Al₂₀${{\rm Cp}{{\ast \hfill \atop 8\hfill}}}$X₁₀ (X=Cl, Br): Snapshots of the Formation of Metalloid Clusters from Polyhedral Al_nX_m Molecules?

Abstract

Dedicated to Professor Peter Paetzold on the occasion of his 70th birthdayTwo subgroups of Al-metal clusters with a predominant number of metal-metal bonds are known: [1] "naked" metalatom clusters, which are produced from solid metal by laser ablation techniques, and metalloid clusters, which are formed in solution starting with Al I species and, for example, subsequent reduction. [2,3] Here we present Al 20 Cp * 8 Br 10 (1) and Al 20 Cp * 8 Cl 10 (2) (Cp* = pentamethylcyclopentadienyl), two compounds of molecular, partially substituted subhalides belonging to the second group, which at first glance seem related to the species Al 13 I x À [4] and Al 14 I x À [5] (x = 1-12), which were generated in mass-spectrometric experiments. In both sets of compounds the halogen atoms form direct bonds to the Al atoms of the icosahedral Al 12 cluster core. However, quantum-chemical calculations for "naked" anionic clusters, for example, the Al 13 I x À anion mentioned above, indicate that an additional Al atom is located in the center.The structures of 1 and 2 are furthermore closely related to those of the recently characterized Al 22 X 20 compounds (X = Cl, Br), for example, Al 22 Br 20 (3) [6] because their cluster

From Icosahedral Boron Subhalides to Octahedral Metalloid Aluminum and Gallium Analogues: Quo vadis, Wade's Rules?

“…This structure, rated to be the most favorable isomer for 13/13 À and 14/14 À , is reminiscent of the structures of 10 and 11 in Figure 3, [24,25,27] and also to the structure of a recently synthesized Al 20 cluster [Al 20 Cp* 8 Cl 10 ] (Cp* = C 5 Me 5 ). [34] The preference of the metallic elements aluminum and gallium to form compounds with a metal-atom core exclusively bound to other metal atoms is not only demonstrated in the structurally characterized metalloid clusters, [13] but also in the simple model compounds presented herein. The polyhedral boron subhalides, however, very convincingly show their preference for icosahedral boron lattices with terminally bound ligands, that is, they follow the Wade-Mingos rules: the increasing metallic character down the group B, Al, and Ga clearly leads to a decrease in the applicability of the WadeMingos rules.…”

An Investigation of the Symmetric and Asymmetric Cleavage Products in the System Aluminum Trihalide/1‐Butylimidazole

“…Single-crystal X-ray structures Pr-Py), [5,8,9,11] [AlBr 2 (L) 4 ] + , [7] and [Al(L) 6 ] 3 + . [22,42] 6 ](Br) 3 ·3.5 MeCN} are shortert han the sum of the van der Waals radii (3.06 ), [43] but clearly longer the sum of the covalentr adii (1.51 ).…”

Growth of metalloid aluminum clusters on graphene vacancies

“…[19][20][21][22][23][24][25] Here we consider the use of graphene as a template for growing small metalloid aluminum clusters. The pioneering work of Schnöckel and co-workers has led to the development of many striking group 13 metalloid systems, [29][30][31][32][33][34][35] including the large Al 77 [N(SiMe 3 )] 2 20 , Al 50 Cp 1 2 ⇤ , and Si@Al 56 [N(2, 6-iPr 2 C 6 H 3 )SiMe 3 ] 12 . Metalloid clusters are often conceptualized as metastable intermediates on the way to formation of a bulk metal, and have been a) Author to whom correspondence should be addressed.…”