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The crystal structures of the brown–yellow and orange polymorphs of the title compound, 4-[(2-nitro­phenyl)­diazenyl]­phenol, C12H9N3O3, have been determined and their visible reflection spectra recorded. Both structures adopt a stacking arrangement with interstack hydrogen bonds. Ab initio and semi-empirical (AM1 and INDO-CISD) calculations were performed in order to rationalize the difference in colour. It can be attributed neither to the subtle distinctions in molecular geometry nor to the effect of intermolecular electrostatic interactions. The most probable origin of this difference is the mixing of intramolecular n\rightarrow π* and intermolecular charge-transfer excitations.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270101007594/na1519sup1.cif
Contains datablocks Ia, Ib, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270101007594/na1519Iasup2.hkl
Contains datablock Ia

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270101007594/na1519Ibsup3.hkl
Contains datablock Ib

CCDC references: 170196; 170197

Comment top

The first examples of differently coloured crystalline forms of organic compounds were reported 94 years ago (Hantzsch, 1907). This phenomenon was originally called chromoisomerism, but recently the more appropriate term crystallochromy has been introduced (Klebe et al., 1989). The current version of the Cambridge Structural Database (CSD; Allen & Kennard, 1993) contains more than 50 families of differently coloured polymorphs and pseudopolymorphs, but for only a few of them have the solid-state spectra been reported and the distinctions in colour rationalized.

These distinctions may be of various natures. Firstly, the molecules in the crystals may exist as different tautomeric forms or may adopt different conformations. In this case, the difference in colour can be interpreted at the level of the calculated electronic spectra of these tautomers or conformers. Secondly, the shifts of the absorption bands may arise from the perturbation of molecular orbitals (MOs) under the effect of the crystal environment. This effect is closely related in its nature to solvatochromism and can be modelled via incorporation of the external electrostatic potential into the Hamiltonian of a molecule (Csikós et al., 1999; Yatsenko & Paseshnichenko, 2000). Thirdly, the absorption bands may be shifted and split, due to the collective interactions within the crystals upon excitation. These effects can be considered at the level of the exciton-polariton approach (Philpott, 1971) and they are very large for strongly allowed transitions in some organic dyes, but are shadowed by other effects for moderately absorbing crystals. Fourthly, the bands corresponding to the intermolecular charge-transfer (CT) interaction can appear not only in the crystals with interlaced donor and acceptor molecules, but also in homomolecular crystals too (Sebastian et al., 1981). If the intermolecular π interactions are strong, the excitonic and CT states mix and should be considered together within the general theory (Hoffmann et al., 2000). In order to extend the understanding of these various factors, we have studied 4-[(2-nitrophenyl)azo]phenol, (I), and present its crystal structure here. \sch

As shown in Fig. 1, the electronic spectrum of (I) in CCl4 solution is typical of azophenols (Okawara et al., 1988). It contains a medium-strong absorption band in the near UV and a weak maximum in the visible region, attributed to the π π* and the n π* excitations, respectively. Fig. 1 indicates that the polymorphs (Ia) and (Ib) differ in colour due to the different intensity of the nπ* band in their solid-state reflection spectra, because the red and yellow hues of coloured materials arise from the absorbance at 20000 and above 23000 cm-1, respectively (Griffiths, 1976). The yellow and orange forms of 1,1'-dinitro-3,3'-azo-1,2,4-triazole (Cromer et al., 1988) provide another example of polymorphs whose colour arises from the n π* excitation.

The bond lengths and angles in both structures are within the normally expected ranges. The molecular conformations in (Ia) and (Ib) differ: in (Ia), the two rings attached to the azo linkage are twisted to the same side and are thus essentially coplanar, whereas in (Ib), the rings are rotated opposite to each other (Table 1). The two independent molecules in (Ib) form pseudo-centrosymmetric pairs and adopt essentially the same conformation. The twist of the nitro group out of the plane of the phenyl ring results from the compromise between the N···O repulsion and the π delocalization. Overall, the molecule of (Ia) is slightly flattened with respect to (Ib).

The molecules in (Ia) form stacks along [010]. The shortest intermolecular C···C distances are 3.536 (3) Å and neighbouring molecules within the stack are related by inversion centres. In (Ib), neighbouring molecules are related by the [100] translation, and the shortest C···C distances within the stack are 3.478 (6) Å. The molecules are linked via hydrogen bonds, to form dimers in (Ia) and tetramers in (Ib) (Fig. 4 and Table 2), and the two independent molecules in (Ib) are non-equivalent in the hydrogen-bonding pattern.

In order to compare the molecular electronic structures in (Ia) and (Ib), and to determine the effect of crystal packing, we have carried out semi-empirical calculations at the AM1 level (Dewar et al., 1985), with the experimental molecular geometries used as input for the calculations. The molecular dipole moment in (I) is determined by the contributions of the nitro group and the hydroxy oxygen lone pair, and it is nearly perpendicular to the long axis of the molecule. Intermolecular interactions therefore cause only a subtle increase (0.03–0.05 e) in the intramolecular CT from the phenolic moiety to the nitro-substituted ring.

