Retracted: catena-Poly[[aqua­(pyrazine-2-car­boxyl­ato-κ²N¹,O)zinc(II)]-μ-pyrazine-2-car­boxyl­ato-κ²N¹,O:N⁴]

The title compound, [Zn(C₅H₃N₂O₂)₂(H₂O)]_n, prepared by hydro­thermal synthesis, is isostructural with its Fe^II, Co^II, Ni^II and Cu^II analogues. The asymmetric unit contains two bidentate pyrazine-2-carboxyl­ate anions bonded to Zn^II in the equatorial plane through one N and one O atom each. The Zn^II atoms are linked into a chain by the second N atom of the anion bonding to an axial site of a neighbouring Zn^II atom. The slightly distorted octa­hedral coordination around Zn^II is completed by a water mol­ecule, which forms hydrogen bonds to link the chains into a three-dimensional structure. The crystal studied was an inversion twin.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](Wave) = 0.000 Å
• R factor = 0.034
• wR factor = 0.096
• Data-to-parameter ratio = 12.5

checkCIF/PLATON results

No syntax errors found



Alert level C
STRVA01_ALERT_4_C           Flack test results are ambiguous.
           From the CIF: _refine_ls_abs_structure_Flack    0.469
           From the CIF: _refine_ls_abs_structure_Flack_su    0.018

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           26.51
           From the CIF: _reflns_number_total               2353
           Count of symmetry unique reflns         1391
           Completeness (_total/calc)            169.16%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       962
           Fraction of Friedel pairs measured     0.692
           Are heavy atom types Z>Si present        yes

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

   0 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
   0 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

---

S1. Comment

The title compound, (I), [Zn(C₅H₃N₂O₂)₂(H₂O)]_n, is isostructural with its Fe^II, Co^II, Ni^II, and Cu^II analogues (Hao & Liu, 2007; Hao et al., 2007; Gao et al., 2007a,b). The Zn^II atoms is coordinated in a bidentate fashion by two O and two N atoms from two independent pyrazine-2-carboxylate anions. The distorted octhedral coordiantion is completed by another N atom from a third pyrazine-2-carboxylate ligand, and by the O atom of a water molecule (Fig. 1). The Zn—N and Zn—O bond lengths are in the range of 2.058 (3)–2.105 (3) and 2.042 (3)–2.073 (3) Å, respectively. One pyrazine-2-carboxylate ligand coordinates to a neighboring Zn^II atom via its second N atom, leading to polymeric structure with zigzag chains extending parallel to the b axis (Fig. 2). Hydrogen bonds between the water molecule and the carboxylate groups stabilize the structure. The refined Flack parameter of 0.469 (18) indicates inversion twinning.

Related literature

For the isostructural Fe^II, Co^II, Ni^II and Cu^II analogues, see: Hao & Liu (2007); Hao et al. (2007); Gao et al. (2007a,b).

S2. Experimental

All chemicals used were purchased from Jinan Henghua Sci & Tec Co. Ltd. A mixture of Zinc(II) acetate dihydrate (0.5 mmol), potassium hydroxide (0.5 mmol), 2-pyrazine caboxylic acid (0.5 mmol), EtOH (8 ml) and H₂O (8 ml) in a 25 ml Teflon-lined stainless steel autoclave was kept at 413 K for 2 d, and then cooled to room temperature. Colorless crystals of (I) were obtained in a yield of 36%. Anal. Calc. for C₁₀H₈ZnN₄O₅: C 36.62, H 2.44, N 17.09%; Found: C 36.59, H 2.47, N 17.01%.

S3. Refinement

C-bound H atoms were generated geometrically (C—H = 0.93 Å) and refined as riding, with U_iso(H) = 1.2U_eq(C). H atoms of the water molecule were located in a difference density map and were refined with distance restraints of O—H = 0.82 (1) and H—H = 1.38 (2) Å.

Computing details

Data collection: APEX2 (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2001); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. A fragment of the structure of the title compound, showing 30% probability displacement ellipsoids. Atoms labeled with I at the symmetry positions (-x + 1, y - 1/2, -z + 3/2).
	Fig. 2. A part of polymeric structure of the title compound.

catena-Poly[aquabis(pyrazine-2-carboxylato-κ²N¹,O)zinc(II)]- µ-pyrazine-2-carboxylato-κ³N¹,O:N⁴]

Crystal data

[Zn(C5H3N2O2)2(H2O)]	F(000) = 664
Mr = 329.57	Dx = 1.908 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 2347 reflections
a = 7.8932 (6) Å	θ = 2.5–26.7°
b = 9.7615 (10) Å	µ = 2.17 mm^−1
c = 14.8921 (15) Å	T = 298 K
V = 1147.43 (19) Å^3	Cube, colorless
Z = 4	0.10 × 0.10 × 0.10 mm

Data collection

Bruker APEX II CCD area-detector diffractometer	2353 independent reflections
Radiation source: fine-focus sealed tube	2200 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
φ and ω scans	θmax = 26.5°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −8→9
Tmin = 0.812, Tmax = 0.812	k = −12→11
6232 measured reflections	l = −18→9

