Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107020112/ga3049sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270107020112/ga3049IVsup2.hkl |
CCDC reference: 652519
To a partially dissolved mixture of 3,5-bis(hydroxymethyl)-N4-(pyrrol-1-yl)-1,2,4-triazole (2.00 g, 10.3 mmol) in dry 1,4-dioxane (1200 ml, freshly distilled from sodium metal) was added manganese dioxide (10.80 g, from Aldrich). The resulting brown coloured suspension was refluxed for 4 h, then filtered through a pad of Celite on a glass sinter. The filtrate was collected and evaporated to dryness in vacuo, yielding 1.40 g (7.35 mmol, 71%) of an off-white coloured crystalline solid. Single crystals were grown by slow evaporation of an acetone solution of the solid. M.p. 408 K. For other details see supplementary data.
The coordinates and Uiso(H) values for the H atoms were freely refined [C—H = 0.923 (16)–0.978 (15) Å].
Data collection: SMART (Bruker, 2004); cell refinement: SMART and SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2004); software used to prepare material for publication: enCIFer (Version 1.2; Allen et al., 2004).
C6H6N4 | F(000) = 840 |
Mr = 134.15 | Dx = 1.381 Mg m−3 |
Monoclinic, C2/c | Melting point: 408 K |
Hall symbol: -C 2yc | Mo Kα radiation, λ = 0.71073 Å |
a = 22.9326 (11) Å | Cell parameters from 5988 reflections |
b = 12.1235 (6) Å | θ = 2.9–26.4° |
c = 7.0111 (3) Å | µ = 0.09 mm−1 |
β = 96.707 (2)° | T = 93 K |
V = 1935.91 (16) Å3 | Block, colourless |
Z = 12 | 0.5 × 0.3 × 0.1 mm |
Bruker Kappa APEX II area-detector diffractometer | 1997 independent reflections |
Radiation source: fine-focus sealed tube | 1834 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.040 |
ϕ amd ω scans | θmax = 26.5°, θmin = 1.9° |
Absorption correction: multi-scan (SCALE; Bruker, 2004) | h = −28→28 |
Tmin = 0.834, Tmax = 1.000 | k = −15→15 |
20165 measured reflections | l = −8→8 |
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)] = 0.036 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.089 | All H-atom parameters refined |
S = 1.10 | w = 1/[σ2(Fo2) + (0.0314P)2 + 1.7122P] where P = (Fo2 + 2Fc2)/3 |
1997 reflections | (Δ/σ)max < 0.001 |
173 parameters | Δρmax = 0.18 e Å−3 |
0 restraints | Δρmin = −0.25 e Å−3 |
C6H6N4 | V = 1935.91 (16) Å3 |
Mr = 134.15 | Z = 12 |
Monoclinic, C2/c | Mo Kα radiation |
a = 22.9326 (11) Å | µ = 0.09 mm−1 |
b = 12.1235 (6) Å | T = 93 K |
c = 7.0111 (3) Å | 0.5 × 0.3 × 0.1 mm |
β = 96.707 (2)° |
Bruker Kappa APEX II area-detector diffractometer | 1997 independent reflections |
Absorption correction: multi-scan (SCALE; Bruker, 2004) | 1834 reflections with I > 2σ(I) |
Tmin = 0.834, Tmax = 1.000 | Rint = 0.040 |
20165 measured reflections |
R[F2 > 2σ(F2)] = 0.036 | 0 restraints |
wR(F2) = 0.089 | All H-atom parameters refined |
S = 1.10 | Δρmax = 0.18 e Å−3 |
1997 reflections | Δρmin = −0.25 e Å−3 |
173 parameters |
