A family of lanthanoid(III) hexafluoroarsenates(V), La (AsF6)(3), LnF(AsF6)
(2), Ln = Ce-Er, and Ln(2)F(3)(AsF6)(3), Ln = Tm, Yb, Lu, has been stabiliz
ed with some fluoro bases as additional ligands forming new compounds: La(H
F)(2)(AsF6)(3), La(XeF2)(2.5)(AsF6)(3) and Ln(AsF3)(3)(AsF6)(3), Ln = Ce, P
r. La(HF)(2) (AsF6)(3) was prepared by solvothermal reaction in AsF5 above
its critical temperature, while syntheses of other compounds were carried o
ut in anhydrous hydrogen fluoride (aHF) as a solvent at ambient temperature
. When Ln(2)O(3) were used as starting compounds in the AsF5/aHF superacid
medium the oxonium compounds of the type (H3O)(x)Ln(y)F(z)(AsF6)(x+3y-z) we
re synthesized. The crystal structures of (H3O)(8)La2F(AsF6)(13), (H3O)(4)L
a2F(AsF3)(2)(AsF6)(9), La(HF)(2)(AsF6)(3) and La(XeF2)(2.5)(AsF6)(3) exhibi
t low-dimensional structural features, while the structure of Ln(AsF3)(3)(A
sF6)(3) (Ln = Ce, Pr) shows a three-dimensional network. In the structure o
f La(HF)(2)(AsF6)(3) bonding interaction between HF and a metal centre is d
escribed for the first time. (C) 2000 Elsevier Science S.A. All rights rese
rved.