Poly[[diaqua­bis­[μ-2-(4-fluoro­phen­oxy)acetato-κ²O¹:O^1′]magnesium] 0.4-hydrate]

In the title compound, {[Mg(C₈H₆FO₃)₂(H₂O)₂]·0.4H₂O}_n, slightly distorted octa­hedral MgO₆ complex units have crystallographic inversion symmetry, the coordination polyhedron comprising two trans-related water mol­ecules and four carboxyl O-atom donors, two of which are bridging. Within the two-dimensional complex polymer which is parallel to (100), coordinating water mol­ecules form inter­molecular O—H...O hydrogen bonds with carboxyl­ate and phen­oxy O-atom acceptors, as well as with the partial-occupancy solvent water mol­ecules.

Key indicators

• Single-crystal X-ray study
• T = 200 K
• Mean [sigma](C-C) = 0.004 Å
• Disorder in solvent or counterion
• R factor = 0.047
• wR factor = 0.109
• Data-to-parameter ratio = 13.2

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT417_ALERT_2_B Short Inter D-H..H-D       H11W   ..  H22W    ..       2.08 Ang.

Alert level C
PLAT077_ALERT_4_C Unitcell contains non-integer number of atoms ..          ?
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for         O1
PLAT415_ALERT_2_C Short Inter D-H..H-X       H11A   ..  H22W    ..       2.12 Ang.
PLAT906_ALERT_3_C Large K value in the Analysis of Variance ......      7.465
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          2

Alert level G
PLAT004_ALERT_5_G Info: Polymeric Structure Found with Dimension .          2
PLAT005_ALERT_5_G No _iucr_refine_instructions_details in CIF ....          ?
PLAT007_ALERT_5_G Note: Number of Unrefined D-H Atoms ............          4
PLAT042_ALERT_1_G Calc. and Reported MoietyFormula Strings  Differ          ?
PLAT302_ALERT_4_G Note: Anion/Solvent Disorder ...................        100 Perc.

   0 ALERT level A = Most likely a serious problem - resolve or explain
   1 ALERT level B = A potentially serious problem, consider carefully
   5 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

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

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S1. Comment

Magnesium complexes involving monoanionic phenoxyacetate ligands (L) show a variety of coordination modes, all based on an octahedral MgO₆ metal stereochemistry, e.g. discrete monomeric [[MgL₂(H₂O)₄] (L = 2-fluorophenoxyacetate) (Kennard et al., 1986); (L = 4-chloro-2-methylphenoxyacetate) (Smith et al., 1981); [MgL(H₂O)₅] (L = 2,4,5-trichlorophenoxyacetate) (Smith et al., 1982)], or polymeric [[MgL₂(H₂O)₂]_n (L = phenoxyacetate or 4-chlorophenoxyacetate) (Smith et al., 1980)].

The title complex, [Mg(H₂O)₂(C₈H₆FO₃)₂]_n (0.4H₂O)_n was obtained from the reaction of 4-fluorophenoxyacetic acid with MgCO₃ in aqueous ethanol and the structure is reported herein. In this structure (Fig. 1), the slightly distorted octahedral MgO₆ complex units [bond range Mg—O, 2.0478 (14)–2.1032 (14) Å (Table 1)] have crystallographic inversion symmetry, the coordination polyhedron comprising two trans-related water molecules and four carboxyl O-atom donors, two of which are bridging. Within the two-dimensional complex polymer layers which extend across (100), the coordinated water molecules from intermolecular O—H···O hydrogen-bonding interactions (Table 2), with carboxyl and phenoxy O-atom acceptors as well as with the partial water molecules of solvation (S.O.F. = 0.2) (Fig. 2). Except for the presence of the partial water molecules, the structure is similar to the those of the isomorphous Mg complexes with phenoxyacetate and 4-chlorophenoxyacetate (Smith et al., 1980). In the present complex, the 4-fluorophenoxyacetate ligand is essentially planar, with the carboxyl group rotated slightly out of the plane [benzene ring to acetate dihedral angle = 12.26 (12)°].

Related literature

For the structures of some magnesium complexes with phenoxyacetic acids, see: Smith et al. (1980, 1981, 1982); Kennard et al. (1986). For the structures of other metal complexes with 4-fluorophenoxyacetate, see: O'Reilly et al. (1984); Smith et al. (1993).

