Two one-dimensional linear zinc(II) polymers: catena-poly[[[2,6-bis­(1H-benzimidazol-2-yl-[kappa]N³)pyridine]zinc(II)]-[mu]-pyridine-2,4-di­carboxyl­ato-[kappa]²O²:O⁴] and catena-poly[[[2,6-bis­(1H-benzimidazol-2-yl-[kappa]N³)pyri­dine]zinc(II)]-[mu]-pyridine-2,5-di­car­boxyl­ato-[kappa]²O²:O⁵]

The solvothermal reactions of 2,6-bis­(1H-benzimidazol-2-yl)pyridine (H₂bpp) and hydrated ZnCl₂ in the presence of pyridine-2,4-di­carb­oxy­lic acid (2,4-pdcH₂) or pyridine-2,5-di­carb­oxy­lic acid (2,5-pdcH₂) afforded the title one-dimensional linear compounds, [Zn(C₇H₃NO₄)(C₁₉H₁₃N₅)]_n or [Zn(2,4-pdc)(H₂bpp)]_n, (I), and [Zn(C₇H₃NO₄)(C₁₉H₁₃N₅)]_n or [Zn(2,5-pdc)(H₂bpp)]_n, (II), respectively. The Zn^II cations in these compounds have closely comparable geometries and both are octa­hedrally coordinated by N₄O₂ donor sets. The thermal stabilities have been investigated by thermogravimetric analysis (TGA) on the crystalline samples and their solid-state photoluminescence properties have been investigated at room temperature.

S1. Comment

The rational design and synthesis of inorganic–organic hybrid materials, consisting of N/O-donor ligands and transition metal ions, is an attractive area in materials science (Ho & Wong, 2011). Benzimidazole and its derivatives have rich coordination chemistries and biological activities. Many compounds including this class of ligand exhibit antitumour, antiviral, anticancer, antimicrobial, antiprotozoal or analgesic properties (Hong et al., 2008). 2,6-Bis(1H-benzimidazol-2-yl)pyridine (H₂bpp) has two adjacent nucleophilic benzimidazole rings which could bond to metal centres, either in a monodentate manner via the pyridine N atom or in a bridging manner through all the N atoms. In the first case, the pyrrole N—H groups of H₂bpp readily form hydrogen-bonding interactions, which may lead to interesting molecular packing in the solid state. Thus, not only may H₂bpp act as a tridentate ligand to metal ions but it also has the potential to form supramolecular interactions through π–π stacking and hydrogen bonding (Liu et al., 2011). Although the coordination chemistry of H₂bpp is well researched, reports of H₂bpp ligands with additional pyridyl multicarboxylic functional binding sites are rare (Tan et al., 2009). Moreover, there has been growing interest in the photochemistry of Zn^II-containing coordination polymers because the coordination geometries can vary from tetrahedral through trigonal–bipyramidal and square–pyramidal to octahedral, making them suitable for the construction of luminescent coordination polymers (Zheng & Chen, 2004). Therefore, Zn^II coordination compounds containing a mixture of H₂bpp and pyridinedicarboxylic acid ligands are worthy of further study.

The asymmetric unit of catena-poly[[[2,6-bis(1H-benzimidazol-2-yl-κN³)pyridine]zinc(II)]-µ-pyridine-2,4-dicarboxylato-κ²O²:O⁴], (I), consists of one H₂bpp ligand, one pyridine-2,4-dicarboxylate (2,4-pdc^2-) ligand and one octahedrally coordinated Zn^II cation (Fig. 1a). The coordination environment of the Zn^II cation involves three N atoms from an H₂bpp ligand and two symmetry-related 2,4-pdc^2- ligands, one donating from the pyridine N atom and a carboxylate O atom, and the other from a carboxylate O atom only. The bridging mode of the 2,4-pdc^2- ligand leads to an extended one-dimensional chain along the c axis (Fig. 2). Atoms O2 and O4 form strong hydrogen bonds with the N—H group of an adjacent [Zn(2,4-pdc)(H₂bpp)] unit, which is indicated by the shorter N5···O4ⁱ and N2···O2ⁱⁱ distances (see Table 2 for hydrogen-bond details and symmetry codes). In addition, extensive intra- and intermolecular π–π interactions are found. The pyridine rings of the H₂bpp and 2,4-pdc^2- ligands form offset face-to-face π–π stacks, with an average centroid-to-centroid distance of 3.676(s.u.?) Å. π-Stacking interactions also exist between the benzimidazole rings of adjacent chains, with an average centroid-to-centroid distance of 4.139(s.u.?) Å. The pyridine ring of the H₂bpp ligand is coplanar with the two adjacent benzimidazole rings. The carboxylate groups of the 2,4-pdc^2- ligand form different dihedral angles with respect to the attached pyridine ring, with values of 10.1(s.u.?) and 30.8(s.u.?)°. This difference possibly results from the different bonding modes and intermolecular hydrogen bonds with the N—H group of the H₂bpp ligand. These relatively weak interactions could be regarded as the stabilizing factor for (I). The equatorial Zn—N bond lengths are normal (Table 1) and the axial Zn—O bond lengths are similar to those of related Zn compounds containing these types of ligands (Erxleben, 2003). The closest intra-chain Zn···Zn separation is 7.940(s.u.?) Å.

