catena-Poly[[tribenzyl­tin(IV)]-μ-(E)-3-phenyl­prop-2-enoato-κ2 O:O′]

Kong Mun Lo; Seik Weng Ng

doi:10.1107/S1600536811017247

. 2011 May 14;67(Pt 6):m744–m745. doi: 10.1107/S1600536811017247

catena-Poly[[tribenzyltin(IV)]-μ-(E)-3-phenylprop-2-enoato-κ² O:O′]

Kong Mun Lo ^a, Seik Weng Ng ^a,^*

PMCID: PMC3120586 PMID: 21754636

Abstract

The Sn^IV atom in the title carboxylate-bridged polymer, [Sn(C₇H₇)₃(C₉H₇O₂)]_n, exists in a trans-C₃SnO₂ trigonal–bipyramidal geometry (average covalent Sn—O = 2.167 Å, average dative Sn—O = 2.361 Å and average O—Sn—O = 169.6°). The polymer propagates as a helical chain along the b axis with a repeat distance that is half the b-axial length. There are four independent formula units in the asymmetric unit; two are disposed about a false center of inversion with respect to the other two so that the space group emulates a centric space group.

Related literature

Trialkyltin(IV) carboxylates generally contain five-coordinate Sn atoms and are carboxylate-bridged polymers; see: Ng et al. (1988 ▶). For the structure of tribenzyltin acetate, see: Ferguson et al. (1995 ▶). For the structure of tribenzyltin p-nitrocinnamate, see: Thong et al. (2008 ▶). For the use of the Hooft and Flack parameters in confirming the P2₁ space-group description, see: Hooft et al. (2008 ▶); Spek (2009 ▶). The polar P2₁ space group is sometimes assigned incorrectly, see: Clemente & Marzotto (2003 ▶, 2004 ▶).

Experimental

Crystal data

[Sn(C₇H₇)₃(C₉H₇O₂)]
M _r = 539.21
Monoclinic,
a = 19.5847 (3) Å
b = 10.2404 (2) Å
c = 26.6224 (4) Å
β = 110.2838 (8)°
V = 5008.15 (15) Å³
Z = 8
Mo Kα radiation
μ = 1.04 mm⁻¹
T = 100 K
0.20 × 0.10 × 0.10 mm

Data collection

Bruker SMART APEX diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.818, T _max = 0.903
47886 measured reflections
22492 independent reflections
19107 reflections with I > 2σ(I)
R _int = 0.049

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.087
S = 0.97
22492 reflections
1189 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.83 e Å⁻³
Δρ_min = −0.79 e Å⁻³
Absolute structure: Flack (1983 ▶), 10328 Friedel pairs
Flack parameter: 0.00 (2)

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: X-SEED (Barbour, 2001 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811017247/si2355sup1.cif

e-67-0m744-sup1.cif^{(61.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811017247/si2355Isup2.hkl

e-67-0m744-Isup2.hkl^{(1.1MB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected geometric parameters (Å, °).

Sn1—O1	2.165 (3)
Sn1—O2ⁱ	2.352 (4)
Sn2—O3	2.177 (3)
Sn2—O4ⁱⁱ	2.338 (3)
Sn3—O5	2.153 (3)
Sn3—O6ⁱⁱⁱ	2.403 (4)
Sn4—O7	2.174 (3)
Sn4—O8^iv	2.352 (4)

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O1—Sn1—O2ⁱ	171.2 (1)
O3—Sn2—O4ⁱⁱ	169.6 (1)
O5—Sn3—O6ⁱⁱⁱ	168.4 (1)
O7—Sn4—O8^iv	169.4 (1)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) .

Acknowledgments

We thank the University of Malaya (grant No. RG020/09AFR) for supporting this study.

supplementary crystallographic information

Comment

Trialkyltin carboxylates generally adopt five-coordinate, carboxylate-bridged structures (Ng et al., 1988), as exemplified by tribenzyltin acetate, which is polymeric with a short covalent and a long dative Sn–O bond [2.131 (2), 2.559 (2) Å] (Ferguson et al., 1995). Other trialkyltin carboxylates have less uneven bonds; however, the repeat distance of such polymers is generally about 5.19 Å. This is approximately the value found in the tribenzyltin cinnamate (Scheme I). In tribenzyltin cinnamate, the Sn^IV atom of the four independent carboxylate-bridged polymeric [Sn(C₇H₇)₃(C₉H₇O₂)]_n, chains exists in a trans-C₃SnO₂ trigonal bipyramidal geometry [covalent Sn–O_av. 2.167 Å, dative Sn–O_av. 2.361 Å; O–Sn–O_av. 169.6 °].. Each chain propagates as a helical chain along the b-axis of the monoclinic unit cell (Figs. 1 - 4). The repeat distance is half the b-axial length, i.e., 5.12 Å. Two formula units are disposed about a false center-of-inversion with respect to the other two so that the space group emulates a centric space group.

Tribenzyltin cinnamate as well as tribenzyltin p-nitrocinnamate (Thong et al., 2008) both display similar covalent and dative tin-oxygen bonds, and their repeat distances are nearly identical.

The title compoud was refined in the polar P2₁ space group; PLATON (Spek, 2009) suggested the centric P2₁/a space group with a 100% probability; the checking program examines the atomic coordinates. In fact, the h0l reflections that define an a-glide, though weak, are not systematically absent. The solution in the centric space group did not converge to a satisfactory R-index although the measurements are of high quality. Finally, the Flack parameter refined to 0.00 (2), an indication of the polar nature of the P2₁ space group. There are examples of incorrectly assigned space groups for which the Flack parameter also refined to zero but the present diffraction dataset has a large number of Friedel pairs that attest to the correctness of Flack parameter. As an additional check, the absolute structure parameter y (Hooft et al., 2008) was calculated using PLATON (Spek, 2009). The resulting value of y is 0.00 (1), which indicates that the absolute structure has probably been determined correctly.

The assignment of P2₁ space groups is sometimes problematic. In this case, the h0l reflections are merely weak whereas in other cases, the h0l reflections are indeed systematically absent. Clemente & Marzotto (2003, 2004) have presented examples of compounds refined in the P2₁ space group that should be described in higher-symmetry space groups.

Experimental

Tribenzyltin hydroxide was first prepared by the base hydrolysis of tribenzyltin chloride with 10% sodium hydroxide solution. The hydroxide (0.40 g, 1 mmol) and cinnamic acid (0.15 g, 1 mmol) were heated in ethanol (100 ml) until the reactants dissolved completely. The solution was then filtered and colorless crystals were obtained upon slow evaporation of the solvent.