Bis[4-(3-pyridylmethyl­eneamino)­phenyl]methane

In the title Schiff base compound, C₂₅H₂₀N₄, the two rigid parts adopt an angular conformation, thus making the compound a potential non-linear ditopic ligand for the construction of interesting coordination polymers.

S1. Comment

Rigid bipyridyl-type bidentate Schiff base ligands have been intensively utilized in order to assemble various coordination polymers with intriguing topology (Barnett & Champness, 2003; Su et al., 2004), while angular chelating bipyridyl Schiff base ligands are known to form helical complexes (Guo et al., 2002). However, angular ditopic Schiff base ligands containing non-chelating dipyridyl groups have rarely been used to construct coordination assemblies. As a continuation of our study of the coordination chemistry of semi-rigid ligands (Su et al., 2003; Chen et al., 2002), we have synthesized the title compound, (I), and report its single-crystal structure.

Compound (I) crystallizes in the non-centrosymmetric space group Pc, which was confirmed by the routine PLUTON ADDSYM check (Spek, 1990, 2003). As expected, the two rigid parts incorporating the 3-pyridyl groups adopt an angular arrangement (Fig. 1). The dihedral angle between the two phenyl rings linked by the methylene is 77.95 (16)°, which determines the specific orientation of the pyridyl groups. However, the pyridyl rings are not exactly coplanar with the phenyl rings, although the coplanar conformation is energetically preferred (Su et al., 2000). On one side of the methylene group, the pyridyl (C21–C25/N4) and phenyl (C14–C19) rings are nearly coplanar, with a dihedral angle of 9.95 (17)°, but on the other side, these two rings (C7–C12 for the phenyl ring and C1–C5/N1 for the pyridyl ring) adopt a dihedral angle of 53.86 (18)°, significantly deviating from the mean plane. Such asymmetric disposition of the two rigid branches may account for the absence of centrosymmetry in the crystal.

Analysis of the crystal-packing mode reveals that the ligands stack up in the crystal lattice with each six-membered ring (both phenyl and pyridyl) parallel to its counterpart in adjacent ligands, giving a centroid-to-centroid distance of ca 4.64 Å. As shown in Fig. 2, the overlapping arrangement of the ligands results in a one-dimensional array along the b axis, which is sustained by forming π–π intermolecular interactions. Such arrays are aligned parallel to each other, to form two-dimensional layers along the c axis. When viewed along the c axis (Fig. 3), it is clear that the one-dimensional parallel arrays run in opposite directions. That is, the arrowheaded methylene groups point in the same direction in one array but in the opposite direction in adjacent arrays. The whole crystal is stacked up into two-dimensional layers of ca 19 Å width, which are composed of the alternately opposite-running one-dimensional arrays.

S2. Experimental

The title compound was prepared from 4,4'-methylenedianiline and 3-pyridinecarboxaldehyde. Single crystals of (I) suitable for X-ray analysis were obtained by slow evaporation from an ethanol solution at room temperature.

S3. Refinement

All H atoms were initially located in a difference Fourier map and were refined freely along with an isotropic displacement parameter.

Computing details

Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXL97; software used to prepare material for publication: Please provide missing information.

Figures

	Fig. 1. A view of the molecule of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are represented by circles of arbitrary size.
	Fig. 2. The molecular packing viewed along the b axis. H atoms have been omitted for clarity.
	Fig. 3. The molecular packing viewed along the c axis. H atoms have been omitted for clarity.

Bis[4-(3-pyridylmethyleneamino)phenyl]methane

Crystal data

C25H20N4	F(000) = 396
Mr = 376.45	Dx = 1.275 Mg m^−3
Monoclinic, Pc	Mo Kα radiation, λ = 0.71073 Å
a = 18.7505 (10) Å	Cell parameters from 25 reflections
b = 4.6414 (10) Å	θ = 8–17.6°
c = 11.3866 (10) Å	µ = 0.08 mm^−1
β = 98.394 (10)°	T = 293 K
V = 980.3 (2) Å^3	Block, yellow
Z = 2	0.4 × 0.35 × 0.26 mm

Data collection

Enraf Nonius CAD-4 diffractometer	Rint = 0.035
ω scans	θmax = 26°, θmin = 2.2°
Absorption correction: ψ scan (North et al., 1968)	h = −23→22
Tmin = 0.956, Tmax = 0.980	k = −5→5
3793 measured reflections	l = 0→14
1920 independent reflections	2 standard reflections every 3600 reflections
1287 reflections with I > 2σ(I)	intensity decay: <97

