Le diméthyl- et le diéthyl-tétracarbonylosmium Synthèse et réactivité |
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| Authors: | F L'Eplattenier Mlle C Plichet |
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| Institution: | F. L'Eplattenier,Mlle C. Pélichet |
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| Abstract: | The sodium salt Na2Os(CO)4] has been obtained in high yields by the reduction of either OsH2(CO)4 or Os3(CO)12 with sodium sand in the presence of catalytic amounts of 2, 2′-bipyridyle. The reaction of Na2Os(CO)4] with alkylating agents such as methyl and ethyl iodide produces OsR2(CO)4 (R = CH3, C2H5). NMR. and IR. spectra indicate a cis-octahedral structure of symmetry C2v for these new alkyl compounds. Bromine breaks one osmium-carbon bond in cis-Os(CH3)2(CO)4 to give cis-OsCH3Br(CO)4, whereas in cis-Os(C2H5)2(CO)4 both ethyl groups are easily displaced by bromine to give cis-OsBr2(CO)4. Under CO pressure and at elevated temperature cis-Os(CH3)2(CO)4 is converted to Os(CO)5 and ethane. With cis-Os(C2H5)2(CO)4 two CO are inserted in osmium-carbon bonds to give  . NMR. and IR. data suggest a cis-configuration for this derivative and the possibility of the presence of rotational isomers. |
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