metal-organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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Di­aqua­bis­­(4-carb­­oxy-2-ethyl-1H-imidazole-5-carboxyl­ato-κ2N3,O4)manganese(II) N,N-di­methyl­formamide disolvate

aDepartment of Chemistry and Chemical Engineering, Henan University of Urban Construction, Pingdingshan, Henan, People's Republic of China, and bDepartment of Chemical Engineering, Henan Polytechnic Institute, Nanyang, 473009, People's Republic of China
*Correspondence e-mail: zhanghn1010@163.com

(Received 18 May 2011; accepted 26 May 2011; online 4 June 2011)

In the title compound, [Mn(C7H7N2O4)2(H2O)2]·2C3H7NO, the central MnII ion, located on an inversion center, is hexa­coordinated by four O atoms from two water mol­ecules and two carboxyl­ate groups, and two N atoms from two 4-carb­oxy-2-ethyl-1H-imidazole-5-carboxyl­ate anions in a slightly distorted octa­hedral environment. The complex mol­ecules and solvent mol­ecules are connected via N—H⋯O and O—H⋯O hydrogen bonds into a two-dimensional polymeric structure parallel to (001).

Related literature

For coordination polymers built from 2-ethyl-4,5-imidazole­dicarb­oxy­lic acid, see: Li et al. (2011[Li, S.-J., Ma, X.-T., Song, W.-D., Li, X.-F. & Liu, J.-H. (2011). Acta Cryst. E67, m295-m296.]); Wang et al. (2008[Wang, S., Zhang, L. R., Li, G. H., Huo, Q. S. & Liu, Y. L. (2008). CrystEngComm, 10, 1662-1666.]); Zhang et al. (2010[Zhang, F. W., Li, Z. F., Ge, T. Z., Yao, H. C., Li, G., Lu, H. J. & Zhu, Y. Y. (2010). Inorg. Chem. 49, 3776-3788.]). For the structure of the analogous MnII complex with a 5-carb­oxy-2-ethyl-1H-imidazole-4-carboxyl­ate ligand, see: Yan et al. (2010[Yan, J.-B., Li, S.-J., Song, W.-D., Wang, H. & Miao, D.-L. (2010). Acta Cryst. E66, m99.]).

[Scheme 1]

Experimental

Crystal data
  • [Mn(C7H7N2O4)2(H2O)2]·2C3H7NO

  • Mr = 603.46

  • Triclinic, [P \overline 1]

  • a = 7.3246 (2) Å

  • b = 9.0070 (2) Å

  • c = 12.0541 (3) Å

  • α = 68.841 (1)°

  • β = 77.780 (1)°

  • γ = 70.132 (1)°

  • V = 693.89 (3) Å3

  • Z = 1

  • Mo Kα radiation

  • μ = 0.54 mm−1

  • T = 296 K

  • 0.20 × 0.20 × 0.18 mm

Data collection
  • Bruker APEXII area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996[Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.]) Tmin = 0.899, Tmax = 0.908

  • 5239 measured reflections

  • 2447 independent reflections

  • 2192 reflections with I > 2σ(I)

  • Rint = 0.017

Refinement
  • R[F2 > 2σ(F2)] = 0.034

  • wR(F2) = 0.096

  • S = 1.04

  • 2447 reflections

  • 182 parameters

  • 3 restraints

  • H-atom parameters constrained

  • Δρmax = 0.33 e Å−3

  • Δρmin = −0.21 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O1W—H2W⋯O1i 0.80 1.92 2.707 (2) 165
O1W—H1W⋯O2ii 0.82 1.96 2.768 (2) 168
N2—H2⋯O5 0.86 1.89 2.740 (2) 168
O3—H3⋯O2 0.82 1.64 2.462 (2) 179
Symmetry codes: (i) -x+1, -y+1, -z; (ii) x, y-1, z.

Data collection: APEX2 (Bruker, 2007[Bruker (2007). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2007[Bruker (2007). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

Self-assembly of supramolecular architectures based on imidazole carboxylate ligands has drawn much attention during recent decades. To the best of our knowledge, coordination polymers based on 2-ethyl-4,5-imidazoledicarboxylate ligand has been reperted only in recent years (Wang et al., 2008; Zhang et al., 2010; Li et al., 2011). Herein we report the title compound obtained by the reaction of manganese chloride with 2-ethyl-4,5-imidazoledicarboxylic acid (H3EIDC) in a N,N-dimethylformamide solution under hydrothermal conditions.

