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Acta Cryst. (2009). E65, m308-m309    [ doi:10.1107/S1600536809005637 ]

Potassium oxalurate monohydrate

L.-F. Zhang

Abstract top

The title salt, poly[aqua-[mu]3-oxalurato-potassium(I)], [K(C3H3N2O4)(H2O)]n, which was obtained from a water solution of oxaluric acid and KOH at room temperature, crystallizes as potassium and oxalurate ions along with a water molecule. The K+ cation lies on a crystallographic twofold rotation axis (site symmetry 2, Wyckoff position f), and the water and oxalurate molecules are located within different mirror planes (site symmetry m, Wyckoff position g). The K+ cation is eight-coordinated by six O atoms of six oxalurate ligands and two O atoms from two water molecules in a distorted square-antiprismatic geometry. All of the eight coordinated O atoms are in a monodentate bridging mode, with alternate bridged K...K distances of 3.5575 (12) and 3.3738 (12) Å. The oxalurate ligand shows a [mu]3-bridging coordination mode, which links the K+ cation into a three-dimensional network. The oxalurate ligands and the water molecules are involved in inter- and intramolecular N-H...O, and O-H...O hydrogen bonds, which stabilize the network.

Comment top

Oxaluric acid is the condensation product of oxalic acid and urea. Deprotonated oxalurate possesses four oxygen atoms and two amine N atoms, which can serve as hydrogen-bond acceptors and hydrogen-bond donors, respectively. In addition, one or more of six different atoms can bind to metal centers in any of at least three distinct coordination modes, namely, chelating, terminal, or bridging coordination (Falvello, 2002).

As shown in Fig. 1, the asymmetric structure unit consists of one K+ cation, one C3H3N2O4- anion, and one water molecule. The K+ cation is surrounded by six oxalurate ligands and two water molecules, making close contacts with eight O atoms at 2.7291 (11)–2.9775 (13) A ° in a distorted square antiprismatic geometry of the central atom (Karapetyan, 2008; Kunz, 2009) (Table 1). All the eight coordinated O atoms are in the monodentate bridging mode, with the bridged K···K distance of 3.558 (1) and 3.374 (1) Å alternately. The oxalurate ligand, which is planar, shows a µ3-bridging coordination mode and links the K+ cation into a three-dimensional network (Fig. 2). The oxalurate ligands and water molecules are involved in inter- and intramolecular N—H···O, and O—H···O hydrogen bonds, which stabilize the network (Table 2).

Related literature top

For oxalurate metal complexes, see: Falvello et al. (2002). For elongated K—O bonds, see: Karapetyan (2008); Kunz et al. (2009).

Experimental top

A 10 ml sample of a KOH solution (0.5 mol/L) was added to a water suspension of oxaluric acid, HOOCCONHCONH2 (0.5 mmol/10 ml). The KOH addition produced a partial solubilization of the acid and then the precipitation of a white solid. After 20 min of stirring, the solid was filtered off, washed with i-PrOH. The single crystals suitable for X-ray analysis were obtained by slow diffusion of Et2O into the water solution of the solid.

Refinement top

Water H atoms were located in a difference Fourier and allowed to ride at the value approximately 0.83 Å with Uiso(H) = 1.5Ueq(O). Other H atoms were positioned geometrically and treated as riding, with N—H = 0.86 Å (NH and NH2) and Uiso(H) = 1.2Ueq(N).

