Extreme electrophilicity of coordinated carbon monoxide in [CpCo(dppe)CO]2+

Bao, Q.-B.; Rheingold, Arnold L.; Brill, T. B.

doi:10.1021/om00142a015

Cited by 20 publications

(6 citation statements)

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“…The two μ-CH 2 −Co distances of 2.037(6) and 2.033(6) Å in 2a are also similar to those found in 1 (1.98 and 1.97 Å) . The Co−S distance of 2.317(2) Å is somewhat longer than in other CpCo(SR) complexes (typically 2.17−2.27 Å) − and is likely due to the steric interaction of the o -methyl groups with the Co-based Cp ligand. However, the Co−S distance is also approximately equal to the sum of the atomic radii …”

Section: Resultssupporting

confidence: 59%

Reaction of Organic Disulfides with Cobalt-Centered Metal Radicals. Use of the E- and C-Based Dual-Parameter Substituent Model and Quantitative Solvent Effect Analyses To Compare Outer-Sphere and Inner-Sphere Electron-Transfer Processes

and

Bergman

1998

J. Am. Chem. Soc.

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Treatment of isolable, paramagnetic Cp2Ta(μ-CH2)2CoCp (1, Cp = η5-C5H5) with aromatic disulfides RSSR affords diamagnetic monothiolate complexes Cp2Ta(μ-CH2)2Co(SR)Cp in quantitative yield. The structure of Cp2Ta(μ-CH2)2Co(SC6H3(CH3)2)Cp (2a) has been characterized by X-ray crystallography. The mechanism of this disulfide S−S bond cleavage reaction has been probed using kinetic, substituent effect, and solvent effect techniques. A Hammett σ/ρ substituent constant analysis yields a nonlinear correlation. In contrast, application of the E- and C-based dual-parameter substituent model gives a good fit of the data and demonstrates that the reaction is sensitive to both the electrostatic and the covalent characteristics of the entering disulfide. All substituents examined (excluding p-(trifluoromethyl)phenyl) exhibited a solvent effect consistent with a modest amount of charge separation in the transition state. The reaction of 1 with the strongly electron withdrawing substituted bis[p-(trifluoromethyl)phenyl] disulfide is much more sensitive to solvent polarity changes. As a comparison system expected to proceed via a limiting outer-sphere electron-transfer mechanism, the reaction of aromatic disulfides with the 19-electron complex cobaltocene (CoCp2, 3), which leads to salts [CoCp2][SR] (4), was investigated using methods parallel to those employed in the study of Ta/Co complex 1. In the cobaltocene system, the kinetic, solvent effect, and substituent effect data showed that the reaction is especially sensitive to the electrostatic character of the disulfide and relatively insensitive to its covalent character and steric bulk. The comparison of cobaltocene with Ta/Co complex 1 shows that the latter reacts with most diaryl disulfides (perhaps with the exception of p-CF3 compound 2f, which may be a borderline case) via a transition state with substantially more covalent character, and correspondingly less charge separation, than that involved in the outer-sphere reactions of Cp2Co.

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Section: Resultssupporting

confidence: 59%

Reaction of Organic Disulfides with Cobalt-Centered Metal Radicals. Use of the E- and C-Based Dual-Parameter Substituent Model and Quantitative Solvent Effect Analyses To Compare Outer-Sphere and Inner-Sphere Electron-Transfer Processes

and

Bergman

1998

J. Am. Chem. Soc.

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“…Each molecule of 1 behaves as an acceptor of two hydrogen bonds and as a donor of two others, as shown in Figure , thus forming a tridimensional network of connected molecules. These structural parameters together with the high CO stretching frequences ( ν CO = 2153 s, 2094 vs, and 2079 vs cm -1 , Nujol mull) indicate a strong degree of activation of the CO ligands toward nucleophilic attack and anticipate the acidic character of coordinated H 2 O …”

