Bis(di-2-pyridylamine-κ²N²,N^2′)(nitrato-κ²O,O′)nickel(II) nitrate

<!?tpct=26.8pt>In the ionic title compound, [Ni(NO₃)(C₁₀H₉N₃)₂]NO₃, the central Ni^II atom exhibits cis-NiN₄O₂ octahedral coordination with three chelating ligands, viz. one nitrate anion and two di-2-pyridylamine (dpya) molecules. A second nitrate group acts as a counter-ion. The complex cations and the nitrate anions are also linked by N—H...O hydrogen bonds. The compound was prepared in two different reproducible ways: direct synthesis from Ni(NO₃)₂ and dpya yielded systematically twinned crystals (the twinning law is discussed), while single crystals were obtained unexpectedly from the Ni(NO₃)₂/dpya/maleic acid/NaOH system.

S1. Comment

Complexes of Ni^II (S = 1) represent a class of model compounds suitable for studies of various physical phenomena associated with magnetism (Haldane, 1983a,b; Orendáč et al., 1995; Boča & Titiš, 2008). Previously, we have prepared and studied several low-dimensional Ni^II complexes in which diamagnetic cyanocomplex anions were used as bridging species (Černák et al., 2002, 2003; Paharová et al., 2003). In order to replace them, we decided to explore the bridging ability of the dicarboxylate ligands, namely maleate (mal). Literature data indicate that the maleate ligand can effectively link central atoms; as examples, the maleate complexes [Ni(H₂O)₃(phen)(mal)].H₂O (phen is 1,10-phenanthroline) and [Ni(py)(H₂O)(mal)] (py is pyridine) can be mentioned (Zheng et al., 2002; Chen et al., 2003). As part of our effort to prepare the above-mentioned low-dimensional maleate complex of Ni^II, in which di-2-dipyridylamine (dpya) should act as a blocking ligand, we have isolated from an aqueous ethanol system the title compound, Ni(dpya)₂(NO₃)₂, (I), in an unexpected but nonetheless reproducible way.

Two synthetic procedures led to the formation of the same product, Ni(dpya)₂(NO₃)₂ (see scheme). Preliminary studies showed crystals from both batches to exhibit the same structure, but while those obtained from the maleate synthesis were single crystals, those obtained by direct targeted synthesis were systematically twinned. The twin domains characterized by the unit-cell vectors (a₁, b₁ and c₁ for the first twin domain and a₂, b₂ and c₂ for the second) in the direct space are related by the symmetry operation (a₂, b₂, c₂) = T(a₁, b₁, c₁) (where as usual the elements involved are a row vector, a square matrix and a column vector, respectively, and where T = U₁^-1U₂ = (-1, 0, -0, 73; 0, -1, 0; 0, 0, 1) (expressed by rows), and U₁ and U₂ are orientation matrices of the first and the second twin domain, respectively. In the direct space the c₁ and c₂ axes of both domains coincide, while the b₁ and b₂ axes are opposite halflines. The transposed matrix T^t transforms the reciprocal base (column) vectors in the way indicated in Fig. 1. The second domain is linked to the first by a pseudo-twofold rotation axis defined by a reciprocal vector 2c^*₁ - 0.73a^*₁, where a^*₁ and c^*₁ are vectors of the first domain. Further discussion about the origin of the observed twinning lies outside the scope of the present report.

The ionic structure of (I) is built up of [Ni(dpya)₂(NO)₃]⁺ complex cations and nitrate^- counter-ions. As shown in Fig. 2, the central Ni^II atom exhibits a very distorted six-coordination. Four coordination sites are occupied by two chelating dpya ligands via pyridine-type N atoms, while the remaining two coordination sites are occupied by a chelating nitrate ligand.

The Ni—N coordination bond lengths are rather uniform and span the range 2.0374 (11)–2.0716 (17) Å; the dihedral angles subtended by dpya pyridine rings are 27.87 (5)° (between the N1- and N3-containing pyridine rings) and 22.72 (5)° (between the N4 and N6 pyridine rings), similar to the 26.1 (3)° found in the [Ni(dpya)₂(C₂N₃)₂] complex (Huang et al., 2006).

