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The existence of [μ‐HSi4]3− in liquid ammonia solutions is confirmed by 1H and 29Si NMR experiments. Both NMR and quantum chemical calculations reveal that the H atom bridges two Si atoms of the [Si4]4− cluster, contrary to the expectation that it is located at one vertex Si of the tetrahedron. The calculations also indicate that in the formation of [μ‐HSi4]3−, protonation is driven by a high charge density and an increase of electron delocalization compared to [Si4]4−. Additionally, [Si5]2− was detected for the first time and characterized by NMR. Calculations show that it is resistant to protonation, owing to a strong charge delocalization, which is significantly reduced upon protonation. Thus, our methods reveal three silicides in liquid ammonia: unprotonated [Si5]2−, terminally protonated [HSi9]3−, and bridge‐protonated [μ‐HSi4]3−. The protonation trend can be roughly predicted by the difference in charge delocalization between the parent compound and the product, which can be finely tuned by the presence of counter ions in solution. [ABSTRACT FROM AUTHOR]

Wir berichten von dem asymmetrischen Einschluss eines einzelnen Metallatoms in einen 12‐atomigen Cluster. Drei Salze verwandter intermetalloider Clusteranionen, [Co@Sn6Sb6]3− (1), [Co2@Sn5Sb7]3− (2) und [Ni2@Sn7Sb5]3− (3) wurden synthetisiert, die pseudo‐C4v‐ oder pseudo‐D4h‐symmetrische 12‐atomige Sn/Sb‐Clusterhüllen und interstitielle Co−‐Ionen oder Ni‐Atome besitzen. 1 ist ein sehr ungewöhnlicher, durch ein einzelnes Metallatom "zentrierter" 12‐Atom‐Cluster, da das innere Atom aus energetischen Gründen klar aus einer zentralen Position ausgelenkt ist. Mittels quantenchemischer Rechnungen konnten die Atomsorten den Atompositionen zugeordnet und relative Stabilitäten möglicher Isomere dieses Clustertyps bestimmt werden. Die Studien zeigen, dass die Gesamtvalenzelektronenzahl der Cluster – die bei ternären intermetalloiden Clusteranionen besonders leicht variiert – ihre Struktur determiniert. Erste 119Sn‐NMR‐Studien in Lösung, die von quantenchemischen Rechnungen flankiert wurden, illustrieren die Komplexität solcher Systeme bezüglich der Sn:Sb‐Verteilung. Ein unsymmetrisch besetzter 12‐Atom‐Käfig – in dieser Form liegt der neue ternäre intermetalloide Cluster [Co@Sn6Sb6]3− vor (siehe Abbildung). Gemäß DFT‐Rechnungen entspricht die beobachtete Struktur dem globalen Minimum der genannten Zusammensetzung. Neben diesem Cluster wurde [Co2@Sn5Sb7]3−, eine verwandte Spezies mit zwei interstitiellen Co‐Atomen, als Minoritätskomponente in der Kristallstruktur identifiziert, was ESI‐Massenspektren einer entsprechenden Lösung bestätigen. [ABSTRACT FROM AUTHOR]

We report on the asymmetric occupation of a 12‐vertex cluster centered by a single metal atom. Three salts of related intermetalloid cluster anions, [Co@Sn6Sb6]3− (1), [Co2@Sn5Sb7]3− (2), and [Ni2@Sn7Sb5]3− (3) were synthesized, which have pseudo‐C4v‐symmetric or pseudo‐D4h‐symmetric 12‐vertex Sn/Sb shells and interstitial Co− ions or Ni atoms. Anion 1 is a very unusual single‐metal‐"centered" 12‐atom cluster, with the inner atom being clearly offset from the cluster center for energetic reasons. Quantum chemistry served to assign atom types to the atomic positions and relative stabilities of this cluster type. The studies indicate that the structures are strictly controlled by the total valence electron count—which is particularly variable in ternary intermetalloid cluster anions. Preliminary 119Sn NMR studies in solution, supported by quantum‐chemical calculations of the shifts, illustrate the complexity regarding Sn:Sb distributions of such ternary systems. Asymmetric occupation of a 12‐vertex cage was found in the new ternary intermetalloid cluster [Co@Sn6Sb6]3− (see picture). According to DFT calculations, the observed structure represents the global minimum for the given composition. Beside this cluster, a related one was identified with two interstitial cobalt atoms, [Co2@Sn5Sb7]3−, as a minor component in the crystal structure, which was also confirmed by ESI mass spectrometry of a corresponding solution. [ABSTRACT FROM AUTHOR]

