Two different modes of halogen bonding in two 4-nitro­imidazole derivatives

In the crystal structures of the two imidazole derivatives 5-chloro-1,2-dimethyl-4-nitro-1H-imidazole, C₅H₆ClN₃O₂, (I), and 2-chloro-1-methyl-4-nitro-1H-imidazole, C₄H₄ClN₃O₂, (II), C-Cl...O halogen bonds are the principal specific inter­actions responsible for the crystal packing. Two different halogen-bond modes are observed: in (I), there is one very short and directional C-Cl...O contact [Cl...O = 2.899 (1) Å], while in (II), the C-Cl group approaches two different O atoms from two different mol­ecules, and the contacts are longer [3.285 (2) and 3.498 (2) Å] and less directional. In (I), relatively short C-H...O hydrogen bonds provide the secondary inter­actions for building the crystal structure; in (II), the C-H...O contacts are longer but there is a relatively short [pi]-[pi] contact between mol­ecules related by a centre of symmetry. The mol­ecule of (I) is almost planar, the plane of the nitro group making a dihedral angle of 6.97 (7)° with the mean plane of the imidazole ring. The mol­ecule of (II) has crystallographically imposed mirror symmetry and the nitro group lies in the mirror plane.

S1. Comment

Halogen atoms covalently bound to a C atom can take part in the determination of a crystal structure (i.e. the supramolecular architecture of molecular crystals) via interactions with the electron pairs of other atoms, interactions with other halogen atoms or acceptance of weak hydrogen bonds. The attractive interactions between halogens and atoms that have lone electron pairs have been known for some time (e.g. Hassel & Rømming, 1962; Bent, 1968; Dahl & Hassel, 1970; Hassel, 1970). This interaction was termed halogen bonding (Dumas et al., 1983; Legon, 1998), in order to stress some geometrical correspondences with hydrogen bonding, for instance the striking tendency towards the linearity of the C—X···Y system [for reviews, see, for example, Legon (1999) and Metrangolo et al. (2005)]. The halogen atom acts here as a Lewis acid. Database analysis (Lommerse et al., 1996) and quantum mechanical calculations (Valerio et al., 2000) allowed the `acidicity' of halogens to be defined as I > Br > Cl, while fluorine generally does not participate in such interactions. Halogen bonds have been utilized successfully in the creation of supramolecular systems; for example, it hass been shown that these interactions can create molecular tapes (Reddy, Panneerselvam et al., 1993) or a diamondoid structure (Reddy, Craig et al., 1993). They have also been used for designing molecular conductors (Imakubo et al., 1998), host–guest systems (Messina et al., 2001) and nonlinear optical crystals (George et al., 2004). N···X intermolecular interactions have also been found in solution (Wash et al., 1999) and in the gas phase (Legon, 1999). Quite recently, experimental electron density studies have clearly shown the presence of an interaction path and critical points connected with I···N and I···O interactions, and the results of these studies confirmed the electrostatic nature of halogen bonds (Bianchi et al., 2003, 2004).

Allen et al. (1997) analyzed the halogen···O_nitro supramolecular synthon [in the sense defined by Desiraju (1995)] using both a crystallographic database and ab initio molecular orbital calculations. They found that in 46% of the crystal structures containing both C—NO₂ and C—X (X = Cl, Br or I) fragments there are X···O contacts shorter than sum of the van der Waals radii plus 0.2 Å. Following Desiraju et al. (1993), three types of halogen-bond system were defined. In the first two cases, the approach of a halogen atom to a nitro group is such that both X···O lines are trans to the C—N bond, forming (i) a symmetrical bifurcated motif, with X···O1 ≈ X···O2, or (ii) an asymmetric motif, where one of the distances is so long that there is no interaction. Possibility (iii) is a cis approach to one of the O atoms. The results of this analysis show also that for chlorine there is a strong tendency to form `monocoordinate interactions' (ii) or (iii), with only one O atom, rather than bifurcated contacts with both O atoms as in (i). This latter arrangement is typical for iodine and to some extent for bromine – such an almost symmetrical, bifurcated halogen bond was found in a similar imidazole derivative, 1-(4'-bromophenyl)-2-methyl-4-nitroimidazole (Kubicki, 2004).

