(Multi‐)Metallic Cluster Growth

Abstract

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 a family of rhodium polystannide clusters [Rh@Sn10]3–, [Rh@Sn12]3–, [Rh2@Sn17]6–and the first triply-fused stannide, [Rh3@Sn24]5–

“…The intimate pathways by which these larger clusters form from smaller component parts have not proven easy to establish for a number of reasons. First, there is rarely a precise stoichiometric relationship between reactants and products, and extensive fragmentation and recombination is clearly an integral feature of cluster growth 26,27. In addition, the under-coordinated nature of the intermediates leads to facile rearrangements that frustrate attempts to follow their formation and decay in real time.…”

Electronic structure and bonding in endohedral Zintl clusters

“…The reduced anionic charge in the heteroatomic group 14/15 clusters confers significant advantages in terms of both stability and solubility, and these binary P 4 analogues show great promise as synthons for the growth of larger, multinary clusters. 19,21,36,121 One drawback, however, is that the characterisation of multi-metallic, as opposed to homo-nuclear, cluster units, is complicated by the difficulties associated with differentiating elements with similar atomic numbers using X-ray diffraction. In such circumstances, careful computational surveys of the potential energy surfaces have allowed the favoured positions of atoms that are neighbours in the periodic table to be established.…”

Current advances in tin cluster chemistry

“…Indeed, the mechanisms of cluster growth remain a mostly speculative aspect in this chemistry due to short reaction times and a lack of spectroscopic handles. 130 Very recently, another report was published that again provides some indirect evidence for a possible cluster formation pathway. Reactions of K 4 Sn 9 with [(coe) 2 Rh(m-Cl)] 2 (coe ¼ cyclooctene) afford a series of Rh-centered polystannide clusters: [Rh@Sn 10 ] 3À , [Rh@Sn 12 ] 3À , [Rh 2 @Sn 17 ] 6À and [Rh 3 @Sn 24 ] 5À (Fig.…”