A β-diketiminato-nickel(II) synthon for nickel(I) complexes

The compound (Nacnac)Ni(mu-Br)(2)Li(THF)(2) (Nacnac = (HC(CMeNC6H3(i-Pr)(2))(2)) was reduced by reaction with K/Na alloy in toluene. The resulting product [((Nacnac)Ni)(2)(mu-eta(3):eta(3)-C(6)H(5)MeA (1) was characterized and is best described as a Ni(II) species in which electron transfer from Ni to toluene has occurred. This compound reacts with a variety of donors to give Ni(I) complexes. For example, compound 1 reacts with phosphines, nitriles, acetylenes, olefins, and ketones to give the paramagnetic complexes (Nacnac)Ni(PCy3) (2), (Nacnac)Ni(Ph2PCH2-PPh2) (3), (Nacnac)Ni(NCPh) (4), (Nacnac)Ni(eta(2)-PhCCPh) (5), (Nacnac)Ni(eta(2)-Me3SiCCSiMe3)-(6), (Nacnac)Ni(eta(2)-H2CCPh2) (7), and (Nacnac)Ni(OCPh2) (8). In the related reaction of 1 with dimethylfulvene, electron transfer from metal to ligand is evidenced by the formation of the dimetallic species [((Nacnac)Ni(eta(3):eta(3)-C5H4CMe2))(2)] (9). The crystal structures of 1-9 are reported, and the bonding and reactivity of these products are discussed.