supplementary materials


aa2086 scheme

Acta Cryst. (2013). E69, m254    [ doi:10.1107/S1600536813009185 ]

Diacetatodi-tert-butyltin(IV)

M. Reichelt and H. Reuter

Abstract top

The title compound, [Sn(C4H9)2(CH3COO)2], was synthesized in order to study the influence of large organic groups on the molecular structure of diorganotin diacetates. The title compound exhibits the same structure type as other diorganotin(IV) diacetates characterized by an unsymmetrical bidentate bonding mode of the two acetate groups to tin. The influence of the t-butyl groups on this molecular structure is expressed in two significant differences: tin-carbon bond lengths are much more longer than in the other diacetates, as are the additional interactions of the acetate groups with the tin atom. Intermolecular interactions are restricted to C-H...O ones similar to those in the other diacetates, giving rise to a chain-like arrangement of the molecules with the tin atoms and acetate groups in the propagation plane.

Comment top

Diorganotin(IV) dicarboxylates, R2Sn(O2CR')2, belong to the class of diorganotin compounds, R2SnX2, with univalent anions X, such as the halides (X = F, Cl, Br, I) or alkoxides (X = OR'). In contrast to these anions, that behave as unidentate substitutents, the carboxylate groups, O2CR', can act via its two oxygen atoms as a bidentate ligand in a more or less symmetrical or unsymmetrical coordination mode giving rise to additional intra- or intermolecular interactions (Tiekink, 1991). In the case of diacetates, R' = Me, this was formerly shown for R = phenyl (Alcock et al. 1992) and R = methyl (Lockhart et al. 1987, α-modification; Mistry et al. 1995, β-modification) both revealing in solid state the same molecular structure type with a strongly unsymmetrical bonding mode of the acetate groups. On this background it was interesting to see whether the larger t-butyl groups are compatible with that structure type or not.

The asymmetric unit of the title compound (Fig. 1) consists of one formula unit with all atoms in general positions although the molecule displays a pseudo twofold rotation axis [midway C11/C21 - Sn - midway O11/O21]. In a first approximation, the tin atom is fourfold coordinated by the two t-butyl groups and an oxygen atom of each acetate group. Both Sn—C bond lengths are almost equal as are both Sn—O bond lengths, too (see Table 1). The last ones are comparable with Sn—O bond lengths in the other diacetates [d(Sn—O) = 2.076 (4), 2.079 (4), R = Ph; 2 x 2.106 (2), R = α-Me, 2.098 (2), 2.094 (2), R = β-Me]. In comparison to the methyl compounds with Sn—C bond lengths of 2 x 2.098 (3) Å [α], respectively 2.096 (3), 2.088 (3) Å [β] and the phenyl compound [2.119 (5), 2.110 (6) Å] Sn—C bonds of the tert-butyl groups are considerable longer. From the bond angles of 138.97 (7)° between the t-butyl groups and 79.93 (6)° between the two oxygen atoms, the coordination polyhedron is compressed to a tetragonal disphenoid (Fig. 2). Obviously, this distortion is typical for diacetates [C—Sn—C = 131.4°, R = Ph; 135.9 (2)°(1)°, R = α-Me; 133.8 (2)°, R = β-Me; O—Sn—O = 82.0 (3)°, R = Ph; 79.5 (1)°, R = α-Me; 80.1 (1)°, R = β-Me].

The coordination sphere of the tin atom is completed by the other two oxygen atoms of the acetate groups that undergo a much more weaker interaction with the tin atom [d(Sn···O) = 2.689 (1) Å to O22, 2.647 (2) Å to O12], resulting in a very unsymmetrical bidentate coordination mode of the acetate groups (Fig. 2). This is also reflected in two different C—O distances for each acetate group (Table 1). Again, within the molecular structures of the other diacetates a similar coordination behaviour is observed but Sn···O interactions are considerably stronger [2.583 (4), 2.527 (5) Å, R = Ph; 2 x 2.539 (2) Å, R = α-Me; 2.563 (2), 2.595 (2) Å, R = β-Me].

