Synthesis and structures of new mono- and multi-nuclear benzyltin carboxylates and phosphinates: a novel dibenzyltin phosphinate stabilized by intramolecular hydrogen bonding

Abstract

The reaction of dibenzyltin dichloride 1 with 2 mol equivalents each of AgO₂P(C₆H₁₁)₂ and (C₆H₁₁)₂PO₂H afforded the novel monometallic complex Sn(CH₂Ph)₂[O₂P(C₆H₁₁)₂]₂[HO₂P(C₆H₁₁)₂]₂ 2. When 1 was treated with 2 mol equivalents of AgO₂P(C₆H₁₁)₂ only the trinuclear O-capped cluster [{Sn(CH₂Ph)(OH)[O₂P(C₆H₁₁)₂]}₃O][O₂P(C₆H₁₁)₂] 4 was obtained by an Sn–C bond cleavage via an intermediate formulated as {Sn(CH₂Ph)(OH)[O₂P(C₆H₁₁)₂]₂}₂ 3. In the reaction with silver carboxylates the type of product isolated depends on the carboxylic acid used. Thus the ‘ladder’ {[(PhCH₂)SnO·O₂CMe]₂(PhCH₂)Sn(O₂CMe)₃}₂ 5, the ‘hexagonal prismanes’ [(PhCH₂)SnO·O₂CR]₆ (R = Me 6, Bu^t 7, C₅H₄N 8, CHCMe₂ 9 or CHPh₂ 10) and the mononuclear compound Sn(CH₂Ph)₂(O₂CCHPh₂)₂ 11 have been isolated. X-Ray structural analysis confirmed the identities of 2, 4·CHCl₃, and 5·2CH₂Cl₂. In 2 the mononuclear structure is stabilized by internal hydrogen bonding between P–OH and PO of the co-ordinated phosphinic acid and the phosphinate, respectively, from the same molecule. Compound 4 has a tristannoxane ring with a capping oxygen, whereas in 5 the stannoxane skeleton is that of a ‘ladder’ with three different types of tin.