Crystal structure of bis-[2,5-bis-(pyridin-2-yl)-1,3,4-thia-diazole-κ(2) N (2),N (3)]bis-(thio-cyanato-κS)copper(II).

The mononuclear title complex, [Cu(SCN)2(C12H8N4S)2], was obtained by the reaction of 2,5-bis-(pyridin-2-yl)-1,3,4-thia-diazole and potassium thio-cyanate with copper(II) chloride dihydrate. The copper cation lies on an inversion centre and displays an elongated octa-hedral coordination geometry. The equatorial positions are occupied by the N atoms of two 2,5-bis-(pyridin-2-yl)-1,3,4-thia-diazole ligands, whereas the axial positions are occupied by the S atoms of two thio-cyanate anions. The thia-diazole and the pyridyl rings linked to the metal are approximately coplanar, with a maximum deviation from the mean plane of 0.190 (2) Å. The cohesion of the crystal structure is ensured by weak C-H⋯N hydrogen bonds and π-π inter-actions between parallel pyridyl rings of neighbouring mol-ecules [centroid-to-centroid distance = 3.663 (2) Å], leading to a three-dimensional network.

Chemical context

The use of compounds containing a 1,3,4-thia­diazole moiety as part of ligand systems has gained considerable attention in recent years (Kadam Sushama et al., 2016 ▸). Indeed, a 2,5-bis­(pyridin-2-yl)-1,3,4-thia­diazole (bptd) and its metal complexes have been extensively studied because of their potential applications in biology (Baghel et al., 2014 ▸; Ahmed et al., 2015 ▸; Zine et al., 2016 ▸), magnetism (Bentiss et al., 2004 ▸) and coordination chemistry (Bentiss et al., 2002 ▸). An inter­esting feature of the metal-ligand chemistry of these compounds is that the complexes can be mononuclear (Bentiss et al., 2011 ▸, 2012 ▸; Klingele et al., 2010 ▸; Kaase & Klingele, 2014 ▸) or binuclear (Laachir et al., 2013 ▸).

We have recently reported the synthesis and characterization of monomeric complexes of NiII and CoII with bptd in the presence of the pseudohalide azide (Laachir et al., 2015a ▸,b ▸). In this context, we report here the synthesis and crystal structure of a new CuII complex with bptd and thio­cyanate as co-ligands.

Structural commentary

The title complex has crystallographically imposed inversion symmetry, the copper atom lying on the Wyckoff special position 2b of the space group P21/c. The elongated octa­hedral coordination polyhedron around the metal cation is provided by four nitro­gen atoms of pyridine and thia­diazole rings occupying the equatorial plane and by the sulfur atoms of two thio­cyanate anions at the apical positions (Fig. 1 ▸). The Cu—N distances are 2.0267 (16) and 2.0463 (15) Å, the Cu—S bond length is 2.8125 (7) Å. A bond-valence-sum calculation (Brown & Altermatt, 1985 ▸) for Cu gives the expected BVS value of 2.11 valence units. The conformation of the ligand is approximately planar, with a maximum deviation from the least-squares plane of 0.190 (2) Å for atom C12. The dihedral angles formed by the thia­diazole ring with the N1/C2–C6 and N4/C8–C12 pyridine rings are 1.94 (8) and 6.96 (5)°, respectively.

Figure 1

The mol­ecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. H atoms are represented as small circles. [Symmetry code: (i) −x + 1, −y + 1, −z + 1.]

Supra­molecular features

In the crystal, the mol­ecules are linked by weak C—H⋯N hydrogen bonds (Table 1 ▸) and by π–π stacking inter­actions between the pyridyl rings of adjacent complex mol­ecules [inter­centroid distance = 3.663 (2) Å], forming a three-dimensional network (Fig. 2 ▸).

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C3—H3⋯N5i	0.93	2.53	3.353 (3)	147
C6—H6⋯N3ii	0.93	2.35	3.143 (3)	142
C4—H4⋯N4iii	0.93	2.57	3.458 (3)	161

Symmetry codes: (i) ; (ii) ; (iii) .

