Coupled hydrogenation of arenes and alkenes or dienes with cobalt phosphine complexes

Шмидт, Ф. К.; Levkovskii, Y. S.; Saraev, V. V.; Ryutina, N. M.; Kosinskii, O. L.; Bakunina, T. I.

doi:10.1007/bf02073834

Cited by 4 publications

(2 citation statements)

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“…Numerous η 6 -arene transition metal complexes are catalytically active. , In some cases, the arene ligand stays bound to the metal center throughout the reaction cycle. 27b,c Of more interest to us, however, are cases in which the arene ligand is substitutionally labile on the metal center and acts to stabilize the complex in the absence of substrate or coordinating solvent …”

Section: Discussionmentioning

confidence: 99%

Oxidation-State-Dependent Reactivity and Catalytic Properties of a Rh(I) Complex Formed from a Redox-Switchable Hemilabile Ligand

et al. 1997

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The synthesis and characterization of a phosphinoalkylarene, redox-switchable hemilabile ligand (RHL), (η5-C5H5)Fe(η5-C5H4C6H4OCH2CH2PPh2) (1), are reported. This ligand, which incorporates a redox-active ferrocenyl group, exhibits oxidation-state-dependent bonding properties and, hence, affords electrochemical control over the electronic and steric environments of bound transition metal centers. Two equivalents of 1 complex to Rh(I) to yield a bis(phosphine), η6-arene complex [(η1:η6-(η5-C5H5)Fe(η5-C5H4C6H4OCH2CH2PPh2))(η1-(η5-C5H5)Fe(η5-C5H4C6H4OCH2CH2PPh2))Rh]+BF4 - (2). Single-crystal X-ray diffraction studies of 2·1.25CH2Cl2, as well as solution spectroscopic data of 2, are consistent with this formulated piano-stool geometry. Foremost, the properties of 2 as a function of bound RHL state-of-charge are extensively investigated. Interestingly, 2D 1H NMR exchange spectroscopy (EXSY) studies demonstrate significantly faster intramolecular η6-arene, free arene exchange rates only upon oxidation of the ligand chelated to the Rh(I) center, as found in 2 2+. This faster exchange rate was used as a qualitative measure of the increased lability of the η6-aryl group upon RHL oxidation. Moreover, activation parameters measured for the arene−arene exchange reaction of 2 2+ also support a decrease in the Rh(I)−arene interaction only upon oxidation of the ferrocenyl group on the bound η6-arene moiety. In addition, changes in the stoichiometric and catalytic reactivity of 2 upon RHL oxidation are consistent with the observed charge-dependent arene−arene exchange behavior. Significantly, labilization of a weakly bound η6-arene moiety in 2 2+ results in substantial increases in both the acetonitrile bonding affinity and allyl ethyl ether isomerization activity of the Rh(I)−RHL complex. In contrast, no significant changes in the reactivity of 2 were observed upon oxidation of the ligand which contained the ferrocenylarene not bound to the Rh(I) center, as found in 2 +. This dependence of complex reactivity on RHL oxidation state demonstrates the utility of such novel metal complexes for the reversible, electrochemical control of transition metal center small molecule uptake or catalytic activity via the selective labilization of weakly coordinating groups upon ligand oxidation.

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Section: Discussionmentioning

confidence: 99%

Oxidation-State-Dependent Reactivity and Catalytic Properties of a Rh(I) Complex Formed from a Redox-Switchable Hemilabile Ligand

et al. 1997

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“…These results have generated the need to study the cobalt-containing catalytic systems, formed by using LiAlH 4 and its alkoxy derivative LiAlH(t-BuO) 3 Red:Co two features: a high activity in the hydrogenation of alkenes and arenes [3,7] and a possibility of carrying out the reactions of conjugated hydrogenation of alkenes and arenes in the presence of the systems modified with trialkylphosphines [12]. A research of the cobalt-containing catalytic systems will allow establishing general patterns and characteristics of the catalysts formed at the action of LiAlH 4 and its alkoxyhydride derivatives on the cobalt compounds.…”

