Hexa­aquanickel(II) di­sulfato(1,4,8,11-tetra­aza­cyclo­tetra­decane)nickelate(II) dihydrate

The title compound, [Ni(H₂O)₆][Ni(SO₄)₂(C₁₀H₂₄N₄)]·2H₂O, is an unusual compound in that it is composed of a hexa­aqua complex, formally a dication, and a mixed-donor complex (four N and two O atoms), formally a dianion, with substantial charge separation between the two nickel centres (6.536 Å). The homoleptic dication complex consists of the weaker-field ligands, whilst the dianion retains the coordination of all the higher-field donors. Both nickel ions are located at centres of symmetry. This rare compound is placed in the context of previously reported structures which emphasizes its peculiarity.

S1. Comment

Macrocyclic complexes of transition metals are a common sight in the coordination chemistry landscape, providing as they do useful chemical differences from related non-cyclic chelates. The versatile and useful ligand cyclam (1,4,8,11-tetraazacyclotetradecane) has received extensive study thanks to its employment with many different metals and across a range of applications including enzyme modelling, metal ion extraction, medicine and a broad range of catalysis. Reflecting such interest, at the time of writing, there are 374 cyclam structures and 1694 cyclam derivatives [with a cyclam backbone, but additional functional groups (including further cyclam units) attached at any point on the ring] in the Cambridge Structural Database (CSD; Allen, 2002; updates to November 2009). Of these, 514 contain Ni.

The structure reported here, (I), however, is notably distinct from the plethora of reported structures thanks to the presence of two nickel centres in considerably different chemical environments; one (Ni1) is coordinated by a tetraaza macrocycle and two trans sulfate groups, and the second (Ni2) is found in a homoleptic hexaaqua environment. What makes this complex remarkable is the substantial charge separation between two quite distant Ni centres: while Ni2 attaches only weak field water ligands, the Ni1 atom retains the coordination of the higher field strength cyclam as well as both the dianionic SO₄^2- groups.

A look at the proton affinity of the ligands, a useful proxy for sigma donor ability (Senn et al., 2000), emphasizes the curiosity of this arrangement. Water has a proton affinity of 691 kJ mol^-1 (Hunter & Lias, 2010) and whilst we do not have an exact value for the E_PA of cyclam, related amine compounds all have values between 900 and 1000 kJ mol^-1 (Hunter & Lias, 2010). The sulfate anion has a proton affinity above 1800 kJ mol^-1 (House & Kemper, 1987). It would seem reasonable that a balanced distribution of the available ligand-donated electron density across each Ni^II centre would provide for stabilization of both, but rather we see the weaker σ-donor ligands (the six water ligands) coordinate to one Ni while the more powerful donors congregate on the other. This leaves the former complex with an overall charge of 2+, and the latter with 2-, giving the coordination compound [Ni(H₂O)₆]²⁺[Ni(cyclam)(SO₄)₂]^2- (plus the two waters of crystallization).

The Ni1—N distances [2.071 (1), 2.077 (1) Å] of the cyclam complex show the typical strong bonds of high-spin Ni^II(cyclam) complexes (Donnelly & Zimmer, 1999), whilst the flexibility of the ring structure allows the Ni1 to sit in the centre (planar by symmetry) of four N atoms. The cyclam ring is in the lowest energy configuration, trans type III (according to the scheme of Bosnich et al., 1965), which is also the most common (Donnelly & Zimmer, 1999). The Ni1—O distance [2.152 (1) Å] involving the sulfate ligands are longer than those found in anhydrous NiSO₄ (2.020–2.118 Å, Wildner, 1990), whose range is also representative for such bonds in organometallic complexes, though longer examples are occasionally found {e.g. [N-(3-aminopropyl)-1,3-propanediamine]-diaqua-(sulfato-O)-nickel(II) monohydrate, Ni—OSO3 2.171 (2) Å, Mukherjee et al. 1995}. In the hexaaqua subunit, the Ni2—O distances range from 2.046 (1) to 2.084 (1) Å, agreeing very closely with those found in the hexaaqua complex of [Ni(H₂O)₆]SO₄ (2.0096–2.0852 Å, Rousseau et al., 2000).

