Azine Steric Hindrances Switch Halogen Bonding to N‐Arylation upon Interplay with σ‐Hole Donating Haloarenenitriles. Issue 11 (29th April 2021)

• Record Type: Journal Article
• Authors: Baykov, Sergey V.; Geyl, Kirill K.; Ivanov, Daniil M.; Gomila, Rosa M.; Frontera, Antonio; Kukushkin, Vadim Y.
• Is Part Of: Chemistry, an Asian journal. Volume 16:Issue 11(2021)
• Page Start: 1445
• Page End: 1455
• Publication Date: 2021-04-29
• Subjects: noncovalent interactions -- halogen bonding -- self-assembly -- nitriles -- azines; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/asia.202100282
• Languages: English
• ISSNs: 1861-4728

Abstract

Abstract: An interplay between 4‐bromo‐ and 4‐iodo‐5‐nitrophthalonitriles (XNPN, X=Br or I) and any one of the azines (pyridine 1, 4‐dimethylaminopyridine 2, isoquinoline 3, 4‐cyanopyridine 4, 2‐methylpyridine 5, 2‐aminopyridine 6, quinoline 7, 1‐methylisoquinoline 8, and 2, 2'‐bipyridine 9 ) proceeds differently depending on steric and electronic effects of the heterocycles. Sterically unhindered azines 1–3 underwent N ‐arylation to give the corresponding azinium salts (characterized by 1 H and 13 C{H} NMR and high‐resolution ESI‐MS). In contrast, azines 4 –9 with sterically hindered N atoms or bearing an electron‐withdrawing substituent, form stable co‐crystals with XNPN, where two interacting molecules are bound by halogen bonding. In all obtained co‐crystals, X⋅⋅⋅N structure‐directed halogen bonds were recognized and theoretically evaluated including DFT calculations (PBE0‐D3/def2‐TZVP level of theory), QTAIM analysis, molecular electrostatic potential surfaces, and noncovalent interaction plot index. Estimated energies of halogen bonding vary from −7.6 kcal/mol (for 6 ⋅ INPN) to −11.4 kcal/mol (5 ⋅ INPN). Abstract : Azines interplay with haloarenenitriles XNPNs (X=Br, I) by two routes: sterically unhindered heterocycles reacted with XNPN to give N ‐arylated azinium salts, while azines featuring sterically hindered N atoms or with an EWG substituent formed halogen‐bonded co‐crystals.