Synthetic, thermochemical, and catalytic studies of fluorinated tertiary phosphine ligands R2PRf [R = Cy, Ph, Pr-i; R-f = CH ' 2CH2(CF2)(5)CF3] in rhodium systems

The fluoroalkylphosphine compounds PR2Rf (R = Cy (1); Pr-i (2); R-f = CH2CH2(CF2)(5)CF3) have been prepared from the reactions of the Grignard reagent IMgRf and appropriate ClPR2 (R = Cy, Pr-i). The fluorinated phosphine ligands [PR2Rf (R = Cy (1); Pr-i (2); Ph (3); R-f = CH2CH2(CF2)(5)CF3] react with [Rh(CO)(2)Cl](2) to yield the corresponding [Rh(CO)Cl(PR2Rf)(2)] (R = Cy (4); Pr-i (5); Ph (6)) complexes. Infrared studies on the carbonyl complexes and solution calorimetry studies of the reaction of (Rh(CO)(2)Cl](2) with PR2Rf (R = Ph, Pr-i, Cy) have been used to quantify the relative ligand donor strength for the series: PCy2Rf approximate to (PPr2Rf)-Pr-i > PPh2Rf. The solid-state crystal structure of [Rh(CO)Cl(PPh2Rf)(2)] (6) is reported. Additionally, these partially fluorinated phosphine ligands (1 and 3) can be used as supporting ligation in rhodium-mediated hydrogenation reactions.