5-Amino-2,4,6-triiodo­isophthalic acid monohydrate

Abstract

The title compound, C₈H₄I₃NO₄·H₂O, shows an extensive hydrogen-bond network; in the crystal structure, mol­ecules are linked by O—H⋯O, N—H⋯O and O—H⋯N hydrogen bonds involving all possible donors and also the water mol­ecule.

Related literature

For the synthetic procedure, see Larsen et al. (1956 ▶). For related crystal structure determinations: 1,3,5-triiodo­benzene, see: Margraf & Bats (2006 ▶); sodium diatrizoate, see: Tonnessen et al. (1996 ▶). For the 1,3,5-triiodo­benzene core as the basis of contrast agents, see: Yu & Watson (1999 ▶).

Experimental

Crystal data

• C₈H₄I₃NO₄·H₂O

• M _r = 576.84

• Orthorhombic,

• a = 9.214 (1) Å

• b = 15.735 (2) Å

• c = 18.816 (2) Å

• V = 2728.0 (5) ų

• Z = 8

• Cu Kα radiation

• μ = 54.11 mm⁻¹

• T = 100 (2) K

• 0.08 × 0.05 × 0.03 mm

Data collection

• Bruker SMART 6000 diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.106, T _max = 0.345 (expected range = 0.061–0.197)

• 49139 measured reflections

• 2716 independent reflections

• 2545 reflections with I > 2σ(I)

• R _int = 0.043

Refinement

• R[F ² > 2σ(F ²)] = 0.026

• wR(F ²) = 0.061

• S = 1.03

• 2716 reflections

• 173 parameters

• 14 restraints

• Only H-atom coordinates refined

• Δρ_max = 0.71 e Å⁻³

• Δρ_min = −1.71 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; 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: SHELXL97 and SHELXTL.

Supplementary Material

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
O11—H11⋯O14	0.79 (5)	1.75 (5)	2.540 (5)	173 (7)
O8—H8⋯O12i	0.80 (5)	1.90 (5)	2.662 (5)	161 (7)
O14—H14A⋯O9ii	0.81 (4)	1.95 (4)	2.751 (5)	170 (6)
O14—H14B⋯N13iii	0.81 (4)	2.05 (4)	2.841 (5)	166 (6)
N13—H13A⋯O14iv	0.88 (4)	2.30 (5)	3.067 (6)	147 (5)
N13—H13B⋯O12iv	0.88 (4)	2.68 (5)	3.478 (5)	152 (5)

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

supplementary crystallographic information

Comment

Iodine-based compounds have always been in the focus of contrast agents for X-ray imaging. The 1,3,5-triiodobenzene core has been the basis of many contrast agents (Yu & Watson 1999). The ionic monomer diatrizoate was one of the first compounds used (Tonnessen et al. 1996).

The title compound, 5-Amino-2,4,6-triiodoisophthalic acid (hereafter I3C), crystallizes as a monohydrate, due to water impurities in the crystallization solution. It forms hydrogen bonds with all potential donors as well as the lattice water being involved (Fig. 2, Table 1). However, the interaction between N13 and O12 is slightly weaker. In the crystal, the molecules are positioned perpendicular to each other, showing no π-π interactions of the phenyl rings (Fig. 3).

The three functional groups for hydrogen bonding, along with the three iodine atoms, render I3C a suitable agent for experimental phasing of macromolecules (Beck et al., unpublished results). The iodine atoms give rise to a large anomalous signal, even at in-house sources. Additionally, they form an equilateral triangle (I—I 6.0 Å) which is easy to recognize in the heavy atom substructure when this compound is used as a heavy atom derivative for macromolecular phasing.

Experimental

The title compound was prepared according to the reported procedure (Larsen et al. 1956). It was recrystallized from a methanol-acetonitrile solution by slowly evaporating the solvents to obtain crystals suitable for X-ray single-crystal diffraction.

