- Sensing of the Induced Helical Chirality by the Chiroptical Response of the Ferrocene Chromophore
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The experimental (infrared, nuclear magnetic resonance, circular dichroism) and computational (density functional theory) methods allowed us to demonstrate the potential of the ferrocene chromophore to translate chiral information stored at N-terminally attached l-Ala, and transmitted through achiral (Aib)n sequence (n=1 to 3), into a characteristic signal in circular dichroism spectra near 470 nm. The sufficiently long tetrapeptide forms a robust and highly organized 310 helices capable of perturbing the environment of the highly symmetric ferrocene chromophore in an asymmetric manner. The origin of the sign in the circular dichroism spectra of the ferrocene chromophore (near the 470 nm) strongly correlates with the sign of the dihedral angle χ, accounting for a rotation of a substituent attached to the cyclopentadienyl ring that depends on the helicity of peptide sequence. These observations may help us in the design of future ferrocene-based probes for the assignment of the screw-sense preference of short peptides.
- ?utalo, Petar,Kodrin, Ivan,Nuskol, Marko,Semen?i?, Mojca ?aki?
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- Aluminum complexes with new non-symmetric ferrocenyl amidine ligands and their application in CO2 transformation into cyclic carbonates
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A set of alkyl aluminum complexes supported by non-symmetric ferrocenyl amidine ligands were used as catalysts for the preparation of cyclic carbonates from epoxides and carbon dioxide using Bu4NI as a co-catalyst. A modified method for the synthesis of aminoferrocene allowed us to obtain this precursor in quantitative yield. Treatment of aminoferrocene with the corresponding acetimidoyl chloride afforded the desired ferrocenyl amidine ligands L1H, (E)-N-(2,6-diisopropylphenyl)-N'-(ferrocenyl)acetimidamide, and L2H, (E)-N-(2,6-dimethylphenyl)-N'-(ferrocenyl)acetimidamide. The reaction of these ligands with 1.0 or 0.5 equiv. of AlMe3 led to the synthesis of aminoferrocene based aluminum complexes ((L1)AlMe2 (1), (L2)AlMe2 (2), (L1)2AlMe (3), and (L2)2AlMe (4)) in excellent yields, which were characterized by spectroscopic and X-ray diffraction methods. In addition, we have studied their electrochemical properties and complex 1 was found to be the most active catalyst for the formation of cyclic carbonates 6a-j from their corresponding epoxides 5a-j and CO2.
- Rios Yepes, Yersica,Martínez, Javier,Rangel Sánchez, Hiram,Quintero, Celso,Ortega-Alfaro, M. Carmen,López-Cortés, José G.,Daniliuc, Constantin G.,Anti?olo, Antonio,Ramos, Alberto,Rojas, René S.
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p. 1124 - 1134
(2020/02/04)
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- Scalable Synthesis of Functionalized Ferrocenyl Azides and Amines Enabled by Flow Chemistry
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A scalable access to functionalized ferrocenyl azides has been realized in flow. By halogen-lithium exchange of ferrocenyl halides and trapping with tosyl azide, a variety of functionalized ferrocenyl azides were obtained in high yields. To allow a scalable preparation of these potentially explosive compounds, a flow protocol was developed accelerating the reaction time to minutes and circumventing accumulation of potentially hazardous intermediates. The corresponding ferrocenyl amines were then prepared by a reliable reduction process.
- Boeser, Lisa,Christmann, Mathias,Hartmayer, Bence,Heretsch, Philipp,Kleoff, Merlin,Sarkar, Biprajit,Schwan, Johannes
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supporting information
(2020/02/04)
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- Enantioselective Twofold C?H Annulation of Formamides and Alkynes without Built-in Chelating Groups
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Twofold C?H annulation of readily available formamides and alkynes without built-in chelating groups was achieved. Ni?Al bimetallic catalysis enabled by a bulky BINOL-derived chiral secondary phosphine oxide (SPO) ligand proved to be critical for high reactivity and high selectivity. This reaction uses readily available formamides as starting materials and provides a concise synthetic pathway to a broad range of chiral ferrocenes in 40–98 % yield and 93–99 % ee.
