Decomposition of methylamino and aminomethyl radicals. The heats of formation of methyleneimine (CH₂NH) and hydrazyl (N₂H₃) radical

A kinetic analysis of the thermal decomposition of methylamino and aminomethyl radicals into methyleneimine, reactions (1) and (2): equation image leads to ΔH (CH 2 NH) = 25.0 ± 3 kcal/mol in excellent agreement with ion cyclotron resonance spectroscopy measurements and to a pi bond energy of E π = 55.0 kcal/mol in CH 2 NH which is comparable but smaller than to the corresponding value in CH 2 CH 2 (63.7 kcal/mol). Assuming that E π (CH 2 NH) = 0.5 [E π (CH 2 CH 2 ) + E π (NHNH)] then requires that E π (NHNH) = 46.8 kcal/mol in diimine and BDE(N 2 H 3 ‐H) = 87.5 kcal/mol i.e. about 11.5 kcal/mol larger than current data for hydrazine but otherwise consistent with additional evidence. The entropy and heat capacity of methyleneimine, calculated from recent infrared and microwave spectroscopic data using the rigid rotor harmonic oscillator approximation, are also reported.