Zur kenntnis ‚Kationen-reicher’︁ Tantalate und Niobate Über Na5TaO5 und Na5NbO5

On Tantalates and Niobates ‘rich in Cations’. On Na₅TaO₅ and Na₅NbO₅ Colourless, transparent single crystals of Na₅TaO₅ [annealed mixtures of Na₂O, Li₂O, and Ta₂O₅, Na : Li : Ta = 6.6 : 1.1 : 1, Ni-cylinder, 1000°C, 75 d] as well as Na₅NbO₅ [annealed mixtures of Na₂O, Li₂O, and Nb₂O₅, Na : Li : Nb = 6.6 : 1.1 : 1, Ni-cylinder, 1000°C, 75 d] have been prepared. Single crystal data show that both isotypic oxides represent a deformed variant of the NaCl-type of structure [Na₅TaO₅: 1154 from 1250 I₀ (hkl), four-cycle diffractometer Philips PW 1100, ω2-θ scan, Ag? Kα , R = 4.88%, space group c2/c with a = 629.3(1) pm, b = 1025.4(2) pm, c = 1004.6(2) pm, b? 106.80(2)°, z = 4 and Na₅NbO₅: 998 from 1247 I₀(hkl), four-cycle diffractometer Philips PW 1100, ω-2θ scan, Ag? Kα , R = 8.58% and R_w = 7.67%, space group C2/2 with a = 629.1(1) pm, b = 1024.4(2) pm, c = 1004.2(2) pm, b? = 106.80(2)°, Z = 4]. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, the latter derived from Mean Effective Fictive Ionic Radii, MEFIR, as well as Charge Distribution, CHARDI, are calculated.     

Neue Oxoferrate(III). Na2Li3[FeO4] und K2Li3[FeO4]

New Oxoferrates (III). Na₂Li₃[FeO₄] and K₂Li₃[FeO₄] . Na₂Li₃[FeO₄] and K₂Li₃[FeO₄] (transparent, pink or light yellow single crystals) have been prepared by heating mixtures of the oxides (Na:Li:Fe = 2.2:3.3:1; Ag-tube, 720°C, 27 d or K:Li:Fe = 2.2:3.3:1; analogous, 700°C, 40 d). Na₂Li₃[FeO₄] is isotypic with Na₂Li₃[GaO₄] (a = 832.2(1), b = 796.0(1), c = 656.3(1)pm, Pnnm) and K₂Li₃[FeO₄] with K₂Li₃[GaO₄] (a = 557.7(1), b = 880.6(1), c = 1101.8(2)pm, β = 111.51(2)°, P2₁/c). Four cycle diffractometer data: MoK_α, 525 out of 686 I₀(hkl), R = 9.36%, R_w = 5.97% or 1424 out of 1424 I₀(hkl), R = 8.45%, R_w = 5.66%. Parameters see text. The structures are characterized by calculations of the Madelung Part of Lattice Energy, MAPLE. The Effective Coordination Numbers, ECoN, which are calculated by means of Mean Fictive Ionic Radii, MEFIR, are compared with the analogous gallates.     

Ein neues Inoferrat(III): K2 Na4[(FeO3)2]

A New Inoferrate(III): K₂Na₄[(FeO₃)₂] For the first time amber coloured single crystals of K₂Na₄[(FeO₃)₂] were prepared by heating well ground mixtures of KFeO₂ and Na₂O (molar ratio Na₂O:KFeO₂= 1.4:1.0; ?Ag-tube”?, 500 °C/29 d, 400 °C/5 d): Spacegroup Pnma with a = 650.50(6) pm, b = 619.62(5) pm, c = 1020.64(12) pm. K₂Na₄[(FeO₃)₂] is isotypic to K₂Na₄[(GaO₃)₂] [2]. The structure has been determined by four-circle-diffractometer data [Mo—Kα , 982 of 982 unique I₀(hkl), R = 4.56%, R_w = 4.56% (no weight)]; parameters as given in the text. The Madelung Part of Lattice Energy, MAPLE, and the Effective Coordination Number, ECoN, these via Mean Fictive Ionic Radii, MEFIR will be calculated and discussed.     

