(n-Nitrophenyl)acetonitrile, with n = 2, 3 and 4

The molecular structures of the three title nitro-substituted phenyl­aceto­nitriles, C₈H₆N₂O₂, at 123 K show that the mol­ecules are linked together very differently. In the 2- and 4-nitro compounds, there are both O...H and N_cyano...H interactions, whereas the crystal lattice of the 3-nitro compound is essentially built up by O...H interactions. The O atoms seem to prefer the aromatic H atoms, while the cyano N atoms prefer the methyl­ene H atoms. The phenyl–nitro torsion angles are −19.83 (13), −5.69 (12) and −2.88 (12)°, while the phenyl–cyano­methyl torsion angles are −62.27 (12), −147.99 (9) and −16.75 (14)° in the 2-, 3- and 4-NO₂-substituted compounds, respectively.

S1. Comment

In recent years, the concept of weak and even very weak hydrogen bonds has been used extensively to rationalize crystal growth, molecular recognition and solvation phenomena (Desiraju & Steiner, 1999). According to this extended definition, hydrogen-bond distances between donor (D) and acceptor (A) atoms comparable to the sum of the van der Waals radii, and even slightly larger distances, have to be taken into account. The strength of an X—H···Y interaction undoubtedly increases the closer the bond angle at the H atom is to 180°, but it is now also suggested that significantly smaller angles may not exclude H···Y interactions (Thalladi et al., 1998). Additionally, one has to consider other types of D—A interactions between functional groups, interactions which, in organic chemistry, are often termed through-space interactions or nucleophilic-electrophilic interactions (Schweizer et al., 1978). These may have a dominating effect on crystal growth in addition to their stereochemical control of many reactions (Nishide et al., 2001). Since a crystal can, in principle, be considered as a supermolecule (Dunitz, 1991; Lehn, 1995), a more detailed analysis of all potential forces between molecules in crystals may lead to improved knowledge of supermolecules and their formation.

Fundamentally, one may assume that a crystallization process will be initiated by a close approach of the atoms forming the stronger contacts, in such a way that repulsive interactions and steric demands of adjacent atoms are minimized, particularly when crystals are formed from very weakly solvating solvents (Shimon et al., 1990). The order of the subsequent weaker interactions forming the crystal lattice may then be a consequence of the configurational and conformational demands set by the first interaction (Seiler & Dunitz, 1989). Thus, even for crystal lattices constructed through only weak interactions, one has to look for the strongest of the weak, i.e. whether certain combinations of D and A atoms are favoured over others. Here, we report on the crystal structures of 2-, 3- and (4-nitrophenyl)acetonitrile, (I), (II) and (III), respectively, which are well suited to this kind of study, since several types of interactions are possible in principle, allowing for a comparison to be made. \sch

The structure of (III) has been reported earlier (Cambridge Structural Database refcode WIQDIJ) as part of a larger methodological study of structure solution and Rietveld refinement of powder diffraction data on organic substances that are difficult to crystallize (Goubitz et al., 1999). The rather high melting points of the three compounds, characteristic for most nitro-substituted aromatic compounds, do indicate some strong intermolecular interactions or numerous weak ones. For these compounds, the following interactions should be considered, all of which have been repeatedly documented [the sums of the relevant van der Waals radii (Bondi, 1964) are given in parentheses]: N(CN)···H(CH₂) and N(CN)···H(Ar) (2.75 Å), O(NO₂)···H(CH₂) and O(NO₂)···H(Ar) (2.72 Å), O(NO₂)···C(CN) and N(CN)···C(CN) (3.22 and 3.25 Å), N(NO₂)···O(NO₂), including four-membered cyclic systems (3.07 Å), and π···π stacking, H(CH₂)···π and H(Ar)···π interactions. Furthermore, different cyclic systems based upon the various interactions mentioned above should also be considered, e.g. cyclic dimers made by O(NO₂)···ortho-H(Ar) interactions (Jaiboon et al., 2001).

For (2-nitrophenyl)acetonitrile, (I), all the intramolecular bond lengths and angles are as expected for this class of compounds (Higashi & Osaki, 1977; Di Rienzo et al., 1980); only the bond between the C atoms bearing the substituents, C1 and C2, is significantly elongated. The aromatic ring is clearly distorted with regard to the bond angles, the ipso bond angle at C1 being some 6° smaller than that at C2. The ring also deviates slightly from planarity towards a boat conformation, with a maximum deviation of 0.040 (6) Å for atoms C3 and C6, and, in the opposite direction, of -0.047 (6) Å for atoms C2 and C5. The methylene atom C7 lies almost in the phenyl ring plane, deviating by only 0.0061 (14) Å, whereas the N atom of the nitro group, N2, lies -0.0346 (13) Å below this plane. The N atom of the cyano group, N1, lies 2.1375 (17) Å from the phenyl plane. Although the NO₂/Ar (C1—C2—N2—O2) and CH₂CN/Ar (C2—C1—C7—C8) torsion angles assume their largest values in (I), compared with (II) and (III), atom O2 still lies only a mere 2.38 Å from H7A, with an O2···H7A—C7 angle of 100.4°.

