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Abstract:
Sr-3[Al2N4] (Pnna, Nr. 52; a = 590.1(3), b = 1000.5(5), c = 958.0(4) pm;
Z = 4) was prepared from the elements (molar ratio Sr:Al = 3:1; reaction
with N-2, 1 atm, 24 h; T-max = 1100 degrees C). The crystal structure
contains corrugated chains (1)(infinity)[AlN4/23-] which consist of
distorted AlN4 tetrahedra sharing common edges (Al-N: 188.5(7)-195.8(7)
pm; N-Al-N: 95.0(3)-126.0(5)degrees). The nitrogen atoms form a
distorted ccp arrangement. 3/4 of the octahedral holes are occupied by
Sr atoms; 1/4 of the tetrahedral holes are occupied by Al atoms.
Sr-3[Al2N4] can be described in terms of the Zintl concept (isosteric
relation of[AlN2](3-) to SiS2).
