SYNTHESIS AND SPECTRAL STUDIES OF NOVEL DIOXOMOLYBDENUM(VI) HETEROCHELATES INVOLVING SOME SCHIFF-BASES DERIVED FROM 4-ACETYL-3-METHYL-1-PHENYL-2-PYRAZOLIN-5-ONE

The synthesis and physico-chemical studies of some <(cis)under bar>-di oxomolybdenum(VI) heterochelates with potentially bidentate and tetrad entate Schiff base ligands derived from 4-acetyl-3-methyl-1-phenyl-2-p yrazolin-5-one have been described. The bidentate Schiff bases were sy nthesized by the reaction of 4-acetyl-3-methyl-1-phenyl-2-pyrazolin-5- one with aromatic amines, viz., (o) under bar-anisidine, (m) under bar -anisidine, (p) under bar-anisidine, (o) under bar-phenetidine, (p) un der bar-phenetidine, (o) under bar-toluidine and (m) under bar-toluidi ne in ethanol. For tetradentate Schiff bases, amines such as, (m) unde r bar-phenylenediamine, (p) under bar-phenylenediamine and benzidine w ere used. The bi- and tetradentate Schiff bases thus obtained were rea cted with the parent compound, bis(acetylacetonato)dioxomolybdenum(VI) , in the stoichiometric ration (2:1 for bidentate and 1:1 for tetraden tate Schiff bases) to give diamagnetic molybdenum(VI) mononuclear comp lexes of the compositions [MoO2(L)(2)] (where LH = bidentate Schiff ba se) and the ligand bridged binuclear complexes [{MoO2(OEt)}(2)(L)] (wh ere LH(2) = tetradentate Schiff base derived from benzidine or (p) und er bar-phenylenediamine) and [MoO2(AMPHP-MPHD)] (where AMPHP-MPHD = Sc hiff base of (m) under bar-phenylenediamine). Suitable structures have been proposed for these complexes.