Reactions of ferricinium salts with Lewis bases

Babin, V. N.; Belousov, Yu. A.; Belousova, T. A.; Borisov, Yu. А.; Gumenyuk, V. V.; Nekrasov, Yu. S.

doi:10.1007/s11172-011-0318-1

Cited by 12 publications

(10 citation statements)

References 24 publications

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“…The reaction of ferrocenium ion with nucleophiles resulting in substitution of the ring hydrogen with a nucleophile are currently known for few examples and their reaction pathways are far from being completely understood. It was assumed that these products can form only in the cases when a nucleophile can be oxidized by a ferrocenium salt and the arising radical then reacts with ferrocenium ion in line with Scheme . In the present work, we showed for the first time that the substitution products of hydrogen in ferrocenium ion with a tertiary phosphine as a nucleophile can result from the sequential nucleophilic addition of the phosphine, the redox reaction of the initial adducts with the starting ferrocenium salts, and the final deprotonation of the intermediate redox reaction product by phosphine (Scheme ).…”

Section: Discussionsupporting

confidence: 61%

“…Although until the present work all reactions of I + X – with nucleophilic reagents resulted in ring hydrogen substitution products were thought to proceed along a radical pathway in accordance with Scheme ,[2c], , we assume that these reactions for non‐oxidizable nucleophiles can proceed also as the oxidative nucleophilic substitution according to Scheme .…”

Section: Introductionmentioning

confidence: 96%

“…In, the reactions of ferrocenium picrate with chloride and bromide ions, as well as neutral bases (DMF, DMSO, HMPTA, Phen, and Bipy) were studied by spectroscopic methods and shown to afford mixtures of cyclopentadienyl ring substitution products (FeX 4 – and [FeL 6 ][OC 6 H 3 (NO 2 ) 3 ] 2 , respectively) and ferrocene as the ferrocenium reduction product. The formation of substitution products of the ring hydrogen was assumed for cases when a nucleophile can be oxidized by a ferrocenium salt and the arising radical then reacts with ferrocenium ion according to Scheme ; it is this pathway along which the reaction of ferrocenium tetrafluoroborate with azolyl anions is thought to proceed . It was shown in that ferrocenium ion acts as a catalyst of electrochemical oxidation of amines.…”

Section: Introductionmentioning

confidence: 99%

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Direct Phosphination of Ferrocenium Ion with Tertiary Phosphines by the Mechanism of Oxidative Nucleophilic Substitution

et al. 2018

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Ferrocenium salts [(C5H5)2Fe]X (X = BF4, PF6) (I+·) react with tertiary phosphines PR3 (PMe3, PEt3, PnBu3, PMe2Ph, and PMePh2) in dichloromethane at room temperature to form a mixture of the corresponding ferrocenylphosphonium salts [(C5H5)FeC5H4PR3]X (III), ferrocene (I), and phosphonium salts [HPR3]X. The same reaction was carried out in an electrochemical cell as the electrolysis of a solution of ferrocene and phosphine in dichloromethane at the oxidation potential of ferrocene. Possible reaction pathways for phosphination of ferrocenium ion were studied by DFT at the M06‐L/6‐311++G(d,p) theory level. The experimental and theoretical studies of this reaction suggest it to proceed according to the Scheme of oxidative nucleophilic substitution of hydrogen in I+· including the following steps: a) nucleophilic exo addition of a phosphine to the cyclopentadienyl ring of I+· to form the radical cation adduct [(η5‐C5H5)Fe·(η4‐C5H5–+PR3)]X (II+·); b) redox reaction of the initial adduct II+· with the starting ferrocenium salt I+· to result in ferrocene (C5H5)2Fe (I) and iron phosphoniocyclopentadiene dication [(η5‐C5H5)Fe+(η4‐C5H5–+PR3)](X)2 (II2+) where the Csp3–H bond is involved in the agostic interaction with the metal atom; and c) deprotonation of the Csp3–H bond in II2+ by the starting phosphine to form III. The relation between the data obtained and current concepts of C–H functionalization in transition metal arene and cyclopentadienyl complexes is discussed.

