{Sn₉[Si(SiMe₃)₃]₂}^2‑: A Metalloid Tin Cluster Compound With a Sn₉ Core of Oxidation State Zero

The disproportionation reaction of the subvalent metastable halide SnCl proved to be a powerful synthetic method for the synthesis of metalloid cluster compounds of tin. Now we present the synthesis and structural characterization of the anionic metalloid cluster compound [Sn₉[Si­(SiMe₃)₃]₂]^2‑ <b>3</b> where the oxidation state of the tin atoms is zero. Quantum chemical calculations as well as Mössbauer spectroscopic investigations show that three different kinds of tin atoms are present within the cluster core. Compound <b>3</b> is highly reactive as shown by NMR investigations, thus being a good starting material for further ongoing research on the reactivity of such partly shielded metalloid cluster compounds

{Sn₉[Si(SiMe₃)₃]₂}^2‑: A Metalloid Tin Cluster Compound With a Sn₉ Core of Oxidation State Zero

The disproportionation reaction of the subvalent metastable halide SnCl proved to be a powerful synthetic method for the synthesis of metalloid cluster compounds of tin. Now we present the synthesis and structural characterization of the anionic metalloid cluster compound [Sn₉[Si­(SiMe₃)₃]₂]^2‑ <b>3</b> where the oxidation state of the tin atoms is zero. Quantum chemical calculations as well as Mössbauer spectroscopic investigations show that three different kinds of tin atoms are present within the cluster core. Compound <b>3</b> is highly reactive as shown by NMR investigations, thus being a good starting material for further ongoing research on the reactivity of such partly shielded metalloid cluster compounds

{Sn₉[Si(SiMe₃)₃]₂}^2‑: A Metalloid Tin Cluster Compound With a Sn₉ Core of Oxidation State Zero

The disproportionation reaction of the subvalent metastable halide SnCl proved to be a powerful synthetic method for the synthesis of metalloid cluster compounds of tin. Now we present the synthesis and structural characterization of the anionic metalloid cluster compound [Sn₉[Si­(SiMe₃)₃]₂]^2‑ <b>3</b> where the oxidation state of the tin atoms is zero. Quantum chemical calculations as well as Mössbauer spectroscopic investigations show that three different kinds of tin atoms are present within the cluster core. Compound <b>3</b> is highly reactive as shown by NMR investigations, thus being a good starting material for further ongoing research on the reactivity of such partly shielded metalloid cluster compounds

Structure and Bonding of Bi₄Ir: A Difficult-to-Access Bismuth Iridide with a Unique Framework Structure

Crystals of Bi₄Ir, a new intermetallic compound, were obtained by the reaction of an iridium-containing intermetallic precursor with liquid bismuth. X-ray diffraction on a single crystal revealed a rhombohedral structure [<i>R</i>3̅<i>m</i>, <i>a</i> = 2656.7(2) pm, and <i>c</i> = 701.6(4) pm]. Bi₄Ir is not isostructural to Bi₄Rh but combines motifs of the metastable superconductor Bi₁₄Rh₃ with those found in the weak topological insulator Bi₁₄Rh₃I₉. The two crystallographically independent iridium sites in Bi₄Ir have square-prismatic and skewed-square-antiprismatic bismuth coordination with Bi–Ir distances of 283–287 pm. By sharing common edges, the two types of [IrBi₈] units constitute a complex three-dimensional network of rings and helices. The bonding in the heterometallic framework is dominated by pairwise Bi–Ir interactions. In addition, three-center bonds are found in the bismuth triangles formed by adjacent [IrBi₈] polyhedra. Density functional theory based band-structure calculations suggest metallic properties

Synthesis and Crystal Structure Determination of Ag₉FeS_4.1Te_1.9, the First Example of an Iron Containing Argyrodite

Ag₉FeS_4.1Te_1.9 was prepared by solid state synthesis from stoichiometric amounts of the elements at 873 K. The compound forms gray crystals which are stable against air and moisture. The crystal structure was determined by X-ray diffraction from selected single crystals. Ag₉FeS_4.1Te_1.9 crystallizes in the space group <i>F</i>4̅3<i>m</i>, <i>a</i> = 11.0415(7) Å, <i>V</i> = 1346.1(1) ų, and <i>Z</i> = 4 (powder data at 293 K). The compound shows a reversible phase transition upon cooling to the space group <i>P</i>2₁3, <i>a</i> = 11.0213(1) Å, <i>V</i> = 1338.75(2) ų, and <i>Z</i> = 4 (single crystal data at 200 K). The title compound is the first example of an iron containing argyrodite-type material with Fe³⁺ located in tetrahedral sites. Silver atoms are disordered at room temperature which was taken into account by nonharmonic refinement of the silver positions. The refinement converged to <i>R</i>₁ = 3.51% and <i>wR</i>₂ = 10.66% for the room temperature measurement and to <i>R</i>₁ = 1.55% and <i>wR</i>₂= 5.23% for the 200 K data set (all data). Impedance measurements were performed in the temperature range from 323 to 473 K. Ionic conductivity values are 1.81 × 10^–2 S cm^–1 at 323 K and 1.41 × 10^–1 S cm^–1 at 468 K. The activation energy is 0.19 eV from 323 to 423 K and 0.06 eV from 393 to 473 K. DTA measurements reveal congruent melting at 907 K. A phase transition temperature of 232 K with an enthalpy of 7.9 kJ/mol was determined by DSC measurements. ⁵⁷Fe Mössbauer spectra show one signal at 298 K and a doublet at 78 K, indicating Fe³⁺ and structural distortions upon cooling the samples. Hyperfine field splitting of iron is observed at 5 K. Measurements of the molar susceptibility revealed that the compound is paramagnetic down to a Néel temperature of <i>T</i>_N = 22.1(5) K. Antiferromagnetic ordering is observed at lower temperatures

