Acta Cryst. (2007). E63, m1569 [ doi:10.1107/S1600536807021186 ]
![[mu]](/logos/entities/mu_rmgif.gif)
2-bromido-bis[dibromoplumbate(II)]]-di-2-bromido]]In the title compound, {(C10H12N2)2[Pb2Br8]}n, the asymmetric unit consists of half a cation and one-quarter of a doubly-bridged dinuclear anionic unit. The planar cations lies on a twofold axis that runs lengthwise through both rings. The Pb and one Br atoms are located on twofold axes, whereas the second Br atom is located on a mirror plane and the third lies on a general position. The polymeric anion forms an infinite ladder structure running along the c axis with rungs consisting of Pb and bridging Br atoms, with two octahedra sharing edges as the rungs of the ladder and sharing vertices as the rails. There are N-H
Br hydrogen-bonding interactions, ca 3.21 Å, linking the PbBr ladders to the cations.
A solution of PbCl2 (1.0 mmol), in absolute ethanol (10 ml), was added to a stirred hot solution of 2,3-dimethylquinoxaline (1 mmol) in absolute ethanol (10 ml) containing 60% HBr (3 ml) and liquid Br2 (2 ml). After heating to reflux for ca 3 h, the mixture was filtered and the filtrate allowed to stand undisturbed at room temperature. Complex (I) crystallized out over 2 days as red blocks. Crystals were filtered off, washed with diethyl ether and dried under vacuum.
All H atoms were initially located in a difference Fourier map and were subsequently refined using a riding model, with C—H distances of 0.96 Å and Uiso(H) = 1.5eq(C) for methyl H atoms; C—H = 0.96 Å and Uiso(H) = 1.2eq(C) for aromatic H atoms, and N—H = 0.86 Å and Uiso(H) = 1.2eq(N).
Data collection: CrystalClear (Rigaku, 2000); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1999); software used to prepare material for publication: SHELXTL.
![[Figure 1]](./dn2167fig1thm.gif)
| Fig. 1. Displacement ellpisoid (30%) plot of (I), showing the atom-numbering scheme. The complete coordination about Pb1 and cation have been included. [Symmetry codes: (i) 1 - x, -y, 1 - z; (ii) x, y, 1 + z; (iii) 1 - x, - y, 1 - z; (iv) x, 1 - y, z; (v) 1 - x, 1 - y, 1 - z; (vi) 2 - x, y, -z]. |
![[Figure 2]](./dn2167fig2thm.gif)
| Fig. 2. View of unit cell approximately down a axis showing H-bonding between Br1 and N3. |
| (C10H12N2)2[Pb2Br8] | F(000) = 1232 |
| Mr = 1374.04 | Dx = 2.918 Mg m−3 |
| Monoclinic, C2/m | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: -C 2y | Cell parameters from 3034 reflections |
| a = 9.4180 (19) Å | θ = 1.5–27.9° |
| b = 28.141 (6) Å | µ = 20.99 mm−1 |
| c = 6.0290 (12) Å | T = 295 K |
| β = 101.83 (3)° | Block, red |
| V = 1563.9 (6) Å3 | 0.20 × 0.15 × 0.10 mm |
| Z = 2 |
| Rigaku Mercury CCD diffractometer | 1419 independent reflections |
| Radiation source: fine-focus sealed tube | 875 reflections with I > 2σ(I) |
| graphite | Rint = 0.092 |
| Detector resolution: 14.6306 pixels mm-1 | θmax = 25.2°, θmin = 3.1° |
| dtintegrate.ref scans | h = −11→11 |
| Absorption correction: numerical (SHAPE Tracing Software; Rigaku, 2000) | k = −33→33 |
| Tmin = 0.102, Tmax = 0.228 | l = −7→6 |
| 7780 measured reflections |
| 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)] = 0.054 | Hydrogen site location: inferred from neighbouring sites |
| wR(F2) = 0.123 | H-atom parameters constrained |
