Potassium oxalurate monohydrate

Abstract

The title salt, poly[aqua-μ₃-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 μ₃-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.

Related literature

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

Experimental

Crystal data

• [K(C₃H₃N₂O₄)(H₂O)]

• M _r = 188.19

• Orthorhombic,

• a = 7.7313 (17) Å

• b = 12.799 (3) Å

• c = 6.9313 (16) Å

• V = 685.9 (3) ų

• Z = 4

• Mo Kα radiation

• μ = 0.75 mm⁻¹

• T = 296 K

• 0.41 × 0.39 × 0.28 mm

Data collection

• Bruker SMART CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 1997 ▶) T _min = 0.748, T _max = 0.816

• 3320 measured reflections

• 699 independent reflections

• 633 reflections with I > 2σ(I)

• R _int = 0.013

Refinement

• R[F ² > 2σ(F ²)] = 0.026

• wR(F ²) = 0.077

• S = 1.09

• 699 reflections

• 66 parameters

• H-atom parameters constrained

• Δρ_max = 0.17 e Å⁻³

• Δρ_min = −0.34 e Å⁻³

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

Supplementary Material

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

Table 1. Selected bond lengths (Å).

K1—O1	2.7291 (11)
K1—O3i	2.7812 (11)
K1—O5	2.8458 (13)
K1—O4ii	2.9775 (13)

Symmetry codes: (i) ; (ii) .

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O4iii	0.86	2.10	2.936 (2)	164
N2—H2A⋯O1iv	0.86	2.17	2.997 (2)	163
N2—H2A⋯O2iv	0.86	2.37	3.069 (2)	139
N2—H2B⋯O3	0.86	2.01	2.667 (2)	133
N2—H2B⋯O5v	0.86	2.38	3.076 (3)	138
O5—H1W⋯O2i	0.83	1.97	2.791 (2)	172
O5—H1W⋯O3i	0.83	2.59	3.068 (2)	118
O5—H2W⋯O2vi	0.83	2.14	2.973 (2)	178

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

supplementary crystallographic information

Comment

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).

Experimental

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

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

Figures

Fig. 1.

A perspective view of the asymmetric unit, showing the atomic numbering and displacement ellipsoids drawn at the 30% probability level.

Fig. 2.

A view of the compound packing down the a axis.

Crystal data

[K(C3H3N2O4)(H2O)]	F(000) = 384
Mr = 188.19	Dx = 1.823 Mg m−3
Orthorhombic, Pnnm	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2 2n	Cell parameters from 1939 reflections
a = 7.7313 (17) Å	θ = 2.9–28.2°
b = 12.799 (3) Å	µ = 0.75 mm−1
c = 6.9313 (16) Å	T = 296 K
V = 685.9 (3) Å3	Block, pink
Z = 4	0.41 × 0.39 × 0.28 mm

Data collection

Bruker SMART CCD area-detector diffractometer	699 independent reflections
Radiation source: fine-focus sealed tube	633 reflections with I > 2σ(I)
graphite	Rint = 0.013
φ and ω scans	θmax = 25.5°, θmin = 3.1°
Absorption correction: multi-scan (SADABS; Bruker, 1997)	h = −9→9
Tmin = 0.748, Tmax = 0.816	k = −15→15
3320 measured reflections	l = −8→6

