Synthesis, characterization, and crystal structure of hexa­kis­(1-methyl-1H-imidazole-κN³)zinc(II) dinitrate

This article is part of a collection of articles to commemorate the founding of the African Crystallographic Association and the 75th anniversary of the IUCr.

The synthesis of the title compound, [Zn(C₄H₆N₂)₆](NO₃)₂, is described. This complex consists of a central zinc metal ion surrounded by six 1-methyl­imidazole ligands, charge balanced by two nitrate anions. The complex crystallizes in the space group P. In the crystal, the nitrate ions are situated within the cavities created by the [Zn(N-Melm)₆]²⁺ cations, serving as counter-ions. The three oxygen atoms of the nitrate ion engage in weak C—H⋯O inter­actions. In addition to single-crystal X-ray diffraction analysis, the complex was characterized using elemental analysis, ¹H NMR, ¹³C NMR, and FTIR spectroscopy.

1. Chemical context

Extensive research has been conducted on zinc complexes containing imidazole and its derivatives due to their significance in chemistry and their diverse applications (Victor et al., 2014; Porchia et al., 2020). These complexes play crucial roles as anti­cancer agents (Porchia et al., 2020; Babijczuk et al., 2023), anti­bacterial agents (Guo et al., 2022), fluorescent sensors (Anjali et al., 2022), in anti-counterfeiting and latent fingerprint detection (Kempegowda et al., 2021), and in materials chemistry (Rashamuse et al., 2023; Bezvikonnyi et al., 2022; Yu et al., 2021). Notably, zinc is the second most prevalent trace metal in the human body and is essential in a variety of biological systems (Haase & Rink, 2014; Kolenko et al., 2013). Consequently, it is unsurprising that Zn^II ions demonstrate the ability to inhibit certain bacterial species (McDevitt et al., 2011; Velasco et al., 2018). The use of Zn^II as the metal center in coordination chemistry is motivated by its ability to form strong complexes with ligands and the low cost of Zn precursors (Häggman et al., 2020; Rashamuse et al., 2023). In recent years, great efforts have been made to develop new organic zinc complexes with various architectures and applications (Abendrot, et al., 2020; Brahma & Baruah, 2020; Chen et al., 2021; Kseniya et al., 2022; Loke et al., 2020).

On the other hand, N-substituted imidazoles, or 1-substituted imidazoles, have emerged as highly attractive compounds due to a broad spectrum of applications (Chen et al., 2020; Gu et al., 2014; Kanzaki et al., 2012; Kseniya et al., 2022; Liu et al., 2014; Bogdanov & Svinyarov, 2017; Park et al., 2020; Wang et al., 2013). This ligand set features a conjugated di­aza five-membered heterocyclic ring structure. One nitro­gen atom has an N-methyl substituent, and its lone pair is delocal­ized in the aromatic ring, while the other nitro­gen is sp² hybridized and capable of coordinating Lewis acids, including metal ions. Numerous studies have been published on transition metal ion complexes involving imidazole and its derivatives (Erer et al., 2011; He et al., 2021; Kühl et al., 2011; Jawad & Al-Adilee 2022; Konarev et al., 2018; Neumüller & Dehnicke, 2010; Reedijk et al., 2012; Zhang et al., 2020). The lack of N-methyl group tautomerization enhances the appeal of N-substituted imidazole for the synthesis of novel mol­ecules. The coordination of imidazole derivatives with metal centers has had a positive impact on the development of novel metal complexes with applications in the field of material science (Anjali et al., 2022; Bezvikonnyi et al., 2022; Kempegowda et al., 2021; Rashamuse et al., 2023; Yu et al., 2021). In addition, the use of imidazole derivatives alongside zinc metal ions is an inter­esting technique to expand the complex repertoire in coordination chemistry. Therefore, our goal was to utilize the N-methyl­imidazole core in conjunction with a zinc metal ion in the presence of ammonia to generate unique complexes with different topologies.

