Clean and Efficient Transformation of CO<sub>2</sub> to Isocyanic Acid: The Important Role of Triatomic Cation ScNH<sup>+</sup>

Achieving the desired selective transformations of the very stable CO<sub>2</sub> into useful chemicals is quite important for the development of economically and environmentally sustainable synthetic methods. Herein, mass spectrometric experiments and quantum-chemical calculations have identified that ScNH<sup>+</sup> reacts quite efficiently with CO<sub>2</sub> under thermal collision conditions to exclusively yield ScO<sup>+</sup> and isocyanic acid (HNCO). This is a novel reaction type in CO<sub>2</sub> activation reactions mediated by gas-phase ions. In this reaction, the CN double bond has also been formed for the first time in the gas phase. The mechanism of “migratory insertion” is proposed. Coupled with the previously reported reaction of Sc<sup>+</sup> with NH<sub>3</sub>, HNCO can be synthesized under mild conditions from NH<sub>3</sub> and CO<sub>2</sub> in quite simple reactions. The mechanistic information gained in this gas-phase model reaction can offer fundamental insights relevant to corresponding processes and further guide on how to design brand new catalysts.