catena-Poly[[aqua­(3,4,7,8-tetra­methyl-1,10-phenanthroline-[kappa]²N,N')cadmium(II)]-[mu]₃-thio­sulfato-[kappa]³S:S:O]

The title compound, [Cd(S₂O₃)(C₁₆H₁₆N₂)(H₂O)]_n, presents a polymeric one-dimensional structure running along the P2₁/c glide direction, with elementary units defined by six-coordinate Cd^II atoms bonded to three symmetry-related thio­sulfate groups, a bidentate tetra­methyl­phenanthroline ligand and one aqua ligand. The bridging thio­sulfates bind metal centers through two different sequences, viz. Cd-S-Cd' and Cd'-S'-S'-O'-Cd, defining a closed six-membered ring. Individual chains are held together via [pi]-[pi] inter­actions to generate two-dimensional networks parallel to the (100) plane. These, in turn, are connected by much weaker van der Waals inter­actions.

S1. Comment

As a part of a general study of metal complexes incorporating sulfur oxoanions, we describe here the structure of Cd(tmph)(S₂O₃)(H₂O), (I) (tmph is 3,4,7,8-tetramethyl-1,10-phenanthroline). Fig. 1 presents a molecular diagram showing general features of the structure, as well as the labeling scheme used. The metal atom has a distorted six-coordinate environment, provided by the two N atoms of a chelating tmph ligand, one O atom from an aqua molecule and three atoms provided by three different symmetry-related thiosulfate anions, through one O atom and the terminal S atoms acting in a bridging mode.

The distorted coordination polyhedron can be described as an asymmetrically elongated octahedron, having atoms N1, N2, O1W and S1 as the basal plane [the mean deviation from the plane is 0.08 (1) Å], with atom Cd1 deviating by 0.44 (1) Å towards the apical site S1ⁱⁱ and with O3ⁱ—Cd1—S1ⁱⁱ as the slightly deformed apical axis [177.15 (8)°; symmetry codes: (i) x, 1/2 − y, 1/2 + z; (ii) x, 1/2 − y, z − 1/2]. The Cd1—S1ⁱⁱ,O3ⁱ vectors subtend angles of 4.5 (1) and 6.3 (1)°, respectively, to the plane normal.

Tmph has been previously reported as a ligand to Ti, W and Mo [refcodes LASDUE, MELGIT, MELGOZ, MELGUF and MELHAM in the November 2004 release of the Cambridge Structural Database (CSD; Allen, 2002)] and we have recently presented (Díaz de Vivar et al., 2004) a close Zn relative to (I), Zn(tmph)(H₂O)₄·(S₂O₃), where the anion does not coordinate but acts as a charge-balance counter-ion. No structures containing the Cd(tmph) group have been reported. The tmph ligand appears absolutely planar within experimental error [the mean deviation from the least-squares plane is 0.011 (6) Å] and binds to the cation in a slightly slanted way, the CdN₂ group subtending a 5.2 (1)° angle to the ligand mean plane.

The Cd—N_tmph bonds are slightly asymmetric (2.1% difference), and this percentage is somewhat larger than the mean value found for the 244 other cadmium complexes with aromatic amines reported in the CSD [Δ(%): 0.4 (4)]. The remaining parameters of the tmph coordination fall well within the reported range [viz. mean Cd—N = 2.356 (41) and 2.316 (24) Å, and mean N—Cd—N = 70.4 (4) and 71.66 (14)°, for the CSD and this work, respectively].

The thiosulfate unit binds to three different Cd centers; atom S1 acts as a direct bridge between two of them, and the third is linked via atom O3. This coordination mode for thiosulfate corresponds to type 6 in the classification presented by Freire et al. (2000), and it seems to be a preferred coordination mode for the anion in Cd complexes, as it has been found to coordinate this way in four out of seven other Cd–thiosulfate complexes reported in the CSD (Baggio et al., 1997, 1998; Freire et al., 2001; Harvey et al., 2004). In contrast to the general trend of internal S—O distances bearing an inverse relationship to the degree of coordination involvement displayed by the corresponding O atom, O2 (not directly bound to cadmium, though an acceptor of two strong hydrogen bonds; see Table 3) does present a longer S—O distance than the (weakly) bound atom O3.

The result of the multiple coordination of the thiosulfate anion is the formation of chains parallel to the c glide direction through two different bridging sequences, Cd1—S1—Cd1ⁱ and Cd1ⁱ—S1ⁱ—S2ⁱ—O3ⁱ—Cd1, defining a six-membered closed loop (see Fig. 1). The symmetry element responsible for the repetition scheme is the glide plane c, which bisects the sequence alongside.

