2,6-Bis(bromo­meth­yl)pyridine

Abstract

In the title mol­ecule, C₇H₇Br₂N, the C—Br vectors of the bromo­methyl groups extend to opposite sides of the pyridine ring and are oriented nearly perpendicular to its plane. In the crystal, the mol­ecules related by a c-glide-plane operation are arranged into stacks along the c axis, with centroid–centroid distances between neighboring aromatic rings of 3.778 (2) Å. A short Br⋯Br contact of 3.6025 (11) Å is observed within a pair of inversion-related mol­ecules.

Related literature  

For the isomorphous crystal structure of 2,6-bis­(chloro­meth­yl)pyridine, see: Betz et al. (2011 ▶). For the synthesis of the title compound, see: Dioury et al. (2009 ▶).

Experimental  

Crystal data  

• C₇H₇Br₂N

• M _r = 264.96

• Monoclinic,

• a = 9.2955 (19) Å

• b = 12.980 (3) Å

• c = 7.5288 (15) Å

• β = 110.75 (3)°

• V = 849.5 (3) ų

• Z = 4

• Mo Kα radiation

• μ = 9.47 mm⁻¹

• T = 293 K

• 0.28 × 0.26 × 0.12 mm

Data collection  

• Nonius KappaCCD diffractometer

• Absorption correction: multi-scan (SORTAV; Blessing, 1995 ▶) T _min = 0.088, T _max = 0.321

• 10219 measured reflections

• 2480 independent reflections

• 1923 reflections with I > 2σ(I)

• R _int = 0.048

Refinement  

• R[F ² > 2σ(F ²)] = 0.044

• wR(F ²) = 0.119

• S = 1.04

• 2480 reflections

• 92 parameters

• H-atom parameters constrained

• Δρ_max = 0.99 e Å⁻³

• Δρ_min = −1.06 e Å⁻³

Data collection: COLLECT (Nonius, 1998 ▶); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997 ▶); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2006 ▶) and XP in SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: enCIFer (Allen et al., 2004 ▶) and PLATON (Spek, 2009 ▶).

Supplementary Material

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

supplementary crystallographic information

1. Comment

2,6-Bis(bromomethyl)pyridine is a well known organic compound which serves as a precursor in various organic reactions leading to formation of a large range of pyridine derivatives. Additionally, the presence of N-donor atom enables coordination of metal ions by this molecule. Due to conformational flexibility of the bromomethyl arms, the title compound has been used as a starting material for the synthesis of macrocycles (Dioury et al., 2009).

Recently, the crystal structure of the Cl analogue of the title compound - 2,6-bis(chloromethyl)pyridine - has been reported and the two compounds form an isomorphous pair.

In the crystal, π-π stacking interaction between aromatic rings of molecules forming stacks along the c axis are observed. The distance between the centroids of the stacked pyridine rings is 3.778 (2) Å (symmetry code: x, 1/2 - y, -1/2 + z).

The bromine atoms are situated at both sides of the pyridine plane and bromomethyl arms are pointing at approximately opposite directions. In the crystal, there are two different Br···Br contacts of type I. The contact longer than the sum of van der Waals radii [Br2···Br1ⁱ 3.7051 (11) Å; symmetry code: (i) 1 + x, y, 1 + z] links the molecules into infinite chains along [1 0 1] whereas the other one [Br2···Br2ⁱⁱⁱ 3.6025 (11) Å; symmetry code: (iii) -x, -y, -z] is formed between neighbouring chains.

2. Experimental

The compund was obtained according to previously reported procedure from the 2,6-bis(hydroxymethyl)pyridine (Dioury et al., 2009). Crystals suitable for the X-ray diffraction study were obtained by recrystallization from diethylether at room temperature.

3. Refinement

The H atoms were positioned geometrically and refined using a riding model with C—H = 0.95–0.99 Å and with U_iso(H) = 1.2 times U_eq(C).

Figures

Fig. 1.

The molecular structure of the title compound. Displacement ellipsoids are drawn at the 50% probability level. H atoms are presented as small spheres of arbitrary radius.

Fig. 2.

Intermolecular Br···Br contacts (dashed lines) in the title compound. Symmetry codes: (i) 1 + x, y, 1 + z; (ii) -1 + x, y, -1 + z; (iii) -x, -y, -z. H atoms have been omitted for clarity.

Crystal data

C7H7Br2N	F(000) = 504
Mr = 264.96	Dx = 2.072 Mg m−3
Monoclinic, P21/c	Melting point = 358–360 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 9.2955 (19) Å	Cell parameters from 10219 reflections
b = 12.980 (3) Å	θ = 2.8–30.4°
c = 7.5288 (15) Å	µ = 9.47 mm−1
β = 110.75 (3)°	T = 293 K
V = 849.5 (3) Å3	Platelet, colourless
Z = 4	0.28 × 0.26 × 0.12 mm

Data collection

Nonius KappaCCD diffractometer	2480 independent reflections
Radiation source: fine-focus sealed tube	1923 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.048
ω and Phi scan	θmax = 30.4°, θmin = 2.8°
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	h = −11→13
Tmin = 0.088, Tmax = 0.321	k = −17→14
10219 measured reflections	l = −10→8