- Chen, Hao,Luan, Yu-Xin,Wang, Yin-Xia,Ye, Mengchun
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supporting information
p. 9428 - 9432
(2020/04/17)
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- Bis-ferrocenyl-pyridinediimine trinuclear mixed-valent complexes with metal-binding dependent electronic coupling: Synthesis, structures, and redox-spectroscopic characterization
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A family of metal dichloride complexes having a bisferrocenyl- substituted pyridinediimine ligand was systematically synthesized ((Fc2PDI)MCl2, M = Mg, Zn, Fe, and Co) and characterized crystallographically, spectroscopically, electrochemically, and computationally. Electronic coupling between the ligand ferrocene units is switched on upon binding to a MCl2 fragment, as evidenced by both sequential oxidation of the ferrocenes in cyclic voltammetry (ΔEox ≈ 200 mV) and by Inter-Valence Charge Transfer electronic excitations in the near IR. Additionally, UV-vis spectra are used to directly observe orbital mixing between the ferrocenyl units and the imine π system since breaking of the orbital symmetry results in allowed transitions (? = 2800 M-1cm-1 vs ? ≈ 200 M-1cm-1 in free ferrocene) as well as broadening and red-shifting of the ferrocenyl transitions-indicating organic character in formerly pure metal-centered transitions. DFT analysis reveals that interaction between the ferrocenes and the MCl2 fragment is small and suggests that communication is mediated by better energy matching between the ferrocene and organic π? orbitals upon coordination, allowing superexchange coupling through the LUMO. Furthermore, single crystal diffraction data obtained from oxidation of one and both ferrocenes show distortions, introducing the empty dxy/dx2-y2 orbitals into the secondary coordination sphere of the MCl2 fragment. Such structural rearrangements are infrequent in ferrocenyl mixedvalent compounds, and implications for catalysis as well as electronic communication are discussed.
- Carter, Cole,Kratish, Yosi,Jurca, Titel,Gao, Yanshan,Marks, Tobin J.
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p. 18715 - 18729
(2020/11/17)
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- TRICARBONYL COMPLEXES OF TRANSITION METALS WITH BENZO-HETEROCYCLIC DERIVATIVES OF THE CYCLOPENTADIENYL ANION
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Complex compounds of transition metals according to formula (1) wherein the M(CO)3+ tricarbonyl-metal core forms a complex with the cyclopentadienyl anion linked to heterocyclic moieties of the benzothiazole, benzimidazole and benzoxazole families. The compounds exhibit high blood-brain barrier permeability and can be used in the diagnosis and/or treatment of diseases of the Central Nervous System.
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Page/Page column 12-14
(2019/10/15)
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- Electrochemical Molecular Switch for the Selective Profiling of Cysteine in Live Cells and Whole Blood and for the Quantification of Aminoacylase-1
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A first-of-a-kind latent electrochemical redox probe, ferrocene carbamate phenyl acrylate (FCPA), was developed for the selective detection of cysteine (Cys) and aminoacylase (ACY-1). The electrochemical signal generated by this probe was shown to be highly specific to Cys and insensitive to other amino acids and biological redox reactants. The FCPA-incorporated electrochemical sensor exhibited a broad dynamic range of 0.25-100 μM toward Cys. This probe also proficiently monitored the ACY-1-catalyzed biochemical transformation of N-acetylcysteine (NAC) into Cys, and this proficiency was used to develop an electrochemical assay for quantifying active ACY-1, which it did so in a dynamic range of 10-200 pM (0.1-2 mU/cm3) with a detection limit of 1 pM (0.01 mU/cm3). Furthermore, the probe was utilized in real-time tracking and quantification of cellular Cys production, specifically in Escherichia coli W3110, along with a whole blood assay to determine levels of Cys and spiked ACY-1 in blood with a reliable analytical performance.
- Balamurugan,Huang, Chih-Hung,Chang, Pu-Chieh,Huang, Sheng-Tung
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p. 12631 - 12638
(2018/11/03)
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- Ratiometric electrochemical detection of Pd???π interactions: application towards electrochemical molecular logic gates
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The widespread and large scale use of platinum group metals, especially palladium, in a wide variety of industrial applications has seen their levels in wastewater streams, roadside dust and even pharmaceuticals significantly rise over recent years. Due to the possible environmental damage and potential health risk this may cause, there is now substantial demand for inexpensive, efficient and robust methods for the detection of palladium. Based upon self-immolative linker technologies, we have designed and synthesised a number of allyl ether-functionalised electrochemical probes to determine the optimum probe structure required to deliver a ratiometric electrochemical detection method capable of achieving a limit of detection of?a proof-of-principle ratiometric electrochemical molecular logic gate.
- Goggins, Sean,Stark, Oliver P.,Naz, Christophe,Marsh, Barrie J.,Frost, Christopher G.
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p. 749 - 757
(2017/07/15)
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- Ratiometric electrochemical detection of β-galactosidase
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A novel ferrocene-based substrate for the ratiometric electrochemical detection of β-galactosidase was designed and synthesised. It was demonstrated to be an excellent electrochemical substrate for β-Gal detection with sensitivity as low as 0.1 U mL-1.
- Spring, Sam A.,Goggins, Sean,Frost, Christopher G.
