über Erdalkalimetalloxocuprate,VIII Zur Kenntnis von Sr2CuO2Cl2

On Alkaline Earth Oxocuprates VIII. About Sr₂CuO₂Cl₂ Sr₂CuO₂Cl₂ was prepared and investigated by single crystal X – ray work (space group D–Immm, a = 3.975, c = 15.618 Å). Sr₂CuO₂Cl₂ is isotypic with K₂NiF₄ – compounds and shows an octahedral configuration for Cu²⁺. Cl^? occupies trans-positions of the octahedral Cu²⁺/O^2? polyhedron. A discussion with related compounds (Sr₂CuO₃ and Nd₂CuO₄) explains the observed distribution of O^2? and Cl^?.     

Über Oxocuprate. XVIII. Zur Kenntnis von Sr2CuO2Br2 mit einem Beitrag über La2NiO4

About Oxocuprates. XVIII. On Sr₂CuO₂Br₂ and a Contribution about La₂NiO₄ Sr₂CuO₂Br₂ (A) and La₂NiO₄ (B) were prepared and investigated by single crystal X-ray technique. (A) is isotypic with Sr₂CuO₂Cl₂, (B) with K₂NiF₄. Both compounds crystallize in the space group D–I4/mmm with the lattice constants (A): a = 399.1, c = 1 713.6 pm, (B): a = 387.6, c = 1 268.3 pm. A discussion about the octahedral distortion of Cu²⁺ and Ni²⁺ respectively in respect to other isotypic compounds is given.     

Über Oxocuprate. XIX. Ein Oxohalogenocuprat(I): Ba2CuO2Cl

On Oxocuprates. XIX. The Oxohalogenocuprate(I): Ba₂CuO₂Cl The hitherto unknown compound Ba₂CuO₂Cl was prepared and examined by single crystal X-ray diffractometer investigation (a = 983.5 pm, α = 25,04°; Space group D⁵_3d? R3 m). Cu⁺ has the coordination O? Cu? O, Ba²⁺ an octahedral surrounding. A discussion of the structure is given.     

Über Oxocuprate. XVII. Zur Kenntnis von Ca2CuO2Cl2 und Ca2CuO2Br2

About Oxocuprates. XVII. Ca₂CuO₂Cl₂ and Ca₂CuO₂Br₂ The so far unkown compounds Ca₂CuO₂Cl₂ (I) and Ca₂CuO₂Br₂ (II) were prepared and examined by X-ray single crystal methods. They are isotypic with Sr₂CuO₂Cl₂ ((I) a = 386.6, c = 1 497.5; (II) a = 387.5, c = 1 726.4 pm, space group d–I4/mmm). A discussion of the distances in respect to the structure shows that the stretching of octahedron around Cu²⁺ is no evidence for a Jahn-Teller-effect.     

Über Oxocuprate,XXVI Synthese und Struktur eines Oxohalogenocuprat(I): Sr2CuO2Cl

Single crystals of Sr₂CuO₂Cl were prepared in a closed system of Ag- and quartz-tubes. The colorless crystals are extremly sensitive against moisture. X-ray investigation proves a trigonal symmetry (a=400.3;c-2767.9 pm, space group P3₁21-D ₃ ⁴ ). Sr²⁺ has a distorted octahedral coordination of 3 O^2– and 3 Cl^–. Cu⁺ shows a dumbbell like O^2– surrounding. The O-Cu-O bond angle (176.5°) differs from the usually value (180°).

     

Charge dynamics of 57Fe probe atoms in La2Li0.5Cu0.5O4

The objective of this study is to characterize the electronic state and local surrounding of ⁵⁷Fe Mössbauer probe atoms within iron-doped layered perovskite La₂Li_0.5Cu_0.5O₄ containing transition metal in unusual formal oxidation states “+3”. An approach based on the qualitative energy diagrams analysis and the calculations within the cluster configuration interaction method have been developed. It was shown that a large amount of charge is transferred via Cu-O bonds from the O: 2p bands to the Cu: 3d orbitals and the ground state is dominated by the d⁹L configuration (“Cu²⁺-O^-” state). The dominant d⁹L ground state for the (CuO₆) sublattice induces in the environment of the ⁵⁷Fe probe cations a charge transfer Fe³⁺ + O⁻(L) → Fe⁴⁺ + O²⁻, which transforms “Fe³⁺” into “Fe⁴⁺” state. The experimental spectra in the entire temperature range 77–300 K were described with the use of the stochastic two-level model based on the assumption of dynamic equilibrium between two Fe³⁺↔Fe⁴⁺ valence states related to the iron atom in the [Fe(1)O₄]^4- center. The relaxation frequencies and activation energies of the corresponding charge fluctuations were estimated based on Mössbauer data. The results are discussed assuming a temperature-induced change in the electronic state of the [CuO₄]^5- clusters in the layered perovskite.     

