SELF-ASSEMBLY OF COPPER AND MAGNESIUM-IONS WITH L-GLUTAMATE - SPECTROSCOPIC AND STRUCTURAL-PROPERTIES OF [CUMG(L-GLUTAMATO)(2)(H2O)(3)]CENTER-DOT-2H(2)O

The mixed-metal complex of copper(II) and magnesium(II) ions with glut amate has been firstly synthesized by self-assembling, and characteriz ed by elemental analyses, IR spectra and electronic spectra. The struc ture of the complex has been determined by single-crystal X-ray diffra ction. The [CuMg(L-glu)(2) (H2O)(3)] . 2H(2)O (L-glu = L-glutamate) co mplex has a one-dimensional polymeric structure, in which Cu-II and Mg -II ions are bridged by glutamate. Each Cu atom exhibits distorted squ are pyramidal five-coordination, with two glutamate ions acting as a b identate ligand through the amino N and the alpha-carboxylate O atoms in trans positions in the equatorial plane, forming two glycine-like r ings, and with a water molecule in apical position. Each Mg atom is co ordinated in a slightly distorted octahedral geometry by two gamma-car boxylate O atoms from two glutamate ions and by four water molecules. The average Cu-O, Cu-N and Mg-O distances are 2.048(2), 1.979(3) and 2 .084(2) Angstrom, respectively. The coordination patterns of glutamate ion in different glutamate Cu-II complexes are also discussed. (C) 19 97 Elsevier Science Ltd.