The utilization of 1-methyl­imidazole as a starting ligand for the synthesis of zinc complexes has been previously explored (Rashidi et al., 2021; Appleton & Sarkar, 1977; Chen et al., 1996; Steichen et al., 2014). In this article, we report the synthesis of a new compound hexa­kis­(1-methyl-1H-imidazole-κN³)zinc(II) dinitrate, [Zn(C₄H₆N₂)₆](NO₃)₂, which is synthesized in the manner depicted in the scheme. The structure of the complex was confirmed via proton NMR, FTIR, and single-crystal X-ray diffraction.

2. Structural commentary

The title compound (Fig. 1) crystallizes in the P space group with half of a formula unit in the asymmetric unit. There are two crystallographically distinct zinc atoms. One has 1/3 occupancy and is bound to two crystallographically unique 1-methyl­imidazole ligands and the other has 1/6 occupancy and is bound to one crystallographically unique 1-methyl­imidazole ligand. One full occupancy nitrate anion is also present in the asymmetric unit.

Figure 1 Displacement ellipsoid plot of [Zn(C4H6N2)6][NO3]2 showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) y − x, 1 − x, z; (ii) 1 − y, 1 + x − y, z; (iii) −y, x − y, z; (iv) y − x, −x, z; (v) −x, −y, −z; (vi) −y, x + x, −z; (vii) y, −x + y, −z.]

The full zinc complex ions {[Zn(N-Melm)₆]²⁺, where N-Melm denotes N-methyl­imidazole} exhibit coordination by six N-Melm ligands. The ions are in a distorted octa­hedral coord­ination environment, demonstrated by N—Zn—N angles close to 90° or 180° depending on their cis or trans relationship. The Zn—N lengths are 2.182 (2) Å for N1—Zn1, 2.177 (2) Å for N3—Zn1, and 2.179 (2) Å for N5—Zn2. The complex mol­ecule also displays fifteen unique C—N bond lengths ranging from 1.308 (3) to 1.471 (4) Å. The nitrate counter-ion demonstrates O—N—O bond angles of 125.4 (4) ° for O2—N7—O3, 118.0 (4)° for O2—N7—O1, and 116.5 (4) ° for O3—N7—O1 and N—O bond lengths of 1.202 (5) Å for N7—O2, 1.209 (4) Å for N7—O3 and 1.234 (5) Å for N7—O1.

3. Supra­molecular features

The packing of the title compound is shown in Fig. 2 while Fig. 3 shows the inter­molecular inter­actions in the [Zn(C₄H₆N₂)₆][NO₃]₂ complex. In the crystal, the nitrate ions are situated within the cavities created by the [Zn(N-Melm)₆]²⁺ cations, serving as counter-ions. The three oxygen atoms of the nitrate ion engage in weak C—H⋯O inter­actions (Table 1) with two hydrogen atoms from the imidazole rings and one hydrogen atom from the methyl groups.

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C12—H12B⋯O1^i	0.98	2.44	3.339 (7)	152
C12—H12C⋯O3^ii	0.98	2.36	3.333 (7)	169
C12—H12A⋯O2^iii	0.98	2.62	3.596 (8)	174
Symmetry codes: (i) ; (ii) ; (iii) .

Figure 2 Packing diagram of the [Zn(C4H6N2)6][NO3]2 complex showing the nitrate cation lying in the void between the cationic complexes.

Figure 3 Diagram showing inter­action between the nitrate ions and N-methyl­imidazole ligands of the title compound with blue dashed lines representing the C—H⋯O close contacts.

