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Cyclopentadienyliron complexes arenes

Various first-generation dendrimers and star-shaped molecules were generated from the nucleophilic aromatic substitution of chlorosubstituted arenes coordinated to cyclopentadienyliron complexes (Schemes 2.68 and 2.69). These compounds contained either ether or ester bridges. The star-shaped molecules prepared with ether bridges showed a decrease in solubility with an increase in star size, whereas the incorporation of ester bridges resulted in a decrease... [Pg.101]

Star-shaped molecules containing cationic arene complexes of iron and ruthenium have been reported by Astruc and co-workers.298 Utilizing the activating nature of the cyclopentadienyliron moiety on the complexed arene, 260 was converted into 262 via bromobenzylation. The photolysis of 262 gave 263, which was subsequently reacted with 264 to give the hexametallic complex 265. Further nucleophilic aromatic substitution reactions with phenol 266 gave the allyl-substituted complex 267 (Scheme 2.70). [Pg.103]

A number of research groups have reported the preparation of a large number of star-shaped molecules and dendrimers containing ferrocenyl or arene cyclopentadienyliron complexes at the core or the peripheries.300-320 A number of these dendrimers were prepared via cyclopentadienyliron-mediated per-alkylation, -benzylation and -allylation reactions of cationic tri-, tetra- and hexamethylbenzene complexes. These dendrimers were multifunctional materials and have been used in the synthesis of branched organic and organometallic polymers. [Pg.104]

Star and dendrimer core molecules were prepared by the peralkylation or allylation of cyclopentadienyliron complexes containing methyl-substituted arenes.298,301,302,304-311,333 The preparation of water-soluble metallodendrimers containing six cationic cyclopentadienyliron moieties, 281, has also been reported.301 Dendrimer 281 was tested for potential use as a redox catalyst for the cationic reduction of nitrates and nitrites to ammonia. [Pg.111]

Astruc and coworkers have reported the synthesis of highly branched polymers coordinated to cyclopentadienyliron and pentamethylcyclopentadienyl-ruthe-niiun cations." The catalytic and sensing ability of star polymers and dendrimers has also been reviewed. Multifunctional core molecules suitable for the synthesis of star and dendritic materials were synthesized by peralkylation or aUylation of methyl-substituted arene complexes of cyclopentadienyliron." The benzylic protons on these complexed arenes are acidic, which permits their facile alkylation. These branched polymers contained cationic cyclopentadienyliron moieties at the core and/or the periphery. The synthesis of a water-soluble metallodendrimers... [Pg.126]

Star-shaped polyaromatic ethers complexed with cyclopentadienyliron cations (92) have been prepared, in which the metallic moieties are evenly spaced throughout the length of the macromolecular branches (Scheme 24). By altering the nature of the aromatic spacers between the complexed arenes, it was possible to alter the properties of these materials. Electrochemical analysis of these polymers demonstrated that the iron centers underwent reversible reduction processes. For the hexa-metallic stars (n=l), two distinct redox couples were observed at , /2=-1.20 and-1.30 V... [Pg.127]

Astruc has also reported the use of arene complexes of iron and ruthenium in the design of star-shaped complexes. The cyclopentadienyliron moiety in 93 (Scheme 25) was utilized to activate the complexed arene toward bromobenzyla-tion to produce 95. Following photolytic demetallation, 96 was reacted with 97 to yield the /jexa-metallic complex 98. These complexed arenes were then subjected to nucleophilic aromatic substitution reactions with 99 allowing for the isolation of 100. [Pg.129]

Arenes, on complexation with Cr, Fe, Mn, and so forth, acquire strongly electrophilic character such complexes in reactions with nucleophiles behave as electrophilic nitroarenes.71 Synthesis of aromatic nitriles via the temporary complexation of nitroarenes to the cationic cyclopentadienyliron moiety, cyanide addition, and oxidative demetalation with DDQ has been reported (Eq. 9.43).72... [Pg.316]

Reduction of arene-Tr-cyclopentadienyliron(II) cations, which are iso-electronic with the di-ir-cyclopentadienylcobalt cation, with lithium aluminium hydride yields the neutral arenecyclopentadiene-iron complexes (100) ... [Pg.92]

The requirement for AlCh adds some obvious limitations, but a modest number of substituted arenes have been successfully coordinated to the [FeCp]+ unit. Photoinduced arene exchange has been described43 and is particularly effective with the -r -chlorobenzene-r -cyclopentadienyliron cation without the need for Lewis acids.42 More basic (electron rich) arenes readily replace chlorobenzene, leading to FeCp cation complexes of O-phenylethyl-p-toluenesulfonate and variously substituted thiophenes.42 The charged complexes are not purified by conventional organic techniques, such as chromatography, but re-crystallization is possible. The complexes are very air and heat stable again, methods of removal of the arene from the Fe are few. The simplest is pyrolysis at >200 C.46... [Pg.521]

