Darstellung und Schwingungsspektren von Fluoro-Chloro-Osmaten(V)/ Preparation and Vibrational Spectra of Fluoro-Chloro-Osm ates(V)

Abstract

Abstract By oxidation of the pure fluoro-chloro-osmates(IV ) with BrF3 in dichlorom ethane the mixed pentavalent complexes [OsF5Cl]-, cis-[OsF4Cl2]-, fac-[OsF3Cl3]- and cis-[OsF2Cl4]- are formed without replacement of ligands. Trans-[OsF4Cl2]- and trans-[OsF2Cl4]- are generated from the corresponding osmates(IV) by oxidation with PbO2 in dichloromethane under addition of trifluoroacetic acid. The vibrational spectra o f the mixed ligand complexes are assigned according to point groups D4h, C4v, C3v and C2v. The increased bond strength com pared with the corresponding Os(IV ) complexes is indicated by a significant shift to higher energy by about 5 -15% . The Os -Cl stretching vibration of [OsF5Cl]- and also the symmetric ClOsCl of trans-[OsF4Cl2]- is split by the isotopes 35Cl and 37Cl, showing two and three well resolved sharp Raman lines in the expected ratio of intensities, respectively.