Under the effect of the crystal electrostatic potential, the gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) decreases from 7.79 to 7.61 eV in (Ia) and from 7.91 to 7.58 eV in (Ib), but in (Ib) LUMO and HOMO are localized on molecules 1 and 2, respectively. Such non-equivalence is caused by the hydrogen bonding: since the orbitals of the hydroxy O atom make a significant contribution to HOMO, this MO can be stabilized or destabilized by hydrogen bonds formed via the H or O atom of this group, respectively. Had the hydrogen bonds been formed via the azo N atoms, as in the structure of 4-(phenyldiazenyl)naphthalen-1-amine (Yatsenko et al., 2001), their impact on the molecular electronic structure would have been much more pronounced, because the azo linkage makes a much larger contribution to LUMO than the nitro group.

The intensity of the n π* transition increases (as what is varied?) in the spectra of aromatic azo compounds, due to the interaction between the azo nitrogen lone pairs and the aromatic π systems, which is assisted by the deviation of a molecule from planarity (Griffiths, 1976). We have studied the effect of the conformation? of (I) on the electronic spectra at the INDO-CISD level. In its original parameterization (Dick & Nickel, 1983), this method strongly underestimates the energy and intensity of the n π* transition. For (I), the calculations predict a gap of 14000 cm-1 between the nπ* and ππ* excited states, whereas the experimentally determined value is about 6000 cm-1. Similarly, the observed oscillator strength estimated according to Guillaumont & Nakamura (2000) is 0.018, versus 0.0009 obtained from the calculations (units?). The structures of the molecular orbitals calculated using INDO-CISD differ from those obtained in the ab initio calculations. Since INDO overestimates the energy of the MO, which is mainly composed of the nitrogen `lone-pair' atomic orbitals, by ca 1.4 eV, this orbital is HOMO-1 in the INDO calculations, but only HOMO-4 according to the ab initio results. Following Ridley & Zerner (1973), we have introduced into the INDO-CISD scheme an additional empirical parameter fσ (equal to 1.2) for scaling up the σ-σ overlap integrals. Besides this, we have increased both core integrals for the N atom by 9%. With these modifications, the INDO-calculated MOs match quite well with those obtained in the ab initio calculations, and the calculated nπ*-ππ* gap and the oscillator strength for the n π* transition are in much better agreement with the experimental data.

Calculations on isolated molecules showed that the difference in molecular geometry between (Ia) and (Ib) is not enough to explain the observed spectral distinctions of these polymorphs. The n π* oscillator strength in (Ia) was even calculated to be slightly larger than in (Ib) [0.007 in (Ia) versus 0.004 and 0.006 in the two molecules of (Ib)]. With the crystal electrostatic potential applied, INDO-CISD predicts a bathochromic shift of 700–800 cm-1 on the π π* transition and a hypsochromic shift of 200–300 cm-1 on the n π* transition, accompanied by a 30% increase in the oscillator strength for both (Ia) and (Ib). As with the π π* transition, these results are in line with the observed effects: the positions of the corresponding absorption maxima in (Ia) and (Ib) are red-shifted by 900–1000 cm-1 with respect to the spectrum of a CCl4 solution of (I). However, neither the difference in molecular geometry nor the intermolecular electrostatic interactions allow explanation of the 1500 cm-1 red shift of the nπ* band on transfer from solution to solid (Ia) and (Ib), or of the increase in intensity of this band in (Ib) with respect to (Ia). Qualitatively, these effects can be explained by the mixing of the nπ* excited state with intermolecular CT excitations. The INDO-CISD calculations on the inversion- and translation-related molecular dimers modelling the stacking in (Ia) and (Ib) partially confirm this supposition: in translation-related dimers, the n π* excitation is accompanied by some intermolecular CT (0.0003–0.0006 e) and the oscillator strength for this transition increases by 50% with respect to the isolated molecule, whereas for inversion-related dimers, the oscillator strength for this excitation decreases twice (? to half?). However, these calculations do not explain the observed red shift of the nπ* absorption band, probably due to the fact that ZDO-based methods (define ZDO) are not very well suited for reproducing intermolecular interactions.

Related literature top

For related literature, see: Allen & Kennard (1993); Cromer et al. (1988); Csikós et al. (1999); Dewar et al. (1985); Dick & Nickel (1983); Elbs et al. (1924); Griffiths (1976); Guillaumont & Nakamura (2000); Hantzsch (1907); Hoffmann et al. (2000); Klebe et al. (1989); Okawara et al. (1988); Philpott (1971); Ridley & Zerner (1973); Schmidt et al. (1993); Sebastian et al. (1981); Yatsenko & Paseshnichenko (2000); Yatsenko et al. (2001).

Experimental top

Compound (I) was prepared according to the established procedure of Elbs et al. (1924). Single crystals of (Ia) and (Ib) were grown by slow evaporation of chloroform and acetone solutions of (I), respectively. The powders prepared from the crystals of (Ia) and (Ib) were brownish-yellow and orange, respectively. The UV-visible spectra were recorded on a Specord M-40 spectrophotometer (Carl Zeiss, Jena). Spectroscopic data: UV-visible [CCl4, λmax, nm (lg ε)]: 350 (4.26), 443 (3.02). The ab initio calculations were performed with GAMESS (Schmidt et al., 1993) using the 6–31G** basis set. Details of the calculations employing crystal electrostatic potential at the AM1 and INDO levels were reported elsewhere (Yatsenko & Paseshnichenko, 2000).

Computing details top

For both compounds, data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: PROFIT (Streltsov & Zavodnik, 1989); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997). Molecular graphics: ORTEP-3 (Farrugia, 1997) for (Ia); ORTEP-3 (Farrugia, 1997) and PLUTON92 (Spek, 1992) for (Ib). For both compounds, software used to prepare material for publication: PARST (Nardelli, 1983).

