Retracted: Poly[diaqua-μ₃-malonato-μ-pyrazine-diiron(II)]

The title compound, [Fe₂(C₃H₂O₄)₂(C₄H₄N₂)(H₂O)₂]_n, prepared by hydro­thermal synthesis, is isostructural with its Co^II, Ni^II, Zn^II and Cd^II analogues. The Fe^II atoms are linked via coordinated malonates into two-dimensional sheets containing cavities. The sheets are connected by bridging pyrazine ligands which lie on centres of inversion. The coordination geometry around Fe^II is a tetra­gonally elongated octa­hedron, in which pyrazine N and aqua O atoms occupy the axial positions. The coordinated water mol­ecules form O—H...O hydrogen bonds to the malonate ligands.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.040
• wR factor = 0.106
• Data-to-parameter ratio = 11.1

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       2.00 Ratio
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.96
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         O3
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        Fe1
PLAT480_ALERT_4_C Long H...A H-Bond Reported H2W    ..  O2      ..       2.78 Ang.
PLAT482_ALERT_4_C Small D-H..A Angle Rep for O5     ..  O2      ..      99.00 Deg.
PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) .       1.20 Ratio

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K
PLAT794_ALERT_5_G Check Predicted Bond Valency for Fe1         (9)       1.69
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          3

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

   5 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 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
   4 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

The title compound is isostructural with its Co^II (Delgado et al., 2003), Ni^II (Liu et al., 2005), Zn^II (Zhang et al., 2003; Delgado et al., 2003) and Cd^II (Mao et al., 2004) analogues. The Fe^II atom exhibits sixfold coordination, chelated by two O atoms from one malonate ligand to form a six-membered boat-type ring, and by two O atoms from two neighbouring malonates, one water molecule and one N atom from the bridging pyrazine ligand (Fig. 1). The Fe—O(carboxylate) and Fe—N bond lengths are in the range 2.064 (4)–2.202 (4) and 2.272 (4) Å, respectively.

The [Fe(malonate)(H₂O)] units form two-dimensional networks parallel to the (010) planes. These are linked by the bridging pyrazine ligands into a three-dimensional structure. O—H···O hydrogen bonds (Table 1) are formed between the coordinated water molecules and the malonate ligands.

Related literature

For the isostructural analogues, see: Co^II (Delgado et al., 2003); Ni^II (Liu et al., 2005); Zn^II (Zhang et al., 2003; Delgado et al., 2003); Cd^II (Mao et al., 2004).

S2. Experimental

A mixture of FeSO₄ (0.5 mmol), malonic acid (0.5 mmol), NaOH (1 mmol), pyrazine (1 mmol) and H₂O (8 ml) in a 25 ml Teflon-lined stainless steel autoclave was heated at 443 K for two days, and then cooled to room temperature. Light green block crystals of the title compound were obtained with a yield of 22%. Elemental analysis: calculated C 27.91, H 2.79, N 6.51%; found: C 27.88, H 2.75, N 6.47%.

S3. Refinement

All H atoms on C atoms were generated geometrically and refined as riding atoms with C—H = 0.93 or 0.97 Å and with U_iso(H) = 1.2U_eq(C). The H atoms of the water molecule were located from difference Fourier maps and were refined with distance restraints of d(H—H) = 1.38 (2) Å, d(O—H) = 0.82 (1) Å.

Computing details

Data collection: APEX2 (Bruker, 2004); 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. Part of the polymeric structure of the title complex showing displacement ellipsoids at 30% probability for non-H atoms. Atoms labeled with the suffix I are generated by the symmetry operator (-x + 1, y + 1/2,-z + 3/2).
	Fig. 2. Packing diagram for the title complex viewed along the c-axis.

