Buy article online - an online subscription or single-article purchase is required to access this article.
Download citation
Download citation
link to html
The crystal structure of the title compound, poly[di-[mu]4-formato-lead(II)], [Pb(HCOO)2]n, has been re-investigated. It consists of a three-dimensional polymeric network of Pb2+ nodes connected by bridging formate anions. Despite having been described previously, the structural information available so far [Harrison & Steel (1982). J. Organomet. Chem. 239, 105-113] is incomplete and the reported Pnma space group is incorrect. In this work, the space-group assignment to P212121 is discussed and a complete description of the structural features of lead(II) formate is provided.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S010827011204913X/sk3452sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S010827011204913X/sk3452Isup2.hkl
Contains datablock I

CCDC reference: 925259

Comment top

We have synthesized several lead carboxylates in order to characterize their structures, as part of a larger research project aiming to study the degradation phenomena of ancient pieces of art, and in particular paintings. Indeed, the formation and slow crystal growth of lead carboxylates within paint layers can eventually cause the formation of cracks and fractures that irreversibly damage the artifacts (Higgitt et al., 2003; Niklasson et al., 2004; Plater et al. 2003; Schieweck et al., 2009; Tétreault et al., 1998, 2003). Among the whole carboxylate homologous family, the simplest compound, lead(II) formate, Pb(HCOO)2, (I), has been widely investigated and characterized in the past, as witnessed by over 100 bibliographic references addressing its preparation and formation, thermodynamic properties and applications. Nevertheless, the published structural characterization is very old and incomplete. The first published crystal structure is probably that reported in 1932 by Halla & Zimmermann (1932), but the accessible information from the Cambridge Structural Database (CSD, Version?; Allen, 2002) is limited to just one entry, by Harrison & Steel (1982) (CSD refcode BIYLAW), which is incomplete since no atomic coordinates were provided in the paper and, moreover, it claims a different space group from the previous literature.

As a first and most relevant result of this study, our diffraction data clearly indicate the space group P212121, instead of the space group Pnma reported by Harrison & Steel (1982). The unit-cell dimensions are identical. Both space groups (P212121 and Pnma) possess 21 screw axes along the three crystallographic directions, hence showing systematic extinctions for odd index values in the reflections h00, 0k0 and 00l. Yet the additional conditions k+l = 2n for 0kl reflections, and even h values for hk0 reflections, must be fulfilled in the space group Pnma (Hahn, 2002). It is interesting to note that the Pb2+ sites in the structure of (I) obey the Pnma symmetry closely, although it is broken by the formate anions which conform only with the P212121 symmetry. Due to the dominating scattering power of Pb atoms, some reflections appear to be pseudo-extinct, and they were probably misinterpreted by Harrison & Steel (1982) as corresponding to the presence of additional n- and a-glide planes.

In the present analysis, E statistics on the collected data clearly suggested the absence of an inversion center, with a Sheldrick criterion |E2 - 1| = 0.666 (where E are the normalized structure factors, and 0.968 and 0.736 are the ideal values for a centric and an acentric random distribution, respectively) (Wilson, 1949; Sheldrick, 1998). Moreover, an attempt to solve the structure in space group Pnma produced an inadequate model where some atoms assumed forbidden bonding geometry, with inconsistently short distances between symmetry-equivalent atoms, and large and highly distorted displacement ellipsoids or, in some cases, nonpositive definite anisotropic displacement parameters. On the other hand, structure solution and refinement in P212121 were carried out successfully, leading to a final R1 value of 0.0354, which represents a better result than previous work [i.e. 0.0549 in Harrison & Steel (1982)]. Finally, the selected space group has been post-validated using PLATON (Spek, 2009), which did not suggest any other possible space group. The P212121 symmetry for lead formate is not actually completely new, as it had been suggested very early on by Sugawara et al. (1951). However, based on the atomic coordinates published by Sugawara et al. (1951), we obtained a structure totally inconsistent with the well known geometries of formate groups, being strongly distorted and characterized by unrealistic bond lengths.

