Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270103009521/bm1529sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270103009521/bm1529IVsup2.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270103009521/bm1529Vsup3.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270103009521/bm1529VIsup4.hkl | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270103009521/bm1529VIIsup5.hkl |
CCDC references: 217147; 217148; 217149; 217150
The syntheses of compounds (IV)-(VI) have been published previously (Sheremetev, Aleksandrova et al., 2000, Sheremetev et al., 2002) (IV), (Sheremetev et al., 1996) (V), (Sheremetev, Kulagina et al.l., 1998) (VI). Crystals of (IV)–(VI) suitable for X-ray analysis were grown from CHCl3 solution. Compound (VII) was prepared by the dropwise addition of 4,4'-dinitroazofurazan (2.56 g, 10 mmol) in diglyme (10 ml) to a stirred solution of 3-cyano-4-hydroxyfurazan Na-salt (2.66 g, 20 mmol) in diglyme (40 ml) under dry conditions. The resulting mixture was stirred for 1.5–2 h at 50–60°C. TLC indicated complete reaction. The mixture was cooled, poured into water, and extracted with CH2Cl2 (3× 60 ml). The combined extracts were washed with water, dried (MgSO4), filtered and concentrated to give 2.73 g. (72%) of (VII) as yellow-orange crystals. An analytically pure sample and a sample for X-ray analysis were prepared by recrystallization from hexane, mp 147–148°C. 13C NMR (acetone-d6, δ): 106.5 (C≡N), 128.9 (C—C≡N), 155.4 (C—NN), 158.8 (C—C—NN), 182.6 (C—O). MS (EI), m/z: 384 [M+], 354 [M+—NO], 324 [M+-2NO]. IR 2270 (CN), 1565, 1480, 1415, 1395, 1255, 1220, 1025 cm-1. C10N12O6 (384.19): calcd. C 31.26, N 43.75; found: C 31.18, N 43.82.
Symmetrical difurazanyl ether derivatives, such as bis(3-nitrofurazan-4-yl) ether, (I) (Sheremetev et al., 1996; Sheremetev et al., 1998?), bis[3-(nitro-N,N,O-azoxy)furazan-4-yl] ether, (II) (Sheremetev, Semenov et al., 1998), and bis[3-(5H-[1,2,3]triazolo[4,5-c]furazan-5-yl)furazan-4-yl] ether, (III) (Sheremetev et al., 1999), have been developed as highly energetic materials having good explosive performance in a variety of industrial, military, and space applications. The impact and friction sensitivities of these compounds are similar to those of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). In addition to continuing efforts in the preparation of highly energetic materials, recent research in our group has focused on hydrogen-free propellant ingredients. Our approach to the synthesis of energetic compounds is to employ the inherent stability and flexibility of the difurazanyl ether skeleton, and to enhance the enthalpy of formation by the inclusion of cyano groups. We have prepared a large number of known and new cyano derivatives of furazan and studied their properties (Sheremetev et al., 1995; Sheremetev et al., 1998?; Sheremetev et al., 2000?; Sinditskii et al., 1998). The different functional groups were chosen in order to modify the physical properties of the target ethers (e.g. melting point, oxygen balance, plasticity and solubility) and to probe the effects of the substituents on the overall lattice architecture and crystal density. 3-Cyanofurazanyl 3-nitrofurazanyl ether, (IV) (Sheremetev, Aleksandrova et al., 2000; Sheremetev et al., 2002), and bis(3-cyanofurazonyl) ether, (V) (Sheremetev et al., 1996), incorporating two furazan rings, and 3,4-bis(3-cyanofurazan-4-yloxy)furazan, (VI) (Sheremetev, Kulagina et al., 1998), having three rings were prepared as previously described. We report here their structures, along with that of the new compound bis[3-(3-cyanofurazan-4-yloxy)furazan-4-yl]diazene, (VII).
We have explored the influence on the difurazanyl ether fragment of different functional groups, such as nitro [R = NO2, (IV)], less electron-withdrawing substitutents [R = –N═N–furazan, (VII), and R = CN, (V)] and an electron-donating moiety [R = O-furazan, (VI)]. The bond lengths of the difurazanyl ether fragments in molecules (II)–(V) and (VII) are very similar and close to the average values published for each type of bond (Allen et al., 1987; Table 1). There are two topologically equivalent N—O bonds in each furazan ring. According to experimental data these N—O bonds have different lengths in (II)–(V) and (VII); those adjacent to an electron-withdrawing substituent are in the range 1.360 (2)–1.375 (5) Å (mean 1.369 Å), while the N–O bonds adjacent to the electron-donating oxygen bridge are in the range 1.385 (3)–1.390 (2) Å (mean 1.388 Å) (see Table 1). This is in agreement with a report by Batsanov et al. (1985), where the shortening of furazan N—O bonds adjacent to electron-withdrawing substituents, relative to those adjacent to electron-releasing substituents, was first pointed out. Molecule (VI) is similar to molecule (IV), but contains additional furazan rings between the two terminal cyano-bearing furazan rings. It was found that these terminal rings in molecule (VI) have the same geometry as in molecules (II)–(V) and (VII), while its symmetrically substituted central furazan ring has very similar N—O bond lengths of 1.387 (4) and 1.389 (4) Å.
The bond lengths in the two independent molecules of (I) differ significantly from those in molecules (II)–(VII). However, as there are also large discrepancies of up to 0.06–0.07 Å in the lengths of chemically equivalent bonds in the two independent molecules of (I), we cannot consider the structure of (I) to be reliable at a level sufficient to allow discussion of its bond lengths. For structures (II)–(VII), the ether C—O bond distances are in the range 1.336 (3)–1.358 (4) Å (mean 1.350 Å), intermediate between single C–O (1.42 Å) and double C═O (1.21 Å) bonds, indicating resonance between the furazan π-system and the lone pairs of bridging atom O8. This is also confirmed by the increase in the bond angle at O8 to an average value of 121°. The bond lengths of the cyano groups in (IV)–(VII) are in the range 1.116 (5)–1.134 (3) Å (mean 1.127 Å). Due to conjugation between the furazan rings and the cyano groups, the cyano NC—C(furazan) bonds are shortened and have bond lengths in the range 1.428 (3)–1.4359 (19) Å (mean 1.432 Å). In (V), the dihedral angle between the furazan ring and the plane of the nitro group is 18.1°, and the length of the N(nitro)—C(furazan) bond is 1.452 (3) Å. Analysis of data from the Cambridge Structural Database (Allen, 2002) shows that the latter value is close to the standard value of 1.46 Å for a Csp2—NO2 bond length. In (VII), the azo group conjugates neighbouring furazan rings, as evidenced by the N═N bond length of 1.247 (3) Å and the N(azo)—C(furazan) bond length of 1.410 (3) Å.
Molecules (I)–(III) and (V)–(VII) are non-planar. In contrast, (IV) can be considered as approximaetely planar as the r.m.s. deviation from the molecular least-squares mean plane is only 0.18 Å. The only difference between the difurazanyl ether fragments in all seven structures is the twist between the two component rings. The conformation of the difurazanyl ether fragment can be described by the torsion angles N6—C7—O8—C9 and N10—C9—O8—C7 (Table 2). If these torsion angles have the same sign, the approximate symmetry of the difurazanyl ether is C2 (Fig. 2a), but with opposing signs it is Cs (Fig. 2 b). It is clear from Table 2 and Figs. 2(a) and 2(b) that the dihedral angle between the furazan rings does not uniquely describe the conformation of the difurazanyl ether fragment. Structures (I), (III), (V) and (VI) have a C2 conformation for the difurazanyl ether fragment, while structures (II), (IV), and (VII) adopt Cs conformations.
To determine the optimal conformation of the difurazanyl ether fragment we optimized the geometry of (IV) using the GAUSSIAN94 program (Frisch et al., 1994) at the MP2/cc-pvdz level of theory. This showed that the conformations of the calculated and experimental molecules are different. The calculated N6—C7—O8—C9 and N10—C9—O8—C7 torsion angles have the same sign and value (7.1°)·Hence, in contrast to experimental molecule (IV), which has approximate Cs symmetry, the calculated molecule has C2 symmetry. The observed dihedral angle between the furazan rings is 24.3 (1)°, whereas the calculated value is 11.8°. To compare the energies of these two conformations, we carried out another calculation with the torsion angles fixed at the experimentally observed values of -28.0 and 20.3°, respectively. This calculation revealed that the energy difference between the two conformations is rather small (1.313 kJ mol-1), so the difference between experimentally determined and calculated conformations could be due to crystal-packing effects which were not included in the calculations.
