Metal chelates of bioinorganic and catalytic relevance: Synthesis, magnetic and spectral studies of some mononuclear and binuclear oxovanadium(IV) and dioxotungsten(VI) complexes involving Schiff bases derived from 4-butyryl-3-methyl-1-phenyl-2-pyrazolin-5-one and certain aromatic amines

Synthesis of two series of metal chelates: (i) mononuclear chelates of comp ositions, [VO(L-1)(2)].H2O and [WO2(SCN)(C2H5OH)(2)(L-1)], (where L1H = N-( 4'-butyrylidene-3'-methyl-1'-phenyl-2'-pyrazolin-5'-one)-p-anisidine (BUMPH P-PAH, I), N-(4'-butyrylidene-3'-methyl-1'-phenyl-2'-pyrazolin-5'-one)-o-ph enitidine (BUMPHP-OPH, II), N-(4'-butyrylidene-3'-methyl-1'-phenyl-2'-pyraz olin-5'-one)-m-phenetidine (BUMPHP-MPH, III) or N-(4'-butyrylidene-3'-methy l-1'-phenyl-2'-pyrazolin-5'-one)-m-toluidine (BUMPHP-MTH, IV) or N-(4'-buty rylidene-3'-methyl-1'-phenyl-2'-pyrazolin-5'-one)-p-toluidine (BUMPHP-PTH V ), [VO(L-2)].H2O, and [WO2(SCN)(L2H)] (where L2H2 = N,N'-bis-(4'-butyrylide ne-3'-methyl-1'-phenyl-2'-pyrazolin-5'-one)-o-phenylenediamine (BUMPHP-OPHD H2, VI) or N,N'-bis-(4'-butyrylidene-3'-methyl-1'-phenyl-2'-pyrazolin-5'-on e)-m-phenylenediamine (BMPHP-MPHDH2, VII) and VO(L-2')(H2O)] (where L-2'H-2 = N,N'-bis(4'-butyrylidene-3'-methyl-1'-phenyl-2'-pyrazolin-5'-one)-m-phen ylenediamine (BMPHP-MPHDH2, VII), and (ii) binuclear chelates of compositio ns, [{VO(H2O)(OH)}(2) L-3] and [{WO2(SCN)(H2O)}(2)(L-3)], where L3H2 = N,N' -bis-(4-butyrylidene-3-methyl-1-phenyl-2-pyrazolin-5-one)-p-phenylenediamin e (BMPHP-PPHDH2, VIII) or N,N'-bis-(4-butyrylidene-3-methyl-1-phenyl-2-pyra zolin-5-one)-benzidine (BMPHP-BZH(2), IX) are described. The resulting chel ates have been characterized by elemental analyses, molar conductance, deco mposition temperature and magnetic measurements, electron spin resonance/ H -1-NMR, infrared and electronic spectral studies. The oxovanadium(IV) compo unds with ligands, BUMPHP-PPHDH2 and BUMPHP-BZH(2) exhibit subnormal magnet ic moments. Structures involving . . .V=O . . .V=O . . . chain for oxovanad ium(IV) complexes, and tentative structures involving cis-WO2 have been pro posed for dioxotungsten(VI) complexes.