EPR Parameters of quantum mixed-spin ferric complexes with rhombic and tetragonal symmetry

Calculations are presented for the EPR g values of ferric iron in a crystal field with axial and rhombic symmetry components for a spin state which is a quantum mechanical mixture of intermediate-spin (S = 3/2) and high-spin (S = 5/2) components. The crystal field parameter μ/δ₁ is discussed as a more fundamental measure of rhombic distortion than the spin Hamiltonian ratio E/D.