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Acta Cryst. (2009). E65, o1160    [ doi:10.1107/S1600536809014986 ]

5,5'-Dimethoxy-2,2'-[(pentane-1,5-diyldioxy)bis(nitrilomethylidyne)]diphenol

Y.-X. Sun, L. Li, W.-K. Dong, J.-C. Wu and J.-F. Tong

Abstract top

The molecule of the title compound, C21H26N2O6, which lies across a crystallographic inversion centre, crystallizes with two unique half-molecules in the symmetric unit and adopts a linear configuration and the imino group is coplanar with the aromatic ring, making a dihedral angle of 3.26 (3)°. Strong intramolecular O-H...N and weak intermolecular O-H...O and C-H...O hydrogen bonds and weak intermolecular [pi]-[pi] stacking interactions [centroid-centroid distance = 4.419 (2) Å]establish an infinite three-dimensional supramolecular structure.

Comment top

Salen-type compound and its derivatives are among the most prevalent mixed-donor ligands in the field of modern coordination chemistry in which there has been growing interest, mainly because of their interesting and important properties, including optical features (Lacroix, 2001), catalytic activity in hydration of acrylonitrile (Onda et al., 2007) and magnetic properties (Nishijo et al., 2006). They can also be used as elemental building blocks for construction of supramolecular structures via intermolecular hydrogen bonding or short contact interaction (Sun et al., 2004). Many salen-type complexes have been structurally characterized, but only a relatively small number of free salen-type compounds have had their X-ray structures reported (Akine et al., 2005). In order to extent our work (Dong et al., 2008a) on structural characterization of salen-type bisoxime compounds, we reported the synthesis and structure of the title compound in this paper in Fig. 1.

The molecule of the title salen-type bisoxime compound lies across a crystallographic inversion centre and adopts a linear configuration with respect to the azomethine C=N bonds. The dihedral angle formed by the two benzene rings is 23.4 (2) °, and the imino group is coplanar with the aromatic ring. This structure is different from our previous work reported in which the molecules assume W-shaped configuration (Dong et al., 2008a) or E configuration (Dong et al., 2008b).

There are two strong intramolecular O—H···N hydrogen bonds involving the hydroxy group and oxime N atoms in each molecule. In the crystal structure, intermolecular C—H···O and O—H···O hydrogen bonds link the each molecule to three others, and weak intermolecular π-π stacking interaction between the neighbouring benzene rings (the inter-molecular plane-to-plane dihedral angle along b axis is 0.48 (4) °). Thus, an infinite three-dimensional supramolecular structure is established (Fig. 2).

Related literature top

For the properties and uses of salen-type compounds, see: Lacroix (2001); Nishijo et al. (2006); Onda et al. (2007); Sun et al. (2004). For the structures of free salen-type compounds, see: Akine et al. (2005). For related sturctures, see: Dong et al. (2008a,b, 2009).

Experimental top

5,5'-Dimethoxy-2,2'-[(pentane-1,5-diyldioxy)bis(nitrilomethylidyne)]diphenol was synthesized according to an analogous method reported earlier (Dong et al., 2009). To an ethanol solution (10 ml) of 4-methoxy-2-hydroxybenzaldehyde (304.3 mg, 2.00 mmol) was added an ethanol solution (6 ml) of 1,5-bis(aminooxy)pentane (134.2 mg, 1.00 mmol). The reaction mixture was stirred at 328 K for 5 h. The formed precipitate was separated by filtration, and washed successively with ethanol and ethanol-hexane (1:4), respectively. The product was dried under vacuum to yield 204.2 mg of the title compound. Yield, 51.8%. mp. 349–350 K. Anal. Calc. for C21H26N2O6: C, 62.67; H, 6.51; N, 9.96. Found: C, 62.79; H, 6.68; N, 6.83.

Colorless block-like single crystals suitable for X-ray diffraction studies were obtained after about two months by slow evaporation from an ethanol solution of the title compound.

Refinement top

Non-H atoms were refined anisotropically. H atoms were treated as riding atoms with distances C—H = 0.97 (CH2), 0.93 Å (CH), O—H = 0.82 Å and Uiso(H) = 1.2 Ueq(C) and 1.5 Ueq(O).

