Dicobalt(II) lead(II) hydrogenphos­phate(V) phos­phate(V) hydroxide monohydrate

The title compound, Co₂Pb(HPO₄)(PO₄)OH·H₂O, which was synthesized under hydro­thermal conditions, crystallizes in a new structure type. Except for two O atoms in general positions and two Co atoms on centres of symmetry, all other atoms in the asymmetric unit (1 Pb, 2 Co, 2 P, 8 O and 4 H) are located on mirror planes. The structure is built up from two infinite linear chains, viz. ¹_∞[CoO_2/1(H₂O)_2/2O_2/2] and ¹_∞[CoO_2/1(OH)_2/2O_2/2], of edge-sharing CoO₆ octa­hedra running along [010]. Adjacent chains are linked to each other through PO₄ and PO₃(OH) tetra­hedra, leading to the formation of layers parallel to (100). The three-dimensional framework is formed by stacking along [100] of adjacent layers that are held together by distorted PbO₈ polyhedra. Hydrogen bonds of the type O—H⋯O involving the water mol­ecule are very strong, while those O atoms involving the OH groups form weak bifurcated and trifurcated hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](P-O) = 0.003 Å
• R factor = 0.016
• wR factor = 0.039
• Data-to-parameter ratio = 18.6

checkCIF/PLATON results

No syntax errors found





Alert level A
PLAT772_ALERT_2_A Suspect O-H Bond in CIF:   O7     --  H8B     ..       1.65 Ang.
PLAT900_ALERT_1_A No Matching Reflection File Found ..............          !

Alert level C
PLAT416_ALERT_2_C Short Intra D-H..H-D       H7     ..  H8B     ..       1.96 Ang.
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          1
              Co2 H4 O10 P2 Pb
PLAT924_ALERT_1_C The Reported and Calculated Rho(min) Differ by .       1.49 eA-3
PLAT925_ALERT_1_C The Reported and Calculated Rho(max) Differ by .       1.76 eA-3

Alert level G
PLAT004_ALERT_5_G Info: Polymeric Structure Found with Dimension .          3
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT007_ALERT_5_G Note: Number of Unrefined D-H Atoms ............          4
PLAT153_ALERT_1_G The su's on the Cell Axes   are Equal ..........    0.00010 Ang.
PLAT232_ALERT_2_G Hirshfeld Test Diff (M-X)  Pb1    --  O3      ..        8.6 su

   2 ALERT level A = Most likely a serious problem - resolve or explain
   0 ALERT level B = A potentially serious problem, consider carefully
   4 ALERT level C = Check. Ensure it is not caused by an omission or oversight
   5 ALERT level G = General information/check it is not something unexpected

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

---

S1. Comment

Metal based phosphates are of great interest owing to either their remarkable diversity of structures or their properties and applications in catalysis, as ion-exchangers (Cheetham et al., 1999; Clearfield, 1988) or as positive electrode materials in lithium- and sodium-containing batteries (Trad et al., 2010)). Mainly, our focus of investigation is focused on orthophosphates with (mixed) divalent metals with general formula (M,M')₃(PO₄)₂^.nH₂O (Assani et al., 2010). It has been pointed out that the structural diversity of this family of compounds depends on the size difference of the divalent cations (Effenberger, 1999) and on the degree of hydratation (Yakubovich et al., 2001; Lee et al., 2008. The highest water content known up to date is realised for Mg₃(PO₄)₂^.22H₂O (Britvin et al., 2002). In this work, a new dicobalt lead phosphate(V)] with formula Co₂Pb(HPO₄)(PO₄)OH^.H₂O, was hydrothermally synthesized and structurally characterized.

