Tetroxo anions of hexavalent technetium and rhenium

Abstract

[(CH3)4N]2MnO4, [(CH3)4N]2TcO4, and [(CH3)4N]2ReO4 are isotypic and crystallize in an antifluoritelike cubic face centered lattice with a=11.09 Å (Mn), 11.20 Å (Tc), and 11.35 Å (Re). The magnetic susceptibilities obey the Curie–Weiss law over the temperature range 77–298 °K with μeff=1.63 μB (Mn), 1.60 μB (Tc), and 1.47 μB (Re). The magnetic moments of [(CH3)4N]2TcO4 and [(CH3)4N]2ReO4 as well as the splitting and vibrational structure of the 2E→2T2 intrashell transition indicate strong Jahn–Teller distortion of TcO42− and ReO42− in the first excited 2T2 state. Tetrahedral crystal field parameters of Δ=−11 kK, Δ=−17 kK, and Δ=−19 kK are derived for MnO42−, TcO42−, and ReO42−. The electron transfer spectra reflect the lower degree of covalency of the Re–O bond in comparison to the Tc–O and Mn–O bond.