A New Class of Eight-Membered Sn2P2O4 Heterocycles. Crystal Structure and Electrolytic Dissociation in Solution of cyclo-[R2Sn(OPPh2O)2SnR2](O3SCF3)2 (R = Me, t-Bu)

The syntheses of cyclo-[R2Sn(OPPh2O)2SnR2](O3SCF3)2 (R = Me (1), t-Bu (2)) by the consecutive reaction of R2SnO (R = Me, t-Bu) with triflic acid and diphenylphosphinic acid are presented. In the solid state, 1 and 2 were investigated by 119Sn MAS and 31P MAS NMR spectroscopy as well as X-ray crystallography and appear to exist as ion pairs of cyclo-[R2Sn(OPPh2O)2SnR2]2+ dications and triflate anions. In solution, 1 and 2 are involved in extensive equilibria processes featuring cationic diorganotin(IV) species with Sn−O−P linkages, as evidenced by 119Sn and 31P NMR spectroscopy, electrospray mass spectrometry, and conductivity measurements.