In the crystal packing of (IV), essentially planar molecules are arranged to form flat ribbons normal to the (201) crystallographic plane, with the ribbons adopting a parquet motif. The packing arrangements for (V), (VI) and (VII) do not assume a readily identifiable motif, a common sitituation with space groups P212121 and Pbca. In (V) and (VI), two intermolecular contacts involving cyano groups were found; in (V), the cyano group approaches O15 from the nitro group [C2···O15(0.5 - x, 1 - y, z - 0.5) = 2.957 (3) Å], while in (VI), there is a contact between the cyano group and a furazan ring [N21···C15(0.5 + x, -0.5 - y, -z) = 2.969 (3) Å]. These interactions can be ascribed to the coulombic interactions of atoms bearing partial opposite charges. No other intermolecular contacts in (IV)–(VII) lie within the sum of the relevant van der Waals radii (Bondi, 1964).
It is well known that high density is a factor favouring good explosive performance. Although we do not have enough data for a representative statistical analysis, we decided to investigate the relationship between the molecular structure and density of crystal packing for the seven difurazanyl ethers (I)-(VII). For this purpose, molecular volume (V) or molecular surface (S), and molecular mass (M) were used. All calculations were carried out using the NONVPOT program (Shil'nikov, 1994) and the radii of Bondi (1964). Comparison of the calculated ratio M/S with X-ray density, dX-ray, shows a moderate dependence of M/S on dX-ray, with a correlation coefficient of 0.884. Better agreement was found by considering `molecular density', dmol, which is the ratio of molecular mass M to molecular volume V. Fig. 3 shows the dependence of crystal density on molecular density, the correlation coefficient in this case being 0.916. This figure also shows that while the crystal density of (III) is higher than expected, the values for (II) and (V) are lower. According to Kitaigorodsky (1973), crystal density can be presented as a product of packing coefficient k and molecular density, dX-ray = k × dmol. Calculated packing coefficients, molecular densities and crystal densities for compounds (I)–(VII) are presented in Table 3. Since the packing coefficient influences crystal density, the search for crystals with high density should consider ways of increasing both dmol and k. According to Kuzmina et al. (1990), there is a tendency for k to decrease with increasing dmol. This relationship restricts the possibilities of obtaining extremely dense structures, but because of its statistical nature exceptions do occur. Compound (III), which has a rather large value of dmol, is a good example of such an exception; while the mean k value for (I)–(VII) is 0.71, for (III) it is higher, at 0.749. Analysis of the factors responsible for the high packing coefficients for this and other compounds will help us to predict compounds likely to exhibit high density.
Data collection: P3/PC (Siemens, 1989) for (IV), (V), (VI); CAD-4 Software (Enraf-Nonius, 1989) for (VII). Cell refinement: P3/PC for (IV), (V), (VI); CAD-4 Software for (VII). Data reduction: P3/PC for (IV), (V), (VI); XCAD4 (Harms, 1996) for (VII). For all compounds, program(s) used to solve structure: SHELXTL (Sheldrick, 1998); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
C6N6O3 | F(000) = 408 |
Mr = 204.12 | Dx = 1.626 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
a = 13.639 (3) Å | Cell parameters from 24 reflections |
b = 8.899 (2) Å | θ = 12–13° |
c = 6.9254 (17) Å | µ = 0.14 mm−1 |
β = 97.13 (2)° | T = 293 K |
V = 834.1 (4) Å3 | Rectangular prism, colorless |
Z = 4 | 0.5 × 0.4 × 0.4 mm |
Siemens P3/PC diffractometer | Rint = 0.008 |
Radiation source: fine-focus sealed tube | θmax = 25.1°, θmin = 2.7° |
Graphite monochromator | h = 0→16 |
θ/2θ scans | k = 0→10 |
1534 measured reflections | l = −8→8 |
1471 independent reflections | 2 standard reflections every 98 reflections |
1276 reflections with I > 2σ(I) | intensity decay: 12% |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Primary atom site location: structure-invariant direct methods |
R[F2 > 2σ(F2)] = 0.034 | Secondary atom site location: difference Fourier map |
wR(F2) = 0.101 | w = 1/[σ2(Fo2) + (0.072P)2 + 0.022P] where P = (Fo2 + 2Fc2)/3 |
S = 1.09 | (Δ/σ)max < 0.001 |
1471 reflections | Δρmax = 0.13 e Å−3 |
136 parameters | Δρmin = −0.19 e Å−3 |
C6N6O3 | V = 834.1 (4) Å3 |
Mr = 204.12 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 13.639 (3) Å | µ = 0.14 mm−1 |
b = 8.899 (2) Å | T = 293 K |
c = 6.9254 (17) Å | 0.5 × 0.4 × 0.4 mm |
β = 97.13 (2)° |
Siemens P3/PC diffractometer | Rint = 0.008 |
1534 measured reflections | 2 standard reflections every 98 reflections |
1471 independent reflections | intensity decay: 12% |
1276 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.034 | 136 parameters |
wR(F2) = 0.101 | 0 restraints |
S = 1.09 | Δρmax = 0.13 e Å−3 |
1471 reflections | Δρmin = −0.19 e Å−3 |
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. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.19094 (11) | 0.70859 (17) | −0.4592 (2) | 0.0787 (4) | |
C2 | 0.15764 (10) | 0.61957 (16) | −0.37020 (19) | 0.0564 (3) | |
C3 | 0.11945 (10) | 0.50804 (14) | −0.24959 (18) | 0.0523 (3) | |
N4 | 0.02968 (9) | 0.45767 (16) | −0.2818 (2) | 0.0704 (4) | |
O5 | 0.02177 (8) | 0.35825 (13) | −0.13341 (17) | 0.0778 (4) | |
N6 | 0.10854 (9) | 0.34768 (14) | −0.00679 (18) | 0.0656 (4) | |
C7 | 0.16739 (9) | 0.43990 (13) | −0.07952 (18) | 0.0505 (3) | |
O8 | 0.26260 (6) | 0.46739 (10) | −0.01040 (13) | 0.0558 (3) | |
C9 | 0.29394 (10) | 0.45189 (13) | 0.18159 (19) | 0.0516 (3) | |
