Complexes of hybrid ligands. Some Pd2+ and Pt2+ complexes of fluoro-alkoxy thioether ligands; the measurement of the trans-effect of phosphines on thioether inversion

The hybrid ligands R—S—CH 2 —C(CF 3 ) 2 —O − (R = CH 3 or C 6 H 5 ) have been used in conjunction with the other donors to prepare complexes of Pt 2+ and Pd 2+ . Five-membered chelate rings are formed by coordination through the hard alkoxy and the soft thioether donor sites. Products are of two types: neutral MCl{RSCH 2 C(CF 3 ) 2 O}(PR 3 ) or cationic [M{RSCH 2 C(CF 3 ) 2 O}(PR 3 ) 2 ] + , and their geometry is assigned. Variable temperature nmr measurements are used to follow the inversion of the thioether function in the hybrid chelate ring, and values of ΔG‡ are calculated. From a comparison of the barrier to inversion in various complexes, the dynamic trans effect of various ligands is assessed including, for the first time using this criterion, the trialkylphosphines.