Vanadium oxide anion cluster reactions with methyl isobutyrate and methyl methacrylate monomer and dimer: a study by FT/ICR mass spectrometry

Abstract

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 addition 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.