catena-Poly[[di­iodidomercury(II)]-μ₂-2-amino­pyrazine-κ²N¹:N⁴]

In the crystal of the title polymeric compound, [HgI₂(C₄H₅N₃)]_n, the Hg^II cation is located on a twofold rotation axis and is coordinated by two I⁻ anions and two 2-amino­pyrazine ligands in a distorted HgI₂N₂ tetra­hedral geometry. In the crystal, the 2-amino­pyrazine ligand is equally disordered over two positions about an inversion center, and bridges the Hg^II cations with pyrazine N atoms to form a polymeric chain running along the c axis. In the polymeric chain, the amino groups link to the coordinated I⁻ anions via inter­molecular N—H⋯I hydrogen bonds.

Related literature

For related structures, see: Sun et al. (2009); Pagola et al. (2008); Boonmak et al. (2010); Gao & Ng (2011); Goher et al. (2008).

Experimental

Crystal data

• [HgI₂(C₄H₅N₃)]

• M_r = 549.50

• Monoclinic, C 2/c

• a = 15.3389 (19) Å

• b = 6.8791 (8) Å

• c = 9.6239 (11) Å

• β = 103.828 (10)°

• V = 986.1 (2) ų

• Z = 4

• Mo Kα radiation

• μ = 21.81 mm⁻¹

• T = 298 K

• 0.50 × 0.05 × 0.04 mm

Data collection

• Bruker APEXII CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2001) T_min = 0.275, T_max = 0.417

• 2648 measured reflections

• 933 independent reflections

• 911 reflections with I > 2σ(I)

• R_int = 0.173

Refinement

• R[F² > 2σ(F²)] = 0.083

• wR(F²) = 0.224

• S = 1.08

• 933 reflections

• 52 parameters

• H-atom parameters constrained

• Δρ_max = 2.67 e Å⁻³

• Δρ_min = −2.69 e Å⁻³

Table 1
Selected bond lengths (Å)

Hg1—I1	2.6373 (13)
Hg1—N1^i	2.497 (11)
Symmetry code: (i) .

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2A⋯I1^i	0.86	2.83	3.67 (3)	169
Symmetry code: (i) .

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Supporting information

S1. Comment

2-Aminopyrazine is a good ligand and numerous complexes with 2-aminopyrazine have been prepared, such as that of silver (Sun et al., 2009), copper (Pagola et al., 2008), cobalt, iron and cadmium (Boonmak et al., 2010) and zinc (Gao & Ng, 2011; Goher et al., 2008). Here, we report the synthesis and structure of the title compound.

The asymmetric unit of the title compound, (Fig. 1), contains one half molecule. The Hg^II atom is four-coordinated in a distorted tetrahedral configuration by two N atoms from two 2-aminopyrazine and two I atoms. The Hgd-I and Hg—N bond lengths angles are collected in Table 1.

Intermolecular N—H···I hydrogen bonds (Table 2) seem to be effective in the stabilization of the polymeric structure (Fig. 2).

Related literature

For related structures, see: Sun et al. (2009); Pagola et al. (2008); Boonmak et al. (2010); Gao & Ng (2011); Goher et al. (2008).

S2. Experimental

For the preparation of the title compound, a solution of 2-aminopyrazine (0.15 g, 1.50 mmol) in methanol (10 ml) was added to a solution of HgI₂ (0.55 g, 1.50 mmol) in methanol (10 ml) and the resulting colorless solution was stirred for 15 min at room temperature. This solution was left to evaporate slowly at room temperature. After one week, colorless needle crystals of the title compound were isolated (yield 0.63 g, 76.4%).

S3. Refinement

H atoms were positioned geometrically with C—H = 0.93 and N—H = 0.86 Å, and constrained to ride on their parent atoms with U_iso(H) = 1.2U_eq(C,N). In the crystal, the 2-aminopyrazine ring is equqlly disordered over two positions about an inversion center.

Computing details

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

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 codes: #1: -x, 1 - y, 1 - z; #2: -x, y, 3/2 - z].
	Fig. 2. A packing diagram of the title complex. Hydrogen bonds are shown as dashed lines.

catena-Poly[[diiodidomercury(II)]-µ₂-2-aminopyrazine- κ²N¹:N⁴]

Crystal data

[HgI2(C4H5N3)]	F(000) = 944
Mr = 549.50	Dx = 3.701 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 2648 reflections
a = 15.3389 (19) Å	θ = 2.7–26.0°
b = 6.8791 (8) Å	µ = 21.81 mm^−1
c = 9.6239 (11) Å	T = 298 K
β = 103.828 (10)°	Needle, colorless
V = 986.1 (2) Å^3	0.50 × 0.05 × 0.04 mm
Z = 4

