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The title compound [systematic name: (4,4-dimethyl-8-methyl­ene-3-azabicyclo[3.3.1]non-2-en-2-yl)(1H-indol-3-yl)methan­one], C20H22N2O, (II), was obtained from mother liquors extracted from Aristotelia chilensis (commonly known as maqui), a native Chilean tree. The compound is a polymorphic form of that obtained from the same source and reported by Watson, Nagl, Silva, Cespedes & Jakupovic [Acta Cryst. (1989), C45, 1322–1324], (Ia). The mol­ecule consists of an indolyl ketone fragment and a nested three-ring system, with both groups linked by a C—C bridge. Comparison of both forms shows that they do not differ in their gross features but in the relative orientation of the two ring systems, due to different rotations around the bridge, as measured by the O=C—C=N torsion angle [130.0 (7)° in (Ia) and 161.6 (2)° in (II)]. The resulting slight conformational differences are reflected in a number of intra­molecular contacts being observed in (II) but not in (Ia). Regarding inter­molecular inter­actions, both forms share a similar N—H...O synthon but with differing hydrogen-bonding strength, leading in both cases to C(6) catemers with different chain motifs. There are marked differences between the two forms regarding colour and the (de)localization of a double bond, which allows speculation about the possible existence of different variants of this type of mol­ecule.

Supporting information


Crystallographic Information File (CIF)
Contains datablocks I, global


Structure factor file (CIF format)
Contains datablock I


Chemical Markup Language (CML) file
Supplementary material

CCDC reference: 960964

Introduction top

Aristotelia chilensis (commonly known as maqui) is a native Chilean tree. Liquors made from it show a variety of therapeutic properties, known to the original Araucanian inhabitants since ancient times. Studies during the 1970s and 1980s gave strong scientific support to this ancient knowledge: the tree has been shown to produce a significant number of molecular species of proved (or potential) pharmaceutical power. Among others, a number of different indole alkaloids have been identified, some of them already known from other botanical species [viz. aristoteline, aristotelone (Bhakuni et al., 1976), aristotelinine, aristone (Bittner et al., 1978)] and others originally described from A. chilensis extracts. One of these latter alkaloids was 4,4-di­methyl-8-methyl­ene-3-aza­bicyclo­[3.3.1]non-2-en-2-yl 3-indolyl ketone, structurally characterized by Watson et al. (1989), where two isomers of this molecule were mentioned as isolated from A. chilensis. Both forms [hereinafter (Ia) and (Ib)] were characterized by NMR, and the results showed that the main difference resided in a double bond being either exo- or endo-cyclic (see scheme, encircled regions). The structure of only one of the two isomers was elucidated by single-crystal methods and shown to have an exocyclic double bond and an endocylic single one, and was thus assigned to form (Ia).

A recrystallization of a harvest of maqui liquors recently made in our laboratory provided a second crystallographic form of the same compound, hereinafter (II), and the crystal structural analysis reported here primarily suggested the molecule to be a polymorph of (Ia) [brief crystal data: both forms orthorhombic, space group P212121, Z = 4, but for (Ia): pale-yellow crystals, a = 6.480 (1), b = 12.844 (2), c = 19.960 (3) Å, and for (II): deep-red crystals, a = 9.7841 (5), b = 12.3479 (7); c = 13.8639 (5) Å].

We shall compare both structures in their gross features, as well as in the subtle differences telling the two molecular forms apart.

Experimental top

Isolation, purification and crystallization top

A. chilensis (maqui) was collected in Concepción, VIII Region of Chile (36°50'00" S and 73°01'54" W) in February 2012. Leaves (20 kg) were dried at 313 K, powdered and macerated for 7 d in water acidified with HCl to pH 3. The water layer (50 l) was then separated by filtration, basified with NaOH to pH 10 and extracted with EtOAc (3 × 20 l), and the organic layer was concentrated in vacuo to obtain a crude alkaloid fraction. The alkaloid extract was chromatographed on aluminium oxide and eluted with hexane, hexane–ethyl acetate 1:1 v/v, ethyl acetate, ethyl acetate–methanol 8:2 v/v gradient. The preparative chromatography was monitored by thin-layer chromatography (TLC) (silica gel) and revealed using UV light and, later, Dragendorff's reagent; those fractions showing similar TLC patterns were pooled and subsequently purified by chromatography with the same procedure. From the hexane–ethyl acetate 1:1 v/v fraction, deep-red crystals of (II) were obtained. Analysis: [α]D25 = 7.9 (c 0.24, CHCl3); m.p. 529–530 K. ESI [M+H]+: 307.1748. The crystals were further characterized by NMR (Table 4).

