Catalysis of surface dispersed Cu2+ species on t-ZrO2: square-planar Cu catalyzed cross-coupling of arylboronic acid and imidazole

We examined the Chan-Lam cross-coupling of imidazole and arylboronic acids under additive-free and mild conditions using heterogeneous CuO/MOX catalysts such as metal oxide-supported CuO and Cu-doped metal oxides. Among them, CuO/t-ZrO2 exhibited the best performance, which was more than ten times the turnover number in comparison with that of bulk CuO. By combining experimental and computational approaches, we elucidated the surface structure of CuO/t-ZrO2. The catalyst contained abundant highly reducible Cu2+ species, in contrast to other Cu2+-containing catalysts. Notably, X-ray absorption spectroscopy and density functional theory calculations revealed that the Cu2+ species are square-planar [CuO4]. Our results indicate that the highly active [CuO4] species play a key role in the present coupling reaction.

Automated summary

In this study, we investigated the Chan-Lam cross-coupling of imidazole and arylboronic acids using heterogeneous CuO/MOX catalysts under additive-free and mild conditions. Among them, CuO/t-ZrO2 showed the best performance, with a turnover number more than ten times higher than that of bulk CuO. Experimental and computational approaches revealed that the surface structure of CuO/t-ZrO2 contained abundant highly reducible Cu2+ species, specifically square-planar [CuO4], which played a crucial role in the coupling reaction.