Refinement

Refinement on F^2	All H-atom parameters refined
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.031P)^2] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.035	(Δ/σ)max = 0.001
wR(F^2) = 0.071	Δρmax = 0.11 e Å^−3
S = 1.02	Δρmin = −0.10 e Å^−3
1920 reflections	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
343 parameters	Extinction coefficient: 0.028 (4)
2 restraints

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
N1	1.38687 (18)	0.3314 (9)	1.4166 (3)	0.0875 (12)
N2	1.21014 (14)	−0.0157 (6)	1.1031 (2)	0.0585 (8)
N3	0.74195 (14)	0.1956 (5)	0.6940 (2)	0.0434 (7)
N4	0.60546 (19)	0.7947 (7)	0.4941 (3)	0.0774 (10)
C1	1.3264 (2)	0.1870 (10)	1.3719 (3)	0.0736 (12)
C2	1.4176 (2)	0.4898 (11)	1.3394 (5)	0.0833 (13)
C3	1.3924 (2)	0.5013 (10)	1.2211 (4)	0.0753 (12)
C4	1.3322 (2)	0.3496 (9)	1.1778 (4)	0.0656 (10)
C5	1.29817 (17)	0.1853 (8)	1.2537 (3)	0.0558 (9)
C6	1.23284 (18)	0.0183 (8)	1.2119 (3)	0.0589 (9)
C7	1.14446 (17)	−0.1646 (7)	1.0697 (3)	0.0515 (9)
C8	1.1390 (2)	−0.3547 (9)	0.9741 (3)	0.0620 (10)
C9	1.07583 (19)	−0.4965 (9)	0.9364 (3)	0.0590 (9)
C10	1.01474 (16)	−0.4492 (6)	0.9883 (3)	0.0449 (8)
C11	1.01964 (19)	−0.2567 (7)	1.0809 (3)	0.0493 (8)
C12	1.08326 (19)	−0.1167 (8)	1.1219 (3)	0.0506 (8)
C13	0.94456 (19)	−0.5996 (8)	0.9437 (3)	0.0502 (9)
C14	0.88863 (15)	−0.3967 (6)	0.8794 (3)	0.0409 (8)
C15	0.89570 (18)	−0.2901 (7)	0.7680 (3)	0.0473 (8)
C16	0.84642 (17)	−0.1021 (7)	0.7103 (3)	0.0448 (8)
C17	0.78862 (16)	−0.0037 (6)	0.7618 (3)	0.0383 (7)
C18	0.78076 (18)	−0.1103 (7)	0.8731 (3)	0.0445 (8)
C19	0.82977 (16)	−0.3062 (7)	0.9295 (3)	0.0417 (8)
C20	0.69408 (18)	0.3254 (7)	0.7398 (3)	0.0459 (8)
C21	0.64497 (16)	0.5350 (7)	0.6741 (3)	0.0440 (8)
C22	0.59340 (19)	0.6733 (8)	0.7285 (4)	0.0635 (10)
C23	0.5481 (2)	0.8671 (9)	0.6633 (4)	0.0695 (12)
C24	0.5556 (2)	0.9178 (9)	0.5486 (4)	0.0665 (12)
C25	0.6488 (2)	0.6058 (8)	0.5587 (3)	0.0608 (10)
H16	0.8509 (15)	−0.025 (7)	0.634 (3)	0.046 (8)*
H15	0.9368 (17)	−0.346 (7)	0.738 (3)	0.054 (9)*
H18	0.7402 (13)	−0.058 (6)	0.910 (2)	0.030 (7)*
H24	0.5257 (15)	1.058 (7)	0.507 (3)	0.046 (9)*
H13B	0.9250 (16)	−0.695 (7)	1.012 (3)	0.059 (9)*
H25	0.686 (2)	0.504 (8)	0.509 (3)	0.089 (12)*
H13A	0.9534 (15)	−0.754 (7)	0.891 (3)	0.047 (9)*
H11	0.9790 (15)	−0.233 (6)	1.116 (2)	0.033 (8)*
H9	1.0757 (19)	−0.618 (8)	0.872 (3)	0.079 (12)*
H2	1.464 (2)	0.605 (10)	1.368 (4)	0.109 (15)*
H8	1.182 (2)	−0.369 (8)	0.939 (3)	0.079 (12)*
H23	0.514 (2)	0.973 (9)	0.703 (4)	0.091 (13)*