The title compound, [Mn(C7H7N2O4)2(H2O)2].2C3H7NO, depicted in Fig. 1. Each MnII is coordinated by two terminal water molecules, two nitrogen atoms and two oxygen atoms from two chelating 2-ethyl-4,5-imidazoledicarboxylate ligands, generating a distorted octahedral coordination environment. The N,N-dimethylformamide molecules are connected to the complex molecule via hydrogen bond between N2 and O6 atoms (Table 1). In each H2EIDC ligand that chelates MnII ion via its N, O atom there is a strong hydrogen bond between the carboxylic and carboxylate groups.

A two-dimensional suramolecular structure is consolidated by intermolecular hydrogen-bonding interactions (N—H···O and O—H···O).

The structure of the title compound is very similar to that formed by 2-propyl-4,5-imidazoledicarboxylate ligand with Mn(II) (Yan et al., 2010).

Related literature top

For coordination polymers built with 2-ethyl-4,5-imidazoledicarboxylic acid, see: Li et al. (2011); Wang et al. (2008); Zhang et al. (2010). For the structure of the analogous MnII complex with a 5-carboxy-2-ethyl-1H-imidazole-4-carboxylate ligand, see: Yan et al. (2010).

Experimental top

A mixture of MnCl2 (0.5 mmol, 0.06 g) and 2-ethyl-1H-imidazole-4,5-dicarboxylic acid (0.5 mmol, 0.95 g) in 15 ml of DMF solution was placed in a 23 ml Teflon-lined reactor, which was heated to 443 K for 4 days, and then cooled to room temperature at a rate of 5 K h-1. Crystals of the title compound were obtained by slow evaporation of the solvent at room temperature.

Refinement top

Carboxyl H atoms were located in a difference map but were refined as riding on the parent O atoms with O—H = 0.82 Å and Uiso(H) = 1.5 Ueq(O). Carbon and nitrogen bound H atoms were placed at calculated positions and were treated as riding on the parent C or N atoms with C—H = 0.96 (methyl), 0.97 (methylene) and N—H = 0.86 Å, Uiso(H) = 1.2 or 1.5 Ueq(C, N). H atoms of the water molecule were located in a difference Fourier map and refined as riding with an O—H distance restraint of 0.84 (1) Å, with Uiso(H) = 1.5 Ueq.

Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The structure of the title compound showing 30% probability displacement ellipsoids [symmetry codes: (i) 2 - x, -y, -z.]
Diaquabis(4-carboxy-2-ethyl-1H-imidazole-5-carboxylato- κ2N3,O4)manganese(II) N,N-dimethylformamide disolvate top
Crystal data top
[Mn(C7H7N2O4)2(H2O)2]·2C3H7NOZ = 1
Mr = 603.46F(000) = 315
Triclinic, P1Dx = 1.444 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 7.3246 (2) ÅCell parameters from 5837 reflections
b = 9.0070 (2) Åθ = 2.8–27.9°
c = 12.0541 (3) ŵ = 0.54 mm1
α = 68.841 (1)°T = 296 K
β = 77.780 (1)°Block, colorless
γ = 70.132 (1)°0.20 × 0.20 × 0.18 mm
V = 693.89 (3) Å3
Data collection top
Bruker APEXII area-detector
diffractometer
2447 independent reflections
Radiation source: fine-focus sealed tube2192 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.017
ϕ and ω scansθmax = 25.0°, θmin = 1.8°
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
h = 88
Tmin = 0.899, Tmax = 0.908k = 1010
5239 measured reflectionsl = 1314
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.034Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.096H-atom parameters constrained
S = 1.04 w = 1/[σ2(Fo2) + (0.0528P)2 + 0.2406P]
where P = (Fo2 + 2Fc2)/3
2447 reflections(Δ/σ)max < 0.001
182 parametersΔρmax = 0.33 e Å3
3 restraintsΔρmin = 0.21 e Å3
Crystal data top
[Mn(C7H7N2O4)2(H2O)2]·2C3H7NOγ = 70.132 (1)°
Mr = 603.46V = 693.89 (3) Å3
Triclinic, P1Z = 1
a = 7.3246 (2) ÅMo Kα radiation
b = 9.0070 (2) ŵ = 0.54 mm1
c = 12.0541 (3) ÅT = 296 K
α = 68.841 (1)°0.20 × 0.20 × 0.18 mm
β = 77.780 (1)°
Data collection top
Bruker APEXII area-detector
diffractometer
2447 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
2192 reflections with I > 2σ(I)
Tmin = 0.899, Tmax = 0.908Rint = 0.017
5239 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0343 restraints
wR(F2) = 0.096H-atom parameters constrained
S = 1.04Δρmax = 0.33 e Å3
2447 reflectionsΔρmin = 0.21 e Å3
182 parameters
Special details top

