[Ga₂₂(PtBu₂)₁₂]: Diversity in the Arrangement of 22 Gallium Atoms—A Unique Case in the Field of Metalloid Clusters?

Abstract

Dedicated to Professor Nils Wiberg on the occasion of his 70th birthdayWith the formation of three different Ga 22 frameworks in metalloid clusters, the element gallium assumes a unique position in the field of metal clusters, [1] since to our knowledge, structural isomers of large metalloid clusters are not known to date for any other metal. Here we report an additional structural variation in the arrangement of 22 gallium atoms, in which for the first time an icosahedral Ga 12 core is retained despite extensive reduction of the Ga 22 framework (average oxidation number 0.55). We have previously achieved low oxidation numbers for Ga 22 clusters only when gallium-centered arrangements were present in the cluster core (oxidation number 0.36, Figure 1): [Ga 22 R 8 ] (1) with R = SitBu 3 (1 a), [2] Si(SiMe 3 ) 3 (1 b), [3] and Ge(SiMe 3 ) 3 (1 c) [4] as well as [Ga 22 R 10 ] 2À (2) with R = N(SiMe 3 ) 2 ; [5] the coordination numbers of the central Ga atoms are 13 for 1 and 11 for 2. In contrast, in the case of the only previously obtained Ga 22 cluster with an icosahedral Ga 22 core (without a central Ga atom), [Ga 22 {N(SiMe 3 ) 2 } 10 Br 10 ] 2À (3), [6] the average oxidation number of 0.82 is not very different from that of the GaX starting material. This is also true for the first polyhedral gallium subhalide [Ga 24 X 22 ] (4) [7] (average oxidation number 0.92), which can be viewed as a common precursor (possibly in a slightly modified form, such as [Ga 22 X 20 ], which is analogous to the well-known [Al 22 X 20 ] [8] ) for the numerous

Second-Order Phase Transitions in Amorphous Gallium Clusters

“…It is worth noting that gallium is the only metal where the metal core of inorganic clusters (i.e., clusters with ligands) show structural isomers. The Ga 22 core, for example, has recently been shown to have at least four different arrangements . This structural flexibility is consistent with the amorphous behavior indicated by our results for some (naked) cluster sizes.…”

Development of the Chemistry of Indium in Formal Oxidation States Lower than +3

“…And no better sign of that advance has come than with the results conjured within the past decade by Schnöckel and his group at Karlsruhe 6-9 and witnessed by the synthesis and characterization of such exotic species as [Al 50 (η 5 -C 5 Me 5 ) 12 ] ( 1 ), [Al 77 {N(SiMe 3 ) 2 } 20 ] 2- ( 2 ), [Ga 22 R 8 ] [R = Si(SiMe 3 ) 3 , Ge(SiMe 3 ) 3 , or Si t Bu 3 ] ( 3a ), [Ga 22 (P t Bu 2 ) 12 ] ( 3b ), [Ga 22 -{N(SiMe 3 ) 2 } 10 ] 2- ( 3c ), [Ga 22 {N(SiMe 3 ) 2 } 10 Br 10+ x ] n - ( x = 1, n = 3; x = 2, n = 2) ( 3d ), [Ga 51 (P t Bu 2 ) 14 Br 6 ] 3- ( 4 ), [Ga 84 {N(SiMe 3 ) 2 } 20 ] n - ( n = 3, 4) ( 5 ), and [Ge 9 {Si(Si-Me 3 ) 3 } 3 ] - ( 6 ) (see Figure ). It is through the intercession of bulky ligands to control the disproportionation of a univalent derivative of the metal that these ligand-sheathed clusters are formed.…”