Reactions of cationic iron clusters with ammonia, models of nitrogen hydrogenation and dehydrogenation

The gas phase reactivities of small cationic iron clusters, Fen+ (n = 1-20), towards ammonia were investigated using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Sequential addition of ammonia molecules to the clusters was observed to be the dominating process for n > 4....

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Veröffentlicht in:Dalton transactions : an international journal of inorganic chemistry 2004-03 (6), p.892-897
Hauptverfasser: Fossan, Kjell O, Uggerud, Einar
Format: Artikel
Sprache:eng
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Zusammenfassung:The gas phase reactivities of small cationic iron clusters, Fen+ (n = 1-20), towards ammonia were investigated using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry. Sequential addition of ammonia molecules to the clusters was observed to be the dominating process for n > 4. In the case of n = 4 we observed addition of ammonia accompanied by dehydrogenation. This reaction was modelled using hybrid density functional theory. Clusters with n < 4 do not react with ammonia. Clusters Fen+ (n = 1-20) react with neither N2 nor H2 at around 10(-8) mbar. When dinitrogen was seeded into the expanding helium, mixed clusters of the type FenNm+ were observed. These ions react with H2, either by addition, or by substitution of N2. The clusters with m = 1 were isolated in separate experiments and reacted with H2, which showed that mixed clusters with n = 5-13 add up to 5 molecules of dihydrogen in successive slow reactions.
ISSN:1477-9226
1477-9234
DOI:10.1039/B316600G