Ferrocenyl-Functionalized Sn/Se and Sn/Te Complexes: Synthesis, Reactivity, Optical, and Electronic Properties

An adamantane-shaped, ferrocenyl-substituted tin selenide complex, [(FcSn)₄Se₆] (<b>1</b>; Fc = ferrocenyl), and a ferrocenyl-substituted tin telluride five-membered ring, [(Fc₂Sn)₃Te₂] (<b>2</b>), were obtained upon treatment of FcSnCl₃ with K₂E (E = Se, Te). Complex <b>1</b> further reacts with Na₂S·9H₂O and [Cu­(PPh₃)₃Cl] to form a ternary complex, [(CuPPh₃)₆(S/Se)₆(SnFc)₂] (<b>3</b>). We discuss structures, optical and electrochemical properties as well as Mössbauer spectra

Polynitroxides from Alkoxyamine Monomers: Structural and Kinetic Investigations by Solid State NMR

A novel synthetic route toward poly­(4-methacryloyloxy-2,2,6,6-tetramethylpiperidine-<i>N</i>-oxyl) (PTMA) is described. The polymerization of alkoxyamine-based monomers by atom transfer radical polymerization (ATRP) was investigated, as the polyalkoxyamine serves as the precursor for PTMA. The polydispersity indices (PDIs) and the kinetic data of the polymerization indicate a controlled reaction. The oxidative C–O bond cleavages of the polyalkoxyamine lead to PTMA. This transformation occurs with excellent yields, and it is possible to transfer the narrow PDIs of the prepolymer to PTMA. The material is characterized in detail using cyclic voltammetry in solution and magnetic susceptibility measurements as well as multinuclear solid state NMR and EPR spectroscopies. The conversion of the precursor polymer to the polynitroxide can be conveniently monitored by ¹H and ¹⁹F magic-angle spinning (MAS) as well as ¹³C­{¹H} cross-polarization (CP)-MAS NMR. In addition, the intermolecular interaction of the nitroxide side chain units in the polymer at high conversion can be detected and monitored by the observation of pronounced low-frequency shifts

Ultraviolet Upconversion Luminescence in a Highly Transparent Triply-Doped Gd³⁺–Tm³⁺–Yb³⁺ Fluoride–Phosphate Glasses

We report near-infrared to ultraviolet (UV) upconversion emissions in triply-doped Gd³⁺–Tm³⁺–Yb³⁺ fluoride–phosphate glasses. Emission at 310 nm, originated from the Gd³⁺:⁶P_7/2 → ⁸S_7/2 transition, was observed for the first time in glasses. The high-purity glasses prepared exhibit extended transparency in the UV down to 200–250 nm. The mixed fluoride–phosphate environment of the rare-earth ions was characterized by means of NMR techniques using scandium as a diamagnetic mimic for the luminescent species, for which the ligand distribution was quantified by ⁴⁵Sc­{³¹P} rotational echo double-resonance NMR. Both the intensity of the Gd³⁺ emission as well as those of the UV emissions at 290, 347, and 363 nm increase with increasing ratio of fluoride to phosphate ligands coordinating to the rare-earth ion

Solid Solution Quantum Dots with Tunable Dual or Ultrabroadband Emission for LEDs

Quantum dots that efficiently emit white light directly or feature a “candle-like” orange photoluminescence with a high Stokes shift are presented. The key to obtaining these unique emission properties is through controlled annealing of the core Cu-In-Ga-S quantum dots in the presence of zinc ions, thus forming Zn-Cu-In-Ga-S solid solutions with different distributions of the substitution and dopant elements. The as-obtained nanocrystals feature excellent quantum yields of up to 82% with limited or even eliminated reabsorption and a color rendering index of bare particles of up to 88, enabling the production of high-quality white LEDs using a single color converter layer. Furthermore, the color properties can be tuned by changing the experimental conditions as well as by varying the excitation wavelength. The multicomponent luminescence mechanism is discussed in detail based on similar literature reports. White LEDs with unparalleled color quality and competitive luminous efficacies are presented herein

Doped Semimetal Clusters: Ternary, Intermetalloid Anions [Ln@Sn₇Bi₇]^4– and [Ln@Sn₄Bi₉]^4– (Ln = La, Ce) with Adjustable Magnetic Properties

Two K([2.2.2]­crypt) salts of lanthanide-doped semimetal clusters were prepared, both of which contain at the same time two types of ternary intermetalloid anions, [Ln@Sn₇Bi₇]^4– and [Ln@Sn₄Bi₉]^4–, in 0.70:0.30 (Ln = La) or 0.39:0.61 (Ln = Ce) ratios. The cluster shells represent nondeltahedral, fullerane-type arrangements of 14 or 13 main group metal atoms that embed the Ln³⁺ cations. The assignment of formal +III oxidation states for the Ln sites was confirmed by means of magnetic measurements that reveal a diamagnetic La­(III) compound and a paramagnetic Ce­(III) analogue. Whereas the cluster anions with a 14-atomic main-group metal cage represent the second examples in addition to a related Eu­(II) cluster published just recently, the 13-atomic cages exhibit a yet unprecedented enneahedral topology. In contrast to the larger cages, which accord to the Zintl–Klemm–Busmann electron number–structure correlation, the smaller clusters require a more profound interpretation of the bonding situation. Quantum chemical investigations served to shed light on these unusual complexes and showed significant narrowing of the HOMO–LUMO gap upon incorporation of Ce³⁺ within the semimetal cages