of the oxo-centred trinuclear core to yield aqueous iron(II), and dinuclear chromium(III). The dinuclear chromium(III) further decomposes by aquation to give an aqueous solution of the metal ions and free ligands.

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Posted on 26 May 2012 | 4:34 am

High-yield postsynthetic modification of MOF with organic–metal precursors

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Jongsik Kim, Dong Ok Kim, Dong Wook Kim, Jeasung Park, Mi Sun Jung

The specific yield of postsynthetic modification for modified IRMOF-16 (HCC-1), synthesized using 1,4-di(4-carboxy-2-hydroxyphenyl)benzene as organic ligand and Zn(NO3)2·6H2O as metal source, respectively, has been investigated with the variation of its BET surface area, reaction time and organic–metal precursor. Two kinds of HCC-1 having different values of BET surface area (HCC-1H: 3000m²/g and HCC-1L: 2000m²/g) were prepared via solvothermal method for the study of effect of BET surface area, whereas isopropoxytitanatrane and tetrabenzyl titanium were adopted as organic–metal precursors It was observed that even if the specific yields of postsynthetic modification for both organic–metal precursors increased with the value of BET surface area of HCC-1, isopropoxytitanatrane showed relatively higher values than those of tetrabenzyl titanium during the entire range of reaction. These observations led us to conclude that HCC-1H has higher specific number of –OH groups, active sites for postsynthetic modification, and tetrabenzyl titanium experiences more difficulty in diffusing deep into HCC-1 due to its relatively larger molecular size. For the effect of reaction time, while it increased slowly with the reaction time until 48h and then leveled off for HCC-1H, it increased during the entire range of reaction time for HCC-1L.

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Posted on 26 May 2012 | 4:34 am

Oxidation states and redox behavior of ruthenium ammine complexes with redox-active dioxolene ligands

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Isao Ando, Takemasa Fukuishi, Kikujiro Ujimoto, Hirondo Kurihara

Synthesis of ruthenium-dioxolene complexes with ammines [Ru(NH3)4(diox-R)] ^{n +}, where diox-R is a dioxolene with substituent R=3,5-di-tert-butyl, H, tetrachloro, and 4-nitro, was carried out. These complexes were characterized by spectroscopy, magnetic susceptibility measurements, and cyclic voltammetry. The oxidation states of ruthenium and the redox-active dioxolene ligand in the complexes varied depending on the nature of the dioxolene substituents. [Ru(NH3)4(diox-R)] ^{n +} (R=3,5-di-tert-butyl and H) has a divalent ruthenium and dioxolene in the quinone oxidation state with a minor amount of the complex in Ru(III)-semiquinonato oxidation state. The complexes exhibited valence tautomerism depending on the donor number of solvents. However, [Ru(NH3)4(diox-R)] ^{n +} (R=tetrachloro and 4-nitro) has a trivalent ruthenium and dioxolene in the catecholate oxidation state. Electrochemical and spectroelectrochemical investigation of these complexes revealed that their electrochemical behavior depended on not only the oxidation state of the prepared complex but also the nature of the dioxolene substituent in the complex. Their redox reaction was found to proceed by the EC mechanism involving valence tautomerism.

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Posted on 26 May 2012 | 4:34 am

A dipicolylamine-appended cyclometalated iridium(III) complex: Synthesis, characterization and metal ions recognition

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Xianghong Li, Huajun Lan, Yuanbing Chen, Kangle Lv, Aiqing Zhang, Tao Huang

A new phosphorescent dye (complex 1) containing iridium cyclometalated complex as fluorophore and di(2-picolyl)amine (DPA), connected to the 4,4?-positions of the bipyridine unit through >CO, as recognition group was synthesized and characterized. The UV–Vis absorption and luminescence properties of 1 were investigated with heavy-metal ions as well as Zn²⁺, Cd²⁺, Co²⁺, Ni²⁺, Ag⁺, Fe²⁺, Mn²⁺, Hg²⁺, Pb²⁺ and Cu²⁺. The emission intensities of complex 1 were strongly quenched by the addition of Cu²⁺, Zn²⁺ and Hg²⁺. The binding constants (K s) and stoichiometry of complex 1 were calculated from luminescence titration data, with values of K s =3.09×10⁵ M^?1 (Cu²⁺), 5.75×10⁴ M^?1 (Zn²⁺) and 1.90×10⁴ M^?1 (Hg²⁺), respectively. Therefore, 1 exhibited high selectivity and efficient signaling behavior to Cu²⁺ over Zn(II), Hg(II) and other metal ions.

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Posted on 26 May 2012 | 4:34 am

Synthesis, characterization and crystal structure of square-pyramidal copper(II) complexes with pyridoxylidene aminoguanidine

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Mirjana M. Lalovi?, Ljiljana S. Vojinovi?-Ješi?, Ljiljana S. Jovanovi?, Vukadin M. Leovac, Valerija I. ?ešljevi?, Vladimir Divjakovi?

The synthesis of pyridoxylidene aminoguanidine hydrogenchloride hydrogennitrate (PLAG·HCl·HNO3), as well as the synthesis, physico-chemical characterization and crystal structure of two Cu(II) complexes with this ligand, of the formulas [Cu(PLAG)py(NO3)]NO3 (1) and [{Cu(PLAG)py}2](NO3)4 (2) are described. The X-ray analysis showed that Cu(II) is situated in a distorted square-pyramidal environment. In 1 PLAG is coordinated as usually, through the oxygen atom of the deprotonated phenolic OH group and nitrogen atoms of the azomethine and imino groups of the aminoguanidine fragment. In particular, in the centrosymmetric dimeric complex 2, besides the mentioned ligators, the oxygen atom of the hydroxymethyl group of the pyridoxal moiety is involved in coordination as the bridging ligator, connecting the subunits. This is the first dimeric complex with this ligand where the tetradentate coordination mode is observed. Voltammetric characteristics of the ligand and complexes 1 and 2 as well as [Cu(PLAG)Cl2] were investigated and reaction pathways including monomer–dimer equilibria established.

