Answer
Nickel is commonly employed as a catalyst in the Heck reaction, alongside palladium. This organic reaction involves the carbon-carbon bond formation between an aryl or vinyl halide and an alkene or alkyne. The versatility of nickel catalysts lies in their ability to facilitate various types of Heck reactions, including intermolecular and intramolecular processes. These reactions find wide application in the synthesis of complex organic molecules, pharmaceuticals, and natural products.