Abstract

The results are reported of potential energy surface (PES) analyses of six symmetrical azines Yp − Ph − RC=N − N=CR − Ph − Yp, namely, the benzaldehyde azines 1H, 2H, and 8H with R = H and the acetophenone azines 1M, 2M, and 8M with R = Me. The Y substituents Cl (1), Br (2), and Me (8) were studied because sets of polymorphs I (C2-symmetry, azine twist τ ≈ 135 ± 10°, disrotatory phenyl twists ϕi ≠ 0°) and II (Ci-symmetry, τ = 180°, conrotatory ϕi ≠ 0°) were crystallized for these three azines. The azine-Me groups in (E,E)-acetophenone azines cause steric strain with the N lone pairs, and this strain is reduced by small rotations about the Az-CH3 bonds and geared phenyl twisting may lead to C2- or Ci-structures. The in-depth exploration of the (τ, ϕ1, ϕ2) conformational space on the MP2(full)/6-311G* PES of 1M shows that the enantiomerization of C2-1M to C2-1M' involves, first, one Ph twist inversion to a Ci-like structure, the subsequent inversion of the azine twist in, and the, second, Ph twist inversion on the path to C2-1M'. The essential characteristics of this enantiomerization mechanism apply in general to disubstituted acetophenone azine.

Department(s)

Chemistry

Publication Status

Full Access

Comments

Missouri University of Science and Technology, Grant 1665487

Keywords and Phrases

1,4-diphenylazines; conformation; electron correlation; enantiomerization; nonbonded through-space interactions

International Standard Serial Number (ISSN)

1099-1395; 0894-3230

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2026 Wiley, All rights reserved.

Publication Date

01 Mar 2026

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