Computing details top

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound with atom numbering scheme [Symmetry codes: #1 - x + 1,-y + 1,-z + 1]. Displacement ellipsoids for non-hydrogen atoms are drawn at the 30% probability level.
[Figure 2] Fig. 2. Part of the supramolecular structure of the title compound. Intra- and intermolecular hydrogen bonds are shown as dashed lines.
5,5'-Dimethoxy-2,2'-[(pentane-1,5-diyldioxy)bis(nitrilomethylidyne)]diphenol top
Crystal data top
C21H26N2O6Z = 2
Mr = 402.44F(000) = 428
Triclinic, P1Dx = 1.284 Mg m−3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 7.3324 (15) ÅCell parameters from 974 reflections
b = 7.6214 (17) Åθ = 2.9–23.1°
c = 20.372 (3) ŵ = 0.09 mm−1
α = 81.525 (1)°T = 298 K
β = 89.928 (2)°Block-like, colorless
γ = 67.870 (1)°0.43 × 0.28 × 0.14 mm
V = 1041.2 (3) Å3
Data collection top
Siemens SMART 1000 CCD area-detector
diffractometer		3618 independent reflections
Radiation source: fine-focus sealed tube1641 reflections with I > 2σ(I)
graphiteRint = 0.028
φ and ω scansθmax = 25.0°, θmin = 2.0°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		h = −8→8
Tmin = 0.961, Tmax = 0.987k = −9→8
5481 measured reflectionsl = −24→15
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.052Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.124H-atom parameters constrained
S = 1.01 w = 1/[σ2(Fo2) + (0.0371P)2]
where P = (Fo2 + 2Fc2)/3
3618 reflections(Δ/σ)max < 0.001
264 parametersΔρmax = 0.14 e Å−3
0 restraintsΔρmin = −0.18 e Å−3
Crystal data top
C21H26N2O6γ = 67.870 (1)°
Mr = 402.44V = 1041.2 (3) Å3
Triclinic, P1Z = 2
a = 7.3324 (15) ÅMo Kα radiation
b = 7.6214 (17) ŵ = 0.09 mm−1
c = 20.372 (3) ÅT = 298 K
α = 81.525 (1)°0.43 × 0.28 × 0.14 mm
β = 89.928 (2)°
Data collection top
Siemens SMART 1000 CCD area-detector
diffractometer		3618 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		1641 reflections with I > 2σ(I)
Tmin = 0.961, Tmax = 0.987Rint = 0.028
5481 measured reflectionsθmax = 25.0°
Refinement top
R[F2 > 2σ(F2)] = 0.052H-atom parameters constrained
wR(F2) = 0.124Δρmax = 0.14 e Å−3
S = 1.01Δρmin = −0.18 e Å−3
3618 reflectionsAbsolute structure: ?
264 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

