catena-Poly­[[silver(I)-[mu]-ethane-1,2-di­amine-[kappa]²N:N'] tri­fluoro­methane­sulfonate]

The title complex, {[Ag(C₂H₈N₂)](CF₃SO₃)}_n, is a mononuclear silver(I) compound. The Ag^I atom lies on a mirror plane and is bicoordinated in a linear configuration by two N atoms from two ethane-1,2-diamine ligands, giving zigzag polymeric chains with an [-Ag-N-C-C-N-]_n backbone running along the b axis. These chains are interconnected by N-H...O hydrogen bonds involving the tri­fluoro­methane­sulfonate anions (which also lie on mirror planes), forming a three-dimensional network.

S1. Comment

Inorganic supramolecular chemistry, and in particular the construction of polymeric coordination networks, is an extremely topical area of research (Xu et al., 2001; Yaghi & Li, 1996). The construction of a wide variety of network topologies has been achieved through ligand design and the use of different counteranions. The balance between the formation of different structures is often subtle. Factors which affect the topology of coordination polymers include not only the highly influential forces of metal and ligand coordination preferences, but also anion-based interactions. The latter factor is particularly notable in Ag^I coordination polymers (Blake et al., 2000; Melcer et al., 2001). Owing to the flexible coordination sphere of Ag^I, coordination numbers from 2 to 6 are all possible and, due to the relatively weak nature of many Ag^I-ligand interactions, such compounds are particularly susceptible to the influence of weaker supramolecular forces (Khlobystov et al., 2001).

Recently, we have reported a polynuclear Ag^I complex, (II), with 1,2-diaminoethane as the ligand and 3-fluorobenzoate as the counteranion, catena-poly[(silver(I)-µ-ethane-1,2-diamine-κ²N:N') 3-fluorobenzoate monohydrate] (You et al., 2004). In order to study the effects of the couteranion in the construction of silver(I) coordination polymers, the structure of the title compound, (I), is reported here. \sch

Complex (I) is a polymeric ethylenediamine-Ag^I compound (Fig. 1). The smallest repeat unit for the complex contains an ethylenediamine-Ag^I cation and a trifluoromethanesulfonate anion, where the Ag1 atom and the O1—S1—C2—F2 moiety of the anion lie on a mirror plane and the ethylenediamine ligand has a centre of symmetry. The Ag^I atom is in a linear coordination environment and is bicoordinated by two N atoms of ethylenediamine ligands, the N1—Ag1—N1ⁱ bond angle being 177.86 (15)° [symmetry code: (i) x, 3/2 − y, z; Table 1].

In the crystal packing of (I), the ethylenediamine-Ag^I polymer forms a zigzag chain along the b axis, and the trifluoromethanesulfonate anions are located between the chains. The sulfonate group ends connect the chains via N—H···O hydrogen bonds (Table 2), forming a three-dimensional structure (Fig. 2).

The Ag—N bond length in (I) [2.143 (4) Å] is comparable with the average value of 2.138 (2) Å in (II). The coordination geometry around the Ag atom in (II) is also linear but slightly distorted, with an N—Ag—N bond angle of 170.50 (11)°. This may be due to weak interactions between the solvate water molecule and the Ag atom in (II), with an Ag···OW distance of 2.610 (3) Å, which inclines the Ag^I atom towards the solvate water molecule.

In (I), two O atoms of the trifluoroacetate anion contribute to intermolecular N—H···O hydrogen bonds, which results in the two 1,2-diaminoethane ligands being located on the same side of the N—Ag—N axis and adopting the trans form to minimize steric effects (Fig. 2). However, in (II), the diaminoethane ligand shows the gauche form, with a C—N—N—C torsion angle of −74.1 (4)°. The 3-fluorobenzoate anion is located near the two N atoms of the diaminoethane ligand. In (II), a nine-membered ring is formed through N—H···O hydrogen bonds involving the carboxylate group of the anion.

S2. Experimental

Silver trifluoromethanesulfonate (0.1 mmol, 25.7 mg) and 1,2-diaminoethane (0.1 mmol, 6.0 mg) were dissolved in an ammonia solution (10 ml, 30%). The mixture was stirred for about 10 min at room temperature to obtain a clear colourless solution. The resulting solution was kept in the dark and, after slow evaporation of the solvent over a period of 5 d, crystals of (I) were isolated, washed three times with water and dried in a vacuum desiccator using anhydrous CaCl₂ (yield 61%). Elemental analysis, calculated: C 11.4, H 2.5, N 8.8%; found: C 11.3, H 2.5, N 8.9%.

S3. Refinement

All H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with N—H = 0.90 and C—H = 0.96 Å, and with U_iso(H) = 0.08 Ų.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART; data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. The structure of (I), showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii. [Symmetry code: (i) x, 3/2 − y, z.]
	Fig. 2. The crystal packing of (I), viewed along the a axis. Broken lines show N—H···O hydrogen bonds.

catena-Poly[[silver(I)-µ-ethane-1,2-diamine-κ²N:N'] trifluoromethanesulfonate]

Crystal data

[Ag(C2H8N2)](CF3SO3)	F(000) = 616
Mr = 317.04	Dx = 2.353 Mg m^−3
Orthorhombic, Pnma	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2n	Cell parameters from 2334 reflections
a = 8.711 (11) Å	θ = 2.8–28.0°
b = 10.050 (13) Å	µ = 2.51 mm^−1
c = 10.224 (13) Å	T = 298 K
V = 895 (2) Å^3	Block, colourless
Z = 4	0.21 × 0.10 × 0.08 mm

Data collection

Bruker SMART CCD area-detector diffractometer	1025 independent reflections
Radiation source: fine-focus sealed tube	972 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.029
ω scans	θmax = 27.0°, θmin = 2.8°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −11→11
Tmin = 0.621, Tmax = 0.824	k = −12→10
4585 measured reflections	l = −8→13

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)] = 0.033	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.076	H-atom parameters constrained
S = 1.19	w = 1/[σ^2(Fo^2) + (0.0314P)^2 + 1.0534P] where P = (Fo^2 + 2Fc^2)/3
1025 reflections	(Δ/σ)max < 0.001
67 parameters	Δρmax = 0.88 e Å^−3
0 restraints	Δρmin = −0.57 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.

