Conformation and Stability of the Hydrogen-Bonded Complex 6-Oxabicyclo[3.1.0]hexane⋅⋅⋅HCl

Abstract

The hydrogen-bonded complex between 6-oxabicyclo[3.1.0]hexane and hydrogen chloride was investigated by microwave spectroscopy in a supersonic jet. A dual flow pulsed valve was used to preclude chemical reaction between the monomers. Only the equatorial conformer was observed and the spectra of three isotopomers, (C5H8O, H35Cl), (C5H8O, H37Cl) and (C5H8O, D35Cl), were measured. The derived structure of the complex has Cs symmetry with the hydrogen chloride pointing to the domain of the equatorial lone pair of electrons at the oxygen atom. The three atoms involved in the hydrogen bond adopt a bent arrangement with a O...H distance of 1.77(4) A, a (O...H-Cl) angle of 115(4)degrees, and a deviation of 15.4(14)degrees of the hydrogen bond from collinearity. In agreement with the experimental results, ab initio calculations predict the equatorial form to be the most stable one.

Determination of the Structure of Cyclopentene Oxide and the Argon−Cyclopentene Oxide van der Waals Complex

“…We also observed spectra from three unique 13 C isotopologues of CPO, of which two pairs of these isotopologues had intensities that were about twice as large as the lone 13 C γ isotopologue, consistent with the observations in ref . This reconfirms that the pairs of β and α carbons are equivalent to their symmetric β′ and α′ counterparts, respectively, see Figure .…”

“…This reconfirms that the pairs of β and α carbons are equivalent to their symmetric β′ and α′ counterparts, respectively, see Figure . The heavy atom Kraitchman substitution structure confirms the C s symmetry of the molecule and boat structure of the ring as in refs and . Although, Kraitchman substitution coordinates are absolute values, only the coordinates with the signs given in Table are consistent with all the isotopologue substitution coordinates and the r e structure from a DFT calculation with a basis set, B3LYP/6-311++g(2df,2pd), using the Gaussian suite of programs .…”

“…Assigned frequencies were fit to a semirigid rotor Hamiltonian in I r representation with a Watson A reduction, using Pickett’s spectral fitting programs with three rotational constants and five quartic centrifugal distortion constants that are reported in Table . The rotational constants for the monomer, CPO, and Kraitchman substitution structures are only modestly improved over those of ref , but the centrifugal distortion constants were fit better since we observed transitions up to J = 7 and K a and K c = 6. The planar moments are also reported in Table .…”

“…Our previous work on argon ring complexes has the argon in a position that is in van der Waals contact with relatively positive hydrogens. In the argon CPO complex, the position of argon is exo to the ring avoiding the polar C−O bonds and the oxygen lone pairs to which the HCl hydrogen is bound in the CPO−HCl complex …”

“…1 Carriera and Lord 2 studied the far-infrared spectrum of CPO and determined that their data could be best fit with a single minimum, asymmetrical potential, suggesting the chair conformation has an energy approximately 1000 cm -1 higher than the boat. Antolinez et al 3 using FTMW spectroscopy determined the heavy atom substitution structure of CPO. They assigned the hydrogenbonded complexes of HCl and DCl, including 35 Cl and 37 Cl isotopes, with CPO.…”