Chains in transition metal complexes with thiosulfate ligands are not unusual, and translational operations promoting them aer diverse; in some cases they are built up along a short cell axis through a unit cell translation (viz. CSD codes WIPNEP and XORWOQ), sometimes with imbedded symmetry centers (as in PAHTAU); they may evolve along a twofold screw axis (as in INIZEK, NUTLUV and RAVLUV) or have glide planes as generators (as in ETUZNT, MIPWAJ and the present structure).

The fact that the C13···C16 transversal axis in tmph is not parallel but oblique to the c glide plane, with one of its outermost methyl groups almost `touching' the plane [atom C16 lays at 0.87 (1) Å] has the effect of clustering symmetry-related tmph groups at one side of the chain, defining some kind of a `hydrophobic column' (a non-active zone for hydrogen-bonding interactions, zone `A' in Fig. 2). The thiosulfate groups and the aqua molecules, on the other hand, pile themselves at the opposite side, in a contrasting hydrophilic, or hydrogen-bonding active, region (zone `B' in Fig. 2). In fact the two hydrogen bonds (Table 2) present in the structure, both of them internal to the chain, evolve in this zone, joining symmetry-related water molecules and O2 atoms in the thiosulfate groups in a sort of continuous threading (Fig. 1).

The `double-column' chains are related to one another by external inversion centers; those symmetry elements at x = 0 and 1 promote the nearest approach of (inverted) neighboring chains, with the effect that consecutive `type-B' columns slide sideways into each other along the b axis with their bulky tmph groups filling neighboring voids in a classical `gear-like' fitting. As a result, parallel aromatic cycles lie at a graphitic distance from one another, thus giving rise to the π–π interactions that link the chains together (Fig. 2 and Table 3). The result is a two-dimensional structure parallel to (100). These broad planes are repeated along the a axis in such a way as to confront `type A' zones with `type B' zones, at a rather long non-interacting distance (typical values H_methyl···O_thiosulfate > 2.70 Å; Fig. 2)

S2. Experimental

The title compound was obtained by allowing a 96% ethanol solution of 3,4,7,8-tetramethyl-1,10-phenanthroline to diffuse into an equimolar aqueous solution containing cadmium acetate and sodium thiosulfate (5 ml of each solution, all concentrations being 0.025 M). After two months, a few colorless needles suitable for X-ray analyses were obtained.

S3. Refinement

H atoms attached to C atoms were placed at calculated positions (C—H_aromatic = 0.93 Å and C—H_methyl = 0.96 Å) and allowed to ride. Methyl groups were also allowed to rotate around the C—C axis. H atoms of water molecules were located from difference Fourier maps and refined with restrained O—H distances [0.85 (2) Å]. U_iso(H) values were set at xU_eq(host), with x = 1.2 for aromatic and water H atoms and x = 1.5 for methyl H atoms.

Computing details

Data collection: SMART-NT (Bruker, 2001); cell refinement: SAINT-NT (Bruker, 2000); data reduction: SAINT-NT; 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

	Fig. 1. A displacement ellipsoid plot (40% probability level) of the dimeric units in (I). Only the independent moiety is drawn in full ellipsoids. Internal hydrogen bonds are shown as broken lines. The way in which planar tmph groups interdigitate is suggested. [Symmetry codes as in Table 1.]
	Fig. 2. A packing diagram of (I), viewed down the c axis, showing the way in which planes parallel to (100) build up. Adjacent interdigitated columns have been drawn in alternating colors (black/grey) for clarity.

catena-Poly[[aqua(3,4,7,8-tetramethyl-1,10-phenanthroline- κ²N,N')cadmium(II)]-µ₃-thiosulfato-κ³S:S:O]

Crystal data

[Cd(S2O3)(C16H16N2)(H2O)]	F(000) = 960
Mr = 478.84	Dx = 1.894 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1520 reflections
a = 11.086 (2) Å	θ = 5.3–47.4°
b = 21.846 (5) Å	µ = 1.57 mm^−1
c = 7.2000 (15) Å	T = 297 K
β = 105.615 (4)°	Plate, colorless
V = 1679.4 (6) Å^3	0.27 × 0.09 × 0.04 mm
Z = 4

Data collection

Bruker CCD area-detector diffractometer	3818 independent reflections
Radiation source: fine-focus sealed tube	2868 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.064
ϕ and ω scans	θmax = 28.1°, θmin = 1.9°
Absorption correction: multi-scan [SADABS (Sheldrick, 1996) in SAINT-NT (Bruker, 2000)]	h = −14→13
Tmin = 0.82, Tmax = 0.94	k = −28→28
13727 measured reflections	l = −9→9

