1-[(4-{[(2-Oxo-1,2-dihydro­naphthalen-1-yl­idene)meth­yl]amino}­anilino)methyl­idene]naphthalen-2(1H)-one dihydrate

Anita Blagus; Branko Kaitner

doi:10.1107/S1600536811041870

. 2011 Oct 12;67(Pt 11):o2958–o2959. doi: 10.1107/S1600536811041870

1-[(4-{[(2-Oxo-1,2-dihydronaphthalen-1-ylidene)methyl]amino}anilino)methylidene]naphthalen-2(1H)-one dihydrate

Anita Blagus ^a,^*, Branko Kaitner ^b

PMCID: PMC3247366 PMID: 22219984

Abstract

The title compound, C₂₈H₂₀N₂O₂·2H₂O, comprises a Schiff base molecule with an imposed inversion centre in the middle of p-phenylenediamine unit and water molecules of crystallization. In the structure, the Schiff base molecule is present as the keto–amino tautomer with a strong intramolecular N—H⋯O hydrogen bond. The Schiff base molecules and water molecules of crystallization create infinite [010] columns through O—H⋯O hydrogen bonds. Intermolecular attractions within columns are through additional π–π interactions [centroid–centroid distance = 3.352 (1) Å] between parallel Schiff base molecules. The columns are joined into infinite (011) layers through weak C—H⋯O hydrogen bonds. The layers pack in an assembly by van der Waals attractions, only being effective between bordering non-polar naphthalene ring systems.

Related literature

For general background to Schiff bases, see: Blagus et al. (2010 ▶). The stereochemistry of intrinsic Schiff bases differs significantly, see: Inabe et al. (1994 ▶). For the quinoid effect in 2-oxy-naphthaldimine Schiff base derivatives, see: Gavranić et al. (1996 ▶); Friščić et al. (1998 ▶). For the herringbone packing motif in fused aromatic systems, see: Desiraju & Gavezzotti (1989 ▶).

Experimental

Crystal data

C₂₈H₂₀N₂O₂·2H₂O
M _r = 452.49
Monoclinic,
a = 17.4222 (11) Å
b = 4.4686 (5) Å
c = 15.9374 (10) Å
β = 116.30 (1)°
V = 1112.3 (2) Å³
Z = 2
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 298 K
0.5 × 0.2 × 0.1 mm

Data collection

Oxford Diffraction Xcalibur CCD diffractometer
14006 measured reflections
2423 independent reflections
1351 reflections with I > 2σ(I)
R _int = 0.054

Refinement

R[F ² > 2σ(F ²)] = 0.061
wR(F ²) = 0.190
S = 1.05
2423 reflections
160 parameters
3 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: CrysAlis CCD (Oxford Diffraction, 2003 ▶); cell refinement: CrysAlis CCD; data reduction: CrysAlis RED (Oxford Diffraction, 2003 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶), PARST97 (Nardelli, 1995 ▶) and Mercury (Macrae et al., 2006 ▶).

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536811041870/kp2357sup1.cif

e-67-o2958-sup1.cif^{(16.4KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811041870/kp2357Isup2.hkl

e-67-o2958-Isup2.hkl^{(119.1KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811041870/kp2357Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O1	0.86	1.86	2.560 (3)	138
O1W—H1B⋯O1	0.83	2.27	3.090 (4)	169
O1W—H1A⋯O1ⁱ	0.84	2.01	2.826 (4)	165
C13—H13⋯O1Wⁱⁱ	0.93	2.33	3.247 (5)	170

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

Financial support by the Ministry of Science, Education and Sport of the Republic of Croatia is gratefully acknowledged (grant No. 119–1193079–3069).

supplementary crystallographic information

Comment

Desiraju and Gavezzotti presented classification of packing arrangements for polynuclear aromatic hydrocarbons depending on the number and positions of C and H atoms in molecules (Desiraju & Gavezzotti, 1989). As a result of significant planarity, Schiff bases derived from p-phenylenediamine have significant aromatic-aromatic C···C interactions compared to the number of intermolecular C–H hydrogen bonds and usually show a herringbone motif of intermolecular assembly (Blagus et al., 2010).

