Poly[[diaqua­bis­[μ-2-(4-fluoro­phen­oxy)acetato-κ2 O 1:O 1′]magnesium] 0.4-hydrate]

Graham Smith

doi:10.1107/S1600536812035246

. 2012 Aug 15;68(Pt 9):m1178. doi: 10.1107/S1600536812035246

Poly[[diaquabis[μ-2-(4-fluorophenoxy)acetato-κ² O ¹:O ^1′]magnesium] 0.4-hydrate]

Graham Smith ^a,^*

PMCID: PMC3435600 PMID: 22969473

Abstract

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.

Related literature

For the structures of some magnesium complexes, derived from 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 ▶).

Experimental

Crystal data

[Mg(C₈H₆FO₃)₂(H₂O)₂]·0.4H₂O
M _r = 405.80
Monoclinic,
a = 17.2526 (9) Å
b = 6.8899 (3) Å
c = 7.5474 (3) Å
β = 95.118 (4)°
V = 893.57 (7) Å³
Z = 2
Mo Kα radiation
μ = 0.17 mm⁻¹
T = 200 K
0.30 × 0.20 × 0.05 mm

Data collection

Oxford Diffraction Gemini-S CCD-detector diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012 ▶) T _min = 0.964, T _max = 0.980
5825 measured reflections
1762 independent reflections
1400 reflections with I > 2σ(I)
R _int = 0.040

Refinement

R[F ² > 2σ(F ²)] = 0.047
wR(F ²) = 0.109
S = 1.06
1762 reflections
133 parameters
H-atom parameters constrained
Δρ_max = 0.25 e Å⁻³
Δρ_min = −0.29 e Å⁻³

Data collection: CrysAlis PRO (Agilent, 2012 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; 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.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812035246/lh5512sup1.cif

e-68-m1178-sup1.cif^{(20.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812035246/lh5512Isup2.hkl

e-68-m1178-Isup2.hkl^{(85KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812035246/lh5512Isup3.cml

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Mg1—O1W	2.1032 (14)
Mg1—O21	2.0478 (14)
Mg1—O22ⁱ	2.0620 (14)

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Symmetry code: (i) Inline graphic .

Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H11W⋯O1^iv	0.91	2.45	3.214 (2)	143
O1W—H12W⋯O22^iv	0.92	2.38	3.0352 (19)	128
O1W—H12W⋯O21ⁱ	0.92	1.92	2.760 (2)	151
O2W—H21W⋯O1^iv	0.95	2.41	3.034 (10)	123
O2W—H22W⋯O22ⁱⁱⁱ	0.85	2.13	2.950 (9)	160

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Symmetry codes: (i) Inline graphic ; (iii) ; (iv) .

Acknowledgments

The author acknowledges financial support from the Australian Research Council, the Science and Engineering Faculty and the University Library, Queensland University of Technology.

supplementary crystallographic information

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)°].

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.