N,N′-Bis(2-methoxy­benzyl­idene) adducts of ethane-1,2-di­amine, propane-1,3-di­amine and butane-1,4-di­amine

We have isolated and crystallographically characterized the three homologous compounds N,N′-bis(2-methoxy­benzyl­idene)­ethane-1,2-di­amine (MeSalen), C₁₈H₂₀N₂O₂, N,N′-bis(2-methoxy­benzyl­idene)­propane-1,3-di­amine (MeSalpr), C₁₉H₂₂N₂O₂, and N,N′-bis(2-methoxy­benzyl­idene)­butane-1,4-di­amine (MeSalbu), C₂₀H₂₄N₂O₂. In contrast with MeSalpr, the mol­ecules of MeSalen and MeSalbu, which have an even number of methyl­ene units, have crystallographic symmetry. Comparing these methoxy-substituted species with their hydroxy equivalents shows that the aryl rings rotate upon removal of the O—H...N hydrogen bonds. The packing of MeSalen and MeSalpr is controlled by C—H...π interactions, whereas that of MeSalbu has only van der Waals contacts.

S1. Comment

We have been investigating the structures adopted by the complexes of the late transition metals Ni, Cu and Zn (Reglinski et al., 2002a,b) with symmetric salicylidene Schiff base ligands, as a function of the number of methylene units (n = 2, 3 or 4) between the two imine groups. As part of our on-going study, we recently turned our attention to the preparation of the homologous compounds derived from o-anisaldehyde. As part of the characterization process, we have isolated and crystallographically characterized the three title compounds, namely N,N-bis(2-methoxybenzylidene)ethane-1,2-diamine (MeSalen), (I) (Billman & Dorman, 1963), N,N-bis(2-methoxybenzylidene)propane-1,3-diamine (MeSalpr), (II) (Moneta et al., 1988), and N,N-bis(2-methoxybenzylidene)butane-1,4-diamine (MeSalbu), (III). A search of the December 2003 release of the Cambridge Structural Database (Allen, 2002) shows that no higher homologues have been reported to date. The availability of the structures of these three compounds has allowed us to make some simple but instructive observations regarding the effects of methylene chain lengths and the effects of hydrogen bonding in these systems, compared with the parent salicylidene complexes, N,N-bis(2-hydroxybenzylidene)ethane-1,2-diamine (salen; Pahor et al., 1978), N,N-bis(2-hydroxybenzylidene)propane-1,3-diamine (Salpr; Elderman et al., 1991) and N,N-bis(2-hydroxybenzylidene)butane-1,4-diamine (Salbu; Kennedy & Reglinski, 2001), respectively. \sch

The three title molecules adopt extended conformations, as shown in Figs. 1a, 1 b and 1c. In salen, (I), and Salbu, (III), where there are an even number of C atoms in the chain, the molecules lie about inversion centres and adopt an essentially planar extended conformation, with the methoxy moieties, of necessity, in a trans arrangement (Figs. 1a and 1c). However, for MeSalpr, (II), which has an odd number of C atoms in the linking chains, no symmetry is imposed by the P1 space group and a markedly non-planar conformation is adopted, with the methoxy moieties in a cis arrangement (Fig. 1 b).

In all three cases, replacement of the salicylidene moiety (–OH) with the anisaldehyde (–OMe) moiety has removed the stabilizing influence of intramolecular hydrogen bonding exhibited in the parent compounds (Pahor et al., 1978; Elderman et al., 1991; Kennedy & Reglinski, 2001), thus allowing a rotation of the aromatic ring such that the methoxy group is remote from the influence of the imine N atom. The lack of intramolecular hydrogen bonding does not alter the bond lengths or angles of the molecules. The largest systematic difference occurs in the angles to the OR group, where O1—C12—C11 is significantly smaller for the methoxy compounds than for their hydroxy equivalents [116.66 (8), 116.29 (14) and 115.75 (12)° for (I), (II) and (III), respectively, and 121.23, 121.68 and 121.37° for the equivalent literature species). This difference is simply explained by the steric effect of the Me group, which lies in the aryl ring plane.

Geometry calculations with PLATON (Spek, 2003) show that the packing of the three compounds is quite different. In MeSalen (Fig. 2), the molecules are linked by pairs of inversion-related C—H···π interactions to generate infinite chains extending in the b direction (details in Table 2). In MeSalpr, chains of inversion-related molecules are linked by two independent C—H···π interactions, as shown in Fig. 3a (details in Table 4). These chains are then linked to form sheets via pairs of inversion-related C17—H17···Cg1ⁱⁱⁱ interactions similar to those observed in MeSalen [Fig. 2; symmetry code: (iii) 1 − x, −y, 2 − z]. In this way, the three independent C—H···π interactions generate sheets of molecules in the [011] plane, as shown in the stereo pair (Fig. 3 b). By contrast, in MeSalbu (Fig. 4), with a short [4.6903 (2) Å] a axis, there are no signficant intermolecular interactions and contacts are all of the van der Waals variety.

