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Photogeneration and characterization of group 6 metal carbonyl derivatives on alumina
Ist Teil von
Polyhedron, 1997-01, Vol.16 (11), p.1937-1943
Ort / Verlag
Elsevier Ltd
Erscheinungsjahr
1997
Quelle
Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)
Beschreibungen/Notizen
The photochemically-induced CO substitution reactions of [M (CO)
6] (M = Cr, Mo, W) have been investigated in the presence of triphenylphosphine (PPh
3) and γ-alumina. The metal loading was determined by Rutherford backscattering spectrometry (RBS) and the generated species were analysed by Fourier transform IR spectroscopy (FT-IR) and
13C NMR spectroscopy. The metal loading on alumina surface was seen to increase with the irradiation time reaching 0.6, 0.8 and 3.4% for Cr, W and Mo, respectively. The ligand cone angle plays an important role in the case of Cr, where only the
trans disubstituted species was found on the alumina surface. However, it is less important for the two other metals, where the
cis compound was formed preferentially and the electronic
cis-labilization factor seems more important. After grafting, only the disubstituted species was seen to remain on alumina evidencing a stronger interaction with the support than in the case of the monosubstituted and the hexacarbonyl compounds.