Synthesis of a rotaxane Cu^I triazolide under aqueous conditions

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