Hydro­gen bonding in nitro­aniline analogues: 4-nitro­benz­aldehyde hydrazone forms hydrogen-bonded sheets of R(26) rings

Molecules of the title compound, C₇H₇N₃O₂, are linked by two N—H...O hydrogen bonds [H...O = 2.42 and 2.47 Å, N...O = 3.191 (4) and 3.245 (4) Å, and N—H...O = 150 and 151°] into sheets built from a single type of (26) ring.

S1. Comment

The title compound, (I) (Fig. 1), may be regarded as a chain-extended analogue of 4-nitroaniline, (II), just as 4-amino-4'-nitrobiphenyl, (III), can be regarded as a phenyl-extended analogue of (II).

In the molecules of (I), the only significant deviation form overall planarity is the 7.9 (2)° twist of the nitro group out of the plane of the phenyl ring. The C—NO₂ distance (Table 1) is less than the lower-quartile value (1.460 Å; Allen et al., 1987) for bonds of this type, while both of the N—O bonds in the nitro group are much longer than the upper-quartile value for such bonds. In addition, the C1—C11 bond is at the lower-quartile value for conjugated C(aryl)—C=N– bonds, while there are indications of quinonoid bond fixation in the aryl ring. These observations taken together point to a modest contribution of the polarized form (Ia) to the overall molecular-electronic structure, just as the dimensions of (II) (Tonogaki et al., 1993) and (III) (Graham et al., 1989) point to the participation of forms (IIa) and (IIIa), respectively.

The molecules of (I) are linked by two N—H···O hydrogen bonds (Table 2) into form sheets. Amino atom N12 in the molecule at (x, y, z) acts as a hydrogen-bond donor, via atoms H12A and H12B, respectively, to nitro atoms O1 and O2 in the molecules at (1 + x, 1 − y, −0.5 + z) and (1 + x, −y, −0.5 + z), respectively. These two hydrogen bonds produce two independent C(10) (Bernstein et al., 1995) chains, both running parallel to the [20–1] direction and generated by the c-glide planes at y = 0.5 and y = 0, respectively (Fig. 2). The combination of these two motifs generates a (102) sheet in the form of a (4,4)-net (Batten & Robson, 1998) built from a single type of R⁴₄(16) ring (Fig. 2). We may compare this sheet with that formed in (II), where the rings are of the R⁴₄(22) type (Tonogaki et al., 1993); however, whereas the sheets in (II) are weakly linked by aromatic π···π stacking interactions, there are no direction-specific interactions between adjacent sheets in the structure of (I).

S2. Experimental

Compound (I) was prepared by heating under reflux for 1 h a solution of 4-nitrobenzaldehyde (5 g) and hydrazine hydrate (10 g) in ethanol (50 ml). After cooling to ambient temperature, the mixture was diluted with water (50 ml) and then extracted with CHCl₃; this extract was dried and and evaporated, and the resulting solid was recrystallized from ethanol, yielding (I) (m.p. 407–408 K). Crystals suitable for single-crystal X-ray diffraction were selected directly from the prepared sample.

S3. Refinement

Crystals of (I) are monoclinic, and the systematic absences permitted Pc and P2/c as possible space groups; Pc was selected and confirmed by the subsequent structure analysis. All H atoms were located from difference maps and treated as riding atoms, with C—H distances of 0.93 Å and N—H distances of 0.86 Å. In the absence of significant anomalous scattering it was not possible to establish the correct orientation of the structure with respect to the polar-axis directions; accordingly, the Friedel equivalents were merged prior to the final refinements. Although the data are essentially 100% complete, the ratio of data to parameters is rather low.

Computing details

Data collection: KappaCCD Server Software (Nonius, 1997); cell refinement: DENZO–SMN (Otwinowski & Minor, 1997); data reduction: DENZO–SMN; program(s) used to solve structure: OSCAIL (McArdle, 2003) and SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: OSCAIL andSHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).

