2.1. Materials

[Rh₂(μ–O₂CCH₂OEt)₄(HO₂CCH₂OEt)₂] [60] and [Rh₂(μ–O₂CCMe₃)₄(HO₂CCMe₃)₂] [65,66] were prepared following published procedures. PPh₄[Au(CN)₂] was synthesized following the published method to obtain PPh₄[Ag(CN)₂] [60]. A solution of 0.2 mmol (0.06 g) of K[Au(CN)₂] in 4 mL of water was mixed with a solution of 0.2 mmol (0.08 g) of PPh₄Br in 8 mL of water and stirred for 5 min at room temperature. The white precipitate obtained was collected by filtration and washed with 15 mL of water and 10 mL of diethyl ether (10 mL). Yield: 0.082 g (70%). The rest of the reagents and solvents were acquired from commercial sources and used as received without further purification.