4. Database survey

A search of the Cambridge Structural Database (CSD, Version 5.45, update of March 2024; Groom et al., 2016) for [Zn(C₄H₆N₂)₆] compounds with nitrate cations resulted in no hits. However, when the search was expanded to include other cationic salts, six relevant ones were found, including a discrete Zn complex with a sixfold coordination. These entries include [Zn(C₄H₆N₂)₆](I)₂ (CCDC reference: 2347502; Rashidi et al., 2021), [Zn(MeIm)₆](Tf₂N)₂, [Zn(EtIm)₆](Tf₂N)₂, [Zn(MeIm)(EtIm)₅](Tf₂N)₂, [Zn(MeIm)₂(EtIm)₄](Tf₂N)₂, and [Zn(MeIm)_4.5(EtIm)_1.5](Tf₂N)₂ (CCDC references: 978387, 978388, 978389, 978390, and 978391; Steichen et al., 2014) where Melm is 1-methyl-1H-imidazole), EtIm is 1-ethyl-1H-imidazole, and (Tf₂N)₂ is bis­(tri­fluoro­methyl­sulfon­yl)imide. The cationic zinc complex paired with iodine anions, [Zn(C₄H₆N₂)₆](I)₂, is particularly inter­esting as it exhibits a very similar structure, similar packing, similar cell parameters, and the same space group as the title compound. Although the zinc ions in the other five complexes had a similar sixfold coordination, the anion involved in these complexes was bis­(tri­fluoro­methyl­sulfon­yl)imide, and their crystals exhibited different structures and space groups.

5. Synthesis and crystallization

In a typical synthesis, 0.9 g of zinc nitrate hexa­hydrate, Zn(NO₃)₂·6H₂O (3.0 mmol), was dissolved in 10 mL of ethanol. A second solution consisting of 0.52 g of N-methyl-1H-imidazole (6.0 mmol) in 30 mL of ethanol and 2.8 ml of ammonia solution (2.48 mmol) was prepared in parallel. The Zn^II solution was poured rapidly into the second solution. The resultant mixture was stirred at room temperature for 10 minutes to complete crystallization. The crystals were collected by centrifugation, filtered, washed three times with ethanol, and dried overnight at room temperature to afford [Zn(C₄H₆N₂)₆][NO₃]₂ as light-blue crystals in 67% yield. Analysis calculated for C₂₄H₃₆N₁₄O₆Zn: C, 42.27%; H 5.32%; N, 28.75%; Found: C, 42.71%; H5.39%; N, 28.56%; ¹H NMR δ/ppm (400 MHz, CDCl₃): 3.77 (s, 3H), 7.06 (s, 2H), 8.13 (s, 1H); ¹³C NMR δ/ppm (101 MHz, CDCl₃): 32.23, 127.99, 140.04; FTIR ν_max/cm⁻¹: 3121, 1643, 1528, 1516, 1327, 1288, 1231, 1088, 1026, 934, 826,768, 660, 621.

The overlaid ¹H NMR spectra of the ligand and zinc complex are shown in Fig. 4. In the proton NMR spectrum of the free N-methyl-1H-imidazole ligand, there are four sharp signals with the methyl group appearing at 3.47 ppm and the three protons of the imidazole motif appearing at 6.69. 6.84 and 7.21 ppm. However, upon complexation with the zinc ion, the methyl proton shifted to 3.77 ppm, while the imidazole signals are broadened with two protons merged at 7.06 ppm, and the third proton exhibiting a downfield shift to 8.13 ppm. Similar behavior can also be observed in the ¹³C NMR spectra, demonstrating complexation.

Figure 4 The superimposed ^1H NMR spectra of (a) the free N-methyl­imidazole ligand (red) and (b) its corresponding [Zn(C4H6N2)6][NO3]2 complex (blue) in deuterated chloro­form.

