Metal-Ion-Induced Mechanical Chirality: Achiral Rotaxane as the Only Ligand in Chiral Palladium(II)-N-Heterocyclic Carbene Complexes

Abstract

We report the insertion of Pd(II) into an originally achiral rotaxane producing two chiral metallorotaxanes: one is planar-chiral, with its two interlocked components both chelating nonequivalently to the metal center; the other is C₂-symmetrical-chiral, with the dynamically exchangeable stereogenic units stabilized by the interlocked structure. Chiral additives confirmed the existence of chirality, with the enantiomers of the C₂-symmetrical N-heterocyclic carbene complex being resolved using chiral TRISPHAT counteranions.