Search

The Ca2Pd2Ge-type stannides Sr2Pd2Sn and Eu2Pd2Sn were synthesized by reaction of the elements in sealed tantalum ampoules in a high-frequency furnace and characterized by powder X-ray diffraction. The structure of Sr2Pd2Sn (Fdd2, a = 1063.95(5), b = 1623.22(9), c = 594.63(14) pm, wR2 = 0.0472, 972 F 2 values and 26 variables) was refined from single-crystal X-ray diffractometer data. The striking structural motif features equidistant chains formed by the palladium atoms (304.7 pm Pd–Pd), which are interlinked by the tin atoms (266.9 and 268.7 pm Pd–Sn). Together, the palladium and tin atoms form a three-dimensional [Pd2Sn] δ– polyanionic network in which the strontium atoms reside in larger cavities. The divalent character of europium in Eu2Pd2Sn was manifested by 151Eu Mössbauer spectroscopy. The isomer shift is δ = −9.48(1) mm s−1 at room temperature. The results of 119Sn Mössbauer-spectroscopic experiments have confirmed the tin site determined by the single-crystal study, the isomer shifts being δ = 1.71(1) mm s−1 for Eu2Pd2Sn and δ = 1.73(1) mm s−1 for Sr2Pd2Sn. Sr2Pd2Sn is a Pauli paramagnet with a susceptibility of 2.2(1) × 10−5 emu mol−1 at room temperature. Eu2Pd2Sn shows Curie-Weiss paramagnetism with an experimental magnetic moment of 7.85(1) µB per Eu atom, confirming divalent europium. The europium magnetic moments order antiferromagnetically at T N = 14 K.

The stannide BaRhSn2 was synthesized by induction melting of an arc-melted RhSn2 precursor compound with barium in a sealed tantalum ampoule. The structure of BaRhSn2 was refined from single-crystal X-ray diffractometer data: MgCuAl2 type, Cmcm, a = 437.56(4), b = 1242.35(10), c = 767.30(6) pm, wR2 = 0.0845, 469 F 2 values and 16 variables. The rhodium and tin atoms form a two-dimensional [RhSn2] δ− polyanionic network with short Rh–Sn (273–274 pm) and Sn–Sn (303–312 pm) distances. The large barium atoms lead to a substantial orthorhombic distortion of the (lonsdaleite-related) tin substructure, forcing a break of the Sn–Sn bond in b direction. This change in the tin substructure is reflected in the 119Sn Mössbauer spectrum. The tin atoms exhibit a higher s electron density which is expressed in an increased isomer shift of δ = 2.08(1) mm s−1 as compared to the previously reported stannide CaRhSn2 with a three-dimensional [RhSn2] δ− polyanionic network and δ = 1.96(4) mm s−1.

Eu2Pd3.37Zn13.63, trigonal, R 3 ‾ m $R\overline{3}m$ (no. 166), a = 9.1693(7) Å, c = 13.2443(13) Å, V = 964.34(14) Å3, Z = 3, Rgt (F) = 0.0268, wR ref(F 2) = 0.0287, T = 293 K.

NbGa3, tetragonal, I4/mmm (no. 139), a = 3.7930(6) Å, c = 8.7049(13) Å, V = 125.24(3) Å3, Z = 2, R gt (F) = 0.0303, wR ref (F 2) = 0.0702, T = 293 K.

The ternary Laves phases Sr2Pd3Sn, Eu2Pd3Sn and Eu2Pd3In were synthesized by induction melting of the elements in sealed tantalum ampoules. The polycrystalline products were characterized through their powder X-ray diffraction patterns. The structure of Eu2Pd3Sn was refined from single crystal X-ray diffractometer data: Mg2MnGa3 type, Cmcm, a = 583.36(5), b = 908.31(7), c = 958.06(8) pm, wR2 = 0.0366, 557 F 2 values, 23 variables. The palladium and tin atoms show the inverse coloring on the network of condensed tetrahedra of Mg2MnGa3, i.e., MnGa3 versus Pd3Sn. Refinement of the occupancy parameters revealed small defects for the europium site, leading to composition Eu1.962(6)Pd3Sn for the studied crystal. Sr2Pd3Sn is a Pauli paramagnet and Eu2Pd3Sn shows Curie-Weiss paramagnetism (7.86(1) µB Eu atom−1 and Θ P = 48.1(1) K). Ferromagnetic ordering is observed below T C = 46.1(1) K. The 119Sn and 151Eu Mössbauer spectra of Sr2Pd3Sn and Eu2Pd3Sn are discussed with respect to electron density changes as a function of the tin content and the ionicity in the sequence of the stannides Sr2Pd3Sn/Eu2Pd3Sn → Sr2Pd2Sn/Eu2Pd2Sn → EuPdSn → EuPdSn2.

The ternary intermetallic phases REPd2Zn3 (RE = Y, La–Nd, Sm, Gd–Dy) were synthesized from the elements by induction melting in sealed niobium ampoules followed by annealing. The CaCu5-type samples (space group P6/mmm) were characterized through Guinier powder patterns. The structures of YPd2Zn3 (a = 523.91(4), c = 430.88(3) pm, wR2 = 0.0570, 96 F 2 values, 9 variables) and NdPd2Zn3 (a = 535.08(7), c = 427.81(6) pm, wR2 = 0.0217, 123 F 2 values, 9 variables) were refined from single-crystal X-ray diffractometer data. The zinc atoms form Kagome layers in AA stacking which leave trigonal prismatic voids for the palladium and hexagonal prismatic voids for the rare earth atoms. The Zn–Zn distances within the Kagome network of YPd2Zn3 are 262 pm and the Pd–Zn distances in the Pd@Zn6 trigonal prisms are 263 pm.