The chelating mode of the nitrate ligand is not uncommon, for example, it was found in [Ni(NO)₃(biqui)(H₂O)₂]NO₃.H₂O (biqui is 2,2'-biquinoline; Freire et al., 2001). As a consequence of chelation the O—Ni—O angle within the four-membered ring is very acute [60.58 (4)°], close to the reported mean value of 59.7 (12)° for such types of coordination (Freire et al., 2001).

The nitrate ligand presents slightly shorter and more symmetrical Ni—O distances (Table 1) than the corresponding ones [2.2065 (10) and 2.1477 (10) Å] in the similar [Ni(NO)₃(biqui)(H₂O)₂]NO₃.H₂O complex with the bulkier biqui ligand (Freire et al., 2001). As a consequence of the binding to the metal, the coordinated N—O distances (O2—N7 = 1.2806 (18) Å and O3—N7 = 1.2798 (19) Å] appear significantly longer than the uncoordinated one [N7—O1 =1.220 (2) Å]. Similar, though less marked differences are also observed in the unbound nitrate anion, with two longer [N8—O5 = 1.262 (2) Å and N8—O6 1.265 (2) Å] and one shorter [N8—O4 = 1.228 (3) Å] N—O bonds (Fig. 2 and Table 2). In this case, however, longer bonds correspond to O atoms strongly involved in hydrogen bonding (Table 2 and Fig. 2).

Although the crystal structure of (I) is essentially ionic, there are a number of weak interactions exhibiting directional character and which contribute to packing stabilization, the most relevant being conventional hydrogen bonds of the N—H···O type, non-conventional C—H···O contacts and π–π interactions.

Regarding the hydrogen bonds, the aforementioned N—H···O interactions link complex cations and nitrate anions in a chain-like arrangement parallel to the [201] direction. Furthermore, there are a number of aromatic H atoms exhibiting short C—H···O_nitrate contacts, many in the limit of commonly accepted hydrogen bonds (the most relevant are reported in Table 2).

The structure presents, in addition, face-to-face π–π interactions between pairs of centrosymmetric pyridine rings, viz. those containing N1 and N1ⁱⁱⁱ [symmetry code: (iii) -x + 1, -y + 1, -z], and N4 and N4^iv [symmetry code: (ii) -x, -y, -z]. The corresponding rings are coplanar, with intercentroid (Cg) distances of 3.7097 (9) Å [Cg(N1)···Cg(N1ⁱ)] and 3.9993 (9) Å [Cg(N4)···Cg(N4ⁱⁱ)], and interplanar separations of 3.478 and 3.307 Å, respectively (Fig. 3). These π–π interactions as well as the C12—H12···π interaction reported in Table 2 serve to link the hydrogen-bonded cation–anion chains into a weakly bound three-dimensional structure.

Related literature

For related literature, see: Boča & Titiš (2008); Chen et al. (2003); Freire et al. (2001); Haldane (1983a, 1983b); Huang et al. (2006); Orendáč et al. (1995); Paharová et al. (2003); Zheng et al. (2002); Černák et al. (2002, 2003).

S2. Experimental

For the fortuitous preparation (single crystals), to an aqueous solution (20 ml) containing Ni(NO)₃.6H₂O (1.454 g, 5 mmol) was added slowly an aqueous solution (7.5 ml) of Na₂mal (0.8 g, 5 mmol). To the resulting green solution an ethanol solution (2 ml) of dpya (0.856 g, 5 mmol) was added with stirring. The resulting violet solution was filtered and left aside for crystallization at room temperature. Violet single crystals in the form of parallelepipeds of the unexpected complex [Ni(dpya)₂(NO)₃]NO₃ were obtained by crystallization at laboratory temperature within two weeks. Yield 1.16 g (80%).

For the targeted preparation (twins), Ni(NO)₃.6H₂O (1.454 g, 5 mmol) and dpya (0.856 g, 5 mmol) were successively dissolved in 10 ml of an ethanol/water mixture (1:1 in volume). The resulting violet solution was filtered and left for crystallization at room temperature. After two weeks, violet irregular cubes of the title compound were collected. Yield 0.957 g (54%). Colour is described as `blue' in CIF; please check.

Calculated for C₂₀H₁₈N₈NiO₆ (Mr = 525.1 g mol^-1): C 45.74, H 3.45, N 21.33, Ni 11.17%; found: C 45.46, H 3.47, N 21.30, Ni 10.35%.

