Crystal structures of 2,4,6-triiodobenzonitrile and 2,4,6-triiodophenyl isocyanide

Abstract

The title crystals, C 7 H 2 I 3 N, are isomorphous. Both molecules lie across two crystallographic mirror planes and a twofold axis. The principal supramolecular interaction is centric R 2 2 (10) CN/NCÁ Á ÁI short contacts involving both ortho I atoms, with two contacts bisecting each cyano and isocyano group. These form ribbons along [010] and give rise to a planar sheet structure parallel to (100). All pairs of adjacent sheets have centric stacking, a mode not previously reported for sheets of this type. This study completes the series of homo-2,4,6-trihalobenzonitriles, in which I atoms give the strongest CNÁ Á ÁX and NCÁ Á ÁX interactions (X = F, Cl, Br, I).

Crystal structure of 2,3,5,6-tetrabromoterephthalonitrile

“…C NÁ Á ÁBr contacts are the most prominent packing feature ( Table 1). The length of these contacts is similar to 3.064 (4) Å , the mean C NÁ Á ÁBr distance found in crystals of 2,4,6-tribromobenzonitrile (Br3BN; Noland et al, 2018). The N and ortho-Br atoms of Br3BN form a contact network similar to a half-molecule of Br4TN.…”

“…The question is whether these contacts will form for a given nitrile, and whether they are isolated or extended to create ribbon or sheet structures in their crystals. The prevailing trend is that C NÁ Á ÁF contacts do not form (Bond et al, 2001), C NÁ Á ÁCl contacts form in isolation or as inversion dimers (Pink et al, 2000), and C NÁ Á ÁBr and Á Á ÁI contacts form networks (Noland et al, 2018). Contact strength tends to increase with the polarizability of the halogen atom (Desiraju & Harlow, 1989).…”

Chameleonic metal-bound isocyanides: a π-donating CuI-center imparts nucleophilicity to the isocyanide carbon toward halogen bonding

“…Commonly used HaB acceptors include electronegative heteroatoms bearing lone pair(s) (LP(s)) 34 or positively charged d 8 metal centers exhibiting d z 2-nucleophilicity (see our recent review 35 ). Owing to the lower electronegativity of C compared to N, O, halogens, or other heteroatoms, the solid-state interaction involving the carbon lone pair is rather an exception and it is only represented by HaB between a halogen σ-hole and the isocyanide C center, [36][37][38][39][40] namely σ-(X)-hole⋯:CuNR interactions.…”

Bi- and Trifurcated Halogen Bonding M–C≡N···I in 1D, 2D, and 3D Supramolecular Network Structures of Co-Crystallized Diiodoacetylene C2I2 and Tetracyanonickelate [Ni(CN)4]2–

“…The structural motif of one nitrogen atom with contacts to two iodine atoms is not exceedingly rare . Typical examples are nitrogen-containing heterocycles or organic nitriles − acting as halogen bond acceptors. In contrast, related structures with metal-cyanide complexes as halogen-bond acceptors are scarce. ,, There exist three structures of cyanometalates where bifurcated nitrogen atoms form halogen bonds to two iodine atoms. ,, The corresponding N···I distances are in the range of 2.952–3.284 Å, while CN···I angles differ between 106.59° and 162.06°, which is comparable to the values obtained in this study.…”