Poly[diaqua­bis(μ₂-5-carb­oxy-2-propyl-1H-imidazole-4-carboxyl­ato-κ³N³,O⁴:O⁵)lead(II)]

In the title complex, [Pb(C₈H₉N₂O₄)₂(H₂O)₂]_n, the eight-coordinate Pb^II atom lies on a twofold rotation axis and adopts a slightly distorted square-anti­prismatic N₂O₆ coordination geometry. The ligand donor atoms are the tertiary N atoms of the imidazole rings and the carboxyl­ate O atoms of two chelating 5-carb­oxy-2-propyl-1H-imidazole-4-carboxyl­ate ligands, the carb­oxy O atoms of two additional imidazole ligands and two water O atoms. The carb­oxy O and the N,O-chelate systems also link adjacent Pb^II atoms, forming a two-dimensional layer structure, with four individual Pb^II atoms located at the corners of a square. These layers are further inter­connected by an extensive array of O—H...O and N—H...O hydrogen bonds into a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.019
• wR factor = 0.039
• Data-to-parameter ratio = 12.2

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Pb1    --  O1      ..       5.49 su
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Pb1    --  O5      ..       6.02 su
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.594          5

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported   _diffrn_ambient_temperature        293 K
PLAT808_ALERT_5_G No Parsable SHELXL style Weighting Scheme Found           !
PLAT929_ALERT_4_G No Interpretable (SHELX) Weight Parameters found          ?

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   3 ALERT level C = Check and explain
   4 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

It is well known that 4,5-imidazoledicarboxylic acid, a rigid N-heterocyclic dicarboxylic acid has great potential as a ligand in coordination complexes and for hydrogen bond formation. Imidazoledicarboxylate complexes have been found to exhibit useful properties, such as magnetism and porosity (Cao et al., 2002; Rajendiran et al., 2003). We have therefore reacted the 2-propyl-1H-imidazole-4,5 dicarboxylic acid ligand with Pb(NO₃)₂ under hydrothermal conditions to obtain a new Pb^II complex and its structure is reported here.

In the title complex, [Pb(C₈H₉N₂O₄)₂(H₂O)₂]_n, the eight coordinate Pb^II atom lies on a two-fold rotation axis and adopts a slightly distorted square-antiprismatic N₂O₆ coordination geometry. The ligand donor atoms are the N1 atoms of the imidazole rings and the carboxylate O1 atoms of two chelating 5-carboxy-2-propyl-1H-imidazole-4- carboxylato ligands, the O4 carboxy oxygen atoms of two additional imidazole ligands and two O5 water molecules. The O1 and N1 atoms of the chelate systems also link adjacent Pb^II centres forming a two-dimensional layer structure, with four individual Pb^II atoms located at the corners of a square. These layers are further interconnected by an extensive array of O—H···O and N—H···O hydrogen bonds into a three-dimensional network.

Related literature

For the properties and uses of imidazoledicarboxylate complexes, see: Cao et al. (2002); Rajendiran et al. (2003).

S2. Experimental

A mixture of Pb(NO₃)₂ (0.5 mmol, 0.07 g) and 2-propyl-1H-imidazole-4,5-dicarboxylic acid(0.5 mmol, 0.99 g) in 15 ml of H₂O solution was sealed in an autoclave equipped with a Teflon liner (25 ml) and then heated at 373k for 3 days. Crystals of the title compound were obtained by slow evaporation of the solvent at room temperature.

S3. Refinement

Carbon and nitrogen bound H atoms were placed at calculated positions and were treated as riding on the parent C or N atoms with C—H = 0.93 Å, N—H = 0.86 Å, and with U_iso(H) = 1.2 U_eq(C, N). H atoms of the water molecule were located in a difference map and were allowed to ride on the parent atom, with U_iso(H)=1.2 U_eq.

Computing details

Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008) and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The structure of the title compound, showing the atomic numbering scheme. Non-H atoms are shown with 30% probability displacement ellipsoids(H atoms are omitted for clarity). [Symmetry codes: (i) 1-x, y, 1.5-z; (ii) -0.5+x, 0.5+y, z; (iii) 0.5+x, 0.5+y, z; (iv) 0.5+x, -0.5+y, z; (v) 0.5-x, -0.5+y, 1.5-z]
	Fig. 2. A two-dimensional layer constructed of Pb4 squares
	Fig. 3. Crystal packing of the title compound

Poly[diaquabis(µ₂-5-carboxy-2-propyl-1H-imidazole-4-carboxylato- κ³N³,O⁴:O⁵)lead(II)]

