Two isomorphous transition metal complexes displaying a coordinated tetra­thio­nate unit: bis­(4,4′-dimethyl-2,2′-bi­pyridine-κ²N,N′)(tetra­thio­nato-κ²S,S′)cadmium(II) di­methyl­formamide disolvate and the zinc(II) analogue

The isomorphous title compounds, [Tr(S₄O₆)(C₁₂H₁₂N₂)₂]·2C₃H₇NO (Tr = Cd^II and Zn^II), consist of metal centres to which one tetra­thio­nate and two 4,4′-dimethyl-2,2′-bi­pyridine chelating ligands bind. The structures are completed by two symmetry-related di­methyl­formamide solvent mol­ecules. Each metal-centred complex is bis­ected by a twofold axis running through the metal centre and halving the chelating tetra­thio­nate dianion through the central S—S bond. The ancillary symmetry-related 4,4′-dimethyl-2,2′-bi­pyridine lig­ands act as chelates. This results in a distorted six-coordinate geometry, with similar Tr—O/N distances but central angles differing substanti­ally from 90 and 180°. Both ligands are basically featureless from a geometric point of view, with torsion angles in both coordinated tetra­thio­nate groups suggesting a trend linking metal size (covalent radius) and ligand `openness'. Packing is directed by (C—H)_aromatic...O bridges and π–π offset stacked inter­actions defining chains along [001], further linked by weaker (C—H)_methyl...O bridges, some of them mediated by the di­methyl­formamide solvent mol­ecules.

S1. Comment

For an extended period of 40 years [viz. those between the reports of Baggio & Baggio (1973) and Suarez et al. (2013)], our group has been interested in the coordination affinity towards transition metals of a variety of different sulfur oxoanions (sufate, sulfite, thiosulfate, peroxodisulfate, di/tri/tetra/pentathionate etc.) in organic–inorganic coordination compounds. Even though many of them show a remarkable coordination tendency (SO₄^2-, SSO₃^2- etc.), others, in particular the latter `thionate' family, present extremely poor binding abilities. This is readily confirmed by a search of the Cambridge Structural database (CSD, Version 5.33; Allen, 2002), contrasting for each ligand the total number of entries (m) and the number of coordinated ones (n); in what follows we shall represent this information as (m,n), viz. dithionate (125,13), trithionate (4,1), tetrathionate (19,2) and pentathionate (8,0). The case of tetrathionate is particularly interesting; only 2 out of 19 structures in the CSD show the anion acting in a coordinating mode [Freire et al. (1998) showed Cu bridging and Freire et al. (2001) showed Mn chelating], and in both cases the ligand had been generated serendipitously during the synthesis procedure as an oxidation product of S<sub>2</sub>O<sub>3</sub><sup>2-</sup>, which thus acted as an unwitting precursor. In summary, no direct synthesis starting from any S<sub>4</sub>O<sub>6</sub><sup>2-</sup> derivative has so far resulted in any transition metal complex with a coordinated tetrathionate group. In order to explore this puzzling situation a bit further, we tried to `fine tune' the synthesis and crystallization process of different S₄O₆^2- transition metal compounds (see Experimental section for details). We present herein the first two successful results of these attempts, the isomorphous Cd and Zn title complexes, namely bis(4,4'-dimethyl-2,2'-bipyridine-κ²N,N')(tetrathionato-κ²S,S')cadmium(II) dimethylformamide disolvate, [Cd(tth)(dmbpy)₂].2DMF, (I) (Fig. 1a), and the zinc(II) analogue, [Zn(tth)(dmbpy)₂(tth)].2DMF, (II) (Fig. 1b), where dmbpy is 4,4'-dimethyl-2,2'-bipyridine, tth is the tetrathionate anion and DMF is dimethylformamide.

The molecules of both isomorphs consist of a transition metal (Tr) cation [Tr = Cd^II for (I) and Tr = Zn^II for (II)] to which one tth and two dmbpy chelating ligands bind. The structures are completed by two symmetry-related DMF solvent molecules. Each complex molecule is bisected by a twofold axis running through the metal centre and halving the chelating tth anion through the central S—S bond. The ancillary symmetry-related dmbpy ligands also act as chelates. The metal cations present a 2+2+2 N₄O₂ environment. As expected, this results in a distorted sixfold geometry, with rather even Tr···O/N distances (Tables 1 and 2) but with the central angles differing substantially from 90 and 180° [90±18.78 (6) and 180±22.44 (7)° for (I), and 90±12.80 (10) and 180±13.27 (9)° for (II)].

The dmbpy units are planar, with maximum deviations of -0.033 (2) and 0.032 (2) Å for (I), and -0.030 (2) and 0.018 (2) Å for (II), corresponding in both cases to the terminal methyl groups.