S2. Experimental

The title compound was synthesized by the addition of excess MgCO₃ to 15 ml of a hot aqueous ethanolic solution (10:1) of 4-fluorophenoxyacetic acid (0.1 g). After completion of the reaction, the excess MgCO₃ was removed by filtration and the solution was allowed evaporate to incipient dryness at room temperature, giving thin colourless plates of the title compound from which a specimen was cleaved for the X-ray analysis.

S3. Refinement

Hydrogen atoms on the coordinated water molecule were located by difference methods and both positional and isotropic displacement parameters were initially refined but these were then allowed to ride, with U_iso(H) = 1.5U_eq(C). Other H-atoms were included in the refinement at calculated positions [C—H(aromatic) = 0.93 Å, 0.98 Å (methylene)] or O—H = 0.84–0.94 Å, with U_iso(H) = 1.2U_eq(C) or 1.5U_eq(O), also using a riding-model approximation. The site occupancy factor for the partial water molecule of solvation was determined as 0.196 (4) and was subsequently fixed as 0.20.

Computing details

Data collection: CrysAlis PRO (Agilent, 2012); cell refinement: CrysAlis PRO (Agilent, 2012); data reduction: CrysAlis PRO (Agilent, 2012); program(s) used to solve structure: SIR92 (Altomare et al., 1993); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) within WinGX (Farrugia, 1999); molecular graphics: PLATON (Spek, 2009); software used to prepare material for publication: PLATON (Spek, 2009).

Figures

	Fig. 1. The molecular structure of the title compound, including the partial water molecules of solvation (O2W), with displacement ellipsoids drawn at the 50% probability level. For symmetry codes, see Table 1.
	Fig. 2. The hydrogen-bonding interactions, shown as dashed lines, in the title compound viewed along c. The partial water molecule of solvation and non-associative H-atoms have been omitted. For symmetry codes, see Tables 1 and 2.

Poly[[diaquabis[µ-2-(4-fluorophenoxy)acetato- κ²O¹:O^1']magnesium] 0.4-hydrate]

Crystal data

[Mg(C8H6FO3)2(H2O)2]·0.4H2O	F(000) = 420
Mr = 405.80	Dx = 1.508 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1476 reflections
a = 17.2526 (9) Å	θ = 3.2–28.9°
b = 6.8899 (3) Å	µ = 0.17 mm^−1
c = 7.5474 (3) Å	T = 200 K
β = 95.118 (4)°	Plate, colourless
V = 893.57 (7) Å^3	0.30 × 0.20 × 0.05 mm
Z = 2

Data collection

Oxford Diffraction Gemini-S CCD-detector diffractometer	1762 independent reflections
Radiation source: Enhance (Mo) X-ray source	1400 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.040
Detector resolution: 16.077 pixels mm^-1	θmax = 26.0°, θmin = 3.2°
ω scans	h = −21→21
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012)	k = −8→8
Tmin = 0.964, Tmax = 0.980	l = −9→9
5825 measured reflections

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)] = 0.047	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.109	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0424P)^2 + 0.393P] where P = (Fo^2 + 2Fc^2)/3
1762 reflections	(Δ/σ)max < 0.001
133 parameters	Δρmax = 0.25 e Å^−3
0 restraints	Δρmin = −0.29 e Å^−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

