6533b7d8fe1ef96bd126a1a4

RESEARCH PRODUCT

New complexes of nickel and nickel/cobalt with tetrahydrofuran-2,3,4,5-tetracarboxylic acid, THF(COOH)4. Crystal structures of Ni[THF(COOH)2(COOH)2](H2O)3 and Ni0.7Co0.3[THF(COOH)2(COO)2](H2O)3·H2O and their thermal behaviour

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Abstract The reaction of NiCl2·6H2O with tetrahydrofuran-2,3,4,5-tetracarboxylic acid, THF(COOH)4, partially deprotonated by Na2CO3 (1 : 1 metal/ligand molar ratio), yielded Ni[THF(COOH)2(COO)2](H2O)3 (1). The molecular structure of 1 was determined by X-ray diffraction on the monocrystal. The structure consists of a mononuclear neutral unit with the nickel atom coordinated by a [THF(COOH)2(COO)2]2− ligand, which acts as a tridentate ligand, and three water molecules. Direct interaction of NiCl2·6H2O and CoCl2·6H2O (1 : 1 molar ratio) with THF(COOH)4 previously deprotonated by Na2CO3 (1 : 1 metal/ligand molar ratio) gave, by slow evaporation of the solution obtained, green crystals of the non-stoichiometric complex Ni0.7Co0.3[THF(COOH)2(COO)2](H2O)3·H2O (2). Its crystal structure was solved by single-crystal X-ray diffraction methods. The structure is similar to that determined for compound 1, but with 30% of the sites for the metal atom occupied by cobalt and including a water molecule of crystallization. The thermal decomposition of both compounds showed three effects: An endothermic effect, corresponding to the loss of water which occurred at about 150°C and second and third exothermic processes, which overlapped each other at ca 310 and 330°C, corresponding to the decomposition of the complex and subsequent formation of oxides at very low temperatures.