Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807044273/gw2023sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807044273/gw2023Isup2.hkl |
CCDC reference: 664189
Key indicators
- Single-crystal X-ray study
- T = 273 K
- Mean (C-C) = 0.007 Å
- R factor = 0.024
- wR factor = 0.087
- Data-to-parameter ratio = 12.1
checkCIF/PLATON results
No syntax errors found
Alert level B PLAT027_ALERT_3_B _diffrn_reflns_theta_full (too) Low ............ 24.98 Deg.
Alert level C GOODF01_ALERT_2_C The least squares goodness of fit parameter lies outside the range 0.80 <> 2.00 Goodness of fit given = 0.740 PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given ....... ? PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent ..... ? PLAT241_ALERT_2_C Check High Ueq as Compared to Neighbors for O3 PLAT242_ALERT_2_C Check Low Ueq as Compared to Neighbors for Sn
Alert level G REFLT03_ALERT_4_G WARNING: Large fraction of Friedel related reflns may be needed to determine absolute structure From the CIF: _diffrn_reflns_theta_max 24.98 From the CIF: _reflns_number_total 2329 Count of symmetry unique reflns 1557 Completeness (_total/calc) 149.58% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 772 Fraction of Friedel pairs measured 0.496 Are heavy atom types Z>Si present yes PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints ....... 1
0 ALERT level A = In general: serious problem 1 ALERT level B = Potentially serious problem 5 ALERT level C = Check and explain 2 ALERT level G = General alerts; check 1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 3 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check
checkCIF publication errors
Alert level A PUBL024_ALERT_1_A The number of authors is greater than 5. Please specify the role of each of the co-authors for your paper.
Author Response: This work is part of a wide collaborative project which involves synthesis, sample preparations, activities tests, diffraction data collection and data analysis. Students also participate in the project. |
1 ALERT level A = Data missing that is essential or data in wrong format 0 ALERT level G = General alerts. Data that may be required is missing
To a round-botton flask charged with 3-[(carboxyphenyl)amino]cyclohexen-2-one (1.0 g, 4.32 mmol) and triethylamine (0.6 ml, 4.32 mmol) dissolved in methanol (20 ml), was added trimethyltin chloride (0.86 g, 4.32 mmol). The X-ray quality crystals were obtained from a methanol/water (3:1) solution. IR (ν/cm-1): 473 (νSn—O). 1H NMR (δ, CDCl3): 8.63 d (C6), 8.0 m (C8, C9), 7.7 m (C7) 6.23 s (C16), 3.0 m (C14), 2.8 m (C12), 2.47 m (C13), 1.58 s (C1, 2, 3). 13C-NMR (δ, CDCl3): 199.5 (C15), 173.4 (C4), 162.5 (C11), 141.8 (C10), 133.9 (C6), 133.6 (C8), 124.3 (C5), 124.2 (C2), 101.58 (C7), 101.56 (C16), 37.5 (C14), 31.2 (C12), 22.8 (C13), 11.7 (C1, 2, 3), 119Sn-NMR (δ, CDCl3): 97.6, 119Sn Mossbauer (mm.s-1): δ 1.32, Δ 3.52, Elemental Analysis (%) for C16H21NO3Sn found (calc.): C 48.41 (48.76), H 5.37 (5.38), N 3.46 (3.55).
Fourier difference in the structure determination stage evidenced most of the H atoms in the structure; nevertheless, their positions were subsequently calculated and refined using a riding model approximation. All non-H atoms were refined anisotropically.
The reaction of 2-(3-oxocyclohex-1-enyl)benzoic acid (Vieira et al., 2007) with Sn(CH3)3Cl in the presence of triethylamine yielded the title complex. The X-ray crystallographic study revealed that it crystallizes forming an infinity double-polymeric chain structure, where the anionic ligand bridges two tin centre via the monodentate carboxylic moiety and the C?O fragment, Fig. 1. The structure possess one tin atom surrounded by three methyl groups and two oxygen atoms, describing an almost perfect trigonal bypiramid. The equatorial corners are occupied by the methyl groups and the axial positions by the oxygen atoms. The angles C1—Sn—C2 and O1—Sn—O3 are all near 120° and 180° as expected for a trigonal bypiramid.
For related literature, see: Vieira et al. (2007).
Data collection: XSCANS (Siemens, 1991); cell refinement: XSCANS (Siemens, 1991); data reduction: XSCANS (Siemens, 1991); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL/PC (Sheldrick, 1990); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).
