Zur Struktur der Kupfer-Weberite Na2CuCrF7 und Na2CuFeF7 / Concerning the Structures of the Copper Weberites Na2CuCrF7 and Na2CuFeF7

1988 ◽  
Vol 43 (6) ◽  
pp. 694-701 ◽  
Author(s):  
S. Kummer ◽  
W. Massa ◽  
D. Babel

AbstractThe crystal structure of the compound Na-CuCrF7 (orthorhombic, a = 710.0, b = 1033.8, c = 751.8 pm, Z = 4) was refined in space group Pmnb to Rg= 0.028 (1545 independent reflections). The Jahn-Teller distortion of the CuF6 -octahedra (Cu-F = 191.1/193.8/212.4 pm. mean 199.1 pm) reduces the symmetry compared to the body-centered orthorhombic weberite type, to which it is otherwise closely related. The CrF6 -octahedra. interconnecting parallel chains of CuF6 -octahedra, are nearly undistorted (mean Cr-F = 190.6 pm). Na2CuFeF7 exhibits a supercell with a different structure (monoclinic, a = 2468.7, b = 734.7, c = 1245.2 pm, β = 99.29°, Z = 16). It may be interpreted as a new intermediate type between orthorhombic and trigonal weberites. Preliminary results obtained from refinement in space group A2/n (Rg = 0.076) are given and discussed (mean values Cu-F = 199 pm, Fe - F = 192 pm).

1992 ◽  
Vol 47 (5) ◽  
pp. 685-692 ◽  
Author(s):  
Matthias Welsch ◽  
Dietrich Babel

The monoclinic weberites Na2CoFeF7 (a = 1262.2(10), b = 736.0(4), c = 2451.6(20) pm, β = 99.71(5)°) and a second modification of Na2CuFeF7 (a = 1244.4(2), b = 734.3(1), c = 2467.2(5) pm, β = 99.27(3)°), crystallize isotypically in space group C 2/c, Ζ = 16. The structure is an intermediate type between orthorhombic and trigonal weberites, characterized by pairs ofparallel chains of octahedra [MF4F2/2]3- (M = Co, Cu) which run in turn along [110] and [110]. The average distances are Fe-F = 192 pm in the [FeF63- octahedra of both compounds. Considerable splitting of distances occurs in the [CoF6- octahedra (av. Co-F = 201 pm), and by Jahn-Teller distortion even more in those of [CuFJ4- (av. Cu-F = 199 pm). One of the copper surroundings is (pseudo)tetragonally elongated (av. 209/194 pm), the other exhibits an unusual splitting into three long and three short bonds (av. 204/193 pm) in meridional positions. Some structural relations are discussed.


1991 ◽  
Vol 44 (10) ◽  
pp. 1495 ◽  
Author(s):  
RC Bott ◽  
DS Sagatys ◽  
DE Lynch ◽  
G Smith ◽  
CHL Kennard ◽  
...  

The copper(II) complex with citric acid (NH4)4 [Cu(C6H5O7)2] has been prepared, and its structure determined by X-ray diffraction, giving a residual R 0.035 for 1208 observed reflections. Crystals are monoclinic, space group P21/c with Z 2 in a cell of dimensions a 8.755(3), b 13.185(4), c 9.364(2)Ǻ, β 113.73(2)°. The complex is a centrosymmetric six-coordinate monomer which is isomorphous with ammonium zinc(II) citrate. However, the Cu-O(hydroxyl) bonds [2.341(3)Ǻ] show Jahn-Teller distortion relative to the Cu-O(carboxyl) bonds [1.969(3) and 1.977(3)Ǻ].


