Varieties of Concurrency Control in IMS/VS Fast Path.

Di-tert-butyltin oxide, ((t)Bu(2)SnO)(3), reacts with R(2)SnCl(2) to give mixed distannoxanes (t)Bu(2)(Cl)SnOSn(Cl)R(2)(2) (1, R = Me; 2, R = Et; 3, R = (i)Pr; 4, (n)Bu) whereas di-tert-butyltin hydroxide chloride, (t)Bu(2)Sn(OH)Cl(2), reacts with (n)Bu(2)SnO(n) to give the chlorohydroxydistannoxane (t)Bu(2)(OH)SnOSn(Cl)(n)Bu(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 R(2)SnCl(2) (R = Me, (i)Pr, (n)Bu) to solutions of 1, 3, and 4, respectively, causes displacement of (t)Bu(2)SnCl(2) with concomitant formation of ((t)Bu(2)SnCl(2))(R(2)SnO)(2)(R(2)SnCl(2)) and (R(2)SnCl(2))(R(2)SnO)(2)(R(2)SnCl(2)). Thus 1-4 can be regarded as (R(2)SnO)(2) units which are stabilized by two (t)Bu(2)SnCl(2) molecules. NMR data indicate that reaction between ((t)Bu(2)SnO)(3) and (t)Bu(2)SnCl(2) gives rise to an equilibrium involving linear (t)Bu(2)Sn(Cl)OSn(Cl)(t)Bu(2) and the novel three-quarter ladder compound (t)Bu(2)SnCl(2)(t)Bu(2)SnO(2). Formation of trinuclear tin species is also evident from electrospray mass spectrometric studies.