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DFT and IsoStar Analyses to Assess the Utility of σ‐ and π‐Hole Interactions for Crystal Engineering
Author(s) -
Mooibroek Tiddo Jonathan
Publication year - 2021
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.202000927
Subject(s) - chemistry , molecule , lone pair , hydrogen bond , crystallography , electrostatics , charge (physics) , crystal (programming language) , adduct , non covalent interactions , computational chemistry , atomic physics , physics , quantum mechanics , organic chemistry , computer science , programming language
The interpretation of 36 charge neutral ‘contact pairs’ from the IsoStar database was supported by DFT calculations of model molecules 1 – 12 , and bimolecular adducts thereof. The ‘central groups’ are σ‐hole donors (H 2 O and aromatic C−I), π‐hole donors (R−C(O)Me, R−NO 2 and R−C 6 F 5 ) and for comparison R−C 6 H 5 (R=any group or atom). The ‘contact groups’ are hydrogen bond donors X−H (X=N, O, S, or R 2 C, or R 3 C) and lone‐pair containing fragments (R 3 C−F, R−C≡N and R 2 C=O). Nearly all the IsoStar distributions follow expectations based on the electrostatic potential of the ‘central‐’ and ‘contact group’. Interaction energies (ΔE BSSE ) are dominated by electrostatics (particularly between two polarized molecules) or dispersion (especially in case of large contact area). Orbital interactions never dominate, but could be significant (∼30 %) and of the n /π→σ*/π* kind. The largest degree of directionality in the IsoStar plots was typically observed for adducts more stable than ΔE BSSE ≈−4 kcal⋅mol −1 , which can be seen as a benchmark‐value for the utility of an interaction in crystal engineering. This benchmark could be met with all the σ‐ and π‐hole donors studied.