Figures top
[Figure 1] Fig. 1. The absorption spectra of (I). Dashed lines: solution in CCl4 at two different concentrations; solid line: reflection spectrum of (Ia); dotted line: reflection spectrum of (Ib). Auth to check concs are on right lines.
[Figure 2] Fig. 2. The asymmetric unit of (Ia) with 50% probability displacement ellipsoids and the atom-numbering scheme. H atoms are drawn as small spheres of arbitrary radii.
[Figure 3] Fig. 3. The asymmetric unit of (Ib) with 50% probability displacement ellipsoids and the atom-numbering scheme. H atoms are drawn as small spheres of arbitrary radii. Atoms O1—C16 belong to molecule 1, and atoms O21—C36 belong to molecule 2.
[Figure 4] Fig. 4. The hydrogen-bonded tetramer in (Ib).
(Ia) 4-[(2-nitrophenyl)azo]phenol top
Crystal data top
C12H9N3O3Z = 2
Mr = 243.22F(000) = 252
Triclinic, P1Dx = 1.470 Mg m3
a = 7.114 (2) ÅMo Kα radiation, λ = 0.71073 Å
b = 7.380 (2) ÅCell parameters from 23 reflections
c = 10.849 (4) Åθ = 14.0–15.8°
α = 96.68 (2)°µ = 0.11 mm1
β = 97.49 (2)°T = 293 K
γ = 100.54 (2)°Prism, yellow-brown
V = 549.4 (3) Å30.44 × 0.25 × 0.18 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
Rint = 0.000
Radiation source: fine-focus sealed tubeθmax = 27.0°, θmin = 1.9°
Graphite monochromatorh = 98
non–profiled ω scansk = 99
2395 measured reflectionsl = 013
2395 independent reflections3 standard reflections every 80 min
1599 reflections with I > 2σ(I) intensity decay: none
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.038Hydrogen site location: difference Fourier map
wR(F2) = 0.101All H-atom parameters refined
S = 1.12 w = 1/[σ2(Fo2) + (0.047P)2]
where P = (Fo2 + 2Fc2)/3
2395 reflections(Δ/σ)max = 0.001
199 parametersΔρmax = 0.13 e Å3
0 restraintsΔρmin = 0.13 e Å3
Crystal data top
C12H9N3O3γ = 100.54 (2)°
Mr = 243.22V = 549.4 (3) Å3
Triclinic, P1Z = 2
a = 7.114 (2) ÅMo Kα radiation
b = 7.380 (2) ŵ = 0.11 mm1
c = 10.849 (4) ÅT = 293 K
α = 96.68 (2)°0.44 × 0.25 × 0.18 mm
β = 97.49 (2)°
Data collection top
Enraf-Nonius CAD-4
diffractometer
Rint = 0.000
2395 measured reflections3 standard reflections every 80 min
2395 independent reflections intensity decay: none
1599 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0380 restraints
wR(F2) = 0.101All H-atom parameters refined
S = 1.12Δρmax = 0.13 e Å3
2395 reflectionsΔρmin = 0.13 e Å3
199 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
O10.11585 (15)0.09869 (18)0.11935 (9)0.0623 (3)
O20.42739 (15)0.09597 (17)0.77164 (10)0.0637 (4)
O30.53975 (17)0.2873 (2)0.93921 (11)0.0986 (6)
N10.55694 (16)0.26659 (17)0.46467 (10)0.0449 (3)
N20.54162 (15)0.26991 (16)0.57761 (10)0.0439 (3)
N30.55263 (17)0.2176 (2)0.83473 (11)0.0502 (3)
C10.04451 (19)0.1421 (2)0.20802 (12)0.0434 (3)
C20.0354 (2)0.1219 (2)0.33272 (13)0.0467 (4)
C30.2008 (2)0.1632 (2)0.41883 (13)0.0442 (3)
C40.37845 (19)0.22757 (18)0.38277 (12)0.0404 (3)
C50.3859 (2)0.2484 (2)0.25806 (13)0.0467 (4)
C60.2206 (2)0.2066 (2)0.17076 (13)0.0482 (4)
C110.72440 (18)0.30347 (18)0.65783 (12)0.0381 (3)
C120.72971 (18)0.28328 (19)0.78406 (12)0.0388 (3)
C130.8999 (2)0.3224 (2)0.86705 (14)0.0468 (4)
C141.0711 (2)0.3820 (2)0.82508 (14)0.0502 (4)
C151.0703 (2)0.4035 (2)0.70105 (14)0.0519 (4)
C160.8998 (2)0.3654 (2)0.61888 (14)0.0479 (4)
H10.219 (3)0.042 (3)0.1592 (19)0.105 (7)*
H50.1982 (18)0.1473 (19)0.5012 (13)0.039 (4)*
H20.093 (2)0.075 (2)0.3550 (13)0.052 (4)*
