HYPERVALENT MONOORGANYLTIN AND DIORGANYLTIN(IV) FLUORIDE COMPLEXES - A F-19 AND SN-119 STUDY OF INTERMOLECULAR AND INTRAMOLECULAR DYNAMICS IN SOLUTION

Reactions of fluoride ion with diorganyltin(IV) dichlorides R2SnCl2 (R = Ph, Me, (n)Bu, (t)Bu) and monoorganyltin(IV) halides RSnCl3 (R = Ph, Me, nBu) in dichloromethane solution have been studied using variable-temperature F-19 and Sn-119 NMR spectroscopy. A number of hypervalent tin species are identified in solution including [Ph2SnF3]-, [Ph2SnClF2]-, and [Ph2SnCl2F]-, which are stereochemically rigid on the NMR time scale at -100-degrees-C but fluxional at about -80-degrees-C. The fluoride in [Ph2SnCl2F]- and [Ph2SnClF2]-shows a smaller apicophilicity than the chloride. Addition of fluoride ion causes appreciable R group migration for R = Ph.