Ligand effect on the rhodium porphyrin catalyzed hydrogenation of [2.2]paracyclophane with water: key bimetallic hydrogenation.

Rhodium porphyrin catalyzed hydrogenation of the aliphatic carbon-carbon σ-bond of [2.2]paracyclophane with water has been examined with a variety of tetraarylporphyrins and axial ligands. Mechanistic investigations show that RhIII(ttp)H, which can be derived from the reaction of [RhII(ttp)]2 with water without a sacrificial reductant, plays an important role in promoting bimetallic reductive elimination to give the hydrogenation product.