Syntheses and structures of a novel trinaphthylene hexaimino cryptand: Three different conformations of a macrobicyclic ligand

A synthesis in good yield of a new hexaimino cryptand containing two tris(2-aminoethyl)amine moieties bridged by three naphthylene groups is reported. Ag⁺ and Cu⁺ cryptates of the ligand have also been prepared and characterized. The cryptand and cryptates have been structurally analyzed by X-ray diffraction, unveiling three different conformations. The macrobicyclic ligand has an anti conformation in the cryptand, but has a sym form in each cryptate. Although the Ag⁺ cryptates have a symmetric structure on the three arms, one of the three arms in the Cu⁺ complex shows remarkable bending. The bent conformation is intrinsic of the Cu⁺ complex, as indicated by X-ray analyses and MM2 calculations. The temperature dependence of the ¹H NMR spectra has also been investigated, revealing fluxional behaviors of the ligand in each compound.