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Vibrational Control of Covalency Effects Related to the Active Sites of Molybdenum Enzymes
- Source :
- J Am Chem Soc
- Publication Year :
- 2018
-
Abstract
- A multi-technique spectroscopic and theoretical study of the Cp(2)M(benzenedithiolato) (M=Ti,V,Mo; Cp = η(5)-C(5)H(5)) series provides deep insight into dithiolene electronic structure contributions to electron transfer reactivity and reduction potential modulation in pyranopterin molybdenum enzymes. This work explains the magnitude of the dithiolene folding distortion, and the concomitant changes in metal-ligand covalency, that are sensitive to electronic structure changes as a function of d-electron occupancy in the redox orbital. It is shown that the large fold angle differences correlate with covalency, and the fold angle distortion is due to a pseudo-Jahn-Teller (PJT) effect. The PJT effect in these and related transition metal dithiolene systems arise from the small energy differences between metal and sulfur valence molecular orbitals, which uniquely poise these systems for dramatic geometric and electronic structure changes as the oxidation state changes. Herein, we have used a combination of resonance Raman, magnetic circular dichroism, electron paramagnetic resonance, and UV photoelectron spectroscopies to explore the electronic states involved in the vibronic coupling mechanism. Comparison between the UV photoelectron spectroscopy (UPS) of the d(2) M=Mo complex and the resonance Raman spectra of the d(1) M=V complex reveals the power of this combined spectroscopic approach. Here, we observe that the UPS spectrum of Cp(2)Mo(bdt) contains an intriguing vibronic progession that is dominated by a “missing-mode” that is comprised of PJT active distortions. We discuss the relationship of the PJT distortions to facile electron transfer in molybdenum enzymes.
- Subjects :
- chemistry.chemical_element
02 engineering and technology
Electronic structure
010402 general chemistry
01 natural sciences
Biochemistry
Vibration
Catalysis
Article
Electron Transport
Electron transfer
Colloid and Surface Chemistry
Transition metal
Oxidation state
Catalytic Domain
Organometallic Compounds
Molecular orbital
Sulfhydryl Compounds
Molybdenum
Valence (chemistry)
Molecular Structure
Chemistry
General Chemistry
021001 nanoscience & nanotechnology
Electron transport chain
0104 chemical sciences
Crystallography
sense organs
0210 nano-technology
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- J Am Chem Soc
- Accession number :
- edsair.doi.dedup.....972b3c71ea531c475ce53d0c3ab16017