Neue Rhodiumverbindungen mit LiCo6P4‐Struktur

New Rhodium Compounds with the LiCo₆P₄ Type Structure Five new phosphides and arsenides respectively of the formula ARh₆X₄ (A: Mg–Sr, Yb; X: P, As) were prepared by heating mixtures of the elements and investigated by means of single crystal X‐ray methods. They are isotypic and crystallize in the LiCo₆P₄ type structure (P6m2; Z = 1) (lattice constants see ”︁Inhaltsübersicht”︁”︁). The compounds belong to the large family of phosphides and arsenides, which have a metal : non‐metal ratio of about 2 : 1. Their structures are characterized by the environment of phosphorus and arsenic respectively, which is composed of trigonal prisms of metal atoms with additional metal atoms capping the rectangular faces of the prisms.     

Neue thermische Abbauprodukte von Ln2CeMO6Cl3 (M = Nb,Ta; Ln = La–Sm) – Darstellung von strukturverwandtem (La, Tb)3,5TaO6Cl4–x

Contributions on the Investigation of Inorganic Nonstoichiometric Compounds. XLV. New Thermal Decomposition Products of Ln₂CeMO₆Cl₃ – Preparation of Structure‐related (La, Tb)_3.5TaO₆Cl_4–x The thermal decomposition (T £ 900–1050°C) of Ln₂CeMO₆Cl₃ (M = Nb, Ta; Ln = La, Ce, Pr, Nd, Sm) leads to the formation of two mixed‐valenced phases (Ln, Ce)_3.25MO₆Cl_3.5–x (phase ‘‘AB”︁”︁) and (Ln, Ce)_3.5MO₆Cl_4–x (phase ‘‘BB”︁”︁) and to the formation of chlorine according to redox‐reactions between Ce⁴⁺ and Cl^–. Single crystals of both phases (Ln, Ce)_3.25MO₆Cl_3.5–x (‘‘AB”︁”︁) and (Ln, Ce)_3.5MO₆Cl_4–x (‘‘BB”︁”︁) were obtained by chemical transport reactions using both powder of Ln₂CeMO₆Cl₃ (phase ‘‘A”︁”︁) and powder of (Ln, Ce)_3.25MO₆Cl_3.5–x (phase ‘‘AB”︁”︁) as starting materials and chlorine (p{Cl₂; 298 K} = 1 atm) or HCl (p{HCl; 298 K} = 1 atm) as transport agent. A crystal of (La, Ce)_3.25NbO₆Cl_3.5–x (”︁AB”︁”︁) (space group: C2/m, a = 35.288(1) Å, b = 5.418(5) Å, c = 9.522(1) Å, β = 98.95(7)°, Z = 4) was investigated by x‐ray diffraction methods, a crystal of (Pr, Ce)_3.5NbO₆Cl_4–x (”︁BB”︁”︁) was investigated by synchrotron radiation (λ = 0.56 Å) diffraction methods. The lattice constants are a = 18.863(6) Å, b = 5.454(5) Å, c = 9.527(6) Å, β = 102.44(3)° and Z = 4. Structure determination in the space group C2/m (No. 12) let to R1 = 0.0313. Main building units are NbO₆‐polyhedra with slightly distorted trigonally prismatic environment for Nb and chains of face‐sharing Cl₆‐octahedra along [010]. The rare earth ions are coordinated by chlorine and oxygen atoms. These main structure features confirmed the expected relation to the starting material Ln₂CeMO₆Cl₃ (phase ”︁A”︁”︁) and to (Ln, Ce)_3.25MO₆Cl_3.5–x (phase ”︁AB”︁”︁).     

AM2X2-Verbindungen mit CaAl2Si2-Struktur. XI. Struktur und Eigenschaften der Verbindungen ACd2X2 (A: Eu,Yb; X: P,As, Sb)

AM₂X₂ Compounds with the CaAl₂Si₂-Type Structure. XI. Structure and Properties of ACd₂X₂ (A: Eu, Yb; X: P, As, Sb) EuCd₂P₂, EuCd₂As₂, EuCd₂Sb₂, YbCd₂As₂, and YbCd₂Sb₂ were prepared by heating mixtures of the elements and investigated by means of single-crystal X-ray methods. The compounds are isotypic (lattice constants see “Inhaltsübersicht”) and crystallize in the CaAl₂Si₂-type structure (P3 m1; Z = 1). Magnetic measurements showed, that Eu is divalent and that the compounds order magnetically at low temperatures.     

