Synthesis and crystal structure of a two-dimensional sodium coordination polymer of 4,4'-(diazene­diyl)bis­(1H-1,2,4-triazol-5-one)

The crystal engineering of coordination polymers has aroused inter­est due to their structural versatility, unique properties and applications in different areas of science. The selection of appropriate ligands as building blocks is critical in order to afford a range of topologies. Alkali metal cations are known for their mainly ionic chemistry in aqueous media. Their coordination number varies depending on the size of the binding partners, and on the electrostatic inter­action between the ligands and the metal ions. The two-dimensional coordination polymer poly[tetra-[mu]-aqua-[[mu]₄-4,4'-(diazenediyl)bis­(5-oxo-1H-1,2,4-triazolido)]disodium(I)], [Na₂(C₄H₂N₈O₂)(H₂O)₄]_n, (I), was synthesized from 4-amino-1H-1,2,4-triazol-5(4H)-one (ATO) and its single-crystal structure determined. The mid-point of the imino N=N bond of the 4,4'-(diazenediyl)bis­(5-oxo-1H-1,2,4-triazolide) (ZTO^2-) ligand is located on an inversion centre. The asymmetric unit consists of one Na⁺ cation, half a bridging ZTO^2- ligand and two bridging water ligands. Each Na⁺ cation is coordinated in a trigonal anti­prismatic fashion by six O atoms, i.e. two from two ZTO^2- ligands and the remaining four from bridging water ligands. The Na⁺ cation is located near a glide plane, thus the two bridging O atoms from the two coordinating ZTO^2- ligands are on adjacent apices of the trigonal anti­prism, rather than being in an anti configuration. All water and ZTO^2- ligands act as bridging ligands between metal centres. Each Na⁺ metal centre is bridged to a neigbouring Na⁺ cation by two water molecules to give a one-dimensional [Na(H₂O)₂]_n chain. The organic ZTO^2- ligand, an O atom of which also bridges the same pair of Na⁺ cations, then crosslinks these [Na(H₂O)₂]_n chains to form two-dimensional sheets. The two-dimensional sheets are further connected by inter­molecular hydrogen bonds, giving rise to a stabile hydrogen-bonded network.

S1. Introduction

In recent years, the crystal engineering of coordination polymers has aroused inter­est due to their structural versatility, unique properties and applications in different areas of science. Therefore, a large body of research has been focused on the structure and topology of coordination polymers (Kim et al., 2015; Smith, 2013; Liu & Zhao, 2013). In these fields, the selection of appropriate ligands as building blocks is critical to afford a range of topologies. Multidentate N- and O-atom donors have attracted considerable attention due to their varying coordination modes (Galani et al., 2014; Mirzaei et al., 2013; Zhao et al., 2008). Alkali metal cations are known for their mainly ionic chemistry in aqueous media. Their coordination number varies depending on the size of the binding partners, and on the electrostatic inter­action between ligands and the metal ions. Thus, the synthesis of coordination polymer networks with these metal ions is of crucial importance (Fromm, 2008; Golovnev & Molokeev, 2013).

Based on the inter­est in coordination polymers described above, we have prepared 4,4'-diazenediyl-bis­(1H-1,2,4-triazol-5-one) (ZTO) and its coordination polymer networks with alkali metal ions. In this work, the bridging behaviour of the two-dimensional coordination polymer poly[tetra-µ-aqua-[µ₄-4,4'-diazenediyl-bis­(5-oxo-1H-1,2,4-triazolido)]disodium(I)], (I) (see Scheme 1), is reported. The structure of ZTO has been reported previously (Ma, Huang, Ma et al., 2013). The introduction of diazenediyl groups in triazole compounds could improve their enthalpy of formation, density and molecular stability. All eight N atoms in the ZTO molecule have potential to be coordinating atoms. Therefore, the ZTO ligand has a variety of potential coordination modes with metal centres (Vimal-Kumar & Radhakrishnan, 2011; Coropceanu et al., 2014; Wang et al., 2012). In addition, their structures contain a disproportionately large number of nitro­gen-containing bonds, such as N—N, C—N, C═N and N═N (Sivabalan et al., 2006; Yang et al., 2008; Yan et al., 2015). They are of inter­est as high nitro­gen energetic materials (Zhong et al., 2011) which could be used as high explosives or as inter­mediates in pyrotechnic mixtures in safety systems. The structures of alkali metal salts with ZTO are of inter­est because of their ability to form polymeric systems.

