Summary
The electrical, magnetic, and optical properties of a series of cubic single crystals of the K2PtCl6 type is reported. The results of the measurements of the conductivities of K2TaCl6, Rb2TaCl6, and Cs2TaCl6, together with the Nb analogues are presented. The optical spectra of Tc(+4) in Cs2ZrCl6 is reported, and a series of experiments on the exciton spectra of pure K2ReCl6 single crystals at 4.2K are discussed. The vibronic splitting of Ir(+4) Gamma 8 excited states as a function of the symmetric mode is also reported. (Author).