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 (Å2) top
xyzUiso*/Ueq
N1−0.1725 (3)0.8216 (3)−0.07342 (10)0.0615 (6)
N20.8214 (3)0.4398 (3)0.28534 (10)0.0657 (6)
O10.0265 (3)0.7497 (3)−0.05195 (8)0.0749 (6)
O20.7701 (3)0.4917 (3)0.21730 (8)0.0800 (6)
O3−0.5543 (2)0.9488 (3)−0.06470 (8)0.0882 (7)
H3−0.44050.9249−0.05160.132*
O4−0.9588 (3)1.0916 (3)−0.25645 (9)0.0917 (7)
O50.8015 (2)0.3232 (3)0.41215 (8)0.0891 (7)
H50.76100.36330.37320.134*
O61.3399 (3)0.2041 (3)0.55807 (9)0.0906 (7)
C10.0438 (4)0.7272 (4)0.01908 (12)0.0678 (8)
H1A−0.01510.63870.03870.081*
H1B−0.02350.84970.03390.081*
C20.2584 (4)0.6508 (4)0.03966 (11)0.0699 (8)
H2A0.31560.73760.01730.084*
H2B0.32200.52790.02480.084*
C30.3029 (4)0.6250 (4)0.11341 (11)0.0651 (8)
H3A0.25700.52910.13570.078*
H3B0.23050.74490.12920.078*
C40.5200 (4)0.5643 (4)0.13208 (12)0.0662 (8)
H4A0.59300.44650.11510.079*
H4B0.56510.66210.11090.079*
C50.5645 (4)0.5332 (4)0.20517 (12)0.0692 (8)
H5A0.48610.64730.22330.083*
H5B0.53220.42720.22660.083*
C6−0.1984 (4)0.8436 (4)−0.13669 (12)0.0607 (7)
H6−0.08990.8147−0.16280.073*
C7−0.3954 (4)0.9133 (4)−0.16794 (12)0.0528 (7)
C8−0.5646 (4)0.9604 (4)−0.13165 (12)0.0599 (8)
C9−0.7468 (4)1.0168 (4)−0.16277 (13)0.0729 (9)
H9−0.85741.0445−0.13770.087*
C10−0.7693 (4)1.0334 (4)−0.23081 (14)0.0633 (8)
C11−0.6068 (4)0.9916 (4)−0.26870 (13)0.0691 (8)
H11−0.62011.0020−0.31470.083*
C12−0.4233 (4)0.9337 (4)−0.23622 (12)0.0661 (8)
H12−0.31320.9071−0.26150.079*
C13−0.9911 (4)1.1077 (4)−0.32617 (14)0.0919 (11)
H13A−0.93391.1923−0.34890.138*
H13B−1.13031.1582−0.33760.138*
H13C−0.93100.9834−0.33920.138*
C140.9944 (4)0.4320 (4)0.29886 (13)0.0642 (8)
H141.06490.46600.26470.077*
C151.0837 (4)0.3722 (4)0.36552 (12)0.0534 (7)
C160.9873 (4)0.3203 (4)0.42012 (13)0.0611 (8)
C171.0779 (4)0.2636 (4)0.48276 (13)0.0727 (9)
H171.01240.22800.51820.087*
C181.2649 (4)0.2590 (4)0.49373 (13)0.0627 (8)
C191.3648 (4)0.3074 (4)0.44140 (13)0.0669 (8)
H191.49220.30230.44830.080*
C201.2727 (4)0.3637 (4)0.37860 (13)0.0670 (8)
H201.34020.39750.34340.080*
C211.5276 (4)0.2114 (4)0.57277 (13)0.0959 (11)
H21A1.62820.11710.55240.144*
H21B1.55520.18530.62000.144*
H21C1.52510.33660.55580.144*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0551 (15)0.0683 (17)0.0543 (15)−0.0171 (13)−0.0062 (11)−0.0058 (12)
N20.0634 (16)0.0769 (18)0.0557 (15)−0.0256 (14)−0.0110 (12)−0.0096 (12)
O10.0562 (12)0.1062 (17)0.0539 (12)−0.0218 (11)−0.0072 (9)−0.0116 (10)
O20.0725 (14)0.1078 (18)0.0599 (12)−0.0379 (12)−0.0111 (10)−0.0041 (11)
O30.0699 (13)0.140 (2)0.0495 (12)−0.0358 (13)0.0041 (10)−0.0105 (11)
O40.0660 (14)0.128 (2)0.0742 (14)−0.0307 (13)−0.0134 (11)−0.0099 (12)
O50.0537 (12)0.150 (2)0.0738 (13)−0.0519 (13)0.0011 (9)−0.0124 (12)
O60.0790 (15)0.132 (2)0.0708 (14)−0.0603 (14)−0.0180 (11)0.0084 (12)
C10.0641 (19)0.078 (2)0.0539 (18)−0.0198 (17)−0.0075 (14)−0.0074 (15)
