Spin Hamiltonian parameters for the neutral trigonal-prismatic Tc(abt)(3) and Re(abt)(3) chelates (abt = o-aminobenzenethiol) are calculated using relativistic density functional theory at the all-electron level. The small magnitude of the calculated g shifts and metal hyperfine interactions is in excellent agreement with previous experimental predictions based upon a ligand-centered ground-state magnetic orbital. The theoretical N-14 ligand hyperfine and quadrupole couplings also reproduce the nuclear frequencies measured by electron spin-echo envelope modulation spectroscopy. The nuclear quadrupole interaction of Re-187 is predicted to be 2 orders of magnitude larger than that of Tc-99, in agreement with empirical simulation of the continuous-wave electron paramagnetic resonance spectrum. The spectrum of Tc(abt)(3) at high solute concentrations contains a central resonance not predicted for the isolated complex by theoretical calculations. The absence of this resonance at low solute concentrations provides evidence of intermolecular interactions in these systems.
Drew, S. C., Baldas, J., & Boas, J. F. (2010). Theoretical calculation of the magnetic resonance parameters of trigonal-prismatic tris(o -aminobenzenethiol)technetium and -rhenium complexes. Inorganic Chemistry, 49(15), 6799 - 6801. https://doi.org/10.1021/IC/1009175