Counteranion-Dependent Reaction Pathways in the Protonation of Cationic Ruthenium鈥揤inylidene Complexes

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• 作者：Manuel Jim茅nez-Tenorio ; M. Carmen Puerta ; Pedro Valerga ; Manuel A. Ortu帽o ; Gregori Ujaque ; Agustı ; &#769 ; Lled贸s
• 刊名：Organometallics
• 出版年：2014
• 出版时间：May 27, 2014
• 年：2014
• 卷：33
• 期：10
• 页码：2549-2560
• 全文大小：551K
• 年卷期：v.33,no.10(May 27, 2014)
• ISSN：1520-6041

文摘

The tetraphenylborate salts of the cationic vinylidene complexes [Cp*Ru鈺怌鈺怌HR(ⁱPr₂PNHPy)]⁺ (R = p-C₆H₄CF₃ (1a-BPh₄), Ph (1b-BPh₄), p-C₆H₄CH₃ (1c-BPh₄), p-C₆H₄Br (1d-BPh₄), ^tBu (1e-BPh₄), H (1f-BPh₄)) have been protonated using an excess of HBF₄路OEt₂ in CD₂Cl₂, furnishing the dicationic carbyne complexes [Cp*Ru鈮CH₂R(ⁱPr₂PNHPy)]²⁺ (R = p-C₆H₄CF₃ (2a), Ph (2b), p-C₆H₄CH₃ (2c), p-C₆H₄Br (2d), ^tBu (2e), H (2f)), which were characterized in solution at low temperature by NMR spectroscopy. The corresponding reaction of the chloride salts 1a-Cl, 1b-Cl, 1c-Cl, and 1d-Cl followed a different pathway, instead affording the novel alkene complexes [Cp*RuCl(魏¹(N),畏²(C,C)-C₅H₄N-NHPⁱPr₂CH鈺怌HR)][BF₄] (3a鈥?b>d). In these species, the entering proton is located at the 伪-carbon atom of the former vinylidene ligand, which also forms a P鈥揅 bond with the phosphorus atom of the ⁱPr₂PNHPy ligand. To shed light on the reaction mechanism, DFT calculations have been performed by considering several protonation sites. The computational results suggest metal protonation followed by insertion. The coordination of chloride to ruthenium leads to alkenyl species which can undergo a P鈥揅 coupling to yield the corresponding alkene complexes. The noncoordinating nature of [BPh₄]^{鈭?/sup> does not allow the stabilization of the unsaturated species coming from the insertion step, thus preventing this alternative pathway.}