Experimental charge density study into C–C σ-interactions in a Binor-S rhodium complex

Transition-metal complexes containing (C–C)→M s-interactions have potential applications in both catalysis and the activation and cleavage of C–C bonds. Fully characterising the bonding and interactions in complexes containing such (C–C)→M s-interactions is vital to understand their chemical behaviour. As a result a high-resolution experimental X-ray charge density study has been undertaken on [Rh(Binor-S)(PCy3)][HCB11Me11] (Binor-S = 1,2,4,5,6,8-dimetheno-s-indacene) which contains a (C–C)→Rh interaction. The data are analysed using Bader’s “Atoms in Molecules” (AIM) approach with particular attention paid to the interactions around the rhodium centre. The results provide clear evidence for the s(C–C)→Rh interaction in the solid-state which is classified as a weak covalent interaction. These results are supported by theoretical calculations