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Section: Discussionsupporting

confidence: 61%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Direct Phosphination of Ferrocenium Ion with Tertiary Phosphines by the Mechanism of Oxidative Nucleophilic Substitution

et al. 2018

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“…These include alkylation, [1] cyanalkylation, [2,3] arylation, [2,[4][5][6][7] acylation, [8] and azolation. [9] However, the mechanistic details of the CÀ H bond breaking have never been studied for such processes; therefore, the type of the leaving group (H * or H + ) remains unclear. The reactions of ferrocenium with neutral and anionic nucleophiles are much less studied.…”

Section: Introductionmentioning

confidence: 99%

Reactions of Ferrocenium Hexafluorophosphate with P−OR Nucleophiles Give Ring C−H Functionalization or Ring Replacement Products Depending on the Phosphorus Reagent

et al. 2021

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Ferrocenium hexafluorophosphate reacts with different PÀ OR nucleophiles (PR 3 ) in CH 2 Cl 2 at room temperature to give either half-sandwich complexes [CpFe(PR 3 ) 3 ](PF 6 ) (PR 3 =P(OMe) 3 , P-(OEt) 3 , PhP(OMe) 2 ) or ferrocenylphosphonium salts [CpFe (C 5 H 4 PR 3 )](PF 6 ) (PR 3 =iPr 2 P(OMe), iPr 2 P(OEt)). Mixtures of both products are formed for some other nucleophiles (PR 3 =Ph 2 P-(OMe), Ph 2 P(OEt), PhP(OiPr) 2 ). The mechanism of the former reaction was established using DFT calculations. This reaction pathway is especially characteristic of π-acceptor nucleophiles, which is presumably explained by their ability to stabilize the 19e intermediates. The result of the reaction with tertiary phosphines, aminophosphines, and PÀ OR nucleophiles can be reliably predicted based on the values of the Tolman electronic parameter (below 2070 cm À 1 -only ferrocenylphosphonium salt, in between 2073 cm À 1 and 2080 cm À 1 -only half-sandwich complex, and in the range from 2070 cm À 1 to 2073 cm À 1mixtures of both products).

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“…To understand the formation of the NHC-Fc adducts, we investigated three possible initial reaction pathways by density functional theory (DFT) calculations: 28,32 (1) Oxidation of NHC by ferrocenium, (2) deprotonation of ferrocenium by NHC, and (3) nucleophilic addition of NHC to ferrocenium (Figure S2 and S3). The computational studies indicate that the nucleophilic addition of NHC to ferrocenium is the most favorable reaction pathway, consistent with the previously reported reaction between ferrocenium and phosphines.…”

mentioning

confidence: 99%

Pyrrolinium-substituted Persistent Zwitterionic Ferrocenate Derivative Enabling the Application of Ferrocene Anolyte

Song

Kwon²,

Citek³

et al. 2021

Preprint

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Here, we report the first isolable low-valent biscyclopentadienyl iron complexes stabilized by NHC-functionalized ligands (NHC-Cps), which were characterized by electron paramagnetic resonance (EPR) and <sup>57</sup>Fe Mössbauer spectroscopy. Additional theoretical studies on these formally low-valent ferrocene complexes clearly explain the origin of their thermodynamic stability and the orbital interactions between iron and NHC-Cp. Exploiting the facile Fe(II/I) redox chemistry, we successfully demonstrated that the NHC-Fc compounds can be applied as anolytes for redox-flow batteries. These low-valent species will not only deepen our understanding of the intrinsic chemistry of low-valent ferrocene but have the potential to open the way for rational design of highly-reduced metallocene derivatives for various applications.

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Reactions of ferricinium salts with Lewis bases

Cited by 12 publications

References 24 publications

Direct Phosphination of Ferrocenium Ion with Tertiary Phosphines by the Mechanism of Oxidative Nucleophilic Substitution

Direct Phosphination of Ferrocenium Ion with Tertiary Phosphines by the Mechanism of Oxidative Nucleophilic Substitution

Reactions of Ferrocenium Hexafluorophosphate with P−OR Nucleophiles Give Ring C−H Functionalization or Ring Replacement Products Depending on the Phosphorus Reagent

Pyrrolinium-substituted Persistent Zwitterionic Ferrocenate Derivative Enabling the Application of Ferrocene Anolyte

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