Bismuth-rich polyanions show a unique potential in constructing nanostructured bismuth-based materials, but they are still poorly investigated. We use a ternary precursor of the nominal composition "K 5 Ga 2 Bi 4 " for the formation of [K(crypt-222)] + salts of novel Bi-rich polyanions [Bi@Ga 8 (Bi 2 ) 6 ] q− (q = 3, 5; in 1), (Ga 2 Bi 16 ) 4− (in 2), and [{Ru(cod)} 4 Bi 18 ] 4− (in 3). Their bismuth contents exceed that of the largest homoatomic polyanion, Bi 11 3− . The numbers of bismuth atoms in the anions in 2 and 3 furthermore surmount that of the Bi-richest binary main-group anion, (Ge 4 Bi 14 ) 4− , and they equal (2) or surmount (3) that reported for the anion and the cations with the largest number of Bi atoms so far, [K 2 Zn 20 Bi 16 ] 6− , [(Bi 8 )Ru(Bi 8 )] 6+ , and [(Bi 8 )Au(Bi 8 )] 5+ . Compounds 1 and 2 were obtained from reaction mixtures that contain [La(C 5 Me 4 H) 3 ], apparently assisting in the network formation without being included in the products. In the presence of [Ru(cod)(H 2 CC(Me)CH 2 ) 2 ], yet another reaction pathway leads to the formation of the anions in 3 (conformers 3a and 3b), which are Bi−Bi linked dimers of two "[{Ru(cod)} 2 Bi 9 ] 2− " subunits. They comprise the largest connected assemblies of Bi atoms within one molecule and may be viewed as snapshots on the way toward even larger polybismuthide units and, ultimately, new bismuth modifications. Mass spectrometry allowed insight into the processes in solution that precede the cluster formation. In-depth quantum chemical studies were applied to explain structural peculiarities, stabilities of the observed isomers, and bonding characteristics of these bismuth-rich nanoarchitectures. The work demonstrates the high potential of the method for the access of new Bi-based materials.

Compounds containing (pseudo-)tetrahedral main group (semi-)metal units are fundamentally important in three regards. Firstly, they provide us with new strategies for the stabilization of tetrahedral units, such as Pn 4 (Pn = P, As) and their isoelectronic analogs, in the coordination sphere of d-/f-block metal atoms. Secondly, they serve as first-step models for the activation of tetrahedral molecules. Thirdly, they are starting materials for subsequent transformations towards larger clusters or materials. Partial or full isoelectronic replacement of the pnictogen atoms in P 4 or As 4 results in a variety of (pseudo-)tetrahedral anions, Tt 4 4− (Tt = Si, Ge, Sn, Si/Ge), (Ge3Pn) 3− (Pn = P, As; formed in situ), (Tt2Pn2) 2− (Tt/Pn = Ge/P, Ge/As, Sn/Sb, Sn/Bi, Pb/Sb, Pb/Bi), or (TrBi3) 2− (Tr = Ga, In, Tl), and also cations, (P3Ch) + (Ch = S, Se, Te). The anions proved to be excellent starting materials and building blocks for multinary clusters in the context of Zintl chemistry. Such compounds, which push forward the boundary of the intriguing P 4 chemistry, have never been thoroughly summarized before. In this mini review, we introduce all known intact (pseudo-)tetrahedral group 13−15 units, as well as the coordination compounds based on them, along with two new missing links, [Au(η 2 -Tt2Bi2)2] 3− (Tt = Sn, Pb).

