Synthesis, crystal structure, weak antiferromagnetic behavior and electronic studies of novel [((-)-sparteine) (PhCO2)(Cl)]Cu(II) complex

Abstract

[((-)-Sparteine)(PhCO2)(CI)]Cu(II) 1 Complex is obtained by direct synthesis using copper(0). 1 crystallizes in the monoclinic space group P2(1) with a = 14.7355(12), b = 8.9768(5), c = 17.28 10(10) Angstrom, beta = 111.916(5)degrees, and Z = 4. The electronic spectrum of 1 shows a broad band with lambda(max) similar to 841 nm (epsilon = 0.261 mM(-1) cm(-6)) characteristic of a low symmetry and tetragonally distorted square pyramidal local Cu geometry. The far IR spectrum of 1 shows characteristic vibrations of Cu-Cl (260, 267 cm(-1)), Cu-N (436, 467 cm(-1)) and Cu-O (457 cm(-1)) bonds. The H-1 NMR spectrum of 1 is typical of magnetic Cu(H) complexes with line broadening due to efficient nuclear relaxation from the metal center. ESR spectra of polycrystalline 1 at 77 K show an axial spectrum with linewidth of 58.6 G and at 300 K of 89.0 G, with areas in the ratio A(77)/A(300) = 2.79, indicative of antiferromagnetic order. The linewidth is reduced by 34% on going from 300 to 77 K. Standard magnetization measurements at low temperatures show an Curie-Weiss behavior with theta = -21.67 K, suggesting a weak exchange coupling interaction. The crystalline structure of I shows that the lattice is arranged so that the space between molecules is smaller than 40 Angstrom(3), not enough to accommodate solvent molecules. However, the shortest Cu-Cu contact is 7.5912(8) Angstrom. (C) 2003 Elsevier B.V. All rights reserved.