Synthesis, crystal structure, weak antiferromagnetic behavior and electronic studies of novel [((-)-sparteine) (PhCo₂)(Cl)]Cu(II) complex

[((-)-Sparteine)(PhCO₂)(Cl)]Cu(II) 1 complex is obtained by direct synthesis using copper(0). 1 crystallizes in the monoclinic space group P2₁ with a = 14.7355(12), b = 8.9768(5), c = 17.2810(10) Å, β = 111.916(5)°, and Z = 4. The electronic spectrum of 1 shows a broad band with λ_max ∼ 841 nm (ε = 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 ¹H NMR spectrum of 1 is typical of magnetic Cu(II) 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 A₇₇/A₃₀₀ = 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 θ = -21.67 K, suggesting a weak exchange coupling interaction. The crystalline structure of 1 shows that the lattice is arranged so that the space between molecules is smaller than 40 ų, not enough to accommodate solvent molecules. However, the shortest Cu-Cu contact is 7.5912(8) Å.