First molecular self-assembly of 1,4-diiodo-tetrafluoro-benzene and a ketone via (O⋯I) non-covalent halogen bonds

Halogen Bonding in Organic Synthesis and Organocatalysis

“…However, several previous studies clearly indicated that halogen bonding to neutral Lewis bases is feasible. Most relevant in the context of this Concept is a crystal structure analysis published by Schöllhorn and co‐workers featuring the adduct of two monodentate halogen‐bond donors to an electron‐rich ketone (Figure ) …”

Interplay between non-covalent interactions in complexes and crystals with halogen bonds

“…Studies on the halogen bonds formed by iodine atoms in complexes with N-heterocycles with sterically hindered basic centres (nitrogen atoms) as well as bifurcated bonds with multiple nonvalent interactions of iodine atom N_I_N were reported. 175,176 Weakening of the mutual influence of two adjacent donor centres, which manifests itself in weakening of halogen bonds provided that the both donor centres are simultaneously involved in the bonding, was emphasized.…”

“…In the crystalline state, namely, in the complex 1,4-diiodotetrafluorobenzene ± 1,10-phenanthroline, the N(1)_I and N(10)_I distances also significantly differ from each other. 175,176 According to B97D/TZVP calculations of the complexes of 1,4-diiodotetrafluorobenzene with 1,10-phenanthroline-5,6-dione and 4,4 H ,6,6 H -tetramethyl-2,2 H -bipyrimidine with the TZVPP basis set for the iodine atom, these systems are good candidates for the formation of bifurcated halogen bonds, 177 viz., complexes with symmetric and asymmetric bifurcated halogen bonds N_I_N H were detected. In the asymmetric complexes of, e.g., 4,5-diazafluoren-9-one with iodine, one N_I bond is 0.17 # A longer than the sum of the van der Waals radii of the N and I atoms (3.61 # A).…”

The Halogen Bond

“… 170 , 171 The same geometrical features are observed for other nitrogen heteroaromatics such as pyrazine or quinoline. 172 − 174 When carbonyl groups act as XB acceptors, the oxygen may function as both a monodentate 175 and a bidentate 176 site, and the XB donor(s) are pinned in a trigonal planar geometry. Sulfonyl 177 , 178 and phosphoryl 179 groups behave similarly to carbonyl moieties, and also imines 180 form XBs along the respective n-pair axis.…”