Zur Kenntnis ternärer Oxide des Bleis1: Über Na2PbO2

On Ternary Oxides Lead. The Na₂PbO₂ New obtained colourless single crystals of Na₂PbO₂ are orthorhombic [Pbcn; a=16.8₃, b=6.93₉, c=5.88₂ Å, Z=8]. Parameters were refined by least-squares [370 h01–h31; Mo– K_α, R=0.108] (parameters see text). Na₂PbO₂ shows a layer-lattice: perpendicular to (100) there follow layers with the sequence (Na_0,5Pb_0,5)ONaO(Na_0,5Pb_0,5Pb_0,5)…?(Na_0,5Pb_0,5)ONaO(Na_0,5Pb_0,5). The connexion of neighboured cation-layers of this type are connected in a way, that the lone-paired electrons of Pb²⁺ are bridged with Na+. The MADELUNG part of lattice energie (MAPLE) is calculated and discussed.     

Crystal Chemistry of the M11+,2+–M22+,3+–(H)‐Arsenites: the First Cadmium(II) Arsenite,Na4Cd7(AsO3)6

The crystal structures among M1–M2–(H)‐arsenites (M1 = Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Ca²⁺, Sr²⁺, Ba²⁺, Cd²⁺, Pb²⁺; M2 = Mg²⁺, Mn^2+,3+, Fe^2+,3+, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺) are less investigated. Up to now, only the structure of Pb₃Mn(AsO₃)₂(AsO₂OH) was described. The crystal structure of hydrothermally synthesized Na₄Cd₇(AsO₃)₆ was solved from the single‐crystal X‐ray diffraction data. Its trigonal crystal structure [space group R$\bar{3}$ , a = 9.5229(13), c = 19.258(4) Å, γ = 120°, V = 1512.5(5) ų, Z = 3] represents a new structure type. The As atoms are arranged in monomeric (AsO₃)^3– units. The surroundings of the two crystallographically unique sodium atoms show trigonal antiprismatic coordination, and two mixed Cd/Na sites are remarkably unequal showing tetrahedral and octahedral coordinations. Despite the 3D connection of the AsO₃ pyramids, (Cd,Na)O_x polyhedra and NaO₆ antiprisms, a layer‐like arrangement of the Na atoms positioned in the hexagonal channels formed by CdO₄ deformed tetrahedra and AsO₃ pyramids in z = 0, 1/3, 2/3 is to be mentioned. These pseudo layers are interconnected to the 3D network by (Cd,Na)O₆ octahedra. Raman spectra confirmed the presence of isolated AsO₃ pyramids.     

Zur Kristallstruktur von Li8PbO6 [1]

On the Structure of Li₈PbO₆ For the first time single crystals of Li₈PbO₆ have been prepared by heating of mixtures of Na₂PbO₃ and Li₂O [Ag-cylinders, 650°C, 150 d]. The structure [382 I₀(hkl), four circle diffractometer PW 1100, ω/2Θ-scan, MoKα, R = 3.07%, R_w = 3.00%, space group R3 ; a = 555.09(4), c = 1564.13(17) pm, D_x = 4.28 g · cm^?3, D_pyk = 4.24 g · cm^?3, Z = 3] is characterized by the motive of a hexagonal-closed O^2? packing. Half of the octahedral sites are occupied by Pb⁴⁺ and Li⁺ and half of the tetrahedral sites only by Li⁺. The Madelung Part of Lattice Energy, MAPLE, and the Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, are calculated.     

Über quaternäre Oxoplumbate(IV). Zur Kenntnis von Rb3NaPbO4

On Quaternary Oxoplumbates(IV). On Rb₃NaPbO₄ For the first time, Rb₃NaPbO₄ has been prepared by annealing mixtures of Na₂PbO₃ and RbO_0.84 with Rb:Na:Pb = 4:2:1 [nonhermetic Ag-cylinders, sealed under vacuum in Duran-glass ampoule, 480°C, 180 d (single crystals)]. The colourless crystals are of squatted shape. The structure determination [2943 symmetry independent hkl, four-circle-diffractometer PW 1100 (Fa. Philips), ω-2Θ-scan, AgKα, R = 8.64%, R_W = 6.59%, absorption not considered] confirms the space group P2₁/c with a = 1101.79(26), b = 662.66(11), c = 1115.01(30) pm, β 112.027(21)°. The structure is characterized by isolated [PbO₄]-tetrahedra and [Na₂O₆]-tetrahedra-doubletts, C.N. 5 and 7 for Rb⁺. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these via Mean Effective Ionic Radii, MEFIR, are calculated.     

