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In the novel title six-coordinate cadmium complex, [Cd(S2O3)(C12H8N2)]n, the anion binds to three different six-coordinate cationic centres through all four external atoms, an unprecedented coordination mode for thio­sulfate metal-organic complexes. This connectivity leads to strongly linked dimers, connected to form interleaved double chains, which in turn interact through remarkably short π–π bonds between their phenanthroline groups.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104019638/ga1075sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270104019638/ga1075Isup2.hkl
Contains datablock I

CCDC reference: 254901

Comment top

Complexes of group XII metals containing sulfur oxoanions have been of interest to us for many years, and as a result we have prepared a large number of compounds having thiosulfate, sulfate, peroxodisulfate and, to a lesser extent, sulfite as ligands. Many of these complexes exhibit novel modes of coordination, as expected from the characteristics of the cations (Zn2+, Cd2+ and Hg2+) as well as the versatility of the anions involved. The use of less common sulfur oxoanions, such as dithionite and pyrosulfite, though highly desirable as a natural continuation of this line of work, appeared to be impaired by the instability of these anions in solution. Transformation products can be expected when interacting with transition metal ions and organic ligands (Remy, 1956). As an example, sodium dithionite, though basically stable in the solid state, decomposes easily in solution, giving thiosulfate and pyrosulfite. On the other hand, the chemistry in solution of the latter is essentially the chemistry of SO32− and HSO3 ions, even though the formal oxidation numbers SIII and SV are those that would be expected in the solid state.

This high anionic instability, which makes the chemistry of sulfur oxoanions so difficult, also makes them attractive as precursors in the synthesis of sulfite and thiosulfate complexes. Some previously unintentional outcomes in our synthetic attempts (Harvey, 2004) strongly suggested that sulfur oxoanions could provide feasible alternative routes where direct syntheses had previously proven unsuccessful, or provide a way to produce different crystallographic phases from those already obtained either from conventional methods or even by similar decomposition procedures. We present here one such case, a novel anhydrous six-coordinate cadmium phenanthroline thiosulfate, viz. the title compound, (I), which is crystallographically different from a recently published five-coordinate form with the same formula [hereafter (II); Harvey, 2004]. Both forms were obtained by essentially the same procedure, under slightly different conditions (See Experimental).

Fig. 1 shows a molecular diagram of the structure, with the atom labelling scheme; the bonds to the six-coordinate Cd centre come from four different ligands, viz. atoms N1 and N2 from the chelating phenanthroline (phen) ligand, atom O2' from the thiosulfate anion at (-x + 1,-y + 1,-z + 1), atom O3" from the thiosulfate anion at (x + 1,y,z), and atoms S1 and O1 from the anion at its reference place, acting in a chelating mode. The latter Cd—O bond is worth analyzing. It is far longer than average (Cd—O1 = 2.788 (4) Å versus a mean of 2.317 (4) Å for the other two Cd—O bonds), but though unusual it is not unprecedented; a number of such long Cd—O bonds are reported in the literature, and a search of the Cambridge Structural Database (CSD; Allen, 2002) produced 32 cases of Cd—O bonds longer than 2.788 Å, out of a total number of ca 5000 bonds?, spanning the range 1.959–3.052 Å. To clarify definitively the coordinating character of this interaction, we carried out a bond valence calculation comparing (I) with its five-coordinate isomer (II). The valence sum around the cation in the latter gave 2.012 electrons, while the same calculation for (I) gave 1.925 electrons when atom O1 was excluded from the calculation and 2.016 electrons when it was included. Although rather weak, the involvement of atom O1 in coordination is therefore confirmed. The highly distorted coordination polyhedron could be described as an asymmetrically elongated octahedron, having atoms S1, N1, O1 and O3" as the basal plane [the mean deviation from the plane is 0.24 (1) Å, leaving Cd 0.06 (1) Å aside?] and N2—Cd—O2' as the apical axis [the deviations from the plane normal are 17.2 (1)° for N2—Cd and 16.8 (1)° for O2'—Cd]. The phen unit is slightly concave in shape, the central ring subtending angles of 4.3 (1) and 2.2 (1)° with the lateral ones, which deformation results in an average deviation from planarity of 0.047 (1) Å.