The tth ligands chelate the metals in a similar manner to that found in the Mn–bipyridine analogue (Freire et al., 2001). They present typical S—S bonds, while the terminal S—O distances are almost indistinguishable, except for a small lengthening for the coordinated atom O1 [S—O = 1.403 (2)–1.4297 (19) Å for (I) and 1.417 (2)–1.442 (2) Å for (II)] [S1═ O2 and S1═O3 are double bonds, while S1—O1 is a single bond, so why quote them all together like this?]. However, they seem to adjust their flexible spatial conformation to the different metal sizes; the O1—S1—S2—S2ⁱ and S1—S2—S2ⁱ—S1ⁱ torsion angles [symmetry code: (i) -x + 1, y, -z + 1/2] along the anion `backbone' are 56.00 (10) and 59.05 (12)° for (I), and -105.19 (4) and -99.48 (6)° for (II), respectively. Given that, in an A—B—C—D torsion angle, a 90° value corresponds to perpendicular A—B—C:B—C—D planes, and a 0 or 180° value to parallel ones, a smaller or larger departure from 90° can be indicative of a more `close/open' character of the tth anionic group. It transpires (perhaps expectedly) that this case appears more `open', with large departures from 90°. Similar results are obtained by comparing the S1···S1ⁱ distances in the coordinated anions, viz. 4.428 (2) for (I) and 4.331 (2) Å for (II).

As stated above, the donor atoms in (I) and (II) cannot fit in any regular polyhedron, but the three chelate ligands abide by the vector bond-valence postulate of the vectorial bond-valence model (for details on the theory, see Harvey et al., 2006). The three ligand vectors, as defined therein, lie in a planar trigonal geometry, with the sum of the angles being 360.0 (2)° for both (I) and (II) (ideal = 360°) and resultant vector moduli of 0.085 valence units (v.u.) for (I) and 0.049 v.u. for (II) (ideal = 0.00 v.u.). The usual bond-valence sums (BVS; Brown, 2002) for each metal atom are 2.00 v.u. for Zn and 2.17 v.u. for Cd (see footnote).

In spite of the lack of good hydrogen-bond donors, which weakens the interactions between monomers, packing indices [as calculated by PLATON (Spek, 2009), following Kitajgorodskij (1973)] are very near the expected average of ca 65% [66.15% for (I) and 67.4% for (II)].

Tables 2 and 4 present relevant C—H···O hydrogen bonds, while Table 5 gives information on the π–π interactions. The first three entries in Tables 2 and 4 correspond to the more active (C—H)_aromatic group, and in fact these have a definite structural role. Fig. 2 shows the way in which the interactions presented as the first two entries serve to link self-complementarily adjacent molecules along the [001] direction, in the form of well defined chains, complemented by the π–π interactions between offset stacked dmbpy groups. The third entry in Tables 2 and 4 binds the DMF solvent molecules to the main molecule. The remaining three entries involve the less active (C—H)_methyl groups, and these interactions ultimately have the role of interlinking chains together in a rather weak fashion.

This differentiated interaction scheme serves to provide, if not an explanation, at least a plausibility argument for the rather intriguing behaviour in cell metrics, viz. the increase in the c cell dimension when going from Zn to Cd (an expected fact) but a tiny decrease in the remaining two cell dimensions (a rather unusual one), more pronounced in the a dimension. Fig. 2 helps in understanding the increase along the [001] chains: this is the overall direction of the Cd—N interactions (~ 10% longer than the corresponding Zn—N ones), as well as of the bridging (C—H)_arom···O and π–π bonds, thus rendering the c cell dimension longer (and more rigid).

Along the remaining two directions, chains are instead held together by much more labile forces [mainly (C—H)_methyl···O contacts; Fig. 3]. These are, accordingly, `soft' directions which would not oppose resistence to any eventual compression required by the close packing of the chains.

Footnote. In our extended experience with Cd complexes, we have detected that the bond-valence parameters presented by Brown (2006) for Cd—O and Cd—N (R_Cd—O = 1.904 and R_Cd—N = 1.960) usually lead to overestimated BVS values for the cation. This is not an unexpected fact, since it is known that these parameters are not absolutely `universal' but depend on, among other features, the coordination environment (Brown, 2008). Trying to overcome this situation, we tried to find better values for both bond-valence parameters and so, while keeping `b' fixed at its standard value of 0.37, we performed a least-squares fit on ca 2000 CdO_nN_6-n coordination polyhedra in the CSD (Allen, 2002) of the valence sum equation

Σ (V_i) _i:1>6 = V [with V = 2, the expected Cd valence and V_i = exp (R_x - R_i)/b)],

where R_x = R_Cd—O or R_Cd—N are the parameters to be refined, and R_i the actual Cd—O and Cd—N bond lengths.

Upon convergence, this procedure led to slightly different values than those given by Brown (2006) (about 1% smaller, viz. R_Cd—O = 1.886 and R_Cd—N = 1.946) and with a better performance; they resulted in a BVS for Cd1 in (I) of 2.17, versus 2.26 as calculated from Brown's data.

Related literature

For related literature, see: Allen (2002); Baggio & Baggio (1973); Brown (2002, 2006, 2008); Freire et al. (1998, 2001); Harvey et al. (2006); Kitajgorodskij (1973); Sheldrick (2008); Spek (2009); Suarez et al. (2013).

