Catalytic Arene H/D Exchange with Novel Rhodium and Iridium Complexes

Three novel pendant acetate complexes, [Rh­(bdmpza)­Cl₃]⁻M⁺, [Rh­(bdmpza)­Cl₂(py)], and [Ir­(bdmpza)­Cl₃]⁻M⁺ (bdmpza = bis­(3,5-dimethylpyrazol-1-yl) acetate, M⁺ = Li⁺, Na⁺), were synthesized. Abstraction of halide from these complexes with silver salts yielded species capable of C–H activation of arenes. The catalytic H/D exchange reaction between benzene and trifluoroacetic acid-<i>d</i> was optimized, and these conditions were used to evaluate H/D exchange in other arenes. Branched alkyl substituents in alkyl aromatics showed an affinity toward deuterium exchange in the β-alkyl position only. DFT calculations were performed to determine the mechanism of H/D exchange.