Complexes of molybdenum(III) with sulphur-donor ligands

Abstract

Reaction of [Mo₂O₂Cl₂(H₂O)₆], (I), with ligands L gives complexes [MO₂O₂(H₂O)_xL_y][L =S-methyl-L-cysteinato hydrochloride (x= 4, y= 2). (II), and 2-aminoethanethiolato hydrochloride (x= 6, y= 2)(III)], [Mo₂(OH)₂L₄][L = 4-mercaptotoluene-3-thiolato. (IV), and 2-aminobenzenethiolato, (V)], [MoL₃]₂(VI; L =NN-diethyldithiocarbamato). and [Mo₂OCIL₃](VII; L = 2-hydroxyethanethiolato). l.r., u.v., visible, n.m.r., and e.s.r. spectra and magnetic susceptibilities of the complexes are reported. Structures are proposed. The complexes are bi- or poly-nuclear. With bidentate thiols. sulphur bridges are formed between molybdenum atoms. In reactions with thiols, oxide bridges are readily replaced probably via initial protonation of bridging oxide. The complexes are discussed in the general context of molybdenum chemistry. The tendency to form sulphur-bridged complexes is greater with molybdenum (III) than with molybdenum(V). Sulphur bridges are less labile than oxygen bridges.