Département de chimie moléculaire

{The structural and electronic properties as well as the catalytic activity toward sulfoxidn. of two new vanadium complexes have been investigated. They both possess in their coordination sphere two alkyl thiolate ligands: a dioxido VV complex VO2LNS2-HNEt3 (1) LNS2 = 2,2'-pyridine-2,6-diyl-bis-1,1'-diphenylethanethiol and an oxido VIV complex VOLN2S2 (2) LN2S2 = 2,2'-2,2'-bipyridine-6,6'-diyl-bis-1,1'-diphenylethanethiol. The X-ray structure of 1 has revealed that the VV metal ion is at the center of a distorted trigonal bipyramid. The optimized structure of 2 obtained by DFT calcns. displays a square-pyramidal geometry, consistent with its EPR spectrum characterized by an axial S = 1/2 signal g⊥ = 1.988, g‖ = 1.966, Ax(V) = 45 × 10-4 cm-1