catena-Poly[[di­pyridine­mercury(II)]-μ-5-amino-2,4,6-tri­iodo­isophthalato]

The reaction of mercury(II) chloride with 5-amino-2,4,6-triiodo­isophthalic acid in pyridine solution leads to the formation of the title compound, [Hg(C₈H₂I₃NO₄)(C₅H₅N)₂]_n. The structure contains a four-coordinate Hg²⁺ ion in a distorted tetra­hedral geometry, which lies on a crystallographic twofold axis. The Hg²⁺ ion is bonded to two N atoms from two pyridine ligands and two carboxylate O atoms from two 5-amino-2,4,6-triiodo­isophthalate anions. The two carboxyl­ate groups of individual 5-amino-2,4,6-triiodo­isophthalate anions act as a bridge to the Hg centers. This anion also resides on a twofold axis, which passes through the amino N and the trans standing I atoms. The Hg—O distance is 2.337 (6) and the Hg—N distance is 2.244 (8) Å.

Related literature

For general background, see: Ziegler et al. (1997). For related structures, see: Bebout et al. (1998); Beck & Sheldrick (2008); Matković-Čalogović et al. (2002); Weil (2001).

Experimental

Crystal data

• [Hg(C₈H₂I₃NO₄)(C₅H₅N)₂]

• M_r = 915.60

• Tetragonal, P 4₁ 2₁ 2

• a = 11.9338 (3) Å

• c = 16.0532 (10) Å

• V = 2286.23 (16) ų

• Z = 4

• Mo Kα radiation

• μ = 10.81 mm⁻¹

• T = 296 (2) K

• 0.20 × 0.15 × 0.15 mm

Data collection

• Bruker SMART APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2000) T_min = 0.16, T_max = 0.20

• 10399 measured reflections

• 2251 independent reflections

• 1661 reflections with I > 2σ(I)

• R_int = 0.045

Refinement

• R[F² > 2σ(F²)] = 0.035

• wR(F²) = 0.067

• S = 1.06

• 2251 reflections

• 134 parameters

• 57 restraints

• H-atom parameters constrained

• Δρ_max = 0.63 e Å⁻³

• Δρ_min = −0.53 e Å⁻³

• Absolute structure: Flack (1983), 897 Friedel pairs

• Flack parameter: 0.010 (9)

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); 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: SHELXTL.

Supporting information

S1. Comment

5-amino-2, 4, 6-triiodoisophthalic acid is the precursor of the synthesis of a wide range of contrast agents with different amide-bound aliphatic side chains, which modulate their physical and physiological properties (Ziegler et al., 1997). The crystal structure of this compound was reported very recently (Beck et al., 2008), however, there is no information about the structural characterization of its metal complexes. In the present study, the synthesis, crystal structures of the catena-[bis(pyridine)- 5-Amino-2,4,6-triiodoisophthalic acid-O,O -mercury(II)] complex is reported.

The molecular structure of title complex comprises of two crystallographically independent chains along the c-axis. In the chains, Hg atom shows a distorted tetrahedron environment with [2 N + 2O] coordination, where two nitrogen atoms originate from pyridines and two oxygen atoms from two 5-amino-2,4,6-triiodoisophthalic acid ligands. The two CO₂^- group of 5-Amino-2,4,6 -triiodoisophthalic acid ligand coordinated to Hg²⁺ and bridging Hg metal centers. The bond lengths of Hg—O in Table 1 indicate that the Hg (II) center is in a distorted. The bond lengths are and 2.337 (6)Å for Hg1—O2. There is a week interaction between Hg²⁺ and O1 with Hg1—O1 distance is 2.618 (6) Å The Hg—O bond lengths of this complex are close to the Hg—O bond lengths in the reported coordination polymers aqua-bromo(6-carboxypyridine-2-carboxylato –O, N, O') mercury(II) (2.425 (4)Å and 2.599 (4) Å) (Matković-Calogović et al., 2002). The bond angles O1—Hg1—O2 existing in the octahedral are 53.1 (2)°, respectively, which also demonstrate the distorted octahedron in the Hg coordination center. The bond lengths of O1—C5 and O2—C5, are 1.245 (10)Å and 1.257 (10) Å, respectively, and the bond angle of O1—C1—O2 is 125.8 (8)°. Compared with the data when the ligand has not been coordinated (Beck et al., 2008), the C—O bond lengths are lengthened and the O—C—O bond angles are slightly expanded when the carboxylate groups are coordinated to central cations. The C—I and C—N bond distances in the complex are very similar with the free ligand (Beck et al., 2008). Two pyridine ligands coordinated to every Hg center with the Hg—N bond distances 2.444 (8) Å, which are fall in the range of the Hg—N bond lengths in the reported coordination compound mercury(II) Complexes of bis[(2-pyridyl)methyl]amine (in which, the Hg—N (pyridyl) bond lengths are range from 2.352 (4)Å to 2.557 (5) Å) (Bebout, et al., 1998)and significantly longer than that in bis(pyridine-N)mercury(II) dichromate(VI)(in which, the average Hg—N distance is 2.101 Å) (Weil, 2001).