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)] = 0.058	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.110	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ^2(Fo^2) + (0.044P)^2] where P = (Fo^2 + 2Fc^2)/3
3818 reflections	(Δ/σ)max = 0.002
238 parameters	Δρmax = 0.82 e Å^−3
9 restraints	Δρmin = −0.64 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
Cd1	0.21821 (3)	0.177844 (17)	0.26774 (6)	0.02836 (14)
S1	0.18986 (12)	0.28725 (6)	0.40571 (19)	0.0276 (3)
S2	0.31287 (12)	0.34086 (6)	0.30477 (19)	0.0245 (3)
O1	0.3514 (4)	0.38946 (17)	0.4426 (5)	0.0377 (9)
O2	0.4185 (3)	0.30215 (16)	0.2916 (5)	0.0316 (9)
O3	0.2431 (4)	0.36164 (17)	0.1142 (5)	0.0365 (9)
O1W	0.4331 (3)	0.18414 (17)	0.4073 (6)	0.0329 (9)
H1WA	0.448 (6)	0.2190 (13)	0.364 (7)	0.07 (2)*
H1WB	0.434 (6)	0.185 (2)	0.526 (3)	0.06 (2)*
N1	0.2092 (4)	0.07311 (19)	0.2503 (5)	0.0232 (9)
N2	0.0114 (4)	0.1475 (2)	0.2379 (6)	0.0277 (10)
C1	0.3067 (5)	0.0371 (2)	0.2626 (7)	0.0280 (12)
H1	0.3831	0.0553	0.2663	0.034*
C2	0.3020 (5)	−0.0266 (3)	0.2702 (7)	0.0341 (14)
C3	0.1899 (5)	−0.0546 (2)	0.2658 (7)	0.0307 (13)
C4	0.0840 (5)	−0.0165 (2)	0.2553 (7)	0.0285 (12)
C5	−0.0355 (6)	−0.0407 (3)	0.2514 (8)	0.0371 (14)
H5	−0.0456	−0.0829	0.2562	0.045*
C6	−0.1349 (5)	−0.0037 (3)	0.2408 (7)	0.0347 (13)
H6	−0.2122	−0.0211	0.2363	0.042*
C7	−0.1243 (5)	0.0613 (2)	0.2365 (7)	0.0291 (12)
C8	−0.2262 (5)	0.1014 (3)	0.2244 (7)	0.0306 (12)
C9	−0.2052 (5)	0.1637 (3)	0.2193 (8)	0.0329 (13)
C10	−0.0853 (5)	0.1838 (3)	0.2276 (7)	0.0322 (12)
H10	−0.0720	0.2258	0.2257	0.039*
C11	−0.0073 (4)	0.0864 (2)	0.2415 (6)	0.0228 (11)
C12	0.0987 (5)	0.0467 (2)	0.2495 (7)	0.0222 (11)
C13	0.4222 (6)	−0.0624 (3)	0.2882 (9)	0.0472 (16)
H13A	0.4087	−0.0926	0.1877	0.071*
H13B	0.4465	−0.0824	0.4115	0.071*
H13C	0.4875	−0.0350	0.2768	0.071*
C14	0.1794 (6)	−0.1227 (2)	0.2718 (8)	0.0435 (15)
H14A	0.2543	−0.1409	0.2541	0.065*
H14B	0.1086	−0.1359	0.1707	0.065*
H14C	0.1685	−0.1349	0.3943	0.065*
C15	−0.3525 (5)	0.0760 (3)	0.2205 (9)	0.0440 (16)