H30.894 (2)0.377 (2)0.5325 (16)0.066 (5)*
H40.5128 (19)0.2895 (19)0.2342 (12)0.046 (4)*
H61.186 (2)0.448 (2)0.6670 (13)0.052 (4)*
H71.188 (2)0.409 (2)0.8824 (13)0.056 (4)*
H80.229 (2)0.221 (2)0.0833 (14)0.056 (4)*
H90.896 (2)0.307 (2)0.9439 (14)0.048 (4)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0473 (6)0.0882 (9)0.0446 (6)0.0022 (6)0.0057 (5)0.0205 (6)
O20.0448 (6)0.0746 (8)0.0666 (7)0.0050 (6)0.0093 (5)0.0158 (6)
O30.0648 (8)0.1724 (16)0.0506 (7)0.0099 (9)0.0201 (6)0.0077 (8)
N10.0435 (6)0.0514 (8)0.0369 (6)0.0055 (5)0.0008 (5)0.0066 (5)
N20.0421 (6)0.0500 (8)0.0376 (6)0.0067 (6)0.0013 (5)0.0078 (5)
N30.0388 (6)0.0738 (9)0.0412 (6)0.0146 (6)0.0065 (5)0.0148 (6)
C10.0438 (7)0.0441 (8)0.0383 (7)0.0030 (6)0.0022 (6)0.0092 (6)
C20.0425 (8)0.0533 (9)0.0436 (8)0.0017 (7)0.0074 (6)0.0155 (7)
C30.0508 (8)0.0497 (9)0.0318 (7)0.0058 (7)0.0056 (6)0.0120 (6)
C40.0419 (7)0.0401 (8)0.0366 (7)0.0056 (6)0.0016 (6)0.0038 (6)
C50.0429 (8)0.0554 (9)0.0401 (7)0.0017 (7)0.0089 (6)0.0103 (7)
C60.0535 (9)0.0565 (10)0.0329 (7)0.0040 (7)0.0062 (6)0.0112 (7)
C110.0378 (7)0.0356 (7)0.0393 (7)0.0064 (6)0.0023 (5)0.0045 (6)
C120.0366 (7)0.0416 (8)0.0393 (7)0.0096 (6)0.0058 (5)0.0081 (6)
C130.0474 (8)0.0554 (10)0.0383 (8)0.0131 (7)0.0015 (6)0.0107 (7)
C140.0380 (8)0.0560 (10)0.0516 (9)0.0046 (7)0.0037 (6)0.0074 (7)
C150.0406 (8)0.0566 (10)0.0549 (9)0.0020 (7)0.0085 (7)0.0109 (8)
C160.0484 (8)0.0518 (9)0.0407 (8)0.0010 (7)0.0054 (6)0.0113 (7)
Geometric parameters (Å, º) top
O1—C11.3557 (15)C4—C51.3860 (18)
O1—H10.96 (2)C5—C61.3724 (19)
O2—N31.2140 (15)C5—H40.976 (14)
O3—N31.2110 (16)C6—H80.976 (15)
N1—N21.2420 (16)C11—C161.3848 (19)
N1—C41.4132 (16)C11—C121.3911 (18)
N2—C111.4305 (16)C12—C131.3740 (18)
N3—C121.4640 (18)C13—C141.371 (2)
C1—C61.385 (2)C13—H90.858 (15)
C1—C21.3867 (19)C14—C151.372 (2)
C2—C31.3658 (19)C14—H70.947 (14)
C2—H20.988 (15)C15—C161.3716 (19)
C3—C41.3888 (19)C15—H60.966 (15)
C3—H50.917 (13)C16—H30.947 (16)
C1—O1—H1106.6 (12)C5—C6—C1119.41 (13)
N2—N1—C4114.35 (12)C5—C6—H8119.8 (8)
N1—N2—C11113.09 (11)C1—C6—H8120.8 (8)
O3—N3—O2123.18 (13)C16—C11—C12116.83 (12)
O3—N3—C12117.67 (13)C16—C11—N2123.67 (12)
O2—N3—C12119.14 (12)C12—C11—N2119.40 (11)
O1—C1—C6118.12 (13)C13—C12—C11122.11 (12)
O1—C1—C2121.71 (13)C13—C12—N3116.68 (12)
C6—C1—C2120.17 (12)C11—C12—N3121.21 (11)
C3—C2—C1120.00 (13)C14—C13—C12119.52 (14)
C3—C2—H2122.6 (8)C14—C13—H9121.6 (10)
C1—C2—H2117.4 (8)C12—C13—H9118.9 (10)
C2—C3—C4120.46 (13)C13—C14—C15119.68 (14)
C2—C3—H5121.3 (8)C13—C14—H7119.4 (9)
C4—C3—H5118.3 (8)C15—C14—H7120.9 (9)
C5—C4—C3119.11 (12)C16—C15—C14120.50 (14)
C5—C4—N1116.76 (12)C16—C15—H6116.4 (8)
C3—C4—N1124.07 (12)C14—C15—H6123.1 (8)
C6—C5—C4120.85 (13)C15—C16—C11121.35 (14)
C6—C5—H4121.4 (8)C15—C16—H3122.7 (9)
C4—C5—H4117.7 (8)C11—C16—H3115.9 (9)
C4—N1—N2—C11178.01 (11)C16—C11—C12—C130.0 (2)
O1—C1—C2—C3178.54 (14)N2—C11—C12—C13176.73 (13)
C6—C1—C2—C30.9 (2)C16—C11—C12—N3179.63 (13)
C1—C2—C3—C40.7 (2)N2—C11—C12—N33.7 (2)
C2—C3—C4—C50.4 (2)O3—N3—C12—C1338.1 (2)
C2—C3—C4—N1177.46 (14)O2—N3—C12—C13141.16 (14)
N2—N1—C4—C5171.01 (13)O3—N3—C12—C11142.27 (16)
N2—N1—C4—C311.8 (2)O2—N3—C12—C1138.4 (2)
C3—C4—C5—C60.1 (2)C11—C12—C13—C140.5 (2)
N1—C4—C5—C6177.43 (14)N3—C12—C13—C14179.12 (14)
C4—C5—C6—C10.3 (2)C12—C13—C14—C150.6 (2)
O1—C1—C6—C5178.80 (14)C13—C14—C15—C160.1 (3)
C2—C1—C6—C50.7 (2)C14—C15—C16—C110.4 (2)
N1—N2—C11—C1613.2 (2)C12—C11—C16—C150.5 (2)