H20	0.6855 (19)	0.281 (8)	0.825 (4)	0.083 (11)*
H1	1.3054 (18)	0.053 (8)	1.429 (3)	0.070 (11)*
H4	1.314 (2)	0.339 (8)	1.102 (3)	0.079 (13)*
H12	1.0836 (15)	0.016 (6)	1.184 (3)	0.042 (8)*
H19	0.8250 (16)	−0.393 (6)	1.007 (3)	0.059 (9)*
H6	1.207 (2)	−0.095 (8)	1.273 (3)	0.085 (12)*
H22	0.5898 (18)	0.630 (7)	0.813 (3)	0.074 (11)*
H3	1.414 (2)	0.625 (8)	1.174 (4)	0.082 (14)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.065 (2)	0.123 (3)	0.070 (2)	−0.004 (2)	−0.0091 (19)	−0.024 (2)
N2	0.0473 (16)	0.0663 (18)	0.0593 (19)	−0.0064 (15)	−0.0009 (14)	−0.0007 (15)
N3	0.0451 (15)	0.0446 (16)	0.0409 (15)	0.0044 (13)	0.0073 (13)	0.0003 (13)
N4	0.091 (3)	0.085 (2)	0.053 (2)	0.035 (2)	−0.0018 (19)	0.0046 (18)
C1	0.061 (3)	0.100 (3)	0.060 (2)	0.005 (2)	0.007 (2)	−0.004 (2)
C2	0.056 (2)	0.092 (3)	0.099 (4)	−0.012 (3)	0.001 (3)	−0.026 (3)
C3	0.057 (2)	0.081 (3)	0.087 (3)	−0.009 (2)	0.008 (2)	−0.007 (3)
C4	0.057 (2)	0.077 (3)	0.059 (2)	−0.005 (2)	−0.0021 (19)	−0.006 (2)
C5	0.044 (2)	0.067 (2)	0.055 (2)	0.0040 (17)	0.0014 (16)	−0.0020 (19)
C6	0.054 (2)	0.060 (2)	0.060 (3)	−0.0026 (19)	0.0038 (19)	0.0053 (19)
C7	0.0447 (19)	0.055 (2)	0.052 (2)	0.0002 (18)	−0.0016 (16)	0.0051 (18)
C8	0.048 (2)	0.080 (3)	0.058 (2)	−0.003 (2)	0.0109 (18)	−0.007 (2)
C9	0.060 (2)	0.067 (2)	0.049 (2)	0.002 (2)	0.0032 (18)	−0.0112 (19)
C10	0.053 (2)	0.0359 (17)	0.0440 (17)	0.0036 (15)	−0.0003 (15)	0.0070 (15)
C11	0.048 (2)	0.049 (2)	0.052 (2)	0.0024 (16)	0.0088 (16)	0.0018 (17)
C12	0.054 (2)	0.048 (2)	0.048 (2)	−0.0002 (17)	0.0000 (17)	−0.0053 (17)
C13	0.058 (2)	0.0415 (19)	0.048 (2)	−0.0005 (17)	−0.0035 (17)	0.0029 (17)
C14	0.0438 (18)	0.0362 (17)	0.0404 (17)	−0.0084 (15)	−0.0016 (14)	0.0019 (15)
C15	0.047 (2)	0.048 (2)	0.048 (2)	0.0042 (16)	0.0116 (16)	0.0014 (16)
C16	0.055 (2)	0.0472 (19)	0.0329 (17)	0.0066 (16)	0.0084 (15)	0.0035 (15)
C17	0.0441 (17)	0.0348 (15)	0.0353 (16)	−0.0039 (14)	0.0033 (14)	−0.0006 (14)
C18	0.0471 (19)	0.0464 (19)	0.0415 (19)	−0.0003 (16)	0.0112 (16)	0.0003 (16)
C19	0.050 (2)	0.0416 (18)	0.0322 (17)	−0.0057 (15)	0.0026 (14)	0.0033 (15)
C20	0.054 (2)	0.0423 (18)	0.0417 (19)	0.0000 (17)	0.0075 (17)	0.0003 (16)
C21	0.0411 (17)	0.0433 (18)	0.047 (2)	0.0014 (15)	0.0046 (15)	−0.0039 (16)
C22	0.062 (2)	0.066 (2)	0.066 (3)	0.011 (2)	0.021 (2)	0.010 (2)
C23	0.054 (2)	0.062 (2)	0.094 (3)	0.017 (2)	0.019 (2)	0.009 (2)
C24	0.064 (3)	0.055 (2)	0.072 (3)	0.009 (2)	−0.018 (2)	0.002 (2)
C25	0.076 (3)	0.062 (2)	0.043 (2)	0.018 (2)	0.0051 (19)	−0.0015 (19)

