Darstellung und spektroskopische charakterisierung von mer-trihalogeno-carbonyl-oxalato-osmaten(III)

Upon treatment of trans-[OsX₄(CO)₂]^? or [OsX₅(CO)]^2? with oxalate in aqueous solution new complexes of the type mer-[OsX₃(CO)ox]^2? (X  Cl, Br, I) are formed. The IR and Ra spectra are assigned according to point group C_s. In the UV/VIS spectra, recorded at 10 K, charge transfer transitions from ligand levels, splitted by spin-orbit coupling, (π + σ)t_1u(X) and πt_2u(X) to t_2g(Os³⁺) are observed. Two weak bands with vibrational fine structure in the NIR region are assigned to intraconfigurational transitions within the ground term of osmium(III). The assignment is confirmed by bands of the same frequency observed in the electronic Raman spectrum.