Uniquely, the thiosulfate ligand binds through its four external atoms to three different metal centers in a new coordination mode in transition metal thiosulfate complexes (scheme 1, ninth entry), which thus adds to the eight different modes already known [scheme 1, entries 1–8; see Freire et al. (2000), where references for the corresponding structures can be obtained]. Another peculiarity of the anion in (I) is that the terminal S atom is singly coordinated and does not enter into formation of any direct M—S—M bridge; this behaviour is unprecedented for cadmium thiosulfates, irrespective of character (metallorganic or inorganic) or coordination number (five- or six-coordinate). In all previous examples, the five-coordinate isomer (II) (Harvey, 2004), Cd(S2O3)(C10H8N2)], (III) (Baggio, Pardo, Baggio & Garland,1997), Cd2(S2O3)2(C14H12N2)2, (IV) (Baggio et al., 1996), Cd(S2O3)(C10H9N3)(H2O)·H2O, (V) (Freire, 2001), Cd(S2O3)(C12H8N2)(H2O)]·H2O, (VI) (Baggio, 1998), and CdS2O3·2H2O, (VII) (Baggio, Pardo, Baggio & Gonzalez, 1997), the terminal S1 atom bridges two different metal centers. The thiosulfate ion exhibits an almost ideal C3v geometry, with S—O distances and S—S—O angles being indistinguishable within experimental errors. The coordination environemnt of the S atoms results in the expected lengthening of the S—S bond with respect to that of the free anion [2.045 (2) Å versus 1.99–2.02 Å; Teng et al., 1984, and references therein].

The special coordination mode of the anion results in five long different three-atom-length bridges (O2—S2—S1, O2—S2—O1, O3—S2—S1, O3—S2—O1, and O2'—S2'—O3'; Fig. 1), which, along with their symmetry-related bridges, connect the cation to its four nearest neighbours. Those bridges in which atom O3 does not take part lead to the formation of strongly linked dimers through a `cage' built up around the symmetry center at (1/2,1/2,1/2) (upper half of Fig. 1). The sharing of atom O3 by these dimers shifted by one unit cell along <100> generates eight-membered loops, which serve to join dimers together into polymeric structures in the shape of double chains. In spite of the structure core being different from those previously reported in metal-organic thiosulfates, the outermost part is basically similar, with the aromatic amines protruding outwards and interleaving into each other in a gear-like fashion (Fig. 2), with an important partial overlap of neighbouring rings. The ππ interactions arising from this setup are relatively strong, leading to interplanar distances (distances from a ring center to the opposite ring's plane) of 3.20 (1) and 3.27 (1) Å, with slippage angles (angles subtended by the vector joining a ring center to one of the planes of the ring) of 24 (1) and 21 (1)°, respectively. This contact seemed to be unusually short for this type of intermolecular interaction without other enhancing interactions. To evaluate this situation, we searched the CSD for structures containing strong `intermolecular' interactions, characterized by having nearly parallel aromatic cycles (the maximum allowed interplanar dihedral angle was 5°), with a maximum center-to-plane distance of 3.40 Å and a maximum slippage angle of 30°. The search provided a total of 340 such cases, of which less than 5% of the total were shorter than the 3.20 (1) Å found in (I) [the minimum values found were 3.17 Å and 26° for CSD refcode HUPZIB (Kingston et al., 2003)]. When the same search was performed allowing any type of interaction (either intra- or intermolecular) this fraction rose to 25% of the total.

In summary, complex (I), synthesized through non-conventional methods, presents a new coordination scheme for the thiosulfate anion. It serves as an efficient connector between cationic centers, and as a result strongly linked two-dimensional structures can be built up. These interact with one another through ππ contacts that are found to be among the strongest intermolecular contacts of that type reported.

Experimental top

The compound was obtained by dissolving Cd acetate and phenanthroline (molar ratio 1:1) in ethanol at 96° and allowing this solution to diffuse slowly into an aqueous solution of Na2S2O4·2H2O and K2S2O5 (molar ratio 1:2). After two months, small colorless prisms suitable for X-ray analysis had developed.

Refinement top

H atoms in the structure were all defined by the stereochemistry and were accordingly placed at calculated positions and treated as riding on their host atoms (C—H = 0.93 Å), with Uiso(H) values of 1.2Ueq(C).