Refinement

Hydrogen atoms were located via the difference Fourier map and their geometrical positions were refined with restraints. The U values were set to 1.5 U_eq of their parent atom. Bond lengths for hydrogen atoms were restrained to be equal (SADI in SHELXL-97). Phenyl ring and carboxylate groups were restrained to planarity.

Figures

Fig. 1.

A view of I3C. Displacement ellipsoids are drawn at the 50% probability level. The hydrogen bond within the asymmetric unit is shown as a dashed line.

Fig. 2.

Hydrogen bonding of I3C. Symmetry equivalents are depicted in orange.

Fig. 3.

Packing of I3C, viewed along b. Hydrogen atoms are omitted for clarity. In alternating layers molecules are positioned perpendicular to each other. Hydrogen bonds are shown as dashed lines.

Fig. 4.

Synthetic scheme of I3C.

Crystal data

C8H4I3NO4·H2O	F000 = 2080
Mr = 576.84	Dx = 2.809 Mg m−3
Orthorhombic, Pbca	Cu Kα radiation λ = 1.54178 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 9945 reflections
a = 9.214 (1) Å	θ = 4.7–60.8º
b = 15.735 (2) Å	µ = 54.11 mm−1
c = 18.816 (2) Å	T = 100 (2) K
V = 2728.0 (5) Å3	Block, yellow
Z = 8	0.08 × 0.05 × 0.03 mm

Data collection

Bruker SMART 6000 diffractometer	2716 independent reflections
Radiation source: rotating anode	2545 reflections with I > 2σ(I)
Monochromator: INCOATEC multilayer optics	Rint = 0.043
Detector resolution: 5.602 pixels mm-1	θmax = 74.3º
T = 100(2) K	θmin = 4.7º
ω scans	h = −10→10
Absorption correction: multi-scan(SADABS; Sheldrick, 1996)	k = −17→19
Tmin = 0.106, Tmax = 0.345	l = −23→23
49139 measured reflections

Refinement

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.026	Only H-atom coordinates refined
wR(F2) = 0.061	w = 1/[σ2(Fo2) + (0.0277P)2 + 17.3624P] where P = (Fo2 + 2Fc2)/3
S = 1.03	(Δ/σ)max = 0.002
2716 reflections	Δρmax = 0.72 e Å−3
173 parameters	Δρmin = −1.71 e Å−3
14 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.000058 (8)