Über den Einfluß von Temperatur,Druck und Substitution auf die Kristallstruktur von ARh2P2 (A = Ca,Sr, Eu,Ba)

About the Effect of Temperature, Pressure, and Substitution on the Crystal Structure of ARh₂P₂ (A = Ca, Sr, Eu, Ba) Four compounds ARh₂P₂ (A = Ca, Sr, Eu, Ba) were prepared by heating mixtures of the elements and investigated by means of single crystal X-ray methods. They crystallize in the ThCr₂Si₂ type structure (I4/mmm; Z = 2) with P? P distances along [001] reaching from 2.26 Å (CaRh₂P₂) to 3.74 Å (BaRh₂P₂). With increasing temperature (EuRh₂P₂) or increasing pressure (SrRh₂P₂) a first order phase transition occurs with strong changes of the P? P distances. Substitution of the atoms changes the bond lengths of the compounds too.     

Darstellung,Kristallstrukturen und Schwingungsspektren neuer ternärer Verbindungen mit dem Anion [N–B–N]3–

Ternary Nitridoborates. 2. Synthesis, Crystal Structure, and Vibrational Spectra of New Ternary Compounds with the [N–B–N]^3– Anion The isotypic compounds LiM₄[BN₂]₃ (M = Ca, Sr, Ba, Eu) and NaM₄[BN₂]₃ (M = Sr, Ba) are formed as colorless to pale yellow prismatic crystals (black with Eu) by reaction of the binary components Li₃N, M₃N₂, EuN and Na, NaN₃, Ba₃N₂ and BN in sealed niobium ampoules at 1375 and 1275 K, respectively. The linear anions [N–B–N]^3– have bond lengths d(B–N) between 132.6 and 136.6 pm. Vibrational frequencies and force constants f(B–N) = 7.25–7.89 Ncm^–1 reveal significant drifts related to bond length and effective anionic charge. The cubic crystal structures (Im3m (No. 229), Z = 2; LiM₄[BN₂]₃: a(Ca) = 711.5 pm; a(Sr) = 745.6 pm; a(Eu) = 742.5 pm, a(Ba) = 788.0 pm and NaM₄[BN₂] ${}_{\text{3}\text{: a(Sr) = 756.8 pm; a(Ba) = 791.7 pm)) are stuffed derivatives of the β‐PtHg4}}$ structure type, and the range of existence of this cubic structure is derived from the molar volume and the ionic radii. The cations form a partial structure of centered cubes E1(E2)₈ which are condensed to a [E1(E2)_8/2] network (E1 = Li, Na; E2 = Ca, Sr, Ba, Eu). The remaining open cubes are filled by the [BN₂]^3– anions yielding two interpenetrating [E1(BN₂)_6/2] networks. Periodic Nodal Surfaces (PNS) of Im3m symmetry show the regions of different interactions.     

Synthese und Kristallstruktur von Ti12Sn3O10 – einem niedervalenten Oxid des Titans mit oxidischem Gerüst und intermetallischen „Inseln”︁

Synthesis and Crystal Structure of Ti₁₂Sn₃O₁₀ – a Low Valent Oxide of Titanium with an Oxidic Network and Intermetallic ”︁Islands”︁”︁ The new ternary compound Ti₁₂Sn₃O₁₀ is obtained by the reaction of Ti, TiO₂ and Sn at 1500 °C. According to the single crystal structure analysis (cubic, space group Fm3m, a = 13.5652(9) Å, Z = 8, wR₂(I) = 0.048, R₁(F) = 0.020) the air stable compound represents a new structure type combining structural features of oxides and intermetallics. While tin is surrounded only by titanium the five different Ti atoms have oxidic and metallic coordination spheres as well, explaining the quite low averaged oxidation number. The crystal structure is characterized by a threedimensional net of Ti₄O‐tetrahedra and trigonal bipyramides Ti₅O. In the voids there are intermetallic ”︁islands”︁”︁ of a composition Ti₃₃Sn₆ with a diameter of about 10 Å.     

