Rotational Spectroscopy and Ring-Puckering Conformation of 3-Hydroxytetrahydrofuran

The microwave spectrum of 3-hydroxytetrahydrofuran was recorded using a Fourier transform microwave spectrometer; the rotational constants (MHz) are: A = 5581.8230(7), B = 3638.8316(7), and C = 2924.7410(7). Microwave spectra for four 13C isotopic species were recorded in natural abundance. Stark effect measurements were used to determine the projections of the dipole moment on the principal inertial axes: μa = 0.956(1) D, μb = 0.875(2) D, μc = 1.050(2) D, and μtot = 1.667(2) D. The internal coordinates of the carbon and oxygen atoms were least-squares fit to the 15 moments of inertia, and the best-fit structure is a C4′-endo envelope ring conformation, in good agreement with ab initio calculations (MP2/6-31G††).