Computing details top

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: MSC/AFC Diffractometer Control Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL/PC (Sheldrick,1994); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. : A displacement ellipsoid plot (50% probability level) showing the polymeric unit of (I). The independent part of the structure is shown with full displacement ellipsoids. [Symmetry codes: (') −x + 1,-y + 1,-z + 1; (") x + 1,y,z.]
[Figure 2] Fig. 2. : The packing of the structure, showing the interleaving of the phenanthroline groups.
poly[[(1,10-phenanthroline-κ2N,N')cadmium(II)]-µ-thiosulfato] top
Crystal data top
[Cd(S2O3)(C12H8N2)]Z = 2
Mr = 404.72F(000) = 396
Triclinic, P1Dx = 2.191 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 6.4860 (13) ÅCell parameters from 25 reflections
b = 9.2530 (19) Åθ = 7.5–15°
c = 10.621 (2) ŵ = 2.13 mm1
α = 76.58 (3)°T = 293 K
β = 83.52 (3)°Prisms, colorless
γ = 83.50 (3)°0.35 × 0.12 × 0.10 mm
V = 613.6 (2) Å3
Data collection top
Rigaku AFC-6S
diffractometer
1913 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.035
Graphite monochromatorθmax = 28.5°, θmin = 2.0°
ω/2θ scansh = 88
Absorption correction: ψ scan
(North et al., 1968)
k = 120
Tmin = 0.74, Tmax = 0.80l = 1313
3025 measured reflections3 standard reflections every 150 reflections
2853 independent reflections intensity decay: 0.9%
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.037Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.097H-atom parameters constrained
S = 0.98 w = 1/[σ2(Fo2) + (0.0478P)2]
where P = (Fo2 + 2Fc2)/3
2853 reflections(Δ/σ)max = 0.008
181 parametersΔρmax = 0.98 e Å3
0 restraintsΔρmin = 1.20 e Å3
Crystal data top
[Cd(S2O3)(C12H8N2)]γ = 83.50 (3)°
Mr = 404.72V = 613.6 (2) Å3
Triclinic, P1Z = 2
a = 6.4860 (13) ÅMo Kα radiation
b = 9.2530 (19) ŵ = 2.13 mm1
c = 10.621 (2) ÅT = 293 K
α = 76.58 (3)°0.35 × 0.12 × 0.10 mm
β = 83.52 (3)°
Data collection top
Rigaku AFC-6S
diffractometer
1913 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)
Rint = 0.035
Tmin = 0.74, Tmax = 0.803 standard reflections every 150 reflections
3025 measured reflections intensity decay: 0.9%
2853 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0370 restraints
wR(F2) = 0.097H-atom parameters constrained
S = 0.98Δρmax = 0.98 e Å3
2853 reflectionsΔρmin = 1.20 e Å3
181 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
Cd0.70305 (6)0.35914 (5)0.68567 (4)0.02050 (13)
S10.4077 (2)0.53823 (16)0.74780 (14)0.0251 (3)
S20.2125 (2)0.46289 (15)0.64365 (12)0.0185 (3)
O10.3147 (7)0.3260 (5)0.6123 (5)0.0355 (10)
O20.1755 (6)0.5804 (4)0.5283 (4)0.0277 (9)
O30.0169 (6)0.4379 (5)0.7259 (4)0.0273 (9)
N10.7388 (7)0.1213 (5)0.6481 (4)0.0222 (10)
N20.7269 (7)0.1858 (5)0.8874 (4)0.0222 (10)
C10.7322 (9)0.0904 (7)0.5325 (6)0.0264 (12)
H1A0.71210.16900.46110.032*
C20.7540 (9)0.0545 (7)0.5140 (6)0.0298 (13)
H2A0.74530.07160.43200.036*
C30.7882 (9)0.1719 (7)0.6168 (6)0.0273 (13)
H3A0.80860.26900.60460.033*
C40.7920 (8)0.1437 (6)0.7423 (5)0.0223 (11)
C50.8143 (9)0.2597 (6)0.8570 (6)0.0294 (13)
H5A0.83860.35840.84950.035*
C60.8008 (8)0.2283 (6)0.9751 (6)0.0249 (12)
H6A0.81200.30571.04820.030*
C70.7697 (8)0.0780 (6)0.9897 (5)0.0222 (11)
C80.7498 (8)0.0385 (7)1.1115 (6)0.0263 (12)
H8A0.75870.11271.18720.032*
