Assessment of Catalysis by Arene‐Ruthenium Complexes Containing Phosphane or NHC Groups bearing Pendant Conjugated Diene Systems

Two p-cymene-ruthenium complexes 1 and 2 were isolated in high yields by treating the [RuCl2(p-cymene)]2 dimer with new hybrid phosphane- or NHC-linked diene ligands. Both complexes were fully characterized by NMR spectroscopy, and the molecular structure of the ruthenium–p-cymene complex 1, containing the phosphane–diene ligand system, was determined by X-ray diffraction analysis. The catalytic activities of both compounds were probed in atom-transfer radical addition (ATRA) and polymerization (ATRP), in the cyclopropanation of olefins, in the ring-opening metathesis polymerization (ROMP) of norbornene, and in the synthesis of enol esters from hex-1-yne and 4-acetoxybenzoic acid.