Metal−Metal Interactions in Weakly Coupled Mixed-Valence <i>E</i>- and <i>Z</i>-Diferrocenylethylene Complexes

Chen, Yuan-Jang; Pan, Dung-Shien; Chiu, C. P.; Su, Jiaxin; Lin, She Jing; Kwan, Keh Shin

doi:10.1021/ic991084j

Cited by 54 publications

(20 citation statements)

References 26 publications

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“…From these values, the equations (2) and (7) lead to the determination of H ab and λ (136 cm −1 and 6127 cm −1 respectively) for [Cu II 4(L) n ] 2+ . The value found for H ab is comparable to the reported data for weakly-coupled diferrocenyl mixed-valence complexes [38,41,55]. Equation (5) allows the determination of the theoretical bandwidth value ((∆ν 1/2 ) theo = 3762 cm −1 ).…”

Section: One and Two-electron Oxidation Of The Diferrocenyl Cu Complesupporting

confidence: 84%

“…Compound 4 bearing a vinyl spacer between mono-substituted and di-substituted ferrocenyl moieties, is a typical example. In UV-Vis, it absorbs at λ max = 458 nm, a value which is close to that found for other bis-ferrocenyl complexes bearing a vinyl spacer [38,41]. The shift of the wavelength compared to the mono-ferrocenyl compounds is best explained by the presence of this spacer which allows an electronic conjugation, thus a decrease of the energy gap (i.e.…”

Section: Synthesis and Characterization Of The Ligands (1-4)supporting

confidence: 78%

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Electron transfer properties of mono- and diferrocenyl based Cu complexes attached as self-assembled monolayers on gold electrodes by “self-induced” electroclick

Orain

Poul

Mest

et al. 2013

Journal of Electroanalytical Chemistry

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Two new Cu complexes bearing a 6-ethynyl bis-(methyl-pyridyl)amine (6eBMPA) moiety, as an electroclickable function linked to a ferrocenylbased triazolyl arm (ligands 3 and 4) have been synthetized and characterized by UV-Visible, EPR spectroscopies and cyclic voltammetry in acetonitrile. Two different spacer groups between the terminal ferrocene and the triazolyl group were inserted: an hexyl chain in the case of the complex Cu-3, an ethenyl-bridged diferrocenyl system for the complex Cu-4. The monoelectronic oxidation of the diferrocenyl species yields a stable mixed-valence complex. NIR-Visible spectroscopic studies show a moderate interaction between ferrocenyl units (class II according to the Robin-Day classification). The immobilization of these systems as SAMs on an azidoundecanethiol modified gold electrode has been successfully operated by using the "self-induced electroclick" procedure. The voltammetric characterization of the surface-tagged Cu complexes indicates that good surface coverage was achieved, with moderately fast electron-transfer reaction between the electrode and the redox active immobilized systems (k 0 (Cu) = 2-4 s −1 , k 0 (Fc) = 20-90 s −1). Remarkably, the rate of charge transport is significantly controlled by the nature of the spacer on the ferrocenyl triazole arm.

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Section: One and Two-electron Oxidation Of The Diferrocenyl Cu Complesupporting

confidence: 84%

Section: Synthesis and Characterization Of The Ligands (1-4)supporting

confidence: 78%

Electron transfer properties of mono- and diferrocenyl based Cu complexes attached as self-assembled monolayers on gold electrodes by “self-induced” electroclick

Orain

Poul

Mest

et al. 2013

Journal of Electroanalytical Chemistry

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“…[32][33][34] The appearance of only one redox event suggests negligible electrochemical communication between the ferrocene units (class I compounds according to Robin-Day [35] ). This is possibly due to the perpendicular orientation of the p orbital at boron towards the conjugated spacer-system, thus insulating it from the ferrocene moieties.…”

