2,2′-[(Butane-1,4-diyldi­oxy)bis­(nitrilo­methyl­idyne)]dinaphthalene

The title complex, C₂₆H₂₄N₂O₂, was synthesized by the reaction of 1-naphthaldehyde with 1,4-bis­(amino­oxy)butane in ethanol. The mol­ecule has crystallographic inversion symmetry. The inter­molecular distance between the nearest naphthalene rings is 3.141 (2) Å, indicating a strong inter­molecular π–π stacking inter­action.

Key indicators

• Single-crystal X-ray study
• T = 273 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.046
• wR factor = 0.120
• Data-to-parameter ratio = 13.7

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent .....          ?
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          1
              C26 H24 N2 O2

Alert level G
PLAT804_ALERT_5_G ARU-Pack Problem in PLATON Analysis ............          1 Times

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

   2 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
   0 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

---

S1. Comment

Schiff bases have been widely used as versatile ligands in the formation of transition metal complexes (Aysegul et al., 2005). They have been found to possess potent activities including inorganic biochemistry (Niederhoffer et al., 1984), catalysis (Srinivasan et al., 1986; Zhang et al., 1990), medical imaging (Tisato et al., 1994), optical materials (Lacroix, 2001) and thin films (Sundari et al., 1997). Although most Schiff base derivatives are stable in solution and in the solid state, C=N bonds often suffer an exchange reaction (Koehler et al., 1964) as well as hydrolysis (Cordes & Jencks, 1962). Rate constants of oxime formation are smaller than those of imine formation, and the equilibrium constants are larger by several orders of magnitude (Akine, Takanori, Taniguchi & Nabeshima, 2005). Hence, the title compound should be stable enough to resist the metathesis of the C=N bonds (Akine et al., 2001). In recent years, we have been very much interested in the chemistry of salen-type derivatives, such as 2,2'-[(1,4-butylene)dioxybis(nitrilomethylidyne)]dinaphthol (Dong, Duan et al., 2006), 4,4'-dibromo-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol (Dong & Feng, 2006),4,4'-dibromo-2,2'-[(1,3-propylene) dioxybis(nitrilomethylidyne)]diphenol (Dong, Feng & Yang, 2006), and 2,2'-[(propane-1,3-diyldioxy)bis(nitrilomethylidyne)]diphenol (Duan et al., 2007). In this paper, a bisoxime ligand, 2,2'-[(1,4-butylene)dioxybis(nitrilomethylidyne)]dinaphthane was designed and synthesized, and shown in Fig. 1. The molecule is disposed about a crystallographic centre of symmetry, and the molecule adopts an extended conformation where the two naphthaldoxime moieties are apart from each other. The oxime groups have the anti-conformation, which is similar to what is observed in our previously reported salen-type bisoxime of 2,2'-[(1,4-butylene)dioxybis(nitrilomethylidyne)]dinaphthol (Dong, Duan et al., 2006). Noteworthy is that the distance between the nearest naphthane rings, parallel to that of another molecule, is 3.141 (2) Å, revealing a strong intermolecular π-π stacking interaction as shown in Fig. 2.

Related literature

Related structures are given by Dong, Duan et al. (2006); Dong & Feng (2006); Dong, Feng & Yang (2006); Duan et al. (2007).

For related literature, see: Akine et al. (2001, 2006); Akine, Takanori, Dong & Nabeshima (2005); Akine, Takanori, Taniguchi & Nabeshima (2005); Aysegul et al. (2005); Cordes & Jencks (1962); Koehler et al. (1964); Lacroix (2001); Niederhoffer et al. (1984); Srinivasan et al. (1986); Sundari et al. (1997); Tisato et al. (1994); Zhang et al. (1990).

