Retracted: Tetra­kis(pyrazine-κN)bis­(thio­cyanato-κN)manganese(II)

In the mol­ecule of the title complex, [Mn(NCS)₂(C₄H₄N₂)₄], the Mn^II atom is coordinated in a distorted octa­hedral arrangement by two N atoms of two SCN⁻ and four N atoms of four pyrazine ligands. A crystallographic twofold rotation axis passes through the Mn atom, and the N and para-N atoms of two trans pyrazine rings. In the crystal structure, the non-classical hydrogen bonds and the weak π–π stacking inter­actions, involving the pyrazine rings of adjacent pyrazine ligands with a centroid–centroid distance of 3.3205 (4) Å, contribute to the formation of a supra­molecular network structure.

Key indicators

• Single-crystal X-ray study
• T = 273 K
• Mean [sigma](C-C) = 0.007 Å
• R factor = 0.050
• wR factor = 0.159
• Data-to-parameter ratio = 16.9

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT242_ALERT_2_B Check Low       Ueq as Compared to Neighbors for         C1

Alert level C
PLAT230_ALERT_2_C Hirshfeld Test Diff for    N7     -   C3      ..       6.29 su
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Mn1    -   N1      ..       8.69 su
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Mn1    -   N3      ..       8.15 su
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         N1
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         N6
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for        Mn1
PLAT341_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          7

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for Mn1         (3)       2.52

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   7 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
   7 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
   0 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

There are three manganese enzymes containing a mononuclear manganese site, viz. superoxide dismutase, peroxidase and dioxygenase, which participate in redox changes in the respective areas of biology (Law et al., 1999). Carboxylatobridged complexes, such as pyridine, phenanthroline, quinoline and benzimidazole, are often employed to mimic the function and structure of these active sites, based on the knowledge that Mn centres in these enzymes are predominately coordinated by N,O donors from available amino acid side chains (Pecoraro & Butler, 1986; Wu et al., 2003; Pan & Xu, 2004; Liu et al., 2004; Li et al., 2005). We herein report the crystal structure of the title compound, (I).

In the molecule of (I), (Fig. 1) the ligand bond lengths and angles are within normal ranges (Allen et al., 1987). The two N atoms of two SCN^- and four N atoms of four pyrazine ligands are coordinated to the Mn atom, in a distorted octahedral arrangement (Table 1). A crystallographic twofold rotation axis passes through the Mn atom, and the N and para-N atoms of two trans pyrazine rings. The planar pyrazine rings I (N3/N6/C4—C7), II (N2/N7/C2A/C3A/C2—C3) and III (N4/N5/C8A/C9A/C8—C9) are nearly perpendicular to each other, with dihedral angles of I/II = 87.7 (2), I/III = 109.2 (6) and II/III = 85.9 (7)°.

In the crystal structure, the non-classical hydrogen bonds and the weak π-π stacking interactions, involving the pyrazine rings of adjacent pyrazine ligands with centroid-centroid distance of 3.3205 (4) Å [symmetry code: 1 - x, 2 - y, 1 - z], cause to the formation of a supramolecular network structure (Fig. 2).

Related literature

For related literature, see: Allen et al. (1987); Law et al. (1999); Li et al. (2005); Liu et al. (2004); Pan & Xu (2004); Pecoraro & Butler (1986); Wu et al. (2003).

S2. Experimental

Crystals of the title compound were synthesized using hydrothermal method in a Teflon-lined Parr bomb (23 ml), which was then sealed. Manganese(II) chloride tetrahydrate (39.6 mg, 0.2 mmol), potassium thiocyanate (38.9 mg, 0.4 mmol), pyrazine (1.5 ml), and distilled water (2 g) were placed into the bomb and sealed. The bomb was heated under autogenous pressure for 6 d at 413 K and allowed to cool at room temperature for 24 h. Upon opening the bomb, a clear colourless solution was decanted from small yellow crystals. These crystals were washed with distilled water followed by ethanol, and allowed to air-dry at room temperature.

S3. Refinement

H atoms were positioned geometrically, with C—H = 0.93 Å for aromatic H and constrained to ride on their parent atoms, with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Siemens, 1996); software used to prepare material for publication: SHELXTL.

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 code (A): - x, y, 3/2 - z].
	Fig. 2. A packing diagram for (I).