Group–subgroup schemes are a useful tool in crystal chemistry for systemizing crystal structures and they are an indispensable help during X-ray crystallographic studies of complex, twinned and modulated structures. Meanwhile many superstructure variants are summarized within so-called Bärnighausen trees. The present database lists relevant literature with respect to the crystallographic/group-theoretical tools and original work and gives a tabulated overview on the crystallographic fingerprints (aristotype, space group symbol, Pearson code and Wyckoff sequence) of the respective superstructures.

Electron-rich [Fe(CN)4]6− features a π-backbonding scheme with non-innocent CN-ligands exhibiting weak C–N bonds and a d10 configuration on iron.

The synthesis and characterization of bis(di-tert-butylindenyl) germanium(ii), tin(ii) and lead(ii) complexes are reported, which includes the first structurally authenticated example of a bis(indenyl)germanocene.

The synthesis of kinetically-stabilized, i.e., metastable, dielectric semiconductors, represents a major frontier within key technologically-important fields as compared to thermodynamically-stable solids that have received considerably more attention. Of longstanding theoretical interest are Sn(II) perovskites (e.g., Sn(Zr1/2Ti1/2)O3, SZT), which are Pb-free analogues of (Pb(Zr1/2Ti1/2)O3, PZT), a commercial piezoelectric composition that is dominant in the electronics industry. Herein, we describe the synthesis of this metastable SZT dielectric through a low-temperature flux reaction technique. The SZT has been found, for the first time, to grow and to be stabilized as a nanoshell at the surfaces of Ba(Zr1/2Ti1/2)O3 (BZT) particles, i.e., forming as BZT-SZT core-shell particles, as a result of Sn(II) cation exchange. In situ powder X-ray diffraction (XRD) and transmission electron microscopy data show that the SZT nanoshells result from the controlled cation diffusion of Sn(II) cations into the BZT particles, with tunable thicknesses of ~25 nm to 100 nm. The SZT nanoshell is calculated to possess a metastability of ~ 0.5 eV atom–1 with respect to decomposition to SnO, ZrO2, and TiO2, and thus cannot currently be prepared as stand-alone particles. Rietveld refinements of the XRD data are consistent with a two-phase BZT-SZT model, with each phase possessing a generally cubic perovskite-type structure and nearly identical lattice parameters. Mössbauer spectroscopic data (119Sn) are consistent with Sn(II) cations within the SZT nanoshells and an outer ~5 to 10 nm surface region comprised of oxidized Sn(IV) cations from exposure to air and water. The optical band gap of the SZT shell was found to be ~2.2 eV, which is redshifted by ~1.2 eV as compared to BZT. This closing of the band gap was probed by X-ray photoelectron spectroscopy and found to stem from a shift of the valence band edge to higher energies (~1.07 eV) as a result of the addition of the Sn 5s2 orbitals forming a new higher-energy valence band. In summary, a novel synthetic tactic is demonstrated to be effective in preparing highly metastable SZT and representing a generally useful strategy for the kinetic stabilization of other predicted, metastable dielectrics.

Directed design of new photocatalysts remains a challenging task in materials chemistry. One approach in metal oxides is to engineer the bulk electronic structure to achieve enhanced visible-light ...

The compounds Pn(pyS)3 (Pn = P, As, Sb, Bi) were synthesized from the respective chloride (Pn = P, As, Sb) or nitrate (Bi), pyridine-2-thiol (pySH) and triethylamine (NEt3) as a supporting base in THF (P, Sb), CHCl3 (As) or methanol (Bi). Sb(pyS)3 was also obtained from the reaction of SbCl3 with LipyS (prepared in situ) in methanol. The compounds Sb(pyS)2Ph and Sb(pyS)Ph2 were prepared in a one-pot reaction starting from SbCl3 and SbPh3 (1:1 ratio). Upon Cl/pyS substitution, the resulting reaction mixture allows for a facile separation of the products in hot hexane. P(pyS)3 and As(pyS)3 crystallize isostructurally to the reported structure of Sb(pyS)3 with κ-S-bound pyS ligands. These crystal structures feature close Pn···Pn contacts which are most pronounced for the arsenic derivative. Bi(pyS)3 adopts a different molecular structure in the solid state, which features two chelating (κ 2-S,N-pyS) ligands and a κ-S-bound ligand. The presence of N→Bi interactions between the nitrogen atom of the κ-S-pyS ligand and the Bi atom of another molecule renders this structure a polymer chain along the crystallographic b axis with Bi⋅⋅⋅Bi van-der-Waals contacts. The structures of this set of Pn(pyS)3 compounds were also studied in solution using 1H NMR spectroscopy, revealing equivalent pyS ligands in discrete Pn(pyS)3 molecules. The molecular structure of Sb(pyS)Ph2 was optimized by quantum chemical methods, and a comparison with the structures reported for the other Sb/pyS/Ph combinations reveals Sb(pyS)2Ph to feature the strongest Sb···N interactions with the κ-S-pyS ligand. The results of 1H NMR spectroscopic investigations of the compounds Sb(pyS) x Ph3–x (x = 3–0) suggest the Ph protons in ortho position to be incorporated into intramolecular C–H···S contacts for x = 2 and 1. Natural localized molecular orbital (NLMO) calculations were employed in order to gain insights into the electronic situations of the Pn atoms and Pn–R bonds (R = S, C), especially for the effects caused by formal substitution of Pn in the compounds Pn(pyS)3 and the ligand patterns in the compounds Sb(pyS) x Ph3–x (x = 3–0). For the latter series of compounds, the electronic situation of the Sb atom was further studied by 121Sb Mössbauer spectroscopy, providing a correlation between the calculated electron density at Sb [ρ(0)] and the experimentally observed isomer shift δ. The missing link between group 15 and group 13 metal compounds of the type M(pyS)3, compound Al(pyS)3, was synthesized in this work. In the solid state (confirmed crystallographically), the mer isomer of this tris-chelate complex with distorted octahedral Al coordination sphere was found. This coordination mode was confirmed for the solution state (CDCl3) by 1H and 13C NMR spectroscopy at T = −40 °C.

