Synthesis and Spectral Studies of Some Oxomolybdenum(V) and Dioxomolybdenum(VI) Complexes of the Azo Dye Derived from 4-Amino- 2,3-dimethyl-1-phenyl Pyrazol-5-one

Abstract

Some novel oxomolybdenum(V) complexes of the type MoOLXCl₂ (L = BPAAP, X = Cl, NCS, ClO₄ or NO₃) and dioxomolybdenum(VI) complexes of the type MoO₂LX₂ (L = BPAAP, X = Cl, ClO₄ or ½SO₄) and MoO₂LXCl (L = BPAAP, X = NCS or NO₃) with the azo dye, 2,3-dimethyl-1-phenyl-4-(2-hydroxy-5-bromophenyl azo) pyrazol-5- one(bromophenolazoantipyrine-BPAAP) derived from 4-aminoantipyrine, have been synthesized and characterized by elemental analysis, magnetic and conductance measurements, IR, electronic, ESR and X-ray diffraction spectral studies. Magnetic and ESR spectral data suggest that the Mo(V) complexes are monomeric with molybdenum in the pentavalent state. The electronic spectral bands of these complexes at 650, 500 and 390nm are assigned to b₂→e, b₂→b₁ and O(π) →d(Mo) transitions respectively The IR data confirms the neutral bidentate behaviour of the ligand and the presence of MoO³⁺ moiety in Mo(V) complexes and cis-MoO₂ moiety in Mo(VI) complexes. The XRD pattern of one of the complexes studied suggest orthorhombic structure with unit cell dimensions a = 10.485 Å, b = 13.829 Å and c = 17.89 Å.