Preparation and Crystal Structure of Au1—xSn1+yP14 and other Polyphosphides with HgPbP14‐Type Structure

The crystal structure of the known compound HgSnP₁₄ (HgPbP₁₄‐type, Pnma, Z = 4) was refined from single‐crystal X‐ray diffractometer data to a residual of R = 0.067 for 1470 structure factors and 83 variable parameters. This polyphosphide has a smaller cell volume than the isotypic compound CdSnP₁₄. For that reason it had been suggested earlier that the mercury atoms in HgSnP₁₄ will show a tendency for linear P—Hg—P coordination. This is not supported by the present structure refinement, which shows a distorted tetrahedral phosphorus coordination for the mercury atoms, very similar to that of the cadmium atoms in CdSnP₁₄. A brief literature survey shows that quite generally the mercury atoms have a smaller volume requirement than the cadmium atoms in intermetallics and more or less covalent compositions, in contrast to more ionic compounds, where the inverse relationship is observed. Chemical bonding in HgSnP₁₄ can be rationalized on the basis of the Zintl‐Klemm concept, resulting in the formula Hg⁺²Sn⁺²(P₁₄)^—4. Accordingly, the environment of the tin atoms shows the lone pair effect. Reactions of the elemental components aiming for the isotypic compounds CuSnP₁₄, CuPbP₁₄, AgSnP₁₄, AgPbP₁₄, AuSnP₁₄, and AuPbP₁₄ resulted in microcrystalline samples. The fibrous habit and the energy dispersive X‐ray fluorescence analyses of the products indicate the formation of these polyphosphides. Only for the gold‐tin compound was it possible to isolate a single crystal suitable for a structure refinement, which confirmed its HgPbP₁₄‐type structure: a = 1259.5(3) pm, b = 982.0(2) pm, c = 1056.2(3) pm, R = 0.046 for 1520 F values and 87 variables. The gold position was found with a lower occupancy, thus resulting in the two possible extreme formulas Au_0.852(4)SnP₁₄ and Au_0.64(1)Sn_1.36(1)P₁₄, depending of whether vacancies or a mixed Au/Sn occupancy is assumed for this position. An analysis of interatomic distances suggests the latter formula to be correct with tetravalent tin on the gold sites corresponding to the formula [(Au⁺¹)_0.64(1)(Sn⁺⁴)_0.36(1)]^+2.08(3)[SnP₁₄]^—2.     

A Mössbauer spectroscopy investigation of the Intergrowth Phases LaSr3Fe3−xMx010−δ (M = Al,Cu)

Iron-57 Mössbauer spectroscopy confirms a high sensitivity of the three-dimensional magnetic ordering temperature (T_Néel) for a series of new intergrowth phases to both oxygen stoichiometry and the partial substitution of iron by copper and aluminium in the Ruddlesden-Popper phase LaSr₃Fe₃0_10?δ. The chemical isomer shifts suggest that significant covalent electron delocalization exists in these phases. Spectra for the paramagnetic phases indicate two distinct iron coordination environments consistent with x-ray and neutron diffraction structure determinations. The Mössbauer spectra at 4.8 K exhibit the overlap of two magnetic hyperfine patterns corresponding to cooperative magnetic order at the iron sites with internal fields of 45 and 27 Tesla for nominal Fe³⁺ and Fe⁴⁺ sites respectively.     

Heteronuclear Nickel‐Iron Complexes and the Crystal Structure of [Fe2(CO)6(μ3‐S)2{Ni(dppe)}]

A series of heteronuclear nickel‐iron complexes [Fe₂(CO)₆(μ‐SH)(μ₃‐S){NiCl(PPh₃)₂}] ( 1 ), [Fe₂(CO)₆(μ‐SH)(μ₃‐S){NiCl(dppe)}] ( 2 ), [Fe₂(CO)₆(μ₃‐S)₂{Ni(PPh₃)₂}] ( 3 ), [Fe₂(CO)₆(μ₃‐S)₂{Ni(dppe)}] ( 4 ) and [Fe₂(CO)₆(μ‐SPh)(μ₃‐S){NiCl(dppe)}] ( 5 ) have been prepared. The structure of 4 has been determined by X‐ray crystallography. The central metal‐sulfur core of 4 has a trigonal bipyramidal shape with a NiFe₂ base plane with two axial sulfur atoms. Each iron atom is 5‐coordinate forming a distorted square pyramid; the nickel is square planar coordinated by two sulfur atoms and two phosphorus atoms.     