Binary antimonides of composition MSb (M = Al, Ga, In), RESb (RE = Sc, Y, La), CdSb, RE4Sb3 (RE = Sc, La), and T5Sb4 (T = Nb, Ta) as well as the pseudobinary solid solutions (La0.25M0.75)4Sb3 (M = ...

The synthesis and characterization of bis(di

The yttrium-rich intermetallic compounds Y14Ni3Cd3 and Y6Co2Zn were obtained by direct reactions of the elements in sealed tantalum tubes in an induction furnace. Both samples were characterized by X-ray powder diffraction and the structures were refined from single-crystal X-ray diffraction data: Lu14Co3In3 type, P42/nmc, a = 960.06(5), c = 2314.9(1) pm, wR2 = 0.0669, 2034 F 2 values, 63 parameters for Y14Ni3.16(2)Cd2.84(2) and Ho6Co2Ga type, Immm, a = 943.08(7), b = 950.08(7), c = 997.64(7) pm, wR2 = 0.0476, 981 F 2 values, 34 parameters for Y6Co2Zn. One cadmium site shows a small degree of Cd/Ni mixing, leading to the composition Y14Ni3.16(2)Cd2.84(2). Although both compounds crystallize with significantly different structure types, they show very similar monomeric building units: (i) transition metal centered trigonal prisms of yttrium, (ii) empty Y6 octahedra and (iii) icosahedral coordination of the cadmium respectively zinc atoms. The condensation patterns of these building units are discussed and for Y14Ni3.16(2)Cd2.84(2), we elaborate a crystal chemical building principle along with the rare earth metal-rich phases RE 15Rh5Cd2 (La15Rh5Cd2 type), RE 23 T 7 X 4 (Pr23Ir7Mg4 type), RE 4 TX (Gd4RhMg type) and RE 10 TX 3/RE 9 TX 4 (ordered Co2Al5 versions). The structures of Y14Ni3Cd3 and Y6Co2Zn show dumbbell formation: 306 pm Cd–Cd in Y14Ni3Cd3 and 224 pm Co1–Co1 and 246 pm Co2–Co2 in Y6Co2Zn.

Anhydrous EuII–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 μB) 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., Multifaceted! Orange coloured Eu(C4O4), the anhydrous EuII salt of acetylenedicarboxylic acid, has many interesting properties: it is stable in air for months, and upon heating in an inert atmosphere decomposition only starts at 440 °C. Below room temperature it shows a negative thermal volume expansion (NTE) and although containing EuII it does not exhibit any luminescence even at 10 K.

A detailed experimental and computational study of a series of stannocene and plumbocene N-heterocyclic carbene complexes is presented. This unique class of group 14 Lewis acid–base adducts was obt...

[SnI8{Fe(CO)4}4][Al2Cl7]2 contains the [SnI8{Fe(CO)4}4]2+ cation with an unprecedented highly coordinated, bicapped SnI8 prism. Given the eightfold coordination with the most voluminous stable halide, it is all the more surprising that this SnI8 arrangement is surrounded only by fragile Fe(CO)4 groups in a clip‐like fashion. Inspite of a predominantly ionic bonding situation in [SnI8{Fe(CO)4}4]2+, the I−⋅⋅⋅I− distances are considerably shortened (down to 371 pm) and significantly less than the van der Waals distance (420 pm). The title compound is characterized by single‐crystal structure analysis, spectroscopic methods (EDXS, FTIR, Raman, UV/Vis, Mössbauer), thermogravimetry, and density functional theory methods., You're clinging! In a clip‐like fashion, Fe(CO)4 groups surround a central SnI8 subunit in [SnI8{Fe(CO)4}4]2+, which has an unprecedentedly high coordination of tin with the most voluminous, stable halide.

The gold-rich intermetallic compounds REAu4Cd2 (RE = La–Nd, Sm) were synthesized from the elements in sealed tantalum ampoules. Their characterization by X-ray powder and single crystal data confirmed the tetragonal YbAl4Mo2 type, space group I4/mmm. The basic building units are Au4 squares (278 pm Au–Au in CeAu4Cd2) and infinite linear cadmium chains (275 pm Cd–Cd in CeAu4Cd2). We exemplarily studied the solid solution CeAu4+ x Cd2− x for x = 0–1 up to CeAu5Cd. Electron diffraction patterns on a CeAu5Cd sample confirm the single crystal data. They give no hint for complete gold-cadmium ordering. Temperature-dependent magnetic susceptibility measurements of CeAu4Cd2, CeAu5Cd, PrAu4Cd2 and NdAu4Cd2 show stable trivalent rare earth ions and give no hint for magnetic ordering above 3 K.

Four new MPtAl2 (M=Ca, Sr, Ba, Eu) compounds, adopting the orthorhombic MgCuAl2 -type structure, have been synthesized from the elements using tantalum ampoules. All compounds are obtained as platelet-shaped crystallites and exhibit an increasing moisture sensitivity with increasing size of the formal M cation. Structural investigations indicate a pronounced elongation of the crystallographic b-axis, which results in a significant distortion of the [PtAl2 ]δ- polyanion. Within the polyanion, layer-like arrangements can be found with bonding Pt-Al interactions within the slab; the increase of the b-axis can be attributed to increasing Al-Al distances and therefore decreasing interactions between the slabs, caused by the differently-sized formal M cations. While the alkaline earth (M=Ca, Sr) representatives exhibit Pauli paramagnetism, BaPtAl2 shows diamagnetic behavior, finally EuPtAl2 is ferromagnetic with TC =54.0(5) K. The effective magnetic moment indicates that the Eu atoms are in a divalent oxidation state, which is confirmed by 151 Eu Mossbauer spectroscopic investigations. Measurements below the Curie-temperature show a full magnetic hyperfine field splitting with Bhf =21.7(1) T. 27 Al and 195 Pt magic-angle spinning NMR spectroscopy corroborates the presence of single crystallographic sites for the Pt and Al atoms. The large 27 Al nuclear electric quadrupolar coupling constants confirm unusually strong electric field gradients, in agreement with the structural distortions and the respective theoretical calculations. X-ray photoelectron spectroscopy has been utilized to investigate the charge transfer within the polyanion. The Pt 4f binding energy decreases with decreasing electronegativity / ionization energy of the alkaline earth elements, suggesting an increasing electron density at the Pt atoms. Theoretical investigations underline the platinide character of the investigated compounds by Bader charge calculations. The analysis of the integrated crystal orbital Hamilton population (ICOHP) values, electron localization function (ELF) and isosurface analyses lead to a consistent structural picture, indicating stable layer-like arrangements of the [PtAl2 ]δ- polyanion.

