- Heterolytic activation of H-X (X = H, Si, B, and C) bonds: An experimental and theoretical investigation
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The highly electrophilic, coordinatively unsaturated, 16-electron [Ru(P(OH)3)(dppe)2][OTf]2 (dppe = Ph 2PCH2CH2PPh2) complex 1 activates the H-H, the Si-H, and the B-H bonds, in H2(g), EtMe2SiH and Et3SiH, and H3B·L (L = PMe3, PPh3), respectively, in a heterolytic fashion. The heterolysis of H2 involves an η2-H2 complex (observable at low temperatures), whereas the computations indicate that those of the Si-H and the B-H bonds proceed through unobserved η1-species. The common ruthenium-containing product in these reactions is trans-[Ru(H)(P(OH) 3)(dppe)2][OTf], 2. The [Ru(P(OH)3)(dppe) 2][OTf]2 complex is unique with regard to activating the H-H, the Si-H, and the B-H bonds in a heterolytic manner. These reactions and the heterolytic activation of the C-H bond in methane by the model complex [Ru(POH)3)-(H2PCH2CH2PH 2)2][CI][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, PPh 3), respectively, with a low barrier, activation of the C-H bond in CH4 involves a transition state of 57.5 kcal/mol high in energy. The inability of the ruthenium complex to activate CH4 is due to the undue stretching of the C-H bond needed at the transition state, in comparison to the other substrates.
- Nagaraja,Parameswaran, Pattiyil,Jemmis, Eluvathingal D.,Jagirdar, Balaji R.
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- Silicon Tetrakis(trifluoromethanesulfonate): A Simple Neutral Silane Acting as a Soft and Hard Lewis Superacid
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A facile synthesis and isolation of pristine silicon tetrakis(trifluoromethanesulfonate), Si(OTf)4, is reported, acting as the first neutral silicon-based Lewis superacid suitable towards soft and hard Lewis bases. Its OTf groups have a dual function: they are excellent leaving groups and modulate the degree of reactivity towards soft and hard Lewis bases. Exposed to soft Lewis donors, Si(OTf)4 leads to [L2Si(OTf)4] complexes (L=isocyanide, thioether and carbonyl compounds) with retention of all Si?OTf bonds. In contrast, it can cleave C?X bonds (X=F, Cl) of hard organic Lewis bases with a high tendency to form SiX4 (X=F, Cl) after halide/triflate exchange. Most notable, Si(OTf)4 allows a gentle oxydefluorination of mono- and bis(trifluoromethyl)benzenes, resulting in the formation of the corresponding benzoylium species, which are stabilized by the weakly coordinating [Si(OTf)6] dianion.
- Driess, Matthias,Hermannsdorfer, André
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supporting information
p. 13656 - 13660
(2021/05/03)
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- Zinc-catalyzed silylation of terminal alkynes
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(Chemical Equation Presented) A rapid and high-yielding silylation of terminal alkynes employing TMSOTf and catalytic quantities of Zn(OTf) 2 has been developed. The reaction works well for a variety of substrates including reactive esters. Fifteen examples with yields of >90% are reported.
- Rahaim Jr., Ronald J.,Shaw, Jared T.
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p. 2912 - 2915
(2008/09/19)
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- Process for producing novel naphthyridine derivatives
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A novel naphthyridine derivative showing high activity as a tachykinin receptor antagonist can be produced at high efficiency by reacting an acylating agent such as a carboxylic acid derivative with a compound represented by the formula (1): wherein R1, R2 and R3 represent independently a hydrogen atom, a lower alkyl group, a lower alkoxyl group, an aryl group, a heteroaryl group, an amino group, etc., and X1 and X2 represent respectively a halogen atom.
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- Lewis acid mediated Peterson fluoroolefination
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Peterson olefination of the alkyl and aryl aldehydes with C,O-bis(triethylsilyl)fluoroketene acetal 1 promoted by titanium tetrachloride and dimethylaluminum chloride was investigated. Desired fluoroolefins were formed with high stereoselectivity and moderate to high yields.
- Welch, John T.,Gregor, Tamas,Kornilov, Andrei
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p. 171 - 178
(2007/10/03)
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