{3,3′-[2,2′-(Ethylenedioxy)dibenzyl­idene]bis(S-methyl dithiocarbazate)}­nickel(II)

The tetradentate N₂S₂ Schiff base ligand 3,3′-[2,2′-(ethyl­ene­di­oxy)di­benzyl­idene]­bis­(S-methyl di­thio­car­ba­zate) (H₂L), prepared by the condensation of S-methyl di­thio­carb­aza­te with 1,4-bis(2-formyl­phenyl)-1,4-dioxa­butane in a 1:2 molar ratio, reacts with nickel acetate to form the title neutral metal complex, [Ni(C₂₀H₂₀N₄O₂S₄)]. The X-ray structure of the complex shows a distorted square-planar geometry around the Ni atom. The monomeric units are weakly associated into dimers via a long Ni...S interaction [3.569 (1) Å]. These dimeric units are then linked by C—H...S intermolecular contacts to form a polymeric chain along the a axis.

S1. Comment

The Schiff-base compounds derived from S-alkyl dithiocarbazate are of interest due to their pronounced biological activity against bacteria, viruses and cancer (Davies et al., 1990; Kirschner et al., 1966), and have stimulated interest in their coordination chemistry. In past years there has been much work devoted to the synthesis and characterization of quadridentate sulfur-nitrogen ligands. As part of our continuing study of new chelating ligands containing mixed NS donors (Tian et al., 1996, 1998), the synthesis and crystal structure of the title nickel(II) complex, (I), derived from a new N₂S₂ quadridentate Schiff-base ligand, are now described. \sch

As shown in Fig. 1, the coordination system in (I) is a distorted square planar configuration (Table 1), the non-planarity being shown by S1 and N3 displaced on one side of the weighted least-squares plane through Ni by 0.052 (1) and 0.362 (2) Å, respectively, while S3 and N1 are displaced on the other side by 0.041 (1) and 0.364 (2) Å, respectively. The ligand part of the molecule deviates slightly from planarity, with a dihedral angle of 11.16 (15)° between the phenyl rings. The twist is introduced by the –OCH₂CH₂O– bridge. The molecular conformation has been influenced by C—H···N intramolecular hydrogen bonds (Table 2). The Schiff-base ligand H₂L is doubly deprotonated, thus acting as a double negatively-charged quadridentate NNSS chelate, coordinated to the Ni atom via both azomethine atoms N1 and N3, and thiolato atoms S1 and S3. The Ni—N and Ni—S bond lengths compare well with those found in other related nickel(II) Schiff-base complexes (Tian et al., 1996, 1998). The bond lengths of C1—S1 and C3—S3 indicate single bonds, whereas those of C1—N2 and N4—C3 indicate double bonds, compared with those in the free ligand S-methyl-N-[4-(dimethylamino)benzylidene]dithiocarbazate (Zhao et al., 1997), where the single C—N bond is 1.333 (5) Å and the double C—S bond is 1.663 (4) Å.

Unlike ML₂ [where M is Ni^II and HL is an NS bidentate Schiff base derived from S-methyl dithiocarbazate; Fun et al., 1996], in the case of (I), atoms N1, N3, S1 and S3 are coordinated to the Ni atom in a cis-fashion, since the two bulky dithiocarbazate groups are preorganized, bridged by the –OCH₂CH₂O– group. When coordinated in this manner, the molecule of (I) is so congested that the two dithiocarbazate groups are not completely equivalent and a centrosymmetric packing is adopted to reduce the steric hindrance in the unit cell. The ligand forms three puckered chelation rings about the Ni atom, two of five members and one of thirteen. The first two are not equal in their total puckering amplitude, Q_T (Cremer & Pople, 1975) being 0.271 (1) and 0.168 (1) Å for the (Ni/S1/C1/N2/N1) and (Ni/S3/C3/N4/N3) rings, respectively, while Q_T is 0.956 (2) Å for the thirteen-member (N1/C5···C20/N3) ring. In this last ring there is a local pseudo twofold axis running between Ni and the midpoint of the C12—C13 bond, the ring distortion being mainly caused by steric hindrance [O1···O2 2.605 (2), C5···C20 3.232 (3), H5A···H20A 2.39 and N1···N3 2.925 (2) Å]. The conformation of the (Ni/S1/C1/N2/N1) ring is such as to have two local pseudo twofold axes, one running between atom N2 and the midpoint of the Ni—S1 bond, the other between atom C1 and the midpoint of the Ni—N1 bond, while in the (Ni/S3/C3/N4/N3) ring there is a local pseudo mirror between N1 and the mid point of C3—N4.