Section: Resultsmentioning

confidence: 91%

Aqueous Organometallic Chemistry of Ruthenium(II). Aquo Carbonyl Derivatives and Related Ethene Hydrocarboxylation in Fully Aqueous Solvent

et al. 1999

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A series of new water soluble and stable organometallic compounds is reported, and the peculiar role of water in their formation and stabilization is documented together with their catalytic properties in aqueous solution. The complex fac-Ru(OCOCF(3))(2)(CO)(3)(H(2)O) (1) constitutes the entry to a new type of aqueous organometallic chemistry. The substitution of trifluoroacetato ligands by H(2)O yields [fac-Ru(CO)(3)(H(2)O)(3)](2+) (2), isolated as the tetrafluoroborate derivative, the first structurally characterized complex bearing CO and H(2)O ligands only. In water, 2 undergoes nucleophilic attack by the solvent yielding [fac-Ru(COOH)(CO)(2)(H(2)O)(3)](+) (3), followed by CO(2) elimination to give [fac-RuH(CO)(2)(H(2)O)(3)](+) (4), a ruthenium(II) hydride devoid of group-15-donor coligands and stable toward strong acids. 4 inserts ethene in water to give [fac-Ru(C(2)H(5))(CO)(2)(H(2)O)(3)](+) (5), an exceptionally inert alkyl complex which inserts CO yielding [fac-Ru(C(O)C(2)H(5))(CO)(2)(H(2)O)(3)](+) (6). Attempts to isolate the mononuclear cationic acyl complex gave the tetranuclear Ru(4)(C(O)C(2)H(5))(4)(OH)(2)(CF(3)SO(3))(2)(CO)(8) (7). At 140 degrees C the mononuclear organometallic complexes become labile intermediates of a Reppe hydrocarboxylation of ethene in fully aqueous solvent.

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“…Unfortunately, this synthesis was not effective with more complex alcohols in our hands, giving only undesired side products. As such, we have developed a method informed by previous work from our group on the carbonylation of salen and salophen cobalt complexes and other related reports. − Both methods are quite general, tolerating a wide range of alcohols and ligand substitution patterns.…”

Section: Resultsmentioning

confidence: 99%

C–O Bond Cleavage of Alcohols via Visible Light Activation of Cobalt Alkoxycarbonyls

et al. 2019

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A strategy for the activation of C−O bonds in alcohols via a carbonylation−homolysis−decarboxylation process is described. Using readily available cobalt(II) porphyrin precursors, carbonylation of simple alcohols provides access to alkoxycarbonyl cobalt(III) complexes. Spectroscopic, crystallographic, and computational methods are used to provide structural details and an estimate for the Co−C bond dissociation energy of an alkoxycarbonylcobalt(III) complex of 39.8 kcal/mol for the first time. Visible light irradiation in the presence of the radical trapping agent TEMPO and a thiol reducing agent demonstrates the cleavage of the alcohol C−O bond under oxidative and reductive conditions, respectively. Addition of a stoichiometric reducing agent allows the use of a catalytic amount of hindered thiol for the reduction of a benzylic alcohol to the corresponding hydrocarbon.

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Extreme electrophilicity of coordinated carbon monoxide in [CpCo(dppe)CO]2+

Cited by 20 publications

References 0 publications

Reaction of Organic Disulfides with Cobalt-Centered Metal Radicals. Use of the E- and C-Based Dual-Parameter Substituent Model and Quantitative Solvent Effect Analyses To Compare Outer-Sphere and Inner-Sphere Electron-Transfer Processes

Reaction of Organic Disulfides with Cobalt-Centered Metal Radicals. Use of the E- and C-Based Dual-Parameter Substituent Model and Quantitative Solvent Effect Analyses To Compare Outer-Sphere and Inner-Sphere Electron-Transfer Processes

Aqueous Organometallic Chemistry of Ruthenium(II). Aquo Carbonyl Derivatives and Related Ethene Hydrocarboxylation in Fully Aqueous Solvent

C–O Bond Cleavage of Alcohols via Visible Light Activation of Cobalt Alkoxycarbonyls

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