The comparative FTIR spectra of the free ligand and the zinc complex are presented in Fig. 5. In the spectrum of the zinc complex, a vibrational peak at 3476 cm⁻¹ is observed, which is attributed to the O—H stretching of water mol­ecules as the complex is hygroscopic. The characteristic vibrational peak associated with C=C stretching appears at 1678 cm⁻¹ in the free ligand, but in the complex spectrum, it is shifted to the vibrational frequency of 1630 cm⁻¹. Furthermore, an intense band at around 1516 cm⁻¹ is evident, which originates from the C=N stretching mode of the imidazole moiety of the free ligand. However, upon zinc coordination, two different vibrational frequencies are observed at 1545 and 1527 cm⁻¹, corresponding to the C=N stretching mode. Notably, both asymmetric and symmetric NO₃ stretching vibrations at 1330 and 958 cm⁻¹ are clearly visible as intense vibrational peaks in the zinc complex spectrum, with both features absent in the free ligand spectrum. Furthermore, a stretching band of Zn—N is observed at a vibrational frequency of 467 cm⁻¹, providing further evidence of the coordination of zinc ions with the nitro­gen atom of the N-methyl­imidazole group.

Figure 5 The superimposed FTIR spectra of the free ligand N-methyl­imidazole (orange) and its [Zn(C4H6N2)6][NO3]2 complex (blue) in the frequency range 3600–400 cm^−1.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. All C bound hydrogen atoms were placed at idealized positions and refined as riding atoms with isotropic parameters 1.2 or 1.5 times those of their parent atoms. The crystal studied was refined as a two-component twin. H atoms were positioned in idealized locations and refined using a riding model, with isotropic displacement parameters set to 1.2 or 1.5 times those of their respective parent atoms. A twin law was also applied.

Table 2
Experimental details

Crystal data
Chemical formula	[Zn(C4H6N2)6](NO3)2
Mr	682.04
Crystal system, space group	Trigonal, P
Temperature (K)	173
a, c (Å)	19.1227 (10), 7.4770 (5)
V (Å^3)	2367.9 (3)
Z	3
Radiation type	Mo Kα
μ (mm^−1)	0.84
Crystal size (mm)	0.45 × 0.34 × 0.23
Data collection
Diffractometer	Bruker D8 Venture Photon CCD area detector
Absorption correction	Multi-scan (SADABS; Krause et al., 2015)
Tmin, Tmax	0.660, 0.745
No. of measured, independent and observed [I > 2σ(I)] reflections	119969, 3247, 3073
Rint	0.040
(sin θ/λ)max (Å^−1)	0.626
Refinement
R[F^2 > 2σ(F^2)], wR(F^2), S	0.032, 0.090, 1.12
No. of reflections	3247
No. of parameters	208
H-atom treatment	H-atom parameters constrained
Δρmax, Δρmin (e Å^−3)	0.51, −0.36
Computer programs: APEX3, SAINT-Plus and XPREP (Bruker 2016), SHELXT2014 (Sheldrick, 2015a), SHELXL2018/3 (Sheldrick, 2015b), ORTEP-3 for Windows and WinGX publication routines (Farrugia, 2012) and PLATON (Spek, 2020).

Supporting information

Computing details

Hexakis(1-methyl-1H-imidazole-κN³)zinc(II) dinitrate

Crystal data

[Zn(C4H6N2)6](NO3)2	Dx = 1.435 Mg m^−3
Mr = 682.04	Mo Kα radiation, λ = 0.71073 Å
Trigonal, P3	Cell parameters from 9720 reflections
a = 19.1227 (10) Å	θ = 3.3–26.2°
c = 7.4770 (5) Å	µ = 0.84 mm^−1
V = 2367.9 (3) Å^3	T = 173 K
Z = 3	Block, colourless
F(000) = 1068	0.45 × 0.34 × 0.23 mm

Data collection

Bruker D8 Venture Photon CCD area detector diffractometer	3073 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.040
ω scans	θmax = 26.4°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	h = −23→23
Tmin = 0.660, Tmax = 0.745	k = −23→23
119969 measured reflections	l = −9→9
3247 independent reflections

