Search results for "Ferrocene"
showing 10 items of 306 documents
Compensation of steric demand by cation–π interactions, cobaltocenium cations as guests in tetraurea calix[4]arene dimers
2003
The affinities of ferrocene (2) and the cobaltocenium cation (3+), which have roughly the same size and differ in their charge, towards the inner cavity of the dimeric capsule formed by tetraurea calix[4]arene (1) were studied in C2D4Cl2 solutions. While 3+, which occupies more than 75% of the internal volume of the dimer, is readily encapsulated this is not the case for 2. This is probably due to cation-pi interactions, which operate only between 3+ and the aromatic rings of the calix[4]arene dimer. We found that the affinity of the cobaltocenium cation is higher than that of the tropylium cation (4+) and is only 2-3 times less than that of the tetraethylammoniun cation (5+). From the vari…
Aminomethyl-Substituted Ferrocenes and Derivatives: Straightforward Synthetic Routes, Structural Characterization, and Electrochemical Analysis
2013
A variety of aminomethyl-substituted ferrocenes and the parent compounds (iminomethyl)ferrocenes, azaferrocenophanes, and diferrocenylamines can be selectively synthesized from reductive amination of 1,1′-diformylferrocene or formylferrocene. The optimized one- or two-step reactions have delivered 13 new compounds, isolated in 65–97% yields, which include tertiary (ferrocenylmethyl)amines and azaferrocenophanes by using NaBH(OAc)3 as a mild reducing agent and (iminomethyl)ferrocenes and secondary (ferrocenylmethyl)amines by using LiAlH4. X-ray structures of representative members of these ferrocene derivative families have evidenced the preferred conformation adopted by ferrocene backbones,…
Gold(I) Complexes of Ferrocenyl Polyphosphines: Aurophilic Gold Chloride Formation and Phosphine-Concerted Shuttling of a Dinuclear [ClAu···AuCl] Fra…
2016
International audience; A smart steric control of the metallocene backbone in bis- and poly(phosphino)ferrocene ligands favors intramolecular aurophilic interactions between [AuCl] fragments in polynuclear gold(I) complexes. We synthesized and characterized by multinuclear NMR and X-ray diffraction analysis mono-, di-, and polynuclear gold complexes of constrained ferrocenyl diphosphines, which bear either bulky tert-butyl groups or more flexible siloxane substituents at the cyclopentadienyl rings. The complexes meso-1,1'-bis-(diphenylphosphino)-3,3'-di-tert-butylferrocene (4-m), rac-1,1'-bis[bis-(5-methy1-2-furyl)phosphino]-3,3'-di-tert-butyfferrocene (5-r), and rac-1,1'-bis ( diphenylphos…
Planar-Chiral 1,1 '-Diboryl Metallocenes: Diastereoselective Synthesis from Boryl Cyclopentadienides and Spin Density Analysis of a Diborylcobaltocene
2017
International audience; The reaction of nonsubstituted alkali metal cyclopentadienides with haloboranes leads to similar to 90:10 mixtures of isomeric diene products that can be deprotonated to give simple boryl cyclopentadienides. We extended this transformation to the sterically hindered lithium tert-butylcyclopentadienide 1 using FBMe(s)2 (Mes = 2,4,6-trimethylphenyl) and ClBCy2 as electrophiles. The boryl group is selectively introduced in the remote position to minimize steric congestion. The new boryl dienes are obtained as mixtures of isomers, and subsequent deprotonation with MeLi or LiHMDS affords the lithium 1,3-disubstituted cyclopentadienides Sa,b in yields over 95%. Direct asse…
Performances of symmetrical achiral ferrocenylphosphine ligands in palladium-catalyzed cross-coupling reactions: A review of syntheses, catalytic app…
2007
Abstract Ferrocene derivatives bearing donor atoms led to the generation of several classes of metallo-ligands, which collectively show an impressive diversity of applications, especially in metal-catalyzed modern organic reactions. Based on the impetus provided by the use of the diphosphine 1,1′-bis(diphenylphosphino)ferrocene (dppf) the investigations directed towards the synthesis of new ferrocenylphosphines remain of fundamental and industrial interest. The present review aims to describe the performances in palladium-catalyzed cross-coupling reactions of symmetrical achiral ferrocenylphosphine ligands, mainly diphosphines. We specifically choose to restrict our review efforts to these …
Synthesis and reactivity of P-ferrocenylalkylidenephosphanes and related iminophosphanes and diphosphenes
1997
P-Ferrocenyl-substituted alkylidenephosphanes have been prepared and characterized spectroscopically. Their ready conversion to the corresponding acylphosphanes and 1,2-diacyldiphosphanes, as well as a new type of phosphirene synthesis are presented. The X-ray structure of the tetraferrocenyl-substituted diacyldiphosphane has been investigated. Furthermore, P-ferrocenyl iminophosphanes and their complexation behaviour are described. Diferrocenyldiphosphene, which is known to be unstable, has been stabilized by complexation; this has been confirmed by NMR-spectroscopy and X-ray structure analysis.
