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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. Long ago Zintlsized and now analyzed: 29Si and 1H NMR experiments confirm the existence of Zintl ions [μ‐HSi4]3− and [Si5]2− in liquid ammonia. For [μ‐HSi4]3−, NMR and theoretical calculations reveal a bridging hydrogen atom forming a 3c‐2e‐bond. Additionally, [Si5]2−, only known from solvate crystal structures so far, was characterized by 29Si NMR. Here, NBO analysis indicates the formation of three localized 3c‐2e‐bonds. [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]

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]