Ein zweites Erdalkalimetall-Kupferoxovanadat: SrCuV2O7

On a Second Alkaline Earth-Copper Oxovanadate: SrCuV₂O₇ Single crystals of SrCuV₂O₇ were prepared by solid state reaction in the order of the meltingpoint of the component mixture. The yellowgreen crystals have orthorhombic symmetry, space group D_2h¹⁶–Pnma; a = 14.470; b = 5.470; c = 7.420 Å; Z = 4. SrCuV₂O₇ represent a new crystal structure with V⁵⁺ in tetrahedric coordination, forming V₂O₇-double-tetrahedra, which are connected with CuO₅ square pyramids into planes. Sr²⁺ between these planes has a complicated surrounding of 11 O^2?. The structure is discussed with respect to the not isotypic compound CaCuV₂O₇.     

Neue Oxometallate vom BaCuSm2O6-Typ: BaCoHo2O5, BaCoYb2O5 und vom BaNiLn2O5-Typ: BaCoEr2O5

Inhaltsübersicht. (I) BaCoHo₂O₅, (II) BaCoYb₂O₅ und (III) BaCoEr₂O₅ wurden neu dargestellt und an Einkristallen mit Röntgenbeugungsmethoden die Kristallstruktur bestimmt. (I) und (II) gehören zum BaCuSm₂O₅-Typ mit (I): A = 12,267; b = 5,714; c = 7,064 Å; Z = 4; (II): A = 12,138; b = 5,662; c = 7,004 Å; Z = 4. Beide kristallisieren in der Raumgruppe D¹⁶_2h–Pnma. (III) kristallisiert im BaNiLn₂O₅-Typ, Raumgruppe D²⁵_2h–Immm mit a = 3,734; b = 5,770; c = 11,421 Å; Z = 2. Die Koordination um Co²⁺ wechselt von (I, II) nach (III) von tetragonal pyramidal nach oktaedrisch. New Oxides of the BaCuSm₂O₅-Type: BaCoHo₂O₅, BaCoYb₂O₅, and of the BaNiLn₂O₅ Type: BaCoEr₂O₅ (I) BaCoHo₂O₅, (II) BaCoYb₂O₅, and (III) BaCoEr₂O₅ are new compounds prepared by high temperature reactions. X-ray single crystal work show: (I) and (II) belong to the BaCuSm₂O₅-type (space group D¹⁶_2h-Pnma, Z = 4). (I): A = 12.267; b = 5.714; c = 7.064 Å; (II): A = 12.138; b = 5.662; c = 7,004 Å. (III) crystallizes with BaNiLn₂O₅-structure, space group D²⁵_2h-Immm; Z = 2; a = 3.734; b = 5.770; c = 11.421 Å; within (I) and (II) Co²⁺ has a tetragonal pyramidal coordination by oxygen. The coordination changes in (III) to a compressed octehedral O^2– surrounding.     

Die Kristallstruktur von (PPh4)2[Mo2(O2C?Ph)4Br2] · 2 CH2Br2

Crystal Structure of (PPh₄)₂[Mo₂(O₂C? Ph)₄Br₂] · 2 CH₂Br₂ The title compound, prepared by the reaction of Mo₂(O₂C? Ph)₄ with PPh₄Br and PPh₄N₃, respectively, under the assistance of CH₂Br₂, was characterized by an X-ray structure determination. Space group P2₁/n, Z = 2, R = 0.074 (5261 independent observed reflexions). The lattice dimensions are at ?70°C: a = 1562.9, b = 1406.2, c = 1662.1 pm, β = 94.11°. the compound consists of PPh₄^⊕ ions, CH₂Br₂ molecules, and centrosymmetric anions [Mo₂(O₂C? Ph)₄Br₂]^2?. The axis Br? Mo?Mo–Br is nearly linear (bond angle 175.6°) with bond lengths MoMo = 212.3 pm and Mo? Br = 303 pm, corresponding with a weak electrostatic Mo? Br bond. In the FIR spectrum the Mobr stretching vibration is found at 85 cm^?1, which corresponds with the low value of the force constant of 0.24 N · cm^?1.     

