One-dimensional C—H...N hydrogen-bonded polymers in flexible tetra­pyridyl systems

In N,N,N′,N′-tetra­kis(2-pyridyl­methyl)­propane-1,3-diamine, C₂₇H₃₀N₆, (I), and N,N,N′,N′-tetra­kis(2-pyridyl­methyl)­butane-1,4-diamine, C₂₈H₃₂N₆, (II), the twofold rotational symmetry of (I) favours the formation of a one-dimensional hydrogen-bonded polymer with two columns of C—H...N hydrogen bonds, while the inversion symmetry of (II) allows the formation of a one-dimensional hydrogen-bonded polymer stabilized by four columns of C—H...N hydrogen bonds. The possible role played by the chain length of the linking alkanediamine in determining the type of supra­molecular architecture in this series of compounds is discussed.

S1. Comment

The tetra(pyridyl) compounds formed by the reaction of four molar equivalents of 2-picolylchloride with an α,ω-alkyldiamine are versatile bis(tridentate) ligands for the synthesis of binuclear transition metal complexes. Coordination compounds based on this ligand system were first reported by Anderegg & Wenk (1967) and later by Toftlund & Yde-Andersen (1981). More recently, the p-phenylenediamine derivative was used to synthesize various copper complexes (Buchen et al., 1997), while the m-phenylenediamine derivatives have been used to synthesize a range of copper(II), iron(II) and nickel(II) complexes (Schindler et al., 1992; Foxon et al., 2007).

Following the improved synthesis of N,N,N',N'-tetrakis(2-pyridylmethyl)-α,ω-alkyldiamines described by Sato et al. (1992), various binuclear metal complexes have been prepared. Thus, platinum(II) complexes of these ligands with varied bridging alkyl chain lengths have been used in mechanistic studies (Hoffmann & van Eldik, 2003). We have used several of these ligands for the coordination of platinum group metals in our laboratory and have obtained crystals suitable for X-ray diffraction analysis of two new metal-free derivatives, namely N,N,N',N'-tetrakis(2-pyridylmethyl)-1,3-propanediamine, (I), and N,N,N',N'-tetrakis(2-pyridylmethyl)-1,4-butanediamine, (II). The crystal structure of the 1,2-ethanediamine analogue (n = 0) was reported only quite recently by Fujihara et al. (2004).

The structure of (I) has C₂ molecular point group symmetry by virtue of the location of the central C atom of the propyl chain (C1) on a twofold rotation axis (Fig. 1). The methylene groups of the structure all adopt the expected staggered (lowest energy) conformation (Munro & Camp, 2003). The C—Nsp² and C—Nsp³ bonds in the structure (Table 1) compare favourably with those reported for the related C₂ symmetry 1,2-ethanediamine analogue of (I) (Fujihara et al., 2004), but have been determined to a higher precision in the present structure. The pyridyl ring containing atom N2 is oriented at 14 (1)° relative to the mean plane of the bridging propyl group, while that containing atom N3 is in a near-orthogonal orientation [81 (1)°].

The underlying reason for the different relative orientations of the pyridyl rings is not immediately apparent from the crystal packing (Fig. 2), which reflects a rather loose interlocked arrangement of layers of (I) in which the propyl chains are all oriented in approximately the same direction as the diagonal plane perpendicular to the (101) direction. A plot of the unit-cell contents using the van der Waals radii of the atoms (not shown) clearly reflects the loose packing in this system [there are no short van der Waals contacts < Σ(van der Waals radii)]. Weak (possibly stabilizing) π–π intermolecular interactions do, however, occur in (I). Specifically, if Cg1 defines the centre of gravity of the pyridyl ring containing atom N2, then the closest symmetry-related neighbouring ring centroid is located < 6 Å away [Cg1···Cg1ⁱ = 5.057 (2) Å; symmetry code: (i) −x, 1 − y, −z]. The interplanar separation is 3.395 (2) Å with a lateral offset (or slippage) of 3.747 (2) Å. The metrics of this interaction reflect weak edge-to-edge π–π overlap (at best) for the C4—C5 π bonds in the inversion pair.

The rather intriguing relative orientations of the pyridyl rings in (I), particularly the fact that the ring containing atom N2 points in the same direction as the b axis of the unit cell, reflect the formation of pairs of C—H···N hydrogen bonds [H···N = 2.56 (2) Å and C—H···N = 145 (1)°] that run collinear with the b axis (Table 2). These unconventional hydrogen bonds lead to the formation of one-dimensional hydrogen-bonded molecular stacks in the crystal structure (Fig. 3). Similar C—H···N hydrogen bonds are observed in the 1,2-ethanediamine analogue of (I) (Fujihara et al., 2004), for which n = 0 in the scheme [mean H···N distance = 2.63 (5) Å and mean C—H···N angle = 163 (7)°]. However, as discussed below, the number of linker CH₂ groups that make up the diamine core of the molecule appears to dictate rather precisely the number of hydrogen-bonded columns (i.e. the supramolecular architecture) formed in this type of system. An additional noteworthy comment for (I) is that some stabilization of the interlocked packing evident in Fig. 2, due to the formation of weak C—H···π bonds [averaging 2.91 (4) Å; Table 2] roughly orthogonal to the stacking axis of each C—H···N hydrogen-bonded column, is likely. In effect, the hydrogen-bonded columns of (I) are tethered laterally by these significant, though often overlooked, interactions (Nishio, 2004).