The Zintl anion (Ge2As2)2− represents an isostructural and isoelectronic binary counterpart of yellow arsenic, yet without being studied with the same intensity so far. Upon introducing [(PPh3)AuMe] into the 1,2‐diaminoethane (en) solution of (Ge2As2)2−, the heterometallic cluster anion [Au6(Ge3As)(Ge2As2)3]3− is obtained as its salt [K(crypt‐222)]3[Au6(Ge3As)(Ge2As2)3]⋅en⋅2 tol (1). The anion represents a rare example of a superpolyhedral Zintl cluster, and it comprises the largest number of Au atoms relative to main group (semi)metal atoms in such clusters. The overall supertetrahedral structure is based on a (non‐bonding) octahedron of six Au atoms that is face‐capped by four (GexAs4−x)x− (x=2, 3) units. The Au atoms bind to four main group atoms in a rectangular manner, and this way hold the four units together to form this unprecedented architecture. The presence of one (Ge3As)3− unit besides three (Ge2As2)2− units as a consequence of an exchange reaction in solution was verified by detailed quantum chemical (DFT) calculations, which ruled out all other compositions besides [Au6(Ge3As)(Ge2As2)3]3−. Reactions of the heavier homologues (Tt2Pn2)2− (Tt=Sn, Pb; Pn=Sb, Bi) did not yield clusters corresponding to that in 1, but dimers of ternary nine‐vertex clusters, {[AuTt5Pn3]2}4− (in 2–4; Tt/Pn=Sn/Sb, Sn/Bi, Pb/Sb), since the underlying pseudo‐tetrahedral units comprising heavier atoms do not tend to undergo the said exchange reactions as readily as (Ge2As2)2−, according to the DFT calculations.

Reactions of the organotin selenide chloride clusters [(R Sn ) Se Cl] (A, R =CMe CH C(O)Me) or [(R Sn ) Se ] (B) with [Cu(PPh ) Cl ] yield cluster compounds with different inorganic, mixed-valence core structures: [Cu Sn Sn Se ], [Cu Sn Sn Se Cl ], [Cu Sn Sn Se ], [Cu Sn Sn Se Cl ], and [Cu Sn Se ]. Five of the compounds, namely [(CuPPh ) {(R Sn ) Se }] (1), [(CuPPh ) Sn {(R Sn ) Se } ] (2), [(CuPPh ) (Sn Cl) {(RSn ) Se } ] (3) [(CuPPh ) (Sn Cu ){(R Sn ) Se } ] (4), and [Cu(CuPPh )(Sn Cu ){(R Sn ) Se } ] (5) are structurally closely related. They are based on [(CuPPh ) {(RSn ) Se } ] aggregates comprising [(RSn ) Se ] and [CuPPh ] building units, which are linked by further metal atoms. A sixth compound, [(CuPPh ) (Sn Cl) {(R Sn Cl)Se } ] (6), differs from the others by containing [(RSn Cl)Se ] units instead, which affects the absorption properties. The compounds were analyzed by single-crystal X-ray diffraction, NMR and Sn Mössbauer spectroscopy, DFT calculations as well as optical absorption experiments.

Binary pseudo‐tetrahedral Zintl anions composed of (semi)metal atoms of the p‐block elements have proven to be excellent starting materials for the synthesis of a variety of heterometallic and intermetalloid transition metal–main group metal cluster anions. However, only ten of the theoretically possible 48 anions have been experimentally accessed to date as isolable salts. This brings up the question whether the other species are generally not achievable, or whether synthetic chemists just have not succeeded in their preparation so far. To contribute to a possible answer to this question, global minimum structures were calculated for all anions of the type (TrTt3)5−, (TrPn3)2−, and (Tt2Pn2)2−, comprising elements of periods 3 to 6 (Tr: triel, Al⋅⋅⋅Tl; Tt: tetrel, Si⋅⋅⋅Pb; Pn: pnictogen, P⋅⋅⋅Bi). By analyzing the computational results, a concept was developed to predict which of the yet missing anions should be synthesizable and why. Additionally, the results of an electrophilic attack by protons or trimethylsilyl groups or a nucleophilic attack by transition metal complex fragments are described. The latter yields butterfly‐like structures that can be viewed as a new form of adaptable tridentate chelating ligands.