ESR spectra of Cu(II) complexes with biologically important ligands at 77 K

Abstract

Low-temperature powder ESR studies of Cu(sal) 2·4H 2O, Cu(sal) 2(2-pycar) 2 and Cu(sal) 2(3-pycar) 2 (sal = salicylate ion, pycar = pyridylcarbinol) are reported. Spin-Hamiltonian parameters (obtained from experimental spectra, by the nonlinear optimization method) indicate, that the unpaired electron is in the antibonding ψ b 1g molecular orbital in all complexes, which clearly demonstrates an elongated tetragonal bipyramidal coordination around Cu(II). Spin-Hamiltonian parameters are used to estimate the molecular orbital coefficients for the Cu(sal) 2(2-pycar) 2 and Cu(sal) 2(3-pycar) 2.