The alchemists of the seventeenth century were already aware that
mixtures of �spiritus vini� (ethanol) and mercury in �aqua fortis� (nitric
acid) made for an explosive brew. In his book Laboratorium Chymicum,
Johann Kunckel von L�wenstern describes the vigorous reaction of
mercury nitrate with alcohol to form mercury fulminate (Hg(CNO)2).
In 1799, the English chemist Edward Howard isolated the compound by
chance, which was produced a sensation in the nascent scientific field
of chemistry.
Mercury fulminate is very sensitive to shock, friction, and sparks. It
explosively decomposes to form mercury, carbon monoxide, and nitrogen.
This explosive power was used extensively: Alfred Nobel put mercury
fulminate into blasting caps for detonating dynamite. This relatively
safe new detonator was what allowed for the huge success of dynamite.
In Germany alone, the annual production of mercury fulminate in the
early 20th century reached about 100,000 Kg.
The first investigations of the crystal structure of mercury fulminate
by X-ray structure analysis date from 1931. Now Beck, Klap�tke and
their team have finally succeeded in fully solving the structure. To
do this, they irradiated small crystals with a uniform crystal lattice,
known as single crystals, with X-rays. The resulting X-ray diffraction
pattern allowed the researchers to precisely calculate the positions
of the individual atoms within the crystal and the distances between
them. Mercury fulminate crystals are orthorhombic and the crystal
consists, as expected, of separate Hg(CNO)2 molecules. Each
mercury atom is surrounded by two carbon atoms. The measured positions
and bond lengths confirm a molecular structure of O−N=C−Hg−C=N−O.
Says Beck: �In addition, we can unambiguously show that the molecules
in the crystal have a stretched-out, nearly linear form. They are not
bent, and each mercury atom is not bound to two oxygen atoms, as they
are amazingly still occasionally depicted in the literature.�
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