catena-Poly[[bis­(thio­cyanato-κN)iron(II)]-bis­(μ-dipyrazin-2-yl di­sulfide-κ²N⁴:N^4′)]

In the title compound, [Fe(NCS)₂(C₈H₆N₄S₂)₂]_n, the Fe^II cation is coordinated by two terminal N-bonded thio­cyanate anions and four bridging N:N′-bridging dipyrazin-2-yl di­sulfide ligands in an octa­hedral geometry. The Fe^II cations are connected via bridging 4,4′-di­pyrazine ligands into chains along the b-axis direction. The asymmetric unit consists of one Fe^II cation located on position with site symmetry 2/m, one thio­cyanate anion located on a mirror plane and one di­sulfide ligand located on a twofold rotation axis.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.051
• wR factor = 0.113
• Data-to-parameter ratio = 14.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT094_ALERT_2_C Ratio of Maximum / Minimum Residual Density ....       2.04
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C1
PLAT906_ALERT_3_C Large K value in the Analysis of Variance ......     12.309
PLAT906_ALERT_3_C Large K value in the Analysis of Variance ......      2.329
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          2
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         15
PLAT913_ALERT_3_C Missing # of Very Strong Reflections in FCF ....         10

Alert level G
PLAT004_ALERT_5_G Info: Polymeric Structure Found with Dimension .          1
PLAT005_ALERT_5_G No _iucr_refine_instructions_details  in the CIF          ? Do !
PLAT083_ALERT_2_G SHELXL Second Parameter in WGHT Unusually Large.       5.36
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported   _diffrn_ambient_temperature        293 K

   0 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   7 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   5 ALERT level G = General information/check it is not something unexpected

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   5 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   2 ALERT type 5 Informative message, check

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S1. Comment

This work is part of a project on the synthesis and characterization of new coordination compounds based on transition metal thiocyanates and different N-donor ligand (Wriedt & Näther, 2011). Crystals of the title compound were obtained by accident in the reaction of iron(II) sulfate heptahydrate with potassium thiocyanate and 2-chloropyrazine. To identify the product of this reaction a structure determination was performed.

In the crystal structure of the title compound each iron(II) cation is octahedrally coordinated by two terminal N-bonded thiocyanato anions and four bridging dipyrazine-disulfide ligands that has accidently formed in the reaction (Fig. 1 and Tab. 1). The Fe—NCS distances of 2.061 (4) Å and the Fe—N(dipyrazine-disulfide) distances of 2.273 (3) Å are in the normal range (Tab. 1). The Fe^II cations are located on position 2/m, the thiocyanato anions on a mirror plane and the dipyrazine-disulfide ligands on a 2-fold axis (Fig. 1). The iron(II) cations are linked into chains by the dipyrazine-disulfide ligands that elongate in the direction of the crystallographic b-axis (Fig. 2). It must be noted that according to a search in the CCDC database such compounds with dipyrazine-disulfide are unknown (ConQuest Ver. 1.14 2012, Allen, 2002).

Related literature

For general background to this work, see: Wriedt & Näther (2011). For a description of the Cambridge Structural Database, see: Allen (2002).

S2. Experimental

FeSO₄.7H₂O and 2-chloropyrazine were obtained from Sigma Aldrich. KNCS was obtained from Alfa Aesar. 0.6 mmol (168.8 mg) FeSO₄.7H₂O, 1.2 mmol (118.5 mg) KNCS and 0.15 mmol (13.2 µL) 2-chloropyrazine were reacted with 1 mL H₂O in a closed test-tube at 120°C for three days. On cooling red block-shaped single crystals of the title compound has formed.

S3. Refinement

All H atoms were located in difference map but were positioned with idealized geometry and were refined isotropic with U_iso(H) = 1.2 U_eq(C) of the parent atom using a riding model with C—H = 0.93 Å.

Computing details

Data collection: X-AREA (Stoe & Cie, 2008); cell refinement: X-AREA (Stoe & Cie, 2008); data reduction: X-AREA (Stoe & Cie, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 2012); software used to prepare material for publication: XCIF in SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. Crystal structure of the title compound with labeling and displacement ellipsoids drawn at the 50% probability level. Symmetry code: i = -x + 1, -y, -z + 1; ii = x, -y, -z + 1; iii = -x + 1, y, z; iv = x, -y + 1, -z + 1.
	Fig. 2. View of the chains that elongate in the direction of the crystallographic b axis.

catena-Poly[[bis(thiocyanato-κN)iron(II)]-bis(µ-dipyrazin-2-yl disulfide-κ²N⁴:N^4')]

Crystal data

[Fe(NCS)2(C8H6N4S2)2]	F(000) = 1248
Mr = 616.59	Dx = 1.648 Mg m^−3
Orthorhombic, Cmca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2bc 2	Cell parameters from 7765 reflections
a = 19.053 (1) Å	θ = 3.0–26.0°
b = 8.0559 (5) Å	µ = 1.14 mm^−1
c = 16.1952 (9) Å	T = 293 K
V = 2485.8 (2) Å^3	Block, red
Z = 4	0.11 × 0.08 × 0.05 mm

Data collection

Stoe IPDS-2 diffractometer	1242 independent reflections
Radiation source: fine-focus sealed tube	1077 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.035
ω scan	θmax = 26.0°, θmin = 3.0°
Absorption correction: numerical (X-SHAPE and X-RED32; Stoe & Cie, 2008)	h = −23→21
Tmin = 0.782, Tmax = 0.902	k = −9→9
7765 measured reflections	l = −19→17