C90.7174 (8)0.1085 (7)1.1191 (5)0.0274 (13)
H9A0.70090.13471.19930.033*
C100.7097 (8)0.2176 (7)1.0043 (6)0.0259 (12)
H10A0.69170.31731.00960.031*
C110.7551 (7)0.0409 (6)0.8793 (5)0.0181 (10)
C120.7644 (8)0.0069 (6)0.7535 (5)0.0206 (11)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cd0.0192 (2)0.0186 (2)0.0217 (2)0.00028 (14)0.00074 (14)0.00178 (14)
S10.0209 (7)0.0279 (7)0.0291 (7)0.0012 (6)0.0053 (6)0.0109 (6)
S20.0183 (6)0.0189 (6)0.0169 (6)0.0022 (5)0.0020 (5)0.0009 (5)
O10.038 (2)0.027 (2)0.044 (3)0.0048 (19)0.009 (2)0.016 (2)
O20.028 (2)0.030 (2)0.020 (2)0.0056 (17)0.0035 (16)0.0057 (17)
O30.022 (2)0.037 (2)0.022 (2)0.0101 (17)0.0017 (16)0.0033 (18)
N10.021 (2)0.023 (2)0.020 (2)0.0013 (18)0.0020 (18)0.0003 (19)
N20.019 (2)0.025 (2)0.023 (2)0.0041 (18)0.0003 (18)0.007 (2)
C10.028 (3)0.029 (3)0.021 (3)0.006 (2)0.004 (2)0.002 (2)
C20.029 (3)0.041 (3)0.025 (3)0.006 (3)0.001 (2)0.018 (3)
C30.025 (3)0.025 (3)0.037 (3)0.007 (2)0.000 (2)0.016 (3)
C40.018 (3)0.019 (3)0.028 (3)0.002 (2)0.003 (2)0.003 (2)
C50.025 (3)0.017 (3)0.043 (4)0.000 (2)0.001 (3)0.001 (3)
C60.026 (3)0.020 (3)0.027 (3)0.001 (2)0.002 (2)0.000 (2)
C70.015 (2)0.026 (3)0.023 (3)0.001 (2)0.003 (2)0.001 (2)
C80.016 (3)0.036 (3)0.022 (3)0.005 (2)0.002 (2)0.005 (2)
C90.023 (3)0.042 (4)0.019 (3)0.004 (2)0.003 (2)0.011 (3)
C100.019 (3)0.033 (3)0.029 (3)0.005 (2)0.000 (2)0.013 (3)
C110.012 (2)0.022 (3)0.020 (3)0.0016 (19)0.0034 (18)0.004 (2)
C120.015 (2)0.022 (3)0.023 (3)0.004 (2)0.003 (2)0.004 (2)
Geometric parameters (Å, º) top
Cd—O2i2.282 (4)C2—H2A0.9300
Cd—N12.308 (5)C3—C41.419 (8)
Cd—O3ii2.353 (4)C3—H3A0.9300
Cd—N22.368 (5)C4—C121.416 (7)
Cd—S12.5207 (16)C4—C51.433 (8)
Cd—O12.788 (4)C5—C61.343 (8)
S1—S22.0462 (19)C5—H5A0.9300
S2—O11.453 (4)C6—C71.424 (8)
S2—O21.459 (4)C6—H6A0.9300
S2—O31.466 (4)C7—C81.413 (8)
N1—C11.330 (7)C7—C111.413 (7)
N1—C121.361 (7)C8—C91.373 (8)
N2—C101.331 (7)C8—H8A0.9300
N2—C111.354 (7)C9—C101.393 (8)
C1—C21.389 (8)C9—H9A0.9300
C1—H1A0.9300C10—H10A0.9300
C2—C31.368 (9)C11—C121.436 (7)
O2i—Cd—N182.45 (15)C3—C2—C1119.8 (5)
O2i—Cd—O3ii85.51 (14)C3—C2—H2A120.1
N1—Cd—O3ii113.41 (15)C1—C2—H2A120.1
O2i—Cd—N2146.44 (15)C2—C3—C4119.2 (5)
N1—Cd—N271.52 (16)C2—C3—H3A120.4
O3ii—Cd—N285.80 (15)C4—C3—H3A120.4
O2i—Cd—S1113.51 (11)C12—C4—C3117.5 (5)
N1—Cd—S1136.50 (12)C12—C4—C5119.2 (5)
O3ii—Cd—S1108.18 (11)C3—C4—C5123.3 (5)
N2—Cd—S1100.00 (12)C6—C5—C4121.2 (5)
O2i—Cd—O189.40 (14)C6—C5—H5A119.4
N1—Cd—O176.14 (14)C4—C5—H5A119.4
O3ii—Cd—O1168.38 (13)C5—C6—C7120.9 (5)
N2—Cd—O1104.03 (15)C5—C6—H6A119.6
S1—Cd—O164.46 (9)C7—C6—H6A119.6
S2—S1—Cd90.74 (7)C8—C7—C11116.4 (5)
O1—S2—O2112.8 (3)C8—C7—C6123.4 (5)
O1—S2—O3112.1 (3)C11—C7—C6120.2 (5)
O2—S2—O3109.9 (2)C9—C8—C7120.5 (5)
O1—S2—S1107.31 (19)C9—C8—H8A119.8
O2—S2—S1107.29 (18)C7—C8—H8A119.8
O3—S2—S1107.18 (17)C8—C9—C10118.7 (5)
S2—O1—Cd95.6 (2)C8—C9—H9A120.7
S2—O2—Cdi138.8 (3)C10—C9—H9A120.7
S2—O3—Cdiii131.2 (2)N2—C10—C9123.0 (6)
C1—N1—C12119.1 (5)N2—C10—H10A118.5
C1—N1—Cd124.4 (4)C9—C10—H10A118.5
C12—N1—Cd116.5 (4)N2—C11—C7122.8 (5)
C10—N2—C11118.6 (5)N2—C11—C12118.4 (5)
C10—N2—Cd126.5 (4)C7—C11—C12118.8 (5)
C11—N2—Cd114.8 (3)N1—C12—C4121.7 (5)
N1—C1—C2122.6 (5)N1—C12—C11118.6 (5)
N1—C1—H1A118.7C4—C12—C11119.6 (5)
C2—C1—H1A118.7
Symmetry codes: (i) x+1, y+1, z+1; (ii) x+1, y, z; (iii) x1, y, z.

