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Acta Crystallogr Sect E Struct Rep Online. 2010 July 1; 66(Pt 7): m845.
Published online 2010 June 26. doi:  10.1107/S160053681002146X
PMCID: PMC3006904

Poly[3,3′-diethyl-1,1′-(ethane-1,2-di­yl)diimidazolium [tetra-μ-bromido-­diargentate(I)]]

Abstract

The asymmetric unit of the title salt, {(C12H20N4)[Ag2Br4]}n, contains one-half of a substituted imidazolium cation, one Ag+ and two Br ions. The cation is completed by crystallographic inversion symmetry. The crystal structure is made up from polymeric sheets of {[AgBr2]}n anions extending parallel to (100). The basic building unit of the anion is a slightly distorted AgBr4 tetra­hedron. A four- and 12-membered ring system is formed by corner sharing of the AgBr4 tetra­hedra. The imidazolium cations are located between the anionic sheets and partly protrude into the voids defined by the 12-membered rings.

Related literature

For general background to N-heterocyclic carbenes, see: Arnold (2002 [triangle]); Lin & Vasam (2004 [triangle]). For related structures, see: Lee et al. (2002 [triangle]); Helgesson & Jagner (1990 [triangle], 1991 [triangle]); Olson et al. (1994 [triangle]).

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Object name is e-66-0m845-scheme1.jpg

Experimental

Crystal data

  • (C12H20N4)[Ag2Br4]
  • M r = 755.90
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-66-0m845-efi1.jpg
  • a = 9.5593 (13) Å
  • b = 12.9512 (17) Å
  • c = 8.4565 (11) Å
  • β = 106.294 (2)°
  • V = 1004.9 (2) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 9.90 mm−1
  • T = 296 K
  • 0.25 × 0.24 × 0.22 mm

Data collection

  • Bruker SMART CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 2006 [triangle]) T min = 0.191, T max = 0.219
  • 5036 measured reflections
  • 1766 independent reflections
  • 1533 reflections with I > 2σ(I)
  • R int = 0.023

Refinement

  • R[F 2 > 2σ(F 2)] = 0.031
  • wR(F 2) = 0.077
  • S = 1.06
  • 1766 reflections
  • 101 parameters
  • H-atom parameters constrained
  • Δρmax = 0.64 e Å−3
  • Δρmin = −0.88 e Å−3

Data collection: SMART (Bruker, 2006 [triangle]); cell refinement: SAINT (Bruker, 2006 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: DIAMOND (Crystal Impact, 2008 [triangle]); software used to prepare material for publication: SHELXL97.

Table 1
Selected geometric parameters (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053681002146X/wm2354sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053681002146X/wm2354Isup2.hkl

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

Acknowledgments

The authors thank the Sichuan Province Youth Foundation of Science and Technology (09 J J0088) for financial support.

supplementary crystallographic information

Comment

Silver and other transition metal N-heterocyclic carbene complexes have played an important role in the development of metal-carbene systems for transmetalation reactions. Silver oxide is the most commonly used metal base for this purposes. Recent reviews dealing with silver N-heterocyclic carbenes were published by Arnold (2002) and Lin & Vasam (2004). The products differ depending upon reaction conditions and the imidazolium salt used. The silver carbene [Ag2(Me2-edimy)Cl2] has been successfully synthesized by the reaction of [Me2-edimyH2][PF6]2 with Ag2O in CH3CN and [NM4]Cl (Lee et al., 2002). In an attempt to prepare a similar carbene, we obtained the title compound, [(C12H20N4)]2+[Ag2Br4]2-, instead. Synthesis and crystal structure are reported in this article.

The crystal structure of the title salt is composed of [(C12H20N4)]2+ cations and [Ag2Br4]2- anions (Fig. 1). The anion forms polymeric sheets extending parallel to (100). The cations are located between the sheets and partly reach through the voids of the anion. A characteristic feature of the polymeric {[Ag2Br4]2-}n anion is the construction of rings built up from corner-sharing of slightly distorted AgBr4 tetrahedra. A large twelve-membered ring is formed by six alternating bromine and six silver atoms; another four-membered ring completes the building units of the polymeric anion (Fig. 2). The four-membered ring is very similar to that in the complex anion [Ag4Br8]4- (Helgesson & Jagner, 1991). These anions contain tetrahedrally coordinated Ag+ atoms, whereas the [Ag4I8]4- ion, isolated as the tetraphenylphosphonium and tetraphenylarsonium salts, contains three-coordinated and four-coordinated Ag+ (Helgesson & Jagner, 1990).

The average Ag—Br distance of the AgBr4 tetrahedron in the title compound is 2.699 Å, which is considerably longer than for the [Ag2Br4]2- dimer ((2.518 (2) Å; Helgesson et al., 1990). These values are comparable to other tetrahedral AgBr4 units (Olson et al., 1994).

