Effects of the nuclear transformation111Ag(I)to111Cd(II)in a single crystal ofAg[111Ag](imidazole)2NO3

Perturbed angular correlation of γ-ray (PAC) spectroscopy performed on a single crystal of ${\mathrm{Ag}\left(\mathrm{imidazole}\right)\mathrm{}}_2{\mathrm{NO}}_3$ doped with radioactive ${}^{111}\mathrm{Ag}\left(\mathrm{I}\right)\mathrm{}$ reveals that one nuclear quadrupole interaction (NQI) characterizes the resulting PAC spectra. This implies a unique coordination geometry for Cd(II) after the decay of ${}^{111}\mathrm{Ag}\left(\mathrm{I}\right)\mathrm{}.$ The full NQI tensor was determined in the experiment. The diagonal elements in the principal-axis system can be derived from the two parameters fitted to the spectrum: ${\omega }_0=|{\omega }_{\mathrm{zz}}|=425.5\mathrm{}\pm 0.1\mathrm{M}\mathrm{r}\mathrm{a}\mathrm{d}/\mathrm{s}$ and $\eta =|{\omega }_{\mathrm{xx}}-{\omega }_{\mathrm{yy}}|/|{\omega }_{\mathrm{xx}}+{\omega }_{\mathrm{yy}}|=0.240\mathrm{}\pm \mathrm{0.001.}$ Quantum-mechanical ab initio calculations of the NQI tensor using the known geometry of ${\mathrm{Ag}\left(\mathrm{imidazole}\right)\mathrm{}}_2{\mathrm{NO}}_3$ substituting Ag(I) with Cd(II) at the position of Ag(I) do not agree with the experimentally derived NQI tensor. The coordination number is two for Ag(I) in ${\mathrm{Ag}\left(\mathrm{imidazole}\right)\mathrm{}}_2{\mathrm{NO}}_3,$ which is an unusual coordination number for Cd(II). The Cd(II) ion was therefore moved towards the ${\mathrm{NO}}_3^{-}$ anion in the ab initio calculations, in an attempt to include the two oxygen atoms of the nitrate ion in the coordination sphere. This resulted in a four coordinated structure with reasonable Cd(II)-ligand bond lengths. The ab initio calculations based upon this geometry agrees well with the experimentally determined NQI tensor.