Diaqua­bis(8-chloro-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetra­hydro-7H-purinato-κN7)copper(II) dihydrate

Deng, J.-H.; Xiong, Z.-X.; Yi, Y.-P.; Yuan, L.; Guo, H.-R.; Guo, M.-P.; Liu, L.

doi:10.1107/S160053680802549X

metal-organic compounds

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ISSN: 2056-9890

Volume 64| Part 9| September 2008| Pages m1159-m1160

doi:10.1107/S160053680802549X

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Diaquabis(8-chloro-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purinato-κN⁷)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 ^* and Lin Liu ^a

^aCollege of Chemistry and Bio-engineering, Yichun University, Yichun, Jiangxi 336000, People's Republic of China
^*Correspondence e-mail: djhycu_2006@yahoo.com.cn, guomengping65@163.com

(Received 31 July 2008; accepted 7 August 2008; online 13 August 2008)

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, $[P \overline 1]$
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[F² > 2σ(F²)] = 0.058
wR(F²) = 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

Table 1
Selected geometric parameters (Å, °)

Cu1—O3	1.934 (5)
Cu1—N1	1.986 (6)

O3ⁱ—Cu1—O3	180
O3—Cu1—N1	89.5 (2)
O3—Cu1—N1ⁱ	90.5 (2)
N1—Cu1—N1ⁱ	180
Symmetry code: (i) -x+1, -y, -z+2.

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

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).

Supporting information

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

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

checkCIF report

Comment top

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.

Related literature top

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 top

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).

Computing details top

Data collection: SMART (Bruker, 2004); cell refinement: SMART (Bruker, 2004); data reduction: SAINT (Bruker, 2004); 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).

Figures top

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

Diaquabis(8-chloro-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purinato- κN⁷)copper(II) dihydrate top

Crystal data top

[Cu(C₇H₆ClN₄O₂)₂(H₂O)₂]·2H₂O	Z = 1
M_r = 562.82	F(000) = 287
Triclinic, P1	D_x = 1.776 Mg m⁻³
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 8.377 (5) Å	Cell parameters from 822 reflections
b = 8.533 (8) Å	θ = 2.6–25.0°
c = 8.830 (3) Å	µ = 1.35 mm⁻¹
α = 67.999 (2)°	T = 293 K
β = 64.180 (7)°	Block, green
γ = 78.388 (6)°	0.36 × 0.24 × 0.16 mm
V = 526.2 (6) Å³

Data collection top

Bruker SMART CCD area-detector diffractometer	1834 independent reflections
Radiation source: fine-focus sealed tube	936 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.099
ϕ and ω scans	θ_max = 25.0°, θ_min = 2.6°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −9→9
T_min = 0.685, T_max = 0.802	k = −8→10
3811 measured reflections	l = −10→10

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.058	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.102	H-atom parameters constrained
S = 0.99	w = 1/[σ²(F_o²)]
1834 reflections	(Δ/σ)_max = 0.004
153 parameters	Δρ_max = 0.54 e Å⁻³
19 restraints	Δρ_min = −0.66 e Å⁻³

Crystal data top

[Cu(C₇H₆ClN₄O₂)₂(H₂O)₂]·2H₂O	γ = 78.388 (6)°
M_r = 562.82	V = 526.2 (6) Å³
Triclinic, P1	Z = 1
a = 8.377 (5) Å	Mo Kα radiation
b = 8.533 (8) Å	µ = 1.35 mm⁻¹
c = 8.830 (3) Å	T = 293 K
α = 67.999 (2)°	0.36 × 0.24 × 0.16 mm
β = 64.180 (7)°

Data collection top

Bruker SMART CCD area-detector diffractometer	1834 independent reflections
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	936 reflections with I > 2σ(I)
T_min = 0.685, T_max = 0.802	R_int = 0.099
3811 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.058	19 restraints
wR(F²) = 0.102	H-atom parameters constrained
S = 0.99	Δρ_max = 0.54 e Å⁻³
1834 reflections	Δρ_min = −0.66 e Å⁻³
153 parameters