Über ternäre Oxide des Bleis: Zur Kenntnis von Na6PbO4

On Ternary Oxides of Lead. The Na₆PbO₄ New obtained Na₆PbO₄ (colourless to pale yellow), is due to single crystal datas cubic, I43m, with a=11,0₁ Å and Z=8. Parameters were refined by least-squares (705 h01–h51, Mo–K_α) Ra=0.082, R′=0.091 (Parameters see text). In an ordered derivative of Na₂O-structure, there are according to [O′′Na₄Na₄] [O′(PbO₃″′)₄] “isolated” Pb₄O₁₃-groups, which are connected with each other by Na′ and Na″. The MADELUNG part of lattice energy (MAPLE) is calculated and discussed.     

Drei Alkalimetall‐Erbium‐Thiophosphate: Von der Schichtstruktur bei KEr[P2S7] zur dreidimensionalen Vernetzung in NaEr[P2S6] und Cs3Er5[PS4]6

Three Alkali‐Metal Erbium Thiophosphates: From the Layered Structure of KEr[P₂S₇] to the Three‐Dimensional Cross‐Linkage in NaEr[P₂S₆] and Cs₃Er₅[PS₄]₆ The three alkali‐metal erbium thiophosphates NaEr[P₂S₆], KEr[P₂S₇], and Cs₃Er₅[PS₄] show a small selection of the broad variety of thiophosphate units: from ortho‐thiophosphate [PS₄]^3? and pyro‐thiophosphate [S₃P–S–PS₃]^4? with phosphorus in the oxidation state +V to the [S₃P–PS₃]^3? anion with a phosphorus‐phosphorus bond (d(P–P) = 221 pm) and tetravalent phosphorus. In spite of all differences, a whole string of structural communities can be shown, in particular for coordination and three‐dimensional linkage as well as for the phosphorus‐sulfur distances (d(P–S) = 200 – 213 pm). So all three compounds exhibit eightfold coordinated Er³⁺ cations and comparably high‐coordinated alkali‐metal cations (CN(Na⁺) = 8, CN(K⁺) = 9+1, and CN(Cs⁺) ≈ 10). NaEr[P₂S₆] crystallizes triclinically ( ; a = 685.72(5), b = 707.86(5), c = 910.98(7) pm, α = 87.423(4), β = 87.635(4), γ = 88.157(4)°; Z = 2) in the shape of rods, as well as monoclinic KEr[P₂S₇] (P2₁/c; a = 950.48(7), b = 1223.06(9), c = 894.21(6) pm, β = 90.132(4)°; Z = 4). The crystal structure of Cs₃Er₅[PS₄] can also be described monoclinically (C2/c; a = 1597.74(11), b = 1295.03(9), c = 2065.26(15) pm, β = 103.278(4)°; Z = 4), but it emerges as irregular bricks. All crystals show the common pale pink colour typical for transparent erbium(III) compounds.     

Über Oxocadmate: K2Cd2O3

New obtained is K₂Cd₂O₃ (brownish red), which – according to single crystal work [487 h 01–h 41, Mo? Kα, R = 9.7₃%, R′ = 10.7₆%] – crystallises monoclinic with a = 6.41₇, b = 6.72₃, c = 6.58₆ Å, β = 116.0° in P2₁/c–C [K⁺, Cd²⁺ and O(1)^2? in 4(e), O(2)^2? in 2(a)] and is isotypic with Na₂Zn₂O₃. [Parameters see text]. The Madelung Part of Lattice Energy is calculated and discussed.     

Zwei Tetrachlorothiotantalate: [Na‐15‐Krone‐5][TaSCl4 · Dioxan] und [Na‐15‐Krone‐5]2[(TaSCl4)2Dioxan] · S8