S3. Refinement

All H atoms could be localized from the difference Fourier map, but according to the commonly used practice were constrained to ideal positions and allowed to ride. Their U_iso values were calculated as 1.2U_eq of the parent atom.

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2007); cell refinement: CrysAlis RED (Oxford Diffraction, 2007); data reduction: CrysAlis RED (Oxford Diffraction, 2007); program(s) used to solve structure: SIR2002 (Burla et al., 2003); program(s) used to refine structure: JANA2006 (Petříček et al., 2007); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: JANA2006 (Petříček et al., 2007).

Figures

	Fig. 1. The relationship of the reciprocal elementary cells of the two twin domains displayed on the basis of the experimental positions of the reflections (red and blue in the electronic version of the paper) found systematically in the samples of (I) prepared by targeted preparation. The view is along b^*2 = -b^*1. The reciprocal axes a^*i and c^*i (i = 1, 2) are indicated by labeled arrows. The direction of b*^*1 (as well as that of b*^*2) follows the right-hand condition. [AUTHOR: this journal prints all figures in black and white, although colour figures can be shown in colour in the online version of the journal; please ensure that you are satisfied with the appearance of this figure when converted to greyscale, or supply an alternative.]
	Fig. 2. One-dimensional arrangement of the ions in [Ni(dpya)2(NO)3]NO3 connected by N—H···O and C—H···O hydrogen bonds (dashed lines). Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) -1 + x, -y + 1/2, z - 1/2; (ii) x, -y + 1/2, z + 1/2.]
	Fig. 3. The packing diagram [Ni(dpya)2(NO)3]NO3. Dashed lines represent face-to-face π–π interactions and C–H···π interactions. [Symmetry codes: (iii) -x + 1, -y + 1, -z; (iv) -x, -y, -z; (iii) x, -y + 1/2, z + 1/2.]

Bis(di-2-pyridylamine-κ²N²,N^2')(nitrato- k²O,O')nickel(II) nitrate

Crystal data

[Ni(NO3)(C10H9N3)2]NO3	F(000) = 1080
Mr = 525.1	Dx = 1.646 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 14914 reflections
a = 14.5928 (2) Å	θ = 2.6–26.5°
b = 9.8699 (2) Å	µ = 0.98 mm^−1
c = 16.0846 (3) Å	T = 120 K
β = 113.843 (2)°	Prism, violet
V = 2118.95 (7) Å^3	0.42 × 0.22 × 0.16 mm
Z = 4

Data collection

Oxford Diffraction Xcalibur 2 diffractometer with a Sapphire 2 CCD detector	4401 independent reflections
Radiation source: X-ray tube	3553 reflections with I > 3σ(I)
Graphite monochromator	Rint = 0.025
Detector resolution: 8.3438 pixels mm^-1	θmax = 26.5°, θmin = 2.5°
Rotation method data acquisition using ω scans	h = −18→18
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2007)	k = −12→12
Tmin = 0.740, Tmax = 0.900	l = −20→20
25248 measured reflections

Refinement

Refinement on F^2	66 constraints
R[F^2 > 2σ(F^2)] = 0.023	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.064	Weighting scheme based on measured s.u.'s w = 1/[σ^2(I) + 0.0016I^2]
S = 1.08	(Δ/σ)max = 0.007
4401 reflections	Δρmax = 0.18 e Å^−3
322 parameters	Δρmin = −0.17 e Å^−3
2 restraints

Special details

Experimental. For elemental anallysis: Perkin-Elmer CHN 2400 Elemental Analyzer; nickel by AAS Varian Spectra AA240 FS

IR (Nicolet Avatar 330 F T—IR, KBr, in cm^-1): 432, 539, 644, 704, 772, 840, 869, 910, 1016, 1052, 1160, 1238, 1267, 1317, 1331, 1384, 1421, 1437, 1476, 1532, 1582, 1645, 2997, 3018, 3074, 3136, 3196, 3237, 3297.

UV-VIS (Specord 40, KBr pellets, concentration 15: 200 mg, deconvolution of the asymmetric band was made using ORIGIN program [OriginLab, 2008], in nm: 540 (B_1g → ³A₂), 619 s h (B_1g → ³B₂), 888 (B_1g → ³E(T_2g)); assignement made according to Lever, Walker & MC Carthy (1982).

