Poly[sodium [μ₄-2-hydroxy­phosphono­acetato(3−)]iron(II)]

The title compound, NaFe[(O₃PCH(OH)CO₂)] or {Na[Fe(C₂H₂O₆P)]}_n, was synthesized under mild hydro­thermal conditions. The Fe^II ion is octa­hedrally coordinated; all O atoms from the 2-hydroxy­phosphono­acetate­(3−) are involved in metal coordination. The overall structure can be described as a three-dimensional open framework with channels running along the a axis and with the charge?compensating Na⁺ cations located inside these channels. This architecture is further stabilized by a number of O—H...O hydrogen bonds involving the protonated hydroxyl O atoms and carboxylate O atoms.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.022
• wR factor = 0.056
• Data-to-parameter ratio = 13.1

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       0.98
PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) .       2.00 Ratio
PLAT779_ALERT_2_C Suspect or Irrelevant (Bond) Angle in CIF ......      43.24 Deg.
              O1   -P1   -NA1     1.555   1.555   1.555
PLAT779_ALERT_2_C Suspect or Irrelevant (Bond) Angle in CIF ......      43.78 Deg.
              O2   -P1   -NA1     1.555   1.555   4.466

Alert level G
PLAT793_ALERT_1_G Check the Absolute Configuration of P1     = ...          R
PLAT793_ALERT_1_G Check the Absolute Configuration of C1     = ...          R
PLAT794_ALERT_5_G Check Predicted Bond Valency for Fe1         (2)       2.01

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

   3 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
   0 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

Metal phosphonates with rich composition and structural diversity have attracted considerable attention during the past few years due to their potential applications in catalysis (Clearfield, 1996), ion exchange (Alberti et al., 1999), proton conductivity (Odobel et al., 2001) and gas and liquid separations (Riou et al., 1998,2000). The strategy of attaching additional functional groups such as amine, hydroxyl and carboxylate groups to the phosphonic acid has proven to be effective for the synthesis of metal phosphonates with open-framework and microporous structures. For example, 2-hydroxyphosphonoacetic acid (H₃L) with functional hydroxyl and carboxylate groups is an interesting ligand for the synthesis of metal phosphonates with open-framework structures, since it can adopt various kinds of coordination modes under different reaction conditions which may result in various interesting structures.

The title compound, (I), has been synthesized by hydrothermal technique, using 2-hydroxyphosphonoacetic acid as ligand. Analysis of the single-crystal data reveals that there are one iron(II) ion, one L^3- [L = O₃PCH(OH)CO₂] ligand, and one Na⁺ ion in the asymmetric unit of (I). Each iron(II) ion is octahedrally coordinated by three phosphonate O atoms from three separate L^3- ligands (Fig 1) [the Fe—O distance range from 2.032 (1) to 2.196 (1) Å], two carboxylate O atoms from two separate L^3- ligands [the Fe—O bond lengths are 2.143 (1) and 2.185 (1) Å] and one hydroxyl O atom [the Fe—O bond length is 2.272 (1) Å]. These values are close to those reported for other analogous six-coordinated iron(II) phosphonates (Fu et al., 2005). As a result, all the O atoms from the L^3- ligand are involved in metal coordination, and act as a monodentate connecting one iron(II) ion. The values of the O—Fe—O angles are in the range 69.39 (5)–171.49 (5)°. The overall structure can be described as a three-dimensional open-framework type with channels running along the a axis (Fig 2).

Related literature

For related literature, see: Alberti et al. (1999); Clearfield (1996); Fu et al. (2005); Odobel et al. (2001); Riou et al. (1998, 2000).

S2. Experimental

A mixture of 0.16 g (0.6 mmol) FeSO₄.7H₂O, 0.5 ml (2.0 mmol) 2-hydroxyphosphonoacetic acid (48.0 wt %) and 0.17 g (4.0 mmol) NaF (as a mineralizer) were dissolved in 10 ml of deionized water, and then 2 mol/L NaOH (aq) was added with stirring to adjust the pH of the mixture. The mixture (pH = 4) was sealed in a 20 ml Teflon-lined stainless steel autoclave, and then heated at 433 K for 72 h. Colorless block crystals were obtained, washed with distilled water, and dried in air at room temperature.

S3. Refinement

H atoms were placed in calculated positions and allaowed to ride, with C—H = 0.93 Å or O—H = and U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: APEX2; data reduction: APEX2; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXTL.

