Synthesis of a perfluoroalkyl-substituted α-diimine by Sm-mediated reductive coupling

Samarium iodide mediates the reductive coupling of imidoyl iodide 1 to the corresponding enediamine 2, which is oxidized by manganese dioxide to an N,N′-diaryl-α-diimine 3. Single-crystal X-ray diffraction analysis shows that 2 crystallizes in the E,E-geometry, with a substantial nonplanarity of the NC–CN moiety, allowing a π-stacking interaction between the N-aryl rings. Unlike its 2,3-dimethyl analogue, 3 resists formation of chelates with palladium(II) or platinum(II).