Tetrakis(pyrazine-κN)bis(thiocyanato-κN)manganese(II)

Crystal data

[Mn(NCS)2(C4H4N2)4]	F(000) = 1004
Mr = 491.47	Dx = 1.308 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 2231 reflections
a = 11.425 (5) Å	θ = 2.3–23.8°
b = 14.543 (4) Å	µ = 0.72 mm^−1
c = 15.022 (3) Å	T = 273 K
β = 90.759 (5)°	Block, yellow
V = 2495.7 (15) Å^3	0.26 × 0.16 × 0.07 mm
Z = 4

Data collection

Bruker APEXII area-detector diffractometer	2434 independent reflections
Radiation source: fine-focus sealed tube	1675 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.033
φ and ω scans	θmax = 26.0°, θmin = 2.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −14→13
Tmin = 0.836, Tmax = 0.952	k = −17→17
7912 measured reflections	l = −18→18

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)] = 0.050	H-atom parameters constrained
wR(F^2) = 0.159	w = 1/[σ^2(Fo^2) + (0.1074P)^2 + 0.9725P] where P = (Fo^2 + 2Fc^2)/3
S = 1.09	(Δ/σ)max < 0.001
2434 reflections	Δρmax = 0.52 e Å^−3
144 parameters	Δρmin = −0.39 e Å^−3
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0113 (16)

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
Mn1	0.0000	0.35963 (4)	0.7500	0.0486 (3)
S1	−0.36253 (15)	0.36697 (11)	0.93412 (13)	0.1233 (6)
N1	−0.1575 (3)	0.3629 (2)	0.8242 (3)	0.0787 (10)
N2	0.0000	0.2153 (3)	0.7500	0.0686 (11)
N3	0.1076 (3)	0.3603 (2)	0.8756 (2)	0.0694 (8)
N4	0.0000	0.5066 (3)	0.7500	0.0700 (11)
N5	0.0000	0.6957 (5)	0.7500	0.150 (3)
N6	0.2516 (6)	0.3887 (4)	1.0292 (5)	0.142 (2)
N7	0.0000	0.0280 (5)	0.7500	0.131 (2)
C1	−0.2437 (3)	0.3646 (2)	0.8699 (3)	0.0663 (10)
C2	−0.0418 (4)	0.1680 (3)	0.8208 (3)	0.0785 (11)
H2	−0.0706	0.2007	0.8691	0.094*
C3	−0.0430 (5)	0.0761 (3)	0.8235 (3)	0.0957 (14)
H3	−0.0716	0.0449	0.8727	0.115*
C4	0.2251 (4)	0.3423 (3)	0.8760 (3)	0.0892 (13)
H4	0.2572	0.3205	0.8234	0.107*
C5	0.3009 (5)	0.3539 (4)	0.9491 (5)	0.1116 (19)
H5	0.3801	0.3396	0.9456	0.134*
C6	0.1327 (7)	0.4051 (5)	1.0275 (4)	0.140 (3)
H6	0.0974	0.4267	1.0788	0.168*
C7	0.0637 (5)	0.3904 (4)	0.9517 (3)	0.1084 (17)
H7	−0.0162	0.4022	0.9545	0.130*
C8	0.0981 (4)	0.5541 (3)	0.7764 (3)	0.0853 (12)
H8	0.1652	0.5214	0.7923	0.102*
C9	0.1006 (5)	0.6463 (3)	0.7802 (5)	0.112 (2)
H9	0.1663	0.6771	0.8020	0.134*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Mn1	0.0436 (5)	0.0510 (5)	0.0515 (5)	0.000	0.0112 (3)	0.000
S1	0.0995 (11)	0.1354 (13)	0.1366 (14)	0.0019 (8)	0.0649 (10)	0.0009 (9)
N1	0.071 (2)	0.086 (3)	0.079 (2)	0.0017 (16)	0.0187 (17)	−0.0001 (17)
N2	0.074 (3)	0.065 (3)	0.067 (3)	0.000	0.005 (2)	0.000
N3	0.068 (2)	0.0669 (19)	0.074 (2)	0.0020 (15)	0.0040 (15)	−0.0021 (15)
N4	0.064 (3)	0.063 (3)	0.084 (3)	0.000	0.004 (2)	0.000
N5	0.142 (7)	0.086 (5)	0.220 (9)	0.000	−0.020 (6)	0.000
N6	0.148 (5)	0.141 (4)	0.134 (5)	0.002 (4)	−0.031 (4)	−0.020 (4)
N7	0.165 (7)	0.088 (4)	0.140 (6)	0.000	−0.015 (5)	0.000
C1	0.064 (2)	0.065 (2)	0.070 (2)	0.0039 (17)	0.0125 (17)	−0.0001 (17)
C2	0.087 (3)	0.070 (2)	0.078 (3)	−0.006 (2)	0.005 (2)	0.009 (2)
C3	0.127 (4)	0.071 (3)	0.089 (3)	−0.007 (3)	0.001 (3)	0.008 (2)
C4	0.071 (3)	0.107 (4)	0.090 (3)	0.012 (2)	0.001 (2)	0.015 (2)
C5	0.076 (3)	0.130 (5)	0.127 (5)	−0.001 (3)	−0.019 (3)	0.026 (4)
C6	0.129 (5)	0.188 (7)	0.101 (4)	0.048 (5)	−0.033 (4)	−0.042 (4)
C7	0.094 (3)	0.154 (5)	0.078 (3)	0.028 (3)	−0.008 (2)	−0.031 (3)
C8	0.074 (3)	0.071 (3)	0.111 (3)	−0.009 (2)	−0.003 (2)	0.005 (2)
C9	0.094 (4)	0.070 (3)	0.171 (6)	−0.010 (3)	−0.025 (4)	0.000 (3)

