CR4- A SPECTROSCOPIC AND STRUCTURAL INVESTIGATION( IN TETRAHEDRAL COORDINATION OF OXIDIC SOLIDS )

Various oxidic solids with chromium(IV) in tetrahedral sites have been synthesized, predominantly without impurities of chromium in other ox idation states, and spectroscopically investigated. The d-d spectra sh ow the typical features of a d(2) cation in distorted tetrahedral coor dination and could be fitted by utilizing AOM calculations on the basi s of the geometry of the host tetrahedra with the parameter set Delta similar or equal to 9650 cm(-1), B-et similar or equal to 480 cm(-1) ( beta(et) similar or equal to 0.47), C/B = 4.2. The EPR spectra usually exhibit only one exchange-averaged signal; the fine structure is only occasionally resolved.