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In the title compound, [Mn(C5H2N2O4)(H2O)2]n, the MnII ion has a distorted octa­hedral geometry and the 4-oxido-2-oxo-1,2-dihydro­pyrimidine-5-carboxyl­ate (Hiso2−) anion acts as a μ34-bridging ligand. Two oxo O atoms from different Hiso2− ligands bridge two MnII ions, forming centrosymmetric dinuclear building blocks. Each dinuclear building block inter­acts with another four by the coordination of the oxide groups and carboxyl­ate O atoms, producing a two-dimensional framework in the ab plane. Hydrogen bonds further extend the two-dimensional sheets into a three-dimensional supra­molecular framework.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270107053875/dn3069sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S0108270107053875/dn3069Isup2.hkl
Contains datablock I

CCDC reference: 672403

Comment top

Construction of porous metal-organic frameworks (MOFs) for hydrogen storage has been intensively studied in recent years, because of their potential for helping to meet targets of safe commercial application of hydrogen gas fuel in all kinds of vehicles (Zhao et al., 2004; Kesanli et al., 2005; Rosi et al., 2003; Li & Yang, 2006; Han & Goddard, 2007). To achieve this goal the designed MOFs must have both enough space to hold hydrogen gas and large surface areas and some special functional groups to bind hydrogen molecules. However, the reported MOFs at present undergo a relatively low enthalpy of adsorption change associated with the H2 uptake, which is significantly lower than that required for fuel cells under operating temperatures and pressures (Dincă et al., 2006). One strategy for solving this problem is to select appropriate organic linkers to increase the H2 binding energy. The linkers used at present are usually organic carboxylic acids bearing aromatic rings, such as benzendicarboxylic acid, benzene tricarboxylic acid, biphenyl-3,3',5,5'-tetracarboxylic acid and naphthalene-1,4,5,8-tetracarboxylate (Han & Goddard, 2007; Wong-Foy et al., 2006; Surblé et al., 2006; Sun et al., 2006; Lin et al., 2006). Organic acids with heteroatomic rings bearing other groups, such as hydroxyl and amino groups, are used much less frequently. This encourages us to use 2,4-dihydroxypyrimidine-5-carboxylic acid as the linker to build MOFs. Therefore, we report here the synthesis and X-ray structure of the title complex, [Mn(H2O)2(Hiso)]n (Hiso2- is 2-oxo-4-oxido-1,2-dihydropyrimidine-5-carboxylate), which exhibits a two-dimensional coordination framework structure assembled by MnII ions and Hiso2-.

As shown in Fig. 1, the MnII ion is coordinated in a distorted octahedral geometry by two water molecules, two oxo O atoms from two different Hiso2– anions, and one carboxylate O atom and one oxido O atom from a third Hiso2– anion. The Mn—O bond lengths range from 2.1271 (16) to 2.3392 (16) Å, and the O—Mn—O bond angles are in the ranges 79.77 (6)–104.37 (6)° and 165.32 (6)–175.33 (6)° (Table 1). Thus, each MnII ion is coordinated to three Hiso2–anions, and each Hiso2– anion acts as a µ3:η4-bridge using the oxo O atom to bridge two MnII ions with a Mn—O—Mn bond angle of 100.23 (6)° and the oxido O atom and one carboxylate O atom to chelate to another MnII ion. To the best of our knowledge, this coordination mode for the Hiso2– ion is unprecedented. The only reported tetradentate case is Pr2(Hiso)(H2iso)4(phen)2(H2O)2·5H2O, in which the Hiso2– anion bridges only two metal ions (Sun & Jin, 2004a).

