The influence of polarizability in metal cluster reactions as seen in the reactions of gas-phase W clusters with cyclopropane

Pedersen, David Bue; Parnis, J. Mark; Rayner, D. M.

doi:10.1063/1.476591

Cited by 10 publications

(4 citation statements)

References 15 publications

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“…The flow-tube apparatus has also been described previously. − In these experiments, the pressed Al-cytosine rod was ablated with ∼80 mJ pulse -1 308 nm laser light focused to a 1 mm diameter spot. A continuous flow of He (15 000 sccm) was maintained over the rod.…”

Section: Methodsmentioning

confidence: 99%

Photoinduced Charge-Transfer Dehydrogenation in a Gas-Phase Metal-DNA Base Complex: Al-cytosine

et al. 2002

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An Al-cytosine association complex has been generated via laser ablation of a mixture of aluminum and cytosine powders that were pressed into a rod form. The ionization energy of the complex is found to be 5.16 +/- 0.01 eV. The photoionization efficiency spectrum of Al-cytosine has also been collected. DFT calculations indicate that binding of Al to cytosine manifests a significant weakening of the N-H bond, predicted to have a strength of 1.5 eV in the complex, and a significant stabilization of the oxo tautomeric form relative to the hydroxy forms. The predicted ionization energy of 5.2 eV agrees well with the experimental value. The threshold for dehydrogenation/ionization of Al-cytosine, forming (Al-cytosine-H)+, is found to occur at photoexcitation energies between 11.4 and 12.8 eV. This is a two-photon process that is proposed to occur via photoinduced electron transfer from Al to an antibonding (sigma) orbital localized on N-H. In the context of this mechanism, this work constitutes the first time charge transfer between a metal and DNA base has been photoinitiated in the gas phase.

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Section: Methodsmentioning

confidence: 99%

Photoinduced Charge-Transfer Dehydrogenation in a Gas-Phase Metal-DNA Base Complex: Al-cytosine

et al. 2002

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“…The apparatus in the two configurations used in this work has been described in detail , and therefore only a brief description is given here. Clusters are generated using a Smalley-type laser ablation source.…”

Section: Methodsmentioning

confidence: 99%

Cluster Size Selectivity in the Product Distribution of Ethene Dehydrogenation on Niobium Clusters

et al. 2005

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/npsi/ctrl?action=rtdoc&an=12327971&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=12327971&lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1021/jp0506944The Journal of Physical Chemistry A, 109, 32, pp. 7046-7056, 2005-07- Sciences, National Research Council of Canada, 100 Sussex DriVe, Ottawa, Ontario, Canada K1A 0R6 ReceiVed: February 8, 2005; In Final Form: May 13, 2005 Ethene reactions with niobium atoms and clusters containing up to 25 constituent atoms have been studied in a fast-flow metal cluster reactor. The clusters react with ethene at about the gas-kinetic collision rate, indicating a barrierless association process as the cluster removal step. Exceptions are Nb 8 and Nb 10 , for which a significantly diminished rate is observed, reflecting some cluster size selectivity. Analysis of the experimental primary product masses indicates dehydrogenation of ethene for all clusters save Nb 10 , yielding either Nb n C 2 H 2 or Nb n C 2 . Over the range Nb-Nb 6 , the extent of dehydrogenation increases with cluster size, then decreases for larger clusters. For many clusters, secondary and tertiary product masses are also observed, showing varying degrees of dehydrogenation corresponding to net addition of C 2 H 4 ,C 2 H 2 ,o rC 2 . With Nb atoms and several small clusters, formal addition of at least six ethene molecules is observed, suggesting a polymerization process may be active. Kinetic analysis of the Nb atom and several Nb n cluster reactions with ethene shows that the process is consistent with sequential addition of ethene units at rates corresponding approximately to the gas-kinetic collision frequency for several consecutive reacting ethene molecules. Some variation in the rate of ethene pick up is found, which likely reflects small energy barriers or steric constraints associated with individual mechanistic steps. Density functional calcu...

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“…The success of the model indicates that the physical size of clusters, or some other extensive cluster property, plays a major role in determining rates of reactions in nonactivated systems. In more recent work, we have discussed the implications that cluster polarizability has on reactivity in determining the collision rate and the stability of physisorbed precursor states, which serve as intermediates in many cluster reactions . In the Nb n −isobutane reaction the rates of reaction lie in the 10 -13 to 10 -12 cm 3 s -1 range, 2−3 orders of magnitude below the expected collision rate.…”

Section: Introductionmentioning

confidence: 99%

Association Complex Formation in Gas-Phase Ta Cluster Reactions with Simple Alkanes: Probing the Role of Entropy in Rate Determination for Barrierless Adsorption Processes

et al. 2004

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Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. NRC Publications Record / Notice d'Archives des publications de CNRC:http://nparc.cisti-icist.nrc-cnrc.gc.ca/eng/view/object/?id=47a49c3c-8e01-40c8-a243-942fbc62a9eb http://nparc.cisti-icist.nrc-cnrc.gc.ca/fra/voir/objet/?id=47a49c3c-8e01-40c8-a243-942fbc62a9eb Sciences, National Research Council of Canada, 100 Sussex DriVe, Ottawa, Ontario K1A OR6, Canada ReceiVed: October 1, 2003; In Final Form: February 1, 2004 Rate coefficients for the reactions of ethane, propane, n-butane, isobutane, and neopentane with Ta atoms and Ta clusters consisting of up to 30 Ta atoms have been measured in a fast-flow reactor. A near-monotonic dependency of the rate coefficients on cluster size is observed for each of these hydrocarbons, with the exception of Ta 11 , which exhibits rate coefficients that are several times that observed for the analogous reaction with Ta 10 and Ta 12 , for propane, n-butane, and isobutane. Modeling the general trend in the rate coefficients using transition state theory is found to require a relatively loose transition state with free rotation of the hydrocarbon about the bonding point on the cluster, consistent with the rate-determining step being cluster removal by an association reaction process. It is demonstrated that, in general, metal cluster reactions with reagents that can form strongly bound association complexes may exhibit little evidence of cluster-size-based selectivity in the rate of cluster removal, despite exhibiting significant selectivity in terms of the extent of the dehydrogenation reaction involved.

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The influence of polarizability in metal cluster reactions as seen in the reactions of gas-phase W clusters with cyclopropane

Cited by 10 publications

References 15 publications

Photoinduced Charge-Transfer Dehydrogenation in a Gas-Phase Metal-DNA Base Complex: Al-cytosine

Photoinduced Charge-Transfer Dehydrogenation in a Gas-Phase Metal-DNA Base Complex: Al-cytosine

Cluster Size Selectivity in the Product Distribution of Ethene Dehydrogenation on Niobium Clusters

Association Complex Formation in Gas-Phase Ta Cluster Reactions with Simple Alkanes: Probing the Role of Entropy in Rate Determination for Barrierless Adsorption Processes

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