2,7-Bis­(trichloro­meth­yl)-1,8-naphthyridine

The complete mol­ecule of the title compound, C₁₀H₄Cl₆N₂, is generated by crystallographic twofold symmetry, with two C atoms lying on the rotation axis; the 1,8-naphthyridine ring is almost planar with an r.m.s. deviation of 0.0002 Å. In the crystal structure, the mol­ecules are stacked in an anti­parallel manner along [001]. Short Cl...Cl [3.3502 (4)] and Cl...N [3.2004 (11)–3.2220 (10) Å] contacts are observed in the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.035
• wR factor = 0.089
• Data-to-parameter ratio = 44.1

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600          7

Alert level G
PLAT764_ALERT_4_G Overcomplete CIF Bond List Detected (Rep/Expd) .       1.18 Ratio

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The substituted 1,8-naphthyridine compounds have been studied for their chemical and biological activities for a long time. They show various biological activities such as antibacterial (Chen et al., 2001; Ferrarini et al., 1998), anti-inflammatory (Braccio et al., 2008) as well as antihypertensive (Ferrarini et al., 2000) properties. Trichloromethyl-substituted heterocyclic compounds are of great importance due to their broad spectrum biological activities. These interesting properties prompt us to synthesise the title compound (I) and its crystal structure was reported.

The asymmetric unit of the title molecule (Fig. 1), C₁₀H₄Cl₆N₂, contains one half-molecule with two shared C atoms (C3 and C4) lying on a twofold rotation axis. The 1,8-naphthyridine ring is planar with the r.m.s. deviation of 0.0002 (2) Å. One Cl atom (Cl3) of the trichloromethyl substitutent is co-planar with the 1,8-naphthyridine ring which can be indicated by the torsion angle C1–C2–C6–Cl3 = 1.85 (14) Å whereas the other two Cl atoms are in the (+)-anti-clinal and (-)-anti-clinal configurations with the torsion angles C1–C2–C6–Cl1 = 122.04 (10)° and C1–C2–C6–Cl2 = -119.02 (10)°, respectively. The C1—H1···Cl3 intramolecular interaction (Table 1) generates S(5) ring motif (Bernstein et al., 1995). The bond distances are of normal values (Allen et al., 1987) and are comparable with related structures (Fun et al., 2009; Wang et al., 2008).

In the crystal structure (Fig. 2), the non-covalent interactions play a significant role in the three-dimensional supramolecular architecture in which the molecules are stacked in an antiparallel manner along the [0 0 1] direction and the neighbouring molecules are interlinked by C—Cl···Cl interactions into polymeric chains along the [0 1 0] direction. The molecules are also consolidated by Cl···Cl [3.3502 (4)Å] and Cl···N [3.2004 (11)–3.2220 (10) Å] short contacts. π···π interactions were observed with the distances of Cg₁···Cg₁ = 4.2360 (6) Å (symmetry code: -x, 1 - y, 2 - z) and Cg₂···Cg₂ = 4.2360 (6) Å (symmetry code: -x, 1 - y, 1 - z): Cg₁ and Cg₂ are the centroids of C1–C4/C5A/N1 and C1A–C2A/C3–C5/N1A, respectively. All these interactions connect the molecules into a three-dimensional supramolecular network.

Related literature

For bond-length data, see: Allen et al. (1987). For graph-set notation of hydrogen-bond motifs, see: Bernstein et al. (1995). For related structures, see: Fun et al. (2009); Wang et al. (2008). For background to the properties and applications of 1,8-naphthyridine, see: Braccio et al. (2008); Chen et al. (2001); Ferrarini et al. (1998; 2000). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).

