Variable temperature13C MAS NMR of KFe2Mn(CO)12 in the solid state and as aCatalyst precursor on a carbon support |
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Authors: | George W Wagner Andrew A Chen M Albert Vannice |
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Affiliation: | (1) Present address: School of Chemical Sciences, University of Illinois at Urbana-Champaign, 61801 Urbana, IL, USA;(2) Department of Chemical Engineering, 16802 University Park, PA, USA |
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Abstract: | Variable temperature13C MAS NMR spectra are reported for13CO-enriched KFe2Mn(CO)12 as a solid and also as dispersed clusters on a carbon support. The spectrum of KFe2Mn(CO)12 at 300 K agrees with the proposed structure for this cluster and shows that the cluster is static. Two bridging carbonyl resonances are clearly resolved and, by comparison with13C MAS NMR spectra of Mn2(CO)10 and Fe2(CO)9, all terminal resonances for the cluster can be assigned. When the cluster is supported on carbon, two broad resonances are observed at room temperature which are assignable to KFe2Mn(CO)12 and a decomposition product, Mn2(CO)10. The carbonyl ligands in both supported clusters are completely averaged, and KFe2Mn(CO)12 on the carbon surface demonstrates fluxional behavior similar to that observed for the cluster in solution. For this fluxional process, activation energies of 0.6 kcal/mol and 0.5 kcal/mol are estimated for carbon-supported KFe2Mn(CO)12 and Mn2(CO)10, respectively. |
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Keywords: | Nuclear magnetic resonance for catalyst characterization KF2Mn(CO)12 as catalyst precursor |
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