Check out the new Science paper by FOI (friend of IONiC) Pat Holland and co-workers. There's a write-up about it in C&E News, too. They synthesized a di-iron complex, which when reduced with potassium graphite reacts with nitrogen to form a nitride complex. Adding hydrogen to the nitride complex produces ammonia! The process is not catalytic, but it offers important mechanistic insights into the Haber-Bosch process. Very cool chemistry!