Thermal Ammonia Activation by Cationic Transition-Metal Hydrides of the First Row - Small but Mighty

Abstract

The thermal reactions of cationic 3d transition-metal hydrides MH(+) (M=Sc-Zn, except V and Cu) with ammonia have been studied by gas-phase experiments and computational methods. There are three primary reaction channels: 1) H(2) elimination by N-H bond activation, 2) ligand exchange under the formation of M(NH(3))(+), and 3) proton transfer to yield NH(4)(+). Computational studies of these three reaction channels have been performed for the couples MH(+)/NH(3) (M=Sc-Zn) to elucidate mechanistic aspects and characteristic reaction patterns of the first row. For N-H activation, σ-bond metathesis was found to be operative.