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	Occ. (<1)
Mg1	0.00000	0.50000	0.50000	0.0187 (3)
F4	0.49577 (8)	−0.0237 (3)	0.7819 (2)	0.0567 (6)
O1	0.20100 (10)	−0.0103 (3)	0.4489 (2)	0.0481 (6)
O1W	0.09125 (8)	0.6177 (2)	0.36712 (19)	0.0255 (5)
O21	0.01967 (8)	0.2303 (2)	0.39916 (19)	0.0255 (4)
O22	0.07774 (8)	0.02846 (19)	0.22234 (18)	0.0220 (4)
C1	0.27377 (13)	−0.0045 (4)	0.5408 (3)	0.0358 (8)
C2	0.32768 (15)	−0.1323 (4)	0.4814 (4)	0.0519 (10)
C3	0.40282 (15)	−0.1370 (4)	0.5616 (4)	0.0487 (9)
C4	0.42218 (13)	−0.0158 (4)	0.7001 (3)	0.0393 (8)
C5	0.37063 (15)	0.1118 (4)	0.7620 (3)	0.0408 (9)
C6	0.29510 (14)	0.1183 (4)	0.6810 (3)	0.0378 (8)
C11	0.14596 (12)	0.1286 (3)	0.4960 (3)	0.0264 (7)
C21	0.07588 (12)	0.1271 (3)	0.3609 (3)	0.0194 (6)
O2W	0.2262 (5)	0.5768 (14)	0.5816 (12)	0.048 (3)	0.200
H2	0.31330	−0.21540	0.38700	0.0620*
H3	0.43940	−0.22160	0.52140	0.0580*
H5	0.38580	0.19330	0.85700	0.0490*
H6	0.25920	0.20490	0.72100	0.0450*
H11A	0.16940	0.25660	0.50070	0.0320*
H11B	0.12990	0.09860	0.61290	0.0320*
H11W	0.13290	0.67830	0.42470	0.0380*
H12W	0.06600	0.68980	0.27780	0.0380*
H21W	0.22790	0.70540	0.62850	0.0710*	0.200
H22W	0.18990	0.52540	0.63450	0.0710*	0.200

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Mg1	0.0232 (5)	0.0158 (5)	0.0167 (5)	0.0015 (4)	0.0003 (4)	−0.0012 (4)
F4	0.0271 (7)	0.0734 (12)	0.0671 (11)	0.0020 (8)	−0.0101 (7)	0.0008 (9)
O1	0.0388 (10)	0.0607 (12)	0.0412 (11)	0.0274 (9)	−0.0169 (8)	−0.0299 (9)
O1W	0.0261 (8)	0.0252 (8)	0.0249 (8)	0.0015 (7)	0.0008 (6)	0.0034 (6)
O21	0.0299 (8)	0.0197 (7)	0.0261 (8)	0.0051 (7)	−0.0011 (6)	−0.0065 (6)
O22	0.0274 (8)	0.0198 (7)	0.0186 (7)	0.0013 (6)	0.0003 (6)	−0.0028 (6)
C1	0.0310 (12)	0.0464 (15)	0.0286 (13)	0.0124 (12)	−0.0048 (10)	−0.0082 (11)
C2	0.0461 (16)	0.0655 (19)	0.0416 (16)	0.0250 (15)	−0.0107 (13)	−0.0223 (14)
C3	0.0373 (15)	0.0621 (18)	0.0457 (16)	0.0206 (14)	−0.0021 (12)	−0.0062 (14)
C4	0.0249 (12)	0.0519 (16)	0.0401 (15)	−0.0001 (12)	−0.0021 (11)	0.0062 (13)
C5	0.0354 (14)	0.0475 (16)	0.0383 (15)	−0.0048 (12)	−0.0037 (11)	−0.0096 (12)
C6	0.0334 (13)	0.0466 (15)	0.0327 (13)	0.0060 (12)	−0.0012 (11)	−0.0109 (12)
C11	0.0293 (12)	0.0258 (11)	0.0237 (11)	0.0069 (10)	−0.0005 (9)	−0.0071 (9)
C21	0.0254 (11)	0.0130 (9)	0.0198 (10)	−0.0022 (9)	0.0022 (8)	0.0013 (8)
O2W	0.045 (5)	0.054 (6)	0.043 (5)	−0.017 (5)	0.001 (4)	0.009 (4)

Geometric parameters (Å, º)