Hydrothermal Synthesis,Crystal Structure Determination,and Magnetic Properties of a New Calcium Iron Iridium Hydrogarnet Ca3(Ir2–xFex)(FeO4)2–x(O4H4)1+x with 0 ≤ x ≤ 1

The new calcium iron iridium hydrogarnet Ca₃(Ir_2–xFe_x)(FeO₄)_2–x(H₄O₄)_1+x (0 ≤ x ≤ 1) was obtained by hydrothermal synthesis under strongly oxidizing alkaline conditions. The compound adopts a garnet‐like crystal structure and crystallizes in the acentric cubic space group I4 3d (no. 220) with a = 12.5396(6) Å determined at T = 100 K for a crystal with a refined composition Ca₃(Ir_1.4Fe_0.6)(FeO₄)_1.4(O₄H₄)_1.6. Iridium and iron statistically occupy the octahedrally coordinated metal position, the two crystallographically independent tetrahedral sites are partially occupied by iron. Hydroxide groups are found to cluster as hydrogarnet defects, i.e. partially substituting oxide anions around the empty tetrahedral metal sites. The presence of hydroxide ions was confirmed by infrared spectroscopy and the hydrogen content was quantified by carrier gas hot extraction; the overall composition was verified by energy dispersive X‐ray spectroscopy. The structure model is supported by ⁵⁷Fe‐Mössbauer spectroscopic data evidencing different Fe sites and a magnetic ordering of the octahedral iron sublattice at room temperature. The thermal decomposition proceeds via three steps of water loss and results in Ca₂Fe₂O₅, Fe₂O₃ and Ir. Mössbauer and magnetization data suggest magnetic order at ambient temperature with complex magnetic interactions.     

Influence of the nacnac Ligand in Iron(I)‐Mediated P4 Transformations

A study of P₄ transformations at low‐valent iron is presented using β‐diketiminato (L) Fe^I complexes [LFe(tol)] (tol=toluene; L=L¹ ( 1 a ), L² ( 1 b ), L³ ( 1 c )) with different combinations of aromatic and backbone substituents at the ligand. The products [(LFe)₄(μ₄‐η²:η²:η²:η²‐P₈)] (L=L¹ ( 2 a ), L² ( 2 b )) containing a P₈ core were obtained by the reaction of 1 a,b with P₄ in toluene at room temperature. Using a slightly more sterically encumbered ligand in 1 c results in the formation of [(L³Fe)₂(μ‐η⁴:η⁴‐P₄)] ( 2 c ), possessing a cyclo‐P₄ moiety. Compounds 2 a – c were comprehensively characterized and their electronic structures investigated by SQUID magnetization and ⁵⁷Fe Mössbauer spectroscopy as well as by DFT methods.     

Fe4Si2Sn7O16: Eine Kombination von FeSn6-Oktaedern mit Schichten von (Fe3Sn)O6-Oktaedern; Präparation,Eigenschaften und Kristallstruktur [1]

Fe₄Si₂Sn₇O₁₆: A Combination of FeSn₆-Octahedra with Layers of (Fe₃Sn)O₆-Octahedra; Preparation, Properties, and Crystal Structure Fe₄Si₂Sn₇O₁₆ has been prepared by a solid state reaction at 900 °C from a mixture of Fe₂O₃, SnO₂, Sn, and Si. The compound is a paramagnetic semiconductor. Results of Mössbauer and suszeptibility measurements as well as bond length-bond strength calculations lead to the possible ionic formulation Fe₄²⁺Si₂⁴⁺Sn₁²⁺Sn₁⁴⁺O₁₆^2–. The compound crystallizes in the trigonal space group P3m1 (no. 164), with one formula unit per cell. Lattice parameters obtained by powder measurements are: a = 6.8243(6) Å, c = 9.1404(6) Å, γ = 120°, V = 368.6(1) ų. The structure consists of layers of edge linked oxygen octehedra exactly centered by Sn and Fe in the ratio 1 : 3. Three plains of isolated SiO₄ tetrahedra, FeSn₆ octahedra and again SiO₄ terahedra are inserted between two such layers. The layers are stacked along [001] and linked three-dimensionally by oxygen.     

