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Dioxotungsten 1,2-benzenedithiolate complex stabilized by NH...S hydrogen bonds
Koji Baba1, Taka-aki Okamura, Hitoshi Yamamoto
1Chemical Analysis Research Center, National Institute for Agro-Environmental Sciences, Tsukuba, Ibaraki 305-8604, Japan.
Inorganic Chemistry
|September 27, 2006
Summary
Novel tungsten complexes with amide groups mimic tungsten enzymes. The NH...S hydrogen bond stabilizes oxo ligands and regulates oxygen transfer, crucial for enzyme function.
Area of Science:
- Inorganic Chemistry
- Bioinorganic Chemistry
- Structural Chemistry
Background:
- Tungsten enzymes play vital roles in biological redox reactions.
- Understanding the mechanisms of oxygen transfer in these enzymes is crucial.
- Tungsten complexes serve as valuable models for studying enzyme active sites.
Purpose of the Study:
- To design and synthesize novel dioxo-tungsten(VI) complexes with neighboring amide groups.
- To investigate the structural and electronic effects of NH...S hydrogen bonds in these complexes.
- To elucidate the role of these hydrogen bonds in mimicking tungsten enzyme activity.
Main Methods:
- Synthesis of novel dioxo-tungsten(VI) bis(1,2-benzenedithiolate) complexes.
- Infrared (IR) spectrometry to confirm hydrogen bonding.
- X-ray crystallographic analysis to determine complex structures.
- Electrochemical studies to evaluate redox potentials and reactivity.
Main Results:
- Successful synthesis of tungsten(VI) complexes with amide functionalities.
- Confirmation of NH...S hydrogen bonds, with stronger trans interactions.
- Observation of positive shifts in W(VI)/W(V) redox potentials due to NH...S bonds.
- Inhibition of reduction by benzoin or triphenylphosphine, indicating altered reactivity.
Conclusions:
- The NH...S hydrogen bond stabilizes oxo ligands via trans influence.
- This hydrogen bond plays a regulatory role in oxygen atom transfer processes.
- The designed complexes serve as effective models for understanding tungsten and molybdenum enzyme mechanisms.
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