metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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

aDepartment of Chemistry and Chemical Engineering, Mianyang Normal University, Mianyang 621000, People's Republic of China
*Correspondence e-mail: wangzhiguo224865@163.com

(Received 20 May 2010; accepted 4 June 2010; online 26 June 2010)

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[Arnold, P. L. (2002). Heteroat. Chem. 13, 534-539.]); Lin & Vasam (2004[Lin, I. J. B. & Vasam, C. S. (2004). Comm. Inorg. Chem. 25, 75-129.]). For related structures, see: Lee et al. (2002[Lee, K. L., Wang, H. M. J. & Lin, I. J. B. (2002). J. Chem. Soc. Dalton Trans. pp. 2852-2856.]); Helgesson & Jagner (1990[Helgesson, G. & Jagner, S. (1990). J. Chem. Soc. Dalton Trans. pp. 2414-2420.], 1991[Helgesson, G. & Jagner, S. (1991). Inorg. Chem. 30, 2514-2571.]); Olson et al. (1994[Olson, S., Helgesson, G. & Jagner, S. (1994). Inorg. Chim. Acta, 217, 15-20.]).

[Scheme 1]

Experimental

Crystal data
  • (C12H20N4)[Ag2Br4]

  • Mr = 755.90

  • Monoclinic, P 21 /c

  • 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[Sheldrick, G. M. (2006). SADABS. University of Göttingen, Germany.]) Tmin = 0.191, Tmax = 0.219

  • 5036 measured reflections

  • 1766 independent reflections

  • 1533 reflections with I > 2σ(I)

  • Rint = 0.023

Refinement
  • R[F2 > 2σ(F2)] = 0.031

  • wR(F2) = 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

Table 1
Selected geometric parameters (Å, °)

Ag1—Br1 2.6788 (7)
Ag1—Br2i 2.6934 (8)
Ag1—Br1ii 2.6999 (7)
Ag1—Br2 2.7227 (8)
Br1—Ag1—Br2i 114.34 (3)
Br1—Ag1—Br1ii 103.92 (2)
Br2i—Ag1—Br1ii 116.12 (3)
Br1—Ag1—Br2 119.16 (3)
Br2i—Ag1—Br2 95.81 (2)
Br1ii—Ag1—Br2 107.93 (2)
Symmetry codes: (i) -x, -y+1, -z+2; (ii) [x, -y+{\script{3\over 2}}, z+{\script{1\over 2}}].

Data collection: SMART (Bruker, 2006[Bruker (2006). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2006[Bruker (2006). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: DIAMOND (Crystal Impact, 2008[Crystal Impact (2008). DIAMOND. Crystal Impact GmbH, Bonn, Germany.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

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).

Related literature top

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

Experimental top

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 top

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).

Computing details top

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

Figures top
[Figure 1] 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.
[Figure 2] Fig. 2. The four- and twelve-membered ring system of the polymeric {[Ag2Br4]2-}n anion.
Poly[3,3'-diethyl-1,1'-(ethane-1,2-diyl)diimidazolium [tetra-µ-bromido-diargentate(I)]] top
Crystal data top
(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 top
Bruker SMART CCD area-detector
diffractometer
1766 independent reflections
Radiation source: fine-focus sealed tube1533 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.023
phi and ω scansθmax = 25.0°, θmin = 2.7°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2006)
h = 1111
Tmin = 0.191, Tmax = 0.219k = 1514
5036 measured reflectionsl = 105
Refinement top
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 = 1.06 w = 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
Crystal data top
(C12H20N4)[Ag2Br4]V = 1004.9 (2) Å3
Mr = 755.90Z = 2
Monoclinic, P21/cMo Kα radiation
a = 9.5593 (13) ŵ = 9.90 mm1
b = 12.9512 (17) ÅT = 296 K
c = 8.4565 (11) Å0.25 × 0.24 × 0.22 mm
β = 106.294 (2)°
Data collection top
Bruker SMART CCD area-detector
diffractometer
1766 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2006)
1533 reflections with I > 2σ(I)
Tmin = 0.191, Tmax = 0.219Rint = 0.023
5036 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0310 restraints
wR(F2) = 0.077H-atom parameters constrained
S = 1.06Δρmax = 0.64 e Å3
1766 reflectionsΔρmin = 0.88 e Å3
101 parameters
Special details top

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) top
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) top
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, º) top
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—Ag1iv123.08 (5)C2—N2—C3—N11.2 (7)
Br2—Ag1—Br1—Ag1iv116.83 (6)C4—N2—C3—N1177.9 (7)
Br1—Ag1—Br2—Ag1i122.09 (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—C518.3 (12)
C3—N1—C1—C21.5 (7)C2—N2—C4—C5165.6 (8)
C6—N1—C1—C2179.6 (5)C3—N1—C6—C6iii98.5 (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, z1/2.

Experimental details

Crystal data
Chemical formula(C12H20N4)[Ag2Br4]
Mr755.90
Crystal system, space groupMonoclinic, P21/c
Temperature (K)296
a, b, c (Å)9.5593 (13), 12.9512 (17), 8.4565 (11)
β (°) 106.294 (2)
V3)1004.9 (2)
Z2
Radiation typeMo Kα
µ (mm1)9.90
Crystal size (mm)0.25 × 0.24 × 0.22
Data collection
DiffractometerBruker SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 2006)
Tmin, Tmax0.191, 0.219
No. of measured, independent and
observed [I > 2σ(I)] reflections
5036, 1766, 1533
Rint0.023
(sin θ/λ)max1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.031, 0.077, 1.06
No. of reflections1766
No. of parameters101
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.64, 0.88

Computer programs: SMART (Bruker, 2006), SAINT (Bruker, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Crystal Impact, 2008).

Selected geometric parameters (Å, º) top
Ag1—Br12.6788 (7)Ag1—Br1ii2.6999 (7)
Ag1—Br2i2.6934 (8)Ag1—Br22.7227 (8)
Br1—Ag1—Br2i114.34 (3)Br1—Ag1—Br2119.16 (3)
Br1—Ag1—Br1ii103.92 (2)Br2i—Ag1—Br295.81 (2)
Br2i—Ag1—Br1ii116.12 (3)Br1ii—Ag1—Br2107.93 (2)
Symmetry codes: (i) x, y+1, z+2; (ii) x, y+3/2, z+1/2.
 

Acknowledgements

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

References

First citationArnold, P. L. (2002). Heteroat. Chem. 13, 534–539.  Web of Science CrossRef CAS Google Scholar
First citationBruker (2006). SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationCrystal Impact (2008). DIAMOND. Crystal Impact GmbH, Bonn, Germany.  Google Scholar
First citationHelgesson, G. & Jagner, S. (1990). J. Chem. Soc. Dalton Trans. pp. 2414–2420.  Google Scholar
First citationHelgesson, G. & Jagner, S. (1991). Inorg. Chem. 30, 2514–2571.  CSD CrossRef Web of Science Google Scholar
First citationLee, K. L., Wang, H. M. J. & Lin, I. J. B. (2002). J. Chem. Soc. Dalton Trans. pp. 2852–2856.  Web of Science CSD CrossRef Google Scholar
First citationLin, I. J. B. & Vasam, C. S. (2004). Comm. Inorg. Chem. 25, 75–129.  Web of Science CrossRef CAS Google Scholar
First citationOlson, S., Helgesson, G. & Jagner, S. (1994). Inorg. Chim. Acta, 217, 15–20.  CSD CrossRef CAS Web of Science Google Scholar
First citationSheldrick, G. M. (2006). SADABS. University of Göttingen, Germany.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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