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

The synthesis of the stannasiloxanes {[R 2 (Me 3 SiO)Sn] 2 O} 2 (1, R = Me; 2, R = Et), [R 2 (Me 3 SiO)Sn] 2 O (8, R = Me 3 SiCH 2 ; 9, R = t-Bu), R 2 Sn(OSiMe 3 ) 2 (3, R = i-Pr; 4, R = Me 3 SiCH 2 ; 5, R = t-Bu; 6, R = Cp(CO) 3 W; 7, R = Cp(CO) 2 Fe), and [Cp(CO) 2 Fe] 2 Sn(OSiPh 3 ) 2 (7a), the monoorganotin trichloride Me 3 SiCH 2 SnCl 3 (13), and the organotin oxocluster (Me 3 SiCH 2 Sn) 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 analyzes. A spinning sideband analysis of the 119 Sn 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 (R 2 SnO) 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-Bu 2 SnO) 3 and of cyclo-[(Me 3 SiCH 2 ) 2 SnO] 3 with cyclo-(t-Bu 2 SnO) 3 provided evidence for the formation in situ of the mixed tetraorganodistannoxane t-Bu 2 (Me 3 SiO)SnOSn(OSiMe 3 )(CH 2 SiMe 3 ) 2 (10) and of the hexaorganotristannoxanes cyclo-[(Me 3 SiCH 2 ) 2 Sn(OSnt-Bu 2 ) 2 O] (11) and cyclo-{t-Bu 2 Sn[OSn(CH 2 SiMe 3 ) 2 ] 2 O} (12).