Heteroatom-Bridged ortho-Biferrocenes: Stereoselective Synthesis, Structural Features, and Electrochemical Properties

Jiawei Chen, Alain C. Tagne Kuate, Roger A. Lalancette, Frieder Jäkle

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

A versatile synthetic protocol is described for the synthesis of heteroatom-bridged biferrocene derivatives, including the symmetric species 2-SnSn and the planar-chiral species 2-SnSi, 2-BSi, and 2-SnP. Treatment of (pR,SS)-2-lithio-1-(p-tolylsufinyl)-ferrocene with 0.5 equiv of Me2SnCl2 afforded the tin-bridged biferrocene 1-Sn. A second Sn, Si, or P bridge was then incorporated by substitution of the sulfinyl group in the ortho-position with a dimethylstannyl, dimethylsilyl, or tert-butylphosphino group, respectively, to give the doubly bridged biferrocenes 2-SnSn, 2-SnSi, and 2-SnP. The dimethylstannyl moiety of 2-SnSi was subsequently replaced with a borane bridge via a two-step transmetalation procedure comprising treatment with HgCl2, followed by PhBCl2. The formation of ferrocene-fused six-membered heterocycles was confirmed by multinuclear NMR spectroscopy and high-resolution MS analyses. The stereochemical configuration of the chiral biferrocenes 2-SnSi, 2-SnP, and 2-BSi was studied by single-crystal X-ray diffraction, chiral HPLC, and optical rotation measurements. The redox characteristics and absorption properties were investigated as well. The longest wavelength absorption experienced a bathochromic shift and an increase in intensity for 2-BSi relative to 2-SnSn and 2-SnSi, indicative of significant charge transfer character. The cyclic voltammograms of 2-SnSn and 2-SnSi displayed two separate one-electron oxidations as expected for the presence of two ferrocene units in close proximity to one another. The incorporation of boron in 2-BSi resulted in an anodic shift of both oxidation waves and an enlarged peak potential separation. The chemical oxidation of 2-BSi was carried out with [Ag(CH2Cl2)]{Al[OC(CF3)3]4}, and the reaction was monitored by NMR spectroscopy. Attempts to crystallographically characterize the corresponding doubly oxidized species proved unsuccessful.

Original languageEnglish (US)
Pages (from-to)1964-1972
Number of pages9
JournalOrganometallics
Volume35
Issue number11
DOIs
StatePublished - Jun 13 2016

Fingerprint

Electrochemical properties
Oxidation
Nuclear magnetic resonance spectroscopy
oxidation
synthesis
Boranes
Optical rotation
Mercuric Chloride
nuclear magnetic resonance
Boron
boranes
Tin
shift
spectroscopy
Charge transfer
proximity
tin
boron
Substitution reactions
charge transfer

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

Cite this

@article{01e4fcfdd1f940b1ac0f0d2dd46e3147,
title = "Heteroatom-Bridged ortho-Biferrocenes: Stereoselective Synthesis, Structural Features, and Electrochemical Properties",
abstract = "A versatile synthetic protocol is described for the synthesis of heteroatom-bridged biferrocene derivatives, including the symmetric species 2-SnSn and the planar-chiral species 2-SnSi, 2-BSi, and 2-SnP. Treatment of (pR,SS)-2-lithio-1-(p-tolylsufinyl)-ferrocene with 0.5 equiv of Me2SnCl2 afforded the tin-bridged biferrocene 1-Sn. A second Sn, Si, or P bridge was then incorporated by substitution of the sulfinyl group in the ortho-position with a dimethylstannyl, dimethylsilyl, or tert-butylphosphino group, respectively, to give the doubly bridged biferrocenes 2-SnSn, 2-SnSi, and 2-SnP. The dimethylstannyl moiety of 2-SnSi was subsequently replaced with a borane bridge via a two-step transmetalation procedure comprising treatment with HgCl2, followed by PhBCl2. The formation of ferrocene-fused six-membered heterocycles was confirmed by multinuclear NMR spectroscopy and high-resolution MS analyses. The stereochemical configuration of the chiral biferrocenes 2-SnSi, 2-SnP, and 2-BSi was studied by single-crystal X-ray diffraction, chiral HPLC, and optical rotation measurements. The redox characteristics and absorption properties were investigated as well. The longest wavelength absorption experienced a bathochromic shift and an increase in intensity for 2-BSi relative to 2-SnSn and 2-SnSi, indicative of significant charge transfer character. The cyclic voltammograms of 2-SnSn and 2-SnSi displayed two separate one-electron oxidations as expected for the presence of two ferrocene units in close proximity to one another. The incorporation of boron in 2-BSi resulted in an anodic shift of both oxidation waves and an enlarged peak potential separation. The chemical oxidation of 2-BSi was carried out with [Ag(CH2Cl2)]{Al[OC(CF3)3]4}, and the reaction was monitored by NMR spectroscopy. Attempts to crystallographically characterize the corresponding doubly oxidized species proved unsuccessful.",
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Heteroatom-Bridged ortho-Biferrocenes : Stereoselective Synthesis, Structural Features, and Electrochemical Properties. / Chen, Jiawei; Tagne Kuate, Alain C.; Lalancette, Roger A.; Jäkle, Frieder.