C20.0615 (19)0.083 (2)0.0596 (18)−0.0226 (17)−0.0068 (14)−0.0071 (15)
C30.0636 (19)0.066 (2)0.0589 (18)−0.0185 (16)−0.0073 (14)−0.0055 (14)
C40.068 (2)0.065 (2)0.0620 (18)−0.0220 (16)−0.0093 (14)−0.0086 (14)
C50.064 (2)0.072 (2)0.0655 (19)−0.0217 (17)−0.0124 (15)−0.0053 (15)
C60.0586 (18)0.069 (2)0.0511 (17)−0.0209 (16)0.0053 (14)−0.0088 (14)
C70.0553 (18)0.0558 (19)0.0467 (16)−0.0212 (15)−0.0018 (14)−0.0061 (13)
C80.0620 (19)0.072 (2)0.0433 (17)−0.0251 (16)0.0005 (14)−0.0045 (14)
C90.0581 (19)0.104 (3)0.0542 (19)−0.0273 (18)0.0038 (14)−0.0135 (16)
C100.0546 (19)0.068 (2)0.063 (2)−0.0212 (16)−0.0073 (16)−0.0059 (15)
C110.073 (2)0.082 (2)0.0518 (18)−0.0293 (18)−0.0038 (16)−0.0088 (15)
C120.0633 (19)0.083 (2)0.0512 (18)−0.0259 (17)0.0038 (14)−0.0120 (15)
C130.089 (2)0.100 (3)0.080 (2)−0.029 (2)−0.0296 (18)−0.0106 (19)
C140.0625 (19)0.070 (2)0.0630 (19)−0.0279 (17)0.0019 (15)−0.0109 (15)
C150.0495 (17)0.0574 (19)0.0555 (17)−0.0213 (14)0.0037 (13)−0.0139 (13)
C160.0417 (16)0.079 (2)0.0681 (19)−0.0269 (15)0.0022 (14)−0.0186 (15)
C170.0602 (19)0.108 (3)0.0597 (19)−0.0455 (18)0.0014 (15)−0.0068 (17)
C180.0563 (18)0.073 (2)0.0621 (19)−0.0302 (16)−0.0057 (15)−0.0061 (15)
C190.0470 (17)0.083 (2)0.076 (2)−0.0294 (16)0.0010 (15)−0.0134 (16)
C200.0539 (18)0.085 (2)0.069 (2)−0.0357 (17)0.0067 (14)−0.0086 (16)
C210.075 (2)0.123 (3)0.097 (2)−0.054 (2)−0.0304 (18)0.003 (2)
Geometric parameters (Å, °) top
N1—C61.280 (2)C6—C71.449 (3)
N1—O11.396 (2)C6—H60.9300
N2—C141.276 (3)C7—C121.383 (3)
N2—O21.395 (2)C7—C81.398 (3)
O1—C11.432 (2)C8—C91.364 (3)
O2—C51.432 (3)C9—C101.378 (3)
O3—C81.354 (2)C9—H90.9300
O3—H30.8200C10—C111.379 (3)
O4—C101.367 (3)C11—C121.382 (3)
O4—C131.420 (3)C11—H110.9300
O5—C161.363 (2)C12—H120.9300
O5—H50.8200C13—H13A0.9600
O6—C181.365 (3)C13—H13B0.9600
O6—C211.431 (3)C13—H13C0.9600
C1—C21.493 (3)C14—C151.441 (3)
C1—H1A0.9700C14—H140.9300
C1—H1B0.9700C15—C201.387 (3)
C2—C31.506 (3)C15—C161.405 (3)
C2—H2A0.9700C16—C171.371 (3)
C2—H2B0.9700C17—C181.376 (3)
C3—C41.513 (3)C17—H170.9300
C3—H3A0.9700C18—C191.377 (3)
C3—H3B0.9700C19—C201.378 (3)
C4—C51.490 (3)C19—H190.9300
C4—H4A0.9700C20—H200.9300
C4—H4B0.9700C21—H21A0.9600
C5—H5A0.9700C21—H21B0.9600
C5—H5B0.9700C21—H21C0.9600
C6—N1—O1112.7 (2)C9—C8—C7120.7 (2)
C14—N2—O2111.7 (2)C8—C9—C10120.9 (3)
N1—O1—C1109.48 (18)C8—C9—H9119.5
N2—O2—C5110.15 (19)C10—C9—H9119.5
C8—O3—H3109.5O4—C10—C9115.7 (3)
C10—O4—C13118.4 (2)O4—C10—C11124.0 (3)
C16—O5—H5109.5C9—C10—C11120.3 (2)
C18—O6—C21117.9 (2)C10—C11—C12117.9 (2)
O1—C1—C2107.6 (2)C10—C11—H11121.1
O1—C1—H1A110.2C12—C11—H11121.1
C2—C1—H1A110.2C11—C12—C7123.3 (3)
O1—C1—H1B110.2C11—C12—H12118.4
C2—C1—H1B110.2C7—C12—H12118.4
H1A—C1—H1B108.5O4—C13—H13A109.5
C1—C2—C3114.5 (2)O4—C13—H13B109.5
C1—C2—H2A108.6H13A—C13—H13B109.5
C3—C2—H2A108.6O4—C13—H13C109.5
