Mononuclear Phenolate Diamine Zinc Hydride Complexes and Their Reactions With CO2

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• 作者：Neil J. Brown ; Jonathon E. Harris ; Xinning Yin ; Ian Silverwood ; Andrew J. P. White ; Sergei G. Kazarian ; Klaus Hellgardt ; Milo S. P. Shaffer ; Charlotte K. Williams
• 刊名：Organometallics
• 出版年：2014
• 出版时间：March 10, 2014
• 年：2014
• 卷：33
• 期：5
• 页码：1112-1119
• 全文大小：348K
• 年卷期：v.33,no.5(March 10, 2014)
• ISSN：1520-6041

文摘

The synthesis, characterization, and zinc coordination chemistry of the three proligands 2-tert-butyl-4-[tert-butyl (1)/methoxy (2)/nitro (3)]-6-{[(2鈥?dimethylaminoethyl)methylamino]methyl}phenol are described. Each of the ligands was reacted with diethylzinc to yield zinc ethyl complexes 4鈥?b>6; these complexes were subsequently reacted with phenylsilanol to yield zinc siloxide complexes 7鈥?b>9. Finally, the zinc siloxide complexes were reacted with phenylsilane to produce the three new zinc hydride complexes 10鈥?b>12. The new complexes 4鈥?b>12 have 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(渭-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 complexes 13鈥?b>15. The zinc formate complexes have been analyzed by NMR spectroscopy and VT-NMR studies, which reveal a temperature-dependent monomer鈥揹imer equilibrium that is dominated by the mononuclear species at 298 K.