Refinement

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)] = 0.026	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.077	H-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 parameters	Δρmax = 0.17 e Å−3
0 restraints	Δρmin = −0.34 e Å−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
K1	1.0000	0.5000	0.24337 (6)	0.0336 (2)
O1	0.89541 (18)	0.34475 (10)	0.0000	0.0329 (4)
O2	0.90620 (19)	0.17010 (11)	0.0000	0.0478 (5)
O3	0.55768 (18)	0.16337 (10)	0.0000	0.0349 (4)
O4	0.30509 (18)	0.44721 (10)	0.0000	0.0396 (4)
N1	0.5439 (2)	0.34235 (12)	0.0000	0.0278 (4)
H1	0.6069	0.3977	0.0000	0.033*
N2	0.2646 (2)	0.27328 (14)	0.0000	0.0414 (5)
H2A	0.1538	0.2794	0.0000	0.050*
H2B	0.3111	0.2122	0.0000	0.050*
C1	0.8300 (3)	0.25554 (15)	0.0000	0.0266 (5)
C2	0.6290 (2)	0.24914 (14)	0.0000	0.0239 (4)
C3	0.3632 (2)	0.35754 (14)	0.0000	0.0281 (5)
O5	0.7184 (2)	0.46547 (13)	0.5000	0.0490 (5)
H1W	0.6919	0.5284	0.5000	0.073*
H2W	0.6298	0.4287	0.5000	0.073*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
K1	0.0406 (3)	0.0241 (3)	0.0362 (4)	−0.00314 (16)	0.000	0.000
O1	0.0213 (7)	0.0206 (7)	0.0567 (10)	−0.0038 (5)	0.000	0.000
O2	0.0210 (7)	0.0224 (7)	0.0999 (15)	0.0037 (6)	0.000	0.000
O3	0.0226 (7)	0.0171 (7)	0.0650 (11)	−0.0027 (6)	0.000	0.000
O4	0.0227 (7)	0.0203 (7)	0.0758 (12)	0.0033 (6)	0.000	0.000
N1	0.0175 (8)	0.0165 (8)	0.0493 (11)	−0.0020 (6)	0.000	0.000
N2	0.0172 (8)	0.0219 (8)	0.0852 (16)	0.0006 (7)	0.000	0.000
C1	0.0194 (10)	0.0224 (9)	0.0379 (11)	−0.0015 (7)	0.000	0.000
C2	0.0197 (10)	0.0190 (9)	0.0330 (11)	−0.0007 (7)	0.000	0.000
C3	0.0184 (9)	0.0221 (9)	0.0438 (13)	0.0014 (7)	0.000	0.000
O5	0.0247 (8)	0.0271 (8)	0.0952 (14)	0.0024 (7)	0.000	0.000

Geometric parameters (Å, °)