The question then arises as to whether there is an interaction between nitro atom O2 and methylene atom H7A, cf. the classical work on 2-nitrobenzaldehyde (Coppens, 1964). The nitro group in (I) is tilted away from the CH₂CN group, as the C1—C2—N2 bond angle is distinctly larger than that of C3—C2—N2, while in (II) and (III), the corresponding angles to the nitro group are similar within experimental error. Likewise, the C2—C1—C7 angle is some 8.6° larger than the C6—C1—C7 angle. This suggests that there is no true intramolecular contact between O2 and the methylene group, even though the O2—C7 distance is also quite short [2.7351 (14) Å]. In the 2-nitrophenyl hydrazone of benzaldehyde, the corresponding C1—C2—N2 bond angle is, on the contrary, diminished to 117°, suggesting that an intramolecular H(N)···O(NO₂) interaction is present (Drew et al., 1984; Drew & Willey, 1986). Nonetheless, it is notable that (I) does not fully exploit all its degrees of freedom in reducing these interactions, as the nitro group is still only moderately tilted out of the plane of the phenyl ring.

The crystal lattice of (I) is built up by a number of weak intermolecular contacts (Fig. 4), the strongest being N1(CN)···H7B and O1···H3, together with the weaker interactions N1···H7A and O2···H5, forming several multi-membered ring systems. One may also mention the presence of a symmetrical four-membered ring system due to weak N2···O1(-x, -y, 1 - z) contacts of 3.0473 (12) Å, only slightly less than the sum of the van der Waals radii (3.07 Å). There is no evidence for N(CN)···H(Ar) contacts, π···π stacking or H···π interactions.

For (3-nitrophenyl)acetonitrile, (II), the bond lengths and angles are again as expected, the angle at C3 being significantly larger than that at C1. This is in agreement with the general rule that the C atom bearing the most electronegative substituent has the larger ipso bond angle, cf. the Hammet σ values for NO₂ (σ_m = 0.71 and σ_p = 0.81) and CH₂CN (σ_m = 0.16 and σ_p = 0.18) (Isaacs, 1987). The phenyl ring is essentially planar, with maximum and minimum deviations of 0.0082 (6) and -0.0070 (6) Å for atoms C4 and C3, respectively. Atoms C7 [-0.0261 (15) Å] and N2 [-0.0422 (13) Å] are both below this plane and located opposite to the cyano group, with a deviation of 1.246 (2) Å for atom N1. The strongest intermolecular contacts (Fig. 5) are between the H2 atom ortho to the nitro group and atom O1, forming a ten-membered cyclic arrangement, and between atoms O2 and H5. All other interactions, including N(CN)···H(CH₂) and N(CN)···H(Ar), are very weak, but some cyclic arrangements seem to be recurrent, e.g. N1···H6. Again, there is no evidence for H···π or π···π interactions.

For (4-nitrophenyl)acetonitrile, (III), as in (II), nitro atom N2 and methylene atom C7 are located opposite to the cyano group, deviating from the phenyl plane by -0.0547 (13) and -0.0727 (15) Å, respectively, compared with 0.5325 (19) Å for N1. Both atoms C1 and C4 lie below the plane of the ring, by -0.0082 (6) and -0.0079 (6) Å,respectively, whereas atoms C2 and C5 lie above, by 0.0079 (6) and 0.0074 (6) Å, respectively. Otherwise, all bond lengths and angles in the phenyl group are as expected for a compound with two para-substituted groups, both being electron withdrawing (Di Rienzo et al., 1980). The strongest intermolecular contacts, between atom O2 and the aromatic H5 atom ortho to the most electronegative substituent, form a cyclic system (Fig. 6). A slightly weaker contact is present between atoms O1 and H6, ortho to the least electronegative substituent. As in (I), the cyano N atom in (III) is bifurcated, making contacts with both the methylene atom H7B and atom H3. A fairly short O1···H7A distance suggests that atom O1 may also be bifurcated. As found for (I) and (II), no H···π or π···π interactions can be detected in (III).

A common characteristic for all three compounds is that the O atoms seem to prefer intermolecular interactions with the aromatic H atoms, the strongest being with the H atom located ortho to the nitro group. Notably, none of the O···H(CH₂) distances in the three compounds are less than the sum of the van der Waals radii (2.72 Å), despite the known acidity of this class of compounds (Bordwell, 1988). The cyano N atoms, however, show the opposite behaviour, with the N···H(CH₂) distances in (I) and (III) being slightly but significantly less than the sum of the van der Waals radii (2.75 Å). Only in (III) is there an N(CN)···H contact with an aromatic H atom (H3), but this contact is distinctly weaker than the O···H(Ar) contacts. These apparent preferences of the O atoms for the aromatic H atoms, and of the cyano N atom for the acidic methylene H atoms, are, in principle, as observed for the F···H(Ar) and N···H(CH₂) interactions in [4-(trifluoromethyl)phenyl]acetonitrile (Boitsov et al., 2001), the O···H(Ar) interactions, however, being slightly stronger than the F···H(Ar) interactions, as judged from the O···H and F···H distances.

One may further note that the O1···C8(x, -1/2 - y, 1/2 + z) distance in (III) is fairly short [3.058 (12) Å] compared with the sum of the van der Waals radii (3.22 Å), suggesting some residual positive charge on the cyano C atom, making it a better acceptor when the nitro group is located in the 4-position. The crystal lattice in (II) is essentially built up by two fairly strong O···H(Ar) interactions only, compared with one strong interaction assisted by weaker N···H(CH₂) interactions in (I) and (III). Consequently, the calculated density of the crystals of (II) (1.453 Mg m^-3) is higher than those of (I) and (III) (1.442 and 1.427 Mg m^-3, respectively). It should be emphasized that only a few of the bond angles at the H atoms in the intermolecular contacts considered here are close to 180° (Tables 2, 4 and 6). Presumably, the presence of two electronegative substituents will efficiently reduce the ability of the aromatic ring to act as a donor. One may therefore conclude that only in the case of (I) will the cyano-N atom be able to compete with the O atoms in initiating the crystallization process.

