Formation,Structural Characterization,and Calculated NMR Chemical Shifts of Selenium‐Nitrogen Compounds from SeCl4 and ArNHLi (Ar = supermesityl,mesityl)

Supermesityl selenium diimide [Se{N(C₆H₂^tBu₃‐2, 4, 6)}₂; Se{N(mes*)}₂] can be prepared in a good yield from the reaction of SeCl₄ and (mes*)NHLi. The molecule adopts an unprecedented anti, anti‐conformation, as deduced by DFT calculations at PBE0/TZVP level of theory and supported by ⁷⁷Se NMR spectroscopy and a crystal structure determination. An analogous reaction involving (C₆H₂Me₃‐2, 4, 6)NHLi [(mes)NHLi] unexpectedly lead to the reduction of selenium and afforded the selenium diamide Se{NH(mes)}₂ that was characterized by X‐ray crystallography and ⁷⁷Se NMR spectroscopy. The Se‐N bonds of 1.847(3) and 1.852(3) Å show normal single bond lengths. The <NSeN bond angle of 109.9(1)° also indicates a tetrahedral AX₂E₂ bonding arrangement around selenium. Two N‐H···N hydrogen bonds link the Se{NH(mes)}₂ molecule with two discrete (mes)NH₂ molecules. In the solid state selenium diamide adopts the anti‐conformation, whereas in solution the presence of both syn‐ and anti‐isomers could be observed. PBE0/TZVP calculations of the shielding tensors of 28 different types of selenium‐containing molecules, for which the ⁷⁷Se chemical shifts are unambiguously known, were carried out to assist the spectral assignment of Se{N(mes*)}₂ and Se{NH(mes)}₂.     

Synthesis and Structure of the Bicyclic [Sn4Se11]6– Anion in Na6Sn4Se11 · 22 H2O

Na₆Sn₄Se₁₁ · 22 H₂O can be crystallised at –8 °C as yellow‐orange needles from the 1 : 2 H₂O/CH₃OH mother liquor of a superheated reaction mixture of NaOH(s), Sn and Se. The bicyclic [Sn₄Se₁₁]^6– anion exhibits crystallographic C₂ symmetry and is composed of corner‐bridged SnSe₄ tetrahedra. Two opposite tin atoms of an Sn₄Se₄ 8‐membered ring are linked by a common Se atom, thereby affording two 6‐membered boat‐shaped Sn₃Se₃ rings with a shared Sn–Se–Sn bridging unit. [Sn₄Se₁₁]^6– thus represents the immediate precursor of the well‐known adamantane‐like [Sn₄Se₁₀]^4– anion.     

Neue Halogenochalkogen(IV)‐Säuren: [H3O(Benzo‐18‐Krone‐6)]2[Te2Br10] und [H5O2(Dibenzo‐24‐Krone‐8)]2[Te2Br10]

Novel Halogenochalcogeno(IV) Acids: [H₃O(Benzo‐18‐Crown‐6)]₂[Te₂Br₁₀] and [H₅O₂(Dibenzo‐24‐Crown‐8)]₂[Te₂Br₁₀] Systematic studies on halogenochalcogeno(IV) acids containing tellurium and bromine led to the new crystalline phases [H₃O(Benzo‐18‐Crown‐6)]₂[Te₂Br₁₀] ( 1 ) and [H₅O₂(Dibenzo‐24‐Crown‐8)]₂[Te₂Br₁₀] ( 2 ). The [Te₂Br₁₀]^2‐ anions consists of two edge‐sharing distorted TeBr₆ octahedra, the oxonium cations are stabilized by crownether. ( 1 ) crystallizes in the monoclinic space group P2₁/n with a = 14.520(5) Å, b = 22.259(6) Å, c = 16.053(5) Å, β = 97.76(3)° and Z = 4, whereas ( 2 ) crystallizes in the triclinic space group with a = 11.005(4) Å, b = 12.103(5) Å, c = 14.951(6) Å, α = 71.61(3)°, β = 69.17(3)°, γ = 68.40(3)° and Z = 1.     

