Thermal decomposition and mass spectra of mixed ligand copper(II) complexes of 1,10-phenanthroline and coumarin derivatives

Four copper(II) new mix ligand complexes of the coumarin derivative (A(1) = 7-hydroxy-10,11-dihydroindeno[5,4-c]chromen-6(9H)-one, A(2) = 2-bromo-7-hydroxy-10,11- dihydroindeno[5,4-c]chromen-6(9H)-one, A(3) = 7-hydroxy-4-methoxy-10,11-dihydroindeno[5,4-c]chromen-6(9H)-one, and A(4) = 5-hydroxy-8,9-dihydrobenzo[f]indeno[5,4-c]chromen-4(7H)-one) and 1,10-Phenanthroline have been synthesized. The structural interpretations were confirmed from elemental analyses, magnetic susceptibility and FAB mass spectral, as well as from IR spectral studies. From the analytical, spectroscopic, and thermal data, the stoichiometry of the mentioned complexes was found to be 1:1:1 (coumarin ligand:copper metal:1,10-Phenanthroline). The thermal stabilities of these complexes were studied by thermogravimetric (TG/DTG) and the decomposition steps of these four complexes are investigated. Kinetic parameters such as order of reaction (n) and the energy of activation (E (a)) were calculated using Freeman-Carroll method. The pre-exponential factor (A), the activation entropy (S*), the activation enthalpy (H*), and the free energy of activation (G*) were calculated using Horowitz-Matzger equations. Based on the E (a) values, the thermal stabilities of complexes in the decreasing order are Cu(II)-2 > Cu(II)-3 > Cu(II)-4 > Cu(II)-1.