Orbital Interactions in Fe(II)/Co(III) Heterobimetallocenes: Single versus Double Bridge
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- 作者：Ralf Warratz ; Gerhard Peters ; Felix Studt ; René ; -Hermann Rö ; mer ; and Felix Tuczek
- 刊名：Inorganic Chemistry
- 出版年：2006
- 出版时间：March 20, 2006
- 年：2006
- 卷：45
- 期：6
- 页码：2531 - 2542
- 全文大小：396K
- 年卷期：v.45,no.6(March 20, 2006)
- ISSN：1520-510X
文摘
Ferrocenyl cobaltocenium hexafluorophosphate (1) and ferrocenylene cobaltocenylenium hexafluorophosphate (2)are investigated by a range of spectroscopic methods. Both compounds are diamagnetic, in contrast to an earlierreport indicating a temperature-dependent paramagnetism of 2. Electronic absorption spectra of 1 and 2 are presentedand fully assigned up to 50 000 cm-1 on the basis of electronic structure (DFT) calculations and spectral comparisonswith ferrocene and cobaltocenium. The lowest-energy bands, I, of both 1 and 2 correspond to metal-to-metal CT(MMCT) transitions; further intermetallocene charge-transfer bands are identified at higher energy (bands III andV). On the basis of the spectroscopic properties, a trans geometry and a twisted structure are derived for 1 and2, respectively, in solution. Analysis of the I bands gives orbital mixing coefficients, 
, electronic-coupling matrixelements, VAB, and reorganization energies, 
. Importantly, and VAB are larger for 1 than for 2 (0.07 and 1200cm-1 vs 0.04 and ~600 cm-1, respectively), apparently in contrast to the presence of one bridge in 1 and twobridges in 2. This result is explained in terms of the respective electronic and geometric structures. Reorganizationenergies are determined to be 7600 cm-1 for 1 and 4600 cm-1 for 2, in qualitative agreement with the analogousFe(II)-Fe(III) compounds. The general implications of these findings with respect to the spectroscopic and electron-transfer properties of bimetallocenes are discussed.
, electronic-coupling matrixelements, VAB, and reorganization energies, . Importantly, and VAB are larger for 1 than for 2 (0.07 and 1200cm-1 vs 0.04 and ~600 cm-1, respectively), apparently in contrast to the presence of one bridge in 1 and twobridges in 2. This result is explained in terms of the respective electronic and geometric structures. Reorganizationenergies are determined to be 7600 cm-1 for 1 and 4600 cm-1 for 2, in qualitative agreement with the analogousFe(II)-Fe(III) compounds. The general implications of these findings with respect to the spectroscopic and electron-transfer properties of bimetallocenes are discussed.