Synthesis and Crystal Structure of >Bis(tetrapropylammonium) Hexabromotellurate(IV)‐bis{dibromoselenate(II)}, [NnPr4]2[TeBr6(SeBr2)2], the Salt of a Mixed‐valence Bromotellurate(IV)‐Selenate(II) Anion

Dark brown crystals of [NⁿPr₄]₂[TeBr₆(SeBr₂)₂] ( 1 ) were obtained when selenium and bromine (1:1) were allowed to react in acetonitrile solution in the presence of tellurium(IV) bromide and tetrapropylammonium bromide. The salt 1 crystallizes in the monoclinic space group P2₁/n with the cell dimensions a = 14.7870(3) Å, b = 9.5523(3) Å, c = 16.7325(3) Å, β = 110.56(10)° (at 123(2) K). In the solid state the [TeBr₆(SeBr₂)₂]^2– anion contains a nearly regular [TeBr₆] octahedron in which the four equatorial bromo ligands have developed bonds to Se^II atoms of the SeBr₂ molecules. The contacts between the bridging bromo and the Se^II atoms of the SeBr₂ molecules are 3.0000(4) and 3.0561(4) Å, and can be interpreted as bonds of the donor‐acceptor type with the bridging bromo ligands as donors and the SeBr₂ molecules as acceptors. The Te^IV–Br distances are in the range 2.6816(3)–2.7131(3) Å and the Se^II–Br bond lengths in the coordinated SeBr₂ molecules are 2.3548(4) and 2.3725(4) Å.     

Reaction of Selenium with Bromine in the Presence of Methyltriphenylphosphonium Bromide: Syntheses and Crystal Structures of [PMePh3]2[Se2Br6] and [PMePh3]2[SeBr6(SeBr2)2]

The brown crystals of [PMePh₃]₂[Se₂Br₆] ( 1 ) and red crystals of [PMePh₃]₂[SeBr₆(SeBr₂)₂] ( 2 ) were obtained when selenium and bromine reacted in the solution of acetonitrile in the presence of methyltriphenylphosphonium bromide. The crystal structures of 1 and 2 has been determined by the X‐ray methods and refined to R = 0.0373 for 2397 reflections and 0.0397 for 3417 reflections, respectively. The salt 1 crystallizes in the monoclinic space group P2₁/n with the cell dimensions a = 13.202(5) Å, b = 11.954(4) Å, c = 13.418(6) Å, β = 93.08(4)° (193(2)). The crystals of 2 are triclinic, space group with the cell dimensions a = 10.266(3) Å, b = 11.311(3) Å, c = 11.619(2) Å, α = 108.87(2)°, β = 105.72(2)°, γ = 99.40(2)° (193(2) K). In the solid state structure of 1 the dinuclear hexabromo‐diselenate(II) anion is centrosymmetric and consists of two distorted almost square planar SeBr₄ units sharing a common edge through two μ‐bridging Br atoms. The terminal Se^II–Br bonds are 2.3984(11) and 2.4273(11) Å, whereas the bridging μBr–Se^II bonds are 2.7817(11) and 2.9081(12) Å. In the solid state the trinuclear [SeBr₆(SeBr₂)₂]^2? anion of 2 is centrosymmetric too and contains a nearly regular [SeBr₆] octahedron where the four equatorial bromo ligands each have developed bonds to the Se^II atoms of the SeBr₂ molecules. The contacts between the bridging bromo and the Se^II atoms of the SeBr₂ molecules are 3.0603(15) and 3.1043(12) Å, and can be interpreted as bonds of the donor‐acceptor type with the bridging bromo ligands as donors and the SeBr₂ molecules as acceptors. The Se^IV–Br distances are in the range 2.5570(9)–2.5773(11) Å and the Se^II–Br bond lengths in coordinated SeBr₂ molecules – 2.3411(12) and 2.3421(10) Å.     