In the course of our studies of weak intermolecular interactions in the crystal structures of simple 4-nitroimidazole derivatives (nitroimidazoles and especially chloronitroimidazoles can be used as radiosensitizers of hypoxic cells; e.g. Widel et al., 1987), we have determined the crystal structures two closely related compounds, viz. 5-chloro-1,2-dimethyl-4-nitroimidazole, (I), and 2-chloro-1-methyl-4-nitroimidazole, (II). In both these compounds, halogen bonds of the C—Cl···O_nitro type are the driving force of the supramolecular architecture.

In (I), the imidazole ring is planar, with a maximum deviation of 0.037 (6) Å, and the closest substituent atoms (i.e. except the O atoms) are almost coplanar with the ring [the maximum deviation from the plane, for C11 atom, is 0.059 (2) Å]. The nitro group is twisted by 6.97 (7)° with respect to the imidazole ring (Fig. 1). The molecule of (II) occupies a special position; it lies on a mirror plane and therefore is perfectly planar (Fig. 2). There are no traces of disorder or strangely shaped displacement ellipsoids, which might suggest the statistical nature of this mirror plane. The same is true at room temperature, so it seems that in this temperature range there is no phase transition (of order–disorder nature). The molecular dimensions are close to typical, with a notable influence of the type of substituents on the intramolecular angles N1—C2—N3 (Table 1). The typical asymmetry of the C—N—O angles can aslo be observed here (cf. Kubicki, 2005).

In both structures, C—Cl···O halogen bonds are the most important factor in the crystal packing. Noticeably, in neither of the structures does the imidazole N atom take part in the halogen bonding. This is in agreement with our observation (in high-resolution studies of the crystal structure of 1-phenyl-4-nitroimidazole) that the electron density of the lone pairs is higher at the O atoms than at the imidazole N atom (Kubicki et al., 2002).

The types of interaction are different in both cases. For description of the networks created by intermolecular interactions it will be useful to apply the graph-set notation (Etter et al., 1990; Bernstein et al., 1995). We will follow Bryant et al. (1998) and regard the Cl···O interactions as pseudo-hydrogen bonds, with Cl as a donor and O as an acceptor. In (I), there is one very short and linear interaction of the cis type (Fig. 3 and Table 2). It is actually one of the shortest interactions of this type found in the Cambridge Structural Database (CSD; Allen, 2002). This interaction should be classified as belonging to type (iii) of those listed earlier. These halogen bonds connect the molecules into infinite chains along the [010] direction. The motif created by these interactions can be described as C¹₁(5).

In (II), the interaction is of another kind. The C—Cl bond approaches two O atoms at moderate distances (Fig. 4 and Table 2), and both approaches are of cis type, because these two O atoms are from two different molecules. Therefore, it belongs – in principle – to type (iii), but the bifurcated nature of this contact allows to a creation of a subtype (iiia). In the CSD, we have found 69 hits with this motif. These halogen bonds connect molecules into two-dimensional layers in the ab plane (on a mirror plane of symmetry; Fig. 4). This structure is much more complicated than that in (I). There are first-rank (i.e. built of only one type of interactions) chains, viz. C¹₁(6) parallel to a and C¹₁(6) parallel to c. These chains interweave and produce second-rank (built of two different interactions) motifs, e.g. C²₂(8) chains along a and closed structures of the R⁴₃(16) type.