Figure 2

Crystal packing of the title compound, showing π–π inter­actions between pyridyl rings (green dashed lines) and inter­molecular hydrogen bonds (blue dashed lines).

Database survey

The structure of the title compound is similar to that of the related complexes [Co(C12H8N4S)2(N3)2] (Laachir et al., 2015b ▸) and [Ni(C12H8N4S)2(N3)2] (Laachir et al., 2015a ▸), in which the azide ion is substituted by the thio­cyanate group. The CuN4S2 octa­hedron is more distorted than the NiN6 and CoN6 octa­hedra.

Synthesis and crystallization

2,5-Bis(pyridin-2-yl)-1,3,4-thia­diazole (bptd) was synthesized as described previously by Lebrini et al. (2005 ▸). A solution of bptd (24 mg, 0.1 mmol) in CH3CN (10 mL) was layered onto a solution of CuCl2·2H2O (17 mg, 0.1 mmol) and KSCN (20 mg, 0.2 mmol) in CH3CN/H2O (1:1 v/v, 10 mL) in a test tube. The solution was left for two months at room temperature to give X-ray quality brown block-shaped crystals. After filtration, the product was washed with cold EtOH and dried under vacuum. Crystals were washed with water and dried under vacuum (yield 60%; m.p. 538 K). Analysis calculated for C26H16N10S4Cu: C, 47.30; H, 2.44; N, 21.21 S, 19.42. Found: C, 47.06; H, 2.43; N, 21.03; S, 19.56.

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2 ▸. H atoms were located in a difference Fourier map and treated as riding, with C—H = 0.96 Å, and with U iso(H) = 1.2 U eq(C). One outlier (002) was omitted in the last cycles of refinement.

Table 2

Experimental details

Crystal data
Chemical formula	[Cu(SCN)2(C12H8N4S)2]
M r	660.27
Crystal system, space group	Monoclinic, P21/c
Temperature (K)	296
a, b, c (Å)	8.0205 (3), 7.8434 (3), 21.3454 (9)
β (°)	92.565 (2)
V (Å3)	1341.45 (9)
Z	2
Radiation type	Mo Kα
μ (mm−1)	1.17
Crystal size (mm)	0.35 × 0.32 × 0.26
Data collection
Diffractometer	Bruker X8 APEX
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 ▸)
T min, T max	0.604, 0.746
No. of measured, independent and observed [I > 2σ(I)] reflections	42199, 4089, 3155
R int	0.060
(sin θ/λ)max (Å−1)	0.714
Refinement
R[F 2 > 2σ(F 2)], wR(F 2), S	0.036, 0.097, 1.04
No. of reflections	4089
No. of parameters	187
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å−3)	0.56, −0.51

Computer programs: APEX2 and SAINT (Bruker, 2009 ▸), SHELXT (Sheldrick, 2015a ▸), SHELXL2014 (Sheldrick, 2015b ▸), ORTEPIII (Burnett & Johnson, 1996 ▸), ORTEP-3 for Windows (Farrugia, 2012 ▸), Mercury (Macrae et al., 2008 ▸) and publCIF (Westrip, 2010 ▸).

Crystal structure: contains datablock(s) I. DOI: 10.1107/S2056989016011713/rz5192sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989016011713/rz5192Isup2.hkl

CCDC reference: 1494615

Additional supporting information: crystallographic information; 3D view; checkCIF report

[Cu(NCS)2(C12H8N4S)2]	Dx = 1.635 Mg m−3
Mr = 660.27	Melting point: 538 K
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 8.0205 (3) Å	Cell parameters from 4089 reflections
b = 7.8434 (3) Å	θ = 2.5–30.5°
c = 21.3454 (9) Å	µ = 1.17 mm−1
β = 92.565 (2)°	T = 296 K
V = 1341.45 (9) Å3	Block, brown
Z = 2	0.35 × 0.32 × 0.26 mm
F(000) = 670

Bruker X8 APEX diffractometer	4089 independent reflections
Radiation source: fine-focus sealed tube	3155 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.060
φ and ω scans	θmax = 30.5°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −11→11
Tmin = 0.604, Tmax = 0.746	k = −11→11
42199 measured reflections	l = −27→30

