Solvent effects on the metalation of Tri,-tert-butylphosphine.Preparation and characterization of [H2Cl]2 and [H2Cl]2

Clark, H. C.; GOEL, A. B.; Goel, Ram G.; Goel, Sarla; Ogini, William O.

doi:10.1016/s0020-1693(00)94955-7

Cited by 32 publications

(23 citation statements)

References 6 publications

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“…[ZnCl 2 ·2THF] was received by drying ZnCl 2 with thionyl dichloride and additional reaction with dry tetrahydrofuran. The palladium catalyst [P( t C 4 H 9 ) 2 C(CH 3 ) 2 CH 2 Pd(µ-Cl)] 2 was synthesized according to Clark et al26…”

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confidence: 99%

Molecular Wires using (Oligo)pyrroles as Connecting Units: An Electron Transfer Study

et al. 2013

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A series of (oligo)pyrroles featuring redox-active terminal ferrocenyl groups (Fc 2 -( c C 4 H 2 NPh) n (4, n = 1; 9, n = 2; 16, n = 3; 20, n = 4)) has been prepared using a Negishi C,C cross-coupling reaction protocol. The bi-, ter-and quarterpyrrole wire moieties have been built up by C,C cross-coupling reactions of trimethyl silyl protected pyrrole units in the presence of [Pd(CH 2 C(CH 3 ) 2 P( t C 4 H 9 ) 2 )(µ-Cl)] 2 as precatalyst. The structural properties of the title compounds were investigated by spectroscopic means and single-crystal X-ray diffraction studies (9, 16 and 20). The influence of the increasing number of N-phenyl pyrrole units on the electronic interaction between the iron centres was studied using electrochemistry (cyclic (CV) and square wave voltammetry (SWV)) as well as spectroelectrochemistry (in situ UV-Vis/NIR spectroscopy). With exception of the diferrocenyl quarterpyrrol 20, the application of [N n Bu 4 ][B(C 6 F 5 ) 4 ] as electrolyte allows the discrete oxidation of the ferrocenyl termini (∆E° ′ = 450 mV (4), ∆E° ′ = 320 mV (9), ∆E° ′ = 165 mV (16)) in cyclic and square wave voltammograms. However, the iron centres of 20 were oxidized simultaneously, generating dicationic 20 2+ . Additionally, one (9) or two (16 and 20) pyrrole-related well-defined reversible one-electron redox processes were observed. The cyclic voltammetry data reveal that the splitting of the ferrocene-based redox couples, ∆E° ′, decreases with increasing oligo-pyrrole chain length and hence, the larger metalmetal distance. The trends in ∆E° ′ with oligo-pyrrole structure also map to the electronic coupling between the ferrocene moieties as estimated by spectroelectrochemical UV-Vis/NIR measurements.Despite no direct metal-metal interaction in diferrocenyl quarterpyrrole 20, a large absorption in the NIR region is observed arising from photo-induced charge transfer from the oligopyrrole backbone to the redox-active ferrocenyl termini. These charge transfer absorptions have also been found in the dicationic oxidation state of the mono-(4), bi-(9) and terpyrroles (16). Within this series of diferrocenyl(oligo)pyrroles this CT band is shifted bathochromically with increasing chain length of the backbone motif.

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Molecular Wires using (Oligo)pyrroles as Connecting Units: An Electron Transfer Study

et al. 2013

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“…Afterward, 0.57 equiv. (1.59 g) of 2‐bromo‐3,4,5‐trimethylthiophene and 33.5 µmol (23 mg) of [Pd(CH 2 CMe 2 P t Bu 2 )(µ‐Cl)] 2 were added to the reaction mixture in a single portion. This reaction mixture was stirred at 55 °C for 18 h. After cooling it to ambient temperature, the reaction mixture was hydrolyzed, the organic layer was separated and the aqueous phase was extracted exhaustively with diethyl ether.…”

Section: Methodsmentioning

confidence: 99%

Ferrocenyl‐Functionalized η⁵‐Thiophene Cr(CO)₃ Half‐Sandwich Compounds

et al. 2018

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The synthesis of η 5 -Cr(CO) 3 complexed 2,5-Fc 2 -(3a), 3,4-Fc 2 -(3b), 2,3-Fc 2 -(3c) and 2-Fc-3,4,5-Me 3 -thiophenes (3d) [Fc = Fe(η 5 -C 5 H 4 )(η 5 -C 5 H 5 )] is described. These half-sandwich compounds are accessible by the reaction of Cr(CO) 3 (MeCN) 3 with the appropriate substituted thiophenes. The compounds were analyzed by NMR spectroscopy, where a highfield shift for the ring-carbons and substituted hydrogen atoms of the thiophene core occurred. The 2,5-and 3,4-derivatives could be characterized structurally by single-crystal X-ray diffraction analysis, demonstrating that a low bending of the sulfur atom out of the thiophene plane of up to 9.95(17)°and an anti-arrangement of the ferrocenyl and Cr(CO) 3 fragments is characteristic. Electrochemical measurements showed that each ferro- [a]

