Di-tert-butyltin oxide, ((Bu2SnO)-Bu-t)(3), reacts with R2SnCl2 to give mixed distannoxanes [Bu-t(2)(Cl)SnOSn(Cl)R-2](2) (1, R = Me; 2, R = Et; 3, R = Pr-i; 4, Bu-n) whereas di-tert-butyltin hydroxide chloride, [(Bu2Sn)-Bu-t(OH)Cl](2), reacts with [(Bu2SnO)-Bu-n](n) to give the chlorohydroxydistannoxane [Bu-t(2)(OH)SnOSn(Cl)Bu-n(2)](2), 5; the dimeric nature of these tetraorganodistannoxanes was confirmed by crystal structure determinations of 1 and 4. Although stable in the solid state, compounds 1-4 rearrange to give a number of distannoxanes in solution. Addition of R2SnCl2 (R Me, Pr-i, Bu-n) to solutions of 1, 3, and 4, respectively, causes displacement of (Bu2SnCl2)-Bu-t with concomitant formation of [((Bu2SnCl2)-Bu-t)(R2SnO)(2)(R2SnCl2)] and [(R2SnCl2)(R2SnO)(2)(R2SnCl2)]. Thus 1-4 can be regarded as (R2SnO)(2) units which are stabilized by two (Bu2SnCl2)-Bu-t molecules. NMR data indicate that reaction between ((Bu2SnO)-Bu-t)(3) and (Bu2SnCl2)-Bu-t gives rise to an equilibrium involving linear [(Bu2Sn)-Bu-t(Cl)OSn(Cl)Bu-t(2)] and the novel three-quarter ladder compound [(Bu2SnCl2)-Bu-t][(Bu2SnO)-Bu-t](2). Formation of trinuclear tin species is also evident from electrospray mass spectrometric studies.