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An Iminosemiquinone-Coordinated Oxidovanadium(V) Complex: A Combined Experimental and Computational Study
Prasenjit Sarkar1, Manas Kumar Mondal1, Amrit Sarmah2
1Department of Chemistry, Indian Institute of Technology Guwahati (IITG) , Guwahati 781039, Assam, India.
Inorganic Chemistry
|June 29, 2017
Summary
This study details the synthesis and characterization of a novel oxidovanadium complex (1) featuring an iminosemiquinone radical anion. Spectroscopic and structural analyses confirm the V(V) oxidation state and radical character, offering insights into vanadium-ligand interactions.
Area of Science:
- Inorganic Chemistry
- Coordination Chemistry
- Vanadium Chemistry
Background:
- Amidophenolate ligands offer versatile coordination environments.
- Oxidovanadium complexes are of interest due to their diverse electronic properties and potential applications.
Purpose of the Study:
- To synthesize and characterize a novel mononuclear oxidovanadium complex.
- To investigate the electronic structure and redox behavior of the resulting complex.
Main Methods:
- Synthesis of the oxidovanadium complex using VOSO4·5H2O and H4Sar(AP/AP) ligand.
- X-ray crystal structure analysis for structural elucidation.
- Electron Paramagnetic Resonance (EPR) and UV-vis-near-IR (NIR) spectroscopy for electronic characterization.
- Density Functional Theory (DFT) studies for mechanistic insights.
- Cyclic voltammetry and spectroelectrochemistry for redox behavior analysis.
Main Results:
- A mononuclear octahedral oxidovanadium complex (1) was successfully synthesized.
- X-ray crystallography confirmed the V(V) oxidation state coordinated to an iminosemiquinone radical anion.
- EPR and magnetic moment measurements supported the presence of the radical species.
- Time-dependent studies and DFT calculations elucidated the formation mechanism involving a VO2+-iminoisemiquinone intermediate.
- UV-vis-NIR spectroscopy revealed charge-transfer transitions, including an intervalence ligand-to-ligand charge transfer at 1162 nm.
- Electrochemical studies indicated ligand-based oxidation and reduction processes.
Conclusions:
- The synthesized complex exhibits a stable V(V) oxidation state with an iminosemiquinone radical ligand.
- The reaction mechanism involves the initial formation of a diamagnetic VO2+-iminoisemiquinone species.
- The complex displays rich electronic transitions and ligand-based redox activity.
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