metal-organic compounds
Poly[μ3-hydroxido-μ-(pyridine-2,4,6-tricarboxylato)-dilead(II)]
aCollege of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000, People's Republic of China
*Correspondence e-mail: vzyh@hotmail.com
The 2(C8H2NO6)(OH)]n, contains two crystallographically independent PbII ions, one pyridine-2,4,6-tricarboxylate (ptc) trianion and one hydroxide anion. One of the PbII atoms is coordinated by one pyridine N and four carboxylate O atoms from the ptc trianion and a hydroxide O atom in a distorted octahedral geometry. The other PbII atom is five-coordinated by three carboxylate O atoms and two hydroxide O atoms in a distorted tetragonal–pyramidal geometry. Four neighbouring PbII atoms are bridged through two μ3-hydroxide ligands, forming the centrosymmetric Pb4(OH)2 core. The three-dimensional structure is further achieved through bridging carboxylate groups. There are also O—H⋯O hydrogen bonds between the hydroxide ligand and the carboxylate group.
of the title coordination polymer, [PbRelated literature
For general background to pyridine-2,4,6-tricarboxylic acid complexes and their derivatives, see: Das et al. (2009); Ding et al. (2009); Ghosh et al. (2006); O'Keeffe et al. (2008); Shi et al. (2010); Xu et al. (2010); Yigit et al. (2005); Zhang et al. (2009); Zhao et al. (2009). For our previous work on metal complexes, see: Zhou et al. (2007); Wu et al. (2007).
Experimental
Crystal data
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Refinement
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Data collection: SMART (Bruker, 1997); cell SAINT (Bruker, 1997); 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/S1600536810049275/is2628sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810049275/is2628Isup2.hkl
A solution of pyridine-2,4,6-tricarboxylic acid (208 mg, 1.0 mmol) and KOH (224 mg, 4.0 mmol) in anhydrous methanol (10 ml) was added slowly to a solution of Pb(CH3COO)2 (672 mg, 2.0 mmol) in anhydrous methanol (10 ml). The resulting mixture was stirred for about 1 h at room temperature, sealed in a 25 ml Teflon-lined stainless steel autoclave and heated at 393 K for five days under autogenous pressure. The reaction system was cooled gradually to room temperature and colorless block-shaped crystals suitable for X-ray diffraction were collected.
H atoms were positioned geometrically (C—H = 0.93 Å and O—H = 0.83 Å) and included in the
in the riding-model approximation, with Uiso(H) =1.2Ueq(C) and 1.5Ueq(O). The highest peak and the deepest hole in the difference Fourier map are located 0.78 and 0.97 Å, respectively, from atom Pb2.Until recently, the construction of coordination polymers has been an active area because of the properties of catalysis and molecular magnetism (Shi et al., 2010; O'Keeffe et al., 2008; Zhang et al., 2009). Pyridine-2,4,6-tricarboxylic acid (H3ptc) is an effective ligand for coordinating to metal cations to generate diverse interesting coordination polymer architectures (Zhao et al., 2009; Yigit et al., 2005). However, the coordination polymers containing H3ptc ligands are seldom high-dimensional complexes (Das et al., 2009; Ghosh et al., 2006). Because of the relatively large ionic radius of the Pb(II) cation, the lead complex should form some interesting frameworks (Ding et al., 2009). Herein, we report the lead polymeric complex [Pb2(C8H2NO6)(OH)]n, (I), which is an unique homometallic three-dimensional framework compound.
The π–π stacking interactions with offset face-to-face mode [centroid-to-centroid distance 3.5486 (4) Å] (Fig. 2). Furthermore, the two-dimensional structure are linked through Pb1—O5i and Pb1ii—O5v bonds to generate a three-dimensional stereo structure. There are some hydrogen bonds O—H···O in (I) between the hydroxide H atom and carboxylic O4iii with an O···O distance of 2.884 (8) Å (Table 2). Hydrogen bonds are helpful to enhance the stability of the molecular structure. A remarkable feature of this structure is the arrangement of [Pb12Pb22(OH)2]6+ units with infinite helices extending along the crystallographic b axis with intervening ptc ligands (Fig. 3). The helical structure is a comprehensive result of metal-ligand interactions and the π–π stacking interactions of pyridine rings of ptc ligands.
