The Bis(pentafluoroethyl)phosphinous Acid (C₂F₅)₂POH

Abstract

The industrial product (C(2)F(5))(3)PF(2) is transformed into the phosphinic acid chloride (C(2)F(5))(2)P(O)Cl, which reacts with an excess of Bu(3)SnH in a clean, multistep reaction to give the stannyl derivative (C(2)F(5))(2)POSnBu(3). Subsequent treatment with gaseous HBr leads to the formation of (C(2)F(5))(2)POH, which is isolated in 70 % yield. Besides (CF(3))(2)POH, bis(pentafluoroethyl)phosphinous acid, (C(2)F(5))(2)POH, represents the second known example of a phosphinous acid that is predicted by using density functional theory calculations at the B3PW91/6-311G(3d,p) level to be more stable than the phosphane oxide tautomer, the energy difference being 11.7 kJ mol(-1). Only the phosphinous acid isomer is detectable in the gas phase and in solution. However, investigations of the neat liquid reveal a temperature-dependent tautomeric equilibrium with the phosphane oxide isomer (C(2)F(5))(2)P(O)H, which is characterized by vibrational and multinuclear NMR spectroscopic methods in combination with quantum-chemical calculations.

A study of the reaction of perfluoroalkyl Grignard reagents with phosphoryl chloride and phenylphosphonic dichloride

“…31 P and 19 F NMR spectra of the acids agree with the literature values. 11,13 31 P NMR monitoring of the reaction of C 2 F 5 MgCl with OvPCl 3 indicates the presence of a pentet at δ 21.8 ppm ( 2 J P-F = 96 Hz), while the 19 F NMR spectrum showed a broad singlet at δ −79.9 and a doublet at δ −121.3 ppm.…”

The Substituent Effect on the Energy Profiles of Inter and Intramolecular Proton Transfers between Phosphine Oxide‐Phosphinous Acid Tautomers

“…It could be concluded that electron-donating substituents (alkyl group) and oxygen-containing groups (hydroxyl and methoxy) stabilized the phosphine oxide tautomer and strong electron-withdrawing substituent (halogens) stabilized the phosphinous acid tautomer. These results were in accordance with those of the previous reports [8,9]. Considering energy À6 in this case.…”

“…It is important to know that the share of each tautomer is different when the connected groups to the phosphorus atom are changed. In the reported studies, it has been shown that electron-donating alkyl and aryl groups stabilize the phosphine oxide tautomer while electron-withdrawing substituents, such as trifluoromethyl, stabilize the phosphinous acid structure [9,10].…”

Air‐Stable Platinum and Palladium Complexes Featuring Bis[2,4‐bis(trifluoromethyl)phenyl]phosphinous Acid Ligands

“…[5] Shifting the tautomeric equilibrium towards the unusual form of a phosphinous acid can also be achieved by the introduction of electron-withdrawing substituents, such as trifluoromethyl-and pentafluoroethyl groups. [6,7] The employAbstract: Secondary phosphane oxides, R 2 P(O)H, are commonly used as preligands for transition-metal complexes of phosphinous acids, R 2 PÀOH (R = alkyl, aryl), which are relevant as efficient catalysts in cross-coupling processes. In contrast to previous work by other groups, we are interested in the ligating properties of an electron-deficient phosphinous acid, (R f ) 2 PÀOH, bearing the strongly electron-withdrawing and sterically demanding 2,4-bis(trifluoromethyl)phenyl group towards catalysisrelevant metals, such as palladium and platinum.…”