The halogen-bonded arrays are further expanded by means of weak C—H···O interactions (Table 2). In (I), these bonds connect neighboring chains into layers, closing consecutive R³₂(12) rings (Fig. 3). In this structure, additional π–π interactions between the imidazole rings connected by a center of symmetry create the bilayers. The distance between the centres of the rings (which are parallel by symmetry) is 3.314 (2) Å, and taking the offset into account the distance between the planes is 3.27 Å. In (II), the weak hydrogen bonds additionally strengthen the halogen-bonded layers, creating R²₂(8) ring motifs. The mirror planes occupied by these layers are b/2 apart (3.07 Å), but the layers are shifted in such a way that the ring planes do not overlap at all.

Related literature

For related literature, see: Allen (2002); Allen et al. (1997); Bent (1968); Bernstein et al. (1995); Bianchi et al. (2003, 2004); Bryant et al. (1998); Dahl & Hassel (1970); Desiraju (1995); Desiraju et al. (1993); Dumas et al. (1983); Etter et al. (1990); George et al. (2004); Hassel (1970); Hassel & Rømming (1962); Imakubo et al. (1998); Kubicki (2004, 2005); Kubicki et al. (2002); Legon (1998, 1999); Lommerse et al. (1996); Messina et al. (2001); Metrangolo et al. (2005); Reddy, Craig, Rae & Desiraju (1993); Reddy, Panneerselvam, Pilati & Desiraju (1993); Suwiński et al. (1982); Valerio et al. (2000); Wash et al. (1999); Widel et al. (1987).

S2. Experimental

The investigated compounds were synthesized from the corresponding dinitro compounds with high yield according to a previously described procedure (Suwiński et al., 1982).

S3. Refinement

H atoms were freely refined [C—H = 0.93 (2)–1.005 (18) Å in (I) and 0.90 (2)–1.01 (3) Å].

Computing details

For both compounds, data collection: CrysAlis CCD (Oxford Diffraction, 2002); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Stereochemical Workstation Operation Manual (Siemens, 1989); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. An anisotropic displacement ellipsoid representation of molecule (I) together with the atom-labelling scheme (Siemens, 1989). The ellipsoids are drawn at the 50% probability level; H atoms are depicted as spheres with arbitrary radii.
	Fig. 2. An anisotropic displacement ellipsoid representation of molecule (II), together with the atom-labelling scheme (Siemens, 1989). The ellipsoids are drawn at the 50% probability level; H atoms are depicted as spheres with arbitrary radii.
	Fig. 3. a. The layer created by halogen and weak hydrogen bonds in (I) (Siemens, 1989), as seen along the a direction. Intermolecular interactions are depicted as dashed lines. [Symmetry codes: (i) x, y, z; (ii) x, y, z - 1; (iii) x, y - 1, z; (iv) x, y - 1, z - 1; (v) x, y + 1, z; (vi) x, y + 1, z - 1.]
	Fig. 4. The layer created by halogen and weak hydrogen bonds in (II) (Siemens, 1989), as seen along the b direction. Intermolecular interactions are depicted as dashed lines. [Symmetry codes: (i) x, y, z; (ii) x, y, z + 1; (iii) x + 1/2, y, -z + 1/2; (iv) x + 1/2, y, -z + 3/2; (v) x + 1/2, y, -z + 5/2; (vi) x + 1, y, z; (vii) x + 1, y, z + 1; (viii) x + 3/2, y, -z + 3/2.]

(I) 5-chloro-1,2-dimethyl-4-nitro-1H-imidazole

Crystal data

C5H6ClN3O2	Z = 2
Mr = 175.58	F(000) = 180
Triclinic, P1	Dx = 1.642 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.8119 (10) Å	Cell parameters from 3226 reflections
b = 7.0301 (12) Å	θ = 3–24°
c = 8.5403 (13) Å	µ = 0.49 mm^−1
α = 66.631 (16)°	T = 100 K
β = 80.204 (13)°	Prism, colourless
γ = 71.305 (14)°	0.15 × 0.1 × 0.1 mm
V = 355.19 (10) Å^3

