title: Carbon-hydrogen bond activation, C-N bond coupling, and cycloaddition reactivity of a three-coordinate nickel complex featuring a terminal imido ligand.
abstract: The three-coordinate imidos (dtbpe)Ni═NR (dtbpe = (t)Bu2PCH2CH2P(t)Bu2, R = 2,6-(i)Pr2C6H3, 2,4,6-Me3C6H2 (Mes), and 1-adamantyl (Ad)), which contain a legitimate Ni-N double bond as well as basic imido nitrogen based on theoretical analysis, readily deprotonate HC≡CPh to form the amide acetylide species (dtbpe)Ni{NH(Ar)}(C≡CPh). In the case of R = 2,6-(i)Pr2C6H3, reductive carbonylation results in formation of the (dtbpe)Ni(CO)2 along with the N-C coupled product keteneimine PhCH═C═N(2,6- (i)Pr2C6H3). Given the ability of the Ni═N bond to have biradical character as suggested by theoretical analysis, H atom abstraction can also occur in (dtbpe)Ni═N{2,6-(i)Pr2C6H3} when this species is treated with HSn((n)Bu)3. Likewise, the microscopic reverse reaction--conversion of the Ni(I) anilide (dtbpe)Ni{NH(2,6-(i)Pr2C6H3)} to the imido (dtbpe)Ni═N{2,6-(i)Pr2C6H3}--is promoted when using the radical Mes*O(•) (Mes* = 2,4,6-(t)Bu3C6H2). Reactivity studies involving the imido complexes, in particular (dtbpe)Ni═N{2,6-(i)Pr2C6H3}, are also reported with small, unsaturated molecules such as diphenylketene, benzylisocyanate, benzaldehyde, and carbon dioxide, including the formation of C-N and N-N bonds by coupling reactions. In addition to NMR spectroscopic data and combustion analysis, we also report structural studies for all the cycloaddition reactions involving the imido (dtbpe)Ni═N{2,6-(i)Pr2C6H3}.
authors.affiliation: Department of Chemistry, The University of Chicago , Chicago, Illinois 60637, United States.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Mindiola
authors.forename: Rory
authors.initials: R
authors.lastname: Waterman
authors.forename: Vlad M
authors.initials: VM
authors.lastname: Iluc
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Cundari
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Hillhouse
mesh_terms: D002244:Carbon / Q000737:chemistry; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D061565:Cycloaddition Reaction; D006859:Hydrogen / Q000737:chemistry; D007094:Imides / Q000138:chemical synthesis / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D007094:Imides; D008024:Ligands; D002244:Carbon; D009532:Nickel; D006859:Hydrogen