The Pseudo Jahn-Teller effect and NBO analysis for untangling the symmetry breaking in the planar configurations of M 2 X 4 + (M = Si, Ge and X = Cl, Br, I): effect on electronic structure and chemical properties.

Autor: Kouchakzadeh G; Department of Chemistry, Khorramabad Branch, Islamic Azad University, Khorramabad, Iran. gh_kouchakzadeh@yahoo.com., Mahmoudzadeh G; The Ministry of Education Tehran, Tehran, Iran.
Jazyk: angličtina
Zdroj: Journal of molecular modeling [J Mol Model] 2023 Dec 06; Vol. 30 (1), pp. 1. Date of Electronic Publication: 2023 Dec 06.
DOI: 10.1007/s00894-023-05792-1
Abstrakt: Context: The Pseudo Jahn- Teller effect is a significant tool for evaluating molecular distortion and symmetry breaking. The PJT effect associated with NBO analysis can be a powerful method for studying the structural properties variations arising from D 2h  → C 2h distortions. The theoretical studies on Si 2 X 4 + and Ge 2 X 4 + radical cations have been rare. The calculations have shown that C 2h non-planar structures are more stable than planar structures with D 2h symmetry. The [Formula: see text] PJTE problem of M 2 X 4 + compounds is a result of the coupling between the ground B 3u state and the exited B 1u state in the Q b2g direction causes. Also, the difference in M and X atoms can affect the PJT instability of compounds. The findings of this work show that the energy gap between the ground and excited states that have D 2h symmetry decreases from M 2 Cl 4 + to M 2 I 4 + and increases from Si 2 X 4 + to Ge 2 X 4 + . In fact, there is a significant relationship between instability of high-symmetry configurations, geometric parameters, electron delocalization, chemical hardness, electronegativity, electrophilicity index, and PJT stabilization energies. These results may serve to evaluate the distortion of similar systems.
Methods: The structures of Si 2 X 4 + and Ge 2 X 4 + are optimized by LC-BLYP, M06-2X, and B3LYP methods with def2-TZVPP basis set in GAMESS software. The details of the excited states of compounds are studied by the TD-DFT method. NBO analysis for planar and non-planar structures is carried out at B3LYP/def2-TZVPP level by the NBO 5. G program that demonstrates HOMO, LUMO, ED, bonding and antibonding orbital occupancies, bond order, and E 2 .
(© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)
Databáze: MEDLINE
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