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

Abstract

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...

A new look at the chalcogen bond: π-hole-based chalcogen (Se, Te) bonding which does not include a σ-hole interaction

“…The overall electron-deficiency of ChDA (see section 2 for relevant theoretical calculations) is additionally provided by two powerful nitrile EWGs. 31 According to extensive experimental and theoretical studies, [23][24][25] various functionalized or unfunctionalized 1,2,5chalcogenadiazoles, exhibiting two deep 90°-directed σ-Chhole(s) on the chalcogen and lone pairs on the N atoms (acting as ChB-acceptors), are capable of self-association via the 2-center Ch⋯N or 4-center head-to-tail [Ch⋯N] 2 pairing to give dimers, 26,32 [Ch⋯N] 2n polymers, 15 or more complex supramolecular assemblies such as ribbons, 26 chains, 27 and even supramolecular capsules. 28 Self-association of some modified chalcogenodiazoles can even form porous supramolecular organic frameworks as a result of the association of monomers.…”

Adjusting the balance between hydrogen and chalcogen bonds

“…Molecules related to benzochalcogenadiazoles were recently examined in the context of their chalcogen bonding to halides. 66 Given the charge-assist gained from the anion, the binding energies were fairly large, between 28 and 86 kcal mol −1 . This charge-assistance was echoed by another work 95 for a variety of different anions, and demonstrated the importance of classical electrostatics to this bonding.…”

“…65 The interaction of this unit with several anions was investigated quite recently. 66 These species have found application in solid-state assembly 65 by virtue of the two σ-holes on each Ch atom. The (ChN) 2 square bonding motif of chalcogenadiazole dimers that contains a pair of ChBs was the subject of recent quantum chemical analyses and the various geometric dispositions in which two related molecules can pair up was probed as well.…”

Halide Complexes of 5,6‐Dicyano‐2,1,3‐Benzoselenadiazole with 1 : 4 Stoichiometry: Cooperativity between Chalcogen and Hydrogen Bonding

“…Amongst recently recognized anion receptors, chromogenic/fluorogenic 1,2,5‐chalcogenadiazoles (chalcogen=S, Se, and Te) and their fused derivatives should be highlighted. Their ChB ‐bonded complexes with anions (mostly halides), as well as with neutral Lewis bases, are characterized by XRD, UV‐Vis, NMR, and quantum chemical calculations; in some cases, double ChB is observed to be based on simultaneous participation of two σ‐holes at the same chalcogen atom [51,72–92] . The capacity of chalcogenadiazoles for the formation of ChB increases with the atomic number/polarizability [68] of the chalcogen.…”

“…The capacity of chalcogenadiazoles for the formation of ChB increases with the atomic number/polarizability [68] of the chalcogen. The common structural peculiarity of the complexes is that the ChB is longer than the sum of the covalent radii of the involved atoms but shorter than the sum of their van der Waals (VdW) radii, which directly indicates an orbital contribution [72–81] . In the form of crown ether‐annulated derivatives, [88,93] chalcogenadiazoles have potential for cooperative ion‐pair recognition.…”