title: Conformations of Organophosphine Oxides.
abstract: The conformations of a series of organophosphine oxides, OP(CH3)2R, where R = methyl, ethyl, isopropyl, tert-butyl, vinyl, and phenyl, are predicted using the MP2/cc-pVTZ level of theory. Comparison of potential energy surfaces for rotation about P-C bonds with crystal structure data reveals a strong correlation between predicted location and energetics of minima and histograms of dihedral angle distributions observed in the solid state. In addition, the most stable conformers are those that minimize the extent of steric repulsion between adjacent rotor substituents, and the torsional barriers tend to increase with the steric bulk of the rotating alkyl group. MM3 force field parameters were adjusted to fit the MP2 results, providing a fast and accurate model for predicting organophosphine oxides shapes-an essential part of understanding the chemistry of these compounds. The predictive power of the modified MM3 model was tested against MP2/cc-pVTZ conformations for triethylphosphine oxide, OP(CH2CH3)3, and triphenylphosphine oxide, OP(Ph)3.
authors.affiliation: †Ames Laboratory and Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.
authors.forename: Nuwan
authors.initials: N
authors.lastname: De Silva
authors.affiliation: †Ames Laboratory and Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.
authors.forename: Federico
authors.initials: F
authors.lastname: Zahariev
authors.affiliation: ‡Supramolecular Design Institute, Oak Ridge, Tennessee 37830, United States.
authors.forename: Benjamin P
authors.initials: BP
authors.lastname: Hay
authors.affiliation: †Ames Laboratory and Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Gordon
authors.affiliation: †Ames Laboratory and Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.
authors.forename: Theresa L
authors.initials: TL
authors.lastname: Windus