of (I) consists of two Pb(II) cations, one ptc trianion and one coordinated hydroxyl anion. As shown in Fig. 1, atom Pb1 is six-coordinated by two carboxylate O and one N atoms from a ligand ptc and one hydroxide anion O in a distorted square-planar geometry, and two carboxylate O atoms from the other two ligand ptc in the axial positions (Table 1). The PbNO5 octahedron is distorted, with the O—Pb1—O(N) bond angles ranging from 64.0 (2) to 147.70 (19)°. Whereas atom Pb2 is five-coordinated by three carboxylate O atoms from two ptc and two µ3-hydroxide O atoms in a distorted tetragonal pyramid geometry. The Pb—O and Pb—N distances (Table 1) are comparable with those observed for [Pb2(bdc)2(piphen)2]n (bdc is benzene-1,4-dicarboxylate and piphen is 6-(4-pyridyl)-5H- imidazolo[4,5-f][1,10]phenanthroline; Xu et al., 2010). Each ptc molecule employs its three carboxylate groups and one N atom to chelate and bridge six Pb(II) cations. Two neighbouring Pb2 atoms are bis-bridged by two hydroxide O atoms (O7 and O7ii) to form a centrosymmetric [Pb2(OH)2]2+ core which is linked by two Pb1 atoms through Pb1—O7ii and Pb1ii—O7 bonds to form [Pb12Pb22(OH)2]6+ unit (Fig. 2). The bonds of Pb2—O4iv, Pb2—O1, Pb2ii—O1ii and Pb2ii—O4iii bonds surrounding the [Pb2(OH)2]2+ unit are contributed to forming a two-dimensional structure which is further tightened by the atoms of Pb1i, Pb1iii, Pb1iv, Pb1v, Pb1vi and Pb1vii with joining neighbouring ptc ligands. Also, the two adjacent pyridine rings of ptc ligands are involved inFor general background to pyridine-2,4,6-tricarboxylic acid complexes and their derivatives, see: Das et al. (2009); Ding et al. (2009); Ghosh et al. (2006); O'Keeffe et al. (2008); Shi et al. (2010); Xu et al. (2010); Yigit et al. (2005); Zhang et al. (2009); Zhao et al. (2009). For our previous work on metal complexes, see: Zhou et al. (2007); Wu et al. (2007).
Data collection: SMART (Bruker, 1997); cell
SAINT (Bruker, 1997); data reduction: SAINT (Bruker, 1997); 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).Fig. 1. A view of the local coordination of the PbII atoms in the title compound, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are shown as small spheres of arbitrary radii. [Symmetry codes: (i) x, -y + 3/2, z - 1/2; (ii) -x, -y + 2, -z; (iii) -x + 1, -y + 2, -z + 1; (iv) -x + 1, -y + 2, -z; (v) x - 1, y, z - 1.] | |
Fig. 2. A view of the [Pb12Pb22(OH)2]6+ unit, surrounded by four Pb1 atoms. [Symmetry codes: (i) x, -y + 3/2, z - 1/2; (ii) -x, -y + 2, -z; (iii) -x + 1, -y + 2, -z + 1; (iv) -x + 1, -y + 2, -z; (v) x - 1, y, z - 1.] | |
Fig. 3. A packing diagram of the title compound viewed along the b axis. |
[Pb2(C8H2NO6)(OH)] | F(000) = 1112 |