Figures

	Fig. 1. The molecule of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. Stereoview of part of the crystal structure of (I), showing the formation of a (102) sheet of R^44(26) rings. For the sake of clarity, H atoms bonded to C atoms have been omitted.

4-Nitrobenzaldehyde hydrazone

Crystal data

C7H7N3O2	F(000) = 172
Mr = 165.16	Dx = 1.508 Mg m^−3
Monoclinic, Pc	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P -2yc	Cell parameters from 829 reflections
a = 3.7070 (2) Å	θ = 3.2–27.4°
b = 6.3963 (3) Å	µ = 0.12 mm^−1
c = 15.4047 (10) Å	T = 120 K
β = 95.064 (2)°	Plate, colourless
V = 363.84 (4) Å^3	0.20 × 0.10 × 0.05 mm
Z = 2

Data collection

Nonius KappaCCD diffractometer	829 independent reflections
Radiation source: fine-focus sealed X-ray tube	765 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.071
ϕ scans, and ω scans with κ offsets	θmax = 27.4°, θmin = 3.2°
Absorption correction: multi-scan (SORTAV; Blessing, 1995, 1997)	h = −4→4
Tmin = 0.967, Tmax = 0.994	k = −8→8
4784 measured reflections	l = −19→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)] = 0.040	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.102	H-atom parameters constrained
S = 1.17	w = 1/[σ^2(Fo^2) + (0.0357P)^2 + 0.1524P] where P = (Fo^2 + 2Fc^2)/3
829 reflections	(Δ/σ)max < 0.001
109 parameters	Δρmax = 0.25 e Å^−3
2 restraints	Δρmin = −0.24 e Å^−3

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

	x	y	z	Uiso*/Ueq
C1	0.4362 (7)	0.2888 (5)	0.32040 (19)	0.0193 (6)
C2	0.4310 (7)	0.1965 (5)	0.40249 (19)	0.0220 (6)
C3	0.3088 (8)	0.3066 (5)	0.4712 (2)	0.0216 (6)
C4	0.1947 (7)	0.5132 (5)	0.4569 (2)	0.0195 (6)
C5	0.2066 (7)	0.6112 (5)	0.37713 (19)	0.0221 (6)
C6	0.3267 (8)	0.4974 (5)	0.30925 (19)	0.0230 (7)
C11	0.5515 (7)	0.1757 (5)	0.24483 (19)	0.0220 (6)
N4	0.0612 (7)	0.6280 (4)	0.52911 (17)	0.0235 (6)
N11	0.6376 (7)	−0.0166 (4)	0.24894 (16)	0.0245 (6)
N12	0.7161 (8)	−0.1091 (4)	0.17187 (19)	0.0293 (6)
O1	−0.0046 (8)	0.8169 (3)	0.51917 (18)	0.0382 (6)
O2	0.0131 (6)	0.5344 (4)	0.59654 (15)	0.0310 (6)
H2	0.5106	0.0595	0.4109	0.026*
H3	0.3024	0.2449	0.5257	0.026*
H5	0.1357	0.7499	0.3695	0.027*
H6	0.3351	0.5604	0.2551	0.028*
H11	0.5620	0.2466	0.1924	0.026*
H12A	0.7053	−0.0369	0.1246	0.035*
H12B	0.7759	−0.2390	0.1711	0.035*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0157 (14)	0.0191 (15)	0.0229 (14)	−0.0021 (11)	−0.0005 (11)	−0.0015 (12)
C2	0.0211 (16)	0.0191 (14)	0.0256 (15)	−0.0005 (12)	0.0010 (13)	0.0015 (12)
C3	0.0237 (15)	0.0209 (15)	0.0198 (13)	−0.0030 (12)	0.0003 (11)	0.0019 (12)
C4	0.0178 (14)	0.0190 (13)	0.0216 (13)	−0.0019 (11)	0.0011 (11)	−0.0034 (12)
C5	0.0236 (16)	0.0190 (13)	0.0234 (16)	−0.0009 (13)	−0.0003 (12)	−0.0008 (12)
C6	0.0276 (16)	0.0206 (14)	0.0203 (14)	−0.0017 (12)	−0.0007 (12)	0.0023 (12)
C11	0.0232 (16)	0.0234 (14)	0.0194 (14)	−0.0030 (13)	0.0016 (12)	0.0016 (12)
N4	0.0233 (14)	0.0237 (13)	0.0234 (13)	−0.0014 (10)	0.0012 (11)	−0.0021 (12)
N11	0.0262 (13)	0.0226 (13)	0.0250 (14)	0.0009 (11)	0.0043 (11)	−0.0025 (11)
N12	0.0377 (16)	0.0235 (14)	0.0270 (13)	0.0025 (11)	0.0049 (11)	−0.0036 (11)
O1	0.0588 (17)	0.0232 (11)	0.0337 (12)	0.0065 (12)	0.0109 (12)	−0.0036 (10)
O2	0.0422 (14)	0.0289 (11)	0.0228 (11)	0.0001 (10)	0.0076 (10)	−0.0001 (10)

