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The title compound, [Sn4(CH3)4(C3H7)4Cl4O2] or {Cl[(CH3)2CH]2SnOSn(CH3)2Cl}2, obtained by the reaction of [(CH3)2CH]2SnO and (CH3)2SnCl2, exists as centrosymmetric dimers in the solid state. It contains a central planar four-membered Sn2O2 ring. The coordinate geometry about the Sn atoms is distorted trigonal pyramidal.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101015645/vj1147sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270101015645/vj1147Isup2.hkl
Contains datablock I

CCDC reference: 179254

Comment top

1,3-Disubstituted-1,1,3,3-tetraorganodistannoxanes are useful catalysts for many reactions (Otera, 1993). A characteristic feature of symmetric tetraorganodistannoxanes is their dimerization that results in a ladder-type arrangement that contains a central planar four-membered Sn2O2 ring. Compared with symmetric tetraorganodistannoxanes, the structures of asymmetric tetraorganodistannoxanes have not been fully investigated. From the reported data of asymmetric tetraorganodistannoxanes with mixed R groups, it can be seen that larger groups promote linkage with exocyclic Sn atoms because of their hindering effect (Dakternieks et al., 1997; Lu et al., 2000). But the title compound, 1,3-disubstituted-1,1,3,3-tetraorganodistannoxane, (I), is an exception.

The title compound exists as ladder-type dimers that are analogous to the traditional structure of symmetric distannoxanes. But the larger bulky isopropyl (iPr) groups unusually link to exo-Sn atoms, while the smaller Me groups connect to endo-Sn atoms. In the asymmetric unit, both Me2SnCl and Sn(iPr)2 groups are connected by a Cl and an O atom to form the Me2Sn(Cl)(µ2-Cl)(µ-O)Sn(iPr)2 fragment. The bridging oxo atom functions as a triple-bond bridge and the internal angles [105.55 (14) and 74.45 (14)°] of the central Sn2O2 are compared with those in other distannoxane systems, such as 104.6 (2)° in [Cl(tBu)2SnOSnMe2Cl]2, 104.8 (2)° in [Cl(tBu)2SnOSnPh2Cl]2 (Dakternieks et al., 1997) and 105.69 (17)° in [Cl(tBu)2SnOSnPh2Cl]2 (Lu et al., 2000). The three µ3-O—Sn bond distances are very similar [Sn2—O1 2.053 (3) Å, Sn1—O1 2.015 (3) Å and Sn2i—O1 2.143 (3) Å; symmetry code: (i) -x, 2 - y, 2 - z] reflecting the strong bridging oxo coordination with Sn atoms in the dimer. All four Sn atoms, the four Cl atoms and two O atoms comprise a fused ring system that is coplanar with a mean deviation of ±0.0054 (6) Å.

The geometry about all the Sn atoms can be described as distorted trigonal bipyramids. With regard to Sn1, one µ-O and two methyl C atoms are in equatorial positions. The axial Cl—Sn—Cl angle of 163.48 (5) Å deviates from the ideal value of 180°. This deviation may be due to the interaction of the Cl atoms with the endocyclic Sn atoms. For Sn2, the axial O—Sn—Cl angle is 150.80 (9)°. Both kinds of Sn atoms are pentacoordinated. Atom Cl2 has a close intermolecular contact with Sn2, which may be viewed as a weak bonding interaction: the Sn2···Cl2 distance is 3.3613 (19) Å, compared to the van Der Waals radii sum of 4.0 Å. It is different from the case in asymmetric tetraorganodistannoxanes [Cl(tBu)2SnOSnR2Cl]2 (R = Me, Bu), in which both Cl atoms interact with the endocyclic Sn atom to make the endo-Sn atom six-coordinate, while the exo-Sn atom is still five-coordinate [the endo-Sn—Cl and exo-Sn—Cl bond lengths are 2.802 (2) and 2.675 (2) Å for R = Me, and 2.907 (2) and 2.598 (2) Å, respectively, for R = nBu]. The reason for this may be attributable to the fact that the Sn2 atom is connected to the larger exo-butyl groups while the endo-Sn atom is connected to the smaller groups in the dimer.

