Si(SiMe3)2SiPh3 – a ligand for novel sub-valent tin cluster compounds

Abstract

For the synthesis of metalloid tin cluster compounds applying the disproportionation reaction of a Sn(I) halide, silyl ligands, especially the symmetric Si(SiMe₃)₃ has proven to be extremely useful. Silyl ligands of lower symmetry where e.g. one SiMe₃ group is substituted with SiPh₃ are thereby unexplored, although the synthesis of the anionic silyl precursors is quite easy, referring to previously described methods. Here the synthesis of the silanide [Si(SiMe₃)₂(SiPh₃)]⁻3 as its potassium (3_K) as well as its lithium salt (3_Li) in excellent yield is presented. 3 proved to be a suitable starting material for the synthesis of subvalent tin compounds as shown by the reaction with tin halides in oxidation state +2 (SnCl₂) and +1 (SnCl); i.e. on the one hand the anticipated stannide [Sn(Si(SiMe₃)₂SiPh₃)₂Cl]⁻ could be isolated and on the other hand the unexpectedly partly substituted ring compound Cl₄Sn₄[Si(SiMe₃)₂SiPh₃]₄ is obtained. As no elemental tin is formed during the reaction with SnCl, metalloid tin clusters may be present in solution too, which is supported by the nearly black color of the reaction mixture, showing that 3 might be a suitable ligand for the synthesis of such cluster compounds.