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Ab initio study of the reaction of CHO + with H 2 O and NH 3
Author(s) -
López R.,
Del Río E.,
Menéndez M. I.,
Sordo T. L.
Publication year - 1999
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/(sici)1096-987x(199910)20:13<1432::aid-jcc10>3.0.co;2-o
Subject(s) - chemistry , ab initio , protonation , gibbs free energy , ab initio quantum chemistry methods , computational chemistry , tautomer , ammonia , formic acid , proton affinity , molecule , ion , thermodynamics , stereochemistry , organic chemistry , physics
An MP4(full,SDTQ)/6‐311++G(d,p)//MP2(full)/6‐311++G(d,p) ab initio study was performed of the reactions of formyl and isoformyl cations with H 2 O and NH 3 , which play an important role in flame and interstellar chemistries. Two different confluent channels were located leading to CO+H 3 O + /NH 4 + . The first one corresponds to the approach of the neutral molecule to the carbon atom of the cations. The second one leads to the direct proton transfer from the cations to the neutrals. At 900 K the separate products CO+H 3 O + /NH 4 +are the most stable species along the Gibbs energy profiles for the processes. For the reaction with H 2 O the reaction channel leading to HC(OH) 2 +(protonated formic acid) is disfavored with respect to the two CO+H 3 O + channels in agreement with the experimental evidence that H 3 O + is the major ion observed in hydrocarbon flames. According to our calculations, NH 4 + +H 2 O are considerably more stable in Gibbs energy than NH 3 +H 3 O + ;NH 4 +will predominate in the reaction zone when ammonia is added to CH 4 +Ar diffusion flame, as experimentally observed. At 100 K the most stable structures are the intermediate complexes CO…HOH 2 + /HNH 3 + . Particularly the CO…HOH 2 +complex has a lifetime large enough to be detected and, therefore, could play a certain role in interstellar chemistry. ©1999 John Wiley & Sons, Inc. J Comput Chem 20: 1432–1443, 1999