There is substantial hydrogen bonding within the crystal structure. The strongest instances are found between the water H atoms and the terminal O atoms of the SO₄^2- ligands (O2, O3 and O4), such that altogether each SO₄^2- ligand is stabilized by six strong hydrogen bonds [distances in the range 1.91 (2)–2.08 (2) Å]. Two of these hydrogen bonds arise from the water solvent molecules, and four from the Ni-complexed waters. The SO₄^2- groups are further stabilized by weaker hydrogen bonding between the amine H atoms of cyclam (H5 and H10) and O2 and O4, respectively [2.377 (17) and 2.229 (18) Å]. The orientation of the SO₄^2- ligands is noticeably influenced by these latter hydrogen bonds, with the S1—O2 and S1—O4 bonds being almost parallel to the plane of the four N atoms, increasing their proximity to H5 and H10, whilst S1—O3 is substantially angled away. The appreciable stabilization afforded by these hydrogen bonds likely enables the formation of the formally ionic 2+/2- complexes, as due to the considerable Ni1···Ni2 distance (the shortest Ni1···Ni2 distance is 6.536 Å, found between adjacent asymmetric units), we infer the Madelung energy must be small.

A search of the CSD returns 15 structures where one Ni is coordinated to cyclam or a derivative, whilst another Ni has no bonds to any form of cyclam. Seven of these involve the second Ni atom in the low-spin environment of four cyano ligands. Another five of these structures have the second Ni bound by four S atoms in a square-planar fashion, and the remaining three structures have mixed N/O donors. None show the second Ni bound by six O donors, as in the compound presented here. Additionally, nine of the 15 structures show molecular crystals, as here, and six one-dimensional chains.

Searching for structures containing any transition metals where one metal atom is coordinated to six water molecules, while a second metal atom (of the same element as the first) is attached at least to four N atoms, returns 22 structures. Eleven of these are disregarded as they do not have a metal centre with the interesting mixed-donor functionality of (I) (i.e. four N plus a different donor atom bound to the same metal). Another five are simply aquated [M(phen)₂] complexes together with an additional hexaaqua complex of the same metal {i.e. [M(phen)₂(H₂O)₂][M(H₂O)₆], M = Mn, Co, Ni, Zn; phen = 1,10-phenanthroline} and of little interest. Another structure is discounted here due to its complexity – its unit cell contains 13 Co atoms, 12 of which are bound by a single mixed N/O donor macromolecule. Four of the remaining five of the 22 structures have metal centres with four N donors and two O donors, but all of the O donor ligands are chelates with N and O functionality. The most interesting of these {hexaaqua-nickel(II) (1,4,7,10-tetrakis(methylenephosphonic acid)-1,4,7,10-tetraazacyclododecane-N,N',N'',N''',O,O'')-nickel(II) [CSD refcode: SAHPOH (Kong et al., 2004)]} is discussed below, along with the final structure from this search {hexaaquacobalt(II) bis[dibromobis(ethanedial dioximato)cobaltate(III)] acetone solvate [CSD refcode: BIYTUY (Egharevba et al., 1982)]}, which does bear some similarity to the title compound.

SAHPOH (see Fig. 2) is a bi-Ni compound with a striking superficial similarity to (I). It has a directly analogous hexaaqua metal centre and a similar (albeit with cis rather than trans geometry) [12]aneN₄ ring derivatized with N-pendant methylenephosphonate groups, where two phosphonate groups act as O donors corresponding to the sulfate groups of (I). However, the crucial difference between (I) and this compound is the hexadentate nature of the single, mixed-donor ligand. This tethering of the phosphonates to the [12]aneN₄ ring gives them considerably greater tendency to coordinate to the same Ni as [12]aneN₄ than to another metal centre by cause of the chelate effect. This is an important difference from (I), where the free sulfate groups may readily coordinate to a non-cyclam connected metal centre but don't.

