Elusive Zintl Ions [μ-HSi ] and [Si ] in Liquid Ammonia: Protonation States, Sites, and Bonding Situation Evaluated by NMR and Theory.

The existence of [μ-HSi ] in liquid ammonia solutions is confirmed by H and Si NMR experiments. Both NMR and quantum chemical calculations reveal that the H atom bridges two Si atoms of the [Si ] 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-HSi ] , protonation is driven by a high charge density and an increase of electron delocalization compared to [Si ] .

[Co@Sn Sb ] : An Off-Center Endohedral 12-Vertex Cluster.

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@Sn Sb ] (1), [Co @Sn Sb ] (2), and [Ni @Sn Sb ] (3) were synthesized, which have pseudo-C -symmetric or pseudo-D -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.

The Structure of [HSi ] in the Solid State and Its Unexpected Highly Dynamic Behavior in Solution.

We report on the first unambiguous detection of the elusive [HSi ] anion in solutions of liquid ammonia by various Si and H NMR experiments including chemical exchange saturation transfer (CEST). The characteristic multiplicity patterns of both the Si and H resonances together with CEST and a partially reduced H, Si coupling constant indicate the presence of a highly dynamic Si entity and a Si-H moiety with slow proton hopping. Theoretical calculations corroborate both reorganization of Si on the picosecond timescale via low vibrational modes and proton hopping.

PPhCl in aqueous solution - the aggregation behavior of an antagonistic salt.

The initial definition of hydrotropy by Neuberg in 1916 describes a hydrotrope as a molecule which enhances the solubilization of hydrophobic substances in water. Sodium dodecyl sulfate (SDS) and sodium xylene sulfonate (SXS) are typical representatives fulfilling this old definition. They are either surfactants with a critical micellar concentration (CMC) or hydrotropes in the current sense of the term, showing a minimum hydrotrope concentration (MHC), respectively.

cyclo-P Building Blocks: Achieving Non-Classical Fullerene Topology and Beyond.

The cyclo-P complexes [Cp Ta(CO) (η -P )] (Cp : Cp''=1,3-C H tBu , Cp'''=1,2,4-C H tBu ) 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.

A nano-sized supramolecule beyond the fullerene topology.

The reaction of [Cp(Bn) Fe(η(5) -P5 )] (1) (Cp(Bn) =η(5) -C5 (CH2 Ph)5 ) with CuI selectively yields a novel spherical supramolecule (CH2 Cl2 )3.4 @[(Cp(Bn) FeP5 )12 {CuI}54 (MeCN)1.46 ] (2) showing a linkage of the scaffold atoms which is beyond the Fullerene topology.

Canted antiferromagnetic phase in a double quantum well in a tilted quantizing magnetic field.

We investigate the double-layer electron system in a parabolic quantum well at filling factor nu=2 in a tilted magnetic field using capacitance spectroscopy. The competition between two ground states is found at the Zeeman splitting appreciably smaller than the symmetric-antisymmetric splitting. Although at the transition point the system breaks up into domains of the two competing states, the activation energy turns out to be finite, signaling the occurrence of a new insulator-insulator quantum phase transition.