6533b7dbfe1ef96bd1271410

RESEARCH PRODUCT

Cobalt(II) and copper(II) assembling through a functionalized oxamate-type ligand

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description

Two new metal complexes of formula {[Co(Hpcpa)(H2O)3]n� 3/2nH2O} (1) and [Cu2(MeHpcpa)4(MeOH)2] � H2O� 3.68 MeOH (2 )[ H 3pcpa = N-(4-carboxyphenyl)oxamic acid and MeH2pcpa = methyl ester derivative of H3pcpa] have been synthesized and their structures determined by X-ray diffraction. 1 is a neutral zigzag chain of cobalt(II) ions bridged by Hpcpa 2� ligands exhibiting the bidentate/monodentate coordination mode. Each cobalt(II) ion is six-coordinate with three mer positioned water molecules, two oxamate-oxygens from a Hpcpa 2� ligand and a carboxylate-oxygen from another Hpcpa 2� group building a somewhat distorted octahedral surrounding. The intrachain cobalt–cobalt separation is 11.326(2) A. The structure of 2 consists of discrete syn–syn tetracarboxylate-bridged dicopper(II) units of the paddle wheel-type, the oxamate fragment of the MeHpcpa ligand being not involved in the coordination. Each copper(II) ion is five-coordinate in a distorted square pyramidal environment with four carboxylateoxygens in the basal plane and a methanol molecule in the apical position. The intradimer copper–copper separation is 2.5974(11) A. The magnetic properties of 1 and 2 have been investigated in the temperature range 1.9–300 K. The magnetic behavior of 1 corresponds to that of a magnetically isolated high-spin cobalt(II) ion with an important orbital contribution. The analysis of its magnetic data through the