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Thermal NH Bond Activation on Anionic and Cationic Platinum Clusters: Non‐Predetermined Reaction Pathways Indicate Transitions to a Bulk Surface Reactivity
Author(s) -
Ončák Milan,
Cao Yali,
Höckendorf Robert F.,
Beyer Martin K.,
Zahradník Rudolf,
Schwarz Helmut
Publication year - 2009
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200900677
Subject(s) - cationic polymerization , platinum , reactivity (psychology) , thermal , chemistry , materials science , catalysis , polymer chemistry , organic chemistry , thermodynamics , physics , medicine , alternative medicine , pathology
Reactions of cationic and anionic platinum clusters Pt n +/− , n =1–5, with NH 3 are studied by FT‐ICR mass spectrometry and DFT calculations. With cationic clusters, radiative association of an intact NH 3 is the dominant reaction channel. On anionic clusters, NH 3 undergoes reductive elimination of molecular hydrogen, with nitride and hydride bound at remote sites of the cluster. Nitride assumes a bridge position, while hydride is bound atop a single platinum atom. On the [Pt n ,NH 3 ] − potential energy surface, for n =4 fifteen local minima and connecting transition states were identified with relevance to the hydrogen formation reaction, and 12 local minima were identified for n =5. These potential energy surfaces offer a rich variety of pathways, illustrating a key feature of a successful bulk catalyst: The variety of pathways helps the catalyst to work over a wide range of temperatures and pressures.