4,4′-[Propane-1,3-diylbis(nitrilo­methyl­idyne)]dibenzonitrile

The mol­ecule of the title Schiff base compound, C₁₉H₁₆N₄, has crystallographic twofold rotation symmetry. The imino group is coplanar with the aromatic ring. Within the mol­ecule, the planar units are parallel, but extend in opposite directions from the central methyl­ene bridge. The packing of the mol­ecules is controlled by C—H...π inter­actions.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.082
• wR factor = 0.127
• Data-to-parameter ratio = 14.2

checkCIF/PLATON results

No syntax errors found



Alert level C
SHFSU01_ALERT_2_C  Test not performed. _refine_ls_shift/su_max and
            _refine_ls_shift/esd_max not present.
            Absolute value of the parameter shift to su ratio given   0.001
PLAT371_ALERT_2_C Long   C(sp2)-C(sp1) Bond  C3     -   C10    ...       1.45 Ang.
PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent .....          ?
PLAT710_ALERT_4_C Delete 1-2-3 or 2-3-4 Linear Torsion Angle ... #         16
            C4  -C3  -C10 -N2     18.00  0.00   1.555   1.555   1.555   1.555
PLAT710_ALERT_4_C Delete 1-2-3 or 2-3-4 Linear Torsion Angle ... #         17
            C2  -C3  -C10 -N2      1.00 14.00   1.555   1.555   1.555   1.555

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

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

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S1. Comment

Schiff bases are one of most prevalent mixed-donor ligands in coordination chemistry. They play an important role in the development of coordination chemistry related to catalysis and enzymatic reactions, magnetism, and supramolecular architectures. Structures of Schiff bases derived from substituted benzaldehydes and closely related to the title compound, (I), are known (Li et al., 2005; Bomfim et al., 2005; Glidewell et al., 2005, 2006; Sun et al., 2004; Habibi et al., 2007).

The molecule of (I), Fig. 1, has a crystallographic 2-fold symmetry. The bond lengths and angles are within normal ranges (Allen et al., 1987). The group is coplanar with the aromatic ring in each half of the molecule. The planar units are parallel by symmetry, but extend in opposite directions from the central methylene bridge, the C6—C7—N1—C8 torsion angle is 178.9 (3)°. The packing of the molecules, Fig. 2, is controlled by C—H···π interactions, Table 1.

Related literature

For values of bond lengths, see Allen et al. (1987). For related structures, see: Li et al. (2005); Bomfim et al. (2005); Glidewell et al. (2005, 2006); Sun et al., (2004); Habibi et al. (2007). Cg1 is the centroid of C1–C6 benzene ring.

S2. Experimental

A solution of 1,3-propanediamine (0.1 mmol, 0.074 g) was slowly added to a solution of 4-cyanobenzaldehyde (0.2 mmol, 0.026 g) in chloroform (30 ml). Recrystallization of the resulting solid from ethanol afforded colourless crystals of (I).

S3. Refinement

The C9-bound H atom was located from a difference Fourier map and refined freely. The remaining H atoms were positioned geometrically with C—H = 0.93 Å (aromatic and methine) or 0.97 Å (CH₂), and refined in the riding mode approximation with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2 (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2003).

Figures

	Fig. 1. The molecular structure of (I) showing atom labeling and 50% probability ellipsoids [symmetry code for i: -x, y, 0.5 - z].
	Fig. 2. A view down the b-axis of the unit cell contents for (I), highlighting the parallel arrangement of the molecules.

4,4'-[Propane-1,3-diylbis(nitrilomethylidyne)]dibenzonitrile

Crystal data

C19H16N4	F(000) = 632
Mr = 300.36	Dx = 1.263 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 2928 reflections
a = 14.4982 (4) Å	θ = 3.0–30.0°
b = 6.9025 (2) Å	µ = 0.08 mm^−1
c = 16.9842 (6) Å	T = 100 K
β = 111.659 (4)°	Needle, colourless
V = 1579.67 (8) Å^3	0.37 × 0.12 × 0.12 mm
Z = 4

Data collection

Bruker SMART APEXII CCD area-detector diffractometer	1544 independent reflections
Radiation source: fine-focus sealed tube	1257 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.077
ϕ and ω scans	θmax = 26.0°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2005)	h = −17→17
Tmin = 0.886, Tmax = 0.991	k = −8→8
13317 measured reflections	l = −20→20

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)] = 0.081	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.127	H atoms treated by a mixture of independent and constrained refinement
S = 1.17	w = 1/[σ^2(Fo^2) + (0.0132P)^2 + 5.0812P] where P = (Fo^2 + 2Fc^2)/3
1544 reflections	(Δ/σ)max < 0.001
109 parameters	Δρmax = 0.18 e Å^−3
0 restraints	Δρmin = −0.37 e Å^−3

Special details

Experimental. The low-temperature data was collected with the Oxford Cyrosystem Cobra low-temperature attachment.

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.