Data collection

Kuma KM-4 CCD four-circle diffractometer	1767 independent reflections
Radiation source: fine-focus sealed tube	1565 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.040
ω scan	θmax = 29.7°, θmin = 4.9°
Absorption correction: multi-scan (SORTAV; Blessing, 1989)	h = −9→7
Tmin = 0.895, Tmax = 0.944	k = −9→9
3402 measured reflections	l = −11→10

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)] = 0.025	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.066	All H-atom parameters refined
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0405P)^2 + 0.0188P] where P = (Fo^2 + 2Fc^2)/3
1767 reflections	(Δ/σ)max = 0.001
124 parameters	Δρmax = 0.34 e Å^−3
0 restraints	Δρmin = −0.38 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
O41	0.26846 (12)	0.53896 (13)	1.25138 (10)	0.01843 (18)
O42	0.30208 (14)	0.19580 (13)	1.32872 (9)	0.02147 (19)
N1	0.23778 (13)	0.35486 (14)	0.81620 (11)	0.01317 (19)
N3	0.25751 (13)	0.60016 (14)	0.91349 (11)	0.01369 (19)
N4	0.27849 (13)	0.38010 (14)	1.21856 (10)	0.01327 (19)
C2	0.24417 (15)	0.56380 (17)	0.77647 (13)	0.0135 (2)
C4	0.26228 (15)	0.40799 (16)	1.04567 (12)	0.0120 (2)
C5	0.24960 (15)	0.25364 (17)	0.99008 (13)	0.0129 (2)
C11	0.23175 (18)	0.2525 (2)	0.69795 (14)	0.0184 (2)
Cl5	0.24485 (4)	−0.00623 (4)	1.08825 (3)	0.01592 (10)
C21	0.23570 (18)	0.72487 (19)	0.59743 (14)	0.0196 (2)
H11A	0.356 (3)	0.145 (3)	0.700 (2)	0.041 (5)*
H11B	0.118 (3)	0.188 (3)	0.737 (2)	0.039 (4)*
H11C	0.207 (3)	0.359 (3)	0.588 (3)	0.045 (5)*
H21A	0.263 (3)	0.847 (3)	0.600 (2)	0.036 (4)*
H21B	0.336 (3)	0.667 (3)	0.527 (2)	0.041 (4)*
H21C	0.099 (3)	0.766 (3)	0.546 (2)	0.036 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0132 (4)	0.0141 (4)	0.0121 (4)	−0.0033 (3)	−0.0009 (3)	−0.0050 (3)
C11	0.0205 (5)	0.0218 (6)	0.0168 (5)	−0.0059 (5)	−0.0007 (4)	−0.0110 (5)
C2	0.0110 (4)	0.0141 (5)	0.0137 (5)	−0.0035 (4)	0.0001 (4)	−0.0037 (4)
C21	0.0232 (6)	0.0192 (6)	0.0135 (5)	−0.0070 (4)	−0.0020 (4)	−0.0015 (4)
N3	0.0133 (4)	0.0127 (4)	0.0133 (4)	−0.0035 (3)	−0.0010 (3)	−0.0030 (3)
C4	0.0117 (4)	0.0123 (5)	0.0112 (4)	−0.0033 (4)	0.0000 (3)	−0.0038 (4)
N4	0.0139 (4)	0.0141 (4)	0.0121 (4)	−0.0045 (3)	0.0003 (3)	−0.0051 (3)
O41	0.0254 (4)	0.0162 (4)	0.0169 (4)	−0.0055 (3)	−0.0014 (3)	−0.0095 (3)
O42	0.0338 (4)	0.0157 (4)	0.0131 (4)	−0.0087 (3)	−0.0027 (3)	−0.0014 (3)
C5	0.0111 (4)	0.0138 (5)	0.0128 (4)	−0.0035 (4)	0.0002 (3)	−0.0042 (4)
Cl5	0.01782 (15)	0.01159 (15)	0.01829 (15)	−0.00569 (10)	−0.00063 (10)	−0.00430 (10)

Geometric parameters (Å, º)

