Syntheses and Properties of A -#x3B1;- Tungstogermanate Isomers Trisubstituted by Transition Elements

摘要

A series of new compounds with the formula A -#x3B1;- M#x2032;xHyGeW9M3(H2O)3O37 nH2O M=Cr (III), Mn (II), Co (II), Ni (II), Cu (II); M#x2032; = Bu4N, K were synthesized and characterized by IR and UV-VIS spectroscopy, polarography and cyclic voltammetry, magnetic moments and ESR and XPS spectra. The vibrational absorption bands in the range 300#x2013;400cm#x2212;1indicates that the title compounds have #x3B1;-Keggin structure. There is a linear relationship between the E1/2of the first polarographic waves of the title compounds and the electro-negetivity and the bonding energy of M (2p3/2) of the transition elements. The pH range in which the anions are stable in aqueous solution are given. The catalytic activity studies have shown that the compounds can catalyze the dehydration of methanol to dimethyl ether.