Refinement. The refinement was carried out against all reflections. The conventional R-factor is always based on F. The goodness of fit as well as the weighted R-factor are based on F and F² for refinement carried out on F and F², respectively. The threshold expression is used only for calculating R-factors etc. and it is not relevant to the choice of reflections for refinement.

The hydrogen atoms could be localized from the difference Fourier map. Despite of that, all hydrogen atoms, except H2n and H5n, were constrained to ideal positions. The N-H distances were restrained to 0.87Å with σ 0.01. The isotropic temperature parameters of hydrogen atoms were calculated as 1.2*U_eq of the parent atom.

The program used for refinement, Jana2006, uses the weighting scheme based on the experimental expectations, see _refine_ls_weighting_details, that does not force S to be one. Therefore the values of S are usually larger than the ones from the SHELX program.

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

	x	y	z	Uiso*/Ueq
Ni1	0.255028 (13)	0.286718 (19)	0.031241 (12)	0.01455 (7)
O1	0.27780 (11)	−0.06906 (12)	−0.04116 (8)	0.0360 (5)
O2	0.20731 (8)	0.13091 (11)	−0.07205 (7)	0.0221 (4)
O3	0.32559 (8)	0.09276 (11)	0.06055 (7)	0.0211 (4)
O4	0.72889 (10)	0.27464 (15)	0.36508 (9)	0.0385 (5)
O5	0.83019 (8)	0.23768 (12)	0.29923 (8)	0.0254 (4)
O6	0.69745 (8)	0.35993 (13)	0.23199 (8)	0.0289 (4)
N1	0.36802 (9)	0.33834 (13)	−0.00976 (8)	0.0152 (4)
N2	0.48874 (9)	0.33502 (13)	0.14230 (8)	0.0166 (4)
N3	0.33349 (9)	0.38677 (13)	0.14967 (8)	0.0165 (4)
N4	0.14562 (9)	0.21213 (13)	0.06895 (8)	0.0171 (4)
N5	0.01542 (9)	0.30067 (13)	−0.06264 (9)	0.0196 (5)
N6	0.15800 (9)	0.43677 (13)	−0.03750 (8)	0.0166 (4)
N7	0.27041 (10)	0.04699 (14)	−0.01832 (9)	0.0215 (5)
N8	0.75161 (9)	0.29001 (13)	0.30003 (9)	0.0215 (5)
C1	0.34944 (11)	0.34350 (15)	−0.09953 (10)	0.0178 (5)
C2	0.42269 (11)	0.33651 (16)	−0.13200 (10)	0.0197 (6)
C3	0.52169 (11)	0.31843 (16)	−0.07025 (10)	0.0200 (6)
C4	0.54294 (11)	0.31597 (15)	0.02110 (10)	0.0183 (5)
