Electronic structure and Mössbauer hyperfine interactions of Au(I) compounds

The electronic structure of the linear Au(1) complexes ${\left(\mathrm{Au}{X}_2\right)}^{-1\mathrm{}}$, where $X=\mathrm{C}\mathrm{N},\mathrm{C}\mathrm{l},\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{F}$ has been studied in the self-consistent one-electron statistical exchange model. The relative importance of gold $5d$, $6s$, and $6p$ states in chemical bonding and for hyperfine interactions is examined, using linear-combination-of-atomic-orbitals decomposition of the molecular eigenstates. The variation of the isomer shift and quadrupole splitting of ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ with covalency is studied theoretically. The effect of pressure on these hyperfine interactions for K[Au${\mathrm{}\left(\mathrm{CN}\right)\mathrm{}}_2$] is investigated by considering different interatomic distances. In this latter case, the main discrepancies with respect to experiment found are believed to arise from bonding with exterior atoms. Relativistic effects are briefly explored by comparison of Dirac-Slater relativistic and nonrelativistic results for the cyanide anion.