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1. The interplay between hydrogen and halogen bonding: substituent effects and their role in the hydrogen bond enhanced halogen bond

   https://doi.org/10.1039/d3sc02348f  

   Sun, Jiyu; Decato, Daniel A.; Bryantsev, Vyacheslav S.; John, Eric A.; Berryman, Orion B. (August 2023, Chemical Science)

   The hydrogen bond enhanced halogen bond can be modulated by changing substituents on the HB or XB donor ring. Thus, distant substituents can impact nearby noncovalent interactions and this can be used as a viable approach for molecular design. 

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2. Organocatalysis by a multidentate halogen-bond donor: an alternative to hydrogen-bond based catalysis

   https://doi.org/10.1039/c9nj01404g  

   Perera, Manomi D.; Aakeröy, Christer B. (May 2019, New Journal of Chemistry)

   null (Ed.)

   A charge neutral iodoethynyl-based multidentate halogen-bond donor was synthesized and successfully utilized as an organocatalyst in a benchmark Ritter-type solvolysis reaction. The catalytic activity was monitored using 1 H NMR spectroscopy and several control experiments were systematically carried out in order to rule out hidden catalysis based on other functional groups. 

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3. A comparison of structure, bonding and non-covalent interactions of aryl halide and diarylhalonium halogen-bond donors

   https://doi.org/10.3762/bjoc.20.125  

   Javaly, Nicole; McCormick, Theresa M; Stuart, David R (January 2024, Beilstein Journal of Organic Chemistry)

   Halogen bonding permeates many areas of chemistry. A wide range of halogen-bond donors including neutral, cationic, monovalent, and hypervalent have been developed and studied. In this work we used density functional theory (DFT), natural bond orbital (NBO) theory, and quantum theory of atoms in molecules (QTAIM) to analyze aryl halogen-bond donors that are neutral, cationic, monovalent and hypervalent and in each series we include the halogens Cl, Br, I, and At. Within this diverse set of halogen-bond donors, we have found trends that relate halogen bond length with the van der Waals radii of the halogen and the non-covalent or partial covalency of the halogen bond. We have also developed a model to calculate ΔGof halogen-bond formation by the linear combination of the % p-orbital character on the halogen and energy of the σ-hole on the halogen-bond donor. 

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4. Influence of Substituents in the Benzene Ring on the Halogen Bond of Iodobenzene with Ammonia

   https://doi.org/10.1002/cphc.202200011  

   Scheiner, Steve; Hunter, Sarah (February 2022, ChemPhysChem)

   Abstract The effects on the C−I⋅⋅N halogen bond between iodobenzene and NH₃of placing various substituents on the phenyl ring are monitored by quantum calculations. Substituents R=N(CH₃)₂, NH₂, CH₃, OCH₃, COCH₃, Cl, F, COH, CN, and NO₂were each placed ortho, meta, and para to the I. The depth of the σ‐hole on I is deepened as R becomes more electron‐withdrawing which is reflected in a strengthening of the halogen bond, which varied between 3.3 and 5.5 kcal mol⁻¹. In most cases, the ortho placement yields the largest perturbation, followed by meta and then para, but this trend is not universal. Parallel to these substituent effects is a progressive lengthening of the covalent C−I bond. Formation of the halogen bond reduces the NMR chemical shielding of all three nuclei directly involved in the C−I⋅⋅N interaction. The deshielding of the electron donor N is most closely correlated with the strength of the bond, as is the coupling constant between I and N, so both have potential use as spectroscopic measures of halogen bond strength. 

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5. Spectroscopic Measurement of a Halogen Bond Energy

   https://doi.org/10.1002/anie.201906279  

   Zhang, Xinxing; Liu, Gaoxiang; Ciborowski, Sandra; Wang, Wei; Gong, Chu; Yao, Yifan; Bowen, Kit (July 2019, Angewandte Chemie International Edition)

   Abstract Halogen bonding (XB) has emerged as an important bonding motif in supramolecules and biological systems. Although regarded as a strong noncovalent interaction, benchmark measurements of the halogen bond energy are scarce. Here, a combined anion photoelectron spectroscopy and density functional theory (DFT) study of XB in solvated Br⁻anions is reported. The XB strength between the positively‐charged σ‐hole on the Br atom of the bromotrichloromethane (CCl₃Br) molecule and the Br⁻anion was found to be 0.63 eV (14.5 kcal mol⁻¹). In the neutral complexes, Br(CCl₃Br)_1,2, the attraction between the free Br atom and the negatively charged equatorial belt on the Br atom of CCl₃Br, which is a second type of halogen bonding, was estimated to have interaction strengths of 0.15 eV (3.5 kcal mol⁻¹) and 0.12 eV (2.8 kcal mol⁻¹). 

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