BIYTUY (see Fig. 3) is a tri-Co compound akin to (I) in having two distinct metal environments: a hexaaqua metal complex and a dibromo-bis(glyoximato)Co. Besides the change in metal, there are, however, three significant differences from (I). The first is that each individual ligand bears a single negative charge, for a total ligand charge of 4-, where the title compound bears this 4- charge (formally) on just the two SO₄^2- ligands. More significantly, the ratio of the two different Co complexes is 1:2, requiring a Co^III complex, [Co(Br)₂(gH^-)₂]^- (gH^- = glyoximato), to ensure charge neutrality. This triply charged metal centre is naturally more attractive to Br^- ligands than a doubly charged centre would be with the same bis-glyoximato ligands. Finally, the C═N functionality of the glyoximato ligands is capable of much stronger π-interactions with the transition metal than the secondary amines of (I).

A search of the type [TM(O)₆][TM(N)₄(SO)₂], i.e any transition metal (TM) compound such that one TM is bound to six O and another TM of the same element is bound to four N donors and two O—S groups (O donor, with S free to have any other connections), returned no results. Placed in the context of previously reported structures, this confirms that the title compound is an intriguing and rare structure for transition metal complexes.

Related literature

For related literature, see: Allen (2002); Bosnich et al. (1965); Churchard et al. (2010); Donnelly & Zimmer (1999); Egharevba et al. (1982); House & Kemper (1987); Hunter & Lias (2010); Kong et al. (2004); Mukherjee et al. (1995); Oxford Diffraction (2004); Rousseau et al. (2000); Senn et al. (2000); Sheldrick (1990, 2008); Wildner (1990).

S2. Experimental

Crystals of (I) were obtained as a by-product during synthesis of Ni(cyclam)(SO₄) (Churchard et al., 2010). Prolonged exposure (several days) to atmospheric water resulted in hydration of the anhydrous solution and precipitation of violet crystals of (I).

The X-ray measurement of (I) was performed at 100 (2) K on a Kuma CCD k-axis diffractometer with graphite-monochromated Mo Kα radiation (0.71073 Å). The crystal was positioned at 62.25 mm from the KM4 CCD camera; 1600 frames were measured at 0.75° intervals on a counting time of 20 s. Data reduction and analysis were carried out with the Kuma Diffraction programs. The data were corrected for Lorentz and polarization effects and multi-scan absorption correction (Oxford Diffraction, 2004) was applied.

S3. Refinement

The structure was solved by direct methods (Sheldrick, 1990) and refined using SHELXL (Sheldrick, 2008). The refinement was based on F² for all reflections except those with very negative F². The weighted R factor, wR and all goodness-of-fit S values are based on F². Non-H atoms were refined anisotropically. The H atoms, except at carbons, were located from difference maps and their positions refined isotropically. Other H atoms were placed in calculated positions and refined within the riding model.

Computing details

Data collection: CrysAlis CCD? (Oxford Diffraction, 2004); cell refinement: CrysAlis CCD? (Oxford Diffraction, 2004); data reduction: CrysAlis RED? (Oxford Diffraction, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); software used to prepare material for publication: Mercury (CCDC, 2009).

Figures

Fig. 1. Thermal elipsoid (50% probability) representation of the crystal structure of [Ni(H2O)6][Ni(cyclam)(SO4)2].2(H2O). H atoms have been omitted for clarity. The second water of crystallization arises from symmetry and is not shown here. Fig. 2. Schematic diagram of hexaaqua-nickel(II) [1,4,7,10-tetrakis(methylenephosphonic acid)-1,4,7,10-tetraazacyclododecane-N,N',N'',N''', O,O'']nickel(II) (CSD refcode: SAHPOH). Fig. 3. Schematic diagram of hexaaquacobalt(II) bis[dibromobis(ethanedial dioximato)cobaltate(III)] acetone solvate (CSD refcode: BIYTUY).

hexaaqua nickel(II) bissulfato-1,4,8,11-tetraazacyclotetradecane nickelate(II) dihydrate

Crystal data

[Ni(H2O)6][Ni(C10H24N4)(SO4)2]·2H2O	Z = 1
Mr = 654.00	F(000) = 344
Triclinic, P1	Dx = 1.747 Mg m^−3
Hall symbol: -P1	Mo Kα radiation, λ = 0.71073 Å
a = 8.0997 (7) Å	Cell parameters from 11856 reflections
b = 8.4360 (6) Å	θ = 2.6–28.7°
c = 9.3521 (9) Å	µ = 1.76 mm^−1
α = 98.558 (7)°	T = 100 K
β = 99.869 (8)°	Prism, violet
γ = 91.640 (7)°	0.10 × 0.10 × 0.05 mm
V = 621.59 (9) Å^3