Poly[diaqua-µ₃-malonato-µ-pyrazine-diiron(II)]

Crystal data

[Fe2(C3H2O4)2(C4H4N2)(H2O)2]	F(000) = 436
Mr = 431.92	Dx = 1.930 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 1293 reflections
a = 6.9652 (10) Å	θ = 2.8–25.0°
b = 14.589 (2) Å	µ = 2.01 mm^−1
c = 7.3212 (10) Å	T = 293 K
β = 92.179 (1)°	Block, green
V = 743.39 (18) Å^3	0.36 × 0.28 × 0.24 mm
Z = 2

Data collection

Bruker APEXII CCD diffractometer	1293 independent reflections
Radiation source: fine-focus sealed tube	1100 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.023
φ and ω scans	θmax = 25.0°, θmin = 2.8°
Absorption correction: multi-scan (SADABS; Bruker, 2001)	h = −8→3
Tmin = 0.532, Tmax = 0.644	k = −13→16
2391 measured reflections	l = −8→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)] = 0.040	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.106	w = 1/[σ^2(Fo^2) + (0.0653P)^2 + 1.1979P] where P = (Fo^2 + 2Fc^2)/3
S = 1.00	(Δ/σ)max = 0.010
1293 reflections	Δρmax = 0.65 e Å^−3
116 parameters	Δρmin = −0.40 e Å^−3
3 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.039 (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 (Ų)

	x	y	z	Uiso*/Ueq
C1	0.5845 (6)	0.3316 (3)	0.7563 (6)	0.0316 (9)
C2	0.6129 (7)	0.3912 (3)	0.5893 (6)	0.0397 (10)
H2A	0.5238	0.4423	0.5912	0.048*
H2B	0.7422	0.4160	0.5955	0.048*
C3	0.5827 (6)	0.3401 (3)	0.4125 (6)	0.0317 (9)
C4	0.4533 (7)	0.0742 (3)	0.5913 (7)	0.0473 (12)
H4	0.4138	0.1251	0.6565	0.057*
C5	0.6788 (6)	−0.0045 (3)	0.4450 (7)	0.0437 (11)
H5	0.8030	−0.0107	0.4042	0.052*
Fe1	0.83758 (7)	0.19136 (3)	0.58103 (6)	0.0177 (3)
N1	0.6323 (5)	0.0716 (2)	0.5376 (5)	0.0357 (8)
O1	0.6634 (4)	0.2528 (2)	0.7697 (4)	0.0397 (8)
O2	0.4864 (4)	0.3672 (2)	0.8748 (4)	0.0403 (8)
O3	0.6700 (5)	0.2644 (2)	0.3900 (4)	0.0429 (8)
O4	0.4752 (4)	0.3774 (2)	0.2946 (4)	0.0393 (7)
O5	1.0315 (5)	0.3106 (2)	0.5861 (4)	0.0439 (8)
H2W	1.090 (8)	0.308 (4)	0.490 (4)	0.080*
H1W	1.101 (7)	0.298 (4)	0.677 (5)	0.080*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.034 (2)	0.029 (2)	0.032 (2)	0.0001 (18)	0.0005 (16)	−0.0053 (18)
C2	0.056 (3)	0.034 (2)	0.029 (2)	0.005 (2)	0.0022 (19)	0.0010 (19)
C3	0.036 (2)	0.028 (2)	0.032 (2)	0.0035 (18)	0.0042 (17)	0.0045 (18)
C4	0.044 (3)	0.039 (3)	0.060 (3)	−0.005 (2)	0.018 (2)	−0.014 (2)
C5	0.038 (2)	0.034 (3)	0.060 (3)	−0.002 (2)	0.012 (2)	−0.009 (2)
Fe1	0.0219 (3)	0.0169 (4)	0.0145 (3)	0.00068 (19)	0.0018 (2)	−0.00062 (19)
N1	0.0357 (18)	0.033 (2)	0.038 (2)	−0.0020 (16)	0.0017 (15)	−0.0011 (16)
O1	0.0516 (18)	0.0358 (18)	0.0325 (16)	0.0069 (14)	0.0116 (13)	0.0027 (13)
O2	0.0454 (17)	0.0379 (18)	0.0387 (17)	0.0043 (14)	0.0168 (13)	0.0000 (14)
O3	0.054 (2)	0.042 (2)	0.0325 (16)	0.0114 (15)	−0.0052 (14)	−0.0031 (14)
O4	0.0476 (17)	0.0335 (17)	0.0363 (16)	0.0027 (14)	−0.0060 (13)	0.0027 (14)
O5	0.0467 (19)	0.053 (2)	0.0325 (17)	−0.0013 (15)	0.0019 (14)	0.0000 (15)