Refinement

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.044	H-atom parameters constrained
wR(F2) = 0.119	w = 1/[σ2(Fo2) + (0.0467P)2 + 1.3504P] where P = (Fo2 + 2Fc2)/3
S = 1.04	(Δ/σ)max < 0.001
2480 reflections	Δρmax = 0.99 e Å−3
92 parameters	Δρmin = −1.06 e Å−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.036 (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
Br1	0.97970 (5)	0.13488 (4)	0.59690 (7)	0.0698 (2)
Br2	0.17000 (5)	0.07677 (4)	0.10894 (7)	0.0696 (2)
N1	0.5656 (3)	0.1307 (2)	0.3525 (4)	0.0461 (6)
C1	0.6810 (4)	0.1899 (3)	0.3462 (5)	0.0447 (7)
C2	0.6751 (4)	0.2963 (3)	0.3423 (5)	0.0509 (8)
H2	0.7580	0.3347	0.3371	0.061*
C3	0.5438 (5)	0.3448 (3)	0.3464 (6)	0.0560 (9)
H3	0.5369	0.4162	0.3454	0.067*
C4	0.4230 (4)	0.2844 (3)	0.3521 (5)	0.0535 (9)
H4	0.3329	0.3148	0.3536	0.064*
C5	0.4380 (4)	0.1781 (3)	0.3554 (5)	0.0479 (8)
C6	0.8218 (4)	0.1350 (4)	0.3439 (6)	0.0559 (9)
H6A	0.8610	0.1688	0.2555	0.067*
H6B	0.7957	0.0646	0.3015	0.067*
C7	0.3117 (5)	0.1099 (4)	0.3646 (6)	0.0646 (11)
H7A	0.2560	0.1441	0.4350	0.078*
H7B	0.3552	0.0468	0.4310	0.078*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Br1	0.0465 (3)	0.0867 (4)	0.0672 (3)	0.01422 (19)	0.00885 (19)	−0.0045 (2)
Br2	0.0558 (3)	0.0711 (3)	0.0710 (3)	−0.01709 (19)	0.0091 (2)	0.0004 (2)
N1	0.0412 (15)	0.0523 (16)	0.0429 (15)	0.0000 (12)	0.0127 (12)	0.0034 (12)
C1	0.0419 (16)	0.0556 (19)	0.0357 (15)	0.0006 (14)	0.0127 (13)	0.0011 (13)
C2	0.0466 (18)	0.056 (2)	0.0481 (19)	−0.0040 (15)	0.0141 (15)	0.0016 (15)
C3	0.057 (2)	0.052 (2)	0.052 (2)	0.0039 (16)	0.0115 (17)	−0.0016 (16)
C4	0.0417 (17)	0.070 (2)	0.0460 (18)	0.0105 (16)	0.0117 (14)	−0.0023 (16)
C5	0.0382 (16)	0.065 (2)	0.0374 (16)	−0.0015 (14)	0.0100 (13)	0.0030 (15)
C6	0.0458 (19)	0.072 (3)	0.052 (2)	0.0069 (17)	0.0199 (16)	0.0008 (17)
C7	0.048 (2)	0.092 (3)	0.055 (2)	−0.010 (2)	0.0190 (18)	0.008 (2)

Geometric parameters (Å, º)

Br1—C6	1.950 (4)	C3—H3	0.9300
Br2—C7	1.956 (4)	C4—C5	1.387 (6)
N1—C1	1.334 (4)	C4—H4	0.9300
N1—C5	1.343 (5)	C5—C7	1.491 (5)
C1—C2	1.382 (6)	C6—H6A	0.9700
C1—C6	1.496 (5)	C6—H6B	0.9700
C2—C3	1.383 (6)	C7—H7A	0.9700
C2—H2	0.9300	C7—H7B	0.9700
C3—C4	1.382 (6)
C1—N1—C5	117.5 (3)	N1—C5—C7	116.3 (4)
N1—C1—C2	123.4 (3)	C4—C5—C7	121.1 (4)
N1—C1—C6	116.3 (3)	C1—C6—Br1	110.4 (3)
C2—C1—C6	120.3 (4)	C1—C6—H6A	109.6
C1—C2—C3	118.8 (4)	Br1—C6—H6A	109.6
C1—C2—H2	120.6	C1—C6—H6B	109.6
C3—C2—H2	120.6	Br1—C6—H6B	109.6
C4—C3—C2	118.4 (4)	H6A—C6—H6B	108.1
C4—C3—H3	120.8	C5—C7—Br2	110.6 (3)
C2—C3—H3	120.8	C5—C7—H7A	109.5
C3—C4—C5	119.2 (3)	Br2—C7—H7A	109.5
C3—C4—H4	120.4	C5—C7—H7B	109.5
C5—C4—H4	120.4	Br2—C7—H7B	109.5
N1—C5—C4	122.6 (3)	H7A—C7—H7B	108.1
C5—N1—C1—C2	0.0 (5)	C1—N1—C5—C7	−179.4 (3)
C5—N1—C1—C6	179.7 (3)	C3—C4—C5—N1	−0.3 (6)
N1—C1—C2—C3	0.4 (6)	C3—C4—C5—C7	179.0 (4)
C6—C1—C2—C3	−179.4 (3)	N1—C1—C6—Br1	−100.1 (3)
C1—C2—C3—C4	−0.7 (6)	C2—C1—C6—Br1	79.7 (4)
C2—C3—C4—C5	0.6 (6)	N1—C5—C7—Br2	−91.3 (4)
C1—N1—C5—C4	0.0 (5)	C4—C5—C7—Br2	89.4 (4)