organic compounds
4,4-Bis(1H-pyrrol-2-yl)pentanol
aInstitute of Chemistry, University of Neuchâtel, rue Emile-Argand 11, 2009 Neuchâtel, Switzerland, and bInstitute of Physics, University of Neuchâtel, rue Emile-Argand 11, 2009 Neuchâtel, Switzerland
*Correspondence e-mail: reinhard.neier@unine.ch
The title achiral compound, C13H18N2O, crystallized in the chiral monoclinic P21. The pyrrole rings are inclined to one another by 62.30 (11)°, and the propanol chain is in an extended conformation. In the crystal, the two pyrrole NH groups are involved in intermolecular N—H⋯O hydrogen bonds, leading to the formation of a helical arrangement propagating along the b axis. An interesting feature of the is the absence of any conventional hydrogen bonds involving the hydroxy H atom. There is, however, a weak intermolecular O—H⋯π interaction involving one of the pyrrole rings.
Related literature
For substituted calix[4]pyrroles, see: Gale et al. (1998); Sessler & Davis (2001); Sessler et al. (2003). For the crystal structures of similar compounds, see: Warriner et al. (2003); Maeda et al. (2007); Sobral et al. (2003). For details of hydrogen-bonding graph-set analysis, see: Bernstein et al. (1995). For a description of the Cambridge Structural Database, see: Allen (2002).
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: X-AREA (Stoe & Cie, 2009); cell X-AREA; data reduction: X-RED32 (Stoe & Cie, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009).
Supporting information
https://doi.org/10.1107/S1600536809054269/is2505sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536809054269/is2505Isup2.hkl
A mixture of 3-acetylpropanol (10 ml, 98.6 mmol) and pyrrole (50 ml, 0.720 mol) were stirred for 5 min and then trifluoro acetic acid [TFA] (0.74 ml, 9.6 mmol, 0.097 equiv.) was added. The whole mixture was stirred foran additional 5 min and then quenched with aqueous NaOH (0.1 N, 30 ml). The mixture was extracted with CH2Cl2 (50 ml × 2) and the organic layer dried (Na2SO4). The solvent was removed in vacuo and the remaining oil crystallized with dichloromethane (20 ml). The colourless block-like crystals obtained were washed with 2-propanol [m.p. 372 K; Yield 14.1 g (65.3%)]. 1H NMR (CDCl3) δ 7.85 (bs, 2H, N—H), 6.63–6.61 (ddd, J = 2.7 Hz,2.7 Hz, 1.6 Hz, 2H, pyrrolic-H1–8), 6.15–6.13 (ddd, J = 3.3 Hz, 2.7 Hz, 1.6 Hz, 2H, pyrrolic-H2–7), 6.10–6.08 (ddd, J = 3.3 Hz, 1.6 Hz,1.6 Hz, 2H, pyrrolic-H3–6), 3.61–3.57 (td, J = 6 Hz, 5 Hz, 2H, –O—CH212), 2.07–2.03 (m, 2H, –CH210–), 1.59 (s, 3H, –CH313), 1.51–1.43 (m, 2H,-CH211–), 1.24–1.20 (t, J = 5 Hz, 1H, –OH); 13C NMR (CDCl3)δ 137.97 (C4–5), 117.15 (C1–5), 107.92 (C2–7),104.77 (C3–6), 63.26 (C12), 39.04 (C9), 37.35 (C10),28.01 (C11), 26.62 (C13). MS calcd. for C13H18N2O 218.14, found 217.13 (M—H+).
In the final cycles of
in the absence of significant effects, 1239 Friedel pairs were merged and Δf " set to zero. The OH and NH H-atoms, located in a difference electron-density map, were freely refined: O—H = 0.83 (3) Å; N—H = 0.88 (2) - 0.90 (2) Å. The C-bound H-atoms were included in calculated positions and treated as riding atoms: C—H = 0.95, 0.99 and 0.98 Å for CH, CH2 and CH3 H-atoms, respectively, with Uiso(H) = k × Ueq(C), where k = 1.2 for CH and CH2 H-atoms, and 1.5 for CH3 H-atoms.The title compound (systematic name: 4,4-di(1H-pyrrol-2-yl)pentan-1-ol) was prepared as a building block for the formation of substituted calix[4]pyrroles. The latter have been shown to form extremely interesting host–guest complexes with various anions (Gale et al., 1998; Sessler and Davis, 2001; Sessler et al., 2003).
