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The title compound, Cs[As(CH
3)
2Se
2], contains discrete tetrahedral dimethyldiselenidoarsenate(V) anions and Cs cations, with As and Cs located on a crystallographic twofold rotation axis. A distorted octahedral coordination is observed for the caesium counter-cation, with Cs
Se distances in the range 3.706 (2)–3.762 (2) Å.
Supporting information
CCDC reference: 293836
Key indicators
- Single-crystal X-ray study
- T = 292 K
- Mean (s-C) = 0.018 Å
- R factor = 0.047
- wR factor = 0.125
- Data-to-parameter ratio = 25.3
checkCIF/PLATON results
No syntax errors found
Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ .... ?
PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent ..... ?
PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for As
PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) . 1.11 Ratio
0 ALERT level A = In general: serious problem
0 ALERT level B = Potentially serious problem
4 ALERT level C = Check and explain
0 ALERT level G = General alerts; check
2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
1 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
Data collection: R3m/V (Siemens, 1989); cell refinement: R3m/V; data reduction: XDISK (Siemens, 1989); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-Plus (Sheldrick, 1995); software used to prepare material for publication: SHELXL97.
Caesium dimethyldiselenidoarsenate(V)
top
Crystal data top
Cs+·C2H6AsSe2− | F(000) = 696 |
Mr = 395.82 | Dx = 3.022 Mg m−3 |
Monoclinic, C2/c | Melting point: not relevant K |
Hall symbol: -C 2yc | Mo Kα radiation, λ = 0.71073 Å |
a = 9.858 (2) Å | Cell parameters from 19 reflections |
b = 10.027 (2) Å | θ = 6.1–14.9° |
c = 9.787 (2) Å | µ = 16.30 mm−1 |
β = 115.92 (3)° | T = 292 K |
V = 870.1 (3) Å3 | Block, colourless |
Z = 4 | 0.12 × 0.10 × 0.08 mm |
Data collection top
Siemens P4 four-circle diffractometer | 574 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.047 |
Graphite monochromator | θmax = 25.0°, θmin = 3.1° |
ω scans | h = 0→11 |
Absorption correction: ψ scan (XPREP in SHELXTL-Plus; Sheldrick, 1995) | k = 0→11 |
Tmin = 0.153, Tmax = 0.275 | l = −11→10 |
807 measured reflections | 3 standard reflections every 97 reflections |
759 independent reflections | intensity decay: 0.0% |
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)] = 0.047 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.125 | H-atom parameters constrained |
S = 1.08 | w = 1/[σ2(Fo2) + (0.066P)2 + 8.7148P] where P = (Fo2 + 2Fc2)/3 |
759 reflections | (Δ/σ)max < 0.001 |
30 parameters | Δρmax = 1.13 e Å−3 |
0 restraints | Δρmin = −1.20 e Å−3 |
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 | 0.5000 | 0.38863 (11) | 0.2500 | 0.0507 (4) | |