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supporting information
p. 7122 - 7126
(2017/09/07)
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- Amino ferrocene derivative and organic light emitting diode
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The invention provides an amino ferrocene derivative. The amino ferrocene derivative is described as in a formula (I) in the specification. In the formula (I), Ar1 and Ar2 are identically or differently selected from substituted or non-substituted aryl groups of C6 to C10. The amino ferrocene derivative provided by the invention can be used as a p-type carrier generation layer in OLED; meanwhile, the OLED connected in series (series type OLED) can obtain the characteristics of high illumination brightness, external quantum efficiency, current efficiency, etc.
- -
-
Paragraph 0035; 0037; 0038
(2017/07/01)
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- Ratiometric electrochemical detection of hydrogen peroxide and glucose
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Hydrogen peroxide (H2O2) detection is of high importance as it is a versatile (bio)marker whose detection can indicate the presence of explosives, enzyme activity and cell signalling pathways. Herein, we demonstrate the rapid and accurate ratiometric electrochemical detection of H2O2 using disposable screen-printed electrodes through a reaction-based indicator assay. Ferrocene derivatives equipped with self-immolative linkers and boronic acid ester moieties were synthesised and tested, and, through a thorough assay optimisation, the optimum probe showed good stability, sensitivity and selectivity towards H2O2. The optimised conditions were then applied to the indirect detection of glucose via an enzymatic assay, capable of distinguishing 10 μM from the background within minutes.
- Goggins, Sean,Apsey, Ellen A.,Mahon, Mary F.,Frost, Christopher G.
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supporting information
p. 2459 - 2466
(2017/03/20)
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- Aminoferrocene derivative and tandem organic light-emitting diode containing the same
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An aminoferrocene derivative is represented by the formula (I): wherein Ar1 and Ar2 independently represent a substituted or unsubstituted C6-C10 aryl group. The aminoferrocene derivative is useful for forming a p-type carrier generation layer of a tandem OLED so that the tandem OLED has superior luminous efficiencies in terms of maximum luminance, maximum external quantum efficiency, maximum current efficiency, etc.
- -
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Page/Page column 4; 5
(2016/06/28)
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- A switchable electrochemical redox ratiometric substrate based on ferrocene for highly selective and sensitive fluoride detection
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A novel latent electrochemical probe based on a ferrocenyl carbamate derivate (FCCD) was synthesized for the highly selective ratiometric detection of fluoride (F-). FCCD was synthesized through an easy, one step reaction using ferrocenyl azide and silyl protected benzyl alcohol as precursors through a Curtius rearrangement. In presence of F-, FCCD undergoes a nucleophilic substitution reaction, which led to the removal of silyl protecting group through 1,6-quinone-methide rearrangement with concomitant release of ferrocenyl amine (FA). As the concentration of F- increases, the amount of FCCD is dissipated, while that of FA accumulated in the reaction medium were monitored through the linear changes in their redox couples. Compared with a conventional ion selective electrode, the use of a cheaper unmodified electrode as a transducer coupled with FCCD displayed higher stability, excellent selectivity and better sensitivity with LOD of 5.1 × 10-7 M (9.69 ppb). Moreover, FCCD is a selective and sensitive colorimetric visualization probe for F-. The proof-of-concept of the approach is demonstrated in direct toothpaste sample (non-transparent solutions), biological and water samples. The important advantages of this approach are high selectivity, the use of cheaper unmodified electrode, adoption of simple electrochemical methods, dual channel detection, low overpotential of the reporter, naked-eye detection, and ability to detect F- in non-transparent samples.
- Manibalan, Kesavan,Mani, Veerappan,Huang, Sheng-Tung
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p. 71727 - 71732
(2016/08/05)
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- A versatile ferrocene-containing material as a p-type charge generation layer for high-performance full color tandem OLEDs
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A novel p-type charge generation material, DPAF, composed of a ferrocene core and a bis(biphenyl)amino group is designed and synthesized for application to tandem OLED devices. This molecular design not only enhances the thermal properties of ferrocene and the hole mobility, but also maintains its electrochemical stability. The red, green, and blue tandem OLEDs all give excellent device performance with low efficiency roll-off by using n-type C60 and p-type DPAFs as charge generation layers.
- Chang, Yu-Wei,Huang, Min-Jie,Lai, Cheng-Chang,Chang, Ching-Chih,Huang, Man-Ping,Liao, Chuang-Yi,Cheng, Chien-Hong
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supporting information
p. 14294 - 14297
(2016/12/14)
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- Synthesis of ferrocene amides and esters from aminoferrocene and 2-substituted ferrocenecarboxylic acid and properties thereof
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Different ferrocenecarboxamides were synthesized from aminoferrocene and various acid coupling partners such as Nα-Boc-l-tryptophan and N-protected sugar amino acids (N-Boc-3-amino-3-deoxy-1,2-O-isopropylidene-α-d-ribofuranoic acid, N-Boc-3-amino-3-deoxy-1,2-O-isopropylidene-α-d-xylofuranoic acid and their corresponding homo- and hetero-dimers). Similarly, reactions between 2-aminoethyl ferrocenecarboxylate and N-protected sugar amino acids afforded compounds with a carboxamide functional group remotely positioned from the ferrocene core. The X-ray diffraction structure of one of them showed the presence of an intermolecular hydrogen bond between the amide functional groups. Carbonylamino (or carbonyloxy) and oxycarbonyl 1,2-disubstituted ferrocenes were prepared either as racemic mixtures or in enantiomerically pure (SP) form. Their electrochemical evaluation revealed distinctive features. Interestingly, the enantiomerically pure ferrocene diester showed a large potential shift (+45 mV) in the presence of l-glutamic acid. Finally, some of the synthesized ferrocenes were evaluated for their antibacterial, antifungal and antiproliferative (MCF-7) activities.
