Activation of C–H and C–Br bonds in cyclopalladation reactions of Schiff base ligands: Influence of the benzylidene ring substituents

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• 作者：Leticia Naya ; Digna Vá ; zquez-Garcí ; a ; Margarita Ló ; pez-Torres ; Alberto Ferná ; ndez ; José ; M. Vila ; Nina Gó ; mez-Blanco ; Jesú ; s J. Ferná ; ndez
• 关键词：Palladium ; Schiff base ; C– ; H activation ; C– ; Br activation ; Triphosphine ; Diphosphine
• 刊名：Journal of Organometallic Chemistry
• 出版年：2008
• 出版时间：15 February 2008
• 年：2008
• 卷：693
• 期：4
• 页码：685-700
• 全文大小：487 K

文摘

Reaction of Pd(AcO)₂ with the Schiff base ligands 2-Br-4,5-(OCH₂O)C₆H₂C(H)N(Cy) (a) and 4,5-(OCH₂CH₂)C₆H₃C(H)N(Cy) (b) leads to the cyclometallated compounds [Pd{2-Br-4,5-(OCH₂O)C₆HC(H)N(Cy)-C6,N}(μ-O₂CMe)]₂ (1a) and [Pd{4,5-(OCH₂CH₂)C₆H₂C(H)N(Cy)-C6,N}(μ-O₂CMe)]₂ (1b), respectively, via C–H activation. Treatment of a with Pd₂(dba)₃ gave [Pd{4,5-(OCH₂O)C₆H₂C(H)N(Cy)-C2,N}(μ-Br)]₂ (6a), via C–Br activation. The metathesis reaction of 1a and 1b with aqueous sodium chloride gave the corresponding cyclopalladated dimers with bridging chloride ligands, 2a and 2b, respectively. Treatment of the halogen-bridged compounds with tertiary tri- and diphosphines in the appropriate molar ratio gave the mono and dinuclear compounds 3a–5a, 7a–9a and 3b–5b. The structure of compounds 3a, 4a, 5a, 8a, 2b, 3b and 5b has been determined by X-ray diffraction analysis.