N10 | 0.25140 (9) | 0.37481 (14) | 0.30552 (18) | 0.0666 (4) | |
O11 | 0.31107 (8) | 0.39759 (13) | 0.48055 (15) | 0.0726 (3) | |
N12 | 0.38935 (9) | 0.48802 (14) | 0.45862 (18) | 0.0670 (4) | |
C13 | 0.38014 (10) | 0.52160 (14) | 0.2754 (2) | 0.0542 (3) | |
C14 | 0.45006 (12) | 0.61276 (17) | 0.1904 (2) | 0.0675 (4) | |
N15 | 0.50433 (13) | 0.6815 (2) | 0.1154 (2) | 0.0995 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0859 (9) | 0.0765 (9) | 0.0743 (8) | 0.0019 (7) | 0.0124 (7) | 0.0172 (7) |
C2 | 0.0544 (7) | 0.0578 (8) | 0.0568 (7) | 0.0045 (6) | 0.0062 (6) | −0.0024 (6) |
C3 | 0.0491 (7) | 0.0495 (7) | 0.0597 (8) | 0.0007 (5) | 0.0126 (5) | −0.0107 (5) |
N4 | 0.0554 (7) | 0.0804 (8) | 0.0762 (8) | −0.0103 (6) | 0.0111 (6) | −0.0115 (6) |
O5 | 0.0592 (6) | 0.0837 (8) | 0.0929 (7) | −0.0239 (5) | 0.0192 (5) | −0.0076 (6) |
N6 | 0.0584 (7) | 0.0599 (7) | 0.0816 (8) | −0.0110 (5) | 0.0211 (6) | −0.0003 (6) |
C7 | 0.0499 (7) | 0.0414 (6) | 0.0631 (7) | −0.0013 (5) | 0.0186 (5) | −0.0046 (5) |
O8 | 0.0479 (5) | 0.0595 (6) | 0.0615 (6) | −0.0035 (4) | 0.0122 (4) | 0.0100 (4) |
C9 | 0.0513 (7) | 0.0425 (6) | 0.0635 (7) | 0.0064 (5) | 0.0163 (5) | 0.0086 (5) |
N10 | 0.0653 (7) | 0.0646 (7) | 0.0722 (7) | −0.0023 (6) | 0.0187 (6) | 0.0166 (6) |
O11 | 0.0708 (7) | 0.0818 (7) | 0.0678 (6) | 0.0041 (6) | 0.0190 (5) | 0.0212 (5) |
N12 | 0.0650 (8) | 0.0686 (7) | 0.0683 (8) | 0.0042 (6) | 0.0119 (6) | 0.0119 (6) |
C13 | 0.0530 (7) | 0.0481 (7) | 0.0622 (8) | 0.0056 (6) | 0.0105 (6) | 0.0081 (5) |
C14 | 0.0654 (9) | 0.0643 (9) | 0.0711 (9) | −0.0111 (7) | 0.0013 (7) | 0.0134 (7) |
N15 | 0.0921 (11) | 0.1033 (12) | 0.1017 (11) | −0.0347 (9) | 0.0061 (8) | 0.0289 (9) |
N1—C2 | 1.1326 (18) | O8—C9 | 1.3522 (16) |
C2—C3 | 1.4359 (19) | C9—N10 | 1.2912 (17) |
C3—N4 | 1.2969 (19) | C9—C13 | 1.414 (2) |
C3—C7 | 1.4111 (18) | N10—O11 | 1.3885 (17) |
N4—O5 | 1.3704 (18) | O11—N12 | 1.3604 (17) |
O5—N6 | 1.3858 (18) | N12—C13 | 1.2946 (18) |
N6—C7 | 1.2930 (16) | C13—C14 | 1.433 (2) |
C7—O8 | 1.3494 (15) | C14—N15 | 1.134 (2) |
N1—C2—C3 | 177.07 (15) | N10—C9—O8 | 126.48 (13) |
N4—C3—C7 | 108.95 (12) | N10—C9—C13 | 110.14 (13) |
N4—C3—C2 | 122.79 (13) | O8—C9—C13 | 123.38 (11) |
C7—C3—C2 | 128.22 (12) | C9—N10—O11 | 103.86 (12) |
C3—N4—O5 | 104.75 (12) | N12—O11—N10 | 111.84 (10) |
N4—O5—N6 | 112.20 (10) | C13—N12—O11 | 105.30 (12) |
C7—N6—O5 | 103.48 (11) | N12—C13—C9 | 108.84 (13) |
N6—C7—O8 | 126.40 (12) | N12—C13—C14 | 123.01 (13) |
N6—C7—C3 | 110.62 (12) | C9—C13—C14 | 128.13 (13) |
O8—C7—C3 | 122.95 (11) | N15—C14—C13 | 176.89 (18) |
C7—O8—C9 | 120.21 (10) | ||
C7—C3—N4—O5 | −0.27 (14) | C7—O8—C9—N10 | 20.33 (19) |
C2—C3—N4—O5 | −178.20 (11) | C7—O8—C9—C13 | −159.13 (12) |
C3—N4—O5—N6 | 0.20 (15) | O8—C9—N10—O11 | −178.88 (12) |
N4—O5—N6—C7 | −0.05 (14) | C13—C9—N10—O11 | 0.64 (14) |
O5—N6—C7—O8 | −178.38 (12) | C9—N10—O11—N12 | −0.31 (15) |
O5—N6—C7—C3 | −0.12 (14) | N10—O11—N12—C13 | −0.17 (16) |
N4—C3—C7—N6 | 0.26 (15) | O11—N12—C13—C9 | 0.55 (15) |
C2—C3—C7—N6 | 178.05 (12) | O11—N12—C13—C14 | −178.24 (13) |
N4—C3—C7—O8 | 178.59 (12) | N10—C9—C13—N12 | −0.80 (16) |
C2—C3—C7—O8 | −3.62 (19) | O8—C9—C13—N12 | 178.74 (12) |
N6—C7—O8—C9 | −28.61 (19) | N10—C9—C13—C14 | 177.91 (13) |
C3—C7—O8—C9 | 153.33 (11) | O8—C9—C13—C14 | −2.6 (2) |
C5N6O5 | Dx = 1.763 Mg m−3 |
Mr = 224.11 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, P212121 | Cell parameters from 24 reflections |
a = 7.853 (2) Å | θ = 11–12° |
b = 8.791 (2) Å | µ = 0.16 mm−1 |
c = 12.229 (3) Å | T = 293 K |
V = 844.2 (4) Å3 | Rectangular prism, yellow |
Z = 4 | 0.6 × 0.5 × 0.4 mm |
F(000) = 448 |
Siemens P3/PC diffractometer | Rint = 0.0 |
Radiation source: fine-focus sealed tube | θmax = 30.1°, θmin = 2.9° |
Graphite monochromator | h = 0→11 |
θ/2θ scans | k = 0→12 |
1433 measured reflections | l = 0→17 |
1433 independent reflections | 2 standard reflections every 98 reflections |
1164 reflections with I > 2σ(I) | intensity decay: 3% |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.045 | w = 1/[σ2(Fo2) + (0.0882P)2] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.121 | (Δ/σ)max = 0.001 |
S = 1.02 | Δρmax = 0.27 e Å−3 |
1433 reflections | Δρmin = −0.23 e Å−3 |
145 parameters | Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881 |
0 restraints | Absolute structure parameter: not reliably determined |
C5N6O5 | V = 844.2 (4) Å3 |
Mr = 224.11 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 7.853 (2) Å | µ = 0.16 mm−1 |
b = 8.791 (2) Å | T = 293 K |
c = 12.229 (3) Å | 0.6 × 0.5 × 0.4 mm |
Siemens P3/PC diffractometer | Rint = 0.0 |
1433 measured reflections | 2 standard reflections every 98 reflections |
1433 independent reflections | intensity decay: 3% |
1164 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.121 | Δρmax = 0.27 e Å−3 |
S = 1.02 | Δρmin = −0.23 e Å−3 |
1433 reflections | Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881 |
145 parameters | Absolute structure parameter: not reliably determined |
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. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.0832 (3) | 0.9050 (2) | −0.0165 (2) | 0.0785 (7) | |
C2 | 0.0203 (3) | 0.8090 (2) | −0.0611 (2) | 0.0537 (5) | |
C3 | −0.0545 (3) | 0.6828 (2) | −0.11701 (18) | 0.0483 (4) | |
N4 | −0.1255 (3) | 0.6929 (3) | −0.2121 (2) | 0.0670 (6) | |
O5 | −0.1779 (3) | 0.5484 (2) | −0.23731 (15) | 0.0720 (5) | |
N6 | −0.1383 (3) | 0.4470 (2) | −0.15446 (16) | 0.0590 (5) | |
C7 | −0.0635 (2) | 0.5288 (2) | −0.08212 (17) | 0.0450 (4) | |
O8 | 0.0027 (2) | 0.48357 (15) | 0.01431 (13) | 0.0558 (4) | |
C9 | −0.0433 (2) | 0.3479 (2) | 0.05784 (16) | 0.0444 (4) | |
