metal-organic compounds
catena-Poly[di-μ3-bromido-bis[(1-ethyl-1H-imidazole-κN3)disilver(I)]]
aDepartment of Chemistry and Chemical Engineering, Mianyang Normal University, Mianyang 621000, People's Republic of China
*Correspondence e-mail: wangzhiguo224865@163.com
The 2Br2(C5H8N2)2]n, comprises a monodentate 1-ethylimidazole ligand, an Ag+ cation and a μ3-bridging Br− anion, giving a distorted tetrahedral AgNBr3 stereochemistry about the Ag+ cation [Ag—N = 2.247 (2) Å and Ag—Br = 2.7372 (4)–2.7523 (4) Å]. Two bridging bromide anions generate the dimeric [Ag2Br2(C5H8N)2] repeat unit [Ag⋯Ag = 3.0028 (5) Å], while a third Br− anion links the units through corner sharing in an inversion-related Ag2Br2 association [Ag⋯Ag = 3.0407 (4) Å], generating a one-dimensional ribbon step-polymer structure, extending along the c axis.
of the title coordination complex, [AgRelated literature
For general background to N-heterocyclic see: Arnold (2002); Lin & Vasam (2004). For related structures, see: Wang & Lin (1998); Liu et al. (2003); Helgesson & Jagner (1990, 1991); Chen & Liu (2003).
Experimental
Crystal data
|
Data collection: APEX2 (Bruker, 2006); cell SAINT (Bruker, 2006); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.
Supporting information
https://doi.org/10.1107/S1600536813016875/zs2262sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536813016875/zs2262Isup2.hkl
1,2-Dibromocyclohexane (2.42 g, 10 mmol) was added to a solution of 1-ethylimidazole (1.92 g, 20 mmol) in DMSO (100 ml) at room temperature and stirred for 2 h, after which Ag2O (2.32 g, 10 mmol) was added and the mixture was refluxed for 3 h with stirring. The volume of the solution was reduced to 50 ml under vacuum, the residue was removed by filtration and the filtrate was kept at room temperature for a few days. Colorless crystals of the title compound were obtained after slow evaporation (1.74 g, 30% yield). (mp: 335 K). 1H NMR(CDCl3): 9.42(m,1H), 6.88(s, 1H, CH), 6.84 (s, 1H, CH), 4.54(s, 2H, CH2), 3.65 (s, 3H, CH3)p.p.m. Anal. calcd.: C, 21.12; H, 2.82; N, 9.86%; found: C, 21.05; H, 2.76; N, 9.75%.
The H atoms attached to C atoms of the imidazole ring were positioned geometrically and allowed to ride on their parent atoms, with C—H = 0.95 Å and Uiso(H) = 1.2Ueq(C). Methylene and methyl H atoms were likewise positioned geometrically (C—H = 0.99 and 0.98 Å, respectively) and also refined as riding atoms, and Uiso(H) = 1.2Ueq(C)
Silver and other transition metal N-heterocyclic carbene complexes have played an important role in development of metal-carbene systems for transmetalation reactions. Recent reviews dealing with silver N-heterocyclic