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Posted on 26 May 2012 | 4:34 am

Synthesis, structure and oxidation of alkynes using a ?-oxo diiron complex with the ligand bis (1-(pyridin-2-ylmethyl)-benzimidazol-2-yl methyl) ether

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Raghvi Khattar, M.S. Hundal, Pavan Mathur

New ligand bis (1-(pyridin-2-ylmethyl)-benzimidazol-2-ylmethyl ether and its ?-oxo diferric complex has been synthesized and characterized. The dimeric [LClFe–O–FeCl3] has been characterized crystallographically, and shows that iron atoms occupy inequivalent coordination sites. One of the Fe (III) atom is coordinated by two benzimidazole nitrogens, one ether oxygen and bridging oxide oxygen, forming the equatorial plane while one Cl^? ion and the oxygen atom of a DMF molecule occupy the axial fifth and the sixth coordination positions. The second Fe (III) is tetrahedrally coordinated by three Cl^? ions and the bridging oxide oxygen O. The bridging oxide anion is unsymmerically coordinated to the two Iron (III) atoms. Oxidation of aromatic alkynes was investigated using this complex as catalyst with small amount of tert-butyl hydroperoxide (TBHP) and Hydrogen peroxide (H2O2) as an alternate source of oxygen. Isolated products were characterized by GC-Mass. Solvent, temperature, Stoichiometry and oxidant variation are studied and reaction conditions have been optimized. Dicarbonyl and ?,?-acetylenic ketone are the major product and depend on the nature of the alkyne employed.

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Posted on 26 May 2012 | 4:34 am

Anion mediated diversity in the H-bonded assembly of a series of heteronuclear copper(II)/sodium(I) compounds

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Prasanta Bhowmik, Subrata Jana, Partha Pratim Jana, Klaus Harms, Shouvik Chattopadhyay

Three heteronuclear Cu(II)/Na(I) compounds, [Cu(vanpn)Na(NO3)(H2O)] (1), [Cu(vanpn)Na(N3)(CH3OH)] (2) and [Cu(vanpn)Na(NCS)(H2O)] (3) where H2vanpn= N,N?-(1,3-propylene)-bis(3-methoxysalicylideneimine), a well known compartmental Schiff base ligand, have been prepared and characterized by elemental analysis, IR and UV–Vis spectroscopy and single crystal X-ray diffraction studies. Compound 1 crystallises in monoclinic space group P21/n, compound 2 in triclinic $P\overline{1}$ and compound 3 in orthorhombic space group Pbca. In all the compounds, Cu atoms assume distorted square planar geometries whereas Na atoms exhibit distorted octahedral geometry. In compound 1, the nitrate ion is coordinated as a chelating ligand and essentially both the O atoms of the nitrate occupy one axial site. Variation of the counter anions leads to considerable change in the H-bonded supramolecular structures of the compounds. Compound 1 forms a dimer, compound 2 constitutes a chain and compound 3 forms a helix. Electrochemical electron transfer study reveals Cu(II)Cu(I) reduction in acetonitrile solution.

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Posted on 26 May 2012 | 4:34 am

Prelim iii Editorial board

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Posted on 26 May 2012 | 4:34 am

Molecular structures and spectroscopic studies of cationic metal–methylisonicotinate complexes with saccharinate counterions

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Esat Bozkurt, Hüseyin Ayaz, ?brahim Uçar, Bünyamin Karabulut

The crystal structures of [Co(methylisonicotinate)2(H2O)4](saccharinate)2 and [Ni(methylisonicotinate)2(H2O)4](saccharinate)2 complexes have been synthesized and characterized by spectroscopic, EPR and X-ray diffraction techniques. The XRD data have indicated that both the Co(II) and Ni(II) ions lie on an inversion center, having distorted octahedral coordination through four aqua ligands composing the basal plane and two trans nitrogen atoms from the monodentate methylisonicotinate ligands occupying the axial sites. The EPR spectra of these complexes have been studied in the temperature range between 113 and 300K in three mutually perpendicular planes. The EPR spectral results were discussed and compared in relation with the other compounds containing saccharinate and methylisonicotinate complexes.

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Posted on 26 May 2012 | 4:34 am

Synthesis, characterization of Cu(II) and Zn(II) complexes of proline-glycine and proline-leucine tetrapeptides: In vitro DNA binding and cleavage studies

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Farukh Arjmand, Shazia Parveen, D.K. Mohapatra

New Cu(II) and Zn(II)-based peptide solid complexes 1–4 were designed by de novo synthetic strategy from tetrapeptide ligands, Pro-Gly-Pro-Gly, L ¹/Pro-Leu-Pro-Leu, L ² and thoroughly characterized by various spectroscopic techniques. To confirm the stability of peptide complexes in solution, solution stability studies of 1 and 3 over a pH range 2–12 were carried out which revealed no change in absorption or intensity of bands. In vitro DNA binding studies employing various optical techniques were carried out to examine the propensity of complexes towards CT DNA. The results of corroborative experiments reveal that the complexes avidly bind to CT DNA via groove binding, with highest K b values for 1 indicative of strong binding propensity as compared to ligands and 2–4. To compare the binding affinity for nucleotides, UV–Vis titrations of 1 and 2 with 5?-GMP and 5?-TMP were carried out; further validated by ¹H and ³¹P NMR. The supercoiled pBR322 DNA nuclease activity 1 and 2, demonstrated that both the complexes were capable of cleaving DNA but with striking differences in their nuclease activity; Cu(II) complex cleaved DNA through oxidative cleavage while Zn(II) complex followed hydrolytic cleavage pathway.

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Posted on 26 May 2012 | 4:34 am

Solvent-regulated assembly of three new polymeric CdII 5-fluoroisophthalates with mono-, di-, and trinuclear nodes: Syntheses, structures, and luminescent properties

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Sheng-Chun Chen, Rui-Rui Qin, Zhi-Hui Zhang, Jing Qin, Hai-Bo Gao, Fu-An Sun, Ming-Yang He, Qun Chen

Three new polymeric Cd^II complexes, [Cd(fip)(MeOH)3] n (1), {[Cd2(fip)2(H2O)5]·4H2O} n (2), and {[Cd3(fip)4(H2O)2][Cd(DMF)2(H2O)4]·2DMF} n (3), have been prepared from the reactions of Cd^II acetate with a rigid fluorinated ligand 5-fluoroisophthalic acid (H2fip) under different solvent systems. Complex 1 shows a 1D zigzag coordination chain with a mononuclear [Cd(COO)(MeOH)3] unit, and complex 2 displays a 2D neutral layered structure containing a dinuclear [Cd2(COO)4(H2O)5] entity, while complex 3 presents a 2D anionic coordination network with the linear trinuclear [Cd3(COO)8(H2O)2] clusters as the linking nodes. The results clearly suggest that the judicious choice of solvent systems does play a critical role in the construction of coordination frameworks with distinct connectivity and dimensionality. The spectroscopic, thermal, and luminescent properties of 1–3 have also been investigated.

