Heterolytic Benzene C−H Activation by a Cyclometalated Iridium(III) Dihydroxo Pyridyl Complex: Synthesis, Hydrogen−Deuterium Exchange, and Density Functional Study
Steven K. Meier, Kenneth J. H. Young, Daniel H. Ess, William J., III Tenn, Jonas Oxgaard, William A. Goddard III, Roy A. Periana
Abstract
We report the synthesis of the pincer-cyclometalated (NNC^(t-Bu))Ir(III) dihydroxo pyridyl complex 6, which catalyzes hydrogen−deuterium (H/D) exchange between water and benzene in the presence of base (TOF = ~6 × 10^(−3) s^(−1) at 190 °C). Experimental and density functional theory (B3LYP) studies suggest that H/D exchange occurs through loss of pyridine followed by benzene coordination and C−H bond activation by a heterolytic substitution mechanism to give a phenyl aquo complex, which may dimerize. Exchange of H_2O for D_2O followed by the microscopic reverse of CH activation leads to deuterium incorporation into benzene. Synthesis of the μ-hydroxo phenyl dinuclear complex [(NNC^(t-Bu))Ir(Ph)(μ-OH)]_2 (9) also catalyzes H/D exchange with a turnover frequency (TOF = ~7 × 10^(−3) s^(−1) at 190 °C) similar to that for 6.
Group Members
Meier, S. K., Young, K. J. H., Ess, D. H., Tenn, W. J. I., Oxgaard, J., III, W. A. G., & Periana, R. A. (2009). Heterolytic Benzene C−H Activation by a Cyclometalated Iridium(III) Dihydroxo Pyridyl Complex: Synthesis, Hydrogen−Deuterium Exchange, and Density Functional Study. *Organometallics*, *28*(18), 5293-5304.