In: Organometallics, Vol. 35, No. 11, 13.06.2016, p. 1964-1972.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Heteroatom-Bridged ortho-Biferrocenes

T2 - Stereoselective Synthesis, Structural Features, and Electrochemical Properties

AU - Chen, Jiawei

AU - Tagne Kuate, Alain C.

AU - Lalancette, Roger A.

AU - Jäkle, Frieder

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N2 - A versatile synthetic protocol is described for the synthesis of heteroatom-bridged biferrocene derivatives, including the symmetric species 2-SnSn and the planar-chiral species 2-SnSi, 2-BSi, and 2-SnP. Treatment of (pR,SS)-2-lithio-1-(p-tolylsufinyl)-ferrocene with 0.5 equiv of Me2SnCl2 afforded the tin-bridged biferrocene 1-Sn. A second Sn, Si, or P bridge was then incorporated by substitution of the sulfinyl group in the ortho-position with a dimethylstannyl, dimethylsilyl, or tert-butylphosphino group, respectively, to give the doubly bridged biferrocenes 2-SnSn, 2-SnSi, and 2-SnP. The dimethylstannyl moiety of 2-SnSi was subsequently replaced with a borane bridge via a two-step transmetalation procedure comprising treatment with HgCl2, followed by PhBCl2. The formation of ferrocene-fused six-membered heterocycles was confirmed by multinuclear NMR spectroscopy and high-resolution MS analyses. The stereochemical configuration of the chiral biferrocenes 2-SnSi, 2-SnP, and 2-BSi was studied by single-crystal X-ray diffraction, chiral HPLC, and optical rotation measurements. The redox characteristics and absorption properties were investigated as well. The longest wavelength absorption experienced a bathochromic shift and an increase in intensity for 2-BSi relative to 2-SnSn and 2-SnSi, indicative of significant charge transfer character. The cyclic voltammograms of 2-SnSn and 2-SnSi displayed two separate one-electron oxidations as expected for the presence of two ferrocene units in close proximity to one another. The incorporation of boron in 2-BSi resulted in an anodic shift of both oxidation waves and an enlarged peak potential separation. The chemical oxidation of 2-BSi was carried out with [Ag(CH2Cl2)]{Al[OC(CF3)3]4}, and the reaction was monitored by NMR spectroscopy. Attempts to crystallographically characterize the corresponding doubly oxidized species proved unsuccessful.

AB - A versatile synthetic protocol is described for the synthesis of heteroatom-bridged biferrocene derivatives, including the symmetric species 2-SnSn and the planar-chiral species 2-SnSi, 2-BSi, and 2-SnP. Treatment of (pR,SS)-2-lithio-1-(p-tolylsufinyl)-ferrocene with 0.5 equiv of Me2SnCl2 afforded the tin-bridged biferrocene 1-Sn. A second Sn, Si, or P bridge was then incorporated by substitution of the sulfinyl group in the ortho-position with a dimethylstannyl, dimethylsilyl, or tert-butylphosphino group, respectively, to give the doubly bridged biferrocenes 2-SnSn, 2-SnSi, and 2-SnP. The dimethylstannyl moiety of 2-SnSi was subsequently replaced with a borane bridge via a two-step transmetalation procedure comprising treatment with HgCl2, followed by PhBCl2. The formation of ferrocene-fused six-membered heterocycles was confirmed by multinuclear NMR spectroscopy and high-resolution MS analyses. The stereochemical configuration of the chiral biferrocenes 2-SnSi, 2-SnP, and 2-BSi was studied by single-crystal X-ray diffraction, chiral HPLC, and optical rotation measurements. The redox characteristics and absorption properties were investigated as well. The longest wavelength absorption experienced a bathochromic shift and an increase in intensity for 2-BSi relative to 2-SnSn and 2-SnSi, indicative of significant charge transfer character. The cyclic voltammograms of 2-SnSn and 2-SnSi displayed two separate one-electron oxidations as expected for the presence of two ferrocene units in close proximity to one another. The incorporation of boron in 2-BSi resulted in an anodic shift of both oxidation waves and an enlarged peak potential separation. The chemical oxidation of 2-BSi was carried out with [Ag(CH2Cl2)]{Al[OC(CF3)3]4}, and the reaction was monitored by NMR spectroscopy. Attempts to crystallographically characterize the corresponding doubly oxidized species proved unsuccessful.

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