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Decomposition of methylamino and aminomethyl radicals. The heats of formation of methyleneimine (CH 2 NH) and hydrazyl (N 2 H 3 ) radical
Author(s) -
Grela M. A.,
Colussi A. J.
Publication year - 1988
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550200905
Subject(s) - chemistry , radical , standard enthalpy of formation , thermal decomposition , decomposition , bond dissociation energy , electron paramagnetic resonance , diimine , kinetic energy , analytical chemistry (journal) , dissociation (chemistry) , nuclear magnetic resonance , organic chemistry , catalysis , physics , quantum mechanics
Abstract A kinetic analysis of the thermal decomposition of methylamino and aminomethyl radicals into methyleneimine, reactions (1) and (2):leads to ΔH f 0 (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 (NHNH)] then requires that E π (NHNH) = 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.