Hexaaqua­magnesium(II) bis­(pyridinium-2,6-dicarboxyl­ate)

Pasdar, H.; Heidari, S.; Aghabozorg, H.; Notash, B.

doi:10.1107/S1600536810046696

metal-organic compounds

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ISSN: 2056-9890

Volume 66| Part 12| December 2010| Page m1581

https://doi.org/10.1107/S1600536810046696

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Hexaaquamagnesium(II) bis(pyridinium-2,6-dicarboxylate)

Hoda Pasdar,^a Sanaz Heidari,^a ^* Hossein Aghabozorg ^a and Behrouz Notash ^b

^aDepartment of Chemistry, Islamic Azad University, North Tehran Branch, Tehran, Iran, and ^bDepartment of Chemistry, Shahid Beheshti University, G. C., Evin, Tehran 1983963113, Iran
^*Correspondence e-mail: heidari.sanaz3335@yahoo.com

(Received 11 October 2010; accepted 11 November 2010; online 17 November 2010)

In the title compound, [Mg(H₂O)₆](C₇H₄NO₄)₂, a single six-coordinate Mg²⁺ cation (site symmetry 2/m) is bonded to six water molecules in a distorted octahedral geometry. The crystal packing between the complex cation and the zwitterionic organic cation (m symmetry) is stabilized by intermolecular O—H⋯O hydrogen bonds and weak intermolecular C—H⋯O interactions.

Related literature

For background to proton-transfer compounds, see: Aghabozorg et al. (2008 ). For related structures, see: Aghabozorg et al. (2005 ); Grossel et al. (2006 ); Ptasiewicz-Bak & Leciejewicz (2003 ); Dale et al. (2003 ); Yang et al. (2005 ); Kariuki & Jones (1989 )

Experimental

Crystal data

[Mg(H₂O)₆](C₇H₄NO₄)₂
M_r = 464.63
Monoclinic, C 2/m
a = 13.432 (3) Å
b = 11.108 (2) Å
c = 6.5845 (13) Å
β = 92.79 (3)°
V = 981.3 (3) Å³
Z = 2
Mo Kα radiation
μ = 0.17 mm⁻¹
T = 298 K
0.35 × 0.30 × 0.15 mm

Data collection

Stoe IPDS II diffractometer
Absorption correction: numerical (X-RED and X-SHAPE; Stoe & Cie, 2005 ) T_min = 0.940, T_max = 0.973
5499 measured reflections
1383 independent reflections
1178 reflections with I > 2σ(I)
R_int = 0.031

Refinement

R[F² > 2σ(F²)] = 0.038
wR(F²) = 0.095
S = 1.12
1383 reflections
94 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3⋯O1	0.862 (19)	1.834 (19)	2.6940 (14)	174.6 (19)
O4—H4⋯O2	0.85 (2)	1.93 (2)	2.7758 (14)	171 (2)
O5—H5⋯O2ⁱ	0.89 (2)	1.92 (2)	2.7960 (14)	167.5 (19)
C1—H1⋯O5ⁱⁱ	0.93	2.58	3.308 (3)	136
Symmetry codes: (i) x, y, z-1; (ii) $[-x+{\script{1\over 2}}, y+{\script{1\over 2}}, -z+1]$ .

Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA; data reduction: X-AREA; 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 ); software used to prepare material for publication: WinGX (Farrugia, 1999 ).

Supporting information

Crystal structure: contains datablocks I, glolbal. DOI: https://doi.org/10.1107/S1600536810046696/jj2069sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810046696/jj2069Isup2.hkl

checkCIF report

Comment top

Pyridine-2,6-dicarboxylic acid is commonly used as proton donor in proton transfer systems (Aghabozorg et al. 2008). It has been reported that the carboxylate groups are deprotonated and the pyridine ring is protonated in compounds containing pyridine-2,6-dicarboxylic acid( Aghabozorg et al. 2005; Grossel et al. 2006). In addition, the formation of a six-coordinated magnesium (II) ion by water molecules in aqueous solution in the presence of poly carboxylic acids has been observed (Dale et al. 2003; Ptasiewicz-Bak & Leciejewicz 2003; Yang et al. 2005). The structure of hexa-aquamagnesium(II) pyrazine-2,6-dicarboxylate, [Mg(H₂O)₆][pz-2,6-dc], has also been reported which exhibits hydrogen bonding between the cationic magnesium species and a pyrazine-2,6-dicarboxylate anion (Ptasiewicz-Bak & Leciejewicz 2003).

