Crystal structure of 1,1′-[imidazolidine-1,3-diylbis(methyl­ene)]bis­(naphthalen-2-ol)

Rivera, A.; Rojas, J.J.; Ríos-Motta, J.; Bolte, M.

doi:10.1107/S2056989015002078

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Volume 71| Part 3| March 2015| Pages 258-260

doi:10.1107/S2056989015002078

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Crystal structure of 1,1′-[imidazolidine-1,3-diylbis(methylene)]bis(naphthalen-2-ol)

Augusto Rivera,^a ^* Jicli José Rojas,^a Jaime Ríos-Motta ^a and Michael Bolte ^b

^aDepartamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Sede Bogotá, Cra 30 No. 45-03, Bogotá, Colombia, and ^bInstitut für Anorganische Chemie, Goethe-Universität, Max-von-Laue-Strasse 7, Frankfurt/Main D-60438, Germany
^*Correspondence e-mail: ariverau@unal.edu.co

Edited by J. Simpson, University of Otago, New Zealand (Received 24 January 2015; accepted 30 January 2015; online 7 February 2015)

The crystal structure of the title compound, C₂₅H₂₄N₂O₂, at 173 K has monoclinic (C2/c) symmetry. The molecule is located on a crystallographic twofold rotation axis with only half a molecule in the asymmetric unit. The imidazolidine ring adopts a twist conformation, with a twist about the ring C—C bond. The crystal structure shows the anticlinal disposition of the two (2-hydroxynaphthalen-1-yl)methyl substituents of the imidazolidine ring. The structure displays two intramolecular O—H⋯N hydrogen bonds, each forming an S(6) ring motif.

Keywords: crystal structure; imadazolidine; (2-hydroxynaphthalen-1-yl)methyl; hydrogen bonding.

CCDC reference: 1046536

1. Chemical context

We have been interested in the synthesis and characterization of a family of symmetrical N,N′-disubstituted imidazolidines by the use of a Mannich-type condensation of cyclic cage aminals with phenols in a one-pot reaction. The main structural feature of the symmetrical N,N′-disubstituted imidazolidines, the so-called aromatic di-Mannich bases, is to form intramolecular hydrogen bonds that reveal great structural and thermodynamic stability. These di-Mannich bases which contain a phenolic or naphtholic hydroxyl group as a proton donor, as well as an ortho-aminomethyl group as a proton acceptor in the same molecule are convenient models for studying the nature of hydrogen bonding and other weak non-covalent interactions (Koll et al., 2006 ).

In previous studies (Rivera et al., 2006 ), 1,1′-[imidazolidine-1,3-diylbis(methylene)]bis(naphthalen-2-ol), (I), was obtained in good yields by an one-pot Mannich-type reaction involving 1,3,6,8-tetraazatricyclo[4.4.1.1^3,8]dodecane (TATD) and naphthalen-2-ol in classical solvents for Mannich reactions, such as dioxane or ethanol. Intriguingly, reactions of 1,3,6,8-tetraazatricyclo[4.4.1.1^3,8]dodecane (TATD) with naphthalen-2-ol may lead to other results. It has been found (Rivera & Quevedo, 2013 ) that interaction of TATD with naphthalen-2-ol in solvent-free conditions by heating in an oil bath a 1:4 mixture with stirring at 423 K for 20 min gives 1,1′-methylenebis(naphthalen-2-ol) in good yields. On the other hand, the reactions of TATD with naphthalen-2-ol under solvent-free microwave-assisted conditions yields the title compound and no formation of 1,1′-methylenebis(naphthalen-2-ol) was observed. In contrast to classical Mannich reaction conditions this reaction required neither solvent nor inert atmosphere conditions.

2. Structural commentary

In contrast to the closely related structure (Rivera et al., 2012a ), which crystallized in the monoclinic P2₁/n space group, the title compound crystallizes in the C2/c space group. The molecular structure is shown in Fig. 1. The asymmetric unit contains one half molecule and the whole molecule is generated by twofold rotational symmetry (see Fig. 1). The near planarity of the fused aromatic ring system is illustrated by the very small deviation of all the atoms from the plane [largest deviation = 0.0227 (17) Å for atom C11]. The imidazolidine ring (C1/N1/C2/C2′/N1′) is in a twisted conformation on C2—C2′, with puckering parameters Q(2) = 0.4126 (17) Å and φ(2) = 126.0 (2)° (Cremer & Pople, 1975 ). The crystal structure shows the anticlinal disposition of the two (2-hydroxynaphthalen-1-yl)methyl substituents of the imidazolidine ring [pseudo-torsion angle CH₂—N⋯N—CH₂ = −121.77 (18)°]. The mean plane of the imidazolidine ring, defined by atoms N1, C1 and N1′, makes a dihedral angle of 70.92 (4)° with the pendant aromatic rings (C11–C20). The dihedral angle between the planes of the naphthyl rings is 60.55 (4)°.

