Observation of an anion⋯anion interaction in a square planar copper(II) Schiff base complex: DFT study and CSD analysis

A Conceptual DFT Study of Phosphonate Dimers: Dianions Supported by H-Bonds

“…They extended this study to the effect of the environment on the complexes, and they also analyzed oxoanion-based hydrogen-bonded complexes, rationalized the interaction in carboxylic acid dimers of anions and cations with different distances between the charged groups, and studied the cation–cation complexes formed by nucleic acids in Watson–Crick disposition . Other authors have extended the computational studies on complexes stabilized by hydrogen-bonding interactions. − In addition, other interactions such as halogen bonds have been used to maintain together the two interacting charged molecules. ,− …”

Halogen Bonding Between Anions: Association of Anion Radicals of Tetraiodo‐p‐benzoquinone with Iodide Anions

“…Yet, many examples of seemingly antielectrostatic intermolecular bonding between two anions or two cations were reported. [3][4][5][6][7] One type of such associations resulted from the "pancake" pbonding between radical anions or cations leading to the formation of dimeric complexes, for example, tetracyanoethylene (TCNE) 2 2À or tetrathiafulvalene (TTF) 2 2+ dimers. [3,4] Hydrogen-bonded (HB) dimers formed by two anionic species represent another type of such counter-intuitive interactions.…”

“…[5] The nature of bonding and the role of counter-ions and solvent in the formation of such dimers, and if they represent global or metastable local minima have been discussed in a number of publications. [3][4][5][6][7] It is noticeable, however, that among a variety of supramolecular interactions, the earlier works were focused mainly on multicenter (HB or pancake) bonding between identical cationic or anionic species. Hence, such bonding affected the structural features of the ionic substances, but it did not lead to co-crystallization of different anions or cations.…”