Dinitrogen activation, partial reduction, and formation of coordinated imide promoted by a chromium diiminepyridine complex

Reduction of 2,6-[2,6-(i-Pr)2PhN=C(CH3)]2(C5H3N)CrCl (3) with NaH afforded the dinuclear dinitrogen complex [2,6-[2,6-(i-Pr)2PhN=C(CH3)]2(C5H3N)Cr(THF)]2(mu-N2).THF (5). Reaction carried in exclusion of dinitrogen afforded instead deprotonation of the ligand with the formation of 2-[2,6-(i-Pr)2PhN=C(CH3)]-6-[2,6-(i-Pr)2PhNC=CH2](C5H3N)Cr(THF) (4). Further reduction of 5 with NaH yielded a curious dinuclear compound formulated as [2,6-[2,6-(i-Pr)2PhN=C(CH3)]2(C5H3N)Cr(THF)][2-[2,6-(i-Pr)2PhN=C(CH3)]-6-[2,6-(i-Pr)2PhNC=CH2](C5H3N)Cr(THF)](mu-N2 H)(mu-Na)2 (6) containing two sodium atoms only bound to the dinitrogen unit and the pi systems of the two diiminepyridine ligands. Subsequent reduction with NaH triggered a complex series of events, leading to the formation of a species formulated as 2-[2,6-(i-Pr)2PhN=C(CH3)]-6-[2,6-(i-Pr)2PhNC=CH2](C5H3N)Cr(mu-NH)][Na(THF)] (7) on the basis of crystallographic, spectroscopic, isotopic labeling, and chemical degradation experiments.