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Acta Crystallogr Sect E Struct Rep Online. 2008 September 1; 64(Pt 9): m1159–m1160.
Published online 2008 August 13. doi:  10.1107/S160053680802549X
PMCID: PMC2960592

Diaqua­bis(8-chloro-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetra­hydro-7H-purinato-κN 7)copper(II) dihydrate

Abstract

The title mononuclear copper(II) complex, [Cu(C7H6ClN4O2)2(H2O)2]·2H2O, based on 8-chloro­theophylline (HCt), has the Cu atom at a center of symmetry in a slightly distorted trans square-planar geometry coordinated by two N atoms of two deprotonated HCt ligands and two O atoms of water mol­ecules. The crystal packing is stabilized by hydrogen bonds involving deprotonated HCt ligands, coordinated water mol­ecules and uncoordinated solvent water mol­ecules.

Related literature

For related literature, see: Halpert et al. (2002 [triangle]); Antholine et al. (1985 [triangle]); García-Tojal et al. (1996 [triangle]); Okabe et al. (1993 [triangle]); Saryan et al. (1979 [triangle]); Serafin (1996 [triangle]); Spealman (1988 [triangle]); West et al. (1993 [triangle]); Zhao et al. (2003 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-m1159-scheme1.jpg

Experimental

Crystal data

  • [Cu(C7H6ClN4O2)2(H2O)2]·2H2O
  • M r = 562.82
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-m1159-efi1.jpg
  • a = 8.377 (5) Å
  • b = 8.533 (8) Å
  • c = 8.830 (3) Å
  • α = 67.999 (2)°
  • β = 64.180 (7)°
  • γ = 78.388 (6)°
  • V = 526.2 (6) Å3
  • Z = 1
  • Mo Kα radiation
  • μ = 1.35 mm−1
  • T = 293 (2) K
  • 0.36 × 0.24 × 0.16 mm

Data collection

  • Bruker SMART CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996 [triangle]) T min = 0.685, T max = 0.802
  • 3811 measured reflections
  • 1834 independent reflections
  • 936 reflections with I > 2σ(I)
  • R int = 0.099

Refinement

  • R[F 2 > 2σ(F 2)] = 0.058
  • wR(F 2) = 0.102
  • S = 0.99
  • 1834 reflections
  • 153 parameters
  • 19 restraints
  • H-atom parameters constrained
  • Δρmax = 0.54 e Å−3
  • Δρmin = −0.66 e Å−3

Data collection: SMART (Bruker, 2004 [triangle]); cell refinement: SAINT (Bruker, 2004 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXTL (Sheldrick, 2008 [triangle]).

Table 1
Selected geometric parameters (Å, °)
Table 2
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S160053680802549X/bg2201sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053680802549X/bg2201Isup2.hkl

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

Acknowledgments

This work was supported by the 2007 Science Foundation of Yichun University.

supplementary crystallographic information

Comment

8-Chlorotheophylline (Ct) is a methylxathine drug related to caffeine and theophylline (Halpert et al., 2002). It produces a number of effects, including nervousness, restlessness, insomnia, convulsions, anxiety, headaches and nausea (Serafin, 1996). The behavioural effects of this agent are attributed primarily to its ability to block adenosine receptors (Spealman, 1988). In recent years, many copper(II) complexes have draw attention due to the fact that they exhibit a greater biological activity, (antitumour, antibacterial, etc.) than the corresponding free ligand because of their chelating ability and positive redox potential (García-Tojal et al., 1996; West et al., 1993; Antholine et al., 1985; Saryan et al., 1979). Here, we report the structure of the title compound, {[Cu(Ct)2(H2O)2](H2O)2} (I), to our knowledge the first reported metal complex with 8-chlorotheophylline..

The stucture of (I) is shown in Fig. 1. It is composed of a mononuclear entity [Cu(Ct)2(H2O)2], together with two crystal water molecules; the copperII atom, lying in a center of symmetry, is bonded to the nitrogen atoms of two individual 8-Ct molecules and oxygen atoms from two water molecules (Table 1), forming a trans square-planar arrangement. It should be noted that the ligand is in its anionic form (8-Ct-) in order to achieve charge balance.

Selected bond distances and bond angles are given in Table 1. The Cu—N and Cu—O bond lengths and bond angles at Cu1 are similar to those reported in some tetra-coordinated copper complexs (Zhao et al., 2003; Okabe et al., 1993). The 8-Ct molecule deviates slightly from planarity and the dihedral angle created by the least squares planes between the pyrimidine and imidazole ring is 1.2 (1) °.

The structure presents O–H···O, O–H···N intermolecular hydrogen bonds (Table 2). between 8-Cts and water molecules. The coordinated water molecule is a donor towards the pyrimidine O2 and the uncoordinated water O4, thus linking the complex units into a 2-dimentional structure along the b axis. Besides, the lattice water molecules acts as a donor towards the pyrimidine O1 and imidazole N4. These two hydrogen bonds serve to link the 2-D structures into a 3-D array along the c axis.