S2. Experimental

2,2'-[(1,4-butylene)dioxybis(nitrilomethylidyne)]dinaphthane was synthesized according to an analogous method reported earlier (Akine, Takanori, Dong & Nabeshima, 2005; Akine et al., 2006). To an ethanol solution (5 ml) of 1-naphthaldehyde (213.6 mg, 1.36 mmol) was added an ethanol (3 ml) solution of 1,4-bis(aminooxy)butane (70.8 mg, 0.67 mmol). The solution was stirred at 328 K for 5 h, then concentrated to about 2 ml under reduced pressure. The precipitate was filtered and washed successively with ethanol and hexane. The product was dried under vacuum and purified by recrystallization from ethanol to yield 182.5 mg of the title compound. Yield, 68.7%. mp. 363–364 K. Anal. Calc. for C₂₆H₂₄N₂O₂: C, 78.76; H, 6.10; N, 7.07. Found: C, 78.68; H, 6.03; N, 7.21. IR: νC=N, 1624 cm^-1 and νC-O, 1175 cm^{-1. 1}H NMR (400 MHz, CDCl₃) 1.97 (s, 4H), 4.36 (s, 4H), 7.46 (t, J= 7.6 Hz, 4H), 7.51 (t, J= 7.8 Hz, 2H), 7.55 (dd, J= 7.0 Hz, 2H), 7.75 (d, J= 7.8 Hz, 2H), 7.86 (d, J= 8.0 Hz, 2H), 8.54(d, J= 8.8 Hz, 2H), 8.74 (s, 2H). Colorless block-shaped single crystals suitable for X-ray diffraction studies were obtained after several weeks by slow evaporation from an ethanol solution of 2,2'-[(1,4-butylene)dioxybis(nitrilomethylidyne)]dinaphthane.

S3. Refinement

Non-H atoms were refined anisotropically. H atoms were treated as riding atoms with distances C—H = 0.97 (CH₂), or 0.93 Å (CH), and U_iso(H) = 1.2 U_eq(C).

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART (Bruker, 1998); data reduction: SAINT (Bruker, 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL (Sheldrick, 1997b).

Figures

	Fig. 1. The molecule structure with the atom numbering scheme. Displacement ellipsoids for non-hydrogen atoms are drawn at the 30% probability level.
	Fig. 2. A view showing the formation of π-π interactions.

2,2'-[(Butane-1,4-diyldioxy)bis(nitrilomethylidyne)]dinaphthalene

Crystal data

C26H24N2O2	F(000) = 420
Mr = 396.47	Dx = 1.241 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 9.0910 (18) Å	Cell parameters from 625 reflections
b = 5.8499 (13) Å	θ = 2.3–20.6°
c = 20.019 (3) Å	µ = 0.08 mm^−1
β = 94.779 (2)°	T = 273 K
V = 1061.0 (3) Å^3	Block, colorless
Z = 2	0.37 × 0.33 × 0.15 mm

Data collection

Bruker SMART CCD area-detector diffractometer	1868 independent reflections
Radiation source: fine-focus sealed tube	1031 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.042
φ and ω scans	θmax = 25.1°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −10→10
Tmin = 0.971, Tmax = 0.988	k = −6→6
5177 measured reflections	l = −23→11

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)] = 0.046	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.121	H-atom parameters constrained
S = 0.99	w = 1/[σ^2(Fo^2) + (0.0505P)^2] where P = (Fo^2 + 2Fc^2)/3
1868 reflections	(Δ/σ)max < 0.001
136 parameters	Δρmax = 0.10 e Å^−3
0 restraints	Δρmin = −0.12 e Å^−3

