Reactions of triphenylphosphane-substituted ethoxycarbonylcarbene-bridged dicobalt carbonyl complexes with carbon monoxide or 13CO: An experimental and theoretical study

Neszta Ungvári, Eszter Fördos, Tamás Kégl, Ferenc Ungváry

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

In CH2Cl2 solution and under a carbon monoxide atmosphere the cobalt complexes [μ2-{ethoxycarbonyl(methylene)}-μ2-(carbonyl)-bis(triphenylphosphanedicarbonyl-cobalt) (Co-Co)] (4) and [μ2-{ethoxycarbonyl(methylene)}-μ2-(carbonyl)-(tricarbonyl-cobalt)-(triphenylphosphanedicarbonyl-cobalt) (Co-Co)] (3) are in equilibrium. The equilibrium constant K = [3][PPh3]/[4][CO] at 10 °C is 1.03 ± 0.11. The bridging and terminal CO ligands in complex 3 or 4 exchange with external 13CO simultaneously. In accord with that variable-temperature 13C NMR spectra reveal fluxional behavior for both complexes. The overall rate constant of 13CO-exchange for 3 at 10 °C is 17 × 10-3 s-1 and for 4 at 10 °C is 26 × 103 s-1. In the case of complex 4 the concentration of PPh3 has practically no influence on the rate of the 13CO-exchange reaction and on the rate of the reaction with CO. The coupling of the μ2-ethoxycarbonylcarbene ligand and one of the coordinated carbon monoxide is at least one order of magnitude slower than the 13CO-exchange reactions, and is faster in complex 4 than in complex 3. The partial pressure of carbon monoxide has practically no effect on the coupling reaction.

Original languageEnglish
Pages (from-to)1333-1342
Number of pages10
JournalInorganica Chimica Acta
Volume362
Issue number4
DOIs
Publication statusPublished - Mar 2 2009

Keywords

  • CC coupling
  • Carbene, carbonyl and phosphane ligands
  • Cobalt
  • Density functional calculations
  • Isotopic labeling

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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