Synthesis, crystal structure and thermal decomposition of Cu(II), Co(II), Mn(II) complexes with hetero-ligands containing cysteic acid, 4,4′-dimethyl-2,2′-bipyridine and azide

Three new transition metal complexes, [Cu(L-cyst)(dmbpy)(H2O)] (1), [Mn(dmbpy)(2) (N-3)(Cl)] (2) and [Co(dmbpy)(3)]center dot[CoCl4]center dot Cl center dot 7H(2)O (3) with (L-cyst = L-cysteic acid, dmbpy = 4,4'-dimethyl-2,2'-bipyridine, N-3 = azide) have been synthesized and characterized by elemental analysis, thermal analysis (DTA/TGA), IR spectroscopy and single crystal X-ray diffraction (XRD). In the complex 1, the copper atoms are five-coordinated in a distorted square pyramidal site. It forms monomeric species, which are further connected into a three-dimensional supramolecular network through hydrogen bonding interactions. In the complex 2, the manganese atoms have a distorted octahedral environment with four nitrogen atoms of the two dmbpy, one nitrogen atom provided from azide ligand, the coordination sphere being completed by a chlorine atom. (2) is also a monomeric complex and the molecular structure of compound 2 is stabilized by non standard weak C-H center dot center dot center dot Cl hydrogen-bonds. The asymmetric unit of the complex 3 is built of two cobalt-containing fragments: the cationic [Co-II(dmbpy)(3)](+2) and the anionic ((COCl4)-Cl-II)(-2) groups. The molecular structure of compound 3 is stabilized by hydrogen bonds via O-H center dot center dot center dot O, O-H center dot center dot center dot Cl and C-H center dot center dot center dot Cl interactions. The thermal decompositions for 1 and 3 in the temperature range 30-1000 degrees C has revealed that the Cu complex decomposes in three steps whereas Co complex decomposes in four steps and transforms into the corresponding metal oxide. (C) 2011 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.