H15A	−0.4138	0.1081	0.1901	0.066*
H15B	−0.3502	0.0591	0.3445	0.066*
H15C	−0.3745	0.0445	0.1244	0.066*
C16	−0.3085 (6)	0.2100 (3)	0.2069 (10)	0.0537 (18)
H16A	−0.2755	0.2506	0.2062	0.081*
H16B	−0.3418	0.2053	0.3161	0.081*
H16C	−0.3739	0.2034	0.0904	0.081*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.0237 (2)	0.0232 (2)	0.0385 (2)	−0.00350 (17)	0.00881 (16)	0.00047 (18)
S1	0.0306 (7)	0.0243 (7)	0.0319 (7)	−0.0040 (6)	0.0155 (6)	−0.0029 (6)
S2	0.0282 (7)	0.0219 (7)	0.0251 (7)	0.0000 (5)	0.0098 (5)	0.0000 (5)
O1	0.047 (2)	0.033 (2)	0.036 (2)	−0.0120 (18)	0.0163 (18)	−0.0110 (18)
O2	0.026 (2)	0.031 (2)	0.040 (2)	0.0024 (16)	0.0141 (17)	0.0019 (17)
O3	0.049 (2)	0.034 (2)	0.029 (2)	0.0141 (18)	0.0137 (18)	0.0091 (17)
O1W	0.029 (2)	0.035 (2)	0.037 (3)	0.0016 (18)	0.0123 (18)	0.0023 (19)
N1	0.022 (2)	0.028 (2)	0.018 (2)	0.0001 (19)	0.0033 (17)	0.0007 (18)
N2	0.026 (2)	0.029 (2)	0.030 (2)	−0.003 (2)	0.0094 (19)	0.000 (2)
C1	0.024 (3)	0.034 (3)	0.025 (3)	0.000 (2)	0.006 (2)	0.003 (2)
C2	0.049 (4)	0.034 (3)	0.020 (3)	0.009 (3)	0.010 (3)	0.002 (2)
C3	0.045 (4)	0.026 (3)	0.020 (3)	0.001 (2)	0.007 (2)	−0.001 (2)
C4	0.040 (3)	0.027 (3)	0.018 (3)	−0.006 (2)	0.007 (2)	0.001 (2)
C5	0.048 (4)	0.029 (3)	0.034 (3)	−0.012 (3)	0.010 (3)	−0.001 (2)
C6	0.036 (3)	0.037 (3)	0.031 (3)	−0.013 (3)	0.009 (3)	−0.004 (3)
C7	0.023 (3)	0.040 (3)	0.024 (3)	−0.012 (2)	0.004 (2)	−0.004 (2)
C8	0.022 (3)	0.047 (4)	0.022 (3)	−0.003 (3)	0.006 (2)	0.002 (2)
C9	0.029 (3)	0.042 (4)	0.031 (3)	0.004 (2)	0.014 (2)	0.002 (3)
C10	0.030 (3)	0.032 (3)	0.035 (3)	0.003 (2)	0.009 (2)	0.002 (2)
C11	0.026 (3)	0.024 (3)	0.017 (3)	−0.004 (2)	0.003 (2)	0.000 (2)
C12	0.026 (3)	0.024 (3)	0.014 (2)	−0.003 (2)	0.002 (2)	0.000 (2)
C13	0.056 (4)	0.040 (4)	0.046 (4)	0.015 (3)	0.013 (3)	0.003 (3)
C14	0.064 (4)	0.029 (3)	0.038 (3)	0.002 (3)	0.014 (3)	0.003 (3)
C15	0.027 (3)	0.064 (4)	0.042 (4)	−0.013 (3)	0.011 (3)	0.010 (3)
C16	0.038 (4)	0.049 (4)	0.077 (5)	0.007 (3)	0.022 (3)	0.009 (4)