Compound (II) has crystallographically required inversion symmetry, with the centroid of the central CH₂—CH₂ bond located on the inversion centre (Fig. 4). As a result, the symmetry-unique pyridyl rings are oriented such that the pyridyl N atoms point in the same general direction (two up, two down), in marked contrast to the C₂ symmetry structure of (I). The pyridyl ring containing atom N2 is oriented at 53 (1)° relative to the mean plane of the bridging butyl group, and that containing atom N3 is similarly oriented [55 (1)°]. The congruent pyridyl ring orientations for (II) directly reflect the supramolecular architecture within the system (see below), which differs significantly from that of (I). The C—N distances listed in Table 3 are, as expected, in agreement with those of the propyl-bridged analogue, (I), and the ethyl-bridged analogue reported by Fujihara et al. (2004). Interestingly, the latter structure also crystallizes in the space group P1 on a special position (C_i point group symmetry). As discussed below, the significance of the molecular symmetry is that it most likely determines the type of supramolecular structure formed in this class of compounds.

The crystal packing of the unit-cell contents for (II) is similar in principle to that observed for (I). Specifically, the molecules interlock neatly within the (011) plane and are stacked in columns perpendicular to this plane, i.e. along the a axis (Fig. 5). The crystal packing is somewhat looser for (II), however, and two inversion-related voids at general positions measuring 5.7 ų (probe radius = 1.0 Å) are located in the unit cell and are surrounded by pyridyl groups. (These voids are too small to accomodate a solvent but do illustrate the low-density crystal packing in this system.) A possible reason for the low-density packing within the (011) layers is the formation of hydrogen-bonded stacks along the a-axis direction (Fig. 6). It is quite probable that optimization of hydrogen bonding in the crystal structure is energetically favoured over optimization of weaker van der Waals interactions. In the case of (II), the inversion symmetry clearly facilitates the formation of one-dimensional hydrogen-bonded polymers through two pairs of inversion-related C—H···N hydrogen bonds (Table 4). The hydrogen-bonded molecular stacks are thus held together by four columns of C—H···N hydrogen bonds with interaction vectors approximately along the a-axis direction. As noted above, the C—H···N hydrogen bonds in the 1,2-diaminoethane analogue of (II) have a mean H···N distance of 2.63 (5) Å and mean C—H···N angle of 163 (7)° (Fujihara et al., 2004). The hydrogen bonding in (II) [mean H···N distance of 2.5 (1) Å and mean C—H···N angle of 166 (15)°] is therefore slightly tighter than in the 1,2-diaminoethane derivative, despite very similar angular interactions between the pyridyl rings within the hydrogen-bonded stacks. Interestingly, the C—H···N angle for (I) of 145 (1)° is significantly more acute than that for (II) and reflects a somewhat less ideal hydrogen-bonding interaction.

As with (I), there are several C—H···π intermolecular interactions in (II) which are formed between molecules within adjacent hydrogen-bonded columns (Table 4) and which average 2.79 (7) Å. These slightly weaker interactions roughly perpendicular to the direction of the C—H···N hydrogen bonds evidently further stabilize the interlocked supramolecular stacks. A significant additional packing stabilization, namely π–π interactions between the pyridyl ring containing atom N2 and the inversion-related pyridine ring of the closest neighbour, is also evident in this system. Specifically, if Cg1 defines the centre of gravity of this pyridyl ring in the asymmetric unit, then the Cg1···Cg1ⁱ interaction is 3.848 (2) Å [symmetry code: (i) −x, 2 − y, 1 − z]. The mean plane separation of the coplanar rings is 3.336 (2) Å (i.e. very similar to the graphite layer separation; Bacon, 1951) and the lateral shift or slippage is 1.917 (2) Å. In effect, two pyridyl rings overlap by exact superposition of the C5—C6 bond of one molecule with the C6—C5 bond of the second through a centre of inversion mid-way between the planes passing through each bond.

Finally, it is intriguing to note that exactly the same supramolecular architecture observed for (II) (i.e. four C—H···N hydrogen-bonded columns) occurs in the C_i symmetry 1,2-ethanediamine analogue (Fujihara et al., 2004), while the C₂ symmetry propyl-bridged derivative, (I), exhibits one-dimensional stacks based on only two columns of hydrogen bonds. Clearly, the number of methylene groups of the linking diamine core in these compounds affects the type of hydrogen-bonded stack that may be formed. Although based on relatively few data at present, a possible trend is that an even number of linking CH₂ groups favours hydrogen-bonded stacks with four columns of hydrogen bonds due to the C_i symmetry of the constituent monomers.