A search in the ICSD (Belsky et al., 2002) reveals that the crystal structure of this phosphate represents a new structure type. A plot of the crystal structure illustrating the most important coordination polyhedra and their mutual connections is represented in Fig. 1. All atoms are in special positions, except two oxygen atoms (O3,O6) in general position of the P2₁/m space group. The crystal structure is built up from three different types of polyhedra more or less distorted, viz. two PbO₈ polyhedra (m symmetry), PO₄ and PO₃(OH) tetrahedra (both with m symmetry) and two CoO₆ octahedra (both with 1 symmetry). The CoO₆ octahedra share edges and form ¹_∞[Co(1)O_2/1(H₂O)_2/2O_2/2] and ¹_∞[Co(2)O_2/1(OH)_2/2O_2/2] chains running parallel to [010], as shown in Fig. 2. Adjacent chains are connected by PO₄ and HPO₄ tetrahedra via vertices, leading to the formation of layers parallel to (100). These layers are in turn linked by sheets of distorted PbO₈ polyhedra as also shown in Fig.2.

Bond valence sum calculations (Brown & Altermatt, 1985) for Pb1²⁺, Co1²⁺, Co2²⁺, P1⁵⁺ and P2⁵⁺ ions are as expected, viz. 1.92, 2.03, 1.93, 5.05 and 5.05 valence units, respectively. The values of the bond valence sums calculated for the oxygen atoms show low values for O2, O7 and O8 when the contribution of H atoms are not considered (i.e. 1.23, 0.88 and 0.75 valence units, respectively). Hence these O atoms are associated with protons and are involved in O—H···O hydrogen bonding (Table 1). H atoms of the water molecule form very strong hydrogen bonds, especially O8–H8B···O7 with an D···A distance less than 2.5 Å. The H atom of the OH^- group (O7) and the hydrogenphosphate group (O2) form weak bifurcated (O2) and trifurcated (O7) hydrogen bonds (Fig. 2, Table 1).

Related literature

For catalytic properties of phosphates, see: Cheetham et al. (1999); Clearfield (1988); Trad et al. (2010). For compounds with related structures, see: Yakubovich et al. (2001); Lee et al. (2008); Effenberger (1999); Britvin et al. (2002); Assani et al. (2010). For bond-valence analysis, see: Brown & Altermatt (1985). For background to the Inorganic Crystal Structure Database (ICSD), see: Belsky et al. (2002).

S2. Experimental

The title compound, Co₂Pb(HPO₄)(PO₄)OH^.H₂O, was obtained from the hydrothermal treatment of a reaction mixture of Pb(NO₃)₂, metallic cobalt and 85_wt% phosphoric acid in the molar ratio Pb:Co:P = 1:3:3. The hydrothermal reaction was conducted in a 23 ml Teflon-lined autoclave under autogeneous pressure at 473 K for three days. The product was filtered off, washed with deionized water and air dried. The resulting product consists of pink crystals besides some pink powder.

S3. Refinement

The O-bound H atoms were initially located in a difference map and refined with O—H distance restraints of 0.86 (1). In a the last cycle they were refined in the riding model approximation with U_iso(H) set to 1.2U_eq(O). The highest remaining positive and negative electron densities observed in the final Fourier map are 0.76 Å and 0.78 Å, respectively, from Pb1.

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia,1997) and DIAMOND (Brandenburg, 2006); software used to prepare material for publication: PLATON (Spek, 2009) and publCIF (Westrip, 2010).

Figures

Fig. 1. A partial three-dimensional plot of the crystal structure of Co2Pb(HPO4)(PO4)OH^.H2O. Displacement ellipsoids are drawn at the 50% probability level. Symmetry codes:(i) -x, y + 1/2, -z; (ii) -x, -y, -z; (iii) x, -y + 1/2, z; (iv) -x, -y, -z + 1; (v) -x - 1, -y, -z; (vi) x + 1, y, z; (vii) -x, -y + 1, -z + 1; (viii) x + 1, -y + 1/2, z + 1; (ix) x + 1, y + 1, z; (x) x, -y - 1/2, z; (xi) x - 1, y - 1, z; (xii) -x, y - 1/2, -z + 1; (xiii) -x - 1, y + 1/2, -z;

Fig. 2. A three-dimensional polyhedral view of the crystal structure of Co2Pb(HPO4)(PO4)OH^.H2O, showing the stacking of layers along the [100] axis and the hydrogen bonding scheme (dashed lines).