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	U_iso*/U_eq
Cu1	0.5000	0.0000	1.0000	0.0214 (5)
N1	0.5200 (8)	0.0829 (8)	0.7503 (7)	0.0214 (17)
N2	0.1993 (8)	0.4308 (7)	0.6697 (7)	0.0203 (16)
N3	0.4180 (8)	0.3889 (8)	0.4053 (7)	0.0264 (18)
N4	0.6338 (8)	0.1570 (8)	0.4472 (8)	0.0245 (18)
O1	0.1930 (7)	0.2659 (6)	0.9464 (6)	0.0296 (15)
O2	0.2040 (6)	0.6046 (6)	0.3965 (6)	0.0210 (13)
O3	0.6720 (6)	0.1598 (6)	0.9341 (6)	0.0340 (15)
H3A	0.7154	0.2029	0.8256	0.051*
H3B	0.7376	0.1651	0.9815	0.051*
O4	0.8607 (7)	0.0978 (6)	0.1220 (6)	0.0330 (16)
H4A	0.9578	0.1413	0.0704	0.049*
H4B	0.7868	0.1226	0.2097	0.049*
Cl1	0.8042 (3)	−0.1040 (3)	0.6122 (3)	0.0308 (6)
C1	0.4156 (10)	0.2195 (9)	0.6872 (9)	0.0171 (19)
C2	0.2692 (10)	0.2944 (9)	0.7842 (10)	0.019 (2)
C3	0.2719 (10)	0.4812 (9)	0.4827 (9)	0.0142 (18)
C4	0.4889 (11)	0.2531 (10)	0.5113 (10)	0.022 (2)
C5	0.6432 (10)	0.0543 (9)	0.6041 (10)	0.019 (2)
C6	0.0408 (9)	0.5307 (9)	0.7496 (9)	0.021 (2)
H6A	0.0759	0.6360	0.7389	0.032*
H6B	−0.0203	0.4686	0.8731	0.032*
H6C	−0.0367	0.5527	0.6890	0.032*
C7	0.4918 (9)	0.4281 (9)	0.2102 (8)	0.020 (2)
H7A	0.3980	0.4704	0.1685	0.030*
H7B	0.5465	0.3273	0.1809	0.030*
H7C	0.5788	0.5122	0.1544	0.030*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Cu1	0.0267 (10)	0.0224 (10)	0.0140 (9)	−0.0032 (8)	−0.0113 (8)	0.0001 (7)
N1	0.019 (4)	0.027 (4)	0.017 (4)	−0.011 (3)	−0.010 (3)	0.001 (3)
N2	0.027 (4)	0.021 (4)	0.009 (3)	−0.004 (3)	−0.004 (3)	−0.003 (3)
N3	0.030 (5)	0.036 (5)	0.011 (4)	−0.006 (4)	−0.004 (3)	−0.008 (3)
N4	0.022 (4)	0.033 (4)	0.012 (4)	−0.006 (3)	−0.002 (3)	−0.003 (3)
O1	0.036 (4)	0.033 (4)	0.014 (3)	−0.006 (3)	−0.007 (3)	−0.003 (3)
O2	0.0205 (16)	0.0215 (16)	0.0201 (15)	0.0010 (9)	−0.0110 (10)	−0.0035 (10)
O3	0.052 (4)	0.038 (4)	0.013 (3)	−0.031 (3)	−0.015 (3)	0.008 (3)
O4	0.027 (4)	0.050 (4)	0.018 (3)	−0.005 (3)	−0.010 (3)	−0.004 (3)
Cl1	0.0279 (15)	0.0291 (15)	0.0273 (13)	0.0002 (11)	−0.0096 (11)	−0.0031 (11)
C1	0.027 (5)	0.014 (5)	0.009 (4)	0.002 (4)	−0.010 (4)	−0.002 (3)
C2	0.019 (2)	0.019 (2)	0.019 (2)	−0.0004 (10)	−0.0083 (12)	−0.0056 (11)
C3	0.014 (2)	0.014 (2)	0.014 (2)	0.0005 (10)	−0.0066 (12)	−0.0031 (11)
C4	0.022 (2)	0.022 (2)	0.022 (2)	−0.0005 (10)	−0.0092 (12)	−0.0064 (12)
C5	0.011 (5)	0.019 (5)	0.028 (5)	−0.002 (4)	−0.002 (4)	−0.014 (4)
C6	0.021 (2)	0.021 (2)	0.020 (2)	0.0002 (10)	−0.0092 (12)	−0.0055 (11)
C7	0.020 (2)	0.020 (2)	0.019 (2)	0.0004 (10)	−0.0088 (12)	−0.0048 (11)

Geometric parameters (Å, º) top

Cu1—O3ⁱ	1.934 (5)	O2—C3	1.244 (7)
Cu1—O3	1.934 (5)	O3—H3A	0.8200
Cu1—N1	1.986 (6)	O3—H3B	0.8388
Cu1—N1ⁱ	1.986 (6)	O4—H4A	0.8242
N1—C5	1.329 (8)	O4—H4B	0.8243
N1—C1	1.401 (8)	Cl1—C5	1.711 (7)
N2—C3	1.407 (8)	C1—C4	1.333 (9)
N2—C2	1.442 (8)	C1—C2	1.351 (9)
N2—C6	1.472 (8)	C6—H6A	0.9600
N3—C3	1.369 (8)	C6—H6B	0.9600
N3—C4	1.402 (8)	C6—H6C	0.9600
N3—C7	1.479 (7)	C7—H7A	0.9600
N4—C5	1.361 (8)	C7—H7B	0.9600
N4—C4	1.347 (9)	C7—H7C	0.9600
O1—C2	1.234 (8)

O3ⁱ—Cu1—O3	180.0 (3)	O1—C2—N2	118.4 (7)
O3ⁱ—Cu1—N1	90.5 (2)	C1—C2—N2	110.6 (7)
O3—Cu1—N1	89.5 (2)	O2—C3—N3	123.4 (6)
O3ⁱ—Cu1—N1ⁱ	89.5 (2)	O2—C3—N2	120.1 (7)
O3—Cu1—N1ⁱ	90.5 (2)	N3—C3—N2	116.5 (6)
N1—Cu1—N1ⁱ	180.000 (1)	C1—C4—N4	116.5 (7)
C5—N1—C1	104.1 (6)	C1—C4—N3	119.0 (7)
C5—N1—Cu1	131.8 (5)	N4—C4—N3	124.4 (7)
C1—N1—Cu1	122.9 (5)	N1—C5—N4	116.4 (7)
C3—N2—C2	125.4 (6)	N1—C5—Cