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Acta Cryst. (2007). E63, m1952-m1953    [ doi:10.1107/S160053680702925X ]

Bis(2,2'-bipyridine-1[kappa]2N,N')-[mu]-bromido-1:2[kappa]2Br-tribromido-2[kappa]3Br-copper(II)mercury(II)

Y.-M. Lee, H.-W. Ryu, S.-N. Choi, J. S. Choi and S. K. Kang

Abstract top

In the title compound, [CuHgBr4(C10H8N2)2], the CuII atom is coordinated by four N atoms of two bidentate 2,2'-bipyridine ligands and one Br atom of a tetrabromidomercurate anion in a distorted trigonal-bipyramidal geometry. The Br atom occupies an equatorial position and bridges the CuII and Hg atoms, with Hg-Br distances of 2.7503 (15) Å, longer by more than 0.15 Å than the terminal Hg-Br bonds. Weak [pi]-[pi] interactions between symmetry-related pyridine rings stabilize the packing; the shortest C-C distance between two parallel aromatic rings of bipy ligands is 3.491 (9) Å.

Comment top

The metal ion assisted exchange reaction strategy for the synthesis of bis and tris-chelated copper(II) complexes with 1,10-phenanthroline (phen) and 2,2'-bipyridine (bipy) has been developed by Majumdar et al., 1998 and Choudhury et al., 1994; for example, the reaction of Cu(phen)Cl2 with 2 moles of Ag(phen)2+ produces a pure tris Cu(phen)32+ cation where two chlorides are transferred from Cu(II) to Ag(I), whereas two phen ligands transferred from Ag(I) to Cu(II). The main driving force for this exchange reaction is presumably the great affinity of Ag(I) toward the halide ion. The Hg(II) assisted exchange reaction was also used for the preparation of a dimeric complex containing (bipy)2CuCl2 units and linear, neutral HgCl2 building blocks; the Hg(II) center in this compound increases structural dimension by accepting chloride ligand from the Cu(II) center in a bridging fashion (Leznoff et al., 2003). Recently, we reported the crystal structure of Tris(1,10-phenanthroline)copper(II) di-µ-iodo-bis(diiodomercurate) dimethyl sulfoxide monohydrate which is produced from the HgII ion assisted exchange reaction between Cu(phen)I2 and Hg(phen)I2 (Oh, et al., 2006).

In this work, we tested the reaction of Cu(bipy)Br2 with Hg(bipy)Br2 with a hope to observe a similar type of tris-chelated CuII complex to be produced since the HgII has stronger affinity toward the halide ion and is softer Lewis acid than CuII. As expected, the transfer of the bipy ligand is observed in this reaction. However, the complete transfer of Br atoms from CuII to HgII does not occur; a bimetallic and bridged complex (bipy)2Cu—Br-HgBr3(I) was produced instead of the formation of an ion pair complex [Cu(bipy)3][HgBr4].

The Cu—Hg distance is 4.196 (2) Å, indicating there is no metal-metal interaction between the two metal centers. The coordination geometry around CuII atom can be described as distorted trigonal bipyramidal with the axial positions occupied by the N12 and N13 atoms of bipy ligands (N12—Cu—N13 177 (4) °) (Fig. 1). The τ value, which is an angular structural parameter as an index of trigonality, is calculated to be 0.83, which means this is closer to trigonal bipyramidal than square pyramidal structure (Addison et al., 1984). One of the equatorial positions is occupied by Br1 atom which then bridges Cu and Hg metals. The Cu—N bond distances range from 1.977 (9) to 2.052 (10) Å which are well within the reported bond distances in Cu—Hg oligomers (1.961 − 2.139 Å) containing bipy ligands (Song et al., 2004). The equatorial Cu—N distances are a little longer than those in the axial Cu—N as usual in trigonal bipyramidal complexes. N24—Cu—Br1 angle (127.8 (3) °) is opened by HgBr3 group from normal angle 120 ° to reduce the steric hindrance. On the other hand, N1—Cu—Br1 angle is closed to 101.3 (3) °. The bridging Hg—Br1 distance in (I) is longer than three terminal Hg—Br bonds by more than 0.15 Å (2.7503 (15) Å for bridging bromide and 2.5512 − 2.6008 Å for terminal bromide). This kind of enlongation has been also observed in [Cu(en)2][HgBr4] complex (Schunk & Thewalt, 2001) and Cu—Hg oligomers, [Cu2(bipy)4HgBr4][Hg2Br6] and [Cu2(bipy)4Hg2Br6][Hg4Br10] (Song et al., 2004).

