Chiral Platinum Duphos Terminal Phosphido Complexes: Synthesis, Structure, Phosphido Transfer, and Ligand Behavior

Treatment of Pt halide precursors with the secondary phosphine PHMe(Is) in the presence of the base NaOSiMe 3 gave the terminal phosphido complexes Pt(Duphos)(Ph)(PMeIs) (Is = 2,4,6-( i -Pr) 3 C 6 H 2, Duphos = ( R, R )-Me-Duphos ( 1 ), ( R, R )- i -Pr-Duphos ( 2 )), Pt(( R, R )-Me-Duphos)(X)(PMeIs) (X = I ( 3 ), Cl ( 4 )), and Pt(( R, R )-Me-Duphos)(PMeIs) 2 ( 5 ). Low-barrier pyramidal inversion in the phosphido complexes was investigated by 31 P NMR spectroscopy. Protonation of 1 − 5 with HBF 4 gave the secondary phosphine complexes [Pt(Duphos)(Ph)(PHMeIs)][BF 4 ] (Duphos = ( R, R )-Me-Duphos ( 6 ), ( R, R )- i -Pr-Duphos) ( 7 )), [Pt(( R, R )-Me-Duphos)(X)(PHMeIs)][BF 4 ] (X = I ( 8 ), Cl ( 9 )), and [Pt(( R, R )-Me-Duphos)(PHMeIs) 2 ][BF 4 ] 2 ( 10 ); cations 6, 9, and 10 were prepared independently from Pt chloride precursors using Ag(I) salts and PHMe(Is) and then deprotonated to yield phosphido complexes 1 − 5 . Oxidation of the phosphido ligands in 4 and 5 with H 2 O 2 gave Pt(( R, R )-Me-Duphos)(Cl)(P(O)MeIs) ( 11 ) and Pt(( R, R )-Me-Duphos)(P(O)MeIs) 2 ( 12 ), respectively. Complexes 1 − 6, 9, and 11 were structurally characterized by X-ray crystallography; structural and 31 P NMR results suggest the trans influence order P(O)MeIs > PMeIs > PHMe(Is). Reaction of 1 with [Pd(allyl)Cl] 2, followed by treatment with dppe, gave Pt(( R, R )-Me-Duphos)(Ph)(Cl), PMeIs(allyl) ( 13 ), and Pd(dppe) 2 . Treatment of 1 with Pd(P( o -Tol) 3 ) 2 gave an equilibrium mixture containing the two-coordinate palladium complex Pd(P( o -Tol) 3 )(μ-PMeIs)Pt(( R, R )-Me-Duphos)(Ph) ( 14 ), Pd(P( o -Tol) 3 ) 2, P( o -Tol) 3, and 1 .