title: Mononuclear Phenolate Diamine Zinc Hydride Complexes and Their Reactions With CO2.
abstract: The synthesis, characterization, and zinc coordination chemistry of the three proligands 2-tert-butyl-4-[tert-butyl (1)/methoxy (2)/nitro (3)]-6-{[(2'-dimethylaminoethyl)methylamino]methyl}phenol are described. Each of the ligands was reacted with diethylzinc to yield zinc ethyl complexes4-6; these complexes were subsequently reacted with phenylsilanol to yield zinc siloxide complexes7-9. Finally, the zinc siloxide complexes were reacted with phenylsilane to produce the three new zinc hydride complexes10-12. The new complexes4-12have been fully characterized by NMR spectroscopy, mass spectrometry, and elemental analyses. The structures of the zinc hydride complexes have been probed using VT-NMR spectroscopy and X-ray diffraction experiments. These data indicate that the complexes exhibit mononuclear structures at 298 K, both in the solid state and in solution (d8-toluene). At 203 K, the NMR signals broaden, consistent with an equilibrium between the mononuclear and dinuclear bis(μ-hydrido) complexes. All three zinc hydride complexes react rapidly and quantitatively with carbon dioxide, at 298 K and 1 bar of pressure over 20 min, to form the new zinc formate complexes13-15. The zinc formate complexes have been analyzed by NMR spectroscopy and VT-NMR studies, which reveal a temperature-dependent monomer-dimer equilibrium that is dominated by the mononuclear species at 298 K.
authors.affiliation: Department of Chemistry, Imperial College London , South Kensington, London SW7 2AZ, U.K.
authors.forename: Neil J
authors.initials: NJ
authors.lastname: Brown
authors.affiliation: Department of Chemistry, Imperial College London , South Kensington, London SW7 2AZ, U.K.
authors.forename: Jonathon E
authors.initials: JE
authors.lastname: Harris
authors.affiliation: Department of Chemistry, Imperial College London , South Kensington, London SW7 2AZ, U.K.
authors.forename: Xinning
authors.initials: X
authors.lastname: Yin
authors.affiliation: Department of Chemical Engineering, Imperial College London , South Kensington, London SW7 2AZ, U.K.
authors.forename: Ian
authors.initials: I
authors.lastname: Silverwood
authors.affiliation: Department of Chemistry, Imperial College London , South Kensington, London SW7 2AZ, U.K.
authors.forename: Andrew J P
authors.initials: AJ
authors.lastname: White
authors.affiliation: Department of Chemical Engineering, Imperial College London , South Kensington, London SW7 2AZ, U.K.
authors.forename: Sergei G
authors.initials: SG
authors.lastname: Kazarian
authors.affiliation: Department of Chemical Engineering, Imperial College London , South Kensington, London SW7 2AZ, U.K.
authors.forename: Klaus
authors.initials: K
authors.lastname: Hellgardt
authors.affiliation: Department of Chemistry, Imperial College London , South Kensington, London SW7 2AZ, U.K.
authors.forename: Milo S P
authors.initials: MS
authors.lastname: Shaffer
authors.affiliation: Department of Chemistry, Imperial College London , South Kensington, London SW7 2AZ, U.K.
authors.forename: Charlotte K
authors.initials: CK
authors.lastname: Williams