S2. Experimental

S2.1. Synthesis and crystallization

ATO and ZTO were prepared according to the literature procedures of Ma, Huang, Zhong et al. (2013). Compound (I) was obtained by dissolving ZTO (0.5 g, 2 mmol) and NaOH (0.4 g, 10 mmol) in water (5 ml). The reaction scheme, carried out at 418 K for 3 h, is shown in Scheme 2. The resulting mixture was cooled slowly to room temperature. Bright-yellow crystals of (I) formed and were filtered off and dried. IR (KBr, cm^-1): ν_N—H 3297, ν_C—H 3140, ν_N═N 2986 , ν_C═N 1664, ν_C—N 1333. Elemental analysis calculated for C₄H₁₀N₈Na₂O₆: C 15.39, H 3.24, N 35.89%; found: C 15.35, H 3.43, N 35.72%.

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1. H atoms bonded to C atoms was refined freely. H atoms bonded to water O atoms were located from difference Fourier maps and refined with O—H bond distances restrained to 0.82 (1) Å, with freely refined isotropic atomic displacement parameters.

S3. Results and discussion

The angles of the triazole ring of the 4,4'-diazenediyl-bis­(5-oxo-1H-1,2,4-triazolide) (ZTO^2-) ligand add up to 540° (Table 2), which indicates that atoms C1, C2, N2, N3 and N4 are located in the same plane. The N—C bond lengths are between normal C—N single- (1.471 Å) and C═N double-bond lengths (1.273 Å). The N3—N4 bond length is between isolated N—N (1.449 Å) and N═N (1.273 Å) bond lengths. The standard bond lengths above were collated according to Allen et al. (1987). Therefore, the C1, C2, N2, N3 and N4 of ZTO^2- in (I) form a conjugated ring.

The X-ray single-crystal determination indicates that complex (I) is a polymer. The ZTO^2- ligand is located about an inversion centre at the mid-point of the N1═N1ⁱ bond. The asymmetric unit of (I) consists of one Na⁺ cation, half a ZTO^2- ligand and two water ligands. Each Na⁺ cation is o­cta­hedrally coordinated by six O atoms, i.e. two from two independent ZTO^2- ligands and the remainder from four water molecules (Fig. 1). The Na—O distances are in the range 2.3214 (12)–2.5761 (13) Å (Table 2). The Na⁺ atom has an unusual trigonal anti­prismatic geometry, reflected in the bond lengths and angles about this atom (Table 2), and is located near the a-glide, thus the two bridging O atoms from the two coordinating ZTO^2- ligands are on adjacent apices of the trigonal anti­prism, rather than being in an anti configuration. The Na⁺ ion in (I) and the K⁺ ion in [K(ZTO)(H₂O)]_n (Ma, Huang, Ma et al., 2013) both adopt a six-coordinated geometry; however, the coordination environment of the Na⁺ is different compared with that of the K⁺ ion. In the potassium salt, one K⁺ ion is coordinated by five adjacent ZTO^2- ligands (through three K—O bonds and two K—N bonds) and by one water molecule, and the second K⁺ ion is coordinated by five adjacent ZTO ligands (through two K—O bonds and three K—N bonds) and by one water molecule. In (I), the Na⁺ atom is coordinated by four bridging water molecules and two O atoms of two ZTO^2- ligands.

All the water molecules and ZTO^2- ligands in complex (I) act as bridges between metal centres. Each Na⁺ centre is inter­linked by four bridging water ligands to give rise to a one-dimensional [Na(H₂O)₂]_n chain along the b axis (Fig. 2). Each O atom of the ZTO^2- ligand bridges two Na⁺ ions, thus bridging the [Na(H₂O)₂]_n chains to form two-dimensional sheets parallel to the b axis (Fig. 2).

The crystal structure of complex (I) is stabilized by hydrogen bonds. Water atom O1 is a donor to atoms N4ⁱⁱ and N3^iv, while O2 donates hydrogen bonds to O3ⁱⁱ and N4ⁱⁱⁱ (see Table 3 for geometric details and symmetry codes). These hydrogen bonds link the two-dimensional sheets into a three-dimensional hydrogen-bonded network (Fig. 3).