In the title compound, [Mg(H₂O)₆][pyH-2,6-dc]₂, the cation is comprised of a six-coordinate Mg^II ion bound by water molecules in a distorted octahedral geometry. The dianion is comprised of a pyridine-2,6-dicarboxylic acid group (Fig. 1). Bond lengths and angles for Mg—O are in normal ranges. Crystal packing is stabilized by O—H···O intra and intermolecular hydrogen bonds and weak C—H···O intermolecular hydrogen bond interactions with the coordinated water molecules (Fig. 2). The pyridine ring in the dianion is protonated and the two carboxylic acid groups are deprotonated forming a proton transfer fragment.

Related literature top

For background to proton-transfer compounds, see: Aghabozorg et al. (2008). For related structures, see: Aghabozorg et al. (2005); Grossel et al. (2006); Ptasiewicz-Bak & Leciejewicz (2003); Dale et al. (2003); Yang et al. (2005); Kariuki & Jones (1989)

Experimental top

A solution of pyridine-2,6-dicarboxylic acid (pydcH₂) (0.1671 g, 1 mmol) in ethanol (20 ml) was added to a solution of pyridazine (pydz) (0.072 ml, 1 mmol) in ethanol (8 ml) and stirred for 2 hrs. Then an aqueous solution of Mg(NO₃)₂.6H₂O (0.1282 g, 0.5 mmol) was added to mixture of pydcH₂-pydz and stirred for 1 h. 1 mL DMSO was then added to the mixture to clear the solution and stirred for more 2 hrs. Slow evaporation of the resulting solution gave colorless crystals of the title compound after three weeks which were suitable for X-ray analysis (decomposition > 260 °C).

Structure description top

For background to proton-transfer compounds, see: Aghabozorg et al. (2008). For related structures, see: Aghabozorg et al. (2005); Grossel et al. (2006); Ptasiewicz-Bak & Leciejewicz (2003); Dale et al. (2003); Yang et al. (2005); Kariuki & Jones (1989)

Computing details top

Data collection: X-AREA (Stoe & Cie, 2005); cell refinement: X-AREA (Stoe & Cie, 2005); data reduction: X-AREA (Stoe & Cie, 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); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures top

	Fig. 1. The molecular structure of [Mg(H₂O)₆][pyH-2,6-dc]₂ with displacement ellipsoids drawn at 30% probability level. Symmetry codes: (i: x, 1 - y, z; ii: 1 - x, y, -z; iv: 1 - x, -y, -z).
	Fig. 2. The packing diagram of [Mg(H₂O)₆][pyH-2,6-dc]₂ viewed down the c-axis. The intra and intermolecular O—H···O and intermolecular C—H···O hydrogen bonds are shown as blue and green dashed lines, respectively.

Hexaaquamagnesium(II) bis(pyridinium-2,6-dicarboxylate) top

Crystal data top

[Mg(H₂O)₆](C₇H₄NO₄)₂	F(000) = 484.0
M_r = 464.63	D_x = 1.572 Mg m⁻³
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2y	Cell parameters from 1383 reflections
a = 13.432 (3) Å	θ = 2.4–29.1°
b = 11.108 (2) Å	µ = 0.17 mm⁻¹
c = 6.5845 (13) Å	T = 298 K
β = 92.79 (3)°	Plate, colorless
V = 981.3 (3) Å³	0.35 × 0.30 × 0.15 mm
Z = 2

Data collection top

Stoe IPDS II diffractometer	1383 independent reflections
Radiation source: fine-focus sealed tube	1178 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.031
Detector resolution: 0.15 pixels mm^-1	θ_max = 29.1°, θ_min = 2.4°
rotation method scans	h = −17→18
Absorption correction: numerical (X-RED and X-SHAPE; Stoe & Cie, 2005)	k = −14→15
T_min = 0.940, T_max = 0.973	l = −9→8
5499 measured reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.038	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.095	H atoms treated by a mixture of independent and constrained refinement
S = 1.12	w = 1/[σ²(F_o²) + (0.0414P)² + 0.5177P] where P = (F_o² + 2F_c²)/3
1383 reflections	(Δ/σ)_max = 0.001
94 parameters	Δρ_max = 0.33 e Å⁻³
0 restraints	Δρ_min = −0.18 e Å⁻³

