Di-μ-nitrato-κ⁴O:O′-bis­[bis­(3-hydroxy­pyridine-κN)silver(I)] dihydrate

The dinuclear title complex, [Ag₂(NO₃)₂(3-PyOH)₄]·2H₂O (3-PyOH is 3-hydroxy­pyridine, C₅H₅NO), situated across a crystallographic inversion centre, can be described as a dimeric structure, in which two [Ag(3-PyOH)₂] groups are held together by the Ag...Ag inter­action [3.317 (1) Å]. Each Ag atom is two-coordinate and exists in an approximately linear geometry. The two NO₃⁻ ions inter­act with the Ag^I atoms in a bridging mode through very weak Ag...O inter­actions [Ag...O = 2.862 (2) and 2.877 (2) Å]. A three-dimensional supramolecular framework is formed by O—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.027
• wR factor = 0.068
• Data-to-parameter ratio = 15.6

checkCIF/PLATON results

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PLAT041_ALERT_1_C Calc. and Rep. SumFormula Strings    Differ ....          ?
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT045_ALERT_1_C Calculated and Reported Z Differ by ............       2.00 Ratio
PLAT244_ALERT_4_C Low   'Solvent' Ueq as Compared to Neighbors for         N3
PLAT720_ALERT_4_C Number of Unusual/Non-Standard Label(s) ........          2
PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) .       1.16 Ratio

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S1. Comment

3-Hydroxypyridine (3-PyOH), when deprotonated, is a good building block in directing polymeric coordination architectures with interesting properties, such as magnetism (Castillo et al., 2000; Kawata et al., 1997) and fluorescence (Gao et al., 2005); in its neutral form, it is also useful in the synthesis of supramolecules and inorganic precursor compounds for solid-state materials, since it is not only capable of binding to metal centers but can also form regular hydrogen bonds by functioning as both a hydrogen-bond donor and an acceptor (Breeze & Wang, 1993). Recently, we have reported the chain and layer hydrogen-bonding architectures of two copper(II) complexes (Gao, Zhang et al., 2004; Gao, Lu et al., 2004), as well as the three-dimensional supramolecular framework structure of [Ag(3-PyOH)₂]NO₃, (I) (Lu et al., 2005). In continuation of our research in synthesis of supramolecular transition metal complexes with the 3-PyOH ligand, we have recently obtained the title compound, (II), from an aqueous solution of AgNO₃ and 3-PyOH. We report here the crystal structure of (II).

The asymmetric unit of (II) consists of one-half of [Ag(3-PyOH)₂NO₃]₂·2H₂O, situated across a crystallographic inversion centre (Fig. 1). Each Ag^I atom is coordinated by two neutral 3-PyOH molecules through the N atoms [Ag—N = 2.142 (2) and 2.148 (2) Å] and shows a linear geometry with an N—Ag—N angle of 171.79 (8)°. The two NO₃⁻ ions interact with the Ag^I atoms in a bridging mode through very weak Ag···O interactions [Ag···O = 2.862 (2) and 2.877 (2) Å]. The fact that the N—Ag—N angle in (II) is wider than that in (I) [162.54 (9)°; Lu et al., 2005] may be ascribed to the bridging mode of the two NO₃⁻ ions, rather than the chelating coordination of just one NO₃⁻ ions in (I). The Ag···O distances in (II) (Table 1) are longer than those in (I) [2.760 (3) and 2.801 (3) Å; Lu et al., 2005]. The Ag···Ag distance of 3.317 (1) Å is within the sum of van der Waals radii for two Ag^I centers (3.44 Å; Bondi, 1964) and can be considered as an Ag···Ag interaction.

In the dinuclear unit, π–π interactions are observed between adjacent pyridine rings, with a centroid–centroid distance of 3.579 (2) Å. The dinuclear units are linked by O—H···O hydrogen bonds involving the water molecules, the hydroxy groups in the 3-PyOH ligands and the NO₃⁻ ions, into a three-dimensional hydrogen-bonded framework (Fig. 2 and Table 2).

S2. Experimental

The title complex, (II), was prepared by the addition of AgNO₃ (2 mmol) to an aqueous solution of 3-hydroxypyridine (6 mmol). The resulting solution was protected from light and allowed to evaporate slowly at room temperature, whereupon colourless prismatic crystals of (I) were isolated after 5 d. Analysis calculated for C₁₀H₁₂N₃O₆Ag: C 31.77, H 3.20, N 11.11%; found: C 31.71, H 3.21, N 11.12%.

