Synthesis and oxidation of chiral rhenium phosphine methyl complexes of the formula (η5-C5Me5)Re(NO)(PR3)(CH3): In search of radical cations with enhanced kinetic stabilities

Wayne E. Meyer, Angelo J. Amoroso, Monika Jaeger, Jean Le Bras, Wing Tak Wong, J. A. Gladysz

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14 Citations (Scopus)

Abstract

Reactions of racemic [(η5-C5Me5)Re(NO)(NCCH3)(CO)]+BF-4and phosphines PR3(R = C6H5a; 4-C6H4CH3b; 4-C6H4-t-C4H9c; 4-C6H4C6H5d; 4-C6H4OCH3e; C-C6H11f) give the phosphine carbonyl complexes [(η5-C5Me5)Re(NO)(PR3)(CO)]+BF-4(5a-5f+BF-4; 55-95%). These are treated with LiEt3BH and then BH3·THF to give the phosphine methyl complexes (η5-C5Me5)Re(NO)(PR3)(CH3) (2a-2f, 50-86%). Cyclic voltammetry shows that the new compounds 2b-2f undergo chemically reversible one-electron oxidations that are thermodynamically more favorable than that of 2a (ΔE○ = 0.07, 0.07, 0.01, 0.09, 0.22 V; CH2Cl2). The radical cations 2•+X-can be generated with Ag+X-or (η5-C5H5)2Fe•+X-(X-= PF-6, SbF-6), as evidenced by IR and ESR spectra, but are labile and efforts to isolate pure salts fail. Reaction of 2a and TCNE give (η5-C5Me5)Re(NO)(η2-TCNE)(CH3), which is crystallographically characterized and proposed to form by initial electron transfer followed by radical chain substitution.
Original languageEnglish
Pages (from-to)44-53
Number of pages10
JournalJournal of Organometallic Chemistry
Volume616
Issue number1-2
DOIs
Publication statusPublished - 15 Dec 2000
Externally publishedYes

Keywords

  • Cyclic voltammetry
  • ESR
  • Radical cations
  • Rhenium
  • TCNE

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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