Poly[bis­(μ₂-1,3-phenyl­enedi­amine-κ² N:N′)di-μ-thio­cyanato-κ² N:S;κ² S:N-cadmium]

Abstract

The structure of the title polymeric compound, [Cd(SCN)₂(C₆H₈N₂)₂]_n, exhibits a two-dimensional staircase-like structure parallel to (010) in which the Cd^II atom lies on a twofold rotation axis and has a distorted octa­hedral CdS₂N₄ geometry involving four μ-1,3-(SCN) group donors and two N-atom donors from 1,3-phenyl­enedi­amine ligands, which also have twofold symmetry. The major contributions to the cohesion and the stability of this two-dimensional polymeric structure are the covalent Cd—S,N bonds and one weak intra­layer N—H⋯S hydrogen bond.

Related literature  

For related structures, see: MacGillivary et al. (1994 ▶); Fujita et al. (1995 ▶); Blake et al. (1997 ▶); Withersby et al. (1997 ▶); Tong et al. (1998 ▶); Yang et al. (2001 ▶); Chemli et al. (2013 ▶). For the HSCN synthesis, see: Bartlett et al. (1969 ▶). For the effects of substituents on the inter­nal angles of the phenyl ring, see: Domenicano & Murray-Rust (1979 ▶). For NLO and luminescence of related compounds, see: Chen et al. (2000 ▶); Bai et al. (2011 ▶). For electric and dielectric properties of related compounds, see: Karoui et al. (2013 ▶).

Experimental  

Crystal data  

• [Cd(NCS)₂(C₆H₈N₂)₂]

• M _r = 336.7

• Monoclinic,

• a = 10.8704 (6) Å

• b = 12.8983 (10) Å

• c = 8.3362 (5) Å

• β = 106.503 (3)°

• V = 1120.67 (13) ų

• Z = 4

• Mo Kα radiation

• μ = 2.29 mm⁻¹

• T = 150 K

• 0.17 × 0.07 × 0.06 mm

Data collection  

• Bruker APEXII diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2011 ▶) T _min = 0.825, T _max = 0.872

• 4396 measured reflections

• 1283 independent reflections

• 1130 reflections with I > 2σ(I)

• R _int = 0.061

Refinement  

• R[F ² > 2σ(F ²)] = 0.034

• wR(F ²) = 0.064

• S = 1.03

• 1283 reflections

• 70 parameters

• H-atom parameters constrained

• Δρ_max = 0.60 e Å⁻³

• Δρ_min = −0.58 e Å⁻³

Data collection: APEX2 (Bruker, 2011 ▶); cell refinement: SAINT (Bruker, 2011 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Berndt, 2001 ▶) and Mercury (Macrae et al., 2008 ▶); software used to prepare material for publication: WinGX (Farrugia, 2012) ▶ and publCIF (Westrip, 2010 ▶).

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Cd1—N1i	2.306 (3)
Cd1—N2	2.364 (3)
Cd1—S1	2.7143 (10)

Symmetry code: (i) .

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2B⋯S1iii	0.92	2.67	3.589 (3)	173

Symmetry code: (iii) .

supplementary crystallographic information

1. Comment

The crystal engineering of inorganic-organic hybrid coordination polymers is currently one of the most active fields in coordination chemistry, supramolecular and materials chemistry. These compounds attract significant attention for their architectures and topologies (Yang et al., 2001), including a large number of extended assemblies such as helical network (Withersby et al., 1997; Chemli et al. 2013) molecular zippers, diamondoid, honeycomb (Tong et al., 1998), square- grid (MacGillivary et al., 1994), T-shaped and ladder frameworks. (Fujita et al., 1995; Blake et al.,1997). Hybrid inorganic-organic thiocyanate materials exhibit interesting physical properties such electrical conductivity and dielectric relaxation process (Karoui et al., 2013) and may have potential applications in non-linear optics and luminescence (Chen et al., 2000; Bai et al., 2011). Herein we report the structure of a new polymeric hybrid [Cd(SCN)₂(C₆H₈N₂)₂]_n. As shown in Fig. 1, each cadmium atom, which sits on a twofold rotation axis, is coordinated by two cis N-bonded and two cis S-bonded thiocyanato anions. Two trans-coordinated neutral m-phenylenediamine ligands complete the octahedral coordination geometry around cadmium. The crystal structure of the title compound consists of both doubly µ-1,3-SCN and µ-1,3-phenylendiamine –bridged two-dimensional networks (Fig. 2). In the CdN4S2 core, the Cd—N and Cd—S bonds are in the range 2.3061 - 2.364 (3) Å and 2.7143 (10) Å, respectively (Table 1). The bond angles involving the cadmium (II) atom range from 83.89 (11) to 96.91 (10)° and from 174.75 (8) to 178.87 (14)°. These values are in good agreement with those observed in other similar complexes (Chemli et al. 2013). The double SCN bridging mode gives rise to a centrosymmetrical eight-membered Cd(SCN)₂Cd rings in a chair conformation because of the almost linear SCN groups (S–C–N angle = 178.8 (3)°). The distance between adjacent Cd atoms in Cd₂ (SCN)₂ rings is 5.937 Å. Again, these rings built up a staircase-like chain through their corner-sharing action at the two cadmium atoms via the µ-1,3-phenylenediamine moiety and give rise to twenty-membered [Cd₄(µ-1,3-SCN)₄(µ-1,3-phenylendiamine)₂] macrocycles as subunits, as depicted in Fig. 2. The bond angles in the phenyl groups deviate significantly from the idealized value of 120° due to the effect of the substituent. In fact, it was established that the angular deformations of phenyl groups can be described as a sum of the effects of the different substituents (Domenicano & Murray-Rust, 1979). The phenyl rings of 1,3-phenylendiamine ligand are planar with the greatest deviation from the six-atoms least-square plane of 0.0001 Å. They are well ordered with C–C–C angles in agreement with the expected sp² hybridization. The π-π interactions between neighboring phenyl rings may be neglected (>4 Å). The major contributions of the cohesion and the stability of this polymeric structure is assured by the covalent Cd-(S,N) bonds and the presence of one weak intralayer N–H···S hydrogen bond with the H···S and N···S distances of 2.674 Å and 3.589 (3) Å, respectively (Table 2).

