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Influence of Element Substitution on the Cluster Arrangement in the Novel Structures Ca 3 Tl 5 , Sr 3 Tl 5 , and Sr 3 Sn 5– x Tl x ( x = 1.8 and 2.2)
Author(s) -
Kim SungJin,
Fässler Thomas F.
Publication year - 2009
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200900210
Subject(s) - crystallography , crystal structure , ternary operation , structure type , group (periodic table) , cluster (spacecraft) , space group , niobium , type (biology) , chemistry , materials science , x ray crystallography , diffraction , physics , ecology , organic chemistry , computer science , optics , biology , programming language
The compounds Sr 3 Sn 5– x Tl x ( x = 1.78(4), I ; 2.16(5), II ), Ca 3 Tl 5 ( III ), and Sr 3 Tl 5 ( IV ) have been obtained by direct fusion of the elements in sealed niobium ampoules at high temperature. Their structures were determined by single crystal X‐ray diffraction studies and the bonding was investigated by TB–LMTO–ASA calculations. The ternary phases I and II crystallize in the Tm 3 Ga 5 structure type; space group Pnma (No. 62); Z = 4 with a = 13.422(1), b = 10.897(1), c = 6.897(1) Å for I and a = 13.482(2), b = 10.938(2), c = 6.850(1) Å for II . The binary compounds III and IV crystallize in the Pu 3 Pd 5 structure type; space group Cmcm (No. 63); Z = 4 with a = 10.231(2), b = 8.362(2), c = 10.623(2) Å for III and a = 10.592(5), b = 8.667(5), c = 10.973(6) Å for IV . Both structure types consist of zigzag chains of distorted square pyramidal { E 5 } ( E = Tl, Sn/Tl) clusters. In the lower symmetric structures I / II the clusters are reoriented with respect to each other and have only two exo –contacts each, whereas in III / IV the clusters are aligned parallel and show a considerably higher degree of polymerization. The DOS for Sr 3 Sn 5– x Tl x calculated for x = 0 reveals a pseudo gap for x = 2 within the rigid band model, whereas the electronic band structure for Sr 3 Tl 5 and Ca 3 Tl 5 show metallic properties and strong participation of the cations in the bonding.