Preparation and Precise Structural Determination of a Second Ga₈₄Cluster Compound. A First Hint for Cluster Doping and Its Fundamental Consequences in the Field of Chemistry and Physics of Nanoscaled Metalloid Cluster Material

Abstract

The Ga(84)R(20)(4-) [R = N(SiMe(3))(2)] species, which represents the largest metalloid cluster entity structurally characterized so far, has been electronically and topologically modified: Via changing the redox potential of the reaction solution, crystals different from those containing the Ga(84)R(20)(4-) anion can be isolated, featuring similar Ga(84)R(20)(3-) entities. An accurate crystal structure analysis via synchrotron radiation is presented, which might be the first step toward an understanding of the metallic conductivity and superconductivity of the Ga(84)R(20)(4-) cluster compound, physical properties which are singular in the field of metalloid clusters so far.

Two Metalloid Ga22 Clusters Containing a Novel Ga22 Core with an Icosahedral Ga12 Center

“…[1] This Ga 22 cluster and two analogous compounds containing different substituents (Ge(SiMe 3 ) 3 and SitBu 3 ) show that the cluster core of 14 naked Ga atoms (1 central atom surrounded by 13 atoms) is the preferred central arrangement for 22 Ga atoms (Figure 1 a). [2,3] Recently we have prepared a further metallic shining Ga 22 compound, namely [GaGa 11 -(GaR) 10 ] 2À , R= N(SiMe 3 ) 2 , which has a different framework of the Ga atoms (Figure 1 b). [4] The topological relations of the Ga 22 units within these two types of Ga 22 clusters, each of which contains a central Ga atom, to the structure of one of the high-pressure allotropes of elemental gallium have been discussed in a review recently.…”

“…The neutral, metallic shining compound [Ga 22 {Si(SiMe 3 ) 3 } 8 ] presented the first example of a metalloid Ga n cluster. [1] This Ga 22 cluster and two analogous compounds containing different substituents (Ge(SiMe 3 ) 3 and SitBu 3 ) show that the cluster core of 14 naked Ga atoms (1 central atom surrounded by 13 atoms) is the preferred central arrangement for 22 Ga atoms (Figure 1 a).…”

“…[2,3] Recently we have prepared a further metallic shining Ga 22 compound, namely [GaGa 11 -(GaR) 10 ] 2À , R= N(SiMe 3 ) 2 , which has a different framework of the Ga atoms (Figure 1 b). [4] The topological relations of the Ga 22 units within these two types of Ga 22 clusters, each of which contains a central Ga atom, to the structure of one of the high-pressure allotropes of elemental gallium have been discussed in a review recently. [5] In the following we present a completely different type of Ga 22 cluster: An icosahedral Ga 12 unit without a central Ga atom, which is surrounded by 10 further Ga atoms directly bonded through two-center, two-electron (2c2e) bonds: [Ga 22 Br{N(Si- …”

27Al NMR Study of the Metal Cluster Compound Al50C120H180

“…Indeed, recently compelling evidence was obtained from 69,71 Ga-NMR studies [16] for the occurrence of band-type conductivity by intercluster charge transfer in crystallographically fully characterized Ga 84 cluster compounds, composed of giant Ga 84 cluster molecules that display mixed-valency properties [17,18]. In addition bulk superconductivity has been observed for these compounds [19][20][21] below a transition temperature T c % 8 K, much higher in fact than known for bulkGa metal ( T c % 1 K).…”

[Ga51(PtBu2)14Br6]3−: An Elementoid Gallium Cluster with Metalloid and Nonmetalloid Structural Elements

“…In addition to the threefold negative charge of 1 a, a partial lower charge (for example 1À), which could be balanced by a dilution in the cationic lattice of the Li 3 Bi lattice structure of the Ga 51 cluster (see Figure 4), is also conceivable for 1. Since according to latest results, the cluster 4 could be present as both a threeand fourfold negatively charged species in the same crystal, [21] such cluster doping could provide an approach for the clarification of the so far not understood conductivity phenomena.…”