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

A series of C,O-chelated organotin(IV) alkoxides, L ₂ PhSnO ^t Bu (4), L ₂ PhSnOMe (6), L ₂ Sn(O ^t Bu) ₂ (11), and siloxides L ₂ PhSnOSiPh ₃ (3), L ₂ Sn(OSiPh ₃ ) ₂ (10) (L=[2-(CH ₂ O) ₂ CH]C ₆ H ₄ ), was prepared by salt elimination reactions. They were obtained from the organotin(IV) iodides L ₂ PhSnI (1) or L ₂ SnI ₂ (2) upon reactions with ^t BuOK, MeONa or Ph ₃ SiONa, respectively, in dry THF or methanol. Under non-inert conditions, compounds 4 and 6 undergo combined hydrolysis and condensation to give the hexaorganodistannoxane (L ₂ PhSn) ₂ O (5). The stannoxane 5 is easily hydrolysed to L ₂ PhSnOH (7), which quickly converts back when heated. Basic hydrolysis of diiodide 2 produces the cyclic oxide (L ₂ SnO) ₃ (8). Its reaction with an equimolar amount of Ph ₃ SiONa gives only a mixture of the expected L ₂ SnI(OSiPh ₃ ) (9), 10 and the precursor, 2. Yet, 8 shows a unique reactivity pattern when combine with m-tolyl boronic acid, affording stannaboroxane (L ₂ SnO) ₂ 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.
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