Refinement

Refinement on F^2	Primary atom site location: dual - dual-space method e.g. SHELXD
Least-squares matrix: full	Secondary atom site location: dual - dual-space method e.g. SHELXD
R[F^2 > 2σ(F^2)] = 0.032	Hydrogen site location: mixed
wR(F^2) = 0.090	H-atom parameters constrained
S = 1.12	w = 1/[σ^2(Fo^2) + (0.0449P)^2 + 1.2961P] where P = (Fo^2 + 2Fc^2)/3
3247 reflections	(Δ/σ)max < 0.001
208 parameters	Δρmax = 0.51 e Å^−3
0 restraints	Δρmin = −0.36 e Å^−3
0 constraints

Special details

Experimental. Absorption corrections were made using the program SADABS (Sheldrick, 1996) Intensity data were determined on a Bruker Venture D8 Photon CMOS diffractometer with graphite-monochromated Mo Ka₁ (λ = 0.71073 Å) radiation at 173 K using an Oxford Cryostream 600 cooler. Data reduction was carried out using the program SAINT+, version 6.02 (Bruker, 2016) and empirical absorption corrections were made using SADABS (Bruker 2016) Space group assignments was made using XPREP (Bruker, 2016). The structure was solved in the WinGX (Farrugia, 2012) Suite of programs, using intrinsic phasing through SHELXT (Sheldrick, 2015a) and refined using full-matrix least-squares/difference Fourier techniques on F² using SHELXL2017 (Sheldrick, 2015b). Diagrams and publication material were generated using ORTEP-3 (Farrugia, 2012) and PLATON (Spek, 2020).

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.

Refinement. Refined as a 2-component twin.