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Posted on 26 May 2012 | 4:34 am

Sulfide oxidation catalyzed vanadyl complexes of N-salicylidene ?-amino acids at low catalyst loading

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Qingle Zeng, Wen Weng, Xinghua Xue

Sulfoxides are extensively used in chemical and pharmaceutical industries. Various catalytically synthetic methods were reported, but in common 1–10(mol)% catalyst loading were demanded. Sulfide oxidation catalyzed by vanadyl complexes of N-salicylidene ?-amino acids with catalyst loading as low as 0.03(mol)% gave high yields at room temperature with aqueous hydrogen peroxide as an oxidant, which is a green, solvent-free, energy-saving and easy-operated protocol. In contrast, vanadyl complexes of N-salicylidene amino alcohols could not, even at 0.1(mol)%. The possible reason is that the stronger acidity of N-salicylidene ?-amino acids makes their vanadyl complexes stable to aqueous hydrogen peroxide. This rule may be used in designing other high efficient catalysts, especially with aqueous hydrogen peroxide as an oxidant.

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Posted on 26 May 2012 | 4:34 am

Synthesis, structure and magnetic properties of phosphate-bridged polynuclear copper(II) complexes

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Hong-Lin Zhu, Ling Jin, De-Yi Cheng, Yue-Qing Zheng

Three new phosphate-bridged copper(II) complexes, [Cu4(H2O)2(phen)4(?4-PO4)2(?2-O)]·11H2O (1), [Cu4(bpy)4(?4-PO4)2(?2-Cl)2]·18H2O (2) and [Cu2(bpp)4(H2PO4)2](HPO4)·H2O (3) (phen=1,10-phenanthroline, bpy=2,2-bipydine and bpp=1,3-bis(4-pyridyl)-propane), have been synthesized under ambient conditions. The tetranuclear Cu(II) butterfly cores in 1 are aggregated to 2D supramolecular layer via intermolecular ?–? stacking interactions. In 2, the dinuclear copper units are bridged by the phosphate and Cl^? anion to generate centrosymmetric tetranuclear complex molecules [Cu4(bpy)4(?4-PO4)2(?2-Cl)2], which are aggregated to 2D layers via ?–? stacking interactions. The Cu atoms in 3 are interlinked by a pair of bpp ligands to generate 2D (4,4) network which is through twofold ‘2D parallel/2D parallel’ mode inclined interpenetration to induce 3D motifs. The variable temperature magnetic characterizations suggest antiferromagnetic coupling interactions with J =?9.38 and ?28.03cm^?1 for 1, J =?2.41cm^?1 for 2, respectively.

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Posted on 26 May 2012 | 4:34 am

Open chains versus closed rings: Comparison of binuclear butadiene cobalt carbonyls with cyclic hydrocarbon analogs

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Qunchao Fan, Hao Feng, Weiguo Sun, Yi Zeng, Yaoming Xie, R. Bruce King

The reaction of Co2(CO)8 with butadiene has long been known to give the binuclear (C4H6)2Co2(CO)2(?-CO)2. In addition, other (diene)2Co2(CO)2(?-CO)2 derivatives have been synthesized. In this connection the binuclear butadiene cobalt carbonyls (C4H6)2Co2(CO) n (n =4, 3, 2, 1) have now been investigated by density functional theory. For (C4H6)2Co2(CO)4 several doubly carbonyl bridged stereoisomers were found differing only in the arrangements of the butadiene ligands and with predicted Co–Co single bond distances in the range 2.53–2.61Å. A similar multiplicity of stereoisomers is not possible for the corresponding cyclobutadiene derivative (C4H4)2Co2(CO)4. The lone unbridged (C4H6)2Co2(CO)4 structure lies ?13kcal/mol above the lowest energy doubly bridged isomer with a significantly longer Co–Co distance of 2.74Å. For (C4H6)2Co2(CO)3 the lowest energy structures are doubly carbonyl bridged structures with CoCo double bond distances in the range 2.45–2.51Å. However, triply carbonyl bridged (C4H6)2Co2(?-CO)3 structures with significantly shorter CoCo distances of 2.24–2.30Å are also found. For (C4H6)2Co2(CO)2 several structures with bridging butadiene ligands and terminal carbonyl groups are energetically competitive with those with bridging carbonyl groups and terminal butadiene ligands, unlike the corresponding cyclobutadiene complexes. The lowest energy singlet (C4H6)2Co2(CO) has a two-electron donor bridging carbonyl group and an extremely short Co–Co distance of 2.13Å suggesting the formal quadruple bond required to give each cobalt atom the favored 18-electron configuration. This differs from the cyclobutadiene analog (C4H4)2Co2(CO) in which the bridging carbonyl group is a four-electron donor ?²-?-CO group and the cobalt-cobalt distance is much longer at ?2.5Å.

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Posted on 26 May 2012 | 4:34 am

Spectroscopic and electrochemical properties of mononuclear Mn(III) complex and of binuclear di-?-oxo bridged Mn(III) and Mn(IV) complex with isocyclam

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

D. Tomczyk, G. Andrijewski, L. Nowak, P. Urbaniak, D. Sroczy?ski

trans-[Mn^III isocyclamCl2]Cl·2H2O and [Mn^IIIMn^IV(?-O)2 isocyclam 2](ClO4)3·2H2O (isocyclam =1,4,7,11-tetraazacyclotetradecane) were synthesised and analysed. Coordination geometry of both of these complexes was estimated with IR and electronic spectroscopy as trans-pseudo-octahedral for the first one and cis-pseudo-octahedral with two oxygen bridges for the other one. Magnetic properties of complexes were characterised as high-spin and antiferromagnetic, respectively. Cyclic voltammetry measurements of neutral aqueous solutions showed the possibility of oxidation of both complexes to [Mn^IVMn^IV(?-O)2 isocyclam 2]⁴⁺. Mechanism of oxidation of mononuclear complex including its isomerisation process was proposed. Formal potentials and transfer coefficients were calculated.

