The lowest-energy ligand to metal charge-transfer absorption band of trans-[OsO2(malonate)2]2-.

The resolved structure of the lowest-energy oxo to osmium charge-transfer absorption band of trans-[OsO2(malonate)2]2- is analyzed on the basis of the exact molecular Ci symmetry determined from the structure of a crystal used for spectroscopy. The multiple progressions observed in the polarized spectra are rationalized in terms of the deviations from idealized D4h point group symmetry and compared to the spectra observed for complexes with D2h symmetry such as trans-[OsO2(oxalate)2]2- that show only a single dominant progression for this transition.