Reactions of 13CO with ethoxycarbonylcarbene-bridged dicobalt carbonyl complexes: [μ2-{ethoxycarbonyl(methylene)} μ2-(carbonyl)-bis(tricarbonylcobalt)(Co-Co)] and [Di-μ2-{ethoxycarbonyl(methylene)}-bis(tricarbonylcobalt)(Co-Co)]

Eszter Fördos, Neszta Ungvári, Tamás Kégl, Ferenc Ungváry

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

In a CH2Cl2 solution, under an atmospheric pressure of 13CO, the bridging and terminal CO ligands of the cobalt complex [μ2-{ethoxycarbonyl(methylene)}-μ2-(carbonyl) bis(tricarbonylcobalt)(Co-Co)] (1) exchange with external 13CO at the same rate. The overall rate of CO exchange is kobs (10°C) = 9.4 × 10-3 s-1 and kobs (25°C) = (20.1 ± 1.2) × 10-3 s-1. In the presence of excess ethanol diethyl malonate (DEM), EtO213CCH 2CO2Et is formed from 1 at a much smaller rate [k DEM (10°C) = 0.40 × 10-5 s-1 and kDEM (25°C) = (1.2 ± 0.1) × 10-5 s -1]. On the other hand, the complex [di-μ2- {ethoxycarbonyl(methylene)}bis(tricarbonylcobalt)(Co-Co)] (2) does not exchange its CO ligands for 13CO at all at 10 or 25°C. In the presence of excess ethanol, diethyl malonate with natural isotopic distribution, and 13CO, ligands containing complex 1 are formed simultaneously and at the same rate, which is kobs (10°C) = (15.2 ± 1.1) × 10-5 s-1 and kobs (25°C) = (33.5 ± 1.8) × 10-5 s-1. Variable temperature 13C NMR spectra of 1 and 2 reveal fluxional behavior for both complexes.

Original languageEnglish
Pages (from-to)1875-1880
Number of pages6
JournalEuropean Journal of Inorganic Chemistry
Issue number9
DOIs
Publication statusPublished - May 8 2006

Keywords

  • C-C coupling
  • Carbene and carbonyl ligands
  • Cobalt
  • Fluxionality
  • Isotopic labeling

ASJC Scopus subject areas

  • Inorganic Chemistry

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