Poly[(μ2-2,2′-bipyridine-κ2 N:N′)bis­(μ3-2,2,2-trifluoro­acetato-κ3 O:O:O′)disilver(I)]

Hadi D Arman; Tyler Miller; Edward R T Tiekink

doi:10.1107/S1600536810035282

. 2010 Sep 4;66(Pt 10):m1209–m1210. doi: 10.1107/S1600536810035282

Poly[(μ₂-2,2′-bipyridine-κ² N:N′)bis(μ₃-2,2,2-trifluoroacetato-κ³ O:O:O′)disilver(I)]

Hadi D Arman ^a, Tyler Miller ^a, Edward R T Tiekink ^b,^*

PMCID: PMC2983243 PMID: 21587368

Abstract

In the title salt, [Ag₂(CF₃CO₂)₂(C₁₀H₈N₂)]_n, which may also be regarded as a coordination polymer if long Ag⋯O interactions are considered, each of the N atoms of the somewhat twisted 2,2′-bipyridine molecule [N—C—C—N = −27.5 (4)°] binds to an Ag atom, and each of the carboxylate ligands is tridentate, linking to three Ag atoms. The bidentate carboxylate O atoms bridge the same two Ag atoms, resulting in the formation of Ag₂O₂ rings. These rings are bridged by the 2,2′-bipyridine ligands, forming a chain along the b axis. The chains are linked into double chains via the remaining Ag—O bonds and Ag⋯Ag contacts. As a consequence of the Ag⋯Ag contacts, the NO₄ donor set about each Ag atom is heavily distorted. Finally, the chains are linked into a three-dimensional network by a combination of C—H⋯O and C—H⋯F interactions.

Related literature

For structural diversity in the supramolecular structures of silver salts, see: Kundu et al. (2010 ▶). For a related Ag salt, see: Arman et al. (2010 ▶).

Experimental

Crystal data

[Ag₂(C₂F₃O₂)₂(C₁₀H₈N₂)]
M _r = 597.96
Monoclinic,
a = 24.597 (6) Å
b = 6.8474 (14) Å
c = 21.253 (5) Å
β = 116.029 (4)°
V = 3216.5 (13) Å³
Z = 8
Mo Kα radiation
μ = 2.53 mm⁻¹
T = 98 K
0.31 × 0.29 × 0.20 mm

Data collection

Rigaku AFC12/SATURN724 diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.619, T _max = 1.000
10231 measured reflections
3662 independent reflections
3469 reflections with I > 2σ(I)
R _int = 0.037

Refinement

R[F ² > 2σ(F ²)] = 0.031
wR(F ²) = 0.091
S = 1.09
3661 reflections
253 parameters
H-atom parameters constrained
Δρ_max = 0.66 e Å⁻³
Δρ_min = −0.65 e Å⁻³

Data collection: CrystalClear (Molecular Structure Corporation & Rigaku, 2005 ▶); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810035282/hb5622sup1.cif

e-66-m1209-sup1.cif^{(22.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810035282/hb5622Isup2.hkl

e-66-m1209-Isup2.hkl^{(175.9KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Ag1—O1	2.284 (2)
Ag1—N1	2.309 (3)
Ag1—O2ⁱ	2.323 (3)
Ag1—O3ⁱⁱ	2.844 (2)
Ag1—O2	2.993 (3)
Ag1⋯Ag1ⁱ	3.0675 (9)
Ag1⋯Ag2	3.1941 (7)
Ag2—O3	2.276 (2)
Ag2—O4ⁱⁱⁱ	2.280 (3)
Ag2—N2	2.326 (3)
Ag2—O1^iv	2.837 (2)
Ag2—O4	3.069 (3)
Ag2⋯Ag2ⁱⁱⁱ	2.9687 (8)

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

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C4—H4⋯O1^v	0.95	2.50	3.410 (4)	159
C8—H8⋯O3^vi	0.95	2.58	3.287 (4)	132
C1—H1⋯F6ⁱⁱ	0.95	2.54	3.072 (4)	116
C2—H2⋯F4^vii	0.95	2.55	3.145 (4)	121
C10—H10⋯F3^iv	0.95	2.52	3.076 (4)	117

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

supplementary crystallographic information

Comment

Supramolecular structures of silver salts are highly dependent upon the nature of counter anions and the presence of solvent (Kundu et al., 2010). During the course of on-going crystal engineering studies on silver salts (Arman et al., 2010), the title salt was isolated and characterized.

The asymmetric unit of (I) comprises two Ag cations, a 2,2'-bipyridine molecule and two trifluoroacetate anions, Fig. 1. Each of the 2,2'-bipyridine-N atoms coordinates to a Ag atom bringing into close proximity the Ag1 and Ag2 atoms [Ag1···Ag2 = 3.1941 (7) Å]. In order to relive steric pressure, the 2,2'-bipyridine molecule is twisted as seen in the torsion angle [N1–C5–C6–N2 = -27.5 (4) °] and the dihedral angle formed between the pyridine rings of 26.93 (15) °. Each Ag atom forms a close Ag–O bond to a carboxylate-O, i.e. Ag1–O1 and Ag2–O3, Table 1, and each of the O1 and O3 atoms also bridges a neighbouring Ag atom to form a non-planar Ag₂O₂ ring. The second carboxylate-O atom in each case, i.e. O2 and O4, bridges to a different Ag atom so that each carboxylate ligand is tridentate. The supramolecular assembly is a double chain along the b axis whereby one row of Ag₂O₂ rings bridged by 2,2'-bipyridine molecules is connected to a second row via the Ag1–O2 and Ag2–O4 bonds and vice versa. Additional stability to the double chain is afforded by Ag1···Ag1 and Ag2···Ag2 interactions, Fig. 2 and Table 1. In terms of coordination geometry, each Ag atom exists within a NO₃ donor set which is grossly distorted owing to the presence of two close Ag···Ag contacts. Chains are consolidated in the crystal packing by a combination of C–H···O and C–H···F contacts, Table 2.

Experimental

2,2'-Bipyridine (0.015 g, 0.1 mmol) was dissolved in 5 ml of methanol. Added to this was silver trifluoroacetate (0.044 g, 0.2 mmol) dissolved in 7 ml of methanol. The resulting solution was gently heated and allowed to stand for slow evaporation affording colourless blocks of (I) after five days.