Refinement top

Crystal data, data collection and structure refinement details are summarized in Table 1. All H atoms were found in a difference map, but C-bound H atoms were repositioned at their ideal values, with C—H(methyl­ene) = 0.97, C—H(aromatic) = 0.93 and C—H(methyl) = 0.96 Å. The only N-bound H atom was refined freely [N—H = 0.88 (3) Å]. In all cases, Uiso(H) = 1.2(1.5 for methyl)Ueq(parent). Due to the (expected) very small Bijvoet pair differences, the absolute structure could not be reliably determined.

Results and discussion top

Fig. 1 shows the molecular structure of (II). Prima facie, the structure does not differ substanti­ally from that of (Ia) except in some torsion angles which determine their spatial stereochemistry, some of which are compared in Table 2. These torsion angles force (II) to be in a slightly more `open' conformation than (Ia), as shown in Fig 2, where an overlap of both molecules is shown. A rough measure of this more open character can be found in the N1···N2 distances, 5.24 (2) Å in (Ia) versus 5.63 (2) Å in (II). This conformation seems to favour the existence of clear, though weak, C—H···N and C—H···O intra­molecular inter­actions [Table 3, structure (II), topmost three entries, and Fig. 1). Similar inter­actions are almost absent in (Ia), where the only significant intra­molecular contact [Table 3, structure (Ia), first entry = 2.966 (6) Å] is much weaker than its counterpart in (II) [2.852 (2) Å].

Regarding inter­molecular inter­actions, both compounds share the same N—H···O synthon, leading in both cases to C(6) catemers (for hydrogen-bond notation, see Etter, 1990). There are, however, dissimilar characteristics in both hydrogen-bond strength [Table 3, structure (II), fourth entry, and structure (Ia), second entry] and the resulting chain geometry (Fig. 3): while the weak inter­action in (Ia) leads to a translationally repetitive motif along [100] (Fig. 3a), the much stronger one in (II), threaded along a two-fold screw axis, leads to an alternating motif along [001] (Fig. 3b). In contrast with what would primarily be expected from a simple analysis of hydrogen-bond strengths, the chain in (Ia) is `shorter' [a(Ia) < 1/2c(II)] by nearly 7%. The ultimate reason is apparent from comparison of both chains in Figs. 3(a) and 3(b): the very weakness of the N—H···O bond allows for a more closed N—H···O angle in (Ia), thus allowing the molecules to approach each other more closely. On the other hand, the `straighter' inter­action in (II) keeps the molecules apart, resulting in a longer [001] chain.

The remaining inter­actions holding the chain motifs together are weaker and unexceptional. However, they seem to be more effective in (II), since the original `shrinkage' in chain length in (Ia) (~7%) reduces to a mere 0.008% in cell volume, the final result being a slightly more compact structure for this latter form [calculated densities: (Ia) 1.225 Mg m-3 and (II) 1.215 Mg m-3]. Nevertheless, these differences in inter­molecular inter­actions do not seem to be manifested in the rather similar melting points of both compounds [(Ia), m.p. 532–533 K; (II), m.p. 529–530K].

Finally, we analyse some subtleties differentiating (Ia) and (II) at the molecular level. A rather puzzling one is their striking colour difference [(Ia) is light yellowish while (II) is deep red; see Fig. 4) regardless of structural similarities. In this respect, the situation resembles much of what was reported by Yu (2002). In that paper the difference in crystal colour, or `colour polymorphism', was attributed to conformational differences between polymorphs, which would cause varying degrees of conjugation between aromatic chromophores. The determining parameter would in this case be the torsion angle between aromatic rings, which with a shift from 104.7 (2) to 52.6 (4) to 21.7 (3)° (when going from one polymorph to another) could be responsible for a striking yellow-to-orange-to-red colour shift. In the (Ia)–(II) system, there is an anlogous situation, the equivalent groups being in this case the indolyl ketone system and the planar portion of the heterocyclic six-membered ring, their relative orientation being easily measured by the O1C14—C15N1 angle [130.0 (7)° in the yellowish (Ia) and 161.6 (2)° in the deep-red (II)]. The striking similarity in colour shift, with an even tighter torsion-angle span, is apparent.