Der unzweifelhafte Nachweis des schwer zu fassenden [HSi9]3−‐Anions gelang in flüssigem Ammoniak mithilfe verschiedenster 29Si‐ und 1H‐NMR‐Experimente, inklusive Chemical‐Exchange‐Saturation‐Transfer(CEST)‐Experimente. Charakteristische Multiplett‐Aufspaltungen sowohl bei den 29Si‐ als auch bei den 1H‐Signalen zusammen mit den CEST‐Messungen und eine teilweise reduzierte 1H,29Si‐Kopplungskonstante zeigen eine äußerst dynamische Si8‐Teilstruktur sowie eine Si‐H‐Einheit mit einem langsamen Protonen‐Hopping. Rechnungen belegen sowohl eine Umstrukturierung von Si8 in der ps‐Zeitskala über schwache Schwingungsmoden als auch das Protonen‐Hopping. Zusätzlich wurde in einer Einkristallstrukturanalyse von (K(DB[18]Krone‐6))(K([2.2.2]Krypt))2[HSi9]⋅8.5 NH3 das H‐Atom eindeutig an einer Ecke der quadratischen Grundfläche des Clusters lokalisiert, der die Gestalt eines einfach überdachten quadratischen Antiprismas hat. Insgesamt liefern experimentelle Studien und theoretische Betrachtungen bisher beispiellose Details sowohl zur Struktur als auch zum dynamischen Verhalten der Clusteranionen, die bisher eher für starr gehalten worden sind. Es fluktuiert! Charakteristische Multiplettmuster von 29Si‐ und 1H‐NMR‐Signalen und CEST‐Untersuchungen zeigen das hochdynamische Verhalten von [HSi9]3− in Lösung. Rechnungen belegen, dass ein hochdynamischer Si8‐Clusteranteil neben einer Si‐H‐Einheit vorliegt. In einer Einkristallstrukturanalyse kann das Wasserstoffatom an der quadratischen Basisfläche des Clusters nachgewiesen werden. [ABSTRACT FROM AUTHOR]

Abstract: We report on the first unambiguous detection of the elusive [HSi9]3− anion in solutions of liquid ammonia by various 29Si and 1H NMR experiments including chemical exchange saturation transfer (CEST). The characteristic multiplicity patterns of both the 29Si and 1H resonances together with CEST and a partially reduced 1H,29Si coupling constant indicate the presence of a highly dynamic Si8 entity and a Si−H moiety with slow proton hopping. Theoretical calculations corroborate both reorganization of Si8 on the picosecond timescale via low vibrational modes and proton hopping. In addition, in a single‐crystal X‐ray study of (K(DB[18]crown‐6))(K([2.2.2]crypt))2[HSi9]⋅8.5 NH3, the H atom was unequivocally localized at one vertex of the basal square of the monocapped square‐antiprismatic cluster. Thus experimental studies and theoretical considerations provide unprecedented insight into both the structure and the dynamic behavior of these cluster anions, which hitherto had been considered to be rigid. [ABSTRACT FROM AUTHOR]

The cyclo-P4 complexes [CpRTa(CO)2(η4-P4)] (CpR: Cp′′=1,3-C5H3tBu2, Cp′′′=1,2,4-C5H2tBu3) turned out to be predestined for the formation of hollow spherical supramolecules with non-classical fullerene-like topology. The resulting assemblies constructed with CuX (X=Cl, Br) showed a highly symmetric 32-vertex core of solely four- and six-membered rings. In some supramolecules, the inner cavity was occupied by an additional CuX unit. On the other hand, using CuI, two different supramolecules with either peanut- or pear-like shapes and outer diameters in the range of 2-2.5 nm were isolated. Furthermore, the spherical supramolecules containing Cp′′′ ligands at tantalum are soluble in CH2Cl2. NMR spectroscopic investigations in solution revealed the formation of isomeric supramolecules owing to the steric hindrance caused by the third tBu group on the Cp′′′ ligand. In addition, a 2D coordination polymer was obtained and structurally characterized. [ABSTRACT FROM AUTHOR]

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The reaction of [CpBnFe(η5-P5)] ( 1) (CpBn=η5-C5(CH2Ph)5) with CuI selectively yields a novel spherical supramolecule (CH2Cl2)3.4@[(CpBnFeP5)12{CuI}54(MeCN)1.46] ( 2) showing a linkage of the scaffold atoms which is beyond the Fullerene topology. Its extended CuI framework reveals an outer diameter of 3.7 nm-a size that has not been reached before using five-fold symmetric building blocks. Furthermore, 2 shows a remarkable solubility in CH2Cl2, and NMR spectroscopy reveals that the scaffold of the supramolecule remains intact in solution. In addition, a novel 2D polymer [{CpBnFe(η5-P5)}2{Cu6(μ-I)2(μ3-I)4}] n ( 3) with an uncommon structural motif was isolated. Its formation can be avoided by using a large excess of CuI in the reaction with 1. [ABSTRACT FROM AUTHOR]

Copyright of Angewandte Chemie is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)