Photooxidation of Cobalt-Bound Thiolato Ligands

by | Aug 14, 2022 | Chemistry, Experiments


In this experiment(Photooxidation of Cobalt-Bound Thiolato Ligands), we will be studying the reaction between the complex bis(ethylenediamine) – (SO)(N, S-2-aminoethanethiol late) Cobalt Chloride (III) and singlet oxygen.


To determine how the oxidation rate of reaction between Cobalt and Thiolato complexes is affected by the solvent polarity.


1. In many biological systems, a similar Sulfur that is coordinated to transition metal is found.

2. Oxidation at the metal-sulfur site leads to the deactivation at the site.


1. Dimethylformamide (DMF)

2. Water

3. Laser Spectroscope

4. Origin 5.0 Computer Program


Step 1: Take polar and nonpolar solvents.

Step 2: Perform a similar reaction in each of the solvents.

Step 3: Record the reaction rates.

Step 4: Repeat the process in Dimethylformamide and in water.

Step 5: Using time-resolved laser spectroscopy, record the rate constant of each of the experiments.

Step 6: Record the decay rate of singleton oxygen at different concentrations of quencher. This will monitor the compound consumption of 102.

Step 7: With the help of an origin 5.0 computer program and Microsoft Excel, process the data of the experiment.


1. From our experiment, we observed that the quenching of Co(SO) Cystamine attends a slower rate in the polar solvents.

2. Nonpolar solvents increase the reaction rate of quenching Co(SO) Cystamine.


1. The nonpolar solvent showed a faster rate of reaction.

2. The reason behind increasing the 102 quenching rate on polar solvent is the added stabilisation.

3. The stabilisation was caused by the intramolecular hydrogen bond between sulfur and amino protons.


1. Handle the chemicals with care.

2. Make sure the computer works properly.

3. Record your data carefully.


In this experiment, we determined the effect of solvent polarity on the oxidation rate of the complexes of Cobalt – Thiolato.

Viva Questions With Answers

Q.1 What was the aim of your experiment?

ANS. We aimed to determine how the oxidation rate of reaction between Cobalt and Thiolato complexes is affected by the solvent polarity.

Q.2 Which solvent showed a faster rate of reaction?

ANS. Nonpolar solvent showed a faster rate of reaction.

Q.3 Which solvent displayed the slower quenching Co(SO) Cystamine rate?

ANS. Polar solvent showed a slower rate of quenching Co(SO) Cystamine?


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