Zur Existenz polynärer Oxide der Alkalimetalle mit einwertigen Cobalt bzw. Nickel [1, 2]

On the Existence of Polynary Oxides of the Alkali Metals with Monovalent Cobalt and Nickel For the first time we obtained RbNa₂NiO₂, KNa₂NiO₂, Na₃CoO₂ and K₃CoO₂ [RbNa₂NiO₂: Na₂NiO₂ + Rb₂O, Rb:Ni = 1.8:1, 600°C, 28 d, Ni-tube; KNa₂NiO₂: Na₂NiO₂ + K₂O, K:Ni = 1.8:1, 600°C, 20 d, Ni-tube; Na₃CoO₂: Na₂O + CoO: Na:Co = 8.8:1, 500°C, 20 d, Co-tube; K₃CoO₂: K₂O + CoO: K:Co = 4.4:1, 550°C, 20 d, Co-tube]. According to X-ray structure analysis of single crystals monovalent Co and Ni is present [always four-circle-diffractometer data, MoKα -radiation; RbNa₂NiO₂: AED 2, all 163 I_o(hkl), R = 3.4%, R_w = 1.9%, I4/mmm, a = 461.7(1), c = 973.6(3) pm, Z = 2; KNa₂NiO₂: AED 2, all 341 I_o(hkl), R = 5.6%, R_w = 3.5%, Cmma, a = 1 048.5(3), b = 626.8(1), c = 621.9(1) pm, Z = 4; Na₃CoO₂: PW 1 100, 517 of 568 I_o(hkl), R = 2.9%, R_w = 1.8%, P4₂/mnm, a = 940.0, c = 464.5 pm, Z = 4; K₃CoO₂: PW 1 100, all 940 I_o(hkl), R = 5.0%, R_w = 3.9%, Pnma, a = 1 190.0, b = 730.4, c = 604.1 pm, Z = 4]. All samples are red, the single crystals transparent. Two O^2? coordinate Ni¹⁺ and Co¹⁺, respectively, like a dumb-bell. Mean Fictive Ionic Radii, MEFIR, and Effective Coordination Numbers, ECoN, and Madelung part of lattice energy, MAPLE, are given.     

Das erste Oxothallat(III) vom Formeltyp AA4′[MO4]: CsK4[TlO4]

The First Oxothallate(III) with the Formula Type AA₄′[MO₄]: CsK₄[TlO₄] For the first time CsK₄[TlO₄] was obtained by heating intimate mixtures of K₂O, CdO and CsTl (molar ratio 3.1:1.0:1.0) in closed Ag-cylinders (25 days, 450°C) in form of yellow, transparent single crystals. The structure determination by four circle diffractometer data (MoKα, 1922 out of 2 094 I_o(hkl), R = 2.98, R_w = 2.49) confirms the space group Pbca with lattice constants a = 1 192.1 pm; b = 685.7 pm; c = 2 143.5 pm; Z = 8. The structure is isotypic with Na₅[GaO₄]. The Madelung Part of Lattice Energy, MAPLE, the Mean Fictive Ionic Radii, MEFIR, Effective Coordination Numbers, ECoN, and Charge Distribution, CHARDI, are calculated.     

Die ersten Oxocobaltate(II) mit zweikernigem Anion: Rb2Na4[Co2O5] und K2Na4[Co2O5]

The First Oxocobaltate(II) with Dinuclear Anion: Rb₂Na₄[Co₂O₅] and K₂Na₄[Co₂O₅] By heating of well ground mixtures of the binary oxides [A₂O, Na₂O, ?CoO”?, A:Na:Co = 1.00:2.00:1, (A = K, Rb); Ag-tube, 600°C, 14 d] we obtained Rb₂Na₄[Co₂O₅] and K₂Na₄[Co₂O₅] rough, transparent, red single crystals. We find a new type of structure with the anion [O₂CoOCoO₂]^6?. Space group P4₂/mnm; a = 634.4 pm, c = 1030.3 pm, Z = 2 (A = K) a = 647.6 pm, c = 1021.1 pm, Z = 2 (A = Rb); four-circle diffractometer data; MoKα -radiation; 360 from 364 I₀(hkl), R = 4.34%, R_w = 3.54% (A = K); 361 from 366 I₀(hkl), R = 6.54%, R_w = 2.70% (A = Rb). The anion is planar, the CN of Co is 3. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, are calculated and discussed.     

