1,3,7-Trimethyl-2,4-dioxo-1,2,3,4-tetra-hydro-pteridine-6-carboxylic acid hemihydrate.

In the title compound, C(10)H(10)N(4)O(4)·0.5H(2)O, the two rings of the pteridine system are nearly coplanar [dihedral angle = 4.25 (9)°]. The atoms of the carboxyl group are also coplanar with the pteridine unit [r.m.s. deviation from the mean plane of the pteridine skeleton = 0.092 (2) Å]. In the crystal, the presence of the water molecule of crystallization (O atom site symmetry 2) leads to a hydrogen-bonding pattern different from the one shown by many carboxylic acid compounds (dimers formed through O-H⋯O hydrogen bonds between neighbouring carboxyl groups): in the present structure, the water mol-ecule, which lies on a binary axis, acts as a bridge between two mol-ecules, forming a hydrogen-bonded dimer. In addition to the hydrogen bonds, there are π-π ring stacking inter-actions involving the pyrimidine and pyrazine rings [centroid-centroid distance = 3.689 (1)Å], and two different pyrazine rings [centroid-centroid distance = 3.470 (1)Å]. Finally, there is a C-O⋯π contact involving a carboxyl-ate C-O and the pyrimidine ring with a short O⋯Cg distance of 2.738 (2) Å.

Related literature

The precursor 6-acetyl-1,3,7-trimethyl­lumazine (DLMAceM) was obtained according to literature methods, see: Kim et al. (1999 ▶). For the structural features of both free and complexed related pteridine derivatives, see for example: Jiménez-Pulido et al. (2008a ▶,b ▶, 2009 ▶).

Experimental

Crystal data

C10H10N4O4·0.5H2O

M = 259.23

Monoclinic,

a = 15.7328 (19) Å

b = 11.5784 (16) Å

c = 12.4062 (18) Å

β = 106.113 (10)°

V = 2171.1 (5) Å3

Z = 8

Mo Kα radiation

μ = 0.13 mm−1

T = 120 K

0.46 × 0.24 × 0.19 mm

Data collection

Nonius KappaCCD diffractometer

Absorption correction: multi-scan (SADABS; Sheldrick, 2003 ▶) T min = 0.944, T max = 0.976

14172 measured reflections

1970 independent reflections

1493 reflections with I > 2σ(I)

R int = 0.038

Refinement

R[F 2 > 2σ(F 2)] = 0.055

wR(F 2) = 0.140

S = 1.21

1970 reflections

180 parameters

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.65 e Å−3

Δρmin = −0.58 e Å−3

Data collection: COLLECT (Nonius, 1998 ▶); cell refinement: DIRAX/LSQ (Duisenberg, 1992 ▶); data reduction: EVALCCD (Duisenberg et al., 2003 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PLATON (Spek, 2009 ▶).

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810007166/bg2332sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810007166/bg2332Isup2.hkl

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

C10H10N4O4·0.5H2O	F(000) = 1080
Mr = 259.23	Dx = 1.586 Mg m−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 1970 reflections
a = 15.7328 (19) Å	θ = 2.2–25.3°
b = 11.5784 (16) Å	µ = 0.13 mm−1
c = 12.4062 (18) Å	T = 120 K
β = 106.113 (10)°	Prism, light yellow
V = 2171.1 (5) Å3	0.46 × 0.24 × 0.19 mm
Z = 8

Nonius KappaCCD diffractometer	1970 independent reflections
Radiation source: fine-focus sealed tube	1493 reflections with I > 2σ(I)
graphite	Rint = 0.038
CCD rotation images, thick slices scans	θmax = 25.3°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −18→18
Tmin = 0.944, Tmax = 0.976	k = −13→13
14172 measured reflections	l = −14→14

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)] = 0.055	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.140	w = 1/[σ2(Fo2) + (0.0794P)2 + 0.6244P] where P = (Fo2 + 2Fc2)/3
S = 1.21	(Δ/σ)max < 0.001
1970 reflections	Δρmax = 0.65 e Å−3
180 parameters	Δρmin = −0.58 e Å−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0125 (14)

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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.