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
xyzUiso*/Ueq
Mn11.00000.00000.00000.03597 (17)
O10.5096 (2)0.68752 (18)0.13763 (14)0.0455 (4)
O20.6923 (2)0.70548 (17)0.03711 (13)0.0431 (4)
O30.8948 (3)0.52116 (18)0.15377 (14)0.0483 (4)
H30.82840.58340.11540.072*
O41.0038 (2)0.25098 (18)0.12795 (13)0.0420 (4)
O50.3937 (3)0.3980 (3)0.39973 (17)0.0701 (6)
N10.8058 (2)0.17558 (19)0.09645 (15)0.0341 (4)
N20.6175 (3)0.3399 (2)0.19823 (15)0.0362 (4)
H20.54130.37180.25540.043*
N30.2062 (3)0.5787 (3)0.49596 (18)0.0519 (5)
C10.6958 (3)0.1811 (3)0.19781 (18)0.0387 (5)
C20.6797 (3)0.4415 (2)0.09255 (17)0.0298 (4)
C30.7965 (3)0.3374 (2)0.02988 (17)0.0292 (4)
C40.6210 (3)0.6249 (2)0.06428 (18)0.0337 (4)
C50.9031 (3)0.3697 (2)0.09070 (17)0.0330 (4)
C60.6624 (4)0.0344 (3)0.2986 (2)0.0594 (7)
H6A0.74100.06560.27920.071*
H6B0.70800.03220.36930.071*
C70.4567 (6)0.0304 (5)0.3278 (4)0.1004 (13)
H7A0.37570.13200.34230.151*
H7B0.44660.06200.39800.151*
H7C0.41450.01870.26200.151*
C80.2127 (5)0.4520 (5)0.6120 (2)0.0766 (9)
H8A0.28520.34540.60290.115*
H8B0.08220.45080.64640.115*
H8C0.27480.47610.66340.115*
C90.1012 (6)0.7462 (5)0.4934 (4)0.1007 (13)
H9A0.09530.81740.41200.151*
H9B0.16680.78290.53500.151*
H9C0.02880.75050.53150.151*
C100.2976 (4)0.5403 (4)0.3999 (2)0.0603 (7)
H100.28970.62540.32720.072*
O1W0.7541 (2)0.0082 (2)0.07777 (18)0.0579 (5)
H1W0.74070.08520.05600.087*
H2W0.66110.08950.08980.087*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Mn10.0376 (3)0.0226 (2)0.0446 (3)0.00243 (18)0.00243 (19)0.01653 (19)
O10.0533 (9)0.0297 (8)0.0465 (9)0.0017 (7)0.0006 (7)0.0197 (7)
O20.0565 (9)0.0226 (7)0.0465 (9)0.0090 (7)0.0017 (7)0.0127 (7)
O30.0653 (11)0.0272 (8)0.0415 (8)0.0125 (7)0.0157 (7)0.0109 (7)
O40.0489 (9)0.0306 (8)0.0404 (8)0.0073 (7)0.0118 (7)0.0173 (6)
O50.0795 (13)0.0729 (14)0.0570 (11)0.0180 (11)0.0185 (10)0.0372 (10)
N10.0374 (9)0.0228 (8)0.0362 (9)0.0041 (7)0.0038 (7)0.0110 (7)
N20.0416 (9)0.0293 (9)0.0313 (9)0.0032 (7)0.0044 (7)0.0131 (7)
N30.0464 (11)0.0616 (13)0.0494 (12)0.0141 (10)0.0077 (9)0.0278 (10)
C10.0434 (12)0.0274 (11)0.0364 (11)0.0047 (9)0.0022 (9)0.0086 (9)
C20.0311 (10)0.0254 (10)0.0317 (10)0.0042 (8)0.0032 (8)0.0112 (8)
C30.0304 (9)0.0224 (9)0.0331 (10)0.0047 (7)0.0007 (8)0.0108 (8)
C40.0360 (10)0.0267 (10)0.0382 (11)0.0031 (8)0.0064 (9)0.0141 (9)
C50.0358 (10)0.0265 (10)0.0346 (10)0.0080 (8)0.0020 (8)0.0114 (8)
C60.0736 (18)0.0351 (13)0.0485 (14)0.0099 (12)0.0116 (12)0.0043 (11)