S2. Experimental

In several previous attempts to obtain hybrid organic tetrathionate transition metal complexes using aqueous solutions, the anion decomposed systematically, rendering thiosulfate. In view of these failures, we thought of using a solvent in which the organic ligand is soluble but the other two components only slightly soluble. In doing so, it was expected that the components would mix slowly to form the complex, while simultaneously displacing the solubility equilibrium. After some tests, we selected dimethylformamide (DMF) as an appropriate solvent. To a solution of 4,4'-dimethyl-2,2'-bipyridine in DMF (5 ml, 0.050 M), solid Cd or Zn diacetate dihydrate and potassium tetrathionate were added in a mass:volume ratio so as to obtain a 0.050 M solution of each component. On standing, in both cases, a poorly crystallized precipitate appeared, to be digested after a while (one week in the Cd case and one month for Zn) to give rise finally to crystals of the expected complexes in the form of well faceted colourless blocks suitable for X-ray diffraction.

S3. Refinement

All H atoms were visible in difference maps, but were subsequently placed in geometrically idealized positions and allowed to ride on their parent atoms, with C—H = 0.93 Å and U_iso(H) = 1.2U_eq(C) for aromatic H, and C—H = 0.96 Å and U_iso(H) = 1.5U_eq(C) for methyl H. In (I), conventional weighting led to a rather low goodness-of-fit, for which a special scheme with enhanced weighting for high-angle reflections (provided in SHELXL97; Sheldrick, 2008) was applied.

Computing details

For both compounds, data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell refinement: CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

	Fig. 1. Molecular views of (a) (I) and (b) (II), with the atom-numbering schemes. Displacement ellipsoids are drawn at the 30% probability level. Full ellipsoids and black bonds represent the independent part of the molecule. [Symmetry code: (i) -x + 1, y, -z + 1/2.]
	Fig. 2. A simplified view of the [001] chain in (I). C—H···O hydrogen bonds are shown as dashed lines. [Looks like π–π interactions are shown the same way?]
	Fig. 3. A packing view of (I), projected down [001], showing the loose manner in which the chains interact parallel to each other.

(I) Bis(4,4'-dimethyl-2,2'-bipyridine-κ²N,N')(tetrathionato-κ²S,S')cadmium(II) dimethylformamide disolvate

Crystal data

[Cd(S4O6)(C12H12N2)2]·2C3H7NO	F(000) = 1744
Mr = 851.30	Dx = 1.522 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 2418 reflections
a = 20.7076 (7) Å	θ = 3.7–28.1°
b = 10.7885 (3) Å	µ = 0.87 mm^−1
c = 17.5044 (5) Å	T = 294 K
β = 108.187 (3)°	Prism, colourless
V = 3715.2 (2) Å^3	0.15 × 0.05 × 0.04 mm
Z = 4

Data collection

Oxford Gemini S Ultra CCD area-detector diffractometer	2693 reflections with I > 2σ(I)
ω scans, thick slices	Rint = 0.025
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	θmax = 26.5°, θmin = 3.6°
Tmin = 0.94, Tmax = 0.96	h = −25→24
9819 measured reflections	k = −13→13
3844 independent reflections	l = −13→21

