Abstract :
By employing a monodentate N-heterocyclic carbene (NHC), 1,3-dicyclohexylimidazol-2-ylidene (ICy) as ligand, the cobalt(0)- and cobalt(-1)uN2 complexes, [(ICy)3Co(N2)] (1) and [(ICy)2Co(N2)2M]n (M=K, 2a; Rb, 2b; Cs, 2c), are synthesized from the stepwise reduction of (ICy)3CoCl by the corresponding alkaline metals under a N2 atmosphere. The bis(dinitrogen)cobalt(-1) complexes 2auc undergo protonation reaction with triflic acid to give N2H4 in 24u30% yields. The fine performance of the NHCucobalt complexes in the stoichiometric and catalytic N2-functionalization reactions points out the utility of low-valent low-coordinate group 9 metal species for N2 fixation.