Crystal data

[Pb(C8H9N2O4)2(H2O)2]	F(000) = 1232
Mr = 637.57	Dx = 2.118 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 2051 reflections
a = 13.1201 (15) Å	θ = 2.5–23.9°
b = 13.2929 (16) Å	µ = 8.50 mm^−1
c = 11.5910 (13) Å	T = 293 K
β = 98.531 (2)°	Block, colorless
V = 1999.2 (4) Å^3	0.45 × 0.17 × 0.13 mm
Z = 4

Data collection

Bruker SMART 1000 CCD area-detector diffractometer	1751 independent reflections
Radiation source: fine-focus sealed tube	1640 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.048
φ and ω scans	θmax = 25.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2007)	h = −13→15
Tmin = 0.114, Tmax = 0.404	k = −15→15
4884 measured reflections	l = −10→13

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.019	H-atom parameters constrained
wR(F^2) = 0.039	w = 1/[σ^2(Fo^2) + 0.170P] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max = 0.002
1751 reflections	Δρmax = 0.82 e Å^−3
143 parameters	Δρmin = −0.69 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.00501 (14)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Pb1	0.5000	0.585420 (12)	0.7500	0.02187 (10)
N1	0.36101 (17)	0.72953 (19)	0.7416 (2)	0.0206 (6)
N2	0.26176 (19)	0.8636 (2)	0.7255 (2)	0.0245 (6)
H2	0.2380	0.9221	0.7040	0.029*
O1	0.33533 (16)	0.55121 (18)	0.8607 (2)	0.0288 (6)
O2	0.20043 (17)	0.61233 (19)	0.9317 (2)	0.0346 (6)
O3	0.09662 (17)	0.7669 (2)	0.9230 (2)	0.0400 (7)
H3	0.1304	0.7149	0.9245	0.060*
O4	0.0980 (2)	0.9168 (2)	0.8428 (3)	0.0521 (9)
O5	0.43915 (18)	0.6096 (2)	0.5232 (2)	0.0374 (6)
H5C	0.4120	0.5656	0.4750	0.045*
H5D	0.4830	0.6427	0.4915	0.045*
C1	0.2736 (2)	0.6209 (3)	0.8716 (3)	0.0240 (7)
C2	0.2842 (2)	0.7169 (2)	0.8095 (3)	0.0204 (7)
C3	0.2221 (2)	0.8003 (3)	0.7997 (3)	0.0228 (8)
C4	0.1323 (3)	0.8316 (3)	0.8572 (3)	0.0314 (9)
C5	0.3450 (2)	0.8188 (2)	0.6912 (3)	0.0230 (8)
C6	0.4039 (2)	0.8661 (3)	0.6046 (3)	0.0285 (8)
H6A	0.4688	0.8309	0.6062	0.034*
H6B	0.4193	0.9353	0.6274	0.034*
C7	0.3461 (3)	0.8646 (3)	0.4806 (3)	0.0355 (9)
H7A	0.3380	0.7954	0.4541	0.043*
H7B	0.2779	0.8928	0.4803	0.043*
C8	0.4016 (3)	0.9236 (3)	0.3967 (4)	0.0408 (10)
H8A	0.4129	0.9913	0.4246	0.061*
H8B	0.3604	0.9245	0.3210	0.061*
H8C	0.4667	0.8923	0.3914	0.061*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pb1	0.02470 (12)	0.01520 (13)	0.02690 (14)	0.000	0.00777 (7)	0.000
N1	0.0251 (13)	0.0146 (16)	0.0229 (15)	0.0002 (11)	0.0059 (11)	0.0026 (13)
N2	0.0337 (15)	0.0126 (15)	0.0273 (16)	0.0049 (12)	0.0047 (12)	0.0059 (14)
O1	0.0343 (13)	0.0162 (13)	0.0375 (15)	0.0015 (10)	0.0110 (10)	0.0029 (12)
O2	0.0376 (14)	0.0306 (14)	0.0396 (16)	−0.0018 (11)	0.0191 (11)	0.0072 (13)
O3	0.0354 (13)	0.0414 (18)	0.0474 (17)	0.0086 (12)	0.0203 (11)	0.0008 (15)
O4	0.0632 (18)	0.046 (2)	0.051 (2)	0.0373 (14)	0.0236 (15)	0.0114 (15)
O5	0.0407 (14)	0.0395 (16)	0.0338 (16)	−0.0070 (12)	0.0115 (11)	−0.0025 (13)
C1	0.0266 (17)	0.0222 (19)	0.0236 (19)	−0.0044 (15)	0.0049 (14)	−0.0031 (17)
C2	0.0235 (15)	0.0163 (18)	0.0212 (18)	−0.0013 (13)	0.0026 (13)	−0.0018 (15)
C3	0.0264 (16)	0.022 (2)	0.0198 (18)	0.0019 (14)	0.0022 (13)	−0.0012 (16)
C4	0.0335 (19)	0.035 (2)	0.027 (2)	0.0074 (17)	0.0083 (15)	−0.0017 (19)
C5	0.0244 (16)	0.0178 (19)	0.0266 (19)	−0.0001 (14)	0.0030 (13)	0.0008 (16)
C6	0.0286 (18)	0.025 (2)	0.033 (2)	−0.0009 (15)	0.0050 (14)	0.0066 (18)
C7	0.0365 (19)	0.037 (2)	0.033 (2)	−0.0111 (17)	0.0026 (15)	0.003 (2)
C8	0.049 (2)	0.042 (3)	0.031 (2)	−0.0065 (18)	0.0058 (18)	0.0088 (19)

