Azobenzene‐Linked Photoswitchable Mesoionic Carbene‐Complexes: Synthesis, Isomerization, and Catalysis

Mesoionic carbenes (MICs) have emerged as an excellent chemical species owing to their unique nature and stronger donating properties. In this work, the syntheses of several azobenzene‐functionalized MIC complexes are reported. The azobenzene‐bearing MIC salts (AzMIC salts) were prepared and utilized to synthesize coinage metal complexes, [(AzMIC)CuCl] and [(AzMIC)AuCl]. These newly developed systems varied in the number and/or position of azobenzene unit(s) over the triazolium ring. The photoisomerization characteristics of the AzMIC derivatives were thoroughly examined using UV–visible and ¹ H NMR spectroscopy. These complexes underwent reversible isomerization upon irradiation with light of suitable wavelengths in varied solvent systems. The effect of the substitution pattern of azobenzene unit(s) on the catalytic performance of the corresponding copper and gold organometallic complexes was systematically evaluated. To demonstrate the catalytic efficiency of Cu(I) and Au(I) complexes, the CuAAC reaction and cyclization of propargylic amide were chosen as a model reactions, respectively. In both organic transformations, the MIC metal complexes bearing two azobenzene moieties yielded the products more rapidly. These findings offer valuable insights into the development of photoswitchable MIC‐based metal complexes and their potential applications in catalysis.