Crystal data top

[Mg(H₂O)₆](C₇H₄NO₄)₂	V = 981.3 (3) Å³
M_r = 464.63	Z = 2
Monoclinic, C2/m	Mo Kα radiation
a = 13.432 (3) Å	µ = 0.17 mm⁻¹
b = 11.108 (2) Å	T = 298 K
c = 6.5845 (13) Å	0.35 × 0.30 × 0.15 mm
β = 92.79 (3)°

Data collection top

Stoe IPDS II diffractometer	1383 independent reflections
Absorption correction: numerical (X-RED and X-SHAPE; Stoe & Cie, 2005)	1178 reflections with I > 2σ(I)
T_min = 0.940, T_max = 0.973	R_int = 0.031
5499 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.038	0 restraints
wR(F²) = 0.095	H atoms treated by a mixture of independent and constrained refinement
S = 1.12	Δρ_max = 0.33 e Å⁻³
1383 reflections	Δρ_min = −0.18 e Å⁻³
94 parameters

Special details top

Experimental. shape of crystal determined optically

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 (Å²) top

	x	y	z	U_iso*/U_eq
Mg1	0.5000	0.0000	0.0000	0.0249 (2)
O1	0.40364 (11)	0.31353 (9)	0.27234 (16)	0.0499 (3)
O2	0.36594 (9)	0.18375 (8)	0.51657 (15)	0.0396 (3)
O3	0.5000	0.18182 (12)	0.0000	0.0360 (3)
O4	0.41819 (12)	0.0000	0.2566 (2)	0.0357 (3)
O5	0.36739 (11)	0.0000	−0.1931 (2)	0.0341 (3)
N1	0.37142 (12)	0.5000	0.4931 (2)	0.0257 (3)
C1	0.31770 (16)	0.5000	0.8796 (3)	0.0347 (4)
H1	0.2989	0.5000	1.0137	0.042*
C2	0.33156 (11)	0.39121 (12)	0.78070 (19)	0.0312 (3)
H2	0.3225	0.3186	0.8476	0.037*
C3	0.35898 (9)	0.39277 (10)	0.58164 (18)	0.0253 (3)
C4	0.37779 (11)	0.28571 (11)	0.4447 (2)	0.0310 (3)
H3	0.4708 (14)	0.2281 (19)	0.084 (3)	0.053 (5)*
H4	0.4046 (15)	0.0617 (19)	0.327 (3)	0.057 (6)*
H5	0.3664 (16)	0.0661 (19)	−0.270 (3)	0.065 (6)*
H1A	0.3899 (19)	0.5000	0.366 (4)	0.046 (7)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Mg1	0.0367 (5)	0.0173 (4)	0.0211 (4)	0.000	0.0062 (3)	0.000
O1	0.0892 (9)	0.0278 (5)	0.0351 (5)	0.0102 (5)	0.0267 (6)	−0.0011 (4)
O2	0.0626 (7)	0.0192 (4)	0.0374 (5)	0.0041 (4)	0.0054 (5)	0.0011 (4)
O3	0.0602 (10)	0.0177 (6)	0.0315 (7)	0.000	0.0172 (6)	0.000
O4	0.0566 (9)	0.0226 (6)	0.0296 (7)	0.000	0.0179 (6)	0.000
O5	0.0467 (8)	0.0295 (7)	0.0262 (6)	0.000	0.0034 (6)	0.000
N1	0.0353 (8)	0.0203 (7)	0.0220 (6)	0.000	0.0081 (6)	0.000
C1	0.0486 (12)	0.0344 (10)	0.0217 (8)	0.000	0.0080 (7)	0.000
C2	0.0422 (8)	0.0253 (6)	0.0265 (6)	0.0000 (5)	0.0059 (5)	0.0048 (5)
C3	0.0303 (6)	0.0192 (5)	0.0267 (5)	0.0018 (4)	0.0036 (4)	0.0007 (4)
C4	0.0410 (7)	0.0210 (6)	0.0312 (6)	0.0050 (5)	0.0048 (5)	−0.0027 (5)

Geometric parameters (Å, º) top

Mg1—O3ⁱ	2.0197 (14)	O5—H5	0.89 (2)
Mg1—O3	2.0197 (14)	N1—C3ⁱⁱ	1.3401 (13)
Mg1—O4ⁱ	2.0601 (15)	N1—C3	1.3401 (13)
Mg1—O4	2.0601 (15)	N1—H1A	0.89 (3)
Mg1—O5ⁱ	2.1375 (16)	C1—C2	1.3897 (16)
Mg1—O5	2.1375 (16)	C1—C2ⁱⁱ	1.3897 (16)
O1—C4	1.2422 (17)	C1—H1	0.9300
O2—C4	1.2406 (16)	C2—C3	1.3788 (17)
O3—H3	0.862 (19)	C2—H2	0.9300
O4—H4	0.85 (2)	C3—C4	1.5208 (17)