Related literature

For related literature, see: Bebout et al. (1998); Beck & Sheldrick (2008); Bruker (2000); Matković-Čalogović et al. (2002); Weil (2001); Ziegler et al. (1997). It would be much more useful to readers if the "Related literature" section had some kind of simple sub-division, so that, instead of just "For related literature, see···" it said, for example, "For general background, see···. For related structures, see···.? etc. Please revise this section as indicated.

S2. Experimental

0.27 g (1 mmol) HgCl₂ was dissolved in 10 mL ethanol, 0.54 g (1 mmol) 5-amino-2, 4, 6-triiodoisophthalic acid was dissolved in 10 mL pyridine. To mix two solutions gave slightly brown solution which was stirred at room temperature for 2 h, then filtered. The filtrate was stood for several days until the well formed colorless single crystals were obtained.

S3. Refinement

H atoms were positioned geometrically and refined with riding model, with U_iso = 1.5U_eq for methyl H atoms.

Computing details

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); 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 (Sheldrick, 2008).

Figures

Fig. 1. The molecular structure of title compound, with atom labels and 30% probability displacement ellipsoids. All H atoms have been omitted.

catena-Poly[[dipyridinemercury(II)]- µ-5-amino-2,4,6-triiodoisophthalato]

Crystal data

[Hg(C8H2I3NO4)(C5H5N)2]	Dx = 2.660 Mg m^−3
Mr = 915.60	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, P41212	Cell parameters from 2411 reflections
Hall symbol: P 4abw 2nw	θ = 2.1–25.1°
a = 11.9338 (3) Å	µ = 10.81 mm^−1
c = 16.0532 (10) Å	T = 296 K
V = 2286.23 (16) Å^3	Pyramid, colorless
Z = 4	0.20 × 0.15 × 0.15 mm
F(000) = 1648

Data collection

Bruker SMART APEX CCD diffractometer	2251 independent reflections
Radiation source: fine-focus sealed tube	1661 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.045
ϕ and ω scans	θmax = 26.0°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 2000)	h = −11→14
Tmin = 0.16, Tmax = 0.20	k = −14→12
10399 measured reflections	l = −19→13