Synthese und Kristallstrukturen von [Cu4(As4Ph4)2(PRR′2)4], [Cu14(AsPh)6(SCN)2(PEt2Ph)8], [Cu14(AsPh)6Cl2(PRR′2)8], [Cu12(AsPh)6(PPh3)6], [Cu10(AsPh)4Cl2(PMe3)8], [Cu12(AsSiMe3)6(PRR′2)6] und [Cu8(AsSiMe3)4(PtBu3)4] (R,R′ = organische Gruppen)

Syntheses and Crystal Structures of [Cu₄(As₄Ph₄)₂(PRR′₂)₄], [Cu₁₄(AsPh)₆(SCN)₂(PEt₂Ph)₈], [Cu₁₄(AsPh)₆Cl₂(PRR′₂)₈], [Cu₁₂(AsPh)₆(PPh₃)₆], [Cu₁₀(AsPh)₄Cl₂(PMe₃)₈], [Cu₁₂(AsSiMe₃)₆(PRR′₂)₆], and [Cu₈(AsSiMe₃)₄(P^tBu₃)₄] (R, R′ = Organic Groups) Through the reaction of CuSCN with AsPh(SiMe₃)₂ in the presence of tertiary phosphines the compounds [Cu₄(As₄Ph₄)₂(PRR′₂)₄] ( 1 – 3 ) ( 1 : R = R′ = ⁿPr, 2 : R = R′ = Et; 3 : R = Me, R′ = ⁿPr) and [Cu₁₄(AsPh)₆(SCN)₂(PEt₂Ph)₈] ( 4 ) can be synthesised. Using CuCl instead of CuSCN results to the cluster complexes [Cu₁₄(AsPh)₆Cl₂(PRR′₂)₈] ( 5–6 ) ( 5 : R = R′ = Et; 6 : R = Me, R′ = ⁿPr), [Cu₁₂(AsPh)₆(PPh₃)₆] ( 7 ) and [Cu₁₀(AsPh)₄Cl₂(PMe₃)₈] ( 8 ). Through reactions of CuOAc with As(SiMe₃)₃ in the presence of tertiary phosphines the compounds [Cu₁₂(AsSiMe₃)₆(PRR′₂)₆] ( 9 – 11 ) ( 9 : R = R′ = Et; 10 : R = Ph, R′ = Et; 11 : R = Et, R′ = Ph) and [Cu₈(AsSiMe₃)₄(P^tBu₃)₄] ( 12 ) can be obtained. In each case the products were characterised by single‐crystal‐X‐ray‐structure‐analyses. As the main structure element 1 – 3 each have two As₄Ph₄^2–‐chains as ligands. In contrast 4 – 12 contain discrete AsR^2–ligands.     

Tl2CuAsO4 – ein Zwischenprodukt bei der Oxidation von Tl/Cu/As-Legierungen im Sauerstoffstrom

Tl₂CuAsO₄ – an Intermediate Phase in the Oxidation of Tl/Cu/As Alloys with Oxygen Waxy, honey-jellow single crystals of the new compound Tl₂CuAsO₄ (monoclinic, P2₁/c, a = 860.1(1) pm, b = 533.94(7) pm, c = 1200.1(2) pm, β = 98.10(1)°, Z = 4) were prepared as an intermediate product of the oxidation process in the reaction of Tl/Cu/As-alloys with oxygen. Their structure was determined from IPDS data (w2R = 0.071 for 1271 F² values and 74 parameters). The structure contains an isolated [Cu₂As₂O₈]^4– group consisting of two AsO₄-tetrahedra connected by two Cu⁺ ions with an approximately linear O–Cu–O coordination. The [Cu₂As₂O₈]^4– groups are linked to a threedimensional framework by thallium(I) ions which show an hemispheric coordination sphere of oxygen ions indicating the stereochemical activity of the Tl⁺ lone pair.     

Synthesis and Structural Characterization of Six Pentanuclear and Tetranuclear Mo/W‐Cu‐S Clusters with Bis(diphenylphosphanyl) Methane