As | 0.5000 | 0.82632 (16) | 0.2500 | 0.0443 (5) | |
Se | 0.36573 (16) | 0.70919 (13) | 0.34653 (16) | 0.0514 (4) | |
C | 0.364 (2) | 0.9413 (17) | 0.0924 (19) | 0.084 (6) | |
H1 | 0.3011 | 0.9882 | 0.1288 | 0.126* | |
H2 | 0.3016 | 0.8887 | 0.0054 | 0.126* | |
H3 | 0.4205 | 1.0043 | 0.0644 | 0.126* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Cs | 0.0502 (7) | 0.0507 (6) | 0.0482 (7) | 0.000 | 0.0188 (5) | 0.000 |
As | 0.0524 (11) | 0.0365 (9) | 0.0520 (11) | 0.000 | 0.0301 (9) | 0.000 |
Se | 0.0509 (8) | 0.0529 (7) | 0.0568 (8) | −0.0006 (7) | 0.0294 (6) | 0.0079 (6) |
C | 0.106 (13) | 0.085 (11) | 0.086 (12) | 0.051 (10) | 0.064 (11) | 0.050 (10) |
Geometric parameters (Å, º) top
Cs—Sei | 3.7063 (17) | As—C | 1.924 (14) |
Cs—Seii | 3.7063 (17) | As—Se | 2.2621 (15) |
Cs—Se | 3.7509 (18) | As—Seiii | 2.2621 (15) |
Cs—Seiii | 3.7509 (18) | C—H1 | 0.9600 |
Cs—Seiv | 3.7617 (17) | C—H2 | 0.9600 |
Cs—Sev | 3.7617 (17) | C—H3 | 0.9600 |
As—Ciii | 1.924 (14) | | |
| | | |
Sei—Cs—Seii | 149.31 (5) | C—As—Se | 108.4 (5) |
Sei—Cs—Se | 119.61 (4) | Ciii—As—Seiii | 108.4 (5) |
Seii—Cs—Se | 87.67 (3) | C—As—Seiii | 107.9 (5) |
Sei—Cs—Seiii | 87.67 (3) | Se—As—Seiii | 117.45 (10) |
Seii—Cs—Seiii | 119.61 (4) | As—Se—Csii | 125.50 (6) |
Se—Cs—Seiii | 62.05 (4) | As—Se—Cs | 90.25 (5) |
Sei—Cs—Seiv | 75.47 (4) | Csii—Se—Cs | 92.33 (3) |
Seii—Cs—Seiv | 89.87 (4) | As—Se—Csvi | 108.56 (6) |
Se—Cs—Seiv | 93.91 (2) | Csii—Se—Csvi | 104.53 (4) |
Seiii—Cs—Seiv | 138.73 (5) | Cs—Se—Csvi | 138.73 (5) |
Sei—Cs—Sev | 89.87 (4) | As—C—H1 | 109.5 |
Seii—Cs—Sev | 75.47 (4) | As—C—H2 | 109.5 |
Se—Cs—Sev | 138.73 (5) | H1—C—H2 | 109.5 |
Seiii—Cs—Sev | 93.91 (2) | As—C—H3 | 109.5 |
Seiv—Cs—Sev | 122.85 (5) | H1—C—H3 | 109.5 |
Ciii—As—C | 106.4 (12) | H2—C—H3 | 109.5 |
Ciii—As—Se | 107.9 (5) | | |
| | | |
Ciii—As—Se—Csii | −29.7 (6) | Seiv—Cs—Se—As | −144.75 (6) |
C—As—Se—Csii | −144.5 (6) | Sev—Cs—Se—As | 60.82 (8) |
Seiii—As—Se—Csii | 93.04 (6) | Sei—Cs—Se—Csii | 165.21 (3) |
Ciii—As—Se—Cs | −122.7 (6) | Seii—Cs—Se—Csii | 0.0 |
C—As—Se—Cs | 122.5 (6) | Seiii—Cs—Se—Csii | −125.55 (6) |
Seiii—As—Se—Cs | 0.0 | Seiv—Cs—Se—Csii | 89.71 (4) |
Ciii—As—Se—Csvi | 94.7 (6) | Sev—Cs—Se—Csii | −64.73 (7) |
C—As—Se—Csvi | −20.1 (6) | Sei—Cs—Se—Csvi | 49.94 (8) |
Seiii—As—Se—Csvi | −142.59 (6) | Seii—Cs—Se—Csvi | −115.27 (7) |
Sei—Cs—Se—As | −69.25 (6) | Seiii—Cs—Se—Csvi | 119.18 (8) |
Seii—Cs—Se—As | 125.55 (6) | Seiv—Cs—Se—Csvi | −25.56 (5) |
Seiii—Cs—Se—As | 0.0 | Sev—Cs—Se—Csvi | 180.0 |
Symmetry codes: (i) x, −y+1, z−1/2; (ii) −x+1, −y+1, −z+1; (iii) −x+1, y, −z+1/2; (iv) −x+1/2, y−1/2, −z+1/2; (v) x+1/2, y−1/2, z; (vi) x−1/2, y+1/2, z. |
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