Ein neues Oxoberyllat: K2Na4[O2BeOBeO2]

On K₂Na₄[O₂BeOBeO₂] For the first time colourless single crystals of K₂Na₄[Be₂O₅] which are isotypic with K₂Na₄[Co₂O₅] [2] and Rb₂Na₄[Co₂O₅] have been prepared by heating e.g. a well ground mixture of K₂O, Na₂O and BeO (K:Na:Be = 2.2:4.4:2; 750°C; 21 d; Ni-tube). The crystal structure was solved by four-circle diffractometer data [Siemens AED 2; 389 I_o(hkl); space group P4₂/mnm; Z = 2; a = 595.17(4) pm, c = 1 002.66(9) pm; R = 4.1%; R_w = 2.3%]. Mean Fictive Ionic Radii, MEFIR, Effective Coordination Numbers, ECoN, the Madelung Part of Lattice Energy, MAPLE, and the charge distribution are calculated.     

Ein neuer Strukturtyp bei Oxoiridaten mit quadratisch-planaren [IrO4]4−-Gruppen: K2Na2[IrO4], ein Raumnetz [Na2IrO4] mit Kanälen. (Mit einer Anmerkung zu Rb2Na2[IrO4])

A New Type of Structure in Oxoiridates with Square-planar Groups [IrO₄]^4?: K₂Na₂[IrO₄], a Network [Na₂IrO₄] with Channels (With a Remark on Rb₂Na₂[IrO₄]) For the first time magnificent dark red cuboid single crystals of K₂Na₂[IrO₄] were prepared by annealing intimate mixtures of a) KO_0.51, Na₂O₂, IrO₂ and Ir-powder (molar proportions 3.02 : 1.40 : 1.00 : 1.00; Ag-bomb, 740°C, 54 d) and of b) KO_0.51, Na₂O and IrO₂ (molar proportions K : Na : Ir = 2.20 : 2.20 : 1.00; Ag-bomb, 760°C, 57 d) respectively. The oxide crystallizes mP36, space group P2₁/c with a = 600.35(6) pm, b = 1111.2(1) pm, c = 933.0(1) pm and β = 113.14(1)°. Structure determination via four-circle diffractometer data (Siemens AED 2, Mo-Kα-Radiation) for all 2347 unique reflexions (merged from 9397 I_o(hkl) gave R = 0.0357 and R_w = 0.0340. K₂Na₂[IrO₄] crystallizes in a new type of structure. The oxide is antiferromagnetic as magnetic measurements showed (T_N = 32 K, Θ = ?60.2 K (single crystals) and ?49.2 K (powder) respectively, μ = 3.06 μ_B (single crystals) and 2.93 μ_B (powder) respectively). Effective coordination numbers ECoN, mean fictive ionic radii MEFIR and the Madelung part lattice energy MAPLE as well as the charge distributions CHARDI and CHARDINO are calculated and discussed.     

Oxydation intermetallischer Phasen: K4{Na2[Tl2O6]} aus NaTl und K2O2

Oxidation of Intermetallic Phases: K₄{Na₂[Tl₂O₆]} from NaTl and K₂O₂ The hitherto unknown K₄{Na₂[Tl₂O₆]} was prepared in form of transparent, yellow single crystals from NaTl and KO_1,08 (molar ratio 1:1.3; sealed Ag-cylinder; 450°C, 30 d). The structure determination (four-circle diffractometer, MoKα, 1 280 out of 1 523 I_o(hkl), R = 5.75%, R_w = 4.58%) confirms the space group P2₁/c with a = 641.3 pm, b = 691.1 pm, c = 1188.5 pm, β = 95.69° and Z = 2. As characteristic building units of the structure there are doubles of tetrahedra of [Tl₂O₆] and [Na₂O₆]. The compound is isotypic with Cs₆[In₂O₆] and Rb₆[Tl₂O₆]. The Madelung Part of Lattice Energy, MAPLE, the Mean Fictive Ionic Radii, MEFIR, Effective Coordination Numbers, ECoN, and Charge Distribution, CHARDI, 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.     

