Kinetics and Mechanism of Aquation and Formation Reactions of Carbonato Complexes: Rate of Decarboxylation of the Bis(carbonato)bis (pyridine)cobaltate(III) complex ion in Aqueous Pyridine Buffer Solutions

Material Information

Title:
Kinetics and Mechanism of Aquation and Formation Reactions of Carbonato Complexes: Rate of Decarboxylation of the Bis(carbonato)bis (pyridine)cobaltate(III) complex ion in Aqueous Pyridine Buffer Solutions
Series Title:
Student Symposium 2014
Creator:
Lubin, Devin
Ghosh, Phalguni
Middlesex College, Department of Natural Sciences
Place of Publication:
Edison, NJ
Publisher:
Middlesex College
Publication Date:

Notes

Abstract:
The synthesis of the metal coordination was first prepared by dissolving Na3[Co(CO3)3]•3H2O in aqueous sodium bicarbonate. The reaction of these green solutions with excess pyridine was found to produce a pale blue, moisture-sensitive hydrate and then as the purple crystalline salt K[Co(py)2(CO3)2] •2H₂O. The behaviors of these product salts in water, ethanol, and aqueous acid wereinvestigated. The kinetics of the title reaction was monitored by conventional spectrophotometry at 525 and 635 nm over the following concentration ranges: [Co(III)] = (5.7-1 1.4) X 10-4 M, [H+] = (0.15-9.52) X 10-9 M, [HCO3-] = 0.14-0.865 Mand [py] = (1.2-29.8) X 10-2 M at 25 ⁰C and ionic strength 1.0 M (NaHCO3, NaCl04). The rate law was found to be pseudo first order as the green solution turns to a purple solution after adding certain molar concentrations of pyridine. Spectral scanning during the course of the reaction showed that the rate-determining steps involve the formation of the first cobalt(II1)-pyridine bond, followed by rapid addition of pyridine to form thebis(carbonato)bis(pyridine)cobaltate(III) product.Another aspect that was studied throughout this experiment was the decomposition of the cobalt complex in nitric acid. Another result that was observed was that the decomposition of the carbonate ligands forms CO2. The rate of decomposition of the carbonate ligands was also found to be pseudo first order.
Preferred Citation:
Lubin, D. Kinetics and Mechanism of Aquation and Formation Reactions of Carbonato Complexes: Rate of Decarboxylation of the Bis(Carbonato)Bis (Pyridine)Cobaltate(III) Complex Ion in Aqueous Pyridine Buffer Solutions; MCC Student Symposium 2014; Middlesex County College: Edison, NJ, 2014. https://digital.middlesexcc.edu/l/AA00002434/00001

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Middlesex County College Institution
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Middlesex County College Institution
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