- Srinivas, Palabindela,Prabhakar, Sunchu,Chevallier, Floris,Nassar, Ekhlass,Erb, William,Dorcet, Vincent,Jouikov, Viatcheslav,Radha Krishna, Palakodety,Mongin, Florence
-
supporting information
p. 9441 - 9447
(2016/11/11)
-
- Catalytically Generated Ferrocene-Containing Guanidines as Efficient Precursors for New Redox-Active Heterometallic Platinum(II) Complexes with Anticancer Activity
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The potential of structurally new ferrocene-functionalized guanidines as redox-active precursors for the synthesis of heterometallic platinum(II)-guanidine complexes with anticancer activity was studied. To this end, an atom-economical catalytic approach was followed by using ZnEt2 to catalyze the addition of aminoferrocene and 4-ferrocenylaniline to N,N′-diisopropylcarbodiimide. Furthermore, reaction of a platinum(II) source with the newly obtained guanidines Fc-Ni=C(NHiPr)2 (3) and Fc(1,4-C6H4)-N=C(NHiPr)2 (4) provided access to the heterometallic complexes [PtCl2{Fc-N=C(NHiPr)2}(DMSO)] (5), [PtCl2{Fc(1,4-C6H4)-N=C(NHiPr)2}(DMSO)] (6), and [PtCl2{Fc(1,4-C6H4)-N=C(NHiPr)2}2] (7). Electrochemical studies evidence the remarkable electronic effect played by the direct attachment of the guanidine group to the ferrocene moiety in 3, making its one-electron oxidation extremely easy. Guanidine-based Fe-Pt complexes 5 and 6 are active against all human cancer cell lines tested, with GI50 values in the range 1.4-2.6 μM, and are more cytotoxic than cisplatin in the resistant T-47D and WiDr cell lines.
- Nieto, Daniel,Bru?a, Sonia,González-Vadillo, Ana Ma,Perles, Josefina,Carrillo-Hermosilla, Fernando,Anti?olo, Antonio,Padrón, José M.,Plata, Gabriela B.,Cuadrado, Isabel
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supporting information
p. 5407 - 5417
(2015/12/08)
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- Urea-bridged diferrocene: Structural, electrochemical, and spectroelectrochemical studies
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Urea-bridged diferrocene derivatives N,N′-diferrocenylurea (1) and N,N′-dimethyl-N,N′-diferrocenylurea (2) were prepared and characterized. Single-crystal X-ray analysis shows that Compound 1 has a trans-trans linear conformation whereas Compound 2 has a trans-cis conformation. Both compounds display two consecutive redox couples with, respectively, E1/2 of +0.29 and +0.42 V vs. Ag/AgCl for 1 and +0.31 and +0.50 V for 2. Spectroelectrochemical studies show the presence of distinct intervalence charge transfer (IVCT) transitions for the one-electron-oxidized mixed-valent Compound 1 +, with an estimated electronic coupling parameter of 190 cm-1. By contrast, the one-electron-oxidized Compound 2 + shows much weaker IVCT transitions.
- Gong, Zhong-Liang,Zhong, Yu-Wu
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p. 1444 - 1450
(2015/09/02)
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- [2]Ferrocenophanes with Nitrogen in Bridging Positions
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Three [2]ferrocenophanes ([2]FCPs) bridged by nitrogen and silicon (7SiMe2) and nitrogen and tin (7SnMe2, 7SntBu2) were synthesized by salt metathesis between a dilithioferrocene derivative, prepared in situ from 1-bromo-1′-(trimethylsilylamino)ferrocene (6), and Me2SiCl2, Me2SnCl2, and tBu2SnCl2, respectively. A multistep synthesis of precursor 6 is described. Only 7SiMe2 and 7SntBu2 could be prepared as analytically pure compounds. The molecular structures of all three [2]FCPs were determined by single-crystal X-ray analysis. Expectedly, the tilting of the Cp ligands in the silicon species 7SiMe2 is larger [α = 15.73(13)°] than in the tin compounds 7SnMe2 [α = 9.36(17) and 9.45(18)°] and 7SntBu2 [α = 10.13(11)°]. Ring-opening polymerizations of 7SiMe2 and 7SntBu2 were attempted using the common methods of thermal, transition-metal-catalyzed, anionic, and photocontrolled ring-opening polymerization, but none of the experiments gave polymeric materials. (Figure Presented).
