,-Diferrocenyl Cumulene Molecular Wires Studied by Density Funct
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- 作者：Benno Bildstein ; Olga Loza ; and Yuri Chizhov
- 刊名：Organometallics
- 出版年：2004
- 出版时间：April 12, 2004
- 年：2004
- 卷：23
- 期：8
- 页码：1825 - 1835
- 全文大小：308K
- 年卷期：v.23,no.8(April 12, 2004)
- ISSN：1520-6041
文摘
Density functional theory calculations for neutral and oxidized diferrocenyldiphenylcumulenes, [Fc(Ph)Cn(Ph)Fc] with n = 2, 4, 6, 8, were performed at the B3LYP/6-31G levelwithout any restrictions in symmetry. Geometrically, of the four possible diasteromericstructures of the neutral cumulenes, no preferential conformation was revealed, and thecalculated structures reproduce the experimental X-ray structural data quite well. The spindensity of all mono- and dications is located on the iron atoms, but not on the cumulenechain. Calculations of the ionization potentials for monocations show a breakdown ofKoopmans' theorem. A calibration procedure was proposed for evaluation of vertical ionizationpotentials, resulting in values with experimental accuracy. UV-visible absorptions areassigned in terms of their band maximums, transition energies, and bandwidths on the basisof deconvoluted experimental spectra and on the basis of comparison with structurally relatedcompounds. Calculations of the characteristic high-frequency symmetric vibrations of thecumulene chain show a very good match with experimental Raman bands. Redox potentialsin solution are calculated by a simplified model on the basis of empirical findings; the resultsreproduce the experimental half-wave potentials quite satisfactorily and allow an estimateof an electrochemical decay slope and an effective conjugation limit in these cumulenemolecular wires. The structural, chemical, optical, electrochemical, and molecular orbitalproperties of 2-31 make ferrocenyl cumulenes very promising molecular objects with greatpotential in molecular-scale electronics in comparison with pure organic molecular wires.