S2. Experimental

MeSalen (Billman et al., 1963) and MeSalpr (Moneta et al., 1988) were prepared as previously reported and crystallized from chloroform: diethyl ether (Ratio?) by vapour diffusion. MeSalbu was prepared by refluxing 1,4-diaminobutane with two equivalents of ortho-anisaldehyde in methanol for 4 h. The solvent was removed, giving a yellow oil which was dissolved in a small amount of diethyl ether. Storing the solution in the freezer (258 K) overnight produced pale-yellow crystals which were recrystallized from chloroform:diethyl ether (Ratio?) by vapour diffussion. Analysis for MeSalbu: found: C 74.06, H 7.37, N 8.39%; expected for C₂₀H₂₄N₂O₂: C 74.05, H 7.46, N 8.64%; ¹H NMR (270 MHz, CDCl₃, δ, p.p.m.): 8.72 (s, 2H, C═N), 7.95 (d, 2H, arom), 7.39 (t, 2H, arom), 7.06 (t, 2H, arom), 6.91 (d, 2H, arom), 3.87 (s, 6H, OCH₃), 3.67 (t, 4H, N—CH₂–), 2.12 (p, 4H, –CH₂—CH₂–); ¹³C NMR (270 MHz, CDCl₃, δ, p.p.m.): 159, 157, 132, 128, 125, 121 (arom), 111 (C═N), 62 (MeO–), 56 (N—CH₂–), 29 (–CH₂—CH₂–); m.p. 332.5–334 K.

S3. Refinement

All H atoms were clearly revealed in difference maps and were then allowed for as riding atoms with idealized geometry in the final refinement cycles. C—H distances were in the range 0.93–0.99 Å, and U_iso(H) values were set to 1.2U_eq(C) for CH and CH₂ groups, and to 1.5U_eq(C) for CH₃ groups.

Computing details

For all compounds, data collection: DENZO (Otwinowski & Minor, 1997) and COLLECT (Nonius, 1998); cell refinement: DENZO and COLLECT; data reduction: DENZO; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997) and WinGX (Farrugia, 1997); molecular graphics: ORTEPII (Johnson, 1976) and PLATON (Spek 2003); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. Views of (a) MeSalen, (b) MeSalpr and (c) MeSalbu, with the atom-numbering schemes and with displacement ellipsoids drawn at the 50% probability level [symmetry code: (i) 1 − x, 1 − y, 1 − z Is added code correct?].
	Fig. 2. A chain of molecules in MeSalen. Cg1 denotes the centroid of the C11—C16 ring CORRECT? [symmetry code: (i) 1 − x, 2 − y, 1 − z].
	Fig. 3. (a) The chains of molecules in MeSalpr. Cg1 denotes the centroid of the C11—C16 ring and Cg2 denotes the centroid of the C21—C26 ring CORRECT? [symmetry codes: (i) 1 − x, 1 − y, 1 − z; (ii) 2 − x, 1 − y, 1 − z]. (b) A stereo view, showing a sheet of molecules in MeSalpr.
	Fig. 4. The crystal packing in MeSalbu.

(I) N,N-bis(2-methoxybenzylidene)ethane-1,2-diamine

Crystal data

C18H20N2O2	F(000) = 316
Mr = 296.36	Dx = 1.229 Mg m^−3
Monoclinic, P21/n	Melting point: 115 K
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71073 Å
a = 7.8727 (2) Å	Cell parameters from 1815 reflections
b = 8.9846 (2) Å	θ = 3.5–27.5°
c = 11.3927 (3) Å	µ = 0.08 mm^−1
β = 96.345 (1)°	T = 123 K
V = 800.90 (3) Å^3	Prism, colourless
Z = 2	0.5 × 0.5 × 0.4 mm

Data collection

Nonius Kappa CCD area-detector diffractometer	1627 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.037
Graphite monochromator	θmax = 27.5°, θmin = 3.5°
ϕ and ω scans	h = −10→10
9458 measured reflections	k = −11→10
1815 independent reflections	l = −14→14

