A low-temperature dynamic 1 H, 13 C, and 77 Se NMR study of 2,2'-selenodicyclohexanol.

2,2'-Selenodicyclohexanol 1 was shown to exist as two (all-trans-achiral and all-trans-chiral) stereoisomers with all C-Se and C-OH bonds in equatorial orientations. When the temperature is lowered, the 1 H, 13 C, and 77 Se NMR spectra exhibit a strongly one-sided dynamic process, which involves sterically hindered rotation about the C-Se bond. Structures, free energy differences of the rotamers ΔG°, and the rotational barrier were determined and confirmed by quantum chemical calculations at the M06-2X/6-311++G**, M06-2X/cc-pVTZ, and MP2/6-311+G** levels of theory.