Darstellung und spektroskopische Charakterisierung von Tetrakis (chloro -iodo ) oxalato -osmaten (IV )/Preparation and Spectroscopical Characterisation of Tetrakis(chloro-iodo)oxalato-osmates(IV)

Abstract

Abstract On treatment of [OsI4ox]2- with Cl- the mixed complexes [OsClnI4-nox]2-, n = 1, 2, 3, are formed. The isolation and complete separation of the differently coloured geometric isomers is achieved by ion exchange chromatography on diethylaminoethyl cellulose. The IR and Ra spectra are assigned according to point groups C2v, Cs, C1. The mutual influence of ligands, especially by the high trans effect of I, is indicated by shifts of the distinct vibrational and electronic bands. The observed splittings of I→Os transitions are attributed to the different groupings I-Os-I, I-Os-Cl, and I-Os-O, important for the distinction of stereoisomers. The CT-bands as well as the d-d-transitions show batho-chromic shifts with increasing number of I-ligands. Up to five spin-orbit components in the NIR region are well resolved. The assignment is improved by the electronic Ra spectra. The fine structure of some d-d-bands originates from coupling with symmetric vibrational modes.