| Abstract: | Preparation and Spectroscopic Characterization of Strontium and Barium Tetrabromoferrate(III) and the Crystal Structure of Ba(FeBr4)2 The synthesis of the hitherto unknown bromoferrates(III) of alkaline‐earth metals was carried out by heating mixtures of the metals or the binary bromides together with bromine at temperatures of 450 °C and pressures of up to 1500 bar in closed quartz ampoules. The attempts have been successful only with the larger cations of Sr and Ba. In the case of Be, Mg, and Ca only mixtures of the binary bromides with FeBr3 could be received. By analysis of the Raman and electronic spectra the dark red compounds of Sr and Ba have been characterized as ternary tetrabromoferrates(III) containing tetrahedral FeBr4 anions. The composition M(FeBr4)2 (M = Sr, Ba) has been determined by potentiometric and titrimetric analysis and thermal degradation by thermogravimetry. A single crystal structure determination of Ba(FeBr4)2 confirmed the spectroscopic assignments. The orthorhombic crystal structure (space group Pbca; a = 13.054(3) Å; b = 11.093(2) Å; c = 21.764(4) Å; Z = 8) consists of FeBr4 and BaBr9 polyhedra. |
