A second polymorph of 3,4-bis­(6-bromo­pyridin-3-yl)-1,2,5-thia­diazole

Becker, L.; Altenburger, K.; Spannenberg, A.; Arndt, P.; Rosenthal, U.

doi:10.1107/S2414314616009603

organic compounds

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Volume 1| Part 6| June 2016| x160960

doi:10.1107/S2414314616009603

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A second polymorph of 3,4-bis(6-bromopyridin-3-yl)-1,2,5-thiadiazole

Lisanne Becker,^a ^* Kai Altenburger,^a Anke Spannenberg,^a Perdita Arndt ^a and Uwe Rosenthal ^a

^aLeibniz-Institut für Katalyse e. V. an der Universität Rostock, Albert-Einstein-Strasse 29a, 18059 Rostock, Germany
^*Correspondence e-mail: lisanne.becker@catalysis.de

Edited by H. Ishida, Okayama University, Japan (Received 2 June 2016; accepted 14 June 2016; online 21 June 2016)

The title compound, C₁₂H₆Br₂N₄S, a second polymorph in the triclinic space group P-1, is presented. As in the earlier reported monoclinic polymorph in the space group C2/c [Becker et al. (2016 ). Chem. Eur. J. In the press], the thiadiazole ring is planar with an r.m.s. deviation of 0.004 Å. The five-membered ring is tilted with respect to the two pyridyl substituents by 23.16 (7) and 49.47 (9)°. In the crystal, molecules are linked by a weak non-bonding Br⋯N interaction [3.056 (3) Å]. Furthermore, a column of molecules is established along the b axis by π–π stacking interactions between the pyridine rings [centroid–centroid distances = 3.7014 (16) and 3.5934 (15) Å]. Additionally, a short intermolecular Br⋯Br contact [3.3791 (6) Å] and Br⋯π-aryl contacts [3.6815 (11)–3.7659 (12) Å] towards the thiadiazole and pyridine rings are found.

Keywords: crystal structure; heterocycle; thiadiazole; polymorph.

CCDC reference: 1485338

Structure description

The title compound was formed by the reaction of SOCl₂ with [Ti(C₅Me₅)₂(N=C(R)—C(R)=N)] (R = 6-Br-3-py), as the coupling product of two molecules of 2-bromo-5-cyanopyridine at [Ti(C₅Me₅)₂] (Becker et al., 2016). Triclinic (P $[\overline{1}]$ ) and monoclinic (C2/c) polymorphs of the title compound were observed, the triclinic one being presented here (Fig. 1). The thiadiazole ring is planar (r.m.s. deviation 0.004 Å) as found in the earlier reported monoclinic polymorph. This fact and the N—S [N1—S1 1.625 (2), N2—S2 1.629 (2) Å], C—N [C1—N1 1.332 (3), C2—N2 1.324 (3) Å] and C—C [C1—C2 1.441 (3) Å] bond lengths indicate electron delocalization in the ring system. The five-membered S1/N1/C1/C2/N2 ring makes dihedral angles of 23.16 (7) and 49.47 (9)°, respectively, with the N3/C3–C7 and N4/C8–C12 pyridyl substituents. Examples for similar symmetrical substituted 1,2,5-thiadiazole derivatives were published by Mellini & Merlino (1976 ), Mühlebach et al. (1986 ), Tomura & Yamashita (2010 ) and Suturina et al. (2011 ). One difference in the molecular structure between the two polymorphs is the orientation of the pyridyl substituents (Fig. 2).

Figure 1
Molecular structure of the title compound with atom labelling and displacement ellipsoids drawn at the 50% probability level.

Figure 2
Molecular structure of the monoclinic polymorph of 3,4-bis(6-bromopyridin-3-yl)-1,2,5-thiadiazole with displacement ellipsoids drawn at the 50% probability level. [Symmetry code: (i) −x + 2, y, −z + $[{3\over 2}]$ .]

In the crystal of the triclinic polymorph, molecules are linked by a weak non-bonding Br⋯N interaction [Br1⋯N4 = 3.056 (3) Å]. Furthermore, a column of molecules is established along the b axis by π–π stacking interactions between the pyridine N3/C3–C7 rings (Fig. 3). This column shows an alternating pattern of short and long contacts, with centroid–centroid distances of 3.5934 (15) and 3.7014 (16) Å, respectively, and with ring slippages [distance between Cg(I) and perpendicular projection of Cg(J) on ring I] of 1.344 and 1.822 Å. Additionally, two Br1⋯π-aryl contacts towards the thiadiazole ring are found [Br1⋯Cg(S1/N1/C1/C2/N2) 3.6815 (11) and 3.7659 (12) Å]. The other bromine atom shows a short intermolecular Br⋯Br contact [Br2⋯Br2 3.3791 (6) Å] and a Br⋯π-aryl contact towards the N4/C8–C12 pyridine ring [Br2⋯Cg(N4/C8–C12) 3.6577 (11) Å]. In the monoclinic polymorph, the molecules are linked by intermolecular non-bonding Br⋯N interactions (3.190 Å), and Br⋯π-aryl contacts can be observed as well [Br⋯Cg(thiadiazole) 3.6748 (13) Å], but no intermolecular Br⋯Br contacts or π–π stacking interactions are present.

