Structural and conformational analysis of diethyl ether by molecular orbital constrained electron diffraction combined with microwave spectroscopic data

The millimeter- and submillimeter-wave spectrum of the trans–gauche conformer of diethyl ether

“…The resulting approximate expression DS 0 = R ln(2.05) leads to DS 0 = 5.97 · 10 À3 kJ mol À1 K À1 . This value is close to the value 6.49 · 10 À3 kJ mol À1 K À1 from [4]. The resulting ab initio-based room temperature population of the trans-gauche conformer is 29.3%, in good agreement with the experimental value.…”

“…All of those studies indicate that at room temperature the percentage of ether in this conformer is approximately 25-35%, and that it lies approximately 5-6 kJ mol À1 or 418-502 cm À1 above the ground state conformer, in agreement with ab initio determinations [4]. In astronomical units, the conformer lies approximately 600-700 K above the ground conformer, making its detection in hot molecular cores a distinct possibility if the tentative detection of the trans-trans form is correct.…”

“…Prior to our experimental work, the trans-gauche conformer had been studied by electron diffraction [4] and Raman spectroscopy in the gas phase, and by liquid-phase vibrational spectra [5,6]. All of those studies indicate that at room temperature the percentage of ether in this conformer is approximately 25-35%, and that it lies approximately 5-6 kJ mol À1 or 418-502 cm À1 above the ground state conformer, in agreement with ab initio determinations [4].…”

“…Results from previous gas-phase electron diffraction work [4] and vibrational spectroscopy of diethyl ether [5,6] suggest that the room temperature population of the trans-gauche conformer is near 30%. Supporting ab initio calculations were carried out at the MP2/6-31G ** level of theory with PC-GAMESS [18,19].…”

Submillimeter-wave spectrum of anti–anti and anti–gauche diethyl ether

“…The most recent geometry has been deduced from the combined results of rotational spectroscopy and electron diffraction [10]. The carbon atoms lie in a zig-zag structure in which they are most strongly separated; all of the heavy atoms and two hydrogen atoms lie in a plane, while the remaining pairs of hydrogen atoms are symmetrically disposed about this plane.…”