Figure 1
The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. Hydrogen bonds are drawn as dashed lines. Atoms labelled with the suffix `A' are generated using the symmetry operator (−x + 1, y, −z + $[{1\over 2}]$ ).

As with related structures in this series, the molecular conformation is stabilized by two intramolecular O—H⋯N hydrogen-bond interactions with S(6) graph-set motifs (Bernstein et al., 1995 ). Due to symmetry and contrary to other structures, where hydrogen-bond distances were different, the two observed intramolecular hydrogen-bond distances were identical (Table 1).

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯N1	1.05 (2)	1.65 (2)	2.6143 (19)	151.0 (19)
C2—H2A⋯O1ⁱ	0.99	2.64	3.257 (2)	121
Symmetry code: (i) $[x, -y+2, z-{\script{1\over 2}}]$ .

3. Supramolecular features

Unlike the situation found in related structures, there is only one significant intermolecular interaction involving the O—H group (as acceptor) and a methylene-H atom (as donor) to consolidate the crystal packing. These weak interactions led to the formation of parallel sets of zigzag chains extending along the c axis of the crystal (Fig. 2).

Figure 2
The crystal packing of the title compound, howing one of the zigzag chains that extend along the crystal c-axis direction. Hydrogen bonds are drawn as dashed lines.

4. Database survey

A search in the Cambridge Structural Database (Groom & Allen, 2014 ) for the fragment 2,2′-[imidazolidine-1,3-diylbis(methylene)]diphenol yielded seven hits, namely 2,2′-[imidazolidine-1,3-diylbis(methylene)]bis(4-tert-butylphenol) (Rivera, Nerio & Bolte, 2013 ), 2,2′-[imidazolidine-1,3-diylbis(methylene)]bis(4-chlorophenol) (Rivera et al., 2011 ), 2,2′-[imidazolidine-1,3-diylbis(methylene)]bis[4-(2,4,4-trimethylpentan-2-yl)phenol] (Kober et al., 2012 ), 4,4′-difluoro-2,2′-[imidazolidine-1,3-diylbis(methylene)]diphenol (Rivera et al., 2012b ) 2,2′-[imidazolidine-1,3-diylbis(methylene)]bis(6-methylphenol) (Rivera et al., 2014 ), 2,2′-[imidazolidine-1,3-diylbis(methylene)]diphenol (Rivera et al., 2012b) and 4,4′-dimethyl-2,2′-[imidazolidine-1,3-diylbis(methylene)]diphenol (Rivera et al., 2012c ). In all of these compounds, the hydroxy groups in the ortho position of the aromatic ring form an intramolecular hydrogen bond to an N atom of the imidazoline ring.

5. Synthesis and crystallization

The title compound has been synthesized in solution according to a literature procedure (Rivera et al., 2006); however, in this instance, the synthesis was carried out under microwave-assisted solvent free conditions. A mixture of 1 mmol of 1,3,6,8-tetraazatricyclo[4.4.1.1^3,8]dodecane (TATD) and 2 mmol of naphthalen-2-ol was subjected to microwave irradiation (200 W) for 10 min at a temperature of 373 K. The product was washed with water and then with benzene (yield 94%, m.p. 435–436 K). Crystals suitable for X-ray diffraction were obtained from a methanol solution upon slow evaporation of the solvent at room temperature.

6. Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 2. All H atoms were located in the difference electron-density map. The hydroxy H atom was refined freely, while C-bound H atoms were fixed geometrically (C—H = 0.95 or 0.99 Å) and refined using a riding model, with U_iso(H) values set at 1.2U_eq of the parent atom.