The rare earth-rich intermetallic compounds RE4OsCd (Gd4RhIn type, RE = La–Nd, Sm, Gd) and RE10OsCd3 (Er10FeCd3 type, RE = Y, Sm, Gd–Tm, Lu) were synthesized by induction melting of the pure elements in sealed niobium ampoules and characterized through their X-ray powder patterns. The structures of Ce4OsCd, Nd4Os0.83Cd1.17, Sm9.87OsCd3.13, and Tm9.89OsCd3.11 were refined from X-ray single crystal diffractometer data. These intermetallics are the first ternary osmium–cadmium compounds. The striking structural feature is an adamantane-like network of osmium-centered trigonal prisms in the RE4OsCd phases with Cd4 tetrahedra (308 pm Cd–Cd in Ce4OsCd) in the cavities. The RE10OsCd3 phases exhibit triangular Cd3 clusters (328 pm Cd–Cd in Sm9.87OsCd3.13) which, together with rare earth atoms, form chains of corner- and face-sharing Cd3RE tetrahedra. Further motifs are Os@RE6 trigonal prisms (TP) that are condensed to empty RE6 octahedra (O), building infinite…TP–O–O… rows in c direction. The two types of rows show the motif of a hexagonal rod packing.

Ternary rare earth metal-rich intermetallic phases containing osmium and magnesium were obtained by induction melting of the elements in sealed niobium ampoules under argon followed by annealing in muffle furnaces. The large rare earth elements form the series of Gd4RhIn-type (F4̅3m) intermetallics RE 4OsMg with RE = La–Nd and Sm, while the smaller rare earth metals gadolinium and terbium form the Y9CoMg4-type (P63/mmc) phases Gd9OsMg4 and Tb9OsMg4. All samples were characterized by X-ray powder diffraction (Guinier technique). The structures of Ce4Os0.973Mg1.027 (a = 1406.54(7) pm, wR2 = 0.0478), Nd4Os0.978Mg1.022 (a = 1402.00(7) pm, wR2 = 0.0463), Sm4Os0.920Mg1.080 (a = 1387.33(5) pm, wR2 = 0.0378) and Gd9OsMg4 (a = 971.01(5), c = 980.43(5) pm, wR2 = 0.0494) were refined from single-crystal X-ray diffractometer data. The three RE 4OsMg phases show small degrees of Os/Mg mixing, as is frequently observed for Rh/In in Gd4RhIn-type intermetallics. The basic building units in both structures are osmium-centered RE 6 trigonal prisms that are condensed with empty RE 6 octahedra. The magnesium atoms in both types build Mg4 tetrahedra. The latter are isolated (312 pm Mg–Mg in Ce4OsMg) and incorporated within the three-dimensional network of prisms and octahedra in the RE 4OsMg phases while one observes rows of corner- and face-sharing tetrahedra in Gd9OsMg4 (305 and 314 pm Mg–Mg). In both structure types direct Os–Mg bonding is not observed.

Eu2Mg4Si3 ≡ (2Eu2+)(4Mg2+)(3Si4−) is an electron-precise Zintl phase. Its Hf2Co4P3-type structure contains three crystallographically independent europium sites. The divalent state of europium was manifested through 151Eu Mössbauer spectroscopy. In the paramagnetic regime (T = 78 K) the isomer shifts range from −9.16 to −11.29 mm s−1. Eu2Mg4Si3 shows complex magnetic hyperfine field splitting at T = 5.7 K with a superposition of three subspectra with magnetic hyperfine fields of 5.4 (Eu2), 20.4 (Eu1) and 22.4 (Eu3) T.

Phase-pure samples of the antimonides PrPdSb and NdPdSb were prepared by arc-melting pieces of the elements and subsequent annealing. The samples were investigated by powder and single crystal X-ray diffraction: NdPtSb type, space group P63 mc, a = 458.70(5), c = 780.55(6) pm, wR2 = 0.0272, 244 F 2 values, 11 variable parameters for PrPdSb and a = 458.18(4), c = 771.25(6) pm, wR2 = 0.0317, 229 F 2 values, 11 variable parameters for NdPdSb. The palladium and antimony atoms form slightly puckered Pd3Sb3 hexagons which are rotated by 60° in every other layer. The rare earth (RE) atoms are coordinated by two Pd3Sb3 hexagons with the RE–Pd shorter than the RE–Sb contacts. The 121Sb Mössbauer spectra at T = 5 K confirm the antimonide character with isomer shifts of −7.55 (PrPdSb) and −7.47 mm · s−1 (NdPdSb). In agreement with the crystal structures, each spectrum could be fitted with one quadrupole split signal.

Eu2 Ir3 Al9 , synthesized from the elements in tantalum tubes, is one of the rare examples for trivalent europium in the field of intermetallic compounds. The compound crystallizes in the Y2 Co3 Ga9 -type structure (space group Cmcm), with lattice parameters fitting in between the isostructural samarium and gadolinium compounds. In the crystal structure, the Eu atoms form Al3 -triangle-centered honeycomb layers and exhibit a coordination number of 17 in the shape of a fivefold-capped hexagonal prism (Eu@Ir6 Al6 +Al5 ). Magnetic measurements indicate an overall low susceptibility, in line with van Vleck paramagnetism caused by the Eu3+ cations. Fits of the susceptibility yield a coupling constant of λ=290(10) K and an effective magnetic moment of μeff =4.56(1) μB , in line with a slight hybridization of the 7 F0 and 7 F1 state. 151 Eu Mossbauer spectroscopic investigations unambiguously prove the presence of solely Eu3+ in the bulk material.