N1—C5	1.3724 (13)	C21—H21B	0.94 (2)
N1—C2	1.3839 (14)	C21—H21C	1.005 (18)
N1—C11	1.4660 (13)	N3—C4	1.3693 (14)
C11—H11A	0.93 (2)	C4—C5	1.3759 (15)
C11—H11B	0.964 (19)	C4—N4	1.4292 (13)
C11—H11C	0.94 (2)	N4—O41	1.2343 (12)
C2—N3	1.3157 (14)	N4—O42	1.2412 (12)
C2—C21	1.4961 (15)	C5—Cl5	1.6897 (11)
C21—H21A	0.944 (19)
C5—N1—C2	106.84 (8)	H21A—C21—H21B	109.5 (16)
C5—N1—C11	125.32 (9)	C2—C21—H21C	112.6 (10)
C2—N1—C11	127.75 (9)	H21A—C21—H21C	110.9 (15)
N1—C11—H11A	109.5 (11)	H21B—C21—H21C	106.2 (15)
N1—C11—H11B	107.6 (11)	C2—N3—C4	104.57 (8)
H11A—C11—H11B	109.6 (16)	N3—C4—C5	111.90 (9)
N1—C11—H11C	109.1 (12)	N3—C4—N4	121.96 (9)
H11A—C11—H11C	111.7 (17)	C5—C4—N4	126.15 (10)
H11B—C11—H11C	109.2 (16)	O41—N4—O42	123.20 (8)
N3—C2—N1	111.91 (9)	O41—N4—C4	118.86 (9)
N3—C2—C21	125.44 (10)	O42—N4—C4	117.94 (9)
N1—C2—C21	122.65 (9)	N1—C5—C4	104.78 (9)
C2—C21—H21A	107.5 (11)	N1—C5—Cl5	120.96 (8)
C2—C21—H21B	110.0 (11)	C4—C5—Cl5	134.26 (8)
C5—N1—C2—N3	−0.49 (11)	N3—C4—N4—O42	−173.15 (9)
C11—N1—C2—N3	−177.25 (10)	C5—C4—N4—O42	6.91 (15)
C5—N1—C2—C21	179.74 (9)	C2—N1—C5—C4	0.06 (11)
C11—N1—C2—C21	2.98 (16)	C11—N1—C5—C4	176.92 (9)
N1—C2—N3—C4	0.69 (11)	C2—N1—C5—Cl5	179.63 (7)
C21—C2—N3—C4	−179.54 (10)	C11—N1—C5—Cl5	−3.52 (14)
C2—N3—C4—C5	−0.66 (11)	N3—C4—C5—N1	0.37 (12)
C2—N3—C4—N4	179.40 (9)	N4—C4—C5—N1	−179.69 (9)
N3—C4—N4—O41	6.85 (14)	N3—C4—C5—Cl5	−179.11 (8)
C5—C4—N4—O41	−173.08 (9)	N4—C4—C5—Cl5	0.83 (17)

(II) 2-chloro-1-methyl-4-nitro-1H-imidazole

Crystal data

C4H4ClN3O2	F(000) = 328
Mr = 161.55	Dx = 1.724 Mg m^−3
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 2802 reflections
a = 11.6550 (9) Å	θ = 4–23°
b = 6.1372 (5) Å	µ = 0.55 mm^−1
c = 8.6994 (6) Å	T = 100 K
V = 622.26 (8) Å^3	Block, colourless
Z = 4	0.2 × 0.15 × 0.1 mm

Data collection

Kuma KM-4 CCD four-circle diffractometer	922 independent reflections
Radiation source: fine-focus sealed tube	696 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
ω scan	θmax = 29.9°, θmin = 2.9°
Absorption correction: multi-scan (SORTAV; Blessing, 1989)	h = −13→15
Tmin = 0.940, Tmax = 0.944	k = −8→7
6383 measured reflections	l = −9→12