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)] = 0.036	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.098	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0465P)^2 + 0.2339P] where P = (Fo^2 + 2Fc^2)/3
1815 reflections	(Δ/σ)max = 0.001
101 parameters	Δρmax = 0.26 e Å^−3
0 restraints	Δρmin = −0.17 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	Occ. (<1)
O1	0.19421 (9)	1.01402 (8)	0.40164 (6)	0.0244 (2)
N1	0.54895 (11)	0.68924 (9)	0.44732 (7)	0.0225 (2)
C1	0.52413 (13)	0.57243 (10)	0.53260 (9)	0.0239 (2)
H1A	0.4323	0.6017	0.5808	0.029*
H1B	0.6307	0.5581	0.5862	0.029*
C11	0.46301 (12)	0.92395 (10)	0.36019 (8)	0.0189 (2)
C12	0.33329 (12)	1.03201 (11)	0.34116 (8)	0.0189 (2)
C13	0.34965 (13)	1.14917 (11)	0.26279 (8)	0.0220 (2)
H13	0.2627	1.2227	0.2508	0.026*
C14	0.49296 (13)	1.15812 (12)	0.20244 (9)	0.0256 (2)
H14	0.5030	1.2377	0.1487	0.031*
C15	0.62209 (13)	1.05223 (12)	0.21951 (9)	0.0271 (2)
H15	0.7199	1.0589	0.1778	0.033*
C16	0.60611 (13)	0.93660 (11)	0.29828 (9)	0.0234 (2)
H16	0.6944	0.8644	0.3104	0.028*
C17	0.44935 (12)	0.80061 (10)	0.44419 (8)	0.0193 (2)
H17	0.3642	0.8047	0.4970	0.023*
C18	0.06398 (14)	1.12653 (13)	0.38476 (11)	0.0319 (3)
H18A	0.1122	1.2228	0.4116	0.048*
H18B	−0.0303	1.1007	0.4304	0.048*
H18C	0.0213	1.1327	0.3008	0.048*
Cg1	0.47785	1.04201	0.28073	0.01*	0.0

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0212 (4)	0.0244 (4)	0.0284 (4)	0.0041 (3)	0.0063 (3)	0.0062 (3)
N1	0.0270 (4)	0.0162 (4)	0.0244 (4)	0.0000 (3)	0.0029 (3)	0.0011 (3)
C1	0.0316 (5)	0.0168 (5)	0.0231 (5)	0.0007 (4)	0.0028 (4)	0.0021 (4)
C11	0.0207 (5)	0.0161 (5)	0.0194 (4)	−0.0019 (3)	0.0000 (3)	−0.0016 (3)
C12	0.0192 (4)	0.0187 (5)	0.0185 (4)	−0.0022 (3)	0.0003 (3)	−0.0016 (3)
C13	0.0235 (5)	0.0193 (5)	0.0223 (5)	0.0006 (4)	−0.0015 (4)	0.0016 (4)
C14	0.0296 (5)	0.0223 (5)	0.0246 (5)	−0.0039 (4)	0.0025 (4)	0.0053 (4)
C15	0.0263 (5)	0.0270 (5)	0.0293 (5)	−0.0028 (4)	0.0092 (4)	0.0022 (4)
C16	0.0228 (5)	0.0193 (5)	0.0283 (5)	0.0005 (4)	0.0037 (4)	−0.0005 (4)
C17	0.0214 (4)	0.0173 (4)	0.0189 (4)	−0.0019 (4)	0.0011 (3)	−0.0019 (3)
C18	0.0250 (5)	0.0333 (6)	0.0387 (6)	0.0097 (4)	0.0088 (4)	0.0093 (5)

Geometric parameters (Å, º)

O1—C12	1.3663 (11)	C13—C14	1.3869 (14)
O1—C18	1.4375 (12)	C13—H13	0.95
N1—C17	1.2693 (13)	C14—C15	1.3903 (15)
N1—C1	1.4579 (12)	C14—H14	0.95
C1—C1^i	1.5256 (19)	C15—C16	1.3876 (14)
C1—H1A	0.99	C15—H15	0.95
C1—H1B	0.99	C16—H16	0.95
C11—C16	1.3984 (14)	C17—H17	0.95
C11—C12	1.4084 (13)	C18—H18A	0.98
C11—C17	1.4759 (13)	C18—H18B	0.98
C12—C13	1.3954 (13)	C18—H18C	0.98
C12—O1—C18	116.67 (8)	C13—C14—H14	119.6
C17—N1—C1	117.28 (8)	C15—C14—H14	119.6
N1—C1—C1^i	109.52 (10)	C16—C15—C14	119.06 (9)
N1—C1—H1A	109.8	C16—C15—H15	120.5
C1^i—C1—H1A	109.8	C14—C15—H15	120.5
N1—C1—H1B	109.8	C15—C16—C11	121.52 (9)
C1^i—C1—H1B	109.8	C15—C16—H16	119.2
H1A—C1—H1B	108.2	C11—C16—H16	119.2
C16—C11—C12	118.50 (9)	N1—C17—C11	121.40 (9)
C16—C11—C17	120.57 (9)	N1—C17—H17	119.3
C12—C11—C17	120.93 (8)	C11—C17—H17	119.3
O1—C12—C13	123.21 (9)	O1—C18—H18A	109.5
O1—C12—C11	116.66 (8)	O1—C18—H18B	109.5
C13—C12—C11	120.13 (9)	H18A—C18—H18B	109.5
C14—C13—C12	119.91 (9)	O1—C18—H18C	109.5
C14—C13—H13	120.0	H18A—C18—H18C	109.5
C12—C13—H13	120.0	H18B—C18—H18C	109.5
C13—C14—C15	120.88 (9)
C17—N1—C1—C1^i	117.42 (11)	C12—C13—C14—C15	−0.50 (15)
C18—O1—C12—C13	−2.37 (14)	C13—C14—C15—C16	−0.07 (16)
C18—O1—C12—C11	178.32 (9)	C14—C15—C16—C11	0.33 (16)
C16—C11—C12—O1	178.79 (8)	C12—C11—C16—C15	−0.02 (15)
C17—C11—C12—O1	−1.68 (13)	C17—C11—C16—C15	−179.55 (9)
C16—C11—C12—C13	−0.55 (14)	C1—N1—C17—C11	−179.39 (8)
C17—C11—C12—C13	178.98 (8)	C16—C11—C17—N1	−12.87 (14)
O1—C12—C13—C14	−178.48 (9)	C12—C11—C17—N1	167.61 (9)
C11—C12—C13—C14	0.81 (14)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C17—H17···Cg1^ii	0.95	3.02	3.428	107

