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Z. Naturforsch. 2013,
68b, 17 – 22
doi:10.5560/ZNB.2013-2293
SrCo2Sn8 and BaCo2Sn8: Tin-rich Stannides with Distorted SnSn6 Octahedra within Three-dimensional [Co2Sn8] Networks
Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany
Reprint requests to R. Pöttgen. E-mail:
pottgen@uni-muenster.de
Received November 7, 2012 / published online January 10, 2013
The tin-rich stannides SrCo2Sn8 and BaCo2Sn8 were synthesized from the elements in sealed tantalum tubes. They crystallize with a new structure type, space group Cccm with a = 1006.0(3), b = 1514.4(6), c = 1385.0(6) pm for SrCo2Sn8 and a = 1032.8(2), b = 1516.8(3), c = 1405.1(3) pm for BaCo2Sn8. The structure of the barium compound was refined on the basis of single-crystal X-ray diffractometer data: wR2 = 0.0450, 1715 F2 values, 57 variables. The cobalt atoms have seven nearest tin
neighbors with Co–Sn distances ranging from 257 to 273 pm. These CoSn7 units are condensed via common rectangular faces to [Co2Sn10] double units which build up a covalently bonded three-dimensional network through Sn–Co–Sn bridges. Larger voids left by this network are filled by the barium and the Sn2 atoms. The latter have distorted octahedral tin coordination with Sn2–Sn distances of 311–315 pm. The barium atoms have 13 nearest tin neighbors (352–399 pm Ba–Sn). Temperature-dependent magnetic susceptibility data of BaCo2Sn8 show Pauli paramagnetism.
Key words: Stannide, Crystal Structure, Pauli Paramagnetism, Cobalt, Strontium, Barium