S3. Refinement

H atoms attached to O atoms were located in a difference Fourier map and refined with an O—H distance restraint of 0.85 (1) Å and U_iso(H) = 1.5U_eq(O). Other H atoms were placed in calculated positions and were allowed to ride on their parent C atoms [C—H = 0.93 Å and U_iso(H) = 1.2U_eq(C)].

Computing details

Data collection: RAPID-AUTO (Rigaku Corporation, 1998); cell refinement: RAPID-AUTO; data reduction: CrystalStructure (Rigaku/MSC & Rigaku Corporation, 2002); 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: SHELXL97.

Figures

	Fig. 1. ORTEPII plot of (II), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. Unlabelled atoms are related to labelled atoms by (1 − x, 1 − y, 1 − z). Bold-dashed lines represent weak Ag···O contacts.
	Fig. 2. Perspective view of the hydrogen-bonded three-dimensional network of (II). Weak Ag···O contacts and hydrogen bonds are denoted by bold- and narrow-dashed lines, respectively. The H atoms of the aromatic rings have been omitted for clarity.

Di-µ-nitrato-κ⁴O:O'-bis[bis(3-hydroxypyridine-κN)silver(I)] dihydrate

Crystal data

[Ag2(NO3)2(C5H5NO)4]·2H2O	Z = 1
Mr = 756.19	F(000) = 376
Triclinic, P1	Dx = 1.892 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.9912 (16) Å	Cell parameters from 5742 reflections
b = 8.8615 (18) Å	θ = 3.1–27.5°
c = 10.399 (2) Å	µ = 1.55 mm^−1
α = 81.37 (3)°	T = 296 K
β = 71.64 (3)°	Prism, colourless
γ = 72.01 (3)°	0.36 × 0.27 × 0.19 mm
V = 663.6 (3) Å^3

Data collection

Rigaku R-AXIS RAPID diffractometer	3011 independent reflections
Radiation source: fine-focus sealed tube	2533 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.017
Detector resolution: 10 pixels mm^-1	θmax = 27.5°, θmin = 3.1°
ω scans	h = −9→10
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	k = −11→11
Tmin = 0.610, Tmax = 0.747	l = −13→13
6582 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)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.068	H atoms treated by a mixture of independent and constrained refinement
S = 1.04	w = 1/[σ^2(Fo^2) + (0.0416P)^2 + 0.0053P] where P = (Fo^2 + 2Fc^2)/3
3011 reflections	(Δ/σ)max = 0.001
193 parameters	Δρmax = 0.58 e Å^−3
5 restraints	Δρmin = −0.32 e Å^−3

