Ligand mediated valence fluctuation of copper in new hybrid materials constructed from decavanadate and a Cu(1,10-phenanthroline) complex

Abstract

Two new organic hybrid materials [H₄V₁₀O₂₈][CuCl(H₂O)₂(1,10-phenanthroline)]₂·4H₂O (V₁₀O₂₈-CuCl-phen) and [H₄V₁₀O₂₈][Cu(H₂O)₃(1,10-phenanthroline)]₂·4H₂O (V₁₀O₂₈-CuO-phen) were synthesized at room temperature. The effect of the presence and absence of AlCl₃ on the single crystal growth of the two compounds was studied. The compounds were characterized using single crystal X-ray diffraction (XRD), scanning electron microscopy, energy dispersive spectroscopy, infra-red spectroscopy and thermogravimetric analysis. XRD studies on selected single crystals suggest that the compounds consist of supramolecular 3D layer structures constructed from a tetra-protonated [V₁₀O₂₈] unit and the organometallic complex Cu(1,10-phen) with Cl and 2H₂O molecules in the presence of AlCl₃ in V₁₀O₂₈-CuCl-phen and with 3H₂O molecules in V₁₀O₂₈-CuO-phen which was confirmed by TGA studies. Both compounds crystallize in the triclinic space group P‾1: a = 8.3886(3) Å, b = 10.4266(4) Å, c = 13.5860(5) Å, α = 92.440(2)°, β = 92.315(2))°, γ = 98.160(2))° for V10O28-CuCl-phen and a = 8.3733(5) Å, b = 10.4132(6) Å, c = 13.5904(8) Å, α = 92.295(4))°, β = 92.331(2))°, γ = 98.086(4))° for V₁₀O₂₈-CuO-phen. Magnetic measurements suggest that Cu exists in magnetic +2 oxidation state in V₁₀O₂₈-CuCl-phen and non-magnetic +1 oxidation state in V₁₀O₂₈-CuO-phen.