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.051	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.113	H-atom parameters constrained
S = 1.15	w = 1/[σ^2(Fo^2) + (0.0413P)^2 + 5.3642P] where P = (Fo^2 + 2Fc^2)/3
1242 reflections	(Δ/σ)max < 0.001
86 parameters	Δρmax = 0.69 e Å^−3
0 restraints	Δρmin = −0.34 e Å^−3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
Fe1	0.5000	0.0000	0.5000	0.0384 (3)
N1	0.5000	0.1936 (5)	0.5832 (3)	0.0507 (10)
C1	0.5000	0.3240 (5)	0.6134 (3)	0.0397 (10)
S1	0.5000	0.50646 (16)	0.65366 (9)	0.0640 (4)
N10	0.41517 (13)	0.1291 (3)	0.42501 (17)	0.0428 (6)
C10	0.37695 (15)	0.2524 (4)	0.4557 (2)	0.0445 (7)
H10	0.3819	0.2818	0.5109	0.053*
C11	0.32962 (17)	0.3380 (4)	0.4062 (2)	0.0490 (8)
C12	0.3600 (2)	0.1830 (6)	0.2972 (2)	0.0713 (11)
H12	0.3561	0.1563	0.2415	0.086*
C13	0.4057 (2)	0.0943 (5)	0.3454 (2)	0.0579 (9)
H13	0.4309	0.0073	0.3219	0.070*
N11	0.32128 (18)	0.3053 (4)	0.3271 (2)	0.0649 (9)
S11	0.27348 (5)	0.50102 (12)	0.43778 (8)	0.0687 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Fe1	0.0371 (5)	0.0304 (4)	0.0478 (5)	0.000	0.000	−0.0021 (4)
N1	0.053 (2)	0.039 (2)	0.060 (2)	0.000	0.000	−0.0075 (19)
C1	0.037 (2)	0.041 (2)	0.041 (2)	0.000	0.000	0.0057 (19)
S1	0.0814 (10)	0.0398 (7)	0.0709 (9)	0.000	0.000	−0.0098 (6)
N10	0.0386 (14)	0.0393 (13)	0.0505 (15)	0.0010 (11)	0.0018 (12)	0.0033 (11)
C10	0.0367 (15)	0.0400 (16)	0.0567 (18)	0.0007 (13)	−0.0023 (15)	0.0000 (14)
C11	0.0394 (17)	0.0375 (16)	0.070 (2)	−0.0023 (13)	−0.0072 (16)	0.0005 (15)
C12	0.080 (3)	0.079 (3)	0.055 (2)	0.011 (2)	−0.010 (2)	−0.005 (2)
C13	0.060 (2)	0.057 (2)	0.056 (2)	0.0099 (18)	−0.0037 (18)	−0.0035 (17)
N11	0.065 (2)	0.0616 (19)	0.068 (2)	0.0059 (16)	−0.0192 (17)	0.0015 (16)
S11	0.0492 (5)	0.0527 (5)	0.1041 (8)	0.0138 (4)	−0.0205 (5)	−0.0146 (6)

Geometric parameters (Å, º)

Fe1—N1^i	2.061 (4)	C10—C11	1.390 (4)
Fe1—N1	2.061 (4)	C10—H10	0.9300
Fe1—N10	2.273 (3)	C11—N11	1.318 (5)
Fe1—N10^ii	2.273 (3)	C11—S11	1.769 (3)
Fe1—N10^iii	2.273 (3)	C12—N11	1.323 (5)
Fe1—N10^i	2.273 (3)	C12—C13	1.371 (5)
N1—C1	1.158 (6)	C12—H12	0.9300
C1—S1	1.608 (5)	C13—H13	0.9300
N10—C10	1.328 (4)	S11—S11^iv	2.015 (2)
N10—C13	1.332 (5)
N1^i—Fe1—N1	180.00 (18)	C10—N10—C13	116.5 (3)
N1^i—Fe1—N10	89.81 (11)	C10—N10—Fe1	122.1 (2)
N1—Fe1—N10	90.19 (11)	C13—N10—Fe1	121.1 (2)
N1^i—Fe1—N10^ii	89.81 (11)	N10—C10—C11	120.7 (3)
N1—Fe1—N10^ii	90.19 (11)	N10—C10—H10	119.6
N10—Fe1—N10^ii	90.62 (13)	C11—C10—H10	119.6
N1^i—Fe1—N10^iii	90.19 (11)	N11—C11—C10	122.7 (3)
N1—Fe1—N10^iii	89.81 (11)	N11—C11—S11	110.9 (3)
N10—Fe1—N10^iii	89.38 (13)	C10—C11—S11	126.4 (3)
N10^ii—Fe1—N10^iii	180.0	N11—C12—C13	122.3 (4)
N1^i—Fe1—N10^i	90.19 (11)	N11—C12—H12	118.9
N1—Fe1—N10^i	89.81 (11)	C13—C12—H12	118.9
N10—Fe1—N10^i	180.00 (11)	N10—C13—C12	121.8 (4)
N10^ii—Fe1—N10^i	89.38 (13)	N10—C13—H13	119.1
N10^iii—Fe1—N10^i	90.62 (13)	C12—C13—H13	119.1
C1—N1—Fe1	164.1 (4)	C11—N11—C12	116.0 (3)
N1—C1—S1	179.0 (4)	C11—S11—S11^iv	106.45 (13)

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