The zwitterion of 4-nitro-2-{(E)-[2-(piperidin-1-yl)eth­yl]imino­meth­yl}­phenol

Santos-Contreras, R.J.; Ramos-Organillo, A.; García-Báez, E.V.; Padilla-Martínez, I.I.; Martínez-Martínez, F.J.

doi:10.1107/S0108270108040407

organic compounds

STRUCTURAL
CHEMISTRY

ISSN: 2053-2296

Volume 65| Part 1| January 2009| Pages o8-o10

doi:10.1107/S0108270108040407

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The zwitterion of 4-nitro-2-{(E)-[2-(piperidin-1-yl)ethyl]iminomethyl}phenol

Rocio J. Santos-Contreras,^a Angel Ramos-Organillo,^a Efrén V. García-Báez,^b Itzia I. Padilla-Martínez ^b and Francisco J. Martínez-Martínez ^a ^*

^aFacultad de Ciencias Químicas, Universidad de Colima, Carretera Coquimatlán-Colima, Coquimatlán Colima, 28400, Mexico, and ^bUnidad Profesional Interdisciplinaria de Biotecnología, Instituto Politécnico Nacional, Avenida Acueducto s/n, Barrio La Laguna Ticomán, México DF 07340, Mexico
^*Correspondence e-mail: fjmartin@ucol.mx

(Received 11 November 2008; accepted 1 December 2008; online 6 December 2008)

The title Schiff base compound, 4-nitro-1-oxo-2-{(E)-[2-(piperidin-1-yl)ethyl]iminiomethyl}cyclohexadienide, C₁₄H₁₉N₃O₃, exists as a zwitterion, with the H atom of the phenol group being transferred to the imine N atom. The C=O, C_Ar—C_Ar and C—N bond lengths are in agreement with the oxocyclohexadienide–iminium zwitterionic form. The iminium H atom is engaged in a strong intramolecular hydrogen bond with the O atom of the keto group (N⁺—H⋯O) to form an S(6) motif. Soft C—H⋯O interactions in the ac plane lead to the development of hydrogen-bonded tapes, which are π-stacked through the oxocyclohexadienide ring and iminium group. The significance of this study is in providing crystallographic evidence, supported by NMR and IR data, of the predominance of the oxocyclohexadienide–iminium zwitterion form over the noncharged canonical form in the title Schiff base.

Comment

Aromatic imines and their derivatives are an important group of molecules in organic chemistry, in particular those that have aryl groups bound to N or C atoms. They have been used successfully to study resonance-assisted hydrogen bonds (RAHBs; Krygowski & Stepien, 2005 ; Sobczyk et al., 2005 ). Imines substituted in the aromatic ring have offered the opportunity to study the substituent effects in RAHBs. In this context, the molecular structure of the title compound, (I) (Fig. 1), is reported here.

The single-crystal structure of the title Schiff base compound is built up by discrete molecules in the monoclinic space group P2/c, with one molecule in the asymmetric unit. A summary of bond lengths and angles is presented in Table 1. The N8—C7 and O1—C1 bond lengths are in agreement with the double-bond character for the imine (ν at 1601 cm⁻¹) and keto-carbonyl groups (ν at 1657 cm⁻¹), respectively (Allen, 2002 ). Moreover, the bond lengths in the C1–C6 ring show

clear alternation in the delocalized C2–C6 portion. The nitro group is tilted out of the mean plane of the adjacent ring by −11.1 (3)°, whereas the C4—N4 distance is in the characteristic range suggesting limited conjugation with the ring. Thus, the whole geometry is in agreement with the predominace of the oxocyclohexadienide–iminium zwitterion bonding scheme (see scheme

) (Krygowski & Stepien, 2005

), in close agreement with the reported configurations of p-nitrophenolates of alkali metal cations (Butt et al., 1987

The iminium H atom (located in a difference map) is coplanar with the oxocyclohexadienide ring and on the same side of the molecule as the O atom of the keto group, allowing the formation of an intramolecular N—H⋯O hydrogen bond (Table 2) in an S(6) motif (Bernstein et al., 1995 ), with dimensions in agreement with the usual values (Krygowski et al., 1997 ; Steiner 1998 , 2002 ). The N8⋯O1 distance has almost the same value as the RAHB of 2.607 (3) Å found in 3-{[(diphenoxythiophosphoryl)hydrazine]methylidene}-3,4-dihydro-2H-1-benzopyran-2,4-dione (Rybarczyk-Pirek et al., 2002 ). The iminium H atom is also engaged in N—H⋯O hydrogen bonding with the O atom from the keto group of a neighbouring molecule, forming dimers with an almost square R₂²(4) motif (Fig. 2).