Figures

	Fig. 1. View showing the octahedral coordination of the iron with the atom-labelling scheme. Ellipsoids are drawn at the 50% probability level. H atoms have been omitted for clarity.[Symmetry codes: (i) 1/2 - x, 3/2 - y, 1/2 + z; (ii) -x - 1/2, 3/2 - y, 1 - z; (iii) -x, 1 - y, 1 - z; (iv) x - 1/2, y, 1/2 - z; (v) 1/2 - x, y - 1/2, z].
	Fig. 2. View of the packing of (I) with the unit cell outlined along the a axis, showing the stacking of compound (I). H and Na atoms have been omitted for clarity.

Poly[sodium [µ₄-2-hydroxyphosphonoacetato(3-)]iron(II)]

Crystal data

Na[Fe(C2H2O6P)]	F(000) = 912
Mr = 231.85	Dx = 2.837 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 3081 reflections
a = 10.2676 (8) Å	θ = 3.4–28.9°
b = 9.7330 (8) Å	µ = 3.12 mm^−1
c = 10.8624 (9) Å	T = 295 K
V = 1085.53 (15) Å^3	Block, colourless
Z = 8	0.23 × 0.17 × 0.08 mm

Data collection

Bruker SMART APEXII CCD diffractometer	1309 independent reflections
Radiation source: fine-focus sealed tube	1213 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.022
ω scans	θmax = 28.0°, θmin = 3.4°
Absorption correction: empirical (using intensity measurements) (SADABS; Bruker, 2005)	h = −13→13
Tmin = 0.531, Tmax = 0.795	k = −9→12
6143 measured reflections	l = −14→11

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.022	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.056	H-atom parameters constrained
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0281P)^2 + 1.0108P] where P = (Fo^2 + 2Fc^2)/3
1309 reflections	(Δ/σ)max = 0.001
100 parameters	Δρmax = 0.50 e Å^−3
0 restraints	Δρmin = −0.36 e Å^−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 > 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
Fe1	0.17708 (3)	0.41645 (3)	0.60678 (3)	0.01090 (10)
P1	0.09669 (4)	0.72190 (5)	0.45975 (5)	0.01002 (12)
Na1	0.37599 (8)	0.58426 (8)	0.42567 (8)	0.01915 (19)
O1	0.17072 (14)	0.60193 (14)	0.51501 (14)	0.0155 (3)
O2	−0.05078 (13)	0.71517 (14)	0.47584 (13)	0.0156 (3)
O3	0.14845 (13)	0.86102 (14)	0.50091 (13)	0.0151 (3)
O4	0.26320 (13)	0.72206 (14)	0.26531 (13)	0.0138 (3)
H4	0.2760	0.8109	0.2565	0.017*
O5	0.18556 (13)	0.48131 (14)	0.22376 (14)	0.0162 (3)
O6	−0.02360 (13)	0.51846 (14)	0.26669 (13)	0.0156 (3)
C1	0.12691 (18)	0.70391 (19)	0.29329 (18)	0.0108 (4)
H1	0.0737	0.7693	0.2466	0.013*
C2	0.09253 (18)	0.5568 (2)	0.25833 (18)	0.0120 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Fe1	0.00952 (15)	0.01086 (15)	0.01232 (15)	−0.00084 (9)	−0.00043 (10)	0.00006 (10)
P1	0.0097 (2)	0.0090 (2)	0.0113 (2)	−0.00012 (16)	−0.00040 (17)	−0.00060 (17)
Na1	0.0176 (4)	0.0158 (4)	0.0241 (5)	0.0005 (3)	0.0032 (4)	0.0014 (3)
O1	0.0161 (7)	0.0137 (7)	0.0168 (7)	0.0025 (5)	0.0003 (6)	0.0041 (5)
O2	0.0102 (6)	0.0180 (7)	0.0187 (7)	−0.0002 (5)	0.0005 (5)	−0.0056 (5)
O3	0.0168 (7)	0.0114 (7)	0.0170 (7)	−0.0017 (5)	−0.0040 (6)	−0.0014 (5)
O4	0.0126 (6)	0.0097 (6)	0.0189 (7)	−0.0017 (5)	0.0034 (6)	0.0008 (5)
O5	0.0155 (7)	0.0100 (6)	0.0230 (8)	0.0017 (5)	0.0065 (6)	−0.0006 (5)
O6	0.0117 (6)	0.0155 (7)	0.0196 (7)	−0.0020 (5)	0.0006 (5)	−0.0042 (6)
C1	0.0095 (8)	0.0104 (8)	0.0126 (9)	0.0011 (7)	0.0002 (7)	0.0005 (7)
C2	0.0138 (9)	0.0111 (9)	0.0110 (9)	0.0007 (7)	0.0003 (7)	0.0001 (7)

Geometric parameters (Å, º)

