Intramolecular rearrangement of the bridging σ,π-acetylide ligand in the Os3H(CO)9(L)(μ-η2-CCPh) (L = CO,PMe2Ph) clusters and crystal structure of Os3H(CO)9(PMe2Ph)(μ-η2-CCPh) |
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Authors: | AA Koridze OA Kizas PV Petrovskii NE Kolobova YuT Struchkov AI Yanovsky |
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Institution: | A.N. Nesmeyanov Institute of Organoelement Compounds, Academy of Sciences, 28 Vavilov St., Moscow U.S.S.R. |
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Abstract: | Clusters Os3H(Cl)(CO)9(L) (L= CO, PMe2Ph) react with lithium phenyl-acetylide to yield Os3H(CO)9(L)(μ-η2-CCPh),which has a bridging acetylide ligand. The Os3H(CO)10(μ-η2-CCPh) complex (II) is fluxional owing to rapid π → σ, σ → π interchange of acetylide ligand between the bridged osmium atoms, whereas the phosphine-substituted derivative, Os3H(CO)9(PM2Ph)(μ-η2-CCPh) (III), is stereochemically rigid and exists at room temperature in two isomeric forms. These isomers have been isolated as solids and have been characterized by 1H and 31P{1H} NMR spectroscopy. According to the spectroscopic data, in the major (IIIa) and minor (IIIb) isomers the phosphine ligand is coordinated to the metal atom which is σ- or π-bonded to the bridging acetylide group, respectively. The isomerization of IIIb into IIIa occurs only at 80°C. The structure of IIIa has been confirmed by an X-ray diffraction study. |
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Keywords: | Author to whom correspondence should be addressed |
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