Stabilizing a metalloid {Zn12} unit within a polymetallide environment in [K2Zn20Bi16]6−

Abstract

The access to molecules comprising direct Zn–Zn bonds has become very topical in recent years for various reasons. Low-valent organozinc compounds show remarkable reactivities, and larger Zn–Zn-bonded gas-phase species exhibit a very unusual coexistence of insulating and metallic properties. However, as Zn atoms do not show a high tendency to form clusters in condensed phases, synthetic approaches for generating purely inorganic metalloid Znx units under ambient conditions have been lacking so far. Here we show that the reaction of a highly reductive solid with the nominal composition K5Ga2Bi4 with ZnPh2 at room temperature yields the heterometallic cluster anion [K2Zn20Bi16]6–. A 24-atom polymetallide ring embeds a metalloid {Zn12} unit. Density functional theory calculations reveal multicenter bonding, an essentially zero-valent situation in the cluster center, and weak aromaticity. The heterometallic character, the notable electron-delocalization, and the uncommon nano-architecture points at a high potential for nano-heterocatalysis.

Insights into Formation and Relationship of Multimetallic Clusters: On the Way toward Bi-Rich Nanostructures

“…27 We recently showed that this solid yields not only said binary anion but also Bi-rich cluster species. 28,45 To expand these studies, we performed reactions in the presence of two mildly Lewis-acidic metal complexes, [La-(C 5 Me 4 H) 3 ] and [Ru(cod)(H 2 CC(Me)CH 2 ) 2 ], which we considered suitable for assisting in the assembly of {Bi n } building units, as the anticipated interaction with the anionic precursor are neither purely ionic nor too strongly covalent. In this way, we obtained single-crystalline compounds [K(crypt-222)] 3.67 [Bi@Ga 8 (Bi •solv (solv = 4.63thf•2en, 3a; solv = none, 3b), comprising the highest bismuth content in clusters reported so far.…”

“…Scheme 1 summarizes the new findings, which will be discussed in detail below, and all related findings based on the K/Ga/Bi system that were reported previously. 27,28,41,44,45,52 With this study, we contribute to the formation of the largest known consecutively linked polybismuthide architectures and to first insights into the formation of corresponding clusters.…”

[Sn8]6−‐Bridged Mixed‐Valence ZnI/ZnIIin {[K2ZnSn8(ZnMes)]2}4−Inverse Sandwich‐Type Cluster Supported by a ZnI−ZnIBond

“…[8c, 9a,c, 12b, 17] The distances from the bases of Sn 8 units to their capped Zn atoms are in a very narrow range of 2.7768-( 18)-2.8014 (18) , comparing well with those of 2.7397(4)-2.7867(4) in [Sn 9 ZnPh] 3À , [9c] 3) ) is only slightly longer than those in [Ge 9 Zn-ZnGe 9 ] 6À (2.420( 1) ) [15] and other monovalent organozinc species (2.305( 3)-2.430( 1) ), [18] but shorter than the Zn-Zn distances (2.544( 3)-2.831( 5) ) in [K 2 Zn 20 Bi 16 ] 6À . [19] To understand the chemical bonding and electronic structure of the investigated cluster, we performed density functional theory (DFT) calculations. All DFT calculations were performed using Gaussian 16 software [20] at PBE0/def2TZVP level of theory.…”

Electronic structure and bonding in endohedral Zintl clusters

“…[26][27][28][29][30][31] In contrast to molecules containing (mainly) non-metal atoms where 2-centre-2-electron (2c-2e) bonding dominates (aliphatic and non-aromatic carbon compounds, for example), the increasingly inert nature of the ns electrons in the heavier (semi)metal atoms in Zintl clusters tends to favour electron delocalization and multi-centre-bonding. 83,84 While the finite size of known Zintl clusters (o50 atoms) prevents them from becoming truly metallic on a molecular scale, the typically intense colours (red to brownish black) of salts with sequestrated cations point to narrow HOMO-LUMO gaps. This small band gap can lead to applications in (photo)catalysis, and also makes Zintl clusters precursors of novel nanostructured or doped metals and intermetallic phases.…”