Arene C[BOND]H Amination at Nickel in Terphenyl–Diphosphine Complexes with Labile Metal–Arene Interactions

Authors

  • Dr. David E. Herbert,

    1. Division of Chemistry and Chemical Engineering, California Institute of Technology–MC 127-72, 1200 E California Boulevard, Pasadena, CA 91125 (USA), Fax: (+1) 626-568-8824
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  • Nadia C. Lara,

    1. Division of Chemistry and Chemical Engineering, California Institute of Technology–MC 127-72, 1200 E California Boulevard, Pasadena, CA 91125 (USA), Fax: (+1) 626-568-8824
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  • Prof. Theodor Agapie

    Corresponding author
    1. Division of Chemistry and Chemical Engineering, California Institute of Technology–MC 127-72, 1200 E California Boulevard, Pasadena, CA 91125 (USA), Fax: (+1) 626-568-8824
    • Division of Chemistry and Chemical Engineering, California Institute of Technology–MC 127-72, 1200 E California Boulevard, Pasadena, CA 91125 (USA), Fax: (+1) 626-568-8824

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Abstract

The meta-terphenyl diphosphine, m-P2, 1, was utilized to support Ni centers in the oxidation states 0, I, and II. A series of complexes bearing different substituents or ligands at Ni was prepared to investigate the dependence of metal–arene interactions on oxidation state and substitution at the metal center. Complex (m-P2)Ni (2) shows strong Ni0–arene interactions involving the central arene ring of the terphenyl ligand both in solution and the solid state. These interactions are significantly less pronounced in Ni0 complexes bearing L-type ligands (2-L: L=CH3CN, CO, Ph2CN2), NiIX complexes (3-X: X=Cl, BF4, N3, N3B(C6F5)3), and [(m-P2)NiIICl2] (4). Complex 2 reacts with substrates, such as diphenyldiazoalkane, sulfur ylides (Ph2S[DOUBLE BOND]CH2), organoazides (RN3: R=para-C6H4OMe, para-C6H4CF3, 1-adamantyl), and N2O with the locus of observed reactivity dependent on the nature of the substrate. These reactions led to isolation of an η1-diphenyldiazoalkane adduct (2-Ph2CN2), methylidene insertion into a Ni[BOND]P bond followed by rearrangement of a nickel-bound phosphorus ylide (5) to a benzylphosphine (6), Staudinger oxidation of the phosphine arms, and metal-mediated nitrene insertion into an arene C[BOND]H bond of 1, all derived from the same compound (2). Hydrogen-atom abstraction from a NiI–amide (9) and the resulting nitrene transfer supports the viability of Ni–imide intermediates in the reaction of 1 with 1-azido-arenes.

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