Geometric parameters (Å, º)

Cd1—N1	2.292 (4)	C5—C6	1.352 (8)
Cd1—O1W	2.327 (4)	C5—H5	0.9300
Cd1—N2	2.340 (4)	C6—C7	1.425 (7)
Cd1—O3^i	2.583 (4)	C6—H6	0.9300
Cd1—S1	2.6394 (14)	C7—C11	1.400 (7)
Cd1—S1^ii	2.6521 (14)	C7—C8	1.414 (7)
S1—S2	2.0719 (18)	C8—C9	1.383 (8)
S2—O1	1.438 (4)	C8—C15	1.500 (7)
S2—O3	1.454 (4)	C9—C10	1.386 (7)
S2—O2	1.468 (4)	C9—C16	1.511 (8)
O1W—H1WA	0.86 (4)	C10—H10	0.9300
O1W—H1WB	0.85 (3)	C11—C12	1.449 (7)
N1—C1	1.321 (6)	C13—H13A	0.9600
N1—C12	1.352 (6)	C13—H13B	0.9600
N2—C10	1.319 (6)	C13—H13C	0.9600
N2—C11	1.354 (6)	C14—H14A	0.9600
C1—C2	1.393 (7)	C14—H14B	0.9600
C1—H1	0.9300	C14—H14C	0.9600
C2—C3	1.378 (8)	C15—H15A	0.9600
C2—C13	1.522 (7)	C15—H15B	0.9600
C3—C4	1.426 (7)	C15—H15C	0.9600
C3—C14	1.492 (7)	C16—H16A	0.9600
C4—C12	1.392 (7)	C16—H16B	0.9600
C4—C5	1.420 (7)	C16—H16C	0.9600
N1—Cd1—O1W	96.15 (14)	C6—C5—H5	119.3
N1—Cd1—N2	71.66 (14)	C4—C5—H5	119.3
O1W—Cd1—N2	156.96 (15)	C5—C6—C7	121.7 (5)
N1—Cd1—O3^i	73.21 (12)	C5—C6—H6	119.2
O1W—Cd1—O3^i	76.81 (13)	C7—C6—H6	119.2
N2—Cd1—O3^i	80.89 (13)	C11—C7—C8	118.6 (5)
N1—Cd1—S1	156.44 (10)	C11—C7—C6	118.1 (5)
O1W—Cd1—S1	89.76 (10)	C8—C7—C6	123.4 (5)
N2—Cd1—S1	94.46 (11)	C9—C8—C7	118.3 (5)
O3^i—Cd1—S1	86.07 (9)	C9—C8—C15	121.9 (5)
N1—Cd1—S1^ii	103.97 (10)	C7—C8—C15	119.8 (5)
O1W—Cd1—S1^ii	104.12 (10)	C8—C9—C10	118.5 (5)
N2—Cd1—S1^ii	97.89 (11)	C8—C9—C16	121.9 (5)
O3^i—Cd1—S1^ii	177.15 (8)	C10—C9—C16	119.6 (5)
S1—Cd1—S1^ii	96.60 (3)	N2—C10—C9	124.5 (5)
S2—S1—Cd1	102.92 (6)	N2—C10—H10	117.7
S2—S1—Cd1^i	105.50 (6)	C9—C10—H10	117.7
Cd1—S1—Cd1^i	129.47 (5)	N2—C11—C7	122.1 (5)
O1—S2—O3	113.9 (2)	N2—C11—C12	117.6 (4)
O1—S2—O2	112.1 (2)	C7—C11—C12	120.3 (5)
O3—S2—O2	110.5 (2)	N1—C12—C4	122.4 (5)
O1—S2—S1	106.06 (16)	N1—C12—C11	118.0 (4)
O3—S2—S1	105.92 (17)	C4—C12—C11	119.6 (5)
O2—S2—S1	107.99 (16)	C2—C13—H13A	109.5
S2—O3—Cd1^ii	134.3 (2)	C2—C13—H13B	109.5
Cd1—O1W—H1WA	100 (5)	H13A—C13—H13B	109.5
Cd1—O1W—H1WB	99 (4)	C2—C13—H13C	109.5
H1WA—O1W—H1WB	113 (3)	H13A—C13—H13C	109.5
C1—N1—C12	118.1 (5)	H13B—C13—H13C	109.5
C1—N1—Cd1	124.6 (3)	C3—C14—H14A	109.5
C12—N1—Cd1	116.9 (3)	C3—C14—H14B	109.5
C10—N2—C11	117.9 (4)	H14A—C14—H14B	109.5
C10—N2—Cd1	126.6 (4)	C3—C14—H14C	109.5
C11—N2—Cd1	115.4 (3)	H14A—C14—H14C	109.5
N1—C1—C2	123.9 (5)	H14B—C14—H14C	109.5
N1—C1—H1	118.0	C8—C15—H15A	109.5
C2—C1—H1	118.0	C8—C15—H15B	109.5
C3—C2—C1	119.1 (5)	H15A—C15—H15B	109.5
C3—C2—C13	122.4 (5)	C8—C15—H15C	109.5
C1—C2—C13	118.4 (5)	H15A—C15—H15C	109.5
C2—C3—C4	117.7 (5)	H15B—C15—H15C	109.5
C2—C3—C14	121.3 (5)	C9—C16—H16A	109.5
C4—C3—C14	120.9 (5)	C9—C16—H16B	109.5
C12—C4—C5	119.0 (5)	H16A—C16—H16B	109.5
C12—C4—C3	118.7 (5)	C9—C16—H16C	109.5
C5—C4—C3	122.3 (5)	H16A—C16—H16C	109.5
C6—C5—C4	121.4 (5)	H16B—C16—H16C	109.5

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WB···O2^i	0.85 (3)	1.98 (3)	2.831 (5)	172 (6)
O1W—H1WA···O2	0.86 (4)	1.89 (3)	2.701 (5)	157 (6)
C14—H14B···Cg2^iii	0.96	2.90	3.492 (6)	121
C14—H14C···Cg2^iv	0.96	2.97	3.877 (6)	159

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