The title compound, {[Ag
2(C
4H
4N
2)
3](CF
3SO
3)
2·2H
2O}
n, is a polymeric pyrazine-silver(I) complex. Each Ag
I ion is three-coordinated by N atoms of three different pyrazine ligands, forming a T-shaped coordination configuration. In the crystal structure, uncoordinated water molecules are linked to trifluoromethanesulfonate anions through intermolecular O-H
O hydrogen bonds. There are weaker Ag
O interactions involving the water and sulfonate O atoms.
Supporting information
CCDC reference: 259014
Pyrazine (0.2 mmol, 16.0 mg) and silver(I) trifluoromethanesulfonate (0.2 mmol, 51.4 mg) were dissolved in a 30% ammonia solution (10 ml). The mixture was stirred at room temperature for 20 min and then filtered. After keeping the colourless filtrate in air for 12 d, colourless block-shaped crystals were formed at the bottom of the vessel on slow evaporation of three-quarters of the solvent. The crystals were isolated, washed three times with distilled water and dried in a vacuum desiccator using anhydrous CaCl2 (yield 71.2%).
All H atoms were placed in idealized positions and constrained to ride on their parent atoms, with C—H distances of 0.96 Å and O—H distance of 0.93 Å. The Uiso(H) value for atom H1WA was fixed at 0.05 Å2, and for the remaining H atoms the values were fixed at 0.08 Å2.
Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Sheldrick, 1997); software used to prepare material for publication: SHELXTL.
catena-Poly[[[µ-pyrazine-
κ2N:
N'-disilver(I)]-di-µ-pyrazine-
κ4N:
N'] bis(trifluoromethanesulfonate) dihydrate]
top
Crystal data top
[Ag2(C4H4N2)3](CF3SO3)2·2H2O | F(000) = 772 |
Mr = 790.18 | Dx = 2.073 Mg m−3 |
Monoclinic, C2/m | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2y | Cell parameters from 987 reflections |
a = 18.630 (4) Å | θ = 2.2–25.8° |
b = 7.250 (3) Å | µ = 1.81 mm−1 |
c = 9.552 (2) Å | T = 293 K |
β = 101.17 (3)° | Block, colourless |
V = 1265.7 (7) Å3 | 0.35 × 0.28 × 0.21 mm |
Z = 2 | |
Data collection top
SMART CCD area-detector diffractometer | 1393 independent reflections |
Radiation source: fine-focus sealed tube | 1289 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.037 |
ω scans | θmax = 26.5°, θmin = 2.2° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −23→20 |
Tmin = 0.570, Tmax = 0.703 | k = −9→5 |
2918 measured reflections | l = −11→11 |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.045 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.113 | H-atom parameters constrained |
S = 1.11 | w = 1/[σ2(Fo2) + (0.0594P)2 + 1.961P] where P = (Fo2 + 2Fc2)/3 |
1393 reflections | (Δ/σ)max < 0.001 |
100 parameters | Δρmax = 0.56 e Å−3 |
0 restraints | Δρmin = −1.13 e Å−3 |
Crystal data top
[Ag2(C4H4N2)3](CF3SO3)2·2H2O | V = 1265.7 (7) Å3 |
Mr = 790.18 | Z = 2 |
Monoclinic, C2/m | Mo Kα radiation |
a = 18.630 (4) Å | µ = 1.81 mm−1 |
b = 7.250 (3) Å | T = 293 K |
c = 9.552 (2) Å | 0.35 × 0.28 × 0.21 mm |
β = 101.17 (3)° | |
Data collection top
SMART CCD area-detector diffractometer | 1393 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1289 reflections with I > 2σ(I) |
Tmin = 0.570, Tmax = 0.703 | Rint = 0.037 |
2918 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.113 | H-atom parameters constrained |
S = 1.11 | Δρmax = 0.56 e Å−3 |
1393 reflections | Δρmin = −1.13 e Å−3 |
100 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. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
Ag1 | 0.33330 (2) | 0.0000 | 0.68487 (5) | 0.0537 (2) | |
S1 | 0.11592 (8) | 0.0000 | 0.71153 (18) | 0.0537 (4) | |
F1 | 0.0831 (6) | 0.0000 | 0.9630 (7) | 0.159 (3) | |
F2 | 0.1802 (4) | 0.1485 (8) | 0.9493 (5) | 0.157 (2) | |
O1 | 0.0746 (2) | 0.1656 (7) | 0.6805 (5) | 0.0895 (13) | |
O2 | 0.1842 (3) | 0.0000 | 0.6657 (7) | 0.0734 (15) | |
O1W | 0.4164 (3) | 0.0000 | 0.4902 (7) | 0.0828 (16) | |
H1WA | 0.4239 | 0.1102 | 0.4458 | 0.050* | |