The asymmetric unit of catena-poly[[[2,6-bis(1H-benzimidazol-2-yl-κN³)pyridine]zinc(II)]-µ-pyridine-2,5-dicarboxylato-κ²O²:O⁵], (II), consists of one H₂bpp ligand, one pyridine-2,5-dicarboxylate (2,5-pdc^2-) ligand and one Zn^II cation (Fig. 1b). As in (I), the Zn^II cation is six-coordinated in a distorted octahedral geometry via four N- and two O-atom donors. The coordination environment of the Zn^II cayion is closely comparable with that of (I). The dihedral angles of the carboxylate groups of the 2,5-pdc^2- ligands with respect to the attached pyridine ring are 19.0(s.u.?) and 21.9(s.u.?)°. The N—H groups of the H₂bpp ligand also form strong hydrogen bonds with the carboxylate O atoms (N5···O4 and N2···O1; see Table 4 for hydrogen-bond details and symmetry codes). The equatorial Zn—N bond lengths (Table 3) are similar to those of (I). The axial Zn—O3ⁱ bond is significantly shorter than the Zn—O1 bond. The bridging behaviour of the 2,5-pdc^2- ligand leads to a one-dimensional infinite zigzag chain along the b axis (Fig. 3). The closest intra-chain Zn···Zn separation is 8.488(s.u.?) Å. In the crystal packing, extensive π–π stacking interactions are found between benzimidazole rings, with an average centroid-to-centroid separation of 3.743(s.u.?) Å.

Thermogravimetric analysis (TGA) was performed on single-crystal samples of (I) and (II) under an N₂ atmosphere with a heating rate of 10 K min^-1. The TGA curve shows that both compounds have good thermal stability, since no clean weight-loss step occurs below 653 K. The sharp weight loss above 797 K is due to the decomposition of the framework structures. [No TGA curves have been supplied - do you wish to include them?]

The photoluminescence properties of (I) and (II) have been explored at room temperature in the solid state, as shown in Fig. 4. The free H₂bpp ligand displays blue luminescence with a maximum of 397 nm, which is predominantly fluorescence from π → π* transitions. Upon excitation at λ_ex = 370 nm, (I) and (II) show emission maxima at 428 and 414 nm, respectively, which are 31 and 17 nm red-shifted compared with free H₂bpp. The emission bands may result from intraligand π → π* transition between the π-bonding orbital (highest occupied molecular orbital, HOMO) and π*-antibonding orbital (lowest unoccupied molecular orbital, LUMO) of the H₂bpp ligand, rather than metal-to-ligand charge transfer (MLCT) or ligand-to-metal charge transfer (LMCT). The red shift may be assigned to the nature of the ligand bonding (chelating or bridging) to the Zn^II centre, which changes the rigidity and conjugation of the H₂bpp ligand. These two compounds display photoluminescence in the blue region, which suggests potential as blue light-emitting materials (Liu et al., 2010).

Related literature

For related literature, see: Erxleben (2003); Ho & Wong (2011); Hong et al. (2008); Liu et al. (2010, 2011); Tan et al. (2009); Zheng & Chen (2004).

S2. Experimental

For the synthesis of [Zn(2,4-pdc)(H₂bpp)]_n, (I), the hydrothermal treatment of ZnCl₂.4H₂O (27.5 mg, 0.2 mmol), 2,6-bis(1H-benzimidazol-2-yl)pyridine (62.2 mg, 0.2 mmol) and pyridine-2,4-dicarboxylic acid (36.8 mg, 0.22 mmol) in a mixture of EtOH and water (13 ml, 1:1v/v) for 3 d at 413 K produced a colourless block-shaped crystalline solid [yield 70.4 mg, 0.13 mmol, 65% based on 2,6-bis(1H-benzimidazol-2-yl)pyridine]. Analysis, calculated for C₂₆H₁₆N₆O₄Zn: C 57.64, H 2.98, N 15.51%; found: C 57.60, H 2.80, N 15.62%. IR (KBr, ν, cm^-1): 3415 (w), 1641 (m), 1599 (s), 1581 (s), 1544 (m), 1463 (s), 1358 (s), 1321 (s), 997 (m), 745 (m), 720 (s).

[Zn(2,5-pdc)(H₂bpp)]_n, (II), was prepared according to a procedure similar to that used for the preparation of (I), except that pyridine-2,5-dicarboxylic acid (36.8 mg, 0.22 mmol) was used in place of pyridine-2,4-dicarboxylic acid [yield 58.5 mg, 0.11 mmol, 54% based on 2,6-bis(1H-benzimidazol-2-yl)pyridine]. Analysis, calculated for C₂₆H₁₆N₆O₄Zn: C 57.64, H 2.98, N 15.51%; found: C 57.58, H 3.00, N 15.55%. IR (KBr, ν, cm^-1): 3425 (w), 1646 (m), 1614 (s), 1594 (m), 1461 (m), 1395 (s), 1337 (s), 1320 (m), 1037 (m), 821 (m), 769 (m).

S3. Refinement

H atoms were placed in calculated positions, with C—H = 0.93 Å and N—H = 0.86 Å, and were included in the refinement in the riding-model approximation, with U_iso(H) = 1.2U_eq(C,N).

Computing details

For both compounds, data collection: APEX2 (Bruker, 2004); cell refinement: SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXS97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures

Fig. 1. The molecular structures of (a) (I) and (b) (II), showing the coordination environments of the Zn^II cations and the atom-numbering schemes. Displacement ellipsoids are drawn at the ??% probability level [Please complete]. H atoms except those on N atoms have been omitted for clarity. [Symmetry codes: in (I), (i) x + 1/2, -y + 1/2, z + 1/2; in (II), (i) -x + 1, y + 1/2, -z + 1/2.] Fig. 2. A perspective drawing showing the one-dimensional linear chain of (I). Fig. 3. A perspective drawing showing the one-dimensional zigzag chain of (II). Fig. 4. The emission spectra of (I) and (II) in the solid state at room temperature.

