A novel two-dimensional cobalt(II) coordination polymer with 1,4-bis(1,2,4-triazol-1-yl­methyl)­benzene

In the crystal structure of the title complex, poly­[[di­azidocobalt(II)]-di-μ-1,4-bis(1,2,4-triazol-1-yl­methyl)­benzene-κ⁴N⁴:N^4′], [Co(N₃)₂(bbtz)₂]_n, where bbtz is 1,4-bis(1,2,4-triazol-1-yl­methyl)­benzene (C₁₂H₁₂N₆), the Co^II atom, which lies on an inversion centre, is six-coordinated by four N atoms from four bbtz ligands and by two N atoms from two azide ligands, in a distorted octahedral coordination environment. The Co^II atoms are bridged by four bbtz ligands to form a two-dimensional [4,4]-network.

S1. Comment

The construction of coordination polymeric architectures is a rapidly developing area of research, because of their fascinating structural motifs and potential applications as functional materials (Batten & Robson, 1998; Moulton & Zaworotko, 2001). Rigid rod-like N-donor ligands have been intensively employed and a variety of topological architectures have been synthesized (Fujita et al., 1994; Li et al., 2001). However, flexible ligands containing triazole or imidazole have not been well studied to date (Effendy et al., 2004; Van Albada et al., 2000; Shen et al., 1999). In our previous studies, we synthesized several coordination polymers with the flexible ligand 1,2-bis(1,2,4-triazol-1-yl)ethane (bte; Li et al., 2003; Zhu et al., 2004). Here, we report the preparation and crystal structure of a novel two-dimensional coordination polymer incorporating the 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (bbtz) ligand, the title compound, (I). \sch

As shown in Fig. 1, the Co^II atom of (I) occupies an inversion centre. The coordination geometry of the Co^II atom is distorted octahedral, coordinated equatorially by four N atoms from the triazole rings of four symmetry-related bbtz ligands, and axially by two N atoms from two symmetry-related azide ligands. This coordination environment is similar to those observed in [Co(4-benzoylpyridine)₄(N₃)₂] (Goher & Mautner, 1999a), {[Co(bpm)₂(N₃)₂][Co(bpm)₂(H₂O)₂]}(ClO₄)₂ [bpm is bis(pyrazol-1-yl)methane; Tang et al., 2000) and [Co(4-methylpyridine)₄(N₃)](PF₆) (Goher & Mautner, 1999b).

The azide anion normally coordinates to Co^II and other metal atoms in the µ-1,1- or µ-1,3-mode (De Munno et al., 1996; Viau et al., 1997; Goher & Mautner, 1999b; Wang et al., 2003; Ribas et al., 1999). Few studies of Co^II complexes with monodentate azide have been reported to date (Randaccio et al., 1998; Goher & Mautner, 1999a; Tang et al., 2000). The Co—N(N₃) bond length is 2.1381 (18) Å, longer than the corresponding values reported for azidecobalamin [1.985 (3) Å; Randaccio et al., 1998], [Co(4-benzoylpyridine)₄(N₃)₂] [2.091 (2) Å; Goher & Maunter, 1999a] and {[Co(bpm)₂(N₃)₂][Co(bpm)₂(H₂O)₂]}(ClO₄)₂ [2.107 (3) Å; Tang et al., 2000], and a little shorter than those found in the structure of [Co(4-methylpyridine)₄(N₃)](PF₆), containing µ-1,3-bridging azide ligands (2.153–2.159 Å; Goher & Mautner, 1999b). The Co—N—N(N₃) bond angle is 130.23 (15)°, close to the corresponding values of 116.0 (3), 128.2 (2), 129.3 (3) and 135.4 (2)°, respectively, in these same four cited compounds. The azide ligand is almost linear in (I) [N—N—N 176.2 (3)°], in good agreement with data usually obtained for monodentate azide complexes.

