Recent Developments in the Chemistry of Spacer Bridged Distannoxanes

Depending on the identity of Z and R the reaction of the spacer bridged tetrachloroditin compounds [R(Cl2)SnCH2]2Z with (t-Bu2SnO)3 or their corresponding organotin oxides {[R(O)SnCH2]2Z} n provides either double ladders {{[R(Cl)SnCH2]2Z}O}4 (Z = CH2; R = CH2SiMe3, CH2CMe3), dimeric tetraorganodistannoxanes { {[R(Cl)SnCH2]2Z}O}2 (Z = Si(Me2), Si(Me2)CzCSi(Me2), Si(Me2)OSi(Me2); R = CH2SiMe3), or mixtures of both of these structures (Z = CH2CH2; R = CH2SiMe3, CH2CMe3, CH2CHMe2). The chlorine atoms can be replaced stepwise by other electronegative groups such as hydroxide or acetate. Preliminary studies on the catalytic activity of some tetraorganodistannoxanes with alkylidene spacers are reported.