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

	x	y	z	Uiso*/Ueq
C1	0.35319 (17)	0.56158 (16)	0.8432 (4)	0.0370 (5)
H1	0.397348	0.608195	0.894545	0.044*
C2	0.32525 (18)	0.48483 (17)	0.8998 (4)	0.0408 (6)
H2	0.345852	0.467857	0.995698	0.049*
C3	0.25403 (19)	0.48549 (16)	0.6749 (4)	0.0434 (6)
H3	0.214048	0.466944	0.583882	0.052*
C4	0.2155 (3)	0.3487 (2)	0.7945 (6)	0.0742 (12)
H4A	0.221478	0.328911	0.911228	0.111*
H4B	0.235574	0.327455	0.700603	0.111*
H4C	0.158422	0.330563	0.773011	0.111*
C5	0.31191 (18)	0.77017 (19)	0.2309 (4)	0.0408 (6)
H5	0.26636	0.723578	0.183396	0.049*
C6	0.34153 (19)	0.84611 (19)	0.1679 (4)	0.0451 (7)
H6	0.321104	0.862707	0.071015	0.054*
C7	0.41433 (19)	0.84552 (17)	0.3924 (4)	0.0479 (7)
H7	0.455942	0.864052	0.479686	0.057*
C8	0.4553 (3)	0.9812 (2)	0.2607 (6)	0.0860 (15)
H8A	0.510363	0.998228	0.300205	0.129*
H8B	0.431985	1.005728	0.337839	0.129*
H8C	0.456463	0.998554	0.136826	0.129*
N1	0.30848 (13)	0.56202 (13)	0.7012 (3)	0.0321 (4)
N2	0.26215 (16)	0.43720 (15)	0.7926 (3)	0.0437 (6)
N3	0.35725 (12)	0.77013 (12)	0.3735 (3)	0.0330 (4)
N4	0.40615 (19)	0.89350 (16)	0.2712 (4)	0.0510 (7)
Zn1	0.333333	0.666667	0.53840 (6)	0.02973 (13)
C9	0.11565 (17)	0.12401 (17)	0.2960 (4)	0.0397 (6)
H9	0.129642	0.086107	0.340727	0.048*
C10	0.14947 (19)	0.20166 (17)	0.3498 (4)	0.0472 (7)
H10	0.192987	0.227884	0.431476	0.057*
C11	0.06016 (17)	0.17677 (16)	0.1425 (4)	0.0394 (6)
H11	0.027212	0.18447	0.058845	0.047*
C12	0.1277 (3)	0.31748 (19)	0.2617 (6)	0.0669 (10)
H12A	0.101449	0.327601	0.160283	0.1*
H12B	0.185931	0.3554	0.257408	0.1*
H12C	0.105592	0.324868	0.373768	0.1*
N5	0.05952 (13)	0.10858 (12)	0.1642 (3)	0.0353 (5)
N6	0.11268 (16)	0.23427 (14)	0.2519 (4)	0.0453 (6)
Zn2	0	0	0	0.03046 (17)
N7	0.65532 (18)	0.6614 (2)	0.7378 (5)	0.0581 (7)
O1	0.6741 (2)	0.6106 (2)	0.6944 (6)	0.1096 (13)
O2	0.6618 (3)	0.6807 (3)	0.8925 (5)	0.1172 (14)
O3	0.6354 (3)	0.6903 (2)	0.6181 (6)	0.1214 (15)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0432 (14)	0.0399 (13)	0.0321 (13)	0.0239 (11)	0.0013 (11)	0.0015 (11)
C2	0.0552 (16)	0.0522 (15)	0.0319 (12)	0.0395 (14)	0.0082 (12)	0.0065 (11)
C3	0.0529 (16)	0.0332 (13)	0.0378 (14)	0.0167 (12)	−0.0037 (12)	0.0044 (11)
C4	0.099 (3)	0.0314 (16)	0.080 (3)	0.0237 (18)	−0.013 (2)	0.0114 (16)
C5	0.0464 (15)	0.0511 (16)	0.0335 (13)	0.0309 (14)	−0.0040 (12)	0.0000 (13)
C6	0.0587 (17)	0.0621 (18)	0.0342 (13)	0.0449 (15)	0.0066 (13)	0.0111 (12)
C7	0.0596 (18)	0.0318 (13)	0.0474 (16)	0.0192 (13)	−0.0115 (13)	0.0062 (11)
C8	0.126 (4)	0.043 (2)	0.082 (3)	0.037 (2)	0.003 (3)	0.0250 (19)
N1	0.0334 (10)	0.0332 (11)	0.0304 (10)	0.0171 (9)	0.0050 (8)	0.0026 (8)
N2	0.0554 (15)	0.0339 (12)	0.0426 (13)	0.0230 (11)	0.0064 (11)	0.0087 (10)
N3	0.0356 (10)	0.0352 (11)	0.0307 (10)	0.0197 (9)	0.0013 (8)	0.0031 (8)
N4	0.0727 (19)	0.0420 (14)	0.0467 (14)	0.0351 (14)	0.0049 (13)	0.0130 (11)
Zn1	0.02969 (16)	0.02969 (16)	0.0298 (2)	0.01484 (8)	0	0
C9	0.0411 (14)	0.0366 (13)	0.0371 (15)	0.0160 (12)	−0.0034 (11)	−0.0042 (11)
C10	0.0530 (16)	0.0423 (15)	0.0385 (14)	0.0179 (13)	−0.0033 (13)	−0.0024 (12)
C11	0.0407 (13)	0.0328 (12)	0.0433 (14)	0.0173 (11)	0.0000 (12)	−0.0068 (11)
C12	0.083 (3)	0.0314 (16)	0.081 (3)	0.0242 (17)	−0.006 (2)	−0.0153 (16)
N5	0.0340 (11)	0.0311 (10)	0.0395 (12)	0.0153 (9)	0.0015 (9)	−0.0015 (9)
N6	0.0497 (14)	0.0293 (12)	0.0493 (14)	0.0141 (11)	0.0028 (11)	−0.0058 (10)
Zn2	0.0271 (2)	0.0271 (2)	0.0372 (4)	0.01354 (10)	0	0
N7	0.0479 (16)	0.0584 (17)	0.0692 (19)	0.0275 (14)	0.0088 (14)	0.0225 (14)
O1	0.108 (3)	0.088 (2)	0.147 (4)	0.059 (2)	−0.004 (3)	−0.018 (2)
O2	0.156 (4)	0.150 (4)	0.0653 (18)	0.091 (3)	0.029 (2)	0.016 (2)
O3	0.131 (3)	0.113 (3)	0.133 (3)	0.071 (3)	−0.051 (3)	0.016 (3)

