Synthesis and characterisation of tin(IV) fluoride complexes of phosphine and arsine oxide ligands

Abstract

The pseudooctahedral complexes [SnF 4L 2] (L = Ph 3PO, Ph 3AsO, Me 3PO, Me 3AsO) and [SnF 4(L–L)] (L–L = Ph 2P(O)CH 2P(O)Ph 2, o-C 6H 4(P(O)Me 2) 2, o-C 6H 4(P(O)Ph 2) 2) have been prepared from [SnF 4(MeCN) 2] and the appropriate ligand in dichloromethane solution. The complexes have been characterised by analysis, IR, 1H, 31P{ 1H}, 19F{ 1H} and 119Sn NMR spectroscopy as appropriate; the NMR studies showing that the complexes of the monodentate ligands exist as mixtures of trans and cis isomers in solution. The crystal structures of trans-[SnF 4(OPMe 3) 2], [SnF 4{ o-C 6H 4(P(O)Ph 2) 2}] · CH 2Cl 2 · H 2O and [ o-C 6H 4(P(O)Ph 2) 2] · CH 2Cl 2 have been determined. Comparison of the structural and NMR spectroscopic data of the tetrafluorotin complexes with those of related [SnX 4L 2] (X = Cl, Br or I) shows that SnF 4 is the strongest Lewis acid in the series towards hard Lewis bases.