Synthesis of the First Chiral Bidendate Bis(trifluoromethyl)phosphane Ligand through Stabilization of the Bis(trifluoromethyl)phosphanide Anion in the Presence of Acetone

Lewis acid/Lewis base adduct formation of the P(CF 3 ) 2 − ion and acetone leads to a reduced negative hyperconjugation and, therefore, limits the CF bond activation. The resulting increased thermal stability of the P(CF 3 ) 2 − ion in the presence of acetone allows selective substitutions and enables the synthesis of the first example of a chiral, bidentate bis(trifluoromethyl)phosphane ligand: a DIOP derivative, [(2,2‐dimethyl‐1,3‐dioxolane‐4,5‐diyl)bis(methylene)]bis(diphenylphosphane), in which the phenyl groups at the phosphorus atoms are replaced by strong electron‐withdrawing trifluoromethyl groups. The resulting high electron‐acceptor strength of the synthesized bidentate (CF 3 ) 2 P ligand is demonstrated by a structural and vibrational study of the corresponding tetracarbonyl–molybdenum complex. The stabilization of the P(CF 3 ) 2 − ion in the presence of acetone is based on the formation of a dynamic Lewis acid/Lewis base couple, (CF 3 ) 2 PC(CH 3 ) 2 O − . Although there is no spectroscopic evidence for the formation of the formulated alcoholate ion, the intermediate formation of (CF 3 ) 2 PC(CH 3 ) 2 O − could be proved through the reaction with (CF 3 ) 2 PP(CF 3 ) 2 , which yields the novel phosphane–phosphinite ligand (CF 3 ) 2 PC(CH 3 ) 2 OP(CF 3 ) 2 . This ligand readily forms square‐planar Pt(II) complexes upon treatment with solid PtCl 2 .