Six heterothiometalic clusters, namely, [WS₄Cu₄(dppm)₄](ClO₄)₂ · 2DMF · MeCN ( 1 ), [MoS₄Cu₄(dppm)₄](NO₃)₂ · MeCN ( 2 ) [MoS₄Cu₃(dppm)₃](ClO₄) · 4H₂O ( 3 ), [WS₄Cu₃(dppm)₃](NO₃) · 4H₂O ( 4 ), [WS₄Cu₃(dppm)₃]SCN · CH₂Cl₂ ( 5 ), and [WS₄Cu₃(dppm)₃]I · CH₂Cl₂ ( 6 ) [dppm = bis (diphenylphosphanyl)methane] were synthesized. Compounds 1 – 4 were obtained by the reactions of (NH₄)₂MS₄ (M = Mo, W) with [Cu₂(μ₂‐dppm)₂(MeCN)₂(ClO₄)₂] {or [Cu(dppm)(NO₃)]₂} in the presence of 1,10‐phen in mixed solvent (CH₃CN/CH₂Cl₂/DMF for 1 and 2 , CH₂Cl₂/CH₃OH/DMF for 3 and 4 . Compounds 5 and 6 were obtained by one‐pot reactions of (NH₄)₂WS₄ with dppm and CuSCN (or CuI) in CH₂Cl₂/CH₃OH. These clusters were characterized by single‐crystal X‐ray diffraction as well as IR, ¹H NMR, and ³¹P NMR spectroscopy. Structure analysis showed that compounds 1 and 2 are “saddle‐shaped” pentanuclear cationic clusters, whereas compounds 3 – 6 are “flywheel‐shaped” tetranuclear cationic clusters. In 1 and 2 , the MS₄^2– unit (M = W, Mo) is coordinated by four copper atoms, which are further bridged by four dppm molecules. In compounds 3 – 6 , the MS₄^2– unit is coordinated by three copper atoms and each copper atom is bridged by three dppm ligands.     

M(SCN)2 (M = Eu,Sr, Ba): Kristallstruktur,thermisches Verhalten,Schwingungsspektroskopie

M(SCN)₂ (M = Eu, Sr, Ba): Crystal Structure, Thermal Behaviour, Vibrational Spectroscopy Single crystals of M(SCN)₂ (M = Eu, Sr, Ba) have been obtained via metathesis of NaSCN and MCl₂ (M = Eu, Sr, Ba) at 340 °C. The isotypic crystal structures of the thiocyanates M(SCN)₂ (C2/c, Z = 4, Eu: a = 979.3(2), b = 660.8(1), c = 815.7(2) pm, β = 91.58(3)°, R_all = 0.0245, Sr: a = 985.5(2), b = 662.9(2), c = 819.6(2) pm, β = 91.29(3)°, R_all = 0.0435, Ba: a = 1018.8(2), b = 687.2(1), c = 852.2(1) pm, β = 92.43(2)°, R_all = 0.0392) contain alternating layers of M²⁺ and SCN^–. According to M(SCN)_4/4(NCS)_4/4 M²⁺ is eight‐coordinated by four sulfur and four nitrogen atoms forming a square antiprism. Thermal investigations show that the compounds melt without decomposition. Vibrational spectroscopic investigations are presented and discussed.     

Cu1,45Er0,85S2: Ein Kupfer(I)‐Erbium(III)‐Sulfid mit kationendefekter CaAl2Si2‐Struktur

Cu_1.45Er_0.85S₂: A Copper(I) Erbium(III) Sulfide with Cation‐Deficient CaAl₂Si₂‐Type Structure Attempts to synthesize single‐phase CuYS₂‐type copper(I) erbium(III) disulfide (CuErS₂) from 1 : 1 : 2‐molar mixtures of the elements (Cu, Er and S) after seven days at 900 °C in sealed evacuated silica tubes failed with equimolar amounts of CsCl working as flux and reagent. In these cases, quaternary CsCu₃Er₂S₅ (orthorhombic, Cmcm; a = 394.82(4), b = 1410.9(1), c = 1667.2(2) pm, Z = 4) and ternary Cu_1.45Er_0.85S₂ (trigonal, P3m1; a = 389.51(4), c = 627.14(6) pm, Z = 1) become the unexpected by‐products. Both emerge even as yellow single crystals (lath‐shaped fibres and platelets, respectively, with triangular cross‐section) and both crystal structures contain condensed [CuS₄] and [ErS₆] units as dominating building blocks. The ternary sulfide Cu_1.45Er_0.85S₂ exhibits CdI₂‐analogous layers {[(Er³⁺)(S^2–)_6/3]^–} of edge‐shared [ErS₆] octahedra (d(Er–S) = 272 pm, 6 × ) which are piled up parallel (001) and interconnected by interstitial Cu⁺ cations in tetrahedral S^2– coordination (d(Cu–S) = 236 pm, 1 × ; 240 pm, 3 × ). The latter thereby form anionic layers {([(Cu⁺)(S^2–)_4/4]^–)₂} as well, consisting of [CuS₄] tetrahedra which share three cis‐oriented edges. When the S^2– anions arrange hexagonally closest‐packed and the corresponding layers are symbolized with capital Roman letters, the Er³⁺ cations (small Roman) and the Cu⁺ cations (small Greek letters) reside layerwise alternatingly within half of the octahedral (Er³⁺) and tetrahedral (Cu⁺) voids according to … AcB αβ AcB αβ A … . Since both kinds of cations occupy only a certain percentage (Cu⁺: 72.6%, Er³⁺: 85.1%) of their regular positions, the crystal structure of Cu_1.45Er_0.85S₂ can be addressed as a double cation‐deficient CaAl₂Si₂‐type arrangement according to (Er_0.85□_0.15)(Cu_1.45□_0.55)S₂. The partial occupation could be established by both released site occupation factors in the course of the crystal structure refinement and electron beam X‐ray microanalysis (EDX).     

