A ligand strand that displays anion-dependant reactivity with acetonitrile: formation of either a mononuclear complex or head-to-tail circular helicate

The ligand L2,2 contains two bidentate domains separated by a 3,3-diamino-2,2′-biphenyl spacer unit and with Cu(ClO4)2 a mononuclear species is formed (e.g. [Cu(L2,2)]2+). Upon coordination with Cu(triflate)2 the ligand undergoes reaction with an acetonitrile solvent, producing a different ligand with unsymmetrical bidentate and tridentate domains (L2,3). This new ligand results in the formation of a tetranuclear head-to-tail circular helicate [Cu4(L2,3)4]8+ showing that in the presence of the triflate anion the ligand denticity is changed.