Redox-switched oxidation of dihydrogen using a non-innocent ligand

Organometallic complexes containing non-innocent ligands of the type Cp*lr((t)BA(F)Ph))(1), where H2(t)BA(F)Ph is 2-(2-trifluoromethyl)anilino-4,6-di-tert-butophenol, were found to activate H-2 in a redox-switchable manner. The 16e(-) complex 1 was inert with respect to H-2, CO, as well as conventional basic substrates until oxidation. Oxidation of 16-electron 1 with 1 equiv of Ag+ resulted in ligand-centered oxidation affording salts of [1](+), which were characterized by crystallographically, EPR, and elemental analyses. [1](+) was reduced to 1 in the presence of H-2 and the sterically hindered base, 2,6-(Bu-t)(2)C5H3N, via a pathway that is first-order in both metal and dihydrogen. Compound [1](+) forms adducts; with MeCN, which inhibits catalysis. The catalytic oxidation of H2 was established by electrochemical methods to be associated with the monocation.