Stacking Interactions: A Supramolecular Approach to Upgrade Weak Halogen Bond Donors

The co‐crystallization of tetracyanobenzene (TCB) with haloarenes ArX provided six new co‐crystals TCB ⋅ ArX (ArX=PhCl, PhBr, 4‐MeC6H4Cl, 4‐MeC6H4Br, 4‐MeOC6H4Cl, 1,2‐Br2C6H4) which were studied by X‐ray diffraction. In these systems, the strong collective effect of π⋅⋅⋅π stacking interactions and l...

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Published in:Chemistry : a European journal 2022-12, Vol.28 (70), p.e202201869-n/a
Main Authors: Baykov, Sergey V., Ivanov, Daniil M., Kasatkina, Svetlana O., Galmés, Bartomeu, Frontera, Antonio, Resnati, Giuseppe, Kukushkin, Vadim Y.
Format: Article
Language:English
Subjects:
Bonding strength
Chemistry
crystal engineering
Crystallization
Crystals
DFT calculations
Electrostatic properties
halogen bonding
Mathematical analysis
noncovalent interactions
Stacking
staking
Trimers
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Summary:The co‐crystallization of tetracyanobenzene (TCB) with haloarenes ArX provided six new co‐crystals TCB ⋅ ArX (ArX=PhCl, PhBr, 4‐MeC6H4Cl, 4‐MeC6H4Br, 4‐MeOC6H4Cl, 1,2‐Br2C6H4) which were studied by X‐ray diffraction. In these systems, the strong collective effect of π⋅⋅⋅π stacking interactions and lone pair‐(X)⋅⋅⋅π‐hole‐(C) bondings between TCB and ArX promote the strength of X⋅⋅⋅Ncyano halogen bonding (HaB). Theoretical studies showed that the stacking interactions affect the σ‐hole depth of the haloarenes, thus significantly boosting their ability to function as HaB donors. According to the molecular electrostatic potential calculations, the σ‐ hole‐(Cl) value (1.5 kcal/mol) in the haloarene 4‐MeOC6H4Cl (featuring an electron‐rich arene moiety and exhibiting very poor σ‐hole‐(Cl) ability) increases significantly in the stacked trimer (TCB)2 ⋅ 4‐MeOC6H4Cl (12.5 kcal/mol). Theoretical DFT calculations demonstrate the dramatic increase of X⋅⋅⋅Ncyano HaB strength for stacked trimers in comparison with parent unstacked haloarenes. π‐Stacking interactions turn on halogen σ‐hole in unactivated chloro‐ and bromo‐arenes which are thus enabled to function as good halogen bonding donors.
ISSN:0947-6539
1521-3765
1521-3765
DOI:10.1002/chem.202201869