Ammonia Activation, H Evolution and Nitride Formation from a Molybdenum Complex with a Chemically and Redox Noninnocent Ligand.

Treatment of the bis(imino)pyridine molybdenum η-benzene complex (PDI)Mo(η-CH) (PDI, 2,6-(2,6-iPrCHN═CMe)CHN) with NH resulted in coordination induced haptotropic rearrangement of the arene to form (PDI)Mo(NH)(η-CH). Analogous η-ethylene and η-cyclohexene complexes were also synthesized, and the latter was crystallographically characterized. All three compounds undergo loss of the η-coordinated ligand followed by N-H bond activation, bis(imino)pyridine modification, and H loss. A dual ammonia activation approach has been discovered whereby reversible M-L cooperativity and coordination induced bond weakening likely contribute to dihydrogen formation. Significantly, the weakened N-H bonds in (PDI)Mo(NH)(η-CH) enabled hydrogen atom abstraction and synthesis of a terminal nitride from coordinated ammonia, a key step in NH oxidation.