Two MnII ions are bridged by the oxo groups of two Hiso2– ions, constructing a centrosymmetric dinuclear [Mn2(H2O)4(Hiso)2] building block with an Mn···Mn separation of 3.4697 (3) Å. Each dinuclear building block acts as a four-connected node to connect another four dinuclear building blocks by the coordination of the oxido groups and carboxylate O atoms to the MnII ions from the adjacent dinuclear building blocks. The MnII ions bridged by Hiso2– ions have Mn···Mn separations of 6.9978 (8) and 8.1870 (9) Å, respectively. This leads to the construction of a two-dimensional framework (Fig. 2a) parallel to the ab plane, which presents an s-like appearance viewed down the b axis (Fig. 2b). The pyrimidine rings aligned along the b axis are almost parallel to each other, with a dihedral angle of 5.546° and a center-to-center distance of 3.4617 (4) Å between the two adjacent pyrimidine rings. The center-to-plane distances are 3.194 and 3.273 Å with offset angles of 22.67 and 19.03°, respectively. This indicates the presence of significant ππ interactions between the adjacent pyrimidine rings. The two-dimensional framework also contains O2W—H2WA···O1Wviii, O2W—H2WA···N1i and O1W—H1WB···O3vii hydrogen bonds (details are given in Table 2). These ππ interactions and hydrogen bonds further stabilize the two-dimensional network. The construction of a two-dimensional framework from transition metal ions and 2,4-dihydroxypyrimidine-5-carboxylic acid is unprecedented. The reported cases are usually mononuclear compounds (Luo et al., 2002; Baran et al., 1996). Only a few were obtained as polynuclear complexes (Hueso-Ureña et al., 1996) or one-dimension coordination polymers (Sun & Jin, 2004b).

The two-dimensional sheets pack along the c axis by the propagation of O1W—H1WA···O2vi, O2W—H2WB···O2ix, N2—H2···O1v and N2—H2···O2v hydrogen bonds between two adjacent sheets (Table 2), constructing a three-dimensional supramolecular framework (Fig. 3).

Related literature top

For related literature, see: Hueso-Ureña Moreno-Carretero Quirós-Olozábal Salas-Peregrín Faure Cienfuegos-López (1996); Baran et al. (1996); Dincă et al. (2006); Han & Goddard (2007); Kesanli et al. (2005); Li & Yang (2006); Lin et al. (2006); Luo et al. (2002); Rosi et al. (2003); Sun & Jin (2004a, 2004b); Sun et al. (2006); Surblé et al. (2006); Wong-Foy, Matzger & Yaghi (2006); Zhao et al. (2004).

Experimental top

A mixture of 2,4-dihydroxypyrimidine-5-carboxylic acid (0.0870 g, 0.5 mmol), Mn(ClO4)2·6H2O (0.0905 g, 0.25 mmol), NaOH (0.0200 g, 0.5 mmol) and water (15 ml) was placed in a 22 ml Teflon-lined stainless steel reactor and heated to 383 K for 144 h. The mixture was then cooled over a period of 48 h, giving yellow crystals in 30% yield. Analysis calculated for C5H6MnN2O6: C 24.51, H 2.47, N 11.43%; found: C 24.66, H 2.41, N 11.33%. IR (KBr): 3452 (s), 3321 (s), 3177 (s), 3060 (s), 2509 (w), 2455 (w), 2263 (w), 1987 (w), 1666 (s), 1639 (s), 1574 (s), 1493 (s), 1456 (s), 1392 (s), 1360 (s), 1182 (s), 1131 (m), 1013 (w), 1002 (w), 849 (m), 818 (s), 801 (m), 720 (m), 677 (m), 641 (s), 595 (m), 490 (m) cm-1.

Refinement top

H atoms on C and N atoms were placed in calculated positions (C—H = 0.93 Å and N—H = 0.86 Å) and refined in riding mode [Uiso(H) = 1.2Ueq(C,N)]. H atoms in water molecules were located in a difference Fourier map and refined as riding on their parent atoms [Uiso(H) = 1.5Ueq(O)].

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg & Putz, 2004); software used to prepare material for publication: SHELXTL (Bruker, 1998).

