First, the precursor complex Au2Cl2(dppe) was synthesized using a method reported by Corma et al. Specifically, 350 μmol of tetrachloroauric acid was dissolved in 2.5 mL of methanol. To this solution, 109 μL (1.05 mmol) of thiodiglycol, dissolved in 500 μL of methanol, was added, and the reaction mixture was stirred at room temperature for 1 h. After the solution changed from yellow to colorless and transparent, 69.7 mg (175 μmol) of dppe, dissolved in 4 mL of a chloroform:toluene (1:1 v/v) mixed solvent, was added, and the mixture was stirred at room temperature for 2 h. The resulting white precipitate was washed with methanol to yield Au2Cl2(dppe).