S2. Experimental

(2-Nitrophenyl)acetonitrile (ex Aldrich, 98%) was dissolved in a minimum volume of diethyl ether at room temperature; cyclohexane was added to the point of turbidity. After filtration, the solution was left at room temperature overnight. The pale-yellow crystals of (I) were washed with cold cyclohexane and dried in vacuo (m.p. 354–355 K). Spectroscopic analysis: IR (Nujol, cm^-1): 2149 (C≡N); ¹³C NMR (600 MHz, CDCl₃, δ, p.p.m.): 125.87 (C1), 147.58 (C2), 125.87 (C3), 129.67 (C4), 134.46 (C5), 131.11 (C6), 22.77 (C7), 116.32 (C8); ¹H NMR (600 MHz, CDCl₃, δ, p.p.m.): 8.19 (H3), 7.58 (H4), 7.73 (unresolved, H5), 7.74 (unresolved, H6), 4.22 (H7).

(3-Nitrophenyl)acetonitrile (ex Aldrich, 99%) was treated similarly to (I), but hexane had to be added to obtain colourless crystals of (II) at 275 K after ~2 h (m.p. 335–336 K). Spectroscopic analysis: IR (Nujol, cm^-1): 2149 (C≡N); ¹³C NMR (600 MHz, CDCl₃, δ, p.p.m.): 133.95 (C1), 123.33 (C2), 148.63 (C3), 123.11 (C4), 130.35 (C5), 131.99 (C6), 23.46 (C7), 116.57 (C8); ¹H NMR (600 MHz, CDCl₃, δ, p.p.m.): 8.23 (H2), 8.23 (H4), 7.62 (H5), 7.73 (H6), 3.90 (H7).

(4-Nitrophenyl)acetonitrile (ex Aldrich, 98%) was dissolved in a minimum amount of acetone and the solution was filtered after cooling. An equal volume of diethyl ether was then added and suitable pale-yellow crystals of (III) were obtained after ~2 h at 253 K (m.p. 387–388 K). Spectroscopic analysis: IR (Nujol, cm^-1): 2149 (C≡N); ¹³C NMR (600 MHz, CDCl₃, δ, p.p.m.): 137.00 (C1), 128.97 (C2), 124.38 (C3), 147.85 (C4), 124.38 (C5), 128.97 (C6), 23.61 (C7), 116.42 (C8); ¹H NMR (600 MHz, CDCl₃, δ, p.p.m.): 7.55 (H2), 8.27 (H3), 8.27 (H5), 7.55 (H6), 3.89 (H7).

S3. Refinement

H atoms were treated as riding atoms, with C—H(CH) and C—H(CH₂) distances of 0.95 and 0.99 Å, respectively, with U_iso(H) = 1.2U_eq of their parent atoms. The maximum residual peak is located 0.82 Å from O2 in (I), 0.69 Å from C2 in (II) and 0.69 Å from C4 in (III).

Computing details

For all compounds, data collection: SMART (Bruker, 1999); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 2001b); molecular graphics: SHELXTL/PC (Sheldrick, 2001a); software used to prepare material for publication: SHELXTL/PC and PLATON (Spek, 2001).

Figures

	Fig. 1. The molecular structure of (I). Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. The molecular structure of (II). Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 3. The molecular structure of (III). Displacement ellipsoids are drawn at the 50% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 4. An illustration down [010] (with [001] upwards) of short contacts for (I). Atoms labelled with an asterisk (*) lie at positions (-1/2 - x, 1/2 + y, z), a plus sign (+) at (-x, 1/2 + y, 3/2 - z), a dollar sign (add) at (x - 1/2, 1/2 - y, 1 - z), a hash (#) at (1/2 + x, 1/2 - y, 1 - z) and an ampersand (add) at (1 + x, y, z). The unit-cell outline has been omitted for clarity.
	Fig. 5. An illustration down [100] (with [010] upwards) of short contacts for (II). Atoms labelled with an ampersand (add) lie at positions (-x, -y, 1 - z), a dollar sign (add) at (1 - x, -y, -z) and a hash (#) at (x - 1/2, 1/2 - y, 1/2 + z). The unit-cell outline has been omitted for clarity.
	Fig. 6. An illustration down [100] (with [001] upwards) of short contacts for (III). Atoms labelled with an asterisk (*) lie at positions (2 - x, y - 1/2, -1/2 - z), a plus sign (+) at (2 - x, -1 - y, -z), a dollar sign (add) at (1 - x, 1 - y, -z), a hash (#) at (x, 1/2 - y, 1/2 + z) and an ampersand (add) at (x, -1/2 - y, 1/2 + z). The unit-cell outline has been omitted for clarity.

(I) (2-nitrophenyl)acetonitrile

Crystal data

C8H6N2O2	Dx = 1.442 Mg m^−3
Mr = 162.15	Melting point = 354–355 K
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 8192 reflections
a = 7.9689 (11) Å	θ = 3.0–31.5°
b = 7.6030 (8) Å	µ = 0.11 mm^−1
c = 24.654 (3) Å	T = 123 K
V = 1493.7 (3) Å^3	Flat prism, pale yellow
Z = 8	0.48 × 0.43 × 0.06 mm
F(000) = 672

Data collection

Bruker SMART 2K CCD area-detector diffractometer	2494 independent reflections
Radiation source: normal-focus sealed tube	2083 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
ω scans	θmax = 31.5°, θmin = 3.0°
Absorption correction: numerical (SHELXTL/PC; Sheldrick, 2001a)	h = −11→11
Tmin = 0.943, Tmax = 0.994	k = −11→11
25225 measured reflections	l = −36→36

