Heterolytic Activation of H-X (X = H, Si, B, and C) Bonds: An Experimental and Theoretical Investigation
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- 作者：C. M. Nagaraja ; Pattiyil Parameswaran ; Eluvathingal D. Jemmis ; Balaji R. Jagirdar
- 刊名：Journal of the American Chemical Society
- 出版年：2007
- 出版时间：May 2, 2007
- 年：2007
- 卷：129
- 期：17
- 页码：5587 - 5596
- 全文大小：199K
- 年卷期：v.129,no.17(May 2, 2007)
- ISSN：1520-5126
文摘
The highly electrophilic, coordinatively unsaturated, 16-electron [Ru(P(OH)3)(dppe)2][OTf]2 (dppe= Ph2PCH2CH2PPh2) complex 1 activates the H-H, the Si-H, and the B-H bonds, in H2(g), EtMe2SiHand Et3SiH, and H3B·L (L = PMe3, PPh3), respectively, in a heterolytic fashion. The heterolysis of H2 involvesan 
2-H2 complex (observable at low temperatures), whereas the computations indicate that those of theSi-H and the B-H bonds proceed through unobserved 1-species. The common ruthenium-containingproduct in these reactions is trans-[Ru(H)(P(OH)3)(dppe)2][OTf], 2. The [Ru(P(OH)3)(dppe)2][OTf]2 complexis unique with regard to activating the H-H, the Si-H, and the B-H bonds in a heterolytic manner. Thesereactions and the heterolytic activation of the C-H bond in methane by the model complex [Ru(POH)3)(H2PCH2CH2PH2)2][Cl][OTf], 4, have been investigated using computational methods as well, at the B3LYP/LANL2DZ level. While the model complex activates the H-H, the Si-H, and the B-H bonds in H2, SiH4,and H3B·L (L = PMe3, PPh3), respectively, with a low barrier, activation of the C-H bond in CH4 involvesa transition state of 57.5 kcal/mol high in energy. The inability of the ruthenium complex to activate CH4 isdue to the undue stretching of the C-H bond needed at the transition state, in comparison to the othersubstrates.
2-H2 complex (observable at low temperatures), whereas the computations indicate that those of theSi-H and the B-H bonds proceed through unobserved 1-species. The common ruthenium-containingproduct in these reactions is trans-[Ru(H)(P(OH)3)(dppe)2][OTf], 2. The [Ru(P(OH)3)(dppe)2][OTf]2 complexis unique with regard to activating the H-H, the Si-H, and the B-H bonds in a heterolytic manner. Thesereactions and the heterolytic activation of the C-H bond in methane by the model complex [Ru(POH)3)(H2PCH2CH2PH2)2][Cl][OTf], 4, have been investigated using computational methods as well, at the B3LYP/LANL2DZ level. While the model complex activates the H-H, the Si-H, and the B-H bonds in H2, SiH4,and H3B·L (L = PMe3, PPh3), respectively, with a low barrier, activation of the C-H bond in CH4 involvesa transition state of 57.5 kcal/mol high in energy. The inability of the ruthenium complex to activate CH4 isdue to the undue stretching of the C-H bond needed at the transition state, in comparison to the othersubstrates.