Resonance spectroscopy of γ-radiation on Au (I) and Au (III) compounds

Isomer shift (IS) and electric quadrupole splitting (QS) of the 77 keV γ-rays of Au¹⁹⁷ were investigated for a large number of Au (I) and Au (III) compounds at 4.2 °K by nuclear γ-resonance Spectroscopy. A close correlation between the observed isomer shifts and the spectrochemical series of the ligands was observed. For each oxidation state, isomer shift and electric quadrupole splitting show approximately a linear relationship. On the basis of LCAO-MO theory, the experimental results are interpreted by covalency effects in the molecular orbitals, synergic coupling of σ- and π-bonds, and the empirically known donor and acceptor properties of the ligands.