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Caesium ytterbium diselenide, CsYbSe2, crystallizes in space group P63/mmc of the hexagonal system. It is isostructural with CsPrS2, which has the β-RbScO2 structure type. In the asymmetric unit, the site symmetries of atoms Cs, Yb and Se are \overline{6}m2, \overline{3}m and 3m, respectively. The structure comprises layers of edge-shared YbSe6 octahedra perpendicular to [001], with Cs atoms between the layers in a trigonal-prismatic arrangement.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536805001157/wm6047sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536805001157/wm6047Isup2.hkl
Contains datablock I

Key indicators

  • Single-crystal X-ray study
  • T = 153 K
  • Mean [sigma](b-Se) = 0.001 Å
  • R factor = 0.019
  • wR factor = 0.041
  • Data-to-parameter ratio = 17.6

checkCIF/PLATON results

No syntax errors found



Alert level A PLAT029_ALERT_3_A _diffrn_measured_fraction_theta_full Low ....... 0.94
Author Response: .. Diffraction data were measured out to 58 deg 2theta by 0.3 deg omega scans at phi values of 0, 90, 180, and 270 deg. on a Bruker CCD-1000 diffractometer. This prescription for data collection leads to high inherent redundancy. Given the Laue symmetry the redundancy is even higher, on average about 17:1 (2727 measured reflections, 158 independent reflections). Although it is not clear to me how the actual calculation _diffrn_measured_fraction_theta_full Low ....... 0.94 is made, if we assume it is based on the number of independent reflections then perhaps 10 independent reflections are missing. Given the small cell and some inherent limitations in the geometry of the Bruker, 10 missing reflections are hardly surprising! Personally, I do not think we have a "serious problem" here.

1 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 0 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 0 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 1 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion

Computing details top

Data collection: SMART (Bruker, 2003); cell refinement: SAINT (Bruker, 2003); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2003); program(s) used to refine structure: SHELXL97 in SHELXTL; molecular graphics: XP in SHELXTL; software used to prepare material for publication: SHELXTL.

