Cohydrolysis of organotin chlorides with trimethylchlorosilane.: Okawara's pioneering work revisited and extended

The synthesis of the stannasiloxanes {[R-2(Me3SiO)Sn](2)O}(2) (1, R = Me; 2, R = Et), [R-2(Me3SiO)Sn](2)O (8, R = Me3SiCH2; 9, R = t-Bu), R2Sn(OSiMe3)(2) (3, R = i-Pr; 4, R= Me3SiCH2; 5, R = t-Bu; 6, R = Cp(CO)(3)W; 7, R = CP(CO)(2)Fe), and [Cp(CO)(2)Fe](2)Sn(OSiPh3)(2) (7a), the monoorganotin trichloride Me3SiCH2SnCl3 (13), and the organotin oxocluster (Me3SiCH2Sn)(12)O-14(OH)(6)Cl-2 (14) is reported. Their identity was confirmed by both solution and solid state multinuclear NMR spectroscopy and in the case of 1, 2, 6, 7a, and 14 also by single-crystal X-ray analyses. A spinning sideband analysis of the Sn-119 MAS spectra reveals the coordination geometries of the tin atoms in the stannasiloxanes 1 and 2 to be different from those of related diorganotin oxides (R2SnO)(n) (R = Me, Et). In solution, 1 and 2 exhibit an intramolecular exchange process as well. as monomer-dimer equilibria. The reaction of 4 with cyclo-(t-Bu2SnO)(3) and of cyclo-[(Me3SiCH2)(2)SnO](3) with cyclo-(t-Bu2SnO)(3) provided evidence for the formation in situ of the mixed tetraorganodistannoxane t-Bu-2(Me3SiO)SnOSn(OSiMe3)(CH2SiMe3)(2) (10) and of the hexaorganotristannoxanes cyclo-[(Me3SiCH2)(2)Sn(OSnt-Bu-2)(2)O] (11) and cyclo-{t-Bu2Sn[OSn(CH2SiMe3)(2)](2)O) (12).