Fig. 1. Monomeric structure of poly-[trimethyltin-3-{(carboxyphenyl)amino} cyclohexen-2-one] |
[Sn(CH3)3(C13H13NO3)] | Dx = 1.534 Mg m−3 |
Mr = 394.03 | Melting point = 440–443 K |
Orthorhombic, Fdd2 | Mo Kα radiation, λ = 0.71073 Å |
a = 30.626 (5) Å | Cell parameters from 26 reflections |
b = 12.981 (2) Å | θ = 11.8–12.5° |
c = 17.164 (2) Å | µ = 1.51 mm−1 |
V = 6823.6 (19) Å3 | T = 273 K |
Z = 16 | Prismatic, colourless |
F(000) = 3168 | 0.2 × 0.2 × 0.2 mm |
Siemens P4 diffractometer | Rint = 0.039 |
Radiation source: fine-focus sealed tube | θmax = 25.0°, θmin = 2.1° |
Graphite monochromator | h = −36→36 |
2θ/ω scans | k = −15→11 |
7294 measured reflections | l = −19→12 |
2329 independent reflections | 3 standard reflections every 97 reflections |
2099 reflections with I > 2σ(I) | intensity decay: 4% |
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)] = 0.024 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.087 | w = 1/[σ2(Fo2) + (0.1P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.74 | (Δ/σ)max < 0.001 |
2329 reflections | Δρmax = 0.26 e Å−3 |
193 parameters | Δρmin = −0.37 e Å−3 |
1 restraint | Absolute structure: Flack (1983), with how many Friedel pairs? |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.04 (4) |
[Sn(CH3)3(C13H13NO3)] | V = 6823.6 (19) Å3 |
Mr = 394.03 | Z = 16 |
Orthorhombic, Fdd2 | Mo Kα radiation |
a = 30.626 (5) Å | µ = 1.51 mm−1 |
b = 12.981 (2) Å | T = 273 K |
c = 17.164 (2) Å | 0.2 × 0.2 × 0.2 mm |
Siemens P4 diffractometer | Rint = 0.039 |
7294 measured reflections | 3 standard reflections every 97 reflections |
2329 independent reflections | intensity decay: 4% |
2099 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.024 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.087 | Δρmax = 0.26 e Å−3 |
S = 0.74 | Δρmin = −0.37 e Å−3 |
2329 reflections | Absolute structure: Flack (1983), with how many Friedel pairs? |
193 parameters | Absolute structure parameter: −0.04 (4) |
1 restraint |
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. |
x | y | z | Uiso*/Ueq | ||
Sn | 0.411524 (8) | −0.002008 (19) | 0.26150 (5) | 0.05087 (14) | |
C1 | 0.43775 (19) | 0.1345 (4) | 0.2137 (4) | 0.0718 (15) | |
H1A | 0.4312 | 0.1915 | 0.2474 | 0.108* | |
H1B | 0.4251 | 0.1466 | 0.1634 | 0.108* | |
H1C | 0.4688 | 0.1276 | 0.2087 | 0.108* | |
C2 | 0.4509 (2) | −0.0989 (5) | 0.3309 (4) | 0.0772 (16) | |
H2A | 0.4442 | −0.0880 | 0.3848 | 0.116* | |
H2B | 0.4811 | −0.0832 | 0.3218 | 0.116* | |
H2C | 0.4454 | −0.1695 | 0.3175 | 0.116* | |
C3 | 0.3535 (2) | −0.0753 (5) | 0.2245 (4) | 0.089 (2) | |
H3A | 0.3308 | −0.0634 | 0.2622 | 0.134* | |
H3B | 0.3585 | −0.1480 | 0.2196 | 0.134* | |
H3C | 0.3447 | −0.0477 | 0.1751 | 0.134* | |
O1 | 0.38557 (11) | 0.0726 (2) | 0.3650 (2) | 0.0602 (8) | |