Fe1—O2^i	2.0318 (14)	Na1—C2^vi	3.002 (2)
Fe1—O1	2.0633 (14)	Na1—P1^v	3.2006 (10)
Fe1—O5^ii	2.1434 (14)	Na1—Na1^vii	3.4326 (18)
Fe1—O6^i	2.1849 (14)	Na1—Fe1^viii	3.5065 (10)
Fe1—O3^iii	2.1960 (14)	O2—Fe1^i	2.0318 (14)
Fe1—O4^ii	2.2713 (14)	O2—Na1^iv	2.3497 (16)
Fe1—Na1	3.2725 (9)	O3—Fe1^ix	2.1960 (14)
Fe1—Na1^ii	3.5065 (10)	O3—Na1^ix	2.3349 (16)
P1—O1	1.5171 (14)	O3—Na1^iv	2.9574 (17)
P1—O3	1.5218 (14)	O4—C1	1.443 (2)
P1—O2	1.5256 (14)	O4—Fe1^viii	2.2713 (14)
P1—C1	1.843 (2)	O4—H4	0.8797
P1—Na1	3.1868 (10)	O5—C2	1.262 (2)
P1—Na1^iv	3.2006 (10)	O5—Fe1^viii	2.1434 (14)
Na1—O1	2.3267 (17)	O6—C2	1.253 (2)
Na1—O3^iii	2.3349 (16)	O6—Fe1^i	2.1849 (14)
Na1—O2^v	2.3497 (16)	O6—Na1^x	2.4164 (17)
Na1—O6^vi	2.4164 (17)	C1—C2	1.523 (3)
Na1—O4	2.4848 (16)	C1—H1	0.9800
Na1—O3^v	2.9574 (17)	C2—Na1^x	3.002 (2)
O2^i—Fe1—O1	108.55 (6)	O3^iii—Na1—P1^v	119.24 (5)
O2^i—Fe1—O5^ii	167.05 (6)	O2^v—Na1—P1^v	26.70 (3)
O1—Fe1—O5^ii	84.32 (6)	O6^vi—Na1—P1^v	100.98 (4)
O2^i—Fe1—O6^i	90.02 (5)	O4—Na1—P1^v	106.52 (4)
O1—Fe1—O6^i	91.57 (6)	O3^v—Na1—P1^v	28.26 (3)
O5^ii—Fe1—O6^i	88.11 (5)	C2^vi—Na1—P1^v	77.70 (4)
O2^i—Fe1—O3^iii	97.73 (5)	P1—Na1—P1^v	110.13 (2)
O1—Fe1—O3^iii	89.30 (5)	O1—Na1—Fe1	38.81 (4)
O5^ii—Fe1—O3^iii	83.55 (5)	O3^iii—Na1—Fe1	42.10 (4)
O6^i—Fe1—O3^iii	171.49 (5)	O2^v—Na1—Fe1	109.92 (5)
O2^i—Fe1—O4^ii	97.64 (5)	O6^vi—Na1—Fe1	130.83 (5)
O1—Fe1—O4^ii	153.40 (6)	O4—Na1—Fe1	113.58 (4)
O5^ii—Fe1—O4^ii	69.42 (5)	O3^v—Na1—Fe1	121.21 (4)
O6^i—Fe1—O4^ii	83.68 (5)	C2^vi—Na1—Fe1	144.90 (5)
O3^iii—Fe1—O4^ii	91.78 (5)	P1—Na1—Fe1	65.06 (2)
O2^i—Fe1—Na1	116.58 (5)	P1^v—Na1—Fe1	120.15 (3)
O1—Fe1—Na1	44.98 (4)	O1—Na1—Na1^vii	120.74 (6)
O5^ii—Fe1—Na1	73.38 (4)	O3^iii—Na1—Na1^vii	58.02 (4)
O6^i—Fe1—Na1	133.12 (4)	O2^v—Na1—Na1^vii	86.87 (5)
O3^iii—Fe1—Na1	45.47 (4)	O6^vi—Na1—Na1^vii	87.91 (5)
O4^ii—Fe1—Na1	125.70 (4)	O4—Na1—Na1^vii	158.98 (6)
O2^i—Fe1—Na1^ii	109.63 (4)	O3^v—Na1—Na1^vii	42.05 (3)
O1—Fe1—Na1^ii	118.30 (5)	C2^vi—Na1—Na1^vii	73.81 (5)
O5^ii—Fe1—Na1^ii	61.15 (4)	P1—Na1—Na1^vii	144.47 (5)
O6^i—Fe1—Na1^ii	42.87 (4)	P1^v—Na1—Na1^vii	64.75 (3)
O3^iii—Fe1—Na1^ii	130.06 (4)	Fe1—Na1—Na1^vii	86.66 (3)
O4^ii—Fe1—Na1^ii	44.91 (4)	O1—Na1—Fe1^viii	105.75 (5)
