Synthesis, Reactivity, and Metal Complexes of Fluorous Triarylphosphines of the Formula P(p-C₆H₄(CH₂)₃(CF₂)n₋₁CF₃)₃(n= 6, 8, 10)

Reactions of p- BrC 6 H 4 CH O with Wittig reagents derived from [Ph 3 PCH 2 CH 2 R f n ] + I - (R f n = (CF 2 ) n - 1 CF 3; n = 6 ( 6a ), 8 ( 6b ), 10 ( 6c )) give p- BrC 6 H 4 CH CHCH 2 R f n (86−93%), which are treated with H 2 and Wilkinson's catalyst to yield p- BrC 6 H 4 (CH 2 ) 3 R f n (91−94%). Reactions with n -BuLi and PCl 3 (0.33 equiv) give, after workup, mixtures of the title compounds ( 9a − c ) and the corresponding phosphine oxides ( 10a − c ). Treatment with H 2 O 2 gives pure 10 ( a / b / c 88/57/24%), which are reduced with Cl 3 SiH/Et 3 N to 9 ( a / b / c 69/82/43%). Fluorous phase affinities increase with perfluoroalkyl chain length, as quantified by CF 3 C 6 F 11 /toluene partition coefficients ( 9a, 19.5:80.5; 9b, 66.6:33.4). Reaction of 9b, [Ir(COD)(μ-Cl)] 2, and CO gives trans -Ir(CO)(Cl)[P( p- C 6 H 4 (CH 2 ) 3 R f8 ) 3 ] 2 (76%). The IR ν CO value is only slightly greater than that of Vaska's complex (1958 vs 1952 cm - 1 ), indicating nearly negligible inductive effects of the perfluoroalkyl groups. Reaction of 9b and [Rh(COD)(μ-Cl)] 2 yields Rh[P( p- C 6 H 4 (CH 2 ) 3 R f8 ) 3 ] 3 (Cl) (82−93%), which gives small equilibrium amounts of [Rh[P( p- C 6 H 4 (CH 2 ) 3 R f8 ) 3 ] 2 (μ-Cl)] 2 and 9b in solution, and catalyzes the hydrogenation of alkenes under both biphasic (CF 3 C 6 F 11 /toluene) and monophasic (CF 3 C 6 H 5 ) conditions.