Determination of pKa for Dithiophosphinic Acids using Density Functional Theory

Journal Article · Wed Oct 01 04:00:00 EDT 2008 · Journal of Molecular Structure, THEOCHEM

DOI:https://doi.org/10.1016/j.theochem.2008.07.020· OSTI ID:944207

Benson, Michael T; Moser, Megan L; Peterman, Dean R; Dinescu, Adriana

Symmetric aromatic dithiophosphinic acids of the form (XC6H4)2P(=S)(SH), where X = H, o-CH3, p-CH3, p-Cl, p-F, o-CF3, m-CF3, and p-CF3, and asymmetric aromatic acids of the form (X’C6H4)(X”C6H4)P(=S)(SH), where X’ = o-CF3, X” = m-CF3; X’ = H, X” = o-CF3, have been investigated using B3LYP/Gaussian03. Solvation was included in the calculations using the CPCM continuum solvation method. Using the data from vibrational frequency calculations, the pKa was calculated for the acids, and compared to Cyanex-301. The unexpectedly high pKa for bis(o-trifluoromethylphenyl)dithiophosphinic acid, when compared to the ortho-meta, meta-meta, and para-para isomers, is rationalized by e- repulsion between nearby fluorines and the sulfurs in the anion. This repulsion destabilizes the anion, versus the other isomers, thus raising the pKa.

• Research Organization: Idaho National Laboratory (INL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC07-99ID13727
• OSTI ID: 944207
• Report Number(s): INL/JOU-08-14310
• Journal Information: Journal of Molecular Structure, THEOCHEM, Journal Name: Journal of Molecular Structure, THEOCHEM Journal Issue: 1-3 Vol. 867; ISSN JMOSB4; ISSN 0022-2860
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
AROMATICS
CARBOXYLIC ACIDS
Cyanex-301
ELECTRONS
FUNCTIONALS
ISOMERS
SOLVATION
density functional theory
dithiophosphinic acid
pKa