Structural Chemistry of Methyl- and Allylpalladium(II) Complexes Containing Chiral Thioether Auxiliaries

Abstract

The molecular structures of three PdII compounds are reported: a) the two [PdCl(Me)] complexes 7a and 8a each containing a different chiral N,S-chelate based on {[(dihydrooxazolyl)phenyl]methyl}-thioglucose backbones, e.g., chloro({2-[(4S)-4,5-dihydro-4-isopropyloxazol-2-yl-κN]phenyl}methyl 2,3,4,6-tetra-O-acetyl-1-(thio-κS)-β-D-glucopyranoside)methylpalladium(II) (7a) and b) one [Pd(η3-C3H5)(P-S)]+ cation in which the P,S-chelate stems from a phosphinoferrocene and thioephedrine-derived thioether donor, i.e., [(S)-1-(diphenylphosphino-κP)-2-((1R)-1-{[(1R,2S)-1-phenyl-2-(piperidin-1-yl)propyl]thio-κS}ethyl)ferrocene] (η3-prop-2-enyl)palladium trifluoromethanesulfonate (11). In the methylpalladium compounds 7a and 8a the thioglucose-κS moiety is pseudo-axial (Figs. 2 and 3), whereas in the allyl complex, the thioephedrine-κS moiety is markedly pseudo-equatorial (Fig. 5). It is suggested, based on these results, that the shape (chiral pocket) of such coordinated chiral thioethers may not be readily predictable.