supplementary materials


bt6896 scheme

Acta Cryst. (2013). E69, m195    [ doi:10.1107/S1600536813006338 ]

catena-Poly[[bis(2-chloropyrazine-[kappa]N4)cadmium]-di-[mu]-thiocyanato-[kappa]2N:S;[kappa]2S:N]

S. Wöhlert, I. Jess and C. Näther

Abstract top

Reaction of cadmium thiocyanate with 2-chloropyrazine leads to the polymeric title compound, [Cd(NCS)2(C4H3ClN2)2]n. The CdII cation, which is located on a center of inversion, is coordinated by two N-bonded and two S-bonded thiocyanate anions and by two N-bonded 2-chloropyrazine ligands within a slightly distorted octahedron. The CdII cations are linked into chains along the a axis by bridging thiocyanate anions.

Comment top

Recently we have reported on the synthesis and characterization of cadmium(II) thiocyanato coordination polymers with different neutral N-donor co-ligands. For [Cd(NCS)2(4-ethylpyridine)2]n a one-dimensional structure was observed, in which the metal cations are octahedrally coordinated by two N and two S atoms of the thiocyanato anions and two N atoms of the co-ligands all of them in an all-trans coordination (Wöhlert et al., 2013). In contrast, for [Cd(NCS)2(pyridine)2]n, three different modifications were obtained in which the anionic ligands are all-trans, all-cis or cis-cis-trans coordinated (Wöhlert et al., 2012). To investigate the influence of the neutral co-ligand in more detail, 2-chloropyrazine was selected, which can act as a bidentate as well as a monodentate ligand. Therefore, cadmium(II) thiocyanate was reacted with 2-chloropyrazine in water which results in the formation of single crystals suitable for structure determination.

The crystal structure of [Cd(NCS)2(2-chloropyrazine)2]n consists of cadmium(II) cations that are located on centers of inversion as well as of thiocyanato anions and 2-chloropyrazine ligand in general position. Each cadmium(II) cation is coordinated by two N-bonded and two S-bonded thiocyanato anions as well as two 2-chloropyrazine ligands within a slightly distorted octahedral geometry (Fig. 1). The CdN4S2 distances ranges from 2.287 (3) Å to 2.7071 (9) Å with angles arround the cadmium(II) cation between 87.75 (8) ° to 92.25 (8) ° and of 180 ° (Tab. 1). In the crystal structure the cadmium(II) cations are connected through µ-1,3 bridging thiocyanato anions into one-dimensional polymeric chains, in which all thiocyanato anions and the 2-chloropyrazine ligand are trans-coordinated (Fig. 2). The intrachain cadmium-cadmium separation amounts to 5.7151 (6) Å, whereas the shortest interchain Cd—Cd distance is 11.2915 (13) Å. This structural motiv is frequently found in cadmium thiocyanato coordination compounds and might represent the most stable coordination. However, in this context it is noted that for [Cd(NCS)2(pyridine)2]n, the form with a cis-cis-trans coordination represents the thermodynamic stable form at room-temperature and this might be an exception (Wöhlert et al., 2012).

Related literature top

For the background to this work and the synthesis of bridging thiocyanato coordination polymers see Wöhlert et al. (2012, 2013).

Experimental top

CdSO4x8/3H2O, Ba(NCS)2x3H2O and 2-chloropyrazine were obtained from Alfa Aesar. All chemicals were used without further purification. Cd(NCS)2 was prepared by the reaction of equimolar amounts of CdSO4x8/3H2O with Ba(NCS)2x3H2O in water. The resulting precipitate of BaSO4 were filtered off and the filtrate were concentrated to complete dryness resulting in white residues of Cd(NCS)2. The purity was checked by XRPD and CHNS analysis. 0.1 mmol (22.0 mg) Cd(NCS)2 and 0.4 mmol (32.0 µL) 2-chloropyrazine were reacted in 1 ml water. Colorless single crystals of the title compound were obtained after three days.

Refinement top

All H atoms were located in difference map but were positioned with idealized geometry and were refined isotropic with Uiso(H) = 1.2 Ueq(C) using a riding model with C—H = 0.93 Å.

Computing details top

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, 2011); software used to prepare material for publication: XCIF in SHELXTL (Sheldrick, 2008) and publCIF (Westrip, 2010).