S2. Experimental

Compounds (I) and (II) were synthesized following the literature method of Sato et al. (1992). Colourless crystals (X-ray quality) were obtained from solutions in ethanol by slow evaporation of the solvent over several days.

Spectroscopic data for (I): ¹H NMR (500 MHz, D₂O spiked with DCl, δ, p.p.m.): 8.60 (d, 4H), 8.38 (t, 4H), 7.94 (d, 4H), 7.82 (t, 4H), 4.20 (s, 8H), 2.50 (t, 4H), 1.71 (m, 2H); ¹³C NMR (125 MHz, D₂O spiked with DCl, δ, p.p.m.): 23.0, 52.5, 55.0, 127.1, 128.0, 128.0, 145.0, 148.0, 154.0; CHN analysis, calculated for C₂₇H₃₀N₆: C 73.94, H 6.89, N 19.17%; found: C 74.08, H 6.96, N 19.17%; MS–ES⁺ m/e: 439.2453 (M + 1)⁺, 461.2428 (M + Na)⁺.

Spectroscopic data for (II): ¹H NMR (500 MHz, CD₃OD, δ, p.p.m.): 8.41 (d, 4H), 7.77 (td, 4H), 7.58 (d, 4H), 7.26 (tt, 4H), 3.31 (m, 8H), 2.45 (s, br, 4H), 1.49 (m, 4H); CHN analysis, calculated for C₂₈H₃₂N₆: C 74.30, H 7.13, N 18.57%; found: C 74.30, H 7.13, N 18.53%; MS–ES⁺ m/e: 453.2199 (M + 1)⁺, 475.2120 (M + Na)⁺.

S3. Refinement

All H atoms were located in a final difference Fourier map and refined isotropically without restraints.

Computing details

For both compounds, data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: WinGX (Farrugia, 1999); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. A plot of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 60% probability level. H atoms are shown only as the intersections and endpoints of bonds represented as cylinders. Unlabelled atoms are related to labelled atoms by the symmetry operator (−x, y, −z + 1/2). [Please check added text]
	Fig. 2. The unit-cell contents for (I), viewed approximately down the b axis. H atoms have been omitted for clarity; all other atoms are shown only as the intersections and endpoints of bonds represented as cylinders.
	Fig. 3. A view of (I), illustrating a single one-dimensional hydrogen-bonded stack of molecules running collinear with the b axis of the unit cell. The symmetry-unique hydrogen-bond distance (in Å) is shown. [Symmetry code: (i) x, 1 + y, z.]
	Fig. 4. A plot of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 60% probability level. H atoms are shown only as the intersections and endpoints of bonds represented as cylinders. Unlabelled atoms are related to labelled atoms by the symmetry operator (2 − x, −y, −z). [Please check added text]
	Fig. 5. The unit-cell contents for (II), viewed approximately down the a axis. H atoms have been omitted for clarity; all other atoms are shown only as the intersections and endpoints of bonds represented as cylinders.
	Fig. 6. A view of (II), illustrating a single one-dimensional hydrogen-bonded stack of molecules running collinear with the a axis of the unit cell. The symmetry-unique hydrogen-bond distances (in Å) are shown. [Symmetry code: (i) −1 + x, y, z.]

(I) N,N,N',N'-tetrakis(2-pyridylmethyl)propane-1,3-diamine

Crystal data

C27H30N6	F(000) = 936
Mr = 438.57	Dx = 1.202 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 4212 reflections
a = 24.615 (3) Å	θ = 3.8–31.9°
b = 6.0114 (11) Å	µ = 0.07 mm^−1
c = 17.1066 (19) Å	T = 293 K
β = 106.702 (10)°	Rhomb, colourless
V = 2424.4 (6) Å^3	0.6 × 0.4 × 0.3 mm
Z = 4

Data collection

Oxford Diffraction Xcalibur2 CCD diffractometer	2270 reflections with I > 2σ(I)
ω/2θ' scans	Rint = 0.020
Absorption correction: multi-scan empirical (using intensity measurements) absorption correction using spherical harmonics (CrysAlis RED; Oxford Diffraction, 2006)	θmax = 31.8°, θmin = 3.8°
Tmin = 0.945, Tmax = 0.973	h = −36→34
11733 measured reflections	k = −8→7
3834 independent reflections	l = −24→24

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.041	w = 1/[σ^2(Fo^2) + (0.0612P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.111	(Δ/σ)max < 0.001
S = 0.99	Δρmax = 0.21 e Å^−3
3834 reflections	Δρmin = −0.17 e Å^−3
210 parameters

