Similarities and Differences between the “Relativistic” Triad Gold, Platinum, and Mercury in Catalysis

Relativistic effects in the valence shell of the elements reach a maximum in the triad Pt–Au–Hg and determine their catalytic activity in organic reactions. In this Review we examine the catalytic activity of Pt, Au, and Hg compounds for some representative reactions, and discuss the respective benefits and disadvantages along with other relevant properties, such as toxicity, price, and availability. For the reactions considered, gold catalysts are generally more active than mercury or platinum catalysts.