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The role of halogen bonding (HaB) in the reactions of N-chlorosuccinimide (SimCl), a versatile reagent in organic synthesis, was investigated through experimental and computational analyses of its interactions with halides. The reactions of SimCl with Br− or I− resulted in the crystallization of HaB complexes of chloride with N-iodosuccinimide (SimI) or N-bromosuccinimide (SimBr). Computational analysis revealed that halogen rearrangements, which occurred even at −73 °C, were facilitated by halogen bonding. The dissociation of SimCl∙Y− (Y = I or Br) complexes into a Sim− + ClY pair (followed by the rotation and re-binding of the interhalogen molecules) bypassed the formation of the high-energy Sim− + Cl+ pair and drastically (about tenfold) reduced the dissociation energy of the N–Cl bond. Furthermore, while the dissociation energy of individual SimCl is higher (and its HaB is weaker) compared to that of SimI or SimBr, the dissociation of the N-Cl bond in SimCl∙Y− requires less energy than in the complexes of SimBr or SimI. The facile cleavage of such bonds in HaB complexes explains the high reactivity of SimCl and its effectiveness as a halogenating agent. 

The first structures containing bonds between chlorines and tertiary nitrogen atoms and very strong halogen bondsviachlorine (with a substantial contribution of orbital interactions) are reported. 

Introducing CF₃between two^tBu groups creates steric crowding that destabilizes the conformations of copper–pyrazolate tetramers. The impact of conformational behavior on luminescence is examined by low-temperature X-ray and photophysical studies. 

Anion–π complexes with the electron-deficient alkene, tetracyanoethylene, are similar to that with aromatic and p-benzoquinone π-acceptors, but their persistence is delimited by the 1e-donating strength and nucleophilicity of anions. 

Despite the formal presence of an acac-like moiety, β-oxo-meso-OH-porphyrins do not bind 3d and 4d metal ions at their periphery. This is attributed to the loss of macrocycle aromaticity upon expression of an acac-like chelate. 

Abstract The interaction of diiodine with quinuclidine (QN) and 4‐dimethylaminopyridine (DMAP) in solutions with 1 : 1 molar ratio of reactants at room temperature produced (in essentially quantitative yields) pure charge‐transfer QN⋅I₂adducts and iodine(I) salt [DMAP‐I‐DMAP]I₃, respectively. In comparison, the quantitative formation of pure iodine (I) salt [QN‐I‐QN]I₅was observed for the room‐temperature reactions of QN with a 50 % excess of I₂, and the charge‐transfer adducts of I₂with DMAP (and other pyridines) were formed when reactions were carried out at low temperatures. Computational analysis related the switch from the formation of charge‐transfer adducts to iodine(I) complexes in these systems to the strength of the halogen bonding of diiodine to the N‐donor bases. It shows that while the halogen‐bonded adducts represent critical intermediates in the formation of iodine(I) complexes, exceedingly strong halogen bonding between diiodine and the base prevents any subsequent transformations. In other words, while halogen bonding usually facilitates electron and halogen transfer, the halogen‐bonded complexes may serve as “black holes” hindering any follow‐up processes if this intermolecular interaction is too strong.