Table 2
Experimental details

Crystal data
Chemical formula	C₂₅H₂₄N₂O₂
M_r	384.46
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	173
a, b, c (Å)	34.883 (5), 8.3956 (9), 6.5830 (8)
β (°)	95.650 (11)
V (Å³)	1918.6 (4)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.09
Crystal size (mm)	0.19 × 0.17 × 0.11

Data collection
Diffractometer	Stoe IPDS II two circle
Absorption correction	Multi-scan (X-AREA; Stoe & Cie, 2001 )
T_min, T_max	0.972, 0.989
No. of measured, independent and observed [I > 2σ(I)] reflections	8297, 1852, 1451
R_int	0.090
(sin θ/λ)_max (Å⁻¹)	0.616

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.055, 0.159, 1.09
No. of reflections	1852
No. of parameters	136
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.24, −0.23
Computer programs: X-AREA (Stoe & Cie, 2001), SHELXS97 and XP (Sheldrick, 2008 ), SHELXL2014 (Sheldrick, 2015 ) and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 1046536

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: 10.1107/S2056989015002078/sj5441sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S2056989015002078/sj5441Isup2.hkl

Supporting information file. DOI: 10.1107/S2056989015002078/sj5441Isup3.cml

checkCIF report

Chemical context top

We have been interested in the synthesis and characterization of a family of symmetrical N,N'-disubstituted imidazolidines by the use of a Mannich-type condensation of cyclic cage aminals with phenols in a one-pot reaction. The main structural feature of the symmetrical N,N'-disubstituted imidazolidines, the so-called aromatic di-Mannich bases, is to form intramolecular hydrogen bonds that reveal great structural and thermodynamic stability. These di-Mannich bases which contain a phenolic or naphtholic hydroxyl group as a proton donor, as well as an ortho-aminomethyl group as a proton acceptor in the same molecule are convenient models for studying the nature of hydrogen bonding and other weak noncovalent interactions (Koll et al., 2006). In previous studies (Rivera et al., 2006), 1,1'-[imidazolidine-1,3-diylbis(methylene)]bis(naphthalen-2-ol), (I), was obtained in good yields by an one-pot Mannich-type reaction involving 1,3,6,8-tetraazatricyclo[4.4.1.1^3,8]dodecane (TATD) and naphthalen-2-ol in classical solvents for Mannich reactions, such as dioxane or ethanol. Intriguingly, reactions of 1,3,6,8-tetraazatricyclo[4.4.1.1^3,8]dodecane (TATD) with naphthalen-2-ol may lead to other results. It has been found (Rivera & Quevedo, 2013) that interaction of TATD with naphthalen-2-ol in solvent-free conditions by heating in an oil bath a 1:4 mixture with stirring at 423 K for 20 min gives 1,1'-methylenebis(naphthalen-2-ol) in good yields. On the other hand, the reactions of TATD with naphthalen-2-ol under solvent-free microwave-assisted conditions yields the title compound and no formation of 1,1'-methylenebis(naphthalen-2-ol) was observed. In contrast to classical Mannich reaction conditions this reaction required neither solvent nor inert atmosphere conditions.

Structural commentary top

In contrast to the closely related structure (Rivera et al., 2012a), which crystallized in the monoclinic P2₁/n space group, the title compound crystallizes in the C2/c space group. The molecular structure is shown in Fig. 1. The asymmetric unit contains one half molecule and the whole molecule is generated by twofold rotational symmetry (see Fig. 1). The planarity of the aromatic ring is illustrated by the very small deviation of all the atoms from the plane [largest deviation = 0.0227 (17) Å for atom C11]. The imidazolidine ring (C1/N1/C2/C2'/N1') is in a twisted conformation on C2—C2', with puckering parameters Q(2) = 0.4126 (17) Å and ϕ(2) = 126.0 (2)° (Cremer & Pople, 1975). The crystal structure shows the anticlinal disposition of the two (2-hydroxynaphthalen-1-yl)methyl substituents of the imidazolidine ring [pseudo-torsion angle CH₂—N···N—CH₂ = -121.77 (18)°]. The mean plane of the imidazolidine ring, defined by atoms N1, C1 and N1', makes a dihedral angle of 70.92 (4)° with the pendant aromatic rings (C11–C20). The dihedral angle between the planes of the naphthyl rings is 60.55 (4)°.