O2 | 0.33660 (11) | 0.1547 (2) | 0.2914 (2) | 0.0616 (9) | |
O3 | 0.44514 (15) | −0.0706 (3) | 0.1396 (2) | 0.0771 (11) | |
C4 | 0.35365 (15) | 0.1367 (3) | 0.3546 (3) | 0.0513 (10) | |
C5 | 0.33861 (13) | 0.1881 (3) | 0.4283 (3) | 0.0444 (10) | |
C6 | 0.35136 (15) | 0.1499 (3) | 0.5001 (3) | 0.0558 (11) | |
H6A | 0.3703 | 0.0939 | 0.5021 | 0.067* | |
C7 | 0.33636 (18) | 0.1936 (5) | 0.5696 (3) | 0.0673 (15) | |
H7A | 0.3450 | 0.1670 | 0.6176 | 0.081* | |
C8 | 0.3084 (2) | 0.2772 (5) | 0.5656 (3) | 0.0643 (15) | |
H8A | 0.2977 | 0.3059 | 0.6115 | 0.077* | |
C9 | 0.29629 (16) | 0.3184 (4) | 0.4959 (3) | 0.0561 (11) | |
H9A | 0.2778 | 0.3753 | 0.4950 | 0.067* | |
C10 | 0.31093 (15) | 0.2770 (4) | 0.4268 (3) | 0.0474 (10) | |
N | 0.29828 (13) | 0.3157 (3) | 0.3544 (3) | 0.0510 (9) | |
H1N | 0.3021 (18) | 0.279 (5) | 0.310 (3) | 0.061* | |
C11 | 0.45673 (14) | −0.3331 (3) | 0.0821 (3) | 0.0449 (10) | |
C12 | 0.47411 (17) | −0.3229 (4) | 0.0014 (3) | 0.0594 (12) | |
H12A | 0.4622 | −0.3776 | −0.0306 | 0.071* | |
H12B | 0.5056 | −0.3310 | 0.0026 | 0.071* | |
C13 | 0.4631 (2) | −0.2201 (4) | −0.0352 (3) | 0.0703 (15) | |
H13A | 0.4799 | −0.2115 | −0.0827 | 0.084* | |
H13B | 0.4323 | −0.2187 | −0.0488 | 0.084* | |
C14 | 0.47305 (19) | −0.1322 (4) | 0.0200 (4) | 0.0665 (14) | |
H14A | 0.4616 | −0.0688 | −0.0018 | 0.080* | |
H14B | 0.5045 | −0.1247 | 0.0245 | 0.080* | |
C15 | 0.45398 (15) | −0.1476 (3) | 0.1002 (3) | 0.0528 (11) | |
C16 | 0.44788 (16) | −0.2510 (3) | 0.1278 (3) | 0.0490 (11) | |
H16A | 0.4376 | −0.2617 | 0.1782 | 0.059* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Sn | 0.05684 (19) | 0.03705 (18) | 0.0587 (2) | 0.00106 (12) | −0.00554 (19) | 0.00251 (11) |
C1 | 0.098 (4) | 0.039 (2) | 0.079 (4) | 0.003 (2) | 0.014 (3) | 0.005 (2) |
C2 | 0.094 (4) | 0.064 (3) | 0.073 (4) | 0.011 (3) | 0.001 (3) | 0.020 (3) |
C3 | 0.084 (4) | 0.072 (4) | 0.112 (6) | −0.009 (3) | −0.016 (4) | −0.026 (4) |
O1 | 0.071 (2) | 0.0529 (19) | 0.057 (2) | 0.0084 (15) | −0.0044 (17) | 0.0016 (15) |
O2 | 0.091 (3) | 0.0457 (16) | 0.049 (2) | 0.0143 (15) | −0.0092 (17) | −0.0075 (14) |
O3 | 0.117 (3) | 0.0449 (18) | 0.069 (2) | 0.0005 (19) | 0.007 (2) | −0.0108 (19) |
C4 | 0.068 (3) | 0.042 (2) | 0.044 (3) | −0.012 (2) | 0.001 (2) | 0.001 (2) |
C5 | 0.051 (3) | 0.038 (2) | 0.045 (2) | −0.0123 (16) | −0.0020 (18) | −0.005 (2) |
C6 | 0.059 (2) | 0.049 (2) | 0.059 (3) | −0.0073 (18) | −0.010 (2) | 0.011 (2) |
C7 | 0.087 (4) | 0.072 (4) | 0.042 (3) | −0.023 (3) | −0.006 (2) | 0.016 (3) |
C8 | 0.083 (4) | 0.063 (3) | 0.047 (3) | −0.020 (3) | 0.019 (3) | −0.006 (3) |
C9 | 0.066 (3) | 0.048 (2) | 0.054 (3) | −0.009 (2) | 0.002 (2) | −0.009 (2) |
C10 | 0.049 (2) | 0.043 (2) | 0.049 (3) | −0.0119 (18) | 0.004 (2) | −0.005 (2) |
N | 0.067 (2) | 0.0390 (19) | 0.047 (2) | −0.0001 (16) | −0.0032 (18) | −0.0048 (17) |