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.035	H-atom parameters constrained
wR(F^2) = 0.067	w = 1/[σ^2(Fo^2) + (0.0151P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.001
2251 reflections	Δρmax = 0.63 e Å^−3
134 parameters	Δρmin = −0.53 e Å^−3
57 restraints	Absolute structure: Flack (1983)
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.010 (9)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
C1	0.6137 (6)	0.3863 (6)	0.7500	0.036 (2)
C2	0.6218 (7)	0.3118 (6)	0.6838 (5)	0.041 (2)
C3	0.7046 (7)	0.2319 (7)	0.6843 (5)	0.046 (2)
C4	0.7809 (7)	0.2191 (7)	0.7500	0.049 (3)
C5	0.5357 (7)	0.3173 (8)	0.6152 (6)	0.051 (2)
C6	0.4694 (10)	0.1635 (9)	0.4089 (8)	0.097 (2)
H6	0.5308	0.1844	0.4410	0.116*
C7	0.4795 (12)	0.0725 (11)	0.3565 (8)	0.112 (2)
H7	0.5451	0.0305	0.3549	0.134*
C8	0.3905 (11)	0.0459 (11)	0.3071 (9)	0.118 (2)
H8	0.3965	−0.0087	0.2660	0.142*
C9	0.2919 (11)	0.1019 (10)	0.3198 (8)	0.111 (2)
H9	0.2264	0.0787	0.2937	0.133*
C10	0.2919 (10)	0.1900 (10)	0.3703 (8)	0.098 (2)
H10	0.2266	0.2322	0.3738	0.118*
Hg1	0.37049 (3)	0.37049 (3)	0.5000	0.05760 (17)
I1	0.72004 (6)	0.12434 (7)	0.58073 (4)	0.0764 (2)
I3	0.48846 (5)	0.51154 (5)	0.7500	0.0606 (2)
N1	0.8605 (6)	0.1395 (6)	0.7500	0.065 (3)
H1A	0.9060	0.1340	0.7914	0.077*	0.50
H1B	0.8660	0.0940	0.7086	0.077*	0.50
N2	0.3772 (8)	0.2212 (7)	0.4151 (5)	0.0831 (19)
O1	0.4543 (5)	0.2528 (6)	0.6227 (4)	0.0659 (18)
O2	0.5496 (5)	0.3874 (6)	0.5577 (4)	0.0669 (18)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.033 (4)	0.033 (4)	0.041 (6)	0.002 (5)	0.006 (4)	0.006 (4)
C2	0.041 (5)	0.043 (5)	0.039 (5)	0.002 (4)	0.011 (5)	0.010 (4)
C3	0.045 (5)	0.049 (5)	0.043 (5)	0.002 (4)	−0.002 (4)	0.000 (4)
C4	0.042 (4)	0.042 (4)	0.062 (8)	0.009 (6)	0.004 (5)	0.004 (5)
C5	0.039 (5)	0.062 (6)	0.051 (6)	0.008 (3)	−0.003 (4)	−0.008 (5)
C6	0.091 (5)	0.089 (5)	0.111 (5)	0.019 (4)	−0.038 (4)	−0.034 (4)
C7	0.104 (5)	0.099 (5)	0.132 (6)	0.027 (4)	−0.041 (4)	−0.043 (4)
C8	0.113 (5)	0.103 (5)	0.138 (6)	0.023 (4)	−0.046 (5)	−0.051 (4)
C9	0.103 (5)	0.096 (5)	0.133 (6)	0.015 (4)	−0.052 (5)	−0.045 (4)
C10	0.092 (5)	0.085 (5)	0.117 (5)	0.014 (4)	−0.046 (4)	−0.033 (4)
Hg1	0.0627 (2)	0.0627 (2)	0.0475 (3)	0.0051 (3)	−0.0068 (2)	0.0068 (2)
I1	0.0676 (4)	0.0958 (6)	0.0658 (5)	0.0210 (4)	0.0003 (4)	−0.0324 (4)
I3	0.0547 (3)	0.0547 (3)	0.0723 (6)	0.0119 (4)	0.0044 (3)	0.0044 (3)
N1	0.070 (4)	0.070 (4)	0.053 (6)	0.004 (7)	−0.004 (4)	−0.004 (4)
N2	0.081 (4)	0.072 (4)	0.097 (4)	0.013 (3)	−0.040 (4)	−0.021 (3)
O1	0.050 (4)	0.077 (5)	0.071 (4)	−0.001 (3)	−0.017 (3)	0.008 (3)
O2	0.068 (4)	0.088 (5)	0.044 (4)	0.001 (4)	−0.006 (3)	0.020 (4)

Geometric parameters (Å, º)

