Dinitrogen (N2), carbon monoxide (CO), and carbon dioxide (CO2) are all abundant and readily available chemical feedstocks. The functionalization of N2 with CO and CO2 is of considerable interest and importance, but remains a formidable challenge, owing to their high thermodynamic and kinetic stability. Here, we report an unprecedented cascade coupling of N2, CO, CO2, and alkynes within a dititanium framework. Sequential reactions of N2, CO, alkynes (R1C≡CR2), and CO2 with a dititanium tetrahydride complex at room temperature selectively afforded the corresponding four-component coupling products, O2CN2CH2C(R2)CR14- (R1 = H, R2 = Ph, Cy, or COOMe; R1 = R2 = Me). Combined experimental and computational studies reveal that coordination of an alkyne to one Ti center of a dititanium dinitrogen/oxymethylene complex, formed via N2 and CO activation, induces N-C bond formation between the dinitrogen and oxymethylene moieties with simultaneous deoxygenation, leading to the formation of diazomethane species NNCH22- at the other Ti center. Subsequent CO2 incorporation at the terminal nitrogen of the diazomethane unit triggers the addition of the CH2 unit to the coordinated alkyne, thereby generating an allylhydrazinocarboxylate species as the final four-component coupling product. This work highlights the unique synergistic reactivity of multinuclear titanium complexes toward cooperative activation and incorporation of N2, CO, and CO2, offering a new strategy for the valorization of small inert molecules at the molecular level.
Zhou et al. (2026) studied this question.