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
C1	0	0.1036 (3)	0.25	0.0551 (4)
C2	0.03464 (4)	−0.03968 (18)	0.20777 (6)	0.0390 (2)
C3	0.03637 (4)	0.22770 (19)	0.10117 (6)	0.0416 (2)
C4	0.06879 (4)	0.31329 (16)	0.04474 (5)	0.0356 (2)
C5	0.08145 (4)	0.53778 (18)	0.04144 (7)	0.0449 (3)
C6	0.11086 (5)	0.6086 (2)	−0.01185 (8)	0.0549 (3)
C7	0.12658 (5)	0.4560 (2)	−0.06086 (7)	0.0531 (3)
C8	0.11214 (5)	0.2371 (2)	−0.05432 (7)	0.0514 (3)
C9	0.11736 (4)	0.20198 (18)	0.22258 (6)	0.0386 (2)
C10	0.16314 (4)	0.05196 (16)	0.27434 (6)	0.0358 (2)
C11	0.17418 (4)	−0.15789 (18)	0.24891 (7)	0.0464 (3)
C12	0.21837 (5)	−0.2823 (2)	0.29844 (9)	0.0581 (3)
C13	0.25048 (5)	−0.1912 (2)	0.37108 (9)	0.0655 (4)
C14	0.23698 (5)	0.0180 (3)	0.39186 (8)	0.0661 (4)
N1	0.07053 (3)	0.08069 (13)	0.16600 (5)	0.0362 (2)
N2	0.08379 (4)	0.16204 (14)	−0.00322 (5)	0.0454 (2)
N3	0.19398 (4)	0.14097 (16)	0.34567 (5)	0.0510 (2)
H1A	0.0270 (6)	0.203 (3)	0.2936 (9)	0.094 (5)*
H2A	0.0600 (5)	−0.1444 (18)	0.2496 (7)	0.050 (3)*
H2B	0.0089 (5)	−0.1360 (18)	0.1658 (7)	0.045 (3)*
H3A	0.0032 (5)	0.1409 (18)	0.0691 (7)	0.051 (3)*
H3B	0.0214 (5)	0.3650 (18)	0.1256 (7)	0.052 (3)*
H5	0.0700 (5)	0.642 (2)	0.0763 (8)	0.058 (3)*
H6	0.1192 (6)	0.766 (3)	−0.0141 (8)	0.071 (4)*
H7	0.1467 (5)	0.498 (2)	−0.0980 (8)	0.068 (4)*
H8	0.1210 (5)	0.121 (2)	−0.0893 (8)	0.068 (4)*
H9A	0.1357 (4)	0.2966 (18)	0.1899 (7)	0.047 (3)*
H9B	0.1041 (4)	0.3047 (18)	0.2614 (7)	0.045 (3)*
H11	0.1508 (5)	−0.2103 (19)	0.1972 (8)	0.053 (3)*
H12	0.2244 (6)	−0.428 (2)	0.2791 (8)	0.075 (4)*
H13	0.2821 (6)	−0.274 (3)	0.4083 (9)	0.091 (5)*
H14	0.2595 (7)	0.089 (2)	0.4459 (10)	0.086 (4)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0604 (10)	0.0573 (10)	0.0631 (10)	0	0.0427 (9)	0
C2	0.0348 (5)	0.0474 (6)	0.0384 (5)	−0.0027 (4)	0.0162 (4)	−0.0009 (5)
C3	0.0329 (5)	0.0561 (6)	0.0367 (5)	0.0058 (5)	0.0116 (4)	0.0040 (5)
C4	0.0321 (5)	0.0414 (5)	0.0312 (4)	0.0043 (4)	0.0058 (3)	0.0004 (4)
C5	0.0456 (6)	0.0391 (6)	0.0478 (6)	0.0082 (4)	0.0098 (5)	−0.0014 (5)
C6	0.0523 (7)	0.0408 (6)	0.0680 (8)	0.0003 (5)	0.0115 (6)	0.0165 (6)
C7	0.0494 (6)	0.0649 (8)	0.0479 (6)	0.0017 (6)	0.0186 (5)	0.0175 (6)
C8	0.0613 (7)	0.0566 (7)	0.0433 (6)	0.0012 (5)	0.0260 (5)	−0.0033 (5)
C9	0.0341 (5)	0.0426 (5)	0.0386 (5)	−0.0001 (4)	0.0095 (4)	0.0003 (4)
C10	0.0285 (4)	0.0442 (5)	0.0367 (5)	−0.0023 (4)	0.0126 (4)	0.0014 (4)
C11	0.0362 (5)	0.0487 (6)	0.0541 (6)	−0.0013 (4)	0.0126 (5)	−0.0057 (5)
C12	0.0430 (6)	0.0484 (7)	0.0857 (9)	0.0067 (5)	0.0230 (6)	0.0056 (6)
C13	0.0436 (7)	0.0773 (9)	0.0694 (8)	0.0137 (6)	0.0062 (6)	0.0200 (7)
C14	0.0505 (7)	0.0891 (10)	0.0486 (7)	0.0087 (7)	−0.0017 (6)	−0.0009 (7)
N1	0.0285 (4)	0.0478 (5)	0.0333 (4)	−0.0002 (3)	0.0107 (3)	0.0024 (3)
N2	0.0553 (5)	0.0421 (5)	0.0440 (5)	−0.0038 (4)	0.0224 (4)	−0.0045 (4)
N3	0.0426 (5)	0.0639 (6)	0.0424 (5)	0.0042 (4)	0.0056 (4)	−0.0059 (4)

