Intramolecular Halogen Bonding Supported by an Aryldiyne Linker

Abstract

Intramolecular halogen bonds between aryl halide donors and suitable acceptors, such as carbonyl or quinolinyl groups, held in proximity by 1,2-aryldiyne linkers, provide triangular structures in the solid state. Aryldiyne linkers provide a nearly ideal template for intramolecular halogen bonding as minor deviations from alkyne linearity can accommodate a variety of halogen bonding interactions, including O···Cl, O···Br, O···I, N···Br, and N···I. Halogen bond lengths for these units, observed by single crystal X-ray crystallography, range from 2.75 to 2.97 Å. Internal bond angles of the semirigid bridge between halogen bond donor and acceptor are responsive to changes in the identity of the halogen, the identity of the acceptor, and the electronic environment around the halogen, with the triangles retaining almost perfect co-planarity in even the most strained systems. Consistency between experimental results and structures predicted by M06-2X/6-31G* calculations demonstrates the efficacy of this computational method for modeling halogen-bonded structures of this type.

Halogen‐Bonded Assemblies of Arylene Imides and Diimides: Insight from Electronic, Structural, and Computational Studies

“…[14] Bowling and co-workers reported the stabilization of at riangular systemt hrough halogen-bonding interactions, whereby the rigidityo ft he halogen-bondedb ridge dependso nt he nature of donorh alogen atomsa nd acceptorc arbonyl groups. [15] There-fore, the strength of halogen bonds can be fine-tuned by varying the motif covalently bound to the halogen atom.…”

Intramolecular Halogen Bonding in Solution: 15N, 13C, and 19F NMR Studies of Temperature and Solvent Effects

“…The absence of any solvent effects on the chemical shift differences of the control pairs 2, 4, and 5 (see the Supporting Information) further supports the assertion that the differences observed for the 1 and 3 pairs are due to intramolecular halogen bonding. [14,20] Acetone is the only solvent in the study that can provide a Lewis basic lone pair. However, the differences in 1A and 1B are small enough in acetone and dichloromethane to call into question the formation of an intramolecular brominecentered halogen bond for these systems in such polar solvents.…”

“…[27] The method and basis set were chosen on the basis of previous work. [14] All structures were verified to be local minima through vibrational frequency analysis.…”

“…[10f] Similarly, the crystal structures of aryldiynes with carbonyl or quinoline acceptors have demonstrated that the conjugated linker brings the halogen bond donors and acceptors into the appropriate positions and is flexible enough to allow halogen-bonding interactions ( Figure 1). [14] Figure 1. Aryldiynes used in prior studies to explore symmetric halogen bonding in solution and asymmetric halogen bonding in the solid state.…”

“Conformational lock” via unusual intramolecular C–F⋯OC and C–H⋯Cl–C parallel dipoles observed in in situ cryocrystallized liquids

“…9 Furthermore, an intramolecular SÁ Á ÁO interaction, reported previously determines the stereoselectivity in an asymmetric Pummerer reaction. 10 The existence of halogen bonding involving the heavier halogen atoms Cl/Br/IÁ Á ÁN/O (intramolecular) 11 is well known in the literature. To date, however, there is no experimental evidence in favor of the existence of a possible short C-FÁ Á ÁOQC contact.…”