There is weak slipped π-π interaction between the pyridine ring (N1) and its symmetry related one with an interplanar distance of 3.438\%A and a centroid to centroid distance of 3.699\%A resulting in an offset of 21.6\%. Such π-π interactions between pyridine rings have been known in various CuII complexes containing bipy and phen ligands (Song et al., 2004; Zheng et al., 2002).

Related literature top

For general background see: Majumdar et al. (1998); Leznoff et al. (2003); Choudhury et al. (1994); Oh et al. (2006); Addison et al. (1984). For related structures see: Song et al. (2004); Schunk & Thewalt (2001); Zheng et al. (2002).

Experimental top

The precursor compounds 2,2'-bipyridinedibromomercury(II), Hg(bipy)Br2, and 2,2'-bipyridinedibromocopper(II), Cu(bipy)Br2, were prepared as following; mercuric bromide (1.08 g; 3.00 mmol) was dissolved in 50 ml of ethanol and then, to this solution, 2,2'-bipyridine (0.484 g; 3.10 mmol) was added. The white crystallines of Hg(bipy)Br2 produced were immediately filtered, washed with cold ethanol and dried under vacuum; the yield was 88.9%. Analysis calculated for C10H8N2HgBr2: C 23.25; H 1.56; N 5.42%; found C 23.19; H 1.60; N 5.49%. Cupric bromide (0,670 g; 3.00 mmol) was dissolved in 50 ml of ethanol and then, to this solution, 2,2'-bipyridine (0.484 g; 3.10 mmol) was added. The mixture reacted at room temperature with stirring for 5 hrs. The dark orange precipitates produced were filtered, washed with cold ethanol and then dried under vacuum. The yield was 89.6%. Analysis calculated for C10H8N2CuBr2: C 31.65; H 2.12; N 7.38%; found C 31.49; H 2.23; N 7.31%.

Hg(bipy)Br2 (0.431 g; 1.14 mmol) and Cu(bipy)Br2 (0.578 g; 1.14 mmol) were dissolved in 10 ml of dimethylsulfoxide respectively, and then two solutions were mixed and stirred for 2 hrs. at room temperature. The dark green crystals of the title compound produced were collected, washed with cold ethanol and dimethylsulfoxide successively and then dried under vacuum. Analysis calculated for C20H16N4CuHgBr4: C 27.67; H 1.86; N 3.23%; found C 27.12; H 2.04; N 3.44%.

Refinement top

All H atoms were fixed geometrically and treated as riding with C—H = 0.93 Å with Uiso(H) = 1.2Ueq(C).