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)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.123	H-atom parameters constrained
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0791P)^2 + 0.1627P] where P = (Fo^2 + 2Fc^2)/3
2494 reflections	(Δ/σ)max = 0.001
109 parameters	Δρmax = 0.41 e Å^−3
0 restraints	Δρmin = −0.36 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.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

* 0.0007 (0.0006) C1 * -0.0047 (0.0006) C2 * 0.0040 (0.0006) C3 * 0.0007 (0.0006) C4 * -0.0047 (0.0006) C5 * 0.0040 (0.0006) C6 0.0061 (0.0014) C7 1.1997 (0.0016) C8 2.1375 (0.0017) N1 - 0.0346 (0.0013) N2

Rms deviation of fitted atoms = 0.0036

- 1.3989 (0.0128) x + 5.6966 (0.0033) y + 15.7438 (0.0182) z = 9.3619 (0.0093)

Angle to previous plane (with approximate e.s.d.) = 19.58 (0.06)

* 0.0000 (0.0000) N2 * 0.0000 (0.0000) O1 * 0.0000 (0.0000) O2

Rms deviation of fitted atoms = 0.0000

0.0782 (0.0028) x + 6.9483 (0.0014) y + 10.0058 (0.0080) z = 6.1748 (0.0049)

Angle to previous plane (with approximate e.s.d.) = 19.58 (0.06)

* 0.0007 (0.0006) C1 * -0.0047 (0.0006) C2 * 0.0040 (0.0006) C3 * 0.0007 (0.0006) C4 * -0.0047 (0.0006) C5 * 0.0040 (0.0006) C6

Rms deviation of fitted atoms = 0.0036

4.7901 (0.0036) x + 1.1927 (0.0107) y + 19.3196 (0.0128) z = 13.0754 (0.0087)

Angle to previous plane (with approximate e.s.d.) = 62.14 (0.09)

* 0.0000 (0.0000) C1 * 0.0000 (0.0000) C7 * 0.0000 (0.0000) C8

Rms deviation of fitted atoms = 0.0000

Refinement. Refinement of F² against ALL reflections, except for 0 0 2, which was systematically in error. 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.

Max. Delta(rho) (0.41) 0.82 Å from O2.

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

	x	y	z	Uiso*/Ueq
C1	0.14973 (10)	−0.03738 (11)	0.64198 (3)	0.01852 (17)
N1	−0.17723 (11)	0.17364 (12)	0.71155 (4)	0.0297 (2)
O1	−0.04864 (10)	0.17042 (10)	0.52866 (3)	0.0339 (2)
O2	−0.15648 (10)	−0.01393 (15)	0.58578 (3)	0.0453 (3)
C2	0.13061 (10)	0.03658 (11)	0.59023 (3)	0.01810 (17)
N2	−0.03670 (10)	0.06786 (11)	0.56683 (3)	0.02394 (18)
C3	0.26637 (11)	0.08303 (11)	0.55779 (3)	0.02081 (18)
H3	0.2486	0.1343	0.5231	0.025*
C4	0.42832 (11)	0.05354 (12)	0.57667 (4)	0.02339 (19)
H4	0.5223	0.0840	0.5549	0.028*
C5	0.45176 (11)	−0.02075 (12)	0.62753 (4)	0.02378 (19)
H5	0.5622	−0.0420	0.6405	0.029*
C6	0.31413 (11)	−0.06426 (11)	0.65970 (4)	0.02159 (19)
H6	0.3327	−0.1135	0.6946	0.026*
C7	0.00907 (12)	−0.08991 (12)	0.68009 (4)	0.0249 (2)
H7A	−0.0623	−0.1786	0.6619	0.030*
H7B	0.0583	−0.1456	0.7127	0.030*
C8	−0.09655 (11)	0.05855 (12)	0.69712 (4)	0.02208 (19)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0195 (4)	0.0169 (3)	0.0192 (4)	0.0010 (3)	0.0022 (3)	−0.0005 (3)
N1	0.0272 (4)	0.0328 (4)	0.0292 (4)	0.0053 (3)	0.0009 (3)	−0.0028 (3)
O1	0.0368 (4)	0.0300 (4)	0.0349 (4)	0.0065 (3)	−0.0145 (3)	0.0026 (3)
O2	0.0183 (4)	0.0843 (7)	0.0333 (4)	−0.0091 (4)	−0.0007 (3)	0.0048 (4)
C2	0.0159 (3)	0.0191 (4)	0.0193 (4)	0.0007 (3)	−0.0016 (3)	−0.0016 (3)
N2	0.0187 (3)	0.0309 (4)	0.0222 (4)	0.0034 (3)	−0.0032 (3)	−0.0055 (3)
C3	0.0219 (4)	0.0206 (4)	0.0199 (4)	−0.0011 (3)	0.0017 (3)	0.0000 (3)
C4	0.0189 (4)	0.0237 (4)	0.0276 (4)	−0.0022 (3)	0.0038 (3)	−0.0023 (3)
C5	0.0184 (4)	0.0236 (4)	0.0293 (4)	0.0018 (3)	−0.0036 (3)	−0.0041 (3)
C6	0.0232 (4)	0.0216 (4)	0.0201 (4)	0.0034 (3)	−0.0025 (3)	−0.0010 (3)
C7	0.0261 (4)	0.0216 (4)	0.0269 (4)	0.0034 (3)	0.0089 (3)	0.0048 (3)
C8	0.0211 (4)	0.0267 (4)	0.0185 (4)	0.0000 (3)	0.0016 (3)	0.0023 (3)

