Syntheses and reactivities of new PC(SP3)P pincer complexes of nickel

Heating Ni(II) halides with 1 equiv of Bu-2(t)(CH2)(5)PBU2t gives the PCsp3P pincer complexes [{((Bu2P)-P-t(CH2)(2))(2)CH}NiX] (X = Cl, 1a; Br, 1b; 1, 1c). These compounds react with MeMgCl or n-BuLi to give, respectively, the methyl species {((Bu2P)-P-t(CH2)(2))(2)CH}NiMe, 2, or the hydride species {((Bu2P)-P-t(CH2)(2))(2)CH}NiH, 3, while reaction with NaBPh4 in a mixture of benzene/acetonitrile gives the cationic species [{((Bu2P)-P-t(CH2)(2))(2)CH}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 [{((Bu2P)-P-t(CH2)(2))(2)CH}Ni(N CCH=CH2)][BPh4], 5. Complexes 1-5 have been characterized by NMR spectroscopy and, in the case of 1, 4, and 5, by X-ray crystallography.