Supraicosahedral polyhedra in carboranes and metallacarboranes: The role of local vertex environments in determining polyhedral topology and the anomaly of 13-vertex closo polyhedra

Density functional theory (DFT) at the hybrid B3LYP level has been applied to the germanium clusters Ge14z (z = –8, –6, –4, –2, 0, +2, +4) starting from seven different initial configurations. An Oh omnicapped cube structure is the most stable for Ge142– followed by a hexagonal antiprism structure with a relative energy of 42.7 kcal/mol. The lowest‐energy structure for neutral Ge14 is a triplet omnicapped cube with full Oh symmetry followed by a singlet omnicapped cube compressed to D4h symmetry through Jahn–Teller distortion. The lowest energy Ge142+ structure is also an Oh structure derived from the omnicapped cube through elongation of the 12 edges of the underlying cube to give a rhomboidal dodecahedron with 12 rhombus faces. The lowest‐energy Ge124+ structure is a bicapped icosahedron. Some D6h hexagonal wheel structures at higher energies are also found for the hypoelectronic systems Ge14, Ge142+, and Ge144+. The lowest‐energy structures for the hyperelectronic Ge144–, Ge146–, and Ge148– are relatively unsymmetrical not readily recognizable open structures typically with some pentagonal or hexagonal faces. The D6d bicapped hexagonal antiprism found in 14‐vertex C2B12 carborane and M2C2B10 dimetallacarborane structures is not the lowest‐energy structure for any of the Ge14z clusters.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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Beyond the Icosahedron: The Quest for High-Nuclearity Supraicosahedral Metallaboranes

Roy

Ghosh

Halet

2013

J Clust Sci

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International audienceA novel spiroborate-based double-stranded helicate bearing photoresponsive cis-stilbene units in the middle (cis-3) was successfully synthesized from the corresponding cis-stilbene-bound tetraphenol strand in the presence of NaBH4, whereas the tetraphenol strands with a trans-stilbene or trans-azobenzene unit did not form such a double-stranded helicate. The 1H NMR and NOESY expts. revealed that cis-3 adopted contracted (cis-3C) and extended (cis-3E) forms under equil. in CD3CN at 25 °C. The contracted cis-3C that accommodated a Na+ ion in the center showed an almost reversible extension and contraction motion by removal and addn. of a Na+ ion. The cis-to-trans photoisomerisation of the extended cis-3E with UV light (295 nm) further induced an extension of the helicate, producing a mixt. of cis,trans-3E and trans-3E helicates at the photostationary state. However, trans-to-cis photoisomerisation of the trans-mixts. using UV light (360 nm) was irreversible in this system and produced the photooxidated aldehyde species (trans-4), resulting from the photo-cleavage of the trans-stilbene moieties of the trans-3E

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Supraicosahedral polyhedra in carboranes and metallacarboranes: The role of local vertex environments in determining polyhedral topology and the anomaly of 13-vertex closo polyhedra

Cited by 18 publications

References 47 publications

Supraicosahedral Polyhedra in Carboranes and Metallacarboranes: The Role of Local Vertex Environments in Determining Polyhedral Topology and the Anomaly of 13‐Vertex closo Polyhedra

Supraicosahedral Polyhedra in Carboranes and Metallacarboranes: The Role of Local Vertex Environments in Determining Polyhedral Topology and the Anomaly of 13‐Vertex closo Polyhedra

Beyond the Icosahedron: A Density Functional Theory Study of 14‐Atom Germanium Clusters

Beyond the Icosahedron: The Quest for High-Nuclearity Supraicosahedral Metallaboranes

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