The molecular beam spectrum and the structure of the hydrogen fluoride dimer

The molecular beam spectrum of the hydrogen fluoride dimer has been investigated in detail. Microwave and radiofrequency transitions of (HF)2, HFDF, and (DF)2 are reported for both the Ka =0 and Ka =1 rotational levels. The results provide information on the structure of the dimers and on the nature of the intermolecular potential energy surface. The average F–F distance is shown to be approximately 2.78 A but with a probably significantly shorter equilibrium distance. The nonhydrogen bonded hydrogen atom is bent 63°±6° from the F–F axis. In addition, analysis of the perpendicular electric dipole moment indicates a nonlinear hydrogen bond. The large centrifugal distortion effects and the unusual quantum mechanical tunneling provide a crude model for the potential surface associated with the hydrogen bond; the effective bond stretching force constant is (1.36±0.03)×104 dyn cm−1.

[1]  R. E. Leckenby,et al.  The observation of double molecules in gases , 1966, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[2]  B. Howard,et al.  An intermolecular potential-energy surface for (HF)2 , 1982 .

[3]  Roger Hayward,et al.  The Hydrogen Bond , 1960 .

[4]  W. J. Lafferty,et al.  Rotational structure and vibrational predissociation in the HF stretching bands of the HF dimer , 1983 .

[5]  D. Levy,et al.  Electron Resonance of Gaseous Diatomic Molecules , 1968 .

[6]  P. Kollman,et al.  Theory of the Hydrogen Bond: Ab Initio Calculations on Hydrogen Fluoride Dimer and the Mixed Water–Hydrogen Fluoride Dimer , 1970 .

[7]  R. Weiss.  Molecular Beam Electron Bombardment Detector , 1961 .

[8]  E. Kaiser.  Dipole Moment and Hyperfine Parameters of H35Cl and D35Cl , 1970 .

[9]  Peter A. Kollman,et al.  Theory of the hydrogen bond , 1972 .

[10]  S. Novick,et al.  POLARITY OF VAN DER WAALS MOLECULES , 1973 .

[11]  W. Klemperer,et al.  Radiofrequency and Microwave Spectrum of the Hydrogen Fluoride Dimer; a Nonrigid Molecule , 1972 .

[12]  P. Bunker,et al.  The rigid bender and semirigid bender models for the rotation-vibration Hamiltonian , 1977 .

[13]  C. Bender,et al.  Interaction potential between two rigid HF molecules , 1974 .

[14]  G. Neely.  Interpretation of extreme centrifugal distortion in HNCO, HNCS and their deuterium derivatives , 1968 .

[15]  A. R. Edmonds.  Angular Momentum in Quantum Mechanics , 1957 .

[16]  J. Muenter.  Electric Dipole Moment of Carbonyl Sulfide , 1968 .

[17]  L. Curtiss,et al.  Ab initio calculation of the force field of the hydrogen fluoride dimer , 1976 .

[18]  M. Waldman,et al.  Internal dynamics of van der Waals complexes. I. Born–Oppenheimer separation of radial and angular motion , 1977 .

[19]  S. Novick,et al.  Determination of the structure of ArHCl , 1973 .

[20]  H. Lischka.  A note on the AB initio calculation of intermolecular potentials: the HF dimer , 1979 .

[21]  G. Diercksen,et al.  SCF MO LCGO studies of hydrogen bonding: The hydrogen fluoride dimer , 1970 .

[22]  Hideaki Umeyama,et al.  The origin of hydrogen bonding. An energy decomposition study , 1977 .