Experimental. 1H NMR (500 MHz, CDCl3): 8.44 (2H, s, TrH), 6.88 (2H, t, 3J = 2 Hz, PyrH) and 6.33 (2H, t, 3J = 2 Hz, PyrH) p.p.m.. 13C NMR (125 MHz, CDCl3): 142.4 (Tr), 121.4 (Pyr) and 109.7 (Pyr) p.p.m.. A sample was sublimed by warming to 50°C at <1 m mH g. Microanalysis: C, 53.72; H, 4.56; N, 41.72%. Calc'd for C6H6N4: C, 53.72; H, 4.51; N, 41.77%. |
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. There are no solvent molecules present and there is no disorder. All non-hydrogen atoms were refined anisotropically. The coordinates and U(iso) values for the hydrogen atoms were freely refined. |
x | y | z | Uiso*/Ueq | ||
N1 | 0.17185 (5) | 0.42851 (9) | 0.02172 (16) | 0.0267 (3) | |
N2 | 0.17322 (5) | 0.34209 (9) | −0.11132 (15) | 0.0262 (3) | |
C3 | 0.17229 (5) | 0.25021 (11) | −0.01590 (17) | 0.0225 (3) | |
H3 | 0.1727 (6) | 0.1748 (12) | −0.065 (2) | 0.025 (4)* | |
N4 | 0.17107 (4) | 0.27229 (8) | 0.17455 (13) | 0.0191 (2) | |
C5 | 0.17085 (5) | 0.38400 (10) | 0.19046 (18) | 0.0227 (3) | |
H5 | 0.1690 (6) | 0.4220 (12) | 0.307 (2) | 0.029 (4)* | |
N11 | 0.16928 (4) | 0.19687 (8) | 0.32121 (14) | 0.0197 (2) | |
C12 | 0.12008 (6) | 0.17326 (11) | 0.40916 (18) | 0.0261 (3) | |
H12 | 0.0856 (7) | 0.2117 (13) | 0.376 (2) | 0.035 (4)* | |
C13 | 0.13635 (6) | 0.09477 (12) | 0.54369 (18) | 0.0286 (3) | |
H13 | 0.1108 (7) | 0.0638 (13) | 0.628 (2) | 0.035 (4)* | |
C14 | 0.19646 (6) | 0.07027 (11) | 0.53655 (18) | 0.0253 (3) | |
H14 | 0.2202 (7) | 0.0188 (13) | 0.614 (2) | 0.036 (4)* | |
C15 | 0.21639 (5) | 0.13478 (10) | 0.39869 (16) | 0.0203 (3) | |
H15 | 0.2537 (6) | 0.1425 (12) | 0.352 (2) | 0.025 (4)* | |
N22 | 0.02906 (5) | 0.57318 (9) | 0.72689 (16) | 0.0295 (3) | |
C23 | 0.04474 (6) | 0.47055 (11) | 0.71337 (17) | 0.0250 (3) | |
H23 | 0.0815 (7) | 0.4429 (12) | 0.682 (2) | 0.029 (4)* | |
N24 | 0.0000 | 0.40305 (12) | 0.7500 | 0.0223 (3) | |
N31 | 0.0000 | 0.28962 (13) | 0.7500 | 0.0267 (3) | |
C32 | 0.02309 (6) | 0.22582 (13) | 0.9026 (2) | 0.0357 (3) | |
H32 | 0.0387 (8) | 0.2610 (15) | 1.014 (3) | 0.044 (5)* | |
C33 | 0.01472 (7) | 0.11950 (14) | 0.8446 (3) | 0.0519 (5) | |
H33 | 0.0266 (9) | 0.0574 (17) | 0.920 (3) | 0.062 (6)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0269 (6) | 0.0245 (5) | 0.0273 (6) | −0.0010 (4) | −0.0018 (4) | 0.0033 (4) |
N2 | 0.0267 (6) | 0.0298 (6) | 0.0219 (5) | 0.0001 (4) | 0.0016 (4) | 0.0032 (4) |
C3 | 0.0232 (6) | 0.0260 (6) | 0.0183 (6) | 0.0004 (5) | 0.0021 (4) | −0.0008 (5) |
N4 | 0.0204 (5) | 0.0202 (5) | 0.0163 (5) | 0.0008 (4) | 0.0004 (4) | 0.0013 (4) |
C5 | 0.0222 (6) | 0.0214 (6) | 0.0236 (6) | 0.0018 (5) | −0.0019 (5) | −0.0005 (5) |
N11 | 0.0206 (5) | 0.0217 (5) | 0.0166 (5) | 0.0000 (4) | 0.0018 (4) | 0.0022 (4) |
C12 | 0.0215 (6) | 0.0343 (7) | 0.0230 (6) | −0.0023 (5) | 0.0049 (5) | −0.0022 (5) |
C13 | 0.0318 (7) | 0.0354 (7) | 0.0192 (6) | −0.0098 (6) | 0.0055 (5) | 0.0001 (5) |
C14 | 0.0321 (7) | 0.0231 (6) | 0.0196 (6) | −0.0031 (5) | −0.0017 (5) | 0.0016 (5) |
C15 | 0.0217 (6) | 0.0198 (6) | 0.0186 (5) | 0.0008 (5) | −0.0006 (4) | −0.0012 (4) |
N22 | 0.0304 (6) | 0.0291 (6) | 0.0273 (6) | −0.0028 (5) | −0.0037 (4) | 0.0004 (4) |
