First Observation of an Inverse Ruddlesden‐Popper Series: (A3n+1ONn−1)Bin+1 with A = Sr,Ba and n = 1, 3

Single crystals ((Ba_0.78(1)Sr_0.22)₄O)Bi₂ and ((Ba_0.62(1)Sr_0.38)₁₀N₂O)Bi₄ were successfully prepared from melt beads of Ba, Sr, and Bi in nitrogen atmosphere with oxygen impurities. The phases can be prepared in single phase from the appropriate mixtures of alkaline‐earth metal, bismuth, and bismuth oxide upon heating in pure nitrogen atmosphere. ((Ba_0.78(1)Sr_0.22)₄O)Bi₂ crystallizes in the K₂NiF₄ structure type (space group I4/mmm, No. 139, a = 522.34(5) pm, c = 1844.0(2) pm, Z = 2, R_gt(F) = 0.039) with layers of vertex‐sharing octahedra ((Ba,Sr)_4/2Ba₂O). ((Ba_0.62(1)Sr_0.38)₁₀N₂O)Bi₄ crystallizes as an isotype of Sr₄Ti₃O₁₀ (space group I4/mmm, No. 139, a = 531.3(1) pm, c = 3983.2(4) pm, Z = 2, R_gt(F) = 0.050) containing slabs of three layers of vertex‐sharing octahedra further connected via corners. These compounds are interpreted in terms of members of an inverse Ruddlesden‐Popper series with the general formula n (A₃ON_n?1)Bi · ABi or (A_3n+1ON_n?1)Bi_n+1, respectively, with n = 1, 3. Partial order of the alkaline‐earth metal ions is analyzed.     

Stabilizing the LaCoAl4 Structure through Indium‐Magnesium Substitution in CeRhIn4−xMgx (x = 0.79 and 0.84) – An Indide with Magnesium Centered Indium Cubes

The intermetallic compounds CeRhIn_4?xMg_x (x = 0.79 and 0.84) were prepared from the elements in sealed tantalum ampoules in a high‐frequency furnace. The samples were investigated by X‐ray powder and single crystal diffraction: LaCoAl₄ type, Pmma, a = 829.5(2), b = 433.56(9), c = 740.2(2) pm, wR2 = 0.0458, 651 F² values, 25 variables for CeRhIn_3.21Mg_0.79 and a = 831.44(10), b = 433.49(10), c = 741.04(10) pm, wR2 = 0.0543, 915 F² values, 25 variables for CeRhIn_3.16Mg_0.84. The indium atoms build up two‐dimensional networks perpendicular to the b axis in an AA stacking sequence leaving slightly distorted trigonal, square and pentagonal prismatic voids for the rhodium, magnesium, and cerium atoms. Both square prismatic voids show small magnesium/indium mixing. The shortest interatomic distances occur for the Rh–Mg contacts (257 pm). Together, the rhodium, indium, and magnesium atoms build up three‐dimensional [RhIn_4?xMg_x] networks in which the cerium atoms fill distorted pentagonal channels.     

4‐Chloro­aceto­phenone [1‐(4‐methoxyphenyl)­ethyl­idene]­hydra­zone

The crystal structure of the title mixed azine, C₁₇H₁₇ClN₂O, contains four independent mol­ecules, A–D, and mol­ecule B is disordered. All four mol­ecules have an N—N gauche conformation, with C—N—N—C torsion angles of 136.5 (4), 137.0 (4), ?134.7 (4) and ?134.7 (4)°, respectively. The phenyl rings are also somewhat twisted with respect to the plane defined by C_ipso and the imine bond. On average, the combined effect of these twists results in an angle of 64.7° between the best planes of the two phenyl rings. Arene–arene double T‐contacts are the dominant intermolecular inter­action. The methoxy‐substituted phenyl ring of one azine mol­ecule interacts to form a T‐contact with the methoxy‐substituted phenyl ring of an adjacent mol­ecule and, similarly, two chloro‐substituted phenyl rings of neighboring mol­ecules interact to form another T‐contact. The only exception is for mol­ecule B, for which the disorder leads to the formation of T‐­contacts between methoxy‐ and chloro‐substituted phenyl rings. The prevailing structural motif of T‐contact formation between like‐substituted arene rings results in a highly dipole‐parallel‐aligned crystal structure.     