The structure of the title compound is shown in Fig. 1, and the geometrical parameters are given in the Supplementary Information and the archived
This achiral compound crystallized in the chiral monoclinic P21. The bond lengths and angles are similar to those observed in 5 similar 1,1-bis(2-pyrrolyl)ethane compounds in the Cambridge Database (CSD, V5.30, last update Sep. 2009; Allen et al., 2002). These include the (3,4,5-tribromo-2-pyrrolyl) derivative (Warriner et al., 2003; AJARIM), the o-, m- and p-pyridyl derivaties (Maeda et al., 2007; CIGKIN, CIGKEJ, CIGKAF, respectively) and the phenyl derivative (Sobral et al., 2003; JADHUS), all of which crystallized as racemates.In the title compound the pyrrole ring mean-planes are inclined to one another by 62.30 (11)°, and the propanol chain is in the extended conformation. In the 5 compounds located in the CSD this angle varies between 68.5 to 89.6 °.
In the crystal the molecules are linked by conventional N—H···N intermolecular hydrogen bonds leading to the formation of helical chains propagating along the b axis (Fig. 2 and Table 1). The basic unitary hydrogen bonding graph set can be described by an R23(16) ring, while the basic binary graph set is a C(8) chain. This gives an extended notation of C(8)[R23(16)] (Bernstein et al., 1995). A fuller hydrogen bonding graph set analysis can be obtained using the program Mercury (Macrea et al., 2006).
An O—H···π interaction is also observed in the (Fig. 2 and Table 1). It can be considered either to involve the C7═C8 bond (centroid = Cg1) with an O—H···π angle of ca 135°, or a weaker interaction involving the pyrrole ring (N2/C5—C8; centroid = Cg2), with an O—H···π angle of only ca 114° [these data were obtained using the program Mercury (Macrae et al., 2006)].
For substituted calix[4]pyrroles, see: Gale et al. (1998); Sessler & Davis (2001); Sessler et al. (2003). For the crystal structures of similar compounds, see: Warriner et al. (2003); Maeda et al. (2007); Sobral et al. (2003). For details of hydrogen-bonding graph-set analysis, see: Bernstein et al. (1995). For a description of the Cambridge Structural Database, see: Allen (2002).
Data collection: X-AREA (Stoe & Cie, 2009); cell
X-AREA (Stoe & Cie, 2009); data reduction: X-RED32 (Stoe & Cie, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).Fig. 1. A view of the molecular structure of the title compound, with the displacement ellipsoids drawn at the 50% probability level. | |
Fig. 2. A view, along the c axis, of the crystal packing of the title compound. The N—H···O hydrogen bonds are shown as dotted cyan lines and the O—H···π interactions as dotted black lines [for clarity these interactions are shown for only one of the helices; see Table 1 for details]. |
C13H18N2O | F(000) = 236 |
Mr = 218.29 | Dx = 1.221 Mg m−3 |
Monoclinic, P21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2yb | Cell parameters from 5671 reflections |
a = 8.4721 (15) Å | θ = 2.4–29.6° |
b = 8.2111 (9) Å | µ = 0.08 mm−1 |
c = 8.7120 (15) Å | T = 173 K |
β = 101.530 (14)° | Block, colourless |