Special details

Experimental. Intensities were measured with a Bruker SMART 6000 area-detector

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 > 2 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. Hydrogen atoms were located via the difference Fourier map and their geometrical positions were refined with restraints. The U values were set to 1.5 Ueq of their parent atom.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I1	1.18424 (3)	0.630616 (18)	0.012748 (16)	0.02419 (10)
I2	0.71499 (3)	0.674286 (18)	0.234093 (15)	0.02375 (10)
I3	1.04238 (3)	0.979824 (17)	0.124476 (17)	0.02693 (10)
C1	1.0827 (5)	0.7970 (3)	0.0781 (2)	0.0161 (8)
C2	1.0606 (5)	0.7094 (3)	0.0789 (2)	0.0161 (9)
C3	0.9544 (5)	0.6745 (3)	0.1231 (2)	0.0153 (9)
C4	0.8655 (5)	0.7276 (3)	0.1631 (2)	0.0163 (9)
C5	0.8803 (5)	0.8172 (3)	0.1604 (2)	0.0165 (9)
C6	0.9945 (5)	0.8492 (3)	0.1199 (2)	0.0180 (9)
C7	1.1981 (5)	0.8362 (3)	0.0320 (3)	0.0202 (10)
O8	1.1458 (4)	0.8648 (2)	−0.02803 (18)	0.0256 (7)
H8	1.205 (6)	0.883 (4)	−0.055 (3)	0.038*
O9	1.3242 (4)	0.8414 (2)	0.05017 (19)	0.0290 (8)
C10	0.9364 (5)	0.5794 (3)	0.1285 (2)	0.0173 (9)
O11	1.0376 (4)	0.5445 (2)	0.16663 (17)	0.0224 (7)
H11	1.031 (7)	0.494 (3)	0.170 (3)	0.034*
O12	0.8358 (4)	0.54161 (19)	0.10032 (17)	0.0213 (7)
N13	0.7889 (5)	0.8702 (2)	0.1997 (2)	0.0210 (8)
H13A	0.698 (5)	0.855 (4)	0.204 (3)	0.031*
H13B	0.785 (6)	0.922 (3)	0.183 (3)	0.031*
O14	1.0395 (4)	0.3834 (2)	0.17540 (18)	0.0235 (7)
H14A	1.074 (7)	0.366 (4)	0.139 (3)	0.035*
H14B	1.099 (6)	0.376 (4)	0.206 (3)	0.035*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
I1	0.02850 (18)	0.02100 (16)	0.02307 (16)	0.00785 (12)	0.00724 (12)	0.00027 (11)
I2	0.02603 (18)	0.02156 (16)	0.02364 (16)	−0.00544 (11)	0.00910 (12)	−0.00016 (11)
I3	0.02852 (19)	0.01260 (15)	0.03966 (19)	−0.00146 (11)	0.00662 (13)	0.00096 (11)
C1	0.018 (2)	0.0143 (19)	0.0162 (19)	0.0012 (17)	0.0007 (17)	0.0000 (16)
C2	0.019 (2)	0.014 (2)	0.0150 (19)	0.0033 (17)	−0.0002 (17)	−0.0002 (16)
C3	0.020 (2)	0.013 (2)	0.0135 (19)	0.0006 (17)	−0.0052 (17)	0.0019 (15)
C4	0.018 (2)	0.016 (2)	0.0150 (19)	−0.0072 (16)	0.0005 (17)	0.0017 (16)
C5	0.018 (2)	0.015 (2)	0.016 (2)	0.0003 (17)	−0.0023 (17)	−0.0006 (16)
C6	0.023 (2)	0.013 (2)	0.017 (2)	−0.0022 (18)	−0.0013 (18)	0.0009 (16)
C7	0.023 (3)	0.014 (2)	0.023 (2)	−0.0007 (17)	0.0010 (19)	−0.0016 (17)
O8	0.0251 (19)	0.0276 (18)	0.0241 (17)	−0.0019 (14)	0.0036 (15)	0.0093 (14)
O9	0.0216 (19)	0.038 (2)	0.0276 (18)	−0.0045 (15)	0.0035 (15)	0.0013 (15)
C10	0.023 (2)	0.014 (2)	0.015 (2)	−0.0007 (18)	0.0048 (18)	0.0001 (16)
O11	0.0274 (18)	0.0132 (15)	0.0265 (17)	−0.0007 (13)	−0.0074 (14)	0.0043 (13)
O12	0.0279 (18)	0.0121 (14)	0.0239 (16)	−0.0039 (13)	−0.0064 (14)	0.0014 (12)
N13	0.021 (2)	0.0148 (18)	0.027 (2)	0.0019 (15)	0.0035 (17)	−0.0026 (15)
O14	0.0255 (19)	0.0217 (16)	0.0233 (17)	0.0028 (14)	−0.0003 (14)	0.0027 (14)

Geometric parameters (Å, °)