A series of ternary transition metal gallides around the equiatomic composition have been synthesized from the elements by arc-melting and subsequent annealing. The compounds crystallize with site occupancy variants of the hexagonal Laves phase MgZn2, with the hexagonal ZrBeSi or the orthorhombic TiNiSi type. All samples have been characterized on the basis of their lattice parameters, determined by X-ray powder diffraction (Guinier technique). The structures of NbCr1.58Ga0.42and NbFe1.51Ga0.49(MgZn2type,P63/mmc), NbRhGa (ZrBeSi type,P63/mmc), and ScNiGa, ScPtGa and ScAuGa (TiNiSi type,Pnma) were refined from single crystal X-ray diffractometer data. The ScPtGa and ScAuGa crystals showed trilling formation. Mixed site occupancies were only observed in the Laves phases while all other crystals were well ordered. A striking structural motif of NbRhGa is the formation of niobium chains (264 pm Nb–Nb) along thecaxis. Several gallides were magnetically characterized. They are Pauli paramagnets. The two crystallographically independent iron sites in the Laves phase TaFeGa could be distinguished in the57Fe Mössbauer spectrum. The isomer shifts of 0.06(3) (Fe1) and –0.02(3) (Fe2) mm s−1indicate metallic iron.

The reaction of the antimony(I) compound ArSb (1) (where Ar = C6H3-2,6-(CHNtBu)2) with various dimeric allyl palladium(II) complexes [Pd(η3-allyl)(μ-X)]2 (where allyl = C3H5 or C3H4Me; X = Cl or CF3CO2) in a 1 : 1 stoichiometric ratio gave unique complexes with the μ-ArSb moiety bridging two palladium fragments, i.e. [{Pd(η3-C3H5)Cl}2(μ-ArSb)] (2), [{Pd(η3-C3H4Me)Cl}2(μ-ArSb)] (3) and [{Pd(η3-C3H5)(CF3CO2)}2(μ-ArSb)] (4). Compound 1 serves formally as a 4e donor in 2–4. The treatment of 2 with another equivalent of ArSb led to the formation of the [Pd(η3-C3H5)(Cl)(μ-ArSb)] complex (5), proving that 1 is able to function as a 2e donor in target complexes as well. The structures of 2–5 were described in detail both in solution (NMR and mass spectrometry) and in the solid state (single crystal X-ray diffraction analysis). DFT methods were used to compare bonding in the 1 : 1 (5) and 1 : 2 (2) complexes. Furthermore, a comprehensive 121Sb Mossbauer spectroscopic investigation of complexes 2 and 5 along with parent ArSbCl2 (6) and 1 was performed. For comparison, complexes [Fe(CO)4(ArSb)] (7) and [Mo(CO)5(ArSb)] (8) were also included in this study.

The pnictides Eu14AlAs11 and Eu14AlSb11 were synthesized from the elements in sealed niobium ampoules. They crystallize in the tetragonal crystal system (Eu14AlAs11: a = 1627.6(2), c = 2180.0(4) pm; Eu14AlSb11: a = 1725.6(2), c = 2289.7(7) pm) with space group I41/acd, isostructural to Ca14AlSb11 and can be described as Zintl phases. The Al atoms are surrounded by four pnictogen atoms, forming [AlPn4]9− tetrahedra. Additionally isolated Pn3− anions and linear Pn37− trimers can be found in the crystal structure. The compounds can be described according to (Eu2+)14(AlPn9−)(Pn3−)4(Pn37−). Eu14AlAs11 and Eu14AlSb11 both exhibit an antiferromagnetic transition at TN = 10.5(1) K and 12.5(1) K, respectively. For the antimonide, the magnetic transition has been confirmed by additional heat capacity measurements. Resistivity investigations indicate that Eu14AlSb11 is a semiconductor with a band gap of Eg = 0.28(5) eV close to room temperature. According to the Zintl formalism, the Eu atoms are divalent, which has been confirmed by magnetic susceptibility and additional 151Eu Mossbauer spectroscopic studies. The measurements conducted at 6 K, below the magnetic ordering temperature, show a full hyperfine field splitting with complex spectra underlining the recorded magnetic data. Furthermore, 121Sb Mossbauer spectroscopic studies have been conducted to study the different antimonide entities in the title compounds.

The equiatomic iron-silicides TFeSi as well as the corresponding germanides TFeGe with the electron-poor 4d and 5d transition metals (T=Zr, Nb, Hf, Ta) have been synthesized from the elements by arc-melting. All samples were characterized through their lattice parameters using powder X-ray diffraction (Guinier technique). Four structures were refined from single-crystal X-ray diffractometer data: a=640.16(3), b=393.45(5), c=718.42(6) pm, Pnma, 390 F 2 values, 20 parameters, wR2=0.0294 for ZrFeSi (TiNiSi type), a=719.63(11), b=1119.27(7), c=649.29(7) pm, Ima2, 1103 F 2 values, 54 parameters, wR2=0.0555 for NbFeGe (TiFeSi type), a=655.96(7), c=372.54(4) pm, P6̅2m, 251 F 2 values, 15 parameters, wR2=0.0260 for HfFeGe (ZrNiAl type) and a=624.10(3), b=378.10(6), c=725.25(7) pm, Pnma, 369 F 2 values, 20 parameters, wR2=0.0513 for TaFeGe (TiNiSi type). The common structural motif of the four different structures is the slightly distorted tetrahedral tetrel (tr) coordination of the iron atoms and a trigonal prismatic coordination of iron by T=Zr, Nb, Hf, Ta. Three compounds were characterized as Pauli-paramagnetic by measuring their susceptibility. The measurement of the electrical resistivity of NbFeSi characterises this compound as a good metal. Furthermore, 57Fe Mössbauer spectra of all compounds could be obtained at room temperature, revealing a clear correlation between the structural distortions and the quadrupole splitting parameters.

