THE STRUCTURE AND RING PUCKERING VIBRATIONS OF THIETANE FROM ITS DIPOLAR COUPLINGS

The r(alpha) structure of thietane has been obtained from its previous ly measured dipolar couplings. The molecular geometry can be described by a model of hindered pseudorotation characterized by a double minim um potential function. The optimized values for the geometric paramete rs are: r(CH) = 1.077 angstrom, HC(alpha)H = 109.7-degrees, HC(beta)H = 108.8-degrees and -6-8-degrees for the bending coordinate. The pucke ring amplitude q corresponding to the potential minimum is 0.24 angstr om, but the height of the inversion barrier (DELTAV) cannot be determi ned because the surface sigma(q, DELTAV) for the root mean square (RMS ) deviations between observed and calculated dipolar couplings shows a valley of minimum deviation instead of local minima.