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Posted on 26 May 2012 | 4:34 am

Synthesis and characterization of trivalent tribridged dicobalt complexes incorporating alkoxide, aqua-hydroxide, acetate and phosphate ligating groups

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Gnana S. Siluvai, Babu Vargheese, Narasimha N. Murthy

Two dinuclear trivalent cobalt complexes viz. [Co2(P1–O)(AcO)(H2O)(OH)](ClO4)3, (1) and [Co2(P1–O)(AcO)(DPP)](ClO4)3, (2), where $\text{P}1''–''\text{O}=N\text{,}{N}^{?}\text{,}{N}^{?}\text{,}{N}^{?}\text{-tetrakis}(2\text{-methylpyridyl})\text{-}2\text{-hydroxy-}1\text{,}3\text{-diaminopropane}$, AcO=acetate and DPP=diphenyl phosphate, containing three intervening bridges between the two cobalt(III) centers have been synthesized and characterized. Complex 1 was formed by the reaction of a divalent dicobalt complex [Co2(P1–O)(AcO)](ClO4)2 with hydrogen peroxide. The X-ray crystallographic analysis shows that 1 contains a ?-acetato–?-aqua-hydroxo–?-alkoxo–dicobalt(III) core comprised of two distorted octahedral Co sites. Complex 2 also has two six-coordinated cobalt(III) ions with N3O3 set of donor atoms derived from the binucleating ligand, P1–OH and the oxygen atoms of acetate (OAc) and diphenyl phosphate (DPP) groups, rendering octahedral geometry around each cobalt(III). The distance between the two cobalt(III) sites in the complexes 1 and 2 is 3.38 and 3.35Å, respectively that are close to the M…M distance in dinuclear metalloenzymes. Complexes 1 and 2 are also characterized by conventional spectroscopic methods such as UV–Vis, FT-IR, ¹H, ¹³C and ³¹P NMR and ESI-MS spectroscopic methods.

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Posted on 26 May 2012 | 4:34 am

Dicyanamido-metal(II) complexes. Part 6: 1D polymeric copper(II) complexes bridging by dicyanamide. Effect of copper(II) salt on the nature of the polymeric product

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Salah S. Massoud, Marcie M. Lemieux, Lucie Le Quan, Ramon Vicente, Jörg H. Albering, Franz A. Mautner

The complexes {[Cu(L)(?1,5-dca)](ClO4)} n (1, L=bepza; 2, L=bedmpza) and [Cu(L)(?1,5-dca)(dca)] n (3, L=bepza; 4, L=bedmpza), where dca=dicyanamide anion, bepza=bis[2-(1-pyrazolyl)ethyl)]amine and bedmpza=bis[2-(di-2,5-dimethyl-1-pyrazolyl)ethyl)]amine, were synthesized and characterized by spectroscopic techniques. The crystal structures of complexes 1 and 3 confirmed their polymeric 1D chain nature through the two terminal nitrile groups of the ?1,5-bridging dicyanamido ligand. The magnetic susceptibility measurements of the two complexes 1 and 3 revealed the occurrence of very weak antiferromagnetic coupling with J values of ?0.17 and ?0.03cm^?1, respectively.

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Posted on 26 May 2012 | 4:34 am

4,5-Bis(methylthio)-1,3-dithiole-2-thione, a versatile sulphur-rich building block for the self-assembly of Cu(I) and Ag(I) coordination polymers: Dithioether versus thiocarbonyl bonding

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Aurélien Hameau, Fabrice Guyon, Abderrahim Khatyr, Michael Knorr, Carsten Strohmann

Reported herein is the investigation of the coordination chemistry of the ligand 4,5-bis(methylthio)-1,3-dithiole-2-thione (L) towards several Ag(I) salts (AgNO3, AgClO4, AgCF3SO3 and Ag-p-MeC6H4SO3) and Cu(I) (CuBr and [Cu(MeCN)4](PF6)). Six polymeric complexes have been characterised by single-crystal X-ray diffraction, FT-IR spectra and elemental analysis. This work evidences five different coordination modes for L. The sulphur-rich ligand always coordinates via the thiocarbonyl group. Additional metal–thioether interactions give rise in some cases to a polymeric structure such as in the molecular wire-like 1D polymer {[Cu(?2-L)(MeCN)](PF6)} n . Supramolecular structures arise from a combination of metal···ligand and short S···S Van der Waals interactions. Furthermore, the emission spectra of the strongly luminescent 2D coordination polymer [Ag(?2-L){?2-(p-CH3C6H4SO3)}] n have been recorded.

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Posted on 26 May 2012 | 4:34 am

Reactions of N-heterocyclic ligands with substitutionally labile organometallic complexes, [(?5-C5R5)Fe(CO)2E]BF4

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Cyprian M. M’thiruaine, Holger B. Friedrich, Evans O. Changamu, Muhammad D. Bala