Data collection

Bruker APEXII CCD area-detector diffractometer	933 independent reflections
Radiation source: fine-focus sealed tube	911 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.173
ω scans	θmax = 26.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −18→18
Tmin = 0.275, Tmax = 0.417	k = −8→8
2648 measured reflections	l = −11→8

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)] = 0.083	H-atom parameters constrained
wR(F^2) = 0.224	w = 1/[σ^2(Fo^2) + (0.1405P)^2 + 17.0935P] where P = (Fo^2 + 2Fc^2)/3
S = 1.08	(Δ/σ)max = 0.002
933 reflections	Δρmax = 2.67 e Å^−3
52 parameters	Δρmin = −2.69 e Å^−3
0 restraints	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.015 (2)

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	0.0725 (10)	0.383 (2)	0.5415 (17)	0.042 (3)
H1	0.1234	0.3063	0.5710	0.050*
C2	−0.0746 (11)	0.455 (2)	0.542 (2)	0.044 (3)
H2C	−0.1274	0.4240	0.5694	0.054*	0.50
N1	−0.0046 (8)	0.3371 (17)	0.5809 (12)	0.040 (2)
N2	−0.154 (2)	0.409 (5)	0.578 (4)	0.059 (8)	0.50
H2A	−0.1586	0.3048	0.6251	0.071*	0.50
H2B	−0.1999	0.4856	0.5531	0.071*	0.50
Hg1	0.0000	0.05992 (11)	0.7500	0.0451 (6)
I1	0.16288 (9)	−0.07523 (19)	0.76493 (17)	0.0629 (7)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.038 (7)	0.040 (7)	0.051 (7)	0.005 (6)	0.016 (6)	0.008 (7)
C2	0.034 (7)	0.046 (8)	0.055 (9)	−0.003 (5)	0.016 (6)	0.005 (6)
N1	0.039 (6)	0.035 (5)	0.050 (6)	0.002 (4)	0.018 (5)	0.004 (5)
N2	0.054 (17)	0.062 (17)	0.070 (17)	0.020 (14)	0.032 (15)	0.034 (14)
Hg1	0.0390 (8)	0.0411 (8)	0.0576 (8)	0.000	0.0164 (5)	0.000
I1	0.0484 (10)	0.0655 (10)	0.0793 (11)	0.0199 (5)	0.0241 (7)	0.0154 (5)

Geometric parameters (Å, º)

C1—N1	1.363 (19)	N1—Hg1	2.497 (11)
C1—C2^i	1.38 (2)	N2—H2A	0.8600
C1—H1	0.9300	N2—H2B	0.8600
C2—N1	1.33 (2)	Hg1—I1^ii	2.6372 (13)
C2—H2C	0.9300	Hg1—I1	2.6373 (13)
C2—C1^i	1.38 (2)	Hg1—N1^ii	2.497 (11)
C2—N2	1.38 (4)
N1—C1—C2^i	119.6 (14)	C1—N1—Hg1	117.9 (10)
N1—C1—H1	120.2	C2—N2—H2A	120.0
C2^i—C1—H1	120.2	C2—N2—H2B	120.0
C1^i—C2—H2C	119.0	H2A—N2—H2B	120.0
N1^i—C2—H2C	149.0	N1^ii—Hg1—N1	80.4 (5)
N1—C2—C1^i	121.6 (15)	N1^ii—Hg1—I1^ii	100.6 (3)
N1—C2—N2	120.0 (17)	N1—Hg1—I1^ii	110.8 (3)
C1^i—C2—N2	118.2 (18)	N1^ii—Hg1—I1	110.8 (3)
C2—N1—C1	118.6 (13)	N1—Hg1—I1	100.6 (3)
C2—N1—Hg1	122.9 (10)	I1^ii—Hg1—I1	138.71 (7)
C1^i—C2—N1—C1	3 (3)	C2—N1—Hg1—N1^ii	−68.8 (12)
N2—C2—N1—C1	179 (2)	C1—N1—Hg1—N1^ii	102.6 (12)
C1^i—C2—N1—Hg1	174.4 (13)	C2—N1—Hg1—I1^ii	29.0 (13)
N2—C2—N1—Hg1	−10 (3)	C1—N1—Hg1—I1^ii	−159.7 (10)
C2^i—C1—N1—C2	−3 (3)	C2—N1—Hg1—I1	−178.4 (12)
C2^i—C1—N1—Hg1	−174.8 (12)	C1—N1—Hg1—I1	−7.0 (11)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···I1^ii	0.86	2.83	3.67 (3)	169

Symmetry code: (ii) −x, y, −z+3/2.