From diferrocenyl-cyclopropenone to diferrocenyl-cyclopropenylium cations and triferrocenylpropenones: An electrochemical study

Steve W. Lehrich, Alexander Hildebrandt, Marcus Korb, Heinrich Lang

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The reaction of 2,3-diferrocenylcyclopropenone (1) with the electrophiles H[BF4] and [Et3O][BF4], respectively, produced the corresponding cyclopropenylium cations [Fc(2)C(3)OH][BF4] (2) and [Fc(2)C(3)OEt] [BF4(]) (3) (Fc = Fe(eta(5)-C5H4)(eta(5)-C5H5)). Reacting 3 with HNEt2 afforded the NE(t)2-functionalized species [Fc(2)C(3)NEt(2)][BF4] (4). However, when 2 was reacted with nucleophiles such as FcLi a ring opening of the C-3 cycle was observed and E- and Z-1,2,3-triferrocenylpropenones Z-5 and E-5 were formed. Crystallization of a dichloromethane solution containing 3, layered with hexane, gave the BF3 adduct of diferrocenylcyclopropenone 6 at the interphase. The molecular solid state structures of Z-5, E-5 and 6 were determined by single crystal X-ray diffraction. Compound E-5 possesses a helical chirality and crystallizes in an enantiopure form. The electronic properties of the ferrocenyl-substituted cyclopropenylium cations 2-4 and of the triferrocenyl-alpha,beta-unsaturated ketones Z-5 and E-5 were studied by cyclic voltammetry and square wave voltammetry. In comparison to the cyclopropenone derivative 1, the ferrocenyl oxidation processes of the cyclopropenylium cations 2 and 3 are shifted towards higher potentials, which is caused by the lower electron density of the strained C-3 rings. Compound 4 decomposes during the electrochemical measurements. Furthermore, it could be shown that E/Z isomerism has only small effects on the electronic properties of the triferrocenyl-alpha, beta-unsaturated ketones. Spectroelectrochemical UV-Vis/NIR measurements carried out on 1 and Z-5 and E-5 confirmed electron-transfer interactions within the 2,3-diferrocenylcyclopropenone and the 1,2,3-triferrocenyl-alpha, beta-unsaturated ketones. However, the cyclopropenylium cations 2 and 3 show no long time stability under oxidative conditions. (C) 2017 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)105-113
Number of pages9
JournalJournal of Organometallic Chemistry
Volume847
DOIs
Publication statusPublished - 1 Oct 2017
Externally publishedYes

