FORMATION AND NMR EVIDENCE FOR λ5-SILICATES WITH A SiS5 COORDINATION

Abstract

The reaction of PhSLi, made from BuLi and PhSH in THF solution, with the spirosilanes C 2 H 4 (S) 2 Si(S)2C 2 H 4 (1) or CÖH^S^SKS^CSFL (3) yields the hypervalent silicon species [Li(THF)n]{[C 2 H 4 (S)2]2SiSPh} (2) and [Li(THF)"]{[C6H 4 (S) 2 ] 2 SiSPh} (4), respectively, with a SiS 5 coordination. The observed 29 Si NMR chemical shifts are with -85.9 ppm (2) and -63.0 ppm (4) in the typical range of silicon with the coordination number five.