ASc[SeO3]2 (A = Na – Cs): Pure Alkali‐Metal Scandium Oxoselenates(IV) and Their Representatives With Mixed Alkali‐Metal Occupation

Alkali‐metal scandium oxoselenates(IV) ASc[SeO₃]₂ (A = Na – Cs) are known since a few years and a hydrothermal synthesis was used to obtain them. In our new studies we applied a flux‐supported solid‐state reaction and produced colorless single crystals as well. All representatives ASc[SeO₃]₂ with A = Na – Cs crystallize in the orthorhombic space group Pnma, in contrast to earlier reports for hexagonal RbSc[SeO₃]₂. Furthermore we have extended this field with some crystals showing a mixed occupation on the alkali‐metal site, namely (K,Na)Sc[SeO₃]₂, (Rb,K)Sc[SeO₃]₂, and (Cs,Rb)Sc[SeO₃]₂. Since all of them contain [ScO₆]^9– octahedra and [SeO₃]^2– ψ¹‐tetrahedra the diverse connectivity of the distinct alkali‐metal centered oxygen polyhedra differentiates the compounds with the smaller alkali metals (A′ = Na and K) from those with the bigger ones (A′′ = Rb and Cs). For the mixed crystals the amount of smaller or bigger alkali metal is responsible, which design is chosen by the system. This forces the mixed crystal (Rb,K)Sc[SeO₃]₂ with a higher amount of potassium instead of rubidium to crystallize isotypically with KSc[SeO₃]₂ and NaSc[SeO₃]₂, whereas the pure rubidium compound RbSc[SeO₃]₂ adopts the CsSc[SeO₃]₂‐type structure. These findings are supported by single‐crystal Raman spectroscopy.     

Nd2(SeO3)2(SeO4) · 2H2O – a Mixed‐Valence Compound containing Selenium in the Oxidation States +IV and +VI

Pale pink crystals of Nd₂(SeO₃)₂(SeO₄) · 2H₂O were synthesized under hydrothermal conditions from H₂SeO₃ and Nd₂O₃ at about 200 °C. X‐ray diffraction on powder and single‐crystals revealed that the compound crystallizes with the monoclinic space group C 2/c (a = 12.276(1) Å, b = 7.0783(5) Å, c = 13.329(1) Å, β = 104.276(7)°). The crystal structure of Nd₂(SeO₃)₂(SeO₄) · 2H₂O is an ordered variant of the corresponding erbium compound. Eight oxygen atoms coordinate the Nd^III atom in the shape of a bi‐capped trigonal prism. The oxygen atoms are part of pyramidal (Se^IVO₃)^2? groups, (Se^VIO₄)^2? tetrahedra and water molecules. The [NdO₈] polyhedra share edges to form chains oriented along [010]. The selenate ions link these chains into layers parallel to (001). The layers are interconnected by the selenite ions into a three‐dimensional framework. The dehydration of Nd₂(SeO₃)₂(SeO₄) · 2H₂O starts at 260 °C. The thermal decomposition into Nd₂SeO₅, SeO₂ and O₂ at 680 °C is followed by further loss of SeO₂ leaving cubic Nd₂O₃.     

Direct Syntheses of Bis(tetraphenylphosphonium) and Bis(ethyltriphenylphosphonium) Hexabromo‐diselenates(II), [PPh4]2[Se2Br6] and [PEtPh3]2[Se2Br6]. The Crystal Structure of [PEtPh3]2[Se2Br6]

Brown crystals of [PPh₄]₂[Se₂Br₆] ( 1 ) and [PEtPh₃]₂[Se₂Br₆] ( 2 ) were obtained when selenium and bromine reacted in acetonitrile solution in the presence of tetraphenylphosphonium bromide and ethyltriphenylphosphonium bromide, respectively. The crystal structure of 2 has been determined by X‐ray methods and refined to R = 0.0420 for 4161 reflections. The crystals are monoclinic, space group P2₁/n with Z = 2 and a = 13.055(3) Å, b = 12.628(3) Å, c = 13.530(3) Å, β = 92.40(3)° (293(2) K). In the solid state structure of 2 the dinuclear hexabromo‐diselenate(II) anion is centrosymmetric and consists of two distorted almost square‐planar SeBr₄ units sharing a common edge through two bridging Br atoms. The terminal Se^II–Br bond distances are found to be 2.419(1) and 2.445(1) Å, the bridging μBr–Se^II bond distances 2.901(1) and 2.802(1) Å.     