Figure 3
Part of the packing diagram of the triclinic polymorph of the title compound, showing the formation of a π–π-stacked column along the b axis. For clarity H atoms have been omitted.

Synthesis and crystallization

[Ti(C₅Me₅)₂(N=C(R)—C(R)=N)] (R = 6-Br-3-py) (0.034 g, 0.05 mmol) were dissolved in C₆D₆ and the red solution was transferred into a sealable J-Young NMR tube. A 0.2 M toluene solution of SOCl₂ (0.25 ml, 0.05 mmol) was then added via syringe and the mixture was warmed to 60°C for 7 d. Upon cooling to ambient temperature, yellow crystals formed (Becker et al., 2016).

Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. The H atoms were placed in idealized positions with d(C—H) = 0.95 Å and refined using a riding model with U_iso(H) fixed at 1.2U_eq(C).

Table 1
Experimental details

Crystal data
Chemical formula	C₁₂H₆Br₂N₄S
M_r	398.09
Crystal system, space group	Triclinic, P $[\overline{1}]$
Temperature (K)	150
a, b, c (Å)	7.1617 (4), 7.2787 (4), 14.4257 (8)
α, β, γ (°)	77.0382 (9), 78.7453 (8), 61.5479 (7)
V (Å³)	640.88 (6)
Z	2
Radiation type	Mo Kα
μ (mm⁻¹)	6.48
Crystal size (mm)	0.49 × 0.36 × 0.19

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Bruker, 2014 )
T_min, T_max	0.24, 0.38
No. of measured, independent and observed [I > 2σ(I)] reflections	8969, 2957, 2672
R_int	0.020
(sin θ/λ)_max (Å⁻¹)	0.650

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.026, 0.075, 1.06
No. of reflections	2957
No. of parameters	172
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.52, −0.84
Computer programs: APEX2 (Bruker, 2014), SAINT (Bruker, 2013 ), SHELXS97 (Sheldrick, 2008 ), SHELXL2014 (Sheldrick, 2015 ), XP in SHELXTL (Sheldrick, 2008), Mercury (Macrae et al., 2006 ), publCIF (Westrip, 2010 ) and PLATON (Spek, 2009 ).

Structural data

CCDC reference: 1485338

Crystal structure: contains datablock I. DOI: 10.1107/S2414314616009603/is4008sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S2414314616009603/is4008Isup2.hkl

Supporting information file. DOI: 10.1107/S2414314616009603/is4008Isup3.cml

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2014); cell refinement: SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: XP in SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2010) and PLATON (Spek, 2009).

3,4-Bis(6-bromopyridin-3-yl)-1,2,5-thiadiazole top

Crystal data top

C₁₂H₆Br₂N₄S	Z = 2
M_r = 398.09	F(000) = 384
Triclinic, P1	D_x = 2.063 Mg m⁻³
a = 7.1617 (4) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.2787 (4) Å	Cell parameters from 5554 reflections
c = 14.4257 (8) Å	θ = 2.9–28.7°
α = 77.0382 (9)°	µ = 6.48 mm⁻¹
β = 78.7453 (8)°	T = 150 K
γ = 61.5479 (7)°	Prism, yellow
V = 640.88 (6) Å³	0.49 × 0.36 × 0.19 mm

Data collection top

Bruker APEXII CCD diffractometer	2957 independent reflections
Radiation source: fine-focus sealed tube	2672 reflections with I > 2σ(I)
Detector resolution: 8.3333 pixels mm^-1	R_int = 0.020
φ and ω scans	θ_max = 27.5°, θ_min = 1.5°
Absorption correction: multi-scan (SADABS; Bruker, 2014)	h = −8→9
T_min = 0.24, T_max = 0.38	k = −9→9
8969 measured reflections	l = −18→18

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.026	H-atom parameters constrained
wR(F²) = 0.075	w = 1/[σ²(F_o²) + (0.037P)² + 1.1147P] where P = (F_o² + 2F_c²)/3
S = 1.06	(Δ/σ)_max = 0.001
2957 reflections	Δρ_max = 0.52 e Å⁻³
172 parameters	Δρ_min = −0.84 e Å⁻³

Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Br1	0.76469 (5)	0.11355 (4)	1.18285 (2)	0.02297 (9)
Br2	1.23819 (5)	0.06797 (5)	0.53206 (2)	0.02999 (10)
C1	0.2757 (4)	0.3696 (4)	0.83700 (18)	0.0127 (5)
C2	0.3420 (4)	0.3729 (4)	0.73593 (18)	0.0138 (5)
C3	0.4074 (4)	0.3033 (4)	0.91690 (17)	0.0122 (5)
C4	0.3258 (4)	0.2520 (4)	1.00972 (18)	0.0145 (5)
H4	0.1887	0.2566	1.0185	0.017*
C5	0.6206 (4)	0.1910 (4)	1.07289 (18)	0.0148 (5)
C6	0.7177 (4)	0.2399 (4)	0.98464 (19)	0.0172 (5)
H6	0.8552	0.2333	0.9785	0.021*
C7	0.6078 (4)	0.2985 (4)	0.90591 (18)	0.0157 (5)
H7	0.6683	0.3356	0.8444	0.019*
C8	0.5597 (4)	0.3033 (4)	0.68630 (17)	0.0141 (5)
C9	0.7254 (4)	0.1039 (4)	0.71185 (18)	0.0175 (5)
H9	0.6961	0.0110	0.7634	0.021*
C10	0.9576 (4)	0.1674 (4)	0.59460 (18)	0.0160 (5)
C11	0.8063 (4)	0.3673 (4)	0.56073 (19)	0.0188 (5)
H11	0.8404	0.4529	0.5070	0.023*
C12	0.6036 (4)	0.4365 (4)	0.60855 (18)	0.0166 (5)
H12	0.4946	0.5736	0.5889	0.020*
N1	0.0649 (4)	0.4469 (3)	0.85706 (16)	0.0164 (4)
N2	0.1799 (4)	0.4540 (4)	0.68361 (16)	0.0182 (4)
N3	0.4294 (4)	0.1969 (3)	1.08689 (15)	0.0156 (4)
N4	0.9244 (4)	0.0363 (3)	0.66717 (16)	0.0178 (4)
S1	−0.03875 (11)	0.52048 (11)	0.75638 (5)	0.01999 (15)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Br1	0.02748 (16)	0.02225 (14)	0.01974 (15)	−0.01104 (12)	−0.00918 (11)	0.00111 (10)
Br2	0.02001 (16)	0.03454 (17)	0.03315 (18)	−0.01163 (13)	0.00630 (12)	−0.01040 (13)
C1	0.0121 (11)	0.0133 (10)	0.0126 (11)	−0.0065 (9)	0.0006 (9)	−0.0014 (9)
C2	0.0148 (12)	0.0137 (11)	0.0121 (11)	−0.0070 (9)	0.0000 (9)	−0.0001 (9)
C3	0.0133 (12)	0.0116 (10)	0.0110 (11)	−0.0058 (9)	0.0010 (9)	−0.0020 (8)
C4	0.0135 (12)	0.0160 (11)	0.0135 (12)	−0.0071 (9)	0.0015 (10)	−0.0029 (9)
C5	0.0186 (13)	0.0126 (10)	0.0129 (11)	−0.0065 (10)	−0.0028 (10)	−0.0016 (9)
C6	0.0149 (12)	0.0194 (12)	0.0187 (13)	−0.0097 (10)	0.0007 (10)	−0.0032 (10)
C7	0.0159 (12)	0.0195 (12)	0.0128 (12)	−0.0105 (10)	0.0023 (10)	−0.0022 (9)
C8	0.0144 (12)	0.0172 (11)	0.0096 (11)	−0.0069 (10)	0.0001 (9)	−0.0019 (9)
C9	0.0181 (13)	0.0173 (12)	0.0123 (12)	−0.0067 (10)	0.0007 (10)	0.0013 (9)
C10	0.0124 (12)	0.0228 (12)	0.0137 (12)	−0.0083 (10)	0.0020 (10)	−0.0064 (10)
C11	0.0197 (13)	0.0226 (12)	0.0129 (12)	−0.0116 (11)	−0.0003 (10)	0.0028 (10)
C12	0.0142 (12)	0.0170 (11)	0.0135 (12)	−0.0051 (10)	−0.0013 (10)	0.0024 (9)
N1	0.0145 (11)	0.0187 (10)	0.0145 (10)	−0.0073 (9)	−0.0004 (9)	−0.0016 (8)
N2	0.0157 (11)	0.0233 (11)	0.0127 (10)	−0.0080 (9)	0.0002 (9)	−0.0004 (8)
N3	0.0179 (11)	0.0162 (10)	0.0124 (10)	−0.0086 (9)	−0.0001 (8)	−0.0009 (8)
N4	0.0145 (11)	0.0194 (10)	0.0152 (10)	−0.0046 (9)	−0.0008 (9)	−0.0024 (8)
S1	0.0127 (3)	0.0278 (3)	0.0158 (3)	−0.0076 (3)	−0.0012 (2)	−0.0004 (2)

