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Zusammenfassung:
CO2 adsorption on Ti3O6-, which serves as a model for an oxygen vacancy on a titania surface, is studied using infrared photodissociation (IRPD) spectroscopy in combination with density functional theory (DFT) and coupled cluster computations as well as a recently developed multi-component artificial force induced reaction method. The IRPD spectra of D2-tagged [Ti3O6(CO2)n]- with n = 1, 2 are reported in the spectral window of 450–2400 cm-1 and assigned based on a comparison to harmonic IR spectra from the DFT calculations. We find that CO2 binding leaves the unpaired electron largely unperturbed. The first two CO2 molecules adsorb chemically to Ti3O6- by incorporating a formally doubly negatively charged, either doubly or triply coordinated O-atom to form a bidentate or tridentate bridging carbonate dianion (CO32-), respectively. The latter binding motif exhibits a characteristic IR signature in the form of an intense doublet of peaks near 1400 cm-1 stemming from two antisymmetric carbonate stretching modes.
