Redox-Switchable Chiral Anions and Cations Based on Heteroatom-Fused Biferrocenes

Jiawei Chen, Didier A. Murillo Parra, Roger Lalancette, Frieder Jaekle

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Abstract

A new class of planar chiral heteroatom-bridged biferrocene species was prepared using (pR,pR,SS,SS)-2,2″-bis(p-tolylsulfinyl)-1,1″-biferrocene (pR,pR,SS,SS)-2 as a readily accessible precursor. Initially, one of the sulfinate groups in compound 2 is replaced with a trimethylstannyl or dimesitylboryl group. Replacement of the second sulfinate group with t-BuLi then results in cyclization to give the Me2Sn-bridged species (pS,pS)-4Sn and the Mes2B-bridged borate anion [(pS,pS)-4B]-. The products are redox active, as cyclic and square wave voltammetry data of (pS,pS)-4Sn and [Li(12-c-4)2][(pS,pS)-4B] reveal two separate reversible oxidation events. The mixed-valent species [(pS,pS)-4Sn]+ and (pS,pS)-4B can also be obtained by chemical oxidation with AgPF6 or by simple exposure to air, respectively. A comparison of X-ray crystal structures reveals that the oxidized (mixed-valent) species contain distinct Fe(II) and Fe(III) sites, but UV-visible-NIR spectra display IVCT bands at ca. 4000 and 5000 cm-1, indicative of electronic coupling in solution. All compounds are obtained in enantiomerically pure form, suggesting potential use as switchable chiral anions and cations.

Original languageEnglish (US)
Pages (from-to)4323-4330
Number of pages8
JournalOrganometallics
Volume34
Issue number17
DOIs
Publication statusPublished - Sep 14 2015

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All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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