Data collection

KM4 CCD diffractometer	2438 independent reflections
Radiation source: fine-focus sealed tube	2010 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
Detector resolution: 8.6479 pixels mm^-1	θmax = 26.0°, θmin = 2.6°
ω scan	h = −9→9
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2004) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm.	k = −10→10
Tmin = 0.844, Tmax = 0.917	l = −11→11
10420 measured 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)] = 0.018	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.040	H atoms treated by a mixture of independent and constrained refinement
S = 0.95	w = 1/[σ^2(Fo^2) + (0.0226P)^2] where P = (Fo^2 + 2Fc^2)/3
2438 reflections	(Δ/σ)max = 0.001
197 parameters	Δρmax = 0.29 e Å^−3
0 restraints	Δρmin = −0.40 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
Ni1	0.5000	0.0000	1.0000	0.00818 (8)
C1	0.2882 (2)	−0.34975 (19)	0.99669 (18)	0.0148 (4)
H1	0.3277	−0.3965	0.9059	0.018*
H2	0.2165	−0.4335	1.0237	0.018*
C2	0.1810 (2)	−0.20956 (19)	0.96344 (18)	0.0132 (4)
H3	0.0737	−0.2515	0.8994	0.016*
H4	0.1548	−0.1519	1.0563	0.016*
N1	0.26664 (16)	−0.09575 (16)	0.89008 (15)	0.0105 (3)
H5	0.281 (2)	−0.1458 (19)	0.8097 (18)	0.006 (4)*
C3	0.1678 (2)	0.04473 (19)	0.86267 (18)	0.0141 (4)
H6	0.1303	0.0933	0.9539	0.017*
H7	0.0671	0.0108	0.7866	0.017*
C4	0.2764 (2)	0.1666 (2)	0.81139 (18)	0.0141 (4)
H8	0.3106	0.1196	0.7182	0.017*
H9	0.2129	0.2626	0.7942	0.017*
N2	0.42708 (16)	0.21232 (16)	0.92743 (15)	0.0104 (3)
H10	0.393 (2)	0.272 (2)	1.001 (2)	0.015 (5)*
C5	0.5596 (2)	0.30776 (19)	0.88088 (18)	0.0140 (4)
H11	0.5132	0.4079	0.8520	0.017*
H12	0.5952	0.2457	0.7940	0.017*
S1	0.38514 (5)	0.21040 (4)	1.29292 (4)	0.00874 (9)
O1	0.38881 (13)	0.05881 (12)	1.19301 (11)	0.0115 (2)
O2	0.55895 (14)	0.26745 (13)	1.36342 (12)	0.0156 (3)
O3	0.29068 (13)	0.17836 (12)	1.41034 (12)	0.0116 (2)
O4	0.30358 (14)	0.33280 (13)	1.21356 (12)	0.0145 (3)