2020 ◽  
Vol 76 (11) ◽  
pp. 1720-1724
Author(s):  
Abigail J. Hall ◽  
Matthias Zeller ◽  
Curtis M. Zaleski

The synthesis and crystal structure of the title compound [systematic name: di-μ-acetato-tetrakis(μ4-N,2-dioxidobenzene-1-carboximidato)hexamethanoltetramanganese(III)nickel(II) methanol disolvate monohydrate], [Mn4Ni(C7H4NO3)4(C2H3O2)2(CH4O)6]·2CH4O·H2O or Ni(OAc)2[12-MCMn(III)N(shi)-4](CH3OH)6·2CH3OH·H2O, where MC is metallacrown, −OAc is acetate, and shi3− is salicylhydroximate, are reported. The macrocyclic metallacrown is positioned on an inversion center located on the NiII ion that resides in the central MC cavity. The macrocycle consists of an MnIII–N–O repeat unit that recurs four times to generate an overall square-shaped molecule. Both the NiII and MnIII ions are six-coordinate with an octahedral geometry. In addition, the MnIII ions possess an elongated Jahn–Teller distortion along the z-axis of the coordination environment. The interstitial water molecule is slightly offset from and disordered about an inversion center.


1989 ◽  
Vol 44 (7) ◽  
pp. 715-720 ◽  
Author(s):  
Dietrich Babel ◽  
Michael Otto

The crystal structures of the isotypic monoclinic fluorides Na2CuF4 (a = 326.7(1), b = 937.0(2), c = 561.2(1) pm, β = 92.49(1)°; V = 171.63 x10-30 m3) and Na2CrF4 (a = 334.8(1), b = 954.9(2), c = 566.5(3) pm, β = 92.85(3)°; V = 180.89 × 10-30 m3) have been redetermined by single crystal X-ray methods. The compounds are Jahn-Teller distorted variants of the orthorhombic Sr2PbO4type (space group Pbam) and crystallize with Z = 2 in space group P21/c, a subgroup of Pbam. They form a chain structure of edge-sharing octahedra which are strongly elongated. The following distances were obtained: Cu-F = 190.4/193.8/235,7(2) pm and Cr-F = 199.1/199.7/241.7(4) pm. The geometry is compared to that of the corresponding distorted rutile type difluorides; relations to further compounds are discussed.


2015 ◽  
Vol 71 (11) ◽  
pp. 936-943 ◽  
Author(s):  
Arumugam Thangavel ◽  
Marika Wieliczko ◽  
Christopher Scarborough ◽  
Birger Dittrich ◽  
John Bacsa

In the crystal structure of the title homoleptic CrIIcomplex, [Cr(CH3CN)6](C24H20B)2·CH3CN, the [Cr(CH3CN)6]2+cation is a high-spind4complex with strong static, rather than dynamic, Jahn–Teller distortion. The electron density of the cation was determined by single-crystal X-ray refinements using aspherical structure factors from wavefunction calculations. The detailed picture of the electronic density allowed us to assess the extent and directionality of the Jahn–Teller distortion of the CrIIcation away from idealized octahedral symmetry. The topological analysis of the asphericald-electron density about the CrIIcation showed that there are significant valence charge concentrations along the axial Cr—N axes. Likewise, there were significant valence charge depletions about the CrIIcation along the equatorial Cr—N bonds. These charge concentrations are in accordance with a Jahn–Teller-distorted six-coordinate complex.


1990 ◽  
Vol 45 (10) ◽  
pp. 1341-1348 ◽  
Author(s):  
Friedemann Hahn ◽  
Werner Massa

Redetermination of the crystal structure of Cs2MnF5 · H2O (space group Cmm 2, Z = 2, a = 974.0(2), b = 867.4(1), c = 426.0(1) pm, R = 0.026 for 478 reflections) revealed ordered instead of disordered positions of water molecules indicating ferroelectric properties. The dehydration of a twinned crystal gave an untwinned single crystal of Cs2MnF5 by a topotactical reaction. The crystal structure of Cs2MnF5 (space group P4/mmm, Z = 1, a = 642.0(1), c = 422.9(1) pm, R = 0.034 for 175 reflections) shows trans-connected octahedral chains [MnF5]∞2- with 180° Mn-F-Mn bridge angles like in the monohydrate. The bridging bonds in Cs2MnF5 · H2O and in Cs2MnF5 resp. are elongated by the Jahn-Teller effect (mean values Mn-Fbridge 213/211, Mn-Fterm 184/186 pm). Cs2MnF5 represents the “aristotype” of the so- called Tl2AlF5 type structure family


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