Fachbereich Chemie und Forschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany.
J Chem Phys. 2009 Nov 21;131(19):194305. doi: 10.1063/1.3264575.
Prior work on benzene activation by size selected niobium cluster cations and anions of up to 30 atoms is extended systematically through studying aromatic poly- and heterocyclic molecules such as naphthalene, pyridine, thiophene, pyrrole, furan, and benzofuran. Naphthalene is found to act much like benzene when reacting under single collision conditions with individual clusters. The most likely process is carbidization through complete dehydrogenation. Some clusters of particular sizes (most notably n=19) fail to activate both homocyclic molecules. Instead seemingly intact adsorption is observed which proves that activation is kinetically hindered at some point. All of the five studied heterocyclic aromatic molecules react unconditionally and by complete dehydrogenation with cationic niobium clusters, while they only attach to or react with anionic clusters larger than a minimum size of n=19-21. These findings are taken as strong evidence for initial coordination to the metal clusters of the heterocycles through their lone pair orbitals. The paper comprehends the observations in terms of cluster surface structure and reactivity.
通过研究萘、吡啶、噻吩、吡咯、呋喃和苯并呋喃等芳香族多环和杂环分子，系统地扩展了对尺寸选择的铌团簇阳离子和阴离子激活苯的先前工作。在与单个团簇进行单次碰撞反应时，萘的反应行为与苯非常相似。最有可能的过程是通过完全脱氢碳化。一些特定大小的团簇（最显著的是 n=19）未能激活同环分子。相反，观察到似乎完整的吸附，这证明在某个点上，活化受到动力学阻碍。在所研究的五个杂环芳香族分子中，所有分子都无条件地通过完全脱氢与铌阳离子团簇反应，而它们仅与大于 n=19-21 的最小尺寸的阴离子团簇附着或反应。这些发现被视为杂环通过孤对轨道最初与金属团簇配位的有力证据。本文根据团簇表面结构和反应性对观察结果进行了综合描述。