A perhaps related issue concerns the delocalization of the terminal C—CH3 <-> CCH2 bond. As previously stated, Watson et al. (1989) differentiated the isomeric forms (Ia) and (Ib) by their NMR results, ascribing to (Ia) a double bond at C5C20 [1.344 (8) Å] and a single one at C5—C16 [1.419 (9) Å]. Unfortunately, no crystal data for (Ib) are available to confirm this difference by crystallographic means. When comparing these results with the present ones for (II), the equivalent values found here, namely C5C20 [1.327 (7) Å] and C5—C16 [1.496 (7) Å] present a much clearer `double' and `single' character than those reported for (Ia). In this sense, it is the present structure, (II), which seems to be the one to be described as a pure non-resonant molecule, while in (Ia) some delocalization between both exo and endo bonds seems to take place. In this context it is tempting to speculate about the possible existence of a continuous series of resonant forms of the molecule, spontaneously occurring in the natural synthesis of the alkaloid. Unfortunately there is no satisfactory way of proving this kind of assertion regarding naturally occurring products, short of obtaining them by chance as in the present report.

Related literature top

For related literature, see: Bhakuni et al. (1976); Bittner et al. (1978); Etter (1990); Watson et al. (1989); Yu (2002).

Computing details top

Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecule of (II), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Dashed lines indicate relevant intramolecular hydrogen-bonding interactions.
[Figure 2] Fig. 2. A comparison of the stereodisposition of the present structure, (II) (solid lines) and that of (Ia) (dashed lines), after matching the almost identical indole groups.
[Figure 3] Fig. 3. The chain structures of both compounds. (a) Structure (Ia) [symmetry code: (i) x + 1, y, z.] (b) Structure (II) [symmetry code: (ii) 3/2 - x, -y, -1/2 + z.]
[Figure 4] Fig. 4. Crystalline samples of both compounds, showing the difference in colour. (a) A pale-yellow crystal of (Ia) and (b) a deep-red crystal of (II).
(4,4-Dimethyl-8-methylene-3-azabicyclo[3.3.1]non-2-en-2-yl)(1H-indol-3-yl)methanone top
Crystal data top
C20H22N2OF(000) = 656
Mr = 306.40Dx = 1.215 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 1161 reflections
a = 9.7841 (5) Åθ = 3.9–28.8°
b = 12.3479 (7) ŵ = 0.08 mm1
c = 13.8639 (5) ÅT = 295 K
V = 1674.95 (14) Å3Prism, red
Z = 40.32 × 0.18 × 0.10 mm
Data collection top
Oxford Gemini S Ultra CCD area-detector
3411 independent reflections
Radiation source: fine-focus sealed tube2453 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.021
ω scans, thick slicesθmax = 28.9°, θmin = 3.9°
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2009)
h = 1312
Tmin = 0.98, Tmax = 0.99k = 816
4670 measured reflectionsl = 1018
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.054H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.140 w = 1/[σ2(Fo2) + (0.0635P)2 + 0.1599P]
where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max < 0.001
3411 reflectionsΔρmax = 0.15 e Å3
214 parametersΔρmin = 0.16 e Å3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.014 (3)