Geometric parameters (Å, º)

Mn1—N1	2.130 (4)	N6—C6	1.378 (8)
Mn1—N2	2.100 (4)	N6—C5	1.428 (9)
Mn1—N3	2.239 (3)	N7—C3^i	1.401 (6)
Mn1—N4	2.137 (4)	N7—C3	1.401 (6)
Mn1—N1^i	2.130 (4)	C2—C3	1.338 (6)
Mn1—N3^i	2.239 (3)	C2—H2	0.9300
S1—C1	1.676 (4)	C3—H3	0.9300
N1—C1	1.209 (6)	C4—C5	1.400 (7)
N2—C2^i	1.359 (5)	C4—H4	0.9300
N2—C2	1.359 (5)	C5—H5	0.9300
N3—C7	1.328 (6)	C6—C7	1.393 (7)
N3—C4	1.368 (5)	C6—H6	0.9300
N4—C8	1.371 (5)	C7—H7	0.9300
N4—C8^i	1.371 (5)	C8—C9	1.342 (6)
N5—C9	1.424 (6)	C8—H8	0.9300
N5—C9^i	1.424 (6)	C9—H9	0.9300
N1—Mn1—N2	91.29 (9)	C3^i—N7—C3	120.2 (6)
N1—Mn1—N3	90.98 (14)	N1—C1—S1	179.5 (4)
N1—Mn1—N4	88.71 (9)	C3—C2—N2	122.2 (4)
N2—Mn1—N3	90.26 (8)	C3—C2—H2	118.9
N2—Mn1—N4	180.000 (1)	N2—C2—H2	118.9
N3—Mn1—N4	89.74 (8)	C2—C3—N7	118.1 (5)
N2—Mn1—N1^i	91.29 (9)	C2—C3—H3	121.0
N1^i—Mn1—N1	177.42 (19)	N7—C3—H3	121.0
N1^i—Mn1—N4	88.71 (9)	N3—C4—C5	125.2 (5)
N1^i—Mn1—N3	89.01 (14)	N3—C4—H4	117.4
N2—Mn1—N3^i	90.26 (8)	C5—C4—H4	117.4
N1^i—Mn1—N3^i	90.98 (14)	C4—C5—N6	117.2 (5)
N1—Mn1—N3^i	89.01 (14)	C4—C5—H5	121.4
N4—Mn1—N3^i	89.74 (8)	N6—C5—H5	121.4
N3—Mn1—N3^i	179.48 (15)	N6—C6—C7	122.4 (6)
C1—N1—Mn1	176.9 (4)	N6—C6—H6	118.8
C2^i—N2—C2	119.2 (5)	C7—C6—H6	118.8
C2^i—N2—Mn1	120.4 (3)	N3—C7—C6	122.5 (5)
C2—N2—Mn1	120.4 (3)	N3—C7—H7	118.8
C7—N3—C4	116.3 (4)	C6—C7—H7	118.8
C7—N3—Mn1	121.1 (3)	C9—C8—N4	122.2 (5)
C4—N3—Mn1	122.0 (3)	C9—C8—H8	118.9
C8—N4—C8^i	119.4 (5)	N4—C8—H8	118.9
C8—N4—Mn1	120.3 (2)	C8—C9—N5	118.3 (5)
C8^i—N4—Mn1	120.3 (2)	C8—C9—H9	120.9
C9—N5—C9^i	119.4 (6)	N5—C9—H9	120.9
C6—N6—C5	116.5 (5)

Symmetry code: (i) −x, y, −z+3/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···N1^i	0.93	2.55	3.109 (6)	119
C7—H7···N1	0.93	2.58	3.176 (6)	122

Symmetry code: (i) −x, y, −z+3/2.