Azine Steric Hindrances Switch Halogen Bonding to N‐Arylation upon Interplay with σ‐Hole Donating Haloarenenitriles

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, 4cyanopyridine 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 cocrystals, 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 À 7.6 kcal/mol (for 6 • INPN) to À 11.4 kcal/mol (5 • INPN).

Metal-Involving Halogen Bonding Including Gold(I) as a Nucleophilic Partner. The Case of Isomorphic Dichloroaurate(I)·Halomethane Cocrystals

“…To the best of our knowledge, this is the first example of the triple exchange of the halomethanes, although the double CHBr 3 /CHCl 3 isostructural isomorphic exchange accompanied by XBs , and not accompanied by XBs and the CHCl 3 /CH 2 Cl 2 isomorphism without XBs have been reported. Previously, we demonstrated the importance of various isostructural exchanges for crystal engineering. ,− Owing to the triple isomorphism in 1 ·CHBr 3 , 1 ·CHCl 3 , and 1 ·CH 2 Cl 2 , the differences in noncovalent interactions in the studied systems are mostly due to the identity of halomethanes.…”

Supramolecular Aggregation of Lead(Ii) Perchlorate and a Thiosemicarbazide Derivative Linked by a Myriad of Non-Covalent Interactions

“…For the S••• N,O contacts, a different equation proposed in the literature was used [47,48] (E dis = -0.556 × V r ). This equation has been successfully used before in a variety of halogen bonding interactions [49][50][51][52][53][54][55][56]. The obtained results show that the hydrogen bonds involving the acetonitrile are slightly stronger (1.09 kcal/mol and 0.72 kcal/mol) than those involving the aromatic ring (0.63 kcal/mol and 0.53 kcal/mol) (Table 3).…”

On the Importance of Halogen Bonding Interactions in Two X-ray Structures Containing All Four (F, Cl, Br, I) Halogen Atoms

“…We used the equation E = 0.556*V r to estimate the association energy of each HaB. This equation has been successfully used before in a variety of halogen bonding interactions [41][42][43][44][45][46][47][48][49]. As a result, the association energy of HaB "a" is −1.67 kcal/mol, HaB "b" is −0.78, and HaB "c" is −0.88 kcal/mol.…”