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 (Ų)

	x	y	z	Uiso*/Ueq
Ag1	0.04722 (5)	0.7500	0.32019 (4)	0.04027 (16)
S1	0.64497 (13)	0.7500	0.56504 (11)	0.0301 (3)
N1	0.0457 (3)	0.5368 (3)	0.3239 (3)	0.0377 (7)
H1A	0.1436	0.5082	0.3234	0.080*
H1B	0.0011	0.5076	0.2498	0.080*
C2	0.4396 (6)	0.7500	0.5307 (5)	0.0379 (11)
C1	−0.0337 (4)	0.4751 (3)	0.4367 (3)	0.0357 (8)
H1C	−0.0282	0.3800	0.4296	0.080*
H1E	−0.1393	0.5025	0.4370	0.080*
O2	0.6658 (3)	0.6296 (3)	0.6389 (3)	0.0488 (7)
F1	0.3989 (3)	0.6442 (3)	0.4631 (3)	0.0720 (8)
O1	0.7145 (4)	0.7500	0.4376 (4)	0.0520 (10)
F2	0.3591 (4)	0.7500	0.6396 (4)	0.0689 (11)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ag1	0.0534 (3)	0.0290 (2)	0.0384 (3)	0.000	−0.00441 (17)	0.000
S1	0.0275 (5)	0.0282 (5)	0.0348 (6)	0.000	−0.0001 (5)	0.000
N1	0.0421 (16)	0.0318 (15)	0.0393 (17)	0.0039 (12)	0.0002 (13)	−0.0038 (12)
C2	0.034 (2)	0.041 (3)	0.039 (3)	0.000	0.001 (2)	0.000
C1	0.0382 (18)	0.0279 (16)	0.041 (2)	−0.0018 (14)	−0.0020 (15)	−0.0005 (14)
O2	0.0485 (15)	0.0375 (14)	0.0604 (17)	0.0066 (12)	−0.0065 (14)	0.0124 (12)
F1	0.0506 (13)	0.0715 (17)	0.094 (2)	−0.0167 (13)	−0.0110 (14)	−0.0339 (15)
O1	0.039 (2)	0.068 (3)	0.048 (2)	0.000	0.0116 (17)	0.000
F2	0.0445 (19)	0.102 (3)	0.060 (2)	0.000	0.0247 (18)	0.000

Geometric parameters (Å, º)

Ag1—N1^i	2.143 (4)	N1—H1B	0.8999
Ag1—N1	2.143 (4)	C2—F2	1.316 (6)
S1—O1	1.437 (4)	C2—F1	1.317 (4)
S1—O2^i	1.437 (3)	C2—F1^i	1.317 (4)
S1—O2	1.437 (3)	C1—C1^ii	1.506 (7)
S1—C2	1.823 (6)	C1—H1C	0.9600
N1—C1	1.481 (5)	C1—H1E	0.9601
N1—H1A	0.9001
N1^i—Ag1—N1	177.86 (15)	F2—C2—F1	107.5 (3)
O1—S1—O2^i	115.02 (15)	F2—C2—F1^i	107.5 (3)
O1—S1—O2	115.02 (15)	F1—C2—F1^i	107.7 (5)
O2^i—S1—O2	114.6 (3)	F2—C2—S1	111.1 (4)
O1—S1—C2	103.8 (3)	F1—C2—S1	111.5 (3)
O2^i—S1—C2	103.02 (15)	F1^i—C2—S1	111.5 (3)
O2—S1—C2	103.02 (15)	N1—C1—C1^ii	110.4 (4)
C1—N1—Ag1	115.8 (2)	N1—C1—H1C	109.5
C1—N1—H1A	108.2	C1^ii—C1—H1C	112.1
Ag1—N1—H1A	108.3	N1—C1—H1E	109.3
C1—N1—H1B	108.5	C1^ii—C1—H1E	106.0
Ag1—N1—H1B	108.3	H1C—C1—H1E	109.5
H1A—N1—H1B	107.5
N1—C1—C1^ii—N1^ii	−180.0	O1—S1—C2—F1	60.2 (3)
O2—S1—C2—F1	−60.1 (4)	O2^i—S1—C2—F1	−179.6 (3)
O2—S1—C2—F2	59.74 (14)	O1—S1—C2—F1^i	−60.2 (3)
O1—S1—C2—F2	180.0	O2^i—S1—C2—F1^i	60.1 (4)
O2^i—S1—C2—F2	−59.74 (14)	O2—S1—C2—F1^i	179.6 (3)

Symmetry codes: (i) x, −y+3/2, z; (ii) −x, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1B···O2^iii	0.90	2.30	3.126 (5)	152
N1—H1A···O2^iv	0.90	2.20	3.043 (5)	156

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