Symmetry code: (ii) −x+1, −y+2, −z+1.

(II) N,N-bis(2-methoxybenzylidene)propane-1,3-diamine

Crystal data

C19H22N2O2	Z = 2
Mr = 310.39	F(000) = 332
Triclinic, P1	Dx = 1.242 Mg m^−3
Hall symbol: -P 1	Melting point: 75 K
a = 8.8669 (2) Å	Mo Kα radiation, λ = 0.71073 Å
b = 9.9139 (3) Å	Cell parameters from 3737 reflections
c = 10.2724 (4) Å	θ = 2.0–27.5°
α = 101.140 (2)°	µ = 0.08 mm^−1
β = 92.341 (2)°	T = 123 K
γ = 109.442 (2)°	Prism, yellow
V = 830.05 (5) Å^3	0.4 × 0.3 × 0.2 mm

Data collection

Nonius Kappa CCD area-detector diffractometer	2279 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.063
Graphite monochromator	θmax = 27.6°, θmin = 2.0°
ϕ and ω scans	h = −11→11
12958 measured reflections	k = −12→12
3737 independent reflections	l = −12→13

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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.122	H-atom parameters constrained
S = 0.99	w = 1/[σ^2(Fo^2) + (0.0622P)^2] where P = (Fo^2 + 2Fc^2)/3
3737 reflections	(Δ/σ)max < 0.001
210 parameters	Δρmax = 0.24 e Å^−3
0 restraints	Δρmin = −0.22 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	Occ. (<1)
O1	0.77317 (12)	0.14374 (12)	1.07537 (10)	0.0282 (3)
O2	1.05404 (13)	0.82837 (12)	0.48211 (10)	0.0335 (3)
N1	0.50559 (15)	0.15505 (14)	0.75501 (12)	0.0241 (3)
N2	0.72851 (15)	0.43107 (14)	0.49220 (12)	0.0269 (3)
C1	0.46774 (19)	0.28801 (17)	0.75720 (15)	0.0250 (4)
H1A	0.5282	0.3644	0.8364	0.030*
H1B	0.3513	0.2668	0.7636	0.030*
C2	0.51246 (18)	0.34378 (17)	0.63030 (15)	0.0241 (4)
H2A	0.4581	0.2639	0.5515	0.029*
H2B	0.4726	0.4255	0.6274	0.029*
C3	0.69278 (18)	0.39654 (18)	0.62193 (15)	0.0269 (4)
H3A	0.7465	0.4850	0.6935	0.032*
H3B	0.7357	0.3195	0.6358	0.032*
C11	0.62244 (17)	0.01624 (17)	0.86792 (14)	0.0219 (4)
C12	0.72085 (17)	0.01728 (17)	0.97853 (14)	0.0228 (4)
C13	0.76131 (19)	−0.10518 (18)	0.98533 (15)	0.0280 (4)
H13	0.8282	−0.1042	1.0604	0.034*
C14	0.7039 (2)	−0.22879 (19)	0.88232 (16)	0.0316 (4)
H14	0.7313	−0.3126	0.8876	0.038*
C15	0.60735 (19)	−0.23176 (18)	0.77203 (16)	0.0293 (4)
H15	0.5694	−0.3165	0.7014	0.035*
C16	0.56651 (18)	−0.10966 (17)	0.76566 (15)	0.0253 (4)
H16	0.4993	−0.1118	0.6903	0.030*
C17	0.57997 (17)	0.14626 (17)	0.85944 (15)	0.0226 (4)
H17	0.6093	0.2261	0.9347	0.027*
C18	0.8520 (2)	0.1415 (2)	1.19883 (15)	0.0340 (4)
H18A	0.7847	0.0593	1.2341	0.051*
H18B	0.8696	0.2337	1.2632	0.051*
H18C	0.9559	0.1300	1.1837	0.051*
C21	0.87439 (17)	0.59806 (17)	0.36295 (14)	0.0217 (4)
C22	0.98652 (17)	0.73724 (17)	0.36087 (15)	0.0235 (4)
C23	1.02586 (18)	0.77502 (18)	0.24003 (15)	0.0256 (4)
H23	1.0991	0.8698	0.2392	0.031*
C24	0.95873 (19)	0.67495 (18)	0.12104 (15)	0.0289 (4)
H24	0.9878	0.7007	0.0388	0.035*
C25	0.8495 (2)	0.53756 (19)	0.12092 (16)	0.0317 (4)
H25	0.8039	0.4688	0.0391	0.038*
C26	0.80752 (18)	0.50115 (18)	0.24110 (15)	0.0267 (4)
H26	0.7309	0.4074	0.2404	0.032*
C27	0.83081 (17)	0.55534 (18)	0.48955 (15)	0.0240 (4)
H27	0.8805	0.6225	0.5714	0.029*
C28	1.1828 (2)	0.9626 (2)	0.48021 (17)	0.0428 (5)
H28A	1.2697	0.9397	0.4357	0.064*
H28B	1.2239	1.0176	0.5720	0.064*
H28C	1.1423	1.0218	0.4317	0.064*
Cg1	0.66373	−0.10698	0.87530 (6)	0.01*	0.0
Cg2	0.91709	0.63733	0.24115 (6)	0.01*	0.0