Syntheses and X‐Ray Crystal Structures of [Li(thf)4][SnCl5(thf)] and {[Li(Et2O)2]2‐(μ‐Cl2)2‐SnIVCl2}

The syntheses and single crystal X‐ray structure determinations are reported for [Li(thf)₄][SnCl₅(thf)] ( 1 ) and {[Li(Et₂O)₂]₂‐(μ‐Cl₂)₂‐Sn^IVCl₂} ( 2 ). Compound 1 is ionic with a tetrahedral coordinated lithium cation and distorted octahedral tin (IV) atom in the anion, while compound ( 2 ) is a centrosymmetric heteronuclear double salt of LiCl and SnCl₄. [Li(thf)₄][SnCl₅(thf)] is monoclinic, P2₁/n, a = 11.204(1), b = 15.599(1), c = 17.720(2) Å; β = 96.734(2)°, Z = 4, R 0.0418; {[Li(Et₂O)₂]₂‐(μ‐Cl₂)₂‐Sn^IVCl₂} is monoclinic, P2₁/n, a = 10.848(2), b = 12.764(2), c = 11.748(2) Å; β = 90.388(3)°, Z = 4, R = 0.0851.     

Synthesis and Crystal Structure of Bis(methyltriethylammonium) Hexabromotellurate(IV)‐tris{dibromodiselenate(I)}, [NMeEt3]2n[TeBr6(Se2Br2)3]n,Containing a Chain‐Polymeric Mixed‐valence Bromotellurate(IV)‐Selenate(I) Anion

Red crystals of [NMeEt₃]_2n[TeBr₆(Se₂Br₂)₃]n ( 1 ) were isolated when selenium and bromine (1:1) were allowed to react in acetonitrile solution in the presence of tellurium(IV) bromide and methyltriethylammonium bromide (1:2). The salt 1 crystallizes in the monoclinic space group C2/c with the cell dimensions a = 27.676(6) Å, b = 9.665(2) Å, c = 18.796(4) Å and ß = 124.96(3)° (120 K). The [TeBr₆(Se₂Br₂)₃]^2— anions contain nearly regular octahedral [TeBr₆]^2— ions which are incorporated into a polymeric chain by bonding contacts between 3 facial bromo ligands and 3 Se₂Br₂ molecules, one of which is situated on the twofold symmetry axis. The distances between the μBr ligands and the Se^I atoms of the Se₂Br₂ molecules are observed in the range 3.308(2) — 3.408(2) Å and can tentatively be interpreted as donor‐acceptor bonds with μBr as donors and Se₂Br₂ as acceptors. The Te^IV—Br distances are in the range 2.669(1) — 2.687(1) Å. The bond lengths in the connecting Se₂Br₂ molecules are: Se^I—Se^I = 2.267(2) and 2.281(2) Å, Se^I—Br = 2.340(1), 2.353(1) and 2.337(1) Å.     

Das erste Alkalimetall‐Lanthanoid(III)‐Iodid‐Oxotellurat(IV): Na2Lu3I3[TeO3]4

Colorless platelets of Na₂Lu₃I₃[TeO₃]₄ were obtained within five days at 775 °C by the reaction of Lu₂O₃ and TeO₂ in a 3:8 molar ratio with NaI added in excess as both fluxing agent and reactant in evacuated silica ampoules. It crystallizes in the monoclinic space group P2/c with the lattice parameters a = 921.69(5), b = 552.71(3), c = 1664.37(9) pm, β = 90.218(4)° and Z = 2. The crystal structure of Na₂Lu₃I₃[TeO₃]₄ exhibits two crystallographically different Lu³⁺ cations, both coordinated by eight O^2– anions as square antiprisms. These polyhedra are interconnected through four common edges to build up {}^2_∞ {[LuO{}^e_8/2 ]^5–} layers (e = edge‐linking) parallel to (100). Furthermore, the crystal structure includes a crystallographically unique Na⁺ cation surrounded by four O^2– and four I^– anions also in the shape of a square antiprism. These polyhedra connect via common (I2)^–···(I2)^– edges in generating {}^1_∞ {[Na₂O₈I{}^e_4 ]^18–} double‐strands that are further linked by (I1)^– vertices to result in the formation of {}^2_∞ {[Na₂O₈I₃{}^e,v_3 ]^17–} layers (v = vertex‐linking) spreading out parallel to (100) as well. Thus, the crystal structure contains two crystallographically distinct I^– anions, of which (I1)^– is coordinated nearly linear (? (Na–I1–Na) = 179.6°) by two Na⁺ cations, whereas (I2)^– has contact to three of them displaying a distance of 114 pm from the triangular (Na⁺)₃ plane. The crystal structure of Na₂Lu₃I₃[TeO₃]₄ is completed by two crystallographically independent Te⁴⁺ cations that show stereochemically active non‐bonding electron pairs (“lone pairs”) and are located above and below the {}^2_∞ {[LuO{}^e_8/2 ]^5–} layers forming isolated ψ¹‐tetrahedral [TeO₃]^2– anions (d(Te–O) = 188–190 pm) with all oxygen atoms.     

