Phosphorus-31 and tin-119 NMR studies on tin(IV) halides and their adducts

Abstract

Tin-119 NMR spectra have been recorded for SnX 4 (X = Cl, Br, I) and mixtures thereof. All fifteen possible SnCl xBr yI z (x + y + z = 4) species were observed. Tin-119 NMR spectra were observed for SnX − 5 and SnX 2− 6 (X = Cl, Br) and for an equimolar mixture of SnCl 2− 6 and SnBr 2− 6 which gave all ten possible isomers of [SnCl xBr 6−x] 2− in the statistical distribution. Phosphorus-31 and tin-119 NMR spectra were observed for SnX 4(PBu 3) 2 (X = Cl, Br) and a mixture gave all six possible trans phosphine isomers in the statistical distribution. [SnX 5(PBu 3)] − (X = Cl, Br) species show some disproportionation, although the [SnX 5(PBu 3)] − ion is the dominant species in solution. A mixture of [SnCl 5(PBu 3)] − and [SnBr 5-(PBu 3)] − gave a complex mixture in solution, but all twelve isomers of the [SnCl 5Br 5−x(PBu 3)] − series were identified. The well known pairwise additivity model fits well within the tetrahalide or hexahalide anion series and it is shown that the chemical shift of tin both tetrahedral and octahedral environments may be predicted from a single set of interaction parameters if geometrical factors are taken into account. The same interaction parameters are of use in identifying the mixed tin halide-phosphine complexes.