Study of the Replacement of Weak Ligands on Square-Planar Organometallic Nickel(II) Complexes. Organo-Nickel Aquacomplexes

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• 作者：Juan A. Casares ; Pablo Espinet ; Jesú ; s M. Martí ; nez-Ilarduya ; Jesú ; s J. Mucientes ; Gorka Salas
• 刊名：Inorganic Chemistry
• 出版年：2007
• 出版时间：February 5, 2007
• 年：2007
• 卷：46
• 期：3
• 页码：1027 - 1032
• 全文大小：99K
• 年卷期：v.46,no.3(February 5, 2007)
• ISSN：1520-510X

文摘

When trans-[NiRf₂L₂] (Rf = 3,5-C₆Cl₂F₃; L = group 15 soft monodentate weak ligand such as SbPh₃ or AsPh₃) isdissolved in wet (CD₃)₂CO, isomerization (to give cis-[NiRf₂L₂]) and subsequent substitutions of L by (CD₃)₂CO orby water occur, and several complexes containing acetone and aqua ligands are formed. The isomerization takesplace in a few seconds at room temperature. The substitution reactions on the cis isomer formed are faster. Thekinetics of the equilibria between all of the participating species have been studied by ¹⁹F exchange spectroscopyexperiments at 217 K, and the exchange rates and rate constants have been calculated. These data reflect theweakness of acetone compared to water and AsPh₃. The data obtained are the first available for square-planarnickel(II) aquacomplexes. The bulkier AsCyPh₂ ligand slows down the exchange processes while the displacementof AsMePh₂ is clearly disfavored. Activation entropy studies support an associative ligand substitution. All of thesedata fit well with the previously reported relative activity of these complexes as catalysts in norbornene polymerization.