Experimental

Ag2O (2.32 g, 10 mmol) was added to a solution of 1H-imidazolium, 1,1'-(1,2-ethanediyl)bis[3-ethyl] dibromide (3.78 g, 10 mmol) in DMSO. This mixture was refluxed for 30 min under stirring, resulting in a clean solution. When the solvent was removed, the residue was exatracted with acetonitrile. The remaining residue was separated by centrifugation and the resulting solution was kept at room temperature. Colourless crystals of the title compound were obtained after slow evaporation (2.64 g, 34.9 % yield). Mp: 421 K. 1H NMR (CDCl3): 9.48(m,1H), 9.43 (m.1H), 6.84 (s, 2H, CH), 6.87 (s, 2H, CH), 4.52 (s, 4H, CH2), 3.64(s, 4H, CH3),1.42(m, 6H) ppm. Anal. calcd.: C, 19.05 H, 2.65; N, 7.41; found: C, 19.26; H, 2.57 ; N, 7.32%.

Refinement

The H atoms attached to C atoms of the imidazole ring were positioned geometrically and allowed to ride on their parent atoms, with a C—H distance of 0.93 Å and Uiso(H) = 1.2Ueq(C). Methylene and methyl H atoms were likewise positioned geometrically and refined as riding atoms, with C—H = 0.97 Å (methylene) and C—H = 0.96 Å (methyl) and Uiso(H) = 1.2Ueq(C).

Figures

Fig. 1.
The [(C12H20N4)]2+ cation and the basic AgBr4 building unit of the polymeric anion. Displacement ellipsoids are drawn at the 30% probability level.
Fig. 2.
The four- and twelve-membered ring system of the polymeric {[Ag2Br4]2-}n anion.

Crystal data

(C12H20N4)[Ag2Br4]F(000) = 708
Mr = 755.90Dx = 2.498 Mg m3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3112 reflections
a = 9.5593 (13) Åθ = 2.2–27.8°
b = 12.9512 (17) ŵ = 9.90 mm1
c = 8.4565 (11) ÅT = 296 K
β = 106.294 (2)°Block, colourless
V = 1004.9 (2) Å30.25 × 0.24 × 0.22 mm
Z = 2

Data collection

Bruker SMART CCD area-detector diffractometer1766 independent reflections
Radiation source: fine-focus sealed tube1533 reflections with I > 2σ(I)
graphiteRint = 0.023
phi and ω scansθmax = 25.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 2006)h = −11→11
Tmin = 0.191, Tmax = 0.219k = −15→14
5036 measured reflectionsl = −10→5

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.031Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.077H-atom parameters constrained
S = 1.06w = 1/[σ2(Fo2) + (0.0366P)2 + 1.7373P] where P = (Fo2 + 2Fc2)/3
1766 reflections(Δ/σ)max = 0.001
101 parametersΔρmax = 0.64 e Å3
0 restraintsΔρmin = −0.88 e Å3

Special details

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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)

xyzUiso*/Ueq
Ag10.06806 (5)0.63160 (3)1.01898 (5)0.05733 (16)
N10.8101 (4)0.5496 (3)0.4321 (5)0.0424 (9)
N20.6179 (5)0.6042 (4)0.2519 (6)0.0575 (12)
Br10.13558 (8)0.75994 (4)0.80302 (6)0.0632 (2)
Br20.20441 (6)0.44528 (4)1.08097 (7)0.05774 (18)
C10.6983 (6)0.4833 (5)0.4277 (8)0.0646 (16)
H10.70400.42390.49110.078*
C20.5809 (6)0.5178 (5)0.3180 (8)0.0650 (16)
H20.48890.48770.29120.078*
C30.7579 (6)0.6221 (5)0.3208 (7)0.0584 (14)
H30.81100.67660.29520.070*
C40.5147 (8)0.6630 (6)0.1169 (10)0.095 (3)
H4A0.49880.62410.01530.114*
H4B0.42190.66830.14170.114*
C50.5611 (12)0.7605 (6)0.0923 (13)0.121 (4)
H5A0.57110.80120.18980.182*
H5B0.49110.79230.00120.182*
H5C0.65350.75630.06880.182*
C60.9600 (5)0.5390 (4)0.5370 (6)0.0432 (11)
H6A0.95940.51690.64640.052*
H6B1.00930.60520.54690.052*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Ag10.0590 (3)0.0526 (3)0.0561 (3)−0.0056 (2)0.0091 (2)0.00076 (18)
N10.031 (2)0.048 (2)0.045 (2)−0.0008 (18)0.0046 (17)0.0031 (18)
N20.039 (3)0.074 (3)0.053 (3)0.005 (2)0.002 (2)0.013 (2)
Br10.1030 (5)0.0489 (3)0.0362 (3)−0.0160 (3)0.0171 (3)0.0008 (2)
Br20.0326 (3)0.0547 (3)0.0783 (4)0.0051 (2)0.0029 (2)−0.0090 (3)
C10.039 (3)0.058 (3)0.088 (4)−0.008 (3)0.002 (3)0.023 (3)
C20.035 (3)0.068 (4)0.083 (4)−0.006 (3)0.002 (3)0.014 (3)
C30.045 (3)0.068 (4)0.061 (4)−0.005 (3)0.013 (3)0.017 (3)
C40.064 (5)0.106 (6)0.096 (6)0.003 (4)−0.007 (4)0.043 (5)
C50.135 (9)0.067 (5)0.125 (8)0.012 (5)−0.026 (6)0.003 (5)
C60.035 (3)0.051 (3)0.040 (3)−0.004 (2)0.005 (2)−0.008 (2)

