1,10-Phenanthroline-5,6-dione complexes of middle transition elements: Mono- and dinuclear derivatives

The synthesis and the characterization of several mono- and dinuclear middle transition metal derivatives of 1,10-phenanthroline5,6-dione, 1, are presented. The reaction of 1 with CrCl(2)(THF)(2) gives CrCl(2)(O, O'-C(12)H(6)N(2)O(2))(THF)(2), 2, while the halides of iron(II), cobalt(II) and nickel(II) afford adducts of general formula MX(2)(N, N'-C(12)H(6)N(2)O(2)), M = Fe, 4, Co, 5, X = Cl; M = Ni, 6, X = Br. DFT calculations on CrCl(2)(L)(THF)(2) with L = O, O'-C(12)H(6)N(2)O(2) or O, O'-C(14)H(8)O(2) allowed a direct comparison of the coordination properties of 9,10-phenanthrenequinone and 1,10-phenanthroline-5,6-dione to be made. Dinuclear compounds of general formula CrCl(2)(THF)(2)(O, O'-C(12)H(6)N(2)O(2)-N, N') MX(n)L(m), M = Zr, 7, X = Cl, n = 4, m = 0; M = Cr, 8, X = Cl, n = 2, L = THF, m = 2; M = Fe, 9, Co, 10, X = Cl, n = 2, m = 0; M= Ni, 11, X = Br, n = 2, m = 0, are prepared from 2 and the corresponding metal halide, while VCp(2)(O, O'-C(12)H(6)N(2)O(2)-N, N') FeCl(2), 12, is synthesized by reacting 4 with VCp2. The electronic properties of the different complexes are investigated by magnetic moment measurements and EPR spectroscopy. (C) 2007 Elsevier B. V. All rights reserved.