The first dimension of the extended structure is built up by soft C—H⋯O interactions with the participation of one of the O atoms from the nitro group, in a monocoordinative fashion (Allen et al., 1997 ), as the acceptor of two hydrogen bonds (Table 2) to form an R₂¹(6) motif. The whole hydrogen-bonding scheme, makes up tapes propagating along the direction of the c axis. All C—H⋯ON and C⋯ON distances are shorter than the mean values of 2.7 (2) and 3.5 (2) Å, respectively, found in a study of nitrobenzenes (André et al., 1997 ), although the C—H⋯ON angles are within the accepted range [C—H⋯O = 133 (20)°]. Even when C—H⋯O interactions involving an NO₂ group as acceptor are half as strong as C—H⋯O interactions (Allen et al., 1997) involving a CO group as the acceptor, they play a significant role in packing owing to their co-operative action.

The second dimension is ruled by the zwitterionic nature of (I). The anionic oxocyclohexadiene ring and the cationic iminium group from neighbouring tapes are overlapped. The iminium N and C atoms are 3.257 (3) and 3.462 (3) Å, respectively, from the centroid of the cyclohexadienide ring at (−x + 1, −y, −z). These short distances strongly suggest not only ion pairing but also a π-stacking interaction between the iminium group, as acceptor, and the oxocyclohexadiene ring, as the donor of electron density (Fig. 3). These π-stacking interactions crosslink pairs of the hydrogen-bonded tapes described above to develop discrete centrosymmetric ribbons which propagate along the c axis.

Figure 1
The molecular structure of (I)

, showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii.

Figure 2
Hydrogen-bonded tapes formed by N—H⋯O and C—H⋯O interactions along the c axis. H atoms not involved in the motifs shown have been omitted for clarity. [Symmetry codes: (i) −x + 1, y, −z + $[{3\over 2}]$ ; (ii) −x + 1, y, −z + $[{1\over 2}]$ .]

Figure 3
The centrosymmetric oxocyclohexadienide–iminium π-stacked pairs of compound (I)

. [Symmetry code: (iii) −x + 1, −y + 1, −z + 1.]

Experimental

Compound (I) was synthesized by amidation of ethyl 6-nitro-2-oxo-2H-chromene-3-carboxylate (0.5 g, 1.9 mmol), prepared according to Santos-Contreras et al. (2007 ), with 1-(2-aminoethyl)piperidine (0.26 ml, 1.9 mmol) and two drops of piperidine as catalyst in refluxing ethanol (10 ml) for 24 h. The resulting orange solution was treated with activated charcoal and evaporated to give 0.3 g of an orange solid in 57% yield. Crystals suitable for X-ray analysis were obtained by slow evaporation from a saturated ethyl acetate solution (m.p. 413 K). IR (cm⁻¹): ν (C=O) 1657, (C=N) 1601, (C—NO) 1535; ¹H NMR (300 MHz, CDCl₃): δ 6.90 (d, H6, ³J = 9.0 Hz), 8.16 (dd, H5, ³J = 9.0 and ⁴J = 3.0 Hz), 8.22 (d, H3, ³J = 9.0 Hz), 11.9 (b, NH), 8.31 (s, H7), 3.74 (t, 2H, ³J = 6.2 Hz, –⁺NHCH₂–), 2.64 (t, 2H, ³J = 6.2 Hz, –CH₂N), 2.46 [m, 4H, N—(CH₂)₂], 1.56 (m, 4H, –CH₂–), 1.46 (m, 2H, –CH₂–); ¹³C NMR: δ 173.1 (C1), 115.6 (C2), 129.7 (C3), 137.5 (C4), 129.0 (C5), 120.9 (C6), 165.3 (C7), 58.4 (C9), 53.2 (C10), 54.8 (C12), 26.2 (C13), 24.3 (C14).

Crystal data

C₁₄H₁₉N₃O₃
M_r = 277.17
Monoclinic, P 2/c
a = 10.5688 (17) Å
b = 12.1887 (19) Å
c = 12.6816 (15) Å
β = 114.696 (10)°
V = 1484.2 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 293 (2) K
0.20 × 0.17 × 0.12 mm

Data collection

Bruker APEXII area-detector diffractometer
13954 measured reflections
2617 independent reflections
2217 reflections with I > 2σ(I)
R_int = 0.039

Refinement

R[F² > 2σ(F²)] = 0.066
wR(F²) = 0.151
S = 1.20
2617 reflections
185 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.21 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

O1—C1	1.257 (3)
O4A—N4	1.227 (3)
O4B—N4	1.230 (3)
N4—C4	1.442 (3)
N8—C7	1.285 (3)
N8—C9	1.454 (3)
N11—C10	1.449 (3)
N11—C12	1.451 (3)
N11—C16	1.455 (3)
C1—C2	1.447 (3)
C1—C6	1.435 (3)
C2—C3	1.395 (3)
C3—C4	1.372 (3)
C4—C5	1.406 (3)
C5—C6	1.357 (3)
C9—C10	1.514 (3)