Both t-butyl groups are well ordered with a mean value for the C—C bonds of 1.527 (3) Å [range: 1.522 (3) - 1.530 (3) Å] and a mean C—C—C bond angle of 110.2 (4)° [range: 109.65 (3)° - 110.65 (3)°]. With respect to Sn—C—C bond angles, both t-butyl groups show similar effects: two angles are around the ideal tetrahedral value of 109.5°, whereas the third one is significantly smaller [107.09 (3)° for C12; 106.07 (2)° for C22].

In the solid, molecules are arranged in chains with the tin atoms and acetate groups defining the propagation plane (Fig. 3). This arrangement is also characteristic for both modifications of the methyl compounds but not for the phenyl one. In the present case, the intermolecular O···Sn distances of 4.692 (1) Å [O21···Sn11] and 4.694 (1) Å [O11···Sn11], however, are so long that seems impossible that these interactions are responsible for the supra-molecular architecture. There are, however, O···HC interactions between the acetate groups and t-butyl groups of neighbouring molecules (Fig. 4) that are much more attractive (Table 2). Similar interactions are found in all other diorganotin(IV) diacetates and even in the phenyl compound.

Related literature top

For background to diorganotin(IV) carboxylates, see: Tiekink (1991) and to diorganotin(IV) diacetates, see: Alcock et al. (1992); Lockhart et al. (1987); Mistry et al. (1995).

Experimental top

Synthesis:

0.51 g (0.68 mmol) di-t-butyltin oxide are dissolved in 0.25 g (4.16 mmol) of acetic acid (Fluka). The solution is stirred for 6 h at ambient temperature before the solvent is allowed to evaporate slowly. After about 1 week colourless block-like crystals are grown.

Spectroscopic studies:

Elemental analysis calcd (%) for C5H4O3: C, 41.06; H, 6.89. Found: C, 40.99; H, 6.53. 1H-NMR (CDCl3, p.p.m.): 2.09 (s,OAc, 3H), 1.35 (s, tBu, 9H, 3J(1H-119/117Sn = 119.1/114.1 Hz). {1H}-13C-NMR (CDCl3, p.p.m.): 180.59 (O2CCH3), 45.29 (Cα-tBu, 1J(13C-119/117Sn) = 515.3/492.4 Hz), 29.67 (Cβ-tBu), 20.37 (O2CCH3). IR (ATR, cm-1): 2853.6, 1601.0, 1438.3, 1367.9, 1323.9, 1160.4, 1053.5, 1018.2, 942.5, 807.9, 688.4, 620.1, 499.2.

Crystallographic studies:

A suitable single-crystal was selected under a polarization microscope and mounted on a 50 µm MicroMesh MiTeGen MicromountTM using FROMBLIN Y perfluoropolyether (LVAC 16/6, Aldrich).

Refinement top

Hydrogen atoms were clearly identified in difference Fourier syntheses. Their positions were idealized and refined at calculated positions riding on the carbon atoms with C—H = 0.98 Å.

