Mole-Ratio-Dependent Reversible Transformation between 2:2 and Cyclic 3:6 Silver(I) Complexes with an Argentivorous Molecule

A tetra-armed cyclen (L) with two substituted 3,5-difluorobenzyl and two substituted pyridine-4-yl methyl groups at the 1,4- and 7,10-positions of the cyclen ring as side arms was synthesized. When L was reacted with 1 equiv of the silver(I), dimetallo[3.3]paracyclophane-like 2:2 cyclic dimer, [Ag2(L)2](PF6)2, was obtained. The reaction of L with 2 equiv of silver(I) gave a 3:6 cyclic trimer, [Ag6(L)3(CH3CN)3](OTf)6·3CH3CN. Furthermore, reversible complexation between the 2:2 cyclic dimer and 3:6 cyclic trimer was confirmed by 1H NMR and the CSI mass in the addition of silver(I) or the [2.2.2]cryptand.