Cerium(IV) fluoride and fluoride-arsenate frameworks.

Five new cerium (IV) fluoride and fluoride-arsenate framework structures have been synthesised hydrothermally using CeF(4) as a fluoride source. Cs[Ce(2)F(8)[F.H(2)O]] (I) consists of layers, formed from linked Ce(F,O)(n) polyhedra cross-linked by hydrogen bonding that defines large channels containing the caesium ions. [(NH(4))(5)(H(2)O)(2)][Ce(4)(AsO(4))(6)(H(2)O)F(3)] (II), has an open framework structure with large channels filled with NH(4)(+) cations and H(2)O molecules. Ce[AsO(4)]F (III) and Ce[AsO(4)]F[H(2)O] (IV) exhibit two types of bridging (Ce-O-Ce and Ce-F-Ce) bonds between Ce(O,F)(n) polyhedra, and (NH(4))[CeF(2)(AsO(4))] (V), is isostructural with the previously reported fluoride-phosphate (NH(4))[Ce(IV)F(2)(PO(4))] (R. B. Yu, D. Wang, T. Takei, N. Kumada, H. Koizumi and N. Kinomura, J. Solid State Chem., 2001, 157, 180).