Na1—Fe1—Na1^ii	133.773 (18)	O3^iii—Na1—Fe1^viii	109.10 (5)
O1—P1—O3	113.18 (8)	O2^v—Na1—Fe1^viii	120.07 (5)
O1—P1—O2	114.76 (8)	O6^vi—Na1—Fe1^viii	37.96 (3)
O3—P1—O2	110.56 (8)	O4—Na1—Fe1^viii	40.19 (3)
O1—P1—C1	103.34 (8)	O3^v—Na1—Fe1^viii	114.44 (4)
O3—P1—C1	108.30 (8)	C2^vi—Na1—Fe1^viii	57.12 (4)
O2—P1—C1	105.99 (8)	P1—Na1—Fe1^viii	88.61 (2)
O1—P1—Na1	43.24 (6)	P1^v—Na1—Fe1^viii	119.69 (3)
O3—P1—Na1	95.39 (6)	Fe1—Na1—Fe1^viii	119.73 (3)
O2—P1—Na1	152.67 (6)	Na1^vii—Na1—Fe1^viii	125.38 (4)
C1—P1—Na1	72.21 (6)	P1—O1—Fe1	151.70 (9)
O1—P1—Na1^iv	130.89 (6)	P1—O1—Na1	110.23 (8)
O3—P1—Na1^iv	66.95 (6)	Fe1—O1—Na1	96.21 (6)
O2—P1—Na1^iv	43.78 (6)	P1—O2—Fe1^i	127.58 (8)
C1—P1—Na1^iv	123.83 (6)	P1—O2—Na1^iv	109.52 (7)
Na1—P1—Na1^iv	158.45 (2)	Fe1^i—O2—Na1^iv	121.38 (7)
O1—Na1—O3^iii	79.95 (5)	P1—O3—Fe1^ix	131.10 (8)
O1—Na1—O2^v	92.21 (6)	P1—O3—Na1^ix	133.44 (8)
O3^iii—Na1—O2^v	130.40 (7)	Fe1^ix—O3—Na1^ix	92.43 (6)
O1—Na1—O6^vi	140.06 (6)	P1—O3—Na1^iv	84.78 (6)
O3^iii—Na1—O6^vi	95.85 (6)	Fe1^ix—O3—Na1^iv	125.89 (6)
O2^v—Na1—O6^vi	118.51 (6)	Na1^ix—O3—Na1^iv	79.93 (5)
O1—Na1—O4	80.23 (5)	C1—O4—Fe1^viii	110.42 (10)
O3^iii—Na1—O4	134.23 (6)	C1—O4—Na1	103.78 (10)
O2^v—Na1—O4	91.14 (5)	Fe1^viii—O4—Na1	94.89 (5)
O6^vi—Na1—O4	74.68 (5)	C1—O4—H4	106.7
O1—Na1—O3^v	136.98 (6)	Fe1^viii—O4—H4	117.4
O3^iii—Na1—O3^v	100.07 (5)	Na1—O4—H4	122.5
O2^v—Na1—O3^v	54.89 (5)	C2—O5—Fe1^viii	113.84 (12)
O6^vi—Na1—O3^v	82.95 (5)	C2—O6—Fe1^i	130.23 (13)
O4—Na1—O3^v	122.19 (5)	C2—O6—Na1^x	105.34 (12)
O1—Na1—C2^vi	162.81 (7)	Fe1^i—O6—Na1^x	99.17 (6)
O3^iii—Na1—C2^vi	103.28 (6)	O4—C1—C2	106.71 (14)
O2^v—Na1—C2^vi	98.06 (6)	O4—C1—P1	111.00 (12)
O6^vi—Na1—C2^vi	23.73 (5)	C2—C1—P1	107.16 (13)
O4—Na1—C2^vi	85.79 (5)	O4—C1—H1	110.6
O3^v—Na1—C2^vi	59.66 (5)	C2—C1—H1	110.6
O1—Na1—P1	26.53 (4)	P1—C1—H1	110.6
O3^iii—Na1—P1	104.70 (5)	O6—C2—O5	124.66 (18)
O2^v—Na1—P1	83.44 (4)	O6—C2—C1	118.85 (17)
O6^vi—Na1—P1	126.57 (5)	O5—C2—C1	116.49 (16)
O4—Na1—P1	55.61 (4)	O6—C2—Na1^x	50.93 (10)
O3^v—Na1—P1	138.09 (4)	O5—C2—Na1^x	114.47 (13)
C2^vi—Na1—P1	141.39 (5)	C1—C2—Na1^x	104.71 (11)
O1—Na1—P1^v	115.82 (5)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O4—H4···O5^ix	0.88	1.74	2.6168 (19)	173

Symmetry code: (ix) −x+1/2, y+1/2, z.