Andreas Schnepf

The synthesis and structural characterization of four structurally similar metalloid silver clusters with 128, 132, 146 and 160 silver atoms give insight into the mechanism of the formation of faceted silver nanoparticles on an atomic scale.

Recently we could demonstrate that the reaction of the bissilylated metalloid cluster K₂[Ge₉(Hyp)₂] (Hyp = Si(SiMe₃)₃) with phosphine-stabilized silver chlorides gives the intermetalloid cluster Ag₁₂[Ge₉(Hyp)₂]₆, featuring a silver core of twelve silver atoms surrounded by six [Ge₉(Hyp)₂] units. Thereby, the silver atoms in the core appear to have an oxidation state of less than +I, indicating that a redox chemistry also takes place during the formation. We now present a possible precursor or intermediate to the intermetalloid cluster in this reaction system with the formula Ag₈(PEt₃)₆[Ge₉(Hyp)₂]₄. In this compound only four [Ge₉(Hyp)₂] units are arranged in a plane and connected via eight silver atoms. This compound seems to contain only silver cations, shedding further light on the complex solution and coordination chemistry of [Ge₉(Hyp)₂]²⁻ with transition metal cations. As the intermetalloid cluster Ag₁₂[Ge₉(Hyp)₂]₆ can be obtained from dissolved crystals of Ag₈(PEt₃)₆[Ge₉(Hyp)₂]₄, this indicated that the Ag₈ compound might be an intermediate (kinetic product) on the way to the Ag₁₂ compound (thermodynamic product).

The reaction of dppb(AuCl) ₂ and InCl gives the [Au ₄ (dppb) ₃ ] ²⁺ cluster where the four gold atoms are arranged in a deltoid. This contrasts all known [Au ₄ ] ²⁺ clusters which exclusively form tetrahedral structures. Single crystals of the title compound luminesce with a high quantum yield in the near infrared at room temperature. The excitation wavelength dictates the emission wavelength which ranges from 680 to 918 nm at 77 K. Comprehensive studies of the excitation‐dependent emission and luminescence lifetimes in both polycrystalline and single‐crystalline samples provide a unique and detailed optical profile of the cluster, uncovering distinct photophysical behavior central to its emissive properties.

The continued miniaturization of microelectronic systems requires new strategies for fabricating microelectronic materials beyond conventional lithography and metal evaporation. Metalloid nanoclusters offer promising alternatives for printing and patterning conductive and semiconductive elements. Here, we report on the synthesis, structural characterization, and first application of the soluble metalloid germanium cluster Ge₁₄Br₈(PⁿPr₃)₄, obtained via controlled disproportionation of a metastable GeBr solution. Substitution of the phosphine ligands markedly enhances the solubility in organic solvents, enabling comprehensive spectroscopic characterization via nuclear magnetic resonance (NMR), ultraviolet-visible (UV-vis), and mass spectrometry. Furthermore, the cluster demonstrates a high Ge content of 45 wt %, rendering it a possible precursor for laser-induced writing of elemental germanium under inert conditions. To demonstrate its potential, we fabricate deliberately designed patterns of Ge microstructures and assess their semiconducting behavior. This work establishes the first example of direct laser writing of germanium from a soluble metalloid cluster precursor, opening new pathways for additive microfabrication in semiconductor technology.

The reaction of dppm(AuCl) ₂ with LiTePh affords the water and air stable gold-tellurolate cluster [Au ₈ (TePh) ₄ dppm ₂ (Ph ₂ PCHPPh ₂ ) ₂ ]Cl ₂ , which shows a bright red luminescence with excellent quantum yield.

Although a large number of copper hydride complexes and clusters have been reported, phosphine-stabilized copper hydrides remain comparatively rare. This is particularly noteworthy given the continuing interest in Stryker’s reagent [HCu(PPh₃)]₆ due to its use as a hydrogenation reagent. In this work, we report on the synthesis and full characterization of a novel copper hydride cluster, [Cu₁₄H₁₂(P^tBu₃)₆Cl₂]. The structure of this copper hydride was determined via SC-XRD. In addition, the reactivity of the hydrides and their position were investigated via a convolutional neural network, quantum chemical calculations, and NMR, and they are compared to the well-known, smaller Stryker’s reagent.

We present the synthesis and characterization of the novel intermetalloid cluster compound Ag ₁₂ [Ge ₉ (Hyp) ₂ ] ₆ , exhibiting a silver core surrounded by bis‐silylated Ge ₉ ‐clusters. The new intermetalloid cluster has an Ag ₁₂ metal cluster core with silver atoms in different oxidation states. To the silver core six [Ge ₉ (Hyp) ₂ ] units are coordinated, acting as ligands. The [Ge ₉ (Hyp) ₂ ] units are arranged octahedrally around the Ag ₁₂ core, leading to a variety of Ag‐Ge bonds and contacts. The cluster is a first example of an intermetalloid cluster, exhibiting a silver core, shielded by [Ge ₉ (Hyp) ₂ ] units.

We present the synthesis and characterization of the novel intermetalloid cluster compound Ag ₁₂ [Ge ₉ (Hyp) ₂ ] ₆ , exhibiting a silver core surrounded by bis‐silylated Ge ₉ ‐clusters. The new intermetalloid cluster has an Ag ₁₂ metal cluster core with silver atoms in different oxidation states. To the silver core six [Ge ₉ (Hyp) ₂ ] units are coordinated, acting as ligands. The [Ge ₉ (Hyp) ₂ ] units are arranged octahedrally around the Ag ₁₂ core, leading to a variety of Ag‐Ge bonds and contacts. The cluster is a first example of an intermetalloid cluster, exhibiting a silver core, shielded by [Ge ₉ (Hyp) ₂ ] units.

We demonstrate high-speed photodetectors based on bi-, few- and multilayered WSe2 flakes fabricated by high-resolution direct laser writing of Au top contacts from atomically precise gold nanoclusters as an alternative to conventional photolithography. Time-resolved steady-state and transient photoresponse measurements reveal remarkable switching speeds exhibiting response times down to 7 ns and electrical bandwidths up to 250 MHz. Key performance metrics, including responsivity, detectivity and external quantum yield are studied with respect to the applied irradiance and excitation wavelength. By demonstrating high-speed switching in thin-layered WSe2-based devices, this work highlights the potential of laser-written metal-semiconductor interfaces for high-speed optoelectronic applications of 2D materials.