Related literature top

For related literature, see: Dakternieks et al. (1997); Lu et al. (2000).

Experimental top

The synthesis of the title compound was carried out by reaction of equimolar amounts of [(CH3)2CH]2SnO and (CH3)2SnCl2 by refluxing an acetone solution for 1 h until the solution became clear. Recrystallization from acetone yielded colourless crystals of (I) suitable for X-ray analysis (yield 67%). Analysis calculated for C16H40Cl4O2Sn4: C 21.81, H 4.58%; found: C 21.73, H 4.62%; FT—IR data (KBr pellet, cm-1): 2965 (s), 2859 (m), 1382 (m), 1355 (s), 1197 (m), 1153 (s), 797 (s), 607 (s), 546 (s).

Refinement top

All H atoms were located geometrically (C—H = 0.96 Å) and and their parameters were not refined.

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SHELXTL (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures top
[Figure 1] Fig. 1. A view of (I) showing the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
1,3-Dichloro-1,1-dimethyl-3,3-diisopropyl distannoxane top
Crystal data top
[Sn4Cl4O2(CH3)4(C3H7)4]F(000) = 840
Mr = 881.04Dx = 1.989 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 10.268 (4) ÅCell parameters from 52 reflections
b = 9.529 (3) Åθ = 2.8–25.3°
c = 15.315 (5) ŵ = 3.73 mm1
β = 101.023 (6)°T = 293 K
V = 1470.8 (9) Å3Rhombic, colorless
Z = 20.20 × 0.10 × 0.10 mm
Data collection top
CCD area-detector
diffractometer
2591 independent reflections
Radiation source: fine-focus sealed tube1825 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.038
ϕ and ω scansθmax = 25.0°, θmin = 2.2°
Absorption correction: multi-scan
SADABS
h = 1211
Tmin = 0.646, Tmax = 0.689k = 911
5966 measured reflectionsl = 1812
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)] = 0.029Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.068H-atom parameters constrained
S = 0.92 w = 1/[σ2(Fo2) + (0.0306P)2]
where P = (Fo2 + 2Fc2)/3
2591 reflections(Δ/σ)max = 0.002
118 parametersΔρmax = 0.43 e Å3
0 restraintsΔρmin = 0.51 e Å3
Crystal data top
[Sn4Cl4O2(CH3)4(C3H7)4]V = 1470.8 (9) Å3
Mr = 881.04Z = 2
Monoclinic, P21/nMo Kα radiation
a = 10.268 (4) ŵ = 3.73 mm1
b = 9.529 (3) ÅT = 293 K
c = 15.315 (5) Å0.20 × 0.10 × 0.10 mm
β = 101.023 (6)°
Data collection top
CCD area-detector
diffractometer
2591 independent reflections
Absorption correction: multi-scan
SADABS
1825 reflections with I > 2σ(I)
Tmin = 0.646, Tmax = 0.689Rint = 0.038
5966 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0290 restraints
wR(F2) = 0.068H-atom parameters constrained
S = 0.92Δρmax = 0.43 e Å3
2591 reflectionsΔρmin = 0.51 e Å3
118 parameters
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
Sn10.30550 (4)1.11003 (4)1.06854 (2)0.03852 (13)
Sn20.05868 (4)0.90184 (4)0.92581 (2)0.03557 (13)
Cl10.32541 (15)0.92297 (15)0.93441 (10)0.0491 (4)
Cl20.21888 (17)1.26380 (17)1.17445 (10)0.0616 (5)
O10.1173 (3)1.0456 (3)1.0254 (2)0.0344 (8)
C10.3665 (6)1.2743 (6)0.9938 (4)0.0570 (17)
H1A0.36941.36041.02660.086*
H1B0.30481.28350.93840.086*
H1C0.45321.25390.98220.086*
C20.4107 (6)0.9748 (6)1.1652 (3)0.0545 (17)
H2A0.41901.01731.22280.082*
H2B0.49740.95791.15260.082*
H2C0.36380.88751.16430.082*
C30.0848 (6)0.6897 (5)0.9725 (4)0.0461 (15)
H3A0.00230.65590.98050.055*
