Dynamic phenomena are established for the [D-3]methyl (2SR,3RS)-2-methyl-4,4,4-trichlorobutanoate-2-yl radical (1). This is revealed by EPR spectroscopy and quantum chemical calculations. The minimum conformations B and D of 1 possess planar radical centers and are sepearated by an energy barrier of 12.0 +/- 1.8 kJ.mol(-1) (experimental; calculated, 11.0 kJ.mol(-1)).