Transition metal chelate complexes with tetrazole derived Mannich base: Metal dependent architecture and properties

Complexes [Cu2L2Cl4], [NiL2Cl2], [PdLCl2], and [PtLCl2], where L is a novel ligand from the series of 2-subsituted 5-(a-aminoalkyl)tetrazoles, namely 5-(N,N-dimethylaminomethyl)-2-tert-butyltetrazole, have been synthesized and characterized by IR spectroscopy, thermal analysis and single crystal X-ray analysis. The complexes reported show different coordination geometries of the metals, viz. octahedral for Ni, square pyramidal for Cu, and square planar for Pt and Pd complexes. At the same time, the ligand L demonstrates the same coordination mode in all the complexes. It acts as a chelating ligand coordinated to the metal via two nitrogen atoms, namely the tetrazole ring N-4 and the dimethylamino N atoms. Complex [PtLCl2] was found to have promising antiproliferative activity against human cervical carcinoma cells, with IC50 value being average between those of cisplatin and carboplatin. The temperature-dependent magnetic susceptibility measurements of complex [Cu2L2Cl4] revealed that the copper(II) ions were weakly antiferromagnetically coupled showing a coupling constant J of -2 cm(-1). (C) 2018 Elsevier Ltd. All rights reserved.