Abstract
ESR studies of dimeric copper(II) carboxylate complexes of the type Cu(CH2COO)2L.2H2O and Cu(CH3CH2COO)2L with the biologically important ligand L = nicotinamide are reported. The spectra show features corresponding to dimeric copper(II) complexes, and which at low temperatures are well resolved. Seven lines from hyperfine splitting A(z2) (high-field side) and six of seven lines from hyperfine splitting A(z1) (low-field side) are found. The observed resonances are used to calculate the zero-field splitting parameters D and E. Spin-Hamiltonian and zero-field splitting parameters are used to estimate the antiferromagnetic interaction; for Cu(CH3CH2COO)2L.2H2O - 2J = 320 cm-1 and for Cu(CH3CH2COO)2L - 2J = 332 cm-1.