O4A—N4—O4B	122.9 (2)
O4A—N4—C4	118.4 (2)
O4B—N4—C4	118.7 (2)
C7—N8—C9	123.6 (2)
C10—N11—C12	111.9 (2)
C10—N11—C16	112.7 (2)
C12—N11—C16	109.9 (2)
O1—C1—C6	122.3 (2)
O1—C1—C2	122.0 (2)
N4—C4—C5	119.6 (2)
N4—C4—C3	120.0 (2)
N8—C7—C2	125.0 (2)
N8—C9—C10	111.0 (2)
N11—C10—C9	112.2 (2)
N11—C12—C13	111.1 (3)
N11—C16—C15	110.9 (3)

Table 2
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N8—H8⋯O1	0.90 (2)	2.02 (3)	2.674 (3)	129 (3)
N8—H8⋯O1ⁱ	0.90 (2)	2.13 (3)	2.857 (3)	137 (3)
C3—H3⋯O4Bⁱⁱ	0.93	2.57	3.400 (3)	149
C7—H7⋯O4Bⁱⁱ	0.93	2.44	3.302 (3)	155
Symmetry codes: (i) $[-x+1, y, -z+{\script{3\over 2}}]$ ; (ii) $[-x+1, y, -z+{\script{1\over 2}}]$ .

The amino H atom was located in a difference Fourier map and refined with an N—H distance of 0.90 (2) Å. All other H atoms were positioned geometrically and refined using a riding model [C—H = 0.93 and 0.97 Å for aromatic and CH₂ H atoms, respectively, and U_iso(H) = 1.2U_eq(C)].

Data collection: APEX2 (Bruker, 2004 ); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and Mercury (Macrae et al., 2006 ); software used to prepare material for publication: SHELXL97 and WinGX2003 (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks global, I. DOI: 10.1107/S0108270108040407/gd3261sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S0108270108040407/gd3261Isup2.hkl

Comment top

Aromatic imines and their derivatives, are an important group of molecules in organic chemistry, in particular those that have aryl groups bound to N or C atoms. They have been used successfully to study resonance-assisted hydrogen bonds (RAHBs; Krygowski & Stepien, 2005; Sobczyk et al., 2005). Imines substituted in the aromatic ring have offered the opportunity to study the substituent effects in RAHBs. In this context, the molecular structure of the title compound, (I) (Fig. 1), is reported here.

The single-crystal structure of the title Schiff base compound is built up by discrete C₁₄H₁₉N₃O₃ molecules in the monoclinic space group P2/c, with four molecules in the asymmetric unit. A summary of bond lengths and angles is listed in Table 1. The N8—C7 and O1—C9 (C1?) bond lengths are in agreement with the double-bond character for the imine (ν at 1601 cm^-1) and keto-carbonyl groups (ν at 1657 cm^-1), respectively (Allen, 2002). Moreover, the bond lengths in the ring (C1–C6) show clear alternation in the delocalized portion C2–C6. The nitro group is tilted out of the mean plane of the adjacent ring by -11.1 (3)°, whereas the C4—N4 distance is in the characteristic range, suggesting limited conjugation with the ring. Thus, the whole geometry is in agreement with the predominace of the ketodienide–iminium zwitterion bonding scheme (see scheme) (Krygowski & Stepien, 2005), in close agreement with p-nitrophenolates of alkali metal cations (Butt et al., 1987).

The iminium H atom (located in a difference map) is coplanar with the keto-cyclohexadienide ring and on the same side of the molecule as the O atom from the keto group, allowing the formation of an intramolecular N—H···O hydrogen bond (Table 2) in an S(6) motif (Bernstein et al., 1995), with dimensions in agreement with the accepted values (Krygowski et al., 1997; Steiner 1998, 2002). The N8···O1 distance has almost the same value as the RAHB of 2.607</span><span style=" font-weight:600;">(3) Å found in 3-{[(diphenoxy-thio-phosphoryl)hydrazine]methylidene}-3,4-dihydro-2H-1-benzopyran-2,4-dione (Rybarczyk-Pirek et al., 2002). The iminium H atom is also engaged in N···H···O hydrogen bonding with the O atom from the keto group of a neighbouring molecule, forming dimers with an almost square R²₂(4) motif (Fig. 2).

The first dimension is built up by soft C—H···O interactions with the participation of one of the O atoms from the nitro group, in monocoordinative fashion (Allen et al., 1997), as the acceptor of two H atoms (Table 2) to form an R¹₂(6) motif. The whole hydrogen-bonding scheme, makes up tapes propagating along the direction of the c axis. All C—H···ON and C···ON distances are shorter than the mean values of 2.7 (2) and 3.5 (2) Å found in a study of nitrobenzenes (André et al., 1997), although the C—H···ON angles are within the accepted range [C—H···O = 133 (20)°]. Even when C—H···O interactions involving an NO₂ group as the acceptor are half as strong as C—H···O interactions (Allen et al., 1997) involving a CO group as the acceptor, they play a significant role in packing owing to their cooperative action.