C40.1288 (8)0.5953 (6)0.9031 (4)0.077 (2)
H4A0.13860.50080.92510.116*
H4B0.21220.62800.89130.116*
H4C0.06340.59770.84920.116*
C50.1784 (7)0.6763 (7)1.0621 (4)0.0669 (19)
H5A0.18520.57951.07980.100*
H5B0.14450.73011.10590.100*
H5C0.26460.71091.05730.100*
C60.0199 (6)1.0060 (6)0.7984 (3)0.0506 (16)
H6A0.07611.02090.78230.061*
C70.0597 (9)0.9139 (7)0.7263 (4)0.086 (3)
H7A0.04020.96210.67030.129*
H7B0.01080.82750.72210.129*
H7C0.15300.89430.74120.129*
C80.0859 (7)1.1500 (6)0.8018 (4)0.071 (2)
H8A0.06551.19280.74400.107*
H8B0.18031.13950.81940.107*
H8C0.05341.20830.84400.107*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Sn10.0304 (2)0.0445 (2)0.0394 (2)0.00084 (19)0.00359 (17)0.00525 (19)
Sn20.0370 (3)0.0384 (2)0.0324 (2)0.00557 (19)0.00948 (17)0.00255 (18)
Cl10.0339 (9)0.0598 (9)0.0573 (9)0.0052 (7)0.0182 (7)0.0029 (8)
Cl20.0561 (11)0.0731 (11)0.0550 (10)0.0023 (9)0.0090 (8)0.0266 (8)
O10.025 (2)0.043 (2)0.035 (2)0.0033 (17)0.0044 (16)0.0073 (17)
C10.054 (5)0.051 (4)0.070 (4)0.002 (3)0.020 (3)0.018 (3)
C20.044 (4)0.066 (4)0.050 (4)0.007 (3)0.002 (3)0.020 (3)
C30.046 (4)0.036 (3)0.058 (4)0.001 (3)0.014 (3)0.000 (3)
C40.090 (6)0.050 (4)0.087 (5)0.020 (4)0.005 (5)0.008 (4)
C50.073 (5)0.059 (4)0.063 (4)0.008 (4)0.000 (4)0.016 (4)
C60.046 (4)0.063 (4)0.040 (3)0.002 (3)0.000 (3)0.009 (3)
C70.130 (8)0.093 (6)0.036 (4)0.002 (5)0.022 (4)0.012 (4)
C80.088 (6)0.062 (4)0.062 (4)0.003 (4)0.008 (4)0.020 (4)
Geometric parameters (Å, º) top
Sn1—O12.015 (3)C3—C41.525 (7)
Sn1—C22.099 (5)C3—H3A0.9800
Sn1—C12.104 (5)C4—H4A0.9600
Sn1—Cl22.474 (2)C4—H4B0.9600
Sn1—Cl12.757 (2)C4—H4C0.9600
Sn2—O12.053 (3)C5—H5A0.9600
Sn2—O1i2.143 (3)C5—H5B0.9600
Sn2—C32.144 (5)C5—H5C0.9600
Sn2—C62.157 (5)C6—C71.526 (8)
Sn2—Cl12.724 (2)C6—C81.527 (8)
O1—Sn2i2.143 (3)C6—H6A0.9800
C1—H1A0.9600C7—H7A0.9600
C1—H1B0.9600C7—H7B0.9600
C1—H1C0.9600C7—H7C0.9600
C2—H2A0.9600C8—H8A0.9600
C2—H2B0.9600C8—H8B0.9600
C2—H2C0.9600C8—H8C0.9600
C3—C51.524 (7)
O1—Sn1—C2112.1 (2)C5—C3—C4111.0 (5)
O1—Sn1—C1114.5 (2)C5—C3—Sn2113.4 (4)
C2—Sn1—C1132.3 (2)C4—C3—Sn2111.0 (4)
O1—Sn1—Cl287.31 (10)C5—C3—H3A107.0
C2—Sn1—Cl295.87 (17)C4—C3—H3A107.0
C1—Sn1—Cl295.63 (17)Sn2—C3—H3A107.0
O1—Sn1—Cl176.21 (10)C3—C4—H4A109.5
C2—Sn1—Cl191.56 (17)C3—C4—H4B109.5
C1—Sn1—Cl190.18 (17)H4A—C4—H4B109.5
Cl2—Sn1—Cl1163.48 (5)C3—C4—H4C109.5
O1—Sn2—O1i74.45 (14)H4A—C4—H4C109.5
O1—Sn2—C3112.44 (18)H4B—C4—H4C109.5
O1i—Sn2—C399.45 (18)C3—C5—H5A109.5
O1—Sn2—C6109.99 (18)C3—C5—H5B109.5
O1i—Sn2—C6100.73 (19)H5A—C5—H5B109.5
C3—Sn2—C6136.5 (2)C3—C5—H5C109.5
O1—Sn2—Cl176.43 (10)H5A—C5—H5C109.5
O1i—Sn2—Cl1150.81 (9)H5B—C5—H5C109.5
C3—Sn2—Cl189.60 (17)C7—C6—C8111.3 (6)
C6—Sn2—Cl191.12 (17)C7—C6—Sn2111.2 (4)
Sn2—Cl1—Sn182.34 (4)C8—C6—Sn2112.3 (4)
Sn1—O1—Sn2125.01 (17)C7—C6—H6A107.3
Sn1—O1—Sn2i129.36 (16)C8—C6—H6A107.3
Sn2—O1—Sn2i105.55 (14)Sn2—C6—H6A107.3
Sn1—C1—H1A109.5C6—C7—H7A109.5
Sn1—C1—H1B109.5C6—C7—H7B109.5
H1A—C1—H1B109.5H7A—C7—H7B109.5
Sn1—C1—H1C109.5C6—C7—H7C109.5
H1A—C1—H1C109.5H7A—C7—H7C109.5
H1B—C1—H1C109.5H7B—C7—H7C109.5
Sn1—C2—H2A109.5C6—C8—H8A109.5
Sn1—C2—H2B109.5C6—C8—H8B109.5
H2A—C2—H2B109.5H8A—C8—H8B109.5
Sn1—C2—H2C109.5C6—C8—H8C109.5
H2A—C2—H2C109.5H8A—C8—H8C109.5
H2B—C2—H2C109.5H8B—C8—H8C109.5
Symmetry code: (i) x, y+2, z+2.

