INTRACONFIGURATIONAL ABSORPTION AND VISIBLE REGION ABSORPTION SPECTROSCOPY OF $ReCl_{6}{^{2-}}$ IN VARIOUS ($NR_{4})_{2}SnCl_{6}$ HOST CRYSTALS

Author Institution: Department of Chemistry, University of Illinois at Chicago; Procter and Gamble, Miami Valley LabsLow temperature absorption spectra for $Re^{4+}, a d^{3}$ system, in various ($NR_{4})_{2}SnCl_{6} (R = CH_{3}, C_{2}H_{5}, C_{3}H_{7}$) host crystals indicate effects of reduced host symmetry and origin shifts. In the $N(C_{2}H_{5})_{4}{^{+}}$ and $N(C_{3}H_{7})_{4}{^{+}}$ containing host crystals, a significant splitting as found that correlated to two substitutional sites with paralleling vibronic parterns. For $ReCl_{6}{^{2-}}$ in ($NR_{4})_{2}SnCl_{6} (R = H, CH_{3}, C_{2}H_{5}, C_{3}H_{7}$), several new transitions located from 16000 to $20000 cm^{-1}$ were found using absorption and excitation spectroscopy, which cannot be assigned to intra-configurational transitions of $ReCl_{6}{^{2-}}$. These may be due to either impurity or interconfigurational transitions. Discussion of these unassignable transitions will be presented