Synthesis and characterization of transition metal stabilized carbocations of the types [Cp^*(CO)₂Fe{μ-(C_nH_2n−1}M(CO)_xCp]PF₆ (x = 2, M = Fe or Ru; x =&#

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• 作者：Evans O. Changamu ; Holger B. Friedrich ; Melanie Rademeyer
• 关键词：Alkanediyl carbocation ; Mixed-ligand ; Heterobimetallic ; Metallacyclopropane ; Hydride abstraction
• 刊名：Journal of Organometallic Chemistry
• 出版年：2007
• 期刊代码：64_0022328x
• 类别：ch
• 出版时间：15 May 2007
• 卷：692
• 期：12
• 页码：2456-2472
• 文件大小：480 K

摘要

The mixed-ligand complexes [Cp^*(CO)₂Fe(CH₂)_nM(CO)_xCp] (x = 2, M = Fe or Ru; x = 3, M = W, Cp^* = η⁵-C₅(CH₃)₅; Cp = η⁵-C₅H₅;n = 3–6), type I, react with one equivalent of the hydride abstractor Ph₃CPF₆ to give the transition metal-stabilized carbocation complexes [Cp^*(CO)₂Fe{μ-(C_nH_2n−1)}M(CO)_xCp]PF₆. Similarly the new heterobimetallic complexes [Cp(CO)₂Ru{μ-(C_nH_2n−1)}W(CO)₃Cp], type II, react with Ph₃CPF₆ to give the carbocation complexes [Cp(CO)₂Ru{μ-(C_nH_2n−1)}W(CO)₃Cp]PF₆. Spectroscopic data show that hydride abstraction selectively takes place from the methylene group β to the metal atom attached to the Cp^* ligand in type I complexes. In type II complexes, the reaction is totally metalloselective with hydride abstraction occurring at the CH₂ β to the ruthenium metal centre. All products have been characterized by IR, ¹H,¹³C NMR spectroscopy and elemental analysis. ¹H and ¹³C NMR data clearly show that in the carbocation complexes one metal is σ-bonded to the alkanediyl carbocation while the other is bonded to the cationic end in a η²-fashion forming a chiral metallacylopropane type structure. The molecular structures of the cationic metallacyclic complexes [Cp^*(CO)₂Fe{μ-(C₃H₅)}Fe(CO)₂Cp]PF₆ [E.O. Changamu, H.B. Friedrich, M. Rademeyer, Acta Crystallogr., Sect. E 62 (2006) m442.] and [Cp^*(CO)₂Fe(μ-C₃H₅)Ru-(CO)₂Cp]PF₆ [H.B. Friedrich, E.O. Changamu, M. Rademeyer, Acta Crystallogr., Sect. E 62 (2006) m405.] have been confirmed by single crystal X-ray crystallography and reported elsewhere. The structures of the precursor complexes [Cp^*(CO)₂Fe(CH₂)₃Ru-(CO)₂Cp] (1), [Cp^*(CO)₂Fe(CH₂)₅Ru-(CO)₂Cp] (2), [Cp^*(CO)₂Fe(CH₂)₅W(CO)₃Cp] (3), and [Cp(CO)₂Ru (CH₂)₅W(CO)₃Cp] (4), have been confirmed by single crystal X-ray crystallography. The structure of [Cp^*(CO)₂Fe(CH₂)₃Ru(CO)₂Cp] is compared with that of its corresponding cationic complex, [Cp^*(CO)₂Fe{μ-(C₃H₅)}Ru(CO)₂Cp]PF₆.