Geometric parameters (Å, º)

C1—C2	1.4026 (12)	C3—H3	0.9500
C1—C6	1.3961 (12)	C4—C5	1.3879 (13)
C1—C7	1.5162 (12)	C4—H4	0.9500
N1—C8	1.1426 (12)	C5—C6	1.3933 (13)
O1—N2	1.2258 (11)	C5—H5	0.9500
O2—N2	1.2314 (12)	C6—H6	0.9500
C2—C3	1.3910 (12)	C7—C8	1.4693 (13)
C2—N2	1.4720 (11)	C7—H7A	0.9900
C3—C4	1.3902 (13)	C7—H7B	0.9900
C2—C1—C6	116.44 (8)	C3—C4—H4	120.2
C2—C1—C7	126.09 (8)	C4—C5—C6	120.33 (8)
C6—C1—C7	117.47 (8)	C4—C5—H5	119.8
C1—C2—C3	122.71 (8)	C6—C5—H5	119.8
C1—C2—N2	121.31 (7)	C1—C6—C5	121.72 (8)
C3—C2—N2	115.98 (8)	C5—C6—H6	119.1
O1—N2—C2	118.29 (8)	C1—C6—H6	119.1
O1—N2—O2	123.53 (8)	C1—C7—C8	113.47 (7)
O2—N2—C2	118.15 (8)	C8—C7—H7A	108.9
C2—C3—C4	119.25 (8)	C1—C7—H7A	108.9
C4—C3—H3	120.4	C8—C7—H7B	108.9
C2—C3—H3	120.4	C1—C7—H7B	108.9
C3—C4—C5	119.55 (8)	H7A—C7—H7B	107.7
C5—C4—H4	120.2	N1—C8—C7	178.40 (10)
C6—C1—C2—C3	−0.53 (12)	N2—C2—C3—C4	−178.52 (7)
C7—C1—C2—C3	179.34 (8)	C2—C3—C4—C5	−0.31 (13)
C6—C1—C2—N2	178.82 (7)	C3—C4—C5—C6	−0.52 (13)
C7—C1—C2—N2	−1.32 (13)	C4—C5—C6—C1	0.85 (13)
C3—C2—N2—O1	−18.62 (11)	C2—C1—C6—C5	−0.33 (13)
C1—C2—N2—O1	162.00 (8)	C7—C1—C6—C5	179.79 (8)
C3—C2—N2—O2	159.55 (9)	C6—C1—C7—C8	117.60 (9)
C1—C2—N2—O2	−19.83 (13)	C2—C1—C7—C8	−62.27 (12)
C1—C2—C3—C4	0.85 (13)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···O1^i	0.95	2.54	3.1982 (11)	127
C5—H5···O2^ii	0.95	2.62	3.2876 (13)	127
C7—H7A···O2	0.99	2.38	2.7351 (14)	100
C7—H7A···N1^iii	0.99	2.66	3.2904 (13)	122
C7—H7B···N1^iv	0.99	2.50	3.4877 (13)	172

Symmetry codes: (i) x+1/2, −y+1/2, −z+1; (ii) x+1, y, z; (iii) −x−1/2, y−1/2, z; (iv) −x, y−1/2, −z+3/2.

(II) (3-nitrophenyl)acetonitrile

Crystal data

C8H6N2O2	F(000) = 336
Mr = 162.15	Dx = 1.453 Mg m^−3
Monoclinic, P21/n	Melting point = 335–336 K
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71073 Å
a = 5.3641 (4) Å	Cell parameters from 6347 reflections
b = 11.5157 (9) Å	θ = 2.5–31.6°
c = 12.1981 (10) Å	µ = 0.11 mm^−1
β = 100.369 (2)°	T = 123 K
V = 741.19 (10) Å^3	Irregular prism, colourless
Z = 4	0.50 × 0.30 × 0.08 mm

Data collection

Bruker SMART 2K CCD area-detector diffractometer	2463 independent reflections
Radiation source: normal-focus sealed tube	2005 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
ω scans	θmax = 31.6°, θmin = 2.5°
Absorption correction: numerical (SHELXTL/PC; Sheldrick, 2001a)	h = −7→7
Tmin = 0.958, Tmax = 0.992	k = −16→16
12917 measured reflections	l = −17→17

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)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.118	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0699P)^2 + 0.0827P] where P = (Fo^2 + 2Fc^2)/3
2463 reflections	(Δ/σ)max < 0.001
109 parameters	Δρmax = 0.41 e Å^−3
0 restraints	Δρmin = −0.21 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.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

* 0.0074 (0.0006) C1 * -0.0009 (0.0006) C2 * -0.0070 (0.0006) C3 * 0.0082 (0.0006) C4 * -0.0017 (0.0006) C5 * -0.0060 (0.0006) C6 - 0.0261 (0.0015) C7 0.6966 (0.0017) C8 1.2463 (0.0020) N1 - 0.0422 (0.0013) N2

Rms deviation of fitted atoms = 0.0059

2.4256 (0.0037) x - 9.8834 (0.0036) y + 1.9200 (0.0197) z = 0.5019 (0.0112)

Angle to previous plane (with approximate e.s.d.) = 6.40 (0.09)

* 0.0000 (0.0000) N2 * 0.0000 (0.0000) O1 * 0.0000 (0.0000) O2

Rms deviation of fitted atoms = 0.0000

2.9310 (0.0017) x - 9.1998 (0.0026) y + 1.8173 (0.0044) z = 0.7915 (0.0017)

Angle to previous plane (with approximate e.s.d.) = 6.40 (0.09)

* 0.0074 (0.0006) C1 * -0.0009 (0.0006) C2 * -0.0070 (0.0006) C3 * 0.0082 (0.0006) C4 * -0.0017 (0.0006) C5 * -0.0060 (0.0006) C6

Rms deviation of fitted atoms = 0.0059

0.5214 (0.0062) x - 9.2018 (0.0036) y + 6.9060 (0.0038) z = 1.4410 (0.0015)

Angle to previous plane (with approximate e.s.d.) = 32.79 (0.07)

* 0.0000 (0.0000) C1 * -0.0020 (0.0004) C7 * 0.0046 (0.0008) C8 * -0.0026 (0.0005) N1

Rms deviation of fitted atoms = 0.0028

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.