Geometric parameters (Å, º)

N1—C2	1.339 (6)	C11—C12	1.379 (5)
N1—C1	1.351 (5)	C11—H11	0.92 (3)
N2—C6	1.259 (4)	C12—H12	0.93 (3)
N2—C7	1.415 (4)	C13—C14	1.516 (4)
N3—C20	1.256 (3)	C13—H13B	1.01 (4)
N3—C17	1.421 (4)	C13—H13A	0.97 (3)
N4—C24	1.325 (5)	C14—C19	1.380 (4)
N4—C25	1.340 (5)	C14—C15	1.386 (4)
C1—C5	1.373 (5)	C15—C16	1.367 (5)
C1—H1	1.02 (4)	C15—H15	0.93 (3)
C2—C3	1.362 (6)	C16—C17	1.383 (4)
C2—H2	1.03 (5)	C16—H16	0.96 (3)
C3—C4	1.361 (5)	C17—C18	1.388 (4)
C3—H3	0.92 (4)	C18—C19	1.382 (4)
C4—C5	1.377 (5)	C18—H18	0.95 (3)
C4—H4	0.88 (4)	C19—H19	0.98 (3)
C5—C6	1.469 (4)	C20—C21	1.467 (4)
C6—H6	1.05 (4)	C20—H20	1.03 (4)
C7—C12	1.385 (5)	C21—C25	1.367 (5)
C7—C8	1.393 (5)	C21—C22	1.381 (5)
C8—C9	1.369 (5)	C22—C23	1.377 (5)
C8—H8	0.96 (4)	C22—H22	1.00 (4)
C9—C10	1.381 (4)	C23—C24	1.355 (6)
C9—H9	0.93 (4)	C23—H23	0.98 (4)
C10—C11	1.375 (5)	C24—H24	0.94 (3)
C10—C13	1.511 (5)	C25—H25	1.07 (4)
C2—N1—C1	116.2 (4)	C10—C13—H13B	109.7 (18)
C6—N2—C7	118.8 (3)	C14—C13—H13B	109.9 (18)
C20—N3—C17	120.5 (2)	C10—C13—H13A	109.4 (17)
C24—N4—C25	116.0 (4)	C14—C13—H13A	109.1 (18)
N1—C1—C5	123.7 (4)	H13B—C13—H13A	106 (3)
N1—C1—H1	116.5 (19)	C19—C14—C15	117.3 (3)
C5—C1—H1	119 (2)	C19—C14—C13	121.9 (3)
N1—C2—C3	123.4 (4)	C15—C14—C13	120.8 (3)
N1—C2—H2	120 (2)	C16—C15—C14	121.3 (3)
C3—C2—H2	117 (3)	C16—C15—H15	122.6 (19)
C4—C3—C2	119.2 (5)	C14—C15—H15	116.0 (19)
C4—C3—H3	121 (3)	C15—C16—C17	121.6 (3)
C2—C3—H3	119 (3)	C15—C16—H16	122.2 (18)
C3—C4—C5	119.7 (4)	C17—C16—H16	116.1 (18)
C3—C4—H4	125 (3)	C16—C17—C18	117.6 (3)
C5—C4—H4	116 (3)	C16—C17—N3	116.3 (3)
C1—C5—C4	117.7 (4)	C18—C17—N3	126.1 (3)
C1—C5—C6	120.3 (4)	C19—C18—C17	120.5 (3)
C4—C5—C6	122.0 (3)	C19—C18—H18	118.6 (16)
N2—C6—C5	122.1 (3)	C17—C18—H18	120.8 (16)
N2—C6—H6	118 (2)	C14—C19—C18	121.7 (3)
C5—C6—H6	120 (2)	C14—C19—H19	115.3 (18)
C12—C7—C8	117.8 (3)	C18—C19—H19	123.0 (18)
C12—C7—N2	123.3 (3)	N3—C20—C21	122.7 (3)
