Predicting Dinitrogen Coupling with a Series of Small Molecules Catalyzed by a Pincer Complex
Due to consumption of more than 2% of the world's annual energy supply by Haber–Bosch process and the strongest triple bond (N≡N) in nature, directly coupling N 2 with small molecules is particularly important and challenging, let alone in a catalytic fashion. Here we first demonstrate that a NNN-type pincer phosphorus complex could act as a catalyst to couple dinitrogen with a series of small molecules including carbon dioxide, formaldehyde, N-ethylidenemethylamine, and acetonitrile in the presence of diborane(4) under a mild condition by theoretical calculations. N 2 fixation proceeds via a stepwise mechanism involving initial N 2 activation by diborane(4), followed by intramolecular isomerization to a key intermediate (zwitterion). Such a zwitterion can be used to couple a series of small molecules with activation barriers of 23.5-25.2 kcal mol -1. All these findings could be particularly useful for main group chemistry aiming at N 2 activation.