Stopped‐flow Spectrophotometric Study on the Reaction between Carbon Dioxide and [Co(NH3)4(H2O)2]3+ Ion in Aqueous Solution

Jacewicz, Dagmara; Chylewska, Agnieszka; Dąbrowska, Aleksandra; Chmurzyński, Lech

doi:10.1002/zaac.200700174

Cited by 3 publications

(4 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Each reported rate constant is an average of at least 7 runs with a standard deviation within 2%. To evaluate activation parameters for each complex, variable temperature measurements were performed at a wavelength that showed most clearly the growth of the intermediate followed by its decay; linear Eyring plots (k 2 0 = [(k B T/h) exp(ÀΔG q /RT) with ΔG q = ΔH q À TΔS q ) were obtained for the fast (direct reaction with CO 2 ) and slow processes of several complexes (2,3,4) and for the fast process of the remaining complexes (5, 6) which did not exhibit sufficient absorbance changes for evaluation of the slow process.…”

Section: T H I S C O N T E N T Imentioning

confidence: 99%

“…In the present context, carbon dioxide fixation is a recognized reaction type by which CO 2 is converted to bicarbonate or carbonate by reaction with metal-bound hydroxo groups. With trivalent metals, the reactions frequently employ terminal M III –OH groups of chromium and cobalt and afford η 1 -bicarbonate species as the initial product. − With divalent metals, the reactions proceed with terminal or bridging hydroxo ligation and yield products that often contain carbonate bound in binuclear or trinuclear bridging modes. Numerous examples of these reactions are found with complexes of Co II , Ni II , Cu II , and Zn II in particular. − In the case of Ni II , nearly all reactions utilize bridged Ni-(OH) 1,2 -Ni units and lead to products in which carbonate is stabilized by η 2 - or η 3 -coordination to two Ni II atoms. ,− …”

Section: Introductionmentioning

confidence: 99%

“…The structures of the seven compounds in Tables 1 and 2 were determined; for brevity, compounds are referred to by their anion number. Diffraction-quality crystals were obtained from the following solvents: DMF/ether (2,8,9,12), DMF/ ethyl acetate (3), DMF/toluene/ether (4,5). Diffraction data were collected on a Bruker CCD area detector diffractometer equipped with an Oxford 700 low-temperature apparatus.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Fast Carbon Dioxide Fixation by 2,6-Pyridinedicarboxamidato-nickel(II)-hydroxide Complexes: Influence of Changes in Reactive Site Environment on Reaction Rates

et al. 2011

View full text Add to dashboard Cite

The planar complexes [Ni(II)(pyN(2)(R2))(OH)](-), containing a terminal hydroxo group, are readily prepared from N,N'-(2,6-C(6)H(3)R(2))-2,6-pyridinedicarboxamidate(2-) tridentate pincer ligands (R(4)N)(OH), and Ni(OTf)(2). These complexes react cleanly and completely with carbon dioxide in DMF solution in a process of CO(2) fixation with formation of the bicarbonate product complexes [Ni(II)(pyN(2)(R2))(HCO(3))](-) having η(1)-OCO(2)H ligation. Fixation reactions follow second-order kinetics (rate = k(2)'[Ni(II)-OH][CO(2)]) with negative activation entropies (-17 to -28 eu). Reactions were monitored by growth and decay of metal-to-ligand charge-transfer (MLCT) bands at 350-450 nm. The rate order R = Me > macro > Et > Pr(i) > Bu(i) > Ph at 298 K (macro = macrocylic pincer ligand) reflects increasing steric hindrance at the reactive site. The inherent highly reactive nature of these complexes follows from k(2)' ≈ 10(6) M(-1) s(-1) for the R = Me system that is attenuated by only 100-fold in the R = Ph complex. A reaction mechanism is proposed based on computation of the enthalpic reaction profile for the R = Pr(i) system by DFT methods. The R = Et, Pr(i), and Bu(i) systems display biphasic kinetics in which the initial fast process is followed by a slower first order process currently of uncertain origin.