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2006) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Molecular structure of the title compound, with 50% probability level displacement ellipsoids for non-H atoms.
[Figure 2] Fig. 2. Polyhedron model of the coordination sphere of the tin atom; t-butyl groups have been omitted for clarity, weak Sn··· O interactions are indicated by dashed sticks. Displacement ellipsoids for non-H atoms are shown with 50% probability level
[Figure 3] Fig. 3. Perspective view of the crystal structure parallel to the crystallographic a axis, showing the chain-like arrangement of acetate groups and tin atoms.
[Figure 4] Fig. 4. Intermolecular oxygen hydrogen interactions within the chain-like arrangement of the diacetate molecules [Symmetry operator: (1) 1 + x, y, z].
Diacetatodi-tert-butyltin(IV) top
Crystal data top
[Sn(C4H9)2(C2H3O2)2]F(000) = 712
Mr = 351.00Dx = 1.562 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 6480 reflections
a = 6.1039 (3) Åθ = 2.6–25.7°
b = 15.3928 (7) ŵ = 1.71 mm1
c = 15.9601 (8) ÅT = 100 K
β = 95.462 (2)°Block, colourless
V = 1492.74 (12) Å30.14 × 0.06 × 0.04 mm
Z = 4
Data collection top
Bruker APEXII CCD
diffractometer
3590 independent reflections
Radiation source: fine-focus sealed tube2980 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.081
φ and ω scansθmax = 28.0°, θmin = 1.8°
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
h = 88
Tmin = 0.791, Tmax = 0.939k = 2019
76636 measured reflectionsl = 2121
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.023H-atom parameters constrained
wR(F2) = 0.046 w = 1/[σ2(Fo2) + (0.0133P)2 + 1.0511P]
where P = (Fo2 + 2Fc2)/3
S = 1.04(Δ/σ)max = 0.002
3590 reflectionsΔρmax = 0.59 e Å3
167 parametersΔρmin = 0.51 e Å3
0 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.00201 (16)
Crystal data top
[Sn(C4H9)2(C2H3O2)2]V = 1492.74 (12) Å3
Mr = 351.00Z = 4
Monoclinic, P21/nMo Kα radiation
a = 6.1039 (3) ŵ = 1.71 mm1
b = 15.3928 (7) ÅT = 100 K
c = 15.9601 (8) Å0.14 × 0.06 × 0.04 mm
β = 95.462 (2)°
Data collection top
Bruker APEXII CCD
diffractometer
3590 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2009)
2980 reflections with I > 2σ(I)
Tmin = 0.791, Tmax = 0.939Rint = 0.081
76636 measured reflectionsθmax = 28.0°
Refinement top
R[F2 > 2σ(F2)] = 0.023H-atom parameters constrained
wR(F2) = 0.046Δρmax = 0.59 e Å3
S = 1.04Δρmin = 0.51 e Å3
3590 reflectionsAbsolute structure: ?
167 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
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
Sn10.19140 (2)0.295768 (9)0.285075 (8)0.01333 (6)
C110.0432 (3)0.20445 (14)0.19231 (13)0.0162 (4)
C120.1709 (3)0.24192 (16)0.14968 (14)0.0257 (5)
H12A0.23740.20010.10850.031 (2)*
H12B0.13960.29620.12110.031 (2)*
H12C0.27300.25340.19220.031 (2)*
