The Unique Crystal Structure of the Triclinic Samarium(III) Oxoselenate(IV) Sm2[SeO3]3

Pale yellow, needle‐shaped single crystals of Sm₂[SeO₃]₃ were obtained by heating stoichiometric mixtures of Sm₂O₃ and SeO₂ (molar ratio: 1:3) along with substantial amounts of CsCl as fluxing agent in evacuated sealed silica tubes at 830 °C for one week. According to X‐ray single‐crystal diffraction data, Sm₂[SeO₃]₃ crystallizes triclinic (space group: ) with two formula units per unit cell of the dimensions a = 698.62(7), b = 789.71(8), c = 910.34(9) pm, α = 96.693(5), β = 104.639(5), γ = 115.867(5)°. Its crystal structure contains two crystallographically distinct Sm³⁺ cations in eight‐ and ninefold coordination with oxygen atoms arranged as distorted uncapped or capped square antiprisms (d(Sm³⁺?O^2?) = 232?271 pm). These [(Sm1)O₈] and [(Sm2)O₉] polyhedra share opposite edges and faces to form zigzag chains along [100] with discrete pyramidal [SeO₃]^2? anions bridging units. Further linkage by [SeO₃]^2? anions in [010] direction leads to a three‐dimensional network, which exhibits almost rectangular channels along [111]. These tunnels offer width enough to incorporate the free non‐bonding electron pairs (?lone pairs”?) at the Se⁴⁺ cations, since all nine different Ψ¹‐tetrahedral [SeO₃]^2? groups (d(Se⁴⁺?O^2?) = 165?173 pm, ?(O–Se–O) = 94 – 108°) exhibit a pronounced stereochemical ?lone‐pair”? activity. For not being isotypic with neither triclinic Er₂[SeO₃]₃ (CN(Er³⁺) = 7 and 8) nor the remainder rare‐earth metal(III) oxoselenates(IV) of the composition M₂[SeO₃]₃ (≡ M₂Se₃O₉; M = Sc, Y, La, Ce – Lu), Sm₂[SeO₃]₃ claims a unique crystal structure among them.     

Synthesis and Crystal Structure of Pb3O2(SeO3)

Single crystals of Pb₃O₂(SeO₃) have been prepared hydrothermally at 230 °C. The structure (orthorhombic, Cmc2₁, a = 10.529(2), b = 10.722(2), c = 5.7527(12)Å, V = 649.5(2)ų) has been solved by direct methods and refined to R₁ = 0.059 on the basis of 615 unique observed reflections (|F_o| = 4σ_F). The structure is based upon double [O₂Pb₃]²⁺ chains of edge‐sharing [OPb₄]⁶⁺ tetrahedra. These [O₂Pb₃]²⁺ chains run parallel to [001], and their planes are parallel to (010). The pyramidal (SeO₃)^2— anions are located between the chains; their triangular oxygen atom bases lie parallel to (001) and all (SeO₃)^2— groups are pointing in the same direction. A short compilation of [O₂M₃] chains of oxocentred M₄ tetrahedra in minerals and inorganic compounds is provided.     

Ce2[SeO3]3 and Pr2[SeO3]3: Non‐Isostructural Oxoselenates(IV) of the Light Lanthanoids

