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Acta Crystallogr Sect E Struct Rep Online. 2008 January 1; 64(Pt 1): m13.
Published online 2007 December 6. doi:  10.1107/S1600536807061491
PMCID: PMC2914906

Dibromidobis(pyrazine-2-carboxylic acid-κN 4)mercury(II) dihydrate

Abstract

The asymmetric unit of the title compound, [HgBr2(C5H4N2O2)2]·2H2O, contains one half-mol­ecule and one water mol­ecule. The HgII ion, lying on a twofold rotation axis, is four-coordinated by two N atoms of pyrazine-2-carboxylic acid ligands and two bromide ions, forming a highly distorted tetrahedral geometry. In the crystal structure, inter­molecular O—H(...)O and O—H(...)N hydrogen bonds link the mol­ecules.

Related literature

For general background, see: O’Conner et al. (1982 [triangle]); Zhang (2005 [triangle]); Zou et al. (1999 [triangle]). For a related structure, see: Wang et al.(2007 [triangle]). For bond-length data, see: Allen et al. (1987 [triangle]).

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Object name is e-64-00m13-scheme1.jpg

Experimental

Crystal data

  • [HgBr2(C5H4N2O2)2]·2H2O
  • M r = 644.63
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-00m13-efi2.jpg
  • a = 13.895 (1) Å
  • b = 5.7176 (2) Å
  • c = 21.8753 (7) Å
  • β = 102.544 (2)°
  • V = 1696.42 (15) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 13.82 mm−1
  • T = 294 (2) K
  • 0.4 × 0.2 × 0.2 mm

Data collection

  • Enraf–Nonius CAD-4 diffractometer
  • Absorption correction: ψ scan (North et al., 1968 [triangle]) T min = 0.048, T max = 0.063
  • 2775 measured reflections
  • 1480 independent reflections
  • 1287 reflections with I > 2σ(I)
  • R int = 0.062
  • 3 standard reflections every 200 reflections intensity decay: none

Refinement

  • R[F 2 > 2σ(F 2)] = 0.070
  • wR(F 2) = 0.150
  • S = 1.12
  • 1480 reflections
  • 112 parameters
  • 2 restraints
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 2.85 e Å−3
  • Δρmin = −3.62 e Å−3

Data collection: CAD-4 Software (Enraf–Nonius, 1989 [triangle]); cell refinement: CAD-4 Software; data reduction: XCAD4 (Harms & Wocadlo, 1995 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 [triangle]); molecular graphics: SHELXTL (Bruker, 2000 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Selected geometric parameters (Å, °)
Table 2
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536807061491/hk2365sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536807061491/hk2365Isup2.hkl

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

Acknowledgments

The authors thank the Center for Testing and Analysis, Nanjing University for support.

supplementary crystallographic information

Comment

Functional materials built up by organic ligands and metal ions, especially transition metals, have potential applications in optics, electronics, magnetics, biology, catalyst and medicine (Zhang, 2005; O'Conner et al., 1982). Pyrazine-2,3-dicarboxylic acid, having six possible coordination sites, is a good ligand with versatile coordination types, which is widely used in the self-assembled polymeric coordination synthesis (Zou et al., 1999; Wang et al., 2007). The title compound, (I), was obtained unintentionally as the product of a hydrothermal synthesis of pyrazine-2,3-dicarboxylic acid and mercury(II) bromide. Under high temperature as 413 K and mercury(II) ion catalyst, pyrazine-2,3-dicarboxylic acid is likely to decarboxylate as 2-pyrazine carboxylic acid. We report herein the crystal structure of (I), a complex containing the ligand of 2-pyrazine carboxylic acid.

The asymmetric unit of (I), (Fig. 1), contains one half-molecule and one water molecule, in which the bond lengths and angles are within normal ranges (Allen et al., 1987). The HgII ion lying on a twofold rotation axis, is four -coordinated (Table 1) by two N atoms of pyrazine carboxylic acid ligands and two bromide atoms. The two pyrazine rings are oriented at a dihedral angle of 78.4 (9)°.

The Hg—N [2.528 (13) Å] bond is slightly longer, while Hg—Br [2.4234 (15) Å] bond is slightly shorter than the corresponding values [2.270 (5) Å and 2.5269 (7) Å, respectively] in [Hg(bib)Br2]0.5THF (where bib is 1-bromo-3,5 -bis(imidazol-1-ylmethyl)benzene) (Wang et al., 2007).