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confidence: 99%

Formation of the cobalt hydrogenation catalysts at the action of lithium aluminum hydride and lithium tri(tert-butoxy)aluminohydride and their properties

et al. 2012

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The interaction of Co(acac) 2(3) with LiAlH 4 or LiAlH(t-BuO) 3 was studied using NMR, UV, IR, ESR spectroscopy, electron microscopy, and volumometry. The basic stages of formation of cobalt catalysts for hydrogenation were suggested. The formation of the nanoparticles that are active in the hydrogenation process is shown to occur at a ratio of reagents 5 ≤ Red/Co ≤ 12. The nanoparticles are stabilized by an excess of LiAlH 4 or LiAlH(t-BuO) 3 , as well as by the products of their catalytic decomposition under the action of cobalt in the reduced state. At the ratio LiAlH 4 / Co> 12 to obtain the particles active in catalysis their activation by a proton-donor compound is required.The study of the Ziegler systems based on the transition metal complex compounds combined with the organic hydride compounds of the metals from I-III groups in the hydrogenation catalysis has been carried out since the second half of XX century and is continued now [1][2][3][4]. Despite such a long period of study and industrial applications of these systems, in particular, in the process of hydrogenation of polymers [5], some aspects of the formation and nature of the catalytically active species require further research of fundamental nature. This concerns, above all, establishing all the functions of the I-III groups metal compounds in the processes of formation and operation of the Ziegler type catalyst.To date, experimentally has been shown that the coreagents in the Ziegler type systems are involved in the formation of hydride or an organic derivative of the transition metal, reduction of the transition metal compound, most often to the metal in the zero oxidation state, formation of adducts with the reduced form of the transition metal of the type of acid-base interaction, and stabilization of nanoparticles [6-8]. However, some aspects of this problem have not yet been substantiated experimentally. These include the role of the decomposition reactions of the I-III group metal compounds catalyzed by the transition metals [8,9].We have previously shown [10] that in the formation of nickel-based hydrogenation catalysts using lithium aluminum hydride LiAlH 4 , the function of the latter is not limited to the reduction of the nickel precursor. The tetrahydroaluminate anions adsorbed on the surface act as a stabilizer of the nickel nanoparticles. Besides, the tetrahydroaluminate anions and probably products of catalytic decomposition of LiAlH 4 occupying the vacant positions on the surface may act as catalyst poisons. Therefore, the resultant nanoparticles are active in the hydrogenation only when they are activated by a proton-donor compound. In contrast to nickel, the palladium catalysts active in the hydrogenation are formed under the action of LiAlH 4 without activation with alcohol or water at a ratio of LiAlH 4 /Pd < 10 [11].These results have generated the need to study the cobalt-containing catalytic systems, formed by using LiAlH 4 and its alkoxy derivative LiAlH(t-BuO) 3 as the reducing agent, in the hydrogenation processes. A...

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Addition of Hydrogen and Hydrogen Cyanide to Carbon–Carbon Double and Triple Bonds

James¹

1982

Comprehensive Organometallic Chemistry

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Coupled hydrogenation of arenes and alkenes or dienes with cobalt phosphine complexes

Cited by 4 publications

References 2 publications

Oxidation-State-Dependent Reactivity and Catalytic Properties of a Rh(I) Complex Formed from a Redox-Switchable Hemilabile Ligand

Oxidation-State-Dependent Reactivity and Catalytic Properties of a Rh(I) Complex Formed from a Redox-Switchable Hemilabile Ligand

Formation of the cobalt hydrogenation catalysts at the action of lithium aluminum hydride and lithium tri(tert-butoxy)aluminohydride and their properties

Addition of Hydrogen and Hydrogen Cyanide to Carbon–Carbon Double and Triple Bonds

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