Interlocked Macrocyclic Ligands: A Kinetic Catenand Effect in Copper(I) Complexes

Article abstract of DOI:10.1021/ja00297a028

Copper(I) complexes of chelates and cyclic ligands containing 1,10-phenanthroline coordinating units have been prepared.Kinetic studies have been carried out in order to gain insight into the particular properties of the recently synthesized catenates.In the presence of the decomplexing agent CN^-, two dissociation mechanisms are involved: a bimolecular attack of CN^- on the copper(I) center and a monomolecular demetallation pathway.The rate law has been obtained and is in good agreement with the two dissociation pathways for each complex studied.The decomplexation rate depends strongly on both the topography and the topology of the molecules.For bis(2,9-diphenyl-1,10-phenanthroline)copper(I), Cu(dpp)2⁺, accessibility of the metal by CN^- is hindered as compared to less substituted complexes, making the bimolecular dissociation process much slower.Such an effect is due to the particular shape of the molecule, two dpp's, fitting in together while encaging the copper atom.A pronounced cyclic effect has also been demonstrated, even for mixed complexes containing only one ring surrounding the chelated metal.A marked catenand effect, of topological origin, has been found: when the ligand is composed of two interlocked rings, the unravelling of the two cycles (necessary to demetallation) renders the latter reaction several orders of magnitude slower than for the acyclic analogue of the catenate.