As with related structures in this series, the molecular conformation is stabilized by two intramolecular O—H···N hydrogen-bond interactions with S(6) graph-set motifs (Bernstein et al., 1995). Due to symmetry and contrary to other structures, where hydrogen-bond distances were different, the two observed intramolecular hydrogen-bond distances were identical (Table 1).

Supramolecular features top

Unlike the situation found in related structures, there is only one significant intermolecular interaction involving the O—H group and a methylene H atom to consolidate the crystal packing. These weak interactions led to the formation of parallel sets of zigzag chains extending along the c axis of the crystal (Fig. 2).

Database survey top

A search in the Cambridge Structural Database (Groom & Allen, 2014) for the fragment 2,2'-[imidazolidine-1,3-diylbis(methylene)]diphenol yielded seven hits, namely 2,2'-[imidazolidine-1,3-diylbis(methylene)]bis(4-tert-butylphenol) (Rivera, Nerio & Bolte, 2013), 2,2'-[imidazolidine-1,3-diylbis(methylene)]bis(4-chlorophenol) (Rivera et al., 2011), 2,2'-[imidazolidine-1,3-diylbis(methylene)]bis[4-(2,4,4-trimethylpentan-2-yl)phenol] (Kober et al., 2012), 4,4'-difluoro-2,2'-[imidazolidine-1,3-diylbis(methylene)]diphenol (Rivera et al., 2012b) 2,2'-[imidazolidine-1,3-diylbis(methylene)]bis(6-methylphenol) (Rivera et al., 2014), 2,2'-[imidazolidine-1,3-diylbis(methylene)]diphenol (Rivera et al., 2012b) and 4,4'-dimethyl-2,2'-[imidazolidine-1,3-diylbis(methylene)]diphenol, (Rivera et al., 2012c). In all of these, the hydroxy groups in the ortho position of the aromatic ring form an intramolecular hydrogen bond to an N atom of the imidazoline ring.

Synthesis and crystallization top

The title compound has been synthesized in solution according to a literature procedure (Rivera et al., 2006); however, in this instance, the synthesis was carried out under microwave-assisted solvent free conditions. A mixture of 1 mmol of 1,3,6,8-tetraazatricyclo[4.4.1.1^3,8]dodecane (TATD) and 2 mmol of naphthalen-2-ol was subjected to microwave irradiation (200 W) for 10 min at a temperature of 373 K. The product was washed with water and benzene (yield 94%, m.p. 435–436 K). Crystals suitable for X-ray diffraction were obtained from MeOH upon slow evaporation of the solvent at room temperature.

Refinement details top

Crystal data, data collection and structure refinement details are summarized in Table 1. All H atoms were located in the difference electron-density map. The hydroxy H atom was refined freely, while C-bound H atoms were fixed geometrically (C—H = 0.95 or 0.99 Å) and refined using a riding-model approximation, with U_iso(H) values set at 1.2U_eq of the parent atom.

Computing details top

Data collection: X-AREA (Stoe & Cie, 2001); cell refinement: X-AREA (Stoe & Cie, 2001); data reduction: X-AREA (Stoe & Cie, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: XP (Sheldrick, 2008); software used to prepare material for publication: SHELXL2014 (Sheldrick, 2015) and publCIF (Westrip, 2010).

Figures top

	Fig. 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level. Hydrogen bonds are drawn as dashed lines. Atoms labelled with the suffix `a' are generated using the symmetry operator (-x+1, y, -z+1/2).
	Fig. 2. The crystal packing of the title compound , howing one of the zigzag chains that extend along the crystal c-axis direction. Hydrogen bonds are drawn as dashed lines.

1-({3-[(2-Hydroxynaphthalen-1-yl)methyl]imidazolidin-1-yl}methyl)naphthalen-2-ol top

Crystal data top

C₂₅H₂₄N₂O₂	F(000) = 816
M_r = 384.46	D_x = 1.331 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 34.883 (5) Å	Cell parameters from 8026 reflections
b = 8.3956 (9) Å	θ = 2.4–26.2°
c = 6.5830 (8) Å	µ = 0.09 mm⁻¹
β = 95.650 (11)°	T = 173 K
V = 1918.6 (4) Å³	Block, colourless
Z = 4	0.19 × 0.17 × 0.11 mm