Geometric parameters (Å, º) top

Br1—C5	1.893 (3)	C6—H6	0.9500
Br2—C10	1.891 (3)	C7—H7	0.9500
C1—N1	1.332 (3)	C8—C9	1.393 (3)
C1—C2	1.441 (3)	C8—C12	1.401 (3)
C1—C3	1.480 (3)	C9—N4	1.344 (3)
C2—N2	1.324 (3)	C9—H9	0.9500
C2—C8	1.475 (4)	C10—N4	1.317 (3)
C3—C4	1.397 (3)	C10—C11	1.384 (4)
C3—C7	1.397 (4)	C11—C12	1.380 (4)
C4—N3	1.338 (3)	C11—H11	0.9500
C4—H4	0.9500	C12—H12	0.9500
C5—N3	1.326 (3)	N1—S1	1.625 (2)
C5—C6	1.385 (4)	N2—S1	1.629 (2)
C6—C7	1.379 (4)

N1—C1—C2	112.7 (2)	C9—C8—C12	117.8 (2)
N1—C1—C3	118.3 (2)	C9—C8—C2	122.2 (2)
C2—C1—C3	128.9 (2)	C12—C8—C2	120.0 (2)
N2—C2—C1	113.1 (2)	N4—C9—C8	123.3 (2)
N2—C2—C8	118.3 (2)	N4—C9—H9	118.4
C1—C2—C8	128.6 (2)	C8—C9—H9	118.4
C4—C3—C7	117.0 (2)	N4—C10—C11	125.8 (2)
C4—C3—C1	119.3 (2)	N4—C10—Br2	115.89 (19)
C7—C3—C1	123.6 (2)	C11—C10—Br2	118.3 (2)
N3—C4—C3	123.8 (2)	C12—C11—C10	116.9 (2)
N3—C4—H4	118.1	C12—C11—H11	121.5
C3—C4—H4	118.1	C10—C11—H11	121.5
N3—C5—C6	124.5 (2)	C11—C12—C8	119.5 (2)
N3—C5—Br1	116.56 (19)	C11—C12—H12	120.2
C6—C5—Br1	118.9 (2)	C8—C12—H12	120.2
C7—C6—C5	117.7 (2)	C1—N1—S1	107.62 (18)
C7—C6—H6	121.2	C2—N2—S1	107.62 (18)
C5—C6—H6	121.2	C5—N3—C4	117.1 (2)
C6—C7—C3	119.9 (2)	C10—N4—C9	116.6 (2)
C6—C7—H7	120.1	N1—S1—N2	98.99 (12)
C3—C7—H7	120.1

N1—C1—C2—N2	0.7 (3)	C12—C8—C9—N4	1.6 (4)
C3—C1—C2—N2	−176.1 (2)	C2—C8—C9—N4	179.4 (2)
N1—C1—C2—C8	179.3 (2)	N4—C10—C11—C12	1.3 (4)
C3—C1—C2—C8	2.5 (4)	Br2—C10—C11—C12	−179.2 (2)
N1—C1—C3—C4	22.4 (3)	C10—C11—C12—C8	−1.1 (4)
C2—C1—C3—C4	−160.9 (2)	C9—C8—C12—C11	−0.2 (4)
N1—C1—C3—C7	−154.3 (2)	C2—C8—C12—C11	−178.0 (2)
C2—C1—C3—C7	22.4 (4)	C2—C1—N1—S1	−0.9 (2)
C7—C3—C4—N3	−0.9 (4)	C3—C1—N1—S1	176.28 (17)
C1—C3—C4—N3	−177.8 (2)	C1—C2—N2—S1	−0.1 (3)
N3—C5—C6—C7	−0.1 (4)	C8—C2—N2—S1	−178.87 (18)
Br1—C5—C6—C7	−179.15 (19)	C6—C5—N3—C4	0.7 (4)
C5—C6—C7—C3	−1.1 (4)	Br1—C5—N3—C4	179.80 (17)
C4—C3—C7—C6	1.5 (4)	C3—C4—N3—C5	−0.2 (4)
C1—C3—C7—C6	178.3 (2)	C11—C10—N4—C9	0.1 (4)
N2—C2—C8—C9	−129.4 (3)	Br2—C10—N4—C9	−179.44 (19)
C1—C2—C8—C9	52.0 (4)	C8—C9—N4—C10	−1.6 (4)
N2—C2—C8—C12	48.3 (3)	C1—N1—S1—N2	0.78 (19)
C1—C2—C8—C12	−130.3 (3)	C2—N2—S1—N1	−0.4 (2)

Acknowledgements

We thank our technical staff for assistance. This work was supported by the Deutsche Forschungsgemeinschaft (RO1269/9–1). The publication of this article was funded by the Open Access Fund of the Leibniz Association.

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