Crystal data top
C20H22N2OV = 1674.95 (14) Å3
Mr = 306.40Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 9.7841 (5) ŵ = 0.08 mm1
b = 12.3479 (7) ÅT = 295 K
c = 13.8639 (5) Å0.32 × 0.18 × 0.10 mm
Data collection top
Oxford Gemini S Ultra CCD area-detector
3411 independent reflections
Absorption correction: multi-scan
(CrysAlis PRO; Oxford Diffraction, 2009)
2453 reflections with I > 2σ(I)
Tmin = 0.98, Tmax = 0.99Rint = 0.021
4670 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0540 restraints
wR(F2) = 0.140H atoms treated by a mixture of independent and constrained refinement
S = 1.02Δρmax = 0.15 e Å3
3411 reflectionsΔρmin = 0.16 e Å3
214 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
O10.67543 (19)0.00046 (14)1.03376 (10)0.0550 (5)
N10.5726 (3)0.1765 (2)0.85277 (16)0.0653 (7)
N20.8665 (2)0.03048 (17)0.73555 (14)0.0515 (5)
H2N0.881 (3)0.027 (2)0.673 (2)0.062*
C10.4690 (4)0.2577 (3)0.8245 (2)0.0769 (10)
C20.3351 (3)0.2516 (2)0.8838 (2)0.0683 (8)
C30.3731 (4)0.2346 (2)0.98827 (19)0.0684 (8)
C40.4408 (3)0.1238 (2)0.99661 (18)0.0562 (7)
C50.3393 (3)0.0374 (3)0.9736 (3)0.0907 (11)
C60.7690 (3)0.0262 (2)0.78094 (14)0.0465 (6)
C70.9286 (3)0.10058 (19)0.79999 (15)0.0437 (6)
C81.0318 (3)0.1763 (2)0.78454 (18)0.0595 (7)
C91.0712 (3)0.2380 (2)0.86195 (19)0.0672 (8)
C101.0123 (3)0.2244 (2)0.95220 (19)0.0676 (8)
C110.9104 (3)0.1487 (2)0.96750 (17)0.0559 (7)
C120.8668 (2)0.08478 (18)0.88987 (14)0.0408 (5)
C130.7629 (2)0.00248 (18)0.87737 (14)0.0396 (5)
C140.6699 (2)0.03597 (18)0.95035 (15)0.0412 (5)
C150.5589 (3)0.11876 (19)0.92747 (15)0.0439 (6)
C160.2784 (4)0.0504 (4)0.8753 (4)0.1232 (17)
C170.2296 (4)0.1662 (4)0.8570 (3)0.1085 (14)
C180.5376 (5)0.3683 (3)0.8374 (3)0.1200 (16)
C190.4439 (6)0.2385 (5)0.7166 (2)0.142 (2)
C200.3082 (5)0.0406 (4)1.0357 (5)0.158 (2)
Atomic displacement parameters (Å2) top
O10.0665 (11)0.0655 (11)0.0329 (7)0.0124 (10)0.0034 (8)0.0052 (8)
N10.0664 (15)0.0780 (16)0.0515 (12)0.0245 (15)0.0029 (11)0.0160 (11)
N20.0576 (12)0.0651 (13)0.0317 (9)0.0064 (12)0.0043 (10)0.0005 (9)
C10.082 (2)0.091 (2)0.0568 (16)0.039 (2)0.0002 (16)0.0165 (15)
C20.0695 (18)0.0718 (19)0.0636 (16)0.0343 (17)0.0032 (16)0.0085 (14)
C30.079 (2)0.0678 (17)0.0582 (16)0.0216 (18)0.0096 (15)0.0074 (13)
C40.0596 (16)0.0590 (15)0.0501 (13)0.0141 (15)0.0071 (13)0.0015 (12)
C50.0481 (16)0.071 (2)0.153 (4)0.0041 (18)0.017 (2)0.006 (2)
C60.0503 (13)0.0525 (14)0.0367 (11)0.0030 (13)0.0024 (10)0.0006 (10)
C70.0468 (13)0.0478 (13)0.0365 (11)0.0012 (12)0.0034 (11)0.0040 (10)
C80.0652 (17)0.0686 (17)0.0445 (13)0.0119 (16)0.0029 (12)0.0127 (12)
C90.077 (2)0.0634 (17)0.0609 (17)0.0259 (18)0.0044 (15)0.0082 (13)
C100.086 (2)0.0669 (17)0.0500 (14)0.0273 (18)0.0066 (15)0.0064 (13)
C110.0674 (17)0.0592 (15)0.0412 (12)0.0107 (14)0.0019 (13)0.0023 (11)
C120.0438 (12)0.0434 (12)0.0352 (11)0.0011 (11)0.0037 (10)0.0026 (9)
C130.0415 (11)0.0434 (12)0.0339 (10)0.0020 (10)0.0040 (10)0.0007 (9)
C140.0429 (12)0.0466 (12)0.0343 (10)0.0017 (11)0.0034 (10)0.0038 (9)
C150.0454 (13)0.0491 (13)0.0373 (11)0.0021 (12)0.0044 (10)0.0038 (10)
C160.070 (2)0.097 (3)0.204 (5)0.007 (2)0.049 (3)0.039 (3)
