Protonation and H2 Heterolysis Reactions of Electrophilic (5-C5R5)Ru(dfepe)(X) (R = H, Me;

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• 作者：Allyn C. Ontko ; James F. Houlis ; R. Chris Schnabel ; Dean M. Roddick ; Tina P. Fong ; Alan J. Lough ; and Robert H. Morris
• 刊名：Organometallics
• 出版年：1998
• 出版时间：December 7, 1998
• 年：1998
• 卷：17
• 期：25
• 页码：5467 - 5476
• 全文大小：186K
• 年卷期：v.17,no.25(December 7, 1998)
• ISSN：1520-6041

文摘

Addition of excess HOSO₂CF₃ (HOTf) to CpRu(L)H (1) (L = dfepe = PR₂CH₂CH₂PR₂, R =C₂F₅) in CD₂Cl₂ under N₂ produces a mixture of [CpRu(L)(H)₂]⁺ (2a), [CpRu(L)(H₂)]⁺ (2b),and CpRu(L)(OTf) (3) in a ratio of 1:5:2. Salts of the acid [HOEt₂]⁺ are not strong enough toprotonate 1. Complexes 2 slowly eliminate H₂ to give 3; this reaction is slowed by addingexcess HOTf. Of all such complexes [CpRu(PR₂CH₂CH₂PR₂)(H₂)]⁺, R = alkyl and aryl, thedihydrogen complex 2b has the greatest acidity (similar to that of HOTf) and the relatedHD complex has the greatest J_HD (29.1 Hz) because of the electron-withdrawing substituentsR = C₂F₅. The reaction of 3 with 1 atm H₂(g) proceeds much faster in the presence than inthe absence of 1 equiv of HOTf to produce 1 and HOTf. This is a rare example of theproduction of a strong acid from H₂(g) where the intermediate dihydrogen complex has beencharacterized. Reaction of Cp*Ru(L)Cl (4), Cp* = C₅Me₅, in dry CH₂Cl₂ at -78 f">C with AgXsalts under H₂(g) (1 atm) gives mixtures of Cp*Ru(L)H (5) and [Cp*Ru(L)(H)₂]⁺ (6), whichhave been identified by ¹H NMR. 6 is deprotonated by traces of water or by PPh₃ to giveCp*Ru(L)H (5). The addition of excess HOTf to mixtures of 5 and 6 under H₂(g) produces 6.Complexes 3, 4, and 5 have been characterized by single-crystal X-ray diffraction. ComplexesCpRu(L)Cl, 1, 4, and 5 have very positive redox potentials that indicate that the dfepe ligandhas the electron-withdrawing power close to that of two carbonyl ligands.