V = 593.82 (16) Å3 | 0.45 × 0.45 × 0.40 mm |
Z = 2 |
Stoe IPDS-2 diffractometer | 1518 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.032 |
Graphite monochromator | θmax = 29.2°, θmin = 2.4° |
φ ans ω scans | h = −10→11 |
6119 measured reflections | k = −11→11 |
1701 independent reflections | l = −11→11 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.030 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.077 | w = 1/[σ2(Fo2) + (0.0571P)2] where P = (Fo2 + 2Fc2)/3 |
S = 0.97 | (Δ/σ)max < 0.001 |
1701 reflections | Δρmax = 0.19 e Å−3 |
159 parameters | Δρmin = −0.16 e Å−3 |
1 restraint | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.108 (11) |
C13H18N2O | V = 593.82 (16) Å3 |
Mr = 218.29 | Z = 2 |
Monoclinic, P21 | Mo Kα radiation |
a = 8.4721 (15) Å | µ = 0.08 mm−1 |
b = 8.2111 (9) Å | T = 173 K |
c = 8.7120 (15) Å | 0.45 × 0.45 × 0.40 mm |
β = 101.530 (14)° |
Stoe IPDS-2 diffractometer | 1518 reflections with I > 2σ(I) |
6119 measured reflections | Rint = 0.032 |
1701 independent reflections |
R[F2 > 2σ(F2)] = 0.030 | 1 restraint |
wR(F2) = 0.077 | H atoms treated by a mixture of independent and constrained refinement |
S = 0.97 | Δρmax = 0.19 e Å−3 |
1701 reflections | Δρmin = −0.16 e Å−3 |
159 parameters |
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles |
Refinement. In the final cycles of refinement, in the absence of significant anomalous scattering effects, 1239 Friedel pairs were merged and Δf " set to zero. The OH and NH hydrogen atoms were located in difference electron-density maps and were freely refined. The C-bound H-atoms were included in calculated positions and treated as riding. |
x | y | z | Uiso*/Ueq | ||
O1 | 0.41371 (13) | 1.28786 (14) | 0.88057 (13) | 0.0300 (3) | |
N1 | 0.24737 (14) | 0.55996 (17) | 0.99568 (13) | 0.0244 (3) | |
N2 | 0.48148 (15) | 0.66563 (17) | 0.79634 (16) | 0.0281 (3) | |
C1 | 0.18516 (15) | 0.69959 (18) | 0.92203 (15) | 0.0220 (3) | |
C2 | 0.12554 (18) | 0.7921 (2) | 1.02911 (17) | 0.0293 (4) | |
C3 | 0.15673 (18) | 0.7047 (2) | 1.17356 (17) | 0.0318 (4) | |
C4 | 0.23207 (17) | 0.5631 (2) | 1.14900 (16) | 0.0286 (4) | |
C5 | 0.33030 (17) | 0.64998 (19) | 0.70462 (15) | 0.0248 (4) | |
C6 | 0.3443 (2) | 0.5545 (3) | 0.57848 (18) | 0.0409 (5) | |
C7 | 0.5085 (3) | 0.5108 (3) | 0.5947 (2) | 0.0518 (7) | |
C8 | 0.5900 (2) | 0.5804 (3) | 0.7302 (2) | 0.0419 (6) | |
C9 | 0.18427 (16) | 0.72822 (17) | 0.74921 (15) | 0.0221 (3) | |
C10 | 0.17922 (17) | 0.91270 (19) | 0.71418 (16) | 0.0244 (4) | |
C11 | 0.32247 (16) | 1.01255 (19) | 0.79998 (16) | 0.0248 (4) | |
C12 | 0.2876 (2) | 1.1921 (2) | 0.7865 (2) | 0.0398 (5) | |
C13 | 0.03085 (19) | 0.6525 (2) | 0.65082 (18) | 0.0349 (4) | |
H1N | 0.297 (2) | 0.482 (3) | 0.955 (2) | 0.037 (5)* | |
H1O | 0.485 (4) | 1.307 (4) | 0.823 (3) | 0.073 (9)* | |
H2 | 0.07350 | 0.89480 | 1.01050 | 0.0350* | |
H2N | 0.504 (2) | 0.709 (3) | 0.893 (2) | 0.034 (5)* | |
H3 | 0.12990 | 0.73890 | 1.26930 | 0.0380* | |
H4 | 0.26760 | 0.48110 | 1.22500 | 0.0340* | |
H6 | 0.25910 | 0.52330 | 0.49530 | 0.0490* | |
H7 | 0.55360 | 0.44540 | 0.52450 | 0.0620* | |