Because the methyl C atom of bbtz can rotate freely to adjust itself to the coordination environment, bbtz can exhibit the trans-gauche and gauche-gauche conformations, similar to the ligand 1,4-bis(imidazol-1-ylmethyl)benzene (bix), as shown in the polyrotaxane [Ag₂(bix)₃](NO₃)₂ (Hoskins et al., 1997a). The bbtz ligands exhibit the trans-gauche conformation in (I), similar to bix in [Mn(bix)₃(NO₂)₂·4H₂O], (II) (Shen et al., 1999). The three rings (two triazole rings and one benzene ring) of one bbtz ligand are not coplanar. The dihedral angle between the two triazole planes is 61.94 (19)°, compared with 39.1° in the terminal bix in (II). The dihedral angles between the benzene plane and the N1- and N4-triazole planes are 67.26 (9) and 66.96 (7)°, respectively, similar to the corresponding values in the terminal bix in (II), 88.9 and 77.4°. In the bridged bix in (II), the dihedral angles between the imidazole and benzene planes are 106.0 and 91.4°, respectively. Comparison with the free-ligand structures p-(N,N-dimethylamino)phenyl-1,2,4-triazol-1-yl-ketone-p- nitrophenylhydrazone, (III) (Stanković et al., 1991), and (RS,SR)-4-(3-(4-fluorophenyl)-2-hydroxy-1-(1,2,4-triazol-1-yl)-propyl) benzonitrile, (IV) (Sodervall & Mutikainen, 2002), containing three rings (one triazole ring and two benzene rings), shows a much wider variation in these interplanar angles. For example, the dihedral angles between two benzene planes is 9.0 and 62.7° (mean) for (III) and (IV).

As illustrated in Fig. 2, each bbtz ligand in (I) coordinates to Co^II atoms through its two triazole N atoms, thus acting as a bridging bidentate ligand to form a two-dimensional neutral [4,4] network. The networks contain square grids (52-membered rings), with a Co^II atom at each corner and a bbtz ligand at each edge connecting two Co^II atoms. The square-grid sheets are stacked in an off-set fashion parallel to the c direction. The off-set half-cell superposition of each pair of adjacent networks divides the voids into smaller rectangles. The azide anions of one sheet project into the holes of the next sheet. In the superposition structure, the sheets are arranged in the sequence ···A—B—A—B···. As a consequence of the symmetry of the crystal structure, the edge lengths are equal with the value of 14.4156 (18) Å, similar to the corresponding metal-metal separation in the related bix complexes [Zn(bix)₂(NO₃)₂]·4.5H₂O [15.037 (2) Å; Hoskins et al., 1997b], [Ag₂(bix)₃(NO₃)₂] [14.626 (2) Å; Hoskins et al., 1997a] and [Mn(bix)₃(NO₂)·4H₂O] [12.659 Å; Shen et al., 1999].

The structures of [Cu(btp)₂(CH₃CN)(H₂O)](CF₃SO₃)₂, (V), and [Cu(btp)₂(CH₃CN)₂](ClO₄)₂, (VI), with the related triazole ligand 1,3-bis(1,2,4-triazol-1-yl)propane (btp; Van Albada et al., 2000), have a similar distorted octahedral structure, coordinated equatorially by four N atoms from the triazole rings of four symmetry-related btp ligands, and axially by one N atom from one CH₃CN molecule and one O atom from one water molecule for (V), and axially by two N atoms from two CH₃CN molecules for (VI). In both these structures, the Cu^II atoms are linked by the bridging btp ligands, resulting in two-dimensional networks with shortest Cu—Cu distances 8.753 (3) in (V) and 8.946 (4) Å in (VI). The metal-metal distances in structures containing triazole and imidazole ligands confirm the important ability of this family of ligands to adjust that distance.