The two methyl groups, S2—C2 and S4—C4, are trans with respect to the S1—C1 and S3—C3 bonds, as defined by the S1—C1—S2—C2 [179.3 (2)°] and S3—C3—S4—C4 [-177.2 (1)°] torsion angles. It should be noted that the Ni atom is weakly coordinated by the S atom from another molecule in the unit cell [Ni···S4ⁱ 3.569 (1) Å; symmetry code: (i) 2 - x, -y, -z], thus giving rise to a dimer. These dimeric units are connected by intermolecular contacts [S3···H13Bⁱⁱ 2.904 and S4···H13Bⁱⁱ 2.933 Å; symmetry code: (ii) 1 + x, y, z] to form a polymeric chain along the a axis (Fig. 2).

Related literature

For related literature, see: Akbar & Tarafdar (1977); Amstrong & Lindoy (1975); Cremer & Pople (1975); Davies et al. (1990); Fun et al. (1996); Kirschner et al. (1966); Tian et al. (1996, 1998); Zhao et al. (1997).

S2. Experimental

1,4-Bis(2'-formylphenyl)-1,4-dioxabutane (1.25 g; Amstrong & Lindoy, 1975) was dissolved in hot absolute ethanol (30 ml). A yellow precipitate was formed when a solution of S-methyl dithiocarbazate (1.22 g; Akbar Ali & Tarafdar, 1977) in absolute ethanol (30 ml) was added to this solution. The reaction mixture was stirred and refluxed for 3 h. After filtration the product, H₂L, was washed with hot ethanol. The ligand H₂L (0.36 g, 1 mmol) was suspended in ethanol (10 ml) in the presence of DMF (2 ml). To this suspension a solution of [Ni(CH₃COO)₂]·2H₂O (1 mmol) in ethanol (10 ml) was added dropwise under reflux and stirring. The reaction lasted until the yellow suspension completely disappeared and a deep-blue crystalline precipitate, (I), was formed instead. Filtration was carried out while the mixture was still hot and the product was then washed with hot ethanol. Single crystals of (I) suitable for X-ray analysis were obtained by slow evaporation from a dichloromethane solution at room temperature.

S3. Refinement

Please provide brief details of H-atom refinement

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 1997); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 1990).

Figures

	Fig. 1. The structure of compound (I) showing 50% probability displacement ellipsoids and the atom-numbering scheme. H atoms are drawn as small spheres of arbitrary radii.
	Fig. 2. The packing diagram of (I) viewed down the c axis, showing the polymeric structure of the dimeric units of (I) along the a axis.

3,3'-[2,2'-(ethylenedioxy)dibenzylidene]bis(S-methyl dithiocarbazate) nickel(II)

Crystal data

[Ni(C20H20N4O2S4)]	F(000) = 1104
Mr = 535.35	Dx = 1.542 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 11.1188 (1) Å	Cell parameters from 8192 reflections
b = 7.6413 (1) Å	θ = 2.8–33.2°
c = 27.4773 (1) Å	µ = 1.23 mm^−1
β = 99.065 (1)°	T = 293 K
V = 2305.37 (4) Å^3	Plate, dark blue
Z = 4	0.45 × 0.30 × 0.06 mm

Data collection

Siemens SMART CCD area-detector diffractometer	5277 independent reflections
Radiation source: fine-focus sealed tube	4356 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.028
Detector resolution: 8.33 pixels mm^-1	θmax = 27.5°, θmin = 2.8°
ω scans	h = −13→14
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996)	k = −9→8
Tmin = 0.608, Tmax = 0.930	l = −35→35
14690 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)] = 0.033	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.080	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.0296P)^2 + 0.9504P] where P = (Fo^2 + 2Fc^2)/3
5277 reflections	(Δ/σ)max = 0.001
280 parameters	Δρmax = 0.32 e Å^−3
0 restraints	Δρmin = −0.27 e Å^−3

Special details

Experimental. The data collection covered over a hemisphere of reciprocal space by a combination of three sets of exposures; each set had a different ϕ angle (0, 88 and 180°) for the crystal and each exposure of 10 s covered 0.3° in ω. The crystal-to-detector distance was 4 cm and the detector swing angle was -35°. Coverage of the unique set is over 99% complete. Crystal decay was monitored by repeating fifty initial frames at the end of data collection and analysing the duplicate reflections, and was found to be negligible.