C23 | 0.0232 (6) | 0.0297 (7) | 0.0209 (6) | −0.0026 (5) | −0.0029 (5) | 0.0008 (5) |
N24 | 0.0225 (7) | 0.0231 (7) | 0.0205 (7) | 0.000 | −0.0018 (5) | 0.000 |
N31 | 0.0242 (8) | 0.0228 (8) | 0.0330 (8) | 0.000 | 0.0030 (6) | 0.000 |
C32 | 0.0266 (7) | 0.0342 (8) | 0.0482 (9) | 0.0065 (6) | 0.0122 (6) | 0.0160 (7) |
C33 | 0.0402 (9) | 0.0301 (8) | 0.0918 (14) | 0.0082 (7) | 0.0346 (9) | 0.0177 (8) |
N1—C5 | 1.3030 (16) | C14—H14 | 0.954 (17) |
N1—N2 | 1.4056 (15) | C15—H15 | 0.955 (15) |
N2—C3 | 1.3008 (16) | N22—C23 | 1.3017 (17) |
C3—N4 | 1.3653 (15) | N22—N22i | 1.408 (2) |
C3—H3 | 0.978 (15) | C23—N24 | 1.3601 (15) |
N4—C5 | 1.3589 (16) | C23—H23 | 0.956 (15) |
N4—N11 | 1.3802 (13) | N24—C23i | 1.3601 (15) |
C5—H5 | 0.942 (16) | N24—N31 | 1.375 (2) |
N11—C15 | 1.3755 (15) | N31—C32i | 1.3753 (17) |
N11—C12 | 1.3776 (15) | N31—C32 | 1.3753 (17) |
C12—C13 | 1.3610 (19) | C32—C33 | 1.358 (2) |
C12—H12 | 0.923 (16) | C32—H32 | 0.926 (18) |
C13—C14 | 1.4168 (19) | C33—C33i | 1.417 (4) |
C13—H13 | 0.959 (16) | C33—H33 | 0.94 (2) |
C14—C15 | 1.3631 (17) | ||
C5—N1—N2 | 107.34 (10) | C15—C14—H14 | 124.1 (10) |
C3—N2—N1 | 107.10 (10) | C13—C14—H14 | 127.7 (10) |
N2—C3—N4 | 109.79 (11) | C14—C15—N11 | 106.32 (11) |
N2—C3—H3 | 128.2 (9) | C14—C15—H15 | 133.4 (9) |
N4—C3—H3 | 122.0 (9) | N11—C15—H15 | 120.3 (9) |
C5—N4—C3 | 106.05 (10) | C23—N22—N22i | 107.08 (7) |
C5—N4—N11 | 126.75 (10) | N22—C23—N24 | 109.90 (12) |
C3—N4—N11 | 127.20 (10) | N22—C23—H23 | 127.6 (9) |
N1—C5—N4 | 109.73 (11) | N24—C23—H23 | 122.5 (9) |
N1—C5—H5 | 126.2 (9) | C23—N24—C23i | 106.03 (15) |
N4—C5—H5 | 124.1 (9) | C23—N24—N31 | 126.99 (8) |
C15—N11—C12 | 110.87 (10) | C23i—N24—N31 | 126.99 (8) |
C15—N11—N4 | 124.50 (10) | N24—N31—C32i | 124.22 (9) |
C12—N11—N4 | 124.63 (10) | N24—N31—C32 | 124.22 (9) |
C13—C12—N11 | 106.43 (11) | C32i—N31—C32 | 111.56 (18) |
C13—C12—H12 | 133.0 (10) | C33—C32—N31 | 105.82 (16) |
N11—C12—H12 | 120.4 (10) | C33—C32—H32 | 135.8 (11) |
C12—C13—C14 | 108.13 (11) | N31—C32—H32 | 118.3 (11) |
C12—C13—H13 | 124.4 (10) | C32—C33—C33i | 108.40 (11) |
C14—C13—H13 | 127.4 (10) | C32—C33—H33 | 124.5 (13) |
C15—C14—C13 | 108.24 (11) | C33i—C33—H33 | 127.1 (13) |
C5—N1—N2—C3 | 0.71 (13) | C12—C13—C14—C15 | 0.49 (15) |
N1—N2—C3—N4 | −0.71 (13) | C13—C14—C15—N11 | −0.61 (14) |
N2—C3—N4—C5 | 0.46 (13) | C12—N11—C15—C14 | 0.53 (14) |
N2—C3—N4—N11 | 179.33 (10) | N4—N11—C15—C14 | −179.21 (10) |
N2—N1—C5—N4 | −0.43 (13) | N22i—N22—C23—N24 | −0.52 (15) |
C3—N4—C5—N1 | 0.01 (13) | N22—C23—N24—C23i | 0.21 (6) |
N11—N4—C5—N1 | −178.87 (10) | N22—C23—N24—N31 | −179.79 (6) |
C5—N4—N11—C15 | −106.22 (14) | C23—N24—N31—C32i | −97.27 (9) |
C3—N4—N11—C15 | 75.14 (16) | C23i—N24—N31—C32i | 82.73 (9) |
C5—N4—N11—C12 | 74.08 (16) | C23—N24—N31—C32 | 82.73 (9) |
C3—N4—N11—C12 | −104.57 (14) | C23i—N24—N31—C32 | −97.27 (9) |
C15—N11—C12—C13 | −0.23 (14) | N24—N31—C32—C33 | −179.63 (8) |
N4—N11—C12—C13 | 179.51 (11) | C32i—N31—C32—C33 | 0.37 (8) |
N11—C12—C13—C14 | −0.16 (14) | N31—C32—C33—C33i | −0.9 (2) |
