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Title: On the Structure and Chemical Bonding of Si62- and Si62- in NaSi6- Upon Na+ Coordination

Abstract

Photoelectron spectroscopy was combined with ab initio calculations to elucidate the structure and bonding in Si62- and NaSi6-. Well-resolved electronic transitions were observed in the photoelectron spectra of Si6- and NaSi6- at three photon energies (355, 266, and 193 nm). The spectra of NaSi6- were observed to be similar to those of Si6- except that the electron binding energies of the former are lower, suggesting that the Si6 motif in NaSi6- is structurally and electronically similar to that of Si6-. The electron affinity of Si6 and NaSi6 were measured fairly accurately to be 2.23 ± 0.03 eV and 1.80 ± 0.05 eV, respectively. Global minimum structure searches for Si62- and NaSi6- were performed using Gradient Embedded Genetic Algorithm followed by B3LYP, MP2 and CCSD(T) calculations. Vertical electron detachment energies (VDEs) were calculated for the lowest Si6- and NaSi6- structures at the CCSD(T)/6-311+G(2df), ROVGF/6-311+G(2df), UOVGF/6-311+G(2d), TD B3LYP/6-311+G(2df) levels of theory. Experimental VDEs were used to verify the global minimum structure for NaSi6-. Though the octahedral Si62-, analogous to the closo-form of borane B6H62-, is the most stable form for the bare hexa-silicon dianion, it is not the kernel for the NaSi6- global minimum. The most stable isomer of NaSi6- is basedmore » on a Si62- motif, which is distorted into C2v symmetry similar to the ground state structure of Si6-. The octahedral Si62- coordinated by a Na+ is a low-lying isomer and was also observed experimentally. The chemical bonding in Si62- and NaSi6- was understood using NBO, molecular orbital, and ELF analysis.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
882967
Report Number(s):
PNNL-SA-48283
3689; KP1303000
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics, 124(12):Article No. 124305
Country of Publication:
United States
Language:
English
Subject:
Environmental Molecular Sciences Laboratory

Citation Formats

Zubarev, Dmitry Y., Alexandrova, Anastassia N., Boldyrev, Alexander I., Cui, Lifeng, Li, Xi, and Wang, Lai S. On the Structure and Chemical Bonding of Si62- and Si62- in NaSi6- Upon Na+ Coordination. United States: N. p., 2006. Web. doi:10.1063/1.2177254.
Zubarev, Dmitry Y., Alexandrova, Anastassia N., Boldyrev, Alexander I., Cui, Lifeng, Li, Xi, & Wang, Lai S. On the Structure and Chemical Bonding of Si62- and Si62- in NaSi6- Upon Na+ Coordination. United States. doi:10.1063/1.2177254.
Zubarev, Dmitry Y., Alexandrova, Anastassia N., Boldyrev, Alexander I., Cui, Lifeng, Li, Xi, and Wang, Lai S. 2006. "On the Structure and Chemical Bonding of Si62- and Si62- in NaSi6- Upon Na+ Coordination". United States. doi:10.1063/1.2177254.
@article{osti_882967,
title = {On the Structure and Chemical Bonding of Si62- and Si62- in NaSi6- Upon Na+ Coordination},
author = {Zubarev, Dmitry Y. and Alexandrova, Anastassia N. and Boldyrev, Alexander I. and Cui, Lifeng and Li, Xi and Wang, Lai S.},
abstractNote = {Photoelectron spectroscopy was combined with ab initio calculations to elucidate the structure and bonding in Si62- and NaSi6-. Well-resolved electronic transitions were observed in the photoelectron spectra of Si6- and NaSi6- at three photon energies (355, 266, and 193 nm). The spectra of NaSi6- were observed to be similar to those of Si6- except that the electron binding energies of the former are lower, suggesting that the Si6 motif in NaSi6- is structurally and electronically similar to that of Si6-. The electron affinity of Si6 and NaSi6 were measured fairly accurately to be 2.23 ± 0.03 eV and 1.80 ± 0.05 eV, respectively. Global minimum structure searches for Si62- and NaSi6- were performed using Gradient Embedded Genetic Algorithm followed by B3LYP, MP2 and CCSD(T) calculations. Vertical electron detachment energies (VDEs) were calculated for the lowest Si6- and NaSi6- structures at the CCSD(T)/6-311+G(2df), ROVGF/6-311+G(2df), UOVGF/6-311+G(2d), TD B3LYP/6-311+G(2df) levels of theory. Experimental VDEs were used to verify the global minimum structure for NaSi6-. Though the octahedral Si62-, analogous to the closo-form of borane B6H62-, is the most stable form for the bare hexa-silicon dianion, it is not the kernel for the NaSi6- global minimum. The most stable isomer of NaSi6- is based on a Si62- motif, which is distorted into C2v symmetry similar to the ground state structure of Si6-. The octahedral Si62- coordinated by a Na+ is a low-lying isomer and was also observed experimentally. The chemical bonding in Si62- and NaSi6- was understood using NBO, molecular orbital, and ELF analysis.},
doi = {10.1063/1.2177254},
journal = {Journal of Chemical Physics, 124(12):Article No. 124305},
number = ,
volume = ,
place = {United States},
year = 2006,
month = 3
}
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