Data collection top

Stoe IPDS II two-circle diffractometer	1451 reflections with I > 2σ(I)
ω scans	R_int = 0.090
Absorption correction: multi-scan X-AREA (Stoe & Cie, 2001)	θ_max = 26.0°, θ_min = 2.5°
T_min = 0.972, T_max = 0.989	h = −42→34
8297 measured reflections	k = −10→10
1852 independent reflections	l = −8→8

Refinement top

Refinement on F²	0 restraints
Least-squares matrix: full	Hydrogen site location: mixed
R[F² > 2σ(F²)] = 0.055	H atoms treated by a mixture of independent and constrained refinement
wR(F²) = 0.159	w = 1/[σ²(F_o²) + (0.085P)² + 0.4089P] where P = (F_o² + 2F_c²)/3
S = 1.09	(Δ/σ)_max < 0.001
1852 reflections	Δρ_max = 0.24 e Å⁻³
136 parameters	Δρ_min = −0.23 e Å⁻³

Crystal data top

C₂₅H₂₄N₂O₂	V = 1918.6 (4) Å³
M_r = 384.46	Z = 4
Monoclinic, C2/c	Mo Kα radiation
a = 34.883 (5) Å	µ = 0.09 mm⁻¹
b = 8.3956 (9) Å	T = 173 K
c = 6.5830 (8) Å	0.19 × 0.17 × 0.11 mm
β = 95.650 (11)°

Data collection top

Stoe IPDS II two-circle diffractometer	1852 independent reflections
Absorption correction: multi-scan X-AREA (Stoe & Cie, 2001)	1451 reflections with I > 2σ(I)
T_min = 0.972, T_max = 0.989	R_int = 0.090
8297 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.055	0 restraints
wR(F²) = 0.159	H atoms treated by a mixture of independent and constrained refinement
S = 1.09	Δρ_max = 0.24 e Å⁻³
1852 reflections	Δρ_min = −0.23 e Å⁻³
136 parameters

Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
O1	0.45368 (4)	0.77294 (16)	0.70176 (19)	0.0507 (4)
H1	0.4677 (6)	0.723 (3)	0.583 (4)	0.061 (6)*
N1	0.47179 (4)	0.69601 (18)	0.3384 (2)	0.0455 (4)
C1	0.5000	0.5948 (4)	0.2500	0.0627 (8)
H1A	0.5132	0.5258	0.3570	0.075*	0.5
H1B	0.4868	0.5258	0.1430	0.075*	0.5
C2	0.47856 (5)	0.8543 (2)	0.2548 (2)	0.0488 (5)
H2A	0.4707	0.9396	0.3459	0.059*
H2B	0.4646	0.8678	0.1175	0.059*
C3	0.43203 (5)	0.6374 (2)	0.2997 (3)	0.0491 (5)
H3A	0.4319	0.5212	0.3249	0.059*
H3B	0.4231	0.6549	0.1540	0.059*
C11	0.40403 (5)	0.7157 (2)	0.4287 (2)	0.0437 (4)
C12	0.41619 (5)	0.7796 (2)	0.6188 (2)	0.0446 (4)
C13	0.38994 (6)	0.8541 (2)	0.7379 (3)	0.0511 (5)
H13	0.3990	0.8993	0.8660	0.061*
C14	0.35197 (6)	0.8623 (2)	0.6724 (3)	0.0541 (5)
H14	0.3348	0.9149	0.7536	0.065*
C15	0.33758 (5)	0.7931 (2)	0.4833 (3)	0.0499 (5)
C16	0.29795 (6)	0.7964 (3)	0.4150 (3)	0.0611 (6)
H16	0.2805	0.8489	0.4948	0.073*
C17	0.28426 (6)	0.7252 (3)	0.2355 (3)	0.0682 (6)
H17	0.2575	0.7286	0.1910	0.082*
C18	0.30975 (6)	0.6476 (3)	0.1178 (3)	0.0662 (6)
H18	0.3001	0.5965	−0.0055	0.079*
C19	0.34828 (6)	0.6438 (3)	0.1770 (3)	0.0545 (5)
H19	0.3650	0.5908	0.0938	0.065*
C20	0.36387 (5)	0.7181 (2)	0.3618 (2)	0.0455 (5)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0588 (8)	0.0562 (8)	0.0367 (6)	−0.0007 (6)	0.0024 (5)	−0.0039 (5)
N1	0.0551 (9)	0.0469 (8)	0.0350 (7)	0.0057 (6)	0.0072 (6)	−0.0001 (6)
C1	0.0688 (18)	0.0559 (17)	0.0670 (17)	0.000	0.0256 (14)	0.000
C2	0.0617 (11)	0.0505 (11)	0.0342 (8)	0.0027 (8)	0.0047 (7)	0.0023 (7)
C3	0.0615 (12)	0.0496 (10)	0.0364 (8)	−0.0001 (8)	0.0061 (7)	−0.0058 (7)
C11	0.0590 (11)	0.0412 (9)	0.0318 (8)	0.0009 (8)	0.0086 (7)	0.0016 (6)
C12	0.0574 (11)	0.0438 (10)	0.0331 (8)	−0.0026 (7)	0.0067 (7)	0.0024 (6)
C13	0.0676 (12)	0.0525 (11)	0.0342 (8)	−0.0042 (9)	0.0098 (8)	−0.0063 (7)
C14	0.0667 (12)	0.0548 (11)	0.0436 (9)	0.0030 (9)	0.0192 (8)	−0.0039 (8)
C15	0.0570 (11)	0.0539 (11)	0.0399 (9)	−0.0012 (8)	0.0107 (7)	0.0054 (7)
C16	0.0597 (12)	0.0746 (14)	0.0508 (11)	0.0032 (10)	0.0141 (9)	0.0079 (9)
C17	0.0549 (12)	0.0951 (18)	0.0539 (12)	−0.0018 (11)	0.0020 (9)	0.0091 (11)
C18	0.0678 (14)	0.0890 (16)	0.0409 (10)	−0.0065 (12)	0.0010 (9)	0.0002 (10)
C19	0.0614 (12)	0.0646 (12)	0.0376 (9)	−0.0022 (9)	0.0055 (8)	−0.0020 (8)
C20	0.0602 (11)	0.0455 (10)	0.0316 (8)	−0.0021 (8)	0.0082 (7)	0.0036 (6)