The second dimension is ruled by the switterionic nature of (I). The anionic keto-cyclohexadiene rin and the cationic iminium group from neighboring tapes are overlapped. The iminium N and C atoms are at 3.257 (3) and 3.462 (3) Å, respectively, from the centroid of the cyclohexadienide ring at (-x + 1, -y, -z). These short distances strongly suggest not only ion-pairing but also a π-stacking interaction between the iminium, as the acceptor, and keto-cyclohexadiene ring, as the donor of electronic density developing discrete centrosymmetric ribbons along the b axis (Fig. 3).

Related literature top

For related literature, see: Allen (2002); Bernstein et al. (1995); Butt et al. (1987); Krygowski & Stepien (2005); Krygowski et al. (1997); Rybarczyk-Pirek, Grabowski, Malecka & Nawrot-Modranka (2002); Sobczyk et al. (2005); Steiner (1998, 2002).

Experimental top

Compound (I) was synthesized by amidation of 0.5 g of ethyl-6-nitro-2-oxo-2H-chromene-3-carboxylate (1.9 mmol), prepared according with reported methodology (Santos-Contreras et al., 2007), with 0.26 ml of 1-(2-aminoethyl) piperidine (1.9 mmol) and two drops of piperidine as catalyst in 10 ml of refluxing ethanol for 24 h. The orange solution was treated with activated charcoal and then evaporated to obtain 0.3 g of an orange solid in 57% yield. Crystals suitable for X-ray analysis were obtained by slow evaporation from saturated ethyl acetate solution (m.p. 413 K). IR (cm^-1): ν (C═O) 1657, 1601 (C═N), (C—NO) 1535; ¹H NMR (300 MHz, CDCl₃): δ 6.90 (d, H6, ³J = 9.0 Hz), 8.16 (dd, H5, ³J = 9.0 Hz and ⁴J = 3.0 Hz), 8.22 (d, H3, ³J = 9.0 Hz), 11.9 (b, NH), 8.31 (s, H7), 3.74 (t, 2H, ³J = 6.2 Hz, –⁺NHCH₂–), 2.64 (t, 2H, ³J = 6.2 Hz, –CH₂N), 2.46 (m, 4H, N—(CH₂)₂, 1.56 (m, 4H, –CH₂–), 1.46 (m, 2H, –CH₂–); ¹³C NMR: δ 173.1 (C1), 115.6 (C2), 129.7 (C3), 137.5 (C4), 129.0 (C5), 120.9 (C6), 165.3 (C7), 58.4 (C9), 53.2 (C10), 54.8 (C12), 26.2 (C13), 24.3 (C14).

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and Mercury (Version 1.4.2; Macrae et al., 2006); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and WinGX2003 (Farrugia, 1999).

Figures top

	Fig. 1. The molecular structure of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. Hydrogen-bonded tapes formed by N—H···O and C—H···O interactions along the c axis. H atoms not involved in the motifs shown have been omited for clarity. [Symmetry codes: (i) -x + 1, y, -z + 3/2; (ii) -x + 1, y, -z + 1/2.]
	Fig. 3. Centrosymmetric cyclohexadienide–iminium π-stacked pairs of compound (I). [Symmetry code: (iii) -x + 1, -y, -z.]

4-nitro-1-oxo-2-{(E)-[2-(piperidin-1- yl)ethyl]iminiomethyl}cyclohexadienide top

Crystal data top

C₁₄H₁₉N₃O₃	F(000) = 592
M_r = 277.17	D_x = 1.241 Mg m⁻³
Monoclinic, P2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yc	Cell parameters from 600 reflections
a = 10.5688 (17) Å	θ = 20–25°
b = 12.1887 (19) Å	µ = 0.09 mm⁻¹
c = 12.6816 (15) Å	T = 293 K
β = 114.696 (10)°	Block, colorless
V = 1484.2 (4) Å³	0.20 × 0.17 × 0.12 mm
Z = 4

Data collection top

Bruker APEXII area-detector diffractometer	R_int = 0.039
Graphite monochromator	θ_max = 25.0°, θ_min = 1.7°
ϕ and ω scans	h = −12→12
13954 measured reflections	k = −14→14
2617 independent reflections	l = −15→15
2217 reflections with I > 2σ(I)

Refinement top

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)] = 0.066	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.151	H atoms treated by a mixture of independent and constrained refinement
S = 1.20	w = 1/[σ²(F_o²) + (0.0545P)² + 0.4948P] where P = (F_o² + 2F_c²)/3
2617 reflections	(Δ/σ)_max < 0.001
185 parameters	Δρ_max = 0.21 e Å⁻³
0 restraints	Δρ_min = −0.20 e Å⁻³

Crystal data top

C₁₄H₁₉N₃O₃	V = 1484.2 (4) Å³
M_r = 277.17	Z = 4
Monoclinic, P2/c	Mo Kα radiation
a = 10.5688 (17) Å	µ = 0.09 mm⁻¹
b = 12.1887 (19) Å	T = 293 K
c = 12.6816 (15) Å	0.20 × 0.17 × 0.12 mm
β = 114.696 (10)°

Data collection top

Bruker APEXII area-detector diffractometer	2217 reflections with I > 2σ(I)
13954 measured reflections	R_int = 0.039
2617 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.066	0 restraints
wR(F²) = 0.151	H atoms treated by a mixture of independent and constrained refinement
S = 1.20	Δρ_max = 0.21 e Å⁻³
2617 reflections	Δρ_min = −0.20 e Å⁻³
185 parameters

Special details top

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. 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.

