Poly[aqua­(μ-pyrazine-2-carboxyl­ato-κ³N,O:O)(μ-pyrazine-2-carboxyl­ato-κ³N,O:O′)lead(II)]

The polymeric structure of the title compound, [Pb(C₅H₃N₂O₂)₂(H₂O)]_n, is built up from centrosymmetric [Pb(C₅H₃N₂O₂)₂(H₂O)]₂ dimers, which are bridged by ligand carboxyl­ate O atoms. The Pb^II ion adopts an irregular PbN₂O₅ coordination polyhedron; it is chelated by one N,O-bidentate ligand and also bonds to a water O atom. A second N,O-bidentate ligand forms the dimer bridge and another bridging O atom from a nearby dimer also bonds to the Pb^II ion, leading to layers propagating in (100). A network of O—H...O hydrogen bonds operates between water O atoms (donors) and carboxyl­ate O atoms (acceptors).

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.018 Å
• R factor = 0.058
• wR factor = 0.163
• Data-to-parameter ratio = 18.1

checkCIF/PLATON results

No syntax errors found



Alert level C
DIFMX01_ALERT_2_C  The maximum difference density is > 0.1*ZMAX*0.75
            _refine_diff_density_max given =      6.450
            Test value =      6.150
DIFMX02_ALERT_1_C  The maximum difference density is > 0.1*ZMAX*0.75
            The relevant atom site should be identified.
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......       0.96
PLAT097_ALERT_2_C Large Reported Max.  (Positive) Residual Density       6.45 eA-3
PLAT342_ALERT_3_C Low Bond Precision on  C-C Bonds (x 1000) Ang ..         18
PLAT369_ALERT_2_C Long   C(sp2)-C(sp2) Bond  C22    -   C27    ...       1.53 Ang.
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         87
PLAT971_ALERT_2_C Large Calcd. Non-Metal Positive Residual Density       1.58 eA-3
PLAT971_ALERT_2_C Large Calcd. Non-Metal Positive Residual Density       1.53 eA-3
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT153_ALERT_1_C The su's on the Cell Axes   are Equal (x 100000)        200 Ang.
PLAT731_ALERT_1_C Bond    Calc     0.84(8), Rep     0.84(2) ......       4.00 su-Ra
              O1   -H1      1.555   1.555
PLAT732_ALERT_1_C Angle   Calc     106(11), Rep      106(3) ......       3.67 su-Ra
              H1   -O1   -H2      1.555   1.555   1.555
PLAT735_ALERT_1_C D-H     Calc     0.84(8), Rep     0.84(2) ......       4.00 su-Ra
              O1   -H1      1.555   1.555
PLAT735_ALERT_1_C D-H     Calc     0.84(8), Rep     0.84(2) ......       4.00 su-Ra
              O1   -H1      1.555   1.555
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600         80

Alert level G
PLAT072_ALERT_2_G SHELXL First Parameter in WGHT Unusually Large..       0.12
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          5
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported   _diffrn_ambient_temperature        293 K

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

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

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S1. Comment

Divalent UO₂(II) ion (Alcock et al.,1996), 3-d metal M(II) ions (Ptasiewicz-Bąk et al.,(1995), Ca(II) and Sr(II) ions (Ptasiewicz-Bąk et al.,1998) form with pyrazine-2-carboxylate and water ligands monomeric molecules with coordination modes characteristic for particular ions. On the other hand, the structure of a Pb(II) complex with pyridazine-4-carboxylate and water ligands is composed of dimeric molecules (Starosta & Leciejewicz, 2009), while the structure of a Pb(II) complex with pyridazine-3-carboxylate and water ligands is polymeric (Starosta & Leciejewicz, 2010). The structure of title compound (I) is composed of centrosymmetric dimeric molecules in which each of the two Pb(II) ions is cheletated by two symmetry independent ligands via their N,O bonding groups. Their planes make at the metal ion an angle of 85.1 (2)^o each to the other. Pb(II) ions are bridged by O11 and O11⁽ⁱ⁾ atoms donated by symmetry related ligands L1. The O12 and O12⁽ⁱ⁾ atoms do not take part in coordination. A water O atom is chelated to each metal ion. The second pair of ligand molecules L2 also coordinates the Pb(II) ions by their N,O bonding groups while the O22 and O22⁽ⁱ⁾ atoms act as bridges to Pb(II) ions in adjacent dimers. A polymeric structure is formed in this way. The coordination geometry of a Pb(II) ion is represented by a pyramid in which N11, O11, O11^(I) and O1 atoms form an equatorial plane [ r.m.s. 0.0083 (1) Å] with a Pb(II) ion shifted from it by 0.3079 (2) Å; N21 and O21 atoms make two apices of the pyramid while the bridging O22^(II) atom forms a single apex on the other side of the equatorial plane. Bond angles reveal an empty space around the metal ion between Pb—O11^(I)and Pb—O1 bonds It may indicate the stereochemical activity of the lone 6 s² electron pair of the Pb(II) ion. Pyrazine rings of both ligands are planar: r.m.s. 0.0089 (2)Å in L1 and 0.0046 (1)Å in L2. The C17/O11/O12 carboxylic group makes an angle of 6.7 (1)° with pyrazine ring L1, the carboxylic group C27/O21/O22 - an angle of 9.1 (1)° with L2. Weak hydrogen bonds operate between the coordinated water O atoms (donors) and carboxylate O21 and O22 atoms (acceptors) in adjacent dimers.