Two Tetrachlorothiotantalates: [Na‐15‐crown‐5][TaSCl₄ · dioxane] and [Na‐15‐crown‐5]₂[(TaSCl₄)₂dioxane] · S₈ During the reaction of Na₂S₄, TaCl₅ and 15‐crown‐5 in dichloromethane the crown ether partly suffers degradation to 1,4‐dioxane. Aside from sulfur, [Na‐15‐crown‐5][TaSCl₄ · dioxane] was the first product obtained. It crystallizes in the monoclinic space group P2₁/n with a = 1066.1, b = 1781.3, c = 1258.3 pm, β = 97.14°, Z = 4. In the [TaSCl₄ · dioxane]^– ion a dioxane molecule is loosely bonded to a square‐pyramidal TaSCl₄^– unit; two chlorine atoms are in contact with an Na⁺ ion. Upon standing with the mother liquor [Na‐15‐crown‐5]₂[(TaSCl₄)₂dioxane] · S₈ was formed. It crystallizes in the monoclinic space group C2/m; a = 1768.5, b = 1084.0, c = 1517.3 pm, β = 118.46°, Z = 4. In this case a dioxane molecule is coordinated with two TaSCl₄^– units. The [(TaSCl₄)₂ · dioxane]^2– ions and S₈ molecules alternate in the stacking direction b.     

Zur Konstitution von ‚KPbO2’︁

On the Constitution of ‘KPbO₂’ Transparent, orangered single crystals of K₂Pb₂O₄ have been obtained by heating mixtures of K₂O₂ and PbO (K:Pb = 1:1) [Ag-cylinders, 560°C, 40 d, after cooling (15°C/h)]. The space group is P1 , a = 1295.94(9), b = 753.35(7), c = 697.12(8) pm, α = 118.00(1)°, β = 106.15(1)°, γ = 93.44(1)°, Z = 4, d_x = 6.573 und d_pyk = 6.54 g · cm³. The structure is characterized by rutilanalogous chains of edge-connected [PbO₆] octahedra along [001] according to [PbO_4/2O_2/1] = PbO₄. On both sides of such a chain there are respectively three O^2?, which belong to two octahedra, alternating capped with Pb²⁺ or not capped, corresponding to [PbO₄]Pb₂[PbO₄]□₂… = Pb₂O₄. Those capped chains are held together by K(1)…K(4), each of them with C.N. 6. The order of the chains corresponds to the motive of a closest packing. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, are calculated and discussed.     

On the proton-acceptor properties of [TeMo6O24]6− in Na4(NH4)2[TeMo6O24] · 16H2O

Colourless triclinic single crystals of Na₄(NH₄)₂[TeMo₆O₂₄] · 16H₂O were grown in aqueous solution (space group P1 , a = 1 075.3(1), b = 1 074.2(1), c = 1 089.8(1) pm, = 96.259(9), β = 118.556(7), γ = 113.355(8)°, Z = 1, 295 K, 311 parameters, 3 689 reflections, R_g = 0.0197). There are two crystallographically independent Na⁺ cations. Na(1) is coordinated octahedrally by four water molecules and two oxygen atoms of the centrosymmetric [TeMo₆O₂₄]^6? anion. Na(2) is bound to five water molecules in a considerably distorted trigonally bipyramidal fashion. These bipyramids are linked with NH₄⁺ by hydrogen bonds to yield centrosymmetric cluster cations consisting of two NH₄⁺ and two Na(H₂O)₅⁺ each. Hydrogen bonds envolving all except one (O(10)) of the oxygen atoms of the [TeMo₆O₂₄]^6? anion as almost equivalent proton acceptors regardless of their bonding mode to Te and Mo, respectively, establish further connections to NH₄⁺ and the water of crystallization.     

Ein neuer Perowskit mit Lücken im Anionenteil: Ba4[Na2W2O11]

A New Perowskite with Deficiencies in the Oxygen Part: Ba₄[Na₂W₂O₁₁] For the first time colourless single crystals of Ba₂NaWO_5.5 were prepared by reaction of Na₄WO₅ [2] and ?BaO₂”? [Ba:Na:W = 4:4:1, Ni-cylinder, 725°C, 35 d]. Single crystal data [432 of 505 I₀ (hkl), Four-circle-diffractometer Siemens AED2, MoKα , R = 6.1%, R_w = 5,6%] verify the space group P mmm with a = 579.16(8), b = 580.85(8), c = 859.4(1) pm, Z = 1. The structure is based upon the CaTiO₃-type of structure. Ba²⁺ take the place of Ca²⁺ meanwhile Ti⁴⁺ is substituted alternately by W⁶⁺ and Na⁺. Complete occupation of all lattice positions would lead to a deficite of positive charge. This is compensate by deficiencies in the oxygen part of the lattice. Related to [Na(1)₁Na(2)₁W(1)₁W(2)₁O(1)₄O(2)₂O(3)₂O(4)₃] these deficiencies are statistically distributed on O(4). Structural relations are deduced by Schlegel-Diagrams. The Madelung Part of Lattice Energie, MAPLE, Effektive Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, are calculated and discussed.     

