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Nitrate and Perchlorate Reduction by a Dinuclear Mo(V) Complex.
Shui Ling Chen1, L Taylor Elrod1, Stephen Marriott1
1Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States.
Inorganic Chemistry
|August 29, 2025
Summary
A novel dinuclear molybdenum catalyst efficiently reduces persistent groundwater contaminants, nitrate and perchlorate. This bioinspired catalyst demonstrates significant potential for environmental remediation applications.
Area of Science:
- Coordination Chemistry
- Environmental Chemistry
- Catalysis
Background:
- Nitrate and perchlorate are stable, soluble groundwater contaminants.
- Microbial reduction of these anions involves molybdenum-containing enzymes.
- A previously studied monomeric Mo(VI) complex, [Mo^VI O_2(L^Br)(MeOH)] (1), was thought to form an inactive dinuclear Mo(V) byproduct, [Mo_2O_3(L^Br)_2(THF)_2] (2).
Purpose of the Study:
- To synthesize and characterize the dinuclear Mo(V) complex 2.
- To investigate the catalytic reactivity of complex 2 with nitrate and perchlorate.
- To explore the effect of scandium(III) as a cocatalyst in these reactions.
Main Methods:
- Synthesis and full characterization (spectroscopic, crystallographic) of the dinuclear Mo(V) complex 2.
- Catalytic studies involving oxygen atom transfer (OAT) reactions with DMSO and PPh3.
- Evaluation of nitrate and perchlorate reduction catalysis by complex 2, with and without Sc^3+.
Main Results:
- The dinuclear Mo(V) complex 2 was successfully synthesized and characterized.
- Contrary to expectations, complex 2 is catalytically active, mediating OAT from DMSO to PPh3.
- Complex 2 effectively reduces both nitrate (two OAT steps per NO3-) and perchlorate (four OAT steps per ClO4-), yielding N2O and Cl-, respectively.
- Scandium(III) significantly accelerates perchlorate reduction but has a minor effect on nitrate reduction.
Conclusions:
- The dinuclear Mo(V) complex 2 is a versatile homogeneous catalyst for oxygen atom transfer reactions.
- Complex 2 demonstrates significant potential for the reductive remediation of nitrate and perchlorate groundwater contaminants.
- The catalytic activity of complex 2 challenges previous assumptions about its role as an inactive byproduct.
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