Related literature

For the crystal structures of divalent metal ions with pyrazine-2-carboxylate and water ligands, see, for example: Alcock et al. (1996); Ptasiewicz-Bąk et al. (1995, 1998). The structures of lead(II) complexes with pyrazine-4-carboxylate (Starosta & Leciejewicz, 2009) and pyrazine-3-carboxylate ligands (Starosta & Leciejewicz, 2010) have also been reported.

S2. Experimental

The title compound was synthetized by reacting boiling aqueous solution of pyrazine-2-carboxylic acid dihydrate (Aldrich) with some excess of lead(II) hydroxide. The mixture was boiled under reflux for three hours and after cooling to room temperature, filtered and left for crystallization. Few days later, colourless blocks of (I) were found after evaporation to dryness. They were extracted, washed with cold ethanol and dried in the air.

S3. Refinement

Water hydrogen atoms were found from Fourier maps and restrained geometrically to form hydrogen bonds. H atoms attached to pyrazine -ring C atoms were positioned geometrically and refined with a riding model. A maximum peak of 6.450 e ų (at 0.83 Å) and a deepest hole of -5.858 e ų (at 0.80 Å) were found on the final electron density map close to the Pb1 atom.

Computing details

Data collection: KM-4 Software (Kuma, 1996); cell refinement: KM-4 Software (Kuma, 1996); data reduction: DATAPROC (Kuma, 2001); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. A structural unit of (1) with 50% probability displacement ellipsoids. Symmetry codes: (i) -x+1,-y,-z+1; (ii) x,-y+1/2,z-1/2.
	Fig. 2. Packing diagram of the structure of (I).

Poly[aqua(µ-pyrazine-2-carboxylato-κ³N,O:O)(µ- pyrazine-2-carboxylato-κ³N,O:O')lead(II)]

Crystal data

[Pb(C5H3N2O2)2(H2O)]	F(000) = 872
Mr = 471.39	Dx = 2.550 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 25 reflections
a = 11.098 (2) Å	θ = 6–15°
b = 10.382 (2) Å	µ = 13.77 mm^−1
c = 11.678 (2) Å	T = 293 K
β = 114.13 (3)°	Blocks, colourless
V = 1228.0 (4) Å^3	0.29 × 0.16 × 0.12 mm
Z = 4

Data collection

Kuma KM-4 four-circle diffractometer	2230 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.051
Graphite monochromator	θmax = 30.1°, θmin = 2.0°
profile data from ω/2θ scans	h = 0→14
Absorption correction: analytical (CrysAlis RED; Oxford Diffraction, 2008)	k = −14→0
Tmin = 0.135, Tmax = 0.251	l = −15→14
3579 measured reflections	3 standard reflections every 200 reflections
3411 independent reflections	intensity decay: 20.2%

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)] = 0.058	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.163	w = 1/[σ^2(Fo^2) + (0.1217P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max < 0.001
3411 reflections	Δρmax = 6.45 e Å^−3
188 parameters	Δρmin = −5.86 e Å^−3
5 restraints	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0154 (12)

