Room Temperature O Transfer from N2O to CO Mediated by Nearest Cd(I) Ions in MFI Zeolite Cavity
Akira Oda, Takahiro Ohkubo, Yasushige Kuroda
The dominant oxidation state of cadmium is +II. Although extensive investigations into the +II oxidation state have been carried out, the chemistry of CdI is largely underdeveloped. Here, we report on a new functionality of cadmium created by zeolite lattice: room temperature O transfer from N2O to CO mediated by the nearest monovalent cadmium ions in MFI zeolite. Thermal activation of CdII ion-exchanged MFI zeolite in vacuo affords the diamagnetic [CdI–CdI]2+ species with a short CdI–CdI σ bond (2.67 Å). This species generates two CdI• sites under UV irradiation through homolytic cleavage of the CdI–CdI σ bond, and thus-formed nearest CdI• sites abstract an O atom from N2O to generate the [CdII–O–CdII]2+ core. This bridging atomic oxygen species is transferred to CO at room temperature, through which CO oxidation and regeneration of the CdI–CdI σ bond then proceeds. This is the first example pertaining to the reversible redox reactivity of the nearest monovalent cadmium ions toward stable small molecules. In situ spectroscopic characterization captured all the intermediates in the reaction processes, and these data allowed us to calibrate the density-functional-theory cluster calculations, by which we were able to show that charge compensation requirements from the nearest two Al sites arrayed circumferentially in the 10-membered ring of MFI zeolite create such novel functionalities of cadmium. The unprecedented reactivity of CdI and its origin are discussed.
Diffuse reflectance, Materials