Effect of Conformation on Electron Localization and Delocalization in Infinite Helical Chains [X(CH3)2]∞ (X = Si, Ge, Sn, and Pb)

0508874 - ÚOCHB 2020 RIV US eng J - Journal Article
Jovanovic, Milena - Michl, Josef
Effect of Conformation on Electron Localization and Delocalization in Infinite Helical Chains [X(CH3)2]∞ (X = Si, Ge, Sn, and Pb).
Journal of the American Chemical Society. Roč. 141, č. 33 (2019), s. 13101-13113. ISSN 0002-7863. E-ISSN 1520-5126
Institutional support: RVO:61388963
Keywords : electronegativity values * sigma conjugation * linear chains
OECD category: Physical chemistry
Impact factor: 14.612, year: 2019
Method of publishing: Limited access
https://pubs.acs.org/doi/10.1021/jacs.9b04780

An intuitive explanation of the effects of conformation (backbone dihedral angle) on electron delocalization in infinite saturated regular helices [(CH3)2]∞Si, [(CH3)2Ge]∞, [(CH3)2Sn]∞, and [(CH3)2Pb]∞ is offered in terms of the simple Ladder C model and confirmed by density functional theory calculations. The effective hole mass, which ranges from near zero to infinity as a function of conformation, is used as a measure of the degree of delocalization and relates to the effects of chain length extension in finite systems. The position of the Fermi level in reciprocal space has a simple counterpart in systems of finite length and is used to characterize the dominant mechanism, σ conjugation (geminal interactions) or σ hyperconjugation (vicinal interactions, through-bond coupling). Constructive or destructive interference of the two mechanisms produces three different delocalization regimes as a function of the backbone dihedral angle and analogy is drawn to polycyclic π-electron systems consisting of fused Hückel or Möbius four-membered rings.
Permanent Link: http://hdl.handle.net/11104/0299667