The palladium complexes of a C3-bridged di(benzimidazol-2-ylidene) ligand via cleavage of a dibenzotetraazafulvalene

Reduction of the N1, N1′-C3-bridged di(benzimidazol-2-thione) (5) with a sodium/potassium alloy leads to the N1, N1′-C3-bridged dibenzotetraazafulvalene (6). One equivalent of 6 reacts with palladium diiodide to give the dicarbene complex 1,3-(2,2-dimethylpropane)-N1,N1′-bis(N3-ethylbenzimidazol-2-ylidene)palladium diiodide (7). The X-ray crystal structure analysis of 7 reveals a slightly distorted square-planar coordination environment for the palladium center and a Ccarbene–Pd–Ccarbene angle of 85.0(15)°. The carbene planes are oriented almost perpendicular (82.7° and 79.3°) to the PdI2C2 plane.