Dicobalt(II) lead(II) hydrogenphosphate(V) phosphate(V) hydroxide monohydrate

Crystal data

Co2Pb(HPO4)(PO4)OH·H2O	F(000) = 500
Mr = 551.02	Dx = 4.807 Mg m^−3
Monoclinic, P21/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yb	Cell parameters from 1601 reflections
a = 7.4299 (1) Å	θ = 2.5–33.5°
b = 6.2949 (1) Å	µ = 26.83 mm^−1
c = 8.9057 (1) Å	T = 296 K
β = 113.936 (1)°	Prism, pink
V = 380.70 (1) Å^3	0.18 × 0.12 × 0.08 mm
Z = 2

Data collection

Bruker X8 APEXII diffractometer	1601 independent reflections
Radiation source: fine-focus sealed tube	1558 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
φ and ω scans	θmax = 33.5°, θmin = 2.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1999)	h = −9→11
Tmin = 0.029, Tmax = 0.117	k = −9→9
8321 measured reflections	l = −13→13

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.016	H-atom parameters constrained
wR(F^2) = 0.039	w = 1/[σ^2(Fo^2) + (0.0153P)^2 + 0.885P] where P = (Fo^2 + 2Fc^2)/3
S = 1.11	(Δ/σ)max = 0.001
1601 reflections	Δρmax = 1.76 e Å^−3
86 parameters	Δρmin = −1.49 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: 0.0061 (3)

Special details

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 > 2σ(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	0.006473 (17)	0.2500	0.232477 (15)	0.01414 (5)
Co1	−0.5000	0.0000	0.0000	0.00717 (8)
Co2	0.5000	0.5000	0.5000	0.00859 (8)
P1	−0.22391 (12)	−0.2500	0.32517 (9)	0.00646 (13)
P2	−0.21025 (11)	0.2500	−0.16270 (9)	0.00642 (13)
O1	−0.3205 (3)	−0.2500	0.4478 (3)	0.0088 (4)
O2	0.0058 (4)	−0.2500	0.4403 (3)	0.0145 (5)
H2	0.0642	−0.2500	0.3744	0.017*
O3	−0.2656 (2)	−0.0469 (3)	0.2228 (2)	0.0102 (3)
O4	0.0041 (4)	0.2500	−0.0355 (3)	0.0160 (5)
O5	−0.3411 (3)	0.2500	−0.0638 (3)	0.0096 (4)
O6	−0.2489 (3)	0.0525 (3)	−0.2742 (2)	0.0135 (3)
O7	−0.4341 (4)	0.2500	0.3936 (3)	0.0100 (4)
H7	−0.3197	0.2500	0.3910	0.012*
O8	−0.6059 (3)	0.2500	0.0885 (3)	0.0086 (4)
H8A	−0.7322	0.2500	0.0522	0.010*
H8B	−0.5660	0.2500	0.1937	0.010*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pb1	0.01157 (7)	0.02066 (8)	0.01059 (7)	0.000	0.00492 (4)	0.000
Co1	0.00890 (17)	0.00553 (19)	0.00703 (16)	0.00041 (14)	0.00319 (14)	0.00011 (13)
Co2	0.01066 (18)	0.0070 (2)	0.00765 (16)	−0.00114 (14)	0.00323 (14)	−0.00053 (13)
P1	0.0091 (3)	0.0062 (3)	0.0048 (3)	0.000	0.0035 (3)	0.000
P2	0.0068 (3)	0.0075 (3)	0.0052 (3)	0.000	0.0028 (2)	0.000
O1	0.0122 (10)	0.0082 (10)	0.0084 (9)	0.000	0.0067 (8)	0.000
O2	0.0080 (10)	0.0233 (14)	0.0106 (10)	0.000	0.0022 (8)	0.000
O3	0.0119 (7)	0.0090 (7)	0.0083 (6)	−0.0011 (6)	0.0027 (5)	0.0010 (6)
O4	0.0073 (10)	0.0287 (15)	0.0101 (10)	0.000	0.0016 (8)	0.000
O5	0.0110 (10)	0.0101 (10)	0.0105 (9)	0.000	0.0071 (8)	0.000
O6	0.0156 (8)	0.0124 (8)	0.0088 (6)	0.0056 (7)	0.0010 (6)	−0.0041 (6)
O7	0.0113 (10)	0.0130 (11)	0.0074 (9)	0.000	0.0055 (8)	0.000
O8	0.0097 (9)	0.0100 (10)	0.0072 (9)	0.000	0.0047 (8)	0.000