N1 | 0.4395 (3) | 0.0000 | 0.8900 (7) | 0.0639 (15) | |
N2 | 0.32700 (16) | 0.3087 (5) | 0.6698 (4) | 0.0455 (8) | |
C1 | 0.1404 (7) | 0.0000 | 0.9061 (12) | 0.103 (3) | |
C2 | 0.5062 (4) | 0.0000 | 0.8652 (8) | 0.0646 (18) | |
H2A | 0.5130 | 0.0000 | 0.7681 | 0.080* | |
C3 | 0.4340 (4) | 0.0000 | 1.0272 (9) | 0.076 (2) | |
H3A | 0.3861 | 0.0000 | 1.0503 | 0.080* | |
C4 | 0.2655 (2) | 0.4056 (6) | 0.6633 (5) | 0.0471 (9) | |
H4A | 0.2200 | 0.3411 | 0.6582 | 0.080* | |
C5 | 0.3880 (2) | 0.4054 (6) | 0.6752 (5) | 0.0497 (10) | |
H5A | 0.4334 | 0.3408 | 0.6794 | 0.080* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Ag1 | 0.0541 (3) | 0.0266 (3) | 0.0771 (4) | 0.000 | 0.0045 (2) | 0.000 |
S1 | 0.0480 (8) | 0.0492 (9) | 0.0658 (9) | 0.000 | 0.0161 (7) | 0.000 |
F1 | 0.219 (8) | 0.185 (9) | 0.098 (4) | 0.000 | 0.091 (5) | 0.000 |
F2 | 0.198 (5) | 0.139 (5) | 0.114 (3) | −0.040 (4) | −0.024 (3) | −0.042 (3) |
O1 | 0.090 (3) | 0.085 (3) | 0.100 (3) | 0.037 (2) | 0.031 (2) | 0.016 (2) |
O2 | 0.054 (3) | 0.064 (3) | 0.109 (4) | 0.000 | 0.033 (3) | 0.000 |
O1W | 0.088 (4) | 0.074 (4) | 0.095 (4) | 0.000 | 0.038 (3) | 0.000 |
N1 | 0.062 (3) | 0.058 (4) | 0.065 (3) | 0.000 | −0.004 (3) | 0.000 |
N2 | 0.0417 (17) | 0.0264 (16) | 0.066 (2) | 0.0014 (13) | 0.0037 (15) | 0.0039 (15) |
C1 | 0.126 (9) | 0.094 (8) | 0.083 (6) | 0.000 | 0.009 (6) | 0.000 |
C2 | 0.071 (5) | 0.066 (5) | 0.055 (4) | 0.000 | 0.008 (3) | 0.000 |
C3 | 0.061 (4) | 0.086 (6) | 0.082 (5) | 0.000 | 0.017 (4) | 0.000 |
C4 | 0.0389 (19) | 0.034 (2) | 0.066 (2) | −0.0017 (16) | 0.0036 (18) | −0.0007 (19) |
C5 | 0.040 (2) | 0.034 (2) | 0.073 (3) | 0.0031 (17) | 0.0060 (19) | 0.000 (2) |
Geometric parameters (Å, º) top
Ag1—N2i | 2.244 (4) | N2—C5 | 1.328 (5) |
Ag1—N2 | 2.244 (4) | N2—C4 | 1.336 (5) |
Ag1—N1 | 2.500 (6) | C1—F2i | 1.327 (8) |
S1—O2 | 1.423 (5) | C2—C3ii | 1.361 (11) |
S1—O1i | 1.427 (4) | C2—H2A | 0.9600 |
S1—O1 | 1.427 (4) | C3—C2ii | 1.361 (11) |
S1—C1 | 1.825 (11) | C3—H3A | 0.9600 |
F1—C1 | 1.288 (15) | C4—C4iii | 1.369 (8) |
F2—C1 | 1.327 (8) | C4—H4A | 0.9601 |
O1W—H1WA | 0.9273 | C5—C5iii | 1.372 (8) |
N1—C2 | 1.310 (9) | C5—H5A | 0.9601 |
N1—C3 | 1.334 (10) | | |
| | | |
N2i—Ag1—N2 | 171.44 (17) | F2—C1—F2i | 108.4 (10) |
N2i—Ag1—N1 | 94.24 (8) | F1—C1—S1 | 111.5 (9) |
N2—Ag1—N1 | 94.24 (8) | F2—C1—S1 | 109.3 (6) |
O2—S1—O1i | 114.5 (2) | F2i—C1—S1 | 109.3 (6) |
O2—S1—O1 | 114.5 (2) | N1—C2—C3ii | 122.0 (7) |
O1i—S1—O1 | 114.6 (4) | N1—C2—H2A | 118.7 |
O2—S1—C1 | 104.6 (5) | C3ii—C2—H2A | 119.3 |
O1i—S1—C1 | 103.3 (3) | N1—C3—C2ii | 122.4 (7) |
O1—S1—C1 | 103.3 (3) | N1—C3—H3A | 118.5 |
C2—N1—C3 | 115.7 (6) | C2ii—C3—H3A | 119.1 |
C2—N1—Ag1 | 119.5 (5) | N2—C4—C4iii | 121.7 (2) |
C3—N1—Ag1 | 124.8 (5) | N2—C4—H4A | 119.1 |
C5—N2—C4 | 116.4 (4) | C4iii—C4—H4A | 119.2 |
C5—N2—Ag1 | 119.4 (3) | N2—C5—C5iii | 121.9 (2) |
C4—N2—Ag1 | 124.1 (3) | N2—C5—H5A | 118.9 |
F1—C1—F2 | 109.1 (7) | C5iii—C5—H5A | 119.2 |
F1—C1—F2i | 109.1 (7) | | |
Symmetry codes: (i) x, −y, z; (ii) −x+1, −y, −z+2; (iii) x, −y+1, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1W—H1WA···O1iv | 0.93 | 2.03 | 2.944 (6) | 170 |
Symmetry code: (iv) −x+1/2, −y+1/2, −z+1. |
Experimental details
Crystal data |
Chemical formula | [Ag2(C4H4N2)3](CF3SO3)2·2H2O |
Mr | 790.18 |
Crystal system, space group | Monoclinic, C2/m |
Temperature (K) | 293 |
a, b, c (Å) | 18.630 (4), 7.250 (3), 9.552 (2) |
β (°) | 101.17 (3) |
V (Å3) | 1265.7 (7) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 1.81 |
Crystal size (mm) | 0.35 × 0.28 × 0.21 |
|
Data collection |
Diffractometer | SMART CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.570, 0.703 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 2918, 1393, 1289 |
Rint | 0.037 |
(sin θ/λ)max (Å−1) | 0.627 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.045, 0.113, 1.11 |
No. of reflections | 1393 |