Über Oxocuprate. XI. Zur Kenntnis von Ba3Cu2O4Cl2

On Osocuprates. XI. Ba₃Cu₂O₄Cl₂ A new oxohalogenocuprat, Ba₃Cu₂O₄Cl₂ mas prepared and investigated by X-ray single crystal methods. The hitherto unknown compound has orthorhombic symmetry (Space group: D_2h⁵—Pmma; a = 6.653, b = 6.000, c = 10.563 Å). It shows angled chains of O^2?-squares around Cu²⁺. One of the Cu²⁺ positions is completed by Cl^minus; to a tetragonal pyramid. The coordination polyhedrals of Ba_I–III and the connection with the Cu/O-chains are described and discussed.     

Sr2Cu2TeO6Br2: honeycomb layers of copper(II) ions

Single crystals of distrontium(II) dicopper(II) tellurium(VI) hexa­oxide dibromide, Sr₂Cu₂TeO₆Br₂, were synthesized via solid state/gas phase reactions in sealed evacuated silica tubes. The building units are irregular SrO₄Br₃ polyhedra (a new type of coordination polyhedron around Sr^II), CuO₅ square pyramids and TeO₆ octa­hedra. The CuO₅ square pyramids and the TeO₆ octa­hedra together form layers in the bc plane bridged by Sr atoms. The Cu atoms are arranged to form puckered honeycomb layers. The Te atom lies on an inversion centre.     

Solvothermal Synthesis,Crystal Structure,and Luminescent Properties of Three Heterometallic Lanthanide‐Transition‐Metal Frameworks Constructed from Three Types of CuBr Motifs

Three three‐dimensional (3D) heterometallic lanthanide‐transition‐metal (hetero‐Ln‐TM) compounds with the formula [Ln₆(Cu₄Br₃)(Cu₂Br₂)₂(Cu₂Br)(IN)₂₀(H₂O)₁₂] · 2H₂O [Ln = Gd ( 1 ), Ln = Sm ( 2 ), Ln = Eu ( 3 )] based on the linkages of one‐dimensional Ln organic chain and Cu_mBr_n units were synthesized by mixing Ln₂O₃ with isonicotinic acid (HIN = pyridine‐4‐carboxylic acid) under hydrothermal condition. During the synthesis, two ligands were used: the isonicotinate (IN^–) stabilizes the cluster and links the one‐dimensional Ln organic chains and Cu_mBr_n motif, whereas Br^– anions play a very important role in the formation of the distinct Cu_mBr_n units. It is interesting that there are three different Cu‐Br motifs: a closed four‐membered ring [Cu₂Br₂] subunit, a linear [Cu₂Br] subunit, an S‐sharp [Cu₄Br₃] subunit. Strong fluorescence of compounds 2 and 3 suggests an efficient energy transfer from the ligand to Eu³⁺ ions. The luminescent investigation indicates that 2 and 3 are excellent candidates for fluorescent materials.     

Electrical Resistivity, Magnetic Susceptibility, X-Ray Photoelectron Spectroscopy, and Electronic Band Structure Studies of Cu2.33−xV4O11

The electronic and physical properties of Cu_2.33V₄O₁₁ were characterized by electrical resistivity, magnetic susceptibility and X-ray photoelectron spectroscopy (XPS) measurements and by tight-binding electronic band structure calculations. Attempts to prepare Cu_2.33−xV₄O₁₁ outside its narrow homogeneity range led to a mixture of Cu_2.33V₄O₁₁, CuVO₃ and β-Cu_xV₂O₅. The magnetic susceptibility data show no evidence for a magnetic/structural transition around 300 K. The XPS spectra of Cu_2.33V₄O₁₁ reveal the presence of mixed valence in both Cu and V. The [Cu⁺]/[Cu²⁺] ratio is estimated to be 1.11 from the Cu 2p_3/2 peak areas, so [V⁴⁺]/[V⁵⁺]=0.56 by the charge balance. Our electronic structure calculations suggest that the oxidation state of the Cu ions is +2 in the channels of CuO₄ tetrahedra, and +1 in the channels of linear CuO₂ and trigonal planar CuO₃ units. This predicts that [Cu⁺]/[Cu²⁺]=1.33 and [V⁴⁺]/[V⁵⁺]=0.50, in good agreement with those deduced from the XPS study.     

