Mechanism. We considered the nitrogen atom attached to R 2 as the hydrogen acceptor (Figures and) because reacting on the R 1 nitrogen was on the order of 100 kJ mol -1 less energetically favourable, and was liable to cause the imide molecule to fall apart. For all variants of the gallium imides, analysis of the intrinsic reaction coordinate starting from the transition state shows that C -H bond cleavage is a concerted reaction (Figure ): methane loses the hydrogen to the nitrogen while simultaneously forming a C -Ga bond.