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The structure of the title compound, [Sn(CH2I)4], consists of Sn situated on a crystallographic fourfold rotatory inversion axis, with pendant iodomethyl groups whose atoms are in general positions. In the molecule, with overall crystallographically imposed S4 molecular symmetry, there is little, if any, distortion of the tetrahedral environment of Sn, but the bulk of I leads to opening up of the Sn-C-I angle to 112.4 (3)°.
Supporting information
CCDC reference: 182582
Key indicators
- Single-crystal X-ray study
- T = 298 K
- Mean (Sn-C) = 0.008 Å
- R factor = 0.038
- wR factor = 0.105
- Data-to-parameter ratio = 56.7
checkCIF results
No syntax errors found
ADDSYM reports no extra symmetry
General Notes
ABSTM_02 When printed, the submitted absorption T values will be replaced
by the scaled T values. Since the ratio of scaled T's is
identical to the ratio of reported T values, the scaling does
not imply a change to the absorption corrections used in the
study.
Ratio of Tmax expected/reported 0.112
Tmax scaled 0.104 Tmin scaled 0.046
REFLT_03
From the CIF: _diffrn_reflns_theta_max 32.64
From the CIF: _reflns_number_total 1191
Count of symmetry unique reflns 702
Completeness (_total/calc) 169.66%
TEST3: Check Friedels for noncentro structure
Estimate of Friedel pairs measured 489
Fraction of Friedel pairs measured 0.697
Are heavy atom types Z>Si present yes
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.
Compound (I), prepared as described by Burnett et al. (1998) (m.p.
348–349 K) and recrystallized from CHCl3, provided crystals suitable for
analysis.
H atoms were placed in calculated positions, with C—H = 0.97 Å, and refined
with a riding model, with Uiso = 1.2Ueq(C). The absolute
configuration was determined on the basis of 492 Friedel pairs.
Data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.
Tetrakis(iodomethyl)stannane
top
Crystal data top
[Sn(CH2I)4] | Dx = 3.462 Mg m−3 |
Mr = 682.40 | Mo Kα radiation, λ = 0.71073 Å |
Tetragonal, P421c | Cell parameters from 3436 reflections |
a = 9.4019 (5) Å | θ = 3.1–30.5° |
c = 7.4051 (4) Å | µ = 11.33 mm−1 |
V = 654.58 (6) Å3 | T = 298 K |
Z = 2 | Block, colourless |
F(000) = 588 | 0.40 × 0.20 × 0.20 mm |
Data collection top
Bruker SMART 1000 CCD area-detector diffractometer | 1191 independent reflections |
Radiation source: fine-focus sealed tube | 1044 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.030 |
ϕ and ω scans | θmax = 32.6°, θmin = 3.1° |
Absorption correction: multi-scan (SADABS; Bruker, 1999) | h = −12→14 |
Tmin = 0.416, Tmax = 0.928 | k = −14→13 |
6440 measured reflections | l = −11→10 |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.038 | H-atom parameters constrained |
wR(F2) = 0.105 | w = 1/[σ2(Fo2) + (0.0512P)2 + 1.6332P] where P = (Fo2 + 2Fc2)/3 |
S = 1.08 | (Δ/σ)max < 0.001 |
1191 reflections | Δρmax = 0.82 e Å−3 |
21 parameters | Δρmin = −1.58 e Å−3 |
0 restraints | Absolute structure: (Flack, 1983) |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.06 (18) |
Crystal data top
[Sn(CH2I)4] | Z = 2 |
Mr = 682.40 | Mo Kα radiation |
Tetragonal, P421c | µ = 11.33 mm−1 |
a = 9.4019 (5) Å | T = 298 K |
c = 7.4051 (4) Å | 0.40 × 0.20 × 0.20 mm |
V = 654.58 (6) Å3 | |
Data collection top
Bruker SMART 1000 CCD area-detector diffractometer | 1191 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 1999) | 1044 reflections with I > 2σ(I) |
