Reaction of (<i>t</i>-Bu₂SnO)₃ with Organohalosilanes. Simple Formation of Open-Chain and Cyclic Stannasiloxanes

Abstract

The synthesis or in situ formation of the new stannasiloxanes R 1 R 2 Si(OSn- t -Bu 2 ) 2 E ( 2, R 1 = R 2 = t -Bu, E = O; 22, R 1 = t -Bu, R 2 = F, E = O; 23, R 1 = R 2 = Ph, E = O; 24, R 1 = R 2 = t -Bu, E = S; 25, R 1 = t -Bu, R 2 = F, E = S; 26, R 1 = R 2 = Ph, E = S), t -Bu 2 Si[OSn(Cl)- t -Bu 2 ] 2 ( 3 ), t -Bu 2 (Cl)SnOSi(X)- t -Bu 2 ( 4, X = Cl; 12, X = H), t -Bu 2 Sn(OSiR 1 R 2 O) 2 M ( 5, R 1 = R 2 = t -Bu, M = Sn- t -Bu 2; 7, R 1 = R 2 = Ph, M = Sn- t -Bu 2; 9, R 1 = R 2 = Ph, M = SiPh 2; 18, R 1 = t -Bu, R 2 = Cl, M = Sn- t -Bu 2; 21, R 1 = t -Bu, R 2 = F, M = Sn- t -Bu 2 ), t -Bu 2 Sn(OSiXR 2 ) 2 ( 10, X = H, R = t -Bu; 11, X = F, R = t -Bu; 13, X = F, R = Et; 14, X = F, R = i -Pr; 15, X = F, R = Ph), t -Bu 2 Sn(OSiX 2 - t -Bu) 2 ( 16, X = Cl; 19, X = F), t -Bu 2 ClSnOSiCl 2 - t -Bu ( 17 ), [R 1 R 2 Si(OSn- t -Bu 2 ) 2 O. t -Bu 2 SnX 2 ] ( 20, R 1 = t -Bu, R 2 = F, X = F; 27, R 1 = t -Bu, R 2 = F, X = OH; 28, R 1 = R 2 = Ph, X = OH), O( t -Bu 2 SnOSiPh 2 ) 2 O ( 29 ), t -Bu 2 Sn(OSiMe 2 CH 2 ) 2 ( 30 ), and t -Bu 2 SnOSiF- t -BuOSn- t -Bu 2 OSi t -Bu 2 O ( 31 ) is described. The compounds were characterized by means of multinuclear NMR spectroscopy and Mössbauer spectroscopy. The molecular structures of the eight-membered stannasiloxane rings 5, 7, 9, 21, and 29 were determined by X-ray analysis. On the basis of NMR and electrospray mass spectrometry a mechanism is proposed involving protonated species for the redistribution reaction between 5 and 21 .