[Ga18(SitBu3)8] and [Ga22(SitBu3)8]--syntheses and structural characterization of novel gallium cluster compounds

Higher stability of metalloid tin clusters obtained via the cation-anion interaction

The reaction of a metastable SnCl solution with KR (R = Si(SiMe₃)₂(SitBuMe₂) = Hyp^tBuMe₂ or Si(SiMe₃)₂(SiEt₃) = Hyp^Et₃) gives the metalloid tin cluster [Sn₁₀R₄]^2- in partly good yields. The tin clusters are in the solid state as well in solution coordinated by a potassium cation, leading first of all to a more static compound and novel coordination polymers in the solid state. Additionally, the coordination of the potassium cation strongly increases the stability of the cluster in solution. This higher stability is thereby an important prerequisite for future investigation of this open shell metalloid tin cluster.

Superatomic Gallium Clusters in Dendrimers: Unique Rigidity and Reactivity Depending on their Atomicity

Superatoms have been investigated due to their possible substitution for other elements. The solution-phase synthesis of superatoms has attracted attention to realize the availability of superatoms. However, the previous approach is basically limited to the formation of a single cluster. Here, superatoms are investigated and the number of valence electrons in these superatoms is changed by designing the number of gallium atoms present. Based on the dendrimer template method, clusters consisting of 3, 12, 13, and other numbers of atoms have been synthesized. The halogen-like superatomic nature of Ga₁₃ is structurally and electrochemically observed as completely different to the other clusters. The gallium clusters of 13 and 3 atoms, which can fill the 2P and 1P superatomic orbitals, respectively, exhibit different reactivities. The 3-atom gallium cluster is suggested as being reduced to Ga₃ H₂ ^- due to the lower shift of energy levels in the unoccupied orbitals. The results for these gallium clusters provide candidates for superatoms.

(Multi-)Metallic Cluster Growth

This review article provides a survey of contemporary investigations on main group metal cluster formation, addressing homo- and heterometallic clusters (including small numbers of transition metal atoms), with or without an external ligand shell, thereby excluding clusters with non-metal atoms as bridging ligands. Most of the studies reflected herein represent insights into the formation of intermediates from the starting material, or the final cluster formation from established intermediates. In rare cases, the entire process was suggested as a result of comprehensive, multi-method elucidations. The article is to be understood as a state-of-the-art report, as the subject matter is currently a rising field of research, which is still in its infancy, despite some early activities that date back to the 1980s. At the same time, the article intends to point toward both the importance and the feasibility of according studies, in order to encourage researchers to gain even more knowledge in this field. Only deep understanding of cluster formation will allow for design, and ultimately control, of their syntheses, with the long-term goal of their optimization and purposeful application in catalysis or novel material synthesis.

Synthesis and structure of tri- and octaindium compounds

The reactions of InCp* with alkali metal silanides M(thf)(n)SiRPh(2) (R = Me, Ph) resulted in the triindanate [(Ph(3)Si)(3)In-In-In(SiPh(3))](-) with a linear arrangement of In atoms and the octaindium clusters [(In(8)(SiPh(3))(8)](m-) (m = 0, 2) amongst others, which were characterized by X-ray crystallography. The neutral cluster has a bisphenoidal core similar to that of B(8)Cl(8), whilst the anionic one adopts a distorted square antiprismatic structure. In addition, the tri- and octaindium compounds were studied by DFT calculations.

A Second Metalloid Ga18 Cluster and Its Topological Similarity to the High-Pressure Ga-II Modification

The topology of many modifications of elemental gallium is reflected in the large variety of metalloid Ga clusters that have been isolated as intermediates on the way from the metastable molecular GaX species (X=Cl, Br, I) by means of disproportionation to the bulk metal. Herein, we report the synthesis and characterization of the first metalloid cluster anion [Ga(18)(PtBu(2))(10)](3-) with the singular core topology that resembles the gallium high-pressure modification Ga-II. The stabilization of the cluster anion through ion-pair contacts with a chainlike "Li(4)Br(2) backbone" is discussed. Furthermore, the compound is discussed in context of the other metalloid clusters Ga(18)R(8) and Ga(22)R(8) (R=SitBu(3)) and their structural relation to the elemental modifications Ga-III and beta-Ga, respectively.

Metalloid Al- and Ga-clusters: a novel dimension in organometallic chemistry linking the molecular and the solid-state areas?

Formation and fragmentation of metal-metal bonds on the way between stable metal compounds in which the metal atoms are oxidised (e.g. isolated species in solution or metal salts in bulk) and the bulk metal are the fundamental steps to understand this process in which formation and chemical behaviour of metalloid Al and Ga clusters as intermediates are essential. Many examples of metalloid Al and Ga clusters show that their formation reflects a high degree of complexity like that of the simple seeming formation of the bulk metal itself: starting from metastable Al(i) and Ga(i) solutions containing small molecular entities, metalloid clusters grow during many self-organization steps including aggregation as well as irreversible redox cascades. This novel class of clusters seems to open a new dimension in chemistry between the molecular and the solid-state area, because, for the first time, it is shown that under well selected conditions definite molecular species, i.e. metalloid clusters, grow via the formation of additional metal-metal bonds and that the solid metal represents the final step.