Darstellung und spektroskopische Charakterisierung von Tetrachloro- und Tetrabromo-Oxalatoiridaten(IV) / Preparation and Spectroscopical Characterization of Tetrachloro- and Tetrabromoiridates(IV)

Abstract

On treatment of [IrX6]2- with oxalate in aqueous solution at first [IrX4OX]3- (X = Cl, Br) is formed, which after extraction with pentylammonium ions into CH2Cl2 can be oxidised by X2 to give the corresponding pure Ir(IV) complexes [IrX4OX]2-. The IR and Raman spectra are assigned according to point group C2V- The UV/VIS absorption spectra show strong CT bands of transitions from "(π + σ)tlu"- and "πt2U"-ligand niveaus to t2g 5 (IrIV). These are split into three components by spin-orbit coupling and corresponding to the different groups of ligands: Xtr 2, Xc 2, ox. The spectrum of (TBA)2[IrBr4OX] recorded at 10 K is highly resolved, showing a splitting of the Brtr 2 → Ir(IV) and Bc 2 → Ir(IV) transitions by 1000-1400 cm-1. In the NIR-region two d-d-transitions are observed superimposed with a fine structure by coupling with vibration modes