Core Polarization of Ag2+ (4d9, 2D) by Electron Paramagnetic Resonance of Frozen Acid Solutions

Electron paramagnetic resonance of divalent silver in frozen solutions of HNO₃, HF, HClO₄, H₂SO₄, and H₃PO₄ in various concentrations has been observed in the X band at 77°K. In all cases, an axial symmetry with $g_{\parallel }{\mathrm{>\; g}}_{\perp }$ indicates that the ground state of the silver ion is $d_{x^2{\mathrm{-y}}^2}$ with various admixtures of ligand orbitals. An interpretation of 49 spectra considering orbital admixture and electron localization gives for the core polarization extrapolated to unit electron density the value of $\text{−9.36±0.32}\mathrm{a.u.}$ which compares very well with the theoretical value of $\text{−9}\mathrm{a.u.}$ for divalent ions of the second transition series. Extrapolation to zero electron density supports the existence of an important contribution to the polarization due to the electron density localized in the ligands.