(^119)Sn N.M.R. Studies of the reactions of some organotin(IV) compounds

Abstract

The chemistry of some organotin (IV) halides, and in particular their acceptor properties in solution, has been investigated by (^119) Sn n.m.r. spectroscopy. Mono- and di-organotin (IV) chlorides and bromides were found to coordinate either one or two halide ions whereas tri organotin (IV) halides would coordinate only one. The tetraorganotin (IV) species showed no acceptor properties whatsoever, even in solution. The complexes thus formed were isolable, and could therefore be investigated by other conventional techniques. Reactions between organotin (IV) chlorides and the powerful Lewis acids, SbC1 (_5) and BC1 (_3) were investigated in solution by (^ll9sn) and (^11) (where appropriate) n.m.r. spectroscopy. Exchange between organogroups from the organotin (IV) compound and chloride ions from the Lewis acid occurred in most cases, and interesting series of chemical shifts were obtained. Solution (^)119Sn n.m.r. spectroscopy was also used to investigate the reaction between organotin (IV) chlorides and the acidic solvent systems, 100% H(_2)S0(_4), 25-oleum, and chlorosulphuric acid. Although other conventional techniques could not be employed to assist product identification, the chemical shifts obtained were very informative, and in the majority of cases could be rationalised on the basis of the reactions expected in these solvents. Several solid adducts were prepared from reactions between organotin (IV) chlorides and the pyridine bases, pyridine, dipy, and phen. Although the adducts themselves were easily prepared, results from (^119) Sn n.m.r. solution (or solid-state) investigations proved generally disappointing. This was due to the very low solubility of the adducts even in solvents or quite high polarity, and probably to relaxation time problems in solid-state n.m.r.