Low temperature d-d spectra of 5-d transition metal complexes containing Re4+, Ir4+, and Pt4+ doped into various A2MX6 (A = alkali metals or alkyl ammonium; M = Sn, Zr, Re, Pt and Y; X = Cl or Br) hosts were measured and analyzed. In the case of IrX62- doped into the lower symmetry hosts, absorption spectra show no significant splittings of 0-0 origins, but interesting vibronic interactions were noted throughout the various mixed crystal samples, the most significant of which was a well-defined Jahn-Teller effect due to the v2 vibration. The results for IrX62- are presented and discussed in chapter 2.
In chapter 3, absorption spectra of ReCl62- doped in various lower symmetry hosts are presented and compared to previous results. The data obtained here showed that all the intra-configurational d-d transitions can be assigned paralleling the previous results of the systems involving cubic hosts. Sharp vibronic spectra arising from the five intra-configurational transitions were analyzed and compared to the earlier results.
Beyond the highest energy intra-configurational transition of ReCl62-, a group of bands was observed in pure K2ReCl6 as well as in a few mixed crystal samples, which could not be assigned with certainty. These bands are the subjects of chapter 4. Low temperature absorption spectra as well as excitation spectra of systems involving ReCl62- are presented and discussed. An attempt was made to fit the ligand field model to these unassignable transitions.
In chapter 5, low temperature absorption and two-photon excitation spectra of complexes containing PtCl62- are presented and discussed. The data obtained here showed a low-lying state located in the region below the transition reported previously by others. Also, for the first time for PtCl62-, moderately well-resolved vibronic spectra were obtained. The two-photon excitation (TPE) spectrum of the mixed Cs2ZrCl6:PtCl62-, which is the first spectrum for a mixed 5-d metal complex, showed a noticeable improvement in signal-to-noise ratio (S/N) compared to the previously reported TPE spectra of K2PtCl6. Detailed analyses of low temperature absorption and TPE spectra of complexes containing Pt4+ conclude this thesis.