([mu]-2,11-Dithia­[3.3]paracyclo­phane-[kappa]²S:S')bis­[(6-carboxy­pyridine-2-carboxylato-[kappa]²N,O⁶)silver(I)]: a mixed-ligand silver-based dinuclear compound

In the title complex, [Ag₂(C₇H₄NO₄)₂(C₁₆H₁₆S₂)], each Ag^I atom is trigonally coordinated by one S atom of a 2,11-dithia­[3.3]paracyclo­phane (dtpcp) ligand, and by one N and one O atom of a 6-carboxy­pyridine-2-carboxylate ligand. Dtpcp acts as a bidentate ligand, bridging two inversion-related Ag^I atoms to give a dinuclear silver(I) compound. The dinuclear moieties are inter­connected via O-H...O hydrogen bonds to form a two-dimensional zigzag sheet. Two such sheets are inter­woven via [pi]-[pi] inter­actions between pyridine rings, affording an inter­woven bilayer network.

S1. Comment

The design of inorganic–organic hybrid frameworks, in particular the construction of polymeric silver(I) coordination networks, has become a growing active research area due to the potential application of these polymers as functional materials with controllable properties and novel molecular structures (Khlobystov et al., 2001; Hu et al., 2003; Yaghi & Li, 1996; Zhao et al., 2001). Recent developments in supramolecular chemistry have made it possible to select building blocks to assemble structures with specific networks. Many investigations in this field have been focused on the construction of metal-organic complexes containing N– or S-atom donor ligands. Very recently, attention has been diverted to the complexes based on mixed ligands. We chose here 2,6-pyridinedicarboxylic acid (H₂pdc) with an N-atom donor and 2,11-dithia[3.3]paracyclophane (dtpcp) with an S-atom donor as mixed ligands. Although metal complexes of H₂pdc have been studied extensively because of its ability to form stable chelates (Ducommun, et al., 1989; Sengupta et al., 1983; Zhou & Kostic, 1988), the structural characterization of its silver(I) complexes is very rare (Wang et al., 2004). On the other hand, reports on polymeric silver(I) complexes of thia-bridged paracyclophane are also very sparse (Munakata et al., 1996; Liu et al., 2004a,b). We report here the crystal structure of the title compound, [Ag₂(dtpcp)(Hpdc)₂], (I).

Compound (I) is a dinuclear complex having a center of symmetry and consisting of two Ag^I ions, one dtpcp molecule and two Hpdc⁻ anions (Fig. 1). One of the two carboxyl groups in the H₂pdc ligand is deprotonated and the Hpdc⁻ anion is chelated to one Ag^I center through the pyridine N atom and one O atom of the deprotonated carboxyl group. Each Ag^I ion is three-coordinate in an approximately trigonal configuration by one of the S atoms of the dtpcp ligand, and N and O atoms of the Hpdc⁻ anion. The S1—C7···C8—S1ⁱ—C7ⁱ···C8ⁱ [symmetry code: (i) 1/2 − x, 1/2 − y, 1 − z] ring moiety exhibits a chair conformation, as observed in other dtpcp–silver(I) complexes (Liu et al., 2004a,b). The dtpcp ligand acts as a µ₂ bridge, linking two Ag atoms with Ag—S bond distance of 2.4129 (6) Å, which is shorter than the values of 2.4787 (5)–2.5471 (6) Å observed in other dtpcp–silver(I) complexes (Liu et al., 2004a,b). The Ag—N bond length [2.287 (2) Å] and Ag—O bond length [2.353 (1) Å] in (I) are also shorter than those observed in another H₂pdc–silver(I) complex (Wang et al., 2004). The shorter bond lengths around the Ag^I center may be attributable to the fact that the coordination number of Ag in (I) is smaller than in other reported dtpcp– or H₂pdc–silver(I) complexes, in which the Ag^I ions are four-coordinate in a distorted tetrahedral configuration.

