Jahn-Teller Effect in the B12F12 Radical Anion and Energetic Preference of an Octahedral B6(BF2)6 Cluster Structure over an lcosahedral Structure for the Elusive Neutral B12F12

The B12F12- radical anion was generated by oxidation of [CoCp2+](2)B12F122- with AsFs in SO2. In the crystal structure of [CoCp2+]B12F12- the anion displays a lowered symmetry (D-2h) instead of an In-symmetric dianion as a result of Jahn-Teller distortion. Moreover, shortening of the B-F bonds and subtle changes of the B-B bonds are observed. DFT calculations show that, for the unknown neutral B12F12, I unprecedented structural isomers [e.g., octahedral B-6(BF2)(6)] are energetically favored instead of an icosahedral structure. structures and energetics are compared with those of the analogous chlorine