N10 | −0.1617 (2) | 0.2591 (2) | 0.02356 (16) | 0.0557 (5) | |
O11 | −0.1614 (2) | 0.13986 (18) | 0.09789 (16) | 0.0629 (4) | |
N12 | −0.0427 (2) | 0.1600 (2) | 0.17751 (17) | 0.0576 (5) | |
C13 | 0.0294 (2) | 0.2875 (2) | 0.15376 (16) | 0.0451 (4) | |
N14 | 0.1663 (2) | 0.3473 (2) | 0.22108 (15) | 0.0521 (4) | |
O15 | 0.1804 (3) | 0.2959 (3) | 0.31297 (16) | 0.0744 (5) | |
O16 | 0.2566 (2) | 0.4433 (2) | 0.18071 (16) | 0.0642 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0843 (15) | 0.0633 (12) | 0.0879 (15) | −0.0119 (13) | −0.0030 (15) | −0.0099 (12) |
C2 | 0.0540 (11) | 0.0462 (10) | 0.0608 (11) | −0.0016 (9) | 0.0026 (10) | 0.0001 (9) |
C3 | 0.0426 (8) | 0.0494 (10) | 0.0530 (10) | 0.0012 (8) | 0.0019 (8) | 0.0009 (8) |
N4 | 0.0698 (13) | 0.0652 (12) | 0.0659 (13) | −0.0058 (11) | −0.0130 (11) | 0.0101 (10) |
O5 | 0.0829 (13) | 0.0745 (11) | 0.0586 (9) | −0.0108 (10) | −0.0208 (9) | 0.0003 (9) |
N6 | 0.0614 (10) | 0.0554 (9) | 0.0602 (10) | −0.0020 (9) | −0.0121 (9) | −0.0036 (9) |
C7 | 0.0390 (8) | 0.0459 (9) | 0.0503 (9) | 0.0009 (7) | −0.0028 (8) | −0.0025 (8) |
O8 | 0.0607 (9) | 0.0457 (7) | 0.0610 (8) | −0.0089 (7) | −0.0180 (8) | 0.0049 (6) |
C9 | 0.0429 (8) | 0.0401 (8) | 0.0501 (9) | 0.0042 (7) | −0.0002 (8) | −0.0048 (8) |
N10 | 0.0517 (9) | 0.0484 (8) | 0.0669 (12) | −0.0056 (8) | −0.0084 (9) | −0.0007 (9) |
O11 | 0.0581 (9) | 0.0530 (8) | 0.0776 (10) | −0.0114 (8) | −0.0042 (9) | 0.0046 (8) |
N12 | 0.0550 (9) | 0.0547 (9) | 0.0632 (11) | 0.0012 (9) | 0.0035 (9) | 0.0039 (9) |
C13 | 0.0405 (8) | 0.0453 (9) | 0.0496 (9) | 0.0055 (7) | 0.0055 (8) | −0.0035 (7) |
N14 | 0.0489 (9) | 0.0555 (9) | 0.0518 (9) | 0.0121 (9) | −0.0034 (7) | −0.0121 (8) |
O15 | 0.0744 (11) | 0.0938 (13) | 0.0549 (9) | 0.0121 (12) | −0.0107 (9) | 0.0014 (10) |
O16 | 0.0581 (9) | 0.0635 (10) | 0.0709 (10) | −0.0077 (9) | −0.0056 (9) | −0.0098 (9) |
N1—C2 | 1.120 (3) | C9—N10 | 1.284 (3) |
C2—C3 | 1.429 (3) | C9—C13 | 1.408 (3) |
C3—N4 | 1.293 (3) | N10—O11 | 1.387 (3) |
C3—C7 | 1.422 (3) | O11—N12 | 1.360 (3) |
N4—O5 | 1.370 (3) | N12—C13 | 1.289 (3) |
O5—N6 | 1.385 (3) | C13—N14 | 1.453 (3) |
N6—C7 | 1.282 (3) | N14—O16 | 1.208 (3) |
C7—O8 | 1.349 (3) | N14—O15 | 1.216 (3) |
O8—C9 | 1.355 (2) | ||
N1—C2—C3 | 177.9 (3) | N10—C9—C13 | 109.66 (18) |
N4—C3—C7 | 108.3 (2) | O8—C9—C13 | 123.42 (18) |
N4—C3—C2 | 123.7 (2) | C9—N10—O11 | 104.12 (17) |
C7—C3—C2 | 128.0 (2) | N12—O11—N10 | 111.82 (15) |
C3—N4—O5 | 105.6 (2) | C13—N12—O11 | 104.66 (18) |
N4—O5—N6 | 111.39 (16) | N12—C13—C9 | 109.72 (19) |
C7—N6—O5 | 104.28 (18) | N12—C13—N14 | 120.8 (2) |
N6—C7—O8 | 127.93 (19) | C9—C13—N14 | 129.48 (19) |
N6—C7—C3 | 110.47 (19) | O16—N14—O15 | 125.7 (2) |
O8—C7—C3 | 121.60 (18) | O16—N14—C13 | 117.12 (18) |
C7—O8—C9 | 120.01 (16) | O15—N14—C13 | 117.2 (2) |
N10—C9—O8 | 126.84 (19) | ||
C7—C3—N4—O5 | −0.2 (3) | O8—C9—N10—O11 | −177.78 (19) |
C2—C3—N4—O5 | 179.0 (2) | C13—C9—N10—O11 | −1.0 (2) |
C3—N4—O5—N6 | 0.3 (3) | C9—N10—O11—N12 | 0.8 (2) |
N4—O5—N6—C7 | −0.3 (3) | N10—O11—N12—C13 | −0.1 (2) |
O5—N6—C7—O8 | −178.9 (2) | O11—N12—C13—C9 | −0.5 (2) |
O5—N6—C7—C3 | 0.2 (2) | O11—N12—C13—N14 | −179.50 (17) |
N4—C3—C7—N6 | 0.0 (3) | N10—C9—C13—N12 | 1.1 (2) |
C2—C3—C7—N6 | −179.2 (2) | O8—C9—C13—N12 | 177.93 (18) |
N4—C3—C7—O8 | 179.2 (2) | N10—C9—C13—N14 | 179.92 (19) |
C2—C3—C7—O8 | 0.0 (4) | O8—C9—C13—N14 | −3.2 (3) |
N6—C7—O8—C9 | −17.3 (3) | N12—C13—N14—O16 | 161.27 (18) |
C3—C7—O8—C9 | 163.60 (19) | C9—C13—N14—O16 | −17.5 (3) |
C7—O8—C9—N10 | −8.6 (3) | N12—C13—N14—O15 | −18.4 (3) |
C7—O8—C9—C13 | 175.08 (18) | C9—C13—N14—O15 | 162.9 (2) |
C8N8O5 | Dx = 1.628 Mg m−3 |
Mr = 288.16 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, P212121 | Cell parameters from 24 reflections |
a = 7.8295 (15) Å | θ = 13–14° |
b = 8.6273 (18) Å | µ = 0.14 mm−1 |
c = 17.409 (3) Å | T = 293 K |
V = 1175.9 (4) Å3 | Rectangular prism, colorless |
Z = 4 | 0.4 × 0.3 × 0.3 mm |
F(000) = 576 |
Siemens P3/PC diffractometer | Rint = 0.0 |
Radiation source: fine-focus sealed tube | θmax = 27.1°, θmin = 2.3° |
Graphite monochromator | h = 0→10 |
θ/2θ scans | k = 0→11 |
1469 measured reflections | l = 0→22 |
1469 independent reflections | 2 standard reflections every 98 reflections |
1267 reflections with I > 2σ(I) | intensity decay: 2% |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | w = 1/[σ2(Fo2) + (0.092P)2 + 0.0462P] where P = (Fo2 + 2Fc2)/3 |
R[F2 > 2σ(F2)] = 0.045 | (Δ/σ)max < 0.001 |
wR(F2) = 0.128 | Δρmax = 0.16 e Å−3 |
S = 1.05 | Δρmin = −0.18 e Å−3 |
1469 reflections | Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
191 parameters | Extinction coefficient: 0.230 (18) |
0 restraints | Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881 |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: not reliably determined |
C8N8O5 | V = 1175.9 (4) Å3 |
Mr = 288.16 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 7.8295 (15) Å | µ = 0.14 mm−1 |
b = 8.6273 (18) Å | T = 293 K |
c = 17.409 (3) Å | 0.4 × 0.3 × 0.3 mm |
Siemens P3/PC diffractometer | Rint = 0.0 |
1469 measured reflections | 2 standard reflections every 98 reflections |
1469 independent reflections | intensity decay: 2% |
1267 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.128 | Δρmax = 0.16 e Å−3 |
S = 1.05 | Δρmin = −0.18 e Å−3 |
1469 reflections | Absolute structure: Flack H D (1983), Acta Cryst. A39, 876-881 |
191 parameters | Absolute structure parameter: not reliably determined |
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. |
x | y | z | Uiso*/Ueq | ||
N1 | 1.4798 (6) | 0.0283 (7) | 0.1840 (3) | 0.159 (2) | |
C2 | 1.3755 (6) | 0.0889 (5) | 0.2158 (2) | 0.0973 (13) | |
C3 | 1.2418 (4) | 0.1738 (3) | 0.25299 (16) | 0.0661 (7) | |
