Ein neues Silicat-Anion: [Si(NCS)6]2- / A New Silicate Anion: [Si(NCS)6]2-

Abstract

Crystalline salts of the new hexa-co-ordinated silicon complex anion [Si(NCS)6]2- were obtained by stoichiometric reaction of Si(NCS)4 with NEt4NCS. NMe4NCS or [DABCO · 2 Me](NCS)2 in acetonitrile. Their crystallographic data were determined: [NEt4]2[Si(NCS)6]: tetragonal, P42/m, a = 1049 pm, c = 1546 pm, Z = 2. [NMe4]2[Si(NCS)6]: rhombohedral, a = 879 pm, α = 83.2°, Z = 1. [DABCO · 2 Me][Si(NCS)6]: triclinic, a = 933 pm, b = 1511 pm, c = 899 pm, α = 105.8°, β = 96.3°, γ = 103.5°, Z = 2. The X-ray structure analysis of [NEt4]2[Si(NCS)6] shows silicon to be coordinated nearly octahedrally by the nitrogen atoms of two linear and four slightly bent NCS groups. The mean Si−N, N−C and C−S bond lengths are 182.1 pm. 115.2 pm and 160.3 pm, respectively. IR spectra are reported. The positions of the [Si(NCS)6]2- bands are discussed in context with the structure.