Redetermination of the Crystal Structure of the 1,2,4,7‐ anti ‐tetramethylbicyclo[2.2.1]heptan‐2‐yl cation at 110 K

The structure of the 1,2,4,7‐ anti ‐tetramethylbicyclo[2.2.1]heptan‐2‐yl cation ( 1 ) was redetermined by X‐ray crystal structure analysis of its Sb 2 F 11 salt at 110 K ( P 2 1 / c , R 1 = 5.76%). The most important structural features of 1 are: C(1)C(2) = 1.409(9), C(1)C(6) = 1.710(8), and C(2)…C(6) = 2.113(9) Å and C(2)C(1)C(6) = 84.7(4)°. These results agree with those obtained earlier by other methods for the rapidly equilibrating, partially s̀‐delocalized 1,2‐dimethylbicyclo[2.2.1]heptan‐2‐yl cation ( 2 ). The detailed experimental procedure for the preparation of crystalline 1 · Sb 2 F 11 and the crystal selection and mounting are described.