Copper-containing hybrid compounds based on extremely rare [V2Mo6O26]6– POM as water oxidation catalysts†
Abstract
Herein, we report two approaches to the synthesis of heterometallic complexes (NH4)2n(H2en)n{[Cu(en)2][α-V2Mo6O26]}·4nH2O (1), (NH4)2{[Cu(dien)(H2O)]2[α-V2Mo6O26]}·5H2O (2) and (NH4)2{[Cu(dien)(H2O)]2[α-V2Mo6O26]}·8H2O (3) that have been employed in homogeneous photochemical oxidation of water to dioxygen. In these hybrid metalorganic–inorganic compounds, copper-containing complex fragments are covalently bound to the rare vanadium-disubstituted α-octamolybdate cluster. They exhibit variable catalytic activity controlled by the local coordination environment of copper reaching a notably high turnover frequency of 0.24 s−1 for 3 in combination with a relatively low water oxidation overpotential. The complexes have been also used as precursors for the preparation of mixed oxide phases that have proven to be active heterogeneous water oxidation catalysts.
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