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)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.065	H-atom parameters constrained
S = 1.00	w = [exp(1.20(sinθ/λ)^2)]/[σ^2(Fo^2) + (0.0331P)^2] where P = 0.33333Fo^2 + 0.66667Fc^2
3844 reflections	(Δ/σ)max = 0.001
226 parameters	Δρmax = 0.34 e Å^−3
0 restraints	Δρmin = −0.33 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
Cd1	0.5000	0.05562 (2)	0.2500	0.04902 (10)
S1	0.58500 (3)	0.31673 (6)	0.36429 (3)	0.04756 (15)
S2	0.50175 (4)	0.43161 (7)	0.30822 (5)	0.0791 (2)
O1	0.57359 (11)	0.19950 (18)	0.32421 (13)	0.0921 (7)
O2	0.64280 (10)	0.3761 (2)	0.35624 (13)	0.0983 (7)
O3	0.58172 (12)	0.3138 (2)	0.44390 (11)	0.0942 (7)
N1	0.57068 (10)	0.04451 (17)	0.17054 (11)	0.0483 (5)
N2	0.45980 (10)	−0.09723 (18)	0.15385 (11)	0.0500 (5)
C1	0.62399 (13)	0.1185 (2)	0.17821 (15)	0.0590 (7)
H1	0.6322	0.1819	0.2160	0.071*
C2	0.66702 (13)	0.1060 (3)	0.13347 (16)	0.0618 (7)
H2	0.7033	0.1603	0.1407	0.074*
C3	0.65629 (12)	0.0120 (3)	0.07735 (15)	0.0539 (6)
C4	0.60000 (12)	−0.0626 (2)	0.06785 (14)	0.0493 (6)
H4	0.5902	−0.1253	0.0295	0.059*
C5	0.55803 (11)	−0.04488 (19)	0.11482 (12)	0.0418 (5)
C6	0.49677 (11)	−0.12373 (19)	0.10555 (12)	0.0415 (5)
C7	0.47863 (12)	−0.2188 (2)	0.05011 (13)	0.0492 (6)
H7	0.5051	−0.2351	0.0170	0.059*
C8	0.42155 (14)	−0.2900 (2)	0.04323 (14)	0.0576 (6)
C9	0.38446 (14)	−0.2612 (3)	0.09368 (16)	0.0707 (8)
H9	0.3457	−0.3065	0.0913	0.085*
C10	0.40441 (14)	−0.1663 (3)	0.14700 (17)	0.0665 (7)
H10	0.3784	−0.1484	0.1804	0.080*
C11	0.70313 (16)	−0.0099 (3)	0.02856 (19)	0.0830 (9)
H11A	0.7162	0.0682	0.0116	0.124*
H11B	0.6803	−0.0588	−0.0178	0.124*
H11C	0.7429	−0.0531	0.0606	0.124*
C12	0.40119 (19)	−0.3912 (3)	−0.01794 (18)	0.0884 (10)
H12A	0.4172	−0.4693	0.0071	0.133*
H12B	0.4208	−0.3760	−0.0601	0.133*
H12C	0.3526	−0.3932	−0.0402	0.133*
N3	0.20135 (10)	0.06463 (19)	0.18402 (12)	0.0552 (5)
O4	0.26101 (12)	−0.1120 (2)	0.18838 (15)	0.0995 (7)
C13	0.15034 (16)	0.1281 (3)	0.2096 (2)	0.0961 (11)
H13A	0.1383	0.0784	0.2486	0.144*
H13B	0.1108	0.1418	0.1640	0.144*
H13C	0.1680	0.2063	0.2332	0.144*
C14	0.22956 (18)	0.1295 (3)	0.13132 (18)	0.0917 (10)
H14A	0.2649	0.0805	0.1217	0.138*
H14B	0.2481	0.2069	0.1554	0.138*
H14C	0.1947	0.1449	0.0813	0.138*
C15	0.22072 (15)	−0.0504 (3)	0.20863 (17)	0.0686 (7)
H15	0.2014	−0.0861	0.2447	0.082*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.05889 (18)	0.04432 (15)	0.04450 (15)	0.000	0.01706 (12)	0.000
S1	0.0500 (4)	0.0489 (3)	0.0423 (3)	−0.0059 (3)	0.0124 (3)	−0.0055 (3)
S2	0.0822 (5)	0.0793 (5)	0.0635 (5)	0.0290 (5)	0.0051 (4)	−0.0199 (4)
O1	0.0762 (14)	0.0635 (12)	0.1052 (16)	0.0086 (11)	−0.0170 (11)	−0.0356 (12)
O2	0.0538 (12)	0.1241 (18)	0.1094 (17)	−0.0224 (13)	0.0147 (12)	0.0315 (15)
O3	0.1243 (19)	0.1135 (17)	0.0521 (12)	0.0258 (15)	0.0380 (12)	0.0153 (11)
N1	0.0502 (12)	0.0452 (11)	0.0474 (11)	−0.0128 (10)	0.0120 (9)	−0.0033 (9)
N2	0.0513 (12)	0.0489 (11)	0.0521 (12)	−0.0121 (10)	0.0193 (10)	−0.0035 (9)
C1	0.0604 (17)	0.0532 (15)	0.0584 (16)	−0.0182 (14)	0.0114 (13)	−0.0055 (12)
C2	0.0456 (15)	0.0662 (16)	0.0684 (18)	−0.0197 (14)	0.0099 (13)	0.0136 (15)
C3	0.0420 (14)	0.0617 (15)	0.0554 (16)	0.0000 (13)	0.0114 (12)	0.0163 (13)
C4	0.0482 (14)	0.0525 (13)	0.0449 (13)	−0.0016 (13)	0.0114 (11)	0.0014 (11)
C5	0.0444 (13)	0.0385 (12)	0.0384 (12)	−0.0020 (11)	0.0071 (10)	0.0058 (10)
C6	0.0436 (13)	0.0380 (12)	0.0395 (12)	−0.0020 (11)	0.0082 (10)	0.0059 (10)
C7	0.0562 (15)	0.0435 (12)	0.0465 (14)	−0.0069 (12)	0.0142 (12)	−0.0022 (11)
C8	0.0693 (18)	0.0449 (13)	0.0484 (15)	−0.0136 (14)	0.0034 (13)	0.0029 (11)
C9	0.0620 (18)	0.0752 (19)	0.0708 (18)	−0.0324 (16)	0.0147 (15)	−0.0018 (16)
C10	0.0621 (17)	0.0730 (19)	0.0712 (18)	−0.0191 (16)	0.0305 (15)	−0.0025 (15)
C11	0.0598 (18)	0.111 (2)	0.087 (2)	−0.0010 (18)	0.0363 (17)	0.0148 (19)
C12	0.114 (3)	0.0622 (18)	0.077 (2)	−0.039 (2)	0.0127 (19)	−0.0135 (16)
N3	0.0535 (12)	0.0504 (12)	0.0608 (13)	−0.0064 (11)	0.0166 (10)	−0.0080 (10)
O4	0.0842 (16)	0.0774 (14)	0.138 (2)	0.0191 (13)	0.0359 (15)	−0.0176 (14)
C13	0.073 (2)	0.078 (2)	0.149 (3)	−0.0009 (19)	0.051 (2)	−0.022 (2)
C14	0.104 (3)	0.098 (2)	0.079 (2)	−0.026 (2)	0.036 (2)	0.0020 (19)
C15	0.0666 (19)	0.0639 (18)	0.0716 (19)	−0.0112 (17)	0.0160 (15)	−0.0053 (16)

