摘要：

Laser ablation of vanadium pentoxide (V_2O_5) powder produces VO_3~-, V_2O_5~-, V_3O_7~-, V_3O~8, and V_4O_(10)~- cluster ions which have subsequently been reacted with methyl isobutyrate, methyl methacrylate monomer and its dimer in the ion cell region of a Fourier transform ion cyclotron resonance mass spectrometer. Gas phase ion/molecule chemistry has revealed that reactivity decreases with increased mass of the vanadium oxide cluster anions. VO_3~-, V_2O_5~-, and V_3O_7~- ions react with the three reagents, methyl isobutyrate, methyl methacrylate and its dimer, respectively, either by additon of a whole reagent molecule or an associated fragment. All products formed are a result of parallel processes. V_4O_(10)~- undergoes no reaction for reaction times of up to 500 s, while V_3O_8~- adds a water molecule. Although the ions possess a net negative charge, the reactive site toward electron rich reagents such as methyl isobutyrate, methyl methacrylate and its dimer is the under-coordinated vanadium atom. This observation is supported by the lack of reactivity toward the studied reagents by those anions (V_3O_8~- and V_4O_(10)~-) whose most likely stable structures contain fully coordinated vanadium atoms.

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