Synthesis of a Rotaxane Cu^I Triazolide under Aqueous Conditions

We describe the serendipitous isolation of a stable, neutral, monomeric mechanically interlocked CuI triazolide under aqueous conditions. This “trapped” intermediate of the CuAAC catalytic cycle is sterically protected from reprotonation by the rotaxane architecture, which renders the CuI–C bond stable toward moisture and aireven carboxylic acids protonate the CuI–C bond only slowly. The isolation of this remarkably stable CuI organometallic points toward potential applications of mechanical bonding in the study of reactive intermediates.