I1—C2	2.094 (4)	C5—N13	1.396 (6)
I2—C4	2.100 (4)	C7—O9	1.214 (6)
I3—C6	2.103 (4)	C7—O8	1.308 (6)
C1—C2	1.394 (6)	O8—H8	0.80 (5)
C1—C6	1.398 (6)	C10—O12	1.223 (6)
C1—C7	1.504 (6)	C10—O11	1.299 (6)
C2—C3	1.396 (6)	O11—H11	0.79 (5)
C3—C4	1.391 (6)	N13—H13A	0.88 (4)
C3—C10	1.509 (6)	N13—H13B	0.88 (4)
C4—C5	1.418 (6)	O14—H14A	0.81 (4)
C5—C6	1.393 (6)	O14—H14B	0.81 (4)
C2—C1—C6	119.4 (4)	C5—C6—C1	122.3 (4)
C2—C1—C7	121.0 (4)	C5—C6—I3	119.3 (3)
C6—C1—C7	119.6 (4)	C1—C6—I3	118.4 (3)
C1—C2—C3	119.8 (4)	O9—C7—O8	125.0 (4)
C1—C2—I1	120.0 (3)	O9—C7—C1	122.7 (4)
C3—C2—I1	120.2 (3)	O8—C7—C1	112.3 (4)
C4—C3—C2	120.0 (4)	C7—O8—H8	115 (5)
C4—C3—C10	119.6 (4)	O12—C10—O11	125.3 (4)
C2—C3—C10	120.4 (4)	O12—C10—C3	122.5 (4)
C3—C4—C5	121.3 (4)	O11—C10—C3	112.3 (4)
C3—C4—I2	119.6 (3)	C10—O11—H11	114 (5)
C5—C4—I2	119.0 (3)	C5—N13—H13A	117 (4)
C6—C5—N13	122.0 (4)	C5—N13—H13B	113 (4)
C6—C5—C4	116.9 (4)	H13A—N13—H13B	105 (6)
N13—C5—C4	121.0 (4)	H14A—O14—H14B	108 (6)
C6—C1—C2—C3	−2.2 (6)	N13—C5—C6—C1	−177.4 (4)
C7—C1—C2—C3	179.0 (4)	C4—C5—C6—C1	6.0 (6)
C6—C1—C2—I1	176.7 (3)	N13—C5—C6—I3	5.2 (5)
C7—C1—C2—I1	−2.0 (5)	C4—C5—C6—I3	−171.4 (3)
C1—C2—C3—C4	3.5 (6)	C2—C1—C6—C5	−2.8 (6)
I1—C2—C3—C4	−175.4 (3)	C7—C1—C6—C5	176.0 (4)
C1—C2—C3—C10	−175.6 (4)	C2—C1—C6—I3	174.7 (3)
I1—C2—C3—C10	5.5 (5)	C7—C1—C6—I3	−6.5 (5)
C2—C3—C4—C5	−0.1 (6)	C2—C1—C7—O9	−84.0 (6)
C10—C3—C4—C5	179.1 (4)	C6—C1—C7—O9	97.2 (5)
C2—C3—C4—I2	−176.2 (3)	C2—C1—C7—O8	97.3 (5)
C10—C3—C4—I2	3.0 (5)	C6—C1—C7—O8	−81.5 (5)
C3—C4—C5—C6	−4.6 (6)	C4—C3—C10—O12	75.4 (5)
I2—C4—C5—C6	171.5 (3)	C2—C3—C10—O12	−105.5 (5)
C3—C4—C5—N13	178.8 (4)	C4—C3—C10—O11	−103.6 (4)
I2—C4—C5—N13	−5.1 (5)	C2—C3—C10—O11	75.5 (5)

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
O11—H11···O14	0.79 (5)	1.75 (5)	2.540 (5)	173 (7)
O8—H8···O12i	0.80 (5)	1.90 (5)	2.662 (5)	161 (7)
O14—H14A···O9ii	0.81 (4)	1.95 (4)	2.751 (5)	170 (6)
O14—H14B···N13iii	0.81 (4)	2.05 (4)	2.841 (5)	166 (6)
N13—H13A···O14iv	0.88 (4)	2.30 (5)	3.067 (6)	147 (5)
N13—H13B···O12iv	0.88 (4)	2.68 (5)	3.478 (5)	152 (5)

Symmetry codes: (i) x+1/2, −y+3/2, −z; (ii) −x+5/2, y−1/2, z; (iii) −x+2, y−1/2, −z+1/2; (iv) −x+3/2, y+1/2, z.