Synthesis and Characterization of Amido Pincer Complexes of Lithium and Nickel and Catalysis of the Nickel Complexes in the Kumada Cross-Coupling

Abstract

Reaction of N-benzylidene-2-(diphenylphosphino)benzenamine (2) with Ph2PLi yielded [Li{N{CH(Ph)PPh2}C6H4(PPh2)-2}] (3), and that with Ph2PCH2Li·TMEDA generated [Li{N{CH(Ph)-CH2PPh2}C6H4(PPh2)-2}] (4). Treatment of 3 with (DME)NiCl2 gave [Ni(Cl){N{CH(Ph)PPh2}C6H4-(PPh2)-2}] (5). Reaction of 4 with (Et3P)2NiCl2 afforded [Ni(Cl){N{CH(Ph)CH2PPh2}C6H4(PPh2)-2}] (6). N-(2-(Diphenylphosphino)benzylidene)-2-(diphenylphosphino)benzenamine reacted with LiMe to give [Li{N{CH(Me)C6H4(PPh2)-2}{C6H4(PPh2)-2}}] (8), which reacted with (Et3P)2NiCl2 to produce [Ni(Cl){N{CH(Me)C6H4(PPh2)-2}{C6H4(PPh2)-2}}] (9). 2 was converted to iminophosphoranes 2-{ArN═P(Ph2)}C6H4N═CHPh (Ar = p-MeC6H4, 10a; Ar = 2,6-Pri2C6H3, 10b) by reaction with p-MeC6H4N3 and 2,6-Pri2C6H3N3, respectively. 10a reacted with Ph2PLi and then (DME)NiCl2 to form [Ni(Cl){N{CH(Ph)PPh2}C6H4{P(Ph2)═NC6H4Me-4}-2}] (11). The respective reaction of 10a and 10b with Ph2PCH2Li·TMEDA afforded [Li{N{CH(Ph)CH2PPh2}C6H4{P(Ph2)═NAr}-2}] (Ar = p-MeC6H4, 12a; Ar = 2,6-Pri2...