RAMAN AND TE-125 NMR SPECTROSCOPIC EVIDENCE ON THE SOLVENT-EXTRACTIONOF TELLURIUM(IV) SPECIES FROM HCL SOLUTIONS

The Raman spectra of solutions of TeCl4 in HCl up to 12 mol l-1 show a changing pattern of bands consistent with a mixture of complexes, inc luding [TeCl6]2- and [TeCl4(OH)]-. High-field Te-125 NMR spectra at 12 6.24 MHz of these aqueous solutions consist of a single band, showing that the Te(IV) species are in rapid equilibrium, which moves upfield within the range + 1550 to + 1400 ppm as the HCl concentration is incr eased. Solvent extraction with diethyl ether selects a single species from Te(IV)-HCl solutions. This is identified as the complex acid HTeC l4(OH) by a Raman spectrum marked by nu(s)(Te-Cl) = 289 cm-1 and nu(Te -O) = 667 cm-1, and a characteristic Te-125 resonance, delta = 1448 pp m, w1/2 = 80 Hz.