- Dey, Subhayan,Quail, J. Wilson,Müller, Jens
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p. 3039 - 3046
(2015/06/30)
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- Ratiometric electrochemical detection of alkaline phosphatase
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A novel ferrocene-derived substrate for the ratiometric electrochemical detection of alkaline phosphatase (ALP) was designed and synthesised. It was demonstrated to be an excellent electrochemical substrate for the ALP-labelled enzyme-linked immunosorbent assay (ELISA). This journal is
- Goggins, Sean,Naz, Christophe,Marsh, Barrie J.,Frost, Christopher G.
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p. 561 - 564
(2015/02/19)
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- Synthesis and conformational study of bioconjugates derived from 1-acetyl-1′-aminoferrocene and α-amino acids
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1,1′-Disubstituted ferrocene conjugates present useful and efficient bioorganometallic constraint design to reduce the conformational flexibility of small peptides. In this study we present the first systematic conformational analysis of nonsymmetric ferrocene peptidomimetics (Boc-AA-NH-Fn-COMe; Boc = tert-butoxycarbonyl; AA = Gly, L-Ala, L-Val; Fn = 1,1′-ferrocenylene) and their monosubstituted analogues (Boc-AA-NH-Fc; Fc = ferrocenyl; AA = Gly, L-Ala, L-Val). The spectroscopic data (IR, NMR and CD) were corroborated by DFT calculations and indicated the engagement of the NH group closest to the ferrocene unit in intrachain hydrogen bonds. This medium-strength bond is not disrupted by the introduction of a hydrogen-bonding acceptor on the other ferrocene ring, but rather is accompanied by an additional interchain hydrogen bond, which causes the restricted rotation of ferrocene rings and gives rise to a chiral arrangement of the ferrocene core in a P helical manner.
- Semen?i?, Mojca ?aki?,Kova?, Veronika,Kodrin, Ivan,Bari?i?, Lidija,Rapi?, Vladimir
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p. 112 - 123
(2015/01/30)
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- Phosphino-amine (PN) Ligands for Rapid Catalyst Discovery in Ruthenium-Catalyzed Hydrogen-Borrowing Alkylation of Anilines: A Proof of Principle
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A general synthetic protocol for the synthesis of simple phosphino-amine (PN) ligands is described with 19 ligands being isolated in good yields. High-throughput ligand screening uncovered the success of two of these ligands for aromatic amine alkylations via ruthenium-catalyzed hydrogen borrowing reactions. The combination of N,N'-bis(diphenylphosphino)-N,N′-dimethylpropylenediamine with a ruthenium(II) source and potassium hydroxide (15 mol%) is the optimal system for selective monobenzylations of aromatic amines (method A). Over 70% isolated yields have been achieved for the formation of 14 secondary aromatic amines under mild reaction conditions (120 C and 1.05 equivalents of benzyl alcohol). On the other hand, N,N-bis(diphenylphosphino)-isopropylamine was the ligand utilized for both selective monomethylation and monoethylation reactions of aromatic amines (method B). Here the alcohol is charged as both the reaction medium and substrate and 9 examples are disclosed with all isolated yields exceeding 70%. These methods have been applied to the synthesis of important synthetic building blocks based on aminoferrocene.
- Broomfield, Lewis Marc,Wu, Yichen,Martin, Eddy,Shafir, Alexandr
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supporting information
p. 3538 - 3548
(2016/01/25)
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- Combining ferrocene, thiophene and a boronic acid: A hybrid ligand for reagentless electrochemical sensing of cis-diols
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A redox-active affinity ligand suitable for reagentless sensing of cis-diols was synthesised and characterised. 4-[(Ferrocenylamino)methyl] thiophene-3-boronic acid (FcTBA) was allowed to interact with the model cis-diol, sorbitol. A discrete, cathodic shift of the redox potential was observed upon interaction of FcTBA with sorbitol thus providing simultaneous differentiation between the free and bound forms of this sensor molecule. Similar behaviour was observed also for FcTBA co-immobilised with thiophene in a mixed self-assembled monolayer on a gold electrode.
- Lacina, Karel,Konhefr, Martin,Novotny, Jan,Potě?il, David,Zdráhal, Zbyněk,Skládal, Petr
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p. 3235 - 3238
(2014/06/09)
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- Probing the tolerance of cucurbit[7]uril inclusion complexes to small structural changes in the guest
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The binding properties of the cucurbit[7]uril host with three structurally related ferrocene-containing guests, ferrocenyltrimethylammonium, ferrocenylmethyltrimethylammonium and ferrocenylethyltrimethylammonium, have been investigated using 1H
- Yi, Song,Li, Wei,Nieto, Daniel,Cuadrado, Isabel,Kaifer, Angel E.
