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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. 

Abstract The studies of the anion‐π interactions advanced during the last two decades from the discussion of the mere existence of this counter‐intuitive bonding to its utilization for anion recognition and transport, catalysis, and other applications. Yet, there are substantial differences in the interpretation of nature and the driving forces of anion‐π bonding. Most surprisingly, there are still different opinions about the meaning of this term (i. e., which associations can be considered anion‐π complexes). After a brief overview of the studies in this area (including early examples of such complexes), we suggested that anion‐π bonding occurs when there is evidence of a net attraction between a (close‐shell) anion and the face of an electrophilic π‐system. This definition encompasses fundamentally similar supramolecular complexes comprising diverse π‐systems and anions and its general acceptance would facilitate a discussion of the nature and distinct driving forces of this fascinating interaction.