Each dinuclear silver(I) complex is interconnected with four adjacent ones through O4—H12···O2(x − 1/2, 3/2 − y, z − 1/2) hydrogen bonds (Table 2), propagating as a zigzag sheet. Two zigzag sheets are interwoven in an offset mode to give a bilayer network (Fig. 2). The chair conformation of the dtpcp ligand leads to a step-like arrangement of the two Ag(Hpdc) moieties (Fig. 1), allowing the formation of the bilayer structure. Within the bilayer, two pyridine rings from different sheets are partially overlapped, with an average interplanar distance of 3.30 Å, indicating strong π–π interactions between them. The bilayers are packed on top of? one another (Fig. 3). No short contacts were found between the bilayers.

S2. Experimental

A mixed solution (4.5 ml) of mesitylene (3 ml) and dimethylformamide (1.5 ml), containing dtpcp (0.03 mmol, 8.2 mg) and H₂pdc (0.06 mmol, 10.0 mg), was introduced into a glass tube and layered with a methanol solution (4.5 ml) containing AgCF₃CO₂ (0.06 mmol, 13.2 mg). The glass tube was sealed under argon. After standing at room temperature for 3 d, colorless block-shaped crystals of (I) were isolated (yield 68%). Analysis calculated for C₃₀H₂₄Ag₂N₂O₈S₂: C 43.92, H 2.95, N 3.41%; found: C 43.66, H 2.91, N 3.38%.

S3. Refinement

All H atoms were found in difference Fourier maps and were subsequently refined with a fixed U_iso(H) value of 0.03 Ų. The C—H bond lengths are 0.89 (3)–1.00 (3) Å.

Computing details

Data collection: CrystalClear (Rigaku, 2001); cell refinement: CrystalClear; data reduction: TEXSAN (Molecular Structure Corporation, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976); software used to prepare material for publication: TEXSAN.

Figures

	Fig. 1. The structure and atom numbering of (I), showing displacement ellipsoids at the 50% probability level. H atoms, except those of the carboxylic acid groups, have been omitted for clarity. [Symmetry code: (i) 1/2 − x, 1/2 − y, 1 − z.]
	Fig. 2. The interwoven bilayer network of (I). H atoms, except those of the carboxylic acid groups, have been omitted. Broken lines indicate O—H···O hydrogen bonds.
	Fig. 3. The crystal structure of (I), viewed along the b axis. H atoms, except those of the carboxylic acid groups, have been omitted.

(µ-2,11-Dithia[3.3]paracyclophane-κ²S:S')bis[(2-carboxylatopyridine- 6-carboxylic acid-κ²N,O)silver(I)]

Crystal data

[Ag2(C16H16S2)(C7H4O4N)2]	F(000) = 1632.0
Mr = 820.38	Dx = 1.884 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.7107 Å
Hall symbol: -c 2yc	Cell parameters from 4714 reflections
a = 17.025 (10) Å	θ = 3.2–27.5°
b = 12.828 (7) Å	µ = 1.55 mm^−1
c = 14.096 (8) Å	T = 150 K
β = 110.075 (6)°	Block, colorless
V = 2892 (3) Å^3	0.30 × 0.25 × 0.20 mm
Z = 4

Data collection

Rigaku/MSC Mercury CCD diffractometer	3038 reflections with I > 2σ(I)
Detector resolution: 14.62 pixels mm^-1	Rint = 0.022
ω scans	θmax = 27.5°, θmin = 3.2°
Absorption correction: multi-scan (Jacobson, 1998)	h = −16→22
Tmin = 0.665, Tmax = 0.733	k = −16→16
11072 measured reflections	l = −18→18
3250 independent reflections

Refinement

Refinement on F^2	Only H-atom coordinates refined
R[F^2 > 2σ(F^2)] = 0.026	w = 1/[σ^2(Fo^2) + (0.0289P)^2 + 3.8032P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.060	(Δ/σ)max = −0.002
S = 1.09	Δρmax = 0.61 e Å^−3
3038 reflections	Δρmin = −0.49 e Å^−3
235 parameters

Special details

Refinement. Refinement using reflections with F² > −10.0 σ(F²). The weighted R-factor (wR) and goodness of fit (S) are based on F². R-factor (gt) are based on F. The threshold expression of F² > 2.0 σ(F²) is used only for calculating R-factor (gt).