C130.2095 (4)0.18975 (15)0.12781 (13)0.0216 (5)
H13A0.34850.16890.15660.031 (2)*
H13B0.23500.24450.09900.031 (2)*
H13C0.15150.14640.08650.031 (2)*
C140.0036 (4)0.11881 (15)0.23553 (14)0.0259 (5)
H14A0.11280.12850.27580.031 (2)*
H14B0.13270.09660.26540.031 (2)*
H14C0.06090.07640.19320.031 (2)*
C210.0894 (3)0.38924 (14)0.37595 (12)0.0161 (4)
C220.0723 (4)0.34722 (15)0.43092 (14)0.0245 (5)
H22A0.11800.39000.47130.030 (2)*
H22B0.00110.29800.46140.030 (2)*
H22C0.20160.32670.39530.030 (2)*
C230.2995 (4)0.41692 (15)0.42919 (14)0.0243 (5)
H23A0.26260.45910.47170.030 (2)*
H23B0.40140.44350.39280.030 (2)*
H23C0.36890.36590.45720.030 (2)*
C240.0185 (4)0.46712 (15)0.33009 (14)0.0249 (5)
H24A0.15020.44810.29500.030 (2)*
H24B0.08520.49360.29440.030 (2)*
H24C0.06010.50980.37130.030 (2)*
O110.4677 (2)0.22581 (9)0.33641 (9)0.0198 (3)
O120.1995 (3)0.18113 (10)0.40892 (10)0.0251 (4)
C150.3940 (4)0.17649 (14)0.39399 (13)0.0203 (5)
C160.5546 (4)0.11407 (16)0.43777 (14)0.0265 (5)
H16A0.52820.10990.49730.037 (4)*
H16B0.70490.13470.43330.037 (4)*
H16C0.53570.05670.41140.037 (4)*
O210.4416 (2)0.36282 (9)0.23048 (9)0.0178 (3)
O220.1404 (2)0.41038 (10)0.15759 (9)0.0231 (3)
C250.3440 (4)0.40733 (13)0.16819 (13)0.0185 (5)
C260.4899 (4)0.45081 (15)0.11080 (14)0.0240 (5)
H26A0.51600.41140.06460.038 (4)*
H26B0.63060.46560.14230.038 (4)*
H26C0.41880.50390.08790.038 (4)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Sn10.01484 (8)0.01307 (8)0.01231 (8)0.00027 (6)0.00240 (5)0.00084 (6)
C110.0158 (10)0.0177 (11)0.0156 (10)0.0010 (8)0.0038 (8)0.0048 (8)
C120.0162 (11)0.0342 (14)0.0260 (12)0.0018 (10)0.0017 (9)0.0072 (10)
C130.0222 (11)0.0235 (13)0.0194 (11)0.0006 (9)0.0037 (9)0.0078 (9)
C140.0294 (13)0.0220 (12)0.0276 (12)0.0095 (10)0.0089 (10)0.0041 (10)
C210.0153 (10)0.0166 (11)0.0167 (10)0.0006 (8)0.0028 (8)0.0051 (8)
C220.0249 (12)0.0239 (13)0.0265 (12)0.0005 (10)0.0128 (10)0.0036 (10)
C230.0246 (12)0.0266 (13)0.0216 (12)0.0006 (10)0.0018 (9)0.0093 (9)
C240.0303 (13)0.0204 (12)0.0246 (12)0.0065 (10)0.0057 (10)0.0020 (9)
O110.0211 (8)0.0180 (8)0.0199 (8)0.0020 (6)0.0005 (6)0.0035 (6)
O120.0273 (9)0.0222 (9)0.0263 (9)0.0039 (7)0.0055 (7)0.0017 (7)
C150.0286 (13)0.0147 (11)0.0166 (11)0.0014 (9)0.0025 (9)0.0031 (8)
C160.0337 (13)0.0229 (12)0.0221 (12)0.0072 (10)0.0024 (10)0.0049 (10)
O210.0192 (8)0.0172 (8)0.0174 (7)0.0003 (6)0.0046 (6)0.0027 (6)
O220.0226 (9)0.0267 (9)0.0202 (8)0.0019 (7)0.0028 (6)0.0013 (6)
C250.0279 (12)0.0137 (11)0.0147 (10)0.0021 (9)0.0055 (9)0.0036 (8)
C260.0304 (13)0.0215 (13)0.0209 (12)0.0012 (10)0.0076 (10)0.0030 (9)
Geometric parameters (Å, º) top
Sn1—O212.1001 (14)C22—H22B0.9800
Sn1—O112.1002 (14)C22—H22C0.9800
Sn1—C112.175 (2)C23—H23A0.9800
Sn1—C212.176 (2)C23—H23B0.9800
C11—C141.527 (3)C23—H23C0.9800
C11—C121.528 (3)C24—H24A0.9800
C11—C131.530 (3)C24—H24B0.9800
