Bridged ferrocenes—II

Barr, T.H.; Watts, William E.

doi:10.1016/s0040-4020(01)96343-4

Cited by 74 publications

(9 citation statements)

References 19 publications

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“…Therefore, clearly other factors must be taken into account in order to achieve a greater understanding of both redox and chromogenic effects. It has been suggested that Cp ring tilt, 18 Cp ring rotation 6b and Fe-metal interactions 17 affect the chromogenic properties of the ferrocene centre. For example, in the case of cryptand 7, an Fe-Ag ϩ interaction has been postulated to explain the enhanced chromogenic and redox response to complexation with this cation.…”

Section: Electrochemical Studiesmentioning

confidence: 99%

The effect of protonation on the spectroscopic and redox properties of a series of ferrocenoyl derivatives

Carr¹,

Coles²,

Hassan³

et al. 1999

J. Chem. Soc., Dalton Trans.

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Section: Electrochemical Studiesmentioning

confidence: 99%

The effect of protonation on the spectroscopic and redox properties of a series of ferrocenoyl derivatives

Carr¹,

Coles²,

Hassan³

et al. 1999

J. Chem. Soc., Dalton Trans.

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“…Thed iborene moiety in 3 was readily identified by its characteristic 11 BNMR signal at d = 28.4 ppm and its lowest energy UV/Vis absorption at l = 571 nm. [15][16][17][18][19][20][21] Furthermore, the 0.53 ppm chemical shift difference between the a and b protons of the Cp ring, which has been shown to provide aq ualitative correlation with the degree of molecular distortion in ansa metallocenes, [22] indicates notable ring strain (cf. 2: Dd = 0.21 ppm).…”

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confidence: 99%

Dibora[2]ferrocenophane: A Carbene‐Stabilized Diborene in a Strained cis‐Configuration

et al. 2016

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Metallocenes with bridged cyclopentadienyl ligands, commonly named ansa metallocenes or metallocenophanes, have emerged as a class of organometallic compounds with an exceptionally wide and diverse range of applications.[1] Among other applications, ansa metallocenes are employed as catalyst precursors in the industrial production of polyolefins [2] and as monomers for ring-opening polymerization to form functional metallopolymers.[3] Their versatility and usefulness stems largely from the fact that their physical properties, and hence reactivity, can be tuned through structural modifications of the ligand framework. For instance, unsaturated two-atom bridges have been developed to increase the configurational rigidity [4] as well as the molecular strain of metallocenophanes, but also to add additional functionality to the metallocene fragment. In part due to difficulties encountered in their synthesis, these types of bridges are relatively rare and only a handful of these have been successfully incorporated into the ferrocene structure, as shown in Figure 1 (I-V). The first examples involved bridging aromatic rings, such as an ortho-phenylene (I), [5,6] a cyclobutadiene cobalt (II) [6] and a ruthenacyclopentadiene fragment (III). [7] Whereas the focus of the initial studies was on synthesis and structural features, the vinylene-bridged dicarba[2]ferrocenophanes IV and V have been developed as candidates for ring-opening metathesis polymerization (ROMP) to produce conjugated metal-containing polymers. [8][9][10] As shown by the groups of Tilley and Manners, such strained ferrocenophanes can indeed undergo ROMP with Schrock-and Grubbs-type catalysts to form conjugated metallopolymers. [9,10] Although homo-and heteronuclear multiple bonding is common for other p-block elements, especially the second-period elements, [11] unsaturated ansa bridges in metallocenophanes are to date restricted to carbon. By capitalizing on the isoelectronic relationship between Lewis base-stabilized diborenes, [(L)RB=BR(L)] (L = Lewis base), [12,13] and olefins, R2C=CR2, we sought to prepare the first ansa metallocene with a heteroatomcontaining multiple bond in the bridge. Herein, we describe the successful synthesis of a strained dibora[2]ferrocenophane (VI), in which the bridging diborene moiety is forced to adopt a cis rather than the prevailing trans configuration. The effects of changing the regiochemistry, as well as the interrelationship between the strain and properties of the diborene are addressed.[a]Prof.

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“…Die Diboren-Einheit in 3 kann leicht durch das charakteristische 11 B-NMR-Signal bei d = 28.4 ppm und die energetisch niedrigste UV/Vis-Absorption bei l = 571 nm identifiziert werden. [15][16][17][18][19][20][21] Zudem zeigt die Differenz in der chemischen Verschiebung zwischen den aund b-Protonen des Cyclopentadienyl(Cp)-Rings (Dd = 0.53 ppm), die als probates Mittel zur Quantifizierung der Spannung in ansa-Metallocenen fungiert, [22] dass die Verbindung eine merkliche Ringspannung aufweist (2: Dd = 0.21 ppm).…”

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Dibora[2]ferrocenophan: ein carbenstabilisiertes Diboren in einer gespannten cis‐Konfiguration

et al. 2016

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Ungesättigte Brücken, die in gespannten ansa-Metallocenen zwei Cyclopentadienyl-Einheiten miteinander verbinden, sind äußerst selten und auf Kohlenstoff-Kohlenstoff-Doppelbindungen beschränkt. Die Synthese und Isolierung eines gespannten Ferrocenophans mit einer ungesättigten Brückea us zwei Boratomen, die isoelektronischm it einer C=C-Doppelbindung ist, wurde durch Reduktion eines carbenstabilisierten 1,1'-Bis(dihalogenboryl)ferrocens erstmals verwirklicht. Spektroskopische und elektrochemischeM essmethoden sowie DFT-Rechnungen wurden angewendet, um den Einfluss der beispiellosen, gespannten cis-Konfiguration auf die optischen und elektrochemischen Eigenschaften der carbenstabilisierten Diboren-Einheit zu untersuchen. Erste Reaktivitätsstudien zeigen, dass das Dibora[2]ferrocenophan anfällig fürdie Spaltung der Bor-Bor-Doppelbindung ist.Abbildung 1. Beispielev on Ferrocenophanen mit einer ungesättigten, zweiatomigen Brücke (R 1 ,R 2 = Ph oder CO 2 CH 3 ,L= Lewis-Base).

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Bridged ferrocenes—II

Cited by 74 publications

References 19 publications

The effect of protonation on the spectroscopic and redox properties of a series of ferrocenoyl derivatives

The effect of protonation on the spectroscopic and redox properties of a series of ferrocenoyl derivatives

Dibora[2]ferrocenophane: A Carbene‐Stabilized Diborene in a Strained cis‐Configuration

Dibora[2]ferrocenophan: ein carbenstabilisiertes Diboren in einer gespannten cis‐Konfiguration

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