The Schiff base N,N′-bis­(3-nitro­benzyl­idene)propane-1,3-diamine

The mol­ecule of the title Schiff base compound, C₁₇H₁₆N₄O₄, has crystallographic twofold rotation symmetry. The nitro and CH=N—C substituents are coplanar with the benzene ring in each half of the mol­ecule. These two planar units are parallel, but extend in opposite directions from the central methyl­ene bridge, so there is no intra­molecular π-stacking. Instead, mol­ecules pack with approximately parallel inter­leaved benzene rings providing inter­molecular π-stacking, the centroid-to-centroid separation being 3.7196 (18) Å.

Key indicators

• Single-crystal X-ray study
• T = 150 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.039
• wR factor = 0.104
• Data-to-parameter ratio = 8.8

checkCIF/PLATON results

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Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           27.50
           From the CIF: _reflns_number_total               1004
           Count of symmetry unique reflns         1010
           Completeness (_total/calc)             99.41%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   0 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Schiff base compounds play an important role in the development of coordination chemistry related to catalysis and enzymatic reactions, magnetism, and molecular architectures. Structures of Schiff bases derived from nitrobenzaldehydes and closely related to the title compound have been reported by Li et al. (2005), Bomfin et al. (2005), Glidewell et al. (2005, 2006), and Sun et al. (2004).

The title compound, (I), was prepared by the condensation of 3-nitrobenzaldehyde and 1,3-diaminopropane in a 2:1 molar ratio. A view of the molecular structure is shown in Fig. 1. The molecule has crystallographic twofold rotation symmetry. Bond lengths and angles are unexceptional. The nitro and CH═N—C substituents are coplanar with the benzene ring in each half of the molecule. These two planar units are parallel by symmetry, but extend in opposite directions from the central methylene bridge, so there is no intramolecular π-stacking. Instead, molecules pack with approximately parallel interleaved benzene rings providing intermolecular π-stacking, the centroid-to-centroid separation being 3.7196 (18) Å (Fig. 2).

Related literature

For related structures, see: Li et al. (2005), Bomfin et al. (2005), Glidewell et al. (2005, 2006), and Sun et al., (2004).

S2. Experimental

A solution of 1,3-propanediamine (0.1 mmol, 0.074 g) in chloroform (5 ml) was slowly added to a solution of 3-nitrobenzaldehyde (0.2 mmol, 0.30 g) in the same solvent (5 ml). Recrystallization of the resulting solid from ethanol afforded colourless crystals, 81% yield.

S3. Refinement

Hydrogen atoms were positioned geometrically with C—H = 0.95 (aromatic) or 0.98 Å (CH₂), and refined in riding mode with U_iso(H) = 1.2U_eq(C). In the absence of significant anomalous scattering effects, Friedel pairs were averaged.

Computing details

Data collection: COLLECT (Nonius, 1998); cell refinement: EVALCCD (Duisenberg et al., 2003); data reduction: EVALCCD; program(s) used to solve structure: SHELXTL (Sheldrick, 2005); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and local programs.

Figures

	Fig. 1. The molecular structure with atom labels and 50% probability ellipsoids for non-H atoms [symmetry code for unlabelled atoms: -x, -y, z].
	Fig. 2. The packing, viewed down the c axis, showing stacking of the benzene rings.

N,N'-bis(3-nitrobenzylidene)propane-1,3-diamine

Crystal data

C17H16N4O4	Dx = 1.390 Mg m^−3
Mr = 340.34	Melting point: 390 K
Orthorhombic, Fdd2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: F 2 -2d	Cell parameters from 106 reflections
a = 12.994 (3) Å	θ = 2.5–27.5°
b = 35.859 (12) Å	µ = 0.10 mm^−1
c = 6.983 (2) Å	T = 150 K
V = 3253.7 (16) Å^3	Block, colourless
Z = 8	0.45 × 0.40 × 0.40 mm
F(000) = 1424

Data collection

Nonius KappaCCD diffractometer	858 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.038
Graphite monochromator	θmax = 27.5°, θmin = 4.3°
φ and ω scans	h = −16→11
7631 measured reflections	k = −46→46
1004 independent reflections	l = −7→9

