Cationic Vinylidene Complexes. Preparation and Structural Characterization of (η5-Cyclopentadienyl)(2-methyl-4,5-bis(diphenylphosphino)-2-penten-3-yl)iron (II). A Base-Induced Interligand Reaction in a Vinylidene Complex

Richard D. Adams, Davison Alan, John P. Selegue

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85 Scopus citations

Abstract

The cationic vinylidene complex [(Cp)Fe(dppe)(C=C(CH3)2|][SO3F] (la) (dppe = 1,2-bis(diphenylphosphino)-ethane), prepared by the methylation of (Cp)Fe(dppe)(C≡CCH3) (II), is smoothly deprotonated by potassium hydroxide or sodium bis(trimethylsilyl)amide. The exclusive product is (Cp) Fe[Ph2PCH2CH(PPh2C =C(CH3)2] (III), which contains a novel ferradiphospha[2.1.1]bicyclohexane ring system. This product was investigated by spectroscopic and crystal structure analysis: space group Cc, a = 14.738 (4) Å b = 12.471 (5) Å c = 16.982 (7) Å β = 106.17 (3)°, V = 2997 (4) Å3, Z = 4, ρclacd = 1 -268 g/cm3. Refinement on 1668 reflections with F02 > 3σ(F02) has yielded the final discrepancy indices R = 0.058 and Rw = 0.060. The bicyclic ring system shows geometric and spectroscopic features which indicate that significant torsional strain is present. The formation of III has been explained by the intermediacy of a zwitterionic complex containing both a deprotonated dppe ligand ([Ph2PCH2CHPPh2]) and a cationic vinylidene moiety. Subsequent intramolecular cyclization produces III.

Original languageEnglish
Pages (from-to)7232-7238
Number of pages7
JournalJournal of the American Chemical Society
Volume101
Issue number24
DOIs
StatePublished - Feb 1 1979

ASJC Scopus subject areas

  • Catalysis
  • Chemistry (all)
  • Biochemistry
  • Colloid and Surface Chemistry

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