Mössbauer magnetization and nuclear magnetic resonance measurements on some iridium(I) complexes with fullerene ligands

Abstract

The isomer shifts of the measured Mossbauer spectra are in accordance with quantum chemical calculations and both techniques showed that the studied iridium(I) complexes have a strong covalent character, namely, there are a direct σ donation of the ligands into the 6s orbital of Ir. The coordination of further π-acceptor ligands decreases the population of 6s orbital. The obtained quadrupole splittings detect significant difference among the electric field gradients at the nucleus of iridium in the discussed coordination compounds. In this paper we present the first attempt to obtain Mossbauer parameters of 193Ir by DFT calculations. The change in the measured quadrupole splittings due to the coordiantion of tetracyanoethylene to central iridium was excellently reproduced by theoretical calculation using ZORA scheme. The magnetization measurements proved that IrI has diamagnetic, singlet electronic structure in all the studied compounds. This finding was in accordance with density functional calculations as well. Nuclear magnetic resonance investigations on 31P nucleus could detect the decrease of the electric field gradient at the nucleus of 193Ir in IrCl(CO)(PPh3)2 due to the coordination of C60 to the central iridium atom.