Tetra­aqua­bis­(3,5-dinitro­benzoato-κO 1)magnesium tetra­hydrate

Graham Smith

doi:10.1107/S160053681300682X

. 2013 Mar 16;69(Pt 4):m215. doi: 10.1107/S160053681300682X

Tetraaquabis(3,5-dinitrobenzoato-κO ¹)magnesium tetrahydrate

Graham Smith ^a,^*

PMCID: PMC3629491 PMID: 23634009

Abstract

In the structure of the title compound, [Mg(C₇H₃N₂O₆)₂(H₂O)₄]·4H₂O, the slightly distorted octahedral MgO₆ coordination polyhedron comprises two trans-related carboxylate O-atom donors from mononodentate 3,5-dinitrobenzoate ligands, and four water molecules. The coordinating water molecules and the four water molecules of solvation give both intra- and inter-unit O—H⋯O hydrogen-bonding interactions with carboxylate, water and nitro O-atom acceptors, forming a three-dimensional structure.

Related literature

For the structures of some magnesium complexes with nitro-substituted benzoic acids, see: Morgant et al. (2006 ▶); Srinivasan et al. (2007 ▶, 2011 ▶); Arlin et al. (2011 ▶). graphic file with name e-69-0m215-scheme1.jpg

Experimental

Crystal data

[Mg(C₇H₃N₂O₆)₂(H₂O)₄]·4H₂O
M _r = 590.67
Triclinic,
a = 7.1748 (3) Å
b = 11.7299 (6) Å
c = 15.0103 (7) Å
α = 103.224 (4)°
β = 98.569 (4)°
γ = 92.181 (4)°
V = 1212.62 (10) Å³
Z = 2
Mo Kα radiation
μ = 0.18 mm⁻¹
T = 200 K
0.32 × 0.22 × 0.10 mm

Data collection

Oxford Diffraction Gemini-S CCD-detector diffractometer
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2012 ▶) T _min = 0.970, T _max = 0.980
15059 measured reflections
4764 independent reflections
3969 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.036
wR(F ²) = 0.095
S = 0.94
4764 reflections
352 parameters
H-atom parameters constrained
Δρ_max = 0.29 e Å⁻³
Δρ_min = −0.20 e Å⁻³

Data collection: CrysAlis PRO (Agilent, 2012 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶) within WinGX (Farrugia, 2012 ▶); molecular graphics: PLATON (Spek, 2009 ▶); software used to prepare material for publication: PLATON.

Supplementary Material

Click here for additional data file.^{(40.5KB, cif)}

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S160053681300682X/sj5305sup1.cif

e-69-0m215-sup1.cif^{(40.5KB, cif)}

Click here for additional data file.^{(228.6KB, hkl)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S160053681300682X/sj5305Isup2.hkl

e-69-0m215-Isup2.hkl^{(228.6KB, hkl)}

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

Table 1. Selected bond lengths (Å).

Mg1—O1W	2.0929 (14)
Mg1—O2W	2.0732 (13)
Mg1—O3W	2.1024 (14)
Mg1—O4W	2.0804 (13)
Mg1—O11A	2.0304 (13)
Mg1—O11B	2.0237 (13)

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1W—H11W⋯O8W	0.91	1.79	2.700 (2)	179
O1W—H12W⋯O6W ⁱ	0.88	1.93	2.7934 (19)	170
O2W—H21W⋯O12A	0.76	2.11	2.8001 (18)	152
O2W—H22W⋯O6W	0.87	1.87	2.7375 (18)	178
O3W—H31W⋯O7W	0.80	2.02	2.8213 (19)	170
O3W—H32W⋯O5W ⁱⁱ	0.90	1.89	2.7722 (18)	170
O4W—H41W⋯O12B	0.80	2.00	2.7310 (18)	151
O4W—H42W⋯O5W ⁱⁱⁱ	0.83	1.97	2.7986 (18)	174
O5W—H51W⋯O7W ⁱⁱⁱ	0.86	2.11	2.9449 (19)	164
O5W—H52W⋯O1W	0.86	2.17	2.9702 (19)	155
O6W—H61W⋯O12A ⁱ	0.86	2.00	2.8404 (19)	163
O6W—H62W⋯O3W ^iv	0.86	2.14	2.9522 (19)	159
O7W—H71W⋯O12B ^v	0.89	1.87	2.708 (2)	158
O7W—H72W⋯O32B ^vi	0.86	2.50	3.236 (2)	145
O8W—H81W⋯O12A ⁱ	0.90	1.99	2.7737 (19)	145

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

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 nitro-substituted benzoate ligands (L) show both the common [Mg(H₂O)₆]²⁺ 2(L) form, e.g. a dihydrate: L = 4-nitrobenzoate (Srinivasan et al., 2007; Arlin et al., 2011), as well as examples in which the ligand is coordinated, e.g. [MgL(H₂O)₅] (L). HL. H₂O (a complex acid adduct: L = 4-nitro-3-hydroxybenzoate) (Morgant et al., 2006) and [MgL₂(H₂O)₄]: (L = 2-nitrobenzoate) (Srinivasan et al., 2011; Arlin et al., 2011). All known examples are monomeric and have essentially octahedral metal stereochemistry.

The title complex, [Mg(C₇H₃N₂O₆)₂(H₂O)₄]. 4H₂O was obtained from the reaction of 3,5-dinitrobenzoic acid acid with MgCO₃ in aqueous ethanol and the structure is reported here. In this structure (Fig. 1), the slightly distorted octahedral MgO₆ coordination polyhedron comprises two trans-related carboxyl O-atom donors from mononodentate 3,5-dinitrobenzoate ligands, and four water molecules [bond range Mg—O, 2.0237 (13)–2.1024 (14) Å (Table 1)]. The coordinated water molecules and the four water molecules of solvation give both intra- and inter-unit O—H···O hydrogen-bonding interactions with carboxyl, water and nitro O-atom acceptors (Table 2), giving a three-dimensional structure (Fig. 2).

In the present complex, the two 3,5-dinitrobenzoate ligands are conformationally similar, with the carboxyl groups lying essentially in the plane of the benzene ring [torsion angles C2—C1—C11—O11 = 178.01 (14)° (A) and 178.90 (14)° (B)]. The C5 nitro groups are variously rotated out of the benzene plane [torsion angles C2—C3—N3—O32 = 154.31 (17)° (A) and 159.03 (15)° (B): C4—C5—N5—O52 = 167.74 (15)° (A) and 163.06 (15)° (B)].

Experimental

The title compound was synthesized by the addition of excess MgCO₃ to 15 ml of a hot aqueous ethanolic solution (10:1) of 3,5-dinitrobenzoic acid (0.1 g). After completion of the reaction, the excess MgCO₃ was removed by filtration and the solution was allowed to evaporate to partial dryness at room temperature, giving colourless plates of the title compound from which a specimen was cleaved for the X-ray analysis.