2. Experimental

To 25 ml of an aqueous solution of thiocyanic acid (0.4 mol.l^-1) prepared using the published procedure (Bartlett et al., 1969) an appropriate amount of cadmium carbonate (0.832 g, 5 mmol) was added and refluxed for 2 h. After cooling, 25 ml of methanol and 0.7 ml of a solution of 1,3-phenylenediamine (7.5 mol.l^-1) was added. The resulting solution was heated under reflux for 2 h and left at ambient temperature for 2 hours after which well shaped brown crystals were obtained on slow evaporation of the solvent. They were washed with diethyl ether and dried over P₂O₅.

3. Refinement

All H atoms were positioned geometrically and allowed to ride on their parent atoms, with C—H = 0.95–0.98 Å, N—H = 0.92 Å, and with U_iso(H) = 1.2U_eq(C, N).

Figures

Fig. 1.

The molecular structure of the title compound, showing the coordination around the Cd2+ cations with labelling and displacement ellipsoids drawn at the 50% probability level. The H atoms are omitted for clarity. Symmetry codes: (i):-x + 3/2, -y + 1/2, -z + 1; (ii):x - 1/2, -y + 1/2, z - 1/2;(iii):-x + 1, y, -z + 1/2; (iv):-x + 1, y, -z - 1/2

Fig. 2.

The two-dimensional molecular structure of the title coordination polymer showing the staircase molecular arrangement.

Crystal data

[Cd(NCS)2(C6H8N2)2]	F(000) = 656
Mr = 336.7	Dx = 1.996 Mg m−3Dm = 1.931 Mg m−3Dm measured by Flotation
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1283 reflections
a = 10.8704 (6) Å	θ = 3.2–27.5°
b = 12.8983 (10) Å	µ = 2.29 mm−1
c = 8.3362 (5) Å	T = 150 K
β = 106.503 (3)°	Prism, brown
V = 1120.67 (13) Å3	0.17 × 0.07 × 0.06 mm
Z = 4

Data collection

Bruker APEXII diffractometer	1130 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.061
Graphite monochromator	θmax = 27.5°, θmin = 3.2°
CCD rotation images, thin slices scans	h = −10→14
Absorption correction: multi-scan (SADABS; Bruker, 2011)	k = −16→16
Tmin = 0.825, Tmax = 0.872	l = −10→9
4396 measured reflections	2 standard reflections every 120 min
1283 independent reflections

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.064	H-atom parameters constrained
S = 1.03	w = 1/[σ2(Fo2) + (0.0156P)2] where P = (Fo2 + 2Fc2)/3
1283 reflections	(Δ/σ)max < 0.001
70 parameters	Δρmax = 0.60 e Å−3
0 restraints	Δρmin = −0.58 e Å−3

