Structural diversity in thallium chemistry: structures of four chlorothallate(III) salts including a novel compound containing three geometrically different anions

Abstract

Four new thallium-containing salts with different alkyl ammonium cations have been prepared and characterized by X-ray crystallography: 1: bis(p-toluidinium) pentachlorothallate(III), [CH3C6H4NH3]2 [TlCl5], M = 597.9, monoclinic, P21/c, a = 7.515(2), b = 21.376(6), c = 12.769(2) Å, β = 92.13(2)°, V = 2050(1) Å3, Z = 4, Dcalc = 1.937 Mg m−3, µ = 8.512 mm−1, T = 293(1) K, R = 0.046; 2: 1,5-pentanediammonium pentachlorothallate(III), [NH3(CH2)5NH3] [TlCl5], M = 485.83, orthorhombic, P212121, a = 13.226(2), b = 13.595(2), c = 7.628(2) Å, V = 1371.6(3) Å3, Z = 4, Dcalc = 2.352 Mg m−3, µ = 12.84 mm−1, T = 173(1) K, R = 0.025; 3: pentakis(2-adamantaneammoniumn) bistetrachlorothallate(III) hexachlorothallate(III), [C10H18N]5 [TlCl4]2[TlCl6], M = 1870.75, monoclinic, P21a = 16.466(5), b = 25.985(2), c = 7.724(3) Å, β = 90.14(3)°, V = 3305(2) Å3, Z = 2, Dcalc = 1.880 Mg m−3, µ = 7.978 mm−1, T = 173(1) K, R = 0.056; 4: bis(piperazinium) decachlorodithallate(III) trihydrate, [NH2C4H8NH2]2 [Tl2Cl10]•3H2O, M = 993.62, monoclinic, C2/c, a = 14.154(3), b = 15.445(3), c = 13.228(3) Å, β = 114.44(1)°, V = 2632.7(9) Å3, Z = 4, Dcalc = 2.506 Mg m−3, µ = 13.39 mm−1, T = 173(1) K, R = 0.026. For most of the salts examined, formation of [TlCl5]2− is possible; however, no isolated [TlCl5]2− anions were observed. In most cases, high coordination numbers at thallium were observed (CN = 6), and these can be achieved via formation of anionic chains or through dimerization, giving [Tl2Cl10]4−. Of particular interest is the solid state structure of salt 3 in which there are three geometrically different chlorothallate ions. Extensive hydrogen-bonding networks are observed in each structure. Key words: thallium, thallium(III) chlorides, chlorothallate, hydrogen bonding, alkyl ammonium cations.