Carbenes tetracarbene

It is interesting to note, that apart from the impressive series of transition metal complexes with monodentate NHCs, tetracarbene palladium(II) and platinum(II) as well as hexacarbene iron(III) complexes with bi- and tridentate chelating carbene ligands were prepared. 

Meyer S, Orben CM, Demeshko S, Dechert S, Meyer F. Synthesis and characterization of di- and tetracarbene iron(II) complexes with chelating N-heterocychc carbene ligands and their apphcation in aryl Grignard-alkyl halide cross-coupling. Organometallics. 2011 30 6692—6702. 

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