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
Cd1	0.5	0.20749 (3)	0.25	0.01462 (12)
S1	0.65559 (10)	0.05195 (8)	0.40889 (13)	0.0297 (3)
N1	0.8532 (3)	0.1670 (2)	0.6240 (4)	0.0219 (7)
C1	0.7707 (3)	0.1202 (3)	0.5352 (4)	0.0163 (8)
N2	0.6151 (3)	0.2057 (2)	0.0483 (4)	0.0191 (7)
H2A	0.6952	0.233	0.0968	0.023*
H2B	0.6263	0.1377	0.0223	0.023*
C2	0.5594 (3)	0.2606 (3)	−0.1055 (4)	0.0159 (8)
C3	0.5	0.2075 (4)	−0.25	0.0149 (10)
H3	0.5	0.1339	−0.25	0.018*
C4	0.5598 (3)	0.3684 (3)	−0.1044 (4)	0.0174 (8)
H4	0.6007	0.4054	−0.0049	0.021*
C5	0.5	0.4211 (4)	−0.25	0.0237 (13)
H5	0.5	0.4947	−0.25	0.028*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Cd1	0.0134 (2)	0.0146 (2)	0.0142 (2)	0	0.00127 (14)	0
S1	0.0252 (6)	0.0127 (5)	0.0371 (6)	−0.0027 (4)	−0.0140 (4)	0.0019 (4)
N1	0.0209 (18)	0.0165 (17)	0.0248 (18)	0.0001 (14)	0.0010 (15)	0.0012 (14)
C1	0.0176 (19)	0.0127 (19)	0.0180 (19)	0.0044 (16)	0.0041 (15)	0.0024 (15)
N2	0.0182 (16)	0.0191 (17)	0.0199 (17)	0.0006 (14)	0.0051 (13)	−0.0011 (14)
C2	0.0117 (18)	0.021 (2)	0.0168 (19)	0.0008 (15)	0.0067 (15)	0.0013 (15)
C3	0.013 (2)	0.012 (3)	0.020 (3)	0	0.006 (2)	0
C4	0.0166 (19)	0.018 (2)	0.0175 (19)	−0.0036 (15)	0.0046 (15)	−0.0055 (15)
C5	0.028 (3)	0.010 (3)	0.036 (3)	0	0.014 (3)	0

Geometric parameters (Å, º)

Cd1—N1i	2.306 (3)	N2—H2A	0.92
Cd1—N1ii	2.306 (3)	N2—H2B	0.92
Cd1—N2iii	2.364 (3)	C2—C3	1.376 (4)
Cd1—N2	2.364 (3)	C2—C4	1.391 (5)
Cd1—S1iii	2.7143 (10)	C3—C2iv	1.376 (4)
Cd1—S1	2.7143 (10)	C3—H3	0.95
S1—C1	1.643 (4)	C4—C5	1.382 (4)
N1—C1	1.157 (4)	C4—H4	0.95
N1—Cd1i	2.306 (3)	C5—C4iv	1.382 (4)
N2—C2	1.439 (4)	C5—H5	0.95
N1i—Cd1—N1ii	90.81 (15)	C2—N2—Cd1	117.1 (2)
N1i—Cd1—N2iii	96.91 (10)	C2—N2—H2A	108
N1ii—Cd1—N2iii	83.89 (11)	Cd1—N2—H2A	108
N1i—Cd1—N2	83.89 (11)	C2—N2—H2B	108
N1ii—Cd1—N2	96.91 (10)	Cd1—N2—H2B	108
N2iii—Cd1—N2	178.87 (14)	H2A—N2—H2B	107.3
N1i—Cd1—S1iii	174.75 (8)	C3—C2—C4	120.2 (4)
N1ii—Cd1—S1iii	92.41 (8)	C3—C2—N2	120.6 (3)
N2iii—Cd1—S1iii	87.56 (8)	C4—C2—N2	119.1 (3)
N2—Cd1—S1iii	91.60 (8)	C2—C3—C2iv	120.4 (5)
N1i—Cd1—S1	92.41 (8)	C2—C3—H3	119.8
N1ii—Cd1—S1	174.75 (8)	C2iv—C3—H3	119.8
N2iii—Cd1—S1	91.60 (8)	C5—C4—C2	119.0 (4)
N2—Cd1—S1	87.56 (8)	C5—C4—H4	120.5
S1iii—Cd1—S1	84.68 (4)	C2—C4—H4	120.5
C1—S1—Cd1	99.92 (12)	C4iv—C5—C4	121.2 (5)
C1—N1—Cd1i	165.4 (3)	C4iv—C5—H5	119.4
N1—C1—S1	178.8 (3)	C4—C5—H5	119.4
N1i—Cd1—S1—C1	6.69 (14)	S1iii—Cd1—N2—C2	81.6 (2)
N1ii—Cd1—S1—C1	−121.1 (9)	S1—Cd1—N2—C2	166.2 (2)
N2iii—Cd1—S1—C1	−90.29 (14)	Cd1—N2—C2—C3	−103.9 (3)
N2—Cd1—S1—C1	90.47 (15)	Cd1—N2—C2—C4	72.5 (3)
S1iii—Cd1—S1—C1	−177.70 (14)	C4—C2—C3—C2iv	0.0 (2)
Cd1i—N1—C1—S1	122 (17)	N2—C2—C3—C2iv	176.3 (3)
Cd1—S1—C1—N1	−147 (17)	C3—C2—C4—C5	0.0 (4)
N1i—Cd1—N2—C2	−101.1 (2)	N2—C2—C4—C5	−176.4 (3)
N1ii—Cd1—N2—C2	−11.0 (3)	C2—C4—C5—C4iv	0.0 (2)
N2iii—Cd1—N2—C2	123.9 (2)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2B···S1v	0.92	2.67	3.589 (3)	173

Symmetry code: (v) x, −y, z−1/2.