Synthesis, characterization and reactivity of oxomoIybdenum(V) complexes with ONS and NNS donors

摘要

The monomeric oxomolybdenum(V) complexes, [MoOLCl_2] la-ld [HL = S-benzyl/methyl 3-(2-pyridyl)methylenedithiocarbazate (la and lb), or N-methyl-S-benzyl/methyl 3-(2-hydroxyphenyt)methylenedithiocarbazate (lc and ld) are synthesized by the reaction ofMoOCl_5~(2-) with HL ligands. All these complexes show magnetic moment of about 1.7B.M. The complexes, 1a and 1b, exhibit rhombic g-tensor anisotropy (like xanthine oxidase) whilst 1c and 1d show axial spectrum. The above complexes undergo irreversible electrochemical reduction furnishing Mo(IV) species and the potentials are dependent on the S-substituents. Reactions of MopX_5~(2-) (X= Cl or Br) with H_2 L~1 [H_2 L~l = S-methyl 3-(5-R-2-hydroxyphenyl) methylenedithiocarbazate] (R = H CH_3, Cl Br) produce complexes of thiolatobndged dimers. [Mo_2O_2L_2~1X_2], which show sub-normal magnetic moments at room temperature. The metal-centred irreversible oxidation and reduction of these complexes how expected dependence on the R-substituents of the saltcyl phenyl ring of the ligands.