Geometric parameters (Å, º) top

O1—C12	1.368 (2)	C12—C13	1.409 (3)
O1—H1	1.05 (2)	C13—C14	1.354 (3)
N1—C1	1.464 (2)	C13—H13	0.9500
N1—C2	1.467 (2)	C14—C15	1.420 (3)
N1—C3	1.470 (2)	C14—H14	0.9500
C1—N1ⁱ	1.464 (2)	C15—C16	1.411 (3)
C1—H1A	0.9900	C15—C20	1.422 (3)
C1—H1B	0.9900	C16—C17	1.368 (3)
C2—C2ⁱ	1.503 (4)	C16—H16	0.9500
C2—H2A	0.9900	C17—C18	1.397 (3)
C2—H2B	0.9900	C17—H17	0.9500
C3—C11	1.507 (2)	C18—C19	1.362 (3)
C3—H3A	0.9900	C18—H18	0.9500
C3—H3B	0.9900	C19—C20	1.427 (2)
C11—C12	1.389 (2)	C19—H19	0.9500
C11—C20	1.427 (3)

C12—O1—H1	102.4 (12)	O1—C12—C13	116.36 (15)
C1—N1—C2	103.73 (15)	C11—C12—C13	121.01 (17)
C1—N1—C3	113.36 (14)	C14—C13—C12	120.94 (16)
C2—N1—C3	114.98 (14)	C14—C13—H13	119.5
N1ⁱ—C1—N1	109.0 (2)	C12—C13—H13	119.5
N1ⁱ—C1—H1A	109.9	C13—C14—C15	120.60 (17)
N1—C1—H1A	109.9	C13—C14—H14	119.7
N1ⁱ—C1—H1B	109.9	C15—C14—H14	119.7
N1—C1—H1B	109.9	C16—C15—C14	121.46 (18)
H1A—C1—H1B	108.3	C16—C15—C20	119.72 (18)
N1—C2—C2ⁱ	102.34 (10)	C14—C15—C20	118.82 (18)
N1—C2—H2A	111.3	C17—C16—C15	120.9 (2)
C2ⁱ—C2—H2A	111.3	C17—C16—H16	119.5
N1—C2—H2B	111.3	C15—C16—H16	119.5
C2ⁱ—C2—H2B	111.3	C16—C17—C18	119.7 (2)
H2A—C2—H2B	109.2	C16—C17—H17	120.1
N1—C3—C11	114.13 (14)	C18—C17—H17	120.1
N1—C3—H3A	108.7	C19—C18—C17	121.1 (2)
C11—C3—H3A	108.7	C19—C18—H18	119.5
N1—C3—H3B	108.7	C17—C18—H18	119.5
C11—C3—H3B	108.7	C18—C19—C20	121.08 (19)
H3A—C3—H3B	107.6	C18—C19—H19	119.5
C12—C11—C20	118.43 (16)	C20—C19—H19	119.5
C12—C11—C3	121.27 (17)	C15—C20—C11	120.07 (16)
C20—C11—C3	120.22 (15)	C15—C20—C19	117.41 (18)
O1—C12—C11	122.62 (16)	C11—C20—C19	122.50 (17)