N4 | 1.2609 (4) | 0.2352 (3) | 0.32031 (14) | 0.0768 (7) | |
O5 | 1.1148 (4) | 0.3176 (3) | 0.33281 (12) | 0.0923 (8) | |
N6 | 1.0013 (4) | 0.3061 (4) | 0.27171 (15) | 0.0866 (8) | |
C7 | 1.0796 (4) | 0.2144 (3) | 0.22446 (15) | 0.0611 (6) | |
O8 | 1.0206 (3) | 0.1618 (2) | 0.15659 (12) | 0.0697 (6) | |
O8' | 0.8778 (3) | 0.04059 (19) | 0.01974 (11) | 0.0662 (5) | |
C9 | 0.8374 (3) | −0.0016 (3) | −0.05184 (15) | 0.0554 (6) | |
N10 | 0.7675 (3) | 0.0810 (3) | −0.10553 (15) | 0.0762 (7) | |
O11 | 0.7611 (4) | −0.0177 (4) | −0.16780 (13) | 0.0959 (8) | |
N12 | 0.8264 (4) | −0.1595 (4) | −0.15097 (15) | 0.0887 (9) | |
C13 | 0.8735 (3) | −0.1506 (3) | −0.08032 (15) | 0.0602 (6) | |
C14 | 0.9480 (4) | −0.2769 (4) | −0.03888 (16) | 0.0717 (8) | |
N15 | 1.0065 (5) | −0.3718 (4) | −0.0031 (2) | 0.1050 (12) | |
C16 | 0.8939 (3) | 0.2340 (3) | 0.11913 (18) | 0.0630 (6) | |
N17 | 0.8191 (4) | 0.3617 (3) | 0.1369 (2) | 0.0872 (8) | |
O18 | 0.7035 (4) | 0.3857 (3) | 0.07770 (18) | 0.1045 (9) | |
N19 | 0.7099 (4) | 0.2679 (4) | 0.02346 (19) | 0.0892 (9) | |
C20 | 0.8246 (3) | 0.1769 (3) | 0.04984 (17) | 0.0637 (7) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.153 (4) | 0.173 (4) | 0.153 (4) | 0.098 (4) | −0.055 (3) | −0.081 (4) |
C2 | 0.116 (3) | 0.084 (2) | 0.092 (2) | 0.038 (2) | −0.042 (2) | −0.0280 (18) |
C3 | 0.0906 (19) | 0.0457 (11) | 0.0621 (13) | −0.0078 (14) | −0.0125 (14) | 0.0005 (10) |
N4 | 0.0981 (18) | 0.0675 (13) | 0.0647 (13) | −0.0075 (15) | −0.0075 (13) | −0.0059 (11) |
O5 | 0.1007 (16) | 0.1105 (18) | 0.0658 (11) | −0.0081 (16) | 0.0111 (12) | −0.0245 (12) |
N6 | 0.0750 (14) | 0.106 (2) | 0.0786 (17) | −0.0074 (17) | 0.0107 (14) | −0.0216 (16) |
C7 | 0.0689 (15) | 0.0515 (12) | 0.0631 (13) | −0.0122 (12) | 0.0019 (12) | 0.0002 (11) |
O8 | 0.0783 (12) | 0.0561 (9) | 0.0748 (11) | 0.0026 (10) | −0.0159 (10) | −0.0106 (9) |
O8' | 0.0736 (11) | 0.0525 (9) | 0.0725 (11) | 0.0050 (9) | −0.0215 (10) | −0.0030 (8) |
C9 | 0.0458 (11) | 0.0570 (11) | 0.0632 (13) | −0.0041 (10) | −0.0068 (10) | 0.0113 (11) |
N10 | 0.0772 (15) | 0.0743 (15) | 0.0771 (15) | 0.0055 (14) | −0.0097 (12) | 0.0184 (13) |
O11 | 0.1100 (18) | 0.1114 (18) | 0.0664 (11) | 0.0327 (17) | −0.0224 (13) | 0.0062 (12) |
N12 | 0.0918 (18) | 0.105 (2) | 0.0694 (15) | 0.0249 (18) | −0.0209 (14) | −0.0044 (14) |
C13 | 0.0528 (12) | 0.0693 (14) | 0.0584 (13) | 0.0053 (12) | −0.0096 (11) | −0.0010 (11) |
C14 | 0.0768 (16) | 0.0697 (15) | 0.0684 (16) | 0.0184 (15) | −0.0133 (14) | −0.0081 (13) |
N15 | 0.128 (3) | 0.0938 (19) | 0.093 (2) | 0.042 (2) | −0.029 (2) | 0.0010 (16) |
C16 | 0.0577 (12) | 0.0516 (12) | 0.0799 (16) | −0.0014 (11) | −0.0034 (13) | −0.0025 (12) |
N17 | 0.0826 (17) | 0.0726 (15) | 0.106 (2) | 0.0142 (14) | −0.0136 (16) | −0.0179 (15) |
O18 | 0.0915 (16) | 0.0874 (15) | 0.135 (2) | 0.0362 (14) | −0.0307 (16) | −0.0266 (16) |
N19 | 0.0758 (15) | 0.0751 (15) | 0.117 (2) | 0.0163 (14) | −0.0277 (16) | −0.0152 (16) |
C20 | 0.0559 (12) | 0.0532 (12) | 0.0819 (16) | −0.0007 (11) | −0.0077 (13) | 0.0022 (12) |
N1—C2 | 1.116 (5) | C9—C13 | 1.406 (4) |
C2—C3 | 1.433 (5) | N10—O11 | 1.379 (4) |
C3—N4 | 1.295 (4) | O11—N12 | 1.358 (4) |
C3—C7 | 1.408 (4) | N12—C13 | 1.286 (4) |
N4—O5 | 1.364 (4) | C13—C14 | 1.431 (4) |
O5—N6 | 1.389 (4) | C14—N15 | 1.126 (4) |
N6—C7 | 1.295 (4) | C16—N17 | 1.285 (4) |
C7—O8 | 1.347 (3) | C16—C20 | 1.411 (4) |
O8—C16 | 1.341 (3) | N17—O18 | 1.387 (4) |
O8'—C9 | 1.336 (3) | O18—N19 | 1.389 (4) |
O8'—C20 | 1.354 (3) | N19—C20 | 1.278 (4) |
C9—N10 | 1.297 (3) | ||
N1—C2—C3 | 176.6 (5) | N12—O11—N10 | 111.9 (2) |
N4—C3—C7 | 108.7 (3) | C13—N12—O11 | 105.1 (3) |
N4—C3—C2 | 122.3 (3) | N12—C13—C9 | 109.5 (3) |
C7—C3—C2 | 128.8 (3) | N12—C13—C14 | 123.6 (3) |
C3—N4—O5 | 105.1 (3) | C9—C13—C14 | 126.9 (2) |
N4—O5—N6 | 112.1 (2) | N15—C14—C13 | 176.6 (3) |
C7—N6—O5 | 103.1 (3) | N17—C16—O8 | 128.2 (3) |
N6—C7—O8 | 126.9 (3) | N17—C16—C20 | 109.3 (3) |
N6—C7—C3 | 110.8 (3) | O8—C16—C20 | 122.6 (2) |
O8—C7—C3 | 122.3 (3) | C16—N17—O18 | 104.3 (3) |
C16—O8—C7 | 121.6 (2) | N17—O18—N19 | 111.8 (2) |
C9—O8'—C20 | 121.7 (2) | C20—N19—O18 | 103.4 (3) |
N10—C9—O8' | 128.5 (3) | N19—C20—O8' | 127.7 (3) |
N10—C9—C13 | 109.5 (2) | N19—C20—C16 | 111.3 (3) |
O8'—C9—C13 | 122.0 (2) | O8'—C20—C16 | 121.1 (2) |
C9—N10—O11 | 104.0 (2) | ||
C7—C3—N4—O5 | −1.9 (3) | O11—N12—C13—C14 | 179.1 (3) |
C2—C3—N4—O5 | 174.2 (3) | N10—C9—C13—N12 | 0.1 (3) |
C3—N4—O5—N6 | 0.4 (3) | O8'—C9—C13—N12 | −178.1 (3) |
N4—O5—N6—C7 | 1.3 (3) | N10—C9—C13—C14 | −178.9 (3) |
O5—N6—C7—O8 | 177.7 (3) | O8'—C9—C13—C14 | 2.9 (4) |
O5—N6—C7—C3 | −2.5 (3) | C7—O8—C16—N17 | 4.7 (4) |
N4—C3—C7—N6 | 3.0 (3) | C7—O8—C16—C20 | −176.9 (3) |
C2—C3—C7—N6 | −172.8 (3) | O8—C16—N17—O18 | 177.8 (3) |
N4—C3—C7—O8 | −177.2 (3) | C20—C16—N17—O18 | −0.7 (3) |
C2—C3—C7—O8 | 7.0 (5) | C16—N17—O18—N19 | 0.2 (4) |
N6—C7—O8—C16 | 20.2 (4) | N17—O18—N19—C20 | 0.4 (4) |
C3—C7—O8—C16 | −159.6 (2) | O18—N19—C20—O8' | 178.1 (3) |
C20—O8'—C9—N10 | 10.4 (4) | O18—N19—C20—C16 | −0.8 (4) |
C20—O8'—C9—C13 | −171.8 (2) | C9—O8'—C20—N19 | 13.6 (4) |
O8'—C9—N10—O11 | 177.8 (3) | C9—O8'—C20—C16 | −167.7 (2) |
C13—C9—N10—O11 | −0.2 (3) | N17—C16—C20—N19 | 1.0 (4) |
C9—N10—O11—N12 | 0.3 (4) | O8—C16—C20—N19 | −177.6 (3) |
N10—O11—N12—C13 | −0.3 (4) | N17—C16—C20—O8' | −177.9 (3) |
O11—N12—C13—C9 | 0.1 (4) | O8—C16—C20—O8' | 3.4 (4) |
C10N12O6 | Dx = 1.690 Mg m−3 |
Mr = 384.22 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, Pbca | Cell parameters from 24 reflections |
a = 6.4300 (13) Å | θ = 10–11° |
b = 13.709 (3) Å | µ = 0.14 mm−1 |
c = 17.134 (3) Å | T = 293 K |
V = 1510.4 (5) Å3 | Rectangular prism, yellow–orange |
