Electrochemistry of Centered Hexanuclear Zirconium Halide Clusters in Ambient-Temperature Chloroaluminate Molten Salts

Abstract

Ambient temperature AlCl(3)-1-ethyl-3-methylimidazolium chloride (ImCl) molten salts, both basic (40/60 mol % AlCl(3)/ImCl) and acidic (60/40 mol % AlCl(3)/ImCl), were used in an electrochemical investigation of centered hexanuclear zirconium halide clusters. In the basic molten salt, these [(Zr(6)ZCl(12))Cl(6)](n-) (Z = Be, B, C, Mn, Fe) centered clusters exhibit the following electrochemical reactions on a glassy carbon electrode (potentials vs Al/Al(3+)): [(Zr(6)BeCl(12))Cl(6)](n)()(-) + e(-) right harpoon over left harpoon [(Zr(6)BeCl(12))Cl(6)](()(n)()(+1))(-), E(1/2) = -0.613 V (n = 4), E(1/2) = -1.085 V (n = 5); [(Zr(6)BCl(12))Cl(6)](n)()(-) + e(-) right harpoon over left harpoon [(Zr(6)BCl(12))Cl(6)](()(n)()(+1))(-), E(1/2) = -0.365 V (n = 4), E(1/2) = 0.072 V (n = 3); [(Zr(6)CCl(12))Cl(6)](n)()(-) + e(-) right harpoon over left harpoon [(Zr(6)CCl(12))Cl(6)](()(n)()(+1))(-), E(1/2) = 0.230 V (n = 3); [(Zr(6)MnCl(12))Cl(6)](4)(-) + e(-) right harpoon over left harpoon [(Zr(6)MnCl(12))Cl(6)](5)(-), E(1/2) = -0.432 V. In the acidic melt, only electrochemical reactions [(Zr(6)BeCl(12))(AlCl(4))(6)](n)()(-) + e(-) right harpoon over left harpoon [(Zr(6)BeCl(12))(AlCl(4))(6)](()(n)()(+1))(-), E(1/2) = -0.069 V (n = 5), E(1/2) = 0.504 V (n = 4), and [(Zr(6)BCl(12))(AlCl(4))(6)](4)(-) + e(-) right harpoon over left harpoon [(Zr(6)BCl(12))(AlCl(4))(6)](5)(-), E(1/2) = 0.700 V are clearly observed. These data is consistent with less systematic observations of oxidation of these clusters in solution. No unambiguous one-electron electrochemical reduction nor oxidation is observable for the Fe-centered cluster in the ionic liquids. The half-wave potentials of the above reactions of the Be-, B-, C-, and Mn-centered clusters are controlled largely by clusters' charges. This correlation of redox potentials allows a useful direct comparison with data for related hexanuclear niobium clusters in the literature.

Electrodeposition of Al-Zr Alloys from Lewis Acidic Aluminum Chloride-1-Ethyl-3-methylimidazolium Chloride Melt

“…30 The electrochemistry of hexanuclear zirconium halide clusters was investigated in the AlCl 3 -EtMeImCl melt containing 60 mol % AlCl 3 . 31 However, no evidence for the electrodeposition of zirconium metal or Al-Zr alloy was obtained during this or any of the investigations just described. In this article, we report the electrodeposition of Al-Zr alloys on Cu substrates from the Lewis acidic AlCl 3 -EtMeImCl molten salt and the electrochemistry of Zr͑IV͒ and Zr͑II͒ in this melt as it pertains to the electrodeposition of these alloys.…”

Cationic Boron‐Centred Hexanuclear Zirconium Cluster Compounds with Nitrilo Ligands and [MIIICl4]– Counter Ions: [(Zr6B)Cl12(CH3CN)6][MIIICl4] with MIII = Al, Ga, In

“…Initial work in this research area by J. D. Corbett and T. Hughbanks and coworkers has focused on the dissolution process of the solid precursors as well as on elaborating various analytical methods for the characterization of the dissolved cluster species. [9][10][11][12][13]15,18,[23][24][25][26] In the latter case heteroatom NMR spectroscopic techniques have proven very useful. [15,23,28] In order to develop the solution chemistry of Zr cluster compounds further and to ensure high yields of new compounds, a high solubility of the precursor is required.…”

Atomlike Building Units of Adjustable Character: Solid‐State and Solution Routes to Manipulating Hexanuclear Transition Metal Chalcohalide Clusters

“…Of these, four have been isolated and structurally characterized, and the fifth, [W 6 CCl 18 ] 4À , should be readily generated using a reductant such as sodium metal. Typically, edge-bridged octahedral clusters of zirconium, niobium, or tantalum have three or four accessible redox states (182)(183)(184)(185)(186). The clusters [Mo 6 X 8 (PEt 3 ) 6 ] (X ¼ S, Se) also exhibit a rich electrochemistry, with three one-electron transformations accessing sates with 19-22 metal-based valence electrons (49).…”