Geometric parameters (Å, º)

C1—C2	1.397 (4)	N4—O1	1.239 (3)
C2—C3	1.381 (4)	N4—O2	1.226 (3)
C3—C4	1.399 (4)	C2—H2	0.93
C4—C5	1.383 (4)	C3—H3	0.93
C5—C6	1.380 (4)	C5—H5	0.93
C6—C1	1.401 (4)	C6—H6	0.93
C1—C11	1.466 (4)	C11—H11	0.93
C11—N11	1.271 (4)	N12—H12A	0.86
N11—N12	1.380 (4)	N12—H12B	0.86
C4—N4	1.456 (4)
C2—C1—C6	119.1 (3)	C4—C5—H5	120.9
C2—C1—C11	122.6 (3)	C5—C6—C1	121.3 (3)
C6—C1—C11	118.3 (3)	C5—C6—H6	119.4
C3—C2—C1	120.7 (3)	C1—C6—H6	119.4
C3—C2—H2	119.7	N11—C11—C1	121.8 (3)
C1—C2—H2	119.7	N11—C11—H11	119.1
C2—C3—C4	118.4 (3)	C1—C11—H11	119.1
C2—C3—H3	120.8	C11—N11—N12	116.3 (3)
C4—C3—H3	120.8	N11—N12—H12A	120.0
C5—C4—C3	122.4 (3)	N11—N12—H12B	120.0
C5—C4—N4	119.3 (3)	H12A—N12—H12B	120.0
C3—C4—N4	118.3 (3)	O2—N4—O1	122.6 (3)
C6—C5—C4	118.2 (3)	O2—N4—C4	119.1 (3)
C6—C5—H5	120.9	O1—N4—C4	118.3 (3)
C6—C1—C2—C3	2.1 (4)	C11—C1—C6—C5	178.4 (3)
C11—C1—C2—C3	−177.8 (3)	C2—C1—C11—N11	3.3 (4)
C1—C2—C3—C4	−0.8 (4)	C6—C1—C11—N11	−176.5 (3)
C2—C3—C4—C5	−1.2 (4)	C1—C11—N11—N12	175.5 (3)
C2—C3—C4—N4	179.2 (3)	C5—C4—N4—O2	172.0 (3)
C3—C4—C5—C6	1.8 (4)	C3—C4—N4—O2	−8.4 (4)
N4—C4—C5—C6	−178.6 (3)	C5—C4—N4—O1	−6.9 (4)
C4—C5—C6—C1	−0.4 (4)	C3—C4—N4—O1	172.7 (3)
C2—C1—C6—C5	−1.5 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N12—H12A···O1^i	0.86	2.47	3.245 (4)	151
N12—H12B···O2^ii	0.86	2.42	3.191 (4)	150

Symmetry codes: (i) x+1, −y+1, z−1/2; (ii) x+1, −y, z−1/2.