N1—N2—C11—C12170.40 (13)N2—C11—C16—C15177.03 (14)
(Ib) 4-[(2-nitrophenyl)azo]phenol top
Crystal data top
C12H9N3O3F(000) = 1008
Mr = 243.22Dx = 1.445 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 3.823 (1) ÅCell parameters from 22 reflections
b = 23.014 (8) Åθ = 11.2–12.8°
c = 25.437 (9) ŵ = 0.11 mm1
β = 92.73 (3)°T = 293 K
V = 2235.5 (13) Å3Needle, orange
Z = 80.39 × 0.12 × 0.07 mm
Data collection top
Enraf-Nonius CAD-4
diffractometer
Rint = 0.046
Radiation source: fine-focus sealed tubeθmax = 25.0°, θmin = 1.2°
Graphite monochromatorh = 04
non–profiled ω scansk = 027
4574 measured reflectionsl = 3030
3954 independent reflections3 standard reflections every 80 min
1544 reflections with I > 2σ(I) intensity decay: none
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.066Hydrogen site location: difference Fourier map
wR(F2) = 0.124All H-atom parameters refined
S = 0.98 w = 1/[σ2(Fo2) + (0.032P)2]
where P = (Fo2 + 2Fc2)/3
3954 reflections(Δ/σ)max < 0.001
397 parametersΔρmax = 0.16 e Å3
0 restraintsΔρmin = 0.15 e Å3
Crystal data top
C12H9N3O3V = 2235.5 (13) Å3
Mr = 243.22Z = 8
Monoclinic, P21/nMo Kα radiation
a = 3.823 (1) ŵ = 0.11 mm1
b = 23.014 (8) ÅT = 293 K
c = 25.437 (9) Å0.39 × 0.12 × 0.07 mm
β = 92.73 (3)°
Data collection top
Enraf-Nonius CAD-4
diffractometer
Rint = 0.046
4574 measured reflections3 standard reflections every 80 min
3954 independent reflections intensity decay: none
1544 reflections with I > 2σ(I)
Refinement top
R[F2 > 2σ(F2)] = 0.0660 restraints
wR(F2) = 0.124All H-atom parameters refined
S = 0.98Δρmax = 0.16 e Å3
3954 reflectionsΔρmin = 0.15 e Å3
397 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
O11.1222 (10)0.09985 (15)0.34897 (14)0.0613 (11)
O210.6705 (11)0.34469 (16)0.24393 (15)0.0680 (12)
O20.3855 (12)0.13177 (18)0.53379 (15)0.0966 (14)
O221.4789 (11)0.12091 (17)0.06884 (14)0.1001 (14)
O30.7184 (12)0.19259 (19)0.57452 (14)0.1106 (16)
O231.1828 (12)0.05988 (17)0.02288 (13)0.1121 (16)
N10.6712 (9)0.12359 (14)0.38991 (14)0.0470 (10)
N211.1606 (9)0.12226 (15)0.20954 (13)0.0470 (10)
N20.6877 (9)0.14127 (14)0.43656 (14)0.0463 (10)
N221.1487 (9)0.10482 (14)0.16238 (13)0.0462 (10)
N30.5367 (13)0.1782 (2)0.53684 (18)0.0685 (14)
N231.3434 (13)0.07355 (18)0.06278 (16)0.0666 (13)
C11.0228 (12)0.0444 (2)0.36164 (18)0.0483 (13)
C210.7855 (12)0.28936 (19)0.23324 (19)0.0451 (12)
C21.0744 (13)0.0219 (2)0.41173 (19)0.0496 (13)
C220.7464 (13)0.2652 (2)0.18338 (18)0.0527 (14)
C30.9648 (12)0.0335 (2)0.42221 (17)0.0477 (13)
C230.8646 (13)0.2107 (2)0.17472 (19)0.0512 (13)
C40.8006 (11)0.06676 (19)0.38299 (16)0.0440 (12)
C241.0205 (11)0.17883 (17)0.21531 (16)0.0403 (11)
C50.7531 (13)0.04426 (19)0.33286 (18)0.0471 (12)
C251.0572 (13)0.2024 (2)0.26531 (17)0.0481 (13)
C60.8604 (13)0.01182 (19)0.32249 (18)0.0490 (13)
C260.9412 (14)0.2579 (2)0.27327 (19)0.0526 (14)
C110.5622 (11)0.19913 (18)0.44222 (17)0.0413 (11)
C311.2864 (11)0.04798 (18)0.15629 (16)0.0411 (12)
C120.4996 (13)0.2188 (2)0.49205 (18)0.0488 (12)
C321.3711 (12)0.03183 (19)0.10622 (18)0.0452 (12)
C130.4036 (14)0.2753 (2)0.5024 (2)0.0623 (16)
C331.4829 (14)0.0229 (2)0.0940 (2)0.0601 (15)
C140.3603 (15)0.3129 (2)0.4610 (2)0.0664 (17)
C341.5147 (15)0.0631 (2)0.1336 (2)0.0667 (16)
C150.4207 (13)0.2947 (2)0.4110 (2)0.0574 (15)
C351.4299 (15)0.0495 (2)0.1837 (2)0.0637 (16)
C160.5177 (13)0.2379 (2)0.40111 (19)0.0504 (13)
C361.3137 (13)0.0064 (2)0.1953 (2)0.0523 (14)
