The Co
II ion in the title complex {[Co(C
5H
2N
2O
4)(H
2O)
3]·1.72H
2O}
n, has a distorted octahedral coordination geometry comprised of three water ligands, one deprotonated pyrimidine N atom and an adjacent carboxylate O atom of one orotate ligand. The sixth coordination site is occupied by an exocyclic O atom from a neighbouring orotate moiety, and through this interaction a helicoidal chain is formed. The molecules are linked by intramolecular O
water—H
O and intermolecular N—H
O and O
water—H
O hydrogen bonds, forming a three-dimensional network.
Supporting information
CCDC reference: 628495
A solution of Co(CH3COO)2·H2O (1 mmol) in water (Volume?) was added to a solution of orotic acid (2 mmol) [In what? Volume?]. The solution was heated at 338 K and stirred for 1 d to remove CH3COOH. The mixture was then left for crystallization. After two weeks, the product obtained was filtered off and dried in air. Analysis calculated for C5H10CoN2O9: C 21.0, H 3.50, N 9.8%; found: C 20.32, H 4.09, N 9.12%. IR (KBr, ν, cm−1): 3390–3100 (b), 1652 (vs), 1605 (sh), 1376 (m), 1480 (w), 1021 (m).
H atoms bonded to C and N atoms were included in their expected positions and allowed to ride, with C—H and N—H distances restrained to 0.93 and 0.86 Å, respectively. Aqua H atoms were located in difference maps and refined subject to a DFIX restraint of O—H = 0.83 (3) Å. In all cases, H atoms were assigned a Uiso(H) value of 1.2Ueq of the parent atom. Attempts to refine O9 resulted in a partial occupancy of 0.716, which was later fixed at 0.72. The H atoms attached to non-coordinated water molecules O8 and O9 could not be located, though they appeared to be involved in strong hydrogen bonding to a neighbouring O atom.
Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED (Stoe & Cie, 2002); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
catena-Poly[[[triaquacobalt(II)]-µ-2,6-dioxo-1,2,3,6-tetrahydropyrimidine- 4-carboxylato(2-)] 1.72-hydrate]
top
Crystal data top
[Co(C5H2N2O4)(H2O)3]·1.72H2O | Dx = 1.893 Mg m−3 |
Mr = 294.6 | Mo Kα radiation, λ = 0.71073 Å |
Hexagonal, P61 | Cell parameters from 5840 reflections |
Hall symbol: P 61 | θ = 2.1–28.0° |
a = 13.4646 (12) Å | µ = 1.70 mm−1 |
c = 9.8777 (7) Å | T = 100 K |
V = 1550.9 (2) Å3 | Rod, brown |
Z = 6 | 0.50 × 0.30 × 0.10 mm |
F(000) = 892.6 | |
Data collection top
Stoe IPDS II diffractometer | 1993 independent reflections |
Radiation source: fine-focus sealed tube | 1810 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.036 |
Detector resolution: 6.67 pixels mm-1 | θmax = 26.0°, θmin = 2.7° |
ω scans | h = −16→11 |
Absorption correction: integration (X-RED32; Stoe & Cie, 2002) | k = −10→16 |
Tmin = 0.672, Tmax = 0.875 | l = −12→11 |
5840 measured reflections | |