| S = 0.73 | w = 1/[σ2(Fo2) + (0.0005P)2] where P = (Fo2 + 2Fc2)/3 |
| 1419 reflections | (Δ/σ)max < 0.001 |
| 81 parameters | Δρmax = 2.30 e Å−3 |
| 0 restraints | Δρmin = −1.46 e Å−3 |
| (C10H12N2)2[Pb2Br8] | V = 1563.9 (6) Å3 |
| Mr = 1374.04 | Z = 2 |
| Monoclinic, C2/m | Mo Kα radiation |
| a = 9.4180 (19) Å | µ = 20.99 mm−1 |
| b = 28.141 (6) Å | T = 295 K |
| c = 6.0290 (12) Å | 0.20 × 0.15 × 0.10 mm |
| β = 101.83 (3)° |
| Rigaku Mercury CCD diffractometer | 1419 independent reflections |
| Absorption correction: numerical (SHAPE Tracing Software; Rigaku, 2000) | 875 reflections with I > 2σ(I) |
| Tmin = 0.102, Tmax = 0.228 | Rint = 0.092 |
| 7780 measured reflections | θmax = 25.2° |
| R[F2 > 2σ(F2)] = 0.054 | H-atom parameters constrained |
| wR(F2) = 0.123 | Δρmax = 2.30 e Å−3 |
| S = 0.73 | Δρmin = −1.46 e Å−3 |
| 1419 reflections | Absolute structure: ? |
| 81 parameters | Flack parameter: ? |
| 0 restraints | Rogers parameter: ? |
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 | ||
| Pb1 | 0.5000 | 0.57831 (3) | 0.5000 | 0.0288 (3) | |
| Br1 | 0.73667 (15) | 0.65358 (6) | 0.5497 (2) | 0.0386 (5) | |
| Br2 | 0.5000 | 0.58691 (8) | 0.0000 | 0.0475 (7) | |
| Br3 | 0.2733 (2) | 0.5000 | 0.4132 (4) | 0.0358 (6) | |
| C1 | 0.9022 (16) | 0.5680 (5) | 0.167 (3) | 0.038 (4) | |
| H1A | 0.9785 | 0.5551 | 0.2817 | 0.057* | |
| H1B | 0.8762 | 0.5455 | 0.0461 | 0.057* | |
| H1C | 0.8192 | 0.5746 | 0.2316 | 0.057* | |
| C2 | 0.9527 (13) | 0.6126 (5) | 0.078 (2) | 0.027 (3) | |
| C4 | 0.9533 (12) | 0.6952 (5) | 0.076 (2) | 0.027 (3) | |
| C5 | 0.9127 (14) | 0.7363 (5) | 0.169 (2) | 0.034 (4) | |
| H5 | 0.8598 | 0.7362 | 0.2829 | 0.040* | |
| C6 | 0.9558 (15) | 0.7782 (6) | 0.080 (2) | 0.045 (4) | |
| H6 | 0.9249 | 0.8071 | 0.1283 | 0.054* | |
| N3 | 0.9122 (11) | 0.6516 (4) | 0.1469 (17) | 0.022 (2) | |
| H3A | 0.8561 | 0.6510 | 0.2429 | 0.026* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Pb1 | 0.0225 (4) | 0.0360 (6) | 0.0290 (5) | 0.000 | 0.0080 (3) | 0.000 |
| Br1 | 0.0285 (8) | 0.0535 (12) | 0.0373 (9) | −0.0104 (7) | 0.0145 (7) | −0.0096 (7) |
| Br2 | 0.0521 (15) | 0.0652 (18) | 0.0253 (13) | 0.000 | 0.0083 (11) | 0.000 |
| Br3 | 0.0244 (11) | 0.0332 (14) | 0.0494 (14) | 0.000 | 0.0066 (9) | 0.000 |
| C1 | 0.042 (9) | 0.042 (10) | 0.036 (9) | 0.002 (8) | 0.021 (8) | 0.004 (8) |
| C2 | 0.023 (7) | 0.033 (9) | 0.024 (8) | −0.001 (7) | 0.001 (6) | 0.001 (7) |
| C4 | 0.015 (6) | 0.040 (10) | 0.024 (8) | 0.003 (7) | 0.003 (5) | 0.002 (7) |
| C5 | 0.037 (8) | 0.036 (10) | 0.032 (9) | −0.002 (8) | 0.016 (7) | −0.003 (8) |
| C6 | 0.045 (10) | 0.055 (12) | 0.037 (10) | 0.011 (8) | 0.013 (7) | −0.012 (8) |
| N3 | 0.023 (6) | 0.018 (7) | 0.025 (6) | 0.000 (5) | 0.010 (5) | −0.003 (5) |
| Pb1—Br2 | 3.0242 (6) | C4—C5 | 1.372 (18) |
| Pb1—Br3 | 3.0380 (14) | C4—N3 | 1.381 (16) |
| Pb1—Br1 | 3.0448 (16) | C4—C4i | 1.40 (2) |
| C1—C2 | 1.481 (18) | C5—C6 | 1.389 (19) |
| C1—H1A | 0.9600 | C5—H5 | 0.9300 |
| C1—H1B | 0.9600 | C6—C6i | 1.40 (3) |
| C1—H1C | 0.9600 | C6—H6 | 0.9300 |
| C2—N3 | 1.262 (15) | N3—H3A | 0.8600 |
| C2—C2i | 1.42 (2) | ||
| Br2ii—Pb1—Br2 | 170.81 (9) | H1B—C1—H1C | 109.5 |
| Br2ii—Pb1—Br3 | 94.95 (6) | N3—C2—C2i | 119.4 (8) |
| Br2—Pb1—Br3 | 91.71 (6) | N3—C2—C1 | 118.4 (12) |
| Br3—Pb1—Br3iii | 87.00 (6) | C2i—C2—C1 | 122.2 (8) |
