Nucleophilic carbene complexes of manganocene

The reaction of the sterically demanding nucleophilic carbenes 1,3-bis(2,6- dimethyl-4-bromophenyl)imidazol-2-ylidene (1) and 1,3-dimesitylimidazol-2-y lidene (3) with manganocene resulted in complexes of the type (eta (2)-C5H5 )(eta (4)-C-5)Mn(carbene) (2 and 4). The reaction of equimolar amounts of t he less sterically demanding nucleophilic carbene tetramethylimidazol-2-yli dene (5) afforded the bis(carbene)complex (eta (1)-C5H5)-(eta (2)-C5H5)Mn(c arbene)(2) (6). The structures of these complexes were determined by single -crystal X-ray diffraction.