Nitrate and Perchlorate Reduction by a Dinuclear Mo(V) Complex.

Nitrate (NO) and perchlorate (ClO) are persistent groundwater contaminants due to their high stability and solubility. Microorganisms reduce these anions using molybdenum-containing enzymes such as nitrate reductases and perchlorate reductases. Reported here is a bioinspired dinuclear Mo(V) catalyst, [MoO(L)(THF)] (), where L = 5-Bromo-2-hydroxybenzaldehyde thiosemicarbazone, and its reactivity with nitrate and perchlorate. Compound was previously speculated to be an inactive byproduct formed when its monomeric Mo(VI) analog, [MoO(L)(MeOH)] (), catalyzes an oxygen atom transfer (OAT) between dimethyl sulfoxide (DMSO) and PPh. This work reports the synthesis, spectroscopic and crystallographic characterizations, and catalytic reactivity of . Contrary to earlier expectations, catalyzes OAT from DMSO to PPh, and also reduces nitrate and perchlorate, making it one of the few homogeneous molybdenum catalysts known to do so. With nitrate, performs two OAT steps per NO to generate and NO, likely via nitrite and nitroxy intermediates. With perchlorate, catalyzes four OAT events per ClO, yielding Cl and . The effect of Sc as a cocatalyst was also investigated; it significantly enhances the rates for perchlorate reduction but has minimal impact on nitrate reduction.