The crystal structures of Ce₂[SeO₃]₃ and Pr₂[SeO₃]₃ have been refined from X‐ray single‐crystal diffraction data. The compounds were obtained using stoichiometric mixtures of CeO₂, SeO₂, Ce, and CeCl₃ (molar ratio 3:3:1:1) or Pr₆O₁₁, SeO₂, Pr, and PrCl₃ (molar ratio 3:27:1:2) heated in evacuated sealed silica tubes at 830 °C for one week. Ce₂[SeO₃]₃ crystallizes orthorhombically (space group: Pnma), with four formula units per unit cell of the dimensions a = 839.23(5) pm, b = 1421.12(9) pm, and c = 704.58(4) pm. Its structure contains only a single crystallographically unique Ce³⁺ cation in tenfold coordination with oxygen atoms arranged as single‐face bicapped square antiprism and two different trigonal pyramidal [SeO₃]^2? groups. The connectivity among the [CeO₁₀] polyhedra results in infinite sheets of face‐ and edge‐sharing units propagating normal to [001]. Pr₂[SeO₃]₃ is monoclinic (space group: P2₁/n) with twelve formula units per unit cell of the dimensions a = 1683.76(9) pm, b = 705.38(4) pm, c = 2167.19(12) pm, and β = 102.063(7)°. Its structure exhibits six crystallographically distinct Pr³⁺ cations in nine‐ and tenfold coordination with oxygen atoms forming distorted capped square antiprisms or prisms (CN = 9), bicapped square antiprisms and tetracapped trigonal prisms (CN = 10), respectively. The [PrO₉] and [PrO₁₀] polyhedra form double layers parallel to (111) by edge‐ or face‐sharing, which are linked by nine different [SeO₃]^2? groups to build up a three‐dimensional framework. In both compounds, the discrete [SeO₃]^2? anions (d(Se⁴⁺–O^2?) = 166–174 pm) show the typical Ψ¹‐tetrahedral shape owing to the non‐bonding “lone‐pair” electrons at the central selenium(IV) particles. Moreover, their stereochemical “lone‐pair” activity seems to flock together in large empty channels running along [010] in the orthorhombic Ce₂[SeO₃]₃ and along [101] in the monoclinic Pr₂[SeO₃]₃ structure, respectively.     

CoSm(SeO3)2Cl,CuGd(SeO3)2Cl,MnSm(SeO3)2Cl,CuGd2(SeO3)4 und CuSm2(SeO3)4: Übergangsmetallhaltige Selenite von Samarium und Gadolinum

CoSm(SeO₃)₂Cl, CuGd(SeO₃)₂Cl, MnSm(SeO₃)₂Cl, CuGd₂(SeO₃)₄ and CuSm₂(SeO₃)₄: Transition Metal containing Selenites of Samarium and Gadolinum The reaction of CoCl₂, Sm₂O₃, and SeO₂ in evacuated silica ampoules lead to blue single crystals of CoSm(SeO₃)₂Cl (triclinic, , Z = 4, a = 712.3(1), b = 889.5(2), c = 1216.2(2) pm, α = 72.25(1)°, β = 71.27(1)°, γ = 72.08(1)°, R_all = 0.0586). If MnCl₂ is used in the reaction light pink single crystals of MnSm(SeO₃)₂Cl (triclinic, , Z = 2, a = 700.8(2), b = 724.1(2), c = 803.4(2) pm, α = 86.90(3)°, β = 71.57(3)°, γ = 64.33(3)°, R_all = 0.0875) are obtained. Green single crystals of CuGd₂(SeO₃)₂Cl (triclinic, , Z = 4, a = 704.3(4), b = 909.6(4), c = 1201.0(7) pm, α = 70.84(4)°, β = 73.01(4)°, γ = 70.69(4)°, R_all = 0.0450) form analogously in the reaction of CuCl₂ and Gd₂O₃ with SeO₂. CoSm(SeO₃)₂Cl contains [CoO₄Cl₂] octahedra, which are connected via one edge and one vertex to infinite chains. The Mn²⁺ ions in MnSm(SeO₃)₂Cl are also octahedrally coordinated by four oxygen and two chlorine ligands. The linkage of the polyhedra to chains occurs exclusively via edges. Both, the cobalt and the manganese compound show the Sm³⁺ ions in eight and ninefold coordination of oxygen atoms and chloride ions. In CuGd(SeO₃)₂Cl the Cu²⁺ ions are coordinated by three oxygen atoms and one Cl^— ion in a distorted square planar manner. One further Cl^— and one further oxygen ligand complete the [CuO₃Cl] units yielding significantly elongated octahedra. The latter are again connected to chains via two common edges. For the Gd³⁺ ions coordination numbers of ?8 + 1”? and nine were found. Single crystals of the deep blue selenites CuM₂(SeO₃)₄ (M = Sm/Gd, monoclinic, P2₁/c, a = 1050.4(3)/1051.0(2), b = 696.6(2)/693.5(1), c = 822.5(2)/818.5(2) pm, β = 110.48(2)°/110.53(2)°, R_all = 0.0341/0.0531) can be obtained from reactions of the oxides Sm₂O₃ and Gd₂O₃, respectively, with CuO and SeO₂. The crystal structure contains square planar [CuO₄] groups and irregular [MO₉] polyhedra.     

