Theoretical studies of the reactions of HCN with atomic hydrogen

Journal Article · Fri Mar 01 04:00:00 EST 1985 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.448323· OSTI ID:6061669

Bair, R A; Dunning, Jr, T H

A comprehensive theoretical study has been made of the energetics of the important pathways involved in the reaction of hydrogen atoms with hydrogen cyanide. For each reaction ab initio GVB-CI calculations were carried out to determine the structures and vibrational frequencies of the reactants, transition states, and products; then POL-CI calculations were carried out to more accurately estimate the electronic contribution to the energetics of the reactions. The hydrogen abstraction reaction is calculated to be endoergic by 24 kcal/mol (expt. ..delta..H (0 K) = 16--19 kcal/mol) with a barrier of 31 kcal/mol in the forward direction and 6 kcal/mol in the reverse direction. For the hydrogen addition reactions, addition to the carbon atom is calculated to be exoergic by 19 kcal/mol with a barrier of 11 kcal/mol, while addition to the nitrogen center is essentially thermoneutral with a barrier of 17 kcal/mol. Calculations were also carried out on the isomerization reactions of the addition products. The cis..-->..trans isomerization of HCNH has a barrier of only 10 kcal/mol with the trans isomer being more stable by 5 kcal/mol. The (1,2)-hydrogen migration reaction, converting H/sub 2/CN to trans-HCNH, is endoergic by only 14 kcal/mol, but the calculated barrier for the transfer is 52 kcal/mol. The energy of the migration pathway thus lies above that of the dissociation--recombination pathway.

• Research Organization: Theoretical Chemistry Group, Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6061669
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 82:5; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMBUSTION
CONFIGURATION INTERACTION
CYANIDES
ELEMENTS
FLAMES
HYDROCYANIC ACID
HYDROGEN
HYDROGEN COMPOUNDS
INORGANIC ACIDS
ISOMERIZATION
KINETICS
NONMETALS
OXIDATION
REACTION KINETICS
THERMOCHEMICAL PROCESSES