Structure description

In recent years, the crystal engineering of coordination polymers has aroused inter­est due to their structural versatility, unique properties and applications in different areas of science. Therefore, a large body of research has been focused on the structure and topology of coordination polymers (Kim et al., 2015; Smith, 2013; Liu & Zhao, 2013). In these fields, the selection of appropriate ligands as building blocks is critical to afford a range of topologies. Multidentate N- and O-atom donors have attracted considerable attention due to their varying coordination modes (Galani et al., 2014; Mirzaei et al., 2013; Zhao et al., 2008). Alkali metal cations are known for their mainly ionic chemistry in aqueous media. Their coordination number varies depending on the size of the binding partners, and on the electrostatic inter­action between ligands and the metal ions. Thus, the synthesis of coordination polymer networks with these metal ions is of crucial importance (Fromm, 2008; Golovnev & Molokeev, 2013).

Based on the inter­est in coordination polymers described above, we have prepared 4,4'-diazenediyl-bis­(1H-1,2,4-triazol-5-one) (ZTO) and its coordination polymer networks with alkali metal ions. In this work, the bridging behaviour of the two-dimensional coordination polymer poly[tetra-µ-aqua-[µ₄-4,4'-diazenediyl-bis­(5-oxo-1H-1,2,4-triazolido)]disodium(I)], (I) (see Scheme 1), is reported. The structure of ZTO has been reported previously (Ma, Huang, Ma et al., 2013). The introduction of diazenediyl groups in triazole compounds could improve their enthalpy of formation, density and molecular stability. All eight N atoms in the ZTO molecule have potential to be coordinating atoms. Therefore, the ZTO ligand has a variety of potential coordination modes with metal centres (Vimal-Kumar & Radhakrishnan, 2011; Coropceanu et al., 2014; Wang et al., 2012). In addition, their structures contain a disproportionately large number of nitro­gen-containing bonds, such as N—N, C—N, C═N and N═N (Sivabalan et al., 2006; Yang et al., 2008; Yan et al., 2015). They are of inter­est as high nitro­gen energetic materials (Zhong et al., 2011) which could be used as high explosives or as inter­mediates in pyrotechnic mixtures in safety systems. The structures of alkali metal salts with ZTO are of inter­est because of their ability to form polymeric systems.

The angles of the triazole ring of the 4,4'-diazenediyl-bis­(5-oxo-1H-1,2,4-triazolide) (ZTO^2-) ligand add up to 540° (Table 2), which indicates that atoms C1, C2, N2, N3 and N4 are located in the same plane. The N—C bond lengths are between normal C—N single- (1.471 Å) and C═N double-bond lengths (1.273 Å). The N3—N4 bond length is between isolated N—N (1.449 Å) and N═N (1.273 Å) bond lengths. The standard bond lengths above were collated according to Allen et al. (1987). Therefore, the C1, C2, N2, N3 and N4 of ZTO^2- in (I) form a conjugated ring.

The X-ray single-crystal determination indicates that complex (I) is a polymer. The ZTO^2- ligand is located about an inversion centre at the mid-point of the N1═N1ⁱ bond. The asymmetric unit of (I) consists of one Na⁺ cation, half a ZTO^2- ligand and two water ligands. Each Na⁺ cation is o­cta­hedrally coordinated by six O atoms, i.e. two from two independent ZTO^2- ligands and the remainder from four water molecules (Fig. 1). The Na—O distances are in the range 2.3214 (12)–2.5761 (13) Å (Table 2). The Na⁺ atom has an unusual trigonal anti­prismatic geometry, reflected in the bond lengths and angles about this atom (Table 2), and is located near the a-glide, thus the two bridging O atoms from the two coordinating ZTO^2- ligands are on adjacent apices of the trigonal anti­prism, rather than being in an anti configuration. The Na⁺ ion in (I) and the K⁺ ion in [K(ZTO)(H₂O)]_n (Ma, Huang, Ma et al., 2013) both adopt a six-coordinated geometry; however, the coordination environment of the Na⁺ is different compared with that of the K⁺ ion. In the potassium salt, one K⁺ ion is coordinated by five adjacent ZTO^2- ligands (through three K—O bonds and two K—N bonds) and by one water molecule, and the second K⁺ ion is coordinated by five adjacent ZTO ligands (through two K—O bonds and three K—N bonds) and by one water molecule. In (I), the Na⁺ atom is coordinated by four bridging water molecules and two O atoms of two ZTO^2- ligands.