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 (Ų)

	x	y	z	Uiso*/Ueq
N1	0.14554 (16)	0.8098 (3)	0.29318 (13)	0.0173 (5)
N2	0.5053 (2)	0.1024 (4)	0.59762 (16)	0.0373 (7)
C1	0.29164 (19)	0.6045 (4)	0.43213 (16)	0.0193 (6)
H1A	0.2869	0.7370	0.4397	0.023*
C2	0.3625 (2)	0.4975 (4)	0.49323 (16)	0.0211 (6)
H2A	0.4052	0.5574	0.5422	0.025*
C3	0.3701 (2)	0.2986 (4)	0.48155 (17)	0.0192 (6)
C4	0.3064 (2)	0.2085 (4)	0.40896 (17)	0.0203 (6)
H4A	0.3116	0.0761	0.4012	0.024*
C5	0.23520 (19)	0.3172 (4)	0.34838 (17)	0.0183 (6)
H5A	0.1921	0.2570	0.2997	0.022*
C6	0.22689 (19)	0.5159 (4)	0.35906 (16)	0.0161 (6)
C7	0.15182 (19)	0.6273 (4)	0.29081 (17)	0.0183 (6)
H7A	0.1077	0.5609	0.2446	0.022*
C8	0.06898 (19)	0.9029 (4)	0.22061 (16)	0.0185 (6)
H8A	0.0310	0.8047	0.1811	0.022*
H8B	0.1002	0.9855	0.1915	0.022*
C9	0.0000	1.0233 (6)	0.2500	0.0162 (8)
C10	0.4454 (2)	0.1869 (4)	0.54596 (18)	0.0262 (7)
H9A	0.0367 (18)	1.110 (4)	0.2938 (15)	0.015 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0147 (12)	0.0211 (13)	0.0155 (11)	0.0035 (10)	0.0049 (9)	0.0024 (10)
N2	0.0446 (17)	0.0425 (17)	0.0235 (14)	0.0218 (15)	0.0109 (13)	0.0090 (13)
C1	0.0215 (15)	0.0158 (14)	0.0217 (14)	0.0001 (12)	0.0091 (12)	−0.0019 (12)
C2	0.0220 (15)	0.0242 (16)	0.0142 (13)	0.0027 (12)	0.0034 (12)	−0.0020 (12)
C3	0.0193 (14)	0.0227 (15)	0.0199 (14)	0.0046 (12)	0.0121 (12)	0.0049 (12)
C4	0.0246 (15)	0.0151 (14)	0.0268 (15)	0.0011 (12)	0.0162 (13)	0.0015 (12)
C5	0.0167 (14)	0.0191 (15)	0.0198 (14)	−0.0056 (11)	0.0075 (12)	−0.0058 (11)
C6	0.0150 (14)	0.0202 (15)	0.0165 (13)	0.0008 (11)	0.0097 (11)	0.0004 (11)
C7	0.0135 (14)	0.0229 (16)	0.0177 (14)	−0.0030 (11)	0.0048 (11)	−0.0025 (11)
C8	0.0156 (13)	0.0236 (15)	0.0159 (13)	0.0031 (12)	0.0052 (11)	0.0001 (12)
C9	0.0144 (19)	0.015 (2)	0.0174 (19)	0.000	0.0042 (16)	0.000
C10	0.0330 (17)	0.0270 (17)	0.0206 (15)	0.0072 (14)	0.0123 (14)	0.0013 (13)

Geometric parameters (Å, º)

N1—C7	1.264 (3)	C4—H4A	0.9300
N1—C8	1.468 (3)	C5—C6	1.395 (4)
N2—C10	1.141 (4)	C5—H5A	0.9300
C1—C2	1.375 (4)	C6—C7	1.479 (4)
C1—C6	1.391 (4)	C7—H7A	0.9300
C1—H1A	0.9300	C8—C9	1.519 (3)
C2—C3	1.398 (4)	C8—H8A	0.9700
C2—H2A	0.9300	C8—H8B	0.9700
C3—C4	1.386 (4)	C9—C8^i	1.519 (3)
C3—C10	1.450 (4)	C9—H9A	0.95 (3)
C4—C5	1.380 (4)
C7—N1—C8	116.8 (2)	C1—C6—C5	119.1 (3)
C2—C1—C6	120.5 (3)	C1—C6—C7	122.0 (2)
C2—C1—H1A	119.7	C5—C6—C7	118.9 (2)
C6—C1—H1A	119.7	N1—C7—C6	122.3 (3)
C1—C2—C3	119.8 (3)	N1—C7—H7A	118.9
C1—C2—H2A	120.1	C6—C7—H7A	118.9
C3—C2—H2A	120.1	N1—C8—C9	110.43 (19)
C4—C3—C2	120.4 (3)	N1—C8—H8A	109.6
C4—C3—C10	120.1 (3)	C9—C8—H8A	109.6
C2—C3—C10	119.5 (3)	N1—C8—H8B	109.6
C5—C4—C3	119.3 (3)	C9—C8—H8B	109.6
C5—C4—H4A	120.4	H8A—C8—H8B	108.1
C3—C4—H4A	120.4	C8—C9—C8^i	113.7 (3)
C4—C5—C6	121.0 (3)	C8—C9—H9A	110.8 (15)
C4—C5—H5A	119.5	C8^i—C9—H9A	109.5 (15)
C6—C5—H5A	119.5	N2—C10—C3	178.6 (4)
C6—C1—C2—C3	0.5 (4)	C4—C5—C6—C7	177.7 (2)
C1—C2—C3—C4	−0.3 (4)	C8—N1—C7—C6	178.9 (2)
C1—C2—C3—C10	179.6 (3)	C1—C6—C7—N1	3.5 (4)
C2—C3—C4—C5	−0.1 (4)	C5—C6—C7—N1	−174.2 (3)
C10—C3—C4—C5	180.0 (3)	C7—N1—C8—C9	123.5 (3)
C3—C4—C5—C6	0.3 (4)	N1—C8—C9—C8^i	−71.64 (19)
C2—C1—C6—C5	−0.4 (4)	C4—C3—C10—N2	−179 (100)
C2—C1—C6—C7	−178.0 (3)	C2—C3—C10—N2	1 (14)
C4—C5—C6—C1	−0.1 (4)

Symmetry code: (i) −x, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C8—H8B···Cg1^ii	0.97	2.85	3.58	133

Symmetry code: (ii) x, −y, z−1/2.