Syntheses and Reactivities of New PC_s_p3P Pincer Complexes of Nickel

Abstract

Heating Ni(II) halides with 1 equiv of But2P(CH2)5PBut2 gives the PCsp3P pincer complexes [{(But2P(CH2)2)2CH}NiX] (X = Cl, 1a; Br, 1b; I, 1c). These compounds react with MeMgCl or n-BuLi to give, respectively, the methyl species {(But2P(CH2)2)2CH}NiMe, 2, or the hydride species {(But2P(CH2)2)2CH}NiH, 3, while reaction with NaBPh4 in a mixture of benzene/acetonitrile gives the cationic species [{(But2P(CH2)2)2CH}Ni (N⋮CCH3)][BPh4], 4. Complexes 1−3 are inert toward olefins, but react with PhSiH3 to give (PhSiH)n. The cationic complex 4 is also inert toward most olefins, but its reaction with excess acrylonitrile results in displacement of coordinated acetonitrile to give [{(But2P(CH2)2)2CH}Ni(N⋮CCHCH2)][BPh4], 5. Complexes 1−5 have been characterized by NMR spectroscopy and, in the case of 1, 4, and 5, by X-ray crystallography.