Special details

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	0.2816 (2)	0.9484 (3)	0.08370 (9)	0.0617 (5)
O1	0.29043 (17)	1.1226 (2)	0.03499 (7)	0.0710 (5)
C1	0.4221 (3)	1.2525 (4)	0.05003 (11)	0.0651 (7)
H1A	0.5076	1.1527	0.0527	0.078*
H1B	0.4185	1.3296	0.0928	0.078*
C2	0.4328 (2)	1.4251 (3)	−0.00515 (11)	0.0621 (6)
H2A	0.4349	1.3451	−0.0475	0.075*
H2B	0.3453	1.5207	−0.0079	0.075*
C3	0.1568 (3)	0.8486 (4)	0.07499 (10)	0.0578 (6)
H3	0.0902	0.9063	0.0414	0.069*
C4	0.1082 (2)	0.6522 (3)	0.11266 (10)	0.0515 (6)
C5	−0.0180 (3)	0.5460 (4)	0.08575 (11)	0.0639 (6)
H5	−0.0691	0.6097	0.0481	0.077*
C6	−0.0726 (3)	0.3454 (4)	0.11292 (12)	0.0716 (7)
H6	−0.1583	0.2776	0.0935	0.086*
C7	0.0009 (3)	0.2513 (4)	0.16784 (12)	0.0670 (7)
H7	−0.0326	0.1145	0.1847	0.080*
C8	0.1274 (2)	0.3570 (3)	0.19992 (11)	0.0553 (6)
C9	0.1829 (2)	0.5628 (3)	0.17299 (10)	0.0496 (6)
C10	0.3057 (2)	0.6688 (4)	0.20813 (11)	0.0605 (6)
H10	0.3429	0.8035	0.1915	0.073*
C11	0.3708 (3)	0.5778 (4)	0.26582 (12)	0.0726 (7)
H11	0.4514	0.6509	0.2881	0.087*
C12	0.3168 (3)	0.3742 (4)	0.29177 (13)	0.0786 (8)
H12	0.3613	0.3134	0.3314	0.094*
C13	0.1998 (3)	0.2660 (4)	0.25924 (13)	0.0712 (7)
H13	0.1666	0.1292	0.2763	0.085*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0703 (14)	0.0557 (11)	0.0602 (12)	−0.0035 (10)	0.0109 (10)	0.0136 (9)
O1	0.0752 (12)	0.0672 (10)	0.0696 (11)	−0.0148 (9)	0.0007 (8)	0.0229 (8)
C1	0.0700 (18)	0.0629 (15)	0.0626 (15)	−0.0090 (13)	0.0065 (12)	0.0065 (12)
C2	0.0685 (16)	0.0572 (14)	0.0603 (14)	−0.0061 (11)	0.0040 (12)	0.0096 (11)
C3	0.0609 (16)	0.0590 (14)	0.0538 (14)	0.0015 (12)	0.0072 (11)	0.0073 (11)
C4	0.0541 (14)	0.0513 (13)	0.0503 (13)	0.0003 (11)	0.0113 (11)	−0.0043 (11)
C5	0.0660 (16)	0.0705 (16)	0.0558 (14)	−0.0066 (14)	0.0085 (12)	−0.0017 (12)
C6	0.0682 (17)	0.0765 (17)	0.0709 (17)	−0.0187 (14)	0.0107 (13)	−0.0089 (14)
C7	0.0762 (18)	0.0506 (14)	0.0781 (18)	−0.0114 (13)	0.0290 (14)	−0.0064 (13)
C8	0.0615 (16)	0.0474 (13)	0.0595 (14)	0.0048 (12)	0.0204 (12)	0.0014 (11)
C9	0.0507 (13)	0.0489 (13)	0.0508 (13)	0.0059 (11)	0.0132 (11)	−0.0002 (10)
C10	0.0585 (15)	0.0623 (14)	0.0607 (15)	−0.0027 (12)	0.0060 (12)	0.0076 (12)
C11	0.0614 (16)	0.0891 (18)	0.0664 (17)	0.0012 (14)	−0.0001 (13)	0.0146 (14)
C12	0.0694 (19)	0.094 (2)	0.0727 (17)	0.0194 (16)	0.0103 (14)	0.0299 (15)
C13	0.0727 (19)	0.0606 (16)	0.0838 (19)	0.0141 (14)	0.0278 (15)	0.0187 (14)

Geometric parameters (Å, º)