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0310 (7)	0.0254 (7)	0.0246 (6)	0.0049 (5)	−0.0008 (5)	0.0068 (5)
O2	0.0337 (7)	0.0264 (7)	0.0281 (6)	−0.0067 (5)	0.0009 (5)	0.0091 (5)
N1	0.0235 (7)	0.0216 (8)	0.0267 (7)	0.0039 (6)	0.0050 (6)	0.0108 (6)
N2	0.0262 (8)	0.0248 (8)	0.0313 (8)	0.0066 (6)	0.0068 (6)	0.0129 (6)
C1	0.0220 (9)	0.0224 (9)	0.0319 (9)	0.0071 (7)	0.0044 (7)	0.0099 (7)
C2	0.0228 (9)	0.0207 (9)	0.0287 (8)	0.0048 (7)	0.0024 (6)	0.0103 (7)
C3	0.0239 (9)	0.0258 (9)	0.0325 (9)	0.0054 (7)	0.0048 (7)	0.0156 (7)
C11	0.0190 (8)	0.0207 (9)	0.0257 (8)	0.0030 (7)	0.0076 (6)	0.0101 (7)
C12	0.0207 (8)	0.0234 (9)	0.0223 (8)	0.0024 (7)	0.0066 (6)	0.0086 (7)
C13	0.0263 (9)	0.0314 (10)	0.0285 (9)	0.0092 (8)	0.0044 (7)	0.0133 (8)
C14	0.0342 (10)	0.0259 (10)	0.0395 (10)	0.0135 (8)	0.0089 (8)	0.0118 (8)
C15	0.0315 (10)	0.0227 (9)	0.0307 (9)	0.0065 (8)	0.0062 (7)	0.0037 (7)
C16	0.0229 (9)	0.0250 (9)	0.0258 (8)	0.0034 (7)	0.0046 (7)	0.0085 (7)
C17	0.0197 (8)	0.0199 (9)	0.0242 (8)	0.0013 (7)	0.0051 (6)	0.0047 (7)
C18	0.0341 (10)	0.0366 (11)	0.0264 (9)	0.0053 (8)	−0.0045 (7)	0.0097 (8)
C21	0.0164 (8)	0.0227 (9)	0.0283 (9)	0.0072 (7)	0.0049 (6)	0.0097 (7)
C22	0.0176 (8)	0.0241 (9)	0.0284 (9)	0.0053 (7)	0.0013 (6)	0.0085 (7)
C23	0.0225 (9)	0.0253 (9)	0.0308 (9)	0.0058 (7)	0.0070 (7)	0.0139 (7)
C24	0.0273 (9)	0.0343 (11)	0.0287 (9)	0.0110 (8)	0.0083 (7)	0.0139 (8)
C25	0.0318 (10)	0.0290 (10)	0.0298 (9)	0.0060 (8)	0.0048 (7)	0.0040 (8)
C26	0.0217 (9)	0.0238 (9)	0.0345 (9)	0.0056 (7)	0.0064 (7)	0.0096 (8)
C27	0.0187 (8)	0.0241 (9)	0.0282 (8)	0.0045 (7)	0.0004 (7)	0.0089 (7)
C28	0.0450 (11)	0.0297 (11)	0.0351 (10)	−0.0123 (9)	−0.0004 (8)	0.0104 (8)

Geometric parameters (Å, º)