Darstellung und Eigenschaften der Alkali-hexajodatogermanate (IV), M2[Ge(JO3)6]

Preparation and Properties of the Alkali Hexaiodatogermanates(IV), M₂[Ge(IO₃)₆] Germanium dioxide aquate and alkali nitrates react with iodic acid to yield alkali hexaiodatogermanates(IV), M₂[Ge(IO₃)₆], (M = NH₄, K, Rb, Cs). The unit-cell dimensions of the trigonal cell are for K₂[Ge(JO₃)₆] a₀ = 11.16 Å, c₀ = 11.34 Å, z = 3. The compounds M[M^IV(IO₃)₆] (M^I = NH₄, K, Rb, Cs, M^IV = Ge, Sn, Pb, Ti, Zr, Mn) are isomorphous¹).     

Über Blei(II)-oxid- und -hydroxidchloride

Inhaltsübersicht. Bei der Reaktion von tetragonalem Blei(II)-oxid in wäßriger Suspension mit Calciumchlorid oder mit Ammoniumchlorid lassen sich für molare Verhältnisse Cl^–/PbO bis zu 4/1 nur drei kristalline basische Blei(II)-chloride in der festen Phase mit den Pb/Cl-Verhältnissen von 3,5, 2,0 bzw. 1,0 nachweisen. Lead(II) Oxide and Hydroxide Chloride Abstract. In the reaction between tetragonal lead(II) oxide in aqueous suspension and calcium chloride, or ammonium chloride, and for molar ratios of Cl^–/PbO up to 4/1 only three kinds of crystalline basic lead chlorides are detectable in the solid phase with Pb/Cl ratios of 3.5, 2.0 and 1.0, respectively.     

Pr4(SeO3)2(SeO4)F6 und NaSm(SeO3)(SeO4): Selenit‐Selenate der Selten‐Erd‐Elemente

Pr₄(SeO₃)₂(SeO₄)F₆ and NaSm(SeO₃)(SeO₄): Selenite‐Selenates of Rare Earth Elements Light green single crystals of Pr₄(SeO₃)₂(SeO₄)F₆ have been obtained from the decomposition of Pr₂(SeO₄)₃ in the presence of LiF in a gold ampoule. The monoclinic compound (C2/c, Z = 4, a = 2230.5(3), b = 710.54(9), c = 835.6(1) pm, β = 98.05(2)°, R_all = 0.0341) contains two crystallographically different Pr³⁺ ions. Pr(1)³⁺ is attached by six fluoride ions and two chelating SeO₃^2– groups (CN = 10), Pr(2)³⁺ is surrounded by four fluoride ions, three monodentate SeO₃^2– and two SeO₄^2– groups. One of the latter acts as a chelating ligand, so the CN of Pr(2)³⁺ is 10. The selenite ions are themselves coordinated by five and the selenate ions by four Pr³⁺ ions. The coordination number of the F^– ions is three and four, respectively. The linkage of the coordination polyhedra leads to cavities in the crystal structure which incorporate the lone pairs of the selenite ions. The reaction of Sm₂(SeO₄)₃ and NaCl in gold ampoules yielded light yellow single crystals of NaSm(SeO₃)(SeO₄). The monoclinic compound (P2₁/c, Z = 4, a = 1066.9(2), b = 691.66(8), c = 825.88(9) pm, β = 91.00(2)°, R_all = 0.0530) contains tenfold oxygen coordinated Sm³⁺ ions. The oxygen atoms belong to five SeO₃^2– and two SeO₄^2– ions. Two of the SeO₃^2– groups as well as one of the SeO₄^2– groups act as a chelating ligand. The sodium ions are surrounded by five SeO₄^2– ions and one SeO₃^2– group. One of the selenate ions is attached chelating leading to a coordination number of seven. Each selenite group is coordinated by six (5 × Sm³⁺ and 1 × Na⁺), each selenate ion by seven cations (5 × Na⁺ and 2 × Sm³⁺).     