Symmetry code: (i) −x, y, −z+3/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5···N1ii | 0.942 (16) | 2.353 (16) | 3.2479 (16) | 158.6 (12) |
C15—H15···N2iii | 0.955 (15) | 2.521 (15) | 3.4261 (16) | 158.3 (11) |
C32—H32···N22ii | 0.926 (18) | 2.528 (18) | 3.325 (2) | 144.3 (14) |
Symmetry codes: (ii) x, −y+1, z+1/2; (iii) −x+1/2, −y+1/2, −z. |
Experimental details
Crystal data | |
Chemical formula | C6H6N4 |
Mr | 134.15 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 93 |
a, b, c (Å) | 22.9326 (11), 12.1235 (6), 7.0111 (3) |
β (°) | 96.707 (2) |
V (Å3) | 1935.91 (16) |
Z | 12 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.5 × 0.3 × 0.1 |
Data collection | |
Diffractometer | Bruker Kappa APEX II area-detector diffractometer |
Absorption correction | Multi-scan (SCALE; Bruker, 2004) |
Tmin, Tmax | 0.834, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 20165, 1997, 1834 |
Rint | 0.040 |
(sin θ/λ)max (Å−1) | 0.627 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.036, 0.089, 1.10 |
No. of reflections | 1997 |
No. of parameters | 173 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.18, −0.25 |
Computer programs: SMART (Bruker, 2004), SMART and SAINT (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 2004), enCIFer (Version 1.2; Allen et al., 2004).
N1—N2 | 1.4056 (15) | N22—N22i | 1.408 (2) |
N4—N11 | 1.3802 (13) | N24—N31 | 1.375 (2) |
C3—N4—N11—C15 | 75.14 (16) | C23—N24—N31—C32 | 82.73 (9) |
C5—N4—N11—C12 | 74.08 (16) |
Symmetry code: (i) −x, y, −z+3/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
C5—H5···N1ii | 0.942 (16) | 2.353 (16) | 3.2479 (16) | 158.6 (12) |
C15—H15···N2iii | 0.955 (15) | 2.521 (15) | 3.4261 (16) | 158.3 (11) |
C32—H32···N22ii | 0.926 (18) | 2.528 (18) | 3.325 (2) | 144.3 (14) |
Symmetry codes: (ii) x, −y+1, z+1/2; (iii) −x+1/2, −y+1/2, −z. |
1,2,4-Triazole derivatives are a class of organic heterocyclic molecules which are of interest for two main reasons. Firstly, they often show biological, such as antifungal, activity (Sweetman & Martindale, 2005); secondly their iron(II) complexes often exhibit spin crossover behaviour (Klingele, Moubaraki, Cashion, Murray & Brooker, 2005; Haasnoot, 2000; Kahn, 1999). Our interest lies in the latter area and we have been actively developing synthetic routes to carefully designed triazole ligands (Beckmann et al., 2003; Depree et al., 2003; Klingele & Brooker, 2004; Klingele, Moubaraki, Murray & Brooker, 2005; Brandt et al., 2007) for the purpose of accessing novel spin crossover materials (Klingele, Moubaraki, Cashion, Murray & Brooker, 2005). As part of this study, we decided to attempt to oxidize the dialcohol (I) we had prepared earlier (Klingele, Moubaraki, Murray & Brooker, 2005) to the dialdehyde (II) using manganese dioxide (see scheme). As the dialcohol is not very soluble, the reaction was carried out in refluxing 1,4-dioxane, rather than at room temperature. Instead of the dialdehyde (II), compound (IV) as presented here was obtained in high yield.
