Templating and Clipping Coordination Reactions Leading to Heteronuclear Trimetallic Complexes Containing Interlocking Rings

Publisher Website
Google Scholar
Abstract
We report the preparation of heterotrimetallic complexes with a Cu-complexed [2]-catenate structure, containing two other metals within the rings. Starting from a multidentate ligand 1 containing two terpy units (terpy 2,2‘:6‘,2‘‘-terpyridine) and one dpp fragment (dpp 2,9-diphenyl-1,10-phenanthroline), a 29-membered macrocycle 2 was prepared in 59% yield by clipping of both terpy moieties of 1 with Ru(DMSO)4Cl2 under high-dilution conditions. Threading of an additional equivalent of ligand 1 through macrocycle 2 was achieved by reaction with Cu(I), which acts as a template, forming a Cu(dpp)2+-type complex bearing two free terpy ligands. Reaction of this complex with different salts of Cu(II), Co(II), Fe(II), and Zn(II) gave the corresponding heteronuclear trimetallic catenates, as mixtures of diastereomers, again by clipping of both terpy units with the metal. The kinetic stability of the Ru complex prevents ligand scrambling. A somewhat different strategy, i.e., simultaneous formation of two rings from Cu(1)2+ by reaction with Ru(DMSO)4Cl2, afforded a catenate containing two Ru(terpy)2+ complexes within the rings. The high stability of these Ru species allows the selective demetalation of Cu(I) to give a catenane containing a free tetrahedral coordination site.