O1—C12	1.3674 (17)	C14—H14	0.95
O1—C18	1.4307 (17)	C15—C16	1.386 (2)
O2—C22	1.3674 (17)	C15—H15	0.95
O2—C28	1.4404 (19)	C16—H16	0.95
N1—C17	1.2688 (18)	C17—H17	0.95
N1—C1	1.4609 (19)	C18—H18A	0.98
N2—C27	1.270 (2)	C18—H18B	0.98
N2—C3	1.4600 (18)	C18—H18C	0.98
C1—C2	1.529 (2)	C21—C26	1.392 (2)
C1—H1A	0.99	C21—C22	1.412 (2)
C1—H1B	0.99	C21—C27	1.471 (2)
C2—C3	1.520 (2)	C22—C23	1.390 (2)
C2—H2A	0.99	C23—C24	1.382 (2)
C2—H2B	0.99	C23—H23	0.95
C3—H3A	0.99	C24—C25	1.383 (2)
C3—H3B	0.99	C24—H24	0.95
C11—C16	1.395 (2)	C25—C26	1.383 (2)
C11—C12	1.400 (2)	C25—H25	0.95
C11—C17	1.475 (2)	C26—H26	0.95
C12—C13	1.389 (2)	C27—H27	0.95
C13—C14	1.386 (2)	C28—H28A	0.98
C13—H13	0.95	C28—H28B	0.98
C14—C15	1.382 (2)	C28—H28C	0.98
C12—O1—C18	117.86 (13)	C15—C16—H16	119.4
C22—O2—C28	116.49 (12)	C11—C16—H16	119.4
C17—N1—C1	117.99 (13)	N1—C17—C11	122.23 (14)
C27—N2—C3	118.37 (13)	N1—C17—H17	118.9
N1—C1—C2	110.05 (12)	C11—C17—H17	118.9
N1—C1—H1A	109.7	O1—C18—H18A	109.5
C2—C1—H1A	109.7	O1—C18—H18B	109.5
N1—C1—H1B	109.7	H18A—C18—H18B	109.5
C2—C1—H1B	109.7	O1—C18—H18C	109.5
H1A—C1—H1B	108.2	H18A—C18—H18C	109.5
C3—C2—C1	112.78 (12)	H18B—C18—H18C	109.5
C3—C2—H2A	109.0	C26—C21—C22	117.86 (14)
C1—C2—H2A	109.0	C26—C21—C27	120.79 (14)
C3—C2—H2B	109.0	C22—C21—C27	121.34 (14)
C1—C2—H2B	109.0	O2—C22—C23	123.15 (14)
H2A—C2—H2B	107.8	O2—C22—C21	116.56 (13)
N2—C3—C2	110.90 (12)	C23—C22—C21	120.28 (14)
N2—C3—H3A	109.5	C24—C23—C22	120.16 (15)
C2—C3—H3A	109.5	C24—C23—H23	119.9
N2—C3—H3B	109.5	C22—C23—H23	119.9
C2—C3—H3B	109.5	C23—C24—C25	120.45 (15)
H3A—C3—H3B	108.0	C23—C24—H24	119.8
C16—C11—C12	118.70 (14)	C25—C24—H24	119.8
C16—C11—C17	120.75 (14)	C26—C25—C24	119.39 (15)
C12—C11—C17	120.55 (14)	C26—C25—H25	120.3
O1—C12—C13	123.50 (14)	C24—C25—H25	120.3
O1—C12—C11	116.29 (14)	C25—C26—C21	121.82 (15)
C13—C12—C11	120.22 (14)	C25—C26—H26	119.1
C14—C13—C12	119.84 (15)	C21—C26—H26	119.1
C14—C13—H13	120.1	N2—C27—C21	121.70 (14)
C12—C13—H13	120.1	N2—C27—H27	119.1
C15—C14—C13	120.84 (16)	C21—C27—H27	119.1
C15—C14—H14	119.6	O2—C28—H28A	109.5
C13—C14—H14	119.6	O2—C28—H28B	109.5
C14—C15—C16	119.25 (16)	H28A—C28—H28B	109.5
C14—C15—H15	120.4	O2—C28—H28C	109.5
C16—C15—H15	120.4	H28A—C28—H28C	109.5
C15—C16—C11	121.15 (15)	H28B—C28—H28C	109.5
C17—N1—C1—C2	133.21 (14)	C16—C11—C17—N1	−7.1 (2)
N1—C1—C2—C3	−66.40 (17)	C12—C11—C17—N1	172.39 (13)
C27—N2—C3—C2	128.37 (15)	C28—O2—C22—C23	−6.3 (2)
C1—C2—C3—N2	172.76 (13)	C28—O2—C22—C21	172.46 (15)
C18—O1—C12—C13	−10.2 (2)	C26—C21—C22—O2	−177.99 (13)
C18—O1—C12—C11	170.25 (13)	C27—C21—C22—O2	1.2 (2)
C16—C11—C12—O1	179.57 (13)	C26—C21—C22—C23	0.8 (2)
C17—C11—C12—O1	0.0 (2)	C27—C21—C22—C23	179.94 (13)
C16—C11—C12—C13	0.0 (2)	O2—C22—C23—C24	176.90 (14)
C17—C11—C12—C13	−179.52 (13)	C21—C22—C23—C24	−1.8 (2)
O1—C12—C13—C14	−179.58 (14)	C22—C23—C24—C25	1.3 (2)
C11—C12—C13—C14	−0.1 (2)	C23—C24—C25—C26	0.2 (2)
C12—C13—C14—C15	0.4 (2)	C24—C25—C26—C21	−1.2 (2)
C13—C14—C15—C16	−0.7 (2)	C22—C21—C26—C25	0.7 (2)
C14—C15—C16—C11	0.6 (2)	C27—C21—C26—C25	−178.42 (14)
C12—C11—C16—C15	−0.3 (2)	C3—N2—C27—C21	179.51 (13)
C17—C11—C16—C15	179.23 (13)	C26—C21—C27—N2	−1.8 (2)
C1—N1—C17—C11	179.40 (13)	C22—C21—C27—N2	179.08 (14)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C1—H1B···Cg2^i	0.99	2.84	3.725	149
C23—H23···Cg1^ii	0.95	3.05	3.944	157
C17—H17···Cg1^iii	0.95	3.23	3.546	102