Refinement top
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.038 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.087 | w = 1/[σ2(Fo2) + (0.0318P)2 + 3.8738P] where P = (Fo2 + 2Fc2)/3 |
S = 1.06 | (Δ/σ)max = 0.003 |
1993 reflections | Δρmax = 0.92 e Å−3 |
173 parameters | Δρmin = −0.94 e Å−3 |
10 restraints | Absolute structure: Flack (1983), with how many Friedel pairs? |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.03 (3) |
Crystal data top
[Co(C5H2N2O4)(H2O)3]·1.72H2O | Z = 6 |
Mr = 294.6 | Mo Kα radiation |
Hexagonal, P61 | µ = 1.70 mm−1 |
a = 13.4646 (12) Å | T = 100 K |
c = 9.8777 (7) Å | 0.50 × 0.30 × 0.10 mm |
V = 1550.9 (2) Å3 | |
Data collection top
Stoe IPDS II diffractometer | 1993 independent reflections |
Absorption correction: integration (X-RED32; Stoe & Cie, 2002) | 1810 reflections with I > 2σ(I) |
Tmin = 0.672, Tmax = 0.875 | Rint = 0.036 |
5840 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.038 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.087 | Δρmax = 0.92 e Å−3 |
S = 1.06 | Δρmin = −0.94 e Å−3 |
1993 reflections | Absolute structure: Flack (1983), with how many Friedel pairs? |
173 parameters | Absolute structure parameter: −0.03 (3) |
10 restraints | |
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 | x | y | z | Uiso*/Ueq | Occ. (<1) |
Co1 | 0.59523 (5) | 0.67470 (5) | 0.72113 (7) | 0.01434 (15) | |
O1W | 0.6577 (3) | 0.6615 (3) | 0.5343 (4) | 0.0222 (8) | |
H1A | 0.704 (4) | 0.712 (3) | 0.483 (5) | 0.027* | |
H1B | 0.663 (5) | 0.604 (3) | 0.514 (5) | 0.027* | |
O2W | 0.5519 (3) | 0.6990 (3) | 0.9127 (4) | 0.0212 (8) | |
H2A | 0.484 (2) | 0.665 (4) | 0.931 (6) | 0.025* | |
H2B | 0.571 (4) | 0.763 (3) | 0.951 (6) | 0.025* | |
O3W | 0.7725 (3) | 0.7854 (3) | 0.7721 (4) | 0.0206 (8) | |
H3A | 0.793 (5) | 0.831 (4) | 0.836 (4) | 0.025* | |
H3B | 0.782 (5) | 0.733 (3) | 0.797 (5) | 0.025* | |
C1 | 0.6696 (4) | 0.5010 (4) | 0.8005 (5) | 0.0146 (9) | |
C2 | 0.5448 (4) | 0.2936 (4) | 0.8008 (5) | 0.0131 (9) | |
C3 | 0.4556 (4) | 0.3141 (4) | 0.7586 (5) | 0.0155 (10) | |
H3 | 0.3826 | 0.2533 | 0.7402 | 0.019* | |
C4 | 0.4793 (4) | 0.4242 (4) | 0.7456 (5) | 0.0159 (9) | |
C5 | 0.3882 (4) | 0.4531 (4) | 0.6992 (5) | 0.0151 (9) | |
N1 | 0.5834 (3) | 0.5176 (3) | 0.7676 (4) | 0.0133 (8) | |
N2 | 0.6494 (3) | 0.3913 (3) | 0.8172 (4) | 0.0146 (8) | |
H2 | 0.7065 | 0.3830 | 0.8396 | 0.017* | |
O4 | 0.4236 (3) | 0.5578 (3) | 0.6776 (4) | 0.0201 (8) | |
O5 | 0.7706 (3) | 0.5851 (3) | 0.8176 (4) | 0.0213 (8) | |
O6 | 0.2871 (3) | 0.3742 (3) | 0.6879 (3) | 0.0192 (8) | |
O7 | 0.5352 (3) | 0.1976 (3) | 0.8214 (3) | 0.0170 (7) | |
O8 | 0.8309 (5) | 0.8593 (8) | 0.4053 (11) | 0.156 (5) | |