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

	x	y	z	U_iso*/U_eq
O1	0.61744 (16)	0.56198 (15)	0.71035 (13)	0.0554 (6)
O4A	0.90206 (18)	0.6309 (2)	0.37604 (17)	0.0822 (9)
O4B	0.70959 (19)	0.71709 (18)	0.27970 (16)	0.0702 (7)
N4	0.7876 (2)	0.66443 (19)	0.36479 (18)	0.0561 (8)
N8	0.36262 (19)	0.63064 (16)	0.56787 (17)	0.0424 (6)
N11	0.2518 (2)	0.85530 (16)	0.54095 (17)	0.0527 (7)
C1	0.6566 (2)	0.58808 (18)	0.63278 (18)	0.0427 (7)
C2	0.5618 (2)	0.63386 (17)	0.52278 (18)	0.0391 (7)
C3	0.6069 (2)	0.65830 (18)	0.43661 (19)	0.0421 (7)
C4	0.7429 (2)	0.64084 (19)	0.45537 (19)	0.0446 (7)
C5	0.8388 (2)	0.5980 (2)	0.5617 (2)	0.0528 (8)
C6	0.7975 (2)	0.5734 (2)	0.6469 (2)	0.0528 (8)
C7	0.4195 (2)	0.65234 (18)	0.49839 (19)	0.0426 (7)
C9	0.2183 (2)	0.6557 (2)	0.5425 (2)	0.0508 (8)
C10	0.2061 (3)	0.7661 (2)	0.5922 (2)	0.0552 (9)
C12	0.2898 (4)	0.9518 (2)	0.6147 (3)	0.0803 (12)
C13	0.3521 (5)	1.0384 (3)	0.5668 (4)	0.1090 (18)
C14	0.2542 (5)	1.0705 (3)	0.4457 (4)	0.1172 (18)
C15	0.2066 (4)	0.9692 (3)	0.3707 (3)	0.0911 (14)
C16	0.1493 (3)	0.8843 (3)	0.4255 (2)	0.0727 (11)
H3	0.54440	0.68660	0.36590	0.0510*
H5	0.93080	0.58650	0.57370	0.0630*
H6	0.86280	0.54600	0.71690	0.0630*
H7	0.36320	0.68250	0.42660	0.0510*
H8	0.413 (3)	0.601 (2)	0.638 (2)	0.062 (8)*
H9A	0.18100	0.59910	0.57540	0.0610*
H9B	0.16370	0.65620	0.45920	0.0610*
H10A	0.10990	0.77830	0.57880	0.0660*
H10B	0.26180	0.76560	0.67540	0.0660*
H12A	0.35650	0.93140	0.69190	0.0970*
H12B	0.20780	0.98100	0.62080	0.0970*
H13A	0.43810	1.01100	0.56630	0.1310*
H13B	0.37430	1.10250	0.61650	0.1310*
H14A	0.30080	1.12000	0.41360	0.1410*
H14B	0.17420	1.10830	0.44720	0.1410*
H15A	0.13530	0.98920	0.29520	0.1090*
H15B	0.28450	0.93820	0.35920	0.1090*
H16A	0.06640	0.91280	0.43070	0.0870*
H16B	0.12320	0.81910	0.37720	0.0870*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0454 (9)	0.0826 (13)	0.0419 (9)	0.0051 (8)	0.0218 (8)	0.0039 (8)
O4A	0.0416 (11)	0.143 (2)	0.0713 (13)	−0.0046 (11)	0.0327 (10)	−0.0041 (12)
O4B	0.0609 (12)	0.0993 (15)	0.0530 (11)	−0.0059 (10)	0.0265 (10)	0.0108 (10)
N4	0.0403 (12)	0.0829 (16)	0.0478 (12)	−0.0133 (11)	0.0210 (10)	−0.0081 (11)
N8	0.0357 (10)	0.0482 (11)	0.0445 (11)	0.0036 (8)	0.0180 (9)	0.0009 (9)
N11	0.0543 (12)	0.0550 (12)	0.0524 (12)	0.0070 (10)	0.0258 (10)	−0.0019 (10)
C1	0.0388 (12)	0.0492 (13)	0.0396 (12)	−0.0023 (10)	0.0159 (10)	−0.0088 (10)
C2	0.0341 (11)	0.0422 (12)	0.0416 (12)	−0.0015 (9)	0.0163 (9)	−0.0057 (10)
C3	0.0377 (12)	0.0463 (13)	0.0395 (12)	−0.0027 (10)	0.0133 (10)	−0.0019 (10)
C4	0.0375 (12)	0.0538 (14)	0.0434 (12)	−0.0087 (10)	0.0179 (10)	−0.0088 (10)
C5	0.0317 (12)	0.0747 (17)	0.0514 (14)	−0.0037 (11)	0.0168 (11)	−0.0077 (12)
C6	0.0332 (12)	0.0758 (17)	0.0423 (13)	0.0021 (11)	0.0087 (10)	−0.0005 (12)
C7	0.0395 (12)	0.0441 (13)	0.0429 (12)	0.0010 (10)	0.0158 (10)	−0.0007 (10)
C9	0.0360 (12)	0.0589 (15)	0.0606 (15)	0.0030 (11)	0.0233 (11)	0.0053 (12)
C10	0.0510 (14)	0.0662 (16)	0.0586 (15)	0.0128 (12)	0.0329 (13)	0.0053 (13)
C12	0.103 (2)	0.068 (2)	0.073 (2)	0.0068 (17)	0.0399 (18)	−0.0112 (16)
C13	0.149 (4)	0.067 (2)	0.109 (3)	−0.030 (2)	0.052 (3)	−0.020 (2)
C14	0.168 (4)	0.068 (2)	0.123 (3)	−0.003 (3)	0.068 (3)	0.015 (2)
C15	0.108 (3)	0.087 (2)	0.075 (2)	−0.002 (2)	0.035 (2)	0.0193 (18)
C16	0.0649 (18)	0.080 (2)	0.0675 (18)	0.0060 (15)	0.0219 (15)	0.0097 (16)