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	0.47863 (3)	0.12876 (4)	0.35712 (3)	0.02848 (19)
O11	0.3570 (7)	−0.0031 (8)	0.4636 (8)	0.0413 (18)
C22	0.6620 (9)	0.3784 (10)	0.5171 (10)	0.034 (2)
O21	0.4811 (9)	0.2586 (8)	0.5220 (8)	0.0399 (18)
N21	0.6655 (8)	0.2972 (9)	0.4344 (8)	0.0327 (18)
C12	0.1581 (9)	0.1152 (9)	0.3625 (10)	0.0299 (19)
C13	0.0296 (11)	0.1383 (11)	0.3473 (11)	0.039 (2)
H13	−0.0039	0.0957	0.3980	0.047*
C27	0.5599 (12)	0.3532 (11)	0.5717 (12)	0.040 (2)
N22	0.8312 (12)	0.5089 (11)	0.5106 (13)	0.059 (3)
C26	0.7546 (11)	0.3203 (12)	0.3893 (12)	0.039 (2)
H26	0.7616	0.2642	0.3303	0.047*
N11	0.2083 (9)	0.1695 (10)	0.2906 (9)	0.0362 (19)
C16	0.1307 (12)	0.2491 (12)	0.2013 (12)	0.045 (3)
H16	0.1628	0.2889	0.1481	0.054*
C23	0.7440 (13)	0.4853 (12)	0.5559 (14)	0.050 (3)
H23	0.7365	0.5409	0.6151	0.060*
O1	0.4080 (11)	0.3287 (10)	0.2149 (9)	0.056 (2)
H1	0.378 (11)	0.402 (7)	0.218 (10)	0.084*
H2	0.385 (8)	0.312 (13)	0.138 (3)	0.084*
O12	0.2045 (8)	−0.0170 (9)	0.5394 (8)	0.0445 (19)
C17	0.2455 (9)	0.0251 (9)	0.4646 (9)	0.0275 (18)
N12	−0.0479 (10)	0.2225 (11)	0.2591 (11)	0.050 (3)
C15	0.0023 (12)	0.2730 (13)	0.1871 (12)	0.047 (3)
H15	−0.0500	0.3278	0.1230	0.056*
C25	0.8376 (14)	0.4253 (14)	0.4272 (15)	0.055 (3)
H25	0.8995	0.4379	0.3935	0.066*
O22	0.5643 (12)	0.4168 (10)	0.6610 (9)	0.054 (2)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pb1	0.0271 (2)	0.0296 (2)	0.0327 (3)	0.00255 (14)	0.01621 (15)	0.00445 (14)
O11	0.024 (3)	0.044 (4)	0.060 (5)	0.005 (3)	0.020 (3)	0.021 (4)
C22	0.019 (4)	0.039 (5)	0.041 (5)	−0.002 (4)	0.010 (4)	0.008 (4)
O21	0.045 (4)	0.035 (4)	0.058 (5)	−0.011 (3)	0.040 (4)	−0.012 (3)
N21	0.024 (4)	0.044 (5)	0.038 (5)	−0.005 (4)	0.021 (3)	−0.002 (4)
C12	0.018 (4)	0.035 (5)	0.038 (5)	−0.002 (3)	0.012 (3)	−0.003 (4)
C13	0.031 (5)	0.048 (7)	0.041 (6)	0.009 (4)	0.019 (4)	−0.001 (4)
C27	0.038 (6)	0.039 (6)	0.047 (6)	−0.005 (4)	0.020 (5)	−0.001 (4)
N22	0.048 (6)	0.050 (6)	0.091 (9)	−0.021 (5)	0.042 (6)	−0.007 (6)
C26	0.034 (5)	0.050 (6)	0.050 (6)	−0.004 (5)	0.032 (5)	−0.003 (5)
N11	0.027 (4)	0.043 (5)	0.040 (5)	0.001 (4)	0.016 (4)	0.009 (4)
C16	0.039 (7)	0.046 (6)	0.051 (7)	0.008 (5)	0.018 (6)	0.021 (5)
C23	0.042 (6)	0.040 (6)	0.077 (9)	−0.017 (5)	0.032 (6)	−0.012 (6)
O1	0.072 (7)	0.052 (5)	0.042 (5)	0.009 (5)	0.022 (5)	0.013 (4)
O12	0.040 (4)	0.056 (5)	0.044 (4)	0.002 (4)	0.024 (3)	0.011 (4)
C17	0.022 (4)	0.027 (4)	0.033 (5)	−0.007 (3)	0.011 (3)	−0.003 (3)
N12	0.031 (5)	0.064 (7)	0.054 (6)	0.018 (5)	0.016 (5)	−0.003 (5)
C15	0.030 (6)	0.057 (8)	0.045 (7)	0.011 (5)	0.008 (5)	0.012 (5)
C25	0.044 (7)	0.055 (8)	0.081 (10)	−0.015 (6)	0.041 (7)	0.003 (7)
O22	0.077 (6)	0.062 (6)	0.042 (5)	−0.030 (5)	0.043 (4)	−0.017 (4)