C70.109 (3)0.093 (3)0.088 (2)0.064 (2)0.007 (2)0.014 (2)
C80.091 (2)0.096 (2)0.0454 (15)0.0368 (19)0.0138 (15)0.0275 (16)
C90.085 (2)0.084 (3)0.129 (3)0.006 (2)0.011 (2)0.058 (3)
C100.0607 (16)0.072 (2)0.0449 (14)0.0210 (14)0.0073 (12)0.0204 (13)
O1W0.0502 (9)0.0266 (8)0.0991 (14)0.0010 (7)0.0228 (9)0.0230 (9)
Geometric parameters (Å, º) top
Mn1—O1Wi2.1683 (17)C1—C61.489 (3)
Mn1—O1W2.1683 (17)C2—C31.369 (3)
Mn1—O4i2.2244 (15)C2—C41.484 (3)
Mn1—O42.2244 (15)C3—C51.475 (3)
Mn1—N1i2.2302 (15)C5—O4i1.238 (2)
Mn1—N12.2302 (15)C6—C71.483 (5)
O1—C41.228 (2)C6—H6A0.9700
O2—C41.281 (3)C6—H6B0.9700
O3—C51.287 (2)C7—H7A0.9600
O3—H30.8200C7—H7B0.9600
O4—C5i1.238 (2)C7—H7C0.9600
O5—C101.235 (4)C8—H8A0.9600
N1—C11.321 (3)C8—H8B0.9600
N1—C31.373 (2)C8—H8C0.9600
N2—C11.350 (3)C9—H9A0.9600
N2—C21.365 (3)C9—H9B0.9600
N2—H20.8600C9—H9C0.9600
N3—C101.309 (3)C10—H100.9300
N3—C91.434 (4)O1W—H1W0.8200
N3—C81.449 (4)O1W—H2W0.8047
O1Wi—Mn1—O1W180.00 (10)O1—C4—C2118.76 (18)
O1Wi—Mn1—O4i90.79 (6)O2—C4—C2116.00 (17)
O1W—Mn1—O4i89.21 (6)O4i—C5—O3122.34 (18)
O1Wi—Mn1—O489.21 (6)O4i—C5—C3119.06 (18)
O1W—Mn1—O490.79 (6)O3—C5—C3118.59 (17)
O4i—Mn1—O4180.00 (11)C7—C6—C1115.0 (2)
O1Wi—Mn1—N1i90.95 (6)C7—C6—H6A108.5
O1W—Mn1—N1i89.05 (6)C1—C6—H6A108.5
O4i—Mn1—N1i104.47 (5)C7—C6—H6B108.5
O4—Mn1—N1i75.53 (5)C1—C6—H6B108.5
O1Wi—Mn1—N189.05 (6)H6A—C6—H6B107.5
O1W—Mn1—N190.95 (6)C6—C7—H7A109.5
O4i—Mn1—N175.53 (5)C6—C7—H7B109.5
O4—Mn1—N1104.47 (5)H7A—C7—H7B109.5
N1i—Mn1—N1180.00 (7)C6—C7—H7C109.5
C5—O3—H3109.5H7A—C7—H7C109.5
C5i—O4—Mn1115.88 (12)H7B—C7—H7C109.5
C1—N1—C3106.19 (16)N3—C8—H8A109.5
C1—N1—Mn1142.61 (14)N3—C8—H8B109.5
C3—N1—Mn1111.18 (12)H8A—C8—H8B109.5
C1—N2—C2108.45 (17)N3—C8—H8C109.5
C1—N2—H2125.8H8A—C8—H8C109.5
C2—N2—H2125.8H8B—C8—H8C109.5
C10—N3—C9122.6 (3)N3—C9—H9A109.5
C10—N3—C8120.8 (3)N3—C9—H9B109.5
C9—N3—C8116.6 (3)H9A—C9—H9B109.5
N1—C1—N2110.34 (18)N3—C9—H9C109.5
N1—C1—C6125.5 (2)H9A—C9—H9C109.5
N2—C1—C6124.14 (19)H9B—C9—H9C109.5
N2—C2—C3105.31 (17)O5—C10—N3124.1 (3)
N2—C2—C4122.29 (17)O5—C10—H10118.0
C3—C2—C4132.40 (18)N3—C10—H10118.0
C2—C3—N1109.70 (16)Mn1—O1W—H1W109.5
C2—C3—C5132.07 (18)Mn1—O1W—H2W120.7
N1—C3—C5118.21 (16)H1W—O1W—H2W120.8
O1—C4—O2125.24 (19)
Symmetry code: (i) x+2, y, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1W—H2W···O1ii0.801.922.707 (2)165
O1W—H1W···O2iii0.821.962.768 (2)168
N2—H2···O50.861.892.740 (2)168
O3—H3···O20.821.642.462 (2)179
Symmetry codes: (ii) x+1, y+1, z; (iii) x, y1, z.