Oxocuprate(I) mit CO2-analogem Anion: Rb3[CuO2] [1]; (3. Mitteilung)

Inhaltsübersicht. Rb₃[CuO₂] wurde als dunkelgelbes Pulver bzw. erstmals in Form transparenter gelber, blockförmiger Einkristalle durch Tempern der binären Oxide (RbO_0,63/Cu₂O, Rb: Cu = 3,1:1 [Pulver] bzw. 4,2:1 [Einkristalle]) hergestellt (geschlossene Cu-Bömbchen, 600°C/10 d, bzw. 560°C/14 d, dann langsam abgekühlt). Nach Strukturaufklärung (a = 930,9(1); b = 966,8(2); c = 675,5(1) pm, β = 110,1(1)°, P2₁/n–C⁵_2h, Z = 4, Vierkreisdiffraktometer AED2, MoKα, 1409 von 1573 I_o(hkl), R = 14,6%, R_w = 10,0%) liegt ein neuer Strukturtyp vor (Parameter siehe Text). Strukturcharakteristisch sind die CO₂-analogen Hanteln [O–Cu–O] mit d(Cu–O) = 177 pm. Die Struktur wird beschrieben. Der Madelunganteil der Gitterenergie, MAPLE, effektive Koordinationszahlen, ECoN, diese über mittlere fiktive Ionenradien, MEFIR, werden berechnet und diskutiert. Oxocuprates(I) with CO₂-analogues Anions: Rb₃[CuO₂] (3^rd Communication) For the first time Rb₃[CuO₂] was prepared as dark yellow powder resp. yellow single crystals from the binary oxides (RbO_0.63/Cu₂O, Rb: Cu = 3.1:1 [powder] resp. 4.2:1 [single crystals], sealed Cu-cylinders). The crystal structure (a = 930.9(1); b = 966.8(2); c = 675.5(1) pm, β = 110.1(1)°, P2₁/n–C⁵_2h, Z = 4, four circle diffractometer AED2, 1409 out of 1573 I_o(hkl), R = 14.6%, R_w = 10.0%) was solved. The characteristic element is the CO₂-analogues group [O–Cu–O] with d(Cu–O) = 177 pm. The structure is described. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, are calculated and discussed.     

Synthese und Kristallstruktur von Ba25Cu142+Cu43+Zn4O49

Synthesis and Crystal Structure of Ba₂₅Cu₁₄²⁺Cu₄³⁺Zn₄O₄₉ Single crystals of Ba₂₅Cu₁₄²⁺Cu₄³⁺Zn₄O₄₉ were prepared with solid state and flux reactions. X-ray investigations show tetragonal symmetry, space group D⁷_4th–P4/nmm, a = 18.2146, c = 9.3230 Å, Z = 2. The hitherto unknown structure type shows copper in square pyramids and planar polygones, connected to six member rings or Cu₅O₂₀ groups. Slightly bent Cu₅O₁₂ groups produced by edge connection of five CuO₄ polygones are connected with ZnO₄ tetrahedra forming Cu₅Zn₄O₂₀ units. The complicated structure is shown step by step.     

Preparation and electrical and magnetic properties of Sr2−xNaxCuO3 (0 ≤ x ≤ 1) solid solutions

Mixed-valence copper(II/III) oxide solid solutions Sr_2?xNa_xCuO₃ (0 ≤ x ≤ 1) have been prepared by solid-state reactions in oxygen atmosphere. All solid solutions exhibit the structure of Sr₂CuO₃ (S.G. Immm). Electrical conductivity and thermoelectric power measurements show a semiconducting behavior in the whole composition range. The electronic structure of Sr₂CuO₃ is compared with that of La₂CuO₄ on the basis of an iono-covalent model. Interpretation of transport properties suggests the formation of small polarons. Magnetic susceptibility and EPR measurements show that the antiferromagnetic ordering of Sr₂CuO₃ tends to vanish as x increases, however magnetic interactions are still strong for a concentration of Cu²⁺ ions corresponding to x = 0.8.     

