NMR studies of chiral P,S-chelate platinum, rhodium, and iridium complexes and the x-ray structure of a palladium (II) allyl derivative

Several Rh(I), Ir(III), and Pt(II) complexes of the chiral P,S-bidentate ligand 2 have been prepared and characterized. Detailed two-dimensional NMR studies show that (i) the boat-type chelate ring and the stereogenic sulfur center can invert rapidly at ambient temperature and (ii) the sulfur donor may dissociate, essentially destroying the chiral pocket. The solid-state structure of [Pt(η³-C₃H₅)(2)]PF₆ (3) has been determined and the sulfur substituent shown to have an axial orientation. The six-membered chelate ring takes up a boatlike conformation. As shown by an X-ray diffraction study for 3, and via incoherent inelastic neutron scattering (IINS) measurements for the Pd analog, 4, the OH group is remote from the metal atom.