Ab initio investigation of geometry changes during inversion of NH 3, NH2F, NH2, NF3 and PH 3, PH2F, PHF2, PF3

Ann Marie Schmiedekamp, Steen Skaarup, Péter Pulay, James E. Boggs

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

Ab initio SCF molecular orbital calculations with complete geometry optimization have been performed using consistent basis sets for each member of the series NH3, NH2F, NH2, NF3 and PH3, PH2F, PHF2, PF3. The calculations were repeated using the same basis sets with the molecules constrained to the planar configuration which is the transition state for inversion, all other geometrical parameters being energy optimized. In the planar configuration, shorter N-F, N-H, and P-H bonds resulted as well as a change from the nearly equal pyramidal bond angles to highly asymmetric planar bond angles with ∠HXH> ∠HXF> ∠FXF. Omission of polarization functions from the basis set produced longer P-F and N-F bonds. Regardless of the inclusion or exclusion of d atomic Orbitals in the basis set, substitution of fluorine for hydrogen yields regular increases in inversion barrier heights. Exclusion of d atomic orbitals results in inversion barriers that are smaller by nearly the same amount for all molecules in a series. The increase in barrier with substitution of fluorine for hydrogen is correlated with an increase of s character in the lone pair. Dipole moment and components, bond moments, and lone pair moments are discussed. Effects of varying the d orbital exponent coefficient on the central atom were examined.

Original languageEnglish (US)
Pages (from-to)5769-5776
Number of pages8
JournalThe Journal of Chemical Physics
Volume66
Issue number12
DOIs
StatePublished - Jan 1 1977

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Fluorine
Hydrogen
Substitution reactions
inversions
exclusion
orbitals
Orbital calculations
Molecules
fluorine
Geometry
Dipole moment
Molecular orbitals
geometry
substitutes
moments
hydrogen
Polarization
configurations
Atoms
self consistent fields

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

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abstract = "Ab initio SCF molecular orbital calculations with complete geometry optimization have been performed using consistent basis sets for each member of the series NH3, NH2F, NH2, NF3 and PH3, PH2F, PHF2, PF3. The calculations were repeated using the same basis sets with the molecules constrained to the planar configuration which is the transition state for inversion, all other geometrical parameters being energy optimized. In the planar configuration, shorter N-F, N-H, and P-H bonds resulted as well as a change from the nearly equal pyramidal bond angles to highly asymmetric planar bond angles with ∠HXH> ∠HXF> ∠FXF. Omission of polarization functions from the basis set produced longer P-F and N-F bonds. Regardless of the inclusion or exclusion of d atomic Orbitals in the basis set, substitution of fluorine for hydrogen yields regular increases in inversion barrier heights. Exclusion of d atomic orbitals results in inversion barriers that are smaller by nearly the same amount for all molecules in a series. The increase in barrier with substitution of fluorine for hydrogen is correlated with an increase of s character in the lone pair. Dipole moment and components, bond moments, and lone pair moments are discussed. Effects of varying the d orbital exponent coefficient on the central atom were examined.",
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Ab initio investigation of geometry changes during inversion of NH 3, NH2F, NH2, NF3 and PH 3, PH2F, PHF2, PF3 . / Schmiedekamp, Ann Marie; Skaarup, Steen; Pulay, Péter; Boggs, James E.

In: The Journal of Chemical Physics, Vol. 66, No. 12, 01.01.1977, p. 5769-5776.

Research output: Contribution to journalArticle

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T1 - Ab initio investigation of geometry changes during inversion of NH 3, NH2F, NH2, NF3 and PH 3, PH2F, PHF2, PF3

AU - Schmiedekamp, Ann Marie

AU - Skaarup, Steen

AU - Pulay, Péter

AU - Boggs, James E.

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AB - Ab initio SCF molecular orbital calculations with complete geometry optimization have been performed using consistent basis sets for each member of the series NH3, NH2F, NH2, NF3 and PH3, PH2F, PHF2, PF3. The calculations were repeated using the same basis sets with the molecules constrained to the planar configuration which is the transition state for inversion, all other geometrical parameters being energy optimized. In the planar configuration, shorter N-F, N-H, and P-H bonds resulted as well as a change from the nearly equal pyramidal bond angles to highly asymmetric planar bond angles with ∠HXH> ∠HXF> ∠FXF. Omission of polarization functions from the basis set produced longer P-F and N-F bonds. Regardless of the inclusion or exclusion of d atomic Orbitals in the basis set, substitution of fluorine for hydrogen yields regular increases in inversion barrier heights. Exclusion of d atomic orbitals results in inversion barriers that are smaller by nearly the same amount for all molecules in a series. The increase in barrier with substitution of fluorine for hydrogen is correlated with an increase of s character in the lone pair. Dipole moment and components, bond moments, and lone pair moments are discussed. Effects of varying the d orbital exponent coefficient on the central atom were examined.

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