In the crystal structure, intermolecular O—H···O and O—H···N hydrogen bonds (Table 2, Fig. 2) link the molecules, in which they seem to be effective in the stabilization of the structure.

Experimental

For the preparation of the title compound, mercury(II) bromide (360 mg, 1 mmol) and 2,3-pyrazine dicarboxylic acid (168 mg, 1 mmol) were dissolved in a mixed solvent of ethanol (5 ml) and acetonitrile (5 ml). Then the mixture was added into a Teflon-lined stainless steel autoclave at 413 K for 2 d. The green crystals were obtained after cooling to room temperature and was filtrated. Elemental analysis calcd: C 19.58%, H 4.40%, N 45.60%; Found: C 19.51%, H 4.35%, N 45.53%.

Refinement

H atoms (for H2O) were located in a difference map and refined [O—H = 0.84 (2) and 0.84 (2) Å, Uiso(H) = 1.5Ueq(O)]. The remaining H atoms were positioned geometrically, with O—H = 0.82 Å (for OH) and C—H = 0.93 Å, for aromatic H atoms and constrained to ride on their parent atoms, with Uiso(H) = xUeq(C,O), where x = 1.2 for aromatic H and x = 1.5 for OH H atoms.

Figures

Fig. 1.
The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level [symmetry code A: 2 - x, y, 3/2 - z]. Hydrogen bonds are shown as dashed lines.
Fig. 2.
A packing diagram of (I). Hydrogen bonds are shown as dashed lines.

Crystal data

[HgBr2(C5H4N2O2)2]·2H2OF000 = 1192
Mr = 644.63Dx = 2.524 Mg m3
Monoclinic, C2/cMo Kα radiation λ = 0.71073 Å
Hall symbol: -C 2ycCell parameters from 25 reflections
a = 13.895 (1) Åθ = 9–13º
b = 5.7176 (2) ŵ = 13.82 mm1
c = 21.8753 (7) ÅT = 294 (2) K
β = 102.544 (2)ºBlock, green
V = 1696.42 (15) Å30.4 × 0.2 × 0.2 mm
Z = 4

Data collection

Enraf–Nonius CAD-4 diffractometerRint = 0.062
Radiation source: fine-focus sealed tubeθmax = 25.1º
Monochromator: graphiteθmin = 1.9º
T = 294(2) Kh = −16→8
ω/2θ scansk = −6→5
Absorption correction: ψ scan(North et al., 1968)l = −20→26
Tmin = 0.048, Tmax = 0.0633 standard reflections
2775 measured reflections every 200 reflections
1480 independent reflections intensity decay: none
1287 reflections with I > 2σ(I)

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.070H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.150  w = 1/[σ2(Fo2) + (0.1015P)2 + 4.7441P] where P = (Fo2 + 2Fc2)/3
S = 1.12(Δ/σ)max < 0.001
1480 reflectionsΔρmax = 2.85 e Å3
112 parametersΔρmin = −3.62 e Å3
2 restraintsExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0045 (4)

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 (Å2)

xyzUiso*/Ueq
Hg11.00001.10939 (9)0.75000.0355 (4)
Br11.16422 (12)1.2057 (6)0.73701 (9)0.0525 (6)
C10.8717 (5)0.6941 (4)0.6566 (4)0.039 (4)
H10.82340.75610.67540.047*
C20.8499 (5)0.5080 (4)0.6166 (4)0.041 (4)
H20.78710.44270.60930.050*
C31.0047 (6)0.5069 (4)0.6006 (6)0.030 (3)
C41.0302 (6)0.6941 (6)0.6411 (6)0.043 (5)
H41.09400.75380.64900.051*
C51.0825 (6)0.4040 (4)0.5701 (5)0.029 (3)
N10.9628 (7)0.7881 (7)0.6688 (6)0.033 (3)
N20.9161 (7)0.4188 (7)0.5885 (5)0.034 (3)
O11.1642 (8)0.4862 (6)0.5761 (6)0.046 (3)
O21.0514 (10)0.2121 (5)0.5379 (6)0.060 (4)
H2A1.09540.16060.52210.090*
O30.8315 (9)0.0042 (3)0.5179 (6)0.051 (3)
H3A0.794 (2)−0.090 (3)0.531 (2)0.077*
H3B0.857 (2)0.123 (2)0.537 (2)0.077*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Hg10.0234 (5)0.0443 (7)0.0442 (6)0.0000.0149 (3)0.000
Br10.0263 (10)0.0587 (14)0.0617 (13)−0.0056 (8)0.0225 (9)0.0088 (10)
C10.029 (9)0.045 (10)0.047 (10)0.007 (8)0.017 (7)−0.011 (8)
C20.031 (8)0.050 (11)0.045 (10)0.000 (9)0.014 (7)−0.004 (9)
C30.027 (7)0.044 (10)0.021 (7)−0.011 (7)0.005 (6)0.003 (7)
C40.029 (8)0.051 (13)0.027 (8)0.004 (9)0.020 (7)−0.009 (8)
C50.035 (9)0.032 (8)0.033 (7)0.001 (7)0.012 (6)0.006 (7)
N10.037 (7)0.034 (8)0.032 (7)0.000 (6)0.012 (6)−0.012 (6)
N20.033 (6)0.053 (9)0.028 (6)−0.012 (6)0.002 (5)−0.008 (6)
O10.030 (6)0.054 (8)0.051 (7)−0.011 (6)0.016 (5)−0.020 (6)
O20.050 (8)0.061 (9)0.057 (9)−0.010 (7)0.033 (7)−0.039 (8)
O30.039 (7)0.052 (9)0.052 (9)−0.014 (7)0.033 (6)−0.030 (7)