S2. Experimental

An H₂O/CH₃CN solution (1:1 v/v, 20 ml) of 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (bbtz; 0.060 g, 0.25 mmol) was added to one leg of an H-shaped tube, and an H₂O/CH₃CN solution (1:1 v/v, 20 ml) of NaN₃ (0.078 g, 1.2 mmol) and Co(NO₃)₂·6H₂O (0.146 g, 0.5 mmol) was added to the other leg. Well shaped pink crystals of (I) suitable for X-ray analysis were obtained after about three months. The product is stable in ambient atmosphere and is insoluble in most common inorganic and organic solvents. Analysis, found: C 46.17, H 3.91, N 40.38%; calculated for C₂₄H₂₄CoN₁₈: C 46.23, H 3.88, N 40.44%.

S3. Refinement

H atoms were placed in idealized positions and refined as riding, with C—H distances of 0.95 (triazole and benzene) and 0.99 Å (methane), and with U_iso(H) = 1.2 U_eq(C).

Computing details

Data collection: CrystalClear (Rigaku, 2000); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1998); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. A view of the local coordination of the Co^II atom in (I), with displacement ellipsoids drawn at the 50% probability level. Only the atoms of the asymmetric unit have been labelled.
	Fig. 2. Part of the two-dimensional sheet of the [4,4] network in (I). H atoms and the next offset sheet (see text) have been omitted for clarity.

poly[[diazidocobalt(II)]-di-µ-1,4-bis(1,2,4-triazol-1-ylmethyl)benzene- κ²N⁴:N^4']

Crystal data

[Co(N3)2(C12H12N6)2]	F(000) = 642
Mr = 623.54	Dx = 1.492 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 5765 reflections
a = 8.2682 (17) Å	θ = 3.1–27.5°
b = 20.593 (4) Å	µ = 0.67 mm^−1
c = 8.3738 (17) Å	T = 193 K
β = 103.273 (4)°	Block, pink
V = 1387.7 (5) Å^3	0.60 × 0.25 × 0.22 mm
Z = 2

Data collection

Rigaku Mercury CCD area-detector diffractometer	3172 independent reflections
Radiation source: fine-focus sealed tube	2772 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.032
ω scans	θmax = 27.5°, θmin = 3.2°
Absorption correction: multi-scan (North et al., 1968)	h = −10→10
Tmin = 0.786, Tmax = 0.867	k = −26→22
15397 measured reflections	l = −10→10