Mr = 639.49 | Dx = 3.918 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 5542 reflections |
a = 7.5391 (9) Å | θ = 2.5–28.2° |
b = 14.1845 (17) Å | µ = 31.05 mm−1 |
c = 10.3084 (12) Å | T = 291 K |
β = 100.468 (1)° | Block, white |
V = 1084.0 (2) Å3 | 0.38 × 0.26 × 0.25 mm |
Z = 4 |
Bruker SMART APEX CCD area-detector diffractometer | 2014 independent reflections |
Radiation source: fine-focus sealed tube | 1903 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.036 |
φ and ω scans | θmax = 25.5°, θmin = 2.5° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −9→9 |
Tmin = 0.030, Tmax = 0.047 | k = −17→17 |
7870 measured reflections | l = −12→12 |
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)] = 0.028 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.069 | H-atom parameters constrained |
S = 1.08 | w = 1/[σ2(Fo2) + (0.0382P)2 + 7.726P] where P = (Fo2 + 2Fc2)/3 |
2014 reflections | (Δ/σ)max = 0.001 |
157 parameters | Δρmax = 1.64 e Å−3 |
0 restraints | Δρmin = −2.07 e Å−3 |
[Pb2(C8H2NO6)(OH)] | V = 1084.0 (2) Å3 |
Mr = 639.49 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 7.5391 (9) Å | µ = 31.05 mm−1 |
b = 14.1845 (17) Å | T = 291 K |
c = 10.3084 (12) Å | 0.38 × 0.26 × 0.25 mm |
β = 100.468 (1)° |
Bruker SMART APEX CCD area-detector diffractometer | 2014 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1903 reflections with I > 2σ(I) |
Tmin = 0.030, Tmax = 0.047 | Rint = 0.036 |
7870 measured reflections |
R[F2 > 2σ(F2)] = 0.028 | 0 restraints |
wR(F2) = 0.069 | H-atom parameters constrained |
S = 1.08 | Δρmax = 1.64 e Å−3 |
2014 reflections | Δρmin = −2.07 e Å−3 |
157 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 | ||
Pb1 | 0.06507 (4) | 0.84421 (2) | 0.28447 (3) | 0.01366 (11) | |
Pb2 | 0.18306 (4) | 0.93099 (2) | −0.06649 (3) | 0.01411 (11) | |
O1 | 0.2977 (9) | 0.9297 (5) | 0.1872 (6) | 0.0289 (11) | |
O2 | 0.5925 (8) | 0.9461 (5) | 0.1816 (6) | 0.0289 (11) | |
O3 | 0.9877 (8) | 0.9721 (4) | 0.6667 (6) | 0.0225 (13) | |
O4 | 0.9167 (8) | 0.8519 (4) | 0.7875 (6) | 0.0250 (14) | |
O5 | 0.2690 (8) | 0.7768 (4) | 0.7342 (6) | 0.0213 (12) | |
O6 | 0.1106 (8) | 0.7676 (4) | 0.5298 (5) | 0.0229 (13) | |
O7 | 0.0597 (7) | 1.0796 (4) | −0.0536 (5) | 0.0152 (11) | |
H7 | 0.1117 | 1.1285 | −0.0232 | 0.023* | |
N1 | 0.3717 (8) | 0.8650 (4) | 0.4344 (6) | 0.0105 (12) | |
C1 | 0.5100 (10) | 0.9033 (5) | 0.3862 (7) | 0.0112 (14) | |
C2 | 0.6798 (11) | 0.9170 (5) | 0.4616 (8) | 0.0162 (16) | |
H2 | 0.7720 | 0.9438 | 0.4249 | 0.019* | |
C3 | 0.7094 (10) | 0.8896 (5) | 0.5943 (8) | 0.0140 (15) | |
C4 | 0.5682 (11) | 0.8484 (5) | 0.6457 (8) | 0.0175 (17) | |
H4 | 0.5847 | 0.8288 | 0.7331 | 0.021* | |
C5 | 0.4032 (10) | 0.8379 (5) | 0.5626 (8) | 0.0116 (15) | |