Computing details top

Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top
[Figure 1] Fig. 1. Molecular structure of (I), showing the atom-numbering scheme. Ellipsoids are drawn at the 30% probability level. H atoms have been omitted for clarity.
Bis(2,2'-bipyridine-1κ2N,N')-\-m-bromido-1:2κ2Br-tribromido-2κ3Br-\ copper(II)mercury(II) top
Crystal data top
[CuHgBr4(C10H8N2)2]F000 = 1652
Mr = 896.14Dx = 2.487 Mg m−3
Monoclinic, P21/nMo Kα radiation
λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 25 reflections
a = 8.5510 (6) Åθ = 11.3–14.1º
b = 15.522 (4) ŵ = 13.99 mm−1
c = 18.056 (2) ÅT = 295 (2) K
β = 92.784 (8)ºBlock, green
V = 2393.8 (7) Å30.23 × 0.2 × 0.2 mm
Z = 4
Data collection top
Enraf-Nonius CAD-4
diffractometer		θmax = 26º
non–profiled ω/2θ scansθmin = 2.3º
Absorption correction: ψ scan
(North et al., 1968)		h = −10→10
Tmin = 0.050, Tmax = 0.059k = −2→19
6320 measured reflectionsl = −2→22
4705 independent reflections3 standard reflections
2406 reflections with I > 2σ(I) every 400 reflections
Rint = 0.057 intensity decay: none
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.060H-atom parameters constrained
wR(F2) = 0.110  w = 1/[σ2(Fo2) + (0.0352P)2]
where P = (Fo2 + 2Fc2)/3
S = 0.99(Δ/σ)max < 0.001
4705 reflectionsΔρmax = 0.93 e Å−3
271 parametersΔρmin = −1.13 e Å−3
156 restraintsExtinction correction: none
Primary atom site location: structure-invariant direct methods
Crystal data top
[CuHgBr4(C10H8N2)2]V = 2393.8 (7) Å3
Mr = 896.14Z = 4
Monoclinic, P21/nMo Kα
a = 8.5510 (6) ŵ = 13.99 mm−1
b = 15.522 (4) ÅT = 295 (2) K
c = 18.056 (2) Å0.23 × 0.2 × 0.2 mm
β = 92.784 (8)º
Data collection top
Enraf-Nonius CAD-4
diffractometer		2406 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)		Rint = 0.057
Tmin = 0.050, Tmax = 0.0593 standard reflections
6320 measured reflections every 400 reflections
4705 independent reflections intensity decay: none
Refinement top
R[F2 > 2σ(F2)] = 0.060156 restraints
wR(F2) = 0.110H-atom parameters constrained
S = 0.99Δρmax = 0.93 e Å−3
4705 reflectionsΔρmin = −1.13 e Å−3
271 parameters
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
C2−0.0322 (14)0.6419 (8)0.5219 (7)0.040 (3)
H20.04850.68130.53060.048*
C3−0.0552 (13)0.5794 (9)0.5747 (7)0.045 (4)
H30.00870.57630.61780.054*
C4−0.1743 (14)0.5227 (9)0.5618 (7)0.048 (4)
H4−0.19250.48040.59680.057*
C5−0.2686 (13)0.5265 (8)0.4980 (7)0.041 (3)
H5−0.34830.48660.48890.049*
C6−0.2414 (12)0.5917 (8)0.4475 (6)0.032 (3)
C7−0.3341 (12)0.6042 (8)0.3783 (7)0.033 (3)
C8−0.4543 (12)0.5510 (8)0.3537 (7)0.040 (3)
H8−0.47950.50190.38010.049*
C9−0.5376 (13)0.5729 (9)0.2877 (9)0.055 (4)
H9−0.62220.53920.27110.066*
C10−0.4967 (12)0.6420 (9)0.2481 (7)0.047 (4)
H10−0.55100.65570.20370.056*
C11−0.3745 (13)0.6917 (8)0.2739 (7)0.038 (3)
H11−0.34540.73930.24640.046*
C140.2304 (13)0.7503 (8)0.4252 (7)0.048 (3)
H140.23510.69090.41880.057*
C150.3632 (14)0.7934 (10)0.4513 (7)0.052 (4)