Cation Effect on Formation of Preyssler‐type 30‐Tungsto‐5‐phosphate: Enhanced Yield of Na‐encapsulated Derivative and Direct Synthesis of Ca‐ and Bi‐Encapsulated Derivatives

The effect of cations in a reaction mixture for the preparation of the Preyssler‐Jeannin‐Pope type 30‐tungsto‐5‐phosphate [P₅W₃₀O₁₁₀Na]^14– is investigated. Reaction of phosphate and tungstate with a P/W ratio of ca. 3.9 in an acidic aqueous solution without cations selectively leads to the Dawson‐type 18‐tungsto‐2‐phosphate, [P₂W₁₈O₆₂]^6–. Amongst all the alkali cations, only Na⁺ allows formation of the Preyssler‐type polyanion [P₅W₃₀O₁₁₀Na]^14–, with an encapsulated Na⁺ ion, and the product yield can be improved by increasing Na⁺ amount. The presence of Li⁺ ions instead results in the Dawson‐type polyanion [P₂W₁₈O₆₂]^6–, whereas K⁺, Rb⁺, and Cs⁺ selectively result in the Keggin‐type polyanion [PW₁₂O₄₀]^3–. An improved synthetic procedure for the Na⁺‐encapsulated Preyssler‐ion leading to a higher isolated yield is presented. Furthermore, addition of Ca²⁺ and Bi³⁺ compounds allows formation of the Ca²⁺‐ and Bi³⁺‐encapsulated Preyssler‐type polyanions, [P₅W₃₀O₁₁₀Ca]^13– and [P₅W₃₀O₁₁₀Bi]^12–, respectively. Furthermore, single‐crystal XRD structure of the Bi³⁺‐encapsulated Preyssler‐type polyanions, [P₅W₃₀O₁₁₀Bi]^12–, is presented for the first time.     

Poly[tetrasodium(I)‐tetra‐μ2‐bis(butane‐1,4‐diyldioxy)borato‐μ2‐1,4‐butane­diol]

In the title compound, [Na₄(C₈H₁₆BO₄)₄(C₄H₁₀O₂)]_n, there are two coordination types for the four independent Na⁺ cations: two Na⁺ cations bond to six diolate O atoms [Na—O = 2.305 (2)–2.609 (2) Å], while the other two are five‐coordinate via one 1,4‐butane­diol [2.289 (2) and 2.349 (3) Å] and four diolate O atoms [2.295 (2)–2.408 (2) Å]. Corresponding to this, there are three‐ and four‐coordinate diolate O atoms, the latter bridging Na atoms. The 1,4‐butane­diol mol­ecules lie on inversion centres. The boron stereochemistry shows minor local perturbations from its usual tetrahedral state [B—O = 1.457 (4)–1.503 (4) Å]. The resulting polymer packs as sheets parallel to the (10) plane crosslinked by the butane­diol mol­ecules. The structure was solved using data from a multiple crystal.     

Über Perrhenate. 3 Zum Aufbau des Mesoperrhenates Na3[ReO5]

About Perrhenates. 3 On the Structure of the Mesoperrhenate Na₃[ReO₅] By tempering powder samples (prepared from mixtures of binary oxides: Na₂O₂/ReO₂ and Na₂O/ReO₃ respectively, Na : Re = 3 : 1, Ar and O₂ atmosphere respectively, 400–450°C, corundum boat) in a closed Ag cylinder (500–550°C, 10 d) yellow single crystals of Na₃ReO₅, sensitive to moisture, were grown. The compound crystallizes trigonal, space group P3₁, P3₂ respectively, with a = 5.544(1), c = 13.580(7) Å, Z = 3, d_rö. = 4.62 g/cm³. The crystal structure [4-circle diffractometer data, 1091 I₀(hkl), AgKα, R = 6.14, R_w = 6.08%] is characterized by “isolated” bipyramids ReO₅. Na⁺ ions are occupying all the tetrahedral (Na2, Na3) and octahedral (Na1) holes of the pseudocubic face centred (c/a = 2.441) Re part of the lattice; resulting in a Na₃Re kation framework corresponding to the Li₃Bi type of structure. Effective Coordination Numbers (ECoN), the Madelung Part of Lattice energy (MAPLE) and the charge distribution (CHARDI) are computed and discussed.     

