TY - JOUR

T1 - Chalcogen-bonded donor-acceptor complexes of 5,6-dicyano[1,2,5]selenadiazolo[3,4-b]pyrazine with halide ions

AU - Radiush, Ekaterina A.

AU - Pritchina, Elena A.

AU - Chulanova, Elena A.

AU - Dmitriev, Alexey A.

AU - Bagryanskaya, Irina Yu

AU - Slawin, Alexandra M.Z.

AU - Woollins, J. Derek

AU - Gritsan, Nina P.

AU - Zibarev, Andrey V.

AU - Semenov, Nikolay A.

N1 - Funding Information: The authors are grateful to the Russian Science Foundation (Grant 21-73-10291) for the financial support (syntheses, XRD and spectroscopy, calculation of MEPs). Instrumentation of the Multi-Access Chemical Research Center of the Siberian Branch of the Russian Academy of Sciences was used. A. A. D, E. A. P. and N. P. G. acknowledge the Ministry of Science and Higher Education of the Russian Federation (Project FWGF-2021-0002) for financial support (DFT calculations, QTAIM and NBO analyses) and the Research Resource Centre “Irkutsk Supercomputer Centre SB RAS” for the computational resources. E. A. R. thanks Dr C. L. Carpenter-Warren for the assistance with the XRD experiments at the University of St. Andrews, UK. Publisher Copyright: © 2022 The Royal Society of Chemistry.

PY - 2022/7/4

Y1 - 2022/7/4

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85136972312&partnerID=8YFLogxK

U2 - 10.1039/d2nj02345h

DO - 10.1039/d2nj02345h

M3 - Article

AN - SCOPUS:85136972312

VL - 46

SP - 14490

EP - 14501

JO - New Journal of Chemistry

JF - New Journal of Chemistry

SN - 1144-0546

IS - 30

ER -