Cluster compounds metalloid

This approach to the formation of metalloid molecular cluster compounds shows clearly the difference lfom Zintl-like phases which lately have been successfully... 

The clusters described so far have in common, that the number of metal atoms is less or equal than the number of substituents. However, there is a still growing number of both neutral and anionic clusters in which the number of metal atoms is larger than the number of substituents. As a consequence, these metal-rich clusters contain naked metal centers which are only bonded to other metal centers. Schnockel referred these ones to as metalloid clusters. Several metalloid A1 and Ga clusters were prepared by standard salt elimination reactions using metastable solutions of metal subhalides MX (M = Al, Ga X = Cl, Br) as well as solutions of Gal. Since the metal subhalides were found to play the key role for the successful synthesis of this particular class of compounds, they will be discussed first. (For excellent review articles see Refs 273 and 274.)... 

Schrenk C, Schellenberg I, Pottgen R et al (2010) The formation of a metalloid Snio[Si (SiMe3)3]g cluster compound and its relation to the alpha <->beta tin phase transition. Dalton Trans 39 1872-1876... 

A. Schnepf (2007) Chem. Soc. Rev., vol. 36, p. 745 - Metalloid group 14 cluster compounds An introductirm and perspectives to this novel group of cluster compounds. ... 

Schenk C, Henke F, Santiso-Quinones G, Krossing I, Schnepf A (2008) [Si(SiMe3)3]6GeigM (M = Cu, Ag, Au) metalloid cluster compounds as unusual building blocks for a supramo-lecular chemistry. Dalton Trans 4436... 

Schrenk C, Winter F, Pottgen R, Schnepf A (2012) Sn9[Si(SiMe3)3]2) a metalloid tin cluster compound with a Sng core of oxidation state zero. Inorg Chem 51 8583... 

The compound [Gai9 C(SiMe3)3 6F[Li2Br(THF)6]+ contains 11, the smallest metalloid gallium cluster with a shell-like structure discussed here. The gallium core of 11 contains 19 gallium atoms, 6 of which are connected to a trisyl ligand... 

The extraordinary bonding properties in 16 can also be seen in a diagram of 16 (Fig. 34). In 16, an almost perfect five-numbered axis is attained, distorted only by the central Ga2 unit. This is the first time that a symmetry close to the five-numbered symmetry is observed for molecular metalloid clusters. A few solid-state modifications with five-numbered symmetry have, however, been found for compounds involving Group 13 elements. Because there is no crystallographic space group with a five-numbered axis, these compounds are summarized under the collective name quasi-crystals .83 For a better understanding of quasi-crystals,... 

In a metalloid cluster [2] more metal-metal bonds than metal-ligand bonds are involved, which means n > r. The largest structurally characterized compounds of this type contain 77 A1 or 84 Ga atoms, respectively [3, 4], Metal-metal bonds dominate these clusters and the framework of the resulting metal-metal bonds exhibits a geometry similar to the bulk metal itself. With respect to the Greek word ei8o< (idea, prototype) the suffix -oid indicates that the bulk metal element is actually visible in the metal atom core of the metalloid or more generally, elementoid clusters. 

This section will focus on homonuclear neutral or anionic clusters of the elements aluminum, gallium, indium, and thallium, which have an equal number of cluster atoms and substituents. Thus, they may clearly be distinguished from the metalloid clusters described below, which in some cases have structures closely related to the allotropes of the elements and in which the number of the cluster atoms exceeds the number of substituents. The compounds described here possess only a single non-centered shell of metal atoms. With few exceptions, their structures resemble those of the well-known deltahedral boron compounds such as B4(CMe3)4 [30], B9CI9 [31] or [B H ]2 [32]. The oxidation numbers of the elements in these... 

However, mixtures of these products with some gallium rich metalloid clusters were formed so that this method is rather inadequate, and compounds 10-12 were isolated in very low yields. 

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