S2. Experimental

A mixture of N-chlorosuccinimide (500 mg, 4.5 mmol) and triphenylphosphine (500 mg, 4.2 mmol) was moistened with CCl₄ (60 ml) in a round bottom flask and stirred at room temperature for 25 min. A solution of 2,7-dimethyl-1,8-naphthyridine (0.9 g, 5.25 mmol) was added to the suspension and the reaction mixture was stirred and heated under reflux for 7 hr. The solution was cooled and filtered. The evaporated filtrate was washed with saturated aqueous Na₂CO₃ and extracted repeatedly with CHCl₃. Drying over anhydrous Na₂SO₄, the solvent was removed under reduced pressure. The crude product was purified with SiO₂ chromatography (eluted with 1% ethylacetate in petroleum ether) to give the title compound as a white crystalline solid. Colorless slabs of (I) were recrystalized from CH₂Cl₂:hexane (1:10, v/v) by the slow evaporation of the solvent at room temperature after a week.

S3. Refinement

H atoms were located in a difference maps and refined isotropically. The highest residual electron density peak is located at 1.72 Å from H6 and the deepest hole is located at 0.65 Å from Cl2.

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

	Fig. 1. The molecular structure of (I) showing 50% probability displacement ellipsoids. Atoms with suffix A were generated by symmetry code -x, y, -1/2 - z.
	Fig. 2. The crystal packing of the title compound viewed along the b axis, N···Cl and C···.Cl short contacts are shown as dashed lines.

2,7-Bis(trichloromethyl)-1,8-naphthyridine

Crystal data

C10H4Cl6N2	F(000) = 720
Mr = 364.85	Dx = 1.870 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 4010 reflections
a = 19.9154 (4) Å	θ = 2.2–40.0°
b = 6.5977 (1) Å	µ = 1.30 mm^−1
c = 10.5975 (2) Å	T = 100 K
β = 111.483 (2)°	Slab, colorless
V = 1295.73 (4) Å^3	0.40 × 0.26 × 0.05 mm
Z = 4

Data collection

Bruker APEXII CCD diffractometer	4010 independent reflections
Radiation source: sealed tube	3136 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.053
ϕ and ω scans	θmax = 40.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −36→34
Tmin = 0.624, Tmax = 0.944	k = −11→11
28872 measured reflections	l = −18→19

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.089	All H-atom parameters refined
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0403P)^2 + 0.889P] where P = (Fo^2 + 2Fc^2)/3
4010 reflections	(Δ/σ)max = 0.002
91 parameters	Δρmax = 0.64 e Å^−3
0 restraints	Δρmin = −0.56 e Å^−3

Special details

Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 120.0 (1) K.

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
Cl1	0.090117 (15)	0.01827 (4)	1.12884 (3)	0.01585 (6)
Cl2	0.194324 (15)	0.02817 (4)	0.99732 (3)	0.01645 (6)
Cl3	0.202697 (15)	0.31574 (4)	1.20815 (3)	0.01848 (6)
N1	0.04657 (5)	0.21807 (14)	0.85379 (9)	0.01358 (15)
C1	0.09721 (6)	0.53166 (17)	0.96675 (12)	0.01599 (18)
C2	0.09266 (6)	0.31794 (16)	0.95656 (11)	0.01302 (16)
C3	0.0000	0.3281 (2)	0.7500	0.0124 (2)
C4	0.0000	0.5430 (2)	0.7500	0.0136 (2)
C5	−0.05049 (6)	0.64457 (17)	0.63741 (11)	0.01611 (18)
C6	0.14272 (6)	0.17959 (16)	1.06796 (10)	0.01333 (16)
H6	−0.0513 (10)	0.788 (3)	0.6355 (18)	0.021 (4)*
H1	0.1292 (10)	0.598 (3)	1.038 (2)	0.024 (5)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.01798 (11)	0.01518 (11)	0.01362 (10)	−0.00263 (8)	0.00487 (8)	0.00164 (8)
Cl2	0.01578 (11)	0.01700 (12)	0.01533 (11)	0.00202 (8)	0.00425 (8)	0.00040 (8)
Cl3	0.02005 (12)	0.01629 (11)	0.01330 (11)	−0.00383 (9)	−0.00076 (8)	−0.00181 (8)
N1	0.0155 (4)	0.0114 (3)	0.0115 (3)	−0.0004 (3)	0.0021 (3)	0.0002 (3)
C1	0.0186 (4)	0.0110 (4)	0.0152 (4)	−0.0022 (3)	0.0025 (4)	−0.0012 (3)
C2	0.0145 (4)	0.0113 (4)	0.0123 (4)	−0.0008 (3)	0.0038 (3)	0.0001 (3)
C3	0.0137 (5)	0.0101 (5)	0.0117 (5)	0.000	0.0027 (4)	0.000
C4	0.0173 (6)	0.0095 (5)	0.0132 (5)	0.000	0.0045 (5)	0.000
C5	0.0198 (5)	0.0104 (4)	0.0155 (4)	0.0011 (3)	0.0033 (4)	0.0009 (3)
C6	0.0148 (4)	0.0122 (4)	0.0113 (4)	−0.0015 (3)	0.0028 (3)	−0.0007 (3)

