Noncovalent Interactions in Succinic and Maleic Anhydride Derivatives

Abstract

Herein, we present a study of the short contacts that several heterocycles of the same family, namely, succinic and maleic anhydrides, maleimide, and succinimide establish in their condensed phases. DFT calculations on model systems in the gas phase have allowed us to calibrate the strength of such interactions, obtaining associated energies up to 2 kcal/mol. We have performed MEP and EDA analysis to unveil their nature, which is mainly electrostatic with some London dispersion contribution. Furthermore, the origin of the interaction is the existence of a charge depletion region (a π-hole) in the inner part of the rings. This hole interacts with a Lewis base in a precise topological way, with the contacts showing a high directionality as revealed by the analysis of hundreds of crystal structures. We believe that the description for the first time of these interactions, along with their abundance, can assist their use as a tool in crystal design.

Methyl groups as widespread Lewis bases in noncovalent interactions

“…Orbital interactions, on the other hand, are based on charge transfer processes from an occupied orbital (e.g., but not necessarily, a lone pair) into an empty antibonding orbital. Usually, noncovalent interactions are the combination of the two effects along with dispersion forces 6 – 8 .…”

Supramolecular Packing of a Series ofN-Phenylamides and the Role of NH···O═C Interactions

“…7,8 Similarly, the molecular reactivity can be obtained by measuring the molecular electrostatic potential (MEP) based on regions of positive and negative potentials. 9…”

Iodide···π Interactions of Perhalogenated Quinoid Rings in Co-crystals with Organic Bases

“…8 A close contact with an anion or a lone electron pair is possible for electron-depleted rings and a number of such interactions have been documented. [9][10][11][12][13][14][15][16] Unlike aromatics, which are mostly electron-rich (except those with five or six electronwithdrawing substituents), quinoid rings are inherently electron-poor due to a lack of electron delocalization and the presence of carbonyl groups; they can be further depleted by introduction of electronegative substituents. Perhalogenoquinones act as mild oxidants and can easily be reduced into semiquinone radicals by mild reducing agents such as iodide ions.…”