Compound (IV) has been deliberately prepared previously as part of a study of heterocyclic cations and anions (Katritzky & Suwinski, 1974), as a precursor for the preparation of N-cyanamidoimines (Olofson & Pepe, 1979) and for comparison with other heterocyclic compounds (De Mendoza et al., 1980). In these deliberate preparations it was made by the simple reaction of 4-amino-1,2,4-triazole with 2,5-diethoxytetrahydrofuran in acetic acid. Our accidental synthesis of (IV) from (I) is presumed to have occurred (see scheme) via a combination of over-oxidation, `beyond' (II) to the dicarboxylic acid (III), followed by double decarboxylation, leaving 3,5-unsubstituted (IV). The decarboxylation of acid-substituted triazole rings was first reported in 1907 (Curtius et al., 1907) and a mechanism proposed later (Dyson & Hammick, 1937). The only other structurally characterized (uncoordinated) compound featuring an N4triazole—Npyrrole connection between a 1,2,4-triazole and a pyrrole ring is 3,5-di(2-pyridyl)-N4-(pyrrol-1-yl)triazole (Mandal et al., 1993; Klingele et al., 2006).
The asymmetric unit comprises one and a half molecules as a C2 axis runs through the second molecule (Figs. 1 and 2, and Table 1). Each molecule consists of two planar five-membered rings, viz. one triazole ring and one pyrrole ring, connected by an N4triazole—Npyrrole bond. In both cases, the triazole ring is almost at right angles to the pyrrole ring [the inter-planar angles are 82.43 (8) and 74.41 (7)°, respectively]. The formulation of (IV) is therefore confirmed to be as shown in the scheme. Within experimental error, the bond lengths and angles in the two independent molecules are identical (Table 1). Likewise, the intra-ring torsion angles of the pairs of analgous rings are identical, although the inter-ring torsion angles differ (Table 1).
The bond lengths and angles in the triazole rings (Table 1) are within 0.012 Å of those seen in 4,4'-bitriazole (Domiano, 1977). The bond lengths in the pyrrole rings (Table 1) are within 0.007 Å of those seen in 1H-pyrrole (Allen et al., 1987). The N4triazole—Npyrrole bond lengths (Table 1) are intermediate between those expected for an N—N single bond (1.425 Å) and an N—N double bond (1.240 Å; Allen et al., 1987), indicating that some delocalization is occurring. The N—N inter-ring bond length observed in (IV) is identical to that in 4,4'-bitriazole (1.380 Å; Domiano, 1977).
Weak offset face-to-face π–π interactions (Hunter & Sanders, 1990; Janiak, 2000) with a centroid–centroid distance of 3.507 (2) Å and an angle of 20.2 (1)° between the mean planes, are present between each of the N22/C23/N24/C23A/N22A triazole rings, leading to stacking of these triazole rings along the c axis as shown in Fig. 2. The other triazole ring and the pyrrole rings are not involved in such π–π interactions.
There are three significant C—H···N interactions (Steiner, 1998; Desiraju & Steiner, 1999), all of which are intermolecular (Table 2, Fig. 2). One of these provides further connections between the adjacent, symmetry generated, offset π–π stacked (along the c axis), N22 triazole rings. The remaining two C—H···N interactions link the other independent set of molecules, those containing N1, to their symmetry-generated sets of neighbouring N1 molecules, generating ribbons along the the b axis. The N22 triazoles lie between the ribbons of N1 triazoles.