Computing details top

Data collection: SMART (Bruker, 1997); cell refinement: SAINT (Bruker, 1997); data reduction: SAINT (Bruker, 1997); 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: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. A perspective view of the asymmetric unit, showing the atomic numbering and displacement ellipsoids drawn at the 30% probability level.
[Figure 2] Fig. 2. A view of the compound packing down the a axis.
poly[aqua-µ3-oxalurato-potassium(I)] top
Crystal data top
[K(C3H3N2O4)(H2O)]F(000) = 384
Mr = 188.19Dx = 1.823 Mg m−3
Orthorhombic, PnnmMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2 2nCell parameters from 1939 reflections
a = 7.7313 (17) Åθ = 2.9–28.2°
b = 12.799 (3) ŵ = 0.75 mm−1
c = 6.9313 (16) ÅT = 296 K
V = 685.9 (3) Å3Block, pink
Z = 40.41 × 0.39 × 0.28 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer		699 independent reflections
Radiation source: fine-focus sealed tube633 reflections with I > 2σ(I)
graphiteRint = 0.013
φ and ω scansθmax = 25.5°, θmin = 3.1°
Absorption correction: multi-scan
(SADABS; Bruker, 1997)		h = −9→9
Tmin = 0.748, Tmax = 0.816k = −15→15
3320 measured reflectionsl = −8→6
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)] = 0.026Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.077H-atom parameters constrained
S = 1.09 w = 1/[σ2(Fo2) + (0.0457P)2 + 0.2142P]
where P = (Fo2 + 2Fc2)/3
699 reflections(Δ/σ)max < 0.001
66 parametersΔρmax = 0.17 e Å−3
0 restraintsΔρmin = −0.34 e Å−3
Crystal data top
[K(C3H3N2O4)(H2O)]V = 685.9 (3) Å3
Mr = 188.19Z = 4
Orthorhombic, PnnmMo Kα radiation
a = 7.7313 (17) ŵ = 0.75 mm−1
b = 12.799 (3) ÅT = 296 K
c = 6.9313 (16) Å0.41 × 0.39 × 0.28 mm
Data collection top
Bruker SMART CCD area-detector
diffractometer		699 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1997)		633 reflections with I > 2σ(I)
Tmin = 0.748, Tmax = 0.816Rint = 0.013
3320 measured reflectionsθmax = 25.5°
Refinement top
R[F2 > 2σ(F2)] = 0.026H-atom parameters constrained
wR(F2) = 0.077Δρmax = 0.17 e Å−3
S = 1.09Δρmin = −0.34 e Å−3
699 reflectionsAbsolute structure: ?
66 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
K11.00000.50000.24337 (6)0.0336 (2)
O10.89541 (18)0.34475 (10)0.00000.0329 (4)
O20.90620 (19)0.17010 (11)0.00000.0478 (5)
O30.55768 (18)0.16337 (10)0.00000.0349 (4)
O40.30509 (18)0.44721 (10)0.00000.0396 (4)
N10.5439 (2)0.34235 (12)0.00000.0278 (4)
H10.60690.39770.00000.033*
N20.2646 (2)0.27328 (14)0.00000.0414 (5)
H2A0.15380.27940.00000.050*
H2B0.31110.21220.00000.050*
C10.8300 (3)0.25554 (15)0.00000.0266 (5)
C20.6290 (2)0.24914 (14)0.00000.0239 (4)
C30.3632 (2)0.35754 (14)0.00000.0281 (5)
O50.7184 (2)0.46547 (13)0.50000.0490 (5)
H1W0.69190.52840.50000.073*
