The Bis(pentafluoroethyl)phosphinous acid (C2F5)2POH.
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.
Hoge
Berthold
B
Institut für Anorganische Chemie, Universität zu Köln, Greinstrasse 6, 50939 Köln, Germany.
Bader
Julia
J
Beckers
Helmut
H
Kim
Yong Seol
YS
Eujen
Reint
R
Willner
Helge
H
Ignatiev
Nikolai
N
D009682:Magnetic Resonance Spectroscopy; D017976:Phosphorus Acids / Q000138:chemical synthesis / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013237:Stereoisomerism; D013816:Thermodynamics; D005466:Fluorocarbons
D017976:Phosphorus Acids; C540666:bis(pentafluoroethyl)phosphinous acid; D005466:Fluorocarbons