An ab initio study of the geometry, energy, and selected force constants for the three planar conformers of carbonic acid, and the bicarbonate ion; and of the energy for the reaction H 2 O + CO 2 → H 2 CO 3
Abstract Ab initio calculations using the unscaled 4‐31 G basis set have been carried out on the cc, tc , and tt conformers of carbonic acid and the bicarbonate ion, with full geometry optimization assuming the structures to be planar. The complete harmonic force field is reported for the (most stab...
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crwiley:10.1002/jcc.540030303 2024-06-02T08:05:12+00:00 An ab initio study of the geometry, energy, and selected force constants for the three planar conformers of carbonic acid, and the bicarbonate ion; and of the energy for the reaction H 2 O + CO 2 → H 2 CO 3 George, Philip Bock, Charles W. Trachtman, Mendel 1982 http://dx.doi.org/10.1002/jcc.540030303 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjcc.540030303 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jcc.540030303 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Computational Chemistry volume 3, issue 3, page 283-296 ISSN 0192-8651 1096-987X journal-article 1982 crwiley https://doi.org/10.1002/jcc.540030303 2024-05-03T11:42:52Z Abstract Ab initio calculations using the unscaled 4‐31 G basis set have been carried out on the cc, tc , and tt conformers of carbonic acid and the bicarbonate ion, with full geometry optimization assuming the structures to be planar. The complete harmonic force field is reported for the (most stable) tt conformer and for the bicarbonate ion, also selected quadratic force constants for the cc and tc conformers. The changes in certain bond lengths and stretching force constants in the cc → tc, tc → tt , and cc → tt conformer conversion reactions are indicative of intramolecular hydrogen bonding, CO…HO and HO…HO, which is examined in greater detail by partitioning the overall conformer conversion energy into distortion and bonding energy components. The fundamental vibration frequencies for the tt conformer and the bicarbonate ion are calculated from the force constant matrices, and hence, using a scaling factor based on a comparison of calculated and experimental values for the bicarbonate ion and trans ‐formic acid, a value is predicted for the zero‐point energy of the tt conformer. A new estimate of Δ H ˚ for the hydration reaction, H 2 O + CO 2 → H 2 CO 3 , at 298 K in the gas phase; is made from thermochemical data, +20.2 ± 3.4 kJ mol −1 , which, together with estimates of ( H 298 ˚ – H 0 ˚) and the zero‐point energy for H 2 CO 3 , gives +8.1 ± 7.0 kJ mol −1 for Δ E T (expt). Δ E T calculated from the 4‐31 G basis set data is ‐29.1 kJ mol −1 . Comparison of the experimental value, the Hartree–Fock limit value, and values calculated with a variety of basis sets for the bond separation reaction, CO 2 + CH 4 → 2H 2 CO, suggests that the differences, Δ E T (expt) minus Δ E T ( SCF ), are due mainly to basis set limitations and not substantial correlation energy contributions. Article in Journal/Newspaper Carbonic acid Wiley Online Library Hartree ENVELOPE(-44.716,-44.716,-60.783,-60.783) Zero Point ENVELOPE(-37.150,-37.150,-54.117,-54.117) Journal of Computational Chemistry 3 3 283 296 |
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Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
Abstract Ab initio calculations using the unscaled 4‐31 G basis set have been carried out on the cc, tc , and tt conformers of carbonic acid and the bicarbonate ion, with full geometry optimization assuming the structures to be planar. The complete harmonic force field is reported for the (most stable) tt conformer and for the bicarbonate ion, also selected quadratic force constants for the cc and tc conformers. The changes in certain bond lengths and stretching force constants in the cc → tc, tc → tt , and cc → tt conformer conversion reactions are indicative of intramolecular hydrogen bonding, CO…HO and HO…HO, which is examined in greater detail by partitioning the overall conformer conversion energy into distortion and bonding energy components. The fundamental vibration frequencies for the tt conformer and the bicarbonate ion are calculated from the force constant matrices, and hence, using a scaling factor based on a comparison of calculated and experimental values for the bicarbonate ion and trans ‐formic acid, a value is predicted for the zero‐point energy of the tt conformer. A new estimate of Δ H ˚ for the hydration reaction, H 2 O + CO 2 → H 2 CO 3 , at 298 K in the gas phase; is made from thermochemical data, +20.2 ± 3.4 kJ mol −1 , which, together with estimates of ( H 298 ˚ – H 0 ˚) and the zero‐point energy for H 2 CO 3 , gives +8.1 ± 7.0 kJ mol −1 for Δ E T (expt). Δ E T calculated from the 4‐31 G basis set data is ‐29.1 kJ mol −1 . Comparison of the experimental value, the Hartree–Fock limit value, and values calculated with a variety of basis sets for the bond separation reaction, CO 2 + CH 4 → 2H 2 CO, suggests that the differences, Δ E T (expt) minus Δ E T ( SCF ), are due mainly to basis set limitations and not substantial correlation energy contributions. |
format |
Article in Journal/Newspaper |
author |
George, Philip Bock, Charles W. Trachtman, Mendel |
spellingShingle |
George, Philip Bock, Charles W. Trachtman, Mendel An ab initio study of the geometry, energy, and selected force constants for the three planar conformers of carbonic acid, and the bicarbonate ion; and of the energy for the reaction H 2 O + CO 2 → H 2 CO 3 |
author_facet |
George, Philip Bock, Charles W. Trachtman, Mendel |
author_sort |
George, Philip |
title |
An ab initio study of the geometry, energy, and selected force constants for the three planar conformers of carbonic acid, and the bicarbonate ion; and of the energy for the reaction H 2 O + CO 2 → H 2 CO 3 |
title_short |
An ab initio study of the geometry, energy, and selected force constants for the three planar conformers of carbonic acid, and the bicarbonate ion; and of the energy for the reaction H 2 O + CO 2 → H 2 CO 3 |
title_full |
An ab initio study of the geometry, energy, and selected force constants for the three planar conformers of carbonic acid, and the bicarbonate ion; and of the energy for the reaction H 2 O + CO 2 → H 2 CO 3 |
title_fullStr |
An ab initio study of the geometry, energy, and selected force constants for the three planar conformers of carbonic acid, and the bicarbonate ion; and of the energy for the reaction H 2 O + CO 2 → H 2 CO 3 |
title_full_unstemmed |
An ab initio study of the geometry, energy, and selected force constants for the three planar conformers of carbonic acid, and the bicarbonate ion; and of the energy for the reaction H 2 O + CO 2 → H 2 CO 3 |
title_sort |
ab initio study of the geometry, energy, and selected force constants for the three planar conformers of carbonic acid, and the bicarbonate ion; and of the energy for the reaction h 2 o + co 2 → h 2 co 3 |
publisher |
Wiley |
publishDate |
1982 |
url |
http://dx.doi.org/10.1002/jcc.540030303 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjcc.540030303 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jcc.540030303 |
long_lat |
ENVELOPE(-44.716,-44.716,-60.783,-60.783) ENVELOPE(-37.150,-37.150,-54.117,-54.117) |
geographic |
Hartree Zero Point |
geographic_facet |
Hartree Zero Point |
genre |
Carbonic acid |
genre_facet |
Carbonic acid |
op_source |
Journal of Computational Chemistry volume 3, issue 3, page 283-296 ISSN 0192-8651 1096-987X |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/jcc.540030303 |
container_title |
Journal of Computational Chemistry |
container_volume |
3 |
container_issue |
3 |
container_start_page |
283 |
op_container_end_page |
296 |
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1800749981658775552 |