3-Amino-5-bromo-2-iodo­pyridine

Abstract

The reaction of 3-amino-5-bromo­pyridine with N-iodo­succinimide in the presence of acetic acid produces the title compound, C₅H₄BrIN, with an iodo substituent in position 2 of the pyridine ring. The crystal structure features rather weak inter­molecular N—H⋯N hydrogen bonds linking the mol­ecules into chains along the z axis of the crystal.

Related literature

For structures of ortho-iodo­anilines, see: McWilliam et al. (2001 ▶); Sandor & Foxman (2000 ▶); Parkin et al. (2005 ▶).

Experimental

Crystal data

• C₅H₄BrIN₂

• M _r = 298.90

• Monoclinic,

• a = 4.0983 (12) Å

• b = 15.172 (4) Å

• c = 12.038 (3) Å

• β = 90.152 (5)°

• V = 748.5 (3) ų

• Z = 4

• Mo Kα radiation

• μ = 9.53 mm⁻¹

• T = 100 (2) K

• 0.40 × 0.33 × 0.04 mm

Data collection

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 2001 ▶) T _min = 0.234, T _max = 0.557

• 3783 measured reflections

• 1251 independent reflections

• 1086 reflections with I > 2σ(I)

• R _int = 0.037

Refinement

• R[F ² > 2σ(F ²)] = 0.032

• wR(F ²) = 0.082

• S = 1.05

• 1251 reflections

• 82 parameters

• H-atom parameters constrained

• Δρ_max = 1.33 e Å⁻³

• Δρ_min = −0.92 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2A⋯N1i	0.88	2.16	3.025 (8)	166
N2—H2B⋯I1	0.88	2.79	3.259 (5)	115

Symmetry code: (i) .

supplementary crystallographic information

Comment

The reaction of 5-bromo-3-aminopyridine with N-iodosuccinimide in the presence of acetic acid leads to iodo-substitution at position 2 of the pyridine ring, as shown by the X-ray study of the title compound (Fig. 1). To the best of our knowledge, this is the first structure of ortho-iodoaminopyridine derivative. The N2···I1 distance 3.259 (5) Å is typical for ortho-iodoanilines (McWilliam et al., 2001; Sandor & Foxman, 2000; Parkin et al., 2005) and may suggest involvement of the H2B atom in weak intramolecular N2—H2B···I1 interaction (Table 1).

The second `active' H-atom, H2A, participates in the intermolecular H-bond N2—H2A···N1ⁱ (symmetry code (i): x, 1/2 - y, z - 1/2; Table 1), which links the molecules into the chains along the z-axis of the crystal (Fig. 2). There are no strong halogen···halogen interactions in the structure; the shortest intermolecular I···I distances are 4.091 (1) Å and 4.098 (1) Å.

Experimental

To a solution of 3-amino-5-bromopyridine (100 mg, 0.56 mmol) in acetic acid (0.1 M, 5.61 ml) was added N-iodosuccinimide (133 mg, 0.56 mmol) at rt. After 3 h, the reaction was quenched with sat. sodium bicarbonate and extracted 3 times with EtOAc. The organic layers were combined, dried, filtered, and concentrated. The crude residue was subjected to flash chromatography (silica gel, 0–50% EtOAc/heptane). Isolated 93 mg (55%) of 3-amino-5-bromo-2-iodopyridine, as a brown solid. X-ray quality crystals were obtained by slow evaporation of a concentrated chromatography fraction (approx. 30% EtOAc/heptane). ¹H NMR (400 MHz, DMSO-d₆) (δ p.p.m.) 5.65 (s, 2 H), 7.16 (d, J = 2.27 Hz, 1 H), 7.67 (d, J = 2.01 Hz, 1 H). ¹³C NMR (101 MHz, DMSO-d₆) (δ p.p.m.) 106.10, 120.01, 120.92, 137.97, 147.68.

Refinement

All H atoms were treated as riding with the C—H and N—H distances of 0.95 Å and 0.88 Å respectively; the U_iso(H) were set to 1.2U_eq of the carrying atom.

Figures

Fig. 1.

Molecular structure of the title compound, showing 50% probability displacement ellipsoids and atom numbering scheme. H atoms are drawn as circles with arbitrary small radius.

Fig. 2.

The crystal packing diagram viewed down the x-axis.

