SYNTHESIS, CRYSTAL-STRUCTURE, VIBRATIONAL -SPECTRA, AND NORMAL-COORDINATE ANALYSIS OF [OS(ACAC)(3)]

In the reaction of K-2[OsCl6] with boiling water/acetylacetone (1:1) a mixture of different chloro-acetylacetonato complexes is formed, from which [Os(acac)(3)] can be isolated by column chromatography with dic hloromethane on silica gel. The crystal structure of [Os(acac)(3)] (mo noclinic, space group P2(1)/c, a = 13,968(5), b = 7,517(5), c = 16.455 (5) Angstrom, beta = 98.939(5)degrees, Z = 4) has been determined by s ingle crystal X-ray diffraction analysis. High resolution IR and Raman spectra were measured at low temperature (10 K). Based on the molecul ar parameters of the X-ray structure determination a normal coordinate analysis has been performed and the normal modes of vibration have be en assigned. With a set of 32 force constants, taking into account the intraligand vibrations, a good agreement between observed and calcula ted frequency has been achieved. The valence force constants are f(d)( OsO) = 3.19 and f(d)(OC) = 6.74 mdyn/Angstrom.