Dipole moments, Kerr constants and solution-state conformations of di(pyridin-4-yl), di(pyridin-3-yl) and di(pyridin-2-yl) ketone

Abstract

Experimental dipole moments and molar Kerr constants are reported and analysed for di(pyridin-4-yl), di(pyridin-3-yl) and di(pyridin-2-yl) ketone as solutes in carbon tetrachloride or cyclohexane at 298 K. The preferred conformation of di(pyridin-4-yl) ketone is found to be very similar to those previously deduced for benzophenone and several 4,4'- disubstituted benzophenones. For di(pyridin-3-yl) and di(pyridin-2-yl) ketone three analogous conrotatory structures having different relative dispositions of the nitrogen atoms are considered. In the case of di(pyridin-3-yl) ketone the cis-trans and trans-trans arrangements are approximately equally abundant, but for di(pyridin-2-yl) ketone there is a strong preference for the trans-trans conformation.