H2W0.62980.42870.50000.073*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
K10.0406 (3)0.0241 (3)0.0362 (4)−0.00314 (16)0.0000.000
O10.0213 (7)0.0206 (7)0.0567 (10)−0.0038 (5)0.0000.000
O20.0210 (7)0.0224 (7)0.0999 (15)0.0037 (6)0.0000.000
O30.0226 (7)0.0171 (7)0.0650 (11)−0.0027 (6)0.0000.000
O40.0227 (7)0.0203 (7)0.0758 (12)0.0033 (6)0.0000.000
N10.0175 (8)0.0165 (8)0.0493 (11)−0.0020 (6)0.0000.000
N20.0172 (8)0.0219 (8)0.0852 (16)0.0006 (7)0.0000.000
C10.0194 (10)0.0224 (9)0.0379 (11)−0.0015 (7)0.0000.000
C20.0197 (10)0.0190 (9)0.0330 (11)−0.0007 (7)0.0000.000
C30.0184 (9)0.0221 (9)0.0438 (13)0.0014 (7)0.0000.000
O50.0247 (8)0.0271 (8)0.0952 (14)0.0024 (7)0.0000.000
Geometric parameters (Å, °) top
K1—O12.7291 (11)O3—K1vii2.7812 (11)
K1—O1i2.7291 (11)O3—K1viii2.7812 (11)
K1—O3ii2.7812 (11)O4—C31.232 (2)
K1—O3iii2.7812 (11)O4—K1v2.9775 (13)
K1—O5iv2.8458 (13)O4—K1ix2.9775 (13)
K1—O52.8458 (13)N1—C21.362 (2)
K1—O4v2.9775 (13)N1—C31.410 (2)
K1—O4vi2.9775 (13)N1—H10.8600
K1—K1i3.3738 (12)N2—C31.321 (3)
K1—K1iv3.5575 (12)N2—H2A0.8600
K1—H1W2.9950N2—H2B0.8600
O1—C11.249 (2)C1—C21.556 (3)
O1—K1i2.7291 (11)O5—K1iv2.8458 (13)
O2—C11.242 (2)O5—H1W0.8312
O3—C21.228 (2)O5—H2W0.8317
O1—K1—O1i103.64 (4)O3ii—K1—K1iv50.24 (2)
O1—K1—O3ii153.54 (4)O3iii—K1—K1iv50.24 (2)
O1i—K1—O3ii84.00 (3)O5iv—K1—K1iv51.32 (2)
O1—K1—O3iii84.00 (3)O5—K1—K1iv51.32 (2)
O1i—K1—O3iii153.54 (4)O4v—K1—K1iv124.509 (19)
O3ii—K1—O3iii100.48 (4)O4vi—K1—K1iv124.509 (19)
O1—K1—O5iv136.56 (4)K1i—K1—K1iv180.0
O1i—K1—O5iv92.67 (4)C1—O1—K1141.79 (2)
O3ii—K1—O5iv66.81 (4)C1—O1—K1i141.79 (2)
O3iii—K1—O5iv66.07 (4)K1—O1—K1i76.36 (4)
O1—K1—O592.67 (4)C2—O3—K1vii138.06 (4)
O1i—K1—O5136.56 (4)C2—O3—K1viii138.06 (4)
O3ii—K1—O566.07 (4)K1vii—O3—K1viii79.52 (4)
O3iii—K1—O566.81 (4)C3—O4—K1v120.01 (9)
O5iv—K1—O5102.63 (4)C3—O4—K1ix120.01 (9)
O1—K1—O4v65.19 (4)K1v—O4—K1ix69.02 (4)
O1i—K1—O4v73.70 (4)C2—N1—C3126.81 (16)
O3ii—K1—O4v93.71 (3)C2—N1—H1116.6
O3iii—K1—O4v131.30 (4)C3—N1—H1116.6
O5iv—K1—O4v157.65 (5)C3—N2—H2A120.0
O5—K1—O4v77.49 (3)C3—N2—H2B120.0
O1—K1—O4vi73.70 (4)H2A—N2—H2B120.0
O1i—K1—O4vi65.19 (4)O2—C1—O1127.80 (18)
O3ii—K1—O4vi131.30 (4)O2—C1—C2115.29 (17)
O3iii—K1—O4vi93.71 (3)O1—C1—C2116.91 (17)
O5iv—K1—O4vi77.49 (3)O3—C2—N1124.44 (17)
O5—K1—O4vi157.65 (5)O3—C2—C1119.70 (17)
O4v—K1—O4vi110.98 (4)N1—C2—C1115.87 (16)
O1—K1—K1i51.82 (2)O4—C3—N2123.36 (18)
O1i—K1—K1i51.82 (2)O4—C3—N1119.31 (17)
O3ii—K1—K1i129.76 (2)N2—C3—N1117.34 (17)
O3iii—K1—K1i129.76 (2)K1iv—O5—K177.37 (4)
O5iv—K1—K1i128.68 (2)K1iv—O5—H1W92.2
O5—K1—K1i128.68 (2)K1—O5—H1W92.2
O4v—K1—K1i55.491 (19)K1iv—O5—H2W135.9
O4vi—K1—K1i55.491 (19)K1—O5—H2W135.9
O1—K1—K1iv128.18 (2)H1W—O5—H2W110.2
O1i—K1—K1iv128.18 (2)
