'Redox-switch' catalysis of C-C bond formation with H2: One-electron reduction of the trityl cation

Article abstract of DOI:10.1002/anie.199700651

Different products are formed from the electron transfer reaction between the ruthenium hydride 1 and the trityl cation when 1 is employed as a 'redox-switch' catalyst or as stoichiometric reducing agent. In the first case 1 converts H₂ into a one-electron reducing agent for C-C bond formation, thus yielding the product known as Gomberg's dimer. In contrast, only triphenylmethane is produced in the stoichiometric reactions, by an electron-transfer/hydride-transfer mechanism.