Experimental details

Crystal data
Chemical formula[Sn4Cl4O2(CH3)4(C3H7)4]
Mr881.04
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)10.268 (4), 9.529 (3), 15.315 (5)
β (°) 101.023 (6)
V3)1470.8 (9)
Z2
Radiation typeMo Kα
µ (mm1)3.73
Crystal size (mm)0.20 × 0.10 × 0.10
Data collection
DiffractometerCCD area-detector
diffractometer
Absorption correctionMulti-scan
SADABS
Tmin, Tmax0.646, 0.689
No. of measured, independent and
observed [I > 2σ(I)] reflections
5966, 2591, 1825
Rint0.038
(sin θ/λ)max1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.029, 0.068, 0.92
No. of reflections2591
No. of parameters118
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.43, 0.51

Computer programs: SMART (Bruker, 1998), SMART, SHELXTL (Bruker, 1997), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL.

Selected geometric parameters (Å, º) top
Sn1—O12.015 (3)Sn2—O12.053 (3)
Sn1—Cl22.474 (2)Sn2—O1i2.143 (3)
Sn1—Cl12.757 (2)Sn2—Cl12.724 (2)
O1—Sn1—Cl287.31 (10)O1—Sn2—Cl176.43 (10)
C2—Sn1—Cl295.87 (17)O1i—Sn2—Cl1150.81 (9)
C1—Sn1—Cl295.63 (17)Sn2—Cl1—Sn182.34 (4)
O1—Sn1—Cl176.21 (10)Sn1—O1—Sn2125.01 (17)
Cl2—Sn1—Cl1163.48 (5)Sn1—O1—Sn2i129.36 (16)
O1—Sn2—O1i74.45 (14)Sn2—O1—Sn2i105.55 (14)
Symmetry code: (i) x, y+2, z+2.
 

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