STEREOCHEMICAL INVESTIGATIONS OF COORDINATED SULFUR STEREOCENTERS - X-RAY STRUCTURES OF DIASTEREOMERS OF (-)589-[PD((R)-CH3CH(1-C10H6)NME2-C2,N)(R/S)-(PH2PCH2SME-P,S)]PF6

The reaction between bis(mu-chloro)bis[(R)-1-[(dimethylamino)ethyl]naphthylenyl-C2,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 [alpha]D -35-degrees (CH2Cl2) in the triclinic space group P1 with a = 7.8690 (10) angstrom, b = 17.837 (2) angstrom, c = 21.830 (2) angstrom, alpha = 82.86 (1)-degrees, beta = 87.19 (1)-degrees, gamma, = 83.39 (1)-degrees, and Z = 4 (R = 0.0412 and R(w) = 0.0666). In solution, the complexes exhibit facile intramolecular asymmetric equilibration between diastereomers epimeric at sulfur at room temperature. A coalescence temperature of -90-degrees-C was recorded for the interconversion by variable-temperature NMR spectroscopy. Similar behavior was observed for analogous complexes of Ph2AsCH2CH2SMe and Me2AsCH2CH2SMe.