Geometric parameters (Å, º) top

O1—C1	1.257 (3)	C14—C15	1.511 (5)
O4A—N4	1.227 (3)	C15—C16	1.507 (5)
O4B—N4	1.230 (3)	C3—H3	0.9300
N4—C4	1.442 (3)	C5—H5	0.9300
N8—C7	1.285 (3)	C6—H6	0.9300
N8—C9	1.454 (3)	C7—H7	0.9300
N11—C10	1.449 (3)	C9—H9A	0.9700
N11—C12	1.451 (3)	C9—H9B	0.9700
N11—C16	1.455 (3)	C10—H10A	0.9700
N8—H8	0.90 (2)	C10—H10B	0.9700
C1—C2	1.447 (3)	C12—H12A	0.9700
C1—C6	1.435 (3)	C12—H12B	0.9700
C2—C7	1.421 (3)	C13—H13A	0.9700
C2—C3	1.395 (3)	C13—H13B	0.9700
C3—C4	1.372 (3)	C14—H14A	0.9700
C4—C5	1.406 (3)	C14—H14B	0.9700
C5—C6	1.357 (3)	C15—H15A	0.9700
C9—C10	1.514 (3)	C15—H15B	0.9700
C12—C13	1.500 (6)	C16—H16A	0.9700
C13—C14	1.502 (7)	C16—H16B	0.9700

O1···N8	2.674 (3)	C1···H10Bⁱ	3.1000
O1···C9ⁱ	3.098 (3)	C3···H13B^v	3.0200
O1···O1ⁱ	3.043 (3)	C5···H9A^vi	2.9200
O1···N8ⁱ	2.857 (3)	C9···H16B	2.7600
O4A···C9ⁱⁱ	3.134 (3)	C16···H9B	2.8100
O4B···C3ⁱⁱⁱ	3.400 (3)	H3···O4B	2.4400
O4B···C7ⁱⁱⁱ	3.302 (3)	H3···H7	2.3400
O1···H8ⁱ	2.13 (3)	H3···O4Bⁱⁱⁱ	2.5700
O1···H8	2.02 (3)	H5···O4A	2.4600
O1···H9Aⁱ	2.7000	H6···O4A^viii	2.8600
O1···H10Bⁱ	2.8900	H7···H3	2.3400
O4A···H5	2.4600	H7···H9B	2.3300
O4A···H9Bⁱⁱ	2.5300	H7···O4Bⁱⁱⁱ	2.4400
O4A···H6^iv	2.8600	H8···O1	2.02 (3)
O4B···H3	2.4400	H8···C1	2.61 (3)
O4B···H3ⁱⁱⁱ	2.5700	H8···O1ⁱ	2.13 (3)
O4B···H7ⁱⁱⁱ	2.4400	H9A···O1ⁱ	2.7000
O4B···H13B^v	2.8900	H9A···C5^vi	2.9200
N8···O1	2.674 (3)	H9B···O4A^vii	2.5300
N8···N11	2.942 (3)	H9B···C16	2.8100
N8···O1ⁱ	2.857 (3)	H9B···H7	2.3300
N11···N8	2.942 (3)	H9B···H16B	2.2000
N11···C7	3.217 (3)	H10A···H16A	2.3900
C1···C7^vi	3.299 (3)	H10B···H12A	2.2300
C1···C2^vi	3.568 (3)	H10B···O1ⁱ	2.8900
C2···C1^vi	3.568 (3)	H10B···C1ⁱ	3.1000
C2···C7^vi	3.511 (3)	H12A···H10B	2.2300
C2···C2^vi	3.472 (3)	H12B···H14B	2.5900
C3···O4Bⁱⁱⁱ	3.400 (3)	H12B···H16A	2.3900
C5···C9^vi	3.318 (3)	H13A···H15B	2.6000
C6···C7^vi	3.563 (3)	H13A···H13A^v	2.5400
C7···C6^vi	3.563 (3)	H13B···O4B^v	2.8900
C7···C2^vi	3.511 (3)	H13B···C3^v	3.0200
C7···O4Bⁱⁱⁱ	3.302 (3)	H14B···H12B	2.5900
C7···C1^vi	3.299 (3)	H15A···H15A^ix	2.6000
C7···N11	3.217 (3)	H15B···H13A	2.6000
C9···O4A^vii	3.134 (3)	H16A···H10A	2.3900
C9···C5^vi	3.318 (3)	H16A···H12B	2.3900
C9···O1ⁱ	3.098 (3)	H16B···C9	2.7600
C1···H8	2.61 (3)	H16B···H9B	2.2000

