Electronic structure, spectroscopy, and photochemistry of group 8 metallocenes
β Scribed by Yoshikazu Yamaguchi; Wei Ding; Cynthia T. Sanderson; Michelle L. Borden; Matthew J. Morgan; Charles Kutal
- Publisher
- Elsevier Science
- Year
- 2007
- Tongue
- English
- Weight
- 771 KB
- Volume
- 251
- Category
- Article
- ISSN
- 0010-8545
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β¦ Synopsis
Spectral and photochemical studies of ferrocene, ruthenocene, and several of their benzoyl-substituted derivatives have provided valuable information about the electronic structures and excited state reactivities of these group 8 metallocenes. The presence of a benzoyl group on one or both cyclopentadienyl rings of the metallocene strongly influences the electronic transitions observed in the UV-vis spectral region. While the parent complexes display low-intensity, solvent-insensitive ligand field absorption bands, the monobenzoyl and 1,1 -dibenzoyl derivatives exhibit bands that are much more intense and sensitive to the solution environment. This behavior results from the mixing of appreciable metal-to-ligand charge transfer (MLCT) character into the low-energy excited states of the benzoyl-substituted complexes. Resonance Raman data lend strong support to this MLCT assignment. Irradiation of a metallocene dissolved in ethyl 2-cyanoacrylate results in the anionic polymerization of the electrophilic monomer. Studies of the kinetics and mechanism of this photoinitiated polymerization process reveal that it occurs by two competing charge transferinduced pathways, the relative importance of which depends upon the identity of the metal and the presence or absence of the benzoyl substituent.
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