Toward the Mechanism of Perchlorinated Cyclopentasilane (Si5Cl10) Ring Flattening in the [Si5Cl10·2Cl]2- Dianion

Konstantin Pokhodnya; Kenneth Anderson; Svetlana Kilina; Philip Boudjouk

doi:10.1021/acs.jpca.6b12938

Toward the Mechanism of Perchlorinated Cyclopentasilane (Si₅Cl₁₀) Ring Flattening in the [Si₅Cl₁₀·2Cl]^2- Dianion

J Phys Chem A. 2017 May 11;121(18):3494-3500. doi: 10.1021/acs.jpca.6b12938. Epub 2017 May 1.

Authors

Konstantin Pokhodnya¹, Kenneth Anderson¹, Svetlana Kilina¹, Philip Boudjouk¹

Affiliation

¹ Department of Chemistry and Biochemistry, North Dakota State University , Fargo, North Dakota 58108, United States.

PMID: 28406632
DOI: 10.1021/acs.jpca.6b12938

Abstract

We report the detailed computational study of flattening of the puckered Si₅ ring by suppression of the pseudo-Jahn-Teller (PJT) effect through coordination of two Cl^- anions to the molecule forming an inverse sandwich dianion [Si₅Cl₁₀·2Cl]^2- complex. The PJT effect that causes nonplanarity of the Si₅Cl₁₀ structure (C_s) results from vibronic coupling of pairs of occupied molecular orbitals (OMOs) and unoccupied molecular orbitals (UMOs). It was shown that filling the intervenient molecular orbitals of puckered Si₅Cl₁₀ with valent electron pairs of Cl^- donors suppresses the PJT effect, with the Si₅ ring becoming planar (D_5h) upon complex formation. In this paper, the stabilization energy E(2) associated with donor-acceptor charge transfer (delocalization) was estimated using NBO analysis for all studied inverse sandwich compounds [Si₅Cl₁₀·2X]^2- (where X = F, Cl, Br). It was found that the polarizability of the donor ion might significantly affect the stabilization energy value and should be taken into account when choosing the ligands suitable for forming Si-based one-dimensional compounds and other nanoscale materials.