A "two-state reactivity" scenario has been computationally disclosed for dinitrogen activation by a diniobium tetrahydride. Remarkably, it is revealed that alkali metal cations play a crucial role via alkali center dot center dot center dot N coordination interaction, which is capable of decreasing the activation barriers of N-H formation and subsequent H-2 elimination in particular. Furthermore, the effect of various alkali metal cations has also been investigated systematically.