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+2, −y+1, −z+1; (iii) −x+1, −y, −z+2.

(III) N,N-bis(2-methoxybenzylidene)butane-1,4-diamine

Crystal data

C20H24N2O2	F(000) = 348
Mr = 324.41	Dx = 1.221 Mg m^−3
Monoclinic, P21/n	Melting point: 60 K
Hall symbol: -P 2yn	Mo Kα radiation, λ = 0.71073 Å
a = 4.6903 (2) Å	Cell parameters from 2004 reflections
b = 14.2387 (6) Å	θ = 2.1–27.5°
c = 13.2170 (5) Å	µ = 0.08 mm^−1
β = 91.002 (2)°	T = 123 K
V = 882.55 (6) Å^3	Needle, pale yellow
Z = 2	0.40 × 0.15 × 0.10 mm

Data collection

Nonius Kappa CCD area-detector diffractometer	1303 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.046
Graphite monochromator	θmax = 27.5°, θmin = 2.1°
ϕ and ω scans	h = −6→6
10154 measured reflections	k = −18→18
2004 independent reflections	l = −17→17

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.042	H-atom parameters constrained
wR(F^2) = 0.103	w = 1/[σ^2(Fo^2) + (0.0411P)^2 + 0.144P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max < 0.001
2004 reflections	Δρmax = 0.19 e Å^−3
111 parameters	Δρmin = −0.19 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.021 (4)

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	0.6705 (2)	0.39640 (8)	0.30317 (8)	0.0288 (3)
O1	1.0906 (2)	0.15552 (7)	0.33652 (7)	0.0420 (3)
C1	0.4697 (3)	0.41660 (10)	0.38382 (10)	0.0284 (3)
H1A	0.4272	0.3582	0.4213	0.034*
H1B	0.2889	0.4407	0.3541	0.034*
C2	0.5965 (3)	0.48897 (9)	0.45585 (10)	0.0268 (3)
H2A	0.6335	0.5476	0.4180	0.032*
H2B	0.7815	0.4654	0.4826	0.032*
C11	0.9857 (3)	0.28276 (10)	0.22940 (10)	0.0268 (3)
C12	1.1410 (3)	0.20003 (10)	0.24681 (10)	0.0308 (4)
C13	1.3370 (3)	0.16890 (11)	0.17602 (11)	0.0356 (4)
H13	1.4399	0.1123	0.1872	0.043*
C14	1.3799 (3)	0.22110 (11)	0.08954 (12)	0.0385 (4)
H14	1.5146	0.2002	0.0416	0.046*
C15	1.2308 (3)	0.30294 (11)	0.07162 (11)	0.0380 (4)
H15	1.2629	0.3383	0.0119	0.046*
C16	1.0337 (3)	0.33327 (10)	0.14122 (10)	0.0318 (4)
H16	0.9297	0.3894	0.1286	0.038*
C17	0.7745 (3)	0.31425 (10)	0.30313 (10)	0.0267 (3)
H17	0.7132	0.2710	0.3530	0.032*
C18	1.2349 (4)	0.06902 (12)	0.35660 (13)	0.0512 (5)
H18A	1.1717	0.0217	0.3073	0.077*
H18B	1.1908	0.0476	0.4250	0.077*
H18C	1.4410	0.0784	0.3513	0.077*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0274 (7)	0.0315 (7)	0.0276 (7)	−0.0003 (5)	0.0046 (5)	−0.0048 (5)
O1	0.0522 (7)	0.0381 (6)	0.0359 (6)	0.0136 (5)	0.0082 (5)	0.0020 (5)
C1	0.0234 (7)	0.0311 (8)	0.0308 (8)	−0.0003 (6)	0.0048 (6)	−0.0029 (6)
C2	0.0220 (7)	0.0276 (8)	0.0310 (8)	−0.0005 (6)	0.0042 (6)	−0.0015 (6)
C11	0.0233 (7)	0.0291 (8)	0.0280 (8)	−0.0046 (6)	0.0013 (6)	−0.0081 (6)
C12	0.0280 (8)	0.0334 (9)	0.0310 (8)	−0.0027 (6)	0.0009 (6)	−0.0088 (6)
C13	0.0290 (8)	0.0365 (9)	0.0414 (9)	−0.0005 (7)	0.0028 (7)	−0.0142 (7)
C14	0.0305 (8)	0.0457 (10)	0.0398 (9)	−0.0083 (7)	0.0124 (7)	−0.0195 (7)
C15	0.0415 (9)	0.0426 (9)	0.0303 (9)	−0.0116 (8)	0.0106 (7)	−0.0075 (7)
C16	0.0314 (8)	0.0330 (8)	0.0310 (8)	−0.0051 (7)	0.0029 (6)	−0.0058 (6)
C17	0.0251 (7)	0.0293 (8)	0.0257 (8)	−0.0033 (6)	0.0020 (6)	−0.0034 (6)
C18	0.0665 (12)	0.0401 (10)	0.0469 (10)	0.0193 (9)	−0.0004 (9)	−0.0002 (8)

