LAUSR

Abstract The fluoropolymers as FEP and PFA are widely used materials for making reaction vessels applied to experiments involving liquid anyhdrous HF, elemental F2 and various inorganic fluorides and fluoro-organic compounds. However, due to their permeability to gases and liquids, crystals of unexpected compounds can be sometimes grown during extended durations of the crystallizations. One of such examples is the growth of single crystals of (H3O)2Ce(BF4)5, which were grown unintentionally from the CeF3/BF3/aHF solution after five months of crystallization. Reaction between the La2O3 and excess of BF3 in anhydrous HF yielded a similar compound, i.e., (H3O)2La(BF4)5 upon crystallization. The attempts to prepare single crystals of analogous compounds of Nd and Sm failed. (H3O)2Ce(BF4)5 crystallizes in the monoclinic P21/n space group (No. 14) with a = 11.9160(14) A, b = 9.1551(12) A, c = 14.5290(14) A, β = 94.929(5)°, V = 1579.1(3) A3, and Z = 4 at 200 K. The crystal structure of (H3O)2La(BF4)5 is isotypic with cerium compound. Corresponding unit cell is monoclinic, P21/n space group (No.14), with a = 12.004(10) A, b = 9.197(2) A, c = 14.577(7) A, β = 94.459(9)°, V = 1604.5(17) A3 and Z = 4 at 100 K. The crystal structures of (H3O)2Ln(BF4)5 (Ln = La, Ce) consist of slabs formed from the Ln3+ cations interconnected with the [BF4]−anions. The oxonium cations are located in the space between the slabs. Ln3+ cations are nine-fold coordinated with a tricapped trigonal prismatic arrangement of F ligands.