Synthesis, structural and spectroscopic characterization, and topological analysis of five novel uranyl-based silicates and germanates have been performed. The open-framework K-4(UO2)(2)Si8O20 center dot 4H(2)O has been synthesized under hydrothermal conditions and is based upon [USi6] heptamers interconnected via edge-sharing. Its structure is composed of sechser silicate layers with 4-, 8-, and 16-membered rings. The largest 16-membered rings have an average dimension of similar to 8.93 X 9.42 angstrom(2). beta-K-2(UO2)Si4O10 has been obtained by the high-temperature flux growth method. Its 3D framework contains a loop-branched sechser single layer with 4- and 8-membered rings and consists of the same [USi6] heptamers as observed in K-4(UO2)(2)Si8O20 center dot 4H(2)O. Na-6(UO2)(3)(Si2O7)(2) has also been synthesized from melted fluxes and represents a 2D layer structure composed by [USi4] pentamers. Two iso-structural compounds A(+)(UO2)(HGeO4)center dot H2O (A(+ )= Rb+, Cs+) were synthesized via the hydrothermal method, and their structures are of the a- uranophane type. The 2D layers consist of [U2Ge2] tetramer secondary building units (SBUs). The Raman spectra of all novel phases were collected, and bands were assigned according to the existing oxo-silicate rings and oxo-germanium units. Additionally, we performed a statistical investigation of the local coordination of uranyl ions in all known inorganic structures with different oxo-anions (TOx, T = B3+, Si/Ge4+, P/As5+, S/Se/Te6+, Cr/Mo/W6+, P/As3+, and Se/Te4+). We found a direct correlation between the ionic potential of the central cations T in oxo-anions in their higher oxidation states and the coordination number of uranyl groups.