Neue Oxoplumbate(II) A2PbO2 (A = K,Rb, Cs) mit zweikernigen Gruppen [OPbO2PbO]

New Oxoplumbates(II) A₂PbO₂ (A = K, Rb, Cs), with Binuclear Groups [OPbO₂PbO] Unknown K₂PbO₂, Rb₂PbO₂ and Cs₂PbO₂ (yellowish powder, yellowish transparent single crystals, respectively) have been prepared, The compounds crystallize triclinic with a = 10.90₁ Å, b = 7.60₆ Å, c = 7.32₈ Å, α = 119.3₅°, β = 88.4₂°, γ =117,7₃°, (K₂PbO₂); a = 10.90₇ Å, b = 8.51₀ Å, c = 7.81₅ Å, α = 124.0₀°, β = 84.9₇°, γ = 120.6₈° (Rb₂PbO₂) and a = 11.64₄ Å, b = 8.90₅ Å, c = 8.04₀ Å, α = 123.3₂°, β = 85.7₀°, γ = 120.4₉° Z = 4, space group P1 -C/_i¹. For K₂PbO₂ we find R = 8.6₅% and R_w = 9.3₂% (2283 independent reflections). Parameters see text. There are isolated [Pb₂O₄]groups, which are connected in a complicated way by mutual K⁺ ions forming layers. The Madelung Part of the Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these by means of mean Fictive Ionic Radii, MEFIR, are calculated and discussed.     

Stabilization of Highly Reactive “Naked Anions”: Synthesis,Crystal Structure and Vibrational Spectrum of [Na(12‐crown‐4)2]2 [P2S6] · CH3CN

The novel thiodiphosphate, [Na(12‐crown‐4)₂]₂[P₂S₆] · CH₃CN, bis[di(12‐crown‐4)sodium] hexathiodiphosphate(V) acetonitrile solvate ( 1 ) has been synthesized by the reaction of Na₂[P₂S₆] with 12‐crown‐4 in dry acetonitrile. The title compound crystallizes in the tetragonal space group P4₂/mbc (no. 135), with a = 15.184(1) Å, c = 21.406(2) Å and Z = 4 and final R1 = 0.0671 and wR2 = 0.0809. The crystal structure is characterized by discrete sodium‐bound crown‐ether sandwich cations, [Na(12‐crown‐4)₂]⁺ and [P₂S₆]^2? ions with D_2h symmetry. Sodium ion is coordinated by the eight oxygen atoms of two crown‐ether molecules to form a square antiprisma. Solvent molecules of CH₃CN are statistically disordered. Distances and angles of the [P₂S₆]^2? unit are similar to those in [K(18‐crown‐6)]₂ [P₂S₆] · 2 CH₃CN, and in K₂[P₂S₆] and Cs₂[P₂S₆]. The FT‐Raman and FT‐IR spectrum of the title compound has been recorded and interpreted, especially with respect to the P₂S₆ group and in comparison to the few known metal hexathiodiphosphates(V).     

Cyanidosilicates—Synthesis and Structure

Starting from fluoridosilicate precursors in neat cyanotrimethylsilane, Me₃Si?CN, a series of different ammonium salts [R₃NMe]⁺ (R=Et, ⁿPr, ⁿBu) with the novel [SiF(CN)₅]^2? and [Si(CN)₆]^2? dianions was synthesized in facile, temperature controlled F^?/CN^? exchange reactions. Utilizing decomposable, non‐innocent cations, such as [R₃NH]⁺, it was possible to generate metal salts of the type M₂[Si(CN)₆] (M⁺=Li⁺, K⁺) via neutralization reactions with the corresponding metal hydroxides. The ionic liquid [BMIm]₂[Si(CN)₆] (m.p.=72 °C, BMIm=1‐butyl‐3‐methylimidazolium) was obtained by a salt metathesis reaction. All the synthesized salts could be isolated in good yields and were fully characterized.     