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)] = 0.034	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.096	w = 1/[σ^2(Fo^2) + (0.072P)^2 + 0.4177P] where P = (Fo^2 + 2Fc^2)/3
S = 1.00	(Δ/σ)max < 0.001
2353 reflections	Δρmax = 0.98 e Å^−3
188 parameters	Δρmin = −0.34 e Å^−3
3 restraints	Absolute structure: Flack (1983), 974 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.469 (18)

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
Zn1	0.92678 (6)	0.86587 (4)	0.90927 (3)	0.02030 (14)
C1	0.6936 (5)	0.6911 (4)	0.8171 (2)	0.0175 (7)
C2	1.1621 (5)	0.6694 (4)	0.7997 (3)	0.0207 (8)
H2	1.2562	0.7111	0.8254	0.025*
C3	0.8722 (4)	0.6460 (4)	0.7893 (2)	0.0155 (7)
C4	1.1047 (5)	1.0415 (4)	0.7732 (2)	0.0182 (8)
H4	1.1989	0.9959	0.7960	0.022*
C5	0.8158 (5)	1.0668 (4)	0.7636 (3)	0.0230 (8)
H5	0.7069	1.0406	0.7801	0.028*
C6	0.6757 (5)	1.0566 (4)	1.0101 (3)	0.0241 (8)
H6	0.5873	1.0211	0.9760	0.029*
C7	0.6414 (5)	1.1488 (4)	1.0786 (3)	0.0278 (8)
H7	0.5299	1.1738	1.0901	0.033*
C8	0.9257 (6)	1.1651 (4)	1.1088 (3)	0.0307 (9)
H8	1.0146	1.2021	1.1418	0.037*
C9	0.9613 (5)	1.0733 (4)	1.0410 (3)	0.0218 (8)
C10	1.1434 (5)	1.0288 (4)	1.0192 (3)	0.0214 (8)
H1W	1.011 (4)	0.703 (6)	1.031 (5)	0.080*
H2W	0.839 (5)	0.680 (5)	1.015 (5)	0.080*
N1	0.7664 (5)	1.2023 (4)	1.1284 (3)	0.0361 (9)
N2	0.8349 (4)	1.0186 (3)	0.9928 (2)	0.0183 (6)
N3	1.0061 (4)	0.7089 (3)	0.8242 (2)	0.0171 (6)
N4	0.9497 (4)	1.0051 (3)	0.80119 (19)	0.0189 (6)
O1	1.1531 (3)	0.9352 (3)	0.95911 (17)	0.0196 (5)
O2	1.2633 (4)	1.0798 (4)	1.0587 (2)	0.0402 (8)
O3	0.6936 (3)	0.7969 (3)	0.86870 (17)	0.0191 (5)
O4	0.5686 (3)	0.6308 (3)	0.79110 (18)	0.0275 (6)
O5	0.9181 (4)	0.7349 (3)	1.01674 (18)	0.0253 (6)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn1	0.0199 (2)	0.0205 (2)	0.0205 (2)	0.00011 (17)	0.00053 (17)	−0.00065 (17)
C1	0.0161 (17)	0.0199 (17)	0.0166 (17)	0.0015 (14)	0.0025 (14)	0.0033 (14)
C2	0.0168 (18)	0.022 (2)	0.0236 (18)	0.0008 (15)	−0.0016 (15)	−0.0049 (15)
C3	0.0178 (17)	0.0162 (16)	0.0124 (14)	0.0000 (13)	0.0005 (12)	0.0004 (14)
C4	0.0180 (19)	0.0184 (17)	0.0182 (16)	−0.0013 (14)	−0.0005 (14)	0.0040 (14)
C5	0.0190 (19)	0.0247 (19)	0.025 (2)	−0.0006 (16)	−0.0003 (15)	0.0044 (16)
C6	0.0194 (19)	0.0221 (19)	0.031 (2)	−0.0023 (15)	−0.0030 (16)	−0.0006 (16)
C7	0.0216 (18)	0.028 (2)	0.034 (2)	0.0025 (16)	0.0026 (17)	−0.0086 (19)
C8	0.027 (2)	0.032 (2)	0.033 (2)	−0.002 (2)	−0.0027 (19)	−0.0137 (16)
C9	0.021 (2)	0.0233 (19)	0.0217 (18)	−0.0011 (15)	−0.0001 (14)	0.0029 (15)
C10	0.0188 (19)	0.0220 (19)	0.0233 (18)	0.0022 (15)	0.0001 (15)	0.0042 (15)
N1	0.032 (2)	0.037 (2)	0.039 (2)	0.0051 (17)	0.0042 (17)	−0.0166 (17)
N2	0.0179 (15)	0.0165 (15)	0.0205 (15)	0.0002 (12)	0.0003 (13)	−0.0005 (12)
N3	0.0175 (14)	0.0179 (15)	0.0160 (15)	−0.0017 (12)	0.0005 (12)	0.0019 (12)
N4	0.0208 (16)	0.0175 (14)	0.0182 (14)	0.0007 (13)	−0.0019 (13)	0.0012 (12)
O1	0.0165 (12)	0.0192 (13)	0.0230 (13)	0.0023 (10)	−0.0012 (11)	−0.0033 (11)
O2	0.0228 (15)	0.047 (2)	0.051 (2)	−0.0052 (14)	−0.0092 (14)	−0.0173 (16)
O3	0.0145 (12)	0.0234 (14)	0.0195 (13)	0.0001 (11)	0.0021 (10)	−0.0048 (11)
O4	0.0161 (12)	0.0330 (14)	0.0333 (14)	−0.0063 (15)	0.0019 (12)	−0.0075 (12)
O5	0.0220 (13)	0.0283 (14)	0.0255 (13)	−0.0088 (13)	−0.0038 (13)	0.0119 (11)