Max. Delta(rho) (0.41) 0.69 Å from C2.

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

	x	y	z	Uiso*/Ueq
C1	0.31273 (16)	0.06697 (8)	0.27428 (7)	0.01862 (18)
N1	0.33325 (19)	−0.10745 (8)	0.03996 (8)	0.0323 (2)
O1	0.20019 (14)	0.11412 (7)	0.59595 (6)	0.02684 (18)
O2	0.55242 (14)	0.20912 (7)	0.63996 (6)	0.02891 (19)
C2	0.27305 (16)	0.07688 (7)	0.38389 (7)	0.01771 (18)
H2	0.1358	0.0380	0.4075	0.021*
N2	0.39360 (15)	0.15698 (7)	0.57222 (6)	0.01958 (17)
C3	0.43914 (16)	0.14500 (7)	0.45747 (7)	0.01726 (18)
C4	0.64376 (17)	0.20269 (8)	0.42789 (8)	0.02000 (19)
H4	0.7562	0.2472	0.4808	0.024*
C5	0.67872 (18)	0.19320 (8)	0.31799 (8)	0.02201 (19)
H5	0.8157	0.2327	0.2947	0.026*
C6	0.51416 (17)	0.12620 (8)	0.24186 (7)	0.02123 (19)
H6	0.5396	0.1208	0.1669	0.025*
C7	0.12750 (18)	−0.00451 (9)	0.19274 (8)	0.0248 (2)
H7A	0.0500	−0.0640	0.2346	0.030*
H7B	−0.0099	0.0468	0.1553	0.030*
C8	0.24486 (19)	−0.06250 (9)	0.10756 (8)	0.0235 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0186 (4)	0.0212 (4)	0.0160 (4)	0.0033 (3)	0.0028 (3)	0.0003 (3)
N1	0.0403 (5)	0.0296 (5)	0.0296 (5)	−0.0068 (4)	0.0137 (4)	−0.0077 (4)
O1	0.0266 (3)	0.0344 (4)	0.0222 (3)	−0.0071 (3)	0.0115 (3)	−0.0027 (3)
O2	0.0291 (4)	0.0366 (4)	0.0211 (3)	−0.0077 (3)	0.0048 (3)	−0.0095 (3)
C2	0.0171 (4)	0.0190 (4)	0.0178 (4)	0.0006 (3)	0.0050 (3)	0.0008 (3)
N2	0.0215 (4)	0.0206 (3)	0.0174 (3)	0.0002 (3)	0.0058 (3)	−0.0014 (3)
C3	0.0190 (4)	0.0187 (4)	0.0149 (4)	0.0021 (3)	0.0053 (3)	0.0008 (3)
C4	0.0192 (4)	0.0205 (4)	0.0208 (4)	−0.0002 (3)	0.0047 (3)	0.0002 (3)
C5	0.0206 (4)	0.0244 (4)	0.0227 (4)	0.0008 (3)	0.0085 (3)	0.0033 (3)
C6	0.0216 (4)	0.0260 (4)	0.0173 (4)	0.0045 (3)	0.0069 (3)	0.0034 (3)
C7	0.0217 (4)	0.0343 (5)	0.0182 (4)	0.0000 (4)	0.0033 (3)	−0.0049 (4)
C8	0.0275 (5)	0.0238 (4)	0.0193 (4)	−0.0030 (3)	0.0042 (3)	−0.0007 (3)

Geometric parameters (Å, º)

C1—C2	1.3959 (12)	C3—C4	1.3852 (12)
C1—C6	1.3939 (12)	C4—C5	1.3910 (13)
C1—C7	1.5161 (13)	C4—H4	0.9500
N1—C8	1.1460 (13)	C5—C6	1.3935 (13)
O1—N2	1.2296 (10)	C5—H5	0.9500
O2—N2	1.2311 (10)	C6—H6	0.9500
C2—C3	1.3881 (12)	C7—C8	1.4687 (13)
C2—H2	0.9500	C7—H7A	0.9900
N2—C3	1.4701 (11)	C7—H7B	0.9900
C2—C1—C6	119.44 (8)	C5—C4—H4	121.2
C2—C1—C7	118.55 (8)	C4—C5—C6	120.44 (8)
C6—C1—C7	121.97 (8)	C4—C5—H5	119.8
C1—C2—C3	118.34 (8)	C6—C5—H5	119.8
C3—C2—H2	120.8	C1—C6—C5	120.81 (8)
C1—C2—H2	120.8	C5—C6—H6	119.6
O1—N2—O2	123.30 (8)	C1—C6—H6	119.6
O1—N2—C3	118.58 (7)	C1—C7—C8	113.41 (8)
O2—N2—C3	118.12 (7)	C8—C7—H7A	108.9
C2—C3—C4	123.31 (8)	C1—C7—H7A	108.9
C2—C3—N2	118.12 (8)	C8—C7—H7B	108.9
C4—C3—N2	118.57 (8)	C1—C7—H7B	108.9
C3—C4—C5	117.64 (8)	H7A—C7—H7B	107.7
C3—C4—H4	121.2	N1—C8—C7	178.98 (11)
C6—C1—C2—C3	−0.72 (13)	N2—C3—C4—C5	−177.99 (8)
C7—C1—C2—C3	−178.27 (8)	C3—C4—C5—C6	−0.96 (13)
C1—C2—C3—C4	−0.67 (13)	C4—C5—C6—C1	−0.38 (14)
C1—C2—C3—N2	178.83 (7)	C2—C1—C6—C5	1.24 (13)
O1—N2—C3—C4	173.83 (8)	C7—C1—C6—C5	178.70 (8)
O2—N2—C3—C4	−6.53 (12)	C6—C1—C7—C8	34.53 (13)
O1—N2—C3—C2	−5.69 (12)	C2—C3—N2—O1	−5.69 (12)
O2—N2—C3—C2	173.95 (8)	C2—C1—C7—C8	−147.99 (9)
C2—C3—C4—C5	1.51 (13)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2···O1^i	0.95	2.51	3.4010 (11)	157
C5—H5···O2^ii	0.95	2.55	3.4009 (11)	150
C6—H6···N1^iii	0.95	2.73	3.6806 (13)	174