were published by Arnold (2002) and Lin & Vasam (2004). The products differ depending upon reaction conditions and the imidazolium salt used. Deprotonation by use of Ag2O has been the most widely used method in the syntheses of N-heterocyclic carbene complexes of silver. The procedure can be accomplished using the reaction of Ag2O with the imidazolium salt in CH2Cl2 solution. The 3-diethylbenzole N-heterocyclic carbene complexes of silver have been successfully synthesized by the reaction of the 1,3-diethylbenzolium salt with Ag2O in CH2Cl2 (Wang & Lin, 1998). In an attempt to prepare similar N-heterocyclic carbene complexes of silver by the reaction of Ag2O with 1,2-dibromocyclohexane and 1-ethylimidazole in DMSO solution, we obtained the title compound, [(C5H8N)2Ag2Br2]n, instead and the synthesis and are reported herein. Although the stair polymers of [(C5H5N)4Ag4I4]n (Liu et al., 2003) and 1-allyl-3-methylimidazole carbine silver iodide (Chen & Liu, 2003) have recently been reported, their structural features are different from that of the title complex being formed through triple and quadruple halide bridges with Ag···Ag interactions.In the title complex the
comprises one monodentate 1-ethylimidazole ligand, an Ag+ cation and a doubly bridging Br- anion, giving a distorted tetrahedral AgNBr3stereochemistry about silver [Ag—N, 2.247 (2) Å; Ag—Br, 2.7372 (4)–2.7752 (3) Å and bond angle range about Ag of 106.78 (6)–113.55 (5)°] (Fig. 1). These Ag—Br bond distances are considerably longer than those found in the [Ag2Br4]2- complex anion [2.518 (2) Å] (Helgesson & Jagner, 1990). The Ag1—N1 bond [2.247 (2) Å] is somewhat shorter than 2.335 Å found in the pyridine silver iodide polymer [(C5H5N)4Ag4I4]n (Liu et al., 2003). The dimeric Ag2Br2 repeating core unit in the title complex is generated through a double Br bridge, giving an Ag···Agi separation of 3.0028(r) Å [for symmetry code (i): -x + 1, y, -z) + 1/2]. The four-membered core ring so formed is very similar to that in the complex anion [Ag4Br8]4-(Helgesson & Jagner, 1991).The basic coomplex is extended into a one-dimensional step-polymer ribbon structure through centrosymmetric Ag—Br and Br—Ag bonds along the c axial direction (Fig. 2). Within these cyclic Ag2Br2 linkages, the Ag···Agiii separation is 3.0407 (4) Å [for symmetry code (iii): -x + 1, -y + 1, -z].
For general background to N-heterocyclic
see: Arnold (2002); Lin & Vasam (2004). For related structures, see: Wang & Lin (1998); Liu et al. (2003); Helgesson & Jagner (1990, 1991); Chen & Liu (2003).Data collection: APEX2 (Bruker, 2006); cell
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: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).[Ag2Br2(C5H8N2)2] | F(000) = 1072 |
Mr = 567.80 | Dx = 2.434 Mg m−3 |
Monoclinic, C2/c | Melting point: 335 K |
Hall symbol: -C 2yc | Mo Kα radiation, λ = 0.71073 Å |
a = 15.2489 (15) Å | Cell parameters from 3344 reflections |
b = 13.9888 (13) Å | θ = 2.8–28.4° |
c = 7.7198 (7) Å | µ = 7.67 mm−1 |
β = 109.809 (1)° | T = 173 K |
V = 1549.3 (3) Å3 | Block, colourless |
Z = 4 | 0.17 × 0.16 × 0.15 mm |
Bruker APEXII CCD diffractometer | 1362 independent reflections |
Radiation source: fine-focus sealed tube | 1315 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.024 |
φ and ω scans | θmax = 25.0°, θmin = 2.9° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −16→18 |
