An unprecedented fully reduced {Mo } polyoxometalate: from an all-inorganic molecular light-absorber model to improved photoelectronic performance.

Fully reduced polyoxometalates are predicted to give rise to a broad and strong absorption spectrum, suitable energy levels, and unparalleled electronic and optical properties. However, they are not available to date. Here, an unprecedented fully reduced polyoxomolybdate cluster, namely Na[Mo O(OH)]·19HO {Mo }, was successfully designed and obtained under hydrothermal conditions, which is rare and is the largest fully reduced polyoxometalate reported so far.