K1—O1	2.7291 (11)	O3—K1vii	2.7812 (11)
K1—O1i	2.7291 (11)	O3—K1viii	2.7812 (11)
K1—O3ii	2.7812 (11)	O4—C3	1.232 (2)
K1—O3iii	2.7812 (11)	O4—K1v	2.9775 (13)
K1—O5iv	2.8458 (13)	O4—K1ix	2.9775 (13)
K1—O5	2.8458 (13)	N1—C2	1.362 (2)
K1—O4v	2.9775 (13)	N1—C3	1.410 (2)
K1—O4vi	2.9775 (13)	N1—H1	0.8600
K1—K1i	3.3738 (12)	N2—C3	1.321 (3)
K1—K1iv	3.5575 (12)	N2—H2A	0.8600
K1—H1W	2.9950	N2—H2B	0.8600
O1—C1	1.249 (2)	C1—C2	1.556 (3)
O1—K1i	2.7291 (11)	O5—K1iv	2.8458 (13)
O2—C1	1.242 (2)	O5—H1W	0.8312
O3—C2	1.228 (2)	O5—H2W	0.8317
O1—K1—O1i	103.64 (4)	O3ii—K1—K1iv	50.24 (2)
O1—K1—O3ii	153.54 (4)	O3iii—K1—K1iv	50.24 (2)
O1i—K1—O3ii	84.00 (3)	O5iv—K1—K1iv	51.32 (2)
O1—K1—O3iii	84.00 (3)	O5—K1—K1iv	51.32 (2)
O1i—K1—O3iii	153.54 (4)	O4v—K1—K1iv	124.509 (19)
O3ii—K1—O3iii	100.48 (4)	O4vi—K1—K1iv	124.509 (19)
O1—K1—O5iv	136.56 (4)	K1i—K1—K1iv	180.0
O1i—K1—O5iv	92.67 (4)	C1—O1—K1	141.79 (2)
O3ii—K1—O5iv	66.81 (4)	C1—O1—K1i	141.79 (2)
O3iii—K1—O5iv	66.07 (4)	K1—O1—K1i	76.36 (4)
O1—K1—O5	92.67 (4)	C2—O3—K1vii	138.06 (4)
O1i—K1—O5	136.56 (4)	C2—O3—K1viii	138.06 (4)
O3ii—K1—O5	66.07 (4)	K1vii—O3—K1viii	79.52 (4)
O3iii—K1—O5	66.81 (4)	C3—O4—K1v	120.01 (9)
O5iv—K1—O5	102.63 (4)	C3—O4—K1ix	120.01 (9)
O1—K1—O4v	65.19 (4)	K1v—O4—K1ix	69.02 (4)
O1i—K1—O4v	73.70 (4)	C2—N1—C3	126.81 (16)
O3ii—K1—O4v	93.71 (3)	C2—N1—H1	116.6
O3iii—K1—O4v	131.30 (4)	C3—N1—H1	116.6
O5iv—K1—O4v	157.65 (5)	C3—N2—H2A	120.0
O5—K1—O4v	77.49 (3)	C3—N2—H2B	120.0
O1—K1—O4vi	73.70 (4)	H2A—N2—H2B	120.0
O1i—K1—O4vi	65.19 (4)	O2—C1—O1	127.80 (18)
O3ii—K1—O4vi	131.30 (4)	O2—C1—C2	115.29 (17)
O3iii—K1—O4vi	93.71 (3)	O1—C1—C2	116.91 (17)
O5iv—K1—O4vi	77.49 (3)	O3—C2—N1	124.44 (17)
O5—K1—O4vi	157.65 (5)	O3—C2—C1	119.70 (17)
O4v—K1—O4vi	110.98 (4)	N1—C2—C1	115.87 (16)
O1—K1—K1i	51.82 (2)	O4—C3—N2	123.36 (18)
O1i—K1—K1i	51.82 (2)	O4—C3—N1	119.31 (17)
O3ii—K1—K1i	129.76 (2)	N2—C3—N1	117.34 (17)
O3iii—K1—K1i	129.76 (2)	K1iv—O5—K1	77.37 (4)
O5iv—K1—K1i	128.68 (2)	K1iv—O5—H1W	92.2
O5—K1—K1i	128.68 (2)	K1—O5—H1W	92.2
O4v—K1—K1i	55.491 (19)	K1iv—O5—H2W	135.9
O4vi—K1—K1i	55.491 (19)	K1—O5—H2W	135.9
O1—K1—K1iv	128.18 (2)	H1W—O5—H2W	110.2
O1i—K1—K1iv	128.18 (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—C1	73.10 (14)
O3iii—K1—O1—C1	28.56 (19)	C3—N1—C2—O3	0.0
O5iv—K1—O1—C1	73.8 (2)	C3—N1—C2—C1	180.0
O5—K1—O1—C1	−37.78 (19)	O2—C1—C2—O3	0.0
O4v—K1—O1—C1	−112.67 (19)	O1—C1—C2—O3	180.0
O4vi—K1—O1—C1	124.22 (19)	O2—C1—C2—N1	180.0
K1i—K1—O1—C1	−177.2 (2)	O1—C1—C2—N1	0.0
K1iv—K1—O1—C1	2.8 (2)	K1v—O4—C3—N2	−40.86 (6)
O1i—K1—O1—K1i	0.0	K1ix—O4—C3—N2	40.86 (6)
O3ii—K1—O1—K1i	104.25 (5)	K1v—O4—C3—N1	139.14 (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—O4	180.0
O5—K1—O1—K1i	139.40 (3)	C2—N1—C3—N2	0.0
O4v—K1—O1—K1i	64.50 (3)	O1—K1—O5—K1iv	139.06 (3)
O4vi—K1—O1—K1i	−58.60 (3)	O1i—K1—O5—K1iv	−107.82 (4)
K1iv—K1—O1—K1i	180.0	O3ii—K1—O5—K1iv	−57.25 (3)
K1—O1—C1—O2	−92.22 (16)	O3iii—K1—O5—K1iv	56.75 (3)
K1i—O1—C1—O2	92.22 (16)	O5iv—K1—O5—K1iv	0.0
K1—O1—C1—C2	87.78 (16)	O4v—K1—O5—K1iv	−157.09 (5)
K1i—O1—C1—C2	−87.78 (16)	O4vi—K1—O5—K1iv	87.77 (8)
K1vii—O3—C2—N1	106.90 (14)	K1i—K1—O5—K1iv	180.0
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, °)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O4v	0.86	2.10	2.936 (2)	164
N2—H2A···O1ix	0.86	2.17	2.997 (2)	163
N2—H2A···O2ix	0.86	2.37	3.069 (2)	139
N2—H2B···O3	0.86	2.01	2.667 (2)	133
N2—H2B···O5vii	0.86	2.38	3.076 (3)	138
O5—H1W···O2ii	0.83	1.97	2.791 (2)	172
O5—H1W···O3ii	0.83	2.59	3.068 (2)	118
O5—H2W···O2x	0.83	2.14	2.973 (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.