We report here the crystal structure of the title compound (I) as a crystal hydrate. The stereochemistry of intrinsic 1,4-bis(2-hydroxy-1-naphthylmethylideneamino)benzene was earlier determined and reported (Inabe et al., 1994). Distinctively planar Schiff base molecule possesses crystallographic inversion centre in the middle of p-phenylenediamine moiety with anti arrangements of chelate rings (Fig. 1). Interplanar angle between naphthalene moiety and the central aromatic ring is 1.7 (2)°. Schiff base molecule does not deviate significantly from planarity in contrast to the structure by Inabe et al. with corresponding interplanar angle being 22.3°.In both structures molecules possess internal (molecular) symmetry with inversion centre in the middle of p-phenylenediamine moiety.

Bond distances C2–O1 [1.277 (4) Å] and C11–N1 [1.322 (4) Å] indicate keto-amino tautomeric form of (I). This is confirmed by a formation of strong intramolecular hydrogen bond N–H···O [N···O = 2.560 (3) Å]. Short C3-to-C4 bond distance [1.345 (5) Å] with O1 oxygen atom at C2 position of naphthalene core indicates the presence of quinoid effect (Gavranić et al., 1996; Friščić et al., 1998). Water molecules play crucial role in crystal packing: a) as bridging media pilling up Schiff base molecules at the separation characteristic for graphite in the form of infinite [010] columns and b) as bridging molecule connecting neighboring [010] columns into infinite (011) layers. Hydrogen bonds effective for columns formation are: a) O1W–H1A···O1ⁱ 2.826 (4) Å [(i): x, y + 1, z] and O1W–H1B···O1 3.090 (4) Å while for layers formation is effective b) C13–H13···OW1ⁱⁱ 3.247 (5) Å [(ii): x, – y + 3/2, z] (Fig. 2 and Table 1).

Along with intermolecular contacts via hydrogen bonds the linking between molecules amplifies through π–π interactions with offset (Fig. 2). Schiff base molecules arrange parallel to each other with their middle p-phenylenediamine moiety being separated at distances characteristic for layer separation in graphite. The shortest separations corresponding to the sum of van der Waals radii are: C12···C12ⁱⁱⁱ 3.362 (3) Å [(iii): -x, -y + 1, -z] and C11···C13^iv 3.374 (3) Å [(iv): x, y - 1, z]. π··· π interactions are also characterised by perpendicular Cgⁱⁱⁱ···Cg^v distance 3.352 (1) Å [(v): -x, 3 - y, -z] and slippage of 2.955 Å. There is a space between each pair of neighboring columns large enough to accommodate water molecules (Fig. 3). Connection between neighboring parallel layers is accomplished through bordering non-polar naphthalene core by the standard van der Walls attractions. The rather planar Schiff base molecules of (I) reveal characteristic herringbone motif of packing arrangement (Fig. 4).

Experimental

The crystals of (I), (1,4-bis(2-hydroxy-1-naphthylmethylideneamino)benzene as crystal hydrate were obtained during an unsuccessful attempt to synthesise the nickel complex of corresponding Schiff base. Schiff base itself was prepared separately in standard way by condensation of 2-hydroxy-naphtaldehyde and p-phenylenediamine in ethanol solution in molar ratio 2:1 and used as a ligand in metal complex synthesis. The 1:1 mixture of 0.1 mmol DMSO solutions of Schiff base and 0.2 mmol nickel salt, NiCl₂. 6H₂O was stirred under reflux for two h at 373 K. Preparation of nickel complex failed. The crystals of title compound crystallised from mother liquor after cooling to RT and mechanically separated from nickel salt.