H11.225 (14)0.115 (2)0.3728 (18)0.10 (2)*
H21.195 (9)0.0455 (14)0.4385 (12)0.037 (11)*
H30.994 (9)0.0495 (15)0.4582 (13)0.047 (12)*
H50.624 (10)0.0676 (15)0.3052 (13)0.046 (12)*
H60.840 (9)0.0306 (14)0.2876 (12)0.036 (11)*
H130.349 (11)0.2875 (17)0.5386 (15)0.067 (15)*
H140.315 (10)0.3522 (15)0.4696 (13)0.047 (13)*
H150.394 (10)0.3245 (16)0.3820 (14)0.054 (13)*
H160.586 (9)0.2260 (15)0.3670 (13)0.036 (11)*
H210.566 (11)0.3543 (18)0.2179 (14)0.047 (17)*
H220.646 (9)0.2901 (13)0.1545 (11)0.027 (10)*
H230.846 (9)0.1899 (15)0.1415 (13)0.040 (12)*
H251.146 (10)0.1783 (15)0.2939 (13)0.050 (13)*
H260.951 (10)0.2741 (15)0.3076 (14)0.054 (13)*
H331.561 (11)0.0299 (18)0.0593 (15)0.073 (17)*
H341.585 (11)0.1020 (17)0.1262 (15)0.064 (14)*
H351.433 (11)0.0768 (16)0.2123 (14)0.057 (14)*
H361.253 (11)0.0155 (18)0.2285 (15)0.065 (16)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.082 (3)0.039 (2)0.063 (3)0.0090 (19)0.003 (2)0.0044 (18)
O210.090 (3)0.046 (2)0.067 (3)0.001 (2)0.004 (3)0.012 (2)
O20.117 (4)0.087 (3)0.086 (3)0.001 (3)0.001 (3)0.024 (3)
O220.137 (4)0.085 (3)0.078 (3)0.035 (3)0.001 (3)0.024 (2)
O30.134 (4)0.136 (4)0.058 (2)0.027 (3)0.031 (3)0.000 (3)
O230.180 (5)0.104 (3)0.049 (2)0.012 (3)0.027 (3)0.012 (2)
N10.049 (3)0.041 (2)0.051 (2)0.000 (2)0.004 (2)0.0025 (19)
N210.051 (3)0.048 (2)0.042 (2)0.001 (2)0.002 (2)0.0012 (19)
N20.047 (3)0.047 (2)0.045 (2)0.001 (2)0.002 (2)0.0055 (19)
N220.052 (3)0.045 (2)0.041 (2)0.003 (2)0.001 (2)0.0033 (19)
N30.074 (4)0.078 (4)0.054 (3)0.024 (3)0.013 (3)0.000 (3)
N230.097 (4)0.056 (3)0.047 (3)0.003 (3)0.011 (3)0.007 (3)
C10.047 (3)0.044 (3)0.055 (3)0.006 (3)0.014 (3)0.009 (3)
C210.042 (3)0.036 (3)0.058 (3)0.007 (2)0.006 (3)0.003 (2)
C20.048 (3)0.046 (3)0.054 (3)0.009 (3)0.002 (3)0.005 (3)
C220.066 (4)0.045 (3)0.045 (3)0.002 (3)0.009 (3)0.006 (3)
C30.052 (3)0.053 (3)0.039 (3)0.001 (3)0.000 (3)0.008 (3)
C230.063 (4)0.047 (3)0.044 (3)0.005 (3)0.005 (3)0.001 (3)
C40.043 (3)0.042 (3)0.048 (3)0.002 (2)0.012 (3)0.000 (2)
C240.043 (3)0.038 (3)0.040 (3)0.005 (2)0.007 (2)0.002 (2)
C50.052 (3)0.043 (3)0.047 (3)0.001 (3)0.002 (3)0.001 (2)
C250.057 (3)0.047 (3)0.040 (3)0.005 (3)0.000 (3)0.004 (2)
C60.060 (4)0.047 (3)0.040 (3)0.005 (3)0.004 (3)0.009 (2)
C260.066 (4)0.051 (3)0.041 (3)0.003 (3)0.002 (3)0.002 (3)
C110.037 (3)0.040 (3)0.047 (3)0.000 (2)0.001 (2)0.006 (2)
C310.038 (3)0.043 (3)0.043 (3)0.004 (2)0.003 (2)0.005 (2)
C120.047 (3)0.058 (3)0.041 (3)0.008 (3)0.007 (2)0.000 (3)
C320.048 (3)0.039 (3)0.049 (3)0.003 (3)0.003 (2)0.001 (2)
C130.068 (4)0.065 (4)0.054 (4)0.013 (3)0.005 (3)0.019 (3)
C330.052 (4)0.063 (4)0.066 (4)0.004 (3)0.010 (3)0.009 (3)
C140.082 (4)0.044 (3)0.073 (4)0.005 (3)0.003 (4)0.014 (3)
C340.065 (4)0.044 (3)0.091 (5)0.005 (3)0.000 (4)0.018 (3)
C150.064 (4)0.041 (3)0.066 (4)0.000 (3)0.005 (3)0.007 (3)
C350.064 (4)0.044 (3)0.082 (4)0.001 (3)0.005 (4)0.012 (3)
C160.054 (3)0.048 (3)0.049 (3)0.001 (3)0.000 (3)0.002 (3)
C360.052 (4)0.056 (3)0.048 (3)0.004 (3)0.002 (3)0.003 (3)
Geometric parameters (Å, º) top
O1—C11.373 (5)C4—C51.380 (5)
O1—H10.79 (5)C24—C251.383 (5)
O21—C211.378 (5)C5—C61.384 (6)
O21—H210.79 (4)C5—H51.00 (3)
O2—N31.216 (5)C25—C261.372 (6)
O22—N231.213 (5)C25—H250.96 (3)
O3—N31.203 (5)C6—H60.99 (3)
O23—N231.203 (5)C26—H260.95 (3)
N1—N21.253 (4)C11—C121.377 (5)
N1—C41.412 (5)C11—C161.379 (5)
N21—N221.264 (4)C31—C361.379 (5)
N21—C241.418 (5)C31—C321.380 (5)
N2—C111.425 (5)C12—C131.380 (6)