Part of the crystal structure of (I) is shown in Fig. 3 and projections of unit-cell content are shown in Fig. 4. Selected geometric data are given in Table 1. The current structure in space group P212121 qualitatively resembles that reported by Harrison & Steel (1982) in terms of the general structural characteristics (i.e. the Pb coordination and the general behaviour of the Pb—O bonds). Our investigation confirms that (I) is a three-dimensional coordination polymer, where the formate anions act as tetradentate bridging groups between adjacent PbII cations, which exhibit a distorted eightfold coordination (Figs. 1 and 2). As observed previously (Harrison & Steel, 1982), the PbII cation forms three shorter and five longer bonds to the O atoms. Quantitatively, the bond lengths in both structures differ, as expected in view of the incorrect space-group assignment. The correctness of the currently assigned space group is clearly indicated by the value of the Flack (1983) parameter [x = 0.03 (4)].

Related literature top

For related literature, see: Allen (2002); Arnaiz et al. (2010); Flack (1983); Hahn (2002); Halla & Zimmermann (1932); Harrison & Steel (1982); Higgitt et al. (2003); Niklasson et al. (2004); Plater et al. (2003); Schieweck et al. (2009); Sheldrick (1998); Spek (2009); Sugawara et al. (1951); Tétreault et al. (1998, 2003); Wilson (1949); Zhang et al. (2007).

Experimental top

The title compound can be easily obtained according to literature methods [see, for example, Zhang et al. (2007) and Arnaiz et al. (2010)]. In the present work, crystals of lead formate were obtained by fractional crystallization from a formic-acid-containing solution of lead palmitate. A few drops of formic acid were added to a saturated solution of lead palmitate, Pb[(OCO(CH2)14CH3]2, in MeOH. The mixture was refluxed for a few minutes and the white insoluble solid which formed was filtered off. The colourless saturated solution was collected in a small vial and crystallized by the diffusion method: the vial was placed in a screw-capped glass test tube containing a few millilitres of Et2O and left at room temperature for several days. A small number of white lead formate single crystals were collected from the solution.

Refinement top

H atoms were placed in idealized positions and refined as riding, with C—H = 0.93Å and Uiso(H) = 1.2Ueq(C). PLATON (Spek, 2009) was used for analysing and validating the symmetry, while the Flack parameter (Flack, 1983) was used to determine the absolute structure.

Computing details top

Data collection: CrysAlis CCD (Oxford Diffraction, 2005); cell refinement: CrysAlis RED (Oxford Diffraction, 2005); data reduction: CrysAlis RED (Oxford Diffraction, 2005); program(s) used to solve structure: WinGX (Farrugia, 1999) and SUPERFLIP (Palatinus & Chapuis, 2007); program(s) used to refine structure: WinGX (Farrugia, 1999) and SHELXL97 (Sheldrick, 2008); molecular graphics: Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010).

Figures top
Fig. 1. The first coordination sphere of O atoms around the central Pb2+ cation, showing the atomic labelling scheme and relevant bond distances in Å. [Symmetry codes: (i) x + 1/2, -y + 1/2, -z + 2; (ii) -x + 2, y + 1/2, -z + 3/2; (iii) -x + 2, y - 1/2, -z + 3/2.]

Fig. 2. The distorted eightfold coordination polyhedron around the Pb2+ cation. [Symmetry codes: (i) x + 1/2, -y + 1/2, -z + 2; (ii) -x + 2, y + 1/2, -z + 3/2; (iii) -x + 2, y - 1/2, -z + 3/2.]