Alkyl‐Tethered Bis‐Phosphoryl Compounds with two 1,3,2‐Benzodiazaphosphorinone Units; Oxidation,Complexation, and X‐Ray Structure Analysis of Selected Compounds

The reaction of the bis‐chlorophosphines 1 a – 1 d with bis(2‐chloroethyl)amine hydrochloride in the presence of triethylamine and with various trimethylsilylamines led to a new class of bis‐phosphorus ligands 2 a – 2 c and 3 a – 3 g . ³¹P‐NMR studies suggested that the bis‐phosphorus ligands undergo rotation reactions about the alkyl bridge in polar solvents. Compounds 2 a – 2 c showed initially only one sharp singlet each in their ³¹P‐NMR spectra. After a few days at room temperature, two signals were observed. Similar results were observed for 3 a – 3 g . In the solid state, the two phosphorus atoms in 2 c are not equivalent, as was confirmed by the observation of two signals in the solid state ³¹P‐NMR spectrum. Oxidation reactions of 2 a – 2 c by the hydrogen peroxide‐urea 1 : 1 adduct (NH₂)₂C(:O) · H₂O₂ led to the formation of the corresponding phosphoryl compounds 4 a – 4 c . Reaction of 2 a and 3 a with Pt[COD]Cl₂ (COD = 1.5‐Cyclooctadiene) furnished the complexes 5 and 6 . The NMR spectra suggested that the two chlorine atoms are in cis position. X‐ray structure analyses were conducted for 2 a , which exhibits twofold symmetry; 2 c , which is linked into dimers by hydrogen bonds C–H…O; and 6 , confirming the cis configuration.     

Germanium carboxylates: the first X‐ray diffraction study of germanium(II) dicarboxylate and germanium(IV) tetracarboxylate

Germanium(II) dipropionate (1) has been synthesized and its crystal structure, as well as that of germanium(IV) tetrapropionate (2), has been determined. By contrast to monomeric 2 with monodentate propionate ligands, compound 1 is associated, forming a cyclotetramer [Ge(O₂CEt)₂]₄ (1a) via intermolecular dative C?O → Ge interactions. Copyright © 2005 John Wiley & Sons, Ltd.     

The Reaction of Selenium Trioxide with Dialkyl Ethers

The donor‐acceptor complexes Et₂O·SeO₃ and (Me₂O)₂·SeO₃ can be obtained as primary products by the reactions of selenium trioxide with dimethyl ether (Me₂O) and diethyl ether (Et₂O). The crystal and molecular structure of both complexes, which are stable below their melting points only, was determined by X‐ray structure analysis. Pairs of molecules Et₂O·SeO₃ form dimers due to two weak intermolecular Se···O contacts. No intermolecular interactions were observed in (Me₂O)₂·SeO₃. Trigonal bipyramidal coordination around Se^VI atoms in the latter complex is almost undistorted. Conversion of the adducts to dialkylesters of diselenic and selenic acid in the liquid phase was monitored by Raman, ¹H‐ and ⁷⁷Se‐NMR spectroscopy.     

Rb6LiPr11Cl16[SeO3]12: Ein chloridisch derivatisiertes Rubidium‐Lithium‐Praseodym(III)‐Oxoselenat(IV)

