6-Bromo-4-oxo-4H-chromene-3-carb­alde­hyde

Yoshinobu Ishikawa

doi:10.1107/S160053681400796X

. 2014 Apr 16;70(Pt 5):o555. doi: 10.1107/S160053681400796X

6-Bromo-4-oxo-4H-chromene-3-carbaldehyde

Yoshinobu Ishikawa ^a,^*

PMCID: PMC4011302 PMID: 24860363

Abstract

In the title compound, C₁₀H₅BrO₃, a brominated 3-formylchromone derivative, the non-H atoms are essentially coplanar (r.m.s. deviation = 0.0420 Å), with the largest deviation from its mean plane [0.109 (2) Å] being found for the ring-bound carbonyl O atom. In the crystal, molecules are linked through halogen bonds [Br⋯O = 3.191 (2) Å, C—Br⋯O = 167.32 (10)° and C=O⋯Br = 168.4 (2)°] along [101]. Molecules are assembled into layers parallel to (101) via π–π stacking interactions along the b axis [shortest centroid–centroid distance between the pyran and benzene rings = 3.495 (2) Å].

Related literature

For related structures, see: Ishikawa & Motohashi (2013 ▶); Ishikawa (2014a ▶,b ▶). For halogen bonding, see: Auffinger et al. (2004 ▶); Metrangolo et al. (2005 ▶); Wilcken et al. (2013 ▶); Sirimulla et al. (2013 ▶).

Experimental

Crystal data

C₁₀H₅BrO₃
M _r = 253.05
Triclinic,
a = 6.5743 (18) Å
b = 6.967 (3) Å
c = 10.350 (4) Å
α = 71.02 (3)°
β = 85.53 (3)°
γ = 70.67 (3)°
V = 422.8 (3) Å³
Z = 2
Mo Kα radiation
μ = 4.85 mm⁻¹
T = 100 K
0.42 × 0.40 × 0.38 mm

Data collection

Rigaku AFC-7R diffractometer
Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.135, T _max = 0.159
2389 measured reflections
1944 independent reflections
1880 reflections with F ² > 2σ(F ²)
R _int = 0.024
3 standard reflections every 150 reflections intensity decay: 2.0%

Refinement

R[F ² > 2σ(F ²)] = 0.030
wR(F ²) = 0.077
S = 1.16
1944 reflections
128 parameters
H-atom parameters constrained
Δρ_max = 1.05 e Å⁻³
Δρ_min = −0.74 e Å⁻³

Data collection: WinAFC Diffractometer Control Software (Rigaku, 1999 ▶); cell refinement: WinAFC Diffractometer Control Software; data reduction: WinAFC Diffractometer Control Software; program(s) used to solve structure: SIR92 (Altomare, et al., 1994 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: CrystalStructure (Rigaku, 2010 ▶); software used to prepare material for publication: CrystalStructure.

Supplementary Material

Crystal structure: contains datablock(s) General, I. DOI: 10.1107/S160053681400796X/tk5306sup1.cif

e-70-0o555-sup1.cif^{(22.9KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681400796X/tk5306Isup2.hkl

e-70-0o555-Isup2.hkl^{(95.7KB, hkl)}

Click here for additional data file.^{(3.3KB, cml)}

Supporting information file. DOI: 10.1107/S160053681400796X/tk5306Isup3.cml

CCDC reference: 996416

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

Acknowledgments

The author acknowledges the University of Shizuoka for instrumental support.

supplementary crystallographic information

1. Structural commentary

Halogen bonds have been found to occur in organic, inorganic, and biological systems, and have recently attracted much attention in medicinal chemistry, chemical biology and supramolecular chemistry (Auffinger et al., 2004, Metrangolo et al., 2005, Wilcken et al., 2013, Sirimulla et al., 2013). We have recently reported the crystal structures of dihalogenated 3-formylchromone derivatives 6,8-dichloro-4-oxo-4H-chromene-3-carbaldehyde (Ishikawa & Motohashi, 2013, Fig.3 (top left)) and 6,8-dibromo-4-oxo-4H-chromene-3-carbaldehyde (Ishikawa, 2014a, Fig.3 (top right)). It was found that halogen bonds between the formyl oxygen atom and the halogen atoms at 8-position are formed in those crystals in a similar fashion. On the other hand, halogen bond is not observed between any oxygen atom and the chlorine atom at 6-position in the crystal structure of 6-chloro-4-oxo-4H-chromene-3-carbaldehyde (Ishikawa, 2014b, Fig.3 (bottom left)). As part of our interest in this type of chemical bonding, we herein report the crystal structure of a monobrominated 3-formylchromone derivative 6-bromo-4-oxo-4H-chromene-3-carbaldehyde. The objective of this study is to reveal whether halogen bond(s) can be formed in the crystal structure of the title compound with the bromine atom at 6-position and without a halogen atom at 8-position.

The mean deviation of the least-square planes for the non-hydrogen atoms is 0.0420 Å, and the largest deviation is 0.109 (2) Å for O2. These mean that these atoms are essentially coplanar (Fig.1).

In the crystal, the molecules are stacked with the inversion-symmetry equivalentⁱ along the b-axis direction [shortest centroid–centroid distance between the pyran and benzene rings of the 4H-chromene units = 3.495 (2) Å, i: -x + 1, -y + 1, -z + 1], as shown in Fig. 1. The Cg–Cg distance of the title compound is almost equal to that of 6-chloro-4-oxo-4H-chromene-3-carbaldehyde (3.4959 (15) Å, Ishikawa, 2014b).

Halogen bond was observed between the bromine atom at 6-position and the formyl oxygen atom of the translation-symmetry equivalentⁱⁱ [Br1···O3ⁱⁱ = 3.191 (2) Å, ii: x - 1, y, z + 1] along [101], as shown in Fig.2. The angles of C–Br···O and Br···O=C are 167.32 (10) and 168.4 (2)°, respectively. Thus, it is found that halogen bonds are formed for the bromine atoms not only at 8-position but also at 6-position, as shown in the top right and bottom right of Fig.3.

The space group and crystal packing mode of the title compound are the same with those of 6-chloro-4-oxo-4H-chromene-3-carbaldehyde. On the other hand, halogen bond is observed in the former and not in the latter, as shown in the bottom of Fig.3. These should be accounted for by the larger size of the σ hole of the bromine atom at 6-position (Wilcken et al., 2013). These results might be applicable for rational drug design.

2. Synthesis and crystallization

Single crystals suitable for X-ray diffraction were obtained by slow evaporation of an N,N-dimethylformamide solution of the commercially available title compound at room temperature.

3. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. The C(sp²)-bound hydrogen atoms were placed in geometrical positions [C–H 0.95 Å, U_iso(H) = 1.2U_eq(C)], and refined using a riding model.