RHODIUM(I) AND RHODIUM(III) PHOSPHINE COMPLEXES WITH NONBRIDGING BENZENETHIOLATO LIGANDS - PREPARATION, STRUCTURES, AND CHEMICAL-PROPERTIES

Reactions of NaSPh with [Rh(PMe3)4]Cl and with RhCl(PMe3)3 give Rh(SPh)(PMe3)3 (1), whose X-ray crystallography shows a square-planar coordination. Temperature-dependent NMR (H-1 and P-31{H-1}) spectra of 1 show fluxionality of the molecule due to intramolecular exchange of the ligands in the solution. Complex 1 reacts smoothly with air to give the dioxygen-coordinated complex Rh(SPh)(O2)(PMe3)3 (2). X-ray crystallography shows a distorted trigonal bipyramidal coordination around the metal center having a dioxygen ligand with the O-O bond distance of 1.456(6) angstrom. Addition of air to the reaction mixture of [Rh(PMe3)4]Cl with NaSC6H4-p-OMe gives the analogous dioxygen-coordinated complex Rh(SC6H4-P-OMe)(O2)(PMe3)3 (3). Reaction of complex 1 with HSPh in hexane causes oxidative addition of the S-H bond to the metal center to give the Rh(III) complex cis,mer-RhH(SPh)2(PMe3)3 (4a) as the initial product. Further stirring of the reaction mixture at room temperature causes isomerization of 4a into trans,mer-RhH(SPh)2(PMe3)3 (4b). NMR (H-1 and P-31) Spectra of the complexes 4a and 4b as well as X-ray crystallography of 4b indicate their respective structures unambiguously. Reaction of DSPh (65% D) with 4a gives trans,mer-RhD(SPh)2(PMe3)3 (4b-d1) in 55% isotopic purity, while similar reaction with 4b causes deuteration in 18%. Reaction of phenyl acetylene with complex 1 gives mer-RhH-(C=CPh)(SPh)(PMe3)3 (5) with the acetylide and the thiolato ligands at mutually trans positions.