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)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.106	H-atom parameters constrained
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0492P)^2 + 0.6596P] where P = (Fo^2 + 2Fc^2)/3
3172 reflections	(Δ/σ)max < 0.001
197 parameters	Δρmax = 0.36 e Å^−3
0 restraints	Δρmin = −0.32 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
Co1	0.5000	0.5000	0.0000	0.02530 (13)
N1	0.4034 (2)	0.58620 (8)	0.4340 (2)	0.0308 (4)
N2	0.5715 (2)	0.58709 (10)	0.4858 (3)	0.0441 (5)
N3	0.4957 (2)	0.54301 (8)	0.2346 (2)	0.0286 (4)
N4	−0.2435 (2)	0.84488 (9)	0.3283 (2)	0.0339 (4)
N5	−0.3620 (2)	0.80809 (9)	0.3736 (3)	0.0408 (5)
N6	−0.3808 (2)	0.91232 (8)	0.4464 (2)	0.0296 (4)
N7	0.2645 (2)	0.54614 (9)	−0.0864 (2)	0.0343 (4)
N8	0.1417 (2)	0.52611 (9)	−0.1685 (2)	0.0334 (4)
N9	0.0185 (3)	0.50864 (12)	−0.2576 (4)	0.0630 (7)
C1	0.1839 (3)	0.66462 (10)	0.4614 (3)	0.0323 (5)
C2	0.0330 (3)	0.65135 (11)	0.3566 (3)	0.0426 (6)
H2A	−0.0010	0.6075	0.3350	0.051*
C3	−0.0697 (3)	0.70118 (12)	0.2824 (3)	0.0442 (6)
H3A	−0.1730	0.6912	0.2099	0.053*
C4	−0.0237 (3)	0.76489 (11)	0.3127 (3)	0.0350 (5)
C5	0.1259 (3)	0.77850 (12)	0.4197 (4)	0.0473 (6)
H5A	0.1588	0.8224	0.4425	0.057*
C6	0.2290 (3)	0.72854 (12)	0.4945 (3)	0.0458 (6)
H6A	0.3312	0.7385	0.5689	0.055*
C7	0.2949 (3)	0.60921 (12)	0.5384 (3)	0.0427 (6)
H7A	0.3644	0.6237	0.6451	0.051*
H7B	0.2249	0.5727	0.5600	0.051*
C8	−0.1352 (3)	0.81853 (13)	0.2272 (3)	0.0482 (6)
H8A	−0.0656	0.8540	0.1994	0.058*
H8B	−0.2049	0.8016	0.1234	0.058*
C9	0.6197 (3)	0.56050 (12)	0.3618 (3)	0.0379 (5)
H9A	0.7335	0.5541	0.3618	0.045*
C10	0.3613 (3)	0.56009 (11)	0.2858 (3)	0.0351 (5)
H10A	0.2503	0.5544	0.2247	0.042*
C11	−0.4403 (3)	0.85116 (10)	0.4447 (3)	0.0352 (5)
H11A	−0.5312	0.8401	0.4911	0.042*
C12	−0.2571 (3)	0.90603 (11)	0.3714 (3)	0.0335 (5)
H12A	−0.1880	0.9405	0.3514	0.040*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Co1	0.0223 (2)	0.0293 (2)	0.0268 (2)	−0.00108 (14)	0.01071 (15)	−0.00124 (15)
N1	0.0314 (9)	0.0339 (9)	0.0287 (9)	0.0083 (7)	0.0101 (7)	−0.0001 (7)
N2	0.0345 (10)	0.0536 (13)	0.0424 (11)	0.0065 (9)	0.0052 (9)	−0.0123 (9)
N3	0.0268 (8)	0.0313 (9)	0.0304 (9)	−0.0013 (7)	0.0123 (7)	−0.0035 (7)
N4	0.0348 (9)	0.0368 (10)	0.0339 (9)	0.0114 (8)	0.0159 (8)	0.0069 (8)
N5	0.0386 (10)	0.0339 (10)	0.0523 (12)	0.0054 (8)	0.0151 (9)	0.0021 (9)
N6	0.0248 (8)	0.0341 (10)	0.0320 (9)	0.0031 (7)	0.0113 (7)	0.0023 (7)
N7	0.0284 (9)	0.0357 (10)	0.0389 (10)	0.0032 (7)	0.0078 (8)	0.0000 (8)
N8	0.0285 (10)	0.0291 (9)	0.0469 (11)	0.0030 (7)	0.0176 (9)	−0.0051 (8)
N9	0.0260 (11)	0.0694 (16)	0.0911 (19)	−0.0023 (10)	0.0082 (11)	−0.0401 (14)
C1	0.0355 (11)	0.0356 (12)	0.0302 (10)	0.0078 (9)	0.0165 (9)	−0.0010 (8)
C2	0.0395 (12)	0.0314 (12)	0.0566 (15)	0.0012 (10)	0.0105 (11)	−0.0087 (10)
C3	0.0336 (12)	0.0476 (15)	0.0474 (14)	0.0061 (10)	0.0011 (10)	−0.0104 (11)
C4	0.0384 (12)	0.0363 (12)	0.0358 (11)	0.0111 (9)	0.0201 (10)	0.0016 (9)
C5	0.0436 (13)	0.0297 (12)	0.0712 (18)	−0.0002 (10)	0.0183 (13)	−0.0057 (11)
C6	0.0318 (12)	0.0453 (14)	0.0578 (15)	0.0016 (10)	0.0048 (11)	−0.0120 (12)
C7	0.0494 (14)	0.0512 (14)	0.0322 (11)	0.0215 (11)	0.0190 (10)	0.0044 (10)
C8	0.0595 (16)	0.0516 (15)	0.0426 (13)	0.0263 (12)	0.0306 (12)	0.0112 (11)
C9	0.0247 (10)	0.0475 (13)	0.0422 (12)	0.0029 (9)	0.0091 (9)	−0.0093 (10)
C10	0.0268 (10)	0.0494 (13)	0.0304 (11)	0.0009 (9)	0.0092 (8)	−0.0063 (9)
C11	0.0272 (10)	0.0348 (12)	0.0463 (13)	0.0030 (8)	0.0140 (9)	0.0046 (9)
C12	0.0317 (11)	0.0353 (12)	0.0373 (12)	0.0052 (9)	0.0156 (9)	0.0054 (9)

