Electronic structures of MoWO_y^- and MoWO_y determined by anion photoelectron spectroscopy and DFT calculations

The anion photoelectron spectra of MoWO_y^- (y=2-5) and density functional theory (DFT) calculations on MoWO_y^- and MoWO_y are reported and compared to previous comparable studies on Mo₂O_y^- / Mo₂ O_y and W₂ O_y^- / W₂ O_y. The property governing the structure of the lowest energy MoWO_y anion and neutral clusters is the stronger W-O bond relative to the Mo-O bond, which results in the stabilization of structures in which the Mo center is in a much lower oxidation state than the W center. Anion PE spectra show a much larger change in structure between anion and neutral states than what was observed in the pure Mo₂ O_y^- and W₂ O _y^- spectra. DFT calculations show increased single-metal localization of spin with respect to the pure metal oxide clusters.