Geometric parameters (Å, º)

C1—C2	1.355 (4)	C8—H8A	0.98
C1—N1	1.365 (3)	C8—H8B	0.98
C1—H1	0.95	C8—H8C	0.98
C2—N2	1.352 (4)	N1—Zn1	2.182 (2)
C2—H2	0.95	N3—Zn1	2.177 (2)
C3—N1	1.319 (3)	C9—C10	1.351 (4)
C3—N2	1.339 (4)	C9—N5	1.376 (4)
C3—H3	0.95	C9—H9	0.95
C4—N2	1.467 (4)	C10—N6	1.363 (4)
C4—H4A	0.98	C10—H10	0.9486
C4—H4B	0.98	C11—N5	1.308 (3)
C4—H4C	0.98	C11—N6	1.335 (4)
C5—C6	1.352 (4)	C11—H11	0.95
C5—N3	1.375 (3)	C12—N6	1.471 (4)
C5—H5	0.95	C12—H12A	0.98
C6—N4	1.351 (4)	C12—H12B	0.98
C6—H6	0.95	C12—H12C	0.98
C7—N3	1.310 (3)	N5—Zn2	2.179 (2)
C7—N4	1.353 (4)	N7—O2	1.202 (5)
C7—H7	0.95	N7—O3	1.209 (4)
C8—N4	1.458 (4)	N7—O1	1.234 (5)
C2—C1—N1	109.9 (2)	N3—Zn1—N1^i	88.74 (8)
C2—C1—H1	125	N3^i—Zn1—N1^i	179.34 (8)
N1—C1—H1	125	N3^ii—Zn1—N1^i	88.28 (8)
N2—C2—C1	106.3 (2)	N1^ii—Zn1—N1^i	91.89 (8)
N2—C2—H2	126.9	N3—Zn1—N1	179.34 (9)
C1—C2—H2	126.9	N3^i—Zn1—N1	88.28 (8)
N1—C3—N2	111.6 (3)	N3^ii—Zn1—N1	88.73 (8)
N1—C3—H3	124.2	N1^ii—Zn1—N1	91.89 (8)
N2—C3—H3	124.2	N1^i—Zn1—N1	91.89 (8)
N2—C4—H4A	109.5	C10—C9—N5	110.0 (3)
N2—C4—H4B	109.5	C10—C9—H9	124.8
H4A—C4—H4B	109.5	N5—C9—H9	125.1
N2—C4—H4C	109.5	C9—C10—N6	105.7 (3)
H4A—C4—H4C	109.5	C9—C10—H10	125.7
H4B—C4—H4C	109.5	N6—C10—H10	128.4
C6—C5—N3	110.2 (3)	N5—C11—N6	111.9 (3)
C6—C5—H5	124.9	N5—C11—H11	124
N3—C5—H5	124.9	N6—C11—H11	124
N4—C6—C5	105.8 (2)	N6—C12—H12A	109.5
N4—C6—H6	127.1	N6—C12—H12B	109.5
C5—C6—H6	127.1	H12A—C12—H12B	109.5
N3—C7—N4	111.0 (3)	N6—C12—H12C	109.5
N3—C7—H7	124.5	H12A—C12—H12C	109.5
N4—C7—H7	124.5	H12B—C12—H12C	109.5
N4—C8—H8A	109.5	C11—N5—C9	104.9 (2)
N4—C8—H8B	109.5	C11—N5—Zn2	128.3 (2)
H8A—C8—H8B	109.5	C9—N5—Zn2	125.97 (18)
N4—C8—H8C	109.5	C11—N6—C10	107.5 (2)
H8A—C8—H8C	109.5	C11—N6—C12	125.5 (3)
