| Abstrakt: |
Both stereoisomers of disiloxane-bis(1-indenyl)-ansa-ferrocene, Fe(η5-inden-1-yl-SiMe2)2O, 1, were prepared by the reaction of disiloxane-bis-1,3-inden-1-yl anion with FeCl2; the diastereomers were separated by column chromatography and recrystallized from n-heptane. A single-crystal X-ray diffraction study confirmed that each stereoisomer, racemic 1r and meso 1m, involves parallel bis-indenyl coordination to the Fe metal center. These isomers were also characterized by 1H, 13C, and 29Si NMR and IR spectroscopy. Compounds 1r and 1m could each be transformed into the other diastereomer: the conversion was retarded by base, but accelerated under weakly acidic conditions. The mechanism of this process, investigated using deuterium labeling experiments, is consistent with a series of successive 1,5-suprafacial, sigmatropic silicon shifts. Compound 1 was also copolymerized with 1,1,3,3,5,5,7,7-octamethylcyclotetrasiloxane (D4) and 1,1,1,3,3,5,5,5-octamethyltrisiloxane (MDM) to produce green organometallic polymers. |
