Electrochemistry of trinuclear metal clusters of molybdenum and tungsten in 1-ethyl-3- methylimidazolium tetrafluoroborate

by Harris, Tracey Lynn

The imidazolium based ionic liquid: 1-ethyl-3- methylimidizoliumtetrafluoroborate, (EMIBF4) was synthesized to be used as a solvent for the electrochemical investigation of molybdenum and tungsten. The electrochemical window is about 4.2V after removing traces of impurities such as Cl- and H2O. Electronic spectra of metal clusters [Mo3O2(O2CCH3)6(H2O)3]^+2 ; [W3O2(O2CCH3)6(H2O)3]^+2 ; [MoW2O2(O2CCH3)6(H2O)3]^+2 and [Mo2WO2(O2CCH3)6(H2O)3]^+2 in EMIBF4 are identical to the spectra of the same clusters obtained in water. Cyclic voltammogram (CV) of Mo and W clusters obtained in EMIBF4 are clearly dependant on the potential of working electrode. For example the CV of [Mo3O2(O2CCH3)6(H2O)3]^+2 metal clusters on glassy carbon electrodes displays a reduction peak at ? +1.0V and a reversible oxidation peak at ? 1.8 - 2.0V and a reoxidation peak upon reversal of potential characteristic of deposition of metals on the Pt electrode. In this research we propose that during electrolysis, the clusters will be disintegrated during oxidation and the metal will be deposited onto the platinum electrode by reduction.