Mechanism and steric course of octahedral aquation. XIII. Kinetics and steric course of the acid and base hydrolysis of cis- and trans-dichloro(1,4,8,11-tetraazacyclotetradecane)chromium(III) cations

Campi, EM; Ferguson, J.; Tobe, M. L.

doi:10.1021/ic50090a001

Cited by 34 publications

(13 citation statements)

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“…This evidence suggests that the ternary species Fe(III)-CYCLAM-MO might not be highly stable and could undergo aquation over time, releasing MO. In fact, a similar behavior showing spectral profiles with various isosbestic points has been reported for trans-chloro CYCLAM metal complexes, being ascribed to aquation processes [46,47]. In any case, our spectroscopic evidence showed no substantial MO oxidative degradation during the catalytic experiments with Fe(III)-CYCLAM.…”

Section: Fe(iii) Complexes Catalytic Performancesupporting

confidence: 87%

Fe(III)-Complex-Imprinted Polymers for the Green Oxidative Degradation of the Methyl Orange Dye Pollutant

et al. 2021

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One of the biggest problems worldwide is the pollution of natural water bodies by dyes coming from effluents used in the textile industry. In the quest for novel effluent treatment alternatives, the aim of this work was to immobilize Fe(III) complexes in molecularly imprinted polymers (MIPs) to produce efficient Fenton-like heterogeneous catalysts for the green oxidative degradation of the methyl orange (MO) dye pollutant. Different metal complexes bearing commercial and low-cost ligands were assayed and their catalytic activity levels towards the discoloration of MO by H2O2 were assessed. The best candidates were Fe(III)-BMPA (BMPA = di-(2-picolyl)amine) and Fe(III)-NTP (NTP = 3,3′,3″-nitrilotripropionic acid), displaying above 70% MO degradation in 3 h. Fe(III)-BMPA caused the oxidative degradation through two first-order stages, related to the formation of BMPA-Fe-OOH and the generation of reactive oxygen species. Only the first of these stages was detected for Fe(III)-NTP. Both complexes were then employed to imprint catalytic cavities into MIPs. The polymers showed catalytic profiles that were highly dependent on the crosslinking agent employed, with N,N-methylenebisacrylamide (MBAA) being the crosslinker that rendered polymers with optimal oxidative performance (>95% conversion). The obtained ion-imprinted polymers constitute cheap and robust solid matrices, with the potential to be coupled to dye-containing effluent treatment systems with synchronous H2O2 injection.

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Section: Fe(iii) Complexes Catalytic Performancesupporting

confidence: 87%

Fe(III)-Complex-Imprinted Polymers for the Green Oxidative Degradation of the Methyl Orange Dye Pollutant

et al. 2021

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“…For a series of reactions which proceed by the same mechanism, there should be a correlation between the change in AG* and the change in AG°, which are proportional to the log of the rate constants for the forward reactions and the log of the equilibrium constants for the overall reactions, respectively. The equilibrium constants listed in Table V are for the anation re-actions8•16 Cr3 + + X-^=5s CrX2 + (Xox) (7) Hg2+ + X-7^= HgX+ (XHEx) (8) and the overall reaction CrX2+ + Hg2+ Cr3+ + HgX+ (K = Xh8x/Ac,x) (9) Literature values of Kcrx were extrapolated to 0.50 M ionic strength using the relationship derived by Swaddle and Gaustalla8 for the ionic strength dependence of the formation reaction (eq7) of Crl2 .01 " &an is the second-order rate constant for the acid-independent path in the formation of CrX2+ from Cr3+ and HgX+ (&a" = ko/K). 6 J. N. Armor and A. Haim, J. Amer.…”

Section: Discussionmentioning

confidence: 99%

Linear free energy relations in the mercury(II)-catalyzed aquation of halopentaaquochromium(III) complexes

Birk¹,

Ingerman²

1972

Inorg. Chem.

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“…The base hydrolysis of these trans isomers studied in buffer solutions was a fast, two stage reaction. Campi et al (17) have studied the base hydrolysis of transand cis-[Cr(cyclam)Cl,]+ complexes. They reported that a typical second order rate law was observed.…”

Section: Comparisonsmentioning

confidence: 99%

Kinetics and mechanism of the base hydrolysis of some trans-dihalogeno(cyclam)rhodium(III) complexes

Chung¹,

Bounsall²

1978

Can. J. Chem.

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. Can. J. Chem. 56,709(1978). The base hydrolysis of iror~s-[Rh(cyclani)XY] + (cyclan~ = 1,4,8,1 l-tetraazacyclotetradecane; X-and Y-= CI-, Br-, and I-) are studied in aqueous solution over a range of OHconcentration and at various temperatures. The kinetics are done at a constant ionic strength with excess of [OH-] (smallest ratio = 200: 1) so that p s e~~d o first order rate constants are obtained for all the determinations. All of the reactions proceed with complete retention of configuration, and no rrotts-to-cis isomerization is found. The kinetic rrntls effect of these complexes is I -> Br-> C1-on a rate basis, but based on AHq, I -> Br-= CI-. These Rh(II1) con~plexes exhibit kinetic class (b) character on the AHq basis. The results of the rate constants and the activation parameters are interpreted in terms of an SNICB mechanism. The behavior of these complexes is compared to that of the other analogous complexes. IntroductionThe kinetics of substitution reactions in octahedral six-coordinate transition metal complexes have been extensively investigated and reviewed (1). In general, these octahedral complexes undergo acid hydrolysis and substitution reactions with other ligands at rates which are of the same magnitude and which are independent of the nature and concentration of the incoming group. Only first order kinetics are observed. In marked contrast, the hydroxide ion exhibits distinctly different behavior. Its substitution (base hydrolysis) takes place at a rate that is many orders of magnitude faster than other substitution reactions of these complexes. The base hydrolysis reactions are second order overall, first order with respect to the concentration of the complex and the hydroxide ion.The rate of base hydrolyses of some octahedral

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Mechanism and steric course of octahedral aquation. XIII. Kinetics and steric course of the acid and base hydrolysis of cis- and trans-dichloro(1,4,8,11-tetraazacyclotetradecane)chromium(III) cations

Cited by 34 publications

References 1 publication

Fe(III)-Complex-Imprinted Polymers for the Green Oxidative Degradation of the Methyl Orange Dye Pollutant

Fe(III)-Complex-Imprinted Polymers for the Green Oxidative Degradation of the Methyl Orange Dye Pollutant

Linear free energy relations in the mercury(II)-catalyzed aquation of halopentaaquochromium(III) complexes

Kinetics and mechanism of the base hydrolysis of some trans-dihalogeno(cyclam)rhodium(III) complexes

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