The ether complexes [Cp(CO)2Fe(OEt2)]BF4 (Cp=?⁵-C5H5) (1) and [Cp^?(CO)2Fe(THF)]BF4 (Cp^? =?⁵-C5(CH3)5) (2) react with 1,3,5,7-tetraazaadamantane (HMTA) to give stable water-soluble dinuclear complexes [{(?⁵-C5R5)(CO)2Fe}2(?-HMTA)](BF4)2 (R=H; R=CH3) and mononuclear complexes [(?⁵-C5R5)(CO)2Fe(HMTA)]BF4 (R=H; R=CH3). The reaction of 1 with 1,4-diazabicyclo[2.2.2]octane (DABCO) gave good yields of the dinuclear and mononuclear complexes, [{Cp(CO)2Fe}2(?-DABCO)](BF4)2 (6a) and [Cp(CO)2Fe(DABCO)]BF4 (6b), respectively, depending on reagent ratios. Similar reactions with 2 gave very low yields of the mononuclear complex [Cp^?(CO)2Fe(DABCO)]BF4 (6c) as the only product. The reactions of [Cp(CO)2Fe(HMTA)]BF4 (3b) and [Cp^?(CO)2Fe(HMTA)]BF4 (4b) with NaBPh4 in acetone proceeded smoothly at room temperature to give the corresponding BPh4 ^- salts. Reaction of 4b with 1 at room temperature gave the dinuclear complex [{Cp(CO)2Fe}2(?-HMTA)](BF4)2 (3a) as the major product, while the same reaction conducted at 0°C led to the unstable mixed ligand complex [{Cp(CO)2Fe}(?-HMTA){Fe(CO)2Cp^?}](BF4)2. The reactions of 1 and 2 with 1-methylimidazole (1-meIm) gave high yields of [(?⁵-C5R5)(CO)2Fe(1-meIm)]BF4 (R=H (7); R=CH3 (8)), of which the NMR, IR and single crystal X-ray studies reveal the coordination of 1-methylimidazole to be via the ‘pyridine nitrogen’ of the imidazole ring. Single-crystal X-ray diffraction studies reveal that compounds 3a and 8 crystallize in the orthorhombic P212121 and Pna21 space groups, respectively. Compound 7 however, crystallized in the monoclinic P21/c space group with three independent molecular cations and anions each in the asymmetric unit.

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Posted on 26 May 2012 | 4:34 am

Arene-ruthenium(II) complexes containing 5-fluorouracil-1-methyl isonicotinate: Synthesis and characterization of their anticancer activity

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Kuan-Guan Liu, Xiao-Qing Cai, Xian-Chuan Li, Da-An Qin, Mao-Lin Hu

To integrate the respective advantages exhibited by half-sandwich arene-Ru(II) fragments and 5-FU derivatives, a multifunctional ligand that links isonicotinic acid and 5-Fu (5-fluorouracil) through an ester bond for achieving the enhanced effect and an organoruthenium(II) complex containing this ligand were prepared and characterized by standard analytical techniques. The cytotoxicity of these organoruthenium(II) compounds containing 5-fluorouracil-1-methyl isonicotinate against BEL-7402 human cancer cells was moderately improved, which implies synergistic action of 5-Fu and the half-sandwich-structured arene-Ru(II). In addition, the organoruthenium(II) compounds containing isonicotinic acid and methyl isonicotinate are also discussed, and the crystal structure of [(?⁶-p-cymene)RuCl2(methyl isonicotinate)] (4) was determined; its piano-stool structure is analyzed in this paper.

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Posted on 26 May 2012 | 4:34 am

Self-assembly of two Keggin-based 3D and 2D complexes with cobalt (II)-bis(triazole) motifs: Influenced by the spacer length of the ligands

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Xiu-Li Wang, Dan Zhao, Ai-Xiang Tian, Guo-Cheng Liu, Hong-Yan Lin, Yu-Fei Wang, Qiang Gao, Xiao-Jing Liu, Na Li

Two Keggin-based inorganic–organic hybrid complexes, [Co2(H2O)2(btb)4(HPMo^VI 10Mo^V 2O40)] (1) and [Co2(btx)5(HPMo^VI 10Mo^V 2O40)] (2) (btb=1,4-bis(1,2,4-triazol-1-yl)butane, btx=1,6-bis(1,2,4-triazol-1-yl)hexane), have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, elemental analyses, IR spectra, and thermogravimetric analyses (TGA). Complex 1 exhibits 2D ladder-like metal–organic layers, which are further linked by the Keggin anions to construct a 3D twofold interpenetrating framework. Complex 2 shows a 2D metal–organic network containing two kinds of pores, in which the Keggin anions acting as bidentate inorganic linkages reside alternately. The flexible bis(triazole) ligands btb and btx with different spacer lengths play an important role in the formation of the final structures. In addition, the electrochemical and photocatalytic properties of 1 and 2 have been reported.

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Posted on 26 May 2012 | 4:34 am

Structural, spectral and magnetic properties of carboxylato cobalt(II) complexes with heterocyclic N-donor ligands: Reconstruction of magnetic parameters from electronic spectra

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

J. Titiš, J. Hudák, J. Kožíšek, A. Krutošíková, J. Moncol’, D. Tarabová, R. Bo?a

Heteroleptic cobalt(II) complexes with general formula of [Co(N-base)2(car)2(H2O)2], have been synthesized and structurally characterized; the N-base stands for neutral N-donor ligands: iso-quinoline (iqu), [1]benzofuro[3,2-c]pyridine (bzfupy), 1-(pyridin-3-yl)[1]benzofuro[3,2-c]pyridine (1-py-bzfupy) and 1-phenyl-1H-imidazole (bylim); car =acetato (ac) or benzoato (bz) ligands. The structure of [Co(iqu)2(ac)2(H2O)2] 1, [Co(bzfupy)2(ac)2·(H2O)2] 2, [Co(1-py-bzfupy)2(ac)2(H2O)2]·H2O 3 and [Co(bylim)2(bz)2(H2O)2] 4 complexes is formed of the {CoN2O2O2?} chromophore. These complexes were subjected to magnetochemical investigation down to 2K (susceptibility and magnetization measurements). They show magnetic behavior typical for the zero-field splitting systems. The axial parameter of the zero-field splitting adopts large values, D =80–103cm^?1. We have analyzed electronic spectra of the complexes in detail with aim to extract the crystal-field parameters. These have been used for reconstruction of the magnetic parameters. The calculated axial ZFS parameters are in good agreement with the experimental values.