C11 | 0.047 (2) | 0.038 (2) | 0.049 (3) | −0.0034 (17) | 0.0002 (18) | −0.0043 (19) |
C12 | 0.077 (3) | 0.049 (2) | 0.053 (3) | 0.000 (2) | 0.016 (3) | 0.003 (3) |
C13 | 0.102 (4) | 0.049 (3) | 0.061 (4) | −0.003 (3) | 0.007 (3) | 0.006 (3) |
C14 | 0.089 (4) | 0.047 (2) | 0.064 (4) | −0.008 (2) | 0.009 (3) | 0.002 (3) |
C15 | 0.059 (3) | 0.038 (2) | 0.061 (3) | −0.0014 (18) | 0.004 (2) | −0.008 (2) |
C16 | 0.054 (3) | 0.043 (2) | 0.050 (3) | 0.0021 (16) | 0.004 (2) | −0.0017 (17) |
Sn—C1 | 2.112 (5) | C7—H7A | 0.9300 |
Sn—C2 | 2.111 (6) | C8—C9 | 1.362 (8) |
Sn—C3 | 2.113 (6) | C8—H8A | 0.9300 |
Sn—O1 | 2.174 (4) | C9—C10 | 1.377 (7) |
Sn—O3 | 2.496 (4) | C9—H9A | 0.9300 |
C1—H1A | 0.9600 | C10—N | 1.396 (7) |
C1—H1B | 0.9600 | N—C11i | 1.376 (6) |
C1—H1C | 0.9600 | N—H1N | 0.91 (6) |
C2—H2A | 0.9600 | C11—C16 | 1.351 (6) |
C2—H2B | 0.9600 | C11—Nii | 1.376 (6) |
C2—H2C | 0.9600 | C11—C12 | 1.489 (7) |
C3—H3A | 0.9600 | C12—C13 | 1.513 (8) |
C3—H3B | 0.9600 | C12—H12A | 0.9700 |
C3—H3C | 0.9600 | C12—H12B | 0.9700 |
O1—C4 | 1.296 (5) | C13—C14 | 1.515 (8) |
O2—C4 | 1.227 (6) | C13—H13A | 0.9700 |
O3—C15 | 1.237 (6) | C13—H13B | 0.9700 |
C4—C5 | 1.503 (7) | C14—C15 | 1.508 (8) |
C5—C6 | 1.384 (7) | C14—H14A | 0.9700 |
C5—C10 | 1.432 (7) | C14—H14B | 0.9700 |
C6—C7 | 1.400 (8) | C15—C16 | 1.436 (6) |
C6—H6A | 0.9300 | C16—H16A | 0.9300 |
C7—C8 | 1.384 (9) | ||
C1—Sn—C2 | 120.1 (3) | C6—C7—H7A | 120.7 |
C1—Sn—C3 | 125.5 (3) | C9—C8—C7 | 121.3 (5) |
C2—Sn—C3 | 112.5 (3) | C9—C8—H8A | 119.3 |
C1—Sn—O1 | 94.73 (19) | C7—C8—H8A | 119.3 |
C2—Sn—O1 | 90.8 (2) | C8—C9—C10 | 121.0 (5) |
C3—Sn—O1 | 97.9 (2) | C8—C9—H9A | 119.5 |
C1—Sn—O3 | 79.46 (19) | C10—C9—H9A | 119.5 |
C2—Sn—O3 | 91.4 (2) | C9—C10—N | 122.4 (5) |
C3—Sn—O3 | 86.3 (2) | C9—C10—C5 | 119.5 (5) |
O1—Sn—O3 | 174.13 (13) | N—C10—C5 | 118.1 (4) |
Sn—C1—H1A | 109.5 | C11i—N—C10 | 128.5 (4) |
Sn—C1—H1B | 109.5 | C11i—N—H1N | 106 (4) |
H1A—C1—H1B | 109.5 | C10—N—H1N | 122 (4) |
Sn—C1—H1C | 109.5 | C16—C11—Nii | 124.6 (4) |
H1A—C1—H1C | 109.5 | C16—C11—C12 | 122.8 (4) |
H1B—C1—H1C | 109.5 | Nii—C11—C12 | 112.6 (4) |
Sn—C2—H2A | 109.5 | C11—C12—C13 | 112.7 (4) |
Sn—C2—H2B | 109.5 | C11—C12—H12A | 109.1 |
H2A—C2—H2B | 109.5 | C13—C12—H12A | 109.1 |
Sn—C2—H2C | 109.5 | C11—C12—H12B | 109.1 |
H2A—C2—H2C | 109.5 | C13—C12—H12B | 109.1 |
H2B—C2—H2C | 109.5 | H12A—C12—H12B | 107.8 |
Sn—C3—H3A | 109.5 | C14—C13—C12 | 111.0 (5) |
Sn—C3—H3B | 109.5 | C14—C13—H13A | 109.4 |
H3A—C3—H3B | 109.5 | C12—C13—H13A | 109.4 |
Sn—C3—H3C | 109.5 | C14—C13—H13B | 109.4 |
H3A—C3—H3C | 109.5 | C12—C13—H13B | 109.4 |
H3B—C3—H3C | 109.5 | H13A—C13—H13B | 108.0 |
C4—O1—Sn | 116.7 (3) | C13—C14—C15 | 113.1 (4) |
C15—O3—Sn | 146.8 (4) | C13—C14—H14A | 109.0 |
O2—C4—O1 | 124.4 (4) | C15—C14—H14A | 109.0 |
