CO activation by the heterobinuclear transition metal-iron clusters: A photoelectron spectroscopic and theoretical study

Abstract

Abstract Spectroscopic characterization of CO activation on multiple metal-containing catalysts remains an important and challenging goal for identifying the structure and nature of active site in many industrial processes such as Fischer-Tropsch chemistry and alcohol synthesis. Here, we use mass-selected photoelectron velocity-map imaging spectroscopy and quantum chemical calculations to study the reactions of CO molecules with several heterobinuclear transition metal-iron clusters M–Fe (M\xa0=\xa0Ti, V, Cr). The mass spectra reveal the favorable formation of MFe(CO)4− with relatively high thermodynamic stability. The MFe(CO)4− (M\xa0=\xa0Ti, V, Cr) complexes are established to have a metal–Fe bonded M–Fe(CO)4 structure with C3v geometry. While the positive charge and unpaired electrons are mainly located on the M atom, the natural charge of Fe(CO)4 is about −2e. The MFe(CO)4− (M\xa0=\xa0Ti, V, Cr) can be seen as being formed via the interactions between the M+ fragment and the [Fe(CO)4]2− core, which satisfies the 18-electron rule. The CO molecules are remarkably activated in these MFe(CO)4−. These results shed insight into the structure–reactivity relationship of heterobinuclear transition metal carbonyls and would have important implications for understanding of CO activation on alloy surfaces.