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)] = 0.030	Hydrogen site location: difference Fourier map
wR(F^2) = 0.065	All H-atom parameters refined
S = 1.01	w = 1/[σ^2(Fo^2) + (0.032P)^2] where P = (Fo^2 + 2Fc^2)/3
922 reflections	(Δ/σ)max < 0.001
71 parameters	Δρmax = 0.26 e Å^−3
0 restraints	Δρmin = −0.31 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. 1.005 (18)

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O41	−0.12219 (12)	0.2500	0.36854 (17)	0.0202 (3)
O42	0.01571 (13)	0.2500	0.19939 (16)	0.0229 (4)
N1	0.22456 (14)	0.2500	0.57663 (18)	0.0149 (4)
N3	0.03393 (14)	0.2500	0.60412 (18)	0.0153 (4)
N4	−0.01970 (15)	0.2500	0.3332 (2)	0.0168 (4)
C2	0.13308 (16)	0.2500	0.6741 (2)	0.0150 (4)
C4	0.06448 (17)	0.2500	0.4523 (2)	0.0140 (4)
C5	0.18052 (18)	0.2500	0.4310 (2)	0.0153 (4)
C11	0.34642 (19)	0.2500	0.6196 (3)	0.0205 (4)
Cl2	0.15103 (4)	0.2500	0.86809 (6)	0.02129 (15)
H5	0.2272 (18)	0.2500	0.336 (2)	0.017 (5)*
H11A	0.392 (3)	0.2500	0.521 (4)	0.070 (10)*
H11B	0.3659 (14)	0.132 (3)	0.676 (2)	0.055 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0131 (9)	0.0162 (9)	0.0156 (8)	0.000	−0.0006 (7)	0.000
C11	0.0138 (10)	0.0258 (11)	0.0220 (11)	0.000	−0.0043 (9)	0.000
C2	0.0161 (12)	0.0134 (9)	0.0155 (9)	0.000	−0.0006 (8)	0.000
Cl2	0.0250 (3)	0.0254 (3)	0.0135 (2)	0.000	−0.0015 (2)	0.000
N3	0.0160 (10)	0.0128 (8)	0.0171 (8)	0.000	0.0001 (7)	0.000
C4	0.0135 (11)	0.0130 (9)	0.0156 (10)	0.000	−0.0001 (8)	0.000
N4	0.0184 (10)	0.0134 (8)	0.0187 (8)	0.000	−0.0019 (7)	0.000
O41	0.0125 (9)	0.0217 (7)	0.0262 (8)	0.000	−0.0035 (7)	0.000
O42	0.0257 (9)	0.0277 (8)	0.0152 (8)	0.000	−0.0034 (7)	0.000
C5	0.0190 (12)	0.0129 (10)	0.0141 (10)	0.000	0.0018 (8)	0.000

Geometric parameters (Å, º)

N1—C2	1.362 (2)	N3—C4	1.368 (2)
N1—C5	1.367 (2)	C4—C5	1.365 (3)
N1—C11	1.469 (3)	C4—N4	1.427 (3)
C11—H11A	1.01 (3)	N4—O41	1.234 (2)
C11—H11B	0.90 (2)	N4—O42	1.235 (2)
C2—N3	1.306 (2)	C5—H5	0.99 (2)
C2—Cl2	1.701 (2)
C2—N1—C5	106.43 (16)	C5—C4—N3	112.90 (18)
C2—N1—C11	126.77 (18)	C5—C4—N4	125.62 (18)
C5—N1—C11	126.80 (17)	N3—C4—N4	121.48 (17)
N1—C11—H11A	106.9 (18)	O41—N4—O42	123.97 (17)
N1—C11—H11B	112.3 (11)	O41—N4—C4	118.99 (17)
H11A—C11—H11B	109.2 (14)	O42—N4—C4	117.04 (17)
N3—C2—N1	113.75 (18)	C4—C5—N1	104.24 (17)
N3—C2—Cl2	124.83 (15)	C4—C5—H5	131.2 (12)
N1—C2—Cl2	121.42 (14)	N1—C5—H5	124.6 (12)
C2—N3—C4	102.68 (16)