Journal article

Publication year: 2016

Pages: 4707-4717

Journal: Journal of Chemical Theory and Computation

Volume number: 12

Issue number: 9

ISSN: 1549-9618

DOI Link: https://doi.org/10.1021/acs.jctc.6b00669

Publisher: American Chemical Society

Abstract: 

The infinite spiro-annelation of cyclopropanes in a nonbranched form
will produce a σ-helicene called polytriangulane, which is an unknown
hydrocarbon with the formula C_nH_n comprised exclusively of formal C(sp³) atoms. The structure of polytriangulane is elucidated here via a rigorous mathematical analysis of a C₈₅H₈₈
prototype optimized by M06-2X/6-31G(d) density functional theory and an
idealized polymer composed of equilateral cyclopropane units. The spiro
carbons in polytriangulane form an exact, nonrepeating helix with a
steep rise angle near 35°, a radius of only 0.41 Å, and irrational
periodicity parameter very close to .
A focal point analysis of the ring opening of cyclopropane to propene
employing basis sets as large as cc-pCV5Z and correlation treatments as
extensive as CCSDT(Q) yields Δ_fH₀^°(cyclopropane) = 17.2 ± 0.1 kcal mol^–1. Subsequent application of CCSD(T)/CBS theory to a homodesmotic equation for ring aggregation predicts that Δ_fH₀^° = +16.1 kcal (mol CH)⁻¹
for polytriangulane; hence, this compound is much more stable
thermodynamically than acetylene. Similar computations on another
hypothetical homodesmotic transformation indicate that the total strain
energy in polytriangulane is 42.7 kcal per mole of cyclopropane units.

Harvard Citation style: Allen, W., Quanz, H. and Schreiner, P. (2016) Polytriangulane, Journal of Chemical Theory and Computation, 12(9), pp. 4707-4717. https://doi.org/10.1021/acs.jctc.6b00669

APA Citation style: Allen, W., Quanz, H., & Schreiner, P. (2016). Polytriangulane. Journal of Chemical Theory and Computation. 12(9), 4707-4717. https://doi.org/10.1021/acs.jctc.6b00669