(I) catena-Poly[[[2,6-bis(1H-benzimidazol-2-yl-κN³)pyridine]zinc(II)]-µ-pyridine-2,4-dicarboxylato-κ²O²:O⁴]

Crystal data

[Zn(C7H3NO4)(C19H13N5)]	F(000) = 1104
Mr = 541.82	Dx = 1.635 Mg m^−3
Monoclinic, Cc	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: C -2yc	Cell parameters from 1463 reflections
a = 8.3782 (6) Å	θ = 2.6–28.5°
b = 18.1569 (19) Å	µ = 1.17 mm^−1
c = 14.7588 (15) Å	T = 293 K
β = 101.309 (8)°	Block, colourless
V = 2201.6 (4) Å^3	0.26 × 0.20 × 0.15 mm
Z = 4

Data collection

Bruker APEX area-dectector diffractometer	3858 independent reflections
Radiation source: fine-focus sealed tube	3041 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.046
ϕ and ω scans	θmax = 25.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→9
Tmin = 0.756, Tmax = 0.840	k = −21→21
6495 measured 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)] = 0.039	H-atom parameters constrained
wR(F^2) = 0.074	w = 1/[σ^2(Fo^2) + (0.0181P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max < 0.001
3490 reflections	Δρmax = 0.44 e Å^−3
334 parameters	Δρmin = −0.33 e Å^−3
2 restraints	Absolute structure: Flack (1983), 1602 Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: −0.014 (12)

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
Zn1	0.60568 (5)	0.29903 (3)	0.72505 (4)	0.02624 (14)
N1	0.4548 (4)	0.3858 (2)	0.7702 (3)	0.0268 (9)
N2	0.4439 (4)	0.4842 (2)	0.8584 (3)	0.0298 (10)
H2A	0.4740	0.5173	0.9000	0.036*
N3	0.7651 (4)	0.3591 (2)	0.8306 (3)	0.0238 (9)
N4	0.8305 (4)	0.2421 (2)	0.7415 (3)	0.0254 (9)
N5	1.0853 (4)	0.2286 (2)	0.8186 (3)	0.0272 (9)
H5A	1.1753	0.2376	0.8563	0.033*
N6	0.4329 (4)	0.2641 (2)	0.6107 (3)	0.0220 (8)
O1	0.6534 (3)	0.37063 (19)	0.6201 (2)	0.0336 (8)
O2	0.5524 (4)	0.4078 (2)	0.4771 (3)	0.0525 (11)
O3	0.0153 (3)	0.27838 (18)	0.3166 (2)	0.0314 (8)
O4	−0.1218 (3)	0.2410 (2)	0.4235 (2)	0.0492 (11)
C1	0.2988 (5)	0.4152 (3)	0.7488 (3)	0.0270 (11)
C2	0.1635 (5)	0.3925 (3)	0.6842 (4)	0.0348 (13)
H2	0.1674	0.3506	0.6485	0.042*
C3	0.0250 (6)	0.4338 (3)	0.6748 (4)	0.0409 (13)
H3	−0.0675	0.4195	0.6328	0.049*
C4	0.0207 (6)	0.4972 (3)	0.7274 (4)	0.0499 (16)
H4	−0.0742	0.5251	0.7177	0.060*
C5	0.1512 (5)	0.5203 (3)	0.7932 (4)	0.0407 (14)
H5	0.1462	0.5622	0.8287	0.049*
C6	0.2916 (5)	0.4770 (3)	0.8032 (3)	0.0282 (11)
C7	0.5356 (5)	0.4300 (3)	0.8347 (3)	0.0268 (11)
C8	0.7095 (5)	0.4165 (2)	0.8708 (3)	0.0246 (10)
C9	0.8119 (5)	0.4569 (3)	0.9397 (3)	0.0341 (12)
H9	0.7735	0.4968	0.9685	0.041*
C10	0.9725 (5)	0.4346 (3)	0.9629 (4)	0.0379 (13)
H10	1.0443	0.4611	1.0072	0.045*
C11	1.0288 (5)	0.3743 (3)	0.9222 (3)	0.0306 (12)
H11	1.1366	0.3591	0.9391	0.037*
C12	0.9192 (5)	0.3370 (3)	0.8551 (3)	0.0243 (11)
C13	0.9475 (5)	0.2711 (2)	0.8047 (3)	0.0227 (10)
C14	1.0517 (5)	0.1684 (3)	0.7601 (3)	0.0276 (11)
C15	1.1439 (5)	0.1073 (3)	0.7470 (4)	0.0327 (13)
H15	1.2483	0.1003	0.7814	0.039*
C16	1.0740 (6)	0.0576 (3)	0.6807 (4)	0.0378 (14)
H16	1.1328	0.0163	0.6693	0.045*
C17	0.9168 (5)	0.0679 (3)	0.6306 (4)	0.0368 (13)
H17	0.8736	0.0337	0.5855	0.044*
C18	0.8231 (6)	0.1273 (3)	0.6456 (3)	0.0349 (12)