	x	y	z	Uiso*/Ueq
O1w	0.5000	0.75980 (19)	0.2500	0.0271 (5)
N1	0.16439 (11)	0.99057 (14)	−0.04043 (14)	0.0213 (4)
C2	0.22500 (13)	1.06607 (18)	−0.06308 (17)	0.0217 (5)
N3	0.31401 (11)	1.03800 (14)	−0.02157 (14)	0.0215 (4)
C4	0.34674 (13)	0.94797 (17)	0.04960 (16)	0.0201 (5)
C4A	0.27938 (13)	0.87743 (17)	0.07728 (15)	0.0181 (5)
N5	0.30569 (11)	0.79181 (13)	0.14868 (13)	0.0190 (4)
C6	0.24465 (13)	0.73144 (16)	0.17889 (16)	0.0201 (5)
C7	0.15435 (14)	0.75701 (17)	0.13777 (16)	0.0211 (5)
N8	0.12794 (11)	0.84253 (14)	0.06406 (13)	0.0209 (4)
C8A	0.18987 (13)	0.90176 (17)	0.03424 (15)	0.0189 (5)
C1	0.07098 (14)	1.0169 (2)	−0.09039 (18)	0.0294 (6)
O2	0.20238 (10)	1.15152 (13)	−0.11888 (12)	0.0303 (4)
C3	0.37550 (14)	1.11665 (19)	−0.05308 (19)	0.0289 (5)
O4	0.42558 (9)	0.92948 (12)	0.08549 (12)	0.0257 (4)
C61	0.28018 (14)	0.63747 (18)	0.26029 (17)	0.0246 (5)
O61	0.36742 (10)	0.63064 (13)	0.30013 (12)	0.0283 (4)
O62	0.23356 (10)	0.56896 (13)	0.28942 (13)	0.0362 (5)
C71	0.08347 (14)	0.69621 (18)	0.17313 (18)	0.0267 (5)
H1W	0.5284 (19)	0.809 (2)	0.305 (2)	0.065 (10)*
H1A	0.0366	0.9451	−0.1014	0.044*
H1B	0.0636	1.0550	−0.1630	0.044*
H1C	0.0501	1.0683	−0.0404	0.044*
H3A	0.4363	1.0901	−0.0197	0.043*
H3B	0.3684	1.1945	−0.0257	0.043*
H3C	0.3631	1.1182	−0.1350	0.043*
H61	0.398 (2)	0.694 (3)	0.273 (3)	0.068 (9)*
H71A	0.0264	0.7330	0.1379	0.040*
H71B	0.0958	0.7004	0.2549	0.040*
H71C	0.0814	0.6151	0.1499	0.040*

	U11	U22	U33	U12	U13	U23
O1w	0.0226 (11)	0.0273 (12)	0.0279 (12)	0.000	0.0013 (9)	0.000
N1	0.0182 (9)	0.0239 (9)	0.0210 (9)	0.0019 (7)	0.0040 (7)	0.0038 (7)
C2	0.0226 (11)	0.0241 (11)	0.0182 (10)	0.0020 (9)	0.0055 (8)	−0.0001 (9)
N3	0.0204 (9)	0.0235 (9)	0.0206 (9)	−0.0005 (7)	0.0059 (7)	0.0031 (7)
C4	0.0211 (11)	0.0217 (11)	0.0167 (10)	0.0000 (9)	0.0036 (8)	−0.0015 (8)
C4A	0.0205 (11)	0.0188 (10)	0.0153 (10)	0.0026 (8)	0.0056 (8)	−0.0013 (8)
N5	0.0212 (9)	0.0189 (9)	0.0168 (8)	0.0006 (7)	0.0053 (7)	−0.0021 (7)
C6	0.0230 (11)	0.0201 (11)	0.0181 (10)	−0.0025 (9)	0.0073 (8)	−0.0029 (8)
C7	0.0251 (11)	0.0213 (11)	0.0178 (10)	−0.0019 (9)	0.0073 (9)	−0.0048 (8)
N8	0.0198 (9)	0.0228 (9)	0.0208 (9)	−0.0002 (7)	0.0067 (7)	−0.0017 (7)
C8A	0.0216 (11)	0.0199 (11)	0.0152 (10)	0.0009 (8)	0.0053 (8)	−0.0040 (8)
C1	0.0193 (11)	0.0373 (13)	0.0296 (12)	0.0047 (10)	0.0037 (9)	0.0078 (10)
O2	0.0283 (9)	0.0298 (9)	0.0318 (9)	0.0052 (7)	0.0065 (7)	0.0114 (7)
C3	0.0242 (12)	0.0299 (12)	0.0332 (12)	−0.0037 (10)	0.0091 (10)	0.0082 (10)
O4	0.0168 (8)	0.0304 (8)	0.0288 (8)	0.0000 (6)	0.0047 (6)	0.0050 (6)
C61	0.0276 (12)	0.0251 (12)	0.0209 (11)	−0.0005 (9)	0.0064 (9)	0.0003 (9)
O61	0.0265 (8)	0.0282 (9)	0.0277 (8)	0.0026 (7)	0.0036 (7)	0.0056 (7)
O62	0.0352 (9)	0.0340 (9)	0.0391 (10)	−0.0040 (8)	0.0100 (8)	0.0148 (8)
C71	0.0234 (11)	0.0314 (12)	0.0265 (12)	−0.0048 (10)	0.0093 (9)	−0.0009 (9)