C2—N1—C1—N1ⁱ	13.70 (8)	C13—C14—C15—C20	−1.4 (3)
C3—N1—C1—N1ⁱ	139.08 (14)	C14—C15—C16—C17	−178.1 (2)
C1—N1—C2—C2ⁱ	−34.89 (17)	C20—C15—C16—C17	1.6 (3)
C3—N1—C2—C2ⁱ	−159.24 (14)	C15—C16—C17—C18	0.2 (4)
C1—N1—C3—C11	166.25 (14)	C16—C17—C18—C19	−1.2 (4)
C2—N1—C3—C11	−74.64 (18)	C17—C18—C19—C20	0.4 (3)
N1—C3—C11—C12	−26.7 (2)	C16—C15—C20—C11	179.33 (16)
N1—C3—C11—C20	156.64 (15)	C14—C15—C20—C11	−1.0 (3)
C20—C11—C12—O1	175.45 (15)	C16—C15—C20—C19	−2.2 (3)
C3—C11—C12—O1	−1.3 (3)	C14—C15—C20—C19	177.39 (17)
C20—C11—C12—C13	−3.9 (3)	C12—C11—C20—C15	3.6 (3)
C3—C11—C12—C13	179.33 (16)	C3—C11—C20—C15	−179.57 (16)
O1—C12—C13—C14	−177.87 (16)	C12—C11—C20—C19	−174.69 (17)
C11—C12—C13—C14	1.5 (3)	C3—C11—C20—C19	2.1 (3)
C12—C13—C14—C15	1.2 (3)	C18—C19—C20—C15	1.3 (3)
C13—C14—C15—C16	178.20 (18)	C18—C19—C20—C11	179.66 (18)

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N1	1.05 (2)	1.65 (2)	2.6143 (19)	151.0 (19)
C2—H2A···O1ⁱⁱ	0.99	2.64	3.257 (2)	121

Symmetry code: (ii) x, −y+2, z−1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···N1	1.05 (2)	1.65 (2)	2.6143 (19)	151.0 (19)
C2—H2A···O1ⁱ	0.99	2.64	3.257 (2)	120.6

Symmetry code: (i) x, −y+2, z−1/2.

Experimental details

Crystal data
Chemical formula	C₂₅H₂₄N₂O₂
M_r	384.46
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	173
a, b, c (Å)	34.883 (5), 8.3956 (9), 6.5830 (8)
β (°)	95.650 (11)
V (Å³)	1918.6 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.19 × 0.17 × 0.11

Data collection
Diffractometer	Stoe IPDS II two-circle diffractometer
Absorption correction	Multi-scan X-AREA (Stoe & Cie, 2001)
T_min, T_max	0.972, 0.989
No. of measured, independent and observed [I > 2σ(I)] reflections	8297, 1852, 1451
R_int	0.090
(sin θ/λ)_max (Å⁻¹)	0.616

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.055, 0.159, 1.09
No. of reflections	1852
No. of parameters	136
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.24, −0.23

Computer programs: X-AREA (Stoe & Cie, 2001), SHELXS97 (Sheldrick, 2008), XP (Sheldrick, 2008), SHELXL2014 (Sheldrick, 2015) and publCIF (Westrip, 2010).

Acknowledgements

We acknowledge the financial support provided to us by the Dirección de Investigación, Sede Bogotá (DIB) at the Universidad Nacional de Colombia through the research project No. 19151 (Code QUIPU 201010020518). JJR thanks COLCIENCIAS for a fellowship.

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