Stereochemistry and reaction rates of anionopentaamine complexes of cobalt(III) and chromium(III)

House, Donald A.

doi:10.1016/s0010-8545(00)80388-4

Cited by 100 publications

(13 citation statements)

References 398 publications

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“…4 and 5)[54], may be responsible for the different arrangements of (Ge 2 S 6 ) 4À anions in the crystal structures of 4a and 4b. The shortest MnÁÁÁMn and NiÁÁÁNi distances are 8.264 and 8.659 Å, respectively.…”

mentioning

confidence: 99%

Five dimeric thiogermanates with transition metal complexes of multidentate chelating amines: Syntheses, structures, magnetism and photoluminescence

Liu

Guo

Wang

et al. 2010

Journal of Molecular Structure

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mentioning

confidence: 99%

Five dimeric thiogermanates with transition metal complexes of multidentate chelating amines: Syntheses, structures, magnetism and photoluminescence

Liu

Guo

Wang

et al. 2010

Journal of Molecular Structure

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“…This area has been reviewed by House (10). The results most pertinent to the present findings are measurements of the rates of aquation, of base hydrolysis, and of Hg2+ assisted aquation of isomers of Co(en)(dien)X2+ where X-is a halide ion (10). For all three reactions a difference in rate of around three was found for the two isomers corresponding to the peroxy complexes discussed above.…”

Section: Methodsmentioning

confidence: 60%

The dependence of the rates of reduction of cobalt(III)-μ-peroxo complexes on isomeric structure

Au-Yeung¹,

Eaton²

1984

Can. J. Chem.

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. Can. J. Chem. 62, 2 127 (1 984). The reaction of ~-peroxybis(ethylenediamine)bis(diethylenetriamine)~~balt(III) with ferrous ions has been studied by stopped flow spectrophotometry and by 5yCo nmr. Two separate initial reduction steps with second order rate constants of 1.0: and 3.04 M-' s-I, respectively, can be discerned in the stopped flow experiments. These two rate constants are assigned to inner sphere reduction of the aef,cd.b and edf,ac.b isomers of the peroxy cobalt complex, respectively. The different isomers can be distinguished by 5'Co nrnr. If there is insufficient Fe" present to completely reduce the complex to Co(I1) and water, the change in the relative intensities of the 5'Co resonances after partial reduction shows that one isomer has reacted faster than the other. The 5'Co resonances can be assigned to the different isomers on the basis of a point charge model for the chemical shifts and line widths. Based on this model it is concluded that the isomer with the central NH of the diethylenetriamine trans to the peroxy ligand reacts faster. This result is compared to literature reports on the relative rates of substitution of isomers of Co (II1) On peut distinguer les differents isomkres _mice j. la rmn du "Co. Si la quantiti de Fe" presente n'est pas suffisante pour reduire completement le complexe en Co(I1) et en eau. le changement des intensites relatives de la resonance du 5yCo, apres la reduction partielle. montre qu'un isomirre reagit plus vite que l'autre. On peut attribuer les resonances du 5 y~o aux diffirents isomeres en se basant sur un modele de charge ponctuelle pour les deplacements chimiques et les largeurs des pics. En se basant sur ce modkle. on conclut que I'isomkre qui reagit le plus rapidement est celui qui porte le NH central de la diethylenetriamine en position trans par rapport aux ligand epoxy. On compare ce resultat ceux repertories dans la litterature pour les vitesses relatives de substitution des isomkres des complexes du Co(ll1) avec des ligands d'ethylenediamine et de diethylknetriamine.[Traduit par le journal] Introduction A series of compounds formed by the reaction of molecular oxygen with solutions containing Co(I1) ions has been extensively studied (1 -3). The complexes with the stoichiometry of two Co atoms to one oxygen molecule are correctly formulated as peroxy compounds containing Co in the 3+ oxidation state. One electron oxidation of these compounds leads to the corresponding superoxy complexes. Complete reduction of the peroxo compounds to Co(I1) and water requires four equivalents of a one electron reducing agent. There have been a number of studies of the mechanisms of these reductions motivated by the analogies with reactions of biological importance (4-6). It seems well established (4) that the first step in the reduction of the superoxo complexes is an outer sphere electron transfer and that reduction of the peroxy compounds is initiated by an inner sphere electron transfer. Subsequent steps are less well understood.McLendon and Martell (5) have ...

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“…As for the aquation, the activation enthalpy and entropy were determined from plots of In(k/T) vs. 1/T. Due to the ionic strength effects on the rate of the base hydrolysis reactions [1], the rate constants, as well as the activation parameters for the Brought to you by | Purdue University Libraries Authenticated Download Date | 6/13/15 2:33 PM base hydrolysis of [Co(NH3)5(OS03)] + ion, were determined for comparison. However, the rate of this reaction is slow enough to be investigated by conventional methods.…”

Section: Base Hydrolysismentioning

confidence: 99%

“…Studies of hydrolysis reactions of amine complex of cobalt(III) have an extensive history, and this research has been widely reviewed [1][2][3]. Despite this activity, mechanistic aspects still need to be resolved.…”

Section: Introductionmentioning

confidence: 99%

Aquation and Base Hydrolysis of trans-Tetraammine(methylamine)sulfatocobalt(III) Complex Ion

Benzo¹,

Capparelll²,

Martire³

et al. 2000

BioInorganic Reaction Mechanisms

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The kinetics of aquation and base hydrolysis reactions of fmns-[Co(NH3 )4(NH2CH3)(OSC>3)r have been studied. In acid solution the aquation rate, Raq, follows the equation Raq/[complex] = ks + fcc[H + ], at constant ionic strenght μ = 1.0 Μ. The activation parameters are ΔΗ* = 88.8 kj mol 1 , AS* =-50.5 JK^mor 1 , ΔΗ* = 96.7 kj mol 1 and AS* =-23 JK 1 mol 1 . The rate constants at 25°C are ks = 4.15 χ 10 V 1 and fcc = 4.52M V 1 . The rate of base hydrolysis, Roh, follows the equation RoH^com-plex] = /C0H [OH -]. The activation parameters are Δ/ί£Η =74.9kJmol 1 and AS^H = 2JK^mol 1 and the rate constant is JCOH = 0.58M J S 1 at 25°C and μ, = 0.15 Μ. The stereochemistry of the hidroxo product has been determined (cis-[Co(NH3)4(NH2CH3)-(OH)] 2+ =9%). The results are discussed in the light of the reaction mechanisms proposed so far.

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Stereochemistry and reaction rates of anionopentaamine complexes of cobalt(III) and chromium(III)

Cited by 100 publications

References 398 publications

Five dimeric thiogermanates with transition metal complexes of multidentate chelating amines: Syntheses, structures, magnetism and photoluminescence

Five dimeric thiogermanates with transition metal complexes of multidentate chelating amines: Syntheses, structures, magnetism and photoluminescence

The dependence of the rates of reduction of cobalt(III)-μ-peroxo complexes on isomeric structure

Aquation and Base Hydrolysis of trans-Tetraammine(methylamine)sulfatocobalt(III) Complex Ion

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