Experimental details

Crystal data
Chemical formula[Mn(C7H7N2O4)2(H2O)2]·2C3H7NO
Mr603.46
Crystal system, space groupTriclinic, P1
Temperature (K)296
a, b, c (Å)7.3246 (2), 9.0070 (2), 12.0541 (3)
α, β, γ (°)68.841 (1), 77.780 (1), 70.132 (1)
V3)693.89 (3)
Z1
Radiation typeMo Kα
µ (mm1)0.54
Crystal size (mm)0.20 × 0.20 × 0.18
Data collection
DiffractometerBruker APEXII area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.899, 0.908
No. of measured, independent and
observed [I > 2σ(I)] reflections
5239, 2447, 2192
Rint0.017
(sin θ/λ)max1)0.595
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.034, 0.096, 1.04
No. of reflections2447
No. of parameters182
No. of restraints3
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.33, 0.21

Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O1W—H2W···O1i0.801.922.707 (2)165
O1W—H1W···O2ii0.821.962.768 (2)168
N2—H2···O50.861.892.740 (2)168
O3—H3···O20.821.642.462 (2)179
Symmetry codes: (i) x+1, y+1, z; (ii) x, y1, z.
 

Acknowledgements

The authors acknowledge Henan University of Urban Construction for supporting this work.

References

First citationBruker (2007). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationLi, S.-J., Ma, X.-T., Song, W.-D., Li, X.-F. & Liu, J.-H. (2011). Acta Cryst. E67, m295–m296.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationSheldrick, G. M. (1996). SADABS. University of Göttingen, Germany.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationWang, S., Zhang, L. R., Li, G. H., Huo, Q. S. & Liu, Y. L. (2008). CrystEngComm, 10, 1662–1666.  Web of Science CSD CrossRef CAS Google Scholar
First citationYan, J.-B., Li, S.-J., Song, W.-D., Wang, H. & Miao, D.-L. (2010). Acta Cryst. E66, m99.  Web of Science CSD CrossRef IUCr Journals Google Scholar
First citationZhang, F. W., Li, Z. F., Ge, T. Z., Yao, H. C., Li, G., Lu, H. J. & Zhu, Y. Y. (2010). Inorg. Chem. 49, 3776–3788.  Web of Science CSD CrossRef CAS PubMed Google Scholar

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