Ni2	0.0000	0.5000	0.5000	0.00769 (8)
O5	−0.02778 (16)	0.26257 (14)	0.40958 (13)	0.0112 (2)
H13	−0.079 (3)	0.209 (2)	0.451 (2)	0.027 (6)*
H14	0.062 (3)	0.230 (2)	0.402 (2)	0.019 (6)*
O6	0.24230 (15)	0.46317 (16)	0.59750 (13)	0.0118 (3)
H15	0.309 (3)	0.534 (3)	0.614 (2)	0.037 (7)*
H16	0.282 (2)	0.386 (2)	0.559 (2)	0.024 (6)*
O7	0.08639 (15)	0.54930 (16)	0.31296 (13)	0.0123 (3)
H17	0.148 (3)	0.492 (3)	0.285 (2)	0.037 (7)*
H18	0.134 (3)	0.644 (3)	0.326 (2)	0.041 (7)*
O8	0.76830 (16)	0.14365 (17)	0.57093 (15)	0.0168 (3)
H19	0.752 (2)	0.062 (3)	0.584 (2)	0.022 (6)*
H20	0.686 (3)	0.170 (3)	0.515 (2)	0.042 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.00835 (15)	0.00736 (15)	0.00930 (16)	0.00155 (11)	0.00294 (12)	0.00101 (11)
C1	0.0174 (9)	0.0105 (8)	0.0178 (9)	−0.0019 (7)	0.0085 (7)	0.0007 (7)
C2	0.0100 (8)	0.0147 (9)	0.0147 (9)	−0.0018 (7)	0.0039 (7)	0.0006 (7)
N1	0.0121 (7)	0.0096 (7)	0.0102 (7)	0.0031 (6)	0.0046 (6)	−0.0006 (6)
C3	0.0107 (9)	0.0154 (9)	0.0148 (9)	0.0030 (7)	0.0010 (7)	−0.0008 (7)
C4	0.0155 (9)	0.0141 (8)	0.0124 (9)	0.0049 (7)	0.0006 (7)	0.0028 (7)
N2	0.0119 (7)	0.0109 (7)	0.0091 (7)	0.0019 (6)	0.0040 (6)	0.0008 (6)
C5	0.0172 (9)	0.0110 (8)	0.0168 (9)	0.0027 (7)	0.0084 (7)	0.0055 (7)
S1	0.0092 (2)	0.00722 (19)	0.0103 (2)	0.00068 (15)	0.00381 (16)	0.00073 (15)
O1	0.0143 (6)	0.0088 (6)	0.0119 (6)	0.0010 (4)	0.0056 (5)	−0.0003 (4)
O2	0.0119 (6)	0.0142 (6)	0.0196 (7)	−0.0039 (5)	0.0020 (5)	0.0007 (5)
O3	0.0130 (6)	0.0112 (6)	0.0122 (6)	0.0022 (4)	0.0067 (5)	0.0021 (5)
O4	0.0205 (7)	0.0120 (6)	0.0140 (6)	0.0072 (5)	0.0074 (5)	0.0050 (5)
Ni2	0.00784 (15)	0.00657 (15)	0.00892 (16)	0.00040 (11)	0.00279 (12)	0.00058 (11)
O5	0.0102 (7)	0.0086 (6)	0.0154 (6)	−0.0004 (5)	0.0058 (5)	0.0004 (5)
O6	0.0107 (6)	0.0091 (6)	0.0152 (7)	0.0009 (5)	0.0033 (5)	−0.0006 (5)
O7	0.0142 (6)	0.0107 (7)	0.0136 (6)	0.0020 (5)	0.0068 (5)	0.0014 (5)
O8	0.0176 (7)	0.0117 (7)	0.0227 (7)	−0.0013 (6)	0.0045 (6)	0.0073 (6)

