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

Reduction of the N1, N1-C-3-bridged di(benzimidazol-2-thione) (5) with a sodium/potassium alloy leads to the N1, N1'-C-3-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 C-carbene-Pd-C-carbine angle of 85.0(15)degrees. The carbene planes are oriented almost perpendicular (82.7 degrees and 79.3 degrees) to the PdI2C2 plane. (c) 2005 Elsevier B.V. All rights reserved.