Magnesium and chlorostannanes—building blocks for novel tinmodified silanes

Cyclic stannasilanes with alternating Si–Sn sequences ([Ph2Sn–Me2Si]3, 1; [t-Bu2Sn–Me2Si]2, 2) were synthesized by the reaction of dimethyldichlorosilane with diorganodichlorostannanes (R2SnCl2, R=Ph, t-Bu) in the presence of magnesium. The reaction pathway towards 2 via the unexpected intermediate product Cl–SiMe2–(t-Bu2Sn)2–SiMe2–Cl (5) is discussed. In addition, some thermodynamic and kinetic studies for the formation of the rings (1, 2) and the Grignard-type tin compounds are presented. All compounds were characterized by NMR, MS and elemental analysis. The solid state structures of 1, 2 and 5 were determined by X-ray crystallography.