A possible role for triplet H₂CN⁺ isomers in the formation of HCN and HNC in interstellar clouds

Journal Article · Wed Oct 01 00:00:00 EDT 1980 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.440520· OSTI ID:1133679

Allen, Thomas L. ^[1]; Goddard, John D. ^[2]; Schaefer, III, Henry F. ^[2]

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1. Univ. of California, Davis, CA (United States)
2. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

We determine the structures and energies of the lowest triplet states of four isomers of H₂CN⁺ by self-consistent field and configuration interaction calculations. When both hydrogen atoms are attached to the nitrogen atom, H₂CN⁺, the molecule has its lowest triplet state energy, which is 97.2 kcal mol^-1 above the energy of the linear singlet ground state. The structure has C_2v symmetry, with an HCH bond angle of 116.8°, and bond lengths of 1.009 Å (H–N) and 1.268 Å (N–C). Other isomers investigated include the H₂CN⁺ isomer at 104.7, the c i s-HCNH⁺ isomer at 105.3, and the t r a n s-HCNH⁺ isomer at 113.6 kcal mol^-1. The H₂CN⁺ isomer has an unusual ’’carbonium nitrene’’ structure, with a C–N bond length of 1.398 Å. It is suggested that the triplet H₂CN⁺ isomer may play a role in determining the relative yields of HCN and HNC from the reaction of C⁺ and NH₃. Specifically, a triplet path is postulated in which C+ and NH3 yield the triplet H₂NC⁺ isomer, which then yields the singlet H₂CN⁺ isomer by phosphorescent emission. Furthermore, because this emission removes a large amount of energy, the singlet H₂CN⁺ isomer may have insufficient energy to isomerize to the linear singlet ground state. Subsequent dissociative recombination would yield the HNC isomer exclusively.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: AC02-05CH11231; W-7405-ENG-48
• OSTI ID: 1133679
• Report Number(s): LBL-11923; JCPSA6
• Journal Information: Journal of Chemical Physics, Vol. 73, Issue 7; ISSN 0021-9606
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Chemical bonds
Ground states
Hydrogen energy
Electron correlation calculations
Hydrogen reactions