Fig. 3. The structure of (I), with displacement ellipsoids drawn at the 50% probability level, and a polymeric expansion showing the two µ4-bridging formate groups. [Symmetry codes: (i) x + 1/2, -y + 1/2, -z + 2; (ii) -x + 2, y + 1/2, -z + 3/2; (iii) -x + 2, y - 1/2, -z + 3/2; (iv) x - 1, y, z; (v) x + 1/2, -y + 1/2, -z + 1; (vi) x - 1/2, -y + 1/2, -z + 2; (vii) -x + 5/2, -y + 1, z - 1/2; (viii) -x + 1, y - 1/2, -z + 3/2.]

Fig. 4. The crystal packing of (I), viewed down (from left to right) the a, b and c axes.
Poly[di-µ4-formato-lead(II)] top
Crystal data top
[Pb(HCO2)2]Dx = 4.657 Mg m3
Mr = 297.24Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121Cell parameters from 2211 reflections
a = 6.5227 (8) Åθ = 3.6–43.1°
b = 7.4153 (8) ŵ = 39.68 mm1
c = 8.7646 (10) ÅT = 297 K
V = 423.92 (8) Å3Block, colourless
Z = 40.15 × 0.09 × 0.08 mm
F(000) = 512
Data collection top
Stoe STADI IV
diffractometer equipped with an Oxford Sapphire I CCD area detector
1026 independent reflections
Radiation source: fine-focus sealed tube867 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.086
ϕ and ω scansθmax = 28.0°, θmin = 3.6°
Absorption correction: numerical
[X-RED (Stoe & Cie, 1999) and X-SHAPE (Stoe & Cie, 2001)]
h = 87
Tmin = 0.011, Tmax = 0.058k = 98
3678 measured reflectionsl = 1111
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)] = 0.035H-atom parameters constrained
wR(F2) = 0.079 w = 1/[σ2(Fo2) + (0.0321P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.00(Δ/σ)max < 0.001
1026 reflectionsΔρmax = 1.30 e Å3
65 parametersΔρmin = 1.94 e Å3
0 restraintsAbsolute structure: Flack (1983), with 404 Bijvoet pairs
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.03 (4)
Crystal data top
[Pb(HCO2)2]V = 423.92 (8) Å3
Mr = 297.24Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 6.5227 (8) ŵ = 39.68 mm1
b = 7.4153 (8) ÅT = 297 K
c = 8.7646 (10) Å0.15 × 0.09 × 0.08 mm
Data collection top
Stoe STADI IV
diffractometer equipped with an Oxford Sapphire I CCD area detector
1026 independent reflections
Absorption correction: numerical
[X-RED (Stoe & Cie, 1999) and X-SHAPE (Stoe & Cie, 2001)]
867 reflections with I > 2σ(I)
Tmin = 0.011, Tmax = 0.058Rint = 0.086
3678 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.035H-atom parameters constrained
wR(F2) = 0.079Δρmax = 1.30 e Å3
S = 1.00Δρmin = 1.94 e Å3
1026 reflectionsAbsolute structure: Flack (1983), with 404 Bijvoet pairs
65 parametersAbsolute structure parameter: 0.03 (4)
0 restraints
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.