Cite this

@article{c912589c66dd4ec99ed3b5070bf20df8,
title = "From diferrocenyl-cyclopropenone to diferrocenyl-cyclopropenylium cations and triferrocenylpropenones: An electrochemical study",
abstract = "The reaction of 2,3-diferrocenylcyclopropenone (1) with the electrophiles H[BF4] and [Et3O][BF4], respectively, produced the corresponding cyclopropenylium cations [Fc(2)C(3)OH][BF4] (2) and [Fc(2)C(3)OEt] [BF4(]) (3) (Fc = Fe(eta(5)-C5H4)(eta(5)-C5H5)). Reacting 3 with HNEt2 afforded the NE(t)2-functionalized species [Fc(2)C(3)NEt(2)][BF4] (4). However, when 2 was reacted with nucleophiles such as FcLi a ring opening of the C-3 cycle was observed and E- and Z-1,2,3-triferrocenylpropenones Z-5 and E-5 were formed. Crystallization of a dichloromethane solution containing 3, layered with hexane, gave the BF3 adduct of diferrocenylcyclopropenone 6 at the interphase. The molecular solid state structures of Z-5, E-5 and 6 were determined by single crystal X-ray diffraction. Compound E-5 possesses a helical chirality and crystallizes in an enantiopure form. The electronic properties of the ferrocenyl-substituted cyclopropenylium cations 2-4 and of the triferrocenyl-alpha,beta-unsaturated ketones Z-5 and E-5 were studied by cyclic voltammetry and square wave voltammetry. In comparison to the cyclopropenone derivative 1, the ferrocenyl oxidation processes of the cyclopropenylium cations 2 and 3 are shifted towards higher potentials, which is caused by the lower electron density of the strained C-3 rings. Compound 4 decomposes during the electrochemical measurements. Furthermore, it could be shown that E/Z isomerism has only small effects on the electronic properties of the triferrocenyl-alpha, beta-unsaturated ketones. Spectroelectrochemical UV-Vis/NIR measurements carried out on 1 and Z-5 and E-5 confirmed electron-transfer interactions within the 2,3-diferrocenylcyclopropenone and the 1,2,3-triferrocenyl-alpha, beta-unsaturated ketones. However, the cyclopropenylium cations 2 and 3 show no long time stability under oxidative conditions. (C) 2017 Elsevier B.V. All rights reserved.",
keywords = "Ferrocenyl, Cyclopropenone, Cyclopropenylium, Solid state structure, (Spectro) Electrochemistry, METAL-METAL INTERACTIONS, ELECTRON-TRANSFER, 5-MEMBERED HETEROCYCLES, NONAQUEOUS SOLVENTS, DELTA-E-1/2 VALUES, MOLECULAR WIRES, COMPLEXES, SYSTEMS, 2,3-DIFERROCENYLCYCLOPROPENONE, FERROCENE",
author = "Lehrich, {Steve W.} and Alexander Hildebrandt and Marcus Korb and Heinrich Lang",
year = "2017",
month = "10",
day = "1",
doi = "10.1016/j.jorganchem.2017.03.018",
language = "English",
volume = "847",
pages = "105--113",
journal = "Journal of Organometallic Chemistry",
issn = "0022-328X",
publisher = "Elsevier Science & Technology",

}

From diferrocenyl-cyclopropenone to diferrocenyl-cyclopropenylium cations and triferrocenylpropenones : An electrochemical study. / Lehrich, Steve W.; Hildebrandt, Alexander; Korb, Marcus; Lang, Heinrich.

In: Journal of Organometallic Chemistry, Vol. 847, 01.10.2017, p. 105-113.

Research output: Contribution to journalArticle

TY - JOUR

T1 - From diferrocenyl-cyclopropenone to diferrocenyl-cyclopropenylium cations and triferrocenylpropenones

T2 - An electrochemical study

AU - Lehrich, Steve W.

AU - Hildebrandt, Alexander

AU - Korb, Marcus

AU - Lang, Heinrich

PY - 2017/10/1

Y1 - 2017/10/1

N2 - The reaction of 2,3-diferrocenylcyclopropenone (1) with the electrophiles H[BF4] and [Et3O][BF4], respectively, produced the corresponding cyclopropenylium cations [Fc(2)C(3)OH][BF4] (2) and [Fc(2)C(3)OEt] [BF4(]) (3) (Fc = Fe(eta(5)-C5H4)(eta(5)-C5H5)). Reacting 3 with HNEt2 afforded the NE(t)2-functionalized species [Fc(2)C(3)NEt(2)][BF4] (4). However, when 2 was reacted with nucleophiles such as FcLi a ring opening of the C-3 cycle was observed and E- and Z-1,2,3-triferrocenylpropenones Z-5 and E-5 were formed. Crystallization of a dichloromethane solution containing 3, layered with hexane, gave the BF3 adduct of diferrocenylcyclopropenone 6 at the interphase. The molecular solid state structures of Z-5, E-5 and 6 were determined by single crystal X-ray diffraction. Compound E-5 possesses a helical chirality and crystallizes in an enantiopure form. The electronic properties of the ferrocenyl-substituted cyclopropenylium cations 2-4 and of the triferrocenyl-alpha,beta-unsaturated ketones Z-5 and E-5 were studied by cyclic voltammetry and square wave voltammetry. In comparison to the cyclopropenone derivative 1, the ferrocenyl oxidation processes of the cyclopropenylium cations 2 and 3 are shifted towards higher potentials, which is caused by the lower electron density of the strained C-3 rings. Compound 4 decomposes during the electrochemical measurements. Furthermore, it could be shown that E/Z isomerism has only small effects on the electronic properties of the triferrocenyl-alpha, beta-unsaturated ketones. Spectroelectrochemical UV-Vis/NIR measurements carried out on 1 and Z-5 and E-5 confirmed electron-transfer interactions within the 2,3-diferrocenylcyclopropenone and the 1,2,3-triferrocenyl-alpha, beta-unsaturated ketones. However, the cyclopropenylium cations 2 and 3 show no long time stability under oxidative conditions. (C) 2017 Elsevier B.V. All rights reserved.