Figures top
[Figure 1] Fig. 1. A view of the molecular structure of (I) with the atom-numbering scheme and 30% probability displacement ellipsoids. For clarity, H atoms have been omitted. [Symmetry codes: (i) x - 1/2, y + 3/2, -z + 1; (ii) -x + 3/2, y - 1/2, z; (iii) -x + 1, -y + 1, -z + 1.]
[Figure 2] Fig. 2. (a) The two-dimensional framework of (I), parallel to the ab plane. (b) The two-dimensional framework of (I), viewed along the b axis. H atoms have been omitted for clarity.
[Figure 3] Fig. 3. The packing of (I). Broken lines indicate hydrogen bonds.
Poly[[diaquamanganese(II)]-µ3-2-oxo-4-oxido-1,2-dihydropyrimidine- 5-carboxylato-κ4O4,O5:O2:O2] top
Crystal data top
[Mn(C5H2N2O4)(H2O)2]F(000) = 984
Mr = 245.06Dx = 2.197 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 2468 reflections
a = 12.9325 (17) Åθ = 2.4–27.2°
b = 6.7317 (9) ŵ = 1.79 mm1
c = 17.018 (2) ÅT = 273 K
V = 1481.5 (3) Å3Block, yellow
Z = 80.20 × 0.10 × 0.10 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer
1303 independent reflections
Radiation source: fine-focus sealed tube1132 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.034
ϕ and ω scansθmax = 25.1°, θmin = 2.4°
Absorption correction: multi-scan
(SADABS; Bruker, 1998)
h = 1415
Tmin = 0.716, Tmax = 0.841k = 78
7030 measured reflectionsl = 2018
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)] = 0.024Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.063H-atom parameters constrained
S = 1.07 w = 1/[σ2(Fo2) + (0.0297P)2 + 0.7981P]
where P = (Fo2 + 2Fc2)/3
1303 reflections(Δ/σ)max = 0.001
127 parametersΔρmax = 0.32 e Å3
0 restraintsΔρmin = 0.25 e Å3
Crystal data top
[Mn(C5H2N2O4)(H2O)2]V = 1481.5 (3) Å3
Mr = 245.06Z = 8
Orthorhombic, PbcaMo Kα radiation
a = 12.9325 (17) ŵ = 1.79 mm1
b = 6.7317 (9) ÅT = 273 K
c = 17.018 (2) Å0.20 × 0.10 × 0.10 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer
1303 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1998)
1132 reflections with I > 2σ(I)
Tmin = 0.716, Tmax = 0.841Rint = 0.034
7030 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0240 restraints
wR(F2) = 0.063H-atom parameters constrained
S = 1.07Δρmax = 0.32 e Å3
1303 reflectionsΔρmin = 0.25 e Å3
127 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 F^2^ against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F^2^, conventional R-factors R are based on F, with F set to zero for negative F^2^. The threshold expression of F^2^ > σ(F^2^) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F^2^ 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
Mn10.46146 (2)0.66790 (5)0.57158 (2)0.01867 (13)
C10.69138 (16)0.7457 (3)0.67430 (13)0.0158 (5)
C20.68969 (16)0.7992 (3)0.59174 (13)0.0159 (5)
C30.86893 (17)0.8237 (3)0.59028 (13)0.0165 (5)
C40.78584 (16)0.7290 (3)0.70827 (13)0.0172 (5)
H40.79050.69390.76100.021*
C50.59655 (17)0.7098 (3)0.72311 (13)0.0193 (5)
N10.77882 (14)0.8396 (3)0.55353 (11)0.0179 (4)
N20.87285 (14)0.7625 (3)0.66708 (11)0.0193 (4)
H20.93190.74520.68930.023*
O10.50967 (13)0.6861 (3)0.69090 (9)0.0267 (4)
O20.60727 (13)0.7022 (2)0.79643 (9)0.0266 (4)