C170.062 (2)0.129 (4)0.135 (3)0.026 (2)0.033 (2)0.025 (3)
C180.113 (3)0.090 (3)0.157 (4)0.021 (3)0.010 (3)0.062 (3)
C190.166 (5)0.213 (5)0.0476 (18)0.122 (4)0.002 (2)0.018 (2)
C200.090 (3)0.096 (3)0.288 (7)0.005 (3)0.055 (4)0.052 (4)
Geometric parameters (Å, º) top
O1—C141.238 (3)C8—C91.372 (4)
N1—C151.265 (3)C8—H80.9300
N1—C11.479 (4)C9—C101.387 (4)
N2—C61.340 (3)C9—H90.9300
N2—C71.384 (3)C10—C111.384 (4)
N2—H2N0.88 (3)C10—H100.9300
C1—C181.532 (6)C11—C121.401 (3)
C1—C191.534 (5)C11—H110.9300
C1—C21.549 (4)C12—C131.447 (3)
C2—C31.509 (4)C13—C141.442 (3)
C2—C171.522 (5)C14—C151.525 (3)
C2—H20.9800C16—C171.529 (6)
C3—C41.525 (4)C16—H16A0.9700
C4—C51.492 (4)C17—H17B0.9700
C4—C151.503 (4)C18—H18A0.9600
C5—C201.327 (5)C18—H18C0.9600
C5—C161.496 (5)C19—H19A0.9600
C6—C131.384 (3)C19—H19B0.9600
C7—C81.392 (3)C20—H20A0.9300
C7—C121.399 (3)C20—H20B0.9300
C15—N1—C1121.8 (3)C11—C10—H10119.4
C6—N2—C7109.63 (19)C9—C10—H10119.4
C6—N2—H2N123.4 (18)C10—C11—C12118.8 (2)
C7—N2—H2N126.7 (18)C10—C11—H11120.6
N1—C1—C18105.8 (3)C12—C11—H11120.6
N1—C1—C19105.3 (3)C7—C12—C11118.3 (2)
C18—C1—C19108.8 (4)C7—C12—C13107.15 (18)
N1—C1—C2113.9 (2)C11—C12—C13134.5 (2)
C18—C1—C2110.6 (3)C6—C13—C14128.4 (2)
C19—C1—C2112.0 (3)C6—C13—C12105.38 (19)
C3—C2—C17107.7 (3)C14—C13—C12126.19 (18)
C3—C2—C1108.0 (3)O1—C14—C13120.8 (2)
C17—C2—C1118.5 (3)O1—C14—C15117.59 (19)
C3—C2—H2107.4C13—C14—C15121.64 (18)
C17—C2—H2107.4N1—C15—C4125.5 (2)
C1—C2—H2107.4N1—C15—C14118.2 (2)
C2—C3—C4107.8 (2)C4—C15—C14116.26 (19)
C2—C3—H3A110.2C5—C16—C17112.1 (3)
C5—C4—C15110.2 (2)H16A—C16—H16B107.9
C5—C4—C3109.6 (3)C2—C17—C16113.3 (3)
C15—C4—C3108.8 (2)C2—C17—H17A108.9
C20—C5—C4122.1 (4)H17A—C17—H17B107.7
C20—C5—C16125.3 (4)C1—C18—H18A109.5
C4—C5—C16112.5 (3)C1—C18—H18B109.5
N2—C6—C13110.5 (2)H18A—C18—H18B109.5
N2—C7—C8129.7 (2)H18B—C18—H18C109.5
N2—C7—C12107.3 (2)C1—C19—H19A109.5
C8—C7—C12123.0 (2)C1—C19—H19B109.5
C9—C8—C7117.2 (2)H19A—C19—H19B109.5
C8—C9—C10121.4 (3)H19B—C19—H19C109.5
C11—C10—C9121.3 (2)H20A—C20—H20B120.0
C15—N1—C1—C18112.2 (3)C8—C7—C12—C13178.5 (2)
C15—N1—C1—C19132.6 (4)C10—C11—C12—C70.0 (4)
C15—N1—C1—C29.5 (4)C10—C11—C12—C13177.5 (3)
N1—C1—C2—C342.3 (4)N2—C6—C13—C14177.6 (2)
C18—C1—C2—C376.7 (3)N2—C6—C13—C120.4 (3)
C19—C1—C2—C3161.7 (3)C7—C12—C13—C60.1 (2)
N1—C1—C2—C1780.4 (4)C11—C12—C13—C6177.8 (3)
C18—C1—C2—C17160.5 (3)C7—C12—C13—C14177.2 (2)
C19—C1—C2—C1739.0 (4)C11—C12—C13—C140.5 (4)
C17—C2—C3—C463.7 (3)C6—C13—C14—O1178.3 (2)
C1—C2—C3—C465.4 (3)C12—C13—C14—O11.7 (3)
C2—C3—C4—C565.5 (3)C6—C13—C14—C150.2 (4)
C2—C3—C4—C1555.1 (3)C12—C13—C14—C15176.5 (2)
C15—C4—C5—C20118.3 (4)C1—N1—C15—C40.4 (4)
C3—C4—C5—C20121.9 (4)C1—N1—C15—C14179.1 (2)
C15—C4—C5—C1662.3 (3)C5—C4—C15—N197.4 (3)
C3—C4—C5—C1657.5 (4)C3—C4—C15—N122.9 (4)
C7—N2—C6—C130.7 (3)C5—C4—C15—C1482.2 (3)
C6—N2—C7—C8178.2 (3)C3—C4—C15—C14157.5 (2)
C6—N2—C7—C120.8 (3)O1—C14—C15—N1161.6 (2)
N2—C7—C8—C9177.9 (3)C13—C14—C15—N120.2 (3)
C12—C7—C8—C90.9 (4)O1—C14—C15—C418.8 (3)
C7—C8—C9—C101.0 (5)C13—C14—C15—C4159.5 (2)
C8—C9—C10—C110.7 (5)C20—C5—C16—C17131.1 (4)
C9—C10—C11—C120.2 (5)C4—C5—C16—C1748.3 (4)
N2—C7—C12—C11178.6 (2)C3—C2—C17—C1656.1 (4)
C8—C7—C12—C110.4 (3)C1—C2—C17—C1666.7 (5)
N2—C7—C12—C130.5 (2)C5—C16—C17—C248.2 (5)

