Stereochemical investigations of coordinated sulfur stereocenters. X-ray structures of diastereomers of (-)589-[Pd{(R)-CH3CH(1-C10H 6)NMe2-C2,N}(R/S)-{Ph2PCH 2SMe-P,S}]PF6

Abstract

The reaction between bis(μ-chloro)bis[(R)-1-[(dimethylamino)ethyl]naphthylenyl-C 2,N]dipalladium(II) and 2 mol of the bidentate Ph2PCH2CH2SMe gave a pair of internal diastereomeric complex cations arising from the coordinated sulfur stereocenter. The hexafluorophosphate salt of the diastereomeric mixture crystallizes as a compound with [α]D -35° (CH2Cl2) in the triclinic space group P1 with a = 7.8690 (10) Å, b = 17.837 (2) Å, c = 21.830 (2) Å, α = 82.86 (1)°, β = 87.19 (1)°, γ = 83.39 (1)°, and Z = 4 (R = 0.0412 and Rw = 0.0666). In solution, the complexes exhibit facile intramolecular asymmetric equilibration between diastereomers epimeric at sulfur at room temperature. A coalescence temperature of -90°C was recorded for the interconversion by variable-temperature NMR spectroscopy. Similar behavior was observed for analogous complexes of Ph2AsCH2CH2SMe and Me2AsCH2CH2SMe. © 1992 American Chemical Society.