Geometric parameters (Å, º)

Ni1—N1	2.0691 (13)	C5—H12	0.9900
Ni1—N2	2.0743 (13)	S1—O4	1.4671 (11)
Ni1—O1	2.1522 (10)	S1—O4	1.4671 (11)
C1—C2	1.525 (2)	S1—O1	1.4715 (11)
C1—C5^i	1.525 (2)	S1—O2	1.4822 (12)
C1—H1	0.9900	S1—O3	1.4930 (11)
C1—H2	0.9900	O1—S1	1.4715 (11)
C2—N1	1.481 (2)	O2—S1	1.4822 (12)
C2—H3	0.9900	O3—S1	1.4930 (11)
C2—H4	0.9900	O4—S1	1.4671 (11)
N1—C3	1.478 (2)	Ni2—O5	2.0451 (11)
N1—H5	0.834 (16)	Ni2—O6	2.0701 (12)
C3—C4	1.517 (2)	Ni2—O7	2.0837 (12)
C3—H6	0.9900	O5—H13	0.79 (2)
C3—H7	0.9900	O5—H14	0.79 (2)
C4—N2	1.487 (2)	O6—H15	0.77 (2)
C4—H8	0.9900	O6—H16	0.80 (2)
C4—H9	0.9900	O7—H17	0.76 (2)
N2—C5	1.485 (2)	O7—H18	0.86 (2)
N2—H10	0.875 (18)	O8—H19	0.73 (2)
C5—H11	0.9900	O8—H20	0.83 (2)
N1—Ni1—N1^i	180.00 (4)	C4—N2—Ni1	105.45 (9)
N1—Ni1—N2	85.74 (5)	C5—N2—H10	107.8 (11)
N1^i—Ni1—N2	94.26 (5)	C4—N2—H10	106.6 (11)
N1—Ni1—N2^i	94.26 (5)	Ni1—N2—H10	106.8 (11)
N1^i—Ni1—N2^i	85.74 (5)	N2—C5—C1^i	111.71 (13)
N2—Ni1—N2^i	180.0	N2—C5—H11	109.3
N1—Ni1—O1	87.80 (5)	C1^i—C5—H11	109.3
N1^i—Ni1—O1	92.20 (5)	N2—C5—H12	109.3
N2—Ni1—O1	91.32 (5)	C1^i—C5—H12	109.3
N2^i—Ni1—O1	88.68 (5)	H11—C5—H12	107.9
N1—Ni1—O1^i	92.20 (5)	O4—S1—O1	110.93 (6)
N1^i—Ni1—O1^i	87.80 (5)	O4—S1—O1	110.93 (6)
N2—Ni1—O1^i	88.68 (5)	O4—S1—O2	110.16 (7)
N2^i—Ni1—O1^i	91.32 (5)	O4—S1—O2	110.16 (7)
O1—Ni1—O1^i	180.0	O1—S1—O2	109.39 (6)
C2—C1—C5^i	115.17 (13)	O4—S1—O3	109.82 (6)
C2—C1—H1	108.5	O4—S1—O3	109.82 (6)
C5^i—C1—H1	108.5	O1—S1—O3	108.24 (6)
C2—C1—H2	108.5	O2—S1—O3	108.23 (7)
C5^i—C1—H2	108.5	S1—O1—Ni1	132.07 (6)
H1—C1—H2	107.5	S1—O1—Ni1	132.07 (6)
N1—C2—C1	112.04 (13)	O5^ii—Ni2—O5	180.00 (3)
N1—C2—H3	109.2	O5^ii—Ni2—O6^ii	89.02 (5)
C1—C2—H3	109.2	O5—Ni2—O6^ii	90.98 (5)
N1—C2—H4	109.2	O5^ii—Ni2—O6	90.98 (5)
C1—C2—H4	109.2	O5—Ni2—O6	89.02 (5)
H3—C2—H4	107.9	O6^ii—Ni2—O6	180.0
C3—N1—C2	112.86 (12)	O5^ii—Ni2—O7	91.30 (5)
C3—N1—Ni1	105.00 (10)	O5—Ni2—O7	88.70 (5)
C2—N1—Ni1	116.10 (10)	O6^ii—Ni2—O7	89.65 (5)
C3—N1—H5	108.8 (11)	O6—Ni2—O7	90.35 (5)
C2—N1—H5	107.1 (11)	O5^ii—Ni2—O7^ii	88.70 (5)
Ni1—N1—H5	106.6 (11)	O5—Ni2—O7^ii	91.30 (5)
N1—C3—C4	108.92 (13)	O6^ii—Ni2—O7^ii	90.35 (5)
N1—C3—H6	109.9	O6—Ni2—O7^ii	89.65 (5)
C4—C3—H6	109.9	O7—Ni2—O7^ii	180.000 (1)
N1—C3—H7	109.9	Ni2—O5—H13	114.2 (14)
C4—C3—H7	109.9	Ni2—O5—H14	109.2 (14)
H6—C3—H7	108.3	H13—O5—H14	112 (2)