Geometric parameters (Å, º)

Pb1—N1	2.637 (2)	O4—C4	1.221 (4)
Pb1—N1^i	2.637 (2)	O4—Pb1^iv	2.725 (3)
Pb1—O5^i	2.651 (3)	O5—H5C	0.8500
Pb1—O5	2.652 (3)	O5—H5D	0.8500
Pb1—O1	2.710 (2)	C1—C2	1.481 (5)
Pb1—O1^i	2.710 (2)	C2—C3	1.370 (4)
Pb1—O4^ii	2.725 (3)	C3—C4	1.496 (5)
Pb1—O4^iii	2.725 (3)	C5—C6	1.494 (5)
N1—C5	1.326 (4)	C6—C7	1.522 (4)
N1—C2	1.377 (4)	C6—H6A	0.9700
N2—C5	1.354 (4)	C6—H6B	0.9700
N2—C3	1.361 (5)	C7—C8	1.517 (5)
N2—H2	0.8600	C7—H7A	0.9700
O1—C1	1.249 (4)	C7—H7B	0.9700
O2—C1	1.273 (4)	C8—H8A	0.9600
O3—C4	1.284 (4)	C8—H8B	0.9600
O3—H3	0.8200	C8—H8C	0.9600
N1—Pb1—N1^i	86.81 (11)	Pb1—O5—H5C	127.1
N1—Pb1—O5^i	93.06 (8)	Pb1—O5—H5D	111.6
N1^i—Pb1—O5^i	76.75 (8)	H5C—O5—H5D	108.5
N1—Pb1—O5	76.75 (8)	O1—C1—O2	122.8 (3)
N1^i—Pb1—O5	93.06 (8)	O1—C1—C2	118.7 (3)
O5^i—Pb1—O5	166.09 (11)	O2—C1—C2	118.4 (3)
N1—Pb1—O1	62.85 (7)	C3—C2—N1	109.3 (3)
N1^i—Pb1—O1	134.44 (7)	C3—C2—C1	129.8 (3)
O5^i—Pb1—O1	72.23 (7)	N1—C2—C1	120.8 (3)
O5—Pb1—O1	110.24 (7)	N2—C3—C2	106.0 (3)
N1—Pb1—O1^i	134.44 (7)	N2—C3—C4	120.6 (3)
N1^i—Pb1—O1^i	62.85 (7)	C2—C3—C4	133.3 (3)
O5^i—Pb1—O1^i	110.23 (7)	O4—C4—O3	122.8 (3)
O5—Pb1—O1^i	72.23 (7)	O4—C4—C3	119.8 (4)
O1—Pb1—O1^i	160.68 (10)	O3—C4—C3	117.3 (3)
N1—Pb1—O4^ii	153.57 (9)	N1—C5—N2	110.3 (3)
N1^i—Pb1—O4^ii	107.45 (9)	N1—C5—C6	127.6 (3)
O5^i—Pb1—O4^ii	69.71 (9)	N2—C5—C6	122.1 (3)
O5—Pb1—O4^ii	123.10 (9)	C5—C6—C7	113.2 (3)
O1—Pb1—O4^ii	92.16 (8)	C5—C6—H6A	108.9
O1^i—Pb1—O4^ii	71.71 (8)	C7—C6—H6A	108.9
N1—Pb1—O4^iii	107.46 (9)	C5—C6—H6B	108.9
N1^i—Pb1—O4^iii	153.56 (9)	C7—C6—H6B	108.9
O5^i—Pb1—O4^iii	123.10 (9)	H6A—C6—H6B	107.8
O5—Pb1—O4^iii	69.70 (9)	C8—C7—C6	112.3 (3)
O1—Pb1—O4^iii	71.72 (8)	C8—C7—H7A	109.1
O1^i—Pb1—O4^iii	92.16 (8)	C6—C7—H7A	109.1
O4^ii—Pb1—O4^iii	69.29 (14)	C8—C7—H7B	109.1
C5—N1—C2	106.2 (3)	C6—C7—H7B	109.1
C5—N1—Pb1	136.9 (2)	H7A—C7—H7B	107.9
C2—N1—Pb1	116.79 (19)	C7—C8—H8A	109.5
