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

Ji-Hua Deng; Zhi-Xing Xiong; Yan-Ping Yi; Lin Yuan; Hui-Rui Guo; Meng-Ping Guo; Lin Liu

doi:10.1107/S160053680802549X

. 2008 Aug 13;64(Pt 9):m1159–m1160. doi: 10.1107/S160053680802549X

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

Ji-Hua Deng ^a,^*, Zhi-Xing Xiong ^a, Yan-Ping Yi ^a, Lin Yuan ^a, Hui-Rui Guo ^a, Meng-Ping Guo ^a,^*, Lin Liu ^a

PMCID: PMC2960592 PMID: 21201609

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 ▶); Antholine et al. (1985 ▶); García-Tojal et al. (1996 ▶); Okabe et al. (1993 ▶); Saryan et al. (1979 ▶); Serafin (1996 ▶); Spealman (1988 ▶); West et al. (1993 ▶); Zhao et al. (2003 ▶).

Experimental

Crystal data

[Cu(C₇H₆ClN₄O₂)₂(H₂O)₂]·2H₂O
M _r = 562.82
Triclinic,
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 ▶) 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
Δρ_max = 0.54 e Å⁻³
Δρ_min = −0.66 e Å⁻³

Data collection: SMART (Bruker, 2004 ▶); cell refinement: SAINT (Bruker, 2004 ▶); 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 (Sheldrick, 2008 ▶).

Supplementary Material

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

e-64-m1159-sup1.cif^{(15.9KB, cif)}

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

e-64-m1159-Isup2.hkl^{(90.3KB, hkl)}

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

Table 1. Selected geometric parameters (Å, °).

Cu1—O3	1.934 (5)
Cu1—N1	1.986 (6)

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O3ⁱ—Cu1—O3	180
O3—Cu1—N1	89.5 (2)
O3—Cu1—N1ⁱ	90.5 (2)
N1—Cu1—N1ⁱ	180

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Symmetry code: (i) Inline graphic .

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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3A⋯O2ⁱⁱ	0.82	1.98	2.729 (7)	154
O3—H3B⋯O4ⁱⁱⁱ	0.84	1.81	2.612 (8)	159
O4—H4A⋯O1^iv	0.82	2.07	2.897 (9)	176
O4—H4B⋯N4	0.82	2.03	2.839 (8)	170

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Symmetry codes: (ii) Inline graphic ; (iii) ; (iv) .

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 copper^II 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).