Geometric parameters (Å, º)

Cd1—O1	2.2767 (19)	C7—C8	1.383 (3)
Cd1—O1^i	2.2767 (19)	C7—H7	0.9300
Cd1—N1^i	2.3156 (18)	C8—C9	1.375 (3)
Cd1—N1	2.3156 (18)	C8—C12	1.495 (3)
Cd1—N2	2.3175 (19)	C9—C10	1.360 (4)
Cd1—N2^i	2.3175 (19)	C9—H9	0.9300
S1—O2	1.403 (2)	C10—H10	0.9300
S1—O3	1.4165 (18)	C11—H11A	0.9600
S1—O1	1.4297 (19)	C11—H11B	0.9600
S1—S2	2.1011 (10)	C11—H11C	0.9600
S2—S2^i	2.0169 (15)	C12—H12A	0.9600
N1—C1	1.335 (3)	C12—H12B	0.9600
N1—C5	1.338 (3)	C12—H12C	0.9600
N2—C6	1.336 (3)	N3—C15	1.333 (3)
N2—C10	1.341 (3)	N3—C14	1.421 (3)
C1—C2	1.364 (4)	N3—C13	1.442 (3)
C1—H1	0.9300	O4—C15	1.204 (3)
C2—C3	1.381 (4)	C13—H13A	0.9600
C2—H2	0.9300	C13—H13B	0.9600
C3—C4	1.383 (3)	C13—H13C	0.9600
C3—C11	1.498 (4)	C14—H14A	0.9600
C4—C5	1.383 (3)	C14—H14B	0.9600
C4—H4	0.9300	C14—H14C	0.9600
C5—C6	1.494 (3)	C15—H15	0.9300
C6—C7	1.381 (3)
O1—Cd1—O1^i	94.04 (10)	N2—C6—C5	116.37 (19)
O1—Cd1—N1^i	97.39 (8)	C7—C6—C5	122.3 (2)
O1^i—Cd1—N1^i	86.67 (8)	C6—C7—C8	120.8 (2)
O1—Cd1—N1	86.67 (8)	C6—C7—H7	119.6
O1^i—Cd1—N1	97.39 (8)	C8—C7—H7	119.6
N1^i—Cd1—N1	174.06 (9)	C9—C8—C7	116.9 (2)
O1—Cd1—N2	157.56 (7)	C9—C8—C12	122.4 (3)
O1^i—Cd1—N2	92.64 (8)	C7—C8—C12	120.7 (3)
N1^i—Cd1—N2	104.38 (7)	C10—C9—C8	120.0 (2)
N1—Cd1—N2	71.22 (6)	C10—C9—H9	120.0
O1—Cd1—N2^i	92.64 (8)	C8—C9—H9	120.0
O1^i—Cd1—N2^i	157.56 (7)	N2—C10—C9	123.2 (2)
N1^i—Cd1—N2^i	71.22 (6)	N2—C10—H10	118.4
N1—Cd1—N2^i	104.38 (7)	C9—C10—H10	118.4
N2—Cd1—N2^i	89.27 (10)	C3—C11—H11A	109.5
O2—S1—O3	114.41 (14)	C3—C11—H11B	109.5
O2—S1—O1	111.72 (15)	H11A—C11—H11B	109.5
O3—S1—O1	114.31 (14)	C3—C11—H11C	109.5
O2—S1—S2	106.56 (10)	H11A—C11—H11C	109.5
O3—S1—S2	100.87 (10)	H11B—C11—H11C	109.5
O1—S1—S2	107.87 (9)	C8—C12—H12A	109.5
S2^i—S2—S1	103.74 (5)	C8—C12—H12B	109.5
S1—O1—Cd1	149.51 (13)	H12A—C12—H12B	109.5
C1—N1—C5	118.2 (2)	C8—C12—H12C	109.5
C1—N1—Cd1	124.52 (16)	H12A—C12—H12C	109.5
C5—N1—Cd1	117.29 (14)	H12B—C12—H12C	109.5
C6—N2—C10	117.9 (2)	C15—N3—C14	121.7 (2)
C6—N2—Cd1	117.70 (14)	C15—N3—C13	121.2 (2)
C10—N2—Cd1	124.29 (16)	C14—N3—C13	117.2 (3)
N1—C1—C2	123.4 (2)	N3—C13—H13A	109.5
N1—C1—H1	118.3	N3—C13—H13B	109.5
C2—C1—H1	118.3	H13A—C13—H13B	109.5
C1—C2—C3	119.5 (2)	N3—C13—H13C	109.5
C1—C2—H2	120.3	H13A—C13—H13C	109.5
C3—C2—H2	120.3	H13B—C13—H13C	109.5
C2—C3—C4	117.1 (2)	N3—C14—H14A	109.5
C2—C3—C11	122.1 (2)	N3—C14—H14B	109.5
C4—C3—C11	120.8 (3)	H14A—C14—H14B	109.5
C3—C4—C5	120.7 (2)	N3—C14—H14C	109.5
C3—C4—H4	119.6	H14A—C14—H14C	109.5
C5—C4—H4	119.6	H14B—C14—H14C	109.5
N1—C5—C4	121.1 (2)	O4—C15—N3	125.9 (3)
N1—C5—C6	117.13 (19)	O4—C15—H15	117.1
C4—C5—C6	121.8 (2)	N3—C15—H15	117.1
N2—C6—C7	121.3 (2)