Hydrothermal Synthesis and Crystal Structures of Na2Be3(SeO3)4·H2O and Cs2[Mg(H2O)6]3(SeO3)4

The selenites, Na₂Be₃(SeO₃)₄ · H₂O and Cs₂[Mg(H₂O)₆]₃(SeO₃)₄, were synthesized under hydrothermal conditions. The crystal structures of Na₂Be₃(SeO₃)₄ · H₂O and Cs₂[Mg(H₂O)₆]₃(SeO₃)₄ were determined by single‐crystal X‐ray diffractions. Na₂Be₃(SeO₃)₄ · H₂O crystallizes in the triclinic space group P1 (no. 2) with unit cell parameters a = 4.8493(9), b = 12.013(2), c = 12.077(2) Å, and Z = 2, whereas Cs₂[Mg(H₂O)₆]₃(SeO₃)₄ crystallizes in the monoclinic space group C2/m (no. 12) with lattice cell parameters a = 12.596(6), b = 7.297(4), c = 16.914(8) Å, and Z = 2. Na₂Be₃(SeO₃)₄ · H₂O features a three‐dimensional open framework structure formed by BeO₄ tetrahedra and SeO₃ trigonal pyramids. Na cations and H₂O molecules are located in different tunnels. Cs₂[Mg(H₂O)₆]₃(SeO₃)₄ has a structure composed of isolated [Mg(H₂O)₆] octahedra and SeO₃ trigonal pyramids interacted by hydrogen bonds, and Cs cations are resided in‐between. Both compounds were characterized by thermogravimetric analysis and FT‐IR spectroscopy.     

The First UV Nonlinear Optical Selenite Material: Fluorination Control in CaYF(SeO3)2 and Y3F(SeO3)4

It is a great challenge to develop UV nonlinear optical (NLO) material due to the demanding conditions of strong second harmonic generation (SHG) intensity and wide band gap. The first ultraviolet NLO selenite material, Y₃F(SeO₃)₄, has been obtained by control of the fluorine content in a centrosymmetric CaYF(SeO₃)₂. The two new compounds represent similar 3D structures composed of 3D yttrium open frameworks strengthened by selenite groups. CaYF(SeO₃)₂ has a large birefringence (0.138@532 nm and 0.127@1064 nm) and a wide optical band gap (5.06 eV). The non-centrosymmetric Y₃F(SeO₃)₄ can exhibit strong SHG intensity (5.5×KDP@1064 nm), wide band gap (5.03 eV), short UV cut-off edge (204 nm) and high thermal stability (690 °C). So, Y₃F(SeO₃)₄ is a new UV NLO material with excellent comprehensive properties. Our work shows that it is an effective method to develop new UV NLO selenite material by fluorination control of the centrosymmetric compounds.     

Crystal structure of Li2Cu3(SeO3)2(SeO4)2

Summary Single crystal X-ray data of the hydrothermally grown new phase Li₂Cu₃(SeO₃)₂(SeO₄)₂ were measured with a four-circle diffractometer up to sin /=0.81 Å^–1 [I2/a,Z=4,V=1175.5 ų,a=16.293(6),b=5.007(2),c=14.448(6) Å, = 94.21(1)°]. The structure was determined by direct and Fourier methods and refined toR=0.034,R _w =0.027 for 2 086 independent reflections.Cu(1)^[4+1]O₅ forms a tetragonal pyramid, Cu(2)^{[4 + 2]}O₆ is a strongly elongated octahedron. The Li atom is surrounded by four O atoms forming a distorted tetrahedron. Se(IV)O₃ and Se(VI)O₄ groups are in accordance to literature, mean Se-O bond lengths are 1.714 and 1.644 Å.

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Die Kristallstruktur von Li₂Cu₃(SeO₃)₂(SeO₄)₂

Zusammenfassung Einkristall-Röntgendaten der hydrothermal gezüchteten neuen Phase Li₂Cu₃(SeO₃)₂(SeO₄)₂ wurden mit einem Vierkreisdiffraktometer im Bereich bis zu sin /=0.81 Å^–1 gemessen [I2/a,Z=4,V=1175.5 ų,a=16.293(6),b=5.007(2),c=14.448(6) Å, =94.21(1)°]. Die Kristallstruktur wurde mittels direkter und Fourier-Methoden bestimmt und für 2 086 unabhängige Reflexe zuR=0.034,R _w =0.027 verfeinert.Cu(1)^[4+1]O₅ bildet eine tetragonale Pyramide, Cu(2)^[4+2]O₆ ist ein stark verlängertes Oktaeder. Das Li-Atom ist von vier O-Atomen in Gestalt eines verzerrten Tetraeders umgeben. Die Se(IV)O₃-und Se(VI)O₄-Gruppen entsprechen der Literatur, die mittleren Se-O-Abstände betragen 1.714 und 1.644 Å.