Geometric parameters (Å, º)

Zn1—O5	2.049 (2)	C5—N4	1.339 (5)
Zn1—O1	2.050 (3)	C5—C2^ii	1.386 (5)
Zn1—O3	2.051 (3)	C5—H5	0.9300
Zn1—N2	2.073 (3)	C6—N2	1.335 (5)
Zn1—N3	2.085 (3)	C6—C7	1.386 (6)
Zn1—N4	2.114 (3)	C6—H6	0.9300
C1—O4	1.213 (5)	C7—N1	1.340 (6)
C1—O3	1.287 (5)	C7—H7	0.9300
C1—C3	1.534 (5)	C8—N1	1.341 (6)
C2—N3	1.341 (5)	C8—C9	1.379 (6)
C2—C5^i	1.386 (5)	C8—H8	0.9300
C2—H2	0.9300	C9—N2	1.339 (5)
C3—N3	1.328 (5)	C9—C10	1.537 (5)
C3—C4^i	1.392 (5)	C10—O2	1.220 (5)
C4—N4	1.341 (5)	C10—O1	1.281 (5)
C4—C3^ii	1.392 (5)	O5—H1W	0.82 (4)
C4—H4	0.9300	O5—H2W	0.82 (4)
O5—Zn1—O1	87.28 (11)	N2—C6—C7	120.4 (4)
O5—Zn1—O3	89.72 (11)	N2—C6—H6	119.8
O1—Zn1—O3	175.86 (11)	C7—C6—H6	119.8
O5—Zn1—N2	88.17 (12)	N1—C7—C6	121.1 (4)
O1—Zn1—N2	81.37 (12)	N1—C7—H7	119.5
O3—Zn1—N2	95.68 (12)	C6—C7—H7	119.5
O5—Zn1—N3	91.51 (12)	N1—C8—C9	121.8 (4)
O1—Zn1—N3	101.61 (12)	N1—C8—H8	119.1
O3—Zn1—N3	81.32 (11)	C9—C8—H8	119.1
N2—Zn1—N3	176.98 (13)	N2—C9—C8	120.0 (4)
O5—Zn1—N4	176.63 (14)	N2—C9—C10	118.1 (3)
O1—Zn1—N4	89.35 (12)	C8—C9—C10	121.9 (4)
O3—Zn1—N4	93.64 (11)	O2—C10—O1	125.5 (4)
N2—Zn1—N4	91.41 (12)	O2—C10—C9	120.6 (4)
N3—Zn1—N4	89.09 (11)	O1—C10—C9	113.9 (3)
O4—C1—O3	125.4 (3)	C7—N1—C8	117.6 (4)
O4—C1—C3	121.5 (3)	C6—N2—C9	119.1 (3)
O3—C1—C3	113.1 (3)	C6—N2—Zn1	130.2 (3)
N3—C2—C5^i	120.5 (4)	C9—N2—Zn1	110.3 (3)
N3—C2—H2	119.7	C3—N3—C2	119.5 (3)
C5^i—C2—H2	119.7	C3—N3—Zn1	109.8 (2)
N3—C3—C4^i	119.7 (3)	C2—N3—Zn1	130.7 (3)
N3—C3—C1	119.5 (3)	C5—N4—C4	118.1 (3)
C4^i—C3—C1	120.7 (3)	C5—N4—Zn1	122.7 (3)
N4—C4—C3^ii	121.4 (3)	C4—N4—Zn1	119.0 (2)
N4—C4—H4	119.3	C10—O1—Zn1	115.9 (2)
C3^ii—C4—H4	119.3	C1—O3—Zn1	116.0 (2)
N4—C5—C2^ii	120.7 (4)	Zn1—O5—H1W	114 (5)
N4—C5—H5	119.7	Zn1—O5—H2W	114 (5)
C2^ii—C5—H5	119.7	H1W—O5—H2W	116 (3)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H1W···O3^iii	0.82 (4)	2.08 (4)	2.781 (4)	144 (7)
O5—H2W···O1^iv	0.82 (4)	1.89 (2)	2.695 (4)	166 (8)

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