O9 | 0.8214 (7) | 0.9712 (8) | 0.9193 (16) | 0.162 (8) | 0.72 |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Co1 | 0.0105 (3) | 0.0121 (3) | 0.0227 (3) | 0.0073 (2) | 0.0003 (3) | 0.0018 (3) |
O1W | 0.0279 (18) | 0.0142 (16) | 0.029 (2) | 0.0138 (15) | 0.0069 (16) | 0.0059 (15) |
O2W | 0.0193 (17) | 0.0141 (16) | 0.028 (2) | 0.0068 (14) | 0.0056 (15) | −0.0023 (15) |
O3W | 0.0141 (17) | 0.0168 (17) | 0.032 (2) | 0.0085 (14) | −0.0001 (14) | 0.0003 (15) |
C1 | 0.011 (2) | 0.012 (2) | 0.019 (2) | 0.0046 (18) | −0.0011 (17) | −0.0004 (17) |
C2 | 0.0079 (19) | 0.013 (2) | 0.015 (2) | 0.0029 (17) | 0.0043 (18) | 0.0015 (18) |
C3 | 0.009 (2) | 0.014 (2) | 0.022 (3) | 0.0041 (18) | 0.0029 (17) | 0.0031 (17) |
C4 | 0.011 (2) | 0.018 (2) | 0.019 (3) | 0.0070 (18) | −0.0014 (18) | 0.0013 (18) |
C5 | 0.013 (2) | 0.014 (2) | 0.018 (3) | 0.0061 (18) | 0.0009 (18) | −0.0009 (18) |
N1 | 0.0087 (18) | 0.0132 (18) | 0.018 (2) | 0.0056 (15) | −0.0009 (14) | 0.0013 (15) |
N2 | 0.0084 (17) | 0.0130 (19) | 0.023 (2) | 0.0059 (15) | −0.0045 (15) | 0.0027 (15) |
O4 | 0.0111 (15) | 0.0146 (16) | 0.037 (2) | 0.0084 (14) | −0.0025 (14) | 0.0023 (14) |
O5 | 0.0104 (15) | 0.0110 (16) | 0.042 (2) | 0.0051 (13) | −0.0087 (15) | −0.0028 (15) |
O6 | 0.0072 (15) | 0.0146 (15) | 0.032 (2) | 0.0024 (13) | −0.0024 (13) | 0.0010 (14) |
O7 | 0.0140 (15) | 0.0093 (15) | 0.0252 (18) | 0.0040 (13) | 0.0003 (13) | 0.0060 (13) |
O8 | 0.026 (3) | 0.142 (7) | 0.249 (11) | 0.004 (4) | −0.006 (5) | 0.147 (8) |
O9 | 0.040 (4) | 0.051 (5) | 0.35 (2) | −0.015 (4) | 0.083 (8) | −0.092 (8) |
Geometric parameters (Å, º) top
Co1—O2W | 2.054 (4) | C1—N1 | 1.328 (6) |
Co1—O5i | 2.074 (3) | C1—N2 | 1.372 (6) |
Co1—O1W | 2.072 (4) | C2—O7 | 1.249 (6) |
Co1—O4 | 2.089 (3) | C2—N2 | 1.374 (6) |
Co1—N1 | 2.091 (4) | C2—C3 | 1.422 (6) |
Co1—O3W | 2.148 (3) | C3—C4 | 1.358 (6) |
O1W—H1A | 0.83 (3) | C3—H3 | 0.9300 |
O1W—H1B | 0.83 (3) | C4—N1 | 1.353 (6) |
O2W—H2A | 0.81 (3) | C4—C5 | 1.531 (6) |
O2W—H2B | 0.86 (3) | C5—O6 | 1.244 (5) |
O3W—H3A | 0.82 (3) | C5—O4 | 1.260 (6) |
O3W—H3B | 0.82 (3) | N2—H2 | 0.8600 |
C1—O5 | 1.272 (5) | O5—Co1ii | 2.074 (3) |
| | | |
O2W—Co1—O5i | 90.60 (14) | O5—C1—N1 | 121.2 (4) |
O2W—Co1—O1W | 173.65 (14) | O5—C1—N2 | 119.4 (4) |
O5i—Co1—O1W | 89.67 (14) | N1—C1—N2 | 119.4 (4) |
O2W—Co1—O4 | 90.83 (14) | O7—C2—N2 | 119.8 (4) |
O5i—Co1—O4 | 93.73 (13) | O7—C2—C3 | 126.0 (4) |
O1W—Co1—O4 | 95.48 (15) | N2—C2—C3 | 114.1 (4) |
O2W—Co1—N1 | 94.28 (14) | C4—C3—C2 | 118.7 (4) |
O5i—Co1—N1 | 170.17 (15) | C4—C3—H3 | 120.7 |
O1W—Co1—N1 | 86.43 (14) | C2—C3—H3 | 120.7 |
O4—Co1—N1 | 77.69 (13) | N1—C4—C3 | 124.6 (4) |
O2W—Co1—O3W | 88.80 (14) | N1—C4—C5 | 113.6 (4) |
O5i—Co1—O3W | 90.19 (13) | C3—C4—C5 | 121.7 (4) |
O1W—Co1—O3W | 84.86 (14) | O6—C5—O4 | 125.5 (4) |
O4—Co1—O3W | 176.07 (13) | O6—C5—C4 | 118.9 (4) |
N1—Co1—O3W | 98.43 (14) | O4—C5—C4 | 115.6 (4) |