Z = 4 | 0.4 × 0.2 × 0.2 mm |
F(000) = 768 |
Enraf-Nonius CAD-4 diffractometer | Rint = 0.0 |
Radiation source: fine-focus sealed tube | θmax = 25.0°, θmin = 2.4° |
Graphite monochromator | h = 0→7 |
θ/5/3θ scans | k = 0→16 |
1326 measured reflections | l = 0→20 |
1326 independent reflections | 2 standard reflections every 98 reflections |
1044 reflections with I > 2σ(I) | intensity decay: 3% |
Refinement on F2 | 0 restraints |
Least-squares matrix: full | Primary atom site location: structure-invariant direct methods |
R[F2 > 2σ(F2)] = 0.040 | Secondary atom site location: difference Fourier map |
wR(F2) = 0.111 | w = 1/[σ2(Fo2) + (0.063P)2 + 0.29P] where P = (Fo2 + 2Fc2)/3 |
S = 1.05 | (Δ/σ)max < 0.001 |
1326 reflections | Δρmax = 0.13 e Å−3 |
127 parameters | Δρmin = −0.19 e Å−3 |
C10N12O6 | V = 1510.4 (5) Å3 |
Mr = 384.22 | Z = 4 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 6.4300 (13) Å | µ = 0.14 mm−1 |
b = 13.709 (3) Å | T = 293 K |
c = 17.134 (3) Å | 0.4 × 0.2 × 0.2 mm |
Enraf-Nonius CAD-4 diffractometer | Rint = 0.0 |
1326 measured reflections | 2 standard reflections every 98 reflections |
1326 independent reflections | intensity decay: 3% |
1044 reflections with I > 2σ(I) |
R[F2 > 2σ(F2)] = 0.040 | 127 parameters |
wR(F2) = 0.111 | 0 restraints |
S = 1.05 | Δρmax = 0.13 e Å−3 |
1326 reflections | Δρmin = −0.19 e Å−3 |
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. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.6319 (3) | 0.72438 (16) | 0.46100 (12) | 0.0741 (6) | |
C2 | 0.5011 (3) | 0.75038 (16) | 0.42179 (11) | 0.0536 (5) | |
C3 | 0.3341 (3) | 0.78005 (14) | 0.37225 (10) | 0.0456 (5) | |
N4 | 0.3248 (3) | 0.86605 (13) | 0.34015 (10) | 0.0570 (5) | |
O5 | 0.1463 (2) | 0.86521 (11) | 0.29696 (9) | 0.0610 (4) | |
N6 | 0.0416 (3) | 0.77689 (13) | 0.30314 (9) | 0.0554 (5) | |
C7 | 0.1576 (3) | 0.72617 (14) | 0.34938 (10) | 0.0447 (5) | |
O8 | 0.1227 (2) | 0.63510 (10) | 0.37587 (8) | 0.0551 (4) | |
C9 | −0.0619 (3) | 0.58976 (14) | 0.36441 (10) | 0.0454 (5) | |
N10 | −0.1819 (3) | 0.60194 (14) | 0.30473 (9) | 0.0589 (5) | |
O11 | −0.3461 (3) | 0.53837 (13) | 0.31892 (10) | 0.0746 (5) | |
N12 | −0.3206 (3) | 0.48832 (14) | 0.38747 (11) | 0.0697 (6) | |
C13 | −0.1466 (3) | 0.51984 (14) | 0.41598 (11) | 0.0476 (5) | |
N14 | −0.0833 (3) | 0.48153 (11) | 0.48858 (9) | 0.0511 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0626 (12) | 0.0967 (16) | 0.0630 (12) | 0.0073 (11) | −0.0153 (10) | −0.0128 (11) |
C2 | 0.0505 (12) | 0.0669 (13) | 0.0435 (10) | 0.0002 (11) | 0.0003 (9) | −0.0097 (10) |
C3 | 0.0494 (11) | 0.0559 (11) | 0.0316 (9) | 0.0056 (8) | 0.0054 (8) | −0.0037 (8) |
N4 | 0.0608 (11) | 0.0609 (11) | 0.0492 (10) | 0.0024 (9) | 0.0038 (8) | −0.0041 (8) |
O5 | 0.0706 (10) | 0.0554 (9) | 0.0570 (9) | 0.0074 (7) | −0.0043 (7) | 0.0094 (7) |
N6 | 0.0614 (11) | 0.0566 (10) | 0.0482 (9) | 0.0034 (9) | −0.0059 (8) | 0.0086 (8) |
C7 | 0.0494 (11) | 0.0539 (11) | 0.0308 (8) | 0.0071 (9) | 0.0012 (8) | 0.0021 (8) |
O8 | 0.0503 (8) | 0.0627 (9) | 0.0522 (8) | −0.0009 (6) | −0.0108 (6) | 0.0178 (7) |
C9 | 0.0513 (11) | 0.0488 (10) | 0.0362 (9) | 0.0076 (9) | −0.0071 (8) | −0.0027 (8) |
N10 | 0.0665 (11) | 0.0668 (11) | 0.0433 (9) | 0.0030 (9) | −0.0157 (8) | 0.0028 (8) |
O11 | 0.0815 (11) | 0.0807 (11) | 0.0617 (10) | −0.0154 (9) | −0.0372 (8) | 0.0092 (8) |
N12 | 0.0772 (13) | 0.0714 (13) | 0.0603 (11) | −0.0156 (10) | −0.0296 (10) | 0.0107 (10) |
C13 | 0.0565 (12) | 0.0447 (10) | 0.0416 (10) | −0.0009 (9) | −0.0118 (9) | −0.0011 (8) |
N14 | 0.0609 (10) | 0.0487 (9) | 0.0437 (9) | −0.0048 (8) | −0.0141 (8) | 0.0051 (7) |
N1—C2 | 1.134 (3) | O8—C9 | 1.354 (2) |
C2—C3 | 1.428 (3) | C9—N10 | 1.292 (2) |
C3—N4 | 1.302 (2) | C9—C13 | 1.413 (3) |
C3—C7 | 1.410 (3) | N10—O11 | 1.390 (2) |
N4—O5 | 1.366 (2) | O11—N12 | 1.370 (2) |
O5—N6 | 1.389 (2) | N12—C13 | 1.295 (3) |
N6—C7 | 1.291 (2) | C13—N14 | 1.410 (2) |
C7—O8 | 1.347 (2) | N14—N14i | 1.247 (3) |
N1—C2—C3 | 178.2 (2) | N10—C9—O8 | 125.38 (18) |
N4—C3—C7 | 108.66 (17) | N10—C9—C13 | 110.63 (18) |
N4—C3—C2 | 122.91 (19) | O8—C9—C13 | 123.97 (16) |
C7—C3—C2 | 128.43 (19) | C9—N10—O11 | 103.55 (16) |
C3—N4—O5 | 105.06 (17) | N12—O11—N10 | 111.90 (14) |
N4—O5—N6 | 111.91 (15) | C13—N12—O11 | 105.03 (17) |
C7—N6—O5 | 103.68 (16) | N12—C13—N14 | 117.24 (18) |
N6—C7—O8 | 127.57 (18) | N12—C13—C9 | 108.89 (17) |
N6—C7—C3 | 110.69 (18) | N14—C13—C9 | 133.86 (18) |
O8—C7—C3 | 121.73 (16) | N14i—N14—C13 | 111.9 (2) |
C7—O8—C9 | 121.51 (15) | ||
C7—C3—N4—O5 | −0.85 (19) | C7—O8—C9—C13 | −149.88 (19) |
C2—C3—N4—O5 | 179.07 (16) | O8—C9—N10—O11 | 178.38 (18) |
C3—N4—O5—N6 | 0.6 (2) | C13—C9—N10—O11 | 0.0 (2) |
N4—O5—N6—C7 | −0.1 (2) | C9—N10—O11—N12 | −0.3 (2) |
O5—N6—C7—O8 | 178.26 (17) | N10—O11—N12—C13 | 0.5 (2) |
O5—N6—C7—C3 | −0.4 (2) | O11—N12—C13—N14 | 178.62 (18) |
N4—C3—C7—N6 | 0.8 (2) | O11—N12—C13—C9 | −0.4 (2) |
C2—C3—C7—N6 | −179.07 (18) | N10—C9—C13—N12 | 0.3 (2) |
N4—C3—C7—O8 | −177.92 (16) | O8—C9—C13—N12 | −178.12 (18) |
C2—C3—C7—O8 | 2.2 (3) | N10—C9—C13—N14 | −178.6 (2) |
N6—C7—O8—C9 | −9.6 (3) | O8—C9—C13—N14 | 3.1 (3) |
C3—C7—O8—C9 | 168.95 (16) | N12—C13—N14—N14i | −178.4 (2) |
C7—O8—C9—N10 | 32.0 (3) | C9—C13—N14—N14i | 0.3 (4) |
Symmetry code: (i) −x, −y+1, −z+1. |
Experimental details
(IV) | (V) | (VI) | (VII) | |
Crystal data | ||||
Chemical formula | C6N6O3 | C5N6O5 | C8N8O5 | C10N12O6 |
Mr | 204.12 | 224.11 | 288.16 | 384.22 |
Crystal system, space group | Monoclinic, P21/c | Orthorhombic, P212121 | Orthorhombic, P212121 | Orthorhombic, Pbca |
Temperature (K) | 293 | 293 | 293 | 293 |
a, b, c (Å) | 13.639 (3), 8.899 (2), 6.9254 (17) | 7.853 (2), 8.791 (2), 12.229 (3) | 7.8295 (15), 8.6273 (18), 17.409 (3) | 6.4300 (13), 13.709 (3), 17.134 (3) |
