Influence of the metal orbital occupancy and principal quantum number on organoazide (RN3) conversion to transition-metal imide complexes

The reaction of phenyl azide with (PNP)Ni, where PNP = ( (t)Bu 2PCH 2SiMe 2) 2N (-), promptly evolves N 2 and forms a P=N bond in the product (PNP=NPh)Ni (I). A similar reaction with (PNP)FeCl proceeds to form a P=N bond but without N 2 evolution, to furnish (PNP=N-N=NPh)FeCl. An analogous reaction with (PNP)RuCl occurs with a more dramatic redox change at the metal (and N 2 evolution), to give the salt composed of (PNP)Ru(NPh) (+) and (PNP)RuCl 3 (-), together with equimolar (PNP)Ru(NPh). The contrast among these results is used to deduce what conditions favor N 2 loss and oxidative incorporation of the NPh fragment from PhN 3 into a metal complex.