All the water molecules and ZTO^2- ligands in complex (I) act as bridges between metal centres. Each Na⁺ centre is inter­linked by four bridging water ligands to give rise to a one-dimensional [Na(H₂O)₂]_n chain along the b axis (Fig. 2). Each O atom of the ZTO^2- ligand bridges two Na⁺ ions, thus bridging the [Na(H₂O)₂]_n chains to form two-dimensional sheets parallel to the b axis (Fig. 2).

The crystal structure of complex (I) is stabilized by hydrogen bonds. Water atom O1 is a donor to atoms N4ⁱⁱ and N3^iv, while O2 donates hydrogen bonds to O3ⁱⁱ and N4ⁱⁱⁱ (see Table 3 for geometric details and symmetry codes). These hydrogen bonds link the two-dimensional sheets into a three-dimensional hydrogen-bonded network (Fig. 3).

Synthesis and crystallization

ATO and ZTO were prepared according to the literature procedures of Ma, Huang, Zhong et al. (2013). Compound (I) was obtained by dissolving ZTO (0.5 g, 2 mmol) and NaOH (0.4 g, 10 mmol) in water (5 ml). The reaction scheme, carried out at 418 K for 3 h, is shown in Scheme 2. The resulting mixture was cooled slowly to room temperature. Bright-yellow crystals of (I) formed and were filtered off and dried. IR (KBr, cm^-1): ν_N—H 3297, ν_C—H 3140, ν_N═N 2986 , ν_C═N 1664, ν_C—N 1333. Elemental analysis calculated for C₄H₁₀N₈Na₂O₆: C 15.39, H 3.24, N 35.89%; found: C 15.35, H 3.43, N 35.72%.

Refinement details

Crystal data, data collection and structure refinement details are summarized in Table 1. H atoms bonded to C atoms was refined freely. H atoms bonded to water O atoms were located from difference Fourier maps and refined with O—H bond distances restrained to 0.82 (1) Å, with freely refined isotropic atomic displacement parameters.

Computing details

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2014 (Sheldrick, 2015); molecular graphics: DIAMOND (Brandenburg, 2006) and Mercury (Macrae et al., 2006).

Figures

	Fig. 1. The coordination environment for the Na^+ cations of complex (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) -x+1, -y+1, -z+1; (ii) x-1/2, y, -z+1/2; (iii) x+1/2, y, -z+1/2; (iv) -x+1/2, 1-y, 1/2+z.]
	Fig. 2. A projection of the structure of complex (I) along the b axis, showing the two-dimensional sheets.
	Fig. 3. The crystal packing of complex (I), viewed along the a axis. Dashed lines indicate hydrogen bonds. The two-dimensional sheets are highlighted in light blue and red.

Poly[tetra-µ-aqua-[µ₄-4,4'-diazenediyl-bis(5-oxo-1H-1,2,4-triazolido)]disodium(I)]

Crystal data

[Na2(C4H2N8O2)(H2O)4]	Dx = 1.768 Mg m^−3
Mr = 312.18	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 2550 reflections
a = 6.4055 (14) Å	θ = 2.6–27.7°
b = 11.587 (3) Å	µ = 0.22 mm^−1
c = 15.805 (4) Å	T = 296 K
V = 1173.1 (4) Å^3	Block, yellow
Z = 4	0.36 × 0.29 × 0.13 mm
F(000) = 640

Data collection

Bruker APEXII CCD diffractometer	1212 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.040
φ and ω scans	θmax = 28.2°, θmin = 2.6°
Absorption correction: multi-scan (SADABS; Bruker, 2008)	h = −8→7
Tmin = 0.927, Tmax = 0.972	k = −15→13
6117 measured reflections	l = −17→19
1405 independent reflections

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)] = 0.034	Hydrogen site location: difference Fourier map
wR(F^2) = 0.087	All H-atom parameters refined
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0392P)^2 + 0.4139P] where P = (Fo^2 + 2Fc^2)/3
1405 reflections	(Δ/σ)max < 0.001
111 parameters	Δρmax = 0.22 e Å^−3
5 restraints	Δρmin = −0.34 e Å^−3

Special details

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.