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

	x	y	z	Uiso*/Ueq
Ag1	0.50228 (1)	0.58511 (1)	0.61899 (1)	0.02816 (7)
S1	0.41061 (3)	0.44452 (4)	0.53498 (4)	0.0196 (1)
O1	0.62197 (9)	0.6226 (1)	0.7595 (1)	0.0257 (3)
O2	0.7080 (1)	0.7532 (1)	0.8338 (1)	0.0322 (4)
O3	0.40063 (9)	0.7006 (1)	0.4475 (1)	0.0281 (3)
O4	0.32971 (9)	0.8480 (1)	0.4463 (1)	0.0269 (3)
N1	0.5164 (1)	0.7624 (1)	0.6302 (1)	0.0155 (3)
C1	0.2388 (1)	0.4202 (2)	0.4585 (2)	0.0203 (4)
C2	0.1967 (1)	0.3798 (2)	0.5191 (2)	0.0215 (4)
C3	0.1440 (1)	0.2949 (2)	0.4875 (2)	0.0201 (4)
C4	0.1327 (1)	0.2477 (2)	0.3949 (2)	0.0193 (4)
C5	0.1704 (1)	0.2923 (2)	0.3310 (2)	0.0226 (4)
C6	0.2226 (1)	0.3776 (2)	0.3624 (2)	0.0221 (4)
C7	0.3055 (1)	0.5013 (2)	0.5014 (2)	0.0251 (4)
C8	0.0816 (1)	0.1491 (2)	0.3643 (2)	0.0241 (4)
C9	0.5829 (1)	0.7981 (2)	0.7060 (1)	0.0168 (4)
C10	0.5993 (1)	0.9040 (2)	0.7225 (2)	0.0210 (4)
C11	0.5431 (1)	0.9748 (2)	0.6611 (2)	0.0242 (4)
C12	0.4732 (1)	0.9384 (2)	0.5845 (2)	0.0203 (4)
C13	0.4633 (1)	0.8316 (2)	0.5697 (1)	0.0160 (4)
C14	0.6419 (1)	0.7163 (2)	0.7718 (1)	0.0195 (4)
C15	0.3937 (1)	0.7860 (2)	0.4813 (1)	0.0186 (4)
H1	0.204 (2)	0.410 (2)	0.580 (2)	0.0301*
H2	0.117 (2)	0.267 (2)	0.531 (2)	0.0301*
H3	0.164 (2)	0.263 (2)	0.269 (2)	0.0301*
H4	0.250 (2)	0.407 (2)	0.320 (2)	0.0301*
H5	0.301 (2)	0.530 (2)	0.563 (2)	0.0301*
H6	0.307 (2)	0.552 (2)	0.452 (2)	0.0301*
H7	0.094 (2)	0.118 (2)	0.315 (2)	0.0301*
H8	0.020 (2)	0.164 (2)	0.342 (2)	0.0301*
H9	0.650 (2)	0.926 (2)	0.774 (2)	0.0301*
H10	0.553 (2)	1.047 (2)	0.673 (2)	0.0301*
H11	0.432 (2)	0.983 (2)	0.541 (2)	0.0301*