α, β, γ (°) | 90, 97.13 (2), 90 | 90, 90, 90 | 90, 90, 90 | 90, 90, 90 |
V (Å3) | 834.1 (4) | 844.2 (4) | 1175.9 (4) | 1510.4 (5) |
Z | 4 | 4 | 4 | 4 |
Radiation type | Mo Kα | Mo Kα | Mo Kα | Mo Kα |
µ (mm−1) | 0.14 | 0.16 | 0.14 | 0.14 |
Crystal size (mm) | 0.5 × 0.4 × 0.4 | 0.6 × 0.5 × 0.4 | 0.4 × 0.3 × 0.3 | 0.4 × 0.2 × 0.2 |
Data collection | ||||
Diffractometer | Siemens P3/PC | Siemens P3/PC | Siemens P3/PC | Enraf-Nonius CAD-4 |
Absorption correction | – | – | – | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 1534, 1471, 1276 | 1433, 1433, 1164 | 1469, 1469, 1267 | 1326, 1326, 1044 |
Rint | 0.008 | 0.0 | 0.0 | 0.0 |
(sin θ/λ)max (Å−1) | 0.596 | 0.705 | 0.641 | 0.595 |
Refinement | ||||
R[F2 > 2σ(F2)], wR(F2), S | 0.034, 0.101, 1.09 | 0.045, 0.121, 1.02 | 0.045, 0.128, 1.05 | 0.040, 0.111, 1.05 |
No. of reflections | 1471 | 1433 | 1469 | 1326 |
No. of parameters | 136 | 145 | 191 | 127 |
Δρmax, Δρmin (e Å−3) | 0.13, −0.19 | 0.27, −0.23 | 0.16, −0.18 | 0.13, −0.19 |
Absolute structure | ? | Flack H D (1983), Acta Cryst. A39, 876-881 | Flack H D (1983), Acta Cryst. A39, 876-881 | ? |
Absolute structure parameter | ? | not reliably determined | not reliably determined | ? |
Computer programs: P3/PC (Siemens, 1989), CAD-4 Software (Enraf-Nonius, 1989), P3/PC, CAD-4 Software, XCAD4 (Harms, 1996), SHELXTL (Sheldrick, 1998), SHELXTL.
Ia | Ib | II | III | IV | V | VI | VII | CSD | |
C3—C7 | 1.464 (6) | 1.406 (6) | 1.397 | 1.411 (6) | 1.411 (2) | 1.422 (3) | 1.408 (4) | 1.410 (3) | 1.428 (7) |
C9—C13 | 1.393 (6) | 1.444 (5) | 1.403 | 1.408 (6) | 1.414 (2) | 1.408 (3) | 1.406 (4) | 1.413 (3) | 1.428 (7) |
C3—N4 | 1.266 (8) | 1.289 (6) | 1.304 | 1.289 (5) | 1.297 (2) | 1.293 (3) | 1.295 (4) | 1.302 (2) | 1.298 (6) |
C13—N12 | 1.242 (5) | 1.309 (7) | 1.281 | 1.295 (6) | 1.295 (2) | 1.289 (3) | 1.286 (4) | 1.295 (3) | 1.298 (6) |
C7—N6 | 1.302 (8) | 1.270 (6) | 1.293 | 1.287 (6) | 1.293 (2) | 1.283 (2) | 1.295 (4) | 1.291 (2) | 1.298 (6) |
C9—N10 | 1.254 (5) | 1.313 (7) | 1.290 | 1.287 (5) | 1.291 (2) | 1.284 (3) | 1.297 (3) | 1.292 (2) | 1.298 (6) |
N4—O5 | 1.355 (9) | 1.317 (7) | 1.375 | 1.375 (5) | 1.370 (2) | 1.370 (3) | 1.364 (4) | 1.366 (2) | 1.385 (13) |
N12—O11 | 1.409 (8) | 1.312 (8) | 1.372 | 1.373 (5) | 1.360 (2) | 1.360 (3) | 1.358 (4) | 1.370 (2) | 1.385 (13) |
N6—O5 | 1.340 (8) | 1.409 (6) | 1.390 | 1.386 (5) | 1.386 (2) | 1.385 (3) | 1.389 (4) | 1.389 (2) | 1.385 (13) |
N10—O11 | 1.404 (7) | 1.379 (8) | 1.390 | 1.386 (6) | 1.389 (2) | 1.387 (3) | 1.379 (4) | 1.390 (2) | 1.385 (13) |
C7—O8 | 1.344 (8) | 1.348 (5) | 1.348 | 1.358 (6) | 1.349 (2) | 1.349 (3) | 1.347 (3) | 1.347 (2) | 1.354 (16) |
O8—C9 | 1.385 (6) | 1.324 (5) | 1.347 | 1.358 (5) | 1.352 (2) | 1.355 (2) | 1.336 (3)a | 1.354 (2) | 1.354 (16) |
Note: (a) For structure (VI) the value O8'—C9 is given. |
N6—C7—O8—C9 | N10—C9—O8—C7 | τa | Symmetry | |
Ia | 15.9 | 49.1 | 53 | C2 |
Ib | 14.4 | 20.1 | 29 | C2 |
II | -13.2 | 12.1 | 11 | Cs |
III | 10.8 | 42.0 | 48 | C2 |
IV | -28.6 (2) | 20.3 (2) | 24.3 (1) | Cs |
V | 17.3 (3) | 8.6 (3) | 22.5 (1) | C2 |
VIb | 20.2 (4) | 4.7 (4) | 24.0 (2) | C2 |
VIc | 13.6 (4) | 10.4 (4) | 20.9 (2) | C2 |
VII | -9.6 (3) | 32.0 (3) | 27.8 (1) | Cs |
Notes: (a) /t is the dihedral angle between the furazan rings; (b) torsion angles N6—C7—O8—C16 and N17—C16—O8—C7 are given; (c) torsion angles N19—C20—O8'—C9 and N10—C9—O8'—C20 are given. |
dmol | dX-ray | k | |
I | 2.605 | 1.898 | 0.728 |
II | 2.617 | 1.845 | 0.704 |
III | 2.519 | 1.888 | 0.749 |
IV | 2.302 | 1.626 | 0.706 |
V | 2.459 | 1.763 | 0.717 |
VI | 2.386 | 1.628 | 0.682 |
VII | 2.401 | 1.690 | 0.704 |
Symmetrical difurazanyl ether derivatives, such as bis(3-nitrofurazan-4-yl) ether, (I) (Sheremetev et al., 1996; Sheremetev et al., 1998?), bis[3-(nitro-N,N,O-azoxy)furazan-4-yl] ether, (II) (Sheremetev, Semenov et al., 1998), and bis[3-(5H-[1,2,3]triazolo[4,5-c]furazan-5-yl)furazan-4-yl] ether, (III) (Sheremetev et al., 1999), have been developed as highly energetic materials having good explosive performance in a variety of industrial, military, and space applications. The impact and friction sensitivities of these compounds are similar to those of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). In addition to continuing efforts in the preparation of highly energetic materials, recent research in our group has focused on hydrogen-free propellant ingredients. Our approach to the synthesis of energetic compounds is to employ the inherent stability and flexibility of the difurazanyl ether skeleton, and to enhance the enthalpy of formation by the inclusion of cyano groups. We have prepared a large number of known and new cyano derivatives of furazan and studied their properties (Sheremetev et al., 1995; Sheremetev et al., 1998?; Sheremetev et al., 2000?; Sinditskii et al., 1998). The different functional groups were chosen in order to modify the physical properties of the target ethers (e.g. melting point, oxygen balance, plasticity and solubility) and to probe the effects of the substituents on the overall lattice architecture and crystal density. 3-Cyanofurazanyl 3-nitrofurazanyl ether, (IV) (Sheremetev, Aleksandrova et al., 2000; Sheremetev et al., 2002), and bis(3-cyanofurazonyl) ether, (V) (Sheremetev et al., 1996), incorporating two furazan rings, and 3,4-bis(3-cyanofurazan-4-yloxy)furazan, (VI) (Sheremetev, Kulagina et al., 1998), having three rings were prepared as previously described. We report here their structures, along with that of the new compound bis[3-(3-cyanofurazan-4-yloxy)furazan-4-yl]diazene, (VII).