Experimental

A solution of Cu(OAc)2.H2O (0.5 mmol) in water (5 ml) was slowly added to a solution of the ligand (1 mmol) in ethanol (14 ml) under stirring at room temperature. The mixture was sealed in a 25 ml Teflon-lined stainless steel vessel and heated under autogenous pressure at 383 K for 6 days, and then slowly cooled to room temperature. The green crystals obtained were recovered by filtration, washed with ethanol and dried in air. Yield: 52% (based on Cu).

Refinement

Hydrogen atoms attached to carbon atoms were positioned geometrically and treated as riding, with C—H = 0.96 Å and Uiso(H) = 1.2Ueq(C). The water H atoms were located in a difference Fourier map, and were refined with a distance restraint of O—H = 0.82—0.84 Å and Uiso(H) = 1.5Ueq(O). The crystals are unstable outside the parental solution, for what the quality of the diffraction data was poor. This led to unrealistic displacement parameters for four C and one O atoms, which were accordingly restrained to be nearly isotropic.

Figures

Fig. 1.
The structure of (I), showing 30% probability displacement ellipsoids and the atom-labeling scheme.
Fig. 2.
The crystal packing of (I).

Crystal data

[Cu(C7H6Cl1N4O2)2(H2O1)2]·2H2OZ = 1
Mr = 562.82F000 = 287
Triclinic, P1Dx = 1.776 Mg m3
Hall symbol: -P 1Mo Kα radiation λ = 0.71073 Å
a = 8.377 (5) ÅCell parameters from 822 reflections
b = 8.533 (8) Åθ = 2.6–25.0º
c = 8.830 (3) ŵ = 1.35 mm1
α = 67.999 (2)ºT = 293 (2) K
β = 64.180 (7)ºBlock, green
γ = 78.388 (6)º0.36 × 0.24 × 0.16 mm
V = 526.2 (6) Å3

Data collection

Bruker SMART CCD area-detector diffractometer1834 independent reflections
Radiation source: fine-focus sealed tube936 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.099
T = 293(2) Kθmax = 25.0º
[var phi] and ω scansθmin = 2.6º
Absorption correction: multi-scan(SADABS; Sheldrick, 1996)h = −9→9
Tmin = 0.685, Tmax = 0.802k = −8→10
3811 measured reflectionsl = −10→10

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.058H-atom parameters constrained
wR(F2) = 0.102  w = 1/[σ2(Fo2)]
S = 0.99(Δ/σ)max = 0.004
1834 reflectionsΔρmax = 0.54 e Å3
153 parametersΔρmin = −0.66 e Å3
19 restraintsExtinction correction: none
Primary atom site location: structure-invariant direct methods

Special details

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)

xyzUiso*/Ueq
Cu10.50000.00001.00000.0214 (5)
N10.5200 (8)0.0829 (8)0.7503 (7)0.0214 (17)
N20.1993 (8)0.4308 (7)0.6697 (7)0.0203 (16)
N30.4180 (8)0.3889 (8)0.4053 (7)0.0264 (18)
N40.6338 (8)0.1570 (8)0.4472 (8)0.0245 (18)
O10.1930 (7)0.2659 (6)0.9464 (6)0.0296 (15)
O20.2040 (6)0.6046 (6)0.3965 (6)0.0210 (13)
O30.6720 (6)0.1598 (6)0.9341 (6)0.0340 (15)
H3A0.71540.20290.82560.051*
H3B0.73760.16510.98150.051*
O40.8607 (7)0.0978 (6)0.1220 (6)0.0330 (16)
H4A0.95780.14130.07040.049*
H4B0.78680.12260.20970.049*
Cl10.8042 (3)−0.1040 (3)0.6122 (3)0.0308 (6)
C10.4156 (10)0.2195 (9)0.6872 (9)0.0171 (19)
C20.2692 (10)0.2944 (9)0.7842 (10)0.019 (2)
C30.2719 (10)0.4812 (9)0.4827 (9)0.0142 (18)
C40.4889 (11)0.2531 (10)0.5113 (10)0.022 (2)
C50.6432 (10)0.0543 (9)0.6041 (10)0.019 (2)
C60.0408 (9)0.5307 (9)0.7496 (9)0.021 (2)
H6A0.07590.63600.73890.032*
H6B−0.02030.46860.87310.032*
H6C−0.03670.55270.68900.032*
C70.4918 (9)0.4281 (9)0.2102 (8)0.020 (2)
H7A0.39800.47040.16850.030*
H7B0.54650.32730.18090.030*
H7C0.57880.51220.15440.030*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
Cu10.0267 (10)0.0224 (10)0.0140 (9)−0.0032 (8)−0.0113 (8)0.0001 (7)
N10.019 (4)0.027 (4)0.017 (4)−0.011 (3)−0.010 (3)0.001 (3)
N20.027 (4)0.021 (4)0.009 (3)−0.004 (3)−0.004 (3)−0.003 (3)
N30.030 (5)0.036 (5)0.011 (4)−0.006 (4)−0.004 (3)−0.008 (3)
N40.022 (4)0.033 (4)0.012 (4)−0.006 (3)−0.002 (3)−0.003 (3)
O10.036 (4)0.033 (4)0.014 (3)−0.006 (3)−0.007 (3)−0.003 (3)
O20.0205 (16)0.0215 (16)0.0201 (15)0.0010 (9)−0.0110 (10)−0.0035 (10)
O30.052 (4)0.038 (4)0.013 (3)−0.031 (3)−0.015 (3)0.008 (3)
O40.027 (4)0.050 (4)0.018 (3)−0.005 (3)−0.010 (3)−0.004 (3)
Cl10.0279 (15)0.0291 (15)0.0273 (13)0.0002 (11)−0.0096 (11)−0.0031 (11)
C10.027 (5)0.014 (5)0.009 (4)0.002 (4)−0.010 (4)−0.002 (3)
C20.019 (2)0.019 (2)0.019 (2)−0.0004 (10)−0.0083 (12)−0.0056 (11)
C30.014 (2)0.014 (2)0.014 (2)0.0005 (10)−0.0066 (12)−0.0031 (11)
C40.022 (2)0.022 (2)0.022 (2)−0.0005 (10)−0.0092 (12)−0.0064 (12)
C50.011 (5)0.019 (5)0.028 (5)−0.002 (4)−0.002 (4)−0.014 (4)
C60.021 (2)0.021 (2)0.020 (2)0.0002 (10)−0.0092 (12)−0.0055 (11)
C70.020 (2)0.020 (2)0.019 (2)0.0004 (10)−0.0088 (12)−0.0048 (11)