C6 | 0.4651 (11) | 0.9281 (5) | 0.2410 (8) | 0.0150 (16) | |
C7 | 0.8872 (11) | 0.9068 (6) | 0.6901 (8) | 0.0163 (16) | |
C8 | 0.2459 (11) | 0.7909 (5) | 0.6105 (7) | 0.0147 (16) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Pb1 | 0.01119 (17) | 0.01504 (17) | 0.01652 (18) | −0.00022 (11) | 0.00723 (12) | 0.00207 (10) |
Pb2 | 0.01304 (18) | 0.01647 (18) | 0.01407 (17) | 0.00281 (11) | 0.00580 (12) | 0.00070 (10) |
O1 | 0.018 (2) | 0.048 (3) | 0.021 (2) | −0.010 (2) | 0.0067 (19) | 0.010 (2) |
O2 | 0.018 (2) | 0.048 (3) | 0.021 (2) | −0.010 (2) | 0.0067 (19) | 0.010 (2) |
O3 | 0.013 (3) | 0.022 (3) | 0.032 (3) | −0.007 (3) | 0.004 (3) | −0.010 (3) |
O4 | 0.019 (3) | 0.037 (4) | 0.019 (3) | 0.003 (3) | 0.002 (2) | 0.002 (3) |
O5 | 0.023 (3) | 0.025 (3) | 0.018 (3) | −0.003 (3) | 0.010 (2) | 0.003 (2) |
O6 | 0.021 (3) | 0.030 (3) | 0.019 (3) | −0.017 (3) | 0.006 (3) | −0.002 (2) |
O7 | 0.014 (3) | 0.013 (3) | 0.021 (3) | −0.002 (2) | 0.008 (2) | −0.001 (2) |
N1 | 0.010 (3) | 0.008 (3) | 0.016 (3) | −0.002 (2) | 0.006 (3) | 0.001 (2) |
C1 | 0.012 (4) | 0.009 (3) | 0.014 (4) | −0.001 (3) | 0.008 (3) | 0.001 (3) |
C2 | 0.016 (4) | 0.012 (4) | 0.023 (4) | 0.001 (3) | 0.008 (3) | −0.002 (3) |
C3 | 0.011 (4) | 0.008 (3) | 0.024 (4) | −0.003 (3) | 0.005 (3) | −0.004 (3) |
C4 | 0.017 (4) | 0.019 (4) | 0.016 (4) | −0.002 (3) | 0.002 (3) | 0.001 (3) |
C5 | 0.011 (4) | 0.009 (4) | 0.016 (4) | 0.000 (3) | 0.003 (3) | −0.003 (3) |
C6 | 0.012 (4) | 0.019 (4) | 0.015 (4) | −0.005 (3) | 0.005 (3) | 0.003 (3) |
C7 | 0.017 (4) | 0.017 (4) | 0.016 (4) | 0.009 (3) | 0.005 (3) | −0.002 (3) |
C8 | 0.023 (4) | 0.008 (3) | 0.015 (4) | 0.000 (3) | 0.009 (3) | −0.001 (3) |
Pb1—O5i | 2.422 (6) | O5—C8 | 1.272 (9) |
Pb1—O1 | 2.489 (6) | O5—Pb1vii | 2.422 (6) |
Pb1—N1 | 2.554 (6) | O6—C8 | 1.238 (10) |
Pb1—O7ii | 2.627 (5) | O7—Pb2ii | 2.393 (5) |
Pb1—O3iii | 2.697 (6) | O7—Pb1ii | 2.627 (5) |
Pb1—O6 | 2.716 (6) | O7—H7 | 0.8286 |
Pb2—O1 | 2.600 (6) | N1—C1 | 1.348 (10) |
Pb2—O2iv | 2.836 (7) | N1—C5 | 1.355 (10) |
Pb2—O4v | 2.541 (6) | C1—C2 | 1.385 (11) |
Pb2—O7 | 2.318 (5) | C1—C6 | 1.515 (10) |
Pb2—O7ii | 2.393 (5) | C2—C3 | 1.401 (11) |
O1—C6 | 1.283 (10) | C2—H2 | 0.9300 |
O2—C6 | 1.256 (10) | C3—C4 | 1.400 (12) |
O3—C7 | 1.247 (11) | C3—C7 | 1.533 (11) |
O3—Pb1iii | 2.698 (6) | C4—C5 | 1.384 (11) |
O4—C7 | 1.258 (10) | C4—H4 | 0.9300 |
O4—Pb2vi | 2.541 (6) | C5—C8 | 1.519 (11) |
O5i—Pb1—O1 | 74.8 (2) | Pb2—O7—H7 | 127.9 |
O5i—Pb1—N1 | 70.8 (2) | Pb2ii—O7—H7 | 102.2 |
O1—Pb1—N1 | 64.0 (2) | Pb1ii—O7—H7 | 93.8 |
O5i—Pb1—O7ii | 103.54 (18) | C1—N1—C5 | 117.6 (6) |
O1—Pb1—O7ii | 66.24 (19) | C1—N1—Pb1 | 119.9 (5) |
N1—Pb1—O7ii | 129.54 (18) | C5—N1—Pb1 | 122.5 (5) |
