Density functional theory calculations of the isomer shift and quadrupole splitting of iridium(I) complexes with and without multimetallic bonding to fullerene

In this article, we present an improved density functional theory (DFT) strategy for the calculation of isomer shifts $$\:\delta\:$$ and quadrupole splittings $$\:\varDelta\:{E}_{Q}$$ of iridium complexes. For the iridium(I) complex ([IrCl(COD)]2) we obtain $$\:\delta\:$$ = -0.63 mms-1 and $$\:\varDelta\:{E}_{Q}$$ = 3.81 mms-1. Our calculation reproduce the negative sign determined experimentally by Gál et al. (Journal of Radioanalytical and Nuclear Chemistry 260 (2004) pp. 133–142). The calculations also reproduce the values of $$\:\delta\:$$ and $$\:\varDelta\:{E}_{Q}$$ in a reasonable manner. We also present calculations of the fullerene adduct C60([IrCl(COD)]2)2 which we consider as a well-defined model system for the exploration of molecule-substrate interaction. The binding of the complex to fullerene leads to an electronic ground state with clearly different Mössbauer parameters: We have calculated $$\:\delta\:$$ = -0.90 mms-1 and $$\:\varDelta\:{E}_{Q}$$ = -6.06 mms-1, again in good agreement with experimental values reported by Tuczek et al. (Tuczek et al. Fullerene Science and Technology 5 (1997) pp.443–452).