An Unusual Carbonyl Chemical Shift in a Carbonylhexairidium Cluster: A Combined Solid‐State NMR and DFT Approach (Eur. J. Inorg. Chem. 22/2007)

Abstract

AbstractThe cover picture shows the structure and the 13C NMR spectrum of [Ir6(CO)15]2− at 173 K. It features an unprecedented μ2‐bridging carbonyl low frequency shift; the resonances of the terminal μ1‐carbonyl groups are placed at higher frequencies. This unusual trend has been explained by combined use of DFT calculations and solid‐state NMR parameters, such us chemical shift tensors and shielding anisotropies. The scalar and Spin‐Orbit (SO) relativistic two‐component Zero‐Order Regular Approximation (ZORA) methods have been employed in the geometry optimization and NMR chemical shift calculations, respectively. The large SO contribution (26.6 ppm) to the 13C chemical shifts of the μ2‐bridging CO groups accounts for the position of the experimentally observed resonance. This work outlines the importance of the SO evaluation in cases of atoms connected to heavy metal atoms. Details are discussed in the article by L. Garlaschelli, R. Gobetto et al. on p. 3487 ff.