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“…2,5-Dibromo-1,1-dimethyl-3,4-diphenyl-1H-silole 59 and diphenylbis(phenylethnyl)-silane 60 were prepared in analogy to published procedures. [N( n Bu) 4 ][B(C 6 F 5 ) 4 ] was prepared by methathesis of lithium tetrakis-(pentafluorophenyl)borate etherate (Boulder Scientific) with tetra-n-butylammonium bromide according to reference, 35 [P( t C 4 H 9 ) 2 C(CH 3 ) 2 CH 2 Pd( -Cl)] 2 61,62 and iodoferrocene 63,64 were prepared according to published procedures. All other chemicals were purchased from commercial suppliers and were used as received.…”

Section: Methodsmentioning

confidence: 99%

Synthesis, Characterization, Electrochemistry, and Computational Studies of Ferrocenyl-Substituted Siloles

et al. 2014

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Ferrocenylsiloles of the type 2,5-Fc 2-3,4-Ph 2-c C 4 SiR 2 (3a, R = Me; 3b, R = Ph) have been prepared by reductive cyclization from diethynyl silanes, followed by ferrocenylation using the Negishi C,C cross coupling protocol with the silole ring serving as either the vinyl halogenide species or as zinc organic component and the complementary functionality introduced on the ferrocenyl moiety. The electrochemical behavior of these silacyclic-bridged bis(ferrocenyl) complexes was investigated by cyclic and square wave voltammetry, and the nature of the redox products studied by in situ UV-vis/NIR spectroelectrochemical measurements. Each of 3a and 3b undergoes two sequential ferrocenyl-based redox processes, the separation of each (E°' = E 2°'-E 1°' = 300 mV (3a); 280 mV (3b)) is in the range of structural similar systems such as 2,5-diferrocenyl-1-phenyl-1H-phosphole (280 mV) and 2,5-diferrocenylfuran (290 mV). Interestingly, the more electron-rich silole 3b, compared to 3a, shows a modestly lower redox separation between the individual ferrocenyl oxidation processes, which may be due to the capacity of this group to shield the effect of an adjacent positive charge. An inter-valence charge transfer (IVCT) absorption was found in the in situ NIR measurements for [3a] + and [3b] + , the analysis of which is consistent with a moderate electronic interaction between the iron atoms through the cis-diene-like fragment of the silole bridge, and allowing description as Robin and Day class II mixedvalence systems. These conclusions are supported by results from quantum chemical calculations, which also reveal the likely presence of a range of molecular conformations in solution. RESULTS AND DISCUSSION Synthesis and Characterisation. Silacyclopentadienes 2a and 2b were synthesized by intramolecular reductive cyclization from dimethyl-bis(phenylethynyl)silane (1a) and diphenylbis(phenylethynyl)silane (1b) with lithium naphthalenide followed by bromination with elemental bromine, forming dibromide 2a, or the reaction with [ZnCl 2 •2thf] giving the zinc organic species 2b (Scheme 1). Applying Negishi-ferrocenylation conditions, the reaction of 2a with FcZnCl (Fc = Fe(5-C 5 H 4)(5-C 5 H 5)) as ferrocenyl source and [Pd(CH 2 CMe 2 P t Bu 2)(µ-Cl)] 2 as precatalyst gave silole 3a. The analog coupling of 2,5-Br 2-3,4-Ph 2-c C 4 SiPh 2 with ferrocenyl zinc chloride did not result in the formation of desired 3b. The synthesis of 3b was realized by a Negishi C,C cross-coupling reaction using iodoferrocene as ferrocenyl source, while the application of bromoferrocene was unsuccessful. After appropriate work up (Experimental Section), molecules 3a and 3b were obtained in moderate (3a) to low (3b) yield as dark red solids.

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Solvent effects on the metalation of Tri,-tert-butylphosphine.Preparation and characterization of [H2Cl]2 and [H2Cl]2

Cited by 32 publications

References 6 publications

Molecular Wires using (Oligo)pyrroles as Connecting Units: An Electron Transfer Study

Molecular Wires using (Oligo)pyrroles as Connecting Units: An Electron Transfer Study

Ferrocenyl‐Functionalized η⁵‐Thiophene Cr(CO)₃ Half‐Sandwich Compounds

Synthesis, Characterization, Electrochemistry, and Computational Studies of Ferrocenyl-Substituted Siloles

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Solvent effects on the metalation of Tri,-tert-butylphosphine.Preparation and characterization of [H2Cl]2 and [H2Cl]2

Cited by 32 publications

References 6 publications

Molecular Wires using (Oligo)pyrroles as Connecting Units: An Electron Transfer Study

Molecular Wires using (Oligo)pyrroles as Connecting Units: An Electron Transfer Study

Ferrocenyl‐Functionalized η5‐Thiophene Cr(CO)3 Half‐Sandwich Compounds

Synthesis, Characterization, Electrochemistry, and Computational Studies of Ferrocenyl-Substituted Siloles

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Ferrocenyl‐Functionalized η⁵‐Thiophene Cr(CO)₃ Half‐Sandwich Compounds