Stoichiometric C−C Coupling Reactions in the Coordination Sphere of an Iridium(III) Alkyl

An alkyl hydride η1-acetone complex of iridium or its α-elimination product undergoes insertion into alkenes to give a carbene dihydride via a proposed pathway that involves C−C bond formation by a rare C(sp3)−C(sp3) reductive elimination followed by a double C−H activation. In MeCN solution, reversible α-elimination equilibrates this carbene dihydride insertion product with its MeCN adduct, an iridium alkyl hydride with diastereotopic trans triphenylphosphine ligands (2JPP = 382 Hz). Alkynes also react, but they give a coupled η3-allyl complex via a proposed pathway that involves C−C bond formation by C(sp3)−C(sp2) reductive elimination. Crystal structures of key products are reported.