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Posted on 26 May 2012 | 4:34 am

Synthesis, structure, DNA binding and photonuclease activity of a nickel(II) complex with a N,N?-Bis(salicylidene)-9-(3,4-diaminophenyl)acridine ligand

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Mariappan Mariappan, Masahiko Suenaga, Abhik Mukhopadhyay, Bhaskar G. Maiya

A new class of salen functionalized novel ligand N,N?-Bis(salicylidene)-9-(3,4-diaminophenyl)acridine, H2daasal (two potential intercalators, salen and acridine, which are linked together via C–C bond) and its metal complex [Ni(daasal)] have been synthesized and characterized by X-ray diffraction, elemental analysis, UV–Vis, IR, ¹H NMR, MALDI-TOF mass spectrometry and cyclic voltammetry methods. From the crystal structure, the salphen moiety is not coplanar with the acridine ring, having a dihedral angle of 68° and 76° in both H2daasal and [Ni(daasal)], respectively. [Ni(daasal)] shows a reversible oxidation cyclic voltammetric response near 1.03V versus SCE in CH3CN (0.1M TBAP) assignable to the Ni(II)/Ni(III) couple. The interaction of these compounds with calf-thymus (CT) DNA was examined using spectroscopic and viscosity measurements. These studies reveal that both compounds bind to CT DNA via an intercalative mode. Molecular-modeling studies also support an intercalative mode of binding to the model duplex d(CGCAATTGCG)2 possibly from the major groove with a slight preference for GC rich region. Additionally, [Ni(daasal)] promotes the cleavage of plasmid pBR322 DNA upon irradiation under terminal oxidant Oxone.

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Posted on 26 May 2012 | 4:34 am

Synthesis, characterization, biological activities, and luminescent properties of lanthanide complexes with N,N?-bis(2-hydroxy-1-naphthylidene)-1,6-hexadiimine

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Abdulaziz M. Ajlouni, Ziyad A. Taha, Waleed Al Momani, Ahmed K. Hijazi, Mohammad Ebqa’ai

A series of lanthanide complexes with a Schiff base ligand, L (N,N?-bis(2-hydroxy-1-naphthylidene)-1,6-hexadiimine) are presented. The ligand and its complexes were synthesized and characterized based on elemental analyses, molar conductance, IR, ¹H and ¹³C NMR, UV–Vis, and TGA studies. These analytical and spectral data reveal that the ligand L coordinates to the central Ln(III) ion by its two imine nitrogen atoms and two phenolic oxygen atoms and the general formula of the complex is [LnL(NO3)2·2H2O]NO3, Ln=[Ln=La(III), Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Dy(III) and Er(III)] Under the excitation at 396nm, the luminescence emission properties for Sm, Tb, and Eu complexes are observed. These observations show that the ligand favors energy transfers to the emitting energy level of these lanthanide ions. Furthermore, the antimicrobial activities of all complexes were studied against a number of pathogenic bacteria. The antimicrobial activity results show that most of the synthesized Ln(III) complexes possessed good antibacterial activity and in most cases higher than that of the corresponding ligand L.

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Posted on 26 May 2012 | 4:34 am

Synthesis and photophysics of platinum(II) complexes bearing 2-(7-(4-R-phenylethynyl)-9,9-dihexadecyl-fluoren-2-yl)-1,10-phenanthroline ligand

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Xu-Guang Liu, Wenfang Sun

A series of platinum(II) complexes bearing 2-(7-(4-R-phenylethynyl)-9,9-dihexadecyl-fluoren-2-yl)-1,10-phenanthroline ligand were synthesized and characterized. Their photophysical properties were systematically investigated by UV–Vis absorption, emission, and transient absorption spectroscopy. All complexes exhibit ¹?,?^? absorption bands below 410nm and charge transfer transitions at 415–550nm in CH2Cl2. They all emit at ca. 624nm with vibronic structures. Both UV–Vis absorption and emission spectra show negative solvatochromic effect. All complexes exhibit broad and moderately strong triplet transient absorption from the near-UV to the near-IR spectral region. Reverse saturable absorption of these complexes in CH2Cl2 for ns laser pulses at 532nm was demonstrated.

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Posted on 26 May 2012 | 4:34 am

Two-step postsynthetic modifications of a dinuclear Zn(II) coordination compound: Investigating the stability of the coordination chromophore

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Zhenbo Ma, Shuangbing Han, Russell Hopson, Yanhu Wei, Brian Moulton

Attempted two-step postsynthetic modifications (Click reaction and recrystallization) of a dinuclear Zn(II) coordination compound Zn2(OOC–C6H4–N3)4(quinoline)2 lead to the formation of a mononuclear Zn(II) compound – Zn(OOC–C6H4–C2HN3–COOCH3)2(quinoline)·DMSO. In this feasibility study, the relatively low stability of the coordination chromophore around Zn(II) in the starting material is evidenced by Hirshfeld surface analysis and results in the transformation of coordination chromophore during the postsynthetic reaction. Diffusion Ordered Spectroscopy NMR experiments confirmed that the intermediate complex Zn(OOC–C6H4–C2HN3–COOCH3)2 formed by Click reaction exists in the coordinated form in the solution phase despite the loss of the neutral ligand-quinoline. The final product Zn(OOC–C6H4–C2HN3–COOCH3)2·(quinoline)·DMSO with a mononuclear crystal structure was formed by recrystallizing the intermediate with presence of quinoline.

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Posted on 26 May 2012 | 4:34 am

The interaction between heteroditopic pyridine–nitrogen NHC with novel sulfur NHC ligands in palladium(0) derivatives: Synthesis and structural characterization of a bis-carbene palladium(0) olefin complex and formation in solution of an alkene–alkyne mixed intermediate as a consequence of the ligands hemilability

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Luciano Canovese, Fabiano Visentin, Carlo Levi, Claudio Santo, Valerio Bertolasi

We have synthesized a new class of heteroditopic chelating ligands bearing the phenylthiomethyl group and variously substituted imidazole derivatives and the corresponding complexes [Pd(?²-ma)(R-NHC-CH2-SPh) (ma=maleic anhydride; R=methyl, mesityl, di-i-propylphenyl). We have compared their chemical characteristics and reactivity with those of similar palladium(0) complexes bearing the R-NHC-CH2-Py ligands. The hemilability of the above-mentioned moieties is apparent when their palladium derivatives react with an excess of the same or different heteroditopic ligands. In these cases, we obtained complexes bearing maleic anhydride and two mono-coordinated heteroditopic ligands bound to the same metal center. However, at variance with the generally accepted opinion, precipitation of AgBr does not warrant the quantitative formation of the bis-heteroditopic Pd(0) derivative and in some cases, a reaction involving a heterogeneous equilibrium is observed. The reaction of the palladium(0) carbene–sulfur or carbene–nitrogen complexes with the alkyne dimethyl-2-butynedioate (dmbd) to give palladacyclometallate derivatives is not always warranted and formation of the intermediate [Pd(?²-ma)(?²-dmdb)(?¹-Mes-NHC-CH2-SPh)] is detected only in one case. Finally, we have carried out a diffractometric study on the solid-state structures of two derivatives and in particular we describe the configurations of the complex [Pd(?²-ma)(?¹-Me-NHC-CH2-SPh)2] and of [Pd(?²-ma)(Me-NHC-CH2-SPh)].

