On the reaction of diorganodihydroxysilanes with (t-Bu2SnO)(3). Synthesis and characterisation of a novel stannasiloxane complex and its dissociation in solution

The complex [Ph2Si(OSnt-Bu-2)(2)Ot-Bu2Sn(OH)(2)] (2) was obtained in high yield by reaction of Ph2Si(OH)(2) with (t-Bu2SnO)(3) (1). Reaction of t-Bu2Si(OH)(2) with 1 gave [t-Bu2Si(OSnt-Bu-2)(2)O] (4a) instead. The compounds were investigated by means of NMR, IR, Mossbauer spectroscopy, and in case of 2 by X-ray analysis. In solution, 2 is in equilibrium with [Ph2Si(OSnt-Bu-2)(2)O] (2a), 1, and water. t-Bu2Sn(OH)(2) (3) was prepared by controlled hydrolysis of t-Bu2Sn(OMe)(2) and was shown to undergo condensation with formation of 1. Mossbauer studies as well as Sn-119 CP MAS NMR including side band analysis suggest 3 to exhibit a dimeric structure with pentacoordinate tin. Similar studies on 1 suggest fast rotation of the molecule in the crystal lattice.