H150.45440.76370.46520.062*
C160.3563 (14)0.8814 (10)0.4561 (7)0.052 (4)
H160.44520.91170.47250.062*
C170.2216 (13)0.9257 (8)0.4375 (6)0.040 (3)
H170.21740.98550.44100.048*
C180.0911 (13)0.8779 (8)0.4130 (7)0.035 (3)
C19−0.0611 (13)0.9174 (8)0.3890 (7)0.035 (3)
C20−0.0916 (14)1.0046 (8)0.3924 (7)0.047 (4)
H20−0.01461.04310.40930.057*
C21−0.2390 (16)1.0331 (9)0.3702 (7)0.053 (4)
H21−0.26231.09150.37290.064*
C22−0.3525 (15)0.9762 (9)0.3440 (8)0.060 (4)
H22−0.45110.99550.32750.072*
C23−0.3154 (14)0.8895 (9)0.3432 (7)0.047 (4)
H23−0.39220.85010.32780.057*
Br10.04425 (13)0.64128 (9)0.27693 (8)0.0433 (4)
Br20.23547 (15)0.67094 (9)0.06716 (8)0.0511 (4)
Br30.28973 (14)0.86587 (9)0.24357 (8)0.0483 (4)
Br4−0.15949 (15)0.82029 (10)0.12790 (9)0.0634 (5)
Cu1−0.10161 (15)0.73448 (10)0.37395 (9)0.0432 (4)
Hg10.11158 (6)0.76093 (3)0.17075 (3)0.04758 (19)
N1−0.1207 (10)0.6482 (6)0.4588 (5)0.032 (2)
N12−0.2952 (10)0.6737 (7)0.3379 (5)0.036 (3)
N130.0957 (10)0.7909 (7)0.4088 (5)0.041 (3)
N24−0.1725 (11)0.8604 (6)0.3640 (5)0.036 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C20.053 (7)0.035 (8)0.031 (8)−0.001 (7)−0.013 (6)0.004 (7)
C30.045 (8)0.059 (9)0.032 (8)0.014 (7)0.008 (7)0.001 (8)
C40.048 (8)0.048 (9)0.048 (9)−0.002 (7)0.013 (7)0.013 (8)
C50.046 (8)0.028 (7)0.050 (9)0.003 (6)0.008 (7)0.003 (7)
C60.034 (6)0.036 (7)0.026 (7)0.007 (6)0.009 (6)−0.005 (6)
C70.018 (6)0.044 (8)0.036 (8)0.005 (6)−0.001 (6)−0.005 (7)
C80.027 (6)0.040 (8)0.055 (9)−0.006 (6)0.008 (7)−0.012 (8)
C90.021 (6)0.053 (10)0.090 (12)−0.004 (7)−0.004 (8)−0.026 (9)
C100.024 (6)0.069 (10)0.045 (9)−0.008 (7)−0.015 (6)−0.005 (8)
C110.037 (7)0.037 (8)0.041 (8)0.005 (6)0.002 (6)0.019 (7)
C140.049 (7)0.035 (8)0.058 (8)0.000 (7)−0.013 (7)0.001 (8)
C150.029 (7)0.072 (11)0.054 (9)−0.012 (7)−0.007 (7)−0.007 (9)
C160.032 (7)0.081 (11)0.042 (8)−0.005 (8)−0.007 (7)−0.010 (9)
C170.058 (8)0.031 (8)0.033 (8)−0.012 (7)0.011 (7)−0.005 (7)
C180.045 (7)0.028 (7)0.033 (7)−0.012 (6)0.002 (6)−0.003 (7)
C190.046 (7)0.022 (7)0.037 (8)−0.014 (6)0.009 (6)0.012 (7)
C200.048 (8)0.041 (9)0.054 (9)0.000 (7)0.009 (7)0.000 (8)
C210.075 (9)0.034 (8)0.051 (9)−0.004 (8)0.003 (8)0.002 (8)
C220.045 (8)0.060 (10)0.075 (11)0.020 (8)0.001 (8)0.016 (9)
C230.049 (8)0.047 (9)0.045 (9)0.008 (7)−0.007 (7)0.007 (8)
Br10.0431 (7)0.0393 (8)0.0472 (9)−0.0010 (6)−0.0027 (7)0.0004 (7)
Br20.0544 (8)0.0526 (9)0.0454 (9)0.0121 (7)−0.0085 (7)−0.0070 (8)
Br30.0541 (8)0.0498 (9)0.0405 (8)−0.0093 (7)−0.0039 (7)−0.0001 (8)
Br40.0496 (8)0.0680 (11)0.0706 (11)0.0113 (8)−0.0187 (8)0.0091 (10)
Cu10.0354 (8)0.0371 (10)0.0552 (11)−0.0115 (8)−0.0170 (7)0.0115 (9)
Hg10.0466 (3)0.0477 (4)0.0472 (3)0.0045 (3)−0.0103 (2)−0.0044 (3)
N10.036 (5)0.024 (6)0.035 (6)−0.001 (5)−0.002 (5)−0.006 (5)
N120.027 (5)0.044 (7)0.035 (6)0.004 (5)−0.007 (5)0.007 (6)
N130.029 (5)0.052 (7)0.041 (7)−0.012 (5)−0.009 (5)0.007 (6)
N240.040 (6)0.029 (6)0.039 (6)0.001 (5)0.002 (5)0.008 (5)
Geometric parameters (Å, °) top
