Chlorine Hyperfine Interactions in π‐Electron Radicals

Using data presented earlier, the complete anisotropic 35Cl hyperfine interaction tensor is evaluated for an α‐chlorine in a π‐electron radical for the first time. In CClHCOOH the tensor has an isotropic part aCl = + 3.7 G and anisotropic parts Bx = + 16.3 G, By = − 6.2 G, Bz = − 10.1 G. The x direction is normal to the radical plane while z is along the C–Cl bond. These values permit the following spin‐density assignments in the various orbitals of the C–Cl fragment: ρCπ = + 0.78, ρClπ = + 0.15, ρClσ(3pz) = − 0.03, and ρClσ(3s) = + 0.002.