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

	x	y	z	Uiso*/Ueq
Ag1	0.69864 (3)	0.54425 (2)	0.43994 (2)	0.05103 (9)
O1W	1.0194 (3)	0.1979 (4)	1.0753 (2)	0.0828 (7)
O1	0.2890 (3)	1.0702 (2)	0.2297 (2)	0.0539 (4)
O2	0.9111 (4)	0.4190 (3)	0.8937 (2)	0.0742 (6)
O3	0.3204 (3)	0.7474 (3)	0.6333 (2)	0.0724 (6)
O4	0.5717 (3)	0.7994 (2)	0.6194 (2)	0.0622 (5)
O5	0.3432 (3)	0.8461 (3)	0.7989 (2)	0.0782 (7)
N1	0.5825 (3)	0.6775 (2)	0.2838 (2)	0.0432 (4)
N2	0.8483 (3)	0.3954 (2)	0.5733 (2)	0.0437 (4)
N3	0.4115 (3)	0.7960 (2)	0.6849 (2)	0.0461 (5)
C1	0.4793 (3)	0.8278 (3)	0.3024 (2)	0.0421 (5)
C2	0.3940 (3)	0.9176 (3)	0.2084 (2)	0.0413 (5)
C3	0.4130 (4)	0.8499 (3)	0.0924 (3)	0.0491 (6)
C4	0.5220 (4)	0.6965 (3)	0.0719 (3)	0.0554 (7)
C5	0.6049 (4)	0.6133 (3)	0.1693 (3)	0.0492 (6)
C6	0.8391 (3)	0.4458 (3)	0.6892 (3)	0.0469 (6)
C7	0.9323 (3)	0.3531 (3)	0.7791 (3)	0.0481 (6)
C8	1.0403 (3)	0.2026 (3)	0.7449 (3)	0.0509 (6)
C9	1.0504 (4)	0.1516 (3)	0.6240 (3)	0.0541 (6)
C10	0.9538 (4)	0.2490 (3)	0.5393 (3)	0.0510 (6)
H1	0.4645	0.8735	0.3816	0.050*
H3	0.3535	0.9067	0.0290	0.059*
H4	0.5396	0.6490	−0.0071	0.066*
H5	0.6784	0.5096	0.1547	0.059*
H6	0.7669	0.5481	0.7118	0.056*
H8	1.1049	0.1371	0.8023	0.061*
H9	1.1231	0.0503	0.5988	0.065*
H10	0.9622	0.2125	0.4576	0.061*
H11	0.335 (5)	1.110 (4)	0.274 (3)	0.081*
H12	0.961 (5)	0.346 (4)	0.943 (4)	0.111*
H1W1	1.087 (4)	0.194 (6)	1.125 (3)	0.124*
H1W2	0.916 (3)	0.189 (6)	1.125 (3)	0.124*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ag1	0.05349 (13)	0.04793 (12)	0.05306 (13)	−0.00751 (9)	−0.02662 (9)	0.00361 (8)
O1W	0.0701 (15)	0.1093 (19)	0.0705 (15)	−0.0225 (15)	−0.0371 (12)	0.0221 (14)
O1	0.0555 (11)	0.0466 (9)	0.0615 (12)	−0.0033 (8)	−0.0301 (9)	−0.0029 (8)
O2	0.0901 (16)	0.0682 (13)	0.0550 (12)	0.0067 (12)	−0.0325 (11)	−0.0116 (10)
O3	0.0952 (17)	0.0712 (13)	0.0732 (14)	−0.0329 (12)	−0.0438 (13)	−0.0074 (11)
O4	0.0598 (12)	0.0608 (12)	0.0601 (12)	−0.0073 (10)	−0.0111 (10)	−0.0191 (10)
O5	0.0730 (15)	0.1116 (19)	0.0545 (12)	−0.0273 (14)	−0.0105 (11)	−0.0320 (13)
N1	0.0453 (11)	0.0423 (10)	0.0427 (10)	−0.0089 (8)	−0.0170 (9)	−0.0019 (8)
N2	0.0410 (10)	0.0394 (10)	0.0509 (12)	−0.0090 (8)	−0.0175 (9)	0.0018 (9)
N3	0.0626 (14)	0.0329 (9)	0.0456 (11)	−0.0036 (9)	−0.0274 (10)	−0.0051 (8)
C1	0.0462 (13)	0.0456 (12)	0.0361 (11)	−0.0115 (10)	−0.0141 (10)	−0.0050 (10)
C2	0.0378 (12)	0.0453 (12)	0.0421 (12)	−0.0121 (10)	−0.0140 (10)	0.0006 (10)
C3	0.0569 (15)	0.0583 (15)	0.0408 (13)	−0.0231 (12)	−0.0224 (11)	0.0043 (11)
C4	0.0732 (19)	0.0588 (15)	0.0389 (13)	−0.0241 (14)	−0.0135 (13)	−0.0102 (12)
C5	0.0542 (15)	0.0479 (13)	0.0432 (13)	−0.0111 (11)	−0.0111 (11)	−0.0084 (11)
C6	0.0434 (13)	0.0399 (12)	0.0511 (14)	−0.0031 (10)	−0.0144 (11)	0.0002 (11)
C7	0.0448 (13)	0.0503 (13)	0.0444 (13)	−0.0081 (11)	−0.0117 (11)	−0.0013 (11)
C8	0.0426 (13)	0.0467 (13)	0.0596 (16)	−0.0055 (11)	−0.0201 (12)	0.0053 (12)
C9	0.0452 (14)	0.0417 (12)	0.0712 (18)	−0.0005 (11)	−0.0209 (13)	−0.0060 (12)
C10	0.0482 (14)	0.0458 (13)	0.0588 (15)	−0.0076 (11)	−0.0195 (12)	−0.0055 (12)

Geometric parameters (Å, º)