     

LuF[SeO3] und LuCl[SeO3]: Zwei nicht‐isotype Halogenid‐Oxoselenate(IV) des Lutetiums

LuF[SeO₃] and LuCl[SeO₃]: Two Non‐Isotypic Halide Oxoselenates(IV) of Lutetium Despite the formal similarity of LuF[SeO₃] and LuCl[SeO₃] both compounds show significant structural differences due to the different positions of the halide anions (X⁻) within the pentagonal bipyramids [LuO₅X₂]⁹⁻. However, both oxoselenates(IV) have these pentagonal bipyramids as basic modules in common that are connected via O²⁻ edges to chains. LuCl[SeO₃] crystallizes orthorhombically in space group Pnma (no. 62; a = 714.63(7), b = 681.76(7) and c = 864.05(9) pm; Z = 4). The structure is isotypic to that one recently presented for ErCl[SeO₃]. With a single Cl⁻ anion in each an apical and an equatorial position, the chains have to be inclined with an angle of about 54° relative to each other to get connected alternately by common Cl⁻ corners and bridging [SeO₃]²⁻ pyramids. In contrast to that, LuF[SeO₃] which crystallizes triclinically in space group (no. 2; a = 644.85(6), b = 684.41(7), c = 427.98(4) pm, α = 94.063(5), β = 96.484(5) and γ = 91.895(5)°; Z = 2) takes a structural motif already known from CsTmCl₂[SeO₃]. Owing to the apical position of both halide anions it is now possible to connect the chains directly via discrete Ψ¹‐tetrahedral [SeO₃]²⁻ groups to layers. The same layers are present in LuF[SeO₃] and without the formal alkali‐metal halide unit (CsCl) of the CsTmCl₂[SeO₃]‐type compounds, the layers can also be connected directly by common F⁻ corners to a three‐dimensional array. Torch‐sealed evacuated silica ampoules were used for the synthesis of both lutetium(III) halide oxoselenates(IV). For LuF[SeO₃] these vessels have been graphitized before to prevent them from oxosilicate‐producing side‐reactions with the applied fluoride. The synthesis of LuCl[SeO₃] required Lu₂O₃ and SeO₂ in a molar ratio of 1 : 6 with a surplus of an eutectic RbCl/LiCl mixture as fluxing agent and an annealing period of five weeks at a temperature of 500 °C, whereas Lu₂O₃, LuF₃ and SeO₂ (in a molar ratio of 1 : 1 : 3) with CsBr as flux were converted to LuF[SeO₃] at 750 °C within six days.     

Lanthanum selenite,La2(SeO3)3

Hydro­thermally prepared La₂(SeO₃)₃ contains a three‐dimensional network of LaO₁₀ polyhedra [d_av(La—O) = 2.622 (3) Å] and SeO₃ pyramids [d_av(Se—O) = 1.691 (3) Å]. One of the SeO₃ pyramids is in a general position and the other has crystallographic m symmetry. There are pseudo‐channels in the [010] direction which are probably associated with the Se^IV lone pairs.     

PbCu3(OH)(NO3)(SeO3)3·1/2H2O und Pb2Cu3O2(NO3)2(SeO3)2: Synthese und Kristallstrukturuntersuchung

Crystals of PbCu₃(OH)(NO₃)(SeO₃)₃·1/2H₂O [a=7.761(3)Å,b=9.478(4)Å,c=9.514(4)Å, =66.94(2)°, =69.83(2)°, =81.83(2)°, space group P ,Z=2] and Pb₂Cu₃O₂(NO₃)₂(SeO₃)₂ [a=5.884(2)Å,b=12.186(3)Å,c=19.371(4)Å, space group Cmc2₁,Z=4] were synthesized under hydrothermal conditions. Their crystal structures were refined with three-dimensional X-ray data toR _w=0.033 resp. 0.055. In PbCu₃(OH)(NO₃)(SeO₃)₃·1/2H₂O the Cu atoms are [4+1] and [4+2] coordinated and via SeO₃ groups a three-dimensional atomic arrangement is built up. In Pb₂Cu₃O₂(NO₃)₂(SeO₃)₂ there are sheets, which are connected only via Pb-O bonds ranging from 2.98 Å to 3.16 Å.