Refinement on F2	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.036	H-atom parameters constrained
wR(F2) = 0.097	w = 1/[σ2(Fo2) + (0.0418P)2 + 0.834P] where P = (Fo2 + 2Fc2)/3
S = 1.04	(Δ/σ)max < 0.001
4089 reflections	Δρmax = 0.56 e Å−3
187 parameters	Δρmin = −0.51 e Å−3

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.

	x	y	z	Uiso*/Ueq
C1	0.4345 (2)	0.6803 (2)	0.38733 (8)	0.0240 (4)
C2	0.5958 (2)	0.6037 (2)	0.37724 (8)	0.0240 (4)
C3	0.6786 (3)	0.6181 (3)	0.32209 (9)	0.0327 (4)
H3	0.6314	0.6778	0.2881	0.039*
C4	0.8333 (3)	0.5416 (3)	0.31863 (10)	0.0372 (5)
H4	0.8909	0.5469	0.2818	0.045*
C5	0.9012 (3)	0.4572 (3)	0.37055 (11)	0.0366 (5)
H5	1.0065	0.4079	0.3696	0.044*
C6	0.8102 (3)	0.4473 (3)	0.42395 (10)	0.0320 (4)
H6	0.8563	0.3896	0.4586	0.038*
C7	0.1712 (2)	0.8133 (2)	0.39355 (9)	0.0251 (4)
C8	0.0124 (2)	0.9022 (3)	0.38144 (9)	0.0270 (4)
C9	−0.1027 (3)	0.9212 (3)	0.42773 (10)	0.0322 (4)
H9	−0.0804	0.8796	0.4680	0.039*
C10	−0.2511 (3)	1.0036 (3)	0.41222 (12)	0.0387 (5)
H10	−0.3306	1.0198	0.4421	0.046*
C11	−0.2792 (3)	1.0615 (3)	0.35150 (12)	0.0430 (5)
H11	−0.3782	1.1168	0.3396	0.052*
C12	−0.1570 (3)	1.0356 (3)	0.30870 (12)	0.0439 (6)
H12	−0.1772	1.0747	0.2679	0.053*
C13	0.3302 (3)	0.2765 (3)	0.36867 (13)	0.0423 (5)
N1	0.65894 (19)	0.5170 (2)	0.42789 (7)	0.0246 (3)
N2	0.36607 (19)	0.6566 (2)	0.44138 (7)	0.0258 (3)
N3	0.2129 (2)	0.7323 (2)	0.44510 (7)	0.0282 (3)
N4	−0.0124 (2)	0.9581 (2)	0.32252 (8)	0.0354 (4)
N5	0.3255 (3)	0.3117 (3)	0.31799 (10)	0.0568 (6)
Cu1	0.5000	0.5000	0.5000	0.02713 (10)
S1	0.31614 (6)	0.80256 (7)	0.33603 (2)	0.02941 (12)
S2	0.33021 (9)	0.22277 (9)	0.44310 (3)	0.04809 (17)