C5—N2—C3	108.3 (3)	C7—C8—H8B	109.5
C5—N2—H2	125.9	H8A—C8—H8B	109.5
C3—N2—H2	125.9	C7—C8—H8C	109.5
C1—O1—Pb1	119.8 (2)	H8A—C8—H8C	109.5
C4—O3—H3	109.5	H8B—C8—H8C	109.5
C4—O4—Pb1^iv	163.7 (3)
N1^i—Pb1—N1—C5	39.1 (3)	Pb1—N1—C2—C1	−7.6 (3)
O5^i—Pb1—N1—C5	115.6 (3)	O1—C1—C2—C3	174.0 (3)
O5—Pb1—N1—C5	−54.8 (3)	O2—C1—C2—C3	−4.4 (5)
O1—Pb1—N1—C5	−176.2 (3)	O1—C1—C2—N1	−0.5 (4)
O1^i—Pb1—N1—C5	−6.9 (3)	O2—C1—C2—N1	−178.9 (3)
O4^ii—Pb1—N1—C5	163.3 (3)	C5—N2—C3—C2	0.4 (4)
O4^iii—Pb1—N1—C5	−118.2 (3)	C5—N2—C3—C4	176.8 (3)
N1^i—Pb1—N1—C2	−137.1 (2)	N1—C2—C3—N2	0.0 (3)
O5^i—Pb1—N1—C2	−60.6 (2)	C1—C2—C3—N2	−175.0 (3)
O5—Pb1—N1—C2	129.0 (2)	N1—C2—C3—C4	−175.8 (3)
O1—Pb1—N1—C2	7.63 (19)	C1—C2—C3—C4	9.3 (6)
O1^i—Pb1—N1—C2	176.89 (18)	Pb1^iv—O4—C4—O3	−108.0 (9)
O4^ii—Pb1—N1—C2	−12.9 (3)	Pb1^iv—O4—C4—C3	74.0 (10)
O4^iii—Pb1—N1—C2	65.6 (2)	N2—C3—C4—O4	−4.3 (5)
N1—Pb1—O1—C1	−8.6 (2)	C2—C3—C4—O4	171.0 (4)
N1^i—Pb1—O1—C1	45.2 (3)	N2—C3—C4—O3	177.7 (3)
O5^i—Pb1—O1—C1	94.6 (2)	C2—C3—C4—O3	−7.1 (6)
O5—Pb1—O1—C1	−70.9 (2)	C2—N1—C5—N2	0.7 (3)
O1^i—Pb1—O1—C1	−164.9 (2)	Pb1—N1—C5—N2	−175.8 (2)
O4^ii—Pb1—O1—C1	162.5 (2)	C2—N1—C5—C6	−176.9 (3)
O4^iii—Pb1—O1—C1	−130.2 (2)	Pb1—N1—C5—C6	6.7 (5)
Pb1—O1—C1—O2	−173.4 (2)	C3—N2—C5—N1	−0.7 (4)
Pb1—O1—C1—C2	8.3 (4)	C3—N2—C5—C6	177.0 (3)
C5—N1—C2—C3	−0.4 (3)	N1—C5—C6—C7	105.0 (4)
Pb1—N1—C2—C3	176.90 (19)	N2—C5—C6—C7	−72.3 (4)
C5—N1—C2—C1	175.1 (3)	C5—C6—C7—C8	173.3 (3)

Symmetry codes: (i) −x+1, y, −z+3/2; (ii) x+1/2, y−1/2, z; (iii) −x+1/2, y−1/2, −z+3/2; (iv) x−1/2, y+1/2, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O5—H5D···O4^v	0.85	2.58	3.182 (4)	129
O5—H5D···O3^v	0.85	2.16	3.004 (3)	176
O5—H5C···O1^vi	0.85	2.19	3.035 (3)	176
O3—H3···O2	0.82	1.64	2.459 (3)	178
N2—H2···O1^vii	0.86	2.05	2.909 (4)	172

Symmetry codes: (v) x+1/2, −y+3/2, z−1/2; (vi) x, −y+1, z−1/2; (vii) −x+1/2, y+1/2, −z+3/2.