N2—C4—C3	108.14 (13)	Ni2—O6—H15	118.8 (16)
N2—C4—H8	110.1	Ni2—O6—H16	114.5 (14)
C3—C4—H8	110.1	H15—O6—H16	108 (2)
N2—C4—H9	110.1	Ni2—O7—H17	115.5 (17)
C3—C4—H9	110.1	Ni2—O7—H18	112.0 (14)
H8—C4—H9	108.4	H17—O7—H18	106 (2)
C5—N2—C4	113.90 (12)	H19—O8—H20	109 (2)
C5—N2—Ni1	115.79 (10)
C5^i—C1—C2—N1	71.22 (17)	S1—S1—O1—Ni1	0.00 (14)
C1—C2—N1—C3	−177.52 (13)	O4—S1—O1—Ni1	60.29 (10)
C1—C2—N1—Ni1	−56.23 (15)	O4—S1—O1—Ni1	60.29 (10)
N2—Ni1—N1—C3	−15.92 (10)	O2—S1—O1—Ni1	−61.44 (10)
N2^i—Ni1—N1—C3	164.08 (10)	O3—S1—O1—Ni1	−179.16 (8)
O1—Ni1—N1—C3	75.57 (10)	N1—Ni1—O1—S1	−126.45 (9)
O1^i—Ni1—N1—C3	−104.43 (10)	N2—Ni1—O1—S1	−40.77 (9)
N2—Ni1—N1—C2	−141.32 (11)	N2^i—Ni1—O1—S1	139.23 (9)
N2^i—Ni1—N1—C2	38.68 (11)	N1—Ni1—O1—S1	−126.45 (9)
O1—Ni1—N1—C2	−49.83 (11)	N1^i—Ni1—O1—S1	53.55 (9)
O1^i—Ni1—N1—C2	130.17 (11)	N2—Ni1—O1—S1	−40.77 (9)
C2—N1—C3—C4	170.65 (13)	N2^i—Ni1—O1—S1	139.23 (9)
Ni1—N1—C3—C4	43.25 (14)	O4—S1—O2—S1	0.0 (11)
N1—C3—C4—N2	−58.68 (16)	O4—S1—O2—S1	0.0 (11)
C3—C4—N2—C5	169.31 (13)	O1—S1—O2—S1	0 (100)
C3—C4—N2—Ni1	41.27 (14)	O3—S1—O2—S1	0 (100)
N1—Ni1—N2—C5	−141.00 (11)	O4—S1—O3—S1	0 (76)
O1—Ni1—N2—C5	131.31 (11)	O4—S1—O3—S1	0 (76)
O1^i—Ni1—N2—C5	−48.69 (11)	O1—S1—O3—S1	0 (100)
N1—Ni1—N2—C4	−14.11 (10)	O2—S1—O3—S1	0 (27)
O1—Ni1—N2—C4	−101.80 (10)	S1—S1—O4—O4	0.0
O1^i—Ni1—N2—C4	78.20 (10)	O1—S1—O4—O4	0.0 (4)
C4—N2—C5—C1^i	−179.38 (13)	O2—S1—O4—O4	0.0 (4)
Ni1—N2—C5—C1^i	−56.86 (15)	O3—S1—O4—O4	0.0 (4)
O4—S1—O1—S1	0 (75)	O4—S1—O4—S1	0 (100)
O4—S1—O1—S1	0 (75)	O1—S1—O4—S1	0 (100)
O2—S1—O1—S1	0 (26)	O2—S1—O4—S1	0.0 (7)
O3—S1—O1—S1	0 (100)	O3—S1—O4—S1	0 (99)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H5···O2^i	0.834 (16)	2.377 (17)	3.1555 (18)	155.6 (14)
N2—H10···O4	0.875 (18)	2.229 (18)	3.0594 (17)	158.4 (15)
N2—H10···S1	0.875 (18)	2.868 (18)	3.4947 (14)	129.9 (14)
O5—H13···O8^iii	0.79 (2)	1.93 (2)	2.6873 (19)	162 (2)
O5—H14···O3^iv	0.79 (2)	1.91 (2)	2.6941 (17)	170.7 (19)
O6—H15···O2^v	0.77 (2)	1.93 (2)	2.6891 (18)	169 (2)
O6—H16···O3^iv	0.80 (2)	2.08 (2)	2.8332 (17)	157.4 (19)
O7—H17···O4^iv	0.76 (2)	1.99 (2)	2.7448 (17)	177 (2)
O7—H18···O8^vi	0.86 (2)	1.98 (2)	2.7972 (19)	159 (2)
O8—H19···O3^i	0.73 (2)	2.06 (2)	2.7811 (18)	172 (2)
O8—H20···O2^iv	0.83 (2)	1.91 (2)	2.7035 (19)	160 (2)

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