Geometric parameters (Å, º)

C1—O2	1.239 (5)	C5—C4^i	1.390 (7)
C1—O1	1.276 (5)	C5—H5	0.930
C1—C2	1.519 (6)	Fe1—O2^ii	2.050 (3)
C2—C3	1.501 (6)	Fe1—O4^iii	2.064 (3)
C2—H2A	0.970	Fe1—O1	2.076 (3)
C2—H2B	0.970	Fe1—O3	2.081 (3)
C3—O4	1.246 (5)	Fe1—O5	2.202 (4)
C3—O3	1.275 (6)	Fe1—N1	2.272 (4)
C4—N1	1.322 (6)	O2—Fe1^iv	2.050 (3)
C4—C5^i	1.390 (7)	O4—Fe1^v	2.064 (3)
C4—H4	0.930	O5—H2W	0.83 (4)
C5—N1	1.347 (6)	O5—H1W	0.83 (4)
O2—C1—O1	124.8 (4)	O4^iii—Fe1—O3	172.32 (12)
O2—C1—C2	114.6 (4)	O1—Fe1—O3	84.20 (12)
O1—C1—C2	120.6 (4)	O2^ii—Fe1—O5	90.84 (12)
C3—C2—C1	113.1 (4)	O4^iii—Fe1—O5	95.99 (12)
C3—C2—H2A	109.0	O1—Fe1—O5	91.21 (12)
C1—C2—H2A	109.0	O3—Fe1—O5	86.27 (14)
C3—C2—H2B	109.0	O2^ii—Fe1—N1	84.81 (12)
C1—C2—H2B	109.0	O4^iii—Fe1—N1	90.23 (13)
H2A—C2—H2B	107.8	O1—Fe1—N1	92.56 (13)
O4—C3—O3	124.5 (4)	O3—Fe1—N1	88.03 (13)
O4—C3—C2	116.2 (4)	O5—Fe1—N1	172.81 (13)
O3—C3—C2	119.3 (4)	C4—N1—C5	114.9 (4)
N1—C4—C5^i	123.2 (4)	C4—N1—Fe1	122.1 (3)
N1—C4—H4	118.4	C5—N1—Fe1	122.9 (3)
C5^i—C4—H4	118.4	C1—O1—Fe1	126.8 (3)
N1—C5—C4^i	122.0 (4)	C1—O2—Fe1^iv	130.5 (3)
N1—C5—H5	119.0	C3—O3—Fe1	128.0 (3)
C4^i—C5—H5	119.0	C3—O4—Fe1^v	124.2 (3)
O2^ii—Fe1—O4^iii	97.03 (13)	Fe1—O5—H2W	106 (4)
O2^ii—Fe1—O1	173.95 (12)	Fe1—O5—H1W	100 (5)
O4^iii—Fe1—O1	88.42 (13)	H2W—O5—H1W	113 (3)
O2^ii—Fe1—O3	90.26 (13)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H2W···O1^ii	0.83 (4)	1.93 (3)	2.689 (4)	152 (6)
O5—H2W···O2^ii	0.83 (4)	2.78 (6)	3.031 (5)	99 (5)

Symmetry code: (ii) x+1/2, −y+1/2, z−1/2.