20762-60-1Relevant articles and documents
Azidoaurates of the alkali metals
Afyon, Semih,Hoehn, Peter,Armbruester, Marc,Baranov, Alexey,Wagner, Frank R.,Somer, Mehmet,Kniep, Ruediger
, p. 1671 - 1680 (2006)
Synthesis, crystal structure as well as IR- and Raman-spectroscopic properties of the new ternary azidoaurates(III) A[Au(N3)4] (A = K, Rb, Cs) are reported. The translucent orange-red compounds were prepared by reaction of the respective binary azides with HAuCl4 in aqueous solutions at room temperature. The crystal structures determined by single crystal X-ray diffraction methods are monoclinic (C2/c (No. 15), K/Rb/Cs[Au(N3)4]: a = 1049.30(9) pm / 1033.93(10) pm / 1011.9(8) pm, b = 1047.52(8) pm / 1064.20(11) pm / 1093.8(8) pm, c = 776.97(7) pm / 809.79(8) pm / 858.4(6) pm, β = 91.220(5)° / 90.322(5)° / 92.72(5)°) and provide the first examples for azidoaurates with mono-atomic cations. The unusual reduction of the lattice parameter a with increasing cation size in the isotypic series is discussed in detail. IR-and Raman-spectroscopic measurements show strongly covalent gold-nitrogen contacts, a bonding situation which is further supported by quantum chemical calculations and ELF-analyses.
Synthesis, Crystal Structure, and Magnetic Properties of K6Mn4O7 Featuring a Novel Two-Dimensional Poly-oxomanganate(II) Anion
Nuss, Jürgen,Kremer, Reinhard K.,Jansen, Martin
, p. 1715 - 1720 (2018)
K6Mn4O7 was synthesized via the azide/nitrate route from a stoichiometric mixture of the precursors KN3, KNO3, and MnO, and alternatively from the binary constituents K2O and MnO, in an all-solid state reaction. Its crystal structure [P1, Z = 1, a = 603.46(3), b = 647.69(4), c = 891.36(5) pm, α = 90.477(2)°, β = 108.417(2)°, γ = 115.358(2)°] consists of cluster-like Mn4O10 units, each composed of four edge sharing MnO4 tetrahedra. The Mn4O10 building blocks, on their part, are linked by six vertices, forming a 2D arrangement, 2∞[Mn4O4/1O6/2]n6–, with the potassium cations occupying the space in between. The temperature dependence of the magnetic susceptibility is dominated by antiferromagnetic coupling along a low-dimensional magnetic exchange path. The heat capacity reveals no clear sign of long-range magnetic ordering, supporting an interpretation of K6Mn4O7 as a new low-dimensional magnetic system.
Synthesis, crystal structure, and physical properties of the new chain alkalioxocuprate K3Cu2O4
Duris, Katarina,Kremer, Reinhard K.,Jansen, Martin
, p. 1101 - 1107 (2011)
Single crystals of K3Cu2O4 were prepared by the azide/nitrate route from respective stoichiometric mixtures of KN 3, KNO3 and CuO, at 923 K, whereas powder samples were synthesised by solid state reaction of K2O, KCuO2 and CuO, sealed in gold ampoules and treated at 723 K. According to the single crystal structure analysis (Cmcm, Z = 4, a = 6.1234(1), b = 8.9826(2), c = 10.8620(2) A, R1 = 0.044, R2 = 0.107), the main structural feature are undulating A1∞ CuO2 chains built up from planar, edge sharing CuO4 square units. From an analysis of the Cu-O bond lengths, the valence state of either +2 or +3 can be unambiguously assigned to each copper atom. The magnetic susceptibilities show the dominance of antiferromagnetic (AFM) interactions. At high temperatures, the magnetic behaviour can be fitted with the Curie-Weiss law (μeff = 1.84μB, θ = -105 K). The experimental data can be very well described by a uniform Heisenberg chain with a nearest-neighbour spin intrachain interaction (Jnn) of ～ 101 K. Copyright
The AFeO2 (A=K, Rb and Cs) family: A comparative study of structures and structural phase transitions
Ali, Naveed Zafar,Nuss, Juergen,Sheptyakov, Denis,Jansen, Martin
, p. 752 - 759 (2010)
Structures and phase transitions for the isostructural series of compounds KFeO2, RbFeO2 and CsFeO2 have been systematically studied by synchrotron X-ray high resolution powder diffraction experiments and in case of CsFeO2 also by single crystal diffractometry. At room temperature, all of the three compounds crystallize in the orthorhombic (Pbca) KGaO2 type of structure consisting of a three dimensional network of corner-sharing [FeO4/2]- tetrahedra, which at elevated temperatures shows a reversible phase transformation to a cubic structure (space group Fd over(3, -) m). For KFeO2, RbFeO2 and CsFeO2 this phase transformation takes place at 1003 K, 737 K and 350 K respectively, as confirmed by differential scanning calorimetry and X-ray diffraction. Upon heating through the transitions the major structural changes are driven by the onset or enhancement of librational motion of the FeO4 tetrahedra. Due to this phenomenon the Fe-O-Fe bonds appear to step-wise getting straight, seemingly approaching 180° within the time and space averaged structure.
