The reactions of matrix-isolated Ti, V, or Nb atoms with ethene (C(2)H(4)) have been studied by FTIR absorption spectroscopy. Under conditions where the ethene dimer forms, metal atoms react with the ethene dimer to yield matrix-isolated ethane (C(2)H(6)) and methane. Under lower ethene concentration conditions ( approximately 1:70 ethene/Ar), hydridic intermediates of the types HMC(2)H(3) and H(2)MC(2)H(2) are also observed, and the relative yield of hydrocarbons is diminished. Reactions of these metals with perdeuterioethene, and equimolar mixtures of C(2)H(4) and C(2)D(4), yield products that are consistent with the production of ethane via a metal atom reaction involving at least two C(2)H(4) molecules. The absence of any other observed products suggests the mechanism also involves production of small, highly symmetric species such as molecular hydrogen and metal carbides. Evidence is presented suggesting that ethane production from the ethene dimer is a general photochemical process for the reaction of excited-state transition-metal atoms with ethene at high concentrations of ethene.

/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...