C1—C2^i	1.389 (9)	C8—C9	1.368 (15)
C1—I3	2.113 (9)	C8—H8	0.9300
C2—C3	1.373 (10)	C9—C10	1.327 (15)
C2—C5	1.508 (12)	C9—H9	0.9300
C3—C4	1.402 (10)	C10—N2	1.302 (12)
C3—I1	2.108 (8)	C10—H10	0.9300
C4—N1	1.344 (14)	Hg1—N2	2.244 (8)
C4—C3^i	1.402 (10)	Hg1—N2^ii	2.244 (8)
C5—O2	1.257 (10)	Hg1—O2^ii	2.337 (6)
C5—O1	1.245 (10)	Hg1—O2	2.337 (6)
C5—Hg1	2.777 (9)	Hg1—O1^ii	2.618 (6)
C6—N2	1.302 (12)	Hg1—O1	2.618 (6)
C6—C7	1.379 (15)	Hg1—C5^ii	2.777 (9)
C6—H6	0.9300	N1—H1A	0.8600
C7—C8	1.363 (15)	N1—H1B	0.8600
C7—H7	0.9300
C2^i—C1—C2	119.7 (9)	N2^ii—Hg1—O2^ii	106.0 (3)
C2^i—C1—I3	120.2 (5)	N2—Hg1—O2	106.0 (3)
C2—C1—I3	120.2 (5)	N2^ii—Hg1—O2	118.8 (3)
C3—C2—C1	119.4 (8)	O2^ii—Hg1—O2	89.9 (3)
C3—C2—C5	121.6 (8)	N2—Hg1—O1^ii	82.3 (2)
C1—C2—C5	118.9 (7)	N2^ii—Hg1—O1^ii	91.0 (3)
C2—C3—C4	123.1 (8)	O2^ii—Hg1—O1^ii	53.1 (2)
C2—C3—I1	118.8 (6)	O2—Hg1—O1^ii	139.1 (2)
C4—C3—I1	118.1 (6)	N2—Hg1—O1	91.0 (3)
N1—C4—C3^i	122.4 (5)	N2^ii—Hg1—O1	82.3 (2)
N1—C4—C3	122.4 (5)	O2^ii—Hg1—O1	139.1 (2)
C3^i—C4—C3	115.2 (10)	O2—Hg1—O1	53.1 (2)
O2—C5—O1	125.8 (8)	O1^ii—Hg1—O1	167.5 (3)
O2—C5—C2	118.4 (8)	N2—Hg1—C5	101.4 (3)
O1—C5—C2	115.8 (8)	N2^ii—Hg1—C5	99.6 (3)
O2—C5—Hg1	56.8 (4)	O2^ii—Hg1—C5	114.3 (3)
O1—C5—Hg1	69.6 (5)	O2—Hg1—C5	26.7 (2)
C2—C5—Hg1	168.6 (6)	O1^ii—Hg1—C5	165.8 (3)
N2—C6—C7	122.5 (12)	O1—Hg1—C5	26.5 (2)
N2—C6—H6	118.7	N2—Hg1—C5^ii	99.6 (3)
C7—C6—H6	118.7	N2^ii—Hg1—C5^ii	101.4 (3)
C6—C7—C8	118.0 (13)	O2^ii—Hg1—C5^ii	26.7 (2)
C6—C7—H7	121.0	O2—Hg1—C5^ii	114.3 (3)
C8—C7—H7	121.0	O1^ii—Hg1—C5^ii	26.5 (2)
C9—C8—C7	118.0 (12)	O1—Hg1—C5^ii	165.8 (3)
C9—C8—H8	121.0	C5—Hg1—C5^ii	140.2 (4)
C7—C8—H8	121.0	C4—N1—H1A	120.0
C10—C9—C8	118.5 (12)	C4—N1—H1B	120.0
C10—C9—H9	120.7	H1A—N1—H1B	120.0
C8—C9—H9	120.7	C6—N2—C10	117.8 (10)
N2—C10—C9	124.4 (12)	C6—N2—Hg1	119.8 (7)
N2—C10—H10	117.8	C10—N2—Hg1	122.4 (7)
C9—C10—H10	117.8	C5—O1—Hg1	83.9 (5)
N2—Hg1—N2^ii	115.2 (5)	C5—O2—Hg1	96.5 (5)
N2—Hg1—O2^ii	118.8 (3)

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