Geometric parameters (Å, º)

N1—C17	1.2673 (17)	C12—C13	1.3954 (19)
N1—C1	1.4634 (17)	C13—C14	1.381 (2)
O1—C12	1.3686 (17)	C13—H13	0.95
O1—C18	1.4279 (18)	C14—C15	1.378 (2)
C1—C2	1.5172 (18)	C14—H14	0.95
C1—H1A	0.99	C15—C16	1.384 (2)
C1—H1B	0.99	C15—H15	0.95
C2—C2^i	1.522 (3)	C16—H16	0.95
C2—H2A	0.99	C17—H17	0.95
C2—H2B	0.99	C18—H18A	0.98
C11—C16	1.391 (2)	C18—H18B	0.98
C11—C12	1.402 (2)	C18—H18C	0.98
C11—C17	1.4719 (18)
C17—N1—C1	115.73 (12)	C14—C13—H13	120.3
C12—O1—C18	118.18 (11)	C12—C13—H13	120.3
N1—C1—C2	109.90 (11)	C15—C14—C13	121.10 (14)
N1—C1—H1A	109.7	C15—C14—H14	119.4
C2—C1—H1A	109.7	C13—C14—H14	119.4
N1—C1—H1B	109.7	C14—C15—C16	119.51 (14)
C2—C1—H1B	109.7	C14—C15—H15	120.2
H1A—C1—H1B	108.2	C16—C15—H15	120.2
C1—C2—C2^i	112.93 (14)	C15—C16—C11	121.00 (15)
C1—C2—H2A	109.0	C15—C16—H16	119.5
C2^i—C2—H2A	109.0	C11—C16—H16	119.5
C1—C2—H2B	109.0	N1—C17—C11	123.01 (13)
C2^i—C2—H2B	109.0	N1—C17—H17	118.5
H2A—C2—H2B	107.8	C11—C17—H17	118.5
C16—C11—C12	118.74 (13)	O1—C18—H18A	109.5
C16—C11—C17	121.19 (13)	O1—C18—H18B	109.5
C12—C11—C17	120.07 (13)	H18A—C18—H18B	109.5
O1—C12—C13	124.01 (13)	O1—C18—H18C	109.5
O1—C12—C11	115.75 (12)	H18A—C18—H18C	109.5
C13—C12—C11	120.22 (13)	H18B—C18—H18C	109.5
C14—C13—C12	119.43 (15)
C17—N1—C1—C2	113.14 (13)	C11—C12—C13—C14	1.1 (2)
N1—C1—C2—C2^i	−177.94 (14)	C12—C13—C14—C15	−0.6 (2)
C18—O1—C12—C13	−3.8 (2)	C13—C14—C15—C16	−0.2 (2)
C18—O1—C12—C11	177.69 (14)	C14—C15—C16—C11	0.5 (2)
C16—C11—C12—O1	177.84 (12)	C12—C11—C16—C15	0.0 (2)
C17—C11—C12—O1	−2.81 (19)	C17—C11—C16—C15	−179.39 (12)
C16—C11—C12—C13	−0.7 (2)	C1—N1—C17—C11	−178.18 (12)
C17—C11—C12—C13	178.61 (12)	C16—C11—C17—N1	−15.5 (2)
O1—C12—C13—C14	−177.41 (13)	C12—C11—C17—N1	165.12 (13)

Symmetry code: (i) −x+1, −y+1, −z+1.