The Arachno‐Zintl Ion (Sn₅Sb₃)³⁻ and the Effects of Element Composition on the Structures of Isoelectronic Clusters: Another Facet of the Pseudo‐Element Concept

Abstract

The pseudo‐element concept, in its most general formulation, states that isoelectronic atoms form equal numbers of bonds. Hence, clusters such as Zintl ions usually retain their structure upon isoelectronic replacement of some or all atoms. Here, a deviation from this common observation is presented, namely the formation of (Sn5Sb3)3− (1), a rare example of an eight‐vertex Zintl ion, and an unprecedented example of a Zintl ion synthesized by solution means that has an arachno‐type structure according to the Wade–Mingos rules. Three structure‐types of interest for (Sn5Sb3)3− were identified by DFT calculations: one that matched the X‐ray diffraction data, and two that that were reminiscent of fragments of known clusters. A study on the isoelectronic series of clusters, (SnxSb8−x)2−x (x=0–8), showed that the relative energies of these three isomers vary significantly with composition (independent of electron count) and that each is the global minimum at least once within the series.

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

“…As the isoelectronic relationship between fragments {BH} and E atoms (E = Si-Pb), these rules have been long borrowed to illustrate and predict the related structures from group 14. [3] Expectedly, the closo-[E 5 ] 2À (E = Si, Ge, Sn, Pb) and [E 10 ] 2À (E = Ge, Pb) as an isostructural and isoelectronic species with corresponding boranes [B 5 H 5 ] 2À and [B 10 H 10 ] 2À have been isolated from solutions, [4] whereas the very stable closostructures limit their reactivity in solutions. [5] In contrast, the nido-clusters of [E 9 ] 4À (E = Si, Ge, Sn, Pb) and [E 4 ] 4À (E = Si, Ge, Sn) have exhibited good reactivity and accounted for a number of new derivatives, [6] such as oxidative coupling, [7] functionalization with main-group/transition-metal fragments, [8][9][10][11] cluster fusion and assembly.…”

Exploration of the potential energy surface in mixed Zintl clusters applying an automatic Johnson polyhedra generator: the case of arachno E6M24− (E = Si, Ge, Sn; M = Sb, Bi)

“…23–26 For instance, in 2020 they published the synthesis and characterization of Sn 5 Sb 3 3− . 27 The stability of this compound was studied by applying the pseudo-element concept which allows to establish that Zintl ions retain their structure after isoelectronic substitution. 27,28 In that work they also identified the structures and energies of the local minima of the (Sn x Sb 8− x ) 2− x ( x = 0–8) systems, from which we take Sn 6 Sb 2 4− as the initial system to perform isoelectronic substitutions.…”

“…27,28 In that work they also identified the structures and energies of the local minima of the (Sn x Sb 8− x ) 2− x ( x = 0–8) systems, from which we take Sn 6 Sb 2 4− as the initial system to perform isoelectronic substitutions. 27…”

Bridging Aromatic/Antiaromatic Units: Recent Advances in Aromaticity and Antiaromaticity in Main‐Group and Transition‐Metal Clusters from Bonding and Magnetic Analyses

“…The recognition of cage‐like clusters displaying spherical aromaticity, reported by Hirsch and coworkers, [36,47] enables the extension of the aromaticity concept to 3D species. Great advances in the synthesis and characterization of Zintl‐ion derivatives [48–67] gave rise to a relevant increase in the number of challenging aromatic species with a wide range of molecular architectures and compositions. Early relevant contributions to the field have been provided by Cummins, Scheer, Robinson, Power, Schnoeckel, Fischer, Fässler, Aldridge and Mountford, among other research groups, increasing the number of examples exhibiting aromaticity in inorganic clusters [68–82] …”