O5i—Pb1—O3iii | 147.70 (19) | N1—C1—C2 | 123.2 (7) |
O1—Pb1—O3iii | 75.1 (2) | N1—C1—C6 | 114.1 (6) |
N1—Pb1—O3iii | 85.62 (18) | C2—C1—C6 | 122.6 (7) |
O7ii—Pb1—O3iii | 74.41 (17) | C1—C2—C3 | 118.4 (7) |
O5i—Pb1—O6 | 86.45 (19) | C1—C2—H2 | 120.8 |
O1—Pb1—O6 | 126.23 (19) | C3—C2—H2 | 120.8 |
N1—Pb1—O6 | 62.30 (18) | C4—C3—C2 | 119.2 (7) |
O7ii—Pb1—O6 | 166.35 (17) | C4—C3—C7 | 117.3 (7) |
O3iii—Pb1—O6 | 102.15 (18) | C2—C3—C7 | 123.4 (7) |
O7—Pb2—O7ii | 71.0 (2) | C5—C4—C3 | 118.1 (7) |
O7—Pb2—O4v | 98.8 (2) | C5—C4—H4 | 121.0 |
O7ii—Pb2—O4v | 71.47 (19) | C3—C4—H4 | 121.0 |
O7—Pb2—O1 | 90.7 (2) | N1—C5—C4 | 123.5 (7) |
O7ii—Pb2—O1 | 67.99 (19) | N1—C5—C8 | 115.6 (7) |
O4v—Pb2—O1 | 132.45 (19) | C4—C5—C8 | 120.9 (7) |
C6—O1—Pb1 | 121.8 (5) | O2—C6—O1 | 124.4 (7) |
C6—O1—Pb2 | 123.8 (5) | O2—C6—C1 | 118.4 (7) |
Pb1—O1—Pb2 | 106.2 (2) | O1—C6—C1 | 117.2 (7) |
C7—O3—Pb1iii | 124.4 (5) | O3—C7—O4 | 126.0 (8) |
C7—O4—Pb2vi | 101.9 (5) | O3—C7—C3 | 119.0 (7) |
C8—O5—Pb1vii | 110.5 (5) | O4—C7—C3 | 115.0 (7) |
C8—O6—Pb1 | 117.9 (5) | O6—C8—O5 | 125.3 (7) |
Pb2—O7—Pb2ii | 108.9 (2) | O6—C8—C5 | 119.7 (7) |
Pb2—O7—Pb1ii | 113.8 (2) | O5—C8—C5 | 115.0 (7) |
Pb2ii—O7—Pb1ii | 108.2 (2) | ||
O5i—Pb1—O1—C6 | −61.3 (6) | C5—N1—C1—C6 | 177.8 (6) |
N1—Pb1—O1—C6 | 14.5 (6) | Pb1—N1—C1—C6 | −1.6 (8) |
O7ii—Pb1—O1—C6 | −173.9 (7) | N1—C1—C2—C3 | 0.1 (11) |
O3iii—Pb1—O1—C6 | 106.9 (6) | C6—C1—C2—C3 | −178.4 (7) |
O6—Pb1—O1—C6 | 12.5 (7) | C1—C2—C3—C4 | 0.8 (11) |
O5i—Pb1—O1—Pb2 | 88.2 (3) | C1—C2—C3—C7 | −175.9 (7) |
N1—Pb1—O1—Pb2 | 163.9 (3) | C2—C3—C4—C5 | −0.9 (11) |
O7ii—Pb1—O1—Pb2 | −24.43 (19) | C7—C3—C4—C5 | 175.9 (7) |
O3iii—Pb1—O1—Pb2 | −103.7 (3) | C1—N1—C5—C4 | 0.6 (11) |
O6—Pb1—O1—Pb2 | 162.02 (19) | Pb1—N1—C5—C4 | 180.0 (6) |
O7—Pb2—O1—C6 | −115.5 (6) | C1—N1—C5—C8 | −177.3 (6) |
O7ii—Pb2—O1—C6 | 175.3 (7) | Pb1—N1—C5—C8 | 2.1 (8) |
O4v—Pb2—O1—C6 | 141.8 (6) | C3—C4—C5—N1 | 0.2 (11) |
O7—Pb2—O1—Pb1 | 95.8 (3) | C3—C4—C5—C8 | 178.0 (7) |
O7ii—Pb2—O1—Pb1 | 26.6 (2) | Pb1—O1—C6—O2 | 159.2 (7) |
O4v—Pb2—O1—Pb1 | −6.8 (4) | Pb2—O1—C6—O2 | 15.2 (11) |
O5i—Pb1—O6—C8 | 82.5 (6) | Pb1—O1—C6—C1 | −21.2 (9) |
O1—Pb1—O6—C8 | 14.3 (7) | Pb2—O1—C6—C1 | −165.2 (5) |
N1—Pb1—O6—C8 | 12.3 (5) | N1—C1—C6—O2 | −165.9 (7) |
O7ii—Pb1—O6—C8 | −139.9 (7) | C2—C1—C6—O2 | 12.7 (12) |
O3iii—Pb1—O6—C8 | −66.1 (6) | N1—C1—C6—O1 | 14.5 (10) |
O7ii—Pb2—O7—Pb2ii | 0.001 (1) | C2—C1—C6—O1 | −167.0 (7) |
O4v—Pb2—O7—Pb2ii | 66.8 (2) | Pb1iii—O3—C7—O4 | −100.9 (9) |
O1—Pb2—O7—Pb2ii | −66.4 (2) | Pb1iii—O3—C7—C3 | 78.7 (8) |
O7ii—Pb2—O7—Pb1ii | −120.9 (3) | Pb2vi—O4—C7—O3 | 11.2 (9) |
O4v—Pb2—O7—Pb1ii | −54.0 (2) | Pb2vi—O4—C7—C3 | −168.5 (5) |
O1—Pb2—O7—Pb1ii | 172.7 (2) | C4—C3—C7—O3 | −152.7 (7) |