O1i—K1—O1—C1−177.2 (2)K1vii—O3—C2—C1−73.10 (14)
O3ii—K1—O1—C1−72.9 (2)K1viii—O3—C2—C173.10 (14)
O3iii—K1—O1—C128.56 (19)C3—N1—C2—O30.0
O5iv—K1—O1—C173.8 (2)C3—N1—C2—C1180.0
O5—K1—O1—C1−37.78 (19)O2—C1—C2—O30.0
O4v—K1—O1—C1−112.67 (19)O1—C1—C2—O3180.0
O4vi—K1—O1—C1124.22 (19)O2—C1—C2—N1180.0
K1i—K1—O1—C1−177.2 (2)O1—C1—C2—N10.0
K1iv—K1—O1—C12.8 (2)K1v—O4—C3—N2−40.86 (6)
O1i—K1—O1—K1i0.0K1ix—O4—C3—N240.86 (6)
O3ii—K1—O1—K1i104.25 (5)K1v—O4—C3—N1139.14 (6)
O3iii—K1—O1—K1i−154.26 (4)K1ix—O4—C3—N1−139.14 (6)
O5iv—K1—O1—K1i−109.03 (4)C2—N1—C3—O4180.0
O5—K1—O1—K1i139.40 (3)C2—N1—C3—N20.0
O4v—K1—O1—K1i64.50 (3)O1—K1—O5—K1iv139.06 (3)
O4vi—K1—O1—K1i−58.60 (3)O1i—K1—O5—K1iv−107.82 (4)
K1iv—K1—O1—K1i180.0O3ii—K1—O5—K1iv−57.25 (3)
K1—O1—C1—O2−92.22 (16)O3iii—K1—O5—K1iv56.75 (3)
K1i—O1—C1—O292.22 (16)O5iv—K1—O5—K1iv0.0
K1—O1—C1—C287.78 (16)O4v—K1—O5—K1iv−157.09 (5)
K1i—O1—C1—C2−87.78 (16)O4vi—K1—O5—K1iv87.77 (8)
K1vii—O3—C2—N1106.90 (14)K1i—K1—O5—K1iv180.0
K1viii—O3—C2—N1−106.90 (14)
Symmetry codes: (i) −x+2, −y+1, −z; (ii) −x+3/2, y+1/2, −z+1/2; (iii) x+1/2, −y+1/2, z+1/2; (iv) −x+2, −y+1, −z+1; (v) −x+1, −y+1, −z; (vi) x+1, y, z; (vii) x−1/2, −y+1/2, z−1/2; (viii) −x+3/2, y−1/2, −z+1/2; (ix) x−1, y, z.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O4v0.862.102.936 (2)164
N2—H2A···O1ix0.862.172.997 (2)163
N2—H2A···O2ix0.862.373.069 (2)139
N2—H2B···O30.862.012.667 (2)133
N2—H2B···O5vii0.862.383.076 (3)138
O5—H1W···O2ii0.831.972.791 (2)172
O5—H1W···O3ii0.832.593.068 (2)118
O5—H2W···O2x0.832.142.973 (2)178
Symmetry codes: (v) −x+1, −y+1, −z; (ix) x−1, y, z; (vii) x−1/2, −y+1/2, z−1/2; (ii) −x+3/2, y+1/2, −z+1/2; (x) x−1/2, −y+1/2, z+1/2.
Table 1
Selected geometric parameters (Å) top
K1—O12.7291 (11)K1—O52.8458 (13)
K1—O3i2.7812 (11)K1—O4ii2.9775 (13)
Symmetry codes: (i) −x+3/2, y+1/2, −z+1/2; (ii) x+1, y, z.
Table 2
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O4iii0.862.102.936 (2)164
N2—H2A···O1iv0.862.172.997 (2)163
N2—H2A···O2iv0.862.373.069 (2)139
N2—H2B···O30.862.012.667 (2)133
N2—H2B···O5v0.862.383.076 (3)138
O5—H1W···O2i0.831.972.791 (2)172
O5—H1W···O3i0.832.593.068 (2)118
O5—H2W···O2vi0.832.142.973 (2)178
Symmetry codes: (iii) −x+1, −y+1, −z; (iv) x−1, y, z; (v) x−1/2, −y+1/2, z−1/2; (i) −x+3/2, y+1/2, −z+1/2; (vi) x−1/2, −y+1/2, z+1/2.
Acknowledgements top

The authors thank Nan Yang Normal University for supporting this work.

references
References top

Bruker (1997). SMART, SAINT and SADABS. Bruker AXS Inc., Madison,Wisconsin, USA.

Falvello, L. R., Garde, R. & Tomás, M. (2002). Inorg. Chem. 41, 4599–4604.

Karapetyan, H. A. (2008). Acta Cryst. E64, m1369.

Kunz, K., Lerner, H.-W. & Bolte, M. (2009). Acta Cryst. E65, m171.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.