Intrinsic Semiconducting Behavior in a Large Mixed‐Valent Uranium(V/VI) Cluster

Uranium based materials recently received substantial attentions in catalysis, superconductivity and magnetism due to integration of unique 5f electron configurations and bonding involvement. Herein, for the first time, we disclose the intrinsic semiconducting properties of one of the largest mixed-valent uranium clusters, [H3O+][UV(UVIO2)8(μ3-O)6(PhCOO)2(Py(CH2O)2)4(DMF)4] (Ph = phenyl, Py = pyridyl, DMF = N,N-Dimethylformamide) (1). Single crystal X-ray crystallography demonstrates that U(V) center is stabilized within a tetraoxo core surrounded by eight uranyl (VI) pentagonal bipyramidal centers. The oxidation states of uranium are substantiated by spectroscopic data and magnetic susceptibility measurement. Electronic spectroscopy and theoretical investigations corroborate that U(V) species serve as electron donors and thus facilitate 1 being a n-type semiconductor. With the largest effective atomic number among all reported radiation-detection semiconductor materials, charge transport properties and photoconductivity were further investigated under X-ray excitation for 1, showing a large on-off ratio of 500 and considerable charge mobility lifetime product of 2.3×10-4 cm2/V, as well as a high detection sensitivity of 23.4 μC Gyair-1 cm-2.