Single crystals of the high-temperature modification of RhSn4 were obtained from a tin flux (1:20 molar ratio; final annealing at 920 K; dissolution of the tin matrix in 2N HCl). The structure was refined from single-crystal X-ray diffractometer data: I41/acd, a=629.73(5), c=2288.36(18) pm, wR2=0.0382, 447 F 2 values and 14 variables. β-RhSn4 is isotypic with β-IrSn4. The rhodium atoms have slightly distorted square-antiprismatic tin coordination with Rh–Sn distances of 4×273.4 and 4×274.1 pm. The RhSn8 units are condensed via common edges to layers that are staggered with respect to each other and stacked in ABCD sequence. A 119Sn Mössbauer spectroscopic characterization of ß-RhSn4 and the stannides RhSn3 and α-RhSn4 shows the typical isomer shifts for transition metal stannides. Only for α-RhSn4 the three crystallographically independent tin sites could be resolved, a consequence of the different s-electron density. Treatment of α-RhSn4 under high-pressure (up to 10 GPa)/high-temperature (up to T=1370 K) conditions leads to decomposition into Rh1.5Sn, RhSn2 and β-Sn.

3d transition metal nitridophosphates MII P8 N14 (MII =Fe, Co, Ni) were prepared by high-pressure metathesis indicating that this route might give a systematic access to a structurally rich family of M-P-N compounds. Their structures, which are stable in air up to at least 1273 K, were determined through powder X-ray diffraction and consist of highly condensed tetra-layers of PN4 tetrahedra and MN6 octahedra. Magnetic measurements revealed paramagnetic behavior of CoP8 N14 and NiP8 N14 down to low temperatures while, FeP8 N14 exhibits an antiferromagnetic transition at TN =3.5(1) K. Curie-Weiss fits of the paramagnetic regime indicate that the transition metal cations are in a oxidation state +II, which was corroborated by Mossbauer spectroscopy for FeP8 N14 . The ligand field exerted by the nitride ions in CoP8 N14 and NiP8 N14 was determined from UV/Vis/NIR data and is comparable to that of aqua-ligands and oxophosphates.

In the course of our investigations of the coordination chemistry of trivalent antimony (Sb) compounds, we studied heteronuclear complexes formed in reactions of the compounds RSb(pyS)2 (R = pyS, Ph; pyS- = pyridine-2-thiolate) with [Pt(PPh3)4], i.e., complexes [(R)Sb(μ-pyS)2Pt(PPh3)] (R = pyS, 1; R = Ph, 2). The reaction of 1 with o-chloranil proceeds cleanly with elimination of 2,2'-dipyridyl disulfide and formation of the salt [(PPh3)Pt(μ-pyS)2Sb(μ-pyS)2Pt(PPh3)]+[Sb(C6Cl4O2)2]- (3III), which features the cation 3+. The charge-neutral, unsymmetrically substituted compound [(PPh3)Pt(μ-pyS)2Sb(μ-pyS)2Pt(κS-pyS)] (4) can be accessed by the reaction of 3+ with LipyS. The oxidation of 2 with o-chloranil furnishes the complex [(κ-O,O-C6Cl4O2)PhSb(μ-pyS)2Pt(PPh3)] (5). The oxidation of 1 with PhICl2 afforded the paddlewheel-shaped complex [Sb(μ-pyS)4PtCl] (6). Moreover, compound 6 was obtained by the reaction of Sb(pyS)3 with [PtCl(pyS)(PPh3)]. The polarization of Pt-Sb bonds of compounds 1-6 was investigated by natural localized molecular orbital (NLMO) calculations, which suggest X-type ligand character (covalent Pt-Sb bonds) for 1 and 2, whereas the Sb ligand of 6 reflects Z-type character (dative Pt→Sb bonds). In 3+, 4, and 5, high contributions of the reverse, i.e., L-type (dative Pt←Sb bonds), were observed. In conjunction with the results of NLMO analyses, 121Sb Mossbauer spectroscopy proves that complexes 1-6 represent essentially trivalent Sb complexes with either a free lone pair (LP) at the Sb atom (1, 2, and 6) or LP character involved in L-type Pt←Sb coordination (3+, 4, and 5).

Chemistry - a European journal 26(44), 10133 - 10139 (2020). doi:10.1002/chem.202002653, Lanthanides (Ln) are critical raw materials, however, their mining and purification have a considerable negative environmental impact and sustainable recycling and separation strategies for these elements are needed. In this study, the precipitation and solubility behavior of Ln complexes with pyrroloquinoline quinone (PQQ), the cofactor of recently discovered lanthanide (Ln) dependent methanol dehydrogenase (MDH) enzymes, is presented. In this context, the molecular structure of a biorelevant europium PQQ complex was for the first time elucidated outside a protein environment. The complex crystallizes as an inversion symmetric dimer, Eu$_2$PQQ$_2$, with binding of Eu in the biologically relevant pocket of PQQ. LnPQQ and Ln1Ln2PQQ complexes were characterized by using inductively coupled plasma mass spectrometry (ICP‐MS), infrared (IR) spectroscopy, $^{151}$Eu‐Mössbauer spectroscopy, X‐ray total scattering, and extended X‐ray absorption fine structure (EXAFS). It is shown that a natural enzymatic cofactor is capable to achieve separation by precipitation of the notoriously similar, and thus difficult to separate, lanthanides to some extent., Published by Wiley-VCH, Weinheim

[Ar′SnCo]2 (1, Ar′ = C6H3-2,6{C6H3-2,6-iPr2}2), a rare metal–metal bonded cobalt–tin cluster with low-coordinate tin atoms, was prepared by the reaction of [K(thf)0.2][Co(1,5-cod)2] (cod = 1,5-cyclooctadiene) with [Ar′Sn(μ-Cl)]2. This reaction illustrates a promising synthetic strategy to access uncommon metal clusters. The structure of 1 features a rhomboidal Co2Sn2 core with strong metal–metal bonds between tin and cobalt and a weaker tin–tin interaction. Reaction of 1 with white phosphorus afforded [Ar′2Sn2Co2P4] (2), the first molecular cluster compound containing phosphorus, cobalt and tin.

