Effects of the nuclear transformation Ag-111(I) to Cd-111(II) in a single crystal of Ag[Ag-111] (imidazole)(2)NO3

Perturbed angular correlation of gamma-ray (PAC) spectroscopy performed on a single crystal of Ag(imidazole)(2)NO3, doped with radioactive Ag-111(I) r eveals that one nuclear quadrupole interaction (NQI) characterizes the resu lting PAC spectra. This implies a unique coordination geometry for Cd(II) a fter the decay of Ag-111(I). The full NQI tensor was determined in the expe riment. The diagonal elements in the principal-axis system can be derived f rom the two parameters fitted to the spectrum: omega(0) = \omega(zz)\ = 425 .5 +/- 0.1 Mrad/s and eta = \omega(xx) - omega(yy)\/\omega(xx) + omega(yy)\ = 0.240 +/- 0.001. Quantum-mechanical ab initio calculations of the NQI te nsor using the known geometry of Ag(imidazole)(2)NO3 substituting Ag(I) wit h Cd(II) at the position of Ag(I) do not agree a ith the experimentally der ived NQI tensor. The coordination number is two for Ag(I) in Ag(imidazole)( 2)NO3, which is an unusual coordination number for Cd(II). The Cd(II) ion w as therefore moved towards the NO3- anion in the ab initio calculations, in an attempt to include the two oxygen atoms of the nitrate ion in the coord ination sphere. This resulted in a four coordinated structure with reasonab le Cd(II)-ligand bond lengths. The ab initio calculations based upon this g eometry agrees well with the experimentally determined NQI tensor.