Halide-Ion Diadducts of Perhalogenated Cyclopenta- and Cyclohexasilanes

Confined Lewis Pairs: Investigation of the X- →Si20 Interaction in Halogen-Encapsulating Silafulleranes

A joint theoretical and experimental study on 32 endohedral silafullerane derivatives [X@Si20 Y20 ]- (X=F-I; Y=F-I, H, Me, Et) andT h ${T_h }$ -[Cl@Si20 H12 Y8 ]- (Y=F-I) is presented. First, we evaluated the structure-determining template effect of Cl- in a systematic series of concave silapolyquinane model systems. Second, we investigated the X- →Si20 interaction energy (E int ${E_{{\rm{int}}} }$ ) as a function of X- and Y and found the largestE int ${E_{{\rm{int}}} }$ values for electron-withdrawing exohedral substituents Y. Given that X- ions can be considered as Lewis bases and empty Si20 Y20 clusters as Lewis acids, we classify our inseparable host-guest complexes [X@Si20 Y20 ]- as "confined Lewis pairs". Third, 35 Cl NMR spectroscopy proved to be highly diagnostic for an experimental assessment of the Cl- →Si20 interaction as the paramagnetic shielding and, in turn, δ ${\delta }$ (35 Cl) of the endohedral Cl- ion correlate inversely withE int ${E_{{\rm{int}}} }$ . Finally, we disclose the synthesis of [PPN][Cl@Si20 Y20 ] (Y=Me, Et, Br) and provide a thorough characterization of these new silafulleranes.

Dope it with germanium: selective access to functionalized Si5Ge heterocycles

The Cl^- diadduct [nBu₄N]₂[A·2Cl] of the mixed cyclohexatetrelane (SiCl₂)₅(GeMe₂), A, is accessible from Me₂GeCl₂, 6 eq. Si₂Cl₆, and 2 eq. [nBu₄N]Cl in one step (96%). Free, tenfold functionalized A can be released from the primary product by decomplexation with AlCl₃ (78%). Insight into the assembly mechanism of [nBu₄N]₂[A·2Cl] and the reactivity of A is provided.

Tetrel Bonding in Anion Recognition: A First Principles Investigation

Twenty-five molecule-anion complex systems [I₄Tt···X^-] (Tt = C, Si, Ge, Sn and Pb; X = F, Cl, Br, I and At) were examined using density functional theory (ωB97X-D) and ab initio (MP2 and CCSD) methods to demonstrate the ability of the tetrel atoms in molecular entities, I₄Tt, to recognize the halide anions when in close proximity. The tetrel bond strength for the [I₄C···X^-] series and [I₄Tt···X^-] (Tt = Si, Sn; X = I, At), was weak-to-moderate, whereas that in the remaining 16 complexes was dative tetrel bond type with very large interaction energies and short Tt···X close contact distances. The basis set superposition error corrected interaction energies calculated with the highest-level theory applied, [CCSD(T)/def2-TZVPPD], ranged from -3.0 to -112.2 kcal mol^-1. The significant variation in interaction energies was realized as a result of different levels of tetrel bonding environment between the interacting partners at the equilibrium geometries of the complex systems. Although the ωB97X-D computed intermolecular geometries and interaction energies of a majority of the [I₄Tt···X^-] complexes were close to those predicted by the highest level of theory, the MP2 results were shown to be misleading for some of these systems. To provide insight into the nature of the intermolecular chemical bonding environment in the 25 molecule-anion complexes investigated, we discussed the charge-density-based topological and isosurface features that emanated from the application of the quantum theory of atoms in molecules and independent gradient model approaches, respectively.

Selective One-Pot Syntheses of Mixed Silicon-Germanium Heteroadamantane Clusters

Si x Ge y alloys are emerging materials for modern semiconductor technology. Well-defined model systems of the bulk structures aid in understanding their intrinsic characteristics. Three such model clusters have now been realized in the form of the Si x Ge y heteroadamantanes [0] , [1] , and [2] via selective one-pot syntheses starting from Me 2 GeCl 2 , Si 2 Cl 6 , and [nBu 4 N]Cl. Compound [0] contains 6 GeMe 2 and 4 SiSiCl 3 vertices, while one and two of the GeMe 2 groups are replaced by SiCl 2 moieties in compounds [1] and [2] , respectively. Chloride ion-mediated rearrangement quantitatively converts [2] into [1] at room temperature and finally into [0] at 60 °C, which is not only remarkable in view of the rigidity of these cage structures but also sheds light on the assembly mechanism.

Probing the electronic boundaries between trigonal and tetrahedral coordination at beryllium

The influence of the beryllium atom's partial charge on its coordination sphere was investigated experimentally and computationally on NEt₃ adducts to BeCl₂, BeBr₂ and BrI₂.

Breaking Carbon-Chlorine Bonds with the Unconventional Lewis Acid Dodecachlorocyclohexasilane

c-Si₆Cl₁₂ functions as a Lewis acid strong enough to abstract chloride ions from 2 mol of triphenylchloromethane to form the salt [Tr⁺]₂[Si₆Cl₁₄^2-]. This is the first example of a Lewis acid "hole" breaking a carbon-halogen bond.

Tetrel Bonding Interactions in Perchlorinated Cyclopenta- and Cyclohexatetrelanes: A Combined DFT and CSD Study

In this manuscript, we combined DFT calculations (PBE0-D3/def2-TZVP level of theory) and a Cambridge Structural Database (CSD) survey to evaluate the ability of perchlorinated cyclopenta- and cyclohexatetrelanes in establishing tetrel bonding interactions. For this purpose, we used Tr₅Cl₁₀ and Tr₆Cl₁₂ (Tr = Si and Ge) and HCN, HF, OH⁻ and Cl⁻ as electron donor entities. Furthermore, we performed an Atoms in Molecules (AIM) analysis to further describe and characterize the interactions studied herein. A survey of crystal structures in the CSD reveals that close contacts between Si and lone-pair-possessing atoms are quite common and oriented along the extension of the covalent bond formed by the silicon with the halogen atom.