Mg1—O1W	2.1032 (14)	O2W—H21W	0.9500
Mg1—O21	2.0478 (14)	C1—C2	1.384 (4)
Mg1—O22^i	2.0620 (14)	C1—C6	1.379 (3)
Mg1—O1W^ii	2.1032 (14)	C2—C3	1.381 (4)
Mg1—O21^ii	2.0478 (14)	C3—C4	1.356 (4)
Mg1—O22^iii	2.0620 (14)	C4—C5	1.363 (4)
F4—C4	1.362 (3)	C5—C6	1.390 (3)
O1—C1	1.380 (3)	C11—C21	1.511 (3)
O1—C11	1.416 (3)	C2—H2	0.9300
O21—C21	1.257 (3)	C3—H3	0.9300
O22—C21	1.250 (3)	C5—H5	0.9300
O1W—H11W	0.9100	C6—H6	0.9300
O1W—H12W	0.9200	C11—H11B	0.9700
O2W—H22W	0.8500	C11—H11A	0.9700
O1W—Mg1—O21	90.96 (5)	C1—C2—C3	120.3 (3)
O1W—Mg1—O22^i	92.03 (5)	C2—C3—C4	118.7 (2)
O1W—Mg1—O1W^ii	180.00	F4—C4—C3	118.7 (2)
O1W—Mg1—O21^ii	89.04 (5)	F4—C4—C5	118.7 (2)
O1W—Mg1—O22^iii	87.97 (5)	C3—C4—C5	122.6 (2)
O21—Mg1—O22^i	84.33 (5)	C4—C5—C6	119.0 (2)
O1W^ii—Mg1—O21	89.04 (5)	C1—C6—C5	119.6 (2)
O21—Mg1—O21^ii	180.00	O1—C11—C21	109.90 (17)
O21—Mg1—O22^iii	95.67 (5)	O21—C21—C11	115.38 (19)
O1W^ii—Mg1—O22^i	87.97 (5)	O22—C21—C11	119.32 (18)
O21^ii—Mg1—O22^i	95.67 (5)	O21—C21—O22	125.3 (2)
O22^i—Mg1—O22^iii	180.00	C3—C2—H2	120.00
O1W^ii—Mg1—O21^ii	90.96 (5)	C1—C2—H2	120.00
O1W^ii—Mg1—O22^iii	92.03 (5)	C2—C3—H3	121.00
O21^ii—Mg1—O22^iii	84.33 (5)	C4—C3—H3	121.00
C1—O1—C11	117.06 (19)	C4—C5—H5	120.00
Mg1—O21—C21	139.08 (14)	C6—C5—H5	121.00
Mg1^iv—O22—C21	132.00 (13)	C5—C6—H6	120.00
Mg1—O1W—H12W	103.00	C1—C6—H6	120.00
H11W—O1W—H12W	114.00	O1—C11—H11A	110.00
Mg1—O1W—H11W	123.00	O1—C11—H11B	110.00
H21W—O2W—H22W	102.00	C21—C11—H11B	110.00
O1—C1—C6	124.9 (2)	H11A—C11—H11B	108.00
C2—C1—C6	119.9 (2)	C21—C11—H11A	110.00
O1—C1—C2	115.2 (2)
O1W—Mg1—O21—C21	36.0 (2)	C6—C1—C2—C3	−0.2 (4)
O22^i—Mg1—O21—C21	127.9 (2)	O1—C1—C6—C5	−179.4 (2)
O1W^ii—Mg1—O21—C21	−144.0 (2)	C2—C1—C6—C5	−0.3 (4)
O22^iii—Mg1—O21—C21	−52.1 (2)	C1—C2—C3—C4	0.7 (4)
C11—O1—C1—C2	−175.1 (2)	C2—C3—C4—F4	178.5 (2)
C11—O1—C1—C6	4.0 (3)	C2—C3—C4—C5	−0.7 (4)
C1—O1—C11—C21	169.15 (19)	F4—C4—C5—C6	−179.0 (2)
Mg1—O21—C21—O22	−136.10 (18)	C3—C4—C5—C6	0.2 (4)
Mg1—O21—C21—C11	43.1 (3)	C4—C5—C6—C1	0.3 (4)
Mg1^iv—O22—C21—O21	4.0 (3)	O1—C11—C21—O21	172.84 (18)
Mg1^iv—O22—C21—C11	−175.24 (13)	O1—C11—C21—O22	−7.9 (3)
O1—C1—C2—C3	179.0 (2)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H11W···O1^v	0.91	2.45	3.214 (2)	143
O1W—H12W···O22^v	0.92	2.38	3.0352 (19)	128
O1W—H12W···O21^i	0.92	1.92	2.760 (2)	151
O2W—H21W···O1^v	0.95	2.41	3.034 (10)	123
O2W—H22W···O22^iii	0.85	2.13	2.950 (9)	160

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