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Posted on 26 May 2012 | 4:34 am

Iron(III) and nickel(II) complexes of O,N,N,O-chelating benzophenone thiosemicarbazone: Electrochemistry and in situ spectroelectrochemistry

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Yasemin Kurt, At?f Koca, Mehmet Akkurt, Bahri Ülküseven

New complexes, [Fe(L)Cl] (1 and 2) and [Ni(L)]·C2H5OH (3 and 4), were synthesized by template condensation of 2,4-dihydroxy-benzophenone-S-methyl-thiosemicarbazone with 5-bromo- and 5-chloro-2-hydroxy-benzaldehyde and characterized by elemental analysis, conductivity measurements, IR, NMR and mass spectra. Complex 4 crystallizes in monoclinic space group P21/c with unit cell dimensions, a =13.1091 (3)Å, b =24.2308 (3)Å, c =15.5808 (4)Å, ? =102.2632 (11)°, V =4836.22 (18)ų, Z =8. The asymmetric unit of 4 contains two main molecules and two ethanol molecules. Electrochemical behaviors of 1–4 were studied using cyclic voltammetry and square wave voltammetry. Voltammetric analysis of the complexes shows a quasi-reversible metal-based reduction processes between ?0.55 and ?0.78V followed by an irreversible reduction process within ?0.91 and ?1.27V versus SCE. An irreversible oxidation is also observed within ?1.10 to ?1.23V versus SCE during anodic potential scans. While the thiosemicarbazone moiety stabilizes +3 and +2 oxidation states for the iron complexes, only Ni^II is stable in solution with the same ligand in dichloromethane and dimethylsulfoxide. In-situ spectroelectrochemical studies were employed to determine the colors and spectra of electrogenerated species of the complexes.

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Posted on 26 May 2012 | 4:34 am

Supramolecular assemblies of organotellurium(IV) dithiocarbamates and third order nonlinear optical susceptibility (?(3)) of C4H7(CH3)Te[S2CN(C2H5)2]2

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Prakash C. Srivastava, Shrinkhala Dwivedi, Vikas Singh, Tripurari Pujan, Arun K. Bhuj, Ray J. Butcher, M. Bala Murali Krishna, D. Narayana Rao

Synthesis of supramolecular assemblies of organotellurium(IV) dithiocarbamates, formed through intramolecular Te?S secondary bonds, intermolecular Te?X (X=I, S) secondary bonds and C–H?O hydrogen bonds are described. The supramolecular assemblies containing diethyldithiocarbamate group may serve as possible “rescue agents”. The third order nonlinear optical susceptibility of the organotellurium(IV) diethyldithiocarbamate C4H7(CH3)Te[S2CN(C2H5)2]2 (1) has been studied by degenerate four wave mixing technique using a picosecond laser. It is found to exhibit efficient third-order nonlinear optical susceptibility (? ⁽³⁾) of 7.21×10^?14 esu and second order hyperpolarizability (?) of 4.88×10^?32 esu.

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Posted on 26 May 2012 | 4:34 am

Electronic effects on the reactivity of copper mono-bipyridine complexes

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Martin Moore, D. Andrew Knight, Dan Zabetakis, Jeffrey R. Deschamps, Walter J. Dressick, Eddie L. Chang, Bianca Lascano, Rafaela Nita, Scott A. Trammell

Electronic effects on the synthesis, structure and reactivity of copper 2,2?-bipyridine (bpy) complexes of formula [Cu(4,4?-R2-2,2?-bipyridine)]Cl2, where R=Cl, CH3, OCH3, and [Cu(4,4?-R2-2,2?-bipyridine)](NO3)2, where R=NO2, Cl, are reported. Pure complexes were formed, as shown by elemental analysis, for mono bpy Cu complexes when bpy ligands with groups R=Cl, CH3 or OCH3 were pre-dissolved in chloroform and added to methanol solution of CuCl2 in a 1:1 molar ratio (compounds 1–3). Mono bpy Cu complexes were obtained when bpy ligands with groups R=Cl and NO2 were pre-dissolved in THF and added to methanol solution of Cu(NO3)2 in a 1:1 molar ratio (compounds 4 and 5). Under the same conditions, for R=OCH3 the bis bipyridine complex [Cu(4,4?-(OCH3)2-2,2?-bipyridine)2(NO3)](NO3) (6) was formed. Suitable crystals of 4 and 6·CH3OH for X-ray analysis were formed by the slow evaporation of solvent. The main electronic effect for the catalytic hydrolysis of methyl parathion by Cu(4,4?-R2-2,2-bipyridine)²⁺ (aq), where R=Cl, H and CH3, was a shift in the acid dissociation constant of coordinated water and a small increase in the second order rate constant, k 2, measured at pH 9.1.

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Posted on 26 May 2012 | 4:34 am

Blue fluorescence from the ligand and yellow phosphorescence from the iridium complex: High-efficiency wet-processed white organic light-emitting device

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Fang-Fang Yu, He-Liang Fan, Hai-Fang Huang, Qian-Yong Cao, Yan-Feng Dai, Xi-Cun Gao, Yu-Zhu Shang, Min-Yan Zhang, Li Long, Hong Xu, Xi-Feng Li, Bin Wei

We synthesized four carbazole modified blue-emitting fluorescent ligands. These ligands coordinated with Ir³⁺ and four yellow-emitting phosphorescent complexes were obtained. A high-efficiency (current efficiency 20.6cd/A) yellow electrophosphorescence device was wet-fabricated using the complex as a guest. The ligands can harvest and transfer energy to the complexes and a high efficiency (?18cd/A) white-light emitting device (CIE 0.31, 0.39) was obtained using the ligand as the blue-fluorescence emitter and the complex as the yellow-phosphorescence emitter. Therefore, the ligand can be a coordinator, an emitter and partly, a host. This is beneficial to device efficiency and saving cost for large-scale manufacturing.

