Hollow Gold Cages and Their Topological Relationship to Dual Fullerenes

Abstract

Golden fullerenes have recently been identified by photoelectron spectra by Bulusu et al. [S. Bulusu, X. Li, L.-S. Wang, X. C. Zeng, PNAS 2006, 103, 8326-8330]. These unique triangulations of a sphere are related to fullerene duals having exactly 12 vertices of degree five, and the icosahedral hollow gold cages previously postulated are related to the Goldberg-Coxeter transforms of C20 starting from a triangulated surface (hexagonal lattice, dual of a graphene sheet). This also relates topologically the (chiral) gold nanowires observed to the (chiral) carbon nanotubes. In fact, the Mackay icosahedra well known in gold cluster chemistry are related topologically to the dual halma transforms of the smallest possible fullerene C20 . The basic building block here is the (111) fcc sheet of bulk gold which is dual to graphene. Because of this interesting one-to-one relationship through Euler's polyhedral formula, there are as many golden fullerene isomers as there are fullerene isomers, with the number of isomers Niso increasing polynomially as O(Niso9 ). For the recently observed Au16- , Au17- , and Au18- we present simulated photoelectron spectra including all isomers. We also predict the photoelectron spectrum of Au32- . The stability of the golden fullerenes is discussed in relation with the more compact structures for the neutral and negatively charged Au12 to Au20 and Au32 clusters. As for the compact gold clusters we observe a clear trend in stability of the hollow gold cages towards the (111) fcc sheet. The high stability of the (111) fcc sheet of gold compared to the bulk 3D structure explains the unusual stability of these hollow gold cages.

D6h‐Au42 Isomer: A Golden Aromatic Toroid Involving Superatomic π‐Orbitals that Follow the Hückel (4n+2)π rule

“…Further exploration of the potential energy surface for Au 42 results in a high‐lying isomer displaying a symmetric toroid‐like structure. The topological relationship between spherical and toroidal conformations has been explored for fullerenes, which in turn can be extended to golden fullerenes . Thus, this structure is a toroidal analogue of the spherical I h ‐Au 42 golden cage.…”

“…The topological relationship between spherical and toroidal conformations has been explored for fullerenes, [51] which in turn can be extended to golden fullerenes. [52] Thus, this structure is at oroidal analogueo ft he spherical I h -Au 42 golden cage. The new isomer is 157 kcal mol À1 higheri n energy than D 5 d-Au 42 ,s howing as ymmetrical D 6 h structure, hereafter denoted as D 6 h-Au 42 .T his finding prompted us to evaluatet his new structure as the first analogue for cyclic hydrocarbons, involving ar ing purely formed by connecting superatomic clusters.…”

On the formation of smaller p‐block endohedral fullerenes: Bonding analysis in the E@C20 (E = Si, Ge, Sn, Pb) series from relativistic DFT calculations

“…The discovery of C 60 by Kroto and coworkers in 1985, followed by its isolation in useful quantities by Krätschemer and Huffman initiated an new era of carbon nanotechnology resulting in a variety of interdisciplinary applications of technological interest . Such carbon clusters, commonly known as fullerenes, have attracted considerable attention in different fields of science owing to their novel physical, chemical, and biological properties in addition to their aesthetically pleasing molecular architectures …”

A Ligand‐Protected Golden Fullerene: The Dipyridylamido Au328+ Nanocluster

“…Metal nanoclusters have attracted immense interest owing to their fundamental importance and technological applications in catalysis, biology, and nanoscale devices . Since the discovery of the T d ‐Au 20 pyramid, golden cages have emerged as a new class of clusters owing to their unusual structural features . Johansson, Gong et al.…”