Carbonyl-Supported Coordination in Imidazolates: A Platform for Designing Porous Nickel-Based ZIFs as Heterogeneous Catalysts

Zeolitic imidazolate frameworks (ZIFs) are a subclass of metal-organic framework that have attracted considerable attention as potential functional materials due to their high chemical stability and ease of synthesis. ZIFs are usually composed of zinc ions coordinated with imidazole linkers, with some other transition metals, such as Cu(II) and Co(II), also showing potential as ZIF-forming cations. Despite the importance of nickel in catalysis, no Ni-based ZIF with permanent porosity is yet reported. It is found that the presence and arrangement of the carbonyl functional groups on the imidazole linker play a crucial role in completing the preferred octahedral coordination of nickel, revealing a promising platform for the rational design of Ni-based ZIFs for a wide range of catalytic applications. Herein, the synthesis of the first Ni-based ZIFs is reported and their high potential as heterogeneous catalysts for Suzuki-Miyaura cross-coupling CC bond forming reactions is demonstrated. Limited success at incorporating nickelinto ZIFs led to a hypothesis that problem lies in forcedtetrahedral coordination of nickel. Two linkers are tested that potentiallyallow for additional coordination, stable metal nodes and porous frameworkformation. The hypothesis is confirmed, prepared materials are tested asheterogeneous alternatives to homogeneous nickel organo-metal catalysts for Suzuki-Miyaura cross-coupling reaction.image