Figures top
[Figure 1] 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 + 1, -z; ii = x - 1, y, z; iii = -x + 2, -y + 1, -z.
[Figure 2] Fig. 2. : Crystal structure of the title compound with view along the b-axis (orange = cadmium, blue = nitrogen, yellow = sulfur, green = chloro, grey = carbon, white = hydrogen).
catena-Poly[[bis(2-chloropyrazine-κN4)cadmium]-di-µ-thiocyanato-κ2N:S;κ2S:N] top
Crystal data top
[Cd(NCS)2(C4H3ClN2)2]Z = 1
Mr = 457.63F(000) = 222
Triclinic, P1Dx = 1.873 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 5.7151 (6) ÅCell parameters from 5777 reflections
b = 6.7625 (8) Åθ = 1.9–26.0°
c = 11.2915 (13) ŵ = 1.93 mm1
α = 76.895 (9)°T = 293 K
β = 82.639 (9)°Block, colourless
γ = 73.068 (8)°0.17 × 0.15 × 0.10 mm
V = 405.70 (8) Å3
Data collection top
Stoe IPDS-2
diffractometer
1592 independent reflections
Radiation source: fine-focus sealed tube1492 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.068
ω scanθmax = 26.0°, θmin = 1.9°
Absorption correction: numerical
(X-SHAPE and X-RED32; Stoe & Cie, 2008)
h = 77
Tmin = 0.551, Tmax = 0.719k = 88
5777 measured reflectionsl = 1313
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.029Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.072H-atom parameters constrained
S = 1.02 w = 1/[σ2(Fo2) + (0.0411P)2]
where P = (Fo2 + 2Fc2)/3
1592 reflections(Δ/σ)max < 0.001
97 parametersΔρmax = 0.56 e Å3
0 restraintsΔρmin = 0.49 e Å3
Crystal data top
[Cd(NCS)2(C4H3ClN2)2]γ = 73.068 (8)°
Mr = 457.63V = 405.70 (8) Å3
Triclinic, P1Z = 1
a = 5.7151 (6) ÅMo Kα radiation
b = 6.7625 (8) ŵ = 1.93 mm1
c = 11.2915 (13) ÅT = 293 K
α = 76.895 (9)°0.17 × 0.15 × 0.10 mm
β = 82.639 (9)°
Data collection top
Stoe IPDS-2
diffractometer
1592 independent reflections
Absorption correction: numerical
(X-SHAPE and X-RED32; Stoe & Cie, 2008)
1492 reflections with I > 2σ(I)
Tmin = 0.551, Tmax = 0.719Rint = 0.068
5777 measured reflectionsθmax = 26.0°
Refinement top
R[F2 > 2σ(F2)] = 0.029H-atom parameters constrained
wR(F2) = 0.072Δρmax = 0.56 e Å3
S = 1.02Δρmin = 0.49 e Å3
1592 reflectionsAbsolute structure: ?
97 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

