Ring-Opening Metathesis Polymerization of a Diolefinic [2]-Catenane–Copper(I) Complex: An Easy Route to Polycatenanes

A dilute (30 mM) dichloromethane solution of the copper(I) complex 1·Cu+ of a [2]-catenane composed of two identical 28-membered macrocyclic alkenes featuring a phenanthroline moiety in the backbone was subjected to ringopening metathesis polymerization (ROMP) with secondgeneration Grubbs catalyst. Shortly after mixing of reactants, the dark red solution transformed into a gel. The bis- (phenanthroline)copper(I) units were effectively preserved during ROMP, as evinced by spectroscopic analysis. This implies that the putative metal alkylidene pseudorotaxane intermediates did not undergo dethreading processes but were involved in ring−chain equilibria strongly biased toward the ring products at the low monomer concentration employed in the ROMP reactions. MALDI-TOF mass spectra of the reaction mixtures obtained at an early stage of the reaction revealed a distribution of interlocked oligomers (1·Cu+)n(PF6−)n−1 with n up to 7, with no traces of peaks ascribable to open chain species.