Bildung eines Amin‐stabilisierten sechsgliedrigen Co2S4‐Heterocyclus: Synthese und Struktur eines ungewöhnlichen zweifach μ‐η1 : η1‐Disulfid‐verbrückten binuklearen Übergangsmetallkomplexes

The Formation of an Amine Stabilized Co₂S₄ Heterocycle: Structure and Synthesis of a Rare Example of a Double μ‐η¹ : η¹ Disulfido Bridged Binuclear Metal Complex Treatment of Co(BPh₄)₂ · 6 MeCN and Co(ClO₄)₂ · 6 MeCN with S₂^2– or S₄^2– in the presence of the macrocyclic tetraaza ligand 1,4,8,12‐tetraazacyclopentadecane ([15]aneN₄) afforded the new binuclear cobalt sulfur compounds [Co(μ‐S₂)([15]aneN₄)]₂[BPh₄]₂ ( 1 ) and [Co(μ‐S₂)([15]aneN₄)]₂[ClO₄]₂ ( 2 ), respectively, in which two cobalt atoms are bridged by two μ‐η¹ : η¹ disulfido groups forming six‐membered Co₂S₄ heterocycles.     

Lanthanoid Antimonides Ln2Sb5 (Ln = Sm,Gd, Tb,Dy) and Rationalization of Chemical Bonding within the Antimony Polyanion by Combining the Zintl‐Klemm Concept with Bond‐Length Bond‐Strength Relationships

The title compounds are formed by peritectic reactions. Single crystals could be isolated from samples with high antimony content. Their structure was determined for Dy₂Sb₅ from four‐circle X‐ray diffractometer data: P2₁/m, a = 1306.6(1) pm, b = 416.27(4) pm, c = 1458.4(1) pm, β = 102.213(8)°, Z = 4, R = 0.061 for 2980 structure factors and 86 variable parameters. All dysprosium atoms have nine antimony neighbors forming tricapped trigonal prisms with Dy–Sb distances varying between 308 and 338 pm. The antimony atoms occupy ten different sites with greatly varying coordination. One extreme case is an antimony atom surrounded only by dysprosium atoms in trigonal prismatic arrangement, the other one is an antimony atom in distorted octahedral antimony coordination. The various antimony‐antimony interactions (with Sb–Sb distances varying between 284 and 338 pm) are rationalized by combining the Zintl‐Klemm concept with bond‐length bond‐strength considerations.     

Rare Earth-Rich Indides <Emphasis Type="Italic">RE</Emphasis><Subscript>5</Subscript>Pt<Subscript>2</Subscript>In<Subscript>4</Subscript> (<Emphasis Type="Italic">RE</Emphasis> = Sc,Y, La–Nd,Sm, Gd–Tm,Lu)

Summary. The isotypic indides RE ₅Pt₂In₄ (RE = Sc, Y, La–Nd, Sm, Gd–Tm, Lu) were synthesized by arc-melting of the elements and subsequent annealing. They were investigated via X-ray powder diffraction. Small single crystals of Gd₅Pt₂In₄ were grown via slow cooling and the structure was refined from X-ray single crystal diffractometer data: Pbam, a = 1819.2(9), b = 803.2(3), c = 367.6(2) pm, wR ² = 0.089, 893 F ² values and 36 parameters. The structure is an intergrowth variant of distorted trigonal and square prismatic slabs of compositions GdPt and GdIn. Together the platinum and indium atoms build up one-dimensional [Pt₂In₄] networks (292–333 pm Pt–In and 328–368 pm In–In) in an AA stacking sequence along the c axis. The gadolinium atoms fill distorted square and pentagonal prismatic cages between these networks with strong bonding to the platinum atoms.     