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
Ni	0.92764 (2)	0.30981 (3)	0.072271 (9)	0.03105 (8)
S1	1.05349 (5)	0.40331 (8)	0.13519 (2)	0.04263 (14)
S2	0.98461 (7)	0.57090 (10)	0.22323 (2)	0.0642 (2)
S3	1.07421 (4)	0.28819 (7)	0.030241 (19)	0.03872 (13)
S4	1.06291 (5)	0.15698 (8)	−0.07070 (2)	0.04734 (14)
O1	0.49596 (14)	0.0823 (2)	0.08147 (6)	0.0519 (4)
O2	0.47201 (14)	0.2810 (2)	0.00352 (6)	0.0533 (4)
N1	0.81329 (15)	0.2859 (2)	0.11702 (6)	0.0353 (4)
N2	0.83086 (16)	0.3833 (2)	0.16142 (6)	0.0422 (4)
N3	0.82021 (14)	0.2800 (2)	0.01106 (6)	0.0314 (3)
N4	0.86589 (15)	0.2209 (2)	−0.03101 (6)	0.0341 (4)
C1	0.9409 (2)	0.4421 (3)	0.17080 (7)	0.0400 (5)
C2	0.8472 (3)	0.5839 (5)	0.24932 (11)	0.0863 (11)
H2A	0.8613	0.6530	0.2789	0.129*
H2B	0.8222	0.4683	0.2571	0.129*
H2C	0.7845	0.6374	0.2261	0.129*
C3	0.98389 (18)	0.2220 (2)	−0.02376 (7)	0.0334 (4)
C4	0.9436 (2)	0.1093 (3)	−0.12081 (9)	0.0521 (6)
H4A	0.9786	0.0717	−0.1489	0.078*
H4B	0.8956	0.2125	−0.1292	0.078*
H4C	0.8928	0.0180	−0.1112	0.078*
C5	0.72657 (18)	0.1716 (3)	0.11303 (7)	0.0376 (4)
H5A	0.7116	0.1124	0.0831	0.045*
C6	0.6488 (2)	0.1226 (3)	0.14899 (8)	0.0449 (5)
C7	0.6907 (3)	0.1089 (5)	0.19930 (10)	0.0776 (10)
H7A	0.7717	0.1337	0.2116	0.093*
C8	0.6133 (4)	0.0589 (7)	0.23085 (12)	0.1133 (16)
H8A	0.6425	0.0476	0.2643	0.136*
C9	0.4928 (4)	0.0254 (6)	0.21346 (13)	0.1058 (14)
H9A	0.4404	−0.0049	0.2354	0.127*
C10	0.4492 (3)	0.0364 (4)	0.16387 (12)	0.0751 (9)
H10A	0.3674	0.0147	0.1522	0.090*
C11	0.5276 (2)	0.0800 (3)	0.13136 (9)	0.0478 (5)
C12	0.37419 (19)	0.1280 (3)	0.06080 (10)	0.0504 (6)
H12A	0.3482	0.2313	0.0769	0.060*
H12B	0.3189	0.0327	0.0648	0.060*
C13	0.3751 (2)	0.1633 (3)	0.00712 (9)	0.0512 (6)
H13A	0.3870	0.0551	−0.0100	0.061*
H13B	0.2982	0.2143	−0.0078	0.061*
C14	0.50005 (19)	0.3223 (3)	−0.04156 (8)	0.0403 (5)
C15	0.4136 (2)	0.3458 (3)	−0.08321 (9)	0.0547 (6)
H15A	0.3318	0.3248	−0.0820	0.066*
C16	0.4497 (3)	0.4000 (4)	−0.12605 (10)	0.0664 (8)
H16A	0.3917	0.4173	−0.1539	0.080*
C17	0.5713 (3)	0.4296 (4)	−0.12848 (9)	0.0636 (7)
H17A	0.5944	0.4683	−0.1577	0.076*
C18	0.6585 (2)	0.4017 (3)	−0.08753 (8)	0.0468 (5)
H18A	0.7404	0.4188	−0.0896	0.056*
C19	0.62447 (18)	0.3483 (3)	−0.04325 (7)	0.0352 (4)
C20	0.70835 (17)	0.3324 (3)	0.00332 (7)	0.0328 (4)