Converging and Diverging Synthetic Strategies to Tetradentate (N,N′)-Diaminomethyl,(P,P′)-Ferrocenyl Ligands: Influence of tert-Butyl Groups on Ferro…
2015
Hexasubstituted hybrid tetradentate (N,N′,P,P′)-ferrocenes bearing phosphino and aminomethyl groups, plus hindering tert-butyl moieties, were synthesized by using two different strategies: a “diverging” synthesis involving successive functionalization of preformed di-tert-butylated ferrocene and a “converging” assembly of the species from appropriately substituted cyclopentadienyl rings. While the new cyclopentadienyl salts formed are of interest, their assembly with iron dichloride used as a “converging” way to produce tetradentate ferrocene ligands presented several drawbacks. Conversely, the synthesis of new tert-butylated (aminomethyl)ferrocene derivatives was found convenient to furthe…
Highly Functionalized Ferrocenes
2020
International audience; Ferrocene is unique among organometallic compounds, and serves notably as a versatile platform towards the production of ligands useful to promote transition metals chemistry. A general limiting aspect of the synthesis of ferrocene derivatives is the efficient access to sophisticated highly functionalized polysubstituted ferrocenes, i. e. bearing four or more substituents replacing hydrogen atoms on the cyclopentadienyl rings. These ferrocene derivatives can bear various functional or/and structuring spectator substituents. Their preparation involves synthetic difficulties resulting from the need of multiple functionalizations coexisting altogether, and satisfying fu…
Hindering the formation of ferrocenes: mono(cyclopentadienyl)halo iron complexes [Fe(C5R5)X] containing a sterically bulky cyclopentadienyl ligand
2001
Abstract The reaction of lithium 1,2,4-tris(trimethylsilyl)cyclopentadienide Li(Si 3 Cp) with ferrous halide FeX 2 (X=Cl, Br, I) in THF at −95 °C gives a thermally extremely sensitive compound that can be regarded as a functional equivalent for the 14-electron fragment [Fe(Si 3 Cp)X]. Experiments to trap this species with TMEDA gives thermally sensitive, colorless, paramagnetic crystals of the composition [LiFe(Si 3 Cp)Cl 2 (TMEDA) 3 ]. Trimethylphosphite gives isolable 18-electron half-sandwich complexes [Fe(Si 3 Cp){P(OMe) 3 } 2 X]. [Fe(Si 3 Cp)X] is also formed by reducing the ferric derivative [Fe(Si 3 Cp)Cl 2 ] with zinc. Analogous reactivity towards ferrous halides is observed for the…
A New Valence Tautomerism Example in an Electroactive Ferrocene Substituted Triphenylmethyl Radical
2003
A new molecular system combining an open-shell organic radical that acts as an acceptor group, different from an o-quinone moiety, covalently linked to a ferrocene moiety, acting as the donor group, is shown to exhibit valence tautomerism.