Dual Association Modes of the 2,5,8‐Tris(pentafluorophenyl)phenalenyl Radical

The 2,5,8‐tris(pentafluorophenyl)phenalenyl radical was obtained by a straightforward synthesis in 11 steps from 2,7‐dibromonaphthalene. This radical crystallized as a σ dimer from a solution in MeCN and as a π‐stack from a melted liquid. The π stack was not confined to dimerization, but extended into a uniform 1D stack with an interplanar distance of 3.503 Å. This unique duality in association mode arose from the thermodynamic stability of the phenalenyl moiety.