Geometric parameters (Å, º)

Pb1—O21	2.341 (7)	C13—N12	1.357 (15)
Pb1—O11^i	2.508 (7)	C13—H13	0.9300
Pb1—O1	2.573 (9)	C27—O22	1.217 (15)
Pb1—O11	2.572 (8)	N22—C23	1.302 (17)
Pb1—N21	2.577 (9)	N22—C25	1.328 (19)
Pb1—N11	2.807 (9)	C26—C25	1.378 (18)
Pb1—O22^ii	2.856 (8)	C26—H26	0.9300
O11—C17	1.277 (12)	N11—C16	1.334 (14)
O11—Pb1^i	2.508 (7)	C16—C15	1.388 (17)
C22—N21	1.295 (14)	C16—H16	0.9300
C22—C23	1.389 (15)	C23—H23	0.9300
C22—C27	1.532 (16)	O1—H1	0.84 (2)
O21—C27	1.285 (14)	O1—H2	0.84 (2)
N21—C26	1.318 (12)	O12—C17	1.219 (12)
C12—N11	1.310 (13)	N12—C15	1.295 (17)
C12—C13	1.385 (13)	C15—H15	0.9300
C12—C17	1.513 (13)	C25—H25	0.9300
O21—Pb1—O11^i	81.6 (3)	C13—C12—C17	120.2 (9)
O21—Pb1—O1	88.0 (3)	N12—C13—C12	120.6 (11)
O11^i—Pb1—O1	152.2 (3)	N12—C13—H13	119.7
O21—Pb1—O11	75.0 (3)	C12—C13—H13	119.7
O11^i—Pb1—O11	70.5 (3)	O22—C27—O21	125.7 (12)
O1—Pb1—O11	131.3 (3)	O22—C27—C22	119.1 (10)
O21—Pb1—N21	65.4 (3)	O21—C27—C22	115.1 (10)
O11^i—Pb1—N21	81.6 (3)	C23—N22—C25	116.5 (11)
O1—Pb1—N21	70.6 (3)	N21—C26—C25	121.9 (11)
O11—Pb1—N21	134.3 (3)	N21—C26—H26	119.0
O21—Pb1—N11	78.0 (3)	C25—C26—H26	119.0
O11^i—Pb1—N11	129.8 (3)	C12—N11—C16	117.4 (10)
O1—Pb1—N11	72.0 (3)	C12—N11—Pb1	116.4 (6)
O11—Pb1—N11	60.1 (3)	C16—N11—Pb1	125.8 (8)
N21—Pb1—N11	127.6 (3)	N11—C16—C15	120.5 (11)
O21—Pb1—O22^ii	149.2 (3)	N11—C16—H16	119.8
O11^i—Pb1—O22^ii	102.5 (3)	C15—C16—H16	119.8
O1—Pb1—O22^ii	74.3 (3)	N22—C23—C22	121.0 (13)
O11—Pb1—O22^ii	135.4 (3)	N22—C23—H23	119.5
N21—Pb1—O22^ii	84.8 (3)	C22—C23—H23	119.5
N11—Pb1—O22^ii	118.2 (3)	Pb1—O1—H1	137 (10)
C17—O11—Pb1^i	119.3 (6)	Pb1—O1—H2	113 (9)
C17—O11—Pb1	125.8 (6)	H1—O1—H2	106 (3)
Pb1^i—O11—Pb1	109.5 (3)	O12—C17—O11	124.8 (9)
N21—C22—C23	123.2 (11)	O12—C17—C12	118.7 (9)
N21—C22—C27	116.9 (9)	O11—C17—C12	116.5 (8)
C23—C22—C27	119.9 (11)	C15—N12—C13	116.5 (10)
C27—O21—Pb1	126.1 (7)	N12—C15—C16	122.9 (11)
C22—N21—C26	115.8 (10)	N12—C15—H15	118.5
C22—N21—Pb1	116.0 (6)	C16—C15—H15	118.5
C26—N21—Pb1	127.7 (8)	N22—C25—C26	121.5 (11)
N11—C12—C13	121.9 (10)	N22—C25—H25	119.2
N11—C12—C17	117.9 (8)	C26—C25—H25	119.2

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H2···O21^ii	0.84 (2)	2.17 (5)	2.837 (13)	136 (7)
O1—H1···O22^iii	0.84 (2)	2.29 (5)	2.969 (15)	139 (7)
O1—H1···O12^ii	0.84 (2)	2.49 (7)	3.056 (13)	126 (7)

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