From Silylone to an Isolable Monomeric Silicon Disulfide Complex.

Abstract

The synthesis and characterization of the first bis-N-heterocyclic carbene stabilized monomeric silicon disulfide (bis-NHC)SiS2 2 (bis-NHC=H2 C[{NC(H)C(H)N(Dipp)}C:]2 , Dipp=2,6-iPr2 C6 H3 ) is reported. Compound 2 is prepared in 89 % yield from the reaction of the zero-valent silicon complex ('silylone') 1 [(bis-NHC)Si] with elemental sulfur. Compound 2 can react with GaCl3 in acetonitrile to give the corresponding (bis-NHC)Si(S)S→GaCl3 Lewis acid-base adduct 3 in 91 % yield. Compound 3 is also accessible through the reaction of the unprecedented silylone-GaCl3 adduct [(bis-NHC)Si→GaCl3 ] 4 with elemental sulfur. Compounds 2, 3, and 4 could be isolated and characterized by elemental analyses, HR-MS, IR, (13) C- and (29) Si-NMR spectroscopy. The structures of 3 and 4 could be determined by single-crystal X-ray diffraction analyses. DFT-derived bonding analyses of 2 and 3 exhibited highly polar Si-S bonds with moderate pπ -pπ bonding character.