A Remarkable Switch from a Diamination to a Hydrohydrazination Catalyst and Observation of an Unprecedented Catalyst Resting State

摘要

Group 4 imido complexes, (L)M=NR, and, more recently, hydrazido complexes, (L)M=NNR2, undergo a range of addition or insertion reactions of their M=N multiple bonds with many unsaturated and saturated substrates. This reactivity has led to a number of new bond-forming methodologies. In the case of hydrazides, reductive cleavage of the N_α-N_β bond can also occur with formally oxidizable substrates, such as CO, isocyanides, and alkynes, in the presence of suitably activating supporting ligand sets, such as bis(cyclopentadienyl) and diamide-amine types. We recently found that the hydrazide complex I (Scheme 1) and certain homologues react with terminal or internal alkynes to form metallacycles of the type n.