title: New 'side-off' coordination asymmetric homobinuclear Ni(II) and heterobinuclear Ni(II)Zn(II) complexes as models for hydrolysis of p-nitrophenylphosphate: synthesis, characterization and electrochemical studies.
abstract: A series of new phenol based coordination asymmetric side-off homobinuclear Ni(II) and heterobinuclear Ni(II)Zn(II) complexes have been synthesized and characterized by elemental analysis and spectral analysis. The electronic spectra of all the complexes show "Red shift" in LMCT band, for the ligand H(2)L(2) having electron donating C(2)H(5) groups as N-substituents in the free side arms compared to ligand H(2)L(1) having relatively lower electron donating CH(3) groups. Electrochemical studies of the complexes reveal that all the binuclear complexes show two irreversible one-electron transfer reduction waves in the cathodic region. There is an "anodic shift" in the first reduction potential of the complexes of the ligand H(2)L(1) when compared to that of the complexes of the ligand H(2)L(2) due to the presence of higher electron donating C(2)H(5) N-substituents in the later case than the relatively lower electron donating N-substituents in the former case. Hydrolysis of p-nitrophenylphosphate using homobinuclear Ni(II) and heterobinuclear Ni(II)-Zn(II) complexes as catalysts showed that the homobinuclear complexes have higher rate constant values than that of the corresponding heterobinuclear complexes. A comparison of the spectral, electrochemical and catalytic behavior of the complexes of the ligands is discussed on the basis of the electron donating nature of the N-substituents at the free side arms.
authors: Department of Inorganic Chemistry, School of Chemical Sciences, University of Madras, Guindy Campus, Chennai 600 025, India.
authors: K
authors: K
authors: Shanmuga Bharathi
authors: S
authors: S
authors: Sreedaran
authors: A
authors: A
authors: Kalilur Rahiman
authors: Vengidusamy
authors: V
authors: Narayanan
mesh_terms: D002384:Catalysis; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D004566:Electrodes; D006868:Hydrolysis; D009532:Nickel / Q000737:chemistry*; D009596:Nitrophenols / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D019800:Phenol / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D015032:Zinc / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D009596:Nitrophenols; D009943:Organophosphorus Compounds; C008644:nitrophenylphosphate; D019800:Phenol; D009532:Nickel; D015032:Zinc