Stabilization of carbonium ions in the vicinity of metallocene nuclei
A remarkable stabilization imparted to a carbonium ion by an adjacent metallocene nucleus has been demonstrated by a solvolytic study of substituted metallocenylcarbinyl acetates. The solvolysis mechanism has be shown to be to be an uncatalyzed alkl-oxygen fission of the neutral ester by a study of...
| Summary: | A remarkable stabilization imparted to a carbonium ion by an adjacent metallocene nucleus has been demonstrated by a solvolytic study of substituted metallocenylcarbinyl acetates. The solvolysis mechanism has be shown to be to be an uncatalyzed alkl-oxygen fission of the neutral ester by a study of the hydrolysis under a variety of conditions and by determination of the products from the ethanolyses. Participation of the metal in the solvolyses by direct bonding between the metal and the incipient carbonium ion center is indicated by the effects of simple substituents by the effect of joining the rings by a three-carbon bridge, by the solvolysis of the acetate vinylogous to methylferrocenylcarbinyl acetate and by the stereochemistry of the solvolyses of derivatives with substitution in the 2-position of the ferrocene nucleus. A plausible molecular orbital model for such participation has been suggested in qualitative terms.
Spectra of the ferrocene derivatives prepared in this study are correlated and discussed. Evidence is presented which demonstrates intramolecular hydrogen bonding to the metal atom in substituted metallocenylcarbinols, and which indicates that the rings of l,l'- trimethyleneferrocene are tilted. |
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