The sila-explosives Si(CH2N3)4 and Si(CH2ONO2)4: silicon analogues of the common explosives pentaerythrityl tetraazide, C(CH2N3)4, and Pentaerythritol Tetranitrate, C(CH2ONO2)4

The reaction of tetrakis(chloromethyl)silane, Si(CH2Cl)4, with sodium azide afforded tetrakis(azidomethyl)silane (sila-pentaerythrityl tetraazide, Si(CH2N3)4 (1b)). Nitration of tetrakis(hydroxymethyl)silane, Si(CH2OH)4, with nitric acid resulted in the formation of tetrakis(nitratomethyl)silane (sila-pentaerythritol tetranitrate, Si(CH2ONO2)4 (2b)). Compounds 1b and 2b are extremely shock-sensitive materials and very difficult to handle. Spectroscopic data were obtained as good as sensitivity and safety allowed for umambiguous identification. Quantum chemical calculations (DFT) of the C/Si pairs C(CH2OH)4/Si(CH2OH)4, 1a/1b, and 2a/2b regarding the structures and electronic populations were performed.     

Stable isotope dilution assay for the accurate determination of mycotoxins in maize by UHPLC-MS/MS

A fast, easy-to-handle and cost-effective analytical method for 11 mycotoxins currently regulated in maize and other cereal-based food products in Europe was developed and validated for maize. The method is based on two extraction steps using different acidified acetonitrile–water mixtures. Separation is achieved using ultrahigh-performance liquid chromatography (UHPLC) by a linear water–methanol gradient. After electrospray ionisation, tandem mass spectrometric detection is performed in dynamic multiple reaction monitoring mode. Since accurate mass spectrometric quantification is hampered by matrix effects, uniformly [¹³C]-labelled mycotoxins for each of the 11 compounds were added to the sample extracts prior to UHPLC-MS/MS analysis. Method performance parameters were obtained by spiking blank maize samples with mycotoxins before as well as after extraction on six levels in triplicates. The twofold extraction led to total recoveries of the extraction steps between 97% and 111% for all target analytes, including fumonisins. The [¹³C]-labelled internal standards efficiently compensated all matrix effects in electrospray ionisation, leading to apparent recoveries between 88% and 105% with reasonable additional costs. The relative standard deviations of the whole method were between 4% and 11% for all analytes. The trueness of the method was verified by the measurement of several maize test materials with well-characterized concentrations. In conclusion, the developed method is capable of determining all regulated mycotoxins in maize and presuming similar matrix effects and extraction recovery also in other cereal-based foods.     

Dual nuclear magnetic resonance for probing intrinsic bone structure and a potential gut–bone axis in ovariectomized rats

Currently, the existence of a gut–bone axis receives massive attention, and while sound premises and indirect proofs exist for the gut–bone axis concept, few studies have provided actual data linking the gut and bone physically. This study aimed to exploit the versatile nature of nuclear magnetic resonance (NMR) to link NMR relaxometry data on bone mineralization with NMR spectroscopic profiling of gut metabolites. For this purpose, sample material was obtained from a 6-week intervention study with ovariectomized (OVX) rats (n = 49) fed with seven different diets varying in calcium content (0.2–6.0 mg/kg) and prebiotic fiber content (0–5.0% w/w). This design ensured a span in (i) calcium available for bone mineralization and (ii) metabolic activity in the gut. After termination of the intervention, longitudinal (T₁), transverse (T₂) relaxation, and mechanical bone strength were measured on the excised femur bones. A PLS model with high predictability (Q² = 0.86, R² = 0.997) was demonstrated between T₂ decay curves and femur mechanical strength. Correlations were established between bone T₂ populations and gut short-chain fatty acids. In conclusion, the present dual NMR approach showed strong correlation between T₂ relaxation and mechanical strength of the bone, and when metabolic activity in the gut was modulated by inulin, the potential existence of a gut–bone axis was demonstrated.