Kinetic study of the reactions of Br2 with OH and OD

The kinetics of the reactions OH + Br₂ → HOBr + Br (1) and OD + Br₂ → DOBr + Br (3) have been studied in the temperature range 230–360 K and at total pressure of 1 Torr of helium using the discharge‐flow mass spectrometric method. The following Arrhenius expressions were obtained either from the kinetics of product formation (HOBr, DOBr) in excess of Br₂ over OH and OD or from the kinetics of Br₂ consumption in excess of OH and OD: k₁ = (1.8 ± 0.3) × 10⁻¹¹ exp [(235 ± 50)/T] and k₃ = (1.9 ± 0.2) × 10⁻¹¹ exp [(220 ± 25)/T] cm³ molecule⁻¹ s⁻¹. For the reaction channels of the title reactions: OH + Br₂ → BrO + HBr and OD + Br₂ → BrO + DBr, the upper limits of the branching ratios were found to be 0.03 and 0.02 at T = 320 K, respectively. © 1999 John Wiley & Sons, Inc. Int J Chem Kinet 31: 698–704, 1999     

Synthese und Struktur einer neuen Form von CuYMo2O8

Synthesis and Structure of a New form of CuYMo₂O₈ Single crystals of a new form of CuYMo₂O₈ were prepared and investigated by X-ray diffractometer technique [space group D-Pbca; a = 10.160 Å, b = 9.701 Å, c = 14.527 Å; Z = 8]. CuYMo₂O₈ represents a new structure type characterised by MoO₄-tetrahedrons, Cu⁺ with coordination number 2 + 1 and square antiprisms around Y³⁺. The crystal structure and the Cu⁺ coordination are discussed.     

Cuprous complexes and dioxygen. Part 11. Concomitant one- and two-electron reduction of O2 by the Cu ion

The autoxidation of Cu^I in aqueous MeCN has been studied using a Clark oxygen electrode in the presence and absence of Cu¹¹. The reaction is inhibited by Cu¹¹ in the pH range of 0.5 to 5.0, reaching a lower limiting value at the highest concentrations. The reaction order changes from 1 to 2 with respect to Cu^I under the influence of Cu²⁺ ion. Detailed kinetics analysis of a total of 275 measurements has shown that an unstable primary adduct CuO⁺₂ decomoses to give ^.O or HO, depnding on pH, and also reacts directly with a second Cu⁺ ion, avoiding one-electrton reduction of O₂ by this path. Reaction of HO is faster with Cu^I than with Cu¹¹ by a factor of 20, and single-electron transfer within CuO⁺₂ to Cu²⁺ and ^.O predominates over reaction with a second copper ion for [Cu^I_tot] < 2. 10^?3M in the absence of Cu²⁺. The most likely value for the reaction of ^.O with Cu^I is 5.3 · 10⁸ M ^?1S^?1, but even this high rate constant is at the limit of significance. All secondary reactions followinfg the initial formation of CuO⁺₂ are shown to be very fast, a fact that should be properly considered in the discussion of mechanisms of copper-catalyzed oxidations and oxygenations.     

Das erste Alkali-Erdalkali-Oxocuprat(II,III): NaBa2Cu22+Cu3+O6

The first Alkaline Alkaline-Earth Oxocuprate (II, III): NaBa₂Cu₂²⁺Cu³⁺O₆ The compound NaBa₂Cu₃O₆ was prepared by heating of Na₂O₂, BaO₂, Cu₂O in closed Ag-tubes. X-ray single crystal investigations led to orthorhombic symmetry, space group D-Fmmm; a = 8.4229; b = 11.4418; c = 14.4063 Å; Z = 8. Cu²⁺ and Cu³⁺ show square planar polygones of four and Na⁺ trigonal prisms of six O^2?. The two barium point positions show coordination numbers C.N. = 8 and 6 + 4. The crystal structure is discussed.