Geometric parameters (Å, º)

C1—C2^i	1.5314 (14)	C7—H7	0.945 (13)
C1—C2	1.5314 (14)	C8—N2	1.3436 (13)
C1—H1A	1.034 (15)	C8—H8	0.984 (14)
C2—N1	1.4757 (12)	C9—N1	1.4682 (12)
C2—H2A	1.020 (12)	C9—C10	1.5144 (13)
C2—H2B	0.995 (11)	C9—H9A	0.992 (11)
C3—N1	1.4772 (13)	C9—H9B	1.027 (11)
C3—C4	1.5086 (13)	C10—N3	1.3488 (13)
C3—H3A	0.992 (12)	C10—C11	1.3865 (15)
C3—H3B	1.039 (12)	C11—C12	1.3896 (16)
C4—N2	1.3455 (12)	C11—H11	0.959 (13)
C4—C5	1.3899 (15)	C12—C13	1.3801 (19)
C5—C6	1.3840 (16)	C12—H12	0.960 (14)
C5—H5	0.960 (13)	C13—C14	1.373 (2)
C6—C7	1.3718 (18)	C13—H13	0.986 (16)
C6—H6	0.972 (15)	C14—N3	1.3454 (15)
C7—C8	1.3756 (17)	C14—H14	1.025 (16)
C2^i—C1—C2	111.53 (14)	N2—C8—H8	113.9 (8)
C2^i—C1—H1A	108.3 (8)	C7—C8—H8	121.4 (8)
C2—C1—H1A	109.6 (8)	N1—C9—C10	113.64 (8)
N1—C2—C1	116.40 (10)	N1—C9—H9A	108.2 (6)
N1—C2—H2A	108.2 (6)	C10—C9—H9A	106.8 (6)
C1—C2—H2A	109.1 (6)	N1—C9—H9B	112.9 (6)
N1—C2—H2B	106.4 (6)	C10—C9—H9B	107.6 (6)
C1—C2—H2B	110.0 (6)	H9A—C9—H9B	107.5 (9)
H2A—C2—H2B	106.3 (9)	N3—C10—C11	122.32 (9)
N1—C3—C4	113.12 (7)	N3—C10—C9	115.06 (8)
N1—C3—H3A	107.5 (6)	C11—C10—C9	122.57 (9)
C4—C3—H3A	109.2 (7)	C10—C11—C12	119.22 (11)
N1—C3—H3B	111.4 (6)	C10—C11—H11	117.9 (7)
C4—C3—H3B	107.5 (6)	C12—C11—H11	122.9 (7)
H3A—C3—H3B	107.9 (9)	C13—C12—C11	118.72 (12)
N2—C4—C5	121.82 (9)	C13—C12—H12	124.4 (8)
N2—C4—C3	116.62 (9)	C11—C12—H12	116.8 (8)
C5—C4—C3	121.55 (9)	C14—C13—C12	118.56 (11)
C6—C5—C4	119.44 (10)	C14—C13—H13	119.9 (10)
C6—C5—H5	120.6 (7)	C12—C13—H13	121.6 (10)
C4—C5—H5	119.9 (7)	N3—C14—C13	124.00 (12)
C7—C6—C5	119.30 (11)	N3—C14—H14	115.5 (8)
C7—C6—H6	121.8 (8)	C13—C14—H14	120.5 (8)
C5—C6—H6	118.9 (8)	C9—N1—C2	112.96 (8)
C6—C7—C8	117.73 (11)	C9—N1—C3	111.56 (8)
C6—C7—H7	121.8 (8)	C2—N1—C3	111.47 (7)
C8—C7—H7	120.5 (8)	C8—N2—C4	117.03 (9)
N2—C8—C7	124.67 (11)	C14—N3—C10	117.17 (10)
C2^i—C1—C2—N1	−179.05 (10)	C12—C13—C14—N3	0.2 (2)
N1—C3—C4—N2	67.15 (11)	C10—C9—N1—C2	70.39 (10)
N1—C3—C4—C5	−114.10 (11)	C10—C9—N1—C3	−163.12 (8)
N2—C4—C5—C6	−0.74 (15)	C1—C2—N1—C9	66.74 (10)
C3—C4—C5—C6	−179.42 (9)	C1—C2—N1—C3	−59.81 (10)
C4—C5—C6—C7	0.48 (16)	C4—C3—N1—C9	65.75 (11)
C5—C6—C7—C8	−0.07 (17)	C4—C3—N1—C2	−166.94 (8)
C6—C7—C8—N2	−0.11 (18)	C7—C8—N2—C4	−0.12 (17)
N1—C9—C10—N3	−155.42 (8)	C5—C4—N2—C8	0.55 (14)
N1—C9—C10—C11	27.15 (13)	C3—C4—N2—C8	179.30 (9)
N3—C10—C11—C12	0.24 (16)	C13—C14—N3—C10	−0.86 (19)
C9—C10—C11—C12	177.48 (10)	C11—C10—N3—C14	0.64 (15)
C10—C11—C12—C13	−0.94 (17)	C9—C10—N3—C14	−176.79 (10)
C11—C12—C13—C14	0.74 (19)