The intermetallic magnesium compounds CeCuMg and GdCuMg as well as the ternary Laves phasesRECu4Mg (RE=Sm, Gd–Tm) were synthesized from the elements by different annealing sequences in high-frequency and muffle furnaces using niobium ampoules as crucibles. All samples were characterized through the lattice parameters using X-ray powder diffraction (Guinier technique). Two structures were refined from single-crystal X-ray diffractometer data:a=764.75(6),c=414.25(4) pm, space groupP6̅2m,wR2=0.0389, 338F2values, 15 parameters for CeCuMg (ZrNiAl type) anda=723.18(2) pm, space groupF4̅3m, wR2=0.0818, 91F2values, eight parameters for Gd1.06(3)Cu4Mg0.94(3)(MgCu4Sn type). The Laves phase shows a small homogeneity range (Gd/Mg mixing). An investigation of the magnetocaloric effect (MCE) of ferromagnetic GdCuMg (ZrNiAl type;TC=82 K) revealed a magnetic entropy change of ΔSM=6.5 J kg−1K−1and a relative cooling power of RCP=260 J kg−1for a field change from 0 to 70 kOe, classifying GdCuMg as a moderate magnetocaloric material for theT=80 K region. Of the Laves phasesRECu4Mg, SmCu4Mg shows van-Vleck paramagnetism above a Néel temperature of 10.8(5) K, whereas GdCu4Mg and TbCu4Mg undergo antiferromagnetic phase transitions at about 48 and 30 K, respectively. TmCu4Mg shows Curie-Weiss behavior in the entire temperature range. The electrical resistivity of SmCu4Mg and the specific heat capacity of GdCu4Mg were measured for further characterization.

Phase pure Ag2MnSnS4 was synthesized from the elements using standard high-temperature solid-state methods. Its crystal structure was solved from single-crystal X-ray diffraction data collected from a pseudo-merohedrally twinned crystal as well as by Rietveld refinement of X-ray powder diffraction data. Ag2MnSnS4 crystallizes in the monoclinic space group Pc (no. 7) with the unit cell parameters a = 6.651(1), b = 6.943(1), c = 10.536(2) angstrom, beta = 129.15(1)degrees, V = 337.3(1) angstrom(3), and Z = 2. The tetrahedraly compound crystallizes in a superstructure of the wurtzite type and the tetrahedra volumes are in good agreement with the model for diamond-related compounds derived from the wurtzite structure type. The red semiconductor Ag2MnSnS4 has an optical bandgap of E-g = 2.0 eV and is stable up to its peritectic decomposition temperature of approximately 700 degrees C. Ag2MnSnS4 is a Curie-Weiss paramagnet with an experimental magnetic moment of mu(exp) = 5.4(1) mu(B) per manganese atom. Antiferromagnetic ordering is detected at a Neel temperature of T-N = 8.8(1) K. Sn-119 Mo ss bauer spectra at 78 K underline the single tetrahedrally coordinated Sn-IV site (delta = 1.34(1) mm center dot s(-1)). The 6 K spectrum (magnetically ordered state) reveals a small transferred magnetic hyperfine field of 1.02(1) T.

A detailed experimental and computational study of a series of stannocene and plumbocene N-heterocyclic carbene complexes is presented. This unique class of group 14 Lewis acid base adducts was obtained from reactions of the corresponding metallocenes and N-heterocyclic carbenes (NHC), and were structurally characterized by single crystal X-ray diffraction. The obtained structures show a perpendicular pose of the NHC with respect to the metallocene, hence precluding the maximal interaction between the moieties. The nature of the Sn-CNHC and Pb-CNHC bonds have been investigated by applying Energy Decomposition Analysis (EDA-NOCV). For the sake of comparison, known stannocene and plumbocene Lewis base complexes have been included in the series. The attractive chemical bonding interactions are around 50% electrostatic, 30% covalent and 20% dispersion. Indeed, dispersion interactions play a determining role the bigger the substituents become. The covalent interactions derive from the donation of the carbene ligand into the empty p orbital of the metallocene.

The stannides REIr2Sn4 (RE=La, Ce, Pr, Nd, Sm) were synthesized from the elements by arc melting or by induction melting in sealed niobium containers. They crystallize with the NdRh2Sn4 type structure, space group Pnma. The samples were characterized by powder X-ray diffraction (Guinier technique). Three structures were refined from single-crystal X-ray data: a=1844.5(2), b=450.33(4), c=716.90(6) pm, wR2=0.0323, 1172 F 2 values, 44 variables for LaIr2Sn4, a=1840.08(2), b=448.24(4), c=719.6(1) pm, wR2=0.0215, 1265 F 2 values, 45 variables for Ce1.13Ir2Sn3.87, and a=1880.7(1), b=446.2(1), c=733.0(1) pm, wR2=0.0845, 836 F 2 values, 45 variables for Ce1.68Ir2Sn3.32. The structures consist of three-dimensional [Ir2Sn4] polyanionic networks in which the rare earth atoms fill pentagonal prismatic channels. The striking structural motif concerns the formation of solid solutions RE 1+ x Ir2Sn4− x on the Sn4 sites, which have similar coordination as the RE sites. Temperature dependent magnetic susceptibility measurements revealed diamagnetic behavior for LaIr2Sn4. CeIr2Sn4, PrIr2Sn4 and NdIr2Sn4 show Curie-Weiss paramagnetism while SmIr2Sn4 exhibits typical van Vleck paramagnetism. Antiferromagnetic ground states were observed for CeIr2Sn4 (T N=3.3 K) and SmIr2Sn4 (T N=3.8 K). 119Sn Mössbauer spectra show a close superposition of four sub-spectra which can be distinguished through their isomer shift and the quadrupole splitting parameter.

