Journal of the American Chemical Society, Год журнала: 2025, Номер unknown

Опубликована: Март 13, 2025

We report that the cationic iridium complex (iPrPCP)IrH+ catalyzes transfer-dehydrogenation of alkanes to give alkenes and hydrogen isotope exchange (HIE) arenes. Contrary established selectivity trends found for C-H activation by transition metal complexes, strained cycloalkanes, including cyclopentane, cycloheptane, cyclooctane, undergo addition much more readily than n-alkanes, which in turn are reactive cyclohexane. Aromatic bonds also H/D less rapidly those but favorably The order reactivity toward dehydrogenation correlates qualitatively with reaction thermodynamics, magnitude is greater can be explained thermodynamics. Accordingly, cycloalkenes corresponding cycloalkanes hydrogenation cyclohexene, despite favorable thermodynamics such hydrogenations. Computational (DFT) studies allow rationalization origin unusual selectivity. Specifically, initial strongly assisted β-agostic interactions, particularly cycloalkanes. Subsequent α-C-H addition, H atom bond transferred directly hydride ligand a dihydrogen ligand. overall processes, β-H-transfer hydride, calculated generally have minima on IRC surface although not necessarily enthalpy or free energy surfaces; these extremely shallow 1,2-dehydrogenations effectively concerted asynchronous.

Язык: Английский