O3ⁱ—Mg1—O3	180.0	Mg1—O5—H5	109.1 (13)
O3ⁱ—Mg1—O4ⁱ	90.0	C3ⁱⁱ—N1—C3	125.46 (15)
O3—Mg1—O4ⁱ	90.0	C3ⁱⁱ—N1—H1A	117.27 (8)
O3ⁱ—Mg1—O4	90.0	C3—N1—H1A	117.27 (8)
O3—Mg1—O4	90.0	C2—C1—C2ⁱⁱ	120.82 (17)
O4ⁱ—Mg1—O4	180.00 (8)	C2—C1—H1	119.6
O3ⁱ—Mg1—O5ⁱ	90.0	C2ⁱⁱ—C1—H1	119.6
O3—Mg1—O5ⁱ	90.0	C3—C2—C1	118.87 (12)
O4ⁱ—Mg1—O5ⁱ	91.46 (6)	C3—C2—H2	120.6
O4—Mg1—O5ⁱ	88.54 (6)	C1—C2—H2	120.6
O3ⁱ—Mg1—O5	90.0	N1—C3—C2	117.99 (12)
O3—Mg1—O5	90.0	N1—C3—C4	114.17 (11)
O4ⁱ—Mg1—O5	88.54 (6)	C2—C3—C4	127.84 (11)
O4—Mg1—O5	91.46 (6)	O2—C4—O1	128.49 (12)
O5ⁱ—Mg1—O5	180.00 (8)	O2—C4—C3	117.37 (12)
Mg1—O3—H3	126.6 (13)	O1—C4—C3	114.14 (11)
Mg1—O4—H4	125.5 (14)

C2ⁱⁱ—C1—C2—C3	−0.3 (3)	N1—C3—C4—O2	−178.85 (14)
C3ⁱⁱ—N1—C3—C2	−0.3 (3)	C2—C3—C4—O2	1.3 (2)
C3ⁱⁱ—N1—C3—C4	179.77 (12)	N1—C3—C4—O1	1.23 (19)
C1—C2—C3—N1	0.3 (2)	C2—C3—C4—O1	−178.66 (14)
C1—C2—C3—C4	−179.83 (15)

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

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O1	0.862 (19)	1.834 (19)	2.6940 (14)	174.6 (19)
O4—H4···O2	0.85 (2)	1.93 (2)	2.7758 (14)	171 (2)
O5—H5···O2ⁱⁱⁱ	0.89 (2)	1.92 (2)	2.7960 (14)	167.5 (19)
C1—H1···O5^iv	0.93	2.58	3.308 (3)	136

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

Experimental details

Crystal data
Chemical formula	[Mg(H₂O)₆](C₇H₄NO₄)₂
M_r	464.63
Crystal system, space group	Monoclinic, C2/m
Temperature (K)	298
a, b, c (Å)	13.432 (3), 11.108 (2), 6.5845 (13)
β (°)	92.79 (3)
V (Å³)	981.3 (3)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	0.17
Crystal size (mm)	0.35 × 0.30 × 0.15

Data collection
Diffractometer	Stoe IPDS II
Absorption correction	Numerical (X-RED and X-SHAPE; Stoe & Cie, 2005)
T_min, T_max	0.940, 0.973
No. of measured, independent and observed [I > 2σ(I)] reflections	5499, 1383, 1178
R_int	0.031
(sin θ/λ)_max (Å⁻¹)	0.685

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.038, 0.095, 1.12
No. of reflections	1383
No. of parameters	94
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.33, −0.18

Computer programs: X-AREA (Stoe & Cie, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O1	0.862 (19)	1.834 (19)	2.6940 (14)	174.6 (19)
O4—H4···O2	0.85 (2)	1.93 (2)	2.7758 (14)	171 (2)
O5—H5···O2ⁱ	0.89 (2)	1.92 (2)	2.7960 (14)	167.5 (19)
C1—H1···O5ⁱⁱ	0.93	2.58	3.308 (3)	135.8

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

Acknowledgements

The authors are grateful to the Islamic Azad University, North Branch, for financial support of this work.

References

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