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.