Tin–bromine bond lengths and mössbauer quadrupole splittings of tin(IV) bromide complexes. Crystal structure of pyridinium tetrabromodiphenylstannate(IV)

Abstract

Mössbauer and crystallographic data have been obtained for pyridinium tetrabromodiphenylstannate(IV). The Sn atom is six-co-ordinated in the centrosymmetric trans-[SnBr₄Ph₂]^2– anion with bond distances Sn–Br(1) 2.7592(3), Sn–Br(2) 2.7737(3) and Sn–C(11) 2.158(3)Å. The average Sn–Br distance for five octahedral tin(IV) bromide complexes, SnBr₄L₂, is related to the partial quadrupole splitting (p.q.s.) of the ligands by means of the correlation d(Sn–Br)/Å=(–0.048 ± 0.002)(4 p.q.s.)+(2.589 ± 0.003). The relationship rationalises the experimental Sn–Br distances and quadrupole splitting data in terms of the donor properties of the auxiliary ligands (L) in such a way that weak donor ligands give rise to shorter Sn–Br distances. The Mössbauer quadrupole splitting can be useful in the assignment of v(SnBr) vibrations in the IR and Raman spectra of trans-SnBr₄L₂ compounds.