O30.60651 (11)0.8146 (2)0.55292 (9)0.0223 (4)
O40.95410 (11)0.8632 (2)0.55584 (9)0.0204 (4)
O1W0.38407 (12)0.9545 (2)0.57592 (9)0.0235 (4)
H1WA0.39761.02360.61620.035*
H1WB0.38571.02730.53540.035*
O2W0.33088 (11)0.5072 (3)0.61325 (10)0.0288 (4)
H2WA0.27830.48540.58510.043*
H2WB0.34670.39980.63640.043*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Mn10.0158 (2)0.0237 (2)0.0164 (2)0.00110 (14)0.00145 (13)0.00042 (14)
C10.0184 (11)0.0144 (11)0.0145 (11)0.0003 (9)0.0012 (9)0.0001 (9)
C20.0167 (11)0.0146 (12)0.0164 (11)0.0006 (9)0.0003 (9)0.0003 (9)
C30.0182 (12)0.0143 (12)0.0170 (12)0.0006 (9)0.0028 (9)0.0032 (9)
C40.0227 (12)0.0150 (12)0.0137 (11)0.0006 (9)0.0013 (9)0.0013 (9)
C50.0246 (13)0.0149 (12)0.0184 (13)0.0010 (9)0.0021 (10)0.0003 (9)
N10.0166 (10)0.0222 (11)0.0149 (9)0.0033 (8)0.0001 (7)0.0005 (8)
N20.0156 (9)0.0252 (11)0.0170 (10)0.0002 (8)0.0032 (8)0.0032 (8)
O10.0189 (9)0.0421 (11)0.0191 (9)0.0032 (7)0.0012 (7)0.0011 (7)
O20.0337 (10)0.0345 (10)0.0117 (9)0.0057 (8)0.0012 (7)0.0007 (7)
O30.0153 (8)0.0331 (10)0.0184 (8)0.0035 (7)0.0044 (7)0.0077 (7)
O40.0150 (8)0.0271 (9)0.0190 (9)0.0046 (6)0.0040 (6)0.0006 (7)
O1W0.0287 (9)0.0248 (9)0.0168 (8)0.0021 (7)0.0012 (7)0.0008 (7)
O2W0.0183 (8)0.0370 (11)0.0310 (10)0.0036 (8)0.0047 (7)0.0074 (8)
Geometric parameters (Å, º) top
Mn1—O2W2.1271 (16)C3—N11.327 (3)
Mn1—O12.1278 (16)C3—N21.371 (3)
Mn1—O32.1437 (16)C4—N21.345 (3)
Mn1—O1W2.1748 (17)C4—H40.9300
Mn1—O4i2.1804 (16)C5—O21.257 (3)
Mn1—O4ii2.3392 (16)C5—O11.260 (3)
C1—C41.356 (3)N2—H20.8600
C1—C21.451 (3)O1W—H1WA0.8471
C1—C51.501 (3)O1W—H1WB0.8458
C2—O31.267 (3)O2W—H2WA0.8440
C2—N11.351 (3)O2W—H2WB0.8481
C3—O41.276 (3)
O2W—Mn1—O186.77 (6)N1—C3—N2120.39 (19)
O2W—Mn1—O3168.07 (6)N2—C4—C1121.2 (2)
O1—Mn1—O381.86 (6)N2—C4—H4119.4
O2W—Mn1—O1W94.27 (6)C1—C4—H4119.4
O1—Mn1—O1W92.94 (6)O2—C5—O1121.7 (2)
O3—Mn1—O1W89.94 (6)O2—C5—C1117.8 (2)
O2W—Mn1—O4i104.37 (6)O1—C5—C1120.5 (2)
O1—Mn1—O4i165.32 (6)C3—N1—C2120.41 (19)
O3—Mn1—O4i86.28 (6)C4—N2—C3121.08 (19)
O1W—Mn1—O4i95.67 (6)C4—N2—H2119.5
O2W—Mn1—O4ii87.87 (6)C3—N2—H2119.5
O1—Mn1—O4ii91.32 (6)C5—O1—Mn1133.12 (15)
O3—Mn1—O4ii88.77 (6)C2—O3—Mn1128.91 (14)
O1W—Mn1—O4ii175.33 (6)C3—O4—Mn1iii118.34 (14)
O4i—Mn1—O4ii79.77 (6)C3—O4—Mn1iv122.21 (13)
C4—C1—C2116.5 (2)Mn1iii—O4—Mn1iv100.23 (6)
C4—C1—C5119.1 (2)Mn1—O1W—H1WA114.8
C2—C1—C5124.32 (19)Mn1—O1W—H1WB118.4
O3—C2—N1117.19 (19)H1WA—O1W—H1WB109.7
O3—C2—C1122.57 (19)Mn1—O2W—H2WA122.6
N1—C2—C1120.22 (19)Mn1—O2W—H2WB113.4
O4—C3—N1121.7 (2)H2WA—O2W—H2WB108.0
O4—C3—N2117.9 (2)
Symmetry codes: (i) x1/2, y+3/2, z+1; (ii) x+3/2, y1/2, z; (iii) x+1/2, y+3/2, z+1; (iv) x+3/2, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2···O2v0.862.303.121 (2)160
N2—H2···O1v0.862.313.039 (2)143
O1W—H1WA···O2vi0.851.912.741 (2)165
O1W—H1WB···O3vii0.851.842.690 (2)178
O2W—H2WA···O1Wviii0.842.122.874 (2)149
O2W—H2WA···N1i0.842.643.094 (2)115
O2W—H2WB···O2ix0.851.852.687 (2)167
Symmetry codes: (i) x1/2, y+3/2, z+1; (v) x+1/2, y, z+3/2; (vi) x+1, y+1/2, z+3/2; (vii) x+1, y+2, z+1; (viii) x+1/2, y1/2, z; (ix) x+1, y1/2, z+3/2.

