RUTHENIUM-(II) AND RUTHENIUM-(III) COMPLEXES OF A DITERTIARY STIBINE LIGAND - THE EFFECT OF COORDINATION ON STIBINE LIGAND GEOMETRY

The complexes trans-[RuX2{Ph2Sb(CH2)(3)SbPh2}(2)] (X = Cl, Pr or I) ha ve been prepared from [Ru(dmf)(6)][CF3SO3](3), LiX and the distibine ( dmf = dimethylformamide), and characterised by chemical analysis and U V/VIS spectroscopy They are oxidised by HNO3 in HBF4 solution to trans -[RuX2{Ph2Sb(CH2)(3)SbPh2}(2)]BF4. The latter have been characterised by similar techniques, and the Ru-II-Ru-III redox potentials establish ed electrochemically. The crystal structures of Ph2Sb(CH2)(3)SbPh2 and trans-[RuBr2{Ph2Sb(CH2)(3)SbPh2}(2)]. 2CH(2)Cl(2) [Ru-Sb 2.5758(5), 2 .6043(8); Ru-Br2.5770(7) Angstrom] have been determined. Using data fr om the Cambridge Crystallographic Database on transition metal SbPh3 c omplexes, the present complexes, and those of Ph2SbCH2SbPh2, the effec t of co-ordination on the C-Sb-C angles and the Sb C distances has bee n examined. A correlation of increased C-Sb C angles with decreased Sb -C distances is observed on co-ordination.