Synthesis and spectroscopic characterization of complexes of Cr(III), Cr(VI), Cu(III), Zn(II), Mo(VI), Pd(II), Ag(III), Au(III) and W(VI) with telluric acid

New preparative methods are reported for telluric acid complexes, Na5[Cr(TeO4(OH)2)2(H2O)2], Na6[Zn(TeO4(OH)2)2(H2O)2], Na6[Pd(TeO4(OH)2)2], Na5[M(TeO4(OH)2)2] (M(III) = Cu, Ag, Au) and K6TeM6′O24 (M′(VI) = Cr, Mo, W). Their structures were characterized on the basis of spectroscopic, crystallographic, magnetic and thermal measurements. The deprotonation constants of telluric acid and the stability constants of the Co(II), Ni(II), Cu(II), Zn(II) and Pd(II) complexes were determined by pH-metric measurements.

Telluric acid complexes, Na5[Cr(TeO4(OH)2)2(H2O)2], Na6[Zn(TeO4(OH)2)2(H2O)2], Na6[Pd(TeO4(OH)2)2], Na5[M(TeO4(OH)2)2] (M(III) = Cu, Ag, Au) and K6[TeM6′O24] (M′(VI) = Cr, Mo, W) are reported. On the bases of spectroscopic, crystallographic, magnetic and thermal measurement, their structures were characterized. The deprotonation constants of telluric acid and the stability constants of its Co(II), Ni(II), Cu(II), Zn(II) and Pd(II) complexes have been measured pH-metrically. This study is a continuation of our interest in the preparation of transition metal ions in high oxidation states complexes, which can be applied as catalysts for the oxidation of many organic substrates; especially that are intermediates in Pharmaceutical and petroleum industries.Figure optionsDownload as PowerPoint slideHighlights
► New complexes of telluric acid {Te(OH)6} are reported.
► IR and Raman spectra show ν(OH), δ(HOH) modes of water, δ(TeOH), ν(MO) and ν(TeO).
► [TeM6O24]6− [M(VI) = Cr, Mo, W] shows D3d structure involves central octahedral TeO6.
► UV–vis. spectra and μeff values suggest square planar Cu, Ag, Au, Pd complexes.
► pKa values of Te(OH)6 and stability constants of Co, Ni, Cu, Zn, Pd were determined.