Geometric parameters (Å, º)

Pb1—O4	2.380 (3)	P1—O1	1.531 (2)
Pb1—O6^i	2.5429 (18)	P1—O2	1.595 (3)
Pb1—O6^ii	2.5429 (18)	P2—O4	1.535 (3)
Pb1—O3	2.7284 (17)	P2—O6	1.5432 (18)
Pb1—O3^iii	2.7284 (17)	P2—O6^iii	1.5432 (18)
Pb1—O5	2.846 (2)	P2—O5	1.554 (2)
Pb1—O1^iv	2.857 (2)	O1—Co2^xi	2.2302 (16)
Pb1—O2^iv	2.952 (3)	O1—Co2^xii	2.2302 (16)
Co1—O8	2.0544 (14)	O1—Pb1^iv	2.857 (2)
Co1—O8^v	2.0544 (14)	O2—Pb1^iv	2.952 (3)
Co1—O3^v	2.0624 (16)	O2—H2	0.8600
Co1—O3	2.0624 (16)	O5—Co1^xiii	2.1766 (15)
Co1—O5	2.1766 (15)	O6—Co2^xiv	2.1426 (17)
Co1—O5^v	2.1766 (15)	O6—Pb1^ii	2.5429 (18)
Co2—O7^vi	1.9978 (14)	O7—Co2^xv	1.9978 (14)
Co2—O7^vii	1.9978 (14)	O7—Co2^xii	1.9978 (14)
Co2—O6^i	2.1426 (17)	O7—H7	0.8600
Co2—O6^viii	2.1426 (17)	O7—H8B	1.6474
Co2—O1^ix	2.2302 (16)	O8—Co1^xiii	2.0544 (14)
Co2—O1^iv	2.2302 (16)	O8—H8A	0.8600
P1—O3^x	1.5274 (18)	O8—H8B	0.8600
P1—O3	1.5274 (18)
O4—Pb1—O6^i	82.12 (5)	O3^v—Co1—O5	88.92 (8)
O4—Pb1—O6^ii	82.12 (5)	O3—Co1—O5	91.08 (8)
O6^i—Pb1—O6^ii	97.00 (9)	O8—Co1—O5^v	96.95 (6)
O4—Pb1—O3	105.34 (5)	O8^v—Co1—O5^v	83.05 (6)
O6^i—Pb1—O3	171.63 (5)	O3^v—Co1—O5^v	91.08 (8)
O6^ii—Pb1—O3	87.90 (7)	O3—Co1—O5^v	88.92 (8)
O4—Pb1—O3^iii	105.34 (5)	O5—Co1—O5^v	180.00 (12)
O6^i—Pb1—O3^iii	87.90 (7)	O7^vi—Co2—O7^vii	180.0
O6^ii—Pb1—O3^iii	171.63 (5)	O7^vi—Co2—O6^i	87.93 (9)
O3—Pb1—O3^iii	86.46 (8)	O7^vii—Co2—O6^i	92.07 (9)
O4—Pb1—O5	55.64 (7)	O7^vi—Co2—O6^viii	92.07 (9)
O6^i—Pb1—O5	117.25 (4)	O7^vii—Co2—O6^viii	87.93 (9)
O6^ii—Pb1—O5	117.25 (4)	O6^i—Co2—O6^viii	180.0
O3—Pb1—O5	65.72 (4)	O7^vi—Co2—O1^ix	100.06 (7)
O3^iii—Pb1—O5	65.72 (4)	O7^vii—Co2—O1^ix	79.94 (7)
