Synthesis and characterization of some new Cu(II) complexes of azo dyes derived from 1,2-dihydro-1,5 -dimethy1-2-pheny 1-4-amino-3H-pyrazol-3-one

85-89Some novel complexes of the ligands 1,2-dihydro-1,5- dimethyl-2-phenyl-4-(2-hydroxy-5-methyl phenylazo)-3H-pyrazol- 3-one (CAAPH) and 1,2-dihydro-l,5-dimethyl-2-phenyl-4- (2-hydroxy-5-chlorophenylazo)-3H-pyrazol-3-one (CPAAPH) with Cu(II) having the formulae [Cu(LH)Cl2), [CuLH(Ac)2] [CuLH(NO3)2 ] [CuLH(SO4)], [CuLH(ClO4)2 ], [CuLH(NCS)Cl] and [Cu(L H)Cl2], [CuL’H (Ac2)], [CuL’ - (NO3)2], [CuL’H (SO4)], [CuL’H (ClO4)2], [CuL’H (NCS)Cl] (LH=CAAPH and L H =CPAAPH) have been synthesized and characterized by elemental analysis, IR, electronic, ESR, NMR, magnetic, conductance measurements and cyclic voltammetric studies. The ligands are found to behave in a neutral bidentate manner. All the complexes are non-electrolytes and square planar with magnetic moment ranging from 1.79 to 1.88 B.M. The X-band ESR spectra of the complexes [Cu(CAAPH)Cl2], [Cu(CAAPH)-(Ac2], [Cu(CAA PH)(NO3)2], [Cu (CAA PH)(SO4)], [Cu(CPAAPH)(ClO4)2] and [Cu(CPAAPH)(NCS)Cl] are seen to be characteristic of Cu(II) in the ligand field with axial symmetry. The complexes [Cu (CAAPH)(SO4)] and [Cu(CPAAPH)Cl2)] are found to be orthorhombic with the unit cell dimensions such as a=5.8564 , Å, b=9.4817 Å and c=12.8383 Å; and a=5.3029 Å, b=10.2028 Å and c=11.6127 Å, respectively. The cyclic voltammograms of [Cu(CAAPH)Cl2] and [Cu(CPAAPH)(Cl O4)2] show quasi-reversible peaks which indicates that metal-ligand linkage is more covalent in nature29