Rb₆LiPr₁₁Cl₁₆[SeO₃]₁₂: A Chloride‐Derivatized Rubidium Lithium Praseodymium(III) Oxoselenate(IV) Transparent green square platelets with often truncated edges and corners of Rb₆LiPr₁₁Cl₁₆[SeO₃]₁₂ were obtained by the reaction of elemental praseodymium, praseodymium(III,IV) oxide and selenium dioxide with an eutectic LiCl–RbCl flux at 500 °C in evacuated silica ampoules. A single crystal of the moisture and air insensitive compound was characterized by X‐ray diffraction single‐crystal structure analysis. Rb₆LiPr₁₁Cl₁₆[SeO₃]₁₂ crystallizes tetragonally in the space group I4/mcm (no. 140; a = 1590.58(6) pm, c = 2478.97(9) pm, c/a = 1.559; Z = 4). The crystal structure is characterized by two types of layers parallel to the (001) plane following the sequence 121′2′1. Cl^? anions form cubes around the Rb⁺ cations (Rb1 and Rb2; CN = 8; d(Rb⁺?Cl^?) = 331 – 366 pm) within the first layer. One quarter of the possible places for Rb⁺ cations within this CsCl‐type kind of arrangement is not occupied, however the Cl^? anions of these vacancies are connected to Pr³⁺ cations (Pr4) above and below instead, forming square antiprisms of [(Pr4)O₄Cl₄]^9? units (d(Pr4?O) = 247–249 pm; d(Pr4?Cl) = 284–297 pm) that work as links between layer 1 and 2. Central cations of the second layer consist of Li⁺ and Pr³⁺. While the Li⁺ cations are surrounded by eight O^2? anions (d(Li?O5) = 251 pm) in the shape of cubes again, the Pr³⁺ cations are likewisely coordinated by eight O^2? anions as square antiprisms (for Pr1, d(Pr1?O2) = 242 pm) and by ten O^2? anions (for Pr2 and Pr3), respectively. The latter form tetracapped trigonal antiprisms (Pr2, d(Pr2?O) = 251–253 pm and 4 × 262 pm) or bicapped distorted cubes (Pr3, d(Pr3?O) = 245–259 pm and 2 × 279 pm). The non‐binding electron pairs (“lone pairs”) at the two crystallographically different Ψ¹‐tetrahedral [SeO₃]^2? anions (d(Se⁴⁺?O^2?) = 169–173 pm) are directing towards the empty cavities between the layer‐connecting [(Pr4)O₄Cl₄]^9? units.     

Synthesis and Crystal Structure of Bis(methyltriphenylphosphonium) Hexabromotellurate(IV)‐bis{dibromoselenate(II)}, [PMePh3]2[TeBr6(SeBr2)2], the Salt of a Mixed‐valence Bromotellurate(IV)‐Selenate(II) Anion

Brown crystals of [PMePh₃]₂[TeBr₆(SeBr₂)₂] ( 1 ) were obtained when selenium and bromine (1:1) react in acetonitrile solution in the presence of tellurium(IV) bromide and methyltriphenylphosphonium bromide. The salt 1 crystallizes in the triclinic space group P1¯ with the cell dimensions a = 10.3630(14)Å, b = 11.5140(12)Å, c = 11.7605(17)Å, α = 108.643(9)°, β = 106.171(10)° and γ = 99.077(9)° (296 K). In the solid state the [TeBr₆(SeBr₂)₂]^2— anion contains a nearly regular [TeBr₆] octahedron where the four equatorial bromo ligands each have developed a bond to the Se^II atom of a SeBr₂ molecule. The contacts between the bridging bromo and the Se^II atoms of the SeBr₂ molecules are observed in the range 3.11—3.21Å, and can be interpreted as bonds of the donor‐acceptor type with the bridging bromo ligands as donors and the SeBr₂ molecules as acceptors. The Te^IV—Br distances are in the range 2.67—2.72Å, and the Se^II—Br bond lengths in coordinated SeBr₂ molecules in the range 2.33—2.34Å.     