     

Bromoplumbate mit kettenförmigen und isolierten Anionen: (Bzl4P)2[Pb3Br8], (Bzl4P)2[Pb3Br8(dmf)2], (Bzl4P)[PbBr3], (Bzl4P)2[PbBr4] und (Bzl4P)4[Pb2Br6][PbBr4]

Bromoplumbates with One‐dimensional Polymeric and Isolated Anions: (Bzl₄P)₂[Pb₃Br₈], (Bzl₄P)₂[Pb₃Br₈(dmf)₂], (Bzl₄P)[PbBr₃], (Bzl₄P)₂[PbBr₄], and (Bzl₄P)₄[Pb₂Br₆][PbBr₄] PbBr₂ reacts with LiBr and (Bzl₄P)(PF₆) (Bzl = CH₂C₆H₅) in acetone to form a series of bromoplumbate complexes with compositions and structures depending on the conditions of reaction and crystallization. While the anions in (Bzl₄P)₂[Pb₃Br₈] ( 1 ) and (Bzl₄P)[PbBr₃] ( 2 ) are one‐dimensional polymers with penta‐ and hexacoordinated Pb atoms, the metal atoms in the mono‐ and dinuclear complex anions of (Bzl₄P)₂[PbBr₄] · 2acetone ( 3 · 2acetone) and (Bzl₄P)₄[Pb₂Br₆][PbBr₄] ( 4 ) bind to four bromo ligands. From DMF as a solvent (Bzl₄P)₂[Pb₃Br₈(dmf)₂] ( 1 b ) crystallizes with the same bromoplumbate structure as in 1 a , but with dmf ligands occupying the coordination sites vacant in 1 a . Upon radiation of compound 3 with ultraviolet light greenish yellow photoluminescence (emssion maximum at 547 nm) is observed. Crystallographic details see “Inhaltsübersicht”.     

Darstellung und Eigenschaften von Blei(IV)-arsenat-Gelen und kristallinem Blei(IV)-hydrogenarsenat-monohydrat

Lead(IV) acetate reacts with aqueous arsenic acid to yield lead(IV) arsenates, the state of which depends on the conditions of precipitation. At room temperature amorphous precipitates or gelatinous masses are obtained. Also clear solutions are obtained, which need sometime to become gelatinous. At 90°C colourless crystalline lead(IV) hydrogenarsenate-monohydrate, Pb(HAsO₄)₂ · H₃O, is obtained, isotypic with lead(IV) hyrdrogen-phosphate-monohydrate.     

Polyol-Metall-Komplexe. XIII [1]. Na2[Be(C4H6O3)2] · 5H2O und Na2[Pb(C4H6O3)2] · 3H2O – zwei homoleptische Bis-polyolato-metallate mit Beryllium und mit Blei

Polyol Metal Complexes. XIII. Na₂[Be(C₄H₆O₃)₂] · 5H₂O and Na₂[Pb(C₄H₆O₃)₂] · 3H₂O – Two Homoleptic Bis Polyolato Metallates with Beryllium and with Lead Na₂[Be(C₄H₆O₃)₂] · 5H₂O ( 1 ) and Na₂[Pb(C₄H₆O₃)₂] · 3H₂O ( 2 ) crystallize from concentrated, alkaline aqueous solutions. The polyol anhydroerythritol is deprotonated twice in the mononuclear, homoleptic complex anions. The preference of beryllium for the binding of cis-furanoid diols is shown. In 2 , a stereochemically active lone pair at the central atom is the reason for the construction of low dimensional aggregates from three plumbate and three sodium ions.     

