SYNTHESIS AND CHARACTERIZATION OF 5-CO-ORDINATE RHENIUM(III) COMPLEXES WITH 2-(DIPHENYLPHOSPHINO)-ETHANETHIOLATE AND MONOTHIOLATE LIGANDS -CRYSTAL-STRUCTURE OF [RE(PH2PCH2CH2S)2(PHCH2S)]

A new series of five-co-ordinate rhenium(III) complexes containing the mixed S,P-bidentate 2-(diphenylphosphino)ethanethiolate ligand togeth er with a monothiol RSH [R = Ph2PCH2CH2, Ph2P(O)CH2CH2, PhCH2, Ph or P r(n)] have been synthesized and characterized. This Re(III)P2S3 series was prepared by substitution reactions of [Re(III)Cl3(MeCN)(PPh3)2], a pre-reduced rhenium(III) precursor, by addition of 2-(diphenylphosph ino)ethanethiol and the corresponding monothiol. Formation of these co mpounds was verified by elemental analysis and H-1 and P-31 NMR and po sitive-ion fast atom bombardment mass spectroscopy. The complexes were found to be diamagnetic, neutral and stable. They exhibit a trigonal- bipyramidal geometry, where three sulfur atoms occupy the equatorial p lane and two phosphorus atoms are positioned at the apices. The X-ray structural analysis of ,kappaP](phenylmethanethiolato-kappaS)rhenium(I II) revealed that this compound crystallizes in the monoclinic space g roup P2(1)/c with Z = 8, a = 21.011(9), b = 20.397(9), c = 16.289(7) a ngstrom, beta = 107.13(5)-degrees, R = 0.050, R' = 0.063, by using 564 4 observed reflections. The above data further demonstrate the prefere nce of a five-co-ordinate configuration when the P2S3 donor-atom set i s available for co-ordinating rhenium(III).