H18	0.7170	0.1329	0.6130	0.042*
C19	0.8935 (5)	0.1785 (2)	0.7115 (3)	0.0247 (11)
C20	0.4189 (5)	0.3103 (2)	0.5385 (3)	0.0224 (10)
C21	0.2852 (5)	0.3078 (3)	0.4668 (3)	0.0280 (11)
H21	0.2799	0.3389	0.4162	0.034*
C22	0.1590 (5)	0.2592 (3)	0.4699 (3)	0.0242 (10)
C23	0.1773 (5)	0.2114 (3)	0.5445 (3)	0.0305 (12)
H23	0.0964	0.1774	0.5492	0.037*
C24	0.3173 (5)	0.2151 (3)	0.6117 (3)	0.0270 (11)
H24	0.3307	0.1814	0.6600	0.032*
C25	0.5538 (5)	0.3679 (3)	0.5454 (4)	0.0293 (11)
C26	0.0043 (5)	0.2595 (3)	0.3963 (3)	0.0288 (11)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn1	0.0198 (2)	0.0313 (3)	0.0236 (3)	0.0014 (3)	−0.00559 (18)	−0.0038 (3)
N1	0.0210 (18)	0.029 (2)	0.029 (2)	0.0026 (17)	−0.0005 (17)	0.0001 (18)
N2	0.029 (2)	0.031 (2)	0.030 (3)	0.0031 (18)	0.0056 (18)	−0.0089 (19)
N3	0.0181 (19)	0.028 (2)	0.022 (2)	0.0013 (16)	−0.0033 (16)	−0.0015 (18)
N4	0.0203 (18)	0.033 (2)	0.022 (2)	0.0010 (17)	0.0008 (16)	−0.0049 (18)
N5	0.0199 (19)	0.034 (2)	0.025 (2)	0.0023 (17)	−0.0042 (17)	−0.0022 (18)
N6	0.0207 (18)	0.023 (2)	0.020 (2)	−0.0034 (17)	−0.0028 (16)	−0.0018 (17)
O1	0.0256 (17)	0.040 (2)	0.031 (2)	−0.0081 (15)	−0.0067 (15)	0.0022 (17)
O2	0.053 (2)	0.054 (3)	0.043 (3)	−0.0185 (19)	−0.0088 (19)	0.028 (2)
O3	0.0321 (17)	0.041 (2)	0.0169 (19)	−0.0005 (15)	−0.0054 (14)	0.0032 (15)
O4	0.0195 (17)	0.083 (3)	0.040 (2)	−0.0045 (18)	−0.0069 (16)	0.007 (2)
C1	0.022 (2)	0.027 (3)	0.032 (3)	0.003 (2)	0.007 (2)	−0.001 (2)
C2	0.021 (2)	0.041 (3)	0.040 (4)	0.005 (2)	0.001 (2)	−0.006 (3)
C3	0.027 (3)	0.049 (4)	0.044 (4)	−0.003 (2)	0.000 (2)	−0.001 (3)
C4	0.024 (3)	0.052 (4)	0.072 (5)	0.015 (3)	0.005 (3)	0.002 (3)
C5	0.029 (3)	0.041 (3)	0.053 (4)	0.007 (2)	0.010 (3)	−0.007 (3)
C6	0.022 (2)	0.032 (3)	0.029 (3)	0.001 (2)	0.003 (2)	0.002 (2)
C7	0.027 (3)	0.026 (3)	0.026 (3)	0.005 (2)	0.002 (2)	−0.001 (2)
C8	0.028 (2)	0.022 (3)	0.023 (3)	0.000 (2)	0.002 (2)	0.000 (2)
C9	0.033 (3)	0.038 (3)	0.027 (3)	0.007 (2)	−0.002 (2)	−0.010 (2)
C10	0.034 (3)	0.038 (3)	0.035 (3)	−0.001 (2)	−0.010 (2)	−0.007 (3)
C11	0.021 (2)	0.031 (3)	0.034 (3)	0.002 (2)	−0.008 (2)	−0.007 (2)
C12	0.024 (2)	0.031 (3)	0.018 (3)	0.001 (2)	0.0034 (19)	0.004 (2)
C13	0.018 (2)	0.025 (3)	0.023 (3)	0.0004 (19)	0.0008 (19)	0.002 (2)
C14	0.024 (2)	0.029 (3)	0.031 (3)	0.000 (2)	0.009 (2)	0.003 (2)
C15	0.015 (3)	0.035 (3)	0.047 (4)	0.005 (2)	0.004 (2)	0.013 (3)
C16	0.038 (3)	0.029 (3)	0.050 (4)	−0.001 (2)	0.017 (3)	−0.001 (3)
C17	0.038 (3)	0.036 (3)	0.038 (4)	−0.007 (2)	0.011 (2)	−0.013 (3)
C18	0.033 (3)	0.038 (3)	0.031 (3)	−0.008 (2)	−0.001 (2)	−0.006 (2)
C19	0.022 (2)	0.028 (3)	0.024 (3)	−0.001 (2)	0.005 (2)	0.003 (2)
C20	0.020 (2)	0.029 (3)	0.017 (3)	0.0019 (19)	0.0007 (18)	−0.002 (2)
C21	0.028 (2)	0.031 (3)	0.022 (3)	0.004 (2)	−0.0026 (19)	0.002 (2)
C22	0.020 (2)	0.028 (3)	0.023 (3)	−0.001 (2)	−0.0007 (19)	−0.004 (2)
C23	0.021 (2)	0.039 (3)	0.029 (3)	−0.010 (2)	−0.002 (2)	0.000 (2)
C24	0.026 (2)	0.030 (3)	0.022 (3)	−0.003 (2)	−0.001 (2)	0.009 (2)
C25	0.025 (2)	0.030 (3)	0.031 (3)	−0.001 (2)	0.000 (2)	0.002 (2)
C26	0.020 (2)	0.033 (3)	0.029 (3)	0.003 (2)	−0.004 (2)	−0.004 (2)

