Α β-Diketiminato−Nickel(II) Synthon for Nickel(I) Complexes

The compound (Nacnac)Ni(μ-Br) 2 Li(THF) 2 (Nacnac = (HC(CMeNC 6 H 3 ( i -Pr) 2 ) 2 ) was reduced by reaction with K/Na alloy in toluene. The resulting product [((Nacnac)Ni) 2 (μ-η 3:η 3 -C 6 H 5 Me)] ( 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(PCy 3 ) ( 2 ), (Nacnac)Ni(Ph 2 PCH 2 PPh 2 ) ( 3 ), (Nacnac)Ni(NCPh) ( 4), (Nacnac)Ni( η 2 -PhCCPh) ( 5 ), (Nacnac)Ni( η 2 -Me 3 SiCCSiMe 3 )( 6 ), (Nacnac)Ni( η 2 -H 2 CCPh 2 ) ( 7 ), and (Nacnac)Ni(OCPh 2 ) ( 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( η 3: η 3 -C 5 H 4 CMe 2 )) 2 ] ( 9 ). The crystal structures of 1 − 9 are reported, and the bonding and reactivity of these products are discussed.