Low-Energy Electronic Absorptions in 17-Electron Organometallic Piano Stool Radicals

Atwood, Christopher G.; Geiger, William E.

doi:10.1021/ja00102a086

Cited by 51 publications

(33 citation statements)

References 4 publications

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“…4000 cm À1 with a very low intensity (100 L mol À1 cm À1 ) (Fig. 6) [81,82]. The predictions of intramolecular interactions in 7 discussed within the electrochemical part (vide supra) are validated with these results.…”

Section: Spectroelectrochemistrysupporting

confidence: 64%

1-Cyano-1′-ethynyl-ferrocene: Synthesis and reaction chemistry

Strehler

Korb

Poppitz

et al. 2015

Journal of Organometallic Chemistry

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Section: Spectroelectrochemistrysupporting

confidence: 64%

1-Cyano-1′-ethynyl-ferrocene: Synthesis and reaction chemistry

Strehler

Korb

Poppitz

et al. 2015

Journal of Organometallic Chemistry

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“…Additionally, a very weak excitation ( ϵ <100 L mol –1 cm –1 ) at λ = 2500 nm was detected, which can be assigned to the forbidden metal‐centered ligand‐field electronic transition (Figure 2). This excitation is a typical indication of the formation of a 17‐valence electron ferrocenium species 50,51. The absence of an intervalence charge‐transfer absorption is attributed to the structural properties of 2 excluding π conjugation and validates that mainly electrostatic interactions are responsible for the observed redox splitting between the equally charged redox centers in 2 n + ( n = 2, 3, 4).…”

Section: Resultsmentioning

confidence: 53%

Si(OCH₂Fc)₄: Synthesis, Electrochemical Behavior, and Twin Polymerization

et al. 2015

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The preparation and twin polymerization of the twin monomer Si(OCH 2 Fc) 4 [Fc = Fe(η 5 -C 5 H 4 )(η 5 -C 5 H 5 )] (2) by the reaction of FcCH 2 OH (1) with SiCl 4 in the presence of pyridine was explored. The electronic properties of 2 were investigated by cyclic voltammetry, square-wave voltammetry, and UV/Vis/near-IR spectroelectrochemistry, which showed a redox separation caused by electrostatic repulsion. Thermally induced condensation of 2 is characteristic, as evidenced by differential scanning calorimetry (DSC) and thermogravimetry coupled mass spectrometry (TG-MS). Upon heating 2 to 210°C, twin polymerization occurred and a hybrid material was formed that showed similarities with known systems derived from 2,2Ј-spirobi[4H-1,3,2-benzodioxasiline] (SBS), such as the nanopatterning of the formed silicon dioxide, which is characteristic for twin polymerization. Electron microscopy of this material revealed the ab-[a]

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“…With this in mind, 3,4‐diferrocenyl‐ N ‐phenylpyrrole ( 3a ) and 3,4‐diferrocenyl‐ N ‐tosylpyrrole ( 3b ) could be classified as weak coupled class II systems according to Robin and Day 29. Hence spectroelectrochemical investigations show the influence of the position of ferrocenyl groups on the intervalence charge transfer through the N ‐phenylpyrrole, thus demonstrating that the 2,5‐position is more suitable to facilitate electron transfer 25,28,30…”

Section: Resultsmentioning

confidence: 82%

“…The forbidden metal‐centered ligand‐field (LF) electronic transition usually occurs at approximately 4000 cm –1 with a very low intensity (generally close to 100 L mol –1 cm –1 ) (Figure 5). 27,28 The LMCT and LF transition can be described very well by Gaussian‐shaped functions by using the method of deconvolution (Figure 5). Considering that the experimental graph is described by two Gauss functions (Table 3), the extinction should tend to zero in the region between 5000 and 7000 cm –1 .…”

Section: Resultsmentioning

confidence: 99%

3,4‐Ferrocenyl‐Functionalized Pyrroles: Synthesis, Structure, and (Spectro)Electrochemical Studies

et al. 2014

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The synthesis of 3,4-diferrocenyl-substituted pyrroles of the type 3,4-Fc 2 -cC 4 H 2 NR [Fc = Fe(η 5 -C 5 H 4 )(η 5 -C 5 H 5 ); R = Ph (3a), SO 2 -4-MeC 6 H 4 (Ts) (3b), SiiPr 3 (3c)], 3,4-(FcCϵC) 2 -cC 4 H 2 NR [R = Ph (4a), Ts (4b)], and 3-Br-4-FcCϵC-cC 4 H 2 NR [R = Ph (7a), Ts (7b)] from 3,4-Br 2 -cC 4 H 2 NR [R = Ph (2a), Ts (2b), SiiPr 3 (2c)] is discussed. The molecular structures of 3a,b, 5, 4b, and 7b in the solid state are reported and show that the formal double bonds in the heterocyclic core are IntroductionRecent investigations on diverse isomeric ferrocenylfunctionalized five-membered heterocycles including furan, [1,2] thiophene, [1,2] pyrrole, [1,2] phosphole, [3a] and maleimides, [3b,3c] as well as titana- [4] and zircona-cycles [5] as model compounds to explain the electronic communication across π-conjugated linking units in redox-active organometallic molecules have been performed, since these species can be understood as building blocks for electronic wires. [6,7] The 2,5-functionalization is the most investigated substitution pattern for heterocyclic compounds, [2,3,[7][8][9] which is explainable by their straightforward accessibility. Super-crowded tetraferrocenyl five-membered heterocycles of thiophene and NR-pyrroles (R = Me, Ph) with their ferrocenyl substituents possess four reversible Fc/Fc + redox events, thus indicating that all ferrocenyl groups can be oxidized separately. The electrochemical and spectroelectrochemical (UV/Vis-NIR, IR spectroscopy) properties of these species were studied. [3,10] In particular, the electronic communication between the redox-active ferrocenyls, depending on the different substitution pattern, has been investigated on the example of thiophene-bridged systems. It was found that the degree of intermetallic interaction decreases from the 2,5-to the 2,3-, 2,4-, and 3,4-functionalization. [11] Nevertheless, the differences, especially within the electrochemical data, between the different substitution pat- [a] 1051 rather localized relative to pyrrole itself. The investigations with (spectro)electrochemical methods reveal the different capabilities for the formation of mixed-valent species and allows the classification of 3a,b as class II systems, whereas compounds that feature electron-withdrawing -CϵC-units (4a,b) can be assigned to class I systems according to Robin and Day.

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Low-Energy Electronic Absorptions in 17-Electron Organometallic Piano Stool Radicals

Cited by 51 publications

References 4 publications

1-Cyano-1′-ethynyl-ferrocene: Synthesis and reaction chemistry

1-Cyano-1′-ethynyl-ferrocene: Synthesis and reaction chemistry

Si(OCH₂Fc)₄: Synthesis, Electrochemical Behavior, and Twin Polymerization

3,4‐Ferrocenyl‐Functionalized Pyrroles: Synthesis, Structure, and (Spectro)Electrochemical Studies

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Low-Energy Electronic Absorptions in 17-Electron Organometallic Piano Stool Radicals

Cited by 51 publications

References 4 publications

1-Cyano-1′-ethynyl-ferrocene: Synthesis and reaction chemistry

1-Cyano-1′-ethynyl-ferrocene: Synthesis and reaction chemistry

Si(OCH2Fc)4: Synthesis, Electrochemical Behavior, and Twin Polymerization

3,4‐Ferrocenyl‐Functionalized Pyrroles: Synthesis, Structure, and (Spectro)Electrochemical Studies

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Si(OCH₂Fc)₄: Synthesis, Electrochemical Behavior, and Twin Polymerization