The r_α structure of oxetane as studied by NMR spectroscopy in a nematic medium

Abstract

The proton and carbon-13 NMR spectra of oxetane partially orientated in a nematic solvent was analysed, and the dipolar coupling constants D_ij thus determined were used to obtain information about the r _α structure of the molecule. It is concluded that the oxetane molecule oscillates between two equivalent bent conformers characterized by a puckering amplitude of 0.128(5) Å. The optimized values for the remaining geometric parameters are: r _CHα = 1·094(1) Å, r _CHβ = 1·082(1) Å, HC_αH = 109·9(1)°, HC_βH = 110·2(1)°, and -4·8(5)° for the bending coordinate. The puckering potential function for oxetane cannot be determined because the surface σ(V ₂, V ₂) for the RMS deviations between observed and calculated D_ij values shows a valley of minimum deviation instead of local minima.