Syntheses,Crystal Structure,and Properties of Hf2Ni2In,Hf2Ni2Sn,Hf2Cu2In,and Hf2Pd2In with Ordered Zr3Al2 Type Structure

Hf₂Ni₂In, Hf₂Ni₂Sn, Hf₂Cu₂In, and Hf₂Pd₂In were synthesized by reacting the elements in an arc-melting furnace under argon and subsequent annealing at 970 K. They crystallize with an ordered Zr₃Al₂ type structure, space group P4₂/mnm which was refined from single crystal X-ray data for Hf₂Ni₂In (a = 713.9(1) pm, c = 660.4(2) pm, wR2 = 0.0665, 513 F² values) and Hf₂Ni₂Sn (a = 703.1(1) pm, c = 676.1(2) pm, wR2 = 0.0423, 507 F² values) with 18 parameters for each refinement. The lattice constants for Hf₂Cu₂In and Hf₂Pd₂In are a = 715.5(1) pm, c = 677.0(1) pm and a = 742.6(1) pm, c = 679.4(2) pm, respectively. The structures may be considered as an intergrowth of distorted CsCl- and AlB₂-like slabs. Magnetic susceptibility measurements indicate Pauli paramagnetism for Hf₂Ni₂In and Hf₂Ni₂Sn, which is consistent with the metallic conductivity observed for Hf₂Ni₂In. ¹¹⁹Sn Mössbauer spectroscopy of Hf₂Ni₂Sn shows one signal with an isomer shift of δ = 1.59(1) mm/s subjected to quadrupole splitting of δE_q = 0.81(1) mm/s.     

Synthesis and characterization of La0.8Sr1.2Co0.5M0.5O4−δ (M=Fe, Mn)

The M⁴⁺-containing K₂NiF₄-type phases La_0.8Sr_1.2Co_0.5Fe_0.5O₄ and La_0.8Sr_1.2Co_0.5Mn_0.5O₄ have been synthesized by a sol–gel procedure and characterized by X-ray powder diffraction, thermal analysis, neutron powder diffraction and Mössbauer spectroscopy. Oxide ion vacancies are created in these materials via reduction of M⁴⁺ to M³⁺ and of Co³⁺ to Co²⁺. The vacancies are confined to the equatorial planes of the K₂NiF₄-type structure. A partial reduction of Mn³⁺ to Mn²⁺ also occurs to achieve the oxygen stoichiometry in La_0.8Sr_1.2Co_0.5Mn_0.5O_3.6. La_0.8Sr_1.2Co_0.5Fe_0.5O_3.65 contains Co²⁺ and Fe³⁺ ions which interact antiferromagnetically and result in noncollinear magnetic order consistent with the tetragonal symmetry. Competing ferromagnetic and antiferromagnetic interactions in La_0.8Sr_1.2Co_0.5Fe_0.5O₄, La_0.8Sr_1.2Co_0.5Mn_0.5O₄ and La_0.8Sr_1.2Co_0.5Mn_0.5O_3.6 induce spin glass properties in these phases.     

Solvothermal Synthesis and Characterization of the New Iron Thioantimonates(III) [Fe(C6H18N4)]FeSbS4 and [Fe(C4H13N3)2]Fe2Sb4S10 Containing FeII and FeIII and Protein‐Analogous [2FeIII‐2S]2+ Clusters

The two new compounds [Fe(tren)]FeSbS₄ ( 1 ) (tren = tris(2‐aminoethyl)amine) and [Fe(dien)₂]Fe₂Sb₄S₁₀ ( 2 ) (dien = diethylendiamine) were prepared under solvothermal conditions and represent the first thioantimonates(III) with iron cations integrated into the anionic network. In both compounds Fe³⁺ is part of a [2Fe^III‐2S] cluster which is often found in ferredoxines. In addition, Fe²⁺ ions are present which are surrounded by the organic ligands. In ( 1 ) the Fe²⁺ ion is also part of the thioantimonate(III) network whereas in ( 2 ) the Fe²⁺ ion is isolated. In both compounds the primary SbS₃ units are interconnected into one‐dimensional chains. The mixed‐valent character of [Fe(tren)]FeSbS₄ was unambiguously determined with Mössbauer spectroscopy. Both compounds exhibit paramagnetic behaviour and for ( 1 ) a deviation from linearity is observed due to a strong zero‐field splitting. Both compounds decompose in one single step.     