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supporting information
p. 287 - 293
(2013/02/23)
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- An environmentally benign and cost-effective synthesis of aminoferrocene and aminoruthenocene
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An improved synthesis of aminoferrocene has been carried out that adheres with the basic green chemistry guidelines. Amination from aqueous NH3 as the nitrogen source, with the inexpensive CuI/Fe2O3 couple as cocatalyst in ethanolic solution, makes the process environmentally attractive as well as a viable alternative for all practical purposes. This procedure has also been applied to prepare aminoruthenocene, being reported for the first time.
- Leonidova, Anna,Joshi, Tanmaya,Nipkow, David,Frei, Angelo,Penner, Johanna-Elena,Konatschnig, Sandro,Patra, Malay,Gasser, Gilles
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p. 2037 - 2040
(2013/05/08)
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- Syntheses of N-bridged ferrocene/porphyrin-fullerene dyads and influence of iminofullerene isomers on the attached chromophores
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N-Ferrocene (Fc)/porphyrin (Por) [5,6]-open azafulleroids and [6,6]-closed aziridinofullerenes have been synthesized for the first time. Electrochemical measurements revealed that chromophores attached to [5,6]-open azafulleroids are more easily oxidizabl
- Chen, Chen,Zhu, Yi-Zhou,Zhao, Hai-Ying,Zheng, Jian-Yu
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supporting information
p. 1607 - 1611
(2013/03/29)
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- The syntheses and electrochemical studies of a ferrocene substituted diiminopyridine ligand and its P, S, Se, and Te complexes
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A new reversible, redox active diiminopyridine ligand (1Fc) containing pendant ferrocene functionalities was isolated and fully characterized. The reaction of 1Fc with chalcogen pseudohalides of sulfur, selenium, and tellurium yielded the respective N,N′,N″-chelated chalcogen dications. Phosphorus chemistry proceeded in a related manner but, in this case, by the direct addition of 1Fc with PI3 to yield the N,N′,N″- chelated P(I) cation. These species represent the first synthesized main group complexes involving a redox active diiminopyridine ligand containing pendant ferrocenes. Electrochemical studies of the free ligand shows a reversible two-electron process. The chelated phosphorus cation, however, displayed three events, the first being a quasi-reversible two-electron process, involving the oxidation at the P(I) center, resulting in a P(III) cation. The subsequent reversible one- and two-electron processes arise from the ligand framework and pendant ferrocenes, respectively.
- Magdzinski, Eleanor,Gobbo, Pierangelo,Martin, Caleb D.,Workentin, Mark S.,Ragogna, Paul J.
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p. 8425 - 8432
(2012/09/22)
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- Triferrocenes built on a C3-symmetric ligand platform: Entry to redox-active pseudo-triphenylenes via chelation-driven stereoselection of triple Schiff bases
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An expedient tandem deprotonation-trapping protocol was employed to prepare a tris(difluoroboronyl) complex of a triferrocenyl ligand that is geometrically analogous to substituted triphenylenes. A triple Schiff base condensation reaction between 1,3,5-triformylphloroglucinol and aminoferrocene afforded the tris(N-salicylideneamine) adducts 5a + 5b in ca. 1:1 ratio. The keto-enamine tautomeric core of this isomeric mixture could be converted to a common enolate-imine intermediate. Subsequent trapping with BF3· Et2O cleanly afforded the tris(difluoroboronyl) adduct 6 in essentially quantitative yield. The electronic and structural properties of this new class of ferrocene compounds were investigated using various methods including UV-vis, cyclic voltammetry (CV), differential pulse voltammetry (DPV), and X-ray crystallography. In CH2Cl2-CH3CN, 6 displayed a reversible three-electron oxidation process at E1/2 ox = +210 mV (vs Fc/Fc+). Despite the sharing of a common [π,π]/[π,π]-conjugated core, no significant electronic communication was observed among the three ferrocenyl units in 6 under either CV or DPV conditions. On the other hand, the broad oxidation wave of 5a + 5b at E 1/2ox = +60 mV in CH2Cl2-CH 3CN was comprised of at least two major components at +20 and +90 mV, which collapsed to become a single peak in DMF electrolyte, despite that the ratios between the two isomers 5a,b remained essentially invariant to the change in solvent.
