Haloperoxidase activity of oxovanadium(V) thiobisphenolates

Area of Science:

• Inorganic Chemistry
• Organometallic Chemistry
• Catalysis

Background:

• Vanadium complexes are known for their diverse catalytic activities.
• Oxovanadium(V) complexes, in particular, have shown promise in oxidation reactions.
• The ligand 2,2'-thiobis(2,4-di-tert-butylphenolate) ((S)L(2-)) was utilized to synthesize a novel complex.

Purpose of the Study:

• To synthesize and characterize a novel oxovanadium(V) complex.
• To investigate the haloperoxidase activity of the synthesized complex.
• To elucidate the mechanism of thioether oxidation catalyzed by the complex.

Main Methods:

• Synthesis of the novel oxovanadium(V) complex (PPh(4))(2)[(S)LV(O)(μ(2)-O)(2)V(O)(S)L] (1) using the (S)L(2-) ligand.
• Investigation of the complex's activity with hydrogen peroxide (H(2)O(2)).
• Characterization of reaction products through independent synthesis and spectroscopic methods.

Main Results:

• The synthesized complex exhibited haloperoxidase activity.
• Oxidation of thioethers by the complex with H(2)O(2) yielded a mixture of five products, involving peroxide formation and thioether oxidation (sulfoxide and sulfone).
• Internal thioether oxidation proceeded via peroxide formation, while external thioether sulfoxidation required activation by protons or alkyl cations.

Conclusions:

• The novel oxovanadium(V) complex is an effective haloperoxidase catalyst.
• The mechanism of thioether oxidation is dependent on the location of the thioether group and reaction conditions.
• Using tert-butyl hydroperoxide (tBuOOH) instead of H(2)O(2) resulted in a highly active system for catalytic thioether sulfoxidation.