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.039	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.104	H-atom parameters constrained
S = 1.15	w = 1/[σ^2(Fo^2) + (0.0609P)^2 + 1.1167P] where P = (Fo^2 + 2Fc^2)/3
1004 reflections	(Δ/σ)max < 0.001
114 parameters	Δρmax = 0.26 e Å^−3
1 restraint	Δρmin = −0.23 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.06407 (16)	0.18127 (4)	0.6914 (3)	0.0409 (5)
O2	0.09163 (14)	0.21456 (5)	0.4384 (3)	0.0446 (5)
N1	0.08005 (15)	0.18443 (5)	0.5184 (3)	0.0304 (5)
N2	0.09255 (14)	0.04422 (5)	0.6668 (3)	0.0310 (5)
C1	0.08638 (15)	0.15000 (6)	0.4017 (3)	0.0249 (5)
C2	0.09912 (17)	0.15330 (7)	0.2039 (4)	0.0298 (5)
H2	0.1014	0.1770	0.1435	0.036*
C3	0.10824 (18)	0.12071 (7)	0.0994 (4)	0.0349 (6)
H3	0.1162	0.1219	−0.0357	0.042*
C4	0.10585 (17)	0.08602 (7)	0.1900 (3)	0.0308 (6)
H4	0.1130	0.0639	0.1161	0.037*
C5	0.09300 (15)	0.08339 (6)	0.3882 (3)	0.0259 (6)
C6	0.08196 (16)	0.11602 (6)	0.4955 (3)	0.0226 (5)
H6	0.0716	0.1149	0.6300	0.027*
C7	0.09518 (17)	0.04671 (6)	0.4865 (4)	0.0296 (6)
H7	0.0986	0.0246	0.4120	0.036*
C8	0.09691 (18)	0.00688 (6)	0.7532 (4)	0.0324 (6)
H8A	0.1585	0.0049	0.8361	0.039*
H8B	0.1024	−0.0122	0.6512	0.039*
C9	0.0000	0.0000	0.8718 (5)	0.0292 (7)
H9A	0.0118	−0.0219	0.9555	0.035*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0569 (11)	0.0346 (9)	0.0313 (11)	−0.0037 (8)	0.0078 (9)	−0.0082 (8)
O2	0.0501 (11)	0.0270 (9)	0.0566 (14)	−0.0030 (7)	0.0149 (10)	0.0076 (9)
N1	0.0243 (10)	0.0299 (11)	0.0369 (13)	−0.0018 (7)	0.0044 (9)	−0.0007 (9)
N2	0.0316 (11)	0.0238 (9)	0.0377 (12)	0.0004 (7)	0.0007 (9)	0.0014 (8)
C1	0.0178 (10)	0.0302 (12)	0.0267 (14)	−0.0016 (8)	−0.0022 (9)	−0.0004 (9)
C2	0.0232 (11)	0.0400 (12)	0.0263 (14)	−0.0040 (9)	−0.0006 (10)	0.0074 (11)
C3	0.0256 (13)	0.0613 (18)	0.0180 (12)	−0.0071 (10)	−0.0023 (10)	0.0008 (12)
C4	0.0236 (11)	0.0436 (13)	0.0253 (14)	−0.0042 (9)	−0.0002 (10)	−0.0100 (11)
C5	0.0192 (11)	0.0313 (12)	0.0272 (15)	−0.0031 (8)	−0.0023 (9)	−0.0041 (9)
C6	0.0190 (11)	0.0298 (11)	0.0191 (12)	−0.0019 (8)	−0.0002 (9)	−0.0006 (9)
C7	0.0257 (12)	0.0268 (11)	0.0364 (15)	−0.0028 (8)	0.0032 (10)	−0.0082 (10)
C8	0.0335 (12)	0.0225 (11)	0.0412 (15)	0.0024 (9)	0.0012 (11)	0.0017 (10)
C9	0.0288 (16)	0.0238 (14)	0.0350 (18)	0.0029 (12)	0.000	0.000

Geometric parameters (Å, º)

O1—N1	1.231 (3)	C4—C5	1.397 (3)
O2—N1	1.226 (3)	C5—C6	1.397 (3)
N1—C1	1.482 (3)	C5—C7	1.484 (3)
N2—C7	1.263 (4)	C6—H6	0.950
N2—C8	1.470 (3)	C7—H7	0.950
C1—C2	1.396 (4)	C8—H8A	0.990
C1—C6	1.384 (3)	C8—H8B	0.990
C2—H2	0.950	C8—C9	1.527 (3)
C2—C3	1.383 (3)	C9—C8^i	1.527 (3)
C3—H3	0.950	C9—H9A	0.990
C3—C4	1.396 (4)	C9—H9A^i	0.990
C4—H4	0.950
O1—N1—O2	123.3 (2)	C1—C6—C5	118.6 (2)
O1—N1—C1	118.20 (19)	C1—C6—H6	120.7
O2—N1—C1	118.5 (2)	C5—C6—H6	120.7
C7—N2—C8	118.2 (2)	N2—C7—C5	121.6 (2)
N1—C1—C2	118.7 (2)	N2—C7—H7	119.2
N1—C1—C6	118.1 (2)	C5—C7—H7	119.2
C2—C1—C6	123.2 (2)	N2—C8—H8A	109.7
C1—C2—H2	121.3	N2—C8—H8B	109.7
C1—C2—C3	117.4 (2)	N2—C8—C9	109.75 (16)
H2—C2—C3	121.3	H8A—C8—H8B	108.2
C2—C3—H3	119.6	H8A—C8—C9	109.7
C2—C3—C4	120.8 (2)	H8B—C8—C9	109.7
H3—C3—C4	119.6	C8—C9—C8^i	114.3 (3)
C3—C4—H4	119.6	C8—C9—H9A	108.7
C3—C4—C5	120.8 (2)	C8^i—C9—H9A	108.7
H4—C4—C5	119.6	C8—C9—H9A^i	108.7
C4—C5—C6	119.1 (2)	C8^i—C9—H9A^i	108.7
C4—C5—C7	121.0 (2)	H9A—C9—H9A^i	107.6
C6—C5—C7	119.8 (2)
O1—N1—C1—C2	176.7 (2)	N1—C1—C6—C5	−176.85 (18)
O1—N1—C1—C6	−4.9 (3)	C2—C1—C6—C5	1.4 (3)
O2—N1—C1—C2	−3.8 (3)	C4—C5—C6—C1	−1.4 (3)
O2—N1—C1—C6	174.61 (18)	C7—C5—C6—C1	176.16 (18)
N1—C1—C2—C3	177.89 (19)	C8—N2—C7—C5	−178.89 (18)
C6—C1—C2—C3	−0.4 (3)	C4—C5—C7—N2	173.8 (2)
C1—C2—C3—C4	−0.7 (3)	C6—C5—C7—N2	−3.7 (3)
C2—C3—C4—C5	0.7 (3)	C7—N2—C8—C9	−120.0 (2)
C3—C4—C5—C6	0.3 (3)	N2—C8—C9—C8^i	73.30 (18)
C3—C4—C5—C7	−177.17 (19)

Symmetry code: (i) −x, −y, z.