Mono- and Bimetallic (NacNac)Ni Cyclopentadienyl Complexes^†

Complexes of the form (Nacnac)Ni(η5-L) (L = Cp (3), indenyl (4)) are readily prepared and have been protonated to generate the corresponding cationic species [(HNacNac)Ni(η5-L)][B(C6F5)4] (L = Cp (5), indenyl (6)). While the symmetric compound 3 is paramagnetic, disruption of the symmetry in 4−6 results in diamagnetism. The species [((Nacnac)Ni)2(μ-η5:η5-Cp)][B(C6F5)4] (7) was prepared in an unusual fashion from the reaction of [(NacNac)Ni]2(η6:η6-C6H5Me) (2) with [Ph3C][B(C6F5)4] and Cp2ZrMe2, while compound 3 serves as a synthon to the neutral bimetallic Ni(II)/Ni(I) species [((Nacnac)Ni)2(μ-η2:η2-Cp)] (8). Compounds 7 and 8 are readily interconverted electrochemically. Consideration of the molecular orbitals reveals that the unpaired electron in 8 prompts alteration of the nature of the bridging cyclopentadienyl ligand between the metal centers. Crystal structures of 3−5, 7, and 8 are reported.