Enantiomerically Pure, Planar Chiral Cp*Ru Complexes: Synthesis, Molecular Structures, DFT and Coordination Properties

Reaction of (S)-1-(2-chlorophenyl)­ethanol with [Cp*Ru­(CH3CN)3]­[OTf] provides the single diastereomer (Sp)-[Cp*Ru­(η6-(S)-1-(2-chlorophenyl)­ethanol)]­[OTf] ((Sp,S)-1), in which the metal center is preferentially placed on one side of the arene ring. The other enantiomer (R)-1-(2-chlorophenyl)­ethanol provides the planar chiral ruthenium compound (Rp,R)-1. The structures of both enantiomers were ascertained by single-crystal X-ray diffraction. These compounds can be used as precursors to prepare the enantiopure metalated phosphino ligands (Sp)-[Cp*Ru­(η6-(S)-1-(2-diphenylphosphinophenyl)­ethanol)]­[OTf] ((Sp,S)-2) and (Rp)-[Cp*Ru­(η6-(R)-1-(2-diphenylphosphinophenyl)­ethanol)]­[OTf] ((Rp,R)-2), in which the −PPh2 unit is attached to a chiral metalated π-arene platform. The chiral planar phosphine ligands react with [AuCl­(tht)] to give heterobinuclear gold complexes with planar chirality, [AuCl­((Sp,S)-2)] ((Sp,S)-3) and [AuCl­((Rp,R)-2)] ((Rp,R)-3), as confirmed by their CD traces. Our method provides an entry to the preparation of a wide range of optically pure coordination compounds with potentially important properties.