O1w—H1W	0.90 (3)	N1—C2	1.379 (3)
O4—C4	1.215 (2)	N1—C1	1.460 (3)
C4A—N5	1.317 (3)	O61—C61	1.326 (3)
C4A—C8A	1.389 (3)	O61—H61	0.98 (3)
C4A—C4	1.453 (3)	O62—C61	1.202 (3)
N8—C8A	1.325 (3)	C7—C71	1.484 (3)
N8—C7	1.334 (3)	C71—H71A	0.9800
N5—C6	1.323 (3)	C71—H71B	0.9800
N3—C4	1.371 (3)	C71—H71C	0.9800
N3—C2	1.390 (3)	C3—H3A	0.9800
N3—C3	1.459 (3)	C3—H3B	0.9800
O2—C2	1.203 (2)	C3—H3C	0.9800
C8A—N1	1.367 (3)	C1—H1A	0.9800
C6—C7	1.401 (3)	C1—H1B	0.9800
C6—C61	1.484 (3)	C1—H1C	0.9800
N5—C4A—C8A	120.46 (18)	O2—C2—N1	121.85 (19)
N5—C4A—C4	117.93 (18)	O2—C2—N3	120.80 (18)
C8A—C4A—C4	121.56 (18)	N1—C2—N3	117.32 (17)
C8A—N8—C7	117.54 (18)	C7—C71—H71A	109.5
C4A—N5—C6	118.07 (18)	C7—C71—H71B	109.5
C4—N3—C2	125.18 (17)	H71A—C71—H71B	109.5
C4—N3—C3	119.27 (17)	C7—C71—H71C	109.5
C2—N3—C3	115.45 (16)	H71A—C71—H71C	109.5
N8—C8A—N1	118.56 (18)	H71B—C71—H71C	109.5
N8—C8A—C4A	122.21 (18)	N3—C3—H3A	109.5
N1—C8A—C4A	119.22 (18)	N3—C3—H3B	109.5
N5—C6—C7	121.83 (18)	H3A—C3—H3B	109.5
N5—C6—C61	114.46 (18)	N3—C3—H3C	109.5
C7—C6—C61	123.70 (18)	H3A—C3—H3C	109.5
C8A—N1—C2	121.70 (17)	H3B—C3—H3C	109.5
C8A—N1—C1	121.06 (17)	O62—C61—O61	120.23 (19)
C2—N1—C1	116.92 (17)	O62—C61—C6	122.8 (2)
C61—O61—H61	112.3 (17)	O61—C61—C6	116.92 (18)
O4—C4—N3	122.20 (18)	N1—C1—H1A	109.5
O4—C4—C4A	123.50 (18)	N1—C1—H1B	109.5
N3—C4—C4A	114.30 (17)	H1A—C1—H1B	109.5
N8—C7—C6	119.86 (18)	N1—C1—H1C	109.5
N8—C7—C71	115.99 (19)	H1A—C1—H1C	109.5
C6—C7—C71	124.13 (18)	H1B—C1—H1C	109.5

D—H···A	D—H	H···A	D···A	D—H···A
O1w—H1w···O4i	0.91 (2)	1.94 (2)	2.841 (2)	172 (3)
O1w—H1w···N5i	0.91 (2)	2.52 (3)	2.988 (2)	113 (2)
O61—H61···O1w	0.99 (3)	1.87 (3)	2.774 (2)	151 (3)
O61—H61···N5	0.99 (3)	2.13 (4)	2.635 (2)	110 (2)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1w—H1w⋯O4i	0.91 (2)	1.94 (2)	2.841 (2)	172 (3)
O1w—H1w⋯N5i	0.91 (2)	2.52 (3)	2.988 (2)	113 (2)
O61—H61⋯O1w	0.99 (3)	1.87 (3)	2.774 (2)	151 (3)
O61—H61⋯N5	0.99 (3)	2.13 (4)	2.635 (2)	110 (2)

Symmetry code: (i) .