The Unusual Magnetic Resonance Properties of Trigonal Prismatic Tc and Re Complexes

Abstract

The electron paramagnetic resonance (EPR) spectra of the trigonal prismatic complexes Tc(abt)3, Tc(bdt)3, Re(abt)3 and Re(bdt)3 (abt, O-aminobenzenethiol; bdt, benzene-1,2-dithiol) in dilute frozen solution are interpreted in terms of an axially symmetric spin Hamiltonian, with g values close to two, principal hyperfine couplings of {pipe} ATc {pipe}̃ 5-12 × 10-4 cm-1, nuclear quadrupole couplings of {pipe} PTc {pipe}̃ 0.3-0.35 × 10-4 cm-1 and the unusual values 5 × 10-4 cm-1̃ {pipe} AzzRe {pipe} < {pipe} PRe {pipe}̃ {pipe} AxxRe {pipe}̃ {pipe} AyyRe {pipe}̃ 25 × 10-4 cm-1. Similar magnitudes of the parameters have been obtained by simulation of the previously published spectra of Re(pda)3, ..