O5i—Pb1—N1—C1 | 76.4 (5) | C2—C3—C7—O3 | 24.0 (11) |
O1—Pb1—N1—C1 | −5.6 (5) | C4—C3—C7—O4 | 27.0 (10) |
O7ii—Pb1—N1—C1 | −15.5 (6) | C2—C3—C7—O4 | −156.3 (7) |
O3iii—Pb1—N1—C1 | −81.2 (5) | Pb1—O6—C8—O5 | 165.4 (6) |
O6—Pb1—N1—C1 | 172.7 (6) | Pb1—O6—C8—C5 | −16.6 (9) |
O5i—Pb1—N1—C5 | −103.0 (5) | Pb1vii—O5—C8—O6 | 18.5 (10) |
O1—Pb1—N1—C5 | 175.0 (6) | Pb1vii—O5—C8—C5 | −159.6 (5) |
O7ii—Pb1—N1—C5 | 165.1 (5) | N1—C5—C8—O6 | 10.3 (10) |
O3iii—Pb1—N1—C5 | 99.5 (5) | C4—C5—C8—O6 | −167.6 (7) |
O6—Pb1—N1—C5 | −6.7 (5) | N1—C5—C8—O5 | −171.5 (6) |
C5—N1—C1—C2 | −0.7 (11) | C4—C5—C8—O5 | 10.6 (11) |
Pb1—N1—C1—C2 | 179.8 (6) |
Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) −x, −y+2, −z; (iii) −x+1, −y+2, −z+1; (iv) −x+1, −y+2, −z; (v) x−1, y, z−1; (vi) x+1, y, z+1; (vii) x, −y+3/2, z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O7—H7···O6viii | 0.83 | 2.58 | 2.989 (8) | 112 |
O7—H7···O4iii | 0.83 | 2.49 | 2.884 (8) | 110 |
Symmetry codes: (iii) −x+1, −y+2, −z+1; (viii) −x, y+1/2, −z+1/2. |
Experimental details
Crystal data | |
Chemical formula | [Pb2(C8H2NO6)(OH)] |
Mr | 639.49 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 291 |
a, b, c (Å) | 7.5391 (9), 14.1845 (17), 10.3084 (12) |
β (°) | 100.468 (1) |
V (Å3) | 1084.0 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 31.05 |
Crystal size (mm) | 0.38 × 0.26 × 0.25 |
Data collection | |
Diffractometer | Bruker SMART APEX CCD area-detector |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.030, 0.047 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7870, 2014, 1903 |
Rint | 0.036 |
(sin θ/λ)max (Å−1) | 0.605 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.028, 0.069, 1.08 |
No. of reflections | 2014 |
No. of parameters | 157 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.64, −2.07 |
Computer programs: SMART (Bruker, 1997), SAINT (Bruker, 1997), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
Pb1—O5i | 2.422 (6) | Pb2—O1 | 2.600 (6) |
Pb1—O1 | 2.489 (6) | Pb2—O2iv | 2.836 (7) |
Pb1—N1 | 2.554 (6) | Pb2—O4v | 2.541 (6) |
Pb1—O7ii | 2.627 (5) | Pb2—O7 | 2.318 (5) |
Pb1—O3iii | 2.697 (6) | Pb2—O7ii | 2.393 (5) |
Pb1—O6 | 2.716 (6) |
Symmetry codes: (i) x, −y+3/2, z−1/2; (ii) −x, −y+2, −z; (iii) −x+1, −y+2, −z+1; (iv) −x+1, −y+2, −z; (v) x−1, y, z−1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O7—H7···O6vi | 0.83 | 2.58 | 2.989 (8) | 111.6 |
O7—H7···O4iii | 0.83 | 2.49 | 2.884 (8) | 110.1 |
Symmetry codes: (iii) −x+1, −y+2, −z+1; (vi) −x, y+1/2, −z+1/2. |
Acknowledgements
We are grateful to the Natural Science Foundation of Anhui province (No. 090416234) for funding this study. We also thank the Doctoral Startup Foundation of Anhui Normal University.