Tmin = 0.416, Tmax = 0.928 | Rint = 0.030 |
6440 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.038 | H-atom parameters constrained |
wR(F2) = 0.105 | Δρmax = 0.82 e Å−3 |
S = 1.08 | Δρmin = −1.58 e Å−3 |
1191 reflections | Absolute structure: (Flack, 1983) |
21 parameters | Absolute structure parameter: 0.06 (18) |
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. Sn in 2 b s pecial positions of space group P-42 (1)c i.e. molecule has
-4 site symmetry. Anisotropic displacement parameters refined for all non-H
atoms. H in calculated positions and refined with a riding model. Absolute structure from 492 Friedel pairs. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Sn1 | 0.5000 | 0.5000 | 1.0000 | 0.04091 (18) | |
I1 | 0.44403 (8) | 0.77733 (7) | 0.68654 (11) | 0.0749 (2) | |
C1 | 0.3508 (7) | 0.6061 (8) | 0.8344 (13) | 0.0552 (18) | |
H1A | 0.2745 | 0.6429 | 0.9092 | 0.066* | |
H1B | 0.3098 | 0.5385 | 0.7502 | 0.066* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Sn1 | 0.0360 (2) | 0.0360 (2) | 0.0507 (4) | 0.000 | 0.000 | 0.000 |
I1 | 0.0710 (4) | 0.0710 (4) | 0.0827 (4) | 0.0096 (3) | 0.0129 (3) | 0.0293 (3) |
C1 | 0.041 (3) | 0.049 (3) | 0.075 (5) | −0.004 (3) | −0.008 (3) | 0.006 (3) |
Geometric parameters (Å, º) top
Sn1—C1 | 2.114 (8) | C1—H1A | 0.9700 |
I1—C1 | 2.135 (8) | C1—H1B | 0.9700 |
| | | |
C1—Sn1—C1i | 109.1 (5) | I1—C1—H1A | 109.1 |
C1—Sn1—C1ii | 109.7 (3) | Sn1—C1—H1B | 109.1 |
Sn1—C1—I1 | 112.4 (3) | I1—C1—H1B | 109.1 |
Sn1—C1—H1A | 109.1 | H1A—C1—H1B | 107.9 |
Symmetry codes: (i) −x+1, −y+1, z; (ii) −y+1, x, −z+2. |
Experimental details
Crystal data |
Chemical formula | [Sn(CH2I)4] |
Mr | 682.40 |
Crystal system, space group | Tetragonal, P421c |
Temperature (K) | 298 |
a, c (Å) | 9.4019 (5), 7.4051 (4) |
V (Å3) | 654.58 (6) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 11.33 |
Crystal size (mm) | 0.40 × 0.20 × 0.20 |
|
Data collection |
Diffractometer | Bruker SMART 1000 CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 1999) |
Tmin, Tmax | 0.416, 0.928 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6440, 1191, 1044 |
Rint | 0.030 |
(sin θ/λ)max (Å−1) | 0.759 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.105, 1.08 |
No. of reflections | 1191 |
No. of parameters | 21 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.82, −1.58 |
Absolute structure | (Flack, 1983) |
Absolute structure parameter | 0.06 (18) |
Selected geometric parameters (Å, º) topSn1—C1 | 2.114 (8) | I1—C1 | 2.135 (8) |
| | | |
C1—Sn1—C1i | 109.1 (5) | Sn1—C1—I1 | 112.4 (3) |
C1—Sn1—C1ii | 109.7 (3) | | |
Symmetry codes: (i) −x+1, −y+1, z; (ii) −y+1, x, −z+2. |
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The asymmetric unit of the title compound, (I), consists of Sn in the 2 b s pecial positions of the space group P421c along with, in the 8 e general positions, C, I and two H atoms of a single representative iodomethyl group. As a consequence, relatively high D2 d symmetry is imposed upon the molecule as a whole, which is shown in Fig. 1, and results in the very compact presentation of symmetry unique bond lengths and angles in Table 2. The bond distances are much as would be anticipated for a molecule of this type. The bond-angle data show that there is no real distortion of the tetrahedral coordination of Sn. However, the Sn1—C1—I1 angle of 112.4 (3)° is clearly attributable to the physical bulk of the I atom.