Cao, JP; Xue, YS; Li, NF; Gong, JJ; Kang, RK; Xu, Y
Carbon dioxide (CO2) and sulfides in gasoline are the main causes of air pollution. Considerable attention has been devoted to solving the problems, and the catalytic reaction seems to be a good choice. Owing to the high density of Lewis acid (LA) active sites and large numbers of open methoxide groups, polyoxovanadates (POVs) are an undisputed option as a heterogeneous catalyst for the CO2 cycloaddition reaction and catalytic oxidation of sulfides. On the basis of the above, a series of V8 clusters, [(C2N2H8)4(CH3O)8VIV8O12]·CH3OH (V
8
-1a), [(C2N2H8)4(CH3O)4VIV4VV4O16]·4CH3OH (V
8
-1), [(C3N2H10)4(CH3O)4VIV4VV4O16]·5H2O (V
8
-2), [(C6N2H14)4(CH3O)4VIV4VV4O16]·5CH3OH·2H2O (V
8
-3), have been legitimately designed and triumphantly isolated. In the synthesis process, three different kinds of Lewis bases (LBs), ethanediamine, 1,2-diaminopropane, and 1,2-cyclohexanediamine, were used to modify LA {V
8
} clusters to form four diverting windmill-shaped configuration. Among them, the vanadium atoms in V
8
-1a are +4 valence of VIV, while the vanadium atoms in V
8
-1-3 are mixed valence states of VIV and VV. Magnetic property investigation indicates that the antiferromagnetic coupling interactions between VIV ions all exist in the four compounds. The compound V
8
-1 also demonstrated high catalytic activity in the cycloaddition of CO2 to several epoxides under relatively mild conditions (70 °C, 0.5 MPa). More importantly, the reaction pressure 0.5 MPa is the lowest among the high nuclear polyoxometallates (POMs). Furthermore, V
8
-1 also has an excellent catalytic conversion for the oxidation of sulfides. The catalytic tests manifested that V
8
-1 was a very efficient difunctional heterogeneous catalyst for CO2 cycloaddition reaction and catalytic oxidation of sulfides.