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

	x	y	z	Uiso*/Ueq
Na1	0.19648 (10)	0.52927 (5)	0.23877 (4)	0.02991 (19)
N1	0.48906 (19)	0.51774 (9)	0.46287 (7)	0.0219 (3)
N2	0.42821 (18)	0.63169 (9)	0.46264 (7)	0.0207 (3)
N3	0.3768 (2)	0.81037 (9)	0.50095 (7)	0.0244 (3)
N4	0.39312 (19)	0.80744 (9)	0.41183 (7)	0.0242 (3)
O1	0.46737 (19)	0.52938 (9)	0.13650 (7)	0.0311 (3)
O2	0.42366 (19)	0.36848 (10)	0.28232 (7)	0.0318 (3)
O3	0.45508 (17)	0.65968 (8)	0.31472 (6)	0.0272 (3)
C1	0.3986 (2)	0.70624 (12)	0.52894 (9)	0.0227 (3)
C2	0.4280 (2)	0.69868 (11)	0.38842 (8)	0.0201 (3)
H1A	0.395 (3)	0.6871 (14)	0.5801 (6)	0.030 (4)*
H2A	0.443 (4)	0.3085 (13)	0.2554 (13)	0.064 (7)*
H1B	0.495 (4)	0.4644 (11)	0.1197 (14)	0.056 (7)*
H2B	0.344 (3)	0.3508 (18)	0.3214 (10)	0.050 (6)*
H1C	0.450 (3)	0.5708 (15)	0.0954 (9)	0.047 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Na1	0.0287 (3)	0.0303 (3)	0.0307 (3)	0.0051 (2)	0.0020 (2)	0.0039 (2)
N1	0.0269 (6)	0.0154 (5)	0.0234 (6)	0.0015 (4)	−0.0011 (5)	0.0013 (4)
N2	0.0279 (6)	0.0146 (5)	0.0194 (6)	0.0017 (4)	−0.0006 (4)	0.0009 (4)
N3	0.0315 (7)	0.0208 (6)	0.0210 (6)	0.0032 (5)	−0.0001 (5)	−0.0027 (5)
N4	0.0338 (7)	0.0173 (5)	0.0214 (6)	0.0025 (5)	0.0007 (5)	0.0011 (4)
O1	0.0463 (7)	0.0238 (5)	0.0232 (6)	0.0056 (5)	0.0027 (5)	0.0017 (4)
O2	0.0406 (6)	0.0282 (6)	0.0268 (6)	−0.0028 (5)	0.0058 (5)	0.0017 (5)
O3	0.0383 (6)	0.0250 (5)	0.0183 (5)	0.0046 (4)	0.0015 (4)	−0.0005 (4)
C1	0.0275 (7)	0.0226 (6)	0.0180 (7)	0.0020 (5)	−0.0005 (5)	−0.0007 (5)
C2	0.0224 (6)	0.0179 (6)	0.0199 (7)	0.0010 (5)	−0.0005 (5)	0.0025 (5)

Geometric parameters (Å, º)