- Lim, Young-Kwan,Wallace, Scott,Bollinger, John C.,Chen, Xufang,Lee, Dongwhan
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p. 1694 - 1703
(2008/10/09)
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- N-ferrocenyl-substituted planar-chiral N-heterocyclic carbenes and their PdII complexes
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The N-ferrocenyl-linked N-heterocyclic carbenes 1a and 1b were obtained by treatment of their imidazolium salts 12a and 12b with potassium tert-butoxide. The latter were shown to be accessible from (R)-1-amino-2-methylferrocene (9) and aminoferrocene, respectively, which were converted into the corresponding formamidines and then subjected to a novel cyclization procedure. Treating the ligand precursors 12a and 12b with [Pd(OAc)2]3 under different reaction conditions afforded the trans-pyridine-substituted Pd II complexes 14a and 14b as well as their trans-triphenylphosphane- substituted counterparts 16a and 16b and, in the case of the chiral ligand precursor, the dinuclear PdII complex 15a. Conformational analysis of the ligands based on the X-ray structures of 12a, 12b and 16a revealed the dependence of the two torsion angles between the central imidazolium core and the adjacent ferrocenyl substituents on the steric and electronic properties of the observed systems. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Bertogg, Andreas,Camponovo, Francesco,Togni, Antonio
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p. 347 - 356
(2007/10/03)
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- Observation of a large current on the cyclic voltammetry of acylaminoferrocenes in the solid state: An efficient electron-transfer pathway through continuous NH...O=C hydrogen-bond chains and π-conjugation
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A series of crystal structures of acylaminoferrocenes, [(C 5H5)Fe(C5H4NHCOR)] (R = CH 3 (1), CH2CH3 (2), t-Bu (3), and CF3 (4)) revealed an unusually delicate dependence of the alkyl substituent structure on electron transfer through NH...O=C bonding and π-conjugation. The presence of strong intermolecular NH...O=C hydrogen bonds in the crystal was established by X-ray, IR, and CRAMPS. Compounds 1 and 2 are without steric or electrostatic hindrance, and both exhibit continuous and strong hydrogen-bond chains, or an effective π-electrons system. However, the hydrogen-bond chains in 3 and 4 are weak, or broken, by the bulkiness of t-Bu or the electrostatic repulsion of CF3. Solid-state cyclic voltammograms of 1-4 have revealed the electrochemical processes, which are critically dependent on the array and the strength of the hydrogen bonds. Although both 3 and 4 show typical reversible cyclic voltammograms, 1 and 2 exhibit irreversible redox behaviors and remarkably large current values, which indicate the presence of an effective electron transfer through the continuous hydrogen-bond chains.
- Okamura, Taka-Aki,Sakauye, Keiko,Doi, Mototsugu,Yamamoto, Hitoshi,Ueyama, Norikazu,Nakamura, Akira
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p. 1270 - 1278
(2007/10/03)
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- Main chain ferrocenyl amides from 1-aminoferrocene-1′-carboxylic acid
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The non-natural amino acid 1-aminoferrocene-1′-carboxylic acid is synthesised from ferrocene in eight steps. The folding and association phenomena of amido-substituted ferrocenes in the crystal as well as in solution are studied by X-ray crystallography, IR and NMR spectroscopy and DFT calculations. The amino acid is selectively protected at the amino group with the use of the fluorenyl-9-methoxycarbonyl (Fmoc) group. An amide-linked ferrocene dimer is prepared using the HOBt/DCC protocol for amide formation. In the crystal the dimer forms a hydrogen-bonded sheet structure, while in solution dynamic intramolecular hydrogen bonds are observed by VT 1H NMR and IR spectroscopy. The dynamic flipping process has been rationalised by DFT calculations. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Heinze, Katja,Schlenker, Manuela
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p. 2974 - 2988
(2007/10/03)
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- Synthesis of 1′-substituted derivatives of 1,2,3,4,5-pentaphenylferrocene
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Pentaphenylferrocene was synthesized in 57% overall yield from 1-bromopentaphenylcyclopentadiene. Functionalization of the unsubstituted cyclopentadienyl ring using the Friedel - Crafts reaction gave 1′-formyl-and 1′-(2-chlorobenzoyl)-substituted derivatives. Hydrolysis of the latter provided the corresponding 1′-carboxylic acid. This was readily transformed via a modified Curtius rearrangement into 1′-amino-1,2,3,4,5-pentaphenylferrocene. This methodology also provided (η5-aminocyclopentadienyl)(η4-tetraphenylcyclobuta diene)-cobalt and gave an improved synthesis of aminoferrocene.
- Butler, David C.D.,Richards, Christopher J.
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p. 5433 - 5436
(2008/10/08)
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- 1,1′-diisocyanoferrocene and a convenient synthesis of ferrocenylamine
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The ferrocene derivative 1,1′-diisocyanoferrocene was prepared from the reaction of 1,1′-diisocyanatoferrocene with formic acid. The reaction was followed by thermal decarboxylation and reaction with POCl3. An improved synthesis method involves lithiation of ferrocene. This is followed by a reaction with α-azidostyrene and subsequent acidification. The new preparation method of ferrocenylamine makes this compound available in good purity. Its use in the synthesis of new ancillary ligands is explored.