Geometric parameters (Å, º)

Cl1—C6	1.7725 (11)	C2—C6	1.5358 (15)
Cl2—C6	1.7827 (11)	C3—N1^i	1.3602 (12)
Cl3—C6	1.7723 (10)	C3—C4	1.418 (2)
N1—C2	1.3156 (14)	C4—C5	1.4160 (13)
N1—C3	1.3602 (12)	C4—C5^i	1.4160 (13)
C1—C5^i	1.3736 (16)	C5—C1^i	1.3737 (16)
C1—C2	1.4145 (15)	C5—H6	0.95 (2)
C1—H1	0.90 (2)
C2—N1—C3	117.68 (10)	C5—C4—C3	118.24 (7)
C5^i—C1—C2	118.28 (10)	C5^i—C4—C3	118.24 (7)
C5^i—C1—H1	118.1 (14)	C1^i—C5—C4	118.91 (11)
C2—C1—H1	123.6 (14)	C1^i—C5—H6	121.6 (11)
N1—C2—C1	124.62 (10)	C4—C5—H6	119.5 (11)
N1—C2—C6	113.48 (9)	C2—C6—Cl3	113.05 (7)
C1—C2—C6	121.90 (9)	C2—C6—Cl1	109.44 (7)
N1—C3—N1^i	115.46 (13)	Cl3—C6—Cl1	107.82 (6)
N1—C3—C4	122.27 (6)	C2—C6—Cl2	108.79 (7)
N1^i—C3—C4	122.27 (6)	Cl3—C6—Cl2	108.72 (6)
C5—C4—C5^i	123.51 (14)	Cl1—C6—Cl2	108.95 (6)
C3—N1—C2—C1	0.00 (16)	N1^i—C3—C4—C5^i	179.98 (8)
C3—N1—C2—C6	−179.95 (8)	C5^i—C4—C5—C1^i	180.00 (13)
C5^i—C1—C2—N1	−0.02 (19)	C3—C4—C5—C1^i	0.00 (13)
C5^i—C1—C2—C6	179.92 (11)	N1—C2—C6—Cl3	−178.20 (8)
C2—N1—C3—N1^i	−179.98 (11)	C1—C2—C6—Cl3	1.85 (14)
C2—N1—C3—C4	0.02 (11)	N1—C2—C6—Cl1	−58.01 (11)
N1—C3—C4—C5	179.98 (8)	C1—C2—C6—Cl1	122.04 (10)
N1^i—C3—C4—C5	−0.02 (8)	N1—C2—C6—Cl2	60.93 (11)
N1—C3—C4—C5^i	−0.02 (8)	C1—C2—C6—Cl2	−119.02 (10)

Symmetry code: (i) −x, y, −z+3/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1···Cl3	0.90 (2)	2.63 (2)	3.0085 (12)	106.0 (14)