Experimental details

Crystal data
Chemical formulaC20H22N2O
Crystal system, space groupOrthorhombic, P212121
Temperature (K)295
a, b, c (Å)9.7841 (5), 12.3479 (7), 13.8639 (5)
V3)1674.95 (14)
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.32 × 0.18 × 0.10
Data collection
DiffractometerOxford Gemini S Ultra CCD area-detector
Absorption correctionMulti-scan
(CrysAlis PRO; Oxford Diffraction, 2009)
Tmin, Tmax0.98, 0.99
No. of measured, independent and
observed [I > 2σ(I)] reflections
4670, 3411, 2453
(sin θ/λ)max1)0.679
R[F2 > 2σ(F2)], wR(F2), S 0.054, 0.140, 1.02
No. of reflections3411
No. of parameters214
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.15, 0.16

Computer programs: CrysAlis PRO (Oxford Diffraction, 2009), SHELXS97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Comparison of selected torsion angles (°) top
Torsion angle(Ia)(II)
C6—C13—C14—C15-3.6 (7)0.2 (4)
C13—C14—C15N1-47.8 (6)-20.2 (3)
O1C14—C15N1130.0 (7)161.6 (2)
Comparison of hydrogen-bond geometries for (II) and (Ia) (Å, °) top
(II)C6—H6···N10.932.312.851 (4)116
C4—H4···O10.982.442.803 (3)109
C11—H11···O10.932.593.086 (3)114
N2—H2N···O1i0.88 (3)2.03 (3)2.852 (2)154 (3)
(Ia)C6—H6···N10.932.522.966 (6)109
N2—H2N···O1ii0.882.502.968 (6)112
Symmetry codes: (i) 3/2 - x, -y, -1/2 + z; (ii) x + 1, y, z.
Spectroscopic characterization of (II) by 1H NMR (CD3OD, 600 MHz) and 13C NMR (CD3OD, 150 MHz) (For site codes (atom labels), see Fig. 1) top
SiteH (p.p.m.)C (p.p.m.)SiteH (p.p.m.)C (p.p.m.)
160.3118.28 (m)123.0
21.90 (t), 1.8937.212127.5
32.22 (m), 2.08 (m)29.913115.4
43.76 (s)42.514190.3
68.07 (s)138.3161.64 (m), 2.08 (m)29.5
7138.4171.77 (m), 2.20 (m)30.2
87.46 (m)112.8181.5227.3
97.26 (m)124.6191.3231.3
107.25 (m)123.6204.75 (d), 1.7, 4.70 (d), 1.7110.5

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