H20A	0.6765	0.3647	0.0313	0.039*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni	0.02009 (12)	0.03720 (14)	0.03493 (14)	−0.00055 (10)	0.00146 (9)	−0.00050 (10)
S1	0.0279 (3)	0.0522 (3)	0.0450 (3)	−0.0071 (2)	−0.0030 (2)	−0.0022 (2)
S2	0.0607 (4)	0.0794 (5)	0.0483 (3)	−0.0177 (4)	−0.0044 (3)	−0.0223 (3)
S3	0.0210 (2)	0.0501 (3)	0.0450 (3)	−0.0004 (2)	0.0050 (2)	0.0001 (2)
S4	0.0354 (3)	0.0604 (4)	0.0492 (3)	0.0073 (3)	0.0158 (2)	−0.0039 (3)
O1	0.0271 (8)	0.0722 (11)	0.0572 (10)	−0.0038 (7)	0.0090 (7)	−0.0120 (8)
O2	0.0323 (8)	0.0760 (12)	0.0517 (9)	−0.0138 (8)	0.0072 (7)	−0.0170 (8)
N1	0.0260 (8)	0.0459 (10)	0.0331 (8)	−0.0023 (7)	0.0016 (7)	−0.0047 (7)
N2	0.0353 (10)	0.0550 (11)	0.0347 (9)	−0.0027 (8)	0.0009 (7)	−0.0114 (8)
N3	0.0230 (7)	0.0356 (9)	0.0359 (8)	0.0003 (6)	0.0054 (6)	−0.0022 (7)
N4	0.0256 (8)	0.0399 (9)	0.0376 (9)	0.0030 (7)	0.0072 (7)	−0.0032 (7)
C1	0.0373 (11)	0.0451 (12)	0.0347 (10)	−0.0023 (9)	−0.0036 (9)	−0.0028 (9)
C2	0.080 (2)	0.119 (3)	0.0602 (18)	−0.008 (2)	0.0116 (16)	−0.0403 (18)
C3	0.0298 (10)	0.0319 (10)	0.0395 (10)	0.0038 (8)	0.0086 (8)	0.0026 (8)
C4	0.0594 (16)	0.0522 (14)	0.0448 (12)	0.0062 (12)	0.0087 (11)	−0.0034 (10)
C5	0.0278 (10)	0.0485 (12)	0.0362 (10)	−0.0028 (9)	0.0037 (8)	−0.0030 (9)
C6	0.0372 (12)	0.0562 (13)	0.0432 (12)	−0.0073 (10)	0.0119 (9)	−0.0018 (10)
C7	0.0613 (18)	0.126 (3)	0.0452 (14)	−0.0217 (18)	0.0088 (13)	0.0090 (16)
C8	0.102 (3)	0.192 (5)	0.0510 (18)	−0.037 (3)	0.0270 (19)	0.018 (2)
C9	0.094 (3)	0.161 (4)	0.074 (2)	−0.035 (3)	0.049 (2)	0.008 (2)
C10	0.0536 (17)	0.097 (2)	0.081 (2)	−0.0207 (16)	0.0311 (15)	−0.0036 (18)
C11	0.0410 (12)	0.0502 (13)	0.0551 (14)	−0.0064 (10)	0.0172 (11)	−0.0056 (11)
C12	0.0243 (10)	0.0542 (14)	0.0744 (16)	−0.0037 (10)	0.0133 (10)	−0.0116 (12)
C13	0.0223 (10)	0.0627 (15)	0.0670 (15)	−0.0047 (10)	0.0016 (10)	−0.0139 (12)
C14	0.0293 (10)	0.0465 (12)	0.0434 (11)	0.0059 (9)	0.0001 (9)	−0.0131 (9)
C15	0.0323 (12)	0.0658 (16)	0.0599 (15)	0.0119 (11)	−0.0115 (11)	−0.0170 (12)
C16	0.0583 (17)	0.081 (2)	0.0502 (15)	0.0194 (15)	−0.0196 (13)	−0.0077 (13)
C17	0.0698 (19)	0.0774 (19)	0.0410 (13)	0.0107 (15)	0.0004 (13)	0.0059 (12)
C18	0.0430 (13)	0.0526 (14)	0.0438 (12)	0.0055 (10)	0.0040 (10)	−0.0001 (10)
C19	0.0286 (10)	0.0366 (10)	0.0388 (10)	0.0073 (8)	0.0005 (8)	−0.0046 (8)
C20	0.0234 (9)	0.0375 (10)	0.0373 (10)	0.0024 (8)	0.0039 (8)	−0.0036 (8)