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···O3^ii	0.93	2.50	3.418 (3)	170
C7—H7···O3^ii	0.93	2.48	3.397 (3)	169
C10—H10···O4	0.93	2.51	3.320 (4)	146
C11—H11C···O2^iii	0.96	2.48	3.427 (4)	168
C12—H12A···O3^iv	0.96	2.49	3.413 (3)	161
C13—H13C···O4^v	0.96	2.57	3.517 (4)	167

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

(II) Bis(4,4'-dimethyl-2,2'-bipyridine-κ²N,N')(tetrathionato-κ²S,S')cadmium(II) dimethylformamide disolvate

Crystal data

[Zn(S4O6)(C12H12N2)2]·2C3H7NO	F(000) = 1672
Mr = 804.27	Dx = 1.463 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 2102 reflections
a = 20.8508 (12) Å	θ = 3.5–28.8°
b = 10.8334 (8) Å	µ = 0.96 mm^−1
c = 16.9888 (10) Å	T = 294 K
β = 107.956 (7)°	Prism, colourless
V = 3650.6 (4) Å^3	0.10 × 0.05 × 0.04 mm
Z = 4

Data collection

Oxford Gemini S Ultra CCD area-detector diffractometer	3945 independent reflections
Radiation source: fine-focus sealed tube	2446 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.062
ω scans, thick slices	θmax = 27.0°, θmin = 3.5°
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009)	h = −26→26
Tmin = 0.95, Tmax = 0.97	k = −13→13
12111 measured reflections	l = −21→21

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)] = 0.052	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.104	H-atom parameters constrained
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0324P)^2] where P = (Fo^2 + 2Fc^2)/3
3945 reflections	(Δ/σ)max = 0.005
226 parameters	Δρmax = 0.32 e Å^−3
0 restraints	Δρmin = −0.29 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.

