Crystal supramolecularity: extended aryl embraces in dimorphs of [Cu(1,10-phen)2I]I3

Abstract

The crystal structures of monoclinic and triclinic dimorphs of [Cu(phen)₂I]⁺ I₃^- are reported, and the crystal packing of each is analysed. Local interactions between [Cu(phen)₂I]⁺ cations are parallel fourfold aryl embraces (P4AE) of the phen ligands, supplemented by offset face-to-face interactions, to form layers of embracing cations. The tri-iodide ions are associated with the faces and the peripheries of the phen ligands, and recurring motifs are identified. Calculations of the intermolecular energies for the [Cu(phen)₂I]⁺...[Cu(phen)₂I]⁺ motifs and the [Cu(phen)₂I]⁺...I₃^- motifs and the negligible I₃^-...I₃^- interactions are presented. While the energy contributions for the two structures have significant differences, the totals are very similar, consistent with the dimorphism. There are significant differences in molecular coordination stereochemistry for [Cu(phen)₂I]⁺ in the two structures, and we conclude that this difference is a consequence of the alternative crystal packings.