Synthesis, Structures, and Transfer Hydrogenation Catalysis of Bifunctional Iridium Complexes Bearing a C–N Chelate Oxime Ligand

<jats:title>Abstract</jats:title><jats:p>We have synthesized a series of organometallic oxime complexes as novel metal–ligand cooperating bifunctional catalysts. The reaction of [{Cp*IrCl(μ<jats:sub>2</jats:sub>‐Cl)}<jats:sub>2</jats:sub>] with ketoximes in the presence of sodium acetate afforded the half‐sandwich chlorido iridium complexes <jats:bold>6</jats:bold> bearing a C–N chelate oxime ligand with a protic OH group in the β‐position to the metal. Complex <jats:bold>6a</jats:bold>, derived from acetophenone oxime, reacted with silver triflate to give the triflate complex <jats:bold>7</jats:bold> and cationic nitrile complex <jats:bold>8</jats:bold> depending upon the reaction solvent. Complexes <jats:bold>6</jats:bold> also reacted with a base in dichloromethane to afford the oximato‐bridged dinuclear complexes <jats:bold>9</jats:bold>, which were converted back to the chlorido complexes <jats:bold>6</jats:bold> upon treatment with an amine hydrochloride. In contrast, dehydrochlorination of <jats:bold>6</jats:bold> in 2‐propanol as well as the reaction of <jats:bold>9</jats:bold> with 2‐propanol yielded the hydrido‐bridged dinuclear oxime–oximato complexes <jats:bold>10</jats:bold>. Crossover experiments revealed that <jats:bold>10</jats:bold> dissociates into the mononuclear hydrido–oxime complex <jats:bold>11</jats:bold> and unsaturated oximato complex <jats:bold>12</jats:bold>, which are interconvertible by reactions with hydrogen donors and acceptors. Owing to the metal–ligand cooperation, <jats:bold>10</jats:bold> effectively catalyzed transfer hydrogenation of ketones with 2‐propanol.</jats:p>