C5	0.46444 (11)	0.33051 (14)	0.04960 (10)	0.0148 (5)
C6	0.43447 (11)	0.38940 (15)	0.18792 (10)	0.0150 (5)
C7	0.48821 (11)	0.44355 (15)	0.27503 (10)	0.0181 (5)
C8	0.43636 (12)	0.49832 (15)	0.32163 (10)	0.0206 (6)
C9	0.33181 (12)	0.49993 (16)	0.28133 (10)	0.0218 (6)
C10	0.28469 (11)	0.44450 (16)	0.19658 (10)	0.0200 (6)
C11	0.17192 (11)	0.13254 (16)	0.14374 (10)	0.0204 (5)
C12	0.10539 (12)	0.06317 (16)	0.16772 (10)	0.0215 (6)
C13	0.00292 (12)	0.07388 (16)	0.11087 (10)	0.0201 (6)
C14	−0.02602 (11)	0.15334 (16)	0.03453 (10)	0.0188 (5)
C15	0.04725 (11)	0.22220 (15)	0.01520 (10)	0.0159 (5)
C16	0.05992 (11)	0.41097 (15)	−0.08437 (10)	0.0167 (5)
C17	−0.00083 (11)	0.49445 (16)	−0.15686 (10)	0.0189 (5)
C18	0.03961 (12)	0.60932 (16)	−0.17607 (10)	0.0216 (6)
C19	0.13951 (12)	0.64263 (16)	−0.12327 (10)	0.0206 (6)
C20	0.19468 (11)	0.55425 (16)	−0.05610 (10)	0.0197 (6)
H1c	0.281181	0.352539	−0.142537	0.0214*
H2c	0.406297	0.343892	−0.195947	0.0237*
H3c	0.574193	0.307865	−0.091267	0.024*
H4c	0.610619	0.304461	0.064843	0.022*
H7c	0.560127	0.44227	0.301552	0.0217*
H8c	0.471696	0.535173	0.381399	0.0247*
H9c	0.293979	0.538883	0.31224	0.0262*
H10c	0.212806	0.446638	0.168722	0.024*
H11c	0.241881	0.124443	0.182325	0.0244*
H12c	0.127862	0.008723	0.221771	0.0258*
H13c	−0.04612	0.026208	0.125285	0.0241*
H14c	−0.095585	0.161759	−0.005221	0.0226*
H17c	−0.069565	0.471108	−0.192255	0.0226*
H18c	−0.000507	0.666723	−0.225613	0.026*
H19c	0.168449	0.724762	−0.133759	0.0247*
H20c	0.263439	0.576515	−0.019927	0.0236*
H2n	0.5518 (7)	0.3364 (17)	0.1751 (10)	0.0199*
H5n	−0.0466 (8)	0.2908 (17)	−0.0993 (10)	0.0236*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.00892 (10)	0.01888 (11)	0.01449 (11)	−0.00099 (7)	0.00331 (8)	0.00010 (7)
O1	0.0607 (9)	0.0192 (6)	0.0394 (7)	−0.0029 (6)	0.0318 (7)	−0.0044 (5)
O2	0.0188 (5)	0.0259 (6)	0.0195 (5)	−0.0041 (5)	0.0056 (5)	−0.0003 (5)
O3	0.0183 (5)	0.0232 (6)	0.0205 (6)	0.0001 (5)	0.0067 (5)	0.0013 (4)
O4	0.0385 (8)	0.0547 (9)	0.0267 (7)	0.0067 (7)	0.0177 (6)	0.0019 (6)
O5	0.0142 (6)	0.0324 (6)	0.0254 (6)	0.0042 (5)	0.0037 (5)	−0.0008 (5)
