Contribution to cation–π interaction of the univalent silver cation with racemic [7]helicene in the solid state

Yellow crystals of the complex [7]helicene–silver perchlorate (i.e., C30H18–AgClO4 or more accurately [Ag(η4-C30H18)]ClO4, respectively), crystallizing in the monoclinic system with the centrosymmetric P21/c space group, where a = 14.4230(3) Å, b = 10.2804(3) Å, c = 15.2541(4) Å, and β = 91.856(2)°, were prepared by slow evaporation of the solvent from a solution obtained by mixing equimolecular amounts of racemic [7]helicene and silver perchlorate in toluene at ambient temperature. Characteristic feature of the complex packing in the solid state is the formation of infinite antiparallel layers of dimeric structures of the proven complex. The investigated [7]helicene ligand in the racemic form functions as a molecular tweezer for the univalent silver cation.