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Caesium ytterbium diselenide, CsYbSe
2, crystallizes in space group
P6
3/
mmc of the hexagonal system. It is isostructural with CsPrS
2, which has the β-RbScO
2 structure type. In the asymmetric unit, the site symmetries of atoms Cs, Yb and Se are
m2,
m and 3
m, respectively. The structure comprises layers of edge-shared YbSe
6 octahedra perpendicular to [001], with Cs atoms between the layers in a trigonal-prismatic arrangement.
Supporting information
Key indicators
- Single-crystal X-ray study
- T = 153 K
- Mean (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
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
CsYbSe2 | Dx = 6.245 Mg m−3 |
Mr = 463.87 | Mo Kα radiation, λ = 0.71073 Å |
Hexagonal, P63/mmc | Cell parameters from 2727 reflections |
Hall symbol: -P 6c 2c | θ = 2.5–29.0° |
a = 4.1539 (3) Å | µ = 40.78 mm−1 |
c = 16.508 (2) Å | T = 153 K |
V = 246.68 (4) Å3 | Plate, red |
Z = 2 | 0.08 × 0.07 × 0.04 mm |
F(000) = 386 | |
Data collection top
Bruker SMART 1000 CCD diffractometer | 158 independent reflections |
Radiation source: fine-focus sealed tube | 153 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.033 |
0.3° ω scans | θmax = 29.0°, θmin = 2.5° |
Absorption correction: numerical (face-indexed; SHELXTL; Sheldrick, 2003) | h = −5→5 |
Tmin = 0.051, Tmax = 0.201 | k = −5→5 |
2727 measured reflections | l = −21→22 |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary 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 = 1.70 | Δρmax = 1.11 e Å−3 |
158 reflections | Δρmin = −1.58 e Å−3 |
9 parameters | Extinction correction: SHELXL97, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
0 restraints | Extinction 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 | x | y | z | Uiso*/Ueq | |
Cs | 0.3333 | 0.6667 | 0.2500 | 0.0086 (2) | |
Yb | 0.0000 | 0.0000 | 0.0000 | 0.0050 (2) | |
Se | 0.3333 | 0.6667 | 0.59251 (5) | 0.0050 (2) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cs | 0.0098 (3) | 0.0098 (3) | 0.0063 (4) | 0.00489 (14) | 0.000 | 0.000 |
Yb | 0.0051 (2) | 0.0051 (2) | 0.0047 (3) | 0.00256 (12) | 0.000 | 0.000 |
Se | 0.0056 (3) | 0.0056 (3) | 0.0038 (4) | 0.00279 (14) | 0.000 | 0.000 |
Geometric parameters (Å, º) top
Cs—Sei | 3.5370 (6) | Yb—Sev | 2.8432 (5) |
Cs—Seii | 3.5370 (6) | Yb—Sexv | 2.8432 (5) |
Cs—Seiii | 3.5370 (6) | Yb—Sexvi | 2.8432 (5) |
Cs—Seiv | 3.5370 (6) | Yb—Ybviii | 4.1539 (3) |
Cs—Sev | 3.5370 (6) | Yb—Ybvii | 4.1539 (3) |
Cs—Sevi | 3.5370 (6) | Yb—Ybix | 4.1539 (3) |
Cs—Csvii | 4.1539 (3) | Yb—Ybxii | 4.1539 (3) |
Cs—Csviii | 4.1539 (3) | Yb—Ybx | 4.1539 (3) |
Cs—Csix | 4.1539 (3) | Yb—Ybxi | 4.1539 (3) |
Cs—Csx | 4.1539 (3) | Se—Ybxvii | 2.8432 (5) |
Cs—Csxi | 4.1539 (3) | Se—Ybxviii | 2.8432 (5) |
Cs—Csxii | 4.1539 (3) | Se—Ybxix | 2.8432 (5) |
Yb—Sexiii | 2.8432 (5) | Se—Csii | 3.5370 (6) |
Yb—Sei | 2.8432 (5) | Se—Csiv | 3.5370 (6) |
Yb—Sexiv | 2.8432 (5) | Se—Csvi | 3.5370 (6) |
| | | |
Sei—Cs—Seii | 140.365 (8) | Sexiv—Yb—Sexv | 93.855 (19) |
Sei—Cs—Seiii | 71.918 (15) | Sev—Yb—Sexv | 86.145 (19) |
Seii—Cs—Seiii | 94.617 (19) | Sexiii—Yb—Sexvi | 86.145 (19) |
Sei—Cs—Seiv | 94.617 (19) | Sei—Yb—Sexvi | 93.855 (19) |
Seii—Cs—Seiv | 71.918 (15) | Sexiv—Yb—Sexvi | 86.145 (19) |
Seiii—Cs—Seiv | 140.365 (7) | Sev—Yb—Sexvi | 93.855 (19) |
Sei—Cs—Sev | 71.918 (15) | Sexv—Yb—Sexvi | 180.00 (3) |
Seii—Cs—Sev | 140.365 (8) | Ybxvii—Se—Ybxviii | 93.855 (19) |
Seiii—Cs—Sev | 71.918 (15) | Ybxvii—Se—Ybxix | 93.855 (19) |
Seiv—Cs—Sev | 140.365 (8) | Ybxviii—Se—Ybxix | 93.855 (19) |
Sei—Cs—Sevi | 140.365 (7) | Ybxvii—Se—Csii | 96.248 (8) |
Seii—Cs—Sevi | 71.918 (15) | Ybxviii—Se—Csii | 165.18 (2) |
Seiii—Cs—Sevi | 140.365 (8) | Ybxix—Se—Csii | 96.248 (8) |
Seiv—Cs—Sevi | 71.918 (15) | Ybxvii—Se—Csiv | 96.248 (8) |
Sev—Cs—Sevi | 94.617 (19) | Ybxviii—Se—Csiv | 96.248 (8) |
Sexiii—Yb—Sei | 180.00 (3) | Ybxix—Se—Csiv | 165.18 (2) |
Sexiii—Yb—Sexiv | 93.855 (19) | Csii—Se—Csiv | 71.918 (15) |
Sei—Yb—Sexiv | 86.145 (19) | Ybxvii—Se—Csvi | 165.18 (2) |
Sexiii—Yb—Sev | 86.145 (19) | Ybxviii—Se—Csvi | 96.248 (8) |
Sei—Yb—Sev | 93.855 (19) | Ybxix—Se—Csvi | 96.248 (8) |
Sexiv—Yb—Sev | 180.00 (3) | Csii—Se—Csvi | 71.918 (15) |
Sexiii—Yb—Sexv | 93.855 (19) | Csiv—Se—Csvi | 71.918 (15) |
Sei—Yb—Sexv | 86.145 (19) | | |
Symmetry codes: (i) −x, −y+1, z−1/2; (ii) −x+1, −y+2, −z+1; (iii) −x+1, −y+2, z−1/2; (iv) −x, −y+1, −z+1; (v) −x+1, −y+1, z−1/2; (vi) −x+1, −y+1, −z+1; (vii) x−1, y−1, z; (viii) x+1, y+1, z; (ix) x, y−1, z; (x) x+1, y, z; (xi) x, y+1, z; (xii) x−1, y, z; (xiii) x, y−1, −z+1/2; (xiv) x−1, y−1, −z+1/2; (xv) x, y, −z+1/2; (xvi) −x, −y, z−1/2; (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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