A NEW RARE-EARTH-METAL NITRIDE HALIDE WITH UNUSUAL STRUCTURAL FEATURES - CSXNA1-XLA9I16N4 WITH A REMARK ABOUT THE STOICHIOMETRIC COMPOUNDS ALA(9)I(16)N(4) (A=NA, RB, CS)
M. Lulei et Jd. Corbett, A NEW RARE-EARTH-METAL NITRIDE HALIDE WITH UNUSUAL STRUCTURAL FEATURES - CSXNA1-XLA9I16N4 WITH A REMARK ABOUT THE STOICHIOMETRIC COMPOUNDS ALA(9)I(16)N(4) (A=NA, RB, CS), European journal of solid state and inorganic chemistry, 33(2-3), 1996, pp. 241-250
Reactions of LaI3, CsI and NaN3 in niobium tubes at 750 degrees C yiel
ded pale yellow, transparent crystals of CsxNa1-xLa9I16N4 (x = 0.64) w
hich were examined by single crystal X-ray diffraction and EDX. The st
ructure (orthorhombic, Fddd, Z = 8, a = 8.980(4) Angstrom, b = 22.91(2
) Angstrom, c = 43.61(3),Angstrom, R(F) = 0.023, R(w) = 0.031) contain
s infinite chains of nitrogen centered, edge-sharing La-4 tetrahedra a
s well as seperate lanthanum atoms that interconnect the chains via co
mmon iodine atoms. The result is a lanthanum-nitrogen-iodine framework
with the alkali-metal atoms statistically distributed on sites within
channels in the structure. Preliminary experiments with the exact sto
ichiometry ALa(9)I(16)N(4) (A = Na, Rb or Cs) and only one alkali meta
l also yielded the same structure type according to the powder pattern
s. The compound is related to the Gd2Cl3N structure type and also to '
'reduced'' cluster compounds like Pr5I4Ru but with a new type of conne
ctivity.