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'Tetrahalooxalato osmates IV UV VIS Spectra' in keywords Facet   Publication Year 1980  [X]
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1Author    Heinrich Homborg, Wilhelm Preetz, Günes Barka, Gernot SchätzelRequires cookie*
 Title    Darstellung und spektroskopische Charakterisierung von Tetrahalogenooxalato-Osmaten(IY)  
 Abstract    Reaction of [OsXe] 2-(X = CI, Br, I) with oxalic acid in water gives the very stable and deeply coloured new complexes [OsX40x] 2-which can be precipitated as alkali or tetra-alkylammonium salts. The salts with long-chain alkylammonium ions are soluble in all common no polar solvents. The IR and Ra spectra and the depolarization ratios are consistent with the local C2v-symmetry. The coupling between the vibrations of co-ordinated oxalate and with the skeletal [OsX402]-modes is apparently small. The optical spectra have been studied at low temperature (10 K). Analogous to [OsXe] 2-the very intense absorptions in the UV and VIS are assigned to the electric dipole allowed electron transfer from "(jr+cr)tiu, 7rt2U(y7), 7it2u(y8) and (<r-f-7r)tiu" to "dt2g". By the descent in symmetry each of these transitions is further split in three components (Ai, Bi, B2) corresponding to the three different groups of ligands, X2 tr -, X2 C -and ox. The distinction between the X2 tr --*-Os and X2 C --> Os is caused by a static trans-effect and depends on the difference of the optical electronegativities induced by ox. This splitting is not observed for [OsCLiox] 2 -but is about 900 cm-* for [OsBr4ox] 2 -and 1200 cm" 1 for [OsI4ox] 2 -. The well defined bands in the NIR and VIS are assigned to the intraconfigurational d-d-transitions between the spin-orbit components in the octahedral doublegroup Oh* splitted by the lower C2v-symmetry. Some of the zero-phonon transitions within the split of the 3 Tig, Oh-groundstate exhibit extremely high intensities (e~2500 cm 2 /mmol). The assign-ment of these transitions is improved by the electronic Ra spectra. The finestructure of some of the d-d-transitions originates from coupling with Ai vibrational modes especially with Vs(C-O). 
  Reference    Z. Naturforsch. 35b, 554—563 (1980); eingegangen am 10. Dezember 1979 
  Published    1980 
  Keywords    Tetrahalooxalato-osmates(IV) UV-VIS Spectra, IR Spectra, Raman Spectra 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-0554.pdf 
 Identifier    ZNB-1980-35b-0554 
 Volume    35