H8 | 0.70230 | 0.57120 | 0.77130 | 0.0500* | |
H10A | 0.17120 | 0.92760 | 0.60010 | 0.0290* | |
H10B | 0.07980 | 0.95800 | 0.74090 | 0.0290* | |
H11A | 0.34710 | 0.98110 | 0.91190 | 0.0300* | |
H11B | 0.41830 | 0.98810 | 0.75510 | 0.0300* | |
H12A | 0.27480 | 1.22540 | 0.67550 | 0.0480* | |
H12B | 0.18470 | 1.21430 | 0.82010 | 0.0480* | |
H13A | −0.06410 | 0.70130 | 0.68090 | 0.0520* | |
H13B | 0.03100 | 0.53480 | 0.66940 | 0.0520* | |
H13C | 0.02780 | 0.67330 | 0.53950 | 0.0520* |
U11 | U22 | U33 | U12 | U13 | U23 | |
O1 | 0.0322 (5) | 0.0208 (6) | 0.0362 (5) | −0.0021 (4) | 0.0048 (4) | −0.0009 (4) |
N1 | 0.0277 (6) | 0.0221 (6) | 0.0244 (5) | −0.0005 (5) | 0.0073 (4) | 0.0010 (5) |
N2 | 0.0256 (5) | 0.0262 (7) | 0.0345 (6) | 0.0036 (5) | 0.0106 (5) | 0.0033 (5) |
C1 | 0.0204 (5) | 0.0215 (7) | 0.0239 (6) | −0.0020 (5) | 0.0043 (4) | 0.0001 (5) |
C2 | 0.0302 (7) | 0.0289 (8) | 0.0307 (7) | 0.0036 (6) | 0.0108 (5) | −0.0001 (6) |
C3 | 0.0331 (7) | 0.0384 (9) | 0.0262 (6) | −0.0018 (7) | 0.0118 (5) | −0.0011 (6) |
C4 | 0.0299 (7) | 0.0320 (8) | 0.0249 (6) | −0.0035 (6) | 0.0078 (5) | 0.0046 (6) |
C5 | 0.0321 (7) | 0.0208 (7) | 0.0224 (6) | 0.0019 (6) | 0.0073 (5) | 0.0027 (5) |
C6 | 0.0604 (11) | 0.0407 (10) | 0.0228 (6) | 0.0155 (9) | 0.0113 (6) | 0.0012 (6) |
C7 | 0.0729 (13) | 0.0529 (13) | 0.0382 (9) | 0.0297 (11) | 0.0318 (9) | 0.0085 (9) |
C8 | 0.0396 (8) | 0.0425 (11) | 0.0505 (10) | 0.0156 (8) | 0.0257 (7) | 0.0153 (8) |
C9 | 0.0231 (6) | 0.0217 (7) | 0.0206 (5) | −0.0018 (5) | 0.0025 (4) | −0.0003 (5) |
C10 | 0.0245 (6) | 0.0230 (7) | 0.0243 (6) | 0.0015 (5) | 0.0016 (5) | 0.0018 (5) |
C11 | 0.0241 (6) | 0.0200 (7) | 0.0290 (6) | 0.0013 (5) | 0.0025 (5) | 0.0026 (5) |
C12 | 0.0364 (8) | 0.0217 (9) | 0.0537 (10) | 0.0023 (7) | −0.0094 (7) | −0.0004 (7) |
C13 | 0.0336 (7) | 0.0372 (9) | 0.0303 (7) | −0.0103 (7) | −0.0021 (5) | −0.0021 (7) |
O1—C12 | 1.443 (2) | C10—C11 | 1.530 (2) |
O1—H1O | 0.87 (3) | C11—C12 | 1.504 (2) |
N1—C1 | 1.367 (2) | C2—H2 | 0.9500 |
N1—C4 | 1.3678 (18) | C3—H3 | 0.9500 |
N2—C8 | 1.371 (2) | C4—H4 | 0.9500 |
N2—C5 | 1.3735 (19) | C6—H6 | 0.9500 |
N1—H1N | 0.88 (2) | C7—H7 | 0.9500 |
N2—H2N | 0.899 (19) | C8—H8 | 0.9500 |
C1—C9 | 1.5224 (18) | C10—H10A | 0.9900 |
C1—C2 | 1.375 (2) | C10—H10B | 0.9900 |
C2—C3 | 1.427 (2) | C11—H11A | 0.9900 |
C3—C4 | 1.364 (2) | C11—H11B | 0.9900 |
C5—C6 | 1.374 (2) | C12—H12A | 0.9900 |
C5—C9 | 1.512 (2) | C12—H12B | 0.9900 |
C6—C7 | 1.416 (3) | C13—H13A | 0.9800 |
C7—C8 | 1.368 (3) | C13—H13B | 0.9800 |
C9—C10 | 1.544 (2) | C13—H13C | 0.9800 |
C9—C13 | 1.538 (2) | ||
C12—O1—H1O | 106.9 (19) | C4—C3—H3 | 126.00 |
C1—N1—C4 | 109.86 (13) | N1—C4—H4 | 126.00 |
C5—N2—C8 | 109.48 (13) | C3—C4—H4 | 126.00 |
C4—N1—H1N | 123.7 (13) | C5—C6—H6 | 126.00 |
C1—N1—H1N | 126.3 (13) | C7—C6—H6 | 126.00 |
C5—N2—H2N | 125.5 (11) | C6—C7—H7 | 126.00 |
C8—N2—H2N | 124.2 (12) | C8—C7—H7 | 126.00 |
N1—C1—C2 | 107.72 (12) | N2—C8—H8 | 126.00 |
N1—C1—C9 | 121.26 (12) | C7—C8—H8 | 126.00 |
C2—C1—C9 | 130.98 (13) | C9—C10—H10A | 108.00 |
C1—C2—C3 | 106.99 (14) | C9—C10—H10B | 108.00 |
C2—C3—C4 | 107.48 (13) | C11—C10—H10A | 108.00 |