	U11	U22	U33	U12	U13	U23
C1	0.0269 (9)	0.0275 (9)	0.0174 (8)	−0.0018 (7)	0.0005 (6)	0.0016 (7)
C2	0.0256 (8)	0.0274 (9)	0.0191 (8)	−0.0026 (7)	0.0017 (6)	−0.0008 (7)
C3	0.0359 (10)	0.0429 (12)	0.0196 (9)	−0.0034 (9)	0.0058 (7)	0.0018 (8)
C4	0.0368 (11)	0.0480 (13)	0.0278 (11)	−0.0035 (9)	0.0142 (8)	−0.0039 (9)
C5	0.0309 (10)	0.0421 (12)	0.0379 (12)	0.0034 (9)	0.0140 (9)	−0.0007 (9)
C6	0.0298 (10)	0.0346 (10)	0.0322 (11)	0.0052 (8)	0.0067 (8)	0.0050 (8)
C7	0.0244 (8)	0.0291 (9)	0.0219 (9)	−0.0009 (7)	0.0004 (6)	0.0005 (7)
C8	0.0257 (9)	0.0294 (9)	0.0256 (9)	−0.0003 (7)	−0.0006 (7)	0.0017 (7)
C9	0.0327 (10)	0.0371 (11)	0.0269 (10)	0.0007 (8)	0.0020 (8)	0.0004 (8)
C10	0.0318 (10)	0.0400 (12)	0.0449 (13)	0.0049 (9)	0.0081 (9)	−0.0054 (10)
C11	0.0314 (11)	0.0419 (12)	0.0554 (15)	0.0082 (9)	−0.0016 (10)	0.0047 (11)
C12	0.0414 (12)	0.0523 (14)	0.0376 (13)	0.0085 (11)	−0.0036 (10)	0.0139 (11)
C13	0.0331 (11)	0.0369 (12)	0.0568 (16)	0.0028 (9)	0.0003 (10)	−0.0137 (11)
N1	0.0247 (7)	0.0278 (8)	0.0217 (8)	0.0002 (6)	0.0047 (6)	0.0015 (6)
N2	0.0246 (7)	0.0311 (8)	0.0216 (8)	0.0017 (6)	0.0016 (6)	0.0026 (6)
N3	0.0267 (8)	0.0346 (9)	0.0236 (8)	0.0046 (7)	0.0035 (6)	0.0034 (7)
N4	0.0319 (9)	0.0440 (10)	0.0304 (9)	0.0065 (8)	0.0022 (7)	0.0108 (8)
N5	0.0803 (17)	0.0623 (15)	0.0260 (10)	0.0160 (13)	−0.0157 (10)	−0.0098 (10)
Cu1	0.02419 (16)	0.0377 (2)	0.02004 (17)	0.00875 (13)	0.00685 (11)	0.00895 (13)
S1	0.0304 (2)	0.0383 (3)	0.0196 (2)	0.0038 (2)	0.00108 (17)	0.00653 (19)
S2	0.0581 (4)	0.0487 (4)	0.0380 (3)	−0.0128 (3)	0.0077 (3)	−0.0015 (3)