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

(III) (4-nitrophenyl)acetonitrile

Crystal data

C8H6N2O2	F(000) = 336
Mr = 162.15	Dx = 1.427 Mg m^−3
Monoclinic, P21/c	Melting point = 387–388 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 8.1695 (7) Å	Cell parameters from 7016 reflections
b = 5.9775 (5) Å	θ = 2.5–31.5°
c = 15.7260 (13) Å	µ = 0.11 mm^−1
β = 100.695 (2)°	T = 123 K
V = 754.61 (11) Å^3	Flat prism, pale yellow
Z = 4	0.40 × 0.30 × 0.11 mm

Data collection

Bruker SMART 2K CCD area-detector diffractometer	2489 independent reflections
Radiation source: normal-focus sealed tube	2097 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
ω scans	θmax = 31.5°, θmin = 2.5°
Absorption correction: numerical (SHELXTL/PC; Sheldrick, 2001a)	h = −11→11
Tmin = 0.965, Tmax = 0.989	k = −8→8
13089 measured reflections	l = −23→23

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)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.120	H-atom parameters constrained
S = 1.08	w = 1/[σ^2(Fo^2) + (0.0734P)^2 + 0.0923P] where P = (Fo^2 + 2Fc^2)/3
2489 reflections	(Δ/σ)max = 0.001
109 parameters	Δρmax = 0.37 e Å^−3
0 restraints	Δρmin = −0.29 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.

Least-squares planes (x,y,z in crystal coordinates) and deviations from them (* indicates atom used to define plane)

7.1091 (0.0015) x + 2.6412 (0.0019) y + 0.8292 (0.0055) z = 5.2723 (0.0011)

* -0.0082 (0.0006) C1 * 0.0079 (0.0006) C2 * 0.0001 (0.0006) C3 * -0.0079 (0.0006) C4 * 0.0074 (0.0006) C5 * 0.0006 (0.0006) C6 - 0.0727 (0.0015) C7 0.2699 (0.0016) C8 0.5325 (0.0019) N1 - 0.0547 (0.0013) N2

Rms deviation of fitted atoms = 0.0064

7.0480 (0.0059) x + 2.4962 (0.0041) y + 1.8890 (0.0235) z = 5.2968 (0.0012)

Angle to previous plane (with approximate e.s.d.) = 4.11 (0.11)

* 0.0000 (0.0000) N2 * 0.0000 (0.0000) O1 * 0.0000 (0.0000) O2

Rms deviation of fitted atoms = 0.0000

7.1091 (0.0015) x + 2.6412 (0.0019) y + 0.8292 (0.0055) z = 5.2723 (0.0011)

Angle to previous plane (with approximate e.s.d.) = 4.11 (0.11)

* -0.0082 (0.0006) C1 * 0.0079 (0.0006) C2 * 0.0001 (0.0006) C3 * -0.0079 (0.0006) C4 * 0.0074 (0.0006) C5 * 0.0006 (0.0006) C6

Rms deviation of fitted atoms = 0.0064

6.2653 (0.0044) x + 3.8255 (0.0043) y - 1.5024 (0.0207) z = 4.7605 (0.0031)

Angle to previous plane (with approximate e.s.d.) = 16.15 (0.08)

* 0.0000 (0.0000) C1 * 0.0000 (0.0000) C7 * 0.0000 (0.0000) C8 - 0.0059 (0.0021) N1

Rms deviation of fitted atoms = 0.0000

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.

Max. Delta(rho) (0.37) 0.69 Å from C4.

