Calcium Pyrenide: A Room-Temperature Reagent for Stoichiometric Calciations and Reductive Ca2+ Intercalation Reactions
Wang, A., Storteboom, R.; Mollick, S. S.; Vasylevskyi, S.; Aubrey M. L.
J. Mater. Chem. A 2025, In Press.
Chemical reductive insertion of metal ions using metal arenes has attracted significant attention due to its capability to readily modulate the electronic and structural properties of host materials. Despite extensive studies involving various metal arenes, systems capable of enabling reductive insertion with Ca2+ species have not been determined. Here, we report the syn-thesis of calcium pyrenide and demonstrate its effectiveness in facilitating reductive insertion into host frameworks. The nominal composition in solution was determined to be spectroscopically consistent with previously reported alkali metal pyrenide solutions and, in DMF, found to participate in stoichiometric titrations of silver salts. Single crystals were grown from THF solutions and structurally characterized by X-ray diffraction. Signatures of the pyrenide’s radical anion were ob-served by EPR. The reduction potential was estimated by cyclic voltammetry of pyrene in a calcium perchlorate electrolyte solution where a reversible one-electron reduction wave was observed at –2.52 V vs Fc/Fc+. To demonstrate the utility of Ca(pyrene)₂ for screening materials capable of reversible calciation via reductive intercalation, the compounds, Cax(DMF)yMoS2 (0 < x < 0.34) were prepared from DMF solutions of calcium pyrenide and characterized by PXRD, SEM, ICP-OES, and TGA.