O4—Pb1—O1^iv	132.09 (7)	O6^i—Co2—O1^ix	93.55 (8)
O6^i—Pb1—O1^iv	67.09 (5)	O6^viii—Co2—O1^ix	86.45 (8)
O6^ii—Pb1—O1^iv	67.09 (5)	O7^vi—Co2—O1^iv	79.94 (7)
O3—Pb1—O1^iv	109.06 (5)	O7^vii—Co2—O1^iv	100.06 (7)
O3^iii—Pb1—O1^iv	109.06 (5)	O6^i—Co2—O1^iv	86.45 (8)
O5—Pb1—O1^iv	172.27 (6)	O6^viii—Co2—O1^iv	93.55 (8)
O4—Pb1—O2^iv	178.00 (7)	O1^ix—Co2—O1^iv	180.0
O6^i—Pb1—O2^iv	99.18 (5)	O3^x—P1—O3	113.68 (14)
O6^ii—Pb1—O2^iv	99.18 (5)	O3^x—P1—O1	112.68 (8)
O3—Pb1—O2^iv	73.26 (5)	O3—P1—O1	112.68 (8)
O3^iii—Pb1—O2^iv	73.26 (5)	O3^x—P1—O2	106.78 (8)
O5—Pb1—O2^iv	122.36 (7)	O3—P1—O2	106.78 (8)
O1^iv—Pb1—O2^iv	49.91 (6)	O1—P1—O2	103.32 (13)
O8—Co1—O8^v	180.00 (11)	O4—P2—O6	109.94 (9)
O8—Co1—O3^v	87.37 (8)	O4—P2—O6^iii	109.94 (9)
O8^v—Co1—O3^v	92.63 (8)	O6—P2—O6^iii	107.30 (15)
O8—Co1—O3	92.63 (8)	O4—P2—O5	106.40 (14)
O8^v—Co1—O3	87.37 (8)	O6—P2—O5	111.63 (9)
O3^v—Co1—O3	180.00 (13)	O6^iii—P2—O5	111.63 (9)
O8—Co1—O5	83.05 (6)	H8A—O8—H8B	104.5
O8^v—Co1—O5	96.95 (6)

Symmetry codes: (i) −x, y+1/2, −z; (ii) −x, −y, −z; (iii) x, −y+1/2, z; (iv) −x, −y, −z+1; (v) −x−1, −y, −z; (vi) x+1, y, z; (vii) −x, −y+1, −z+1; (viii) x+1, −y+1/2, z+1; (ix) x+1, y+1, z; (x) x, −y−1/2, z; (xi) x−1, y−1, z; (xii) −x, y−1/2, −z+1; (xiii) −x−1, y+1/2, −z; (xiv) −x, y−1/2, −z; (xv) x−1, y, z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O6^ii	0.86	2.28	3.027 (3)	145
O2—H2···O6^xiv	0.86	2.28	3.027 (3)	145
O7—H7···O2^iv	0.86	2.20	2.915 (3)	140
O7—H7···O3	0.86	2.53	2.986 (2)	114
O7—H7···O3^iii	0.86	2.53	2.986 (2)	114
O8—H8A···O4^xv	0.86	1.79	2.649 (3)	177
O8—H8B···O7	0.86	1.65	2.489 (3)	165

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