Geometric parameters (Å, º)

Co1—N7	2.1381 (18)	C1—C2	1.378 (3)
Co1—N7^i	2.1381 (18)	C1—C6	1.379 (3)
Co1—N6^ii	2.1529 (17)	C1—C7	1.513 (3)
Co1—N6^iii	2.1529 (17)	C2—C3	1.385 (3)
Co1—N3	2.1628 (17)	C2—H2A	0.9500
Co1—N3^i	2.1628 (17)	C3—C4	1.373 (3)
N1—C10	1.323 (3)	C3—H3A	0.9500
N1—N2	1.358 (3)	C4—C5	1.380 (3)
N1—C7	1.468 (3)	C4—C8	1.510 (3)
N2—C9	1.315 (3)	C5—C6	1.390 (3)
N3—C10	1.327 (3)	C5—H5A	0.9500
N3—C9	1.347 (3)	C6—H6A	0.9500
N4—C12	1.322 (3)	C7—H7A	0.9900
N4—N5	1.360 (3)	C7—H7B	0.9900
N4—C8	1.470 (3)	C8—H8A	0.9900
N5—C11	1.318 (3)	C8—H8B	0.9900
N6—C12	1.324 (3)	C9—H9A	0.9500
N6—C11	1.351 (3)	C10—H10A	0.9500
N6—Co1^iv	2.1529 (17)	C11—H11A	0.9500
N7—N8	1.163 (2)	C12—H12A	0.9500
N8—N9	1.172 (3)
N7—Co1—N7^i	180.00 (9)	C4—C3—C2	120.7 (2)
N7—Co1—N6^ii	88.95 (7)	C4—C3—H3A	119.7
N7^i—Co1—N6^ii	91.05 (7)	C2—C3—H3A	119.7
N7—Co1—N6^iii	91.05 (7)	C3—C4—C5	118.9 (2)
N7^i—Co1—N6^iii	88.95 (7)	C3—C4—C8	119.9 (2)
N6^ii—Co1—N6^iii	180.00 (9)	C5—C4—C8	121.2 (2)
N7—Co1—N3	85.51 (7)	C4—C5—C6	120.5 (2)
N7^i—Co1—N3	94.49 (7)	C4—C5—H5A	119.7
N6^ii—Co1—N3	87.11 (6)	C6—C5—H5A	119.7
N6^iii—Co1—N3	92.89 (6)	C1—C6—C5	120.4 (2)
N7—Co1—N3^i	94.49 (7)	C1—C6—H6A	119.8
N7^i—Co1—N3^i	85.51 (7)	C5—C6—H6A	119.8
N6^ii—Co1—N3^i	92.89 (6)	N1—C7—C1	112.54 (18)
N6^iii—Co1—N3^i	87.11 (6)	N1—C7—H7A	109.1
N3—Co1—N3^i	180.00 (9)	C1—C7—H7A	109.1
C10—N1—N2	109.56 (17)	N1—C7—H7B	109.1
C10—N1—C7	128.66 (19)	C1—C7—H7B	109.1
N2—N1—C7	121.73 (18)	H7A—C7—H7B	107.8
C9—N2—N1	102.46 (18)	N4—C8—C4	112.52 (18)
C10—N3—C9	102.45 (17)	N4—C8—H8A	109.1
C10—N3—Co1	126.28 (14)	C4—C8—H8A	109.1
C9—N3—Co1	131.25 (14)	N4—C8—H8B	109.1
C12—N4—N5	110.05 (17)	C4—C8—H8B	109.1
C12—N4—C8	127.6 (2)	H8A—C8—H8B	107.8
N5—N4—C8	121.89 (19)	N2—C9—N3	114.96 (19)
