Ruthenium-(II) and -(III) complexes of a ditertiary stibine ligand. The effect of co-ordination on stibine ligand geometry†

Abstract

The complexes trans-[RuX₂{Ph₂Sb(CH₂)₃SbPh₂}₂] (X = Cl, Br or I) have been prepared from [Ru(dmf)₆][CF₃SO₃]₃, LiX and the distibine (dmf = dimethylformamide), and characterised by chemical analysis and UV/VIS spectroscopy. They are oxidised by HNO₃ in HBF₄ solution to trans-[RuX₂{Ph₂Sb(CH₂)₃SbPh₂}₂]BF₄. The latter have been characterised by similar techniques, and the Ru^II–Ru^III redox potentials established electrochemically. The crystal structures of Ph₂Sb(CH₂)₃SbPh₂ and trans-[RuBr₂{Ph₂Sb(CH₂)₃SbPh₂}₂]·2CH₂Cl₂ [Ru–Sb 2.5758(5), 2.6043(8); Ru–Br 2.5770(7) Å] have been determined. Using data from the Cambridge Crystallographic Database on transition metal SbPh₃ complexes, the present complexes, and those of Ph₂SbCH₂SbPh₂, the effect of co-ordination on the C–Sb–C angles and the Sb–C distances has been examined. A correlation of increased C–Sb–C angles with decreased Sb–C distances is observed on co-ordination.