Darstellung,Kristallstruktur und Eigenschaften des Kupfer(II)‐Indium(III)‐Orthophosphats Cu3In2[PO4]4

Contributions on Crystal Chemistry and Thermal Behaviour of Anhydrous Phosphates. XXIV. Preparation, Crystal Structure, and Properties of Copper(II) Indium(III) Orthophosphate Cu₃In₂[PO₄]₄ Crystals of Cu₃In₂[PO₄]₄ were grown by chemical vapour transport (temperature gradient 1273 K → 1173 K) using chlorine as transport agent. The mixed metal phosphate forms a new structure type (P2₁/c, Z = 2, a = 8.9067(6), b = 8.8271(5), c = 7.8815(5) Å, β = 108.393(5)°, 13 atoms in asymmetric unit, 2549 unique reflections with F_o > 4σ, 116 variables, R(F²) = 0.065). The crystal structure shows a hexagonal closest packing of [PO₄]^3– tetrahedra. Close‐packed layers parallel (1 0 –1) are stacked according to the sequence A, B, A′, B′, A. The octahedral interstices in this packing are completely occupied by two In³⁺, one (Cu1)²⁺ and a “dumb bell” (Cu2)₂⁴⁺. In the latter case four of the six phosphate groups that belong to this octahedral void act as bi‐dentate ligands, thus forming dimers [(Cu2)₂O₁₀] with d_Cu–Cu = 3.032 Å. Cu₃In₂[PO₄]₄ is paramagnetic (μ_eff = 1.89 μ_B, θ_P = –16.9 K). The infrared and UV/Vis reflectance spectra are reported. The observed d‐electron levels of the Cu²⁺ cations agree well with those obtained from angular overlap calculations.     

Darstellung und Struktur von Tetraethylcyclotetraarsoxan-Komplexen von Kupfer(I)-Halogeniden

Preparation and Structure of Tetraethylcyclotetraarsoxane Complexes of Copper(I) Halides The polymeric complexes [Cu₄Cl₄{cyclo-(C₂H₅AsO)₄}₃]_n ( 1 ), [Cu₃Br₃{cyclo-(C₂H₅AsO)₄}₂]_n ( 2 ) and [Cu₆I₆{cyclo-(C₂H₅AsO)₄}₃]_n ( 3 ) were prepared by the reaction of (C₂H₅AsO)_n and CuX (X = Cl, Br, I) in acetonitrile and characterised by X-ray analysis. All three complexes contain only tetramers (C₂H₅AsO)₄ as ligands, in which the As₄O₄ ring systems coordinate between two and four Cu-atoms. In each case one As₄O₄ ring with a crown-shaped conformation is observed, which coordinates either four (in 1 ) or three (in 2 and 3 ) axially sited Cu-atoms. In addition there are further (C₂H₅AsO)₄ ligands, which display either a boat-chair- (in 1 ) or a twist-chair-conformation (in 1–3 ). The individual building units are connected to one another via Cu? X? Cu bridges (in 2 and 3 ) and/or centrosymmetric As₄O₄ ring systems (in 1–3 ) into chain ( 1 ) or layer structures ( 2 und 3 ).     