No. of parameters | 100 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.56, −1.13 |
Selected geometric parameters (Å, º) topAg1—N2 | 2.244 (4) | Ag1—N1 | 2.500 (6) |
| | | |
N2i—Ag1—N2 | 171.44 (17) | N2—Ag1—N1 | 94.24 (8) |
Symmetry code: (i) x, −y, z. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O1W—H1WA···O1ii | 0.93 | 2.03 | 2.944 (6) | 170 |
Symmetry code: (ii) −x+1/2, −y+1/2, −z+1. |
Studying the variety of products in the self-assembly processes between labile metal ions and multidentate ligands is an interesting topic in supramolecular chemistry (Zheng et al., 2003; You, Zhu & Liu, 2004; You, Yang et al., 2004). The primary reason for the interest in such compounds is their ability to afford functional solid materials with potentially controllable properties and fascinating molecular structures. Recent developments in supramolecular chemistry have made it possible to select building units for assembly into structures with specific network topologies (Xu et al., 2001). The construction of a wide variety of network topologies has been achieved through ligand design and the use of different transition metal coordination geometries. These include one-dimensional chains, which can be helical, two-dimensional sheets with a variety of connectivities and three-dimensional networks, such as the diamondoid or adamantoid structures (Khlobystov et al., 2001). Crystal engineering of coordination polymeric networks based on multidentate ligands is a growing area of coordination and supramolecular chemistry. We have focused our attention on the assembly of metal ions with flexible ligands, since they can adopt diverse coordination modes according to the different geometric needs of the metal ions (Zhu, Ma et al., 2003; Ren et al., 2001). As reported previously, the bidentate ligand 1,2-diaminocyclohexane gives a two-dimensional framework depending on the metal ions and the trifluoromethanesulfanate counter-anions (Usman et al., 2003). We have now extended this work to pyrazine instead of 1,2-diaminocyclohexane. Suprisingly, reaction of pyrazine with silver(I) trifluoromethanesulfonate gives a one-dimensional chain that is entirely different from that found in the complex formed by 1,2-diaminocyclohexane with silver(I) trifluoromethanesulfonate.
The title compound, (I), is a polymeric pyrazine–AgI complex with an inversion center (Fig. 1). The smallest repeat unit for the complex contains two silver(I) cations, three bridging pyrazine ligands, two trifluoromethanesulfonate anions and two uncoordinated water molecules. Each AgI ion is in a T-shaped environment, coordinated by three N atoms of three different pyrazine ligands, the N2—Ag1—N2i [symmetry code: (i) x, −y, z] bond angle being 171.44 (17)° (Table 1) and the other two bond angles related to atom Ag1 being 94.24 (8)°. The Ag1—N1 bond length [2.500 (6) Å] is slightly longer than the Ag1—N2 bond [2.244 (4) Å], the difference probably being caused by the presence of weak static forces related to the interactions of two O atoms with atom Ag1. Atom O2 of the trifluoromethanesulfonate anion and atom O1W of the uncoordinated water molecule are located, respectively, 2.641 (5) and 2.748 (5) Å from atom Ag1.
In the crystal structure, the pyrazine ligands bridge the AgI ions, forming two parallel chains along the b axis. The dihedral angle between the two intersecting pyrazine rings is 90.0°. The two chains are then linked by the intersecting bridging pyrazine ligands, forming numerous tetragons with border lengths of 7.768 (2) and 7.250 (2) Å. The tetragons are combined along the b axis, forming a one-dimensional ladder-shaped strip. The uncoordinated water molecules and the trifluoromethanesulfonate anions are linked through intermolecular O—H···O hydrogen bonds and are located beside the one-dimensional cationic chains (Table 2 and Fig. 2).