Experimental details

Crystal data
Chemical formula[Mn(C5H2N2O4)(H2O)2]
Mr245.06
Crystal system, space groupOrthorhombic, Pbca
Temperature (K)273
a, b, c (Å)12.9325 (17), 6.7317 (9), 17.018 (2)
V3)1481.5 (3)
Z8
Radiation typeMo Kα
µ (mm1)1.79
Crystal size (mm)0.20 × 0.10 × 0.10
Data collection
DiffractometerBruker SMART CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 1998)
Tmin, Tmax0.716, 0.841
No. of measured, independent and
observed [I > 2σ(I)] reflections
7030, 1303, 1132
Rint0.034
(sin θ/λ)max1)0.596
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.024, 0.063, 1.07
No. of reflections1303
No. of parameters127
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.32, 0.25

Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 1998), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1997) and DIAMOND (Brandenburg & Putz, 2004), SHELXTL (Bruker, 1998).

Selected geometric parameters (Å, º) top
Mn1—O2W2.1271 (16)Mn1—O1W2.1748 (17)
Mn1—O12.1278 (16)Mn1—O4i2.1804 (16)
Mn1—O32.1437 (16)Mn1—O4ii2.3392 (16)
O2W—Mn1—O186.77 (6)O3—Mn1—O4i86.28 (6)
O2W—Mn1—O3168.07 (6)O1W—Mn1—O4i95.67 (6)
O1—Mn1—O381.86 (6)O2W—Mn1—O4ii87.87 (6)
O2W—Mn1—O1W94.27 (6)O1—Mn1—O4ii91.32 (6)
O1—Mn1—O1W92.94 (6)O3—Mn1—O4ii88.77 (6)
O3—Mn1—O1W89.94 (6)O1W—Mn1—O4ii175.33 (6)
O2W—Mn1—O4i104.37 (6)O4i—Mn1—O4ii79.77 (6)
O1—Mn1—O4i165.32 (6)Mn1iii—O4—Mn1iv100.23 (6)
Symmetry codes: (i) x1/2, y+3/2, z+1; (ii) x+3/2, y1/2, z; (iii) x+1/2, y+3/2, z+1; (iv) x+3/2, y+1/2, z.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2···O2v0.862.303.121 (2)160.0
N2—H2···O1v0.862.313.039 (2)142.9
O1W—H1WA···O2vi0.851.912.741 (2)165.4
O1W—H1WB···O3vii0.851.842.690 (2)178.2
O2W—H2WA···O1Wviii0.842.122.874 (2)149.1
O2W—H2WA···N1i0.842.643.094 (2)115.3
O2W—H2WB···O2ix0.851.852.687 (2)167.4
Symmetry codes: (i) x1/2, y+3/2, z+1; (v) x+1/2, y, z+3/2; (vi) x+1, y+1/2, z+3/2; (vii) x+1, y+2, z+1; (viii) x+1/2, y1/2, z; (ix) x+1, y1/2, z+3/2.
 

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