Kristallstrukturen und chemische Bindung von AM2GeSe4 (A = Sr,Ba; M = Cu,Ag)

New Noncentrosymmetric Selenogermanates. I. Crystal Structures and Chemical Bonding of AM ₂GeSe₄ ( A = Sr, Ba; M = Cu, Ag) Three new quaternary selenogermanates were synthesized by heating the elements at 983–1073 K. Their crystal structures were determined by single crystal X‐ray methods. The dark red semiconductors crystallize in noncentrosymmetric space groups. SrCu₂GeSe₄ (Ama2, a = 10.807(4) Å, b = 10.735(4) Å, c = 6.541(2) Å, Z = 4) forms a new structure type, whereas BaCu₂GeSe₄ (P3₁, a = 6.490(1) Å, c = 16.355(3) Å, Z = 3) and BaAg₂GeSe₄ (I222, a = 7.058(1) Å, b = 7.263(1) Å, c = 8.253(2) Å, Z = 2) crystallize in structures known from thiostannates. Main structural features are almost regular GeSe₄‐, but distorted CuSe₄‐ or AgSe₄‐tetrahedra sharing corners or edges. Eight selenium atoms coordinate the alkaline earth atoms in the voids of these three dimensional tetrahedral networks. Chemical bonding and the electronic structure are elucidated by self‐consistent band structure calculations and the COHP method. The electron density and the electron localization function ELF of SrCu₂GeSe₄ reveal a significant stronger covalent character for the Ge–Se bonds compared with the Cu–Se bonds. For this reason the GeSe₄ tetrahedra appear as quasi molecular entities, arranged spatially according to the motifs of closest packing. The metal atoms occupy the tetrahedral and octahedral voids of these “tetrahedra packing”. This concept allows to derive the structures of AM₂GeSe₄‐compounds from simple binary structure types as Li₃Bi or Ni₂In.     

Crystal Structure and Properties of Some Filled and Unfilled Skutterudites: GdFe4P12, SmFe4P12, NdFe4As12, Eu0.54Co4Sb12, Fe0.5Ni0.5P3, CoP3, and NiP3

The new cubic compound Fe_0.5Ni_0.5P₃ (a = 775.29(5) pm) as well as the known compounds CoP₃ and NiP₃ were synthesized from the elemental components using tin as a flux. Their skutterudite (CoAs₃) type structures were refined from single‐crystal X‐ray data. The new compound GdFe₄P₁₂ was prepared by reaction of an alloy Gd_1/3Fe_2/3 with phosphorus in a tin flux. Its cubic “filled” skutterudite (LaFe₄P₁₂ type) structure was refined from single‐crystal X‐ray data: a = 779.49(4) pm, R = 0.019 for 304 structure factors and 11 variable parameters. SmFe₄P₁₂ shows Van Vleck paramagnetism while GdFe₄P₁₂ is a soft ferromagnet with a Curie temperature of T_C = 22(5) K. Both are metallic conductors. The new isotypic polyarsenide NdFe₄As₁₂ (a = 830.9(1) pm) was obtained by reacting NdAs₂ with iron and arsenic in the presence of a NaCl/KCl flux. The new isotypic polyantimonide Eu_0.54(1)Co₄Sb₁₂ (a = 909.41(8) pm) was prepared by reaction of EuSb₂ with cobalt and antimony. Its structure was refined from single‐crystal X‐ray data to a residual of 0.024 (137 F values, 12 variables). A comparison of the Fe–P and P–P bond lengths in the compounds AFe₄P₁₂, where the A atoms (A = Ce, Eu, Gd, Th) have differing valencies, suggests that the Fermi level cuts through Fe–P bonding and P–P antibonding bands.     

ACu9X4 ‐ Neue Verbindungen mit der CeNi8, 5Si4, 5‐Struktur (A: Sr,Ba; X: Si,Ge)

ACu₉X₄ ‐ New Compounds with CeNi_{8, 5}Si_{4, 5} Structure (A: Sr, Ba; X: Si, Ge) The new compounds SrCu₉Si₄ (a = 8.146(1), c = 11.629(2)Å), BaCu₉Si₄ (a = 8.198(2), c = 11.735(2)Å), SrCu₉Ge₄ (a = 8.273(2), c = 11.909(5)Å), and BaCu₉Ge₄ (a = 8.338(4), c = 12.011(7)Å) are formed by reaction of the elements at 1000° ‐ 1100 °C. They are isotypic (I4/mcm, Z = 4) and crystallize in an ordered variant of the cubic NaZn₁₃ type structure, also built up by the binary phase BaCu₁₃. In the ternary compounds the positions of Cu2 are orderly occupied by copper and silicon and germanium, respectively. This results in a lowering of symmetry and a distortion of the polyhedra. The metallic conductivity of the compounds was confirmed by measurements on BaCu₉Si₄.     

