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The crystal structure of the title compound, 3,7-di­hydro-1,3-di­methyl-1H-purine-2,6-dione monohydrate, C7H8N4O2·H2O, was determined by single-crystal X-ray diffractometry using direct methods. Water mol­ecules in the crystals form infinite chains, through hydrogen-bonded chains running through tunnels formed by surrounding theophyl­line mol­ecules along the a axis. The water chains are also crosslinked through hydrogen bonds by hydrogen-bonded theophyl­line dimers, and form a two-dimensional hydrogen-bonded structure parallel to the ab plane. The previously reported structure [Suctor (1958), Acta Cryst. 11, 83-87] in space group P21, with Z = 4, appears to be incorrect.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802002921/om6079sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536802002921/om6079Isup2.hkl
Contains datablock I

CCDC reference: 183780

Key indicators

  • Single-crystal X-ray study
  • T = 173 K
  • Mean [sigma](C-C) = 0.003 Å
  • R factor = 0.045
  • wR factor = 0.125
  • Data-to-parameter ratio = 11.2

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry








Computing details top

Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL/PC (Bruker, 1997); software used to prepare material for publication: SHELXTL/PC.

theophylline monohydrate top
Crystal data top
C7H8N4O2·H2OF(000) = 416
Mr = 198.19Dx = 1.476 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
a = 4.468 (2) ÅCell parameters from 514 reflections
b = 15.355 (5) Åθ = 2.1–25.0°
c = 13.121 (5) ŵ = 0.12 mm1
β = 97.792 (7)°T = 173 K
V = 891.9 (6) Å3Needle, light yellow
Z = 40.50 × 0.11 × 0.09 mm
Data collection top
Bruker CCD area-detector
diffractometer
1554 independent reflections
Radiation source: normal-focus sealed tube1285 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.031
π and ω scansθmax = 25.0°, θmin = 2.1°
Absorption correction: multi-scan
(SADABS; Blessing, 1995; Sheldrick, 2000)
h = 55
Tmin = 0.985, Tmax = 0.989k = 1818
5481 measured reflectionsl = 1515
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)] = 0.045Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.125H atoms treated by a mixture of independent and constrained refinement
S = 1.01 w = 1/[σ2(Fo2) + (0.063P)2 + 0.7841P]
where P = (Fo2 + 2Fc2)/3
1554 reflections(Δ/σ)max = 0.001
139 parametersΔρmax = 0.20 e Å3
6 restraintsΔρmin = 0.19 e Å3
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
xyzUiso*/UeqOcc. (<1)
N10.5006 (4)0.86445 (11)0.70804 (13)0.0248 (4)
C20.4946 (5)0.77444 (14)0.72914 (16)0.0256 (5)
N30.2779 (4)0.72580 (11)0.67088 (13)0.0253 (4)
C40.0840 (5)0.76507 (14)0.59422 (15)0.0234 (5)
C50.1007 (5)0.85251 (13)0.57384 (16)0.0236 (5)
C60.3118 (5)0.90849 (14)0.63115 (16)0.0251 (5)
N70.1274 (4)0.86794 (11)0.49419 (13)0.0257 (4)
H7A0.17480.91820.46410.031*
C80.2629 (5)0.79099 (14)0.47166 (17)0.0266 (5)
H8A0.42800.78360.41860.032*
N90.1431 (4)0.72607 (12)0.53104 (14)0.0265 (4)
O100.3377 (4)0.98801 (10)0.61981 (12)0.0329 (4)
C100.7207 (5)0.91660 (16)0.77636 (18)0.0336 (6)
H10A0.78000.96760.73900.050*
H10B0.89950.88110.79920.050*
H10C0.62880.93570.83630.050*
O120.6760 (4)0.74234 (10)0.79635 (12)0.0343 (4)
C130.2595 (6)0.63201 (15)0.6900 (2)0.0367 (6)
H13A0.35400.61910.76020.055*0.64 (3)
H13B0.36510.60020.64080.055*0.64 (3)
H13C0.04710.61410.68190.055*0.64 (3)
H13D0.15680.60320.62840.055*0.36 (3)
H13E0.14570.62200.74780.055*0.36 (3)
H13F0.46370.60820.70680.055*0.36 (3)
O10.2597 (5)0.54582 (11)0.47253 (16)0.0458 (5)
H1A0.236 (7)0.5979 (17)0.495 (2)0.069*
H1B0.098 (8)0.525 (3)0.506 (4)0.069*0.50
H1C0.378 (11)0.529 (3)0.515 (4)0.069*0.50
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0233 (9)0.0224 (9)0.0272 (10)0.0010 (7)0.0023 (7)0.0012 (7)