H8B—C8—H8C	109.5	C10—N6—C12	127.1 (3)
C3—N1—C1	105.0 (2)	N5^iii—Zn2—N5^iv	180.00 (9)
C3—N1—Zn1	128.56 (18)	N5^iii—Zn2—N5	88.61 (8)
C1—N1—Zn1	126.11 (18)	N5^iv—Zn2—N5	91.39 (8)
C3—N2—C2	107.3 (2)	N5^iii—Zn2—N5^v	91.39 (8)
C3—N2—C4	126.1 (3)	N5^iv—Zn2—N5^v	88.61 (8)
C2—N2—C4	126.5 (3)	N5—Zn2—N5^v	180
C7—N3—C5	105.2 (2)	N5^iii—Zn2—N5^vi	88.61 (8)
C7—N3—Zn1	128.32 (18)	N5^iv—Zn2—N5^vi	91.39 (8)
C5—N3—Zn1	126.43 (19)	N5—Zn2—N5^vi	91.39 (8)
C6—N4—C7	107.8 (3)	N5^v—Zn2—N5^vi	88.61 (8)
C6—N4—C8	126.0 (3)	N5^iii—Zn2—N5^vii	91.39 (8)
C7—N4—C8	126.1 (3)	N5^iv—Zn2—N5^vii	88.61 (8)
N3—Zn1—N3^i	91.09 (8)	N5—Zn2—N5^vii	88.61 (8)
N3—Zn1—N3^ii	91.09 (8)	N5^v—Zn2—N5^vii	91.39 (8)
N3^i—Zn1—N3^ii	91.09 (8)	N5^vi—Zn2—N5^vii	180.00 (8)
N3—Zn1—N1^ii	88.28 (8)	O2—N7—O3	125.4 (4)
N3^i—Zn1—N1^ii	88.73 (8)	O2—N7—O1	118.0 (4)
N3^ii—Zn1—N1^ii	179.34 (8)	O3—N7—O1	116.5 (4)
N1—C1—C2—N2	−0.4 (3)	C5—C6—N4—C7	0.3 (3)
N3—C5—C6—N4	0.5 (3)	C5—C6—N4—C8	−176.3 (4)
N2—C3—N1—C1	0.1 (3)	N3—C7—N4—C6	−1.1 (4)
N2—C3—N1—Zn1	173.38 (18)	N3—C7—N4—C8	175.5 (4)
C2—C1—N1—C3	0.2 (3)	N5—C9—C10—N6	1.0 (3)
C2—C1—N1—Zn1	−173.31 (17)	N6—C11—N5—C9	−0.2 (3)
N1—C3—N2—C2	−0.3 (3)	N6—C11—N5—Zn2	−170.42 (18)
N1—C3—N2—C4	−175.6 (3)	C10—C9—N5—C11	−0.6 (3)
C1—C2—N2—C3	0.4 (3)	C10—C9—N5—Zn2	170.0 (2)
C1—C2—N2—C4	175.7 (3)	N5—C11—N6—C10	0.8 (3)
N4—C7—N3—C5	1.4 (4)	N5—C11—N6—C12	−179.7 (3)
N4—C7—N3—Zn1	−175.52 (19)	C9—C10—N6—C11	−1.1 (3)
C6—C5—N3—C7	−1.2 (3)	C9—C10—N6—C12	179.4 (3)
C6—C5—N3—Zn1	175.81 (18)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C12—H12B···O1^viii	0.98	2.44	3.339 (7)	152
C12—H12C···O3^ii	0.98	2.36	3.333 (7)	169
C12—H12A···O2^ix	0.98	2.62	3.596 (8)	174

Symmetry codes: (ii) −x+y, −x+1, z; (viii) −x+1, −y+1, −z+1; (ix) −x+y, −x+1, z−1.