Geometric parameters (Å, °)

Hg1—Br12.4234 (15)C3—C41.381 (6)
Hg1—Br1i2.4234 (15)C3—C51.510 (7)
Hg1—N12.528 (13)C4—N11.334 (10)
Hg1—N1i2.528 (13)C4—H40.9300
C1—N11.351 (7)C5—O11.209 (18)
C1—C21.369 (8)C5—O21.327 (19)
C1—H10.9300O2—H2A0.8200
C2—N21.310 (6)O3—H3A0.84 (2)
C2—H20.9300O3—H3B0.84 (2)
C3—N21.303 (8)
Br1—Hg1—Br1i153.72 (12)C4—C3—C5118.4 (6)
Br1—Hg1—N197.8 (3)N1—C4—C3119.6 (7)
Br1i—Hg1—N1101.2 (3)N1—C4—H4120.2
Br1—Hg1—N1i101.2 (3)C3—C4—H4120.2
Br1i—Hg1—N1i97.8 (3)O1—C5—O2124.8 (7)
N1—Hg1—N1i86.9 (6)O1—C5—C3123.1 (8)
N1—C1—C2120.3 (8)O2—C5—C3112.1 (6)
N1—C1—H1119.8C1—N1—C4118.1 (7)
C2—C1—H1119.8C1—N1—Hg1118.0 (10)
N2—C2—C1121.3 (8)C4—N1—Hg1123.7 (11)
N2—C2—H2119.4C2—N2—C3118.7 (8)
C1—C2—H2119.4C5—O2—H2A109.5
N2—C3—C4122.0 (7)H3A—O3—H3B125 (4)
N2—C3—C5119.6 (8)
N1—C1—C2—N2−1.0 (12)C3—C4—N1—Hg1175.2 (12)
N2—C3—C4—N1−0.3 (13)Br1—Hg1—N1—C1−174.8 (12)
C5—C3—C4—N1−179.9 (15)Br1i—Hg1—N1—C1−13.0 (13)
N2—C3—C5—O1175.2 (15)N1i—Hg1—N1—C184.4 (13)
C4—C3—C5—O1−4.8 (12)Br1—Hg1—N1—C410.9 (13)
N2—C3—C5—O2−7.1 (11)Br1i—Hg1—N1—C4172.7 (13)
C4—C3—C5—O2173.3 (15)N1i—Hg1—N1—C4−89.9 (14)
C2—C1—N1—C40.3 (9)C1—C2—N2—C31.8 (12)
C2—C1—N1—Hg1−175.1 (5)C4—C3—N2—C2−1.1 (11)
C3—C4—N1—C11.2 (9)C5—C3—N2—C2178.5 (14)

Symmetry codes: (i) −x+2, y, −z+3/2.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O2—H2A···O3ii0.821.752.56 (2)166
O3—H3A···O1iii0.84 (2)2.28 (3)2.89 (2)130 (2)
O3—H3B···N20.84 (2)2.09 (3)2.93 (2)177 (3)

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HK2365).

References

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  • Bruker (2000). SHELXTL Bruker AXS Inc., Madison, Wisconsin, USA.
  • Enraf–Nonius (1989). CAD-4 Software Version 5.0. Enraf–Nonius, Delft, The Netherlands.
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  • North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359.
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