Na4SeO5, ein neues Pentaoxoselenat(VI) – Synthese,Charakterisierung und Vergleich mit isotypem Na4MoO5

Na₄SeO₅, a Novel Pentaoxoselenate(VI) – Synthesis, Charakterisation, and Comparison with Na₄MoO₅ Na₄SeO₅ was prepared by high pressure solid state reaction at 500 °C and at a hydrostatic pressure of 2.5 Gpa from a mixture of Na₂O and Na₂SeO₄ in silver crucibles and Na₄MoO₅ by solid state reaction at 450 °C from a mixture of Na₂O and MoO₃. The crystal structures of both new compounds were solved and refined using X‐ray powder methods (Profilematching Na₄SeO₅: P1, a = 988.3(1), b = 988.4(1), c = 558.6(1) pm, α = 96.25(1)°, β = 96.24(1)°, γ = 113.41(1)°, R_p = 0.0783, R_wp = 0.1037. Profilematching Na₄MoO₅: P1, a = 999.5(1), b = 1002.0(1), c = 565.1(1) pm, α = 96.54(1)°, β = 96.29(1)°, γ = 113.35(1)°, R_p = 0.0623, R_wp = 0.0867). Both compounds contain novel XO₅^4– anions of approximately tetragonal pyramidal shape. The crystal structures are consistent with spectroscopic data (IR, Raman).     

Neuartige Mäander mit Co3+ und Au3+: Na4[AuCoO5] = Na8 [(O2/2(CoO)O2AuO2/2)2]

Novel meander with Co³⁺ und Au³⁺: Na₄[AuCoO₅] = Na₈ ¹∞ [(O_2/2 (CoO)O₂AuO_2/2)₂] By “reaction with the wall” we obtained for the first time transparent brown single crystals of Na₄[AuCoO₅] while heating intimate mixtures of Co₃O₄, Na₂O₂, and K₂O₂ (Co: Na: K = 1.00:4.91:2.20; 650°C/44d) in a sealed gold-tube: monoclinic, P2₁/m, with a = 555.69(4) pm, b = 1042.11 (8) pm, c = 555.69(4) pm, β = 117.387(5)°, Z = 2. Characteristic features of Na₄[AuCoO₅] are meandric chains [(O_2/2 (CoO)O₂AuO_2/2)₂]. The structure has been determined by four-circle diffractometer data (Siemens AED 2; Mo? Kα , graphite, 881 I₀(hkl), R = 0.0366, R_w = 0.0316), parameters as given in the text. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, these via Mean Fictive Ionic Radii, and Charge-distribution, CHARDI, are calculated and discussed.     

Neue Phosphor-verbrückte Übergangsmetallcarbonyl-Komplexe Die Kristallstrukturen von [Re2(CO)7(PtBu)3], [Co4(CO)10(PtBu)2], [Ir4(CO)6(PtBu)6] und [Ni4(CO)10(PiPr)6]

New Phosphorus-bridged Transition Metal Carbonyl Complexes. The Crystal Structures of [Re₂(CO)₇(P^tBu)₃], [Co₄(CO)₁₀(P^tBu)₂], [Ir₄(CO)₆(P^tBu)₆], and [Ni₄(CO)₁₀(PⁱPr)₆], (P^tBu)₃ reacts with [Mn₂(CO)₁₀], [Re₂(CO)₁₀], [Co₂(CO)₈] and [Ir₄(CO)₁₂] to form the multinuclear complexes [M₂(CO)₇(P^tBu)₃] (M = Re ( 1 ), Mn ( 5 )), [Co₄(CO)₁₀(P^tBu)₂] ( 2 ) and [Ir₄(CO)₆(P^tBu)₆] ( 3 ). The reaction of (PⁱPr)₃ with [Ni(CO)₄] leads to the tetranuclear cluster [Ni₄(CO)₁₀(PⁱPr)₆] ( 4 ). The complex structures were obtained by X-ray single crystal structure analysis: ( 1 : space group P1 (Nr. 2), Z = 2, a = 917.8(3) pm, b = 926.4(3) pm, c = 1 705.6(7) pm, α = 79.75(3)°, β = 85.21(3)°, γ = 66.33(2)°; 2 : space group C2/c (Nr. 15), Z = 4, a = 1 347.7(6) pm, b = 1 032.0(3) pm, c = 1 935.6(8) pm, β = 105.67(2)°; 3 : space group P1 (Nr. 2), Z = 4, a = 1 096.7(4)pm, b = 1 889.8(10)pm, c = 2 485.1(12) pm, α = 75.79(3)°, β = 84.29(3)°, γ = 74.96(3)°; 4 : space group P2₁/c (Nr. 14), Z = 4, a = 2 002.8(5) pm, b = 1 137.2(8) pm, c = 1 872.5(5) pm, β = 95.52(2)°).     

