ESR studies of (Cu(H 2O) 6) 2+ in magnesium sulfate heptahydrate

Abstract

ESR studies of (Cu(H 2O) 6) 2+ complex in magnesium sulfate heptahydrate are undertaken at 300, 150, and 77 K. The spin-Hamiltonian parameters at 150 K indicate a rhombic symmetry and are g x = 2.098 ± 0.002, g y = 2.089 ± 0.002, g z = 2.441 ± 0.002, ∥ A x ∥ = (22 ± 1) × 10 −4cm −1, ∥ A y ∥ = (18 ± 1) × 10 −4cm −1, and ∥ A z ∥ = (116 ± 1) × 10 −4cm −1. The ground-state wavefunction of the (Cu(H 2O) 6) 2+ complex at 150 K is calculated and the covalency and the admixture coefficient of ∥3 z 2 − r 2> into the ground state are estimated. The covalency reflected in the ground-state wavefunction is found to be in conformity with the optical absorption data. The temperature dependence of spin-Hamiltonian parameters is explained on the basis of dynamic Jahn-Teller effects.