A new uranyl silicate sheet derived from phosphuranylite topology in the structure of Cs₄[(UO₂)₅(SiO₃OH)₂O₂F₄]

A new uranyl silicate Cs 4 [(UO 2 ) 5 (SiO 3 OH) 2 O 2 F 4 ] ( 1 ), was obtained via a hydrothermal route. The new compound is monoclinic, P 2 1 / n , a = 8.3870(2), b = 13.4612(2), c = 10.9503(2) Å, β = 91.223(2)°, V = 1236.00(4) Å 3 ; the structure has been solved and refined down to R 1 = 0.022. Therein, the phosphouranylite units ( PU s) associate into a new type of uranyl-silicate layers, [(UO 2 ) 5 (SiO 3 OH) 2 O 2 F 4 ] 4− , which interleave with the Cs + cations. Topological analysis of PU based structures indicates that these layers in 1 provide a unique example of complexes constructed only via association of the PU and not involving other building units.