Symmetry code: (i) −x, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···N2^ii	0.97 (2)	2.56 (2)	3.404 (2)	145 (1)
C8—H8···Cg2^iii	0.98 (1)	2.94 (1)	3.700 (2)	135 (1)
C12—H12···Cg2^iv	0.96 (1)	2.88 (1)	3.586 (2)	131 (1)

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

(II) N,N,N',N'-tetrakis(2-pyridylmethyl)butane-1,4-diamine

Crystal data

C28H32N6	Z = 1
Mr = 452.6	F(000) = 242
Triclinic, P1	Dx = 1.218 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.1942 (3) Å	Cell parameters from 6130 reflections
b = 9.2425 (3) Å	θ = 3.5–33.9°
c = 11.6798 (5) Å	µ = 0.07 mm^−1
α = 101.756 (3)°	T = 100 K
β = 96.953 (4)°	Thick plate, colourless
γ = 106.289 (4)°	0.5 × 0.4 × 0.2 mm
V = 616.96 (5) Å^3

Data collection

Oxford Diffraction Xcalibur2 CCD diffractometer	3241 reflections with I > 2σ(I)
ω/2θ scans	Rint = 0.020
Absorption correction: multi-scan empirical (using intensity measurements) absorption correction using spherical harmonics (CrysAlis RED; Oxford Diffraction, 2006)	θmax = 34.0°, θmin = 3.6°
Tmin = 0.945, Tmax = 0.983	h = −8→9
9960 measured reflections	k = −14→13
4227 independent reflections	l = −17→18

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	All H-atom parameters refined
R[F^2 > 2σ(F^2)] = 0.045	w = 1/[σ^2(Fo^2) + (0.1013P)^2] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.139	(Δ/σ)max < 0.001
S = 1.02	Δρmax = 0.51 e Å^−3
4227 reflections	Δρmin = −0.27 e Å^−3
218 parameters

