Synthesis and structure of an air-stable binuclear complex of bis(ethylcyclopentadienyl)zirconium perfluorooctanesulfonate and its catalytic application in one-pot three-component aza-Friedel–Crafts reactions

An air-stable Lewis acidic binuclear complex of bis(ethylcyclopentadienyl)zirconium perfluorooctanesulfonate (1a) was successfully synthesized by the reaction of (CH3CH2Cp)2ZrCl2 with C8F17SO3Ag. The complex 1a was characterized by different techniques and found to have the nature of air-stability, water tolerance, thermal-stability, and strong Lewis-acidity. In addition, its solubility was higher than that of our previously reported uninuclear zirconocene bis(perfluorooctanesulfonate). This complex showed high catalytic efficiency, good recyclability, and reusability in the one-pot three-component aza-Friedel–Crafts reactions of indoles with aldehydes and N,N-dimethylaniline. The yields of the corresponding 3-diarylmethyl indoles are higher than those from the traditional Lewis acidic catalysts.