C1—C2—H2B108.6H13A—C13—H13C109.5
C3—C2—H2B108.6H13B—C13—H13C109.5
H2A—C2—H2B107.6N2—C14—C15121.9 (2)
C2—C3—C4113.2 (2)N2—C14—H14119.1
C2—C3—H3A108.9C15—C14—H14119.1
C4—C3—H3A108.9C20—C15—C16116.6 (2)
C2—C3—H3B108.9C20—C15—C14120.6 (2)
C4—C3—H3B108.9C16—C15—C14122.8 (2)
H3A—C3—H3B107.8O5—C16—C17118.2 (2)
C5—C4—C3113.1 (2)O5—C16—C15120.9 (2)
C5—C4—H4A109.0C17—C16—C15121.0 (2)
C3—C4—H4A109.0C16—C17—C18120.6 (2)
C5—C4—H4B109.0C16—C17—H17119.7
C3—C4—H4B109.0C18—C17—H17119.7
H4A—C4—H4B107.8O6—C18—C17115.9 (2)
O2—C5—C4108.8 (2)O6—C18—C19124.0 (2)
O2—C5—H5A109.9C17—C18—C19120.1 (2)
C4—C5—H5A109.9C18—C19—C20118.8 (2)
O2—C5—H5B109.9C18—C19—H19120.6
C4—C5—H5B109.9C20—C19—H19120.6
H5A—C5—H5B108.3C19—C20—C15122.9 (2)
N1—C6—C7120.5 (2)C19—C20—H20118.6
N1—C6—H6119.8C15—C20—H20118.6
C7—C6—H6119.8O6—C21—H21A109.5
C12—C7—C8116.8 (2)O6—C21—H21B109.5
C12—C7—C6120.5 (2)H21A—C21—H21B109.5
C8—C7—C6122.6 (2)O6—C21—H21C109.5
O3—C8—C9117.5 (2)H21A—C21—H21C109.5
O3—C8—C7121.7 (2)H21B—C21—H21C109.5
C6—N1—O1—C1−179.4 (2)C9—C10—C11—C12−0.1 (4)
C14—N2—O2—C5−169.4 (2)C10—C11—C12—C71.0 (4)
N1—O1—C1—C2−179.9 (2)C8—C7—C12—C11−2.0 (4)
O1—C1—C2—C3177.9 (2)C6—C7—C12—C11177.2 (3)
C1—C2—C3—C4−174.9 (2)O2—N2—C14—C15−176.9 (2)
C2—C3—C4—C5−178.3 (2)N2—C14—C15—C20179.5 (3)
N2—O2—C5—C4−173.06 (19)N2—C14—C15—C16−0.6 (4)
C3—C4—C5—O2−175.4 (2)C20—C15—C16—O5−179.7 (2)
O1—N1—C6—C7178.8 (2)C14—C15—C16—O50.4 (4)
N1—C6—C7—C12−178.8 (2)C20—C15—C16—C17−0.3 (4)
N1—C6—C7—C80.4 (4)C14—C15—C16—C17179.8 (2)
C12—C7—C8—O3−178.9 (2)O5—C16—C17—C18−179.6 (3)
C6—C7—C8—O31.9 (4)C15—C16—C17—C180.9 (4)
C12—C7—C8—C92.3 (4)C21—O6—C18—C17−175.2 (3)
C6—C7—C8—C9−176.9 (2)C21—O6—C18—C195.0 (4)
O3—C8—C9—C10179.5 (2)C16—C17—C18—O6178.8 (2)
C7—C8—C9—C10−1.6 (4)C16—C17—C18—C19−1.4 (4)
C13—O4—C10—C9−178.8 (2)O6—C18—C19—C20−179.0 (2)
C13—O4—C10—C110.9 (4)C17—C18—C19—C201.2 (4)
C8—C9—C10—O4−179.8 (3)C18—C19—C20—C15−0.6 (4)
C8—C9—C10—C110.5 (4)C16—C15—C20—C190.1 (4)
O4—C10—C11—C12−179.8 (2)C14—C15—C20—C19−180.0 (2)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O3—H3···N10.821.902.610 (3)144
O5—H5···N20.821.902.628 (3)147
O3—H3···O3i0.822.683.045 (3)109
C2—H2A···O3ii0.972.583.533 (4)168
C19—H19···O5ii0.932.443.300 (4)154
Symmetry codes: (i) −x−1, −y+2, −z; (ii) x+1, y, z.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O3—H3···N10.821.902.610 (3)144
O5—H5···N20.821.902.628 (3)147
O3—H3···O3i0.822.683.045 (3)109
C2—H2A···O3ii0.972.583.533 (4)168
C19—H19···O5ii0.932.443.300 (4)154
Symmetry codes: (i) −x−1, −y+2, −z; (ii) x+1, y, z.
Acknowledgements top

This work was supported by the Foundation of the Education Department of Gansu Province (No. 0604–01) and the 'Qing Lan' Talent Engineering Funds of Lanzhou Jiaotong University (No. QL-03–01 A), which are gratefully acknowledged.

references
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