Geometric parameters (Å, º)

Zn1—N6	2.095 (4)	C4—H4	0.9300
Zn1—O1	2.119 (3)	C5—C6	1.399 (6)
Zn1—N4	2.120 (3)	C5—H5	0.9300
Zn1—N3	2.142 (4)	C7—C8	1.470 (6)
Zn1—O3^i	2.186 (3)	C8—C9	1.401 (6)
Zn1—N1	2.203 (4)	C9—C10	1.382 (6)
N1—C7	1.325 (6)	C9—H9	0.9300
N1—C1	1.390 (5)	C10—C11	1.375 (6)
N2—C7	1.338 (6)	C10—H10	0.9300
N2—C6	1.378 (5)	C11—C12	1.388 (6)
N2—H2A	0.8600	C11—H11	0.9300
N3—C8	1.328 (5)	C12—C13	1.454 (6)
N3—C12	1.333 (5)	C14—C15	1.386 (6)
N4—C13	1.322 (5)	C14—C19	1.390 (6)
N4—C19	1.379 (5)	C15—C16	1.374 (6)
N5—C13	1.369 (5)	C15—H15	0.9300
N5—C14	1.388 (6)	C16—C17	1.392 (6)
N5—H5A	0.8600	C16—H16	0.9300
N6—C24	1.318 (5)	C17—C18	1.376 (6)
N6—C20	1.342 (5)	C17—H17	0.9300
O1—C25	1.247 (5)	C18—C19	1.390 (6)
O2—C25	1.239 (5)	C18—H18	0.9300
O3—C26	1.246 (6)	C20—C21	1.383 (6)
O3—Zn1^ii	2.186 (3)	C20—C25	1.528 (6)
O4—C26	1.248 (5)	C21—C22	1.384 (6)
C1—C6	1.388 (7)	C21—H21	0.9300
C1—C2	1.392 (6)	C22—C23	1.387 (6)
C2—C3	1.366 (6)	C22—C26	1.519 (6)
C2—H2	0.9300	C23—C24	1.382 (6)
C3—C4	1.393 (8)	C23—H23	0.9300
C3—H3	0.9300	C24—H24	0.9300
C4—C5	1.377 (7)
N6—Zn1—O1	78.24 (13)	N3—C8—C7	112.2 (4)
N6—Zn1—N4	113.77 (14)	C9—C8—C7	126.8 (4)
O1—Zn1—N4	95.30 (13)	C10—C9—C8	117.1 (4)
N6—Zn1—N3	166.96 (14)	C10—C9—H9	121.4
O1—Zn1—N3	92.23 (14)	C8—C9—H9	121.4
N4—Zn1—N3	75.63 (14)	C11—C10—C9	121.6 (4)
N6—Zn1—O3^i	92.04 (13)	C11—C10—H10	119.2
O1—Zn1—O3^i	169.83 (12)	C9—C10—H10	119.2
N4—Zn1—O3^i	91.32 (13)	C10—C11—C12	117.7 (4)
N3—Zn1—O3^i	96.89 (13)	C10—C11—H11	121.2
N6—Zn1—N1	96.48 (13)	C12—C11—H11	121.2
O1—Zn1—N1	89.09 (13)	N3—C12—C11	121.1 (4)
N4—Zn1—N1	149.71 (14)	N3—C12—C13	110.9 (4)
N3—Zn1—N1	74.26 (13)	C11—C12—C13	128.0 (4)
O3^i—Zn1—N1	89.08 (13)	N4—C13—N5	111.7 (4)
C7—N1—C1	104.8 (4)	N4—C13—C12	121.0 (4)
C7—N1—Zn1	114.1 (3)	N5—C13—C12	127.2 (4)
C1—N1—Zn1	140.9 (3)	C15—C14—N5	131.8 (4)
C7—N2—C6	106.7 (4)	C15—C14—C19	122.3 (4)
C7—N2—H2A	126.7	N5—C14—C19	105.9 (4)
C6—N2—H2A	126.7	C16—C15—C14	117.0 (4)
C8—N3—C12	121.4 (4)	C16—C15—H15	121.5
C8—N3—Zn1	120.1 (3)	C14—C15—H15	121.5
C12—N3—Zn1	118.5 (3)	C15—C16—C17	121.1 (4)
C13—N4—C19	106.4 (4)	C15—C16—H16	119.5
C13—N4—Zn1	114.0 (3)	C17—C16—H16	119.5
C19—N4—Zn1	139.4 (3)	C18—C17—C16	122.0 (5)
C13—N5—C14	106.7 (3)	C18—C17—H17	119.0
C13—N5—H5A	126.6	C16—C17—H17	119.0
C14—N5—H5A	126.6	C17—C18—C19	117.4 (4)
C24—N6—C20	118.8 (4)	C17—C18—H18	121.3
C24—N6—Zn1	126.0 (3)	C19—C18—H18	121.3
C20—N6—Zn1	112.9 (3)	N4—C19—C18	130.4 (4)
C25—O1—Zn1	115.6 (3)	N4—C19—C14	109.3 (4)
C26—O3—Zn1^ii	120.4 (3)	C18—C19—C14	120.2 (4)
C6—C1—N1	108.9 (4)	N6—C20—C21	121.2 (4)
C6—C1—C2	120.9 (4)	N6—C20—C25	115.2 (4)
N1—C1—C2	130.2 (4)	C21—C20—C25	123.4 (4)
C3—C2—C1	118.0 (5)	C20—C21—C22	120.3 (4)
C3—C2—H2	121.0	C20—C21—H21	119.9
C1—C2—H2	121.0	C22—C21—H21	119.9
C2—C3—C4	120.7 (5)	C21—C22—C23	117.3 (4)
C2—C3—H3	119.6	C21—C22—C26	121.6 (4)
C4—C3—H3	119.6	C23—C22—C26	121.0 (4)
C5—C4—C3	122.7 (5)	C24—C23—C22	119.1 (4)
C5—C4—H4	118.6	C24—C23—H23	120.5
C3—C4—H4	118.6	C22—C23—H23	120.5
C4—C5—C6	116.0 (5)	N6—C24—C23	123.2 (4)
C4—C5—H5	122.0	N6—C24—H24	118.4
C6—C5—H5	122.0	C23—C24—H24	118.4
N2—C6—C1	106.3 (4)	O2—C25—O1	126.4 (4)
N2—C6—C5	132.1 (5)	O2—C25—C20	117.2 (4)
C1—C6—C5	121.6 (5)	O1—C25—C20	116.4 (4)
N1—C7—N2	113.3 (4)	O3—C26—O4	127.0 (4)
N1—C7—C8	119.4 (4)	O3—C26—C22	117.7 (4)
N2—C7—C8	127.3 (4)	O4—C26—C22	115.3 (4)
N3—C8—C9	121.0 (4)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N5—H5A···O4^iii	0.86	1.83	2.689 (5)	173
N2—H2A···O2^iv	0.86	1.81	2.668 (5)	173

