Organotin(IV) Alkoxides, Siloxides, and Related Stannoxanes. Characterisation and Thermogravimetric Studies.

A series of C,O-chelated organotin(IV) alkoxides, LPhSnOBu (4), LPhSnOMe (6), LSn(OBu) (11), and siloxides LPhSnOSiPh (3), LSn(OSiPh) (10) (L=[2-(CHO)CH]CH), was prepared by salt elimination reactions. They were obtained from the organotin(IV) iodides LPhSnI (1) or LSnI (2) upon reactions with BuOK, MeONa or PhSiONa, respectively, in dry THF or methanol. Under non-inert conditions, compounds 4 and 6 undergo combined hydrolysis and condensation to give the hexaorganodistannoxane (LPhSn)O (5). The stannoxane 5 is easily hydrolysed to LPhSnOH (7), which quickly converts back when heated. Basic hydrolysis of diiodide 2 produces the cyclic oxide (LSnO) (8). Its reaction with an equimolar amount of PhSiONa gives only a mixture of the expected LSnI(OSiPh) (9), 10 and the precursor, 2. Yet, 8 shows a unique reactivity pattern when combine with m-tolyl boronic acid, affording stannaboroxane (LSnO)OB(m-tol) (12). All the isolated species were characterised in solution by NMR spectroscopy and mass spectrometry. The solid-state molecular structures of 1-5, 10-12 were established by single-crystal X-ray diffraction (XRD). Additionally, thermogravimetric analysis of 3-5, 8, 10, and 12 was conducted.