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Until recently, the construction of coordination polymers has been an active area because of the properties of catalysis and molecular magnetism (Shi et al., 2010; O'Keeffe et al., 2008; Zhang et al., 2009). Pyridine-2,4,6-tricarboxylic acid (H3ptc) is an effective ligand for coordinating to metal cations to generate diverse interesting coordination polymer architectures (Zhao et al., 2009; Yigit et al., 2005). However, the coordination polymers containing H3ptc ligands are seldom high-dimensional complexes (Das et al., 2009; Ghosh et al., 2006). Because of the relatively large ionic radius of the Pb(II) cation, the lead complex should form some interesting frameworks (Ding et al., 2009). Herein, we report the lead polymeric complex [Pb2(C8H2NO6)(OH)]n, (I), which is an unique homometallic three-dimensional framework compound.
The asymmetric unit of (I) consists of two Pb(II) cations, one ptc trianion and one coordinated hydroxyl anion. As shown in Fig. 1, atom Pb1 is six-coordinated by two carboxylate O and one N atoms from a ligand ptc and one hydroxide anion O in a distorted square-planar geometry, and two carboxylate O atoms from the other two ligand ptc in the axial positions (Table 1). The PbNO5 octahedron is distorted, with the O—Pb1—O(N) bond angles ranging from 64.0 (2) to 147.70 (19)°. Whereas atom Pb2 is five-coordinated by three carboxylate O atoms from two ptc and two µ3-hydroxide O atoms in a distorted tetragonal pyramid geometry. The Pb—O and Pb—N distances (Table 1) are comparable with those observed for [Pb2(bdc)2(piphen)2]n (bdc is benzene-1,4-dicarboxylate and piphen is 6-(4-pyridyl)-5H- imidazolo[4,5-f][1,10]phenanthroline; Xu et al., 2010). Each ptc molecule employs its three carboxylate groups and one N atom to chelate and bridge six Pb(II) cations. Two neighbouring Pb2 atoms are bis-bridged by two hydroxide O atoms (O7 and O7ii) to form a centrosymmetric [Pb2(OH)2]2+ core which is linked by two Pb1 atoms through Pb1—O7ii and Pb1ii—O7 bonds to form [Pb12Pb22(OH)2]6+ unit (Fig. 2). The bonds of Pb2—O4iv, Pb2—O1, Pb2ii—O1ii and Pb2ii—O4iii bonds surrounding the [Pb2(OH)2]2+ unit are contributed to forming a two-dimensional structure which is further tightened by the atoms of Pb1i, Pb1iii, Pb1iv, Pb1v, Pb1vi and Pb1vii with joining neighbouring ptc ligands. Also, the two adjacent pyridine rings of ptc ligands are involved in π–π stacking interactions with offset face-to-face mode [centroid-to-centroid distance 3.5486 (4) Å] (Fig. 2). Furthermore, the two-dimensional structure are linked through Pb1—O5i and Pb1ii—O5v bonds to generate a three-dimensional stereo structure. There are some hydrogen bonds O—H···O in (I) between the hydroxide H atom and carboxylic O4iii with an O···O distance of 2.884 (8) Å (Table 2). Hydrogen bonds are helpful to enhance the stability of the molecular structure. A remarkable feature of this structure is the arrangement of [Pb12Pb22(OH)2]6+ units with infinite helices extending along the crystallographic b axis with intervening ptc ligands (Fig. 3). The helical structure is a comprehensive result of metal-ligand interactions and the π–π stacking interactions of pyridine rings of ptc ligands.