Bis{2-[(E)-(5-tert-butyl-2-hy­droxy­phen­yl)diazen­yl]benzoato}dimethyl­tin(IV)

Tushar S Basu Baul; Anup Paul; Edward R T Tiekink

doi:10.1107/S1600536811036543

. 2011 Sep 14;67(Pt 10):m1383–m1384. doi: 10.1107/S1600536811036543

Bis{2-[(E)-(5-tert-butyl-2-hydroxyphenyl)diazenyl]benzoato}dimethyltin(IV)

Tushar S Basu Baul ^a,^‡, Anup Paul ^a, Edward R T Tiekink ^b,^*

PMCID: PMC3201396 PMID: 22065466

Abstract

In the title diorganotin dicarboxylate, [Sn(CH₃)₂(C₁₇H₁₇N₂O₃)₂], the tin(IV) atom is six-coordinated by four O atoms derived from asymmetrically coordinating carboxylate ligands, and two methyl-C atoms. The resulting C₂O₄ donor set defines a skew-trapezoidal bipyramid with the Sn—C bonds disposed over the weaker Sn—O bonds. Within each carboxylate ligand, the hydroxyl-H atom forms bifurcated O—H⋯(O,N) hydrogen bonds with carboxylate-O and azo-N atoms. The dihedral angles between the benzene rings in the two ligands are 10.44 (11) and 34.24 (11)°. In the crystal, centrosymmetric dimers are formed through pairs of Sn⋯O interactions [2.8802 (16) Å], and the dimers are linked into supramolecular layers in the ac plane by C—H⋯π interactions.

Related literature

For background to the potential anti-cancer activity of related compounds, see: Basu Baul et al. (2011 ▶). For the synthesis of the ligand, see: Basu Baul et al. (2008 ▶). For related structural studies, see: Basu Baul et al. (2010 ▶). For a review of the structural chemistry of organotin carboxylates, see: Tiekink (1991 ▶).

Experimental

Crystal data

[Sn(CH₃)₂(C₁₇H₁₇N₂O₃)₂]
M _r = 743.43
Monoclinic,
a = 9.6298 (1) Å
b = 31.8788 (4) Å
c = 11.0963 (1) Å
β = 93.502 (1)°
V = 3400.05 (6) Å³
Z = 4
Mo Kα radiation
μ = 0.80 mm⁻¹
T = 100 K
0.36 × 0.13 × 0.03 mm

Data collection

Bruker SMART APEXII diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.895, T _max = 1
26762 measured reflections
7749 independent reflections
6165 reflections with I > 2σ(I)
R _int = 0.031

Refinement

R[F ² > 2σ(F ²)] = 0.033
wR(F ²) = 0.071
S = 1.04
7749 reflections
434 parameters
H-atom parameters constrained
Δρ_max = 0.55 e Å⁻³
Δρ_min = −0.41 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS86 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) general, I. DOI: 10.1107/S1600536811036543/hb6399sup1.cif

e-67-m1383-sup1.cif^{(31.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811036543/hb6399Isup2.hkl

e-67-m1383-Isup2.hkl^{(371.5KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Sn—O1	2.1118 (16)
Sn—O2	2.6967 (16)
Sn—O4	2.1120 (16)
Sn—O5	2.4482 (16)
Sn—C35	2.081 (3)
Sn—C36	2.098 (2)

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Table 2. Hydrogen-bond geometry (Å, °).

Cg1 is the centroid of the C25–C30 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3⋯O1	0.84	2.49	3.142 (2)	136
O3—H3⋯N1	0.84	1.87	2.573 (2)	140
O6—H6⋯O5	0.84	2.20	2.877 (3)	137
O6—H6⋯N3	0.84	1.93	2.620 (3)	139
C10—H10⋯Cg1ⁱ	0.95	2.97	3.863 (2)	157

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Symmetry code: (i) Inline graphic .