N1—C4—C3 | 107.94 (13) | C11—C10—H10B | 108.00 |
N2—C5—C6 | 107.40 (14) | H10A—C10—H10B | 107.00 |
N2—C5—C9 | 121.77 (12) | C10—C11—H11A | 109.00 |
C6—C5—C9 | 130.82 (13) | C10—C11—H11B | 109.00 |
C5—C6—C7 | 107.75 (15) | C12—C11—H11A | 109.00 |
C6—C7—C8 | 107.25 (18) | C12—C11—H11B | 109.00 |
N2—C8—C7 | 108.11 (17) | H11A—C11—H11B | 108.00 |
C1—C9—C10 | 109.96 (11) | O1—C12—H12A | 109.00 |
C1—C9—C5 | 110.24 (11) | O1—C12—H12B | 109.00 |
C5—C9—C10 | 110.97 (12) | C11—C12—H12A | 109.00 |
C5—C9—C13 | 109.20 (12) | C11—C12—H12B | 109.00 |
C1—C9—C13 | 108.99 (11) | H12A—C12—H12B | 108.00 |
C10—C9—C13 | 107.43 (11) | C9—C13—H13A | 109.00 |
C9—C10—C11 | 116.18 (12) | C9—C13—H13B | 109.00 |
C10—C11—C12 | 111.28 (12) | C9—C13—H13C | 109.00 |
O1—C12—C11 | 112.24 (13) | H13A—C13—H13B | 109.00 |
C1—C2—H2 | 127.00 | H13A—C13—H13C | 109.00 |
C3—C2—H2 | 126.00 | H13B—C13—H13C | 110.00 |
C2—C3—H3 | 126.00 | ||
C4—N1—C1—C2 | −1.41 (16) | N2—C5—C6—C7 | 0.2 (2) |
C4—N1—C1—C9 | −179.27 (12) | C9—C5—C6—C7 | −178.96 (17) |
C1—N1—C4—C3 | 1.08 (17) | N2—C5—C9—C1 | −45.13 (18) |
C8—N2—C5—C6 | −0.4 (2) | N2—C5—C9—C10 | 76.94 (16) |
C8—N2—C5—C9 | 178.81 (15) | N2—C5—C9—C13 | −164.83 (14) |
C5—N2—C8—C7 | 0.5 (2) | C6—C5—C9—C1 | 133.92 (18) |
N1—C1—C2—C3 | 1.17 (17) | C6—C5—C9—C10 | −104.0 (2) |
C9—C1—C2—C3 | 178.74 (14) | C6—C5—C9—C13 | 14.2 (2) |
N1—C1—C9—C5 | −32.86 (18) | C5—C6—C7—C8 | 0.1 (2) |
N1—C1—C9—C10 | −155.52 (13) | C6—C7—C8—N2 | −0.4 (3) |
N1—C1—C9—C13 | 86.97 (15) | C1—C9—C10—C11 | 61.87 (15) |
C2—C1—C9—C5 | 149.85 (15) | C5—C9—C10—C11 | −60.36 (15) |
C2—C1—C9—C10 | 27.2 (2) | C13—C9—C10—C11 | −179.65 (12) |
C2—C1—C9—C13 | −90.32 (18) | C9—C10—C11—C12 | −166.90 (12) |
C1—C2—C3—C4 | −0.53 (18) | C10—C11—C12—O1 | 173.65 (12) |
C2—C3—C4—N1 | −0.33 (17) |
Cg1 and Cg2 are the centroids of the C7═C8 bond and the N2/C5–C8 pyrrole ring, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N···O1i | 0.88 (2) | 2.05 (2) | 2.9238 (18) | 174.3 (19) |
N2—H2N···O1ii | 0.90 (2) | 2.06 (2) | 2.9529 (18) | 171.5 (19) |
O1—H1O···Cg1iii | 0.87 (3) | 2.53 | 3.20 | 135 |
O1—H1O···Cg2iii | 0.87 (3) | 2.64 | 3.10 | 114 |
Symmetry codes: (i) x, y−1, z; (ii) −x+1, y−1/2, −z+2; (iii) x, y+1, z. |
Experimental details
Crystal data | |
Chemical formula | C13H18N2O |
Mr | 218.29 |
Crystal system, space group | Monoclinic, P21 |
Temperature (K) | 173 |
a, b, c (Å) | 8.4721 (15), 8.2111 (9), 8.7120 (15) |
β (°) | 101.530 (14) |
V (Å3) | 593.82 (16) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.45 × 0.45 × 0.40 |
Data collection | |
Diffractometer | Stoe IPDS2 |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6119, 1701, 1518 |
Rint | 0.032 |
(sin θ/λ)max (Å−1) | 0.686 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.030, 0.077, 0.97 |
No. of reflections | 1701 |
No. of parameters | 159 |
No. of restraints | 1 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.19, −0.16 |
Computer programs: X-AREA (Stoe & Cie, 2009), X-RED32 (Stoe & Cie, 2009), SHELXS97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2006), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).
