Poly­[[di­bromo­mercury(II)]-di-μ-pyrazine-κ⁴N:N′]

The crystal structure of [HgBr₂(Pyp)₂]_n (Pyp = pyrazine, C₄H₄N₂) consists of almost linear HgBr₂ mol­ecules which are linked by pyrazine mol­ecules to form double strands of a coordination polymer in the [010] direction. The Hg and Br atoms lie on mirror planes.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.023
• wR factor = 0.038
• Data-to-parameter ratio = 17.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT342_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...          9
PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) .       1.36 Ratio

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-STEP32 (Stoe & Cie, 2000); data reduction: X-RED (Stoe & Cie, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXL97.

Poly[[dibromomercury(II)]-di-µ-pyrazine-k⁴N:N']

Crystal data

[HgBr2(C4H4N2)]	F(000) = 936
Mr = 520.59	Dx = 2.772 Mg m^−3
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 12170 reflections
a = 11.5603 (10) Å	θ = 2.4–24.0°
b = 8.3073 (19) Å	µ = 18.72 mm^−1
c = 12.9906 (16) Å	T = 293 K
V = 1247.6 (3) Å^3	Prism, brown
Z = 4	0.3 × 0.2 × 0.2 mm

Data collection

Stoe IPDS-I diffractometer	1316 independent reflections
Radiation source: fine-focus sealed tube	916 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.086
φ scans	θmax = 26.0°, θmin = 2.4°
Absorption correction: numerical (X-SHAPE; Stoe & Cie, 1998)	h = −14→14
Tmin = 0.229, Tmax = 0.539	k = −9→10
15175 measured reflections	l = −16→16

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)] = 0.023	H-atom parameters constrained
wR(F^2) = 0.038	w = 1/[σ^2(Fo^2) + (0.0115P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.85	(Δ/σ)max < 0.001
1316 reflections	Δρmax = 0.77 e Å^−3
74 parameters	Δρmin = −0.58 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00104 (6)

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
Hg	0.30513 (3)	0.7500	−0.01735 (2)	0.04273 (11)
Br1	0.31147 (8)	0.7500	−0.20761 (6)	0.0498 (2)
Br2	0.34415 (7)	0.7500	0.16952 (6)	0.0475 (2)
N1	0.1097 (4)	0.5684 (6)	−0.0083 (4)	0.0593 (13)
N2	0.3657 (3)	0.0818 (5)	−0.0193 (4)	0.0478 (11)
C1	0.0458 (6)	0.5347 (11)	−0.0886 (5)	0.068 (2)
H1	0.0754	0.5551	−0.1539	0.081*
C2	0.0631 (6)	0.5294 (10)	0.0802 (5)	0.065 (2)
H2	0.1058	0.5459	0.1399	0.078*
C3	0.3404 (5)	0.1680 (8)	−0.1021 (4)	0.0488 (15)
H3	0.3219	0.1144	−0.1627	0.059*
C4	0.3930 (5)	0.1677 (8)	0.0641 (5)	0.0517 (16)
H4	0.4127	0.1136	0.1243	0.062*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Hg	0.04316 (15)	0.0515 (2)	0.03352 (16)	0.000	0.00078 (16)	0.000
Br1	0.0692 (5)	0.0462 (5)	0.0341 (4)	0.000	0.0027 (4)	0.000
Br2	0.0583 (5)	0.0493 (6)	0.0349 (5)	0.000	−0.0008 (3)	0.000
N1	0.047 (2)	0.073 (4)	0.058 (4)	−0.009 (2)	−0.003 (3)	0.005 (3)
N2	0.048 (2)	0.043 (3)	0.052 (3)	0.001 (2)	−0.005 (2)	0.002 (3)
C1	0.066 (4)	0.095 (7)	0.043 (4)	−0.026 (4)	0.006 (3)	0.009 (4)
C2	0.069 (5)	0.083 (6)	0.042 (4)	−0.027 (4)	−0.013 (3)	0.012 (3)
C3	0.068 (4)	0.040 (3)	0.039 (3)	0.000 (3)	−0.004 (3)	−0.002 (3)
C4	0.067 (4)	0.045 (4)	0.044 (4)	0.002 (3)	−0.012 (3)	0.006 (3)

Geometric parameters (Å, º)

Hg—Br2	2.4691 (10)	N2—Hg^iv	2.844 (4)
Hg—Br1	2.4726 (9)	C1—C2^v	1.372 (8)
Hg—N1	2.719 (4)	C1—H1	0.930
Hg—N1^i	2.719 (4)	C2—C1^v	1.372 (8)
Hg—N2^ii	2.844 (4)	C2—H2	0.930
Hg—N2^iii	2.844 (4)	C3—C3^ii	1.362 (12)
N1—C1	1.309 (8)	C3—H3	0.930
N1—C2	1.310 (8)	C4—C4^ii	1.368 (13)
N2—C3	1.324 (7)	C4—H4	0.930
N2—C4	1.335 (7)
Br2—Hg—Br1	167.78 (3)	C2—N1—Hg	121.1 (4)
Br2—Hg—N1	96.27 (12)	C3—N2—C4	115.0 (5)
Br1—Hg—N1	93.89 (12)	C3—N2—Hg^iv	118.5 (4)
Br2—Hg—N1^i	96.27 (12)	C4—N2—Hg^iv	124.7 (4)
Br1—Hg—N1^i	93.89 (12)	N1—C1—C2^v	122.5 (6)
N1—Hg—N1^i	67.4 (2)	N1—C1—H1	118.7
Br2—Hg—N2^ii	87.93 (11)	C2^v—C1—H1	118.7
Br1—Hg—N2^ii	89.07 (11)	N1—C2—C1^v	123.0 (5)
N1—Hg—N2^ii	70.56 (14)	N1—C2—H2	118.5
N1^i—Hg—N2^ii	137.95 (13)	C1^v—C2—H2	118.5
Br2—Hg—N2^iii	87.93 (11)	N2—C3—C3^ii	122.7 (3)
Br1—Hg—N2^iii	89.07 (11)	N2—C3—H3	118.6
N1—Hg—N2^iii	137.95 (13)	C3^ii—C3—H3	118.6
N1^i—Hg—N2^iii	70.56 (14)	N2—C4—C4^ii	122.3 (3)
N2^ii—Hg—N2^iii	151.49 (16)	N2—C4—H4	118.9
C1—N1—C2	114.5 (5)	C4^ii—C4—H4	118.9
C1—N1—Hg	123.6 (4)

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