Scheme 2.71 shows the preparation of an octametallic star-shaped molecule containing cyclopentadienyliron arene complexes at the peripheries. The reaction of the organic core, 269, with the organometallic complex, 270, gave the organometallic star-shaped molecule, 271. A previously reported synthesis of 271 occurred via deprotonation of a permethylated iron complex. Astruc et al. have also reported silicon-containing star-shaped molecules, 272.312... [Pg.104]

The product > -cyclohexadienyl- / -cyclopentadienyliron(I) complexes such as XXXII are stable, soluble in non polar solvents and readily characterized ". The selectivity for the arene ligand (even, open) in preference to the cyclopentadienyl ring is consistent with prediction . The nucleophiles add to an unsubstituted position as before, and the regioselectivity in addition to monosubstituted arene ligands is variable, and is sometimes dependent on the reaction conditions ". With complex XXXIII, the )j -cyclo-hexadienyl species are obtained in 91% yield with the ratio o- m- p- of 89 7 4 . [Pg.198]

The ring-opening metathesis polymerization of norbomene monomers functionalized with arene complexes of cyclopentadienyliron has been reported using Grubbs catalyst. These polymerization reactions proceeded rapidly to produce the corresponding polynorbomenes (32 and 33). It was found that the incorporation of bulkier aromatic groups in the sidechains of these materials increased their glass transition temperatures and thermal stability. [Pg.16]

This chapter was intended to briefly introduce the types of organoiron polymers that have been developed since the early 1950s. Subsequent chapters in this volume will detail some of the advances that have taken place in recent years. The synthesis and properties of ferrocene-based polymers and polymers containing arene complexes of cyclopentadienyliron will be described. The properties and applications of some of these materials will be described, and the reader will hopefully gain an appreciation of organoiron polymers. [Pg.25]

The success associated with the controlled synthesis of aromatic ethers using arene complexes of cyclopentadienyliron makes this methodology attractive for the design of branched molecules. Reaction of complexes 1 and 21 with phloroglucinol (22) resulted in the isolation of trimetallic complexes 23 and 24 in 78-90% yields as yellow and beige solids, respectively (Scheme Complex 23 is an excellent... [Pg.206]

Polymerization of Olefinic Monomers Functionalized with Cationic Cyclopentadienyliron Arene Complexes... [Pg.233]

We have reported that norbornene monomers functionalized with arene complexes also undergo ring-opening metathesis polymerization to produce the corresponding cyclopentadienyliron-coordinated polynorbomenes. Scheme 13 shows the synthesis of polymers containing aromatic ether sidechains functionalized with organoiron moieties. ... [Pg.259]

It was also possible to design norbomene monomers functionalized with two cyclopentadienyliron arene complexes. " Scheme 15 shows the synthesis of complex 36 via reaction of the diiron complex 9 with endo,exo-5-norhomene-2-methanol (35). While this monomer could itself be ring-opened, it could also be reacted with various phenolic compounds (37a-c) to produce longer aromatic ether spacers. [Pg.262]

Arene cyclopentadienylmetal and arene metal carbonyl complexes are two other classes of materials that are metallocene-like in structure. The first report of the synthesis of tiie T) -mesitylene-Ti -cyclopentadienyliron cation in 1957 by Coffield et al. was a seminal event in this research field. However, it was the 1985 report on the polymerization of T -dichlorobenzene-Ti -cyclopentadienylruthenimn with diphe-nohc compounds, forming compounds such as 10, by Segal that caused research in this area to expand. [Pg.6]

On irradiation, the arene ligand is lost and the coordina-tively unsaturated complex, 111, is formed. If the photolysis takes place in the presence of an epoxide monomer. 111 ligates to three molecules of the monomer to form 112. Epoxide polymerization begins within the coordination sphere of the iron atom of 112 and then proceeds outward. Experimental evidenceusing ethylene oxide as a monomer appears to confirm this conclusion. The quantum yields for the photolysis of these rj -cyclopentadienyliron(II) salts do not appear to have been measured. [Pg.946]


See other pages where Cyclopentadienyliron complexes arenes is mentioned: [Pg.14]    [Pg.14]    [Pg.86]    [Pg.1017]    [Pg.3]    [Pg.207]    [Pg.230]    [Pg.234]    [Pg.235]    [Pg.258]    [Pg.69]    [Pg.1016]    [Pg.174]    [Pg.186]    [Pg.191]    [Pg.174]   
See also in sourсe #XX -- [ Pg.13 , Pg.14 , Pg.15 , Pg.16 , Pg.17 , Pg.18 ]




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Arene complexe

Arene complexes

Arenes complexes

Cyclopentadienyliron complexes

Dendrimers cyclopentadienyliron arene complexes

Polymerization of Olefinic Monomers Functionalized with Cationic Cyclopentadienyliron Arene Complexes

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