Tmin = 0.355, Tmax = 0.392 | k = −16→14 |
3840 measured reflections | l = −6→9 |
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)] = 0.019 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.048 | H-atom parameters constrained |
S = 1.05 | w = 1/[σ2(Fo2) + (0.025P)2 + 1.7996P] where P = (Fo2 + 2Fc2)/3 |
1362 reflections | (Δ/σ)max < 0.001 |
83 parameters | Δρmax = 0.38 e Å−3 |
0 restraints | Δρmin = −0.68 e Å−3 |
[Ag2Br2(C5H8N2)2] | V = 1549.3 (3) Å3 |
Mr = 567.80 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 15.2489 (15) Å | µ = 7.67 mm−1 |
b = 13.9888 (13) Å | T = 173 K |
c = 7.7198 (7) Å | 0.17 × 0.16 × 0.15 mm |
β = 109.809 (1)° |
Bruker APEXII CCD diffractometer | 1362 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1315 reflections with I > 2σ(I) |
Tmin = 0.355, Tmax = 0.392 | Rint = 0.024 |
3840 measured reflections |
R[F2 > 2σ(F2)] = 0.019 | 0 restraints |
wR(F2) = 0.048 | H-atom parameters constrained |
S = 1.05 | Δρmax = 0.38 e Å−3 |
1362 reflections | Δρmin = −0.68 e Å−3 |
83 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Ag1 | 0.445475 (14) | 0.080848 (14) | −0.12049 (3) | 0.02369 (10) | |
Br1 | 0.363999 (18) | 0.066857 (18) | −0.49464 (4) | 0.01975 (10) | |
N1 | 0.39450 (15) | 0.21798 (15) | −0.0362 (3) | 0.0183 (5) | |
N2 | 0.34342 (14) | 0.31681 (15) | 0.1304 (3) | 0.0204 (5) | |
C1 | 0.38660 (17) | 0.23374 (18) | 0.1262 (4) | 0.0182 (5) | |
H1 | 0.4088 | 0.1914 | 0.2280 | 0.022* | |
C2 | 0.32148 (18) | 0.35730 (18) | −0.0411 (4) | 0.0236 (6) | |
H2 | 0.2903 | 0.4163 | −0.0808 | 0.028* | |
C3 | 0.35336 (18) | 0.29593 (19) | −0.1426 (4) | 0.0216 (6) | |
H3 | 0.3482 | 0.3052 | −0.2676 | 0.026* | |
C4 | 0.3277 (2) | 0.3578 (2) | 0.2924 (4) | 0.0307 (7) | |
H4A | 0.3101 | 0.3061 | 0.3618 | 0.037* | |
H4B | 0.2751 | 0.4036 | 0.2514 | 0.037* | |
C5 | 0.4122 (2) | 0.4081 (2) | 0.4169 (4) | 0.0295 (7) | |
H5A | 0.4648 | 0.3635 | 0.4555 | 0.044* | |
H5B | 0.3996 | 0.4318 | 0.5256 | 0.044* | |
H5C | 0.4275 | 0.4620 | 0.3512 | 0.044* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ag1 | 0.02308 (14) | 0.02533 (14) | 0.02428 (15) | 0.00355 (7) | 0.01013 (10) | −0.00298 (8) |
Br1 | 0.01675 (15) | 0.02566 (16) | 0.01700 (17) | 0.00117 (9) | 0.00595 (12) | 0.00022 (10) |
N1 | 0.0171 (11) | 0.0193 (10) | 0.0203 (12) | −0.0016 (9) | 0.0089 (9) | −0.0010 (9) |
N2 | 0.0145 (10) | 0.0223 (11) | 0.0242 (12) | −0.0017 (9) | 0.0064 (9) | −0.0064 (9) |
C1 | 0.0148 (12) | 0.0213 (13) | 0.0179 (13) | −0.0015 (10) | 0.0046 (10) | −0.0001 (10) |
C2 | 0.0193 (13) | 0.0171 (13) | 0.0312 (15) | −0.0016 (10) | 0.0043 (11) | 0.0014 (11) |
C3 | 0.0201 (13) | 0.0219 (13) | 0.0215 (14) | −0.0036 (10) | 0.0053 (11) | 0.0047 (11) |
C4 | 0.0247 (15) | 0.0373 (17) | 0.0332 (17) | −0.0033 (12) | 0.0138 (13) | −0.0189 (13) |
C5 | 0.0228 (15) | 0.0343 (15) | 0.0287 (17) | 0.0016 (12) | 0.0050 (13) | −0.0108 (13) |
Ag1—N1 | 2.247 (2) | N2—C4 | 1.467 (3) |
Ag1—Br1 | 2.7372 (4) | C1—H1 | 0.9500 |
Ag1—Br1i | 2.7420 (4) | C2—C3 | 1.358 (4) |