C1—N2	1.313 (2)	C10—C11	1.382 (4)
C1—C2	1.452 (3)	C10—H10	0.9300
C1—S1	1.7106 (18)	C11—C12	1.384 (4)
C2—N1	1.356 (2)	C11—H11	0.9300
C2—C3	1.382 (3)	C12—N4	1.331 (3)
C2—S1	2.8397 (19)	C12—H12	0.9300
C3—C4	1.383 (3)	C13—N5	1.115 (3)
C3—H3	0.9300	C13—S2	1.644 (3)
C4—C5	1.382 (3)	N1—Cu1	2.0463 (15)
C4—H4	0.9300	N2—N3	1.370 (2)
C5—C6	1.383 (3)	N2—Cu1	2.0267 (16)
C5—H5	0.9300	N2—S1	2.5392 (16)
C6—N1	1.337 (2)	N3—S1	2.5657 (16)
C6—H6	0.9300	N4—S1	2.9062 (18)
C7—N3	1.301 (2)	N5—S2	2.759 (2)
C7—C8	1.465 (3)	Cu1—N2i	2.0267 (16)
C7—S1	1.7300 (19)	Cu1—N1i	2.0463 (15)
C8—N4	1.338 (3)	Cu1—S2i	2.8124 (7)
C8—C9	1.390 (3)	Cu1—S2	2.8125 (7)
C8—S1	2.774 (2)	S1—S2ii	4.0094 (9)
C9—C10	1.382 (3)	S2—S1iii	4.0094 (9)
C9—H9	0.9300
N2—C1—C2	118.82 (16)	N2—N3—S1	73.37 (9)
N2—C1—S1	113.60 (14)	C12—N4—C8	116.71 (19)
C2—C1—S1	127.58 (14)	C12—N4—S1	172.31 (16)
N1—C2—C3	122.97 (18)	C8—N4—S1	70.92 (11)
N1—C2—C1	113.12 (15)	C13—N5—S2	1.19 (15)
C3—C2—C1	123.91 (18)	N2—Cu1—N2i	180.0
N1—C2—S1	141.62 (12)	N2—Cu1—N1i	99.96 (6)
C3—C2—S1	95.40 (13)	N2i—Cu1—N1i	80.04 (6)
C1—C2—S1	28.52 (8)	N2—Cu1—N1	80.04 (6)
C2—C3—C4	118.45 (19)	N2i—Cu1—N1	99.96 (6)
C2—C3—H3	120.8	N1i—Cu1—N1	180.0
C4—C3—H3	120.8	N2—Cu1—S2i	91.78 (5)
C5—C4—C3	119.16 (19)	N2i—Cu1—S2i	88.22 (5)
C5—C4—H4	120.4	N1i—Cu1—S2i	91.80 (5)
C3—C4—H4	120.4	N1—Cu1—S2i	88.20 (5)
C4—C5—C6	119.0 (2)	N2—Cu1—S2	88.22 (5)
C4—C5—H5	120.5	N2i—Cu1—S2	91.78 (5)
C6—C5—H5	120.5	N1i—Cu1—S2	88.20 (5)
N1—C6—C5	122.9 (2)	N1—Cu1—S2	91.80 (5)
N1—C6—H6	118.6	S2i—Cu1—S2	180.00 (2)
C5—C6—H6	118.6	C1—S1—C7	86.79 (9)
N3—C7—C8	124.76 (17)	C1—S1—N2	28.28 (7)
N3—C7—S1	114.92 (14)	C7—S1—N2	58.51 (7)
C8—C7—S1	120.27 (14)	C1—S1—N3	59.41 (7)
N4—C8—C9	123.86 (18)	C7—S1—N3	27.38 (7)
N4—C8—C7	114.43 (17)	N2—S1—N3	31.13 (5)
C9—C8—C7	121.69 (18)	C1—S1—C8	113.89 (8)
N4—C8—S1	81.95 (12)	C7—S1—C8	27.14 (7)
C9—C8—S1	154.16 (14)	N2—S1—C8	85.63 (5)
C7—C8—S1	32.59 (9)	N3—S1—C8	54.50 (5)
C10—C9—C8	118.2 (2)	C1—S1—C2	23.90 (7)
C10—C9—H9	120.9	C7—S1—C2	110.69 (7)
C8—C9—H9	120.9	N2—S1—C2	52.18 (5)
C9—C10—C11	118.7 (2)	N3—S1—C2	83.31 (5)
C9—C10—H10	120.6	C8—S1—C2	137.77 (6)
C11—C10—H10	120.6	C1—S1—N4	140.66 (7)
C10—C11—C12	118.7 (2)	C7—S1—N4	54.21 (7)
C10—C11—H11	120.6	N2—S1—N4	112.55 (5)
C12—C11—H11	120.6	N3—S1—N4	81.50 (5)
N4—C12—C11	123.8 (2)	C8—S1—N4	27.13 (5)
N4—C12—H12	118.1	C2—S1—N4	164.06 (5)
C11—C12—H12	118.1	C1—S1—S2ii	95.46 (7)
N5—C13—S2	178.0 (3)	C7—S1—S2ii	63.79 (7)
C6—N1—C2	117.53 (16)	N2—S1—S2ii	82.33 (4)
C6—N1—Cu1	128.20 (13)	N3—S1—S2ii	70.21 (4)
C2—N1—Cu1	114.18 (12)	C8—S1—S2ii	64.66 (4)
C1—N2—N3	113.62 (15)	C2—S1—S2ii	105.86 (4)
C1—N2—Cu1	113.43 (13)	N4—S1—S2ii	73.36 (4)
N3—N2—Cu1	132.74 (12)	C13—S2—N5	0.81 (10)
C1—N2—S1	38.12 (9)	C13—S2—Cu1	101.44 (9)
N3—N2—S1	75.50 (9)	N5—S2—Cu1	102.00 (6)
Cu1—N2—S1	151.43 (8)	C13—S2—S1iii	70.19 (8)
C7—N3—N2	111.07 (15)	N5—S2—S1iii	69.96 (5)
C7—N3—S1	37.70 (9)	Cu1—S2—S1iii	151.94 (2)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···N5iv	0.93	2.53	3.353 (3)	147
C6—H6···N3i	0.93	2.35	3.143 (3)	142
C4—H4···N4v	0.93	2.57	3.458 (3)	161