### Abstract

Ab initio SCF molecular orbital calculations with complete geometry optimization have been performed using consistent basis sets for each member of the series NH_{3}, NH_{2}F, NH_{2}, NF_{3} and PH_{3}, PH_{2}F, PHF_{2}, PF_{3}. 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 language | English (US) |
---|---|

Pages (from-to) | 5769-5776 |

Number of pages | 8 |

Journal | The Journal of Chemical Physics |

Volume | 66 |

Issue number | 12 |

DOIs | |

State | Published - Jan 1 1977 |

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### All Science Journal Classification (ASJC) codes

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

### Cite this

_{3}, NH

_{2}F, NH

_{2}, NF

_{3}and PH

_{3}, PH

_{2}F, PHF

_{2}, PF

_{3}

*The Journal of Chemical Physics*,

*66*(12), 5769-5776. https://doi.org/10.1063/1.433852

}

_{3}, NH

_{2}F, NH

_{2}, NF

_{3}and PH

_{3}, PH

_{2}F, PHF

_{2}, PF

_{3}',

*The Journal of Chemical Physics*, vol. 66, no. 12, pp. 5769-5776. https://doi.org/10.1063/1.433852

**Ab initio investigation of geometry changes during inversion of NH _{3}, NH_{2}F, NH_{2}, NF_{3} and PH _{3}, PH_{2}F, PHF_{2}, PF_{3} .** / Schmiedekamp, Ann Marie; Skaarup, Steen; Pulay, Péter; Boggs, James E.

Research output: Contribution to journal › Article

TY - JOUR

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.

PY - 1977/1/1

Y1 - 1977/1/1

N2 - 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.

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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U2 - 10.1063/1.433852

DO - 10.1063/1.433852

M3 - Article

AN - SCOPUS:0006449366

VL - 66

SP - 5769

EP - 5776

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 12

ER -

_{3}, NH

_{2}F, NH

_{2}, NF

_{3}and PH

_{3}, PH

_{2}F, PHF

_{2}, PF

_{3}The Journal of Chemical Physics. 1977 Jan 1;66(12):5769-5776. https://doi.org/10.1063/1.433852