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

(II) catena-Poly[[[2,6-bis(1H-benzimidazol-2-yl-κN³)pyridine]zinc(II)]-µ-pyridine-2,5-dicarboxylato-κ²O²:O⁵]

Crystal data

[Zn(C7H3NO4)(C19H13N5)]	F(000) = 1104
Mr = 541.82	Dx = 1.593 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1213 reflections
a = 11.066 (3) Å	θ = 2.8–28.4°
b = 9.708 (2) Å	µ = 1.14 mm^−1
c = 21.717 (6) Å	T = 293 K
β = 104.42 (3)°	Block, colourless
V = 2259.5 (11) Å^3	0.22 × 0.18 × 0.16 mm
Z = 4

Data collection

Bruker APEX area-dectector diffractometer	3979 independent reflections
Radiation source: fine-focus sealed tube	2454 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.094
ϕ and ω scans	θmax = 25.0°, θmin = 2.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −13→12
Tmin = 0.959, Tmax = 1.000	k = −11→11
13029 measured reflections	l = −25→18

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)] = 0.060	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.121	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0352P)^2] where P = (Fo^2 + 2Fc^2)/3
3979 reflections	(Δ/σ)max < 0.001
334 parameters	Δρmax = 0.55 e Å^−3
0 restraints	Δρmin = −0.41 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
Zn1	0.29752 (5)	0.36481 (6)	0.09893 (3)	0.0367 (2)
N1	0.1661 (4)	0.5253 (4)	0.10675 (19)	0.0362 (10)
N2	0.0326 (3)	0.6874 (4)	0.0577 (2)	0.0395 (11)
H2A	−0.0071	0.7417	0.0283	0.047*
N3	0.2613 (3)	0.4742 (4)	0.00976 (19)	0.0340 (10)
N4	0.4268 (3)	0.2768 (4)	0.04703 (19)	0.0372 (10)
N5	0.4988 (4)	0.2791 (4)	−0.0402 (2)	0.0408 (11)
H5A	0.5063	0.3014	−0.0774	0.049*
N6	0.3019 (4)	0.2062 (4)	0.1672 (2)	0.0424 (11)
O1	0.1419 (3)	0.2274 (4)	0.05410 (17)	0.0469 (9)
O2	0.0347 (4)	0.0458 (4)	0.0752 (2)	0.0866 (15)
O3	0.5511 (3)	−0.0518 (4)	0.33622 (17)	0.0538 (10)
O4	0.5515 (4)	0.1742 (4)	0.34483 (18)	0.0608 (11)
C1	0.1008 (4)	0.5760 (5)	0.1489 (2)	0.0378 (13)
C2	0.1104 (5)	0.5416 (6)	0.2121 (3)	0.0569 (16)
H2	0.1680	0.4765	0.2328	0.068*
C3	0.0319 (6)	0.6069 (6)	0.2431 (3)	0.0726 (19)
H3	0.0358	0.5848	0.2852	0.087*
C4	−0.0532 (6)	0.7057 (6)	0.2121 (3)	0.073 (2)
H4	−0.1056	0.7470	0.2342	0.088*
C5	−0.0624 (5)	0.7440 (6)	0.1505 (3)	0.0615 (17)
H5	−0.1184	0.8113	0.1306	0.074*
C6	0.0173 (5)	0.6766 (5)	0.1189 (3)	0.0412 (13)
C7	0.1223 (4)	0.5957 (5)	0.0533 (2)	0.0343 (12)
C8	0.1732 (4)	0.5710 (5)	−0.0025 (2)	0.0345 (12)
C9	0.1413 (5)	0.6396 (5)	−0.0601 (3)	0.0456 (14)
H9	0.0806	0.7081	−0.0678	0.055*
C10	0.2028 (5)	0.6027 (5)	−0.1060 (3)	0.0537 (15)
H10	0.1830	0.6460	−0.1454	0.064*
C11	0.2938 (5)	0.5013 (5)	−0.0931 (3)	0.0485 (14)
H11	0.3355	0.4764	−0.1237	0.058*
C12	0.3219 (4)	0.4377 (5)	−0.0343 (2)	0.0374 (13)
C13	0.4145 (4)	0.3308 (5)	−0.0102 (2)	0.0372 (13)
C14	0.5701 (5)	0.1834 (5)	0.0006 (3)	0.0421 (14)
C15	0.6698 (5)	0.1015 (5)	−0.0056 (3)	0.0519 (15)
H15	0.6992	0.1023	−0.0421	0.062*
C16	0.7222 (5)	0.0191 (6)	0.0459 (3)	0.0617 (17)
H16	0.7888	−0.0378	0.0440	0.074*
C17	0.6785 (5)	0.0187 (6)	0.1002 (3)	0.0638 (18)
H17	0.7176	−0.0375	0.1340	0.077*
