Enhanced Dihydrogen Activation by Mononuclear Iridium(II) Compounds: A Mechanistic Study.

The organometallic chemistry of 4d and 5d transition metals has been vastly dominated by closed-shell states. The reactivity of their metalloradical species is though remarkable, albeit yet poorly understood and with limited mechanistic investigations available. In this work we report the synthesis and characterization of two mononuclear Ir II species, including the first dinitrogen adduct. These compounds activate dihydrogen at a dissimilar rate, in the latter case several orders of magnitude faster than its Ir I precursor. A combined experimental/computational investigation to ascertain the mechanism of this transformation in Ir II compounds is reported.