Reaction energies. It is desirable that the overall reaction energy between methane and gallium imide is only moderately negative, so that the product of the C -H bond cleavage can undergo further transformation instead of becoming trapped in the low-energy state. We found that using C 6 F 5 groups as R 1 makes the reaction more exothermic, which is undesirable, whilst using electron-donating TMS has the opposite effect (Figure ). of C-H bonds. .