A novel double-chain silver(I) coordination polymer: catena-poly[[[μ-aqua-aqua­disilver(I)]-bis­(μ3-5-methyl­pyrazine-2-carboxyl­ato)] dihydrate]

Bin Zhai; Xiangfei Zhang; Maotian Xu

doi:10.1107/S160053680802984X

. 2008 Sep 24;64(Pt 10):m1312–m1313. doi: 10.1107/S160053680802984X

A novel double-chain silver(I) coordination polymer: catena-poly[[[μ-aqua-aquadisilver(I)]-bis(μ₃-5-methylpyrazine-2-carboxylato)] dihydrate]

Bin Zhai ^a,^*, Xiangfei Zhang ^a, Maotian Xu ^a

PMCID: PMC2959376 PMID: 21201049

Abstract

In the title silver(I) coordination polymer, {[Ag₂(C₆H₅N₂O₂)₂(H₂O)₂]·2H₂O}_n, the [Ag₂(μ₂-H₂O)(H₂O)] cores are extended by antiparallel 5-methylpyrazine-2-carboxylate (L) ligands, forming a novel double-chain structure. Both Ag⁺ cations show a distorted square-pyramidal coordination. Ag1 is bonded to two water molecules, one L N atom, one N atom and one carboxylate O atom from a neighbouring L, whereas Ag2 is surrounded by two L N atoms, two L carboxylate O atoms and one bridging water molecule. O—H⋯O hydrogen-bonding interactions involving water clusters and carboxylate O atoms link the molecules into a three-dimensional supramolecular architecture, which is further consolidated by weak C—H⋯O interactions and π–π stacking interactions [centroid–centroid distance 3.643 (5) Å].

Related literature

For related literature, see: Ciurtin et al. (2001 ▶, 2003 ▶); Dong et al. (2000 ▶); Garribba et al. (2006 ▶); Liu et al. (2007 ▶); Ptasiewicz-Bak & Leciejewicz (2000 ▶); Shang et al. (2007 ▶); Tanase et al. (2006 ▶); Etter (1990 ▶).

Experimental

Crystal data

[Ag₂(C₆H₅N₂O₂)₂(H₂O)₂]·2H₂O
M _r = 562.04
Triclinic,
a = 6.9481 (5) Å
b = 10.1827 (8) Å
c = 13.483 (1) Å
α = 107.503 (1)°
β = 100.185 (1)°
γ = 103.164 (1)°
V = 854.4 (1) Å³
Z = 2
Mo Kα radiation
μ = 2.34 mm⁻¹
T = 293 (2) K
0.24 × 0.20 × 0.16 mm

Data collection

Bruker APEX CCD area-detector diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.581, T _max = 0.698
4422 measured reflections
2982 independent reflections
2518 reflections with I > 2σ(I)
R _int = 0.014

Refinement

R[F ² > 2σ(F ²)] = 0.027
wR(F ²) = 0.071
S = 1.07
2982 reflections
236 parameters
H-atom parameters constrained
Δρ_max = 0.39 e Å⁻³
Δρ_min = −0.51 e Å⁻³

Data collection: SMART (Bruker, 2001 ▶); cell refinement: SAINT (Bruker, 2003 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg & Putz, 2005 ▶); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S160053680802984X/kj2095sup1.cif

e-64-m1312-sup1.cif^{(21.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053680802984X/kj2095Isup2.hkl

e-64-m1312-Isup2.hkl^{(146.3KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Ag1—N1	2.260 (3)
Ag1—N3	2.311 (3)
Ag1—O6	2.478 (3)
Ag1—O5	2.517 (3)
Ag1—O4	2.598 (3)
Ag2—N4ⁱ	2.233 (3)
Ag2—N2	2.250 (3)
Ag2—O2	2.558 (3)
Ag2—O5ⁱⁱ	2.688 (3)
Ag2—O4ⁱⁱ	2.809 (3)

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Symmetry codes: (i) Inline graphic ; (ii) .

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1—H1⋯O4	0.93	2.38	3.061 (4)	130
O5—H5B⋯O2ⁱⁱ	0.85	1.94	2.675 (4)	144
O5—H5A⋯O7ⁱⁱⁱ	0.85	1.91	2.756 (4)	175
O6—H6A⋯O7^iv	0.85	2.00	2.828 (4)	166
O6—H6B⋯O1^v	0.85	1.96	2.794 (4)	168
O7—H7A⋯O8^vi	0.85	1.86	2.698 (4)	168
O7—H7B⋯O3^vii	0.85	1.87	2.712 (4)	171
O8—H8A⋯O1	0.85	2.02	2.867 (4)	176
O8—H8B⋯O3	0.85	2.13	2.965 (4)	166
O8—H8B⋯O4	0.85	2.44	3.116 (4)	137

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Symmetry codes: (ii) Inline graphic ; (iii) ; (iv) ; (v) ; (vi) ; (vii) .