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

	x	y	z	Uiso*/Ueq
C1	0.77027 (10)	−0.05217 (14)	−0.08930 (5)	0.02110 (17)
N1	1.01216 (11)	−0.47692 (16)	−0.15817 (6)	0.0343 (2)
O1	0.66473 (11)	0.08971 (13)	0.20532 (4)	0.0380 (2)
O2	0.57552 (9)	0.39312 (12)	0.13721 (5)	0.03289 (19)
C2	0.80832 (11)	−0.17273 (14)	−0.01202 (5)	0.02254 (18)
H2	0.8628	−0.3133	−0.0113	0.027*
N2	0.64076 (9)	0.20685 (13)	0.13998 (5)	0.02431 (17)
C3	0.76712 (11)	−0.08866 (14)	0.06404 (5)	0.02252 (17)
H3	0.7916	−0.1710	0.1165	0.027*
C4	0.68949 (10)	0.11821 (13)	0.06097 (5)	0.01999 (17)
C5	0.65350 (11)	0.24453 (14)	−0.01450 (5)	0.02310 (18)
H5	0.6025	0.3874	−0.0145	0.028*
C6	0.69374 (11)	0.15734 (15)	−0.08986 (5)	0.02362 (18)
H6	0.6691	0.2405	−0.1421	0.028*
C7	0.80434 (13)	−0.14149 (18)	−0.17468 (6)	0.0308 (2)
H7A	0.6976	−0.1897	−0.2106	0.037*
H7B	0.8494	−0.0186	−0.2057	0.037*
C8	0.92138 (11)	−0.32963 (16)	−0.16565 (5)	0.02575 (19)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0210 (3)	0.0249 (4)	0.0180 (3)	0.0009 (3)	0.0051 (3)	0.0010 (3)
N1	0.0353 (4)	0.0389 (5)	0.0298 (4)	0.0075 (3)	0.0090 (3)	−0.0020 (3)
O1	0.0571 (5)	0.0404 (4)	0.0170 (3)	0.0133 (4)	0.0082 (3)	0.0029 (3)
O2	0.0392 (4)	0.0312 (4)	0.0281 (4)	0.0114 (3)	0.0058 (3)	−0.0049 (3)
C2	0.0270 (4)	0.0214 (4)	0.0194 (4)	0.0040 (3)	0.0050 (3)	0.0016 (3)
N2	0.0255 (3)	0.0284 (4)	0.0184 (3)	0.0027 (3)	0.0022 (3)	−0.0029 (3)
C3	0.0266 (4)	0.0228 (4)	0.0180 (3)	0.0028 (3)	0.0037 (3)	0.0024 (3)
C4	0.0211 (4)	0.0223 (4)	0.0163 (3)	0.0004 (3)	0.0028 (3)	−0.0013 (3)
C5	0.0262 (4)	0.0210 (4)	0.0222 (4)	0.0035 (3)	0.0050 (3)	0.0025 (3)
C6	0.0269 (4)	0.0253 (4)	0.0191 (4)	0.0034 (3)	0.0054 (3)	0.0050 (3)
C7	0.0365 (5)	0.0386 (5)	0.0185 (4)	0.0126 (4)	0.0081 (3)	0.0021 (3)
C8	0.0259 (4)	0.0326 (4)	0.0197 (4)	−0.0003 (3)	0.0069 (3)	−0.0026 (3)

Geometric parameters (Å, º)

C1—C2	1.3973 (11)	C3—C4	1.3865 (11)
C1—C6	1.3991 (12)	C3—H3	0.9500
C1—C7	1.5179 (12)	C4—C5	1.3913 (11)
N1—C8	1.1431 (13)	C5—C6	1.3887 (12)
O1—N2	1.2288 (10)	C5—H5	0.9500
O2—N2	1.2317 (10)	C6—H6	0.9500
C2—C3	1.3950 (11)	C7—C8	1.4659 (13)
C2—H2	0.9500	C7—H7A	0.9900
N2—C4	1.4720 (11)	C7—H7B	0.9900
C2—C1—C6	119.61 (7)	C5—C4—N2	118.51 (7)
C2—C1—C7	122.70 (8)	C4—C5—C6	118.57 (8)
C6—C1—C7	117.67 (7)	C6—C5—H5	120.7
C1—C2—C3	120.65 (8)	C4—C5—H5	120.7
C3—C2—H2	119.7	C1—C6—C5	120.46 (7)
C1—C2—H2	119.7	C5—C6—H6	119.8
O1—N2—O2	123.05 (8)	C1—C6—H6	119.8
O1—N2—C4	118.34 (7)	C1—C7—C8	114.05 (7)
O2—N2—C4	118.60 (7)	C8—C7—H7A	108.7
C2—C3—C4	118.23 (7)	C1—C7—H7A	108.7
C4—C3—H3	120.9	C8—C7—H7B	108.7
C2—C3—H3	120.9	C1—C7—H7B	108.7
C3—C4—C5	122.45 (7)	H7A—C7—H7B	107.6
C3—C4—N2	119.03 (7)	N1—C8—C7	179.54 (10)
C6—C1—C2—C3	1.56 (13)	C3—C4—C5—C6	1.45 (13)
C7—C1—C2—C3	−176.76 (8)	N2—C4—C5—C6	−177.61 (7)
C1—C2—C3—C4	−0.76 (13)	C4—C5—C6—C1	−0.61 (13)
C2—C3—C4—C5	−0.77 (13)	C2—C1—C6—C5	−0.86 (13)
C2—C3—C4—N2	178.28 (7)	C7—C1—C6—C5	177.55 (8)
O1—N2—C4—C3	−2.88 (12)	C2—C1—C7—C8	−16.75 (14)
O2—N2—C4—C3	178.26 (8)	C3—C4—N2—O1	−2.88 (12)
O1—N2—C4—C5	176.21 (8)	C6—C1—C7—C8	164.90 (8)
O2—N2—C4—C5	−2.65 (12)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3···N1^i	0.95	2.65	3.3459 (12)	130
C5—H5···O2^ii	0.95	2.55	3.2520 (11)	131
C6—H6···O1^iii	0.95	2.60	3.5262 (11)	165
C7—H7A···O1^iv	0.99	2.72	3.3528 (13)	122
C7—H7B···N1^v	0.99	2.61	3.4040 (13)	137

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