First Name:
Louis
Last Name:
Martin
Major Department:
Biology
Thesis Director:
Dale Wheeler
Date of Thesis:
May 2010
Organometallic materials with large molecular polarizabilities exhibit nonlinear optical properties and therefore, have potential uses in photonic devices, optical information processing/storage, and telecommunications. Previous research in Prof. Wheeler's lab has isolated para-substituted ferrocenylimine, FcCH=N-C6H4X-p (where X is an electron withdrawing or donating group; ie Cl, CH3, NO2) with C=N as the connecting bridge (Wheeler et al. 2002 and 2010).1,2 This research expands upon the previous findings by replacing the C=N bridge with a planar C=C (vinyl) bridge. The goal of this project is to synthesize a class of seven vinylferrocene derivatives, FcCH=CHC6H4X-p (where X= H, CN, CH3, N(CH3)2, NO2, Cl, OCH2CH3) and to characterize them using IR, 13C and 1H NMR, and UV-vis spectroscopy.
Initially, a phase transfer adaptation of Wittig's reaction (Wittig 1951 and 1956) 3,4 was used for the synthesis of the vinylferrocenes. Ferrocenecarboxaldhyde, FcCHO, was reacted with 10% excess of the Wittig reagent in methylene chloride and 50/50 KOH/H2O. Alternately, "green" chemistry methods were also pursued. Ferrocenecarboxaldhyde was reacted with 10% excess of the Wittig reagent and ground in an open mortar with a small excess of KOH. The vinylferrocene products were extracted from the reaction mixture and solvents were removed by vacuum.
Cis and trans isomers were further purified using column chromatography on an alumina or silica gel column with petroleum ether or hexanes. Trans isomers were typically isolated by recrystallization in petroleum ether and dried in a vacuum desiccator prior to metalation. Recrystallization in petroleum ether was an effective way to separate trans isomers. Trans isomers were reacted with the metalating agent, (CH3CN)3RuCp*+ OTf - in either anhydrous methylene chloride or anhydrous DMSO in a dry nitrogen atmosphere. The metalated product was precipitated with diethyl ether and the product dried under vacuum. Metalation of the benzyl derivative, FcCH=CH-C6H5 (V), was successful when methylene chloride was used as the solvent. Metalation attempts of other vinylferrocenes in DMSO were unsuccessful.