Zur Kristallstruktur von KGaO2 und NaGaO2(II) [1]

The Crystal Structure of KGaO₂ and NaGaO₂(II) By annealing intimate mixtures of K₂O, Na₂O and β-Ga₂O₃ (K : Na : Ga = 2.2 : 1.1 : 1) we obtained single crystals of K₂Na₄[(GaO₃)₂] and KGaO₂ (Ag-cylinder; 600°C, 26 d). Structure refinement for KGaO₂ (four-circle diffractometer data, Mo-Kα , 1 390 or 1 390 I_o(hkl); R = 5.55%, R_w = 3.05%) confirms the space group Pbca; a = 552.1 pm, b = 1 107.5 pm, c = 1 580.7 pm, Z = 16. According to K[GaO_4/2] we have a stuffed cristobalite-related structure. Single crystals of NaGaO₂(II) were grown by annealing intimate mixtures of Na₂O₂ and GaAs (Na₂O₂ : GaAs 4.1 : 1) in Ag-cylinders that were not completely closed (570°C, 6 weeks). Structure refinement for NaGaO₂(II) (four-circle diffractometer data, Mo-Kα , 588 of 616 I_o(hkl); R = 4.54%, R_w = 4.06%) confirms the spacegroup Pna2₁; a = 549.8(1) pm, b = 720.6(1) pm, c = 529.8(1) pm, Z = 4. In NaGaO₂(II) we have a wurtzite-related structure.     

Na4[PbO4] — Darstellung neuer Plumbate(IV) durch Oxydation intermetallischer Phasen

Na₄[PbO₄] — Preparation of new Plumbates(IV) by Oxidizing Intermetallic Phases By oxidizing NaPb with Na₂O₂ (molar ratio Na₂O₂:NaPb = 2.04:1; Ag-tubes; 600°C/50d) we obtained for the first time small orange coloured single crystals of Na₄[PbO₄]: Na₄[SiO₄]-type [2], P? 1 (I.T. No. 2) with a = 898.5(3); b = 675.6(3); c = 592.2(2) pm; α = 124.75(1)°; β = 96.75(1)°; γ = 100.18(2)°; Z = 2; (four circle diffractometer data (MoK; 3 251 I_o(hkl); R = 3.4%; R_w = 3.0%), parameters see text. Furthermore the Madelung part of lattice energy (MAPLE), effective coordination numbers (ECoN), mean fictive ionic radii (MEFIR) and the charge distribution (CHARDI) are being calculated.     

Quaternäre Monoborate der Alkalimetalle: Na4Li5[BO3]3

Quaternary Monoborates of Alkali Metals: Na₄Li₅[BO₃]₃ We prepared hitherto unknown Na₄Li₅[BO₃]₃ in the shape of monoclinic, colourless-transparent and prismatic single crystals [a = 1238.8(5) pm, b = 729.6(3) pm, c = 973.8(3) pm, β = 107,29(4)°, Z = 4, d_x = 2,397 g/cm³, d_pyk = 2,37 g/cm³]. The crystal structure was solved by four-circle-diffractometer [PW 1100, MoKα , R = 9,02%, R_w = 5,29%, 1221 I₀(hkl)]I₀(hkl)]. Na₄Li₅[BO₃]₃ is sensitive against atmospheric moisture; hydrolysis takes place within 60 minutes. Effective Coordination numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, and the Madelung Part of Lattice Energy, MAPLE, are calculated and discussed.     

Na2Li3CoO4, das Erste quaternäre Oxocobaltat(III) der Alkalimetalle

Na₂Li₃CoO₄, the First Quaternary Oxocobaltate(III) of the Alkali Metals For the first time we obtained Na₂Li₃CoO₄ by annealing intimate mixtures of Co₃O₄, Na₂O₂, and Li₂O [Co : Na : Li = 1 : 2.2 : 10.1; 760°C; 21 d; Ag-tube] in form of transparent red single crystals. Structure Refinement [four-circle diffractometer data; AED2; MoKα-radiation; 1016 I_o(hkl); R = 2.6%; R_w = 2.0%; space group Pnnm; Z = 4; a = 818.7(3), b = 799.4(2), c = 655.1(2) pm] confirms the isotypism to Na₂Li₃GaO₄ [2] and Na₂Li₃FeO₄ [3]. Mean Fictive Ionic Radii, MEFIR, Effective Coordination Numbers, ECoN, and the Charge Distribution were calculated. The isotypism of Na₂Li₃CoO₄ and Na₂Li₃GaO₄ is compared graphically.     

