Abstract
The homo- and heterogeneous dimers of diacetylene (H-C≡C-C≡C-H) and cyanogen (N≡C-C≡N) were studied using ab initio electronic structure computations to probe the effects of heterogeneity on noncovalent interactions between systems with delocalized π electron networks. Full geometry optimizations and harmonic vibrational frequencies were performed using the robust coupled-cluster with single and double and perturbative triple excitations (CCSD(T)) method with the triple-ζ plus 2 sets of polarization functions TZ2P(f,d)++ basis set. Seven basic configurations were examined for each dimer (cross, stacked, parallel-slipped, parallel-tipped, linear, T-shaped and Y-shaped), but only four stationary points were identified on the potential energy surfaces (PESs) of the homogeneous cyanogen dimer and the mixed diacetylene/cyanogen dimer. Six previously characterized stationary points on the diacetylene dimer PES were re-examined with the CCSD(T) method and the TZ2P(f,d)++ basis set for consistency. Second-order Møller-Plesset perturbation theory (MP2) and CCSD(T) complete basis set (CBS) limit interaction energies were estimated using the explicitly correlated MP2-F12 and CCSD(T)-F12 methods in conjunction with the VQZ-F12 basis set. On the cyanogen dimer PES, the C2v T-shaped structure is the only minimum, with an average electronic interaction energy, Eint, of -1.96 kcal mol-1 at the CCSD(T) CBS limit. The Cs Y-shaped structure (in agreement with previous results) is the global minimum on the diacetylene dimer PES, having a mean CCSD(T) CBS limit Eint of -1.75 kcal mol-1. Three low-lying minima have been identified on the diacetylene/cyanogen dimer PES, a C∞v linear, a C2v cross, and a Cs parallel-slipped structure with average CCSD(T) CBS limit interaction energies of -2.00, -2.16, and -2.45 kcal mol-1, respectively. © 2012 American Chemical Society.
Recommended Citation
K. L. Copeland and G. S. Tschumper, "Effects of Heterogeneity in Small Π-Type Dimers: Homogeneous and Mixed Dimers of Diacetylene and Cyanogen," Journal of Chemical Theory and Computation, vol. 8, no. 11, pp. 4279 - 4284, American Chemical Society, Nov 2012.
The definitive version is available at https://doi.org/10.1021/ct300644a
Department(s)
Chemistry
International Standard Serial Number (ISSN)
1549-9626; 1549-9618
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2024 American Chemical Society, All rights reserved.
Publication Date
13 Nov 2012