show abstract

Section: T H I S C O N T E N T Imentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Fast Carbon Dioxide Fixation by 2,6-Pyridinedicarboxamidato-nickel(II)-hydroxide Complexes: Influence of Changes in Reactive Site Environment on Reaction Rates

et al. 2011

View full text Add to dashboard Cite

show abstract

“…In order to confirm this conclusion we decided to study the reaction opposite to acid hydrolysis of [Co(NH 3 ) 4 CO 3 ] ϩ cation, which is the reaction of carbon dioxide uptake by [Co(NH 3 ) 4 (OH 2 ) 2 ] 3ϩ . We have already proposed the mechanism of this reaction [27]. On the basis of UV-Vis spectrum obtained from SVD analysis, we concluded that these two reactions are opposite to each other.…”

Section: Proposed Mechanism For Acid Hydrolysis Of [Co(nh 3 ) 4 Co 3 mentioning

confidence: 77%

Kinetics and Mechanism of Formation and Acid–Catalyzed Decomposition of the [Co(NH₃)₄CO₃]⁺ Complex Cation in Aqueous Solution

Jacewicz

Chylewska

Dąbrowska

et al. 2007

Zeitschrift anorg allge chemie

Self Cite

View full text Add to dashboard Cite

Astract. It has been found that the kinetics of acid-catalyzed hydrolysis of the [Co(NH 3 ) 4 CO 3 ] ϩ cation follows the rate law Ϫd ln HClO 4 ] < 2.7M and I ϭ 1.0M (NaClO 4 ). The reaction course consists of a rapid pre-equlibrium protonation followed by a rate determining ring opening process and the subsequent fast release of monodentate carbonato ligand. The changes of the absorbance for the acidic aqueous solution of the [Co(NH 3 ) 4 CO 3 ] ϩ complex ion proceeded at relevant wavelength in the UV-Vis region and time 137 course of these changes were analysed according to a programme "Glint" for the consecutive first Ϫ order reaction with two experimental rate constants k fast and k slow . Finally, the aquation mechanism has been proposed and the effect of ligand coordination mode (bidentate carbonato anion) on complex reactivity has been discussed.

show abstract

Kinetics and mechanistic analysis of an extremely rapid carbon dioxide fixation reaction