Co1—O1W—H1A | 130 (4) | C1—N1—C4 | 118.0 (4) |
Co1—O1W—H1B | 121 (4) | C1—N1—Co1 | 126.4 (3) |
H1A—O1W—H1B | 103 (4) | C4—N1—Co1 | 115.1 (3) |
Co1—O2W—H2A | 116 (4) | C1—N2—C2 | 125.0 (4) |
Co1—O2W—H2B | 127 (4) | C1—N2—H2 | 117.5 |
H2A—O2W—H2B | 100 (4) | C2—N2—H2 | 117.5 |
Co1—O3W—H3A | 122 (4) | C5—O4—Co1 | 117.8 (3) |
Co1—O3W—H3B | 94 (4) | C1—O5—Co1ii | 132.5 (3) |
H3A—O3W—H3B | 106 (4) | | |
| | | |
O7—C2—C3—C4 | 177.6 (5) | O4—Co1—N1—C1 | 173.0 (4) |
N2—C2—C3—C4 | −3.3 (7) | O3W—Co1—N1—C1 | −7.7 (4) |
C2—C3—C4—N1 | 1.3 (8) | O2W—Co1—N1—C4 | 91.3 (3) |
C2—C3—C4—C5 | 179.4 (4) | O1W—Co1—N1—C4 | −95.0 (3) |
N1—C4—C5—O6 | −173.6 (4) | O4—Co1—N1—C4 | 1.4 (3) |
C3—C4—C5—O6 | 8.1 (7) | O3W—Co1—N1—C4 | −179.3 (3) |
N1—C4—C5—O4 | 5.4 (6) | O5—C1—N2—C2 | −179.5 (4) |
C3—C4—C5—O4 | −172.9 (5) | N1—C1—N2—C2 | 0.9 (8) |
O5—C1—N1—C4 | 177.3 (5) | O7—C2—N2—C1 | −178.4 (5) |
N2—C1—N1—C4 | −3.1 (7) | C3—C2—N2—C1 | 2.3 (7) |
O5—C1—N1—Co1 | 5.9 (7) | O6—C5—O4—Co1 | 174.6 (4) |
N2—C1—N1—Co1 | −174.5 (3) | C4—C5—O4—Co1 | −4.4 (5) |
C3—C4—N1—C1 | 2.1 (7) | O2W—Co1—O4—C5 | −92.4 (4) |
C5—C4—N1—C1 | −176.2 (4) | O5i—Co1—O4—C5 | 177.0 (4) |
C3—C4—N1—Co1 | 174.4 (4) | O1W—Co1—O4—C5 | 87.0 (4) |
C5—C4—N1—Co1 | −3.8 (5) | N1—Co1—O4—C5 | 1.8 (4) |
O2W—Co1—N1—C1 | −97.1 (4) | N1—C1—O5—Co1ii | 172.4 (3) |
O1W—Co1—N1—C1 | 76.6 (4) | N2—C1—O5—Co1ii | −7.2 (8) |
Symmetry codes: (i) y, −x+y+1, z−1/6; (ii) x−y+1, x, z+1/6. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2···O4ii | 0.86 | 1.93 | 2.736 (5) | 155 |
O1W—H1A···O8 | 0.83 (3) | 2.01 (3) | 2.819 (7) | 164 (6) |
O1W—H1B···O7iii | 0.83 (3) | 1.89 (3) | 2.719 (4) | 173 (5) |
O2W—H2A···O7iv | 0.81 (3) | 1.95 (3) | 2.717 (5) | 157 (5) |
O2W—H2B···O6v | 0.86 (3) | 1.90 (3) | 2.750 (5) | 174 (5) |
O3W—H3A···O9 | 0.82 (3) | 1.92 (3) | 2.676 (9) | 153 (5) |
O3W—H3B···O5 | 0.82 (3) | 1.92 (3) | 2.722 (5) | 164 (5) |
Symmetry codes: (ii) x−y+1, x, z+1/6; (iii) −x+y+1, −x+1, z−1/3; (iv) x−y, x, z+1/6; (v) −y+1, x−y+1, z+1/3. |
Experimental details
Crystal data |
Chemical formula | [Co(C5H2N2O4)(H2O)3]·1.72H2O |
Mr | 294.6 |
Crystal system, space group | Hexagonal, P61 |
Temperature (K) | 100 |
a, c (Å) | 13.4646 (12), 9.8777 (7) |
V (Å3) | 1550.9 (2) |
Z | 6 |
Radiation type | Mo Kα |
µ (mm−1) | 1.70 |
Crystal size (mm) | 0.50 × 0.30 × 0.10 |
|
Data collection |
Diffractometer | Stoe IPDS II diffractometer |
Absorption correction | Integration (X-RED32; Stoe & Cie, 2002) |
Tmin, Tmax | 0.672, 0.875 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 5840, 1993, 1810 |
Rint | 0.036 |
(sin θ/λ)max (Å−1) | 0.617 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.038, 0.087, 1.06 |
No. of reflections | 1993 |
No. of parameters | 173 |
