CO oxidation on the heterodinuclear tantalum–nickel monoxide carbonyl complex anions

For the TaNiO(CO)n− series, the CO oxidation occurs at n = 8, and both LH-like and ER-like mechanisms become generally favorable. [Display omitted] The series of heterodinuclear metal oxide carbonyls in the form of TaNiO(CO)n− (n = 5–8) are generated in the pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy. During the consecutive CO adsorption, the μ2-O-bent structure initially is the most favorable for TaNiO(CO)5−, and subsequently both μ2-O-bent and μ2-O-linear structures are degenerate for TaNiO(CO)6−, then the μ2-O-linear structure is most preferential for TaNiO(CO)7−, and finally the η2-CO2-tagged structure is the most energetically competitive one for TaNiO(CO)8−, i.e., the CO oxidation occurs at n = 8. In contrast to the literature reported CO oxidation on heteronuclear metal oxide complexes generally proceeding via Langmuir–Hinshelwood-like mechanism, complementary theoretical calculations suggest that both Langmuir–Hinshelwood-like and Eley–Rideal-like mechanisms prevail for the CO oxidation reaction on TaNiO(CO)8− complex. Our findings provide new insight into the composition-selective mechanism of CO oxidation on heteronuclear metal complexes, of which the composition be tailored to fulfill the desired chemical behaviors.