Caesium ytterbium diselenide top
Crystal data top
CsYbSe2Dx = 6.245 Mg m3
Mr = 463.87Mo Kα radiation, λ = 0.71073 Å
Hexagonal, P63/mmcCell parameters from 2727 reflections
Hall symbol: -P 6c 2cθ = 2.5–29.0°
a = 4.1539 (3) ŵ = 40.78 mm1
c = 16.508 (2) ÅT = 153 K
V = 246.68 (4) Å3Plate, red
Z = 20.08 × 0.07 × 0.04 mm
F(000) = 386
Data collection top
Bruker SMART 1000 CCD
diffractometer
158 independent reflections
Radiation source: fine-focus sealed tube153 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.033
0.3° ω scansθmax = 29.0°, θmin = 2.5°
Absorption correction: numerical
(face-indexed; SHELXTL; Sheldrick, 2003)
h = 55
Tmin = 0.051, Tmax = 0.201k = 55
2727 measured reflectionsl = 2122
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.019 w = 1/[σ2(Fo2) + (0.017P)2]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.041(Δ/σ)max < 0.001
S = 1.70Δρmax = 1.11 e Å3
158 reflectionsΔρmin = 1.58 e Å3
9 parametersExtinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0231 (15)
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
Cs0.33330.66670.25000.0086 (2)
Yb0.00000.00000.00000.0050 (2)
Se0.33330.66670.59251 (5)0.0050 (2)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cs0.0098 (3)0.0098 (3)0.0063 (4)0.00489 (14)0.0000.000
Yb0.0051 (2)0.0051 (2)0.0047 (3)0.00256 (12)0.0000.000
Se0.0056 (3)0.0056 (3)0.0038 (4)0.00279 (14)0.0000.000
Geometric parameters (Å, º) top
Cs—Sei3.5370 (6)Yb—Sev2.8432 (5)
Cs—Seii3.5370 (6)Yb—Sexv2.8432 (5)
Cs—Seiii3.5370 (6)Yb—Sexvi2.8432 (5)
Cs—Seiv3.5370 (6)Yb—Ybviii4.1539 (3)
Cs—Sev3.5370 (6)Yb—Ybvii4.1539 (3)
Cs—Sevi3.5370 (6)Yb—Ybix4.1539 (3)
Cs—Csvii4.1539 (3)Yb—Ybxii4.1539 (3)
Cs—Csviii4.1539 (3)Yb—Ybx4.1539 (3)
Cs—Csix4.1539 (3)Yb—Ybxi4.1539 (3)
Cs—Csx4.1539 (3)Se—Ybxvii2.8432 (5)
Cs—Csxi4.1539 (3)Se—Ybxviii2.8432 (5)
Cs—Csxii4.1539 (3)Se—Ybxix2.8432 (5)
Yb—Sexiii2.8432 (5)Se—Csii3.5370 (6)
Yb—Sei2.8432 (5)Se—Csiv3.5370 (6)
Yb—Sexiv2.8432 (5)Se—Csvi3.5370 (6)
Sei—Cs—Seii140.365 (8)Sexiv—Yb—Sexv93.855 (19)
Sei—Cs—Seiii71.918 (15)Sev—Yb—Sexv86.145 (19)
Seii—Cs—Seiii94.617 (19)Sexiii—Yb—Sexvi86.145 (19)
Sei—Cs—Seiv94.617 (19)Sei—Yb—Sexvi93.855 (19)
Seii—Cs—Seiv71.918 (15)Sexiv—Yb—Sexvi86.145 (19)
Seiii—Cs—Seiv140.365 (7)Sev—Yb—Sexvi93.855 (19)
Sei—Cs—Sev71.918 (15)Sexv—Yb—Sexvi180.00 (3)
Seii—Cs—Sev140.365 (8)Ybxvii—Se—Ybxviii93.855 (19)
Seiii—Cs—Sev71.918 (15)Ybxvii—Se—Ybxix93.855 (19)
Seiv—Cs—Sev140.365 (8)Ybxviii—Se—Ybxix93.855 (19)
Sei—Cs—Sevi140.365 (7)Ybxvii—Se—Csii96.248 (8)
Seii—Cs—Sevi71.918 (15)Ybxviii—Se—Csii165.18 (2)
Seiii—Cs—Sevi140.365 (8)Ybxix—Se—Csii96.248 (8)
Seiv—Cs—Sevi71.918 (15)Ybxvii—Se—Csiv96.248 (8)
Sev—Cs—Sevi94.617 (19)Ybxviii—Se—Csiv96.248 (8)
Sexiii—Yb—Sei180.00 (3)Ybxix—Se—Csiv165.18 (2)
Sexiii—Yb—Sexiv93.855 (19)Csii—Se—Csiv71.918 (15)
Sei—Yb—Sexiv86.145 (19)Ybxvii—Se—Csvi165.18 (2)
Sexiii—Yb—Sev86.145 (19)Ybxviii—Se—Csvi96.248 (8)
Sei—Yb—Sev93.855 (19)Ybxix—Se—Csvi96.248 (8)
Sexiv—Yb—Sev180.00 (3)Csii—Se—Csvi71.918 (15)
Sexiii—Yb—Sexv93.855 (19)Csiv—Se—Csvi71.918 (15)
Sei—Yb—Sexv86.145 (19)
Symmetry codes: (i) x, y+1, z1/2; (ii) x+1, y+2, z+1; (iii) x+1, y+2, z1/2; (iv) x, y+1, z+1; (v) x+1, y+1, z1/2; (vi) x+1, y+1, z+1; (vii) x1, y1, z; (viii) x+1, y+1, z; (ix) x, y1, z; (x) x+1, y, z; (xi) x, y+1, z; (xii) x1, y, z; (xiii) x, y1, z+1/2; (xiv) x1, y1, z+1/2; (xv) x, y, z+1/2; (xvi) x, y, z1/2; (xvii) x, y+1, z+1/2; (xviii) x, y, z+1/2; (xix) x+1, y+1, z+1/2.
 

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