H12	0.289 (2)	0.814 (2)	0.408 (2)	0.0301*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ag1	0.0210 (1)	0.01937 (9)	0.0361 (1)	−0.00372 (6)	−0.00042 (7)	−0.00345 (6)
S1	0.0144 (2)	0.0191 (2)	0.0241 (2)	−0.0026 (2)	0.0051 (2)	−0.0022 (2)
O1	0.0205 (8)	0.0250 (8)	0.0248 (8)	0.0001 (6)	−0.0010 (6)	0.0036 (6)
O2	0.0181 (8)	0.0336 (9)	0.0312 (8)	−0.0008 (6)	−0.0091 (6)	−0.0024 (7)
O3	0.0228 (8)	0.0253 (8)	0.0270 (8)	0.0020 (6)	−0.0032 (6)	−0.0069 (6)
O4	0.0154 (7)	0.0261 (8)	0.0290 (8)	0.0028 (6)	−0.0055 (6)	−0.0038 (6)
N1	0.0115 (8)	0.0201 (8)	0.0149 (7)	−0.0007 (6)	0.0046 (6)	−0.0005 (6)
C1	0.0119 (9)	0.0172 (9)	0.029 (1)	0.0035 (7)	0.0038 (8)	0.0015 (8)
C2	0.016 (1)	0.0221 (10)	0.025 (1)	0.0033 (8)	0.0065 (8)	−0.0037 (8)
C3	0.0148 (10)	0.0227 (10)	0.0234 (10)	0.0031 (8)	0.0073 (8)	0.0000 (8)
C4	0.0135 (9)	0.0202 (9)	0.0203 (9)	0.0012 (7)	0.0008 (8)	0.0016 (7)
C5	0.021 (1)	0.026 (1)	0.0161 (9)	−0.0002 (8)	0.0009 (8)	0.0021 (8)
C6	0.0160 (10)	0.024 (1)	0.025 (1)	0.0010 (8)	0.0049 (8)	0.0068 (8)
C7	0.016 (1)	0.019 (1)	0.038 (1)	0.0007 (8)	0.0071 (9)	−0.0035 (9)
C8	0.024 (1)	0.027 (1)	0.0184 (10)	−0.0052 (9)	0.0034 (8)	−0.0019 (8)
C9	0.0116 (9)	0.0250 (10)	0.0143 (8)	−0.0014 (8)	0.0049 (7)	−0.0014 (7)
C10	0.017 (1)	0.027 (1)	0.0173 (9)	−0.0054 (8)	0.0034 (8)	−0.0032 (8)
C11	0.027 (1)	0.020 (1)	0.025 (1)	−0.0053 (9)	0.0076 (9)	−0.0033 (8)
C12	0.019 (1)	0.0222 (10)	0.0186 (9)	0.0015 (8)	0.0050 (8)	0.0028 (8)
C13	0.0117 (9)	0.0214 (9)	0.0152 (9)	−0.0001 (7)	0.0051 (7)	0.0003 (7)
C14	0.0141 (9)	0.027 (1)	0.0164 (9)	0.0000 (8)	0.0042 (7)	−0.0002 (8)
C15	0.0157 (10)	0.0223 (10)	0.0159 (9)	−0.0015 (8)	0.0031 (7)	0.0015 (7)

