The Crystal Structure of Cs3Fe2Cl9 and of Cs3Sb2Cl9

Abstract

Auszug Cs3Sb2Cl9 kristallisiert in zwei Strukturtypen. Der eine hat die Raumgruppe P321 und die Gitterkonstanten a = 7,633 Â, c = 9,345 Â. Der andere ist rhom-bisch mit a = 7,63 Â, b = 13,22 Â, c = 18,69 Â; seine Raumgruppe ist Pcmn. Abstract Cs3Sb2Cl9 crystallizes with two structure types. One is trigonal, the unit-cell dimensions being a = 7.633 Â, c = 9.345 Â and the space group P321; the other is orthorhombic, with a = 7.63 Â, b = 13.22 Â, c = 18.69 Â and the space group Pcmn. A number of trihalides, in reaction with alkali halides, form crystals with type formula A3B2X9. The structure of CS3AS2CI9 has been investigated by Hoard and Goldstein1. Yamatera and Nakatsu2 investigated Cs3Sb2Clg on the basis of powder photographs. We prepared Cs3Sb2Clg and Cs3Bi2Cl9 crystals and found that Cs3Sb2Cl9 crystallizes in the structure similar to CS3AS2CI9 proposed by Hoard and Gold-stein. We also found in the present case that a modified structure of Cs3Sb2Cl9 occurs commonly. In the following, we shall call the former the « type and the latter the ß type. Cs3Sb2Cl9 is obtained by cooling or evaporating a mixed solution of the two chlorides dissolved into dilute hydrochloric acid. When a sealed glass tube containing the solution saturated at 40 °C was immersed in water at 30 °C and was kept still, acicular crystals appeared in the body of the solution, and no hexagonal crystal was 1 J. L. Hoard and Leonard Goldstein, The structure of caesium ennea-chlordiarsenite, CS3AS2CI9.