C18	0.5787 (5)	0.0990 (6)	0.1062 (3)	0.0546 (16)
H18	0.5494	0.0967	0.1428	0.065*
C19	0.5245 (4)	0.1829 (5)	0.0552 (3)	0.0395 (13)
C20	0.2266 (5)	0.0999 (5)	0.1469 (3)	0.0422 (13)
C21	0.2401 (5)	−0.0256 (6)	0.1796 (3)	0.0501 (15)
H21	0.1859	−0.0982	0.1647	0.060*
C22	0.3348 (5)	−0.0406 (5)	0.2343 (3)	0.0507 (15)
H22	0.3472	−0.1246	0.2555	0.061*
C23	0.4117 (5)	0.0714 (5)	0.2573 (2)	0.0395 (13)
C24	0.3902 (5)	0.1929 (5)	0.2225 (2)	0.0435 (14)
H24	0.4392	0.2692	0.2380	0.052*
C25	0.1267 (5)	0.1253 (6)	0.0867 (3)	0.0479 (14)
C26	0.5188 (5)	0.0612 (6)	0.3191 (2)	0.0357 (12)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn1	0.0357 (4)	0.0404 (4)	0.0327 (3)	0.0056 (3)	0.0062 (3)	0.0021 (3)
N1	0.041 (3)	0.034 (2)	0.033 (3)	0.0093 (19)	0.009 (2)	0.0030 (19)
N2	0.042 (3)	0.039 (3)	0.039 (3)	0.010 (2)	0.013 (2)	0.009 (2)
N3	0.030 (2)	0.038 (2)	0.034 (3)	0.0013 (19)	0.007 (2)	0.0005 (19)
N4	0.032 (2)	0.044 (3)	0.036 (3)	0.010 (2)	0.008 (2)	−0.001 (2)
N5	0.044 (3)	0.049 (3)	0.034 (3)	0.005 (2)	0.016 (2)	0.001 (2)
N6	0.046 (3)	0.044 (3)	0.036 (3)	0.001 (2)	0.008 (2)	−0.002 (2)
O1	0.041 (2)	0.050 (2)	0.050 (3)	0.0037 (17)	0.0113 (19)	0.0013 (19)
O2	0.061 (3)	0.085 (3)	0.094 (4)	−0.027 (3)	−0.019 (3)	0.024 (3)
O3	0.050 (2)	0.055 (3)	0.050 (3)	0.001 (2)	0.000 (2)	0.008 (2)
O4	0.071 (3)	0.067 (3)	0.040 (2)	−0.003 (2)	0.005 (2)	−0.002 (2)
C1	0.042 (3)	0.039 (3)	0.033 (3)	0.005 (2)	0.012 (3)	0.000 (2)
C2	0.071 (4)	0.056 (4)	0.046 (4)	0.018 (3)	0.019 (3)	0.006 (3)
C3	0.109 (6)	0.071 (5)	0.048 (4)	0.020 (4)	0.038 (4)	0.012 (3)
C4	0.100 (5)	0.068 (4)	0.072 (5)	0.029 (4)	0.059 (5)	0.000 (4)
C5	0.067 (4)	0.059 (4)	0.067 (5)	0.024 (3)	0.033 (4)	0.008 (3)
C6	0.045 (3)	0.036 (3)	0.045 (4)	0.003 (2)	0.016 (3)	0.000 (2)
C7	0.030 (3)	0.035 (3)	0.038 (3)	0.002 (2)	0.009 (3)	0.003 (2)
C8	0.028 (3)	0.040 (3)	0.034 (3)	−0.001 (2)	0.006 (2)	0.001 (2)
C9	0.041 (3)	0.046 (3)	0.048 (4)	0.012 (3)	0.009 (3)	0.008 (3)
C10	0.058 (4)	0.064 (4)	0.041 (4)	0.012 (3)	0.015 (3)	0.016 (3)
C11	0.049 (4)	0.057 (4)	0.046 (4)	0.011 (3)	0.023 (3)	0.002 (3)
C12	0.035 (3)	0.041 (3)	0.036 (3)	−0.001 (2)	0.008 (3)	−0.004 (2)
C13	0.035 (3)	0.039 (3)	0.037 (3)	0.004 (2)	0.008 (3)	−0.002 (2)
C14	0.039 (3)	0.044 (3)	0.044 (4)	0.008 (3)	0.011 (3)	−0.007 (3)
C15	0.046 (4)	0.064 (4)	0.049 (4)	0.010 (3)	0.018 (3)	−0.011 (3)
C16	0.052 (4)	0.064 (4)	0.067 (5)	0.028 (3)	0.011 (4)	−0.009 (3)
C17	0.067 (4)	0.071 (4)	0.053 (4)	0.035 (3)	0.013 (4)	0.004 (3)
C18	0.048 (4)	0.073 (4)	0.042 (4)	0.020 (3)	0.010 (3)	−0.001 (3)
C19	0.031 (3)	0.042 (3)	0.042 (3)	0.006 (2)	0.002 (3)	−0.007 (2)
C20	0.037 (3)	0.054 (4)	0.036 (3)	−0.001 (3)	0.010 (3)	0.001 (3)
C21	0.048 (4)	0.048 (4)	0.050 (4)	−0.007 (3)	0.004 (3)	0.007 (3)
C22	0.048 (4)	0.050 (4)	0.051 (4)	−0.006 (3)	0.008 (3)	0.010 (3)
C23	0.041 (3)	0.044 (3)	0.036 (3)	0.000 (3)	0.016 (3)	0.004 (3)
C24	0.039 (3)	0.056 (4)	0.034 (3)	−0.002 (3)	0.007 (3)	0.003 (3)
C25	0.040 (3)	0.053 (4)	0.049 (4)	0.013 (3)	0.009 (3)	0.007 (3)
C26	0.051 (3)	0.035 (3)	0.028 (3)	−0.013 (3)	0.022 (3)	−0.003 (2)