Synthesen und Schwingungsspektren der homoleptischen Acetonitrilkomplex-Kationen [Au(NCCH3)2]+, [Pd(NCCH3)4]2+, [Pt(NCCH3)4]2+ und des Adduktes CH3CN · SbF5. Kristallstrukturen der Salze [M(NCCH3)4][SbF6]2 · CH3CN,M = Pd,Pt

The Syntheses and Vibrational Spectra of the Homoleptic Metal Acetonitrile Cations [Au(NCCH₃)₂]⁺, [Pd(NCCH₃)₄]²⁺, [Pt(NCCH₃)₄]²⁺, and the Adduct CH₃CN · SbF₅. The Crystal and Molecular Structures of [M(NCCH₃)₄][SbF₆]₂ · CH₃CN, M = Pd or Pt Solvolyses of the homoleptic metal carbonyl salts [M(CO)₄][Sb₂F₁₁]₂, M = Pd or Pt, in acetonitrile leads at 50 °C both to complete ligand exchange for the cations as well as to a conversion of the di-octahedral anion [Sb₂F₁₁]^– into [SbF₆]^– and the molecular adduct CH₃CN · SbF₅ according to: [M(CO)₄][Sb₂F₁₁]₂ + 7 CH₃CN → [M(NCCH₃)₄][SbF₆]₂ · CH₃CN + 2 CH₃CN · SbF₅ + 4 CO M = Pd, Pt The monosolvated [M(NCCH₃)₄][SbF₆]₂ · CH₃CN are obtained as single crystals from solution and are structurally characterized by single crystal x-ray diffraction. Both salts are isostructural. The cations are square planar but the N–C–C-sceletial groups of the ligands depart slightly from linearity. The new acetonitrile complexes as well as [Au(NCCH₃)₂][SbF₆] and the adduct CH₃CN · SbF₅ are completely characterized by vibrational spectroscopy.     

Natriumkomplexe mit Salicylideniminen: Synthesen,Strukturen, CO2‐Aufnahme und Carboxylierung von 2‐Fluorpropiophenon bzw. Estronmethylether

Chiral salicylidenphenethylamines (R)‐HA or (S)‐HA , 2‐salicylidenfurfuryl‐imines HB , and 2‐salicylidenaminoethanol HC react with sodium hydride or sodium hexamethyldisilylamide to form the sodium complexes [Na(R)‐A] ₄ · 0,5 Et ₂ , [Na(S)‐A] ₄ · 0,5 Et ₂ O (1) , [NaB] ₄ · 0,5 Ph‐Me (2) and [(dme)NaC] ₄ (3) . In the presence of 18‐crown‐6 the complex [Na(18‐crown‐6)(thf) ₂ ] ₂ [Na ₂ (C)] ₄ · THF (4) can also be isolated. The crystal structure analyses of both 1 and 2 show that heterocubane structures with a Na₄O₄ frame work are formed. Additionally, the imine nitrogen atom is bonded at the Na atom which has the coordination number 4 in 1 . Additional coordination of the furfuryl oxygen atom results in the coordination number five for the sodium atom in 2 . In 3 which is also a tetramer, two Na₂O₂ units are connected via two imino‐ethanol bridges Na(1)‐N(=CH‐phenolat)‐CH₂CH₂‐OH‐Na(2A). The crystal structure analysis displays that 4 is an ionic compound consisting of two [(thf)₂Na(18‐crown‐6)]⁺ cations and the dinuclear dianion [Na ₂ (C) ₄ ] ^2? . Both 1 and 2 are carboxylation reagents which transfer CO₂ to 2‐fluoropropiophenone. 1 is more active than 2 , but 3 and 4 are inactive.     

The Sodium Antimony Telluridogermanate(III) Na9Sb[Ge2Te6]2

Systematic studies in the quaternary system Na/Ge/Sb/Te yielded the new compound Na₉Sb[Ge₂Te₆]₂. Its crystal structure is isotypic to Na₉Sb[Ge₂Se₆]₂ (space group C2/c with a = 9.541(2), b = 26.253(7), c = 7.5820(18) Å and β = 122.233(15)°, Z = 2). The structure is characterized by Ge–Ge dumbbells that are octahedrally coordinated by Te, forming ethane‐like [Ge₂Te₆]^6– anions. Cation sites are occupied by Na⁺ as well as shared by Na⁺ and Sb³⁺. Na₉Sb[Ge₂Te₆]₂ is formally obtained from the reaction of one equivalent Na₈[Ge₄Te₁₀] and one equivalent NaSbTe₂. In contrast to members of the metastable solid solution series (NaSbTe₂)_1–x(GeTe)_x, Na₉Sb[Ge₂Te₆]₂ is a thermodynamically stable compound. It is a semiconductor with a bandgap of 1.51 eV.