O4A—N4—O4B	122.9 (2)	C2—C7—H7	117.00
O4A—N4—C4	118.4 (2)	N8—C9—H9A	109.00
O4B—N4—C4	118.7 (2)	N8—C9—H9B	110.00
C7—N8—C9	123.6 (2)	C10—C9—H9A	109.00
C10—N11—C12	111.9 (2)	C10—C9—H9B	109.00
C10—N11—C16	112.7 (2)	H9A—C9—H9B	108.00
C12—N11—C16	109.9 (2)	N11—C10—H10A	109.00
C9—N8—H8	116 (2)	N11—C10—H10B	109.00
C7—N8—H8	121 (2)	C9—C10—H10A	109.00
O1—C1—C6	122.3 (2)	C9—C10—H10B	109.00
O1—C1—C2	122.0 (2)	H10A—C10—H10B	108.00
C2—C1—C6	115.7 (2)	N11—C12—H12A	109.00
C1—C2—C7	121.0 (2)	N11—C12—H12B	109.00
C1—C2—C3	120.8 (2)	C13—C12—H12A	109.00
C3—C2—C7	118.2 (2)	C13—C12—H12B	109.00
C2—C3—C4	120.5 (2)	H12A—C12—H12B	108.00
N4—C4—C5	119.6 (2)	C12—C13—H13A	109.00
C3—C4—C5	120.5 (2)	C12—C13—H13B	109.00
N4—C4—C3	120.0 (2)	C14—C13—H13A	109.00
C4—C5—C6	120.2 (2)	C14—C13—H13B	109.00
C1—C6—C5	122.4 (2)	H13A—C13—H13B	108.00
N8—C7—C2	125.0 (2)	C13—C14—H14A	110.00
N8—C9—C10	111.0 (2)	C13—C14—H14B	110.00
N11—C10—C9	112.2 (2)	C15—C14—H14A	110.00
N11—C12—C13	111.1 (3)	C15—C14—H14B	110.00
C12—C13—C14	111.5 (4)	H14A—C14—H14B	108.00
C13—C14—C15	109.7 (3)	C14—C15—H15A	109.00
C14—C15—C16	111.3 (3)	C14—C15—H15B	109.00
N11—C16—C15	110.9 (3)	C16—C15—H15A	109.00
C2—C3—H3	120.00	C16—C15—H15B	109.00
C4—C3—H3	120.00	H15A—C15—H15B	108.00
C4—C5—H5	120.00	N11—C16—H16A	109.00
C6—C5—H5	120.00	N11—C16—H16B	109.00
C1—C6—H6	119.00	C15—C16—H16A	109.00
C5—C6—H6	119.00	C15—C16—H16B	110.00
N8—C7—H7	117.00	H16A—C16—H16B	108.00

O4B—N4—C4—C5	−169.0 (2)	C6—C1—C2—C3	1.8 (3)
O4A—N4—C4—C5	11.1 (3)	O1—C1—C6—C5	177.7 (2)
O4A—N4—C4—C3	−167.7 (2)	C3—C2—C7—N8	177.8 (2)
O4B—N4—C4—C3	12.3 (3)	C1—C2—C7—N8	−0.5 (3)
C9—N8—C7—C2	176.8 (2)	C1—C2—C3—C4	−1.0 (3)
C7—N8—C9—C10	−93.7 (3)	C7—C2—C3—C4	−179.3 (2)
C10—N11—C12—C13	173.5 (3)	C2—C3—C4—N4	178.8 (2)
C16—N11—C10—C9	77.0 (3)	C2—C3—C4—C5	0.0 (3)
C12—N11—C16—C15	60.1 (4)	C3—C4—C5—C6	0.1 (4)
C16—N11—C12—C13	−60.5 (4)	N4—C4—C5—C6	−178.7 (2)
C12—N11—C10—C9	−158.4 (3)	C4—C5—C6—C1	0.8 (4)
C10—N11—C16—C15	−174.3 (3)	N8—C9—C10—N11	62.9 (3)
C6—C1—C2—C7	−180.0 (2)	N11—C12—C13—C14	57.5 (5)
C2—C1—C6—C5	−1.7 (3)	C12—C13—C14—C15	−52.8 (5)
O1—C1—C2—C3	−177.6 (2)	C13—C14—C15—C16	52.4 (5)
O1—C1—C2—C7	0.7 (3)	C14—C15—C16—N11	−56.8 (4)