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
C1	0.87861 (15)	−0.00048 (10)	0.00591 (8)	0.01689 (18)
C2	0.73069 (15)	−0.01230 (10)	−0.11180 (8)	0.01632 (17)
C3	0.70889 (15)	0.06927 (10)	−0.29429 (8)	0.01621 (17)
C4	0.77234 (14)	−0.05903 (10)	−0.37091 (7)	0.01496 (17)
C5	1.00079 (15)	−0.05395 (10)	−0.36452 (8)	0.01618 (17)
C6	1.05392 (16)	−0.16940 (11)	−0.44113 (8)	0.01828 (18)
C7	0.87743 (17)	−0.28621 (12)	−0.52090 (9)	0.0230 (2)
C8	0.65573 (18)	−0.28353 (13)	−0.52117 (10)	0.0278 (2)
C9	0.81079 (16)	0.26152 (10)	−0.10755 (8)	0.01667 (17)
C10	0.95777 (15)	0.39319 (9)	−0.14940 (7)	0.01498 (17)
C11	1.19356 (16)	0.42026 (11)	−0.13810 (8)	0.01878 (18)
C12	1.32435 (16)	0.54041 (11)	−0.17909 (8)	0.02066 (19)
C13	1.21481 (16)	0.63050 (10)	−0.23023 (8)	0.01931 (19)
C14	0.98061 (16)	0.59657 (10)	−0.23707 (8)	0.01879 (18)
N1	0.82702 (12)	0.11135 (8)	−0.17002 (6)	0.01422 (15)
N2	0.60084 (14)	−0.17227 (10)	−0.44725 (7)	0.02344 (19)
N3	0.85111 (13)	0.48060 (9)	−0.19789 (7)	0.01747 (17)
H1A	0.798 (2)	−0.0940 (15)	0.0365 (11)	0.024 (3)*
H1B	0.884 (2)	0.0915 (15)	0.0655 (11)	0.022 (3)*
H2A	0.7176 (19)	−0.1124 (13)	−0.1645 (10)	0.015 (3)*
H2B	0.570 (2)	−0.0168 (15)	−0.0987 (11)	0.024 (3)*
H3A	0.7539 (19)	0.1644 (14)	−0.3292 (10)	0.021 (3)*
H3B	0.535 (2)	0.0357 (14)	−0.3021 (11)	0.023 (3)*
H5	1.119 (2)	0.0295 (16)	−0.3118 (12)	0.028 (3)*
H6	1.214 (2)	−0.1659 (14)	−0.4404 (11)	0.022 (3)*
H7	0.906 (2)	−0.3698 (16)	−0.5767 (12)	0.029 (3)*
H8	0.526 (2)	−0.3655 (17)	−0.5761 (12)	0.031 (3)*
H9A	0.871 (2)	0.2793 (15)	−0.0191 (12)	0.024 (3)*
H9B	0.647 (2)	0.2652 (14)	−0.1204 (10)	0.018 (3)*
H11	1.270 (2)	0.3527 (14)	−0.1017 (12)	0.023 (3)*
H12	1.490 (2)	0.5575 (16)	−0.1701 (12)	0.032 (3)*
H13	1.301 (2)	0.7165 (15)	−0.2597 (11)	0.026 (3)*
H14	0.899 (2)	0.6610 (15)	−0.2710 (11)	0.026 (3)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0190 (4)	0.0163 (4)	0.0167 (4)	0.0053 (3)	0.0056 (3)	0.0061 (3)
C2	0.0160 (4)	0.0132 (4)	0.0189 (4)	0.0022 (3)	0.0044 (3)	0.0049 (3)
C3	0.0161 (4)	0.0164 (4)	0.0155 (4)	0.0063 (3)	0.0012 (3)	0.0020 (3)
C4	0.0151 (4)	0.0143 (4)	0.0150 (4)	0.0042 (3)	0.0027 (3)	0.0032 (3)
C5	0.0148 (4)	0.0156 (4)	0.0165 (4)	0.0035 (3)	0.0014 (3)	0.0032 (3)
C6	0.0183 (4)	0.0210 (4)	0.0186 (4)	0.0088 (3)	0.0060 (3)	0.0066 (3)
C7	0.0254 (5)	0.0216 (4)	0.0211 (4)	0.0094 (4)	0.0055 (4)	−0.0004 (3)
C8	0.0209 (5)	0.0239 (5)	0.0282 (5)	0.0043 (4)	−0.0002 (4)	−0.0094 (4)
C9	0.0198 (4)	0.0129 (4)	0.0175 (4)	0.0054 (3)	0.0059 (3)	0.0025 (3)
C10	0.0166 (4)	0.0115 (3)	0.0154 (4)	0.0039 (3)	0.0031 (3)	0.0010 (3)
C11	0.0173 (4)	0.0166 (4)	0.0222 (4)	0.0061 (3)	0.0021 (3)	0.0044 (3)
C12	0.0157 (4)	0.0190 (4)	0.0238 (4)	0.0025 (3)	0.0028 (3)	0.0023 (3)
C13	0.0203 (4)	0.0135 (4)	0.0205 (4)	0.0008 (3)	0.0039 (3)	0.0025 (3)
C14	0.0215 (4)	0.0141 (4)	0.0203 (4)	0.0052 (3)	0.0027 (3)	0.0046 (3)
N1	0.0171 (3)	0.0109 (3)	0.0137 (3)	0.0035 (3)	0.0027 (3)	0.0022 (2)
N2	0.0158 (4)	0.0221 (4)	0.0253 (4)	0.0034 (3)	0.0011 (3)	−0.0044 (3)
N3	0.0180 (3)	0.0146 (3)	0.0199 (4)	0.0053 (3)	0.0032 (3)	0.0045 (3)

Geometric parameters (Å, º)

