The crystal and molecular structure of mercury fulminate (Knallquecksilber) [1]

Abstract

A short survey on the fascinating history of mercury fulminate is given. The crystal structure of Hg(CNO) 2 has been determined using single crystal X-ray diffraction. Mercury fulminate crystallizes in an orthorhombic cell, space group Cmce with a = 5.3549(2), b = 10.4585(5), c = 7.5579(4) Å and Z = 4. The distances and angles in the O-N≡C-Hg-C≡N-O molecule are Hg-C 2.029(6) Å, C≡N 1.143(8) Å, N-O 1.248(6) Å and C-Hg-C 180.0(1)°, Hg-C≡N 169.1(5)°, C≡N-O 179.7(6)°. Each mercury atom is surrounded by two oxygen atoms from neighbouring g(CNO) 2 molecules with a nonbonding distance of Hg⋯O 2.833(4) Å. The Hg-C bond lengths in the linear Hg(CNO) 2 molecules are shorter than those in the tetrahedral complex [Hg(CNO) 4] 2-. This refers to a large contribution of the 6s orbital in the Hg-C bonds of Hg(CNO) 2. The results of the X-ray powder investigation on Hg(CNO) 2 are also reported. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.