No. of restraints | 10 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.92, −0.94 |
Absolute structure | Flack (1983), with how many Friedel pairs? |
Absolute structure parameter | −0.03 (3) |
Selected geometric parameters (Å, º) topCo1—O2W | 2.054 (4) | Co1—O3W | 2.148 (3) |
Co1—O5i | 2.074 (3) | C1—O5 | 1.272 (5) |
Co1—O1W | 2.072 (4) | C1—N1 | 1.328 (6) |
Co1—O4 | 2.089 (3) | C2—O7 | 1.249 (6) |
Co1—N1 | 2.091 (4) | C4—N1 | 1.353 (6) |
| | | |
O4—Co1—N1 | 77.69 (13) | | |
| | | |
C3—C4—C5—O6 | 8.1 (7) | N1—C4—C5—O4 | 5.4 (6) |
Symmetry code: (i) y, −x+y+1, z−1/6. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2···O4ii | 0.86 | 1.93 | 2.736 (5) | 155.3 |
O1W—H1A···O8 | 0.83 (3) | 2.01 (3) | 2.819 (7) | 164 (6) |
O1W—H1B···O7iii | 0.83 (3) | 1.89 (3) | 2.719 (4) | 173 (5) |
O2W—H2A···O7iv | 0.81 (3) | 1.95 (3) | 2.717 (5) | 157 (5) |
O2W—H2B···O6v | 0.86 (3) | 1.90 (3) | 2.750 (5) | 174 (5) |
O3W—H3A···O9 | 0.82 (3) | 1.92 (3) | 2.676 (9) | 153 (5) |
O3W—H3B···O5 | 0.82 (3) | 1.92 (3) | 2.722 (5) | 164 (5) |
Symmetry codes: (ii) x−y+1, x, z+1/6; (iii) −x+y+1, −x+1, z−1/3; (iv) x−y, x, z+1/6; (v) −y+1, x−y+1, z+1/3. |
Orotic acid (vitamin B13, H3Or) and its metal complexes continue to attract attention because of its multidentate functionality and its great significance in living organisms as a precursor of pyrimidine nucleosides (Genchev, 1970; Rawn, 1989; Lalioti et al., 1998). Metal orotates have potential applications in medicine and some orotate complexes have already been screened as therapeutic agents for cancer treatment (Castan et al., 1990; Kumberger et al., 1993). Orotic acid and its anions, viz. H2Or−, HOr2− and Or3−, are also interesting multidentate ligands, especially above the deprotonation pH values. The coordination around the metal ions is formed by the N atom, the two carbonyl O atoms and the carboxylate O atom. H3Or can act as a dibasic acid, depending on the pH range. In the pH range 3–9, orotic acid exists mainly as the readily coordinating monodeprotonated HOr2− anion (the carboxylic acid group has a pKa value of 2.07; Lutz, 2001). In basic solutions (pH 9), both the carboxyl group and a heterocylic N atom are deprotonated, so the anion acts as a bidentate ligand. Existing studies of its coordination complexes demonstrate that it occurs as a dianion, often coordinating via the N atom and carboxylic acid group, so forming a five-membered chelate ring (Maistralis et al., 2000; Wysokinski et al., 2002; Icbudak et al., 2003; Ölmez et al., 2004). In polymeric orotic acid complexes, the orotate anion bridges the metal ions through the carboxylate group and N and O atoms, forming one-dimensional polymeric chains (Castan et al., 1990; Sun et al., 2002). We present here the crystal structure of the title Co complex of H3Or, (I).