Reactivity in the System Copper/Arsenic/Sulfur II. The Formation of CuAsS, (Lautite)

The reaction pathways during the synthesis of CuAsS have been studied with the DTA in the range 25 — 810 °C with a heating rate of 10 K/min. Educts, intermediates, and products were characterized by X‐ray diffraction at room and elevated temperatures. Educts were the corresponding elements and the binary compounds As₄S₄, As₂S₃, Cu_3—xAs, Cu_5—δAs₂, Cu₂S, and CuS. The 13 examined educt mixtures can be divided into four groups specified by their thermal effects observed during the reaction. Mixtures of group I contain copper arsenides and arsenic sulfides, those of group II and III arsenic and copper sulfides, and arsenic sulfides and copper, respectively. Group IV includes mixtures showing individual reactions. In all cases the reaction to CuAsS proceeds stepwise. The reaction is not completed at 574 °C, the decomposition temperature of CuAsS, because the product is still associated with Cu_12+xAs_4+yS₁₃ , As, and to a lesser amount with Cu_1.81S. Nevertheless, a consecutive run in which the samples were heated above the liquidus temperature shows no exothermic reaction effect. When the mixtures were cooled at 10 K/min after the runs, no CuAsS was found in the X‐ray experiments. Only Cu_12+xAs_4+yS₁₃ and As were then observed.     

Zur Abgrenzung der PbFCl‐ und Cu2Sb‐Strukturfamilien: Neubestimmung und Verfeinerung der Kristallstrukturen von CuMgSb,Cu2Sb und CuMgAs

Demarcation of the PbFCl and Cu₂Sb Structure Families: Crystal Structure Re‐Determinations and Refinements of CuMgSb, Cu₂Sb, and CuMgAs The crystal structures of CuMgSb, Cu₂Sb, and CuMgAs have been re‐determined and refined from single crystal data, and the structural relationship between CuMgSb (cubic), Cu₂Sb (tetragonal) and CuMgAs (orthorhombic) is discussed in detail. CuMgAs does not crystallize in the Cu₂Sb type, as assumed until now; but in a new structure type oP24 (Pnma; Z = 8): a = 1346.0(1) pm, b = 395.40(3) pm, c = 739.58(6) pm. The structure is related to Cu₂Sb and can be derived from it following the principle of ′chemical twinning′. The re‐determined parameters of Cu₂Sb are included in a structure field diagram together with additional representatives of the PbFCl type. The structure field can be devided into three regions with the prototypes PbFCl, Cu₂Sb, and Fe₂As, respectively. The assignment can be related to the predominant type of bonding of each structure.     

Assemblies of 1D and 2D Copper(II) Chiral Coordination Polymers by Salicylaldehyde Schiff Bases: Synthesis,Crystal Structures,and Magnetic Properties

Reaction of CuCl₂ · 2H₂O with chiral Schiff bases and sodium dicyanamide led to the formation of two chiral copper(II) coordination polymers, namely [Cu₄(L¹)₂(dca)₄]_n ( 1 ) and [Cu₂(L²)(μ‐Cl)(dca)(H₂O)]_n · nH₂O ( 2 ) {H₂L¹ = (1R, 3S)‐N′,N′′‐bis[salicylidene]‐1,3‐diamino‐ 1,2,2‐trimethylcyclopentane, H₂L² = (1R, 3S)‐N′,N′′‐bis[3‐ethoxysalicylidene]‐1,3‐diamino‐ 1,2,2‐trimethylcyclopentane, dca = dicyanamide}. Both complexes were structurally characterized by elemental analyses, IR spectroscopy and single‐crystal X‐ray diffraction. Complex 1 exhibits a two‐dimensional polymeric structure formed by single dca bridging tetranuclear Cu₄ units. Complex 2 displays a left‐handed helical chain structure constructed from Cu₂ dimers with single dca bridges. The chirality of 1 and 2 was confirmed by circular dichroism (CD) measurements in solution. Both complexes exhibit strong antiferromagnetic couplings with J = –308(4) cm^–1 for 1 and J = –123(1) cm^–1 for 2 in 2–300 K.