Crystal data

C5H4BrIN2	F(000) = 544
Mr = 298.90	Dx = 2.652 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 2536 reflections
a = 4.0983 (12) Å	θ = 2.7–25.3°
b = 15.172 (4) Å	µ = 9.53 mm−1
c = 12.038 (3) Å	T = 100 K
β = 90.152 (5)°	Plate, colourless
V = 748.5 (3) Å3	0.40 × 0.33 × 0.04 mm
Z = 4

Data collection

Bruker APEXII CCD diffractometer	1251 independent reflections
Radiation source: fine-focus sealed tube	1086 reflections with I > 2σ(I)
graphite	Rint = 0.037
φ and ω scans	θmax = 25.3°, θmin = 2.2°
Absorption correction: analytical (SADABS; Bruker, 2001)	h = −4→1
Tmin = 0.234, Tmax = 0.557	k = −17→18
3783 measured reflections	l = −10→14

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)] = 0.032	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.082	H-atom parameters constrained
S = 1.05	w = 1/[σ2(Fo2) + (0.037P)2 + 2.524P] where P = (Fo2 + 2Fc2)/3
1251 reflections	(Δ/σ)max = 0.003
82 parameters	Δρmax = 1.33 e Å−3
0 restraints	Δρmin = −0.92 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
I1	0.18405 (10)	0.37509 (3)	0.48761 (3)	0.02516 (17)
Br1	−0.56202 (16)	0.01782 (4)	0.28399 (5)	0.0266 (2)
N2	−0.0278 (15)	0.3306 (4)	0.2326 (4)	0.0298 (13)
H2A	−0.0808	0.3282	0.1617	0.036*
H2B	0.0760	0.3769	0.2589	0.036*
N1	−0.1133 (14)	0.1994 (4)	0.4858 (4)	0.0264 (13)
C2	−0.2684 (18)	0.1278 (4)	0.4470 (6)	0.0264 (15)
H2	−0.3243	0.0815	0.4965	0.032*
C1	−0.0390 (15)	0.2637 (5)	0.4165 (5)	0.0242 (14)
C5	−0.1071 (15)	0.2622 (5)	0.3019 (5)	0.0227 (14)
C3	−0.3480 (16)	0.1208 (4)	0.3350 (5)	0.0221 (14)
C4	−0.2713 (15)	0.1878 (4)	0.2636 (5)	0.0213 (14)
H4	−0.3303	0.1834	0.1874	0.026*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
I1	0.0244 (3)	0.0324 (3)	0.0187 (3)	−0.00094 (16)	−0.00522 (18)	−0.00340 (17)
Br1	0.0285 (4)	0.0274 (4)	0.0238 (4)	−0.0007 (3)	−0.0039 (3)	−0.0027 (3)
N2	0.044 (4)	0.029 (3)	0.016 (3)	−0.002 (3)	−0.008 (3)	−0.001 (2)
N1	0.035 (3)	0.030 (3)	0.015 (3)	0.002 (2)	−0.005 (2)	0.002 (2)
C2	0.035 (4)	0.024 (4)	0.020 (3)	0.000 (3)	−0.007 (3)	0.002 (3)
C1	0.017 (3)	0.036 (4)	0.020 (3)	0.004 (3)	−0.006 (3)	−0.008 (3)
C5	0.017 (3)	0.035 (4)	0.016 (3)	0.006 (3)	−0.001 (2)	−0.002 (3)
C3	0.021 (4)	0.027 (4)	0.018 (3)	0.005 (3)	−0.001 (3)	−0.001 (3)
C4	0.021 (3)	0.033 (4)	0.011 (3)	0.007 (3)	−0.005 (2)	−0.006 (3)

Geometric parameters (Å, °)

I1—C1	2.102 (7)	C2—C3	1.390 (9)
Br1—C3	1.894 (7)	C2—H2	0.9500
N2—C5	1.371 (9)	C1—C5	1.407 (9)
N2—H2A	0.8800	C5—C4	1.393 (9)
N2—H2B	0.8800	C3—C4	1.368 (9)
N1—C1	1.320 (9)	C4—H4	0.9500
N1—C2	1.342 (9)
C5—N2—H2A	120.0	N2—C5—C4	121.8 (5)
C5—N2—H2B	120.0	N2—C5—C1	122.6 (6)
H2A—N2—H2B	120.0	C4—C5—C1	115.6 (6)
C1—N1—C2	119.3 (5)	C4—C3—C2	119.9 (6)
N1—C2—C3	120.6 (6)	C4—C3—Br1	121.1 (5)
N1—C2—H2	119.7	C2—C3—Br1	119.0 (5)
C3—C2—H2	119.7	C3—C4—C5	120.4 (6)
N1—C1—C5	124.2 (6)	C3—C4—H4	119.8
N1—C1—I1	116.0 (4)	C5—C4—H4	119.8
C5—C1—I1	119.8 (5)

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···N1i	0.88	2.16	3.025 (8)	166
N2—H2B···I1	0.88	2.79	3.259 (5)	115

Symmetry codes: (i) x, −y+1/2, z−1/2.