Dimethyl 5-amino-2,4,6-triiodo­isophthalate

Pei Zou; Shi-Neng Luo; Min-Hao Xie; Ya-Ling Liu; Jun Wu

doi:10.1107/S1600536810001005

. 2010 Jan 16;66(Pt 2):o360. doi: 10.1107/S1600536810001005

Dimethyl 5-amino-2,4,6-triiodoisophthalate

Pei Zou ^a,^*, Shi-Neng Luo ^a, Min-Hao Xie ^a, Ya-Ling Liu ^a, Jun Wu ^a

PMCID: PMC2979769 PMID: 21579785

Abstract

The title compound, C₁₀H₈I₃NO₄, crystallizes with two molecules in the asymmetric unit. The I atoms and the benzene ring plane in the two molecules are approximately coplanar, the I atoms deviating by −0.1631 (1), 0.0704 (1) and −0.0507 (1) Å from the mean plane of the benzene ring in one molecule and by 0.1500 (1), −0.0034 (1) and −0.1213 (1) Å in the other. The planes of the ester groups are almost orthogonal to those of the benzene rings in both molecules, forming dihedral angles of 83.5 (3), 76.4 (3), 97.3 (1) and 75.7 (1)°. The mean planes of the benzene rings in two molecules are inclined at 69.8 (3)° with respect to each other. In the crystal, intermolecular I⋯O interactions link the molecules into infinite chains. In addition, N—H⋯O and non-classical C—H⋯O hydrogen bonds are observed.

Related literature

For general background to 1,3,5-triiodobenzene derivatives, see: Morin et al. (1987 ▶); Singh & Rathore (1980 ▶); Stacul et al. (2001 ▶); Yu & Watson (1999 ▶). For a related structure, see: Beck & Sheldrick (2008 ▶).

Experimental

Crystal data

C₁₀H₈I₃NO₄
M _r = 586.87
Triclinic,
a = 8.4423 (17) Å
b = 10.3545 (19) Å
c = 18.365 (3) Å
α = 75.158 (5)°
β = 80.045 (5)°
γ = 89.728 (6)°
V = 1527.2 (5) Å³
Z = 4
Mo Kα radiation
μ = 6.15 mm⁻¹
T = 93 K
0.40 × 0.33 × 0.13 mm

Data collection

Rigaku SPIDER diffractometer
Absorption correction: empirical (using intensity measurements) (North et al., 1968 ▶) T _min = 0.193, T _max = 0.495
10344 measured reflections
5251 independent reflections
4488 reflections with I > 2σ(I)
R _int = 0.036

Refinement

R[F ² > 2σ(F ²)] = 0.035
wR(F ²) = 0.067
S = 0.98
5251 reflections
325 parameters
24 restraints
H-atom parameters constrained
Δρ_max = 1.10 e Å⁻³
Δρ_min = −1.19 e Å⁻³

Data collection: RAPID-AUTO (Rigaku, 2004 ▶); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810001005/pv2251sup1.cif

e-66-0o360-sup1.cif^{(22.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810001005/pv2251Isup2.hkl

e-66-0o360-Isup2.hkl^{(257.1KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1A—H1A⋯I2A	0.88	2.74	3.224 (5)	116
N1A—H1A⋯O4Bⁱ	0.88	2.48	3.036 (7)	122
N1A—H1B⋯I3A	0.88	2.72	3.211 (5)	117
N1B—H1C⋯I2B	0.88	2.73	3.212 (5)	116
N1B—H1D⋯I3B	0.88	2.73	3.222 (5)	116
N1B—H1D⋯O2Aⁱⁱ	0.88	2.43	3.026 (7)	125
C8B—H8E⋯O2Bⁱⁱⁱ	0.98	2.54	3.516 (9)	171
C10A—H10A⋯O2B^iv	0.98	2.58	3.499 (9)	155
C10A—H10B⋯O4A^v	0.98	2.54	3.519 (9)	173

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

Acknowledgments

The authors acknowledge financial support from the Jiangsu Institute of Nuclear Medicine.

supplementary crystallographic information

Comment

The 1,3,5-triiodobenzene core has been the basis of many contrast agents (Yu & Watson, 1999). The title compound is useful as an important intermediate for the preparation of iodinated X-ray contrast agent, such as iotalamic acid, ioxitalamic acid, and ioxilan, which are used clinically all over the world (Morin et al., 1987; Singh et al., 1980; Stacul et al., 2001). In this paper, we present the crystal structure of the title compound.

The asymmetric unit of the title compound (Fig. 1) contains two crystallographically independent molecules (A and B) in an asymmetric unit. The three I atoms deviate from the mean-planes of the phenyl rings, respectively, by -0.1631 (1), 0.0704 (1) and -0.0507 (1) Å for molecule A and 0.1500 (1), -0.0034 (1) and -0.1213 (1) Å for molecule B. Bond lengths and angles are comparable to those observed in a related structure (Beck & Sheldrick, 2008). The planes of the ester groups in both molecule are almost orthogonal to the benzene ring, as indicated by the dihedral angles of 83.5 (3)° (C10A/O3A/C9A/O4A; C1A—C6A), 76.4 (3)°(C8A/O1A/C7A/O2A; C1A—C6A), 97.3 (1)° (C10B/O3B/C9B/O4B; C1B—C6B) and 75.7 (1)° (C8B/O1B/C7B/O2B; C1B—C6B). The dihedral angle between the rings (C1A—C6A) and (C1B—C6B) is 69.8 (3)°.

In the crystal structure, intermolecular I···O interactions link the molecules into infinite one-dimensional chains (Fig. 2). In addition, C—H···O hydrogen bonds and N—H···O hydrogen bonds are observed.

Experimental

A mixture of 5-amino-2,4,6-triiodoisophthaloyl dichloride (2.97 g, 5 mmol) and methanol (15 ml) was heated under reflux for four hours to produce dimethyl 5-amino-2,4,6-triiodoisophthalate. It was recrystallized from a methanol solution by slowly evaporating the solvents to obtain crystals suitable for X-ray single-crystal diffraction.