Geometric parameters (Å, º)

Ag1—S1	2.4129 (6)	C9—C10	1.390 (3)
Ag1—O1	2.353 (1)	C9—C14	1.526 (3)
Ag1—N1	2.287 (2)	C10—C11	1.386 (3)
S1—C7	1.837 (2)	C11—C12	1.385 (3)
S1—C8^i	1.829 (2)	C12—C13	1.387 (3)
O1—C14	1.245 (3)	C13—C15	1.512 (2)
O2—C14	1.257 (2)	O4—H12	0.84 (3)
O3—C15	1.218 (3)	C2—H1	0.91 (3)
O4—C15	1.301 (2)	C3—H2	0.95 (3)
N1—C9	1.342 (2)	C5—H3	0.92 (3)
N1—C13	1.343 (2)	C6—H4	0.95 (3)
C1—C2	1.390 (4)	C7—H5	0.97 (3)
C1—C6	1.397 (3)	C7—H6	0.96 (3)
C1—C7	1.505 (3)	C8—H7	0.89 (3)
C2—C3	1.383 (3)	C8—H8	1.00 (3)
C3—C4	1.391 (3)	C10—H9	0.96 (3)
C4—C5	1.396 (3)	C11—H10	0.95 (3)
C4—C8	1.512 (3)	C12—H11	0.95 (3)
C5—C6	1.383 (3)
Ag1···S1^ii	3.0437 (9)	N1···C14^iii	3.475 (3)
Ag1···O1^iii	3.183 (2)	C3···C9^viii	3.572 (3)
O1···C7^iii	3.528 (3)	C8···C8^ix	3.458 (4)
O2···C15^iv	3.171 (3)	C9···C9^iii	3.453 (5)
O2···O3^iv	3.172 (3)	C9···C13^iii	3.537 (3)
O2···O4^iii	3.586 (3)	C10···C12^iii	3.382 (4)
O4···C7^v	3.278 (3)	C10···C11^iii	3.484 (4)
O4···C14^vi	3.399 (3)	C10···C13^iii	3.567 (3)
O4···C2^v	3.576 (3)	C11···C11^iii	3.312 (5)
N1···C9^iii	3.329 (3)	C11···C12^x	3.555 (3)
N1···C3^vii	3.456 (3)	C12···C12^x	3.240 (5)
S1—Ag1—O1	142.50 (4)	O1—C14—O2	126.6 (2)
S1—Ag1—N1	144.31 (4)	O1—C14—C9	119.2 (2)
O1—Ag1—N1	72.45 (5)	O2—C14—C9	114.2 (2)
Ag1—S1—C7	103.83 (7)	O3—C15—O4	125.7 (2)
Ag1—S1—C8^i	104.33 (7)	O3—C15—C13	121.1 (2)
C7—S1—C8^i	105.4 (1)	O4—C15—C13	113.2 (2)
Ag1—O1—C14	115.5 (1)	C15—O4—H12	109 (2)
Ag1—N1—C9	115.7 (1)	C1—C2—H1	119 (2)
Ag1—N1—C13	125.6 (1)	C3—C2—H1	120 (2)
C9—N1—C13	118.7 (2)	C2—C3—H2	119 (1)
C2—C1—C6	118.5 (2)	C4—C3—H2	119 (1)
C2—C1—C7	119.2 (2)	C4—C5—H3	120 (1)
C6—C1—C7	122.0 (2)	C6—C5—H3	119 (2)
C1—C2—C3	120.7 (2)	C1—C6—H4	118 (1)
C2—C3—C4	120.7 (2)	C5—C6—H4	120 (1)
C3—C4—C5	118.8 (2)	S1—C7—H5	106 (1)
C3—C4—C8	120.8 (2)	S1—C7—H6	101 (2)
C5—C4—C8	120.4 (2)	C1—C7—H5	110 (1)
C4—C5—C6	120.3 (2)	C1—C7—H6	112 (1)
C1—C6—C5	120.7 (2)	H5—C7—H6	115 (2)
S1—C7—C1	111.3 (2)	S1^i—C8—H7	109 (1)
S1^i—C8—C4	116.5 (1)	S1^i—C8—H8	99 (1)
N1—C9—C10	122.2 (2)	C4—C8—H7	109 (2)
N1—C9—C14	116.7 (2)	C4—C8—H8	111 (1)
C10—C9—C14	121.1 (2)	H7—C8—H8	110 (3)
C9—C10—C11	118.6 (2)	C9—C10—H9	119 (1)
C10—C11—C12	119.4 (2)	C11—C10—H9	121 (1)
C11—C12—C13	118.5 (2)	C10—C11—H10	119 (1)
N1—C13—C12	122.5 (2)	C12—C11—H10	121 (1)
N1—C13—C15	115.8 (2)	C11—C12—H11	123 (1)
C12—C13—C15	121.7 (2)	C13—C12—H11	118 (1)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O4—H12···O2^vi	0.84 (3)	1.66 (3)	2.497 (2)	180 (3)

Symmetry code: (vi) x−1/2, −y+3/2, z−1/2.