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

	x	y	z	Uiso*/Ueq
Zn1	0.5000	0.05985 (5)	0.2500	0.04149 (18)
S1	0.57909 (4)	0.31202 (8)	0.36779 (5)	0.0424 (2)
S2	0.50021 (5)	0.43416 (10)	0.30940 (6)	0.0700 (3)
O1	0.56286 (11)	0.1942 (2)	0.32708 (14)	0.0652 (7)
O2	0.63916 (11)	0.3628 (3)	0.35902 (15)	0.0764 (8)
O3	0.57462 (13)	0.3140 (3)	0.44977 (13)	0.0748 (8)
N1	0.56672 (12)	0.0504 (2)	0.17879 (15)	0.0407 (6)
N2	0.45588 (12)	−0.0803 (2)	0.16141 (15)	0.0414 (7)
C1	0.62052 (16)	0.1225 (3)	0.18716 (19)	0.0474 (9)
H1	0.6283	0.1872	0.2249	0.057*
C2	0.66462 (16)	0.1058 (3)	0.1429 (2)	0.0513 (9)
H2	0.7013	0.1583	0.1510	0.062*
C3	0.65451 (15)	0.0105 (4)	0.0862 (2)	0.0480 (9)
C4	0.59720 (16)	−0.0613 (3)	0.07514 (18)	0.0442 (8)
H4	0.5875	−0.1243	0.0360	0.053*
C5	0.55459 (14)	−0.0400 (3)	0.12157 (17)	0.0359 (7)
C6	0.49276 (15)	−0.1152 (3)	0.11258 (18)	0.0383 (8)
C7	0.47340 (16)	−0.2104 (3)	0.05736 (18)	0.0460 (8)
H7	0.4997	−0.2311	0.0239	0.055*
C8	0.41503 (18)	−0.2761 (3)	0.05085 (19)	0.0508 (9)
C9	0.37809 (18)	−0.2399 (4)	0.1009 (2)	0.0598 (10)
H9	0.3384	−0.2811	0.0983	0.072*
C10	0.39926 (16)	−0.1432 (4)	0.1547 (2)	0.0535 (10)
H10	0.3732	−0.1204	0.1879	0.064*
C11	0.70261 (18)	−0.0158 (4)	0.0385 (2)	0.0716 (12)
H11A	0.7169	0.0605	0.0205	0.107*
H11B	0.6806	−0.0657	−0.0089	0.107*
H11C	0.7412	−0.0591	0.0732	0.107*
C12	0.3930 (2)	−0.3805 (4)	−0.0092 (2)	0.0785 (13)
H12A	0.4011	−0.4575	0.0203	0.118*
H12B	0.4181	−0.3785	−0.0480	0.118*
H12C	0.3458	−0.3726	−0.0383	0.118*
N3	0.19834 (13)	0.0609 (3)	0.18132 (16)	0.0491 (7)
O4	0.25600 (13)	−0.1184 (3)	0.19203 (19)	0.0871 (9)
C13	0.1478 (2)	0.1295 (4)	0.2038 (3)	0.0907 (15)
H13A	0.1326	0.0827	0.2426	0.136*
H13B	0.1104	0.1454	0.1552	0.136*
H13C	0.1665	0.2064	0.2285	0.136*
C14	0.2296 (2)	0.1193 (4)	0.1266 (2)	0.0809 (13)
H14A	0.2639	0.0660	0.1187	0.121*
H14B	0.2496	0.1959	0.1504	0.121*
H14C	0.1963	0.1349	0.0743	0.121*
C15	0.21530 (19)	−0.0527 (4)	0.2094 (2)	0.0590 (10)
H15	0.1940	−0.0848	0.2456	0.071*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Zn1	0.0414 (3)	0.0397 (3)	0.0429 (3)	0.000	0.0122 (2)	0.000
S1	0.0429 (5)	0.0435 (5)	0.0397 (5)	−0.0051 (4)	0.0112 (4)	−0.0032 (4)
S2	0.0766 (7)	0.0627 (7)	0.0578 (6)	0.0251 (6)	0.0018 (5)	−0.0164 (5)
O1	0.0612 (15)	0.0436 (16)	0.0741 (16)	0.0018 (13)	−0.0036 (13)	−0.0181 (13)
O2	0.0464 (14)	0.096 (2)	0.0844 (18)	−0.0230 (15)	0.0161 (13)	0.0091 (17)
O3	0.104 (2)	0.080 (2)	0.0458 (14)	0.0132 (17)	0.0322 (14)	0.0081 (14)
N1	0.0386 (14)	0.0382 (17)	0.0420 (15)	−0.0071 (13)	0.0078 (12)	−0.0018 (13)
N2	0.0375 (15)	0.0397 (17)	0.0452 (15)	−0.0081 (13)	0.0103 (12)	−0.0017 (13)
C1	0.0432 (19)	0.042 (2)	0.051 (2)	−0.0081 (17)	0.0059 (17)	−0.0003 (17)
C2	0.0362 (19)	0.057 (3)	0.056 (2)	−0.0076 (18)	0.0079 (17)	0.0100 (19)
C3	0.0362 (18)	0.059 (2)	0.047 (2)	0.0035 (18)	0.0099 (16)	0.0205 (19)
C4	0.0483 (19)	0.046 (2)	0.0373 (17)	0.0021 (18)	0.0124 (15)	0.0014 (16)
C5	0.0353 (17)	0.036 (2)	0.0333 (16)	−0.0002 (15)	0.0052 (14)	0.0066 (14)
C6	0.0384 (18)	0.039 (2)	0.0339 (17)	0.0006 (16)	0.0051 (15)	0.0031 (15)
C7	0.050 (2)	0.042 (2)	0.0431 (18)	−0.0034 (18)	0.0097 (16)	−0.0043 (17)
C8	0.063 (2)	0.038 (2)	0.0419 (19)	−0.0115 (19)	0.0027 (18)	−0.0024 (17)
C9	0.052 (2)	0.057 (3)	0.062 (2)	−0.027 (2)	0.006 (2)	−0.003 (2)
C10	0.043 (2)	0.061 (3)	0.057 (2)	−0.0110 (19)	0.0164 (17)	0.002 (2)
C11	0.057 (2)	0.093 (3)	0.074 (3)	0.007 (2)	0.034 (2)	0.017 (2)
C12	0.101 (3)	0.049 (3)	0.069 (3)	−0.026 (2)	0.000 (2)	−0.009 (2)
N3	0.0466 (16)	0.0467 (19)	0.0539 (17)	−0.0067 (16)	0.0151 (14)	−0.0073 (16)
O4	0.0615 (18)	0.067 (2)	0.130 (3)	0.0112 (16)	0.0251 (18)	−0.0105 (19)
C13	0.070 (3)	0.067 (3)	0.141 (4)	0.004 (3)	0.042 (3)	−0.025 (3)
C14	0.089 (3)	0.085 (3)	0.071 (3)	−0.019 (3)	0.028 (2)	0.010 (2)
C15	0.055 (2)	0.062 (3)	0.057 (2)	−0.016 (2)	0.0125 (19)	−0.003 (2)

Geometric parameters (Å, º)