Huang

Makhlynets

Tan

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

124

101

View full text Add to dashboard Cite

Carbon dioxide may react with free or metal-bound hydroxide to afford products containing bicarbonate or carbonate, often captured as ligands bridging two or three metal sites. We report the kinetics and probable mechanism of an extremely rapid fixation reaction mediated by a planar nickel complex ½Ni II ðNNNÞðOHÞ 1− containing a tridentate 2,6-pyridinedicarboxamidate pincer ligand and a terminal hydroxide ligand. The minimal generalized reaction is M-OH þ CO 2 → M-OCO 2 H; with variant M, previous rate constants are ≲10 3 M −1 s −1 in aqueous solution. For the present bimolecular reaction, the (extrapolated) rate constant is 9.5 × 10 5 M −1 s −1 in N, N′-dimethylformamide at 298 K, a value within the range of k cat ∕K M ≈10 5 -10 8 M −1 s −1 for carbonic anhydrase, the most efficient catalyst of CO 2 fixation reactions. The enthalpy profile of the fixation reaction was calculated by density functional theory. The initial event is the formation of a weak precursor complex between the Ni-OH group and CO 2 , followed by insertion of a CO 2 oxygen atom into the Ni-OH bond to generate a four center Niðη 2 -OCO 2 HÞ transition state similar to that at the zinc site in carbonic anhydrase. Thereafter, the Ni-OH bond detaches to afford the Niðη 1 -OCO 2 HÞ fragment, after which the molecule passes through a second, lower energy transition state as the bicarbonate ligand rearranges to a conformation very similar to that in the crystalline product. Theoretical values of metric parameters and activation enthalpy are in good agreement with experimental values [ΔH ‡ ¼ 3.2ð5Þ kcal∕mol].nickel hydroxide | carbon dioxide-bicarbonate conversion | reaction mechanism R ecent research in this laboratory has been directed toward the attainment of synthetic analogues of the NiFe 3 S 4 active site of the enzyme carbon monoxide dehydrogenase (1, 2), which catalyzes the interconversion reactionIn the course of this work, we have prepared binuclear Ni II ∕Fe II bridged species with the intention of simulating the Ni…Fe component of the enzyme site that is the locus of substrate binding, activation, and product release (3). The nickel site in the binuclear species has been prepared separately in the form of the planar hydroxide complex ½NiðpyN 2 Me2 ÞðOHÞ 1− containing a N,N′-2,6-dimethylphenyl-2,6-pyridinedicarboxamidate dianion. Whereas bridging hydroxide ligation is common, terminal binding is not and in general is stabilized in divalent metal complexes by hydrogen bonding or by steric shielding, as is the case here. As reported recently (3), exposure of a solution of ½NiðpyN 2 Me2 ÞðOHÞ 1− to the atmosphere results in an instantaneous color change from red to red-orange. This results in the fixation of CO 2 as the bicarbonate complex ½NiðpyN 2 Me2 ÞðHCO 3 Þ 1− accompanied by the spectral changes in Fig. 1. Several features of the CO 2 fixation reaction 1 are noteworthy. The reactant is a terminal hydroxide species affording a unidentate bicarbonate (η 1 -OCO 2 H) product. Far more common is the reaction of bridged M II 2 ðμ-OHÞ 1;2 pr...

show abstract

Stopped‐flow Spectrophotometric Study on the Reaction between Carbon Dioxide and [Co(NH₃)₄(H₂O)₂]³⁺ Ion in Aqueous Solution

Cited by 3 publications

References 22 publications

Fast Carbon Dioxide Fixation by 2,6-Pyridinedicarboxamidato-nickel(II)-hydroxide Complexes: Influence of Changes in Reactive Site Environment on Reaction Rates

Fast Carbon Dioxide Fixation by 2,6-Pyridinedicarboxamidato-nickel(II)-hydroxide Complexes: Influence of Changes in Reactive Site Environment on Reaction Rates

Kinetics and Mechanism of Formation and Acid–Catalyzed Decomposition of the [Co(NH₃)₄CO₃]⁺ Complex Cation in Aqueous Solution

Kinetics and mechanistic analysis of an extremely rapid carbon dioxide fixation reaction

Contact Info

Product

Resources

About

Stopped‐flow Spectrophotometric Study on the Reaction between Carbon Dioxide and [Co(NH3)4(H2O)2]3+ Ion in Aqueous Solution

Cited by 3 publications

References 22 publications

Fast Carbon Dioxide Fixation by 2,6-Pyridinedicarboxamidato-nickel(II)-hydroxide Complexes: Influence of Changes in Reactive Site Environment on Reaction Rates

Fast Carbon Dioxide Fixation by 2,6-Pyridinedicarboxamidato-nickel(II)-hydroxide Complexes: Influence of Changes in Reactive Site Environment on Reaction Rates

Kinetics and Mechanism of Formation and Acid–Catalyzed Decomposition of the [Co(NH3)4CO3]+ Complex Cation in Aqueous Solution

Kinetics and mechanistic analysis of an extremely rapid carbon dioxide fixation reaction

Contact Info

Product

Resources

About

Stopped‐flow Spectrophotometric Study on the Reaction between Carbon Dioxide and [Co(NH₃)₄(H₂O)₂]³⁺ Ion in Aqueous Solution

Kinetics and Mechanism of Formation and Acid–Catalyzed Decomposition of the [Co(NH₃)₄CO₃]⁺ Complex Cation in Aqueous Solution