Geometric parameters (Å, º)

Zn1—O3^i	2.066 (4)	C4—H4	0.9300
Zn1—N6	2.130 (4)	C5—C6	1.407 (7)
Zn1—N3	2.157 (4)	C5—H5	0.9300
Zn1—N1	2.167 (4)	C7—C8	1.477 (7)
Zn1—N4	2.202 (4)	C8—C9	1.384 (7)
Zn1—O1	2.204 (3)	C9—C10	1.386 (7)
N1—C7	1.330 (6)	C9—H9	0.9300
N1—C1	1.390 (6)	C10—C11	1.385 (6)
N2—C7	1.355 (5)	C10—H10	0.9300
N2—C6	1.385 (6)	C11—C12	1.383 (7)
N2—H2A	0.8600	C11—H11	0.9300
N3—C8	1.332 (5)	C12—C13	1.461 (6)
N3—C12	1.345 (6)	C14—C15	1.392 (6)
N4—C13	1.325 (6)	C14—C19	1.401 (7)
N4—C19	1.392 (5)	C15—C16	1.380 (7)
N5—C13	1.360 (6)	C15—H15	0.9300
N5—C14	1.386 (6)	C16—C17	1.382 (8)
N5—H5A	0.8600	C16—H16	0.9300
N6—C20	1.331 (6)	C17—C18	1.384 (7)
N6—C24	1.352 (6)	C17—H17	0.9300
O1—C25	1.254 (6)	C18—C19	1.386 (7)
O2—C25	1.251 (6)	C18—H18	0.9300
O3—C26	1.185 (5)	C20—C21	1.399 (7)
O3—Zn1^ii	2.066 (4)	C20—C25	1.508 (7)
O4—C26	1.243 (5)	C21—C22	1.382 (7)
C1—C6	1.390 (6)	C21—H21	0.9300
C1—C2	1.390 (7)	C22—C23	1.394 (7)
C2—C3	1.379 (7)	C22—H22	0.9300
C2—H2	0.9300	C23—C24	1.389 (7)
C3—C4	1.394 (8)	C23—C26	1.557 (7)
C3—H3	0.9300	C24—H24	0.9300
C4—C5	1.368 (8)
O3^i—Zn1—N6	86.23 (16)	N3—C8—C7	111.1 (4)
O3^i—Zn1—N3	110.92 (14)	C9—C8—C7	126.9 (5)
N6—Zn1—N3	161.46 (15)	C8—C9—C10	117.7 (5)
O3^i—Zn1—N1	96.37 (15)	C8—C9—H9	121.2
N6—Zn1—N1	111.39 (15)	C10—C9—H9	121.2
N3—Zn1—N1	74.81 (15)	C11—C10—C9	120.1 (5)
O3^i—Zn1—N4	88.93 (15)	C11—C10—H10	119.9
N6—Zn1—N4	99.84 (15)	C9—C10—H10	119.9
N3—Zn1—N4	74.37 (15)	C12—C11—C10	119.2 (5)
N1—Zn1—N4	148.57 (15)	C12—C11—H11	120.4
O3^i—Zn1—O1	161.75 (15)	C10—C11—H11	120.4
N6—Zn1—O1	75.53 (15)	N3—C12—C11	120.2 (5)
N3—Zn1—O1	87.21 (14)	N3—C12—C13	111.2 (5)
N1—Zn1—O1	90.23 (13)	C11—C12—C13	128.6 (5)
N4—Zn1—O1	94.29 (14)	N4—C13—N5	112.4 (4)
C7—N1—C1	104.9 (4)	N4—C13—C12	121.1 (4)
C7—N1—Zn1	114.0 (3)	N5—C13—C12	126.5 (5)
C1—N1—Zn1	140.8 (3)	N5—C14—C15	131.3 (5)
C7—N2—C6	106.6 (4)	N5—C14—C19	106.0 (4)
C7—N2—H2A	126.7	C15—C14—C19	122.7 (5)
C6—N2—H2A	126.7	C16—C15—C14	116.0 (5)
C8—N3—C12	120.9 (4)	C16—C15—H15	122.0
C8—N3—Zn1	119.3 (3)	C14—C15—H15	122.0
C12—N3—Zn1	119.7 (3)	C15—C16—C17	121.8 (5)
C13—N4—C19	105.9 (4)	C15—C16—H16	119.1
C13—N4—Zn1	113.5 (3)	C17—C16—H16	119.1
C19—N4—Zn1	140.5 (3)	C16—C17—C18	122.4 (6)
C13—N5—C14	106.9 (4)	C16—C17—H17	118.8
C13—N5—H5A	126.5	C18—C17—H17	118.8
C14—N5—H5A	126.5	C17—C18—C19	116.9 (5)
C20—N6—C24	118.4 (5)	C17—C18—H18	121.6
C20—N6—Zn1	115.2 (4)	C19—C18—H18	121.6
C24—N6—Zn1	125.0 (3)	C18—C19—N4	130.9 (5)
C25—O1—Zn1	115.4 (4)	C18—C19—C14	120.3 (5)
C26—O3—Zn1^ii	135.0 (4)	N4—C19—C14	108.8 (4)
N1—C1—C6	109.5 (4)	N6—C20—C21	121.9 (5)
N1—C1—C2	129.9 (5)	N6—C20—C25	115.1 (5)
C6—C1—C2	120.7 (5)	C21—C20—C25	123.0 (5)
C3—C2—C1	117.9 (5)	C22—C21—C20	119.4 (5)
C3—C2—H2	121.1	C22—C21—H21	120.3
C1—C2—H2	121.1	C20—C21—H21	120.3
C2—C3—C4	120.9 (6)	C21—C22—C23	119.4 (5)
C2—C3—H3	119.5	C21—C22—H22	120.3
C4—C3—H3	119.5	C23—C22—H22	120.3
C5—C4—C3	122.4 (5)	C24—C23—C22	117.4 (5)
C5—C4—H4	118.8	C24—C23—C26	120.9 (5)
C3—C4—H4	118.8	C22—C23—C26	121.6 (5)
C4—C5—C6	116.6 (5)	N6—C24—C23	123.5 (5)
C4—C5—H5	121.7	N6—C24—H24	118.3
C6—C5—H5	121.7	C23—C24—H24	118.3
N2—C6—C1	106.1 (4)	O2—C25—O1	126.3 (5)
N2—C6—C5	132.4 (5)	O2—C25—C20	117.1 (5)
C1—C6—C5	121.5 (5)	O1—C25—C20	116.5 (5)
N1—C7—N2	112.9 (4)	O3—C26—O4	130.2 (5)
N1—C7—C8	120.1 (4)	O3—C26—C23	115.8 (5)
N2—C7—C8	126.9 (4)	O4—C26—C23	113.9 (5)
N3—C8—C9	121.9 (5)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2A···O1^iii	0.86	2.05	2.824 (5)	150
N5—H5A···O4^iv	0.86	1.89	2.739 (6)	168

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