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Complexes [Cu 2 L 2 Cl 4 ], [NiL 2 Cl 2 ], [PdLCl 2 ], and [PtLCl 2 ], where L is a novel ligand from the series of 2-subsituted 5-(α-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 [PtLCl 2 ] was found to have promising antiproliferative activity against human cervical carcinoma cells, with IC 50 value being average between those of cisplatin and carboplatin. The temperature-dependent magnetic susceptibility measurements of complex [Cu 2 L 2 Cl 4 ] revealed that the copper(II) ions were weakly antiferromagnetically coupled showing a coupling constant J of −2 cm −1 . [ABSTRACT FROM AUTHOR]

Abstract: Two series of tetrazole-containing platinum(II) and palladium(II) chlorido complexes, trans-[ML2Cl2] (M=Pt, Pd) and cis-[PtL2Cl2]·nH2O (n =0, 1), where L is 1- or 2-substituted 5-aminotetrazole, have been synthesized and thoroughly characterized. Configuration of platinum(II) complexes obtained from the reaction of 5-aminotetrazoles with K2PtCl4 has been found to vary depending on the nature of tetrazole derivatives and reaction conditions. According to in vitro cytotoxic evaluation, only platinum complexes display noticeable antiproliferative effect, and their cytotoxicity depends strongly on their geometry and hydrophobicity of the carrier ligands. The most promising complexes are cis-[Pt(1-apt)2Cl2]·H2O and cis-[Pt(2-abt)2Cl2]·H2O, where 1-apt is 5-amino-1-phenyltetrazole and 2-abt is 5-amino-2-tert-butyltetrazole. In comparison with cisplatin, they show comparable cytotoxic potency against cisplatin-sensitive human cancer cell lines, cis-[Pt(2-abt)2Cl2]·H2O performing substantially higher activity against cisplatin-resistant cell lines. Cell cycle studies in H1299 cell line indicated that cis-[Pt(2-abt)2Cl2]·H2O induced apoptosis launched from G2 accumulations. The DNA interaction with cis-[Pt(1-apt)2Cl2]·H2O was followed by UV spectroscopy, circular dichroism, hydrodynamic and electrophoretic mobility studies. Both cis-[Pt(1-apt)2Cl2]·H2O and cis-[Pt(2-abt)2Cl2]·H2O complexes appeared to be significantly less toxic than cisplatin in mice, while only compound cis-[Pt(1-apt)2Cl2]·H2O displayed noticeable efficacy in vivo. [Copyright &y& Elsevier]

Abstract: Complexes CuL3Cl2, PdL2Cl2 and PtL2Cl2, where L is a novel ligand from the series of 2-substituted 5-aminotetrazoles, namely 5-amino-2-tert-butyltetrazole (1), have been synthesized by the reaction of metal(II) chlorides with 1 and characterized by IR spectroscopy, thermal and X-ray analyses. The crystallographic structural analysis of these complexes revealed that 1 acts as a monodentate ligand coordinated to the metal via endocyclic N4 atom. Platinum complex demonstrates promising cytotoxicity against human cervical carcinoma cells with IC50 value average between those of cisplatin and carboplatin. [Copyright &y& Elsevier]