Bi34Ir3Br37: Ein pseudosymmetrisches Subbromid aus Bi5+- und Bi62+-Polykationen sowie [IrBi6Br12]–- und [IrBi6Br13]2–-Clusteranionen

Abstract

Aus der Schmelzreaktion von Ir mit Bi und BiBr3 werden schwarze, metallisch glänzende und luftbeständige Kristalle des Subbromids Bi34Ir3Br37 erhalten. Die trikline Kristallstruktur (Raumgruppe P 1, a = b = 1303,4(2) pm, c = 1647,4(4) pm, α = β = 90°, γ = 120°, V = 2423,7 · 106 pm3) täuscht die Pseudosymmetrie der rhomboedrischen Raumgruppe R 3 vor, was zu mehrfach verzwillingten Kristallen führt. Die Struktur läßt sich formal in vier neuartige Typen ionischer Baugruppen aufgliedern: (a) kuboktaedrische [IrBi6Br12]–‐Cluster, (b) um ein Br‐Atom erweiterte [IrBi6Br13]2–‐Cluster, (c) quadratisch‐pyramidale Bi5+‐ und (d) verzerrt oktaedrische Bi62+‐Polykationen. Die Substanz zeigt eine Phasenbreite, die auf veränderliche Anteile der verschiedenen Cluster zurückgeführt werden kann.

Ab Initio Calculations on Bismuth Cluster Polycations

“…Unfortunately, the amount of information on this cation is not sufficient for a definitive conclusion. The cation has been characterized within one compound only, Bi 34 Ir 3 Br 37 , [29] and is described by the author as a distorted octahedron. However, with one vertex more than 0.3 closer to the equatorial plane than the other, it is possible to interpret Bi 6 2 not as a unit, but rather as an associate of two other speciesÐthe Bi 5 and Bi cations.…”

“…Moreover, two new bismuth polycationsÐBi 5 and Bi 6 2 Ð were recently discovered within the structure of the Bi 34 Ir 3 Br 37 compound, [29] of which only the former cluster obeys Wades rules. Thus, the question of the applicability of Wades rules to the bismuth polycations has not received a definite answer.…”

Bismuth Polyanions in Solution: Synthesis and Structural Characterization of (2, 2, 2-crypt-A)2Bi4 (A = K, Rb) and the Formation of the Laves Phases ABi2 (A = K, Rb, Cs) from Solution

“…Ein Mechanismus zur Bildung von ABi 2 wird vorgeschlagen. least postulated, since the late 60s, with Bi 5 ϩ and Bi 6 2ϩ being recent additions to the family [10], although for the latter two weak covalent interactions with surrounding anions might be possible. All these cluster polycations were isolated and characterized in inorganic solid state as salts with MX n lϪ halogenometallates as anions.…”

Reprint of “Coordination chemistry of homoatomic ligands of bismuth, selenium and tellurium”

“…Very recently, the first anionic bismuth polyhedron, the Zintl anion Bi 11 3− , has been isolated [16]. Besides the observation of anionic bismuth Zintl ions, such as Bi 7 3− , in the gas-phase were reported [17]. The newly discovered chain Bi 4 6− is the bismuth polyanion with the highest known charge per atom obtained from solution [18].…”

“…An expanded version is also known, the [MBi 6 X 13 ] (n+1)− cluster, which bears an additional 3 -bridging X anion above one face of the bismuth octahedron (Fig. 1c) [7,8]. In some cases the plausible charge of such an anionic cluster has been used to derive the less predictable counter-charge of a polycation in the structure.…”