SrIr9In18 – A Structurally Complex Intermetallic Compound with Sr@Ir4In12, Ir@In8 and Ir@In9 Building Units

Single crystals of SrIr₉In₁₈ were obtained by induction melting of the elements in a glassy carbon crucible followed by annealing at 1070 K. SrIr₉In₁₈ was structurally characterized by X-ray powder and single crystal diffraction: P4 m2, a = 811.21(5), c = 854.49(5) pm, wR₂ = 0.0511, 1223 F² values, and 46 variables. The structure is of a new type. The basic building units are Ir@In₈ (distorted square-prismatic, square anti-prismatic and bicapped trigonal prismatic coordination) and Ir@In₉ (distorted trigonal prismatic coordination) polyhedra, which condense to a three-dimensional network, which leaves large cavities for the strontium cations, which are coordinated to four iridium and twelve indium atoms. The [Ir₉In₁₈]^2– polyanionic network is stabilized through Ir–In (267–290 pm) and In–In (302–354 pm) bonding.     

SrIrIn6 – An Intergrowth of SrIrIn4 with Indium Slabs

The indium-rich intermetallic compound SrIrIn₆ was synthesized from the elements in a sealed tantalum ampoule at 1173 K, followed by slow cooling for crystal growth. SrIrIn₆ crystallizes with a new structure type which was characterized by X-ray powder and single crystal diffraction: Pmma, a = 852.34(2), b = 434.54(5), c = 1059.18(6) pm, wR₂ = 0.0178, 884 F² values, and 32 variables. The SrIrIn₆ structure shows two basic building units: (i) Ir@In₉ tricapped trigonal prisms (261–292 pm Ir–In) and (ii) distorted bcc In@In₈ cubes (301 to 329 pm In–In). The strontium cations fill cages within the complex three-dimensional [IrIn₆] network and have coordination number 13 (Sr@In₁₃) in form of a tricapped pentagonal prism. The SrIrIn₆ structure can be described as a simple intergrowth variant of SrIrIn₄ (LaCoAl₄ type) with indium slabs. The crystal chemical similarities with the structures of SrIrIn₄, SrIr₂In₈ and Eu₃Ir₂In₁₅ are discussed.     

Eu(O2C-C≡C-CO2): An EuII Containing Anhydrous Coordination Polymer with High Stability and Negative Thermal Expansion

Anhydrous Eu^II–acetylenedicarboxylate (EuADC; ADC²⁻ = ⁻O₂C-C≡C-CO₂⁻) was synthesized by reaction of EuBr₂ with K₂ADC or H₂ADC in degassed water under oxygen-free conditions. EuADC crystallizes in the SrADC type structure (I4₁/amd, Z=4) forming a 3D coordination polymer with a diamond-like arrangement of Eu²⁺ nodes (msw topology including the connecting ADC²⁻ linkers). Deep orange coloured EuADC is stable in air and starts decomposing upon heating in an argon atmosphere only at 440 °C. Measurements of the magnetic susceptibilities (μ_eff=7.76 μ_B) and ¹⁵¹Eu Mössbauer spectra (δ=−13.25 mm s⁻¹ at 78 K) confirm the existence of Eu²⁺ cations. Diffuse reflectance spectra indicate a direct optical band gap of E_g=2.64 eV (470 nm), which is in accordance with the orange colour of the material. Surprisingly, EuADC does not show any photoluminescence under irradiation with UV light of different wavelengths. Similar to SrADC, EuADC exhibits a negative thermal volume expansion below room temperature with a volume expansion coefficient α_V=−9.4(12)×10⁻⁶ K⁻¹.     

A Comprehensive Study on Tetraaryltetrabenzoporphyrins

Tetraaryltetrabenzoporphyrins (TATBPs) show, due to their optoelectronic properties, rising potential as dyes in various fields of physical and biomedical sciences. However, unlike in the case of porphyrins, the potential structural diversity of TATBPs has been explored only to little extent, owed mainly to synthetic hurdles. Herein, we prepared a comprehensive library of 30 TATBPs and investigated their fundamental properties. We elucidated structural properties by X-ray crystallography and found explanations for physical properties such as solubility. Fundamental electronic aspects were studied by optical spectroscopy as well as by electrochemistry and brought in context to the stability of the molecules. Finally, we were able to develop a universal synthetic protocol, utilizing a readily established isoindole synthon, which gives TATBPs in high yields, regardless of the nature of the used arylaldehyde and without meticulous chromatographic purifications steps. This work serves as point of orientation for scientists, that aim to utilize these molecules in materials, nanotechnological, and biomedical applications.     

Structural Peculiarities and Thermoelectric Study of Iron Indium Thiospinel

The homogeneity range of ternary iron indium thiospinel at 873 K was investigated. A detailed study was focused on two distinct series (y=z): 1) a previously reported charge-balanced (In_0.67+0.33y□_0.33−0.33y)_tetr[In_2−zFe_z]_octS₄ (A1-series; □ stands for vacancy; the abbreviations “tetr” and “oct” indicate atoms occupying tetrahedral 8a and octahedral 16d sites, respectively) and 2) a new charge-unbalanced (In_0.67+y□_0.33−y)_tetr[In_2−zFe_z]_octS₄ (A2-series). Fe atoms were confirmed to exclusively occupy an octahedral position in both series. An unusual reduction of the unit cell parameter with increasing Fe content is explained by differences in the ionic radii between Fe and In, as well as by an additional electrostatic attraction originating from charge imbalance (latter only in A2-series). The studied compound is an n-type semiconductor, and its charge carrier concentration increases or decreases for larger Fe content within the A1- and A2-series, respectively. The thermal conductivity κ_tot is significantly reduced upon increasing vacancy concentration, whereas the change of power factor is insufficient to drastically improve the thermoelectric figure of merit.     

The Quasi‐Binary Acetonitriletriide Sr3[C2N]2

The first quasi‐binary acetonitriletriide Sr₃[C₂N]₂ has been synthesised and characterised. The nearly colourless crystals were obtained from the reaction of Sr metal, graphite, and elemental N₂, generated by decomposition of Sr(N₃)₂, in a sealed Ni ampoule with the aid of an alkali metal flux. The structure of this compound was analysed via single‐crystal X‐ray diffraction and the identity of the [C₂N]^3? anion was confirmed by Raman spectroscopy and further investigated by quantum‐chemical methods. Computed interatomic distances within the [C₂N]^3? anion strikingly match the obtained experimental data.     

Synthesis of Oligomeric Axially Bridged Ruthenium Phthalocyanines and 2,3-Naphthalocyanines

Bridged 2,3-naphthalocyaninatoruthenium oligomers {[MacRu(L)] _n } were synthesized and characterized using solid-state methods. For comparison, soluble t-butyl substituted phthalocyaninatoruthenium oligomers were prepared and their chain length examined by ¹H NMR spectroscopy. The powder conductivities of all bridged compounds ([MacRu(L)] _n ) were measured and the dependence of the conductivities on the bridging ligands is discussed.