Cg1 and Cg2 are the centroids of the C7═C8 bond and the N2/C5–C8 pyrrole ring, respectively. |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1N···O1i | 0.88 (2) | 2.05 (2) | 2.9238 (18) | 174.3 (19) |
N2—H2N···O1ii | 0.90 (2) | 2.06 (2) | 2.9529 (18) | 171.5 (19) |
O1—H1O···Cg1iii | 0.87 (3) | 2.53 | 3.20 | 135 |
O1—H1O···Cg2iii | 0.87 (3) | 2.64 | 3.10 | 114 |
Symmetry codes: (i) x, y−1, z; (ii) −x+1, y−1/2, −z+2; (iii) x, y+1, z. |
Acknowledgements
HSE is grateful to the XRD Application LAB, Microsystems Technology Division, Swiss Center for Electronics and Microtechnology, Neuchâtel, for access to the X-ray diffraction equipment.
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The title compound (systematic name: 4,4-di(1H-pyrrol-2-yl)pentan-1-ol) was prepared as a building block for the formation of substituted calix[4]pyrroles. The latter have been shown to form extremely interesting host–guest complexes with various anions (Gale et al., 1998; Sessler and Davis, 2001; Sessler et al., 2003).
The structure of the title compound is shown in Fig. 1, and the geometrical parameters are given in the Supplementary Information and the archived CIF. This achiral compound crystallized in the chiral monoclinic space group P21. The bond lengths and angles are similar to those observed in 5 similar 1,1-bis(2-pyrrolyl)ethane compounds in the Cambridge Crystal Structure Database (CSD, V5.30, last update Sep. 2009; Allen et al., 2002). These include the (3,4,5-tribromo-2-pyrrolyl) derivative (Warriner et al., 2003; AJARIM), the o-, m- and p-pyridyl derivaties (Maeda et al., 2007; CIGKIN, CIGKEJ, CIGKAF, respectively) and the phenyl derivative (Sobral et al., 2003; JADHUS), all of which crystallized as racemates.
In the title compound the pyrrole ring mean-planes are inclined to one another by 62.30 (11)°, and the propanol chain is in the extended conformation. In the 5 compounds located in the CSD this angle varies between 68.5 to 89.6 °.
In the crystal the molecules are linked by conventional N—H···N intermolecular hydrogen bonds leading to the formation of helical chains propagating along the b axis (Fig. 2 and Table 1). The basic unitary hydrogen bonding graph set can be described by an R23(16) ring, while the basic binary graph set is a C(8) chain. This gives an extended notation of C(8)[R23(16)] (Bernstein et al., 1995). A fuller hydrogen bonding graph set analysis can be obtained using the program Mercury (Macrea et al., 2006).
An O—H···π interaction is also observed in the crystal structure (Fig. 2 and Table 1). It can be considered either to involve the C7═C8 bond (centroid = Cg1) with an O—H···π angle of ca 135°, or a weaker interaction involving the pyrrole ring (N2/C5—C8; centroid = Cg2), with an O—H···π angle of only ca 114° [these data were obtained using the program Mercury (Macrae et al., 2006)].