Hyperfine structure of EPR spectra of distorted antiferromagnetic trinuclear metal clusters

The hyperfine electron-nuclear interaction in distorted antiferromagnetic trinuclear metal clusters is considered. The joint effect of antisymmetric exchange, Heisenberg interactions and external magnetic field on the hyperfine structure of the EPR spectrum of trinuclear clusters is taken into account. It is shown that the type of hyperfine structure observed (equilateral, isosceles, scalene) depends upon the ratio between the antisymmetric exchange parameter on the one hand and both the effective parameters of distortions and resonance field on the other hand. Strong C₂ type distortions result in a hyperfine spectrum characterized by intermediate spin. Strong antisymmetric exchange transforms the hyperfine spectrum to the trigonal type.