Acknowledgments

This work was supported by the National Natural Science Foundation of China (grant No. 20775047).

supplementary crystallographic information

Comment

During the past two decades poly-carboxylic acid ligands have aroused great interest for chemists because many coordination polymers with this series of ligands have shown intriguing structures and potential applications in the optical, electric and magnetic areas. 5-methylpyrazine-2-carboxylic acid contains N and O donor atoms, which makes it a good building block for constructing functional materials. For example, Dong et al. (2000) use Cu(L)₂(H₂O) as a building block for constructing novel one-dimensional hetero-bimetallic Cu(II)–Ag(I) frameworks. Tanase et al. (2006) investigate the magnetic properties of Co(II), Ni(II) and Fe(II) compounds with HL, in structures where L is also involved in intricate supramolecular interactions. In this work we describe how using HL and corresponding silver(I) salts under hydrothermal conditions, a novel one-dimensional double silver(I) framework with Ag₂(µ₂-H₂O)(H₂O) cores can be isolated.

As is shown in Fig. 1, the title compound comprises two crystallographically independent silver(I) atoms, two deprotonated ligands L, one bridged coordinated water molecule, one terminal coordinated water molecule and two lattice water molecules. Ag1 is five-coordinated in the square-pyramidal geometry by two coordinated water molecules, one L nitrogen atom, one nitrogen atom and one carboxylate oxygen atom from a neighboring L. The coordinated water molecule O5 occupies the apical site and the other four atoms occupy the plane with the mean deviation of 0.0463 (1) Å. Ag1 lies above the plane at a distance of 0.3523 (2) Å. Ag2 is also five-coordinated in the square-pyramidal geometry by two L nitrogen atoms, two L carboxylate oxygen atoms and one bridged water molecule.

There exist two kinds of crystallographically different L ligands which make a dihedral angle of 13.786 (2)°. These ligands, in anti-parallel pairs, alternatively link Ag₂(µ₂-H₂O)(H₂O) cores, forming a novel one-dimensional double chain structure along the crystallographic [101] direction. The distances of Ag2—O5 and Ag2—O4 are longer than other Ag—O distances (Table 1). However all the Ag—N and Ag—O bond distances fall in the normal range.

The formation of this novel framework also reveals great potential in constructing silver(I) frameworks with HL. Solvent water molecules are key because they greatly affect the coordination geometries. Interestingly, although several Ni(II), Co(II) and Cd(II) compounds with HL have been prepared from solutions in water (Garribba et al., 2006; Shang et al.,2007; Liu et al., 2007; Ciurtin et al., 2003; Ciurtin et al., 2001; Ptasiewicz-Bak & Leciejewicz, 2000), such arrangement of different metal(II) coordination geometries induced by coordinated water molecules are not observed. This may be ascribed to the flexible and varied coordination geometries of silver atoms, i.e., a metal-directing effect.

The one-dimensional double chains of the title compound are extended into a three-dimensional supramolecular architecture by nine O—H···O hydrogen bonds (Table 2). The detailed environments of the O—H···O interactions are represented in Fig. 2. Lattice water molecule O7 acts as hydrogen bond donors to lattice water molecule O8 forming binuclear water clusters. As shown in Fig. 3, O—H···O hydrogen bonds from carboxylate oxygen atoms and lattice water molecules link the chains into a two-dimensional supramolecular sheet: O8 acts as hydrogen donor to two carboxylate oxygen atoms (O3 and O4) forming a C₂²(4) ring (Etter, 1990) and one carboxylate oxygen O1 of neighboring L ligands. O7 also acts as hydrogen bond acceptor to O5, O6 and acts as hydrogen bond donor to atom O3. Additionally O5 is also hydrogen bonded to O2 forming a strong O—H···O hydrogen bond, further consolidating the supramolecular sheet. Neighboring sheets are assembled into a three-dimensional supramolecular architecture by O6—H6B···O1 and O7—H7A···O8 hydrogen bonds (Fig. 3).

Besides classical O—H···O hydrogen bonds, also weaker non-classical C—H···O hydrogen bonds are observed (geometric details in Table 2), further extending the title compound into a three-dimensional supramolecular architecture. Additionally π–π stacking interactions are also be observed between two pyrazine groups with a distance of 3.643 (5) Å, which also help to stabilize the supramolecular architecture. The detailed environment of C—H···O interactions are also represented in Fig. 3.

Experimental

{[Ag₂(L)₂(H₂O)₂]2H₂O}_n (I) was prepared under the hydrotheraml conditions. AgNO₃(0.2 mmol), 5-methylpyrazine-2-carboxylic acid (0.2 mmol) was added into a 25 ml reaction vessel. the reaction vessel was then sealed and subsequently placed in an oven for 140 h at 120°C. The well shaped colorless block crystals suitable for single-crystal X-ray diffraction analysis can be obtained.