N1—C3	1.274 (3)	C6—C7	1.355 (3)
N1—O1	1.417 (2)	C6—H6	0.9300
O1—C1	1.429 (2)	C7—C8	1.412 (3)
C1—C2	1.506 (3)	C7—H7	0.9300
C1—H1A	0.9700	C8—C13	1.413 (3)
C1—H1B	0.9700	C8—C9	1.428 (3)
C2—C2^i	1.504 (4)	C9—C10	1.413 (3)
C2—H2A	0.9700	C10—C11	1.361 (3)
C2—H2B	0.9700	C10—H10	0.9300
C3—C4	1.463 (3)	C11—C12	1.404 (3)
C3—H3	0.9300	C11—H11	0.9300
C4—C5	1.375 (3)	C12—C13	1.357 (3)
C4—C9	1.434 (3)	C12—H12	0.9300
C5—C6	1.402 (3)	C13—H13	0.9300
C5—H5	0.9300
C3—N1—O1	109.64 (17)	C7—C6—H6	120.4
N1—O1—C1	109.40 (15)	C5—C6—H6	120.4
O1—C1—C2	107.81 (17)	C6—C7—C8	121.3 (2)
O1—C1—H1A	110.1	C6—C7—H7	119.4
C2—C1—H1A	110.1	C8—C7—H7	119.4
O1—C1—H1B	110.1	C7—C8—C13	121.4 (2)
C2—C1—H1B	110.1	C7—C8—C9	119.82 (19)
H1A—C1—H1B	108.5	C13—C8—C9	118.7 (2)
C2^i—C2—C1	113.0 (2)	C10—C9—C8	118.12 (18)
C2^i—C2—H2A	109.0	C10—C9—C4	123.95 (19)
C1—C2—H2A	109.0	C8—C9—C4	117.91 (18)
C2^i—C2—H2B	109.0	C11—C10—C9	121.4 (2)
C1—C2—H2B	109.0	C11—C10—H10	119.3
H2A—C2—H2B	107.8	C9—C10—H10	119.3
N1—C3—C4	126.4 (2)	C10—C11—C12	120.3 (2)
N1—C3—H3	116.8	C10—C11—H11	119.9
C4—C3—H3	116.8	C12—C11—H11	119.9
C5—C4—C9	119.1 (2)	C13—C12—C11	120.2 (2)
C5—C4—C3	115.5 (2)	C13—C12—H12	119.9
C9—C4—C3	125.35 (19)	C11—C12—H12	119.9
C4—C5—C6	122.5 (2)	C12—C13—C8	121.3 (2)
C4—C5—H5	118.8	C12—C13—H13	119.4
C6—C5—H5	118.8	C8—C13—H13	119.4
C7—C6—C5	119.2 (2)
C3—N1—O1—C1	172.74 (18)	C7—C8—C9—C4	−1.3 (3)
N1—O1—C1—C2	176.28 (17)	C13—C8—C9—C4	179.82 (19)
O1—C1—C2—C2^i	179.6 (2)	C5—C4—C9—C10	−174.4 (2)
O1—N1—C3—C4	176.55 (19)	C3—C4—C9—C10	7.1 (3)
N1—C3—C4—C5	−167.4 (2)	C5—C4—C9—C8	4.1 (3)
N1—C3—C4—C9	11.1 (3)	C3—C4—C9—C8	−174.37 (19)
C9—C4—C5—C6	−3.6 (3)	C8—C9—C10—C11	0.4 (3)
C3—C4—C5—C6	175.0 (2)	C4—C9—C10—C11	179.0 (2)
C4—C5—C6—C7	0.1 (4)	C9—C10—C11—C12	0.2 (3)
C5—C6—C7—C8	2.9 (3)	C10—C11—C12—C13	0.4 (4)
C6—C7—C8—C13	176.6 (2)	C11—C12—C13—C8	−1.6 (4)
C6—C7—C8—C9	−2.2 (3)	C7—C8—C13—C12	−176.6 (2)
C7—C8—C9—C10	177.3 (2)	C9—C8—C13—C12	2.2 (3)
C13—C8—C9—C10	−1.6 (3)

Symmetry code: (i) −x+1, −y+3, −z.