### Abstract

Ab initio molecular orbital calculations are performed for a series of lanthanide trihalides LnX_{3} (Ln = La to Lu; X = Cl, F), with the relativistic effective core potentials of Cundari and Stevens, to characterize the tendency in their electronic and geometric structures. In all the complexes (LnX_{3}), the planar structure (D(3h) symmetry) is calculated to be stable through normal mode analyses at the complete active space self-consistent field (CASSCF) levels. In the LnX_{3}, the number of 4f-electrons increases with increasing the atomic number, and 1.2-1.6 (2.1-2.2) electrons are transferred from Ln to Cl (F); the Ln-X bonds are dominated by charge- transfer but have a significant amount of covalent character that involves the 5d-orbital on Ln. It is also found that, along the lanthanide trihalide series, the first seven f-electrons occupy 4f-orbitals one by one from the lowest one up, while the second seven occupy 4f-orbitals from the highest one down, at the Hartree-Fock level. This occupation mechanism is explained in terms of the self-repulsion interactions between two electrons occupying the same spatial 4f-orbital. The Ln-X bond lengths, net charges, and vibrational frequencies show monotonic variation along the lanthanide series, which corresponds to the lanthanide contraction. State-averaged CASSCF calculations are also carried out for LnCl_{3}, in a combination with spin-orbit calculations using the atomic spin-orbit coupling constant for the f- electrons, to investigate the energy splitting of the nearly-degenerate low- lying states in the scheme of L-S coupling.

Original language | English |
---|---|

Pages (from-to) | 203-222 |

Number of pages | 20 |

Journal | Journal of Molecular Structure: THEOCHEM |

Volume | 461-462 |

DOIs | |

Publication status | Published - Apr 2 1999 |

Externally published | Yes |

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### All Science Journal Classification (ASJC) codes

- Biochemistry
- Condensed Matter Physics
- Physical and Theoretical Chemistry

### Cite this

_{3}(Ln = La-Lu; X = Cl, F).

*Journal of Molecular Structure: THEOCHEM*,

*461-462*, 203-222. https://doi.org/10.1016/S0166-1280(98)00461-8

**Theoretical study of electronic and geometric structures of a series of lanthanide trihalides LnX _{3} (Ln = La-Lu; X = Cl, F).** / Tsuchiya, Takashi; Taketsugu, Tetsuya; Nakano, Haruyuki; Hirao, Kimihiko.

Research output: Contribution to journal › Article

_{3}(Ln = La-Lu; X = Cl, F)',

*Journal of Molecular Structure: THEOCHEM*, vol. 461-462, pp. 203-222. https://doi.org/10.1016/S0166-1280(98)00461-8

_{3}(Ln = La-Lu; X = Cl, F). Journal of Molecular Structure: THEOCHEM. 1999 Apr 2;461-462:203-222. https://doi.org/10.1016/S0166-1280(98)00461-8

}

TY - JOUR

T1 - Theoretical study of electronic and geometric structures of a series of lanthanide trihalides LnX3 (Ln = La-Lu; X = Cl, F)

AU - Tsuchiya, Takashi

AU - Taketsugu, Tetsuya

AU - Nakano, Haruyuki

AU - Hirao, Kimihiko

PY - 1999/4/2

Y1 - 1999/4/2

N2 - Ab initio molecular orbital calculations are performed for a series of lanthanide trihalides LnX3 (Ln = La to Lu; X = Cl, F), with the relativistic effective core potentials of Cundari and Stevens, to characterize the tendency in their electronic and geometric structures. In all the complexes (LnX3), the planar structure (D(3h) symmetry) is calculated to be stable through normal mode analyses at the complete active space self-consistent field (CASSCF) levels. In the LnX3, the number of 4f-electrons increases with increasing the atomic number, and 1.2-1.6 (2.1-2.2) electrons are transferred from Ln to Cl (F); the Ln-X bonds are dominated by charge- transfer but have a significant amount of covalent character that involves the 5d-orbital on Ln. It is also found that, along the lanthanide trihalide series, the first seven f-electrons occupy 4f-orbitals one by one from the lowest one up, while the second seven occupy 4f-orbitals from the highest one down, at the Hartree-Fock level. This occupation mechanism is explained in terms of the self-repulsion interactions between two electrons occupying the same spatial 4f-orbital. The Ln-X bond lengths, net charges, and vibrational frequencies show monotonic variation along the lanthanide series, which corresponds to the lanthanide contraction. State-averaged CASSCF calculations are also carried out for LnCl3, in a combination with spin-orbit calculations using the atomic spin-orbit coupling constant for the f- electrons, to investigate the energy splitting of the nearly-degenerate low- lying states in the scheme of L-S coupling.

AB - Ab initio molecular orbital calculations are performed for a series of lanthanide trihalides LnX3 (Ln = La to Lu; X = Cl, F), with the relativistic effective core potentials of Cundari and Stevens, to characterize the tendency in their electronic and geometric structures. In all the complexes (LnX3), the planar structure (D(3h) symmetry) is calculated to be stable through normal mode analyses at the complete active space self-consistent field (CASSCF) levels. In the LnX3, the number of 4f-electrons increases with increasing the atomic number, and 1.2-1.6 (2.1-2.2) electrons are transferred from Ln to Cl (F); the Ln-X bonds are dominated by charge- transfer but have a significant amount of covalent character that involves the 5d-orbital on Ln. It is also found that, along the lanthanide trihalide series, the first seven f-electrons occupy 4f-orbitals one by one from the lowest one up, while the second seven occupy 4f-orbitals from the highest one down, at the Hartree-Fock level. This occupation mechanism is explained in terms of the self-repulsion interactions between two electrons occupying the same spatial 4f-orbital. The Ln-X bond lengths, net charges, and vibrational frequencies show monotonic variation along the lanthanide series, which corresponds to the lanthanide contraction. State-averaged CASSCF calculations are also carried out for LnCl3, in a combination with spin-orbit calculations using the atomic spin-orbit coupling constant for the f- electrons, to investigate the energy splitting of the nearly-degenerate low- lying states in the scheme of L-S coupling.

UR - http://www.scopus.com/inward/record.url?scp=0033515412&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033515412&partnerID=8YFLogxK

U2 - 10.1016/S0166-1280(98)00461-8

DO - 10.1016/S0166-1280(98)00461-8

M3 - Article

AN - SCOPUS:0033515412

VL - 461-462

SP - 203

EP - 222

JO - Computational and Theoretical Chemistry

JF - Computational and Theoretical Chemistry

SN - 2210-271X

ER -