O6	0.0142 (5)	0.0368 (7)	0.0278 (6)	0.0027 (5)	0.0004 (5)	0.0080 (5)
N1	0.0115 (6)	0.0167 (6)	0.0152 (6)	−0.0013 (5)	0.0031 (5)	−0.0010 (5)
N2	0.0085 (6)	0.0232 (7)	0.0158 (6)	0.0002 (5)	0.0026 (5)	0.0007 (5)
N3	0.0131 (6)	0.0191 (6)	0.0167 (6)	0.0015 (5)	0.0055 (5)	0.0004 (5)
N4	0.0130 (6)	0.0218 (7)	0.0155 (6)	−0.0005 (5)	0.0048 (5)	0.0000 (5)
N5	0.0098 (6)	0.0259 (7)	0.0189 (7)	−0.0030 (5)	0.0014 (5)	0.0023 (5)
N6	0.0118 (6)	0.0197 (7)	0.0174 (6)	0.0002 (5)	0.0051 (5)	−0.0004 (5)
N7	0.0248 (7)	0.0209 (7)	0.0240 (7)	−0.0035 (6)	0.0152 (6)	−0.0005 (5)
N8	0.0157 (7)	0.0241 (7)	0.0202 (7)	−0.0021 (6)	0.0025 (6)	−0.0039 (5)
C1	0.0144 (7)	0.0196 (8)	0.0169 (7)	−0.0011 (6)	0.0037 (6)	−0.0011 (6)
C2	0.0224 (8)	0.0209 (8)	0.0172 (8)	−0.0022 (6)	0.0094 (7)	−0.0016 (6)
C3	0.0176 (7)	0.0217 (8)	0.0247 (8)	−0.0030 (6)	0.0126 (7)	−0.0041 (6)
C4	0.0112 (7)	0.0206 (8)	0.0219 (8)	−0.0009 (6)	0.0054 (6)	−0.0019 (6)
C5	0.0136 (7)	0.0133 (7)	0.0167 (7)	−0.0007 (6)	0.0052 (6)	−0.0001 (5)
C6	0.0128 (7)	0.0144 (7)	0.0167 (7)	−0.0007 (6)	0.0049 (6)	0.0024 (5)
C7	0.0149 (7)	0.0191 (8)	0.0170 (7)	−0.0015 (6)	0.0030 (6)	0.0018 (6)
C8	0.0257 (8)	0.0193 (8)	0.0141 (7)	−0.0023 (6)	0.0052 (6)	−0.0004 (6)
C9	0.0249 (8)	0.0219 (8)	0.0210 (8)	0.0039 (7)	0.0117 (7)	0.0014 (6)
C10	0.0159 (7)	0.0225 (8)	0.0226 (8)	0.0019 (6)	0.0089 (7)	0.0001 (6)
C11	0.0151 (7)	0.0260 (8)	0.0177 (8)	0.0015 (6)	0.0042 (6)	0.0009 (6)
C12	0.0243 (8)	0.0230 (8)	0.0184 (8)	0.0013 (7)	0.0100 (7)	0.0026 (6)
C13	0.0198 (8)	0.0207 (8)	0.0240 (8)	−0.0036 (6)	0.0132 (7)	−0.0029 (6)
C14	0.0135 (7)	0.0228 (8)	0.0200 (8)	−0.0017 (6)	0.0066 (6)	−0.0048 (6)
C15	0.0140 (7)	0.0180 (7)	0.0151 (7)	0.0001 (6)	0.0052 (6)	−0.0021 (6)
C16	0.0148 (7)	0.0192 (8)	0.0174 (7)	−0.0002 (6)	0.0078 (6)	−0.0017 (6)
C17	0.0145 (7)	0.0242 (8)	0.0169 (7)	0.0038 (6)	0.0054 (6)	−0.0008 (6)
C18	0.0242 (8)	0.0218 (8)	0.0205 (8)	0.0067 (7)	0.0107 (7)	0.0026 (6)
C19	0.0249 (8)	0.0173 (8)	0.0245 (8)	0.0001 (6)	0.0151 (7)	−0.0004 (6)
C20	0.0159 (7)	0.0216 (8)	0.0234 (8)	−0.0018 (6)	0.0097 (7)	−0.0032 (6)

