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Homoleptic Naked Clusters of Endohedral Zintl Ions

dc.contributor.advisorEichhorn, Bryan Wen_US
dc.contributor.authorNalbant-Esenturk, Emrenen_US
dc.date.accessioned2006-06-14T05:36:57Z
dc.date.available2006-06-14T05:36:57Z
dc.date.issued2006-03-31en_US
dc.identifier.urihttp://hdl.handle.net/1903/3387
dc.description.abstractNanoclusters are of interest because of their remarkable catalytic properties and their application in nanotechnology fields. There is a strong preference toward bimetallic systems due to their superior catalytic properties compare to monometallic systems. Synthetic protocols are developed by using polyatomic main group clusters (Zintl ions) for making new bimetallic nano-catalysts. In this study, new, free standing, transition metal stabilized Zintl ions have been isolated. They are promising candidates to be used both in nanotechnology and heterogeneous catalysis. [M@Pb<sub>12</sub>]<sup>2-</sup> (M = Ni, Pd, Pt) are the <em>first isolated</em> free-standing centered icosahedra without any attendant of ligands. The anions contain naked Pb<sub>12</sub> icosahedra clusters encapsulating Group 10 transition metals and posses near perfect I<sub>h</sub> point symmetry. These endohedral naked metal clusters have nontraditional spherical aromatic electronic structures. They are the smallest members of the nanoparticle growth sequence, M<sub>13</sub> (centered icosahedra), with hcp lattices. Their positive chemical shifts in <sup>207</sup>Pb NMR spectra contradict theoretical chemical shift calculations of isostructural aromatic clusters. A new type of Zintl ion, [Ni@Pb<sub>10</sub>]<sup>2-</sup>, has also been synthesized. The anion contains Ni atom centered in a closo-Pb<sub>10</sub><sup>2-</sup> bicapped square antiprism, and possesses virtual D<sub>4d</sub> point symmetry. It is the first isolated ten atom, homoatomic naked Zintl ion cluster. The Pt and Pd analogs, and non-metallated Pb<sub>10</sub> and Pb<sub>12</sub> clusters have also been observed in the gas phase by LDI-TOF-MS. NMR spectroscopy was used to investigate unusual dynamic behaviors of the one focus [Ni@Pb<sub>10</sub>]<sup>2-</sup> and two focus [Ni<sub>2</sub>Sn<sub>17</sub>]<sup>4-</sup> anions and both demonstrated surprising global atomic mobility. The latter has a capsule like structure having central Sn atom with coordination number of eight. This extraordinary high coordination of the central Sn is more akin to solid state compounds. The [Ge<sub>9</sub>Ni<sub>2</sub>(PPh<sub>3</sub>)]<sup>2-</sup> anion is the new example of Zintl ion, which do not adopt Wadian type structure. Another Ni-Ge system with exciting structure, [Ni<sub>6</sub>Ge<sub>13</sub>(CO)<sub>5</sub>]<sup>4-</sup> is also isolated. The anion has interpenetrating biicosahedral structure which is unique to Zintl ion chemistry. The potential interconversion of [Ge<sub>9</sub>Ni<sub>2</sub>(PPh<sub>3</sub>)]<sup>2-</sup> and [Ni<sub>6</sub>Ge<sub>13</sub>(CO)<sub>5</sub>]<sup>4-</sup> have been investigated through ESI-MS studies.en_US
dc.format.extent12104004 bytes
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.titleHomoleptic Naked Clusters of Endohedral Zintl Ionsen_US
dc.typeDissertationen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.contributor.departmentChemistryen_US
dc.subject.pqcontrolledChemistry, Inorganicen_US
dc.subject.pquncontrolledZintl ionsen_US
dc.subject.pquncontrolledcluster compoundsen_US
dc.subject.pquncontrolledaromaticityen_US
dc.subject.pquncontrolledinclusion compoundsen_US


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