- Leusen, Daan van,Hessen, Bart
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p. 224 - 226
(2008/10/08)
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- N,N'-diferrocenyl-N-heterocyclic carbenes and their derivatives
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In continuation of our work on Wanzlick/Arduengo carbenes containing redox-active ferrocenyl substituants we report on the synthesis of N,N'-diferrocenyl imidazol(in)ium salts as precursors of imidazol(in)-2-ylidenes. The necessary starting material for t
- Bildstein, Benno,Malaun, Michael,Kopacka, Holger,Wurst, Klaus,Mitterb?ck, Martin,Ongania, Karl-Hans,Opromolla, Giuliana,Zanello, Piero
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p. 4325 - 4336
(2008/10/08)
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- The synthesis and characterisation of heterosubstituted aminoferrocenes
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The synthesis of 1-bromo-1′-aminoferrocene is reported using a simple synthetic methodology. This compound serves as a useful precursor to other heterosubstituted aminoferrocenes. For example, (1′-amino)ferrocenecarboxylic acid has been obtained and is conveniently isolated in its C-protected form by lithiation of 1-bromo-1′-aminoferrocene, quenching with solid carbon dioxide and esterification of the resulting carboxylate with methanolic HCl. The new ligand 1-diphenylphosphino-1′-aminoferrocene has also been obtained using a similar methodology.
- Butler, Ian R.,Quayle, Scott C.
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- Ferrocenyl sulfinylimide and diferrocenyl sulfurdiimide, Fc - NSO and Fc(NSN)Fc
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The reactions of ferrocenylamine, Fc - NH2 (1), with thionyl chloride and sulfur dichloride in hexane solution in the presence of triethylamine lead to the title compounds Fc - NSO (2) and Fc(NSN)Fc (3), respectively. 2 and 3 have also been obtained in reactions of the silylated ferrocenylamine, Fc - NH(SiMe3) (1b), with thionyl chloride. The ferrocenyl sulfinylimide 2 has been converted to sulfurdiimides such as Fc(NSN)Fc (3) and Fc(NSN)R (R = 1Bu (4 a), SiMe3 (4b)) by reaction with the lithium derivative of silylated amines, LiN(SiMe3)R (R = Fc, 1Bu, SiMe3). The new ferrocenyl compounds 2-4 have been characterized by their NMR spectra, and their electrochemical behaviour has been studied. The molecular structure of Fc - NSO (2) has been determined by an X-ray structure analysis; the sulfinylimide has the Z configuration, and the - NSO group is coplanar with the cyclopentadienyl ring to which it is attached. Johann Ambrosius Barth 1996.
- Herberhold, Max,Distler, Berthold,Maisel, Heidi,Milius, Wolfgang,Wrackmeyer, Bernd,Zanello, Piero
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p. 1515 - 1523
(2008/10/09)
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- Ferrocene derivatives. 23. Isocyanoferrocene and isothiocyanatoferrocene
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Aminoferrocene has been converted into formamidoferrocene, which exists in solution as an equilibrium mixture of two rotational isomers, a monomeric cis form and a dimeric (or oligomeric) trans form. Variable-temperature 1H and 13C{1H} NMR spectra have been used to measure ΔG for the hindered internal rotation about the C-N bond. Dehydration of formamidoferrocene yields isocyanoferrocene, which has been characterized by complex formation with iron and molybdenum carbonyls. A high-yield conversion of aminoferrocene into isothiocyanatoferrocene is described.
- Knox,Pauson,Willison,Solcaniova,Toma
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p. 301 - 306
(2008/10/08)
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- FERROCENYLAMINE
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A general method for the preparation of ferrocenylamines involves the reactions of ferrocenyl bromide, FcBr*, with the sodium salt of an amine or amide in the presence of copper(I)bromide/pyridine.The syntheses of diferrocenylphenylamine and triferrocenylamine, NFc2Ph and NFc3, respectively, are reported, and the hydrolysis of N-ferrocenyl acetamide to give ferrocenylamine, NH2Fc, is described.The system of the ferrocenyl- and/or phenyl-substituted derivatives of ammonia, NFcnX3-n (n=0-3; X=H, Ph), is characterised on the basis of mass, UV VIS and in particular of 1H and 13C NMR spectroscopic data.
- Herberhold, Max,Ellinger, Max,Kremnitz, Walter
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p. 227 - 240
(2007/10/02)
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- Ferrocenylmethyl azide
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The preparation of ferrocenylmethyl azide and its use as a synthetic intermediate is discussed. Acid catalyzed decomposition of the azide provides the novel product bis(ferrocenylmethyl)amine.
- Bublitz
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p. 225 - 228
(2008/10/08)
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