Does perdeuteration increase the polarity of Janus face cycloalkanes?

Stimulated by a suggestion of the late Professor Jack D. Dunitz, that perdeuterated Janus face cycloalkanes may be more polar than their unlabelled forms, the deuterated isotopologue of all cis-1,2,3,4,5,6-hexafluorocyclohexane ([²H₆]-1a) and all cis-1,2,3,4-tetrafluorocyclopentane ([²H₆]-3a) were prepared. Computation at the B3LYP−D3 level indicated that [²H₆]-1a is not more polar than its protio form 1, however perdeuterated cyclopentane [²H₆]-3a may indeed be more polar than 3, although the magnitude is predicted to be small. None-the-less retention time analysis on a reverse phase GC/MS column of an add-mix of 3 and [²H₆]-3a gave some indication that the per-deuterated isotopologue 3a was detected marginally before the unlabelled compound consistent with increased polarity associated with perdeuteration.