Geometric parameters (Å, °)

Ag1—Br12.6788 (7)C2—H20.9300
Ag1—Br2i2.6934 (8)C3—H30.9300
Ag1—Br1ii2.6999 (7)C4—C51.374 (10)
Ag1—Br22.7227 (8)C4—H4A0.9700
N1—C31.324 (6)C4—H4B0.9700
N1—C11.363 (7)C5—H5A0.9600
N1—C61.466 (6)C5—H5B0.9600
N2—C31.321 (7)C5—H5C0.9600
N2—C21.341 (7)C6—C6iii1.506 (9)
N2—C41.491 (8)C6—H6A0.9700
C1—C21.317 (8)C6—H6B0.9700
C1—H10.9300
Br1—Ag1—Br2i114.34 (3)N2—C3—H3125.6
Br1—Ag1—Br1ii103.92 (2)N1—C3—H3125.6
Br2i—Ag1—Br1ii116.12 (3)C5—C4—N2114.4 (7)
Br1—Ag1—Br2119.16 (3)C5—C4—H4A108.7
Br2i—Ag1—Br295.81 (2)N2—C4—H4A108.7
Br1ii—Ag1—Br2107.93 (2)C5—C4—H4B108.7
C3—N1—C1106.9 (4)N2—C4—H4B108.7
C3—N1—C6127.3 (4)H4A—C4—H4B107.6
C1—N1—C6125.7 (4)C4—C5—H5A109.5
C3—N2—C2108.4 (5)C4—C5—H5B109.5
C3—N2—C4128.2 (5)H5A—C5—H5B109.5
C2—N2—C4123.4 (5)C4—C5—H5C109.5
Ag1—Br1—Ag1iv152.39 (4)H5A—C5—H5C109.5
Ag1i—Br2—Ag184.19 (2)H5B—C5—H5C109.5
C2—C1—N1108.1 (5)N1—C6—C6iii109.6 (5)
C2—C1—H1125.9N1—C6—H6A109.8
N1—C1—H1125.9C6iii—C6—H6A109.8
C1—C2—N2107.8 (5)N1—C6—H6B109.8
C1—C2—H2126.1C6iii—C6—H6B109.8
N2—C2—H2126.1H6A—C6—H6B108.2
N2—C3—N1108.8 (5)
Br2i—Ag1—Br1—Ag1iv4.51 (7)C4—N2—C2—C1177.1 (7)
Br1ii—Ag1—Br1—Ag1iv−123.08 (5)C2—N2—C3—N1−1.2 (7)
Br2—Ag1—Br1—Ag1iv116.83 (6)C4—N2—C3—N1−177.9 (7)
Br1—Ag1—Br2—Ag1i−122.09 (3)C1—N1—C3—N21.7 (7)
Br2i—Ag1—Br2—Ag1i0.0C6—N1—C3—N2179.7 (5)
Br1ii—Ag1—Br2—Ag1i119.87 (3)C3—N2—C4—C5−18.3 (12)
C3—N1—C1—C2−1.5 (7)C2—N2—C4—C5165.6 (8)
C6—N1—C1—C2−179.6 (5)C3—N1—C6—C6iii−98.5 (7)
N1—C1—C2—N20.8 (8)C1—N1—C6—C6iii79.1 (7)
C3—N2—C2—C10.2 (8)

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WM2354).

References

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  • Bruker (2006). SMART and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Crystal Impact (2008). DIAMOND Crystal Impact GmbH, Bonn, Germany.
  • Helgesson, G. & Jagner, S. (1990). J. Chem. Soc. Dalton Trans. pp. 2414–2420.
  • Helgesson, G. & Jagner, S. (1991). Inorg. Chem.30, 2514–2571.
  • Lee, K. L., Wang, H. M. J. & Lin, I. J. B. (2002). J. Chem. Soc. Dalton Trans. pp. 2852–2856.
  • Lin, I. J. B. & Vasam, C. S. (2004). Comm. Inorg. Chem.25, 75–129.
  • Olson, S., Helgesson, G. & Jagner, S. (1994). Inorg. Chim. Acta, 217, 15–20.
  • Sheldrick, G. M. (2006). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]

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