Figure 2 . (a)-(b) Values of charge transfer between TM1 and TM2 on TM2@site1, TM2@site2, TM3@site3, and TM4@site4 systems as well as the average charge transfer between them, respectively. (c) Schematic diagram of the N2 sensitive capture, activation, and hydrogenation under the ’capture-charge distribution-recapture-charge redistribution’ mechanism. (d) Gibbs free energy changes of the first hydrogenation for side on configuration in distal and proximal N2 side, the sky blue, cornflower-blue, and blue ball represent TM1, TM2, and, N atom, respectively.