1,2,4-Triazole-Based N-Heterocyclic Carbene Nickel Complexes - Synthesis and Catalytic Application

Article abstract of DOI:10.1002/ejic.201500852

Four nickel complexes bearing 1,2,4-triazole-based N-heterocyclic carbene backbones and a cyclopentadienyl ligand were prepared from the corresponding 1,2,4-triazolium salts and nickelocene in tetrahydrofuran (THF) under reflux. The obtained complexes were fully characterized, including by X-ray diffraction analysis. They were then used as catalysts (5 mol-%) for the borylation of aryl bromide derivatives with bis(pinacolato)diboron in the presence of Cs₂CO₃ as the base in THF at 70 C for 20 h to form the corresponding borylated products in moderate yields. Four new nickel complexes bearing 1,2,4-triazole-based N-heterocyclic carbene backbones and a cyclopentadienyl ligand are prepared, fully characterized, and evaluated in the catalytic borylation of aryl bromides with bis(pinacolato)diboron.