A view of the molecule of (I) is presented in Fig. 1. The CoII ion has a distorted octahedral coordination geometry, comprised of atoms N1 and O4 from a doubly deprotonated bidentate orotate ligand, three aqua molecules (O1W, O2W and O3W) and an exocyclic O atom (O5i; see Table 1 for symmetry code) from a neighbouring orotate moiety. Atoms N1 and O4 are bonded to Co1 to form a five-membered chelate ring (C4/N1/Co1/O4/C5) and, in conjunction with O3W and O5i, they define the approximately planar equatorial plane, with an r.m.s. deviation of 0.0179 Å and a largest deviation from the mean plane of 0.026 (3) Å for atom C5. This is apparently due to the strong intermolecular hydrogen-bonding interaction between atom H2 of the pyrimidine ring and carboxylate atom O4i. Finally, the apical positions of the CoII coordination octahedron are occupied by O1W and O2W.
All N—Co—O and O—Co—O bond angles of (I) deviate significantly from 90 or 180°, presumably as a result of the steric constraints arising from the shape of the ligand. The angle subtended at the Co atom by the orotate ligand is 77.69 (13)°, which is in agreement with the values reported previously for other CoII complexes (Zhang & You, 2003).
The orotate group of (I) is essentially planar (r.m.s. deviation = 0.0142 Å), with a slight deviation from planarity arising from the non-zero torsion angle between the carboxylate group and the ring. Of all the N—C bonds in the uracylic ring, N1—C1 and N1—C4 are the shortest. This indicates that there is considerable π-electron delocalization within the C3/C4/N1/C1 skeleton. The dihedral angle between the pyrimidine ring and the five-membered chelate ring is 4.82 (2)°, while that between the pyrimidine ring and the O4/C5/O6 carboxylate group is 6.07 (3)°. The C═O bond lengths for exocyclic atoms O5 and O7 clearly indicate their double-bond character (Table 1).
Crystal packing in (I) is achieved via intermolecular hydrogen bonding (Fig. 2 and Table 2). Graph-set notation (Bernstein et al., 1995) is used to describe these hydrogen-bonding patterns. Thus, the intramolecular O—H···O hydrogen bond can be described as an S(6) motif. Fig. 2 shows the way in which the three aqua ligands and carboxylate O6 and carbonyl O7 atoms enter into inter- and intramolecular hydrogen-bonding interactions. As a result, zigzag tapes are formed through O2Wi—H2Ai···O7ii, N2ii—H2ii···O4 and O2Wi—H2Bi···O6 interactions [symmetry codes: (i) −x + y, 1 − x, z − 1/3; (ii) y, 1 − x + y, z − 1/6], which define R23(10) and R11(6) ring patterns. Furthermore, an R44(35) motif appears via the O1Wv—H1Bv···O7iv, O2Wiv—H2Aiv···O7iii and O2Wiii—H2Aiii···O7 interactions [symmetry codes: (iii) y, −x + y, z − 1/6; (iv) −x + y, −x, z − 1/3; (v) −1 + x, −1 + y, −z]. These helicoidal chains zigzagging along the a axis are interlinked through O1W—H1B···O7vi and O2Wiii—H2Aiii···O7 interactions [symmetry code: (vi) 1 − x + y, 1 − x, z − 1/3], which in turn define an R22(16) ring pattern (Fig. 3).