Zur Konstitution von Cs2[FeO4]

On the Constitution of Cs₂[FeO₄] For the first time black, spherical single crystals of Cs₂[FeO₄] were prepared by an “oxydative exchange reaction” of NaFeO₂ with CsO_1,8 (molar ratio Fe:Cs = 1.00:2.10, Au-tube, 250°C 3d, 480°C 24d, 360°C 5d): Spacegroup Pnma with a = 842.86(12) pm, b = 628.12(10) pm, c = 1105.33(17) pm. Cs₂[FeO₄] is isotypic to β-K₂SO₄. The structure was determined by four circle diffractometer data [MoKα , 1384 of 1387 I_o(hkl), R = 3.36%, R_w = 3.08%]; parameters as given in the text. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, and the Charge-distribution will be calculated and discussed.     

Ein Oxostannat neuen Strukturtyps: Cs4[SnO4]

An Oxostannate of a New Structure Type: Cs₄[SnO₄] In order to prepare Cs₃LiSnO₄ by heating of a well ground mixture of the binary oxides [CsO_0.67, Li₂O, SnO₂; Cs:Li:Sn = 3.3:1.0:1.0; 450°C; 28 d; Ni-tube] colourless, monoclinic single crystals of Cs₄[SnO₄] have been yielded for the first time: space group P2₁/c with a = 1180.8 pm. b = 728.2 pm, c = 1166,7 pm, β = 111.79°, Z = 4. The crystal structure was solved by fourcycle-diffractometer data [Siemens AED2, 2299 from 2708 I₀(hkl), R = 7.0%, R_w = 5.6%], parameters see text. Characteristic for the complicated structure are “isolated” [SnO₄]^4? tetrahedra. Mean Fictive Ionic Radii, MEFIR, Effective Coordination Numbers, ECoN and the Madelung Part of Lattice Energy, MAPLE, have been calculated.     

Untersuchungen zur Reaktivität in den Systemen A/Cu/M/O (A = Na–Cs und M = Co,Ni, Cu,Ag); Synthese und Kristallstrukturen von K3Cu5O4 und Cs3Cu5O4

Reactivity in the Systems A/Cu/M/O (A = Na–Cs and M = Co, Ni, Cu, Ag); Synthesis and Crystal Structures of K₃Cu₅O₄ und Cs₃Cu₅O₄ The systems A/Cu/M/O with A = Na–Cs and M = Co, Ni, Cu, Ag have been investigated with preparative, thermoanalytical and in situ X‐ray techniques to study the reactivity. For the redox reaction Co/CuO in the presence of Na₂O the intermediate, NaCuO, has been characterized. K₃Cu₅O₄ was obtained by annealing intimate mixtures of K₂O and CuO (molar ratio 1 : 1) in Ag containers at 500 °C. Cs₃Cu₅O₄ could be synthezised by reaction of KCuO₂ with Cs₂O (molar ratio 1 : 1) in Cu containers at 500 °C. Both compounds crystallize in the space group P2₁/c with Z = 4 isotypic to Rb₃Cu₅O₄ [IPDS data, Mo–Kα; K₃Cu₅O₄: a = 946.0(1), b = 735.61(6), c = 1401.3(2) pm, β = 107.21(1)°; 2249 F²(hkl), R₁ = 7.09%, wR₂ = 11.42%; Cs₃Cu₅O₄: a = 1027.7(1), b = 761.42(7), c = 1473.4(2) pm, β = 106.46(1)°, 1712 F²(hkl), R₁ = 6.04%, wR₂ = 14.22%]. Force constants obtained from FIR experiments for the deformation mode δ(O–Cu–O), the Madelung Part of the Lattice Energie, MAPLE, Effective Coordination Numbers, ECoN, calculated via Mean Effective Ionenradii, MEFIR, are given.