A flexible dibenzo-O4S2-macrocycle: twist-and-squeeze type metal binding via synergic action of metal–ligand and metal–π interactions

A 21-membered O4S2-donor-macrocycle (L) incorporating a dibenzo-subunit was synthesized. From the reaction of L with AgPF6, an endo-type 1:1 complex [AgL]PF6 (1) was obtained. On complexation, the conformation of L changes dramatically due to metal–ligand coordination as well as π-interactions between the metal and the dibenzo-subunit from L. This unique change in configuration showing a twist-and-squeeze type process illustrates how large flexible ligands stabilize complexes through conformational changes.