Ag1—Br1ii | 2.7523 (4) | C2—H2 | 0.9500 |
Ag1—Ag1i | 3.0028 (5) | C3—H3 | 0.9500 |
Ag1—Ag1iii | 3.0407 (4) | C4—C5 | 1.497 (4) |
Br1—Ag1i | 2.7420 (4) | C4—H4A | 0.9900 |
Br1—Ag1iv | 2.7522 (4) | C4—H4B | 0.9900 |
N1—C1 | 1.318 (3) | C5—H5A | 0.9800 |
N1—C3 | 1.381 (3) | C5—H5B | 0.9800 |
N2—C1 | 1.342 (3) | C5—H5C | 0.9800 |
N2—C2 | 1.374 (4) | ||
N1—Ag1—Br1 | 106.78 (6) | C2—N2—C4 | 127.2 (2) |
N1—Ag1—Br1i | 113.55 (5) | N1—C1—N2 | 111.8 (2) |
Br1—Ag1—Br1i | 112.899 (9) | N1—C1—H1 | 124.1 |
N1—Ag1—Br1ii | 107.26 (5) | N2—C1—H1 | 124.1 |
Br1—Ag1—Br1ii | 102.771 (10) | C3—C2—N2 | 106.1 (2) |
Br1i—Ag1—Br1ii | 112.797 (10) | C3—C2—H2 | 126.9 |
N1—Ag1—Ag1i | 121.11 (5) | N2—C2—H2 | 126.9 |
Br1—Ag1—Ag1i | 56.845 (11) | C2—C3—N1 | 109.6 (2) |
Br1i—Ag1—Ag1i | 56.690 (10) | C2—C3—H3 | 125.2 |
Br1ii—Ag1—Ag1i | 130.781 (8) | N1—C3—H3 | 125.2 |
N1—Ag1—Ag1iii | 128.97 (6) | N2—C4—C5 | 112.2 (2) |
Br1—Ag1—Ag1iii | 123.435 (12) | N2—C4—H4A | 109.2 |
Br1i—Ag1—Ag1iii | 56.559 (9) | C5—C4—H4A | 109.2 |
Br1ii—Ag1—Ag1iii | 56.238 (11) | N2—C4—H4B | 109.2 |
Ag1i—Ag1—Ag1iii | 95.508 (11) | C5—C4—H4B | 109.2 |
Ag1—Br1—Ag1i | 66.464 (9) | H4A—C4—H4B | 107.9 |
Ag1—Br1—Ag1iv | 109.172 (11) | C4—C5—H5A | 109.5 |
Ag1i—Br1—Ag1iv | 67.204 (10) | C4—C5—H5B | 109.5 |
C1—N1—C3 | 105.3 (2) | H5A—C5—H5B | 109.5 |
C1—N1—Ag1 | 124.76 (17) | C4—C5—H5C | 109.5 |
C3—N1—Ag1 | 129.32 (18) | H5A—C5—H5C | 109.5 |
C1—N2—C2 | 107.1 (2) | H5B—C5—H5C | 109.5 |
C1—N2—C4 | 125.6 (2) | ||
N1—Ag1—Br1—Ag1i | 116.60 (6) | Br1i—Ag1—N1—C3 | 107.5 (2) |
Br1i—Ag1—Br1—Ag1i | −8.881 (15) | Br1ii—Ag1—N1—C3 | −127.1 (2) |
Br1ii—Ag1—Br1—Ag1i | −130.686 (9) | Ag1i—Ag1—N1—C3 | 43.4 (2) |
Ag1iii—Ag1—Br1—Ag1i | −72.907 (15) | Ag1iii—Ag1—N1—C3 | 172.66 (18) |
N1—Ag1—Br1—Ag1iv | 169.81 (6) | C3—N1—C1—N2 | −0.2 (3) |
Br1i—Ag1—Br1—Ag1iv | 44.330 (16) | Ag1—N1—C1—N2 | −172.05 (16) |
Br1ii—Ag1—Br1—Ag1iv | −77.474 (18) | C2—N2—C1—N1 | 0.3 (3) |
Ag1i—Ag1—Br1—Ag1iv | 53.212 (9) | C4—N2—C1—N1 | −176.8 (2) |
Ag1iii—Ag1—Br1—Ag1iv | −19.696 (19) | C1—N2—C2—C3 | −0.3 (3) |
Br1—Ag1—N1—C1 | 152.24 (18) | C4—N2—C2—C3 | 176.8 (2) |
Br1i—Ag1—N1—C1 | −82.7 (2) | N2—C2—C3—N1 | 0.1 (3) |
Br1ii—Ag1—N1—C1 | 42.6 (2) | C1—N1—C3—C2 | 0.0 (3) |
Ag1i—Ag1—N1—C1 | −146.79 (17) | Ag1—N1—C3—C2 | 171.36 (17) |
Ag1iii—Ag1—N1—C1 | −17.6 (2) | C1—N2—C4—C5 | 80.9 (3) |
Br1—Ag1—N1—C3 | −17.5 (2) | C2—N2—C4—C5 | −95.7 (3) |
Symmetry codes: (i) −x+1, y, −z−1/2; (ii) x, −y, z+1/2; (iii) −x+1, −y, −z; (iv) x, −y, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | [Ag2Br2(C5H8N2)2] |
Mr | 567.80 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 173 |
a, b, c (Å) | 15.2489 (15), 13.9888 (13), 7.7198 (7) |
β (°) | 109.809 (1) |
V (Å3) | 1549.3 (3) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 7.67 |
Crystal size (mm) | 0.17 × 0.16 × 0.15 |
Data collection | |
Diffractometer | Bruker APEXII CCD |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.355, 0.392 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3840, 1362, 1315 |