We have explored the influence on the difurazanyl ether fragment of different functional groups, such as nitro [R = NO2, (IV)], less electron-withdrawing substitutents [R = –N═N–furazan, (VII), and R = CN, (V)] and an electron-donating moiety [R = O-furazan, (VI)]. The bond lengths of the difurazanyl ether fragments in molecules (II)–(V) and (VII) are very similar and close to the average values published for each type of bond (Allen et al., 1987; Table 1). There are two topologically equivalent N—O bonds in each furazan ring. According to experimental data these N—O bonds have different lengths in (II)–(V) and (VII); those adjacent to an electron-withdrawing substituent are in the range 1.360 (2)–1.375 (5) Å (mean 1.369 Å), while the N–O bonds adjacent to the electron-donating oxygen bridge are in the range 1.385 (3)–1.390 (2) Å (mean 1.388 Å) (see Table 1). This is in agreement with a report by Batsanov et al. (1985), where the shortening of furazan N—O bonds adjacent to electron-withdrawing substituents, relative to those adjacent to electron-releasing substituents, was first pointed out. Molecule (VI) is similar to molecule (IV), but contains additional furazan rings between the two terminal cyano-bearing furazan rings. It was found that these terminal rings in molecule (VI) have the same geometry as in molecules (II)–(V) and (VII), while its symmetrically substituted central furazan ring has very similar N—O bond lengths of 1.387 (4) and 1.389 (4) Å.
The bond lengths in the two independent molecules of (I) differ significantly from those in molecules (II)–(VII). However, as there are also large discrepancies of up to 0.06–0.07 Å in the lengths of chemically equivalent bonds in the two independent molecules of (I), we cannot consider the structure of (I) to be reliable at a level sufficient to allow discussion of its bond lengths. For structures (II)–(VII), the ether C—O bond distances are in the range 1.336 (3)–1.358 (4) Å (mean 1.350 Å), intermediate between single C–O (1.42 Å) and double C═O (1.21 Å) bonds, indicating resonance between the furazan π-system and the lone pairs of bridging atom O8. This is also confirmed by the increase in the bond angle at O8 to an average value of 121°. The bond lengths of the cyano groups in (IV)–(VII) are in the range 1.116 (5)–1.134 (3) Å (mean 1.127 Å). Due to conjugation between the furazan rings and the cyano groups, the cyano NC—C(furazan) bonds are shortened and have bond lengths in the range 1.428 (3)–1.4359 (19) Å (mean 1.432 Å). In (V), the dihedral angle between the furazan ring and the plane of the nitro group is 18.1°, and the length of the N(nitro)—C(furazan) bond is 1.452 (3) Å. Analysis of data from the Cambridge Structural Database (Allen, 2002) shows that the latter value is close to the standard value of 1.46 Å for a Csp2—NO2 bond length. In (VII), the azo group conjugates neighbouring furazan rings, as evidenced by the N═N bond length of 1.247 (3) Å and the N(azo)—C(furazan) bond length of 1.410 (3) Å.
Molecules (I)–(III) and (V)–(VII) are non-planar. In contrast, (IV) can be considered as approximaetely planar as the r.m.s. deviation from the molecular least-squares mean plane is only 0.18 Å. The only difference between the difurazanyl ether fragments in all seven structures is the twist between the two component rings. The conformation of the difurazanyl ether fragment can be described by the torsion angles N6—C7—O8—C9 and N10—C9—O8—C7 (Table 2). If these torsion angles have the same sign, the approximate symmetry of the difurazanyl ether is C2 (Fig. 2a), but with opposing signs it is Cs (Fig. 2 b). It is clear from Table 2 and Figs. 2(a) and 2(b) that the dihedral angle between the furazan rings does not uniquely describe the conformation of the difurazanyl ether fragment. Structures (I), (III), (V) and (VI) have a C2 conformation for the difurazanyl ether fragment, while structures (II), (IV), and (VII) adopt Cs conformations.
To determine the optimal conformation of the difurazanyl ether fragment we optimized the geometry of (IV) using the GAUSSIAN94 program (Frisch et al., 1994) at the MP2/cc-pvdz level of theory. This showed that the conformations of the calculated and experimental molecules are different. The calculated N6—C7—O8—C9 and N10—C9—O8—C7 torsion angles have the same sign and value (7.1°)·Hence, in contrast to experimental molecule (IV), which has approximate Cs symmetry, the calculated molecule has C2 symmetry. The observed dihedral angle between the furazan rings is 24.3 (1)°, whereas the calculated value is 11.8°. To compare the energies of these two conformations, we carried out another calculation with the torsion angles fixed at the experimentally observed values of -28.0 and 20.3°, respectively. This calculation revealed that the energy difference between the two conformations is rather small (1.313 kJ mol-1), so the difference between experimentally determined and calculated conformations could be due to crystal-packing effects which were not included in the calculations.
In the crystal packing of (IV), essentially planar molecules are arranged to form flat ribbons normal to the (201) crystallographic plane, with the ribbons adopting a parquet motif. The packing arrangements for (V), (VI) and (VII) do not assume a readily identifiable motif, a common sitituation with space groups P212121 and Pbca. In (V) and (VI), two intermolecular contacts involving cyano groups were found; in (V), the cyano group approaches O15 from the nitro group [C2···O15(0.5 - x, 1 - y, z - 0.5) = 2.957 (3) Å], while in (VI), there is a contact between the cyano group and a furazan ring [N21···C15(0.5 + x, -0.5 - y, -z) = 2.969 (3) Å]. These interactions can be ascribed to the coulombic interactions of atoms bearing partial opposite charges. No other intermolecular contacts in (IV)–(VII) lie within the sum of the relevant van der Waals radii (Bondi, 1964).
It is well known that high density is a factor favouring good explosive performance. Although we do not have enough data for a representative statistical analysis, we decided to investigate the relationship between the molecular structure and density of crystal packing for the seven difurazanyl ethers (I)-(VII). For this purpose, molecular volume (V) or molecular surface (S), and molecular mass (M) were used. All calculations were carried out using the NONVPOT program (Shil'nikov, 1994) and the radii of Bondi (1964). Comparison of the calculated ratio M/S with X-ray density, dX-ray, shows a moderate dependence of M/S on dX-ray, with a correlation coefficient of 0.884. Better agreement was found by considering `molecular density', dmol, which is the ratio of molecular mass M to molecular volume V. Fig. 3 shows the dependence of crystal density on molecular density, the correlation coefficient in this case being 0.916. This figure also shows that while the crystal density of (III) is higher than expected, the values for (II) and (V) are lower. According to Kitaigorodsky (1973), crystal density can be presented as a product of packing coefficient k and molecular density, dX-ray = k × dmol. Calculated packing coefficients, molecular densities and crystal densities for compounds (I)–(VII) are presented in Table 3. Since the packing coefficient influences crystal density, the search for crystals with high density should consider ways of increasing both dmol and k. According to Kuzmina et al. (1990), there is a tendency for k to decrease with increasing dmol. This relationship restricts the possibilities of obtaining extremely dense structures, but because of its statistical nature exceptions do occur. Compound (III), which has a rather large value of dmol, is a good example of such an exception; while the mean k value for (I)–(VII) is 0.71, for (III) it is higher, at 0.749. Analysis of the factors responsible for the high packing coefficients for this and other compounds will help us to predict compounds likely to exhibit high density.