Dithiolate–hydrazido(2-) molybdenum complexes: synthesis and structure

Reaction of [MoO2(acac)2] with an excess of X(CH2CH2SH)2 where X=O, S leads to the formation of mononuclear complexes [MoO2{X(CH2CH2S)2}]: (1a) for X=O and (1b) for X=S. The complexes 1a and 1b react with organohydrazines in methanol, MeCN or THF to give the family of hydrazido(2-)-oxo-molybdenum compounds [MoO(NNRR′){X(CH2CH2S)2}]: (2a) for R=R′=Me and X=O; (2b) for R=R′=Me and X=S; (2c) for R=Me, R′=Ph and X=O; (2d) for R=Me, R′=Ph and X=S. Similar reaction carried out in CH2Cl2 with an excess of NH2NMe2 leads to the formation of 2a and hydrazinium salt [NH2N(CH2Cl)Me2]Cl consisting of tetrahedral cations bonded by hydrogen bonds to chloride ions as shown by X-ray studies. The X-ray crystal structures of 2a and 2b have been determined. These molecules have a distorted trigonal bipyramidal configuration with the hydrazido(2-) ligand bonded linearly in a trans position to either the ether oxygen or the thioether sulfur atoms of the dithiolate ligand. Me3SiCl causes abstraction of the oxo group in 2a–2d to create the six-coordinate compounds [MoCl2(NNRR′){X(CH2CH2S)2}] (3a–3d), respectively. The chlorides in 3d can be easily substituted by oxygen and nitrogen donor ligands to give the new compounds [Mo(di-t-Bu-cat)(NNRR′){X(CH2CH2S)2}] (4) and [Mo(NNRR′)2{X(CH2CH2S)2}] (5), respectively.