Rint | 0.024 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.019, 0.048, 1.05 |
No. of reflections | 1362 |
No. of parameters | 83 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.38, −0.68 |
Computer programs: APEX2 (Bruker, 2006), SAINT (Bruker, 2006), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
Acknowledgements
The authors thank the Quality Engineering of Higher Education in Chemical Specialty Construction from Sichuan Province (Sc-mnu1111; Sc-mnu1115; Mnu-JY1104) for financial support.
References
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Silver and other transition metal N-heterocyclic carbene complexes have played an important role in development of metal-carbene systems for transmetalation reactions. 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. Deprotonation by use of Ag2O has been the most widely used method in the syntheses of N-heterocyclic carbene complexes of silver. The procedure can be accomplished using the reaction of Ag2O with the imidazolium salt in CH2Cl2 solution. The 3-diethylbenzole N-heterocyclic carbene complexes of silver have been successfully synthesized by the reaction of the 1,3-diethylbenzolium salt with Ag2O in CH2Cl2 (Wang & Lin, 1998). In an attempt to prepare similar N-heterocyclic carbene complexes of silver by the reaction of Ag2O with 1,2-dibromocyclohexane and 1-ethylimidazole in DMSO solution, we obtained the title compound, [(C5H8N)2Ag2Br2]n, instead and the synthesis and crystal structure are reported herein. Although the stair polymers of [(C5H5N)4Ag4I4]n (Liu et al., 2003) and 1-allyl-3-methylimidazole carbine silver iodide (Chen & Liu, 2003) have recently been reported, their structural features are different from that of the title complex being formed through triple and quadruple halide bridges with Ag···Ag interactions.
In the title complex the asymmetric unit comprises one monodentate 1-ethylimidazole ligand, an Ag+ cation and a doubly bridging Br- anion, giving a distorted tetrahedral AgNBr3stereochemistry about silver [Ag—N, 2.247 (2) Å; Ag—Br, 2.7372 (4)–2.7752 (3) Å and bond angle range about Ag of 106.78 (6)–113.55 (5)°] (Fig. 1). These Ag—Br bond distances are considerably longer than those found in the [Ag2Br4]2- complex anion [2.518 (2) Å] (Helgesson & Jagner, 1990). The Ag1—N1 bond [2.247 (2) Å] is somewhat shorter than 2.335 Å found in the pyridine silver iodide polymer [(C5H5N)4Ag4I4]n (Liu et al., 2003). The dimeric Ag2Br2 repeating core unit in the title complex is generated through a double Br bridge, giving an Ag···Agi separation of 3.0028(r) Å [for symmetry code (i): -x + 1, y, -z) + 1/2]. The four-membered core ring so formed is very similar to that in the complex anion [Ag4Br8]4-(Helgesson & Jagner, 1991).
The basic coomplex is extended into a one-dimensional step-polymer ribbon structure through centrosymmetric Ag—Br and Br—Ag bonds along the c axial direction (Fig. 2). Within these cyclic Ag2Br2 linkages, the Ag···Agiii separation is 3.0407 (4) Å [for symmetry code (iii): -x + 1, -y + 1, -z].