Issue 30, 2022

Chalcogen-bonded donor–acceptor complexes of 5,6-dicyano[1,2,5]selenadiazolo[3,4-b]pyrazine with halide ions

Abstract

New complexes of 5,6-dicyano[1,2,5]selenadiazolo[3,4-b]pyrazine 1 with halide anions X (X = Cl, Br, I) are prepared. With XRD, DFT, QTAIM and NBO, it is found that the complexes are formed via Se–X chalcogen bonding. Diffuse reflectance spectroscopy of polycrystalline samples and UV/Vis spectroscopy of solutions of [1–X] reveal significant spectral changes upon complexation. According to time-dependent DFT, these changes are caused by the appearance of charge transfer bands (p-AO(X) → LUMO(1)) in the visible region. The equilibrium constants for complex formation were measured with UV/Vis spectrophotometric titration and found to be significantly lower than those reported for structurally similar complexes of 3,4-dicyano-1,2,5-selena(tellura)diazoles, which indicates relatively weak chalcogen bonding in [1–X]. Dispersion-corrected DFT reproduces well the Gibbs free energies of complexation. The QTAIM descriptors and NBO analyses using second-order perturbation theory suggest that the Se–X chalcogen bonding in the studied complexes is predominantly electrostatic and dispersive in nature with a small but significant contribution from donor–acceptor (or orbital) interactions. The strongest contribution to the latter comes from negative hyperconjugation, i.e. donation of the electron density of the lone-pair of X onto the σ*–MO of the Se–N bond of 1.

Graphical abstract: Chalcogen-bonded donor–acceptor complexes of 5,6-dicyano[1,2,5]selenadiazolo[3,4-b]pyrazine with halide ions

Supplementary files

Article information

Article type
Paper
Submitted
12 Mai 2022
Accepted
01 Jul 2022
First published
04 Jul 2022

New J. Chem., 2022,46, 14490-14501

Chalcogen-bonded donor–acceptor complexes of 5,6-dicyano[1,2,5]selenadiazolo[3,4-b]pyrazine with halide ions

E. A. Radiush, E. A. Pritchina, E. A. Chulanova, A. A. Dmitriev, I. Y. Bagryanskaya, A. M. Z. Slawin, J. D. Woollins, N. P. Gritsan, A. V. Zibarev and N. A. Semenov, New J. Chem., 2022, 46, 14490 DOI: 10.1039/D2NJ02345H

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