Solid state and theoretical study of structural properties induced by step-wise chloro functionalization in dicarbonyl-[2-(phenylamino)pent-3-en-4-onato]rhodium(I) complexes

A series of five rhodium(I) dicarbonyl complexes containing systematically introduced phenyl-chloro substituted mono-anionic <i>β</i>-enaminoketonato ligands (N,O-bidentate donors) are presented. The influence of chloro substitution on the phenyl ring was investigated in the solid state and by theoretically optimized structures. Chloro substitution on the phenylamino ring in dicarbonyl [2-(phenylamino)pent-3-en-4-onato]rhodium(I) complexes were thus investigated with regard to optimized energies, metal–metal interactions, and bonding distances and angles primarily using X-ray diffraction and DFT calculations. The five complexes crystallized in three different crystal systems and five separate space groups. The packing modes of the complexes were evaluated by considering the relative orientation and metal–metal interactions and were found to be influenced by different factors, including weak intermolecular hydrogen bonds. Although no significant Cl⋯Cl interactions were observed, significant Rh⋯Rh bonding was identified. The theoretically optimized structures correlate very well with the solid state, with RMS overlay values varying between 0.62 and 0.23 Å. Upon coordination, the phenyl ring of the enaminato ligand adopts, without exception, an approximately 90° dihedral angle relative to the coordination plane, inducing a significant corresponding steric hindrance at the metal center. This is manifested by the complete blocking out of the well-known iodomethane oxidative addition reaction.