C1—C2	1.5229 (12)	C7—H7	0.977 (14)
C1—C1^i	1.5244 (17)	C8—N2	1.3506 (13)
C1—H1A	1.026 (13)	C8—H8	0.984 (15)
C1—H1B	0.972 (13)	C9—N1	1.4671 (11)
C2—N1	1.4687 (10)	C9—C10	1.5091 (11)
C2—H2A	0.977 (12)	C9—H9A	1.018 (13)
C2—H2B	1.015 (12)	C9—H9B	1.019 (12)
C3—N1	1.4651 (11)	C10—N3	1.3435 (11)
C3—C4	1.5085 (12)	C10—C11	1.3957 (12)
C3—H3A	1.026 (12)	C11—C12	1.3872 (13)
C3—H3B	1.018 (12)	C11—H11	1.009 (12)
C4—N2	1.3363 (12)	C12—C13	1.3899 (13)
C4—C5	1.3950 (12)	C12—H12	0.983 (13)
C5—C6	1.3881 (12)	C13—C14	1.3841 (13)
C5—H5	0.945 (14)	C13—H13	0.976 (13)
C6—C7	1.3821 (14)	C14—N3	1.3447 (11)
C6—H6	0.984 (12)	C14—H14	0.992 (13)
C7—C8	1.3801 (15)
C2—C1—C1^i	112.98 (9)	N2—C8—C7	123.47 (9)
C2—C1—H1A	106.9 (7)	N2—C8—H8	115.6 (8)
C1^i—C1—H1A	110.2 (7)	C7—C8—H8	121.0 (8)
C2—C1—H1B	110.7 (7)	N1—C9—C10	110.95 (7)
C1^i—C1—H1B	109.7 (8)	N1—C9—H9A	108.2 (7)
H1A—C1—H1B	106.0 (10)	C10—C9—H9A	107.7 (7)
N1—C2—C1	113.85 (7)	N1—C9—H9B	112.1 (7)
N1—C2—H2A	108.4 (7)	C10—C9—H9B	108.0 (7)
C1—C2—H2A	106.7 (6)	H9A—C9—H9B	109.8 (10)
N1—C2—H2B	111.8 (7)	N3—C10—C11	122.38 (8)
C1—C2—H2B	109.1 (7)	N3—C10—C9	117.05 (8)
H2A—C2—H2B	106.6 (10)	C11—C10—C9	120.57 (7)
N1—C3—C4	112.34 (7)	C12—C11—C10	119.46 (8)
N1—C3—H3A	109.3 (6)	C12—C11—H11	119.6 (7)
C4—C3—H3A	107.3 (7)	C10—C11—H11	121.0 (7)
N1—C3—H3B	112.2 (7)	C11—C12—C13	118.45 (9)
C4—C3—H3B	108.5 (7)	C11—C12—H12	118.1 (8)
H3A—C3—H3B	107.0 (9)	C13—C12—H12	123.5 (8)
N2—C4—C5	122.54 (8)	C14—C13—C12	118.36 (8)
N2—C4—C3	116.67 (8)	C14—C13—H13	120.8 (7)
C5—C4—C3	120.74 (8)	C12—C13—H13	120.9 (7)
C6—C5—C4	119.15 (8)	N3—C14—C13	124.01 (8)
C6—C5—H5	119.9 (8)	N3—C14—H14	116.0 (7)
C4—C5—H5	120.8 (8)	C13—C14—H14	120.0 (7)
C7—C6—C5	118.58 (8)	C3—N1—C9	110.03 (7)
C7—C6—H6	120.9 (7)	C3—N1—C2	109.96 (7)
C5—C6—H6	120.5 (7)	C9—N1—C2	111.55 (7)
C8—C7—C6	118.77 (9)	C4—N2—C8	117.49 (8)
C8—C7—H7	119.6 (8)	C10—N3—C14	117.33 (8)
C6—C7—H7	121.6 (8)
C1^i—C1—C2—N1	−56.58 (12)	C12—C13—C14—N3	−0.48 (14)
N1—C3—C4—N2	136.20 (8)	C4—C3—N1—C9	164.47 (7)
N1—C3—C4—C5	−46.42 (10)	C4—C3—N1—C2	−72.29 (9)
N2—C4—C5—C6	0.85 (13)	C10—C9—N1—C3	−71.12 (9)
C3—C4—C5—C6	−176.36 (8)	C10—C9—N1—C2	166.57 (7)
C4—C5—C6—C7	−0.34 (12)	C1—C2—N1—C3	165.15 (7)
C5—C6—C7—C8	−0.06 (14)	C1—C2—N1—C9	−72.50 (9)
C6—C7—C8—N2	0.00 (17)	C5—C4—N2—C8	−0.90 (14)
N1—C9—C10—N3	120.23 (8)	C3—C4—N2—C8	176.42 (8)
N1—C9—C10—C11	−59.36 (10)	C7—C8—N2—C4	0.48 (16)
N3—C10—C11—C12	−0.65 (13)	C11—C10—N3—C14	0.60 (13)
C9—C10—C11—C12	178.91 (8)	C9—C10—N3—C14	−178.97 (7)
C10—C11—C12—C13	0.11 (14)	C13—C14—N3—C10	−0.04 (13)
C11—C12—C13—C14	0.42 (13)

Symmetry code: (i) −x+2, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6···N2^ii	0.98 (1)	2.42 (1)	3.405 (1)	177 (1)
C12—H12···N3^ii	0.98 (1)	2.57 (2)	3.484 (1)	155 (1)
C7—H7···Cg2^iii	0.98 (1)	2.79 (2)	3.663 (1)	149 (1)
C9—H9A···Cg2^iv	1.02 (1)	2.72 (2)	3.545 (1)	139 (1)
C14—H14···Cg1^v	0.99 (1)	2.86 (2)	3.756 (1)	151 (1)

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