Molecular conformation of di-2-pyridyl sulphide. A dipole moment, 1H nuclear magnetic resonance, and CNDO/2 study

Abstract

Di-2-pyridyl sulphide has been prepared and its electric dipole moment measured at 25 and 45°(3.50 D, in benzene solution). The 250 MHz variable temperature pulsed Fourier transform ¹H n.m.r. spectrum has been also measured and analysed. Results of theoretical energy calculations (CNDO/2 type)together with the experimental data have been interpreted in terms of molecular solute conformations. It has been found that the molecule prefers a twisted conformation in which the ring planes are rotated ca. 36° out of the CSC plane. A fast interconverson between the three conformers that correspond to the possible relative orientations of the pyridine rings in this structure was found to occur in the solution state.