Intramolecular Rearrangement for Regioselective Complexation by Intramolecular CH/π Interaction in a Hydrophobic Cavity of a Ruthenium Coordination Sphere

A Ru II complex with a hydrophobic cavity formed from two 1‐naphthoylamide groups was prepared. Its reactions with β‐diketones gave β‐diketonato complexes in which hydrophobic π–π or CH/π interactions were confirmed by NMR spectroscopy and X‐ray crystallography. In the case of the asymmetric β‐diketone benzoylacetone, an isomer with a CH/π interaction was afforded as the sole product owing to thermodynamic control. The reaction was found to involve a novel intramolecular rearrangement from the phenyl‐included isomer to the methyl‐included one without rupture of Ruβ‐diketonato coordination bonds (activation energy 52 kJ mol −1 ). This indicates that CH/π interactions can be more favored thermodynamically than π–π interactions in a suitable hydrophobic environment.