Reaktionen und Strukturen von [(C2H5)4N][OsCl6] und [(n-C4H9)4N]2[Os2Cl10] / Reactions and Structures of [(C2H5)4N][OsCl6] and [(n-C4H9)4N]2[Os2Cl10]

Abstract

On heating of [(C2H5)4N][OsCl6] for a short time at 240 °C , Cl2 is lost and [(C2H5)4N]2[Os2Cl10] is formed quantitatively. Both complexes are connected by a temperature dependent redox equilibrium so that by treatment at 120 °C with Cl2 gas the hexachloroosmate(V) is recovered from the decachlorodiosmate(IV). The crystal structures of salts of both an ions were determined from single crystal X -ray diffraction analyses. [(C2H5)4N][OsCl6] is monoclinic, space group P2 1 with a = 7 .020 (1), b = 10 .163 (2), c = 11.609 (2) Å , β = 103.91(1)° (at - 133 °C ). The strongly pseudocentrosymmetric structure shows a reversible phase transition at ca. 85 °C. The Os -Cl bond length (mean value 2.303 Å) in the regular [OsCl6]-octahedra is significantly smaller than in [OsCl6]2− , in accordance with vibrational spectra. [(n -C4H9)4N]2 [Os2Cl10] crystallizes in the orthorhombic space group Pbca with a = 15 .496 (2), b = 15 .965 (3), c = 19 .431(3) Å and contains centrosymmetric [Os2Cl10]2− ions with approximate D2h symmetry. Within the edge-sharing [OsCl6] octahedra the mean terminal and bridging Os -Cl bond lengths are 2.307 and 2.411 Å , respectively.