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.