Insights About the Mechanism of the Formation of Supramolecular π-Stacked Rectangles Based on CuI Bimetallic Complexes Bearing a Bridging Phosphane Ligand



The variation in the ratio of the reactants in the supramolecular self-assembly reaction of the bimetallic CuI “U-shaped” molecular clip 1 with the 1,4-dicyanobenzene 3 and the 1,8-anthracene-9,10-carbonitrile 4 “short” ditopic ligand have allowed the observation of new “open” supramolecular assemblies 7 and 8, respectively, in addition to the previously characterized π-stacked supramolecular rectangles 5 and 6, respectively. These new derivatives have been characterized by their solid-state structure obtained by X-ray diffraction on single crystals and by NMR spectroscopy in the case of derivative 7. Depending on the extent of the π system included in the core of the homoditopic linker, different behaviors are observed. In the case of derivative 7 based on the “phenyl” linker 3, a 1:1 1/3 ratio affords the open derivative in a good yield, whereas a 1:0.5 1/4 ratio allows the isolation of derivative 8 in very low yield. These results allow for a tentative analysis of the mechanism that occurs along with the supramolecular self-assembly processes to afford π-stacked supramolecular rectangles.