Ag1—N1	2.142 (2)	N2—C10	1.339 (3)
Ag1—N2	2.148 (2)	C1—C2	1.379 (3)
Ag1—O3^i	2.862 (2)	C1—H1	0.93
Ag1—O4	2.877 (2)	C2—C3	1.373 (4)
Ag1—Ag1^i	3.317 (1)	C3—C4	1.375 (4)
O1W—H1W1	0.85 (4)	C3—H3	0.93
O1W—H1W2	0.85 (3)	C4—C5	1.380 (4)
O1—C2	1.362 (3)	C4—H4	0.93
O1—H11	0.84 (4)	C5—H5	0.93
O2—C7	1.346 (4)	C6—C7	1.390 (4)
O2—H12	0.84 (4)	C6—H6	0.93
O3—N3	1.230 (3)	C7—C8	1.374 (4)
O4—N3	1.253 (3)	C8—C9	1.369 (4)
O5—N3	1.226 (3)	C8—H8	0.93
N1—C5	1.334 (3)	C9—C10	1.380 (4)
N1—C1	1.338 (3)	C9—H9	0.93
N2—C6	1.321 (3)	C10—H10	0.93
O4—Ag1—N1	96.37 (7)	C2—O1—H11	107 (2)
O4—Ag1—N2	90.05 (8)	C2—C1—H1	118.8
N1—Ag1—N2	171.79 (8)	C2—C3—C4	118.6 (2)
N1—Ag1—O3^i	91.78 (2)	C2—C3—H3	120.7
N2—Ag1—O3^i	84.98 (2)	C3—C2—C1	119.0 (2)
O4—Ag1—O3^i	151.50 (2)	C3—C4—C5	119.6 (2)
N1—Ag1—Ag1^i	84.09 (6)	C3—C4—H4	120.2
N2—Ag1—Ag1^i	100.95 (6)	C4—C3—H3	120.7
O4—Ag1—Ag1^i	91.48 (2)	C4—C5—H5	119.1
O3^i—Ag1—Ag1^i	62.10 (2)	C5—C4—H4	120.2
O1—C2—C3	119.6 (2)	C5—N1—C1	118.5 (2)
O1—C2—C1	121.5 (2)	C5—N1—Ag1	121.9 (2)
O2—C7—C8	124.6 (2)	C6—N2—C10	118.8 (2)
O2—C7—C6	117.0 (2)	C6—N2—Ag1	121.1 (2)
O3—N3—O4	120.2 (2)	C7—O2—H12	106 (3)
O5—N3—O3	119.8 (2)	C7—C6—H6	118.5
O5—N3—O4	120.0 (2)	C7—C8—H8	120.9
N1—C1—C2	122.5 (2)	C8—C9—C10	120.7 (3)
N1—C1—H1	118.8	C8—C9—H9	119.7
N1—C5—C4	121.9 (2)	C8—C7—C6	118.4 (3)
N1—C5—H5	119.1	C9—C8—C7	118.2 (2)
N2—C6—C7	123.0 (2)	C9—C10—H10	119.6
N2—C6—H6	118.5	C9—C8—H8	120.9
N2—C10—C9	120.9 (3)	C10—C9—H9	119.7
N2—C10—H10	119.6	C10—N2—Ag1	120.13 (18)
C1—N1—Ag1	119.6 (2)	H1W1—O1W—H1W2	109 (3)
Ag1^i—Ag1—N1—C5	−90.6 (2)	O1—C2—C3—C4	179.1 (2)
Ag1^i—Ag1—N1—C1	87.1 (2)	O2—C7—C8—C9	−179.4 (3)
Ag1^i—Ag1—N2—C6	−88.4 (2)	C1—C2—C3—C4	−2.3 (4)
Ag1^i—Ag1—N2—C10	91.9 (2)	C1—N1—C5—C4	−1.3 (4)
Ag1—N1—C5—C4	176.5 (2)	C2—C3—C4—C5	1.8 (4)
Ag1—N1—C1—C2	−177.1 (2)	C3—C4—C5—N1	0.1 (4)
Ag1—N2—C6—C7	179.4 (2)	C5—N1—C1—C2	0.8 (4)
Ag1—N2—C10—C9	−179.8 (2)	C6—C7—C8—C9	−0.1 (4)
N1—C1—C2—O1	179.7 (2)	C6—N2—C10—C9	0.5 (4)
N1—C1—C2—C3	1.1 (4)	C7—C8—C9—C10	−0.2 (4)
N2—C6—C7—O2	180.0 (2)	C8—C9—C10—N2	0.0 (4)
N2—C6—C7—C8	0.6 (4)	C10—N2—C6—C7	−0.8 (4)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H11···O4^ii	0.84 (4)	1.89 (4)	2.735 (3)	177 (3)
O1—H11···O5^ii	0.84 (4)	2.58 (3)	3.163 (3)	128 (3)
O2—H12···O1W	0.84 (4)	1.82 (4)	2.650 (3)	168 (4)
O1W—H1W1···O1^iii	0.85 (4)	2.16 (2)	2.937 (3)	153 (4)
O1W—H1W2···O5^iv	0.85 (3)	2.08 (3)	2.901 (3)	166 (4)

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