C12—H12A0.9800C24—H24C0.9800
C12—H12B0.9800O11—C151.304 (3)
C12—H12C0.9800O12—C151.235 (3)
C13—H13A0.9800C15—C161.497 (3)
C13—H13B0.9800C16—H16A0.9800
C13—H13C0.9800C16—H16B0.9800
C14—H14A0.9800C16—H16C0.9800
C14—H14B0.9800O21—C251.304 (3)
C14—H14C0.9800O22—C251.239 (3)
C21—C241.522 (3)C25—C261.495 (3)
C21—C221.525 (3)C26—H26A0.9800
C21—C231.530 (3)C26—H26B0.9800
C22—H22A0.9800C26—H26C0.9800
O21—Sn1—O1179.93 (6)C21—C22—H22B109.5
O21—Sn1—C11107.88 (7)H22A—C22—H22B109.5
O11—Sn1—C11101.58 (7)C21—C22—H22C109.5
O21—Sn1—C21102.54 (7)H22A—C22—H22C109.5
O11—Sn1—C21110.43 (7)H22B—C22—H22C109.5
C11—Sn1—C21138.97 (7)C21—C23—H23A109.5
C14—C11—C12109.77 (18)C21—C23—H23B109.5
C14—C11—C13109.93 (18)H23A—C23—H23B109.5
C12—C11—C13110.51 (17)C21—C23—H23C109.5
C14—C11—Sn1109.51 (14)H23A—C23—H23C109.5
C12—C11—Sn1109.99 (14)H23B—C23—H23C109.5
C13—C11—Sn1107.09 (13)C21—C24—H24A109.5
C11—C12—H12A109.5C21—C24—H24B109.5
C11—C12—H12B109.5H24A—C24—H24B109.5
H12A—C12—H12B109.5C21—C24—H24C109.5
C11—C12—H12C109.5H24A—C24—H24C109.5
H12A—C12—H12C109.5H24B—C24—H24C109.5
H12B—C12—H12C109.5C15—O11—Sn1104.81 (13)
C11—C13—H13A109.5O12—C15—O11120.3 (2)
C11—C13—H13B109.5O12—C15—C16123.1 (2)
H13A—C13—H13B109.5O11—C15—C16116.6 (2)
C11—C13—H13C109.5C15—C16—H16A109.5
H13A—C13—H13C109.5C15—C16—H16B109.5
H13B—C13—H13C109.5H16A—C16—H16B109.5
C11—C14—H14A109.5C15—C16—H16C109.5
C11—C14—H14B109.5H16A—C16—H16C109.5
H14A—C14—H14B109.5H16B—C16—H16C109.5
C11—C14—H14C109.5C25—O21—Sn1106.07 (13)
H14A—C14—H14C109.5O22—C25—O21120.25 (19)
H14B—C14—H14C109.5O22—C25—C26123.21 (19)
C24—C21—C22109.65 (17)O21—C25—C26116.51 (19)
C24—C21—C23110.46 (18)C25—C26—H26A109.5
C22—C21—C23110.65 (17)C25—C26—H26B109.5
C24—C21—Sn1109.79 (13)H26A—C26—H26B109.5
C22—C21—Sn1110.17 (14)C25—C26—H26C109.5
C23—C21—Sn1106.07 (13)H26A—C26—H26C109.5
C21—C22—H22A109.5H26B—C26—H26C109.5
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C12—H12C···O21i0.982.543.362 (3)142
C22—H22C···O11i0.982.653.584 (3)160
C16—H16C···O22ii0.982.693.636 (3)163
C16—H16A···O22iii0.982.603.518 (3)155
Symmetry codes: (i) x1, y, z; (ii) x+1/2, y1/2, z+1/2; (iii) x+1/2, y+1/2, z+1/2.
Selected bond lengths (Å) top
Sn1—O212.1001 (14)O11—C151.304 (3)
Sn1—O112.1002 (14)O12—C151.235 (3)
Sn1—C112.175 (2)O21—C251.304 (3)
Sn1—C212.176 (2)O22—C251.239 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C12—H12C···O21i0.982.543.362 (3)141.5
C22—H22C···O11i0.982.653.584 (3)160.0
C16—H16C···O22ii0.982.693.636 (3)163.2
C16—H16A···O22iii0.982.603.518 (3)155.2
Symmetry codes: (i) x1, y, z; (ii) x+1/2, y1/2, z+1/2; (iii) x+1/2, y+1/2, z+1/2.
Acknowledgements top

We thank the Deutsche Forschungsgemeinschaft and the Government of Lower Saxony for their financial support in the acquisition of the diffractometer.

references
References top

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