Coordination behavior of L-glutamic acid: spectroscopic and structural properties of (L-glutamato)(imidazole)copper(II), (L-glutamato)(2,2'-bipyridine)copper(II) and aqua(L-glutamato) (1,10-phenanthroline)copper(II) trihydrate complexes.

The synthesis and structural and spectroscopic characterization of three ternary copper(I1)-L-glutamate complexes of formulasCu(L-glu)(im), Cu(r-glu)(bpy), and Cu(~-glu)(o-phen).4H~(OL -glu = L-glutamate ion; im = imidazole; bpy = 2,2\u2019-bipyridine;o-phen = 1 ,lo-phenanthroline) are described. The Cu(L-glu)(im) complex has a one-dimensional polymeric structure, due to thebridging by the glutamate ligand between square-planar copper ions. The same polymeric structure and the same metal bindingby the glutamate ion occur in the Cu(L-glu)(bpy) complex, but in a square-pyramidal geometry. The structure of [CU(Lglu)(o-phen)H20].3H20 is made up of discrete mononuclear units, in which the glutamate ion acts as a simple bidentate ligandtoward a s uare pyramidal Cu atom. Crystal data are as follows. [CU(L-glu)(im)]: orthorhombic, space group P2,2,2,, a =24.286 (2)I$r, b 8.604 (1) A, c = 5.075 (1) A, Z = 4, R = 0.044 for 831 observed reflections. [Cu(r-glu)(bpy)]: orthorhombic,space group P2,2,2,, a = 7.674 (1) A, b = 17.738 (4) A, c = 21.761 (5) A, 2 = 8, R = 0.077 for 2129 reflections. [CU(Lglu)(o-phen).HzO].3H20: monoclinic, space group P2,, a = 12.168 (2) A, b = 22.222 (3) A, c = 7.591 (1) A, 0 = 106.10 (2)O,2 = 4, R = 0.049 for 3554 reflections. Spectroscopic (EPR, IR, and vis) properties of the complexes are interpreted in the lightof the known structures. The polymeric ability of the L-glutamate and L-aspartate ions in the presence of the copper(I1) ion isalso discussed