Metalated-Arene-Phosphino Ligands: A Novel Approach to Open-Sided Gold Compounds

A novel type of metalated phosphino ligands, [Cp*Ru(η6-arene-PPh2)][OTf] (2a−d-OTf), has been prepared in which the −PPh2 unit is attached to a metalated π-arene platform. This unique class of ligands 2a−d are converted to open-sided cationic gold complexes 3a−d upon treatment with [AuCl(tht)]. The structure of one of these compounds, [Cp*Ru(η6-C6H5−PPh2−Au-Cl)][OTf] (3a-OTf), was ascertained by single-crystal X-ray diffraction. Preliminary studies suggest that cationic complex 3a is active in metal-catalyzed cycloisomerization reactions.