C11—N5—N4	102.19 (18)	N2—C9—H9A	122.5
C12—N6—C11	102.86 (18)	N3—C9—H9A	122.5
C12—N6—Co1^iv	128.42 (14)	N1—C10—N3	110.57 (19)
C11—N6—Co1^iv	126.96 (13)	N1—C10—H10A	124.7
N8—N7—Co1	130.23 (15)	N3—C10—H10A	124.7
N7—N8—N9	176.2 (3)	N5—C11—N6	114.65 (19)
C2—C1—C6	118.7 (2)	N5—C11—H11A	122.7
C2—C1—C7	119.6 (2)	N6—C11—H11A	122.7
C6—C1—C7	121.7 (2)	N6—C12—N4	110.25 (19)
C1—C2—C3	120.7 (2)	N6—C12—H12A	124.9
C1—C2—H2A	119.6	N4—C12—H12A	124.9
C3—C2—H2A	119.6
C10—N1—N2—C9	−0.2 (3)	C7—C1—C6—C5	178.9 (2)
C7—N1—N2—C9	177.4 (2)	C4—C5—C6—C1	0.7 (4)
N7—Co1—N3—C10	25.19 (18)	C10—N1—C7—C1	−62.2 (3)
N7^i—Co1—N3—C10	−154.81 (18)	N2—N1—C7—C1	120.7 (2)
N6^ii—Co1—N3—C10	114.37 (18)	C2—C1—C7—N1	86.8 (3)
N6^iii—Co1—N3—C10	−65.63 (18)	C6—C1—C7—N1	−93.8 (3)
N7—Co1—N3—C9	−153.3 (2)	C12—N4—C8—C4	124.5 (3)
N7^i—Co1—N3—C9	26.7 (2)	N5—N4—C8—C4	−64.2 (3)
N6^ii—Co1—N3—C9	−64.1 (2)	C3—C4—C8—N4	96.3 (3)
N6^iii—Co1—N3—C9	115.9 (2)	C5—C4—C8—N4	−84.7 (3)
C12—N4—N5—C11	−0.6 (2)	N1—N2—C9—N3	0.3 (3)
C8—N4—N5—C11	−173.3 (2)	C10—N3—C9—N2	−0.3 (3)
N6^ii—Co1—N7—N8	137.8 (2)	Co1—N3—C9—N2	178.44 (16)
N6^iii—Co1—N7—N8	−42.2 (2)	N2—N1—C10—N3	0.0 (3)
N3—Co1—N7—N8	−135.0 (2)	C7—N1—C10—N3	−177.3 (2)
N3^i—Co1—N7—N8	45.0 (2)	C9—N3—C10—N1	0.1 (3)
C6—C1—C2—C3	1.7 (4)	Co1—N3—C10—N1	−178.68 (14)
C7—C1—C2—C3	−178.9 (2)	N4—N5—C11—N6	0.5 (3)
C1—C2—C3—C4	−0.5 (4)	C12—N6—C11—N5	−0.2 (3)
C2—C3—C4—C5	−0.6 (4)	Co1^iv—N6—C11—N5	165.60 (15)
C2—C3—C4—C8	178.4 (2)	C11—N6—C12—N4	−0.2 (2)
C3—C4—C5—C6	0.5 (4)	Co1^iv—N6—C12—N4	−165.74 (14)
C8—C4—C5—C6	−178.4 (2)	N5—N4—C12—N6	0.5 (3)
C2—C1—C6—C5	−1.8 (4)	C8—N4—C12—N6	172.7 (2)

Symmetry codes: (i) −x+1, −y+1, −z; (ii) x+1, −y+3/2, z−1/2; (iii) −x, y−1/2, −z+1/2; (iv) −x, y+1/2, −z+1/2.