Synthesis,Crystal Structures,and Optical Properties of AM2(OH)(SeO3)2 (A = Na,Rb; M = Mg,Zn)

Sodium magnesium selenite NaMg₂(OH)(SeO₃)₂ and rubidium zinc selenite RbZn₂(OH)(SeO₃)₂ were prepared by hydrothermal reactions. The crystal structures of the title compounds were determined by single‐crystal X‐ray diffraction. NaMg₂(OH)(SeO₃)₂ crystallizes in the orthorhombic space group Pnma (no. 62) with lattice parameters a = 13.1919(10), b = 6.0415(4), c = 8.2182(6) Å, and Z = 4 and RbZn₂(OH)(SeO₃)₂ crystallizes in the triclinic space group P$\bar{1}$ (no. 2) with lattice parameters a = 4.8698(5), b = 7.3446(8), c = 11.7796(12) Å, α = 82.554(3), β = 78.456(2), γ = 71.603(3)°,and Z = 2. The structure of NaMg₂(OH)(SeO₃)₂ is a three‐dimensional framework consisting of edge‐sharing MgO₆ octahedra and trigonal pyramidal SeO₃^2– groups, whereas the structure of RbZn₂(OH)(SeO₃)₂ is a two‐dimensional layers structure consisting of corner‐sharing [Zn₂O₇] dimers linked by trigonal pyramidal SeO₃^2– groups. The compounds were characterized by the solid state UV/Vis/NIR diffuse reflectance, and FT‐IR spectroscopy.     

Darstellung und Kristallstruktur von Pb2(NO2)(NO3)(SeO3)

Crystals of Pb₂(NO₂)(NO₃)(SeO₃) were synthesized by partial reduction of nitrate ions with native copper under hydrothermal conditions. The crystal structure [a=5.529 (2) Å,b=10.357 (3) Å,c=6.811 (2) Å, space group Pmn2₁,Z=2] was determined from 1 707 independent X-ray data up to sin /=0.81 Å^–1 and was refined toR _w =0.028. The Pb(1) atom is ten coordinated to O atoms [Pb(1)-O from 2.51 Å to 2.96 Å], the Pb(2) atom has three nearest O atoms [Pb(2)-O=2.41 Å (1 ×) and 2.45 Å (2 ×)] and six next-nearest O atoms [Pb(2)-O from 2.80 Å to 3.22 Å].

Herrn Prof. Dr.K. Komarek zum 60. Geburtstag gewidmet.     

Synthese und Kristallstruktur von (Ph3PNPPh3)2[Cu(N3)4]

Inhaltsübersicht. Die Titelverbindung entsteht neben CuN₃ · PPh₃ bei der Einwirkung von Natriumazid auf CuCl₂ und Triphenylphosphan in siedendem Acetonitril bei Anwesenheit von 15-Krone-5 als Lösungsvermittler für NaN₃. (Ph₃PNPPh₃)₂[Cu(N₃)₄] bildet schwarze Kristalle, die wir durch das IR-Spektrum und durch eine röntgenographische Strukturanalyse charakterisiert haben. Raumgruppe Pbca, Z = 4, (4245 beobachtete unabhängige Reflexe, R = 7,2%), Gitter-abmessungen (20°C):a = 1980, 1;b = 1618,8; c = 2014,3 pm. Die Verbindung besteht aus Kationen [Ph₃PNPPh₃]⁺ und Anionen [Cu(N₃)₄]^2– der Symmetrie C_i, in denen das Cu-Atom planar von den α-N-Atomen der Azidgruppen mit Cu–N-Abständen von 197,2(4) und 189,5(4) pm umgeben ist. Synthesis and Crystal Structure of (Ph₃PNPPh₃)₂[Cu(N₃)₄] The title compound is prepared besides CuN₃ · PPh₃ by the reaction of sodium azide with CuCl₂ and PPh₃ in boiling acetonitrile in the presence of 15-crown-5. (Ph₃PNPPh₃)₂[Cu(N₃)4] forms black crystals, which have been characterized by their IR spectrum as well as by an X-ray structure determination. Space group Pbca, Z = 4 (4245 observed independent reflexions, R = 0.072), lattice dimensions (20°C): A = 1980.1; b = 1618.8; c = 2014.3 pm. The compound consists of Ph₃PNPPh₃⁺ cations and anions [Cu(N₃)₄]^2– with symmetry C₁, in which the copper atom is planarly surrounded by the four nitrogen atoms of the azide groups with bond lengths Cu–N of 197.2(4) and 189.5(4) pm, respectively.