Orientational disorder in nickel(II)hexammine nitrate

Hoser, A.; Joswig, W.; Prandl, W.; Vogt, Karsten

doi:10.1080/00268978500102761

Cited by 9 publications

(3 citation statements)

References 22 publications

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“…The F positions describe ah orientational disorder of the anions (Fig. 2) similar to that in the related hexaammine complexes MU(NH3)6(BF4)2 with MEE= Co [111 or Ni [12].…”

Section: Crystal Structure Of A-cu(nh3) 5 (Bf4)mentioning

confidence: 97%

An EPR investigation of the phase transitions and cooperative ordering phenomena of pentaamminecopper(II) polyhedra in Cu(NH3)5X2 [X=BF4, CIO4; Br]

1996

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Abstraer, The results of powder and single-crystal EPR studies on Cu(NH3)sX 2 compounds [X = BF4, CICI4; Br] gire evidence that phase transitions from a eubic c~-phase (g, = 2.12) with ma anti-K2PtCl 6 type structure to low-temperature ~-phases with reduced symmetry occur, which ate indur by orderhag proeesses of the vacaneies 3 of elongated [Cu0qH3)~l~] 2+ pseudo-oetahedra. The b'pe of order is crucially eontrolted by the nature of the anion, la the case of the BF4-and CIOg ~lts the large an[ons ate s'mueture-determining leading to a slightly disturbed anfiferrodistortive order of the elongatr CuJtNs square pyramids at T,-~ 155 K and <130 K, respeet[vely. The resuking pseudo-~etragonal I]-s¨ of the BF 4 eompound is characte¡ by two thombic crystal g tensors (g~allglA = 2.173; gr allg2 A-2.124; gnnllg~^ 2.071). The dibromide sak undergoes a first-ordcr phase transition at Te = 285 K from cubic to tetragonal with a rather Iow cia ratio of about 0.9. The CuUNs square pyramids ha the Low-tcmperature ~-structure are arranged in this case aeeording to a "m[xed ferrodistortive/anª order partero. Interestingly enough the angular dependenee of the g tensor components ]ndicate further structttral ehanges with decreasing temperature, which are of rather local eharaeter, however, not eorrelated with a second phase transit[on. Atomic displaeements lead to reduced Cu~r-Cu" d[stances with[n certain antiferrodistortive pairs, as evideneed by EPR spectroscopy. The molecular g-values at higher temperatures (g~l = 2.243; gi 2.056) transform to those of pairs with eanting aŸ of about 80 ~ (ga = 2.168; g~ = 2.138; g~ = 2.046).

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“…The F positions describe ah orientational disorder of the anions (Fig. 2) similar to that in the related hexaammine complexes MU(NH3)6(BF4)2 with MEE= Co [111 or Ni [12].…”

Section: Crystal Structure Of A-cu(nh3) 5 (Bf4)mentioning

confidence: 97%

An EPR investigation of the phase transitions and cooperative ordering phenomena of pentaamminecopper(II) polyhedra in Cu(NH3)5X2 [X=BF4, CIO4; Br]

1996

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“…; H = natural hydrogen or deuterium), with the K 2 PtCl 6 -type structure have been performed by single crystal neutron diffraction. [10][11][12][13] A common feature in the density maps is four clear hydrogen density maxima in a square planar configuration for each NH 3 unit. The hydrogen density maxima are between the N atom and the four X À anions in the closest face of the surrounding cube of X atoms.…”

mentioning

confidence: 95%

Crystal structure and dynamics of Mg(ND3)6Cl2

Sørby¹,

Løvvik²,

Tsubota³

et al. 2011

Phys. Chem. Chem. Phys.

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The crystal structure and dynamics of Mg(ND(3))(6)Cl(2) have been investigated by powder neutron diffraction and molecular dynamics. The powder diffraction data can be well described by 4 partly occupied deuterium sites in a square arrangement around the N atoms, which is seemingly inconsistent with the 3-fold symmetry of the ND(3) molecule. Molecular dynamics show highly correlated rotational and translational motion of the ND(3) molecules which explains the apparent 4-fold symmetry of the deuterium arrangement. A more disordered structure model based on the molecular dynamics results gives a better fit to the experimental data and is in agreement with the 3-fold symmetry of ND(3).

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“…Data of the same crystal were collected with the fourcircle diffractometer P32 at the Siloe reactor in Grenoble (Hoser, Joswig, Prandl & Vogt, 1985). The step scans (0/20) were evaluated by minimizing tr(I)/I (Lehmann & Larsen, 1974).…”

Section: Comparison With Four-circle Measurementsmentioning

confidence: 99%

Collection of Bragg data with a neutron flat-cone diffractometer

Hohlwein¹,

Hoser²,

Prandl³

1986

J Appl Cryst

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The design and operational principles are presented of a novel neutron diffractometer based on the flat-cone technique which uses a 400-cell one-dimensional multidetector. Setting angles and measuring conditions are given for a generalized flat-cone geometry. Test data were collected from an Ni(NH3)6(NO3) 2 crystal. They are compared with Bragg intensities measured from the same crystal with a conventional four-circle diffractometer. A test for consistency between the two data sets gives R values of 0.019 and 0-031 depending on the weighting scheme. The results of independent structure refinements are in good agreement.

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Orientational disorder in nickel(II)hexammine nitrate

Cited by 9 publications

References 22 publications

An EPR investigation of the phase transitions and cooperative ordering phenomena of pentaamminecopper(II) polyhedra in Cu(NH3)5X2 [X=BF4, CIO4; Br]

An EPR investigation of the phase transitions and cooperative ordering phenomena of pentaamminecopper(II) polyhedra in Cu(NH3)5X2 [X=BF4, CIO4; Br]

Crystal structure and dynamics of Mg(ND3)6Cl2

Collection of Bragg data with a neutron flat-cone diffractometer

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