| Br2ii—Pb1—Br1 | 89.76 (5) | C5—C4—N3 | 120.4 (12) |
| Br2—Pb1—Br1 | 83.85 (5) | N3—C4—C4i | 117.2 (7) |
| Br3—Pb1—Br1 | 174.84 (4) | C4—C5—C6 | 115.6 (13) |
| Br3iii—Pb1—Br1 | 90.76 (4) | C4—C5—H5 | 122.2 |
| Br1—Pb1—Br1iv | 91.84 (6) | C6—C5—H5 | 122.2 |
| Pb1—Br3—Pb1iii | 93.00 (6) | C5—C6—C6i | 121.9 (8) |
| C2—C1—H1A | 109.5 | C5—C6—H6 | 119.1 |
| C2—C1—H1B | 109.5 | C2—N3—C4 | 123.3 (12) |
| H1A—C1—H1B | 109.5 | C2—N3—H3A | 118.3 |
| C2—C1—H1C | 109.5 | C4—N3—H3A | 118.3 |
| H1A—C1—H1C | 109.5 |
| Symmetry codes: (i) −x+2, y, −z; (ii) x, y, z+1; (iii) −x+1, −y+1, −z+1; (iv) −x+1, y, −z+1. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| N3—H3A···Br1 | 0.86 | 2.35 | 3.206 (10) | 171 |
| C1—H1C···Br2 | 0.96 | 3.06 | 3.752 (14) | 130 |
| D—H···A | D—H | H···A | D···A | D—H···A |
| N3—H3A···Br1 | 0.86 | 2.35 | 3.206 (10) | 171 |
| C1—H1C···Br2 | 0.96 | 3.06 | 3.752 (14) | 130 |
This research was supported by Al al-Bayt University and Al-Balqa'a Applied University.
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Research in the field of organic inorganic hybrid compounds is of great interest. This is because of the their special magnetic, electronic and optoelectronic properties (Cui et al., 2000; Lacroix et al.,1994; Chakravarthy & Guloy, 1997). Haloplumbates, have demonstrated a structural diversity in lead-halide based organic inorganic hybrids (Billing & Lemerrer, 2005) in particular, in terms of the nets formed by the inorganic components, which show many distinct topologies. Examples are layers of corner sharing octahedra, linear chains of face sharing octahedra as well as a number of mixed intermediates (Billing & Lemerrer, 2005). In the crystal structure of the title complex, (I). The use of 2,3-dimethylquinoxaline (henceforth dmqxH2) and its protonation were expected to create many important centers of interaction with the bromo-lead anion, e.g. NH···Br, CH···Br and possibly Br···aryl and aryl···aryl interactions.
In the title compound, (I), {C10H12Br4N2Pb}n, the asymmetric unit consists of half of the repeated extended structure of both cation and anion. The planar cations [C10H12N2]2+ with both nitrogen atoms protonated, lies on a 2-fold axis that runs lengthwise between the two halves (Fig. 1). The dinuclear unit [Pb2Br10]6- consists of two distorted octahedra bridged by Br3 and its symmetry related Br3i [Symmetry code: (iii) -x + 1, -y, -z + 1). These dinuclear units are further interconnected through bridging Br2 to form a polymeric chain structure developping parallel to the c axis (Fig. 2). This anion chain demonstrates a novel structural arrangement in metal halide extended anion networking.
The Pb—Br distances are similar, 3.0242 (6)–3.0448 (16) Å and fall within the range of Pb—Br distances reported previously for compounds containing lead-bromides (Reynolds et al., 2003; Cui et al., 2000; Klapotke et al., 1999). The bond angles for linear Br—Pb—Br are in the range 170.87 (9)– 174.84 (4)°, while those for perpendicular Br—Pb—Br are in the range 83.85 (5)–94.95 (6)°. In the dmqxH2 cation, the bond distances and angles are the same as those reported previously, within experimental error (Willett & Twamley, 2001).
The extra supramolecularity in the structure is represented by H-bonding (Table 1) leading to a layer arrangement in ac plane.