Nickel(II) complexes of new polydentate carboxyamide: spectroscopic, kinetics of thermal decomposition and X-ray powder diffraction studies

Abstract

Complexes of NiII with new ligands N′,N′′-bis(3-carboxy-1-oxoprop-2-enyl), 2-Amino-N-arylbenzamidine (C21H17N3O6), N′,N′′-bis(3-carboxy-1-oxopropanyl) 2-Amino-N-arylbenzamidine (C21H21N3O6) and N′,N′′-bis(3-carboxy-1- oxophenelenyl) 2-Amino-N-arylbenzamidine (C29H21N3O6) have been synthesized and characterized by elemental analyses, vibrational spectra, electronic spectra, TOF-mass spectra, magnetic susceptibility measurements, thermal studies and X-ray powder diffraction studies. Vibrational spectra indicate coordination of amide and carboxylate oxygen of the ligands along with two water molecules giving a MO6 weak field octahedral chromophore. Electronic spectra and magnetic susceptibility measurements reveal octahedral geometry for NiII complexes. The elemental analyses and mass spectral data have justified the ML complexes. Kinetic and thermodynamic parameters were computed from the thermal data using Coats and Redfern method, which confirm first order kinetics. The crystal data: C21H19N3O8 Ni is orthorhombic, space group Pmmm, a = b = 9.015360(A), c = 10.554430(A), V = 572.11A3; C21H23N3O8Ni is monoclinic, space group P2/m, a = 15.08206(A), b = 5.358276(A), c = 9.898351(A), V = 671.58A3; C29H23N3O8Ni is tetragonal, space group P4/m, a = b = 6.328104(A), c = 9.82213(A), V = 393.33A3. Molecular structures of the complexes have been optimized by MM2 calculations and supported octahedral arrangements around Nickel(II) ions.