mentioning

confidence: 99%

Unexpected Generation of Diastereomers by Double Diboration of a Dialkyne

Bauer

Braunschweig

Gruß

et al. 2011

Chemistry A European J

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During the last two decades, boron compounds have become established as versatile reagents in organic synthesis, and different methods have been developed for their preparation. Along with hydroboration, [1][2][3][4] transition-metalcatalyzed diboration [5] has become useful for the functionalization of unsaturated organic compounds. [6,7] This reaction is widely applicable to substrates such as alkynes [8,9] arynes, [10] alkenes, [11][12][13] carbenoids, [14,15] as well as diazo [16] and carbonyl compounds. [17][18][19][20] Although bis(catecholato)diborane(4) and bis(pinacolato)diborane(4) represent by far the most commonly employed diborane(4) species, the reaction is not restricted to their use. For instance, several diboranes(4) with interesting properties are derived from [2]borametalloarenophanes. The first example of this class of organometallic compound, the [2]boraferrocenophane 1, was prepared by Herberhold, Wrackmeyer and co-worker, [21] while the molecular structure along with an alternative synthesis was published by our group.[22] Subsequently, a series of [2]borametalloarenophanes has appeared. [23-28b] These ansa complexes show tilted molecular structures, thus featuring significant molecular strain. In 2006, we successfully exploited this ring strain in oxidative addition reactions of [2]borametalloarenophanes to low-valent platinum centers, affording[3]diboraplatinametalloarenophanes. In addition, we demonstrated the suitability of [2]borametalloarenophanes as diboranes(4) in the platinum-mediated diboration of alkynes to form [4]diboradicarbametalloarenophanes.[29] By expansion of this strategy, we also achieved the diboration of diazo compounds [16] and isocyanides.[30]Herein, we report on the two diastereomeric [4]diboradicarbaferrocenophanes 4 and 5, which were obtained by double diboration of the conjugated dialkyne 3 either by a platinum-mediated route employing the [2]boraferrocenophane 1 in the presence of [PtA C H T U N G T R E N N U N G (PEt 3 ) 3 ], or stoichiometrically by using the [3]diboraplatinaferrocenophane 2, directly (Scheme 1). In contrast to related transformations of monoalkynes, [29] monitoring the reaction progress by multinuclear NMR spectroscopy revealed the gradual disappearance of the starting materials, and the formation of two distinct compounds in benzene solution at elevated temperatures. Both species feature similar resonances in the 1 H, 11 B, and 13 C NMR spectra, which we rationalized by the generation of diastereomeric species. Complexes 4 and 5 were eventually isolated after workup as orange, moderately moisture-sensitive powders. The NMR spectroscopic data of both diastereomers are fully consistent with the presence of doubly bis(borylated), conjugated triene systems bearing two ferro-

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“…First, there exists a large body of experimental data for diferrocenylpolyenes and their derivatives. The ET matrix elements have been explored with spectroscopic methods [30,33,34]; the metal-metal distance has been measured with x-ray crystallography [35,36] and estimated using a PC model [30]; and the effect of bridge substitution has been investigated [37]. Second, because of the complexity of the electronic structure of transition metal complexes, reliable quantum chemical modeling is difficult.…”

Section: Mixed-valence Diferrocenylpolyenesmentioning

confidence: 99%

A metric for characterizing the bistability of molecular quantum-dot cellular automata

Lent

2008

Nanotechnology

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Much of molecular electronics involves trying to use molecules as (a) wires, (b) diodes or (c) field-effect transistors. In each case the criterion for determining good performance is well known: for wires it is conductance, for diodes it is conductance asymmetry, while for transistors it is high transconductance. Candidate molecules can be screened in terms of these criteria by calculating molecular conductivity in forward and reverse directions, and in the presence of a gating field. Hence so much theoretical work has focused on understanding molecular conductance. In contrast a molecule used as a quantum-dot cellular automata (QCA) cell conducts no current at all. The keys to QCA functionality are (a) charge localization, (b) bistable charge switching within the cell and (c) electric field coupling between one molecular cell and its neighbor. The combination of these effects can be examined using the cell-cell response function which relates the polarization of one cell to the induced polarization of a neighboring cell. The response function can be obtained by calculating the molecular electronic structure with ab initio quantum chemistry techniques. We present an analysis of molecular QCA performance that can be applied to any candidate molecule. From the full quantum chemistry, all-electron ab initio calculations we extract parameters for a reduced-state model which reproduces the cell-cell response function very well. Techniques from electron transfer theory are used to derive analytical models of the response function and can be employed on molecules too large for full ab initio treatment. A metric is derived which characterizes molecular QCA performance the way transconductance characterizes transistor performance. This metric can be assessed from absorption measurements of the electron transfer band or quantum chemistry calculations of appropriate sophistication.

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Metal−Metal Interactions in Weakly Coupled Mixed-Valence E- and Z-Diferrocenylethylene Complexes

Cited by 54 publications

References 26 publications

Electron transfer properties of mono- and diferrocenyl based Cu complexes attached as self-assembled monolayers on gold electrodes by “self-induced” electroclick

Electron transfer properties of mono- and diferrocenyl based Cu complexes attached as self-assembled monolayers on gold electrodes by “self-induced” electroclick

Unexpected Generation of Diastereomers by Double Diboration of a Dialkyne

A metric for characterizing the bistability of molecular quantum-dot cellular automata

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