Synthesis,structure, thermal studies on Zn(II), Cd(II) complexes of N-(2-pyridylmethyl)pyridine-2-carbaldimine and N-(2-pyridylmethyl)pyridine-2-methylketimine |
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Authors: | Sumanta Kumar Padhi Rojalin SahuVadivelu Manivannan |
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Institution: | Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039, Assam, India |
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Abstract: | The bivalent zinc and cadmium complexes of two Schiff bases N-(2-pyridylmethyl)pyridine-2-carbaldimine (L1), N-(2-pyridylmethyl)pyridine-2-methylketimine (L2), tridentate ligands with an N3 chromophore and coordinating with two five-membered chelate rings, were synthesized. Complexes Zn(L1)(NO3)2] (1), Zn(L2)(NO3)2] (2), Cd(L1)(NO3)2(H2O)] (3) and Cd(L2)(NO3)2(CH3OH)] (4) were characterized by X-ray crystallography. In 1 and 2, Zn(II) has a distorted square-pyramidal geometry where as in 3 and 4, Cd(II) possesses a pseudo-pentagonal-bipyramidal geometry. The following trends in the bond lengths are observed: M–Nim < M–Npy; Zn–N > Zn–O; Cd–N < Cd–O. The final residues from the thermogravimetric analysis are ZnO and CdO, the SEM studies revealed, respectively, their porous and spherical natures. The average activation energy (E) for the loss of pyridine rings obtained from the Friedman fitting of the DSC data, for 1, 2, 3, and 4 are 193.8(2), 114.5(3), 127.1(4), and 63.7(3) kJ mol−1 and their logarithmic pre-exponential factor (A) are 11.22, 5.31, 6.88, and 2.09, respectively. |
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Keywords: | Schiff base Crystal structure Thermogravimetry SEM Thermokinetics |
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