Geometric parameters (Å, º)

Ni—N1	1.912 (2)	N3—N4	1.408 (2)
Ni—N3	1.917 (2)	N4—C3	1.296 (2)
Ni—S3	2.1471 (6)	C5—C6	1.460 (3)
Ni—S1	2.1668 (6)	C6—C7	1.391 (3)
S1—C1	1.732 (2)	C6—C11	1.398 (3)
S2—C1	1.749 (2)	C7—C8	1.368 (4)
S2—C2	1.790 (3)	C8—C9	1.374 (5)
S3—C3	1.731 (2)	C9—C10	1.375 (5)
S4—C3	1.744 (2)	C10—C11	1.383 (3)
S4—C4	1.792 (2)	C12—C13	1.501 (3)
O1—C11	1.361 (3)	C14—C15	1.385 (3)
O1—C12	1.427 (3)	C14—C19	1.406 (3)
O2—C14	1.361 (3)	C15—C16	1.366 (4)
O2—C13	1.419 (3)	C16—C17	1.383 (4)
N1—C5	1.293 (3)	C17—C18	1.381 (3)
N1—N2	1.416 (2)	C18—C19	1.391 (3)
N2—C1	1.291 (3)	C19—C20	1.465 (3)
N3—C20	1.292 (2)
N1—Ni—N3	99.64 (7)	S3—C3—S4	115.18 (11)
N1—Ni—S3	167.62 (5)	N1—C5—C6	128.97 (19)
N3—Ni—S3	86.55 (5)	C7—C6—C11	118.7 (2)
N1—Ni—S1	85.97 (5)	C7—C6—C5	123.4 (2)
N3—Ni—S1	166.91 (5)	C11—C6—C5	117.8 (2)
S3—Ni—S1	90.29 (2)	C8—C7—C6	120.4 (3)
C1—S1—Ni	94.23 (7)	C7—C8—C9	120.5 (3)
C1—S2—C2	102.54 (12)	C8—C9—C10	120.4 (3)
C3—S3—Ni	95.53 (7)	C9—C10—C11	119.7 (3)
C3—S4—C4	103.19 (11)	O1—C11—C10	124.4 (2)
C11—O1—C12	118.86 (19)	O1—C11—C6	115.3 (2)
C14—O2—C13	119.71 (17)	C10—C11—C6	120.3 (2)
C5—N1—N2	115.32 (17)	O1—C12—C13	106.38 (19)
C5—N1—Ni	124.94 (14)	O2—C13—C12	107.78 (18)
N2—N1—Ni	119.25 (13)	O2—C14—C15	123.6 (2)
C1—N2—N1	110.66 (18)	O2—C14—C19	115.51 (18)
C20—N3—N4	115.26 (16)	C15—C14—C19	120.8 (2)
C20—N3—Ni	123.94 (14)	C16—C15—C14	119.5 (2)
N4—N3—Ni	120.19 (12)	C15—C16—C17	120.9 (2)
C3—N4—N3	111.04 (16)	C18—C17—C16	120.1 (3)
N2—C1—S1	125.05 (16)	C17—C18—C19	120.3 (2)
N2—C1—S2	119.49 (17)	C18—C19—C14	118.39 (19)
S1—C1—S2	115.45 (12)	C18—C19—C20	124.38 (19)
N4—C3—S3	124.79 (16)	C14—C19—C20	116.99 (19)
N4—C3—S4	120.03 (15)	N3—C20—C19	129.30 (18)
N1—Ni—S1—C1	−16.22 (9)	N1—C5—C6—C7	−38.5 (4)