Experimental details

Crystal data
Chemical formula[Cd(S2O3)(C12H8N2)]
Mr404.72
Crystal system, space groupTriclinic, P1
Temperature (K)293
a, b, c (Å)6.4860 (13), 9.2530 (19), 10.621 (2)
α, β, γ (°)76.58 (3), 83.52 (3), 83.50 (3)
V3)613.6 (2)
Z2
Radiation typeMo Kα
µ (mm1)2.13
Crystal size (mm)0.35 × 0.12 × 0.10
Data collection
DiffractometerRigaku AFC-6S
diffractometer
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.74, 0.80
No. of measured, independent and
observed [I > 2σ(I)] reflections
3025, 2853, 1913
Rint0.035
(sin θ/λ)max1)0.671
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.037, 0.097, 0.98
No. of reflections2853
No. of parameters181
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.98, 1.20

Computer programs: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1988), MSC/AFC Diffractometer Control Software, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), XP in SHELXTL/PC (Sheldrick,1994), SHELXL97.

Selected geometric parameters (Å, º) top
Cd—O2i2.282 (4)Cd—O12.788 (4)
Cd—N12.308 (5)S1—S22.0462 (19)
Cd—O3ii2.353 (4)S2—O11.453 (4)
Cd—N22.368 (5)S2—O21.459 (4)
Cd—S12.5207 (16)S2—O31.466 (4)
O2i—Cd—N182.45 (15)N1—Cd—O176.14 (14)
O2i—Cd—O3ii85.51 (14)O3ii—Cd—O1168.38 (13)
N1—Cd—O3ii113.41 (15)N2—Cd—O1104.03 (15)
O2i—Cd—N2146.44 (15)S1—Cd—O164.46 (9)
N1—Cd—N271.52 (16)O1—S2—O2112.8 (3)
O3ii—Cd—N285.80 (15)O1—S2—O3112.1 (3)
O2i—Cd—S1113.51 (11)O2—S2—O3109.9 (2)
N1—Cd—S1136.50 (12)O1—S2—S1107.31 (19)
O3ii—Cd—S1108.18 (11)O2—S2—S1107.29 (18)
N2—Cd—S1100.00 (12)O3—S2—S1107.18 (17)
O2i—Cd—O189.40 (14)
Symmetry codes: (i) x+1, y+1, z+1; (ii) x+1, y, z.
 

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