Einkristalle des Cer(IV)–Oxotellurats(IV) CeTe2O6

Single Crystals of the Cerium(IV) Oxotellurate(IV) CeTe₂O₆ Orange‐red, coffin‐shaped single crystals of CeTe₂O₆ (monoclinic, P2₁/n; a = 703.71(5), b = 1106.32(8), c = 735.24(5) pm, β = 108.066(6)°; Z = 4) were obtained by the reaction of admixtures of cerium dioxide and tellurium dioxide (CeO₂, TeO₂; molar ratio 1 : 2) in the presence of fluxing CsCl (750 °C, 4 d) in evacuated silica tubes. The crystal structure contains eightfold coordinated Ce⁴⁺ cations, which are surrounded by irregular trigonal dodecahedra of oxygen atoms. The interconnection of these [CeO₈] polyhedra occurs via two edges (O2–O2′ and O3–O3′) with equatorial orientation relative to each other forming zigzag chains {[CeO_4/1O_4/2]^8–} which run parallel to [100] and arrange as a hexagonal packing of rods. Both crystallographically different Te⁴⁺ cations exhibit trigonal non‐planar coordination figures (ψ¹ tetrahedra) with three oxygen atoms each as a result of the stereochemical activity of the non‐binding electron pairs (“lone pairs”). They also are responsible for the necessary cross‐linkage of the anionic {[CeO₆]^8–} chains. The isotypical relationship with Ce(SeO₃)₂ therefore justifies the formulation Ce(TeO₃)₂ for CeTe₂O₆.     

Bis(p‐nitrobenzoxasulfamato) Complexes of Cadmium(II) and Mercury(II) ‐ Synthesis,Spectra, and X‐Ray Crystal Structures

The reaction of sodium benzoxasulfamate (nbs) with cadmium(II) and mercury(II) sulfate in aqueous solution yield the novel complexes [Cd(nbs)₂(H₂O)₄] (1) and [Hg(nbs)₂(H₂O)₃] ( 2 ), respectively. The complexes were characterized by elemental analyses, IR spectroscopy and X‐ray crystallography. Complex 1 is monomeric and has an octahedral arrangement in which the N‐donor nbs ligands occupy the axial positions, while the water oxygen atoms form the equatorial plane. Complex 2 is polymeric and shows a pentagonal bipyramidal arrangement achieved by the bridging of the HgN₂O₃ units through the weak interaction of the O atoms of the nitro group. The nbs ligands also occupy the axial positions of the pentagonal bipyramid, whereas three water and two nitro oxygen atoms constitute the pentagonal plane. The crystal structure packing in both crystals is achieved by the intermolecular hydrogen bonds involving water hydrogen atoms, nitro and sulfonyl oxygen atoms.     

Pniktogenidostannate(IV) mit isolierten Tetraeder‐Anionen: Neue Vertreter (E1)4(E2)2[Sn(E15)4] (mit E1 = Na,K; E2 = Ca,Sr, Ba; E15 = P,As, Sb,Bi) vom Na6[ZnO4]‐Typ und die Überstrukturvariante von K4Sr2[SnAs4]

Pnictogenidostannates(IV) with Discrete Tetrahedral Anions: New Representatives (E1)₄(E2)₂[Sn(E15)₄] (with E1 = Na, K; E2 = Ca, Sr, Ba; E15 = P, As, Sb, Bi) of the Na₆[ZnO₄] Type and the Superstructure Variant of K₄Sr₂[SnAs₄] The silvery to dark metallic lustrous compounds (E1)₄(E2)₂[Sn(E15)₄] (E1 = Na, K; E2 = Ca, Sr, Ba; E15 = P, As, Sb, Bi) were prepared from melts of stoichiometric mixtures of the elements. They crystallize in the Na₆[ZnO₄]‐type structure (hexagonal, space group: P6₃mc, Z = 2; Na₄Ca₂[SnP₄]: a = 938.94(7), c = 710.09(8) pm; K₄Sr₂[SnAs₄]: a = 1045.0(2), c = 767.0(1) pm; K₄Ba₂[SnP₄]: a = 1029.1(6), c = 780.2(4) pm; K₄Ba₂[SnAs₄]: a = 1051.3(1), c = 795.79(7) pm; K₄Ba₂[SnSb₄]: a = 1116.9(2), c = 829.2(1) pm; K₄Ba₂[SnBi₄]: a = 1139.5(2), c = 832.0(2) pm). The anionic partial structure consists of tetrahedra [Sn(E15)₄]^8– orientated all in the same direction along [001]. In the cationic partial structure one of the two cation positions is occupied statistically by alkali and alkaline earth metal atoms. Up to now only for K₄Sr₂[SnAs₄] a second modification could be isolated, forming a superstructure type with three times the unit cell volume (hexagonal, space group: P6₃cm, Z = 6; a = 1801.3(2), c = 767.00(9) pm) and an ordered cationic partial structure.