Zn1—O1	2.119 (2)	C7—C8	1.384 (4)
Zn1—O1^i	2.119 (2)	C7—H7	0.9300
Zn1—N1	2.109 (3)	C8—C9	1.368 (5)
Zn1—N1^i	2.109 (3)	C8—C12	1.497 (5)
Zn1—N2	2.136 (3)	C9—C10	1.370 (5)
Zn1—N2^i	2.136 (3)	C9—H9	0.9300
S1—O2	1.417 (2)	C10—H10	0.9300
S1—O3	1.424 (2)	C11—H11A	0.9600
S1—O1	1.442 (2)	C11—H11B	0.9600
S1—S2	2.1056 (13)	C11—H11C	0.9600
S2—S2^i	2.016 (2)	C12—H12A	0.9600
N1—C1	1.338 (4)	C12—H12B	0.9600
N1—C5	1.348 (4)	C12—H12C	0.9600
N2—C10	1.337 (4)	N3—C15	1.328 (4)
N2—C6	1.348 (4)	N3—C13	1.435 (4)
C1—C2	1.367 (4)	N3—C14	1.436 (4)
C1—H1	0.9300	O4—C15	1.211 (4)
C2—C3	1.383 (5)	C13—H13A	0.9600
C2—H2	0.9300	C13—H13B	0.9600
C3—C4	1.389 (4)	C13—H13C	0.9600
C3—C11	1.499 (4)	C14—H14A	0.9600
C4—C5	1.377 (4)	C14—H14B	0.9600
C4—H4	0.9300	C14—H14C	0.9600
C5—C6	1.493 (4)	C15—H15	0.9300
C6—C7	1.368 (4)
N1—Zn1—N1^i	174.45 (15)	N2—C6—C5	115.0 (3)
N1—Zn1—O1	89.77 (10)	C7—C6—C5	123.0 (3)
N1^i—Zn1—O1	94.04 (10)	C6—C7—C8	120.5 (3)
N1—Zn1—O1^i	94.04 (10)	C6—C7—H7	119.7
N1^i—Zn1—O1^i	89.77 (10)	C8—C7—H7	119.7
O1—Zn1—O1^i	93.27 (13)	C9—C8—C7	116.9 (3)
N1—Zn1—N2	77.20 (10)	C9—C8—C12	121.8 (3)
N1^i—Zn1—N2	98.79 (10)	C7—C8—C12	121.3 (3)
O1—Zn1—N2	166.73 (9)	C8—C9—C10	120.4 (3)
O1^i—Zn1—N2	90.15 (9)	C8—C9—H9	119.8
N1—Zn1—N2^i	98.79 (10)	C10—C9—H9	119.8
N1^i—Zn1—N2^i	77.20 (10)	N2—C10—C9	122.8 (3)
O1—Zn1—N2^i	90.15 (9)	N2—C10—H10	118.6
O1^i—Zn1—N2^i	166.73 (9)	C9—C10—H10	118.6
N2—Zn1—N2^i	89.42 (14)	C3—C11—H11A	109.5
O2—S1—O3	115.04 (16)	C3—C11—H11B	109.5
O2—S1—O1	112.20 (17)	H11A—C11—H11B	109.5
O3—S1—O1	113.95 (17)	C3—C11—H11C	109.5
O2—S1—S2	107.08 (13)	H11A—C11—H11C	109.5
O3—S1—S2	100.03 (12)	H11B—C11—H11C	109.5
O1—S1—S2	107.26 (10)	C8—C12—H12A	109.5
S2^i—S2—S1	103.49 (7)	C8—C12—H12B	109.5
S1—O1—Zn1	155.98 (15)	H12A—C12—H12B	109.5
C1—N1—C5	117.7 (3)	C8—C12—H12C	109.5
C1—N1—Zn1	126.2 (2)	H12A—C12—H12C	109.5
C5—N1—Zn1	116.0 (2)	H12B—C12—H12C	109.5
C10—N2—C6	117.4 (3)	C15—N3—C13	121.4 (4)
C10—N2—Zn1	126.9 (2)	C15—N3—C14	121.1 (3)
C6—N2—Zn1	115.47 (19)	C13—N3—C14	117.5 (4)
N1—C1—C2	123.2 (3)	N3—C13—H13A	109.5
N1—C1—H1	118.4	N3—C13—H13B	109.5
C2—C1—H1	118.4	H13A—C13—H13B	109.5
C1—C2—C3	119.9 (3)	N3—C13—H13C	109.5
C1—C2—H2	120.1	H13A—C13—H13C	109.5
C3—C2—H2	120.1	H13B—C13—H13C	109.5
C2—C3—C4	116.9 (3)	N3—C14—H14A	109.5
C2—C3—C11	122.4 (3)	N3—C14—H14B	109.5
C4—C3—C11	120.8 (3)	H14A—C14—H14B	109.5
C5—C4—C3	120.6 (3)	N3—C14—H14C	109.5
C5—C4—H4	119.7	H14A—C14—H14C	109.5
C3—C4—H4	119.7	H14B—C14—H14C	109.5
N1—C5—C4	121.6 (3)	O4—C15—N3	125.9 (4)
N1—C5—C6	115.8 (3)	O4—C15—H15	117.1
C4—C5—C6	122.6 (3)	N3—C15—H15	117.1
N2—C6—C7	122.0 (3)

Symmetry code: (i) −x+1, y, −z+1/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···O3^ii	0.93	2.49	3.411 (4)	170
C7—H7···O3^ii	0.93	2.46	3.381 (4)	171
C10—H10···O4	0.93	2.47	3.250 (5)	142
C11—H11C···O2^iii	0.96	2.55	3.479 (5)	163
C12—H12A···O3^iv	0.96	2.55	3.465 (5)	160
C13—H13C···O4^v	0.96	2.59	3.525 (5)	166

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