Geometric parameters (Å, °)

Cu1—O3i1.934 (5)O2—C31.244 (7)
Cu1—O31.934 (5)O3—H3A0.8200
Cu1—N11.986 (6)O3—H3B0.8388
Cu1—N1i1.986 (6)O4—H4A0.8242
N1—C51.329 (8)O4—H4B0.8243
N1—C11.401 (8)Cl1—C51.711 (7)
N2—C31.407 (8)C1—C41.333 (9)
N2—C21.442 (8)C1—C21.351 (9)
N2—C61.472 (8)C6—H6A0.9600
N3—C31.369 (8)C6—H6B0.9600
N3—C41.402 (8)C6—H6C0.9600
N3—C71.479 (7)C7—H7A0.9600
N4—C51.361 (8)C7—H7B0.9600
N4—C41.347 (9)C7—H7C0.9600
O1—C21.234 (8)
O3i—Cu1—O3180.0 (3)O1—C2—N2118.4 (7)
O3i—Cu1—N190.5 (2)C1—C2—N2110.6 (7)
O3—Cu1—N189.5 (2)O2—C3—N3123.4 (6)
O3i—Cu1—N1i89.5 (2)O2—C3—N2120.1 (7)
O3—Cu1—N1i90.5 (2)N3—C3—N2116.5 (6)
N1—Cu1—N1i180.000 (1)C1—C4—N4116.5 (7)
C5—N1—C1104.1 (6)C1—C4—N3119.0 (7)
C5—N1—Cu1131.8 (5)N4—C4—N3124.4 (7)
C1—N1—Cu1122.9 (5)N1—C5—N4116.4 (7)
C3—N2—C2125.4 (6)N1—C5—Cl1122.0 (6)
C3—N2—C6115.4 (6)N4—C5—Cl1121.6 (6)
C2—N2—C6119.2 (6)N2—C6—H6A109.5
C3—N3—C4120.1 (6)N2—C6—H6B109.5
C3—N3—C7118.8 (6)H6A—C6—H6B109.5
C4—N3—C7121.0 (6)N2—C6—H6C109.5
C5—N4—C498.7 (6)H6A—C6—H6C109.5
Cu1—O3—H3A109.4H6B—C6—H6C109.5
Cu1—O3—H3B132.7N3—C7—H7A109.5
H3A—O3—H3B112.4N3—C7—H7B109.5
H4A—O4—H4B118.2H7A—C7—H7B109.5
C4—C1—C2128.2 (7)N3—C7—H7C109.5
C4—C1—N1104.3 (7)H7A—C7—H7C109.5
C2—C1—N1127.5 (7)H7B—C7—H7C109.5
O1—C2—C1131.0 (7)

Symmetry codes: (i) −x+1, −y, −z+2.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O3—H3A···O2ii0.821.982.729 (7)154
O3—H3B···O4iii0.841.812.612 (8)159
O4—H4A···O1iv0.822.072.897 (9)176
O4—H4B···N40.822.032.839 (8)170

Symmetry codes: (ii) −x+1, −y+1, −z+1; (iii) x, y, z+1; (iv) x+1, y, z−1.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BG2201).

References

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