Activation of E–Cl bonds (E = C, Si, Ge and Sn) by a C,N-chelated stannylene

Abstract

The reactivity of (L^CN)₂Sn (1) (where L^CN is 2-(N,N-dimethylaminomethyl)phenyl-) towards various substrates containing E–Cl bond(s) has been studied (E = C, Si, Ge and Sn). Alkyl chlorides like chloroform or dichloromethane reacts with 1 to form (L^CN)₂SnCl₂ and unidentified by-products in poor yields. The reaction of benzoyl chloride with 1 at low temperature yielded a thermally unstable product (L^CN)₂Sn(Cl)C(O)Ph (2) which was isolated and characterized by both multinuclear NMR spectroscopy and X-ray diffraction techniques. The vicinity of the central tin atom in 2 reveals trigonal bipyramidal geometry. Attempts to oxidize 2 by dioxygen to give the corresponding organotin(IV) benzoate failed. On the other hand, the reaction of the in situ prepared (L^CN)₂SnO (synthesized by the reaction of 1 with dioxygen) with PhCOCl resulted in the formation of the desired organotin(IV) benzoate (L^CN)₂Sn(Cl)C(O)OPh (3). The reaction of 1 with Ph₃GeCl yielded triphenylgermyl-substituted diorganotin(IV) chloride (L^CN)₂Sn(Cl)GePh₃ (4) which subsequently gave mixed diorganotin(IV) chloride-oxide [(L^CN)₂SnCl]₂O (5) upon loss of the GePh₃ moiety in the air. When the same reaction was carried out in benzene instead of chloroform a unique [Ph₃Ge]₄[Sn₆O₈] cluster (6) was obtained. Similarly, the reaction of 1 with Ph₃SiCl provided triphenylsilyl-substituted diorganotin(IV) chloride (L^CN)₂Sn(Cl)SiPh₃ (7) which was then oxidized to (L^CN)₂Sn(Cl)OSiPh₃ (8). The unprecedented reaction of 1 with (n-Bu)₃SnCl provided the distannane (L^CN)₂Sn(Cl)SnBu₃ (9) which could be oxidized by dioxygen to a distannoxane (L^CN)₂Sn(Cl)OSnBu₃ (10). In addition, the solid-state structures of 3, 5, 6 and 8 were determined by the X-ray diffraction techniques.