Cerium(IV) fluoride and fluoride-arsenate frameworks

Abstract

Five new cerium (IV) fluoride and fluoride–arsenate framework structures have been synthesised hydrothermally using CeF₄ as a fluoride source. Cs[Ce₂F₈[F·H₂O]] (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. [(NH₄)₅(H₂O)₂][Ce₄(AsO₄)₆(H₂O)F₃] (II), has an open framework structure with large channels filled with NH₄⁺ cations and H₂O molecules. Ce[AsO₄]F (III) and Ce[AsO₄]F[H₂O] (IV) exhibit two types of bridging (Ce–O–Ce and Ce–F–Ce) bonds between Ce(O,F)_n polyhedra, and (NH₄)[CeF₂(AsO₄)] (V), is isostructural with the previously reported fluoride-phosphate (NH₄)[Ce^IVF₂(PO₄)] (R. B. Yu, D. Wang, T. Takei, N. Kumada, H. Koizumi and N. Kinomura, J. Solid State Chem., 2001, 157, 180).