Interplay of hydrogen bonds, iodo...nitro interactions and aromatic π...π stacking interactions in iodo-nitroanilines

Abstract

Molecules of 2-iodo-5-nitroaniline (I) are linked by N-H...O hydrogen bonds into centrosymmetric dimers and by asymmetric three-centre iodo...nitro interactions into chains, so forming chains of fused centrosymmetric rings: these chains are linked by aromatic pi...pi stacking interactions to form a three-dimensional structure. In the isomeric 4-iodo-2-nitroaniline (II), each of the two independent molecules forms hydrogen-bonded chains that are linked by two-centre iodo...nitro interactions into sheets of two types, each containing only a single type of molecule: pi...pi stacking interactions are absent. In 2,4-diiodo-3-nitroaniline (III), where the nitro group is almost orthogonal to the aryl ring, a combination of N-H...O hydrogen bonds and two distinct two-centre iodo...nitro interactions links the molecules into a three-dimensional framework that is reinforced by aromatic pi...pi stacking interactions. Bond lengths and conformations are discussed and comparisons are drawn with related compounds.

Second sphere coordination in fluoroanion binding: Synthesis, spectroscopic and X-ray structural study of [Co(phen)2CO3](Pfbz)·6H2O

“…Other than the above mentioned heteroatom interactions, intermolecular interactions involving heavier halogens (Cl, Br, I) have also become an effective tool in preorganising molecules in the crystalline state [23][24][25][26][27][28][29][30][31]. The role of lightest of the halogens, namely fluorine, in engineering molecules is still debatable as it has been argued that organic fluorine does not accept interactions involving hydrogen atom [32][33][34][35][36][37].…”

The Aryl Bromine−Halide Ion Synthon and Its Role in the Control of the Crystal Structures of Tetrahalocuprate(II) Ions

“…Such competitive interactions provide diversity in the observed structures as well as uncertainty in the structure predictions. Thus, for example, Garden et al 3 have examined the competitive effects of hydrogen bonding, iodo-nitro interactions, and aromatic π-π stacking in iodo-nitroanilines. One of the challenges of crystal engineering today is the clarification of the relative roles of the various synthons in supramolecular structures.…”