The reaction of giant wheel polyoxomolybdate clusters with ethanol

The conversion of ethanol at 100-280° C was used in order to characterise the redox and acid centres present in Na15{0.5[Mo(152)O(457)H14(H(2)O)68] • 0.5[Mo(154)O(462)H(2)14 (H(2)O)(70]}-ca. 400 H(2)O (1). It is concluded that Mo(VI)/Mo pairs at the external surface of the rings, of which the structure of 1 is composed, are the redox centres active in ethanol dehydrogenation to acetaldehyde. Simultaneous ethanol dehydration to diethyl ether or ethylene is a typical reaction occurring on acid centres. It is suggested that OH groups situated in (u3-0)(2)0(2) tetrahedrons inside the ring structure play such role. The formation of ethane predominating at highest temperatures is attributed to secondary reactions of primary ethylene.