Symmetry codes: (i) −x+1, y, −z+3/2; (ii) x+1, y, z; (iii) −x+1, y, −z+1/2; (iv) x, −y+1, z−1/2; (v) −x+1, −y+2, −z+1; (vi) −x+1, −y+1, −z+1; (vii) x−1, y, z; (viii) x, −y+1, z+1/2; (ix) −x, y, −z+1/2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N8—H8···O1	0.90 (2)	2.02 (3)	2.674 (3)	129 (3)
N8—H8···O1ⁱ	0.90 (2)	2.13 (3)	2.857 (3)	137 (3)
C3—H3···O4Bⁱⁱⁱ	0.93	2.57	3.400 (3)	149
C7—H7···O4Bⁱⁱⁱ	0.93	2.44	3.302 (3)	155
C9—H9B···O4A^vii	0.97	2.53	3.134 (3)	120

Symmetry codes: (i) −x+1, y, −z+3/2; (iii) −x+1, y, −z+1/2; (vii) x−1, y, z.

Experimental details

Crystal data
Chemical formula	C₁₄H₁₉N₃O₃
M_r	277.17
Crystal system, space group	Monoclinic, P2/c
Temperature (K)	293
a, b, c (Å)	10.5688 (17), 12.1887 (19), 12.6816 (15)
β (°)	114.696 (10)
V (Å³)	1484.2 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.20 × 0.17 × 0.12

Data collection
Diffractometer	Bruker APEXII area-detector diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	13954, 2617, 2217
R_int	0.039
(sin θ/λ)_max (Å⁻¹)	0.594

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.066, 0.151, 1.20
No. of reflections	2617
No. of parameters	185
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.21, −0.20

Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and Mercury (Version 1.4.2; Macrae et al., 2006), SHELXL97 (Sheldrick, 2008) and WinGX2003 (Farrugia, 1999).

Selected geometric parameters (Å, º) top

O1—C1	1.257 (3)	N11—C16	1.455 (3)
O4A—N4	1.227 (3)	C1—C2	1.447 (3)
O4B—N4	1.230 (3)	C1—C6	1.435 (3)
N4—C4	1.442 (3)	C2—C3	1.395 (3)
N8—C7	1.285 (3)	C3—C4	1.372 (3)
N8—C9	1.454 (3)	C4—C5	1.406 (3)
N11—C10	1.449 (3)	C5—C6	1.357 (3)
N11—C12	1.451 (3)	C9—C10	1.514 (3)

O4A—N4—O4B	122.9 (2)	O1—C1—C2	122.0 (2)
O4A—N4—C4	118.4 (2)	N4—C4—C5	119.6 (2)
O4B—N4—C4	118.7 (2)	N4—C4—C3	120.0 (2)
C7—N8—C9	123.6 (2)	N8—C7—C2	125.0 (2)
C10—N11—C12	111.9 (2)	N8—C9—C10	111.0 (2)
C10—N11—C16	112.7 (2)	N11—C10—C9	112.2 (2)
C12—N11—C16	109.9 (2)	N11—C12—C13	111.1 (3)
O1—C1—C6	122.3 (2)	N11—C16—C15	110.9 (3)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N8—H8···O1	0.90 (2)	2.02 (3)	2.674 (3)	129 (3)
N8—H8···O1ⁱ	0.90 (2)	2.13 (3)	2.857 (3)	137 (3)
C3—H3···O4Bⁱⁱ	0.93	2.57	3.400 (3)	149
C7—H7···O4Bⁱⁱ	0.93	2.44	3.302 (3)	155

Symmetry codes: (i) −x+1, y, −z+3/2; (ii) −x+1, y, −z+1/2.

Acknowledgements

This work was supported by CGIC–UC (Coordinación General de Investigación Científica de la Universidad de Colima) and SIP–IPN (Secretaria de Investigación y Postgrado del Instituto Politécnico Nacional).

References

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Volume 65| Part 1| January 2009| Pages o8-o10

doi:10.1107/S0108270108040407

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organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

The zwitterion of 4-nitro-2-{(E)-[2-(piperidin-1-yl)eth­yl]imino­meth­yl}­phenol

Comment

Experimental

Crystal data

Data collection

Refinement

Supporting information

Acknowledgements

References

organic compounds

The zwitterion of 4-nitro-2-{(E)-[2-(piperidin-1-yl)ethyl]iminomethyl}phenol