N3—Ni—S1—C1	99.7 (2)	N1—C5—C6—C11	144.5 (2)
S3—Ni—S1—C1	175.59 (8)	C11—C6—C7—C8	−1.7 (5)
N1—Ni—S3—C3	110.4 (2)	C5—C6—C7—C8	−178.7 (3)
N3—Ni—S3—C3	−10.09 (8)	C6—C7—C8—C9	−1.4 (7)
S1—Ni—S3—C3	−177.38 (7)	C7—C8—C9—C10	2.0 (8)
N3—Ni—N1—C5	41.66 (18)	C8—C9—C10—C11	0.6 (7)
S3—Ni—N1—C5	−77.6 (3)	C12—O1—C11—C10	32.2 (4)
S1—Ni—N1—C5	−150.26 (17)	C12—O1—C11—C6	−148.9 (2)
N3—Ni—N1—N2	−146.69 (14)	C9—C10—C11—O1	175.1 (3)
S3—Ni—N1—N2	94.1 (3)	C9—C10—C11—C6	−3.8 (5)
S1—Ni—N1—N2	21.39 (14)	C7—C6—C11—O1	−174.7 (3)
C5—N1—N2—C1	155.92 (19)	C5—C6—C11—O1	2.5 (3)
Ni—N1—N2—C1	−16.5 (2)	C7—C6—C11—C10	4.3 (4)
N1—Ni—N3—C20	33.94 (17)	C5—C6—C11—C10	−178.5 (3)
S3—Ni—N3—C20	−156.87 (16)	C11—O1—C12—C13	166.1 (2)
S1—Ni—N3—C20	−80.6 (3)	C14—O2—C13—C12	174.03 (19)
N1—Ni—N3—N4	−155.52 (14)	O1—C12—C13—O2	−50.1 (2)
S3—Ni—N3—N4	13.68 (13)	C13—O2—C14—C15	38.0 (3)
S1—Ni—N3—N4	89.9 (3)	C13—O2—C14—C19	−144.8 (2)
C20—N3—N4—C3	160.43 (17)	O2—C14—C15—C16	175.1 (2)
Ni—N3—N4—C3	−10.9 (2)	C19—C14—C15—C16	−2.0 (4)
N1—N2—C1—S1	−1.6 (3)	C14—C15—C16—C17	0.8 (4)
N1—N2—C1—S2	178.67 (14)	C15—C16—C17—C18	1.0 (4)
Ni—S1—C1—N2	14.8 (2)	C16—C17—C18—C19	−1.7 (4)
Ni—S1—C1—S2	−165.48 (11)	C17—C18—C19—C14	0.5 (3)
C2—S2—C1—N2	−0.9 (2)	C17—C18—C19—C20	−173.6 (2)
C2—S2—C1—S1	179.32 (16)	O2—C14—C19—C18	−175.97 (19)
N3—N4—C3—S3	−0.3 (2)	C15—C14—C19—C18	1.3 (3)
N3—N4—C3—S4	−179.18 (13)	O2—C14—C19—C20	−1.4 (3)
Ni—S3—C3—N4	8.83 (18)	C15—C14—C19—C20	175.9 (2)
Ni—S3—C3—S4	−172.24 (9)	N4—N3—C20—C19	−3.8 (3)
C4—S4—C3—N4	1.82 (19)	Ni—N3—C20—C19	167.2 (2)
C4—S4—C3—S3	−177.17 (12)	C18—C19—C20—N3	−37.0 (3)
N2—N1—C5—C6	−3.7 (3)	C14—C19—C20—N3	148.9 (2)
Ni—N1—C5—C6	168.3 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7A···N2	0.93	2.50	2.902 (4)	106
C18—H18A···N4	0.93	2.47	2.917 (3)	109