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 (Å2) top
xyzUiso*/Ueq
Cd10.50000.50000.00000.04055 (12)
N10.7466 (5)0.7003 (4)0.0217 (3)0.0512 (6)
N120.6360 (5)0.2497 (4)0.1840 (2)0.0457 (6)
C120.5473 (6)0.0818 (5)0.2234 (3)0.0485 (7)
H120.43400.05910.17940.058*
C110.6252 (7)0.0574 (5)0.3298 (3)0.0502 (8)
C140.8718 (8)0.1294 (6)0.3560 (3)0.0623 (9)
H140.98560.15020.40050.075*
C130.8027 (7)0.2699 (6)0.2508 (3)0.0545 (8)
H130.87260.38190.22470.065*
N110.7817 (7)0.0377 (5)0.3977 (3)0.0590 (7)
Cl110.5080 (2)0.27337 (15)0.37726 (10)0.0755 (3)
S11.14072 (16)0.73906 (13)0.12925 (8)0.0535 (2)
C10.9108 (6)0.7182 (4)0.0647 (3)0.0404 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cd10.03692 (19)0.04198 (17)0.04287 (19)0.01361 (12)0.01125 (13)0.00014 (12)
N10.0460 (16)0.0474 (13)0.0632 (17)0.0154 (12)0.0118 (13)0.0089 (12)
N120.0451 (15)0.0484 (13)0.0416 (14)0.0117 (11)0.0087 (11)0.0031 (11)
C120.0487 (18)0.0482 (15)0.0459 (16)0.0095 (13)0.0086 (14)0.0057 (13)
C110.060 (2)0.0455 (15)0.0418 (16)0.0124 (14)0.0037 (15)0.0052 (12)
C140.071 (3)0.071 (2)0.0480 (18)0.0249 (19)0.0237 (18)0.0015 (16)
C130.059 (2)0.0546 (17)0.0511 (19)0.0204 (15)0.0145 (16)0.0011 (14)
N110.072 (2)0.0601 (16)0.0431 (14)0.0183 (15)0.0143 (14)0.0004 (12)
Cl110.1033 (9)0.0591 (5)0.0665 (6)0.0365 (5)0.0086 (6)0.0031 (4)
S10.0426 (5)0.0638 (5)0.0620 (5)0.0142 (4)0.0100 (4)0.0250 (4)
C10.0381 (16)0.0394 (13)0.0452 (16)0.0123 (11)0.0033 (13)0.0088 (12)
Geometric parameters (Å, º) top
Cd1—N12.287 (3)C12—H120.9300
Cd1—N1i2.287 (3)C11—N111.303 (5)
Cd1—N12i2.417 (2)C11—Cl111.730 (3)
Cd1—N122.417 (2)C14—N111.341 (5)
Cd1—S1ii2.7071 (9)C14—C131.364 (5)
Cd1—S1iii2.7071 (9)C14—H140.9300
N1—C11.158 (4)C13—H130.9300
N12—C121.338 (4)S1—C11.636 (3)
N12—C131.342 (4)S1—Cd1iv2.7071 (9)
C12—C111.381 (4)
N1—Cd1—N1i180.0C12—N12—Cd1120.7 (2)
N1—Cd1—N12i88.62 (10)C13—N12—Cd1122.4 (2)
N1i—Cd1—N12i91.38 (10)N12—C12—C11119.6 (3)
N1—Cd1—N1291.38 (10)N12—C12—H12120.2
N1i—Cd1—N1288.62 (10)C11—C12—H12120.2
N12i—Cd1—N12180.00 (15)N11—C11—C12124.5 (3)
N1—Cd1—S1ii92.25 (8)N11—C11—Cl11117.2 (2)
N1i—Cd1—S1ii87.75 (8)C12—C11—Cl11118.2 (3)
N12i—Cd1—S1ii91.06 (7)N11—C14—C13122.5 (4)
N12—Cd1—S1ii88.94 (7)N11—C14—H14118.7
N1—Cd1—S1iii87.75 (8)C13—C14—H14118.7
N1i—Cd1—S1iii92.25 (8)N12—C13—C14121.3 (3)
N12i—Cd1—S1iii88.94 (7)N12—C13—H13119.4
N12—Cd1—S1iii91.06 (7)C14—C13—H13119.4
S1ii—Cd1—S1iii180.00 (4)C11—N11—C14115.1 (3)
C1—N1—Cd1150.2 (2)C1—S1—Cd1iv96.53 (11)
C12—N12—C13116.9 (3)N1—C1—S1178.3 (3)
Symmetry codes: (i) x+1, y+1, z; (ii) x+2, y+1, z; (iii) x1, y, z; (iv) x+1, y, z.
Selected bond lengths (Å) top
Cd1—N12.287 (3)Cd1—S1i2.7071 (9)
Cd1—N122.417 (2)
Symmetry code: (i) x1, y, z.
Acknowledgements top

We gratefully acknowledge financial support by the DFG (project No. NA 720/3–1) and the State of Schleswig–Holstein. We thank Professor Dr Wolfgang Bensch for access to his experimental facility.

references
References top

Brandenburg, K. (2011). DIAMOND. Crystal Impact GbR, Bonn, Germany.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.

Stoe & Cie (2008). X-AREA, X-RED32 and X-SHAPE. Stoe & Cie, Darmstadt, Germany.

Westrip, S. P. (2010). J. Appl. Cryst. 43, 920–925.

Wöhlert, S., Boeckmann, J., Jess, I. & Näther, C. (2012). CrystEngComm, 14, 5412–5420.

Wöhlert, S., Jess, I. & Näther, C. (2013). Z. Anorg. Allg. Chem. 639, 385–391.