Metal Cluster Catalysis:  A Kinetic and Mechanistic Study of the Carbonylation of Methanol to Give Methyl Formate as Catalyzed by [Et4N]2[Fe3(CO)9E] (E = S, Se, Te)

The cluster compounds [Et4N]2[Fe3(CO)9E] (E = S, Se, Te) catalyze the homogeneous carbonylation of methanol to form methyl formate under moderate CO pressures (600−1200 psi) between 50 and 90 °C. A detailed kinetic analysis of this system shows that the reaction is first order with respect to cluste...

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Bibliographic Details
Published in:Organometallics 2003-04, Vol.22 (9), p.1914-1922
Main Authors: Guzman-Jimenez, Ilse Y, van Hal, Jaap W, Whitmire, Kenton H
Format: Article
Language:English
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Summary:The cluster compounds [Et4N]2[Fe3(CO)9E] (E = S, Se, Te) catalyze the homogeneous carbonylation of methanol to form methyl formate under moderate CO pressures (600−1200 psi) between 50 and 90 °C. A detailed kinetic analysis of this system shows that the reaction is first order with respect to cluster concentration and quasi-second order with respect to the pressure of CO. All three cluster compounds show similar behavior. The reaction appears to be almost independent of the [CH3O-]total at values of [CH3O-]total ≤ 3 × 10-3 M, but at higher concentrations it appears to be first-order dependent on [CH3O-]total. This system affords the opportunity to compare the effects of different main group heteroatoms in a homologous series. The rates of the reaction were found to lie in the following order:  Te (6 × 10-4 M·min-1) > S (4 × 10-4 M·min-1) > Se (2 × 10-4 M·min-1) at 1200 psi and 90 °C. The activation energies were found to be 43 ± 11 kJ·mol-1 (E = S), 76 ± 8 kJ·mol-1 (E = Se), and 72 ± 7 kJ·mol-1 (E = Te). The rate dependence upon CO pressure suggests a mechanism in which metal−metal bond opening is important.
ISSN:0276-7333
1520-6041
DOI:10.1021/om020548+