This work has been digitalized and published in 2013 by Verlag Zeitschrift für Naturforschung in cooperation with the Max Planck Society for the Advancement of Science under a Creative Commons Attribution 4.0 International License. Dieses Werk wurde im Jahr 2013 vom Verlag Zeitschrift für Naturforschung in Zusammenarbeit mit der Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. digitalisiert und unter folgender Lizenz veröffentlicht: Creative Commons Namensnennung 4.0 Lizenz. Tris(ethyldimethylphenylammonium) nonahalogenodibismuthates(III) H. Eickmeier, Bernd Jaschinski, A. Hepp, Jürgen Nuß, Hans Reuter, Roger Blachnik* Institut für Chemie, Universität Osnabrück, Postfach 4469, D-49069 Osnabrück Dedicated to Prof. Dr. Bernt Krebs on the occasion of his 60th birthday Z. Naturforsch. 54 b, 305-313 (1999); received August 7, 1998 Bismuth, Tris(ethyldimethylphenylammonium) nonachlorodibismuthate, Tris(ethyldimethyl- phenylammonium) nonabromodibismuthate, Tris(ethyldimethylphenylammonium) nonaiodo- dibismuthate, Enthalpy of Transition The halogenobismuthates Q 3Bi:X 9 (Q = EtMe2PhN; X = Cl, Br, I) were prepared by re action of BiXi with EtMe->PhNX in ethanol. Single crystal structure determinations yielded: [EtMe2PhNMBi 2Cl9], S.G. P2 , 2 , 2 ,, Nr. 19, a = 952.5(3), b = 1184.1(4), c = 3726.4(9 pm, Z = 2;[EtMe.PhNMBi.Br 9]S.G.P2,/c, No. 14, a= 1839.4(4),6= 1329.5(3), c= 1817.3(6)pm, ß = 92.68(3)°, Z = 4, [EtMe2PhN] 3[Bi2l 9], S.G. P2,/c, No. 14, a = 1915.3(2), b = 1379.0(3), c = 1890.9(5) pm, ß = 92.48(1)°, Z = 4. The thermal behaviour was investigated with the aid of DSC measurements and temperature dependent X-ray powder diffraction. All compounds undergo a transition into a high temperature modification which could be obtained in case of [EtMe2PhN] 3[Bi2Br9 _.vIv] in form of single crystals: S.G. P2|/c, Nr. 14, a = 1002.7(5), b = 1278.7 ( 8 ), c = 3584.3(5) pm, ß = 90.12(2)°, Z = 4. Surprisingly in this compound the iodine atoms are not statistically distributed over all possible bromine positions, but occupy only one position. Lattice parameters of the other high temperature modifications and enthalpies of transition of the compounds are given. In addition a second iodobismuthate was isolated: [EtMeoPhN]4[Bi6L2], S.G. Pi, Nr. 2 , with lattice parameters of a = 1343.4(3), b = 1554.3(3), c = 2262.5(6) pm, a = 100.89(3)°, ß = 96.63(1)°, 7 = 98.94(2)° and Z = 2. Introduction Compounds with large second-order optical non- linearities are of considerable interest because they are potential electro-optical materials for applica tions in telecommunication, optical computing and data storage. Necessary condition for this property is the crystallization in acentric space groups. Our synthetic efforts in a search for such materials were concentrated recently on argyrodites [1]. This class is related to sillenites which also exhibit a strong electro-optical activity [2], The structure of both groups is determined by isolated anionic entities in a cationic matrix. Similar building principles are found in salts of the general formula Q/;Bi,„X„+ 3,„ (X = Cl, Br, I; Q = organylammonium cation). The structures of these compounds consist of anionic substructures built from distorted BiX63~ octahe- dra, which are isolated or connected to oligomers or polymers and embedded in a matrix of large cations. These compounds can be prepared eas ily and have low melting temperatures, thus being * Reprint requests to Prof. Dr. Roger Blachnik. model substances for high melting chalcogenides. By variation of the group Q numerous compounds of this type are possible. In the hope to find electro-optical materials we prepared salts of [Bi 2 X 9 ]3- (X = Cl, Br, I) with the cation [EtMe2 PhN]+. Bismuth was chosen because a statistical analysis of 23000 inorganic compounds has revealed that its compounds crystallize more than statistically in acentric space groups [3]. Experimental Methods Differential scanning calorimetry was carried out with a Setaram Calorimeter DSC 92 (DSC) and a heating rate of 2.5 K-1, thermogravimetric experiments with a thermobalance (DuPont 951 TGA; TG). Temperature and enthalpy calibrations were performed with the melt ing points and enthalpies of indium and 1, 2 -dichloro- ethane [4], The thermodynamic data were determined by integration of the DSC signals. Powder diffractograms were recorded with the aid of a Stoe Stadi P-powder diffractometer (CuKcvi -radiation, germanium-monochromator) at ambient and higher tem peratures. For measurements below room temperature 0932-0776/99/0300-0305 $ 06.00 © 1999 Verlag der Zeitschrift für Naturforschung, Tübingen • www.znaturforsch.com K