Na1—O3^i	2.3214 (12)	N3—C1	1.2927 (17)
Na1—O1	2.3714 (14)	N3—N4	1.4129 (17)
Na1—O1^i	2.4575 (14)	N4—C2	1.3323 (17)
Na1—O2	2.4623 (13)	O1—Na1^ii	2.4576 (14)
Na1—O3	2.5433 (12)	O1—H1B	0.818 (10)
Na1—O2^i	2.5761 (13)	O1—H1C	0.815 (9)
Na1—Na1^ii	3.2223 (7)	O2—Na1^ii	2.5761 (13)
Na1—Na1^i	3.2224 (7)	O2—H2A	0.825 (10)
Na1—H2B	2.62 (2)	O2—H2B	0.828 (9)
N1—N1^iii	1.251 (2)	O3—C2	1.2614 (17)
N1—N2	1.3767 (14)	O3—Na1^ii	2.3214 (12)
N2—C1	1.3712 (17)	C1—H1A	0.839 (9)
N2—C2	1.4066 (17)
O3^i—Na1—O1	103.82 (4)	O3—Na1—H2B	90.0 (4)
O3^i—Na1—O1^i	83.92 (4)	O2^i—Na1—H2B	74.8 (4)
O1—Na1—O1^i	169.64 (5)	Na1^ii—Na1—H2B	65.6 (3)
O3^i—Na1—O2	171.12 (5)	Na1^i—Na1—H2B	107.6 (3)
O1—Na1—O2	76.02 (4)	N1^iii—N1—N2	110.45 (13)
O1^i—Na1—O2	97.42 (4)	C1—N2—N1	129.88 (11)
O3^i—Na1—O3	102.65 (5)	C1—N2—C2	106.83 (11)
O1—Na1—O3	81.07 (4)	N1—N2—C2	122.12 (11)
O1^i—Na1—O3	90.58 (4)	C1—N3—N4	108.10 (11)
O2—Na1—O3	86.14 (4)	C2—N4—N3	108.18 (10)
O3^i—Na1—O2^i	88.39 (5)	Na1—O1—Na1^ii	83.70 (4)
O1—Na1—O2^i	114.11 (5)	Na1—O1—H1B	112.3 (17)
O1^i—Na1—O2^i	72.49 (4)	Na1^ii—O1—H1B	97.5 (17)
O2—Na1—O2^i	83.67 (4)	Na1—O1—H1C	116.5 (15)
O3—Na1—O2^i	158.85 (4)	Na1^ii—O1—H1C	136.0 (15)
O3^i—Na1—Na1^ii	134.60 (3)	H1B—O1—H1C	108 (2)
O1—Na1—Na1^ii	49.29 (3)	Na1—O2—Na1^ii	79.48 (4)
O1^i—Na1—Na1^ii	120.34 (4)	Na1—O2—H2A	125.6 (18)
O2—Na1—Na1^ii	51.82 (3)	Na1^ii—O2—H2A	116.1 (18)
O3—Na1—Na1^ii	45.63 (3)	Na1—O2—H2B	91.7 (15)
O2^i—Na1—Na1^ii	133.51 (3)	Na1^ii—O2—H2B	134.0 (15)
O3^i—Na1—Na1^i	51.54 (3)	H2A—O2—H2B	106 (2)
O1—Na1—Na1^i	143.35 (4)	C2—O3—Na1^ii	131.37 (9)
O1^i—Na1—Na1^i	47.01 (3)	C2—O3—Na1	124.00 (9)
O2—Na1—Na1^i	123.82 (3)	Na1^ii—O3—Na1	82.83 (4)
O3—Na1—Na1^i	126.54 (3)	N3—C1—N2	109.96 (12)
O2^i—Na1—Na1^i	48.70 (3)	N3—C1—H1A	125.0 (12)
Na1^ii—Na1—Na1^i	167.35 (4)	N2—C1—H1A	125.0 (12)
O3^i—Na1—H2B	159.2 (3)	O3—C2—N4	128.20 (12)
O1—Na1—H2B	94.4 (3)	O3—C2—N2	124.92 (12)
O1^i—Na1—H2B	79.4 (3)	N4—C2—N2	106.89 (11)
O2—Na1—H2B	18.4 (2)
N1^iii—N1—N2—C1	2.5 (2)	Na1^ii—O3—C2—N2	−45.10 (19)
N1^iii—N1—N2—C2	168.54 (14)	Na1—O3—C2—N2	68.08 (16)
C1—N3—N4—C2	−0.81 (16)	N3—N4—C2—O3	−178.85 (14)
N4—N3—C1—N2	−0.34 (16)	N3—N4—C2—N2	1.58 (15)
N1—N2—C1—N3	168.94 (13)	C1—N2—C2—O3	178.64 (13)
C2—N2—C1—N3	1.30 (16)	N1—N2—C2—O3	9.8 (2)
Na1^ii—O3—C2—N4	135.40 (13)	C1—N2—C2—N4	−1.77 (15)
Na1—O3—C2—N4	−111.42 (14)	N1—N2—C2—N4	−170.59 (12)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2A···O3^iv	0.83 (1)	2.15 (1)	2.9679 (16)	171 (3)
O1—H1B···N4^iv	0.82 (1)	2.02 (1)	2.8277 (16)	171 (2)
O2—H2B···N4^v	0.83 (1)	2.14 (1)	2.9678 (17)	173 (2)
O1—H1C···N3^vi	0.82 (1)	2.09 (1)	2.8940 (16)	172 (2)

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