N22—C311.421 (5)C32—C331.370 (6)
N3—C121.474 (6)C13—C141.365 (6)
N23—C321.464 (5)C13—H130.99 (4)
C1—C61.372 (6)C33—C341.367 (7)
C1—C21.381 (6)C33—H330.96 (4)
C21—C261.363 (6)C14—C151.370 (6)
C21—C221.386 (6)C14—H140.95 (3)
C2—C31.373 (6)C34—C351.368 (7)
C2—H20.97 (3)C34—H340.96 (4)
C22—C231.354 (6)C15—C161.384 (6)
C22—H220.99 (3)C15—H151.01 (3)
C3—C41.383 (5)C35—C361.398 (6)
C3—H30.99 (3)C35—H350.96 (4)
C23—C241.379 (5)C16—H160.96 (3)
C23—H230.97 (3)C36—H360.91 (4)
C1—O1—H1112 (4)C1—C6—C5120.0 (4)
C21—O21—H21104 (3)C1—C6—H6115 (2)
N2—N1—C4114.6 (4)C5—C6—H6125 (2)
N22—N21—C24113.1 (4)C21—C26—C25121.2 (5)
N1—N2—C11113.4 (4)C21—C26—H26118 (2)
N21—N22—C31113.5 (4)C25—C26—H26120 (2)
O3—N3—O2123.2 (5)C12—C11—C16117.7 (4)
O3—N3—C12118.2 (5)C12—C11—N2118.3 (4)
O2—N3—C12118.6 (5)C16—C11—N2123.9 (4)
O23—N23—O22122.7 (5)C36—C31—C32117.7 (4)
O23—N23—C32118.8 (4)C36—C31—N22125.1 (4)
O22—N23—C32118.6 (4)C32—C31—N22116.9 (4)
C6—C1—O1117.3 (4)C11—C12—C13123.0 (5)
C6—C1—C2120.3 (4)C11—C12—N3119.3 (4)
O1—C1—C2122.4 (5)C13—C12—N3117.8 (5)
C26—C21—O21118.4 (5)C33—C32—C31123.1 (5)
C26—C21—C22119.7 (5)C33—C32—N23116.4 (5)
O21—C21—C22122.0 (5)C31—C32—N23120.5 (4)
C3—C2—C1119.8 (5)C14—C13—C12118.2 (5)
C3—C2—H2122 (2)C14—C13—H13121 (2)
C1—C2—H2119 (2)C12—C13—H13121 (2)
C23—C22—C21119.9 (5)C34—C33—C32118.2 (5)
C23—C22—H22122.3 (18)C34—C33—H33123 (3)
C21—C22—H22117.7 (18)C32—C33—H33118 (3)
C2—C3—C4120.4 (4)C13—C14—C15120.2 (5)
C2—C3—H3120 (2)C13—C14—H14116 (2)
C4—C3—H3119 (2)C15—C14—H14123 (2)
C22—C23—C24120.4 (5)C33—C34—C35121.0 (5)
C22—C23—H23126 (2)C33—C34—H34120 (2)
C24—C23—H23114 (2)C35—C34—H34119 (2)
C5—C4—C3119.6 (4)C14—C15—C16121.0 (5)
C5—C4—N1115.5 (4)C14—C15—H15117 (2)
C3—C4—N1124.9 (4)C16—C15—H15122 (2)
C23—C24—C25120.1 (4)C34—C35—C36119.9 (5)
C23—C24—N21124.3 (4)C34—C35—H35124 (2)
C25—C24—N21115.6 (4)C36—C35—H35116 (2)
C4—C5—C6119.9 (5)C11—C16—C15119.8 (5)
C4—C5—H5119 (2)C11—C16—H16118 (2)
C6—C5—H5121 (2)C15—C16—H16121 (2)
C26—C25—C24118.8 (5)C31—C36—C35120.0 (5)
C26—C25—H25122 (2)C31—C36—H36120 (3)
C24—C25—H25119 (2)C35—C36—H36120 (3)
C4—N1—N2—C11178.8 (4)C16—C11—C12—C131.5 (8)
C24—N21—N22—C31179.6 (4)N2—C11—C12—C13174.9 (5)
C6—C1—C2—C30.5 (7)C16—C11—C12—N3178.6 (4)
O1—C1—C2—C3179.1 (4)N2—C11—C12—N34.9 (7)
C26—C21—C22—C230.3 (7)O3—N3—C12—C11128.0 (5)
O21—C21—C22—C23179.8 (5)O2—N3—C12—C1151.3 (7)
C1—C2—C3—C40.5 (7)O3—N3—C12—C1351.8 (7)
C21—C22—C23—C240.7 (8)O2—N3—C12—C13128.9 (6)
C2—C3—C4—C51.2 (7)C36—C31—C32—C330.7 (7)
C2—C3—C4—N1178.5 (4)N22—C31—C32—C33175.3 (5)
N2—N1—C4—C5173.8 (4)C36—C31—C32—N23179.2 (4)
N2—N1—C4—C35.9 (6)N22—C31—C32—N234.5 (6)
C22—C23—C24—C250.0 (7)O23—N23—C32—C3351.1 (7)
C22—C23—C24—N21178.1 (5)O22—N23—C32—C33130.0 (5)
N22—N21—C24—C234.2 (6)O23—N23—C32—C31128.7 (5)
N22—N21—C24—C25174.0 (4)O22—N23—C32—C3150.1 (7)
C3—C4—C5—C61.9 (7)C11—C12—C13—C141.7 (8)
N1—C4—C5—C6177.9 (4)N3—C12—C13—C14178.5 (5)
C23—C24—C25—C261.0 (7)C31—C32—C33—C340.6 (8)
N21—C24—C25—C26177.2 (4)N23—C32—C33—C34179.6 (5)
O1—C1—C6—C5179.8 (4)C12—C13—C14—C151.7 (9)
C2—C1—C6—C51.1 (7)C32—C33—C34—C351.4 (8)
C4—C5—C6—C11.9 (7)C13—C14—C15—C161.6 (9)
O21—C21—C26—C25179.2 (4)C33—C34—C35—C361.0 (9)
C22—C21—C26—C250.7 (7)C12—C11—C16—C151.4 (7)
C24—C25—C26—C211.4 (7)N2—C11—C16—C15174.9 (4)
N1—N2—C11—C12166.8 (4)C14—C15—C16—C111.4 (8)
N1—N2—C11—C1617.0 (6)C32—C31—C36—C351.1 (7)
N21—N22—C31—C3622.8 (6)N22—C31—C36—C35175.3 (5)
N21—N22—C31—C32162.9 (4)C34—C35—C36—C310.4 (8)