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Posted on 26 May 2012 | 4:34 am

Binuclear fluoroborylene (BF) cobalt carbonyls: Comparison with homoleptic cobalt carbonyls

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Liancai Xu, Qian-shu Li, R. Bruce King

The recent synthesis by Vidovi? and Aldridge of the complex (? ⁵-C5H5)2Ru2(CO)4(?-BF) containing the fluoroborylene ligand (BF), isoelectronic with CO, suggests the possibility of introducing the BF ligand into binuclear cobalt carbonyl derivatives of the type Co2(BF)2(CO) n (n =7, 6, 5, 4, 3). This has now been explored using density functional theory. Structures in which both BF groups bridge a cobalt–cobalt bond are energetically preferred for the Co2(BF)2(CO) n (n =6, 5, 4, 3) derivatives over other types of structures. Thus the Co2(?-BF)2(CO)6 structure with two bridging BF groups lies more than 18kcal/mol below the next lowest Co2(BF)2(CO)6 structure and appears to be a reasonable synthetic objective. This differs from the well-known isoelectronic Co2(CO)8 for which the structures with two bridging CO groups and with all terminal CO groups are so close in energy that they are found experimentally to exist in equilibrium. Examples of Co2(B2F2)(CO) n (n =7, 4, 3) derivatives are found in which the two BF groups have coupled to form a bridging difluorodiborene (B2F2) ligand with a B–B distance of ?1.9Å. However, the Co2(B2F2)(CO)7 structures do not appear to be viable since loss of a CO group to give Co2(BF)2(CO)6 is predicted to be an exothermic process.

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Posted on 26 May 2012 | 4:34 am

A novel fluorescent ?-O bridged dinuclear Ni(II) coordination polymer with 4,4?-oxybis(benzoic acid) and its photocatalysis activity

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Jing Han, Zhong Yu, Xiang He, Peng Li, Yun Wang, Chun-yan Quan

A novel Ni(II) coordination polymer with flexible 4,4?-oxybis(benzoic acid) (oba) and rigid 4,4?-bipyridine was prepared hydrothermally and crystallographically characterized. It shows an unusual ?-oxo(O^2?) bridged dinickel(II) polymer. In the dimetal core, each metal center is six-coordinated to three carboxylate oxygen atoms from two different oba ligands, two nitrogen atoms of distinct 4,4?-bipyridine and one bridging oxygen forming a distorted octahedron. Upon complexation, nickel complex exhibits intense purple fluorescence (413.8nm) which may originates to the O^2?Ni²⁺(LMCT) in addition to the peaks of intraligand ?–?^? transition of oba ligand (317.7 and 720.7nm). Moreover, nickel crystals possess preferable photocatalytic decomposition of RhB solution.

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Posted on 26 May 2012 | 4:34 am

Phosphorescent cationic iridium(III) complexes with cyclometalating 1H-indazole and 2H-[1,2,3]-triazole ligands

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Nail M. Shavaleev, Rosario Scopelliti, Michael Grätzel, Mohammad K. Nazeeruddin

Two new cationic iridium(III) complexes with cyclometalating 1-phenylindazole or 2-phenyl-1,2,3-triazole ligands, [(C^N)2Ir(4,4?-di-tert-butyl-2,2?-dipyridyl)](PF6), exhibit yellow or green phosphorescence with quantum yields and excited state lifetimes of up to 45% and 840ns in argon-saturated dichloromethane solution at room temperature.

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Posted on 26 May 2012 | 4:34 am

Stereospecific ligands and their complexes. Part X: Synthesis, characterization and in vitro antitumoral activity of platinum(IV) complexes with O,O?-dialkyl-(S,S)-ethylenediamine-N,N?-di-2-(4-methyl)pentanoate ligands

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 390

Jelena M. Vuji?, Goran N. Kalu?erovi?, Bojana B. Zmejkovski, Marija Milovanovi?, Vladislav Volarevi?, Nebojša Arsenijevi?, Tatjana P. Stanojkovi?, Sre?ko R. Trifunovi?

Synthesis of four new platinum(IV) complexes 1–4, with bidentate N,N?-ligand precursors O,O?-dialkyl esters (alkyl=ethyl, n-propyl, n-butyl and n-pentyl), of (S,S)-ethylenediamine-N,N?-di-2-(4-methyl)pentanoic acid dihydrochloride [(S,S)-H4eddl]Cl2 were reported. The composition of the novel platinum complexes was determined by elemental analysis and characterizations were performed by infrared, ¹H and ¹³C NMR spectroscopy. DFT calculations indicate formation one (R,R) from three possible diastereoisomers (S,S; R,S). Complexes 1–4 displayed potent anticancer activity. IC50 values range from 0.74 to 70?M, against tested cell lines, except for CLL cells. The antitumoral activity of 2–4 was found to be considerably stronger to Jurkat and K562. Cell cycle analysis of cell lines showed G1 arrest in the presence of analyzed complexes.

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Posted on 26 May 2012 | 4:34 am

High-valent titanium(IV)salophen: An efficient catalyst for rapid conversion of aldehydes to 1,1-diacetates with acetic anhydride

Publication year: 2012
Source:Inorganica Chimica Acta, Volume 388

Maryam Yadegari, Majid Moghadam, Shahram Tangestaninejad, Valiollah Mirkhani, Iraj Mohammadpoor-Baltork

In the present work, a mild and highly efficient method for protection of aldehydes with acetic anhydride in the presence of high-valent titanium (IV) salophen trifluoromethanesulfonate, [Ti^IV(salophen)(OTf)2], at room temperature is reported. Under these conditions, different aldehydes bearing electron-withdrawing and electron-donating substituents were reacted with acetic anhydride and the corresponding 1,1-diacetates were obtained in good to excellent yields. The results showed that the yields were higher for aldehydes bearing electron-withdrawing substituents such as nitro, chloro, bromo and 3-methoxy, while aldehydes containing electron donating groups such as 4-methoxy and 4-methyl produced the lower yields. The catalyst was reused several times without loss of its catalytic activity.

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Posted on 26 May 2012 | 4:34 am