Acknowledgments

The financial support of the Department of Science and Technology, New Delhi, India (grant No. SR/S1/IC-03/2005,TSBB), the Council of Scientific and Industrial Research, New Delhi, India [grant No. 09/347/(0197)/2011/EMR I, for the award of a Senior Research Fellowship to AP] and the University Grants Commission, New Delhi, India, through SAP–DSA, Phase-III, are gratefully acknowledged.

supplementary crystallographic information

Comment

Organotin carboxylates related to the title compound, (I), have been investigated for potential anti-cancer activity (Basu Baul et al., 2011). Complementing biological studies are structural investigations (Basu Baul et al., 2010). In (I), the Sn atom is bound by two asymmetrically coordinating carboxylate ligands and two methyl groups, Fig. 1 and Table 1. The coordination geometry is based on a skew-trapezoidal bipyramid with the methyl groups disposed to lie over the weaker Sn—O bonds; the C35—Sn—C36 angle is 149.63 (10) °. The overall molecular conformation matches those normally observed for structures of the general formula R₂Sn(O₂CR')₂ (Tiekink, 1991).

Centrosymmetrically related molecules associate into dimeric aggregates via weak Sn···O2ⁱ contacts of 2.8802 (16) Å, Fig. 1, symmetry operation i: -x, 1 - y, -z. A consequence of this association is the significant lengthening of the Sn—O2 bond with respect to the chemically equivalent Sn—O5 bond, Table 1. The relative dispositions of the carboxylate residues are different in order to reduce steric hindrance. Thus, while the hydroxy group of the O1-carboxylate ligand is orientated towards the more strongly coordinating O1 atom, the hydroxy group of the O4-carboxylate ligand is orientated towards the weakly coordinating O5 atom, Fig. 1. Within each carboxylate ligand, intramolecular O—H···O,N hydrogen bonds are noted, Table 2. Despite these, the ligands exhibit significant deviations from planarity. The values of the O1—C1—C2—C3 and O4—C18—C19—C20 torsion angles of 15.2 (3) and 158.7 (2) °, respectively, indicate that the carboxylate groups lie out of the plane of the respective benzene ring to which it is attached. Significant twisting is found in the O1-carboxylate ligand with the dihedral angle formed between the two benzene rings being 34.24 (11) °. This arises in part to avoid a steric clash with a benzene ring of the adjacent carboxylate ligand. The O4-carboxylate ligand, being directed away from the rest of the molecule, is less twisted with the dihedral angle formed between the two benzene rings being 10.44 (11) °.

Over and above the intermolecular Sn···O interactions mentioned above, the most prominent feature of the crystal packing is the formation of C—H···π interactions, Table 2. These serve to link dimeric aggregates into supramolecular arrays in the ac plane. A view of the unit-cell contents is shown in Fig. 2 which highlights the stacking of layers along the b axis.

Experimental

The title compound was prepared by reacting 2-[(E)-(5-tert-butyl-2-hydroxyphenyl)diazenyl]benzoic acid (Basu Baul et al., 2008) (0.30 g, 1.00 mmol) and Me₂SnO (0.08 g, 0.49 mmol) in anhydrous toluene (50 ml) using a Dean and Stark apparatus for 6 h. The red solution was filtered while hot, concentrated to one tenth of its initial volume and precipitated with hexane. The red precipitate was separated by filtration, washed with hexane (2 x 5 ml) and dried in vacuo. The dried residue was dissolved in chloroform-hexane (10:1 v/v) and filtered. The filtrate was allowed to evaporate at room temperature, which afforded red prisms. Yield: 0.15 g, 40%, M.pt. 439–441 K. Elemental analysis, found: C 58.44, H 5.61, N 7.37%. C₃₆H₄₀N₄O₆Sn requires: C 58.14, H, 5.43, N 7.54%. IR (KBr, cm^-1): 1589 ν(OCO)_asym. ¹H-NMR (CDCl₃, 400.44 MHz): δ H: 12.8 [br, 1H, OH], 8.22 [d, 8 Hz, 1H, H7], 7.92 [d, 8 Hz, 1H, H4], 7.78 [d, 2.5 Hz, 1H, H13], 7.60 [t, 8 Hz, 1H, H5], 7.50 [t, 8 Hz, 1H, H6], 7.37 [dd, 2.5, 8 Hz, 1H, H11], 6.96 [d, 8 Hz, 1H, H10], 1.32 [s, 9H, CH₃], 1.19 [s, 3H, Sn—CH₃] p.p.m. ¹¹⁹Sn-NMR (CDCl₃, 149.33): δ -112.7 p.p.m.