O2—C4—C5 | 122.0 (4) | C13—C14—H14B | 109.0 |
O1—C4—C5 | 113.6 (4) | C15—C14—H14B | 109.0 |
C6—C5—C10 | 118.1 (4) | H14A—C14—H14B | 107.8 |
C6—C5—C4 | 120.2 (4) | O3—C15—C16 | 123.1 (5) |
C10—C5—C4 | 121.6 (4) | O3—C15—C14 | 118.5 (4) |
C5—C6—C7 | 121.4 (4) | C16—C15—C14 | 118.4 (4) |
C5—C6—H6A | 119.3 | C11—C16—C15 | 121.3 (4) |
C7—C6—H6A | 119.3 | C11—C16—H16A | 119.4 |
C8—C7—C6 | 118.6 (5) | C15—C16—H16A | 119.4 |
C8—C7—H7A | 120.7 |
Symmetry codes: (i) −x+3/4, y+3/4, z+1/4; (ii) −x+3/4, y−3/4, z−1/4. |
D—H···A | D—H | H···A | D···A | D—H···A |
N—H1N···O2 | 0.91 (6) | 1.96 (6) | 2.631 (5) | 129 (5) |
Experimental details
Crystal data | |
Chemical formula | [Sn(CH3)3(C13H13NO3)] |
Mr | 394.03 |
Crystal system, space group | Orthorhombic, Fdd2 |
Temperature (K) | 273 |
a, b, c (Å) | 30.626 (5), 12.981 (2), 17.164 (2) |
V (Å3) | 6823.6 (19) |
Z | 16 |
Radiation type | Mo Kα |
µ (mm−1) | 1.51 |
Crystal size (mm) | 0.2 × 0.2 × 0.2 |
Data collection | |
Diffractometer | Siemens P4 |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7294, 2329, 2099 |
Rint | 0.039 |
(sin θ/λ)max (Å−1) | 0.594 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.024, 0.087, 0.74 |
No. of reflections | 2329 |
No. of parameters | 193 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.26, −0.37 |
Absolute structure | Flack (1983), with how many Friedel pairs? |
Absolute structure parameter | −0.04 (4) |
Computer programs: XSCANS (Siemens, 1991), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL/PC (Sheldrick, 1990).
Sn—C1 | 2.112 (5) | Sn—O3 | 2.496 (4) |
Sn—C2 | 2.111 (6) | C10—N | 1.396 (7) |
Sn—C3 | 2.113 (6) | N—C11i | 1.376 (6) |
Sn—O1 | 2.174 (4) | ||
C1—Sn—C2 | 120.1 (3) | C1—Sn—O3 | 79.46 (19) |
C1—Sn—C3 | 125.5 (3) | C2—Sn—O3 | 91.4 (2) |
C2—Sn—C3 | 112.5 (3) | C3—Sn—O3 | 86.3 (2) |
C1—Sn—O1 | 94.73 (19) | O1—Sn—O3 | 174.13 (13) |
C2—Sn—O1 | 90.8 (2) | C11i—N—C10 | 128.5 (4) |
C3—Sn—O1 | 97.9 (2) |
Symmetry code: (i) −x+3/4, y+3/4, z+1/4. |
D—H···A | D—H | H···A | D···A | D—H···A |
N—H1N···O2 | 0.91 (6) | 1.96 (6) | 2.631 (5) | 129 (5) |
The reaction of 2-(3-oxocyclohex-1-enyl)benzoic acid (Vieira et al., 2007) with Sn(CH3)3Cl in the presence of triethylamine yielded the title complex. The X-ray crystallographic study revealed that it crystallizes forming an infinity double-polymeric chain structure, where the anionic ligand bridges two tin centre via the monodentate carboxylic moiety and the C?O fragment, Fig. 1. The structure possess one tin atom surrounded by three methyl groups and two oxygen atoms, describing an almost perfect trigonal bypiramid. The equatorial corners are occupied by the methyl groups and the axial positions by the oxygen atoms. The angles C1—Sn—C2 and O1—Sn—O3 are all near 120° and 180° as expected for a trigonal bypiramid.