Reactions with Oleum under Harsh Conditions: Characterization of the Unique [M(S2O7)3]2− Ions (M=Si,Ge, Sn) in A2[M(S2O7)3] (A=NH4, Ag)

The reactions of group 14 tetrachlorides MCl₄ (M=Si, Ge, Sn) with oleum (65 % SO₃) at elevated temperatures lead to the unique complex ions [M(S₂O₇)₃]^2?, which show the central M atoms in coordination with three chelating S₂O₇^2? groups. The mean distances M? O within the anions increase from 175.6(2)–177.5(2) pm (M=Si) to 186.4(4)–187.7(4) pm (M=Ge) to 201.9(2)–203.5(2) pm (M=Sn). These distances are reproduced well by DFT calculations. The same calculations show an increasing positive charge for the central M atom in the row Si, Ge, Sn, which can be interpreted as the decreasing covalency of the M? O bonds. For the silicon compound (NH₄)₂[Si(S₂O₇)₃], ²⁹Si solid‐state NMR measurements have been performed, with the results showing a signal at ?215.5 ppm for (NH₄)₂[Si(S₂O₇)₃], which is in very good agreement with theoretical estimations. In addition, the vibrational modes within the [MO₆] skeleton have been monitored by Raman spectroscopy for selected examples, and are well reproduced by theory. The charge balance for the [M(S₂O₇)₃]^2? ions is achieved by monovalent A⁺ counter ions (A=NH₄, Ag), which are implemented in the syntheses in the form of their sulfates. The sizes of the A⁺ ions, that is, their coordination requirements, cause the crystallographic differences in the crystal structures, although the complex [M(S₂O₇)₃]^2? ions remain essentially unaffected with the different A⁺ ions. Furthermore, the nature of the A⁺ ions influences the thermal behavior of the compounds, which has been monitored for selected examples by thermogravimetric differential thermal analysis (DTA/TG) and XRD measurements.     

Synthese und Eigenschaften von Eisen(II)-Komplexen mit vier- und fünfzähnigen N,S-Chelatliganden. Kristallstruktur von [Fe(GBMA)py] · py (GBMA2− = Glyoxal-bis-(2-mercaptoanil))

Synthesis and Properties of Iron(II) Complexes with tetra- and pentadentate N,S-Chelate Ligands. Crystal Structure of [Fe(GBMA)py] · py (GBMA^2? = Glyoxal bis-(2-mercaptoanil)) The complexes glyoxal-bis-(2-mercaptoanil)iron(II) [Fe(GBMA)], diacetyl-bis-(2-mercaptoanil)iron(II), [Fe(DBMA)] and o-phthalaldehyde-bis-(2-mercaptoanil)iron(II) [Fe(PhBMA)] have been synthesized by reaction of the corresponding protonated ligands with anhydrous iron(II)-acetate. Pyridine-2,6-dialdehyde-bis-(2-mercaptoanil)iron(II), [Fe(PyBMA)] was obtained by a template synthesis with pyridine-2,6-dialdehyde, 2-aminothiophenol and iron(II)-acetate. Recrystallizing the complexes [Fe(GBMA)] and [Fe(DBMA)] from pyridine afforded [Fe(GBMA)py] · py and [Fe(DBMA)py] · py. For all complexes the magnetic properties have been determined, and the Mössbauer spectra were recorded at 82 K. Compounds [Fe(GBMA)] and [Fe(DBMA)] show quasi reversible redox properties in the cyclovoltammogram, while for [Fe(PhBMA)] an irreversible oxidation was observed. [Fe(GBMA)py] · py crystallizes in the monoclinic space group P2₁ with a = 1288.7(1), b = 1242.63(5), c = 1396.0(1) pm, β = 98.24(1)°, and Z = 4. In the neutral complex the Fe atom has a square pyramidal coordination with the pyridine nitrogen atom in apical position. The basal plane is formed by two nitrogen and two sulfur atoms of the ligand GBMA^2?. The iron is located 40 pm above the pyramidal base. Its average distances to the donor atoms of the GBMA ligand are Fe? N = 190 pm, and Fe? S = 222 pm, while the distance to the nitrogen atom of the coordinated pyridine molecule is 207 pm.