Eu2Pt6Al15 has been prepared from the elements via arc-melting and subsequent temperature treatment; the structure was refined from single crystal X-ray diffraction data. The compound crystallizes in an orthorhombic (3 + 1)D commensurately modulated structure (Sc2Pt6Al15 type) with space group Cmcm(α,0,0)0s0 (α = 2/3). Full ordering of the Pt and Al atoms within the [Pt6Al15]δ− polyanion was observed. Magnetic measurements revealed an anomaly in the susceptibility data at T = 41.6(1) K, which was also observed as λ-type anomaly in heat capacity measurements (T = 40.7(1) K). Temperature dependent powder X-ray diffraction experiments indicated a drastic shortening of the c axis (−18 pm, −1.1%) around 45 K, while the a axis nearly remains the same (−1 pm, −0.2%). Measurements of the electrical resistivity verified the anomaly, indicating a clear change in the electronic structure of the material. The observed anomalies in the physical measurements can be explained by a temperature driven first order valence ...

1,1′-Dilithioferrocene was reacted with 2 equiv of isopropyl (Ar*) or methyl (Ar′) substituted terphenyl tin(II) chloride. Reaction product 1, carrying the bulkier terphenyl substituent Ar*, displays a bis(stannylene) structure in the solid state without formation of a tin–tin bond. Temperature-dependent solution 119Sn NMR spectroscopy, however, revealed a dynamic interplay between bis(stannylene) (100 °C) and cyclic distannene (−80 °C). In contrast to 1, the less bulky Ar′ substituent results in a cyclic distannene 2. On the basis of temperature-dependent 119Sn NMR spectroscopy the Sn–Sn bond of compound 2 was preserved up to 100 °C. Both compounds were further characterized by solid-state 119Sn NMR spectroscopy as well as 119Sn and 57Fe Mossbauer spectroscopy. 1 reacted as a chelating ligand with nickel and palladium complexes [Ni(cod)2] and [Pd(nbe)3] (nbe = norbornene). In the resulting coordination compounds the nonstabilized stannylene acts as a donor as well as an acceptor ligand and shows a dynami...

Highly condensed nitridosilicates doped with Eu2+ or Ce3+ play an important role in saving energy by converting the blue light of (In,Ga)N-LEDs. Although nitridosilicates are known for great structural variety based on covalent anionic Si-N networks, elemental variety is restricted. Presenting a significant extension of the latter, this work describes a general access to open-shell transition-metal nitridosilicates. As a proof-of-principle, the first iron nitridosilicate, namely Fe2 Si5 N8 , was prepared by exchanging Ca2+ in α-Ca2 Si5 N8 applying a FeCl2 melt (salt metathesis). The title compound was analyzed by powder X-ray diffraction, EDX, ICP-OES, combustion analysis, TG/DSC, Mossbauer spectroscopy and magnetic susceptibility measurements. Furthermore, the structure of α-Ca2 Si5 N8 was determined at 1073 and 1173 K confirming the anionic network of α-Ca2 Si5 N8 providing possible migration pathways for the ion-exchange reaction.

Catalysed alkane oxyhalogenation has recently been demonstrated as an attractive route for the selective functionalisation of natural gas into commodity chemicals such as alkyl halides or olefins. Herein, we assess the role of the hydrogen halide on the product distribution in ethane and propane oxyhalogenation over europium oxychloride and europium oxybromide catalysts. While olefins are the main reaction products in oxychlorination (selectivity ≥95%), the formation of alkyl bromides (selectivity ≤95%) is favoured in oxybromination, particularly at low conversion levels. At high conversion levels, olefins are also observed, although the selectivity is generally limited (≤60%) due to the formation of cracking and combustion products. A comprehensive kinetic analysis of the oxyhalogenation, halogenation, and oxidative dehydrogenation of the alkanes as well as of the dehydrohalogenation of the alkyl halides provide insights on the complex reaction network, which proceeds through alkyl halide formation followed by its conversion to olefins and/or halocarbons. The observed selectivity differences primarily originate from (i) the halide-dependent alkane activation path, which is surface-driven in oxychlorination, while it mostly occurs via gas-phase halogenation in oxybromination, along with (ii) the preferred tendency of alkyl chlorides towards catalytic dehydrochlorination pathways opposing alkyl bromides that undergo further bromination routes in the gas phase. Finally, detailed characterisation corroborated the above findings and revealed the higher structural stability of europium oxychloride compared to the analogous oxybromide phase under oxyhalogenation conditions. These results deepen the understanding of the alkane oxyhalogenation chemistry on catalyst surfaces for the manufacture of valuable commodities.

Recently, we reported the synthesis and investigations of EuSr2Bi2S4F4 and Eu2SrBi2S4F4. We have now been able to induce superconductivity in EuSr2Bi2S4F4 by Se substitution at the S site (isovalent substitution) with Tc = 2.9 K in EuSr2Bi2S2Se2F4. The other compound, Eu2SrBi2S4F4, shows a significant enhancement of Tc. In Se-substituted Eu2SrBi2S4–xSexF4, we find Tc = 2.6 K for x = 1.5 and Tc = 2.8 K for x = 2, whereas Tc = 0.4 K in the Se-free sample. In addition to superconductivity, an important effect associated with Se substitution is that it gives rise to remarkable changes in the Eu valence. Our 151Eu Mossbauer and X-ray photoemission spectroscopic measurements show that Se substitution in both of the compounds Eu2SrBi2S4F4 and EuSr2Bi2S4F4 gives rise to an increase in the Eu2+ component in the mixed-valence state of Eu.