AB - The reaction of 2,3-diferrocenylcyclopropenone (1) with the electrophiles H[BF4] and [Et3O][BF4], respectively, produced the corresponding cyclopropenylium cations [Fc(2)C(3)OH][BF4] (2) and [Fc(2)C(3)OEt] [BF4(]) (3) (Fc = Fe(eta(5)-C5H4)(eta(5)-C5H5)). Reacting 3 with HNEt2 afforded the NE(t)2-functionalized species [Fc(2)C(3)NEt(2)][BF4] (4). However, when 2 was reacted with nucleophiles such as FcLi a ring opening of the C-3 cycle was observed and E- and Z-1,2,3-triferrocenylpropenones Z-5 and E-5 were formed. Crystallization of a dichloromethane solution containing 3, layered with hexane, gave the BF3 adduct of diferrocenylcyclopropenone 6 at the interphase. The molecular solid state structures of Z-5, E-5 and 6 were determined by single crystal X-ray diffraction. Compound E-5 possesses a helical chirality and crystallizes in an enantiopure form. The electronic properties of the ferrocenyl-substituted cyclopropenylium cations 2-4 and of the triferrocenyl-alpha,beta-unsaturated ketones Z-5 and E-5 were studied by cyclic voltammetry and square wave voltammetry. In comparison to the cyclopropenone derivative 1, the ferrocenyl oxidation processes of the cyclopropenylium cations 2 and 3 are shifted towards higher potentials, which is caused by the lower electron density of the strained C-3 rings. Compound 4 decomposes during the electrochemical measurements. Furthermore, it could be shown that E/Z isomerism has only small effects on the electronic properties of the triferrocenyl-alpha, beta-unsaturated ketones. Spectroelectrochemical UV-Vis/NIR measurements carried out on 1 and Z-5 and E-5 confirmed electron-transfer interactions within the 2,3-diferrocenylcyclopropenone and the 1,2,3-triferrocenyl-alpha, beta-unsaturated ketones. However, the cyclopropenylium cations 2 and 3 show no long time stability under oxidative conditions. (C) 2017 Elsevier B.V. All rights reserved.

KW - Ferrocenyl

KW - Cyclopropenone

KW - Cyclopropenylium

KW - Solid state structure

KW - (Spectro) Electrochemistry

KW - METAL-METAL INTERACTIONS

KW - ELECTRON-TRANSFER

KW - 5-MEMBERED HETEROCYCLES

KW - NONAQUEOUS SOLVENTS

KW - DELTA-E-1/2 VALUES

KW - MOLECULAR WIRES

KW - COMPLEXES

KW - SYSTEMS

KW - 2,3-DIFERROCENYLCYCLOPROPENONE

KW - FERROCENE

U2 - 10.1016/j.jorganchem.2017.03.018

DO - 10.1016/j.jorganchem.2017.03.018

M3 - Article

VL - 847

SP - 105

EP - 113

JO - Journal of Organometallic Chemistry

JF - Journal of Organometallic Chemistry

SN - 0022-328X

ER -