Geometric parameters (Å, º)

Ni1—O2	2.1621 (11)	C2—H2c	0.96
Ni1—O3	2.1342 (11)	C3—C4	1.374 (2)
Ni1—N1	2.0719 (15)	C3—H3c	0.96
Ni1—N3	2.0374 (11)	C4—C5	1.403 (3)
Ni1—N4	2.0595 (15)	C4—H4c	0.96
Ni1—N6	2.0384 (12)	C6—C7	1.4055 (19)
O1—N7	1.2209 (19)	C7—C8	1.373 (3)
O2—N7	1.2796 (16)	C7—H7c	0.96
O3—N7	1.2789 (15)	C8—C9	1.396 (2)
O4—N8	1.228 (2)	C8—H8c	0.96
O5—N8	1.2624 (19)	C9—C10	1.368 (2)
O6—N8	1.2646 (16)	C9—H9c	0.96
N1—C1	1.358 (2)	C10—H10c	0.96
N1—C5	1.3458 (16)	C11—C12	1.365 (3)
N2—C5	1.387 (2)	C11—H11c	0.96
N2—C6	1.387 (2)	C12—C13	1.406 (2)
N2—H2n	0.856 (9)	C12—H12c	0.96
N3—C6	1.3482 (18)	C13—C14	1.372 (2)
N3—C10	1.355 (2)	C13—H13c	0.96
N4—C11	1.356 (2)	C14—C15	1.404 (2)
N4—C15	1.3472 (17)	C14—H14c	0.96
N5—C15	1.383 (2)	C16—C17	1.4102 (19)
N5—C16	1.383 (2)	C17—C18	1.370 (2)
N5—H5n	0.863 (10)	C17—H17c	0.96
N6—C16	1.3452 (18)	C18—C19	1.398 (2)
N6—C20	1.360 (2)	C18—H18c	0.96
C1—C2	1.368 (3)	C19—C20	1.369 (2)
C1—H1c	0.96	C19—H19c	0.96
C2—C3	1.3948 (19)	C20—H20c	0.96
O2—Ni1—O3	60.56 (4)	N2—C6—N3	120.24 (12)
O2—Ni1—N1	88.90 (5)	N2—C6—C7	117.82 (13)
O2—Ni1—N3	161.41 (4)	N3—C6—C7	121.92 (16)
O2—Ni1—N4	85.69 (5)	C6—C7—C8	119.04 (14)
O2—Ni1—N6	99.36 (4)	C6—C7—H7c	120.479
O3—Ni1—N1	85.18 (5)	C8—C7—H7c	120.4811
O3—Ni1—N3	100.93 (4)	C7—C8—C9	119.41 (13)
O3—Ni1—N4	88.65 (5)	C7—C8—H8c	120.2964
O3—Ni1—N6	159.86 (4)	C9—C8—H8c	120.2955
N1—Ni1—N3	87.69 (5)	C8—C9—C10	118.21 (17)
N1—Ni1—N4	173.26 (5)	C8—C9—H9c	120.8937
N1—Ni1—N6	96.68 (5)	C10—C9—H9c	120.893
N3—Ni1—N4	96.17 (5)	N3—C10—C9	123.88 (14)
N3—Ni1—N6	99.18 (5)	N3—C10—H10c	118.0607
N4—Ni1—N6	88.18 (5)	C9—C10—H10c	118.0617
C1—N1—C5	117.30 (15)	N4—C11—C12	124.25 (13)
C5—N2—C6	128.95 (12)	N4—C11—H11c	117.8732
C5—N2—H2n	114.0 (11)	C12—C11—H11c	117.8728
C6—N2—H2n	111.7 (11)	C11—C12—C13	117.99 (14)
C6—N3—C10	117.47 (12)	C11—C12—H12c	121.0064
C11—N4—C15	117.27 (15)	C13—C12—H12c	121.0065
C15—N5—C16	130.50 (11)	C12—C13—C14	119.12 (17)
C15—N5—H5n	115.5 (12)	C12—C13—H13c	120.4373
C16—N5—H5n	112.7 (11)	C14—C13—H13c	120.4377
C16—N6—C20	117.54 (12)	C13—C14—C15	119.25 (13)
O1—N7—O2	122.07 (12)	C13—C14—H14c	120.3756
O1—N7—O3	122.21 (12)	C15—C14—H14c	120.3753
O2—N7—O3	115.72 (12)	N4—C15—N5	120.20 (15)
O4—N8—O5	121.15 (13)	N4—C15—C14	122.11 (13)
O4—N8—O6	121.01 (15)	N5—C15—C14	117.68 (12)
O5—N8—O6	117.84 (15)	N5—C16—N6	120.62 (12)
N1—C1—C2	123.57 (12)	N5—C16—C17	117.81 (12)
N1—C1—H1c	118.2142	N6—C16—C17	121.58 (15)
C2—C1—H1c	118.2148	C16—C17—C18	119.07 (13)
C1—C2—C3	118.61 (15)	C16—C17—H17c	120.4646
C1—C2—H2c	120.6954	C18—C17—H17c	120.4633
C3—C2—H2c	120.6956	C17—C18—C19	119.75 (13)
C2—C3—C4	119.01 (17)	C17—C18—H18c	120.1245
C2—C3—H3c	120.4967	C19—C18—H18c	120.1242
C4—C3—H3c	120.4966	C18—C19—C20	117.77 (15)
C3—C4—C5	119.12 (13)	C18—C19—H19c	121.1122
C3—C4—H4c	120.4375	C20—C19—H19c	121.1129
C5—C4—H4c	120.4396	N6—C20—C19	123.97 (13)
N1—C5—N2	120.04 (15)	N6—C20—H20c	118.0164
N1—C5—C4	122.12 (14)	C19—C20—H20c	118.0161
N2—C5—C4	117.84 (12)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2n···O6	0.856 (13)	1.959 (13)	2.8046 (19)	169.4 (14)
N5—H5n···O5^i	0.863 (14)	1.898 (14)	2.7442 (18)	166.3 (14)
C4—H4c···O6	0.96	2.53	3.2550 (19)	133
C9—H9c···O1^ii	0.96	2.48	3.325 (2)	147
C17—H17c···O5^i	0.96	2.50	3.228 (2)	133
C12—H12c···Cg(N6)^ii	0.96	2.99	3.7871 (17)	141

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