DarsteIlung und Schwingungsspektren des 13C- und 18O-Hiarkierten trans-Dioxotetracyanoosmats(VI), [OsO2(CN)4]2- / Preparation and Vibrational Spectra of 13C and 18O Labelled trans-Dioxotetracyanoosmate(VI), [OsO2(CN)4]2-

Abstract

Abstract Through careful acidification of the aqueous solution of [OsO2(OH)4]2- in the presence of CN- or 13CN- with acetic acid, [OsO2(CN)4]2- or [OsO2(12CN)4]2- are formed, respectively. The reaction of Os18O4 and tetrabutylammonium cyanide with glacial acetic acid in anhydrous methanol yields [Os18O2(CN)4]2- . The shifts of the infrared and Raman bands of the isotopically labelled complexes are in good agreement with Teller-Redlich calculations. The degenerate E modes, expected for tetragonal symmetry, are split by approx. 15 cm-1, indicating an orthorhombic distortion of the complex ion in the solid state. Therefore, all the observed IR- and Raman frequencies are assigned according to point group D2h. For the complex containing an 18O=Os=18O axis, the symmetry is lowered to C2v, and the rule of mutual exclusion is restricted. This results in a weak absorption in the infrared spectrum of the Raman active symmetric OsO stretching vibration and vice versa a weak band in the Raman spectrum for the antisymmetric infrared active mode.