Experimental details

(Ia)(Ib)
Crystal data
Chemical formulaC12H9N3O3C12H9N3O3
Mr243.22243.22
Crystal system, space groupTriclinic, P1Monoclinic, P21/n
Temperature (K)293293
a, b, c (Å)7.114 (2), 7.380 (2), 10.849 (4)3.823 (1), 23.014 (8), 25.437 (9)
α, β, γ (°)96.68 (2), 97.49 (2), 100.54 (2)90, 92.73 (3), 90
V3)549.4 (3)2235.5 (13)
Z28
Radiation typeMo KαMo Kα
µ (mm1)0.110.11
Crystal size (mm)0.44 × 0.25 × 0.180.39 × 0.12 × 0.07
Data collection
DiffractometerEnraf-Nonius CAD-4
diffractometer
Enraf-Nonius CAD-4
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
2395, 2395, 1599 4574, 3954, 1544
Rint0.0000.046
(sin θ/λ)max1)0.6380.594
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.038, 0.101, 1.12 0.066, 0.124, 0.98
No. of reflections23953954
No. of parameters199397
H-atom treatmentAll H-atom parameters refinedAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.13, 0.130.16, 0.15

Computer programs: CAD-4 Software (Enraf-Nonius, 1989), CAD-4 Software, PROFIT (Streltsov & Zavodnik, 1989), SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997) and PLUTON92 (Spek, 1992), PARST (Nardelli, 1983).

Selected geometric parameters (Å, °) for (Ia) and (Ib). top
(Ia)(Ib)
Molecule 1Molecule 2
C4-N1-N2-C11178.0 (1)178.8 (4)-179.6 (4)
O2···N22.726 (2)2.788 (5)2.771 (5)
Interplanar angles:
C1-C6/C4,N1,N2,C1111.12 (9)6.7 (3)5.8 (3)
C4,N1,N2,C11/C11-C1610.93 (9)15.7 (3)19.9 (3)
C1-C6/C11-C161.73 (9)22.0 (3)25.2 (3)
N3,O2,O3/C11-C1638.44 (6)51.6 (2)51.0 (2)
Hydrogen-bonding geometry (Å, °) for (Ia) and (Ib). top
D-H···AD-HH···AD···AD-H···A
(Ia)O1-H1···O2i0.96 (2)1.93 (2)2.879 (2)174 (2)
(Ib)O1-H1···O3ii0.79 (5)2.23 (5)2.933 (5)148 (5)
(Ib)O21-H21···O1iii0.79 (4)2.10 (4)2.866 (5)164 (4)
Symmetry codes: (i) -x, -y, 1 - z; (ii) 2 - x, -y, 1 - z; (iii) 3/2 - x, 1/2 + y, 1/2 - z.
 

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