Reactions of [t-Bu(2)SnO](3) with [t-BuX(2)Si](2) (X = F, Cl). Syntheses and Structures of Novel Stannasiloxanes and of [(t-Bu(2)FSn)(2)O](2), the First Fluorine-Containing Tetraorganodistannoxane(,).

Di-tert-butyltin oxide, (t-Bu(2)SnO)(3) (1), reacts with 1,2-di-tert-butyltetrachlorodisilane, (t-BuCl(2)Si)(2) (2), to provide the stannasiloxane t-Bu(2)Sn[OSi(OSnCl-t-Bu(2))-t-Bu](2) (4, racemate). The reaction of 1 with 1,2-di-tert-butyltetrafluorodisilane, (t-BuF(2)Si)(2) (3), provides the stannasiloxane [t-Bu(F)SiOSn-t-Bu(2)](2)O (5, meso/racemate mixture) and the tetraorganodistannoxane [t-Bu(2)(F)SnOSn(F)-t-Bu(2)](2) (6). Under loss of (1)/(3) mole equiv of 1, the stannasiloxane 5 is transformed into t-Bu(2)Sn[OSi(F)-t-BuSi(F)-t-BuO](2)Sn-t-Bu(2) (7). Its ten-membered ring structure was elucidated by X-ray analysis. In solution, 7 forms the five-membered ring t-Bu(2)Sn[OSi(F)-t-Bu](2) (7a). The dimeric nature of 6 was confirmed by its crystal structure determination. In solution, 6 exhibits a unique valence tautomerism as evidenced by (19)F and (119)Sn NMR spectroscopy.