C2—N11.341 (13)C16—C171.370 (16)
C2—C31.380 (16)C16—H160.9300
C2—H20.9300C17—C181.394 (14)
C3—C41.357 (16)C17—H170.9300
C3—H30.9300C18—N131.353 (14)
C4—C51.375 (16)C18—C191.484 (15)
C4—H40.9300C19—N241.361 (13)
C5—C61.388 (16)C19—C201.380 (16)
C5—H50.9300C20—C211.377 (16)
C6—N11.363 (13)C20—H200.9300
C6—C71.460 (15)C21—C221.379 (17)
C7—N121.353 (14)C21—H210.9300
C7—C81.375 (15)C22—C231.383 (17)
C8—C91.399 (17)C22—H220.9300
C8—H80.9300C23—N241.339 (13)
C9—C101.346 (17)C23—H230.9300
C9—H90.9300Br1—Cu12.632 (2)
C10—C111.363 (15)Br1—Hg12.7502 (15)
C10—H100.9300Br2—Hg12.6008 (15)
C11—N121.340 (13)Br3—Hg12.5512 (14)
C11—H110.9300Br4—Hg12.5780 (14)
C14—N131.334 (13)Cu1—N131.977 (9)
C14—C151.382 (15)Cu1—N121.987 (9)
C14—H140.9300Cu1—N12.047 (10)
C15—C161.370 (18)Cu1—N242.052 (10)
C15—H150.9300
N1—C2—C3123.0 (12)N24—C19—C20121.4 (12)
N1—C2—H2118.5N24—C19—C18114.7 (10)
C3—C2—H2118.5C20—C19—C18123.9 (11)
C4—C3—C2117.8 (12)C21—C20—C19118.4 (13)
C4—C3—H3121.1C21—C20—H20120.8
C2—C3—H3121.1C19—C20—H20120.8
C3—C4—C5121.4 (13)C20—C21—C22120.8 (13)
C3—C4—H4119.3C20—C21—H21119.6
C5—C4—H4119.3C22—C21—H21119.6
C4—C5—C6118.1 (12)C21—C22—C23118.0 (13)
C4—C5—H5120.9C21—C22—H22121.0
C6—C5—H5120.9C23—C22—H22121.0
N1—C6—C5121.4 (11)N24—C23—C22122.1 (13)
N1—C6—C7114.7 (11)N24—C23—H23118.9
C5—C6—C7123.9 (12)C22—C23—H23118.9
N12—C7—C8120.3 (11)Cu1—Br1—Hg1102.40 (6)
N12—C7—C6115.5 (10)N13—Cu1—N12177.8 (4)
C8—C7—C6124.2 (12)N13—Cu1—N198.6 (4)
C7—C8—C9118.1 (13)N12—Cu1—N180.8 (4)
C7—C8—H8121.0N13—Cu1—N2481.3 (4)
C9—C8—H8121.0N12—Cu1—N24100.7 (4)
C10—C9—C8120.8 (12)N1—Cu1—N24130.9 (4)
C10—C9—H9119.6N13—Cu1—Br191.8 (3)
C8—C9—H9119.6N12—Cu1—Br186.3 (3)
C9—C10—C11119.0 (12)N1—Cu1—Br1101.3 (3)
C9—C10—H10120.5N24—Cu1—Br1127.8 (3)
C11—C10—H10120.5Br3—Hg1—Br4115.60 (5)
N12—C11—C10121.6 (12)Br3—Hg1—Br2117.37 (5)
N12—C11—H11119.2Br4—Hg1—Br2111.58 (5)
C10—C11—H11119.2Br3—Hg1—Br1102.23 (5)
N13—C14—C15122.2 (13)Br4—Hg1—Br1103.59 (5)
N13—C14—H14118.9Br2—Hg1—Br1104.19 (5)
C15—C14—H14118.9C2—N1—C6118.1 (11)
C16—C15—C14117.9 (13)C2—N1—Cu1128.5 (8)
C16—C15—H15121.1C6—N1—Cu1113.4 (8)
C14—C15—H15121.1C11—N12—C7120.2 (10)
C17—C16—C15121.6 (13)C11—N12—Cu1124.2 (9)
C17—C16—H16119.2C7—N12—Cu1115.1 (7)
C15—C16—H16119.2C14—N13—C18119.1 (11)
C16—C17—C18117.4 (12)C14—N13—Cu1125.1 (9)
C16—C17—H17121.3C18—N13—Cu1115.7 (8)
C18—C17—H17121.3C23—N24—C19119.2 (11)
N13—C18—C17121.6 (12)C23—N24—Cu1127.4 (9)
N13—C18—C19115.0 (10)C19—N24—Cu1113.0 (8)
C17—C18—C19123.3 (11)
Table 1
Selected geometric parameters (Å) top
Br1—Cu12.632 (2)Br3—Hg12.5512 (14)
Br1—Hg12.7502 (15)Br4—Hg12.5780 (14)
Br2—Hg12.6008 (15)
Acknowledgements top

This work was supported by a grant from the Ministry of Commerce, Industry and Energy, and the Korea Industrial Technology Foundation. X-ray data were collected at the Center for Research Facilities in Chungnam National University.

references
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