C20.0245 (11)0.0267 (11)0.0254 (11)0.0029 (9)0.0026 (9)0.0008 (9)
N30.0278 (10)0.0188 (9)0.0286 (10)0.0015 (7)0.0006 (8)0.0028 (7)
C40.0236 (11)0.0208 (11)0.0256 (11)0.0006 (8)0.0023 (9)0.0000 (8)
C50.0239 (11)0.0198 (11)0.0263 (11)0.0035 (8)0.0009 (9)0.0009 (8)
C60.0260 (11)0.0219 (12)0.0274 (11)0.0021 (9)0.0036 (9)0.0003 (9)
N70.0287 (10)0.0187 (9)0.0277 (10)0.0020 (8)0.0035 (8)0.0005 (7)
C80.0252 (11)0.0247 (12)0.0285 (11)0.0019 (9)0.0019 (9)0.0018 (9)
N90.0263 (10)0.0216 (9)0.0305 (10)0.0015 (7)0.0004 (8)0.0006 (8)
O100.0394 (9)0.0179 (8)0.0388 (9)0.0010 (7)0.0044 (7)0.0005 (7)
C100.0320 (13)0.0310 (13)0.0352 (13)0.0011 (10)0.0044 (10)0.0072 (10)
O120.0338 (9)0.0301 (9)0.0357 (9)0.0042 (7)0.0067 (7)0.0059 (7)
C130.0449 (15)0.0193 (12)0.0428 (14)0.0011 (10)0.0051 (11)0.0056 (10)
O10.0525 (11)0.0223 (9)0.0585 (13)0.0000 (8)0.0069 (9)0.0033 (8)
Geometric parameters (Å, º) top
N1—C61.399 (3)C8—N91.332 (3)
N1—C21.411 (3)C8—H8A0.95
N1—C101.474 (3)C10—H10A0.98
C2—O121.218 (3)C10—H10B0.98
C2—N31.371 (3)C10—H10C0.98
N3—C41.375 (3)C13—H13A0.98
N3—C131.466 (3)C13—H13B0.98
C4—N91.359 (3)C13—H13C0.98
C4—C51.373 (3)C13—H13D0.98
C5—N71.378 (3)C13—H13E0.98
C5—C61.415 (3)C13—H13F0.98
C6—O101.237 (3)O1—H1A0.86 (2)
N7—C81.342 (3)O1—H1B0.86 (3)
N7—H7A0.88O1—H1C0.85 (3)
C6—N1—C2126.14 (17)N1—C10—H10C109.5
C6—N1—C10117.61 (18)H10A—C10—H10C109.5
C2—N1—C10116.21 (17)H10B—C10—H10C109.5
O12—C2—N3122.2 (2)N3—C13—H13A109.5
O12—C2—N1120.7 (2)N3—C13—H13B109.5
N3—C2—N1117.07 (18)H13A—C13—H13B109.5
C2—N3—C4119.77 (18)N3—C13—H13C109.5
C2—N3—C13119.43 (18)H13A—C13—H13C109.5
C4—N3—C13120.79 (18)H13B—C13—H13C109.5
N9—C4—C5111.59 (18)N3—C13—H13D109.5
N9—C4—N3126.68 (19)H13A—C13—H13D141.1
C5—C4—N3121.73 (19)H13B—C13—H13D56.3
C4—C5—N7105.18 (18)H13C—C13—H13D56.3
C4—C5—C6122.73 (19)N3—C13—H13E109.5
N7—C5—C6132.05 (19)H13A—C13—H13E56.3
O10—C6—N1120.45 (19)H13B—C13—H13E141.1
O10—C6—C5127.0 (2)H13C—C13—H13E56.3
N1—C6—C5112.51 (18)H13D—C13—H13E109.5
C8—N7—C5106.31 (17)N3—C13—H13F109.5
C8—N7—H7A126.8H13A—C13—H13F56.3
C5—N7—H7A126.8H13B—C13—H13F56.3
N9—C8—N7113.36 (19)H13C—C13—H13F141.1
N9—C8—H8A123.3H13D—C13—H13F109.5
N7—C8—H8A123.3H13E—C13—H13F109.5
C8—N9—C4103.57 (18)H1A—O1—H1B96 (3)
N1—C10—H10A109.5H1A—O1—H1C96 (3)
N1—C10—H10B109.5H1B—O1—H1C96 (3)
H10A—C10—H10B109.5
C6—N1—C2—O12177.9 (2)N3—C4—C5—C61.5 (3)
C10—N1—C2—O124.4 (3)C2—N1—C6—O10179.9 (2)
C6—N1—C2—N32.0 (3)C10—N1—C6—O102.2 (3)
C10—N1—C2—N3175.74 (18)C2—N1—C6—C50.7 (3)
O12—C2—N3—C4178.3 (2)C10—N1—C6—C5177.08 (18)
N1—C2—N3—C41.6 (3)C4—C5—C6—O10178.1 (2)
O12—C2—N3—C130.6 (3)N7—C5—C6—O100.8 (4)
N1—C2—N3—C13179.49 (19)C4—C5—C6—N11.1 (3)
C2—N3—C4—N9179.3 (2)N7—C5—C6—N1178.4 (2)
C13—N3—C4—N91.8 (3)C4—C5—N7—C80.3 (2)
C2—N3—C4—C50.0 (3)C6—C5—N7—C8177.9 (2)
C13—N3—C4—C5178.9 (2)C5—N7—C8—N90.5 (3)
N9—C4—C5—N70.0 (2)N7—C8—N9—C40.5 (2)
N3—C4—C5—N7179.40 (18)C5—C4—N9—C80.3 (2)
N9—C4—C5—C6177.89 (19)N3—C4—N9—C8179.7 (2)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N7—H7A···O10i0.881.902.763 (2)168
O1—H1A···N90.86 (2)2.05 (3)2.901 (3)171 (3)
O1—H1B···O1ii0.86 (3)1.92 (3)2.726 (4)156 (6)
O1—H1C···O1iii0.85 (3)2.01 (4)2.744 (4)143 (5)
Symmetry codes: (i) x, y+2, z+1; (ii) x, y+1, z+1; (iii) x1, y+1, z+1.
Crystal data of theophylline monohydrate top
The present workSuctor (1958)a
Experiment temperature173 (2)K295K
Crystal systemmonoclinicmonoclinic
Space groupP21/nP21
a4.468 (2)4.50
b15.355 (5)15.3
c13.121 (5)13.3
β97.792 (7)99.5
Volume891.9 (6)903.15
Z44
Density1.4761.456
Notes: (a) the axes of this earlier crystal structure (Suctor, 1958) were assigned differently and have now been interchanged to match the assignment in the present work.
 

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