C8—C7—N2	118.8 (3)	N3—C20—H20	121 (2)
C9—C8—C7	120.8 (4)	C21—C20—H20	116 (2)
C9—C8—H8	126 (2)	C25—C21—C22	117.3 (3)
C7—C8—H8	113 (2)	C25—C21—C20	122.2 (3)
C8—C9—C10	121.5 (4)	C22—C21—C20	120.5 (3)
C8—C9—H9	116 (2)	C23—C22—C21	118.6 (4)
C10—C9—H9	122 (2)	C23—C22—H22	122 (2)
C11—C10—C9	117.7 (3)	C21—C22—H22	119 (2)
C11—C10—C13	121.0 (3)	C24—C23—C22	119.3 (4)
C9—C10—C13	121.2 (3)	C24—C23—H23	122 (2)
C10—C11—C12	121.6 (3)	C22—C23—H23	118 (2)
C10—C11—H11	116.5 (17)	N4—C24—C23	123.8 (4)
C12—C11—H11	121.9 (17)	N4—C24—H24	118.1 (19)
C11—C12—C7	120.6 (3)	C23—C24—H24	118.0 (18)
C11—C12—H12	118.4 (18)	N4—C25—C21	124.9 (4)
C7—C12—H12	121.0 (18)	N4—C25—H25	113 (2)
C10—C13—C14	112.5 (3)	C21—C25—H25	122 (2)
C2—N1—C1—C5	3.1 (6)	C10—C13—C14—C19	−106.9 (3)
C1—N1—C2—C3	−2.4 (7)	C10—C13—C14—C15	71.8 (4)
N1—C2—C3—C4	1.3 (7)	C19—C14—C15—C16	0.2 (4)
C2—C3—C4—C5	−0.6 (6)	C13—C14—C15—C16	−178.5 (3)
N1—C1—C5—C4	−2.6 (6)	C14—C15—C16—C17	1.9 (5)
N1—C1—C5—C6	178.9 (3)	C15—C16—C17—C18	−2.2 (5)
C3—C4—C5—C1	1.2 (6)	C15—C16—C17—N3	178.8 (3)
C3—C4—C5—C6	179.7 (4)	C20—N3—C17—C16	−170.3 (3)
C7—N2—C6—C5	−176.2 (3)	C20—N3—C17—C18	10.7 (4)
C1—C5—C6—N2	−171.6 (4)	C16—C17—C18—C19	0.5 (4)
C4—C5—C6—N2	10.0 (5)	N3—C17—C18—C19	179.4 (3)
C6—N2—C7—C12	44.3 (5)	C15—C14—C19—C18	−1.9 (4)
C6—N2—C7—C8	−140.4 (3)	C13—C14—C19—C18	176.8 (3)
C12—C7—C8—C9	−2.3 (5)	C17—C18—C19—C14	1.6 (5)
N2—C7—C8—C9	−178.0 (4)	C17—N3—C20—C21	179.4 (3)
C7—C8—C9—C10	2.4 (6)	N3—C20—C21—C25	−0.9 (5)
C8—C9—C10—C11	−0.9 (5)	N3—C20—C21—C22	−179.7 (3)
C8—C9—C10—C13	178.1 (3)	C25—C21—C22—C23	1.6 (5)
C9—C10—C11—C12	−0.6 (5)	C20—C21—C22—C23	−179.6 (3)
C13—C10—C11—C12	−179.6 (3)	C21—C22—C23—C24	−0.4 (6)
C10—C11—C12—C7	0.6 (5)	C25—N4—C24—C23	1.5 (6)
C8—C7—C12—C11	0.8 (5)	C22—C23—C24—N4	−1.2 (6)
N2—C7—C12—C11	176.3 (3)	C24—N4—C25—C21	−0.2 (6)
C11—C10—C13—C14	70.4 (4)	C22—C21—C25—N4	−1.3 (6)
C9—C10—C13—C14	−108.6 (4)	C20—C21—C25—N4	179.9 (4)