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 (Å2) top
xyzUiso*/Ueq
Pb10.92919 (8)0.25999 (6)0.83375 (7)0.02668 (16)
O10.5193 (15)0.2353 (14)0.8629 (12)0.033 (2)
O21.2416 (17)0.0663 (13)0.8153 (18)0.041 (3)
O30.8524 (18)0.0793 (14)0.5921 (13)0.030 (2)
O41.144 (2)0.4259 (13)0.6077 (13)0.035 (3)
C10.421 (3)0.1095 (17)0.8001 (14)0.022 (3)
C21.247 (2)0.349 (2)0.5066 (19)0.028 (3)
H10.49570.03910.73220.027*
H21.24360.22340.50620.034*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Pb10.0267 (2)0.0235 (2)0.0298 (3)0.0009 (3)0.0014 (2)0.0018 (3)
C10.030 (7)0.030 (6)0.008 (6)0.010 (7)0.002 (6)0.001 (4)
O10.028 (5)0.028 (5)0.044 (6)0.001 (5)0.000 (4)0.011 (6)
O40.043 (7)0.028 (5)0.034 (6)0.004 (5)0.018 (5)0.011 (5)
O20.031 (7)0.026 (5)0.067 (9)0.004 (4)0.013 (6)0.004 (6)
C20.028 (7)0.033 (8)0.024 (8)0.003 (6)0.001 (6)0.001 (7)
O30.024 (6)0.032 (5)0.033 (6)0.002 (4)0.007 (5)0.001 (5)
Geometric parameters (Å, º) top
Pb1—O12.692 (10)Pb1—O4iii2.575 (10)
Pb1—O22.498 (11)C1—O11.259 (17)
Pb1—O32.556 (11)C1—O2iv1.22 (2)
Pb1—O42.722 (11)C1—H10.9300
Pb1—O1i2.723 (10)C2—O3v1.226 (19)
Pb1—O2ii2.848 (12)C2—O41.249 (19)
Pb1—O3ii2.839 (10)C2—H20.9300
O2—Pb1—O378.8 (4)O2—Pb1—O2ii138.42 (19)
O2—Pb1—O4iii67.2 (4)O3—Pb1—O2ii87.8 (4)
O3—Pb1—O4iii67.9 (4)O4iii—Pb1—O2ii141.8 (4)
O2—Pb1—O1141.0 (3)O1—Pb1—O2ii73.1 (3)
O3—Pb1—O181.3 (3)O4—Pb1—O2ii60.5 (4)
O4iii—Pb1—O174.4 (4)O1i—Pb1—O2ii121.5 (4)
O2—Pb1—O478.0 (4)O3ii—Pb1—O2ii68.7 (3)
O3—Pb1—O474.6 (4)O2iv—C1—O1129.5 (14)
O4iii—Pb1—O4132.5 (3)O2iv—C1—H1115.3
O1—Pb1—O4127.7 (4)O1—C1—H1115.3
O2—Pb1—O1i83.9 (4)C1—O1—Pb1121.0 (10)
O3—Pb1—O1i149.1 (3)C1—O1—Pb1vi109.0 (9)
O4iii—Pb1—O1i81.8 (4)Pb1—O1—Pb1vi107.8 (3)
O1—Pb1—O1i97.0 (3)C2—O4—Pb1ii133.0 (10)
O4—Pb1—O1i126.4 (3)C2—O4—Pb1125.9 (9)
O2—Pb1—O3ii94.9 (3)Pb1ii—O4—Pb1101.2 (3)
O3—Pb1—O3ii136.5 (2)C1vii—O2—Pb1129.7 (9)
O4iii—Pb1—O3ii148.3 (4)O3v—C2—O4127.0 (14)
O1—Pb1—O3ii122.2 (3)O3v—C2—H2116.5
O4—Pb1—O3ii62.0 (3)O4—C2—H2116.5
O1i—Pb1—O3ii70.0 (3)C2viii—O3—Pb1117.8 (10)
Symmetry codes: (i) x+1/2, y+1/2, z+2; (ii) x+2, y+1/2, z+3/2; (iii) x+2, y1/2, z+3/2; (iv) x1, y, z; (v) x+1/2, y+1/2, z+1; (vi) x1/2, y+1/2, z+2; (vii) x+1, y, z; (viii) x1/2, y+1/2, z+1.

Experimental details

Crystal data
Chemical formula[Pb(HCO2)2]
Mr297.24
Crystal system, space groupOrthorhombic, P212121
Temperature (K)297
a, b, c (Å)6.5227 (8), 7.4153 (8), 8.7646 (10)
V3)423.92 (8)
Z4
Radiation typeMo Kα
µ (mm1)39.68
Crystal size (mm)0.15 × 0.09 × 0.08
Data collection
DiffractometerStoe STADI IV
diffractometer equipped with an Oxford Sapphire I CCD area detector
Absorption correctionNumerical
[X-RED (Stoe & Cie, 1999) and X-SHAPE (Stoe & Cie, 2001)]
Tmin, Tmax0.011, 0.058
No. of measured, independent and
observed [I > 2σ(I)] reflections
3678, 1026, 867
Rint0.086
(sin θ/λ)max1)0.660
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.035, 0.079, 1.00
No. of reflections1026
No. of parameters65
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)1.30, 1.94
Absolute structureFlack (1983), with 404 Bijvoet pairs
Absolute structure parameter0.03 (4)

Computer programs: CrysAlis CCD (Oxford Diffraction, 2005), CrysAlis RED (Oxford Diffraction, 2005), WinGX (Farrugia, 1999) and SUPERFLIP (Palatinus & Chapuis, 2007), WinGX (Farrugia, 1999) and SHELXL97 (Sheldrick, 2008), Mercury (Macrae et al., 2008), publCIF (Westrip, 2010).

Selected geometric parameters (Å, º) top
Pb1—O12.692 (10)Pb1—O3ii2.839 (10)
Pb1—O22.498 (11)Pb1—O4iii2.575 (10)
Pb1—O32.556 (11)C1—O11.259 (17)
Pb1—O42.722 (11)C1—O2iv1.22 (2)
Pb1—O1i2.723 (10)C2—O3v1.226 (19)
Pb1—O2ii2.848 (12)C2—O41.249 (19)
O2—Pb1—O378.8 (4)O2—Pb1—O3ii94.9 (3)
O2—Pb1—O4iii67.2 (4)O3—Pb1—O3ii136.5 (2)
O3—Pb1—O4iii67.9 (4)O4iii—Pb1—O3ii148.3 (4)
O2—Pb1—O1141.0 (3)O1—Pb1—O3ii122.2 (3)
O3—Pb1—O181.3 (3)O4—Pb1—O3ii62.0 (3)
O4iii—Pb1—O174.4 (4)O1i—Pb1—O3ii70.0 (3)
O2—Pb1—O478.0 (4)O2—Pb1—O2ii138.42 (19)
O3—Pb1—O474.6 (4)O3—Pb1—O2ii87.8 (4)
O4iii—Pb1—O4132.5 (3)O4iii—Pb1—O2ii141.8 (4)
O1—Pb1—O4127.7 (4)O1—Pb1—O2ii73.1 (3)
O2—Pb1—O1i83.9 (4)O4—Pb1—O2ii60.5 (4)
O3—Pb1—O1i149.1 (3)O1i—Pb1—O2ii121.5 (4)
O4iii—Pb1—O1i81.8 (4)O3ii—Pb1—O2ii68.7 (3)
O1—Pb1—O1i97.0 (3)O2iv—C1—O1129.5 (14)
O4—Pb1—O1i126.4 (3)O3v—C2—O4127.0 (14)
Symmetry codes: (i) x+1/2, y+1/2, z+2; (ii) x+2, y+1/2, z+3/2; (iii) x+2, y1/2, z+3/2; (iv) x1, y, z; (v) x+1/2, y+1/2, z+1.
 

Subscribe to Acta Crystallographica Section C: Structural Chemistry

The full text of this article is available to subscribers to the journal.

If you have already registered and are using a computer listed in your registration details, please email support@iucr.org for assistance.

Buy online

You may purchase this article in PDF and/or HTML formats. For purchasers in the European Community who do not have a VAT number, VAT will be added at the local rate. Payments to the IUCr are handled by WorldPay, who will accept payment by credit card in several currencies. To purchase the article, please complete the form below (fields marked * are required), and then click on `Continue'.
E-mail address* 
Repeat e-mail address* 
(for error checking) 

Format*   PDF (US $40)
   HTML (US $40)
   PDF+HTML (US $50)
In order for VAT to be shown for your country javascript needs to be enabled.

VAT number 
(non-UK EC countries only) 
Country* 
 

Terms and conditions of use
Contact us

Follow Acta Cryst. C
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds