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The crystal structure of mercury(II) chromium(III) tetroxide has been redetermined from a single crystal grown from an HgO-CrO3 mixture at 743 K in an evacuated silica ampoule. The present investigation confirms the previous study, which was based on powder data [Wessels, Czekalla & Jeitschko (1998). Mater. Res. Bull. 33, 95-191], but with higher precision and with all displacement parameters refined anisotropically. HgCr2O4 adopts the normal 2-3-spinel structure, with mercury in one-eighth of the tetra­hedral and chromium in one-half of the octa­hedral voids of the cubic closed-packed O atoms.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536806033952/br2011sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536806033952/br2011Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](r-O) = 0.001 Å
  • R factor = 0.011
  • wR factor = 0.023
  • Data-to-parameter ratio = 15.3

checkCIF/PLATON results

No syntax errors found



Alert level C PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings Differ .... ? PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............ 0.25 Ratio PLAT127_ALERT_1_C Implicit Hall Symbol Inconsistent with Explicit -F 4vw 2vw
Alert level G REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF. From the CIF: _diffrn_reflns_theta_max 39.95 From the CIF: _reflns_number_total 122 Count of symmetry unique reflns 0 Completeness (_total/calc) Infinity % TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 122 Fraction of Friedel pairs measured Infinity Are heavy atom types Z>Si present yes PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature 293 K PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature . 293 K
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 3 ALERT level G = General alerts; check 5 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 0 ALERT type 2 Indicator that the structure model may be wrong or deficient 0 ALERT type 3 Indicator that the structure quality may be low 1 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Computing details top

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software; data reduction: HELENA implemented in PLATON (Spek, 2003); program(s) used to solve structure: coordinates taken from a previous refinement; program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ATOMS (Dowty, 2000); software used to prepare material for publication: SHELXL97.

Mercury(II) chromium(III) tetroxide top
Crystal data top
HgCr2O4Dx = 7.580 Mg m3
Mr = 368.59Mo Kα radiation, λ = 0.71073 Å
Cubic, Fd3mCell parameters from 25 reflections
Hall symbol: -F 4vw 2vwθ = 10.3–15.6°
a = 8.6443 (3) ŵ = 53.86 mm1
V = 645.94 (4) Å3T = 293 K
Z = 8Octahedron, black
F(000) = 12800.06 × 0.05 × 0.05 mm
Data collection top
Enraf–Nonius CAD-4
diffractometer
114 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.099
Graphite monochromatorθmax = 40.0°, θmin = 4.1°
ω/2θ scansh = 1515
Absorption correction: numerical
(HABITUS; Herrendorf, 1997)
k = 1515
Tmin = 0.093, Tmax = 0.216l = 1515
3703 measured reflections3 standard reflections every 200 min
122 independent reflections intensity decay: none
Refinement top
Refinement on F2Primary atom site location: isomorphous structure methods
Least-squares matrix: full w = 1/[σ2(Fo2) + 1.36P]
where P = (Fo2 + 2Fc2)/3
R[F2 > 2σ(F2)] = 0.011(Δ/σ)max < 0.001
wR(F2) = 0.023Δρmax = 1.18 e Å3
S = 1.15Δρmin = 1.66 e Å3
122 reflectionsExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
8 parametersExtinction coefficient: 0.00043 (12)
0 restraints
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Hg0.37500.37500.37500.00884 (9)
Cr0.00000.00000.00000.00544 (10)
O10.22968 (14)0.22968 (14)0.22968 (14)0.0072 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Hg0.00884 (9)0.00884 (9)0.00884 (9)0.0000.0000.000
Cr0.00544 (10)0.00544 (10)0.00544 (10)0.00027 (11)0.00027 (11)0.00027 (11)
O10.0072 (3)0.0072 (3)0.0072 (3)0.0011 (3)0.0011 (3)0.0011 (3)
Geometric parameters (Å, º) top
Hg—O12.176 (2)Cr—O1vii2.0009 (10)
Hg—O1i2.176 (2)Cr—O1viii2.0009 (10)
Hg—O1ii2.176 (2)Cr—O1ix2.0009 (10)
Hg—O1iii2.176 (2)O1—Crix2.0009 (10)
Cr—O1iv2.0009 (10)O1—Crvii2.0009 (10)
Cr—O1v2.0009 (10)O1—Crv2.0009 (10)
Cr—O1vi2.0009 (10)
O1—Hg—O1i109.5O1vi—Cr—O1viii79.52 (8)
O1—Hg—O1ii109.5O1vii—Cr—O1viii180.000 (9)
O1i—Hg—O1ii109.5O1iv—Cr—O1ix180.000 (9)
O1—Hg—O1iii109.5O1v—Cr—O1ix79.52 (8)
O1i—Hg—O1iii109.5O1vi—Cr—O1ix100.48 (8)
O1ii—Hg—O1iii109.5O1vii—Cr—O1ix79.52 (8)
O1iv—Cr—O1v100.48 (8)O1viii—Cr—O1ix100.48 (8)
O1iv—Cr—O1vi79.52 (8)Crix—O1—Crvii99.58 (7)
O1v—Cr—O1vi180.000 (9)Crix—O1—Crv99.58 (7)
O1iv—Cr—O1vii100.48 (8)Crvii—O1—Crv99.58 (7)
O1v—Cr—O1vii79.52 (8)Crix—O1—Hg118.13 (5)
O1vi—Cr—O1vii100.48 (8)Crvii—O1—Hg118.13 (5)
O1iv—Cr—O1viii79.52 (8)Crv—O1—Hg118.13 (5)
O1v—Cr—O1viii100.48 (8)
Symmetry codes: (i) x, y+3/4, z+3/4; (ii) x+3/4, y+3/4, z; (iii) x+3/4, y, z+3/4; (iv) x, y1/4, z1/4; (v) x+1/4, y+1/4, z; (vi) x1/4, y1/4, z; (vii) x+1/4, y, z+1/4; (viii) x1/4, y, z1/4; (ix) x, y+1/4, z+1/4.
 

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