Comparative Studies on Periodatocuprate(II, III) and Telluratocuprate(II, III)

Abstract

The crystal structures, electronic spectra, and Cu2 p XPS of Cu(III) complexes Na 4H[Cu(H 2TeO 6) 2] · 17H 2O and Na 4K[Cu (HIO 6) 2] · 12H2O have been described. The characterizations of a Cu(III) atom in a complex are as follows: (i) In a square-planar coordination, the average bond length of Cu-O is 0.183 nm, shorter than the 0.190-0.200 nm found for a Cu(II) complex. (2) The "blue shift" occurs for d-d transitions in the electronic spectrum of the Cu(III) complex compared to those of its related Cu(II) complex, resulting from the higher valence state. (3) Cu(III) compounds with CuO 4 square-planar coordination are expected to be diamagnetic whereas Cu(II) compounds to be paramagnetic. (4) Comprehensive investigations on Cu2 p XPS show that the binding energy of Cu2 p 3/2 of a pure Cu(III) compound is about 2.0 eV higher than that of its corresponding Cu(II) compound: the shakeup satellites do not appear in the Cu2 p XPS for a pure diamagnetic Cu(III) compound, the same as found for a diamagnetic Ni(II) compound: the FWHM of the signal of Cu2 p XPS may become broader for Cu(III) compound because its core hole's lifetime shortens due to the higher valence state of copper.