Molybdate Dianion Traps Carbon Dioxide And Spits Out Formate

Inexpensive reduction of carbon dioxide to useful chemical reagents would help put a dent in solving Earth’s overabundance problem with the greenhouse gas. Inorganic chemists have turned to the task of designing catalysts for the job, but most of these systems so far involve complex ligands that are costly to synthesize. Taking a simple approach, Ioana Knopf and Christopher C. Cummins of Massachusetts Institute of Technology and their colleagues have identified a soluble molybdate system unencumbered by organic ligands for easy reduction of CO₂ (Chem. Sci. 2014, DOI: 10.1039/c4sc00132j). The team found that [MoO₄]^2– readily binds CO₂ at room temperature to irreversibly form a monocarbonate complex. With excess CO₂ the complex forms a dicarbonate species, which is the first structurally characterized transition-metal dicarbonate derived from CO₂. The researchers also found that the monocarbonate reacts with triethylsilane to produce formate, HCO₂^–, which is an important reagent in many chemical processes. “While many researchers spend considerable time designing elaborate ligand systems perfectly tuned both sterically and electronically for carbon dioxide fixation applications, this work represents a straightforward and beautifully simple approach to achieving the same sorts of transformations,” observes Christine M. Thomas of Brandeis University, whose group has developed CO₂-reduction catalysts.