K. Lutar et al., XEF2-CENTER-DOT-2CRF(4) AND XEF5- - SYNTHESES, CRYSTAL-STRUCTURES, AND SOME PROPERTIES(CRF5), Inorganic chemistry, 37(12), 1998, pp. 3002-3006
XeF2. 2CrF(4) was prepared by solvolysis of XeF2. CrF4 in anhydrous hy
drogen fluoride (aHF) and subsequent decantation of the majority of di
ssolved XeF2 in aHF. Remaining XeF2 and a large excess of CrF4 form Xe
F2. 2CrF(4) after aHF is removed. Ruby-red single crystals were obtain
ed either by healing the sample in a thermal gradient or by recrystall
ization in supercritical SF6. The compound crystallizes in the triclin
ic space group P (1) over bar with a = 855.1(3) pm, b = 922.1(3) pm, c
= 1043.8(3) pm, alpha = 76.02(2)degrees, beta = 81.36(2)degrees, gamm
a 88.08(3)degrees, and Z = 4 at 293 K. The basic structural unit is fo
rmed by four independent Cr atoms, each octahedrally coordinated by si
x F atoms. Two fluorine ligands are provided by two different XeF2 mol
ecules. The distorted octahedra are connected via common F atoms to fo
rm a three-dimensional network. XeF5+CrF5- was prepared from XeF6 and
CrF4 at room temperature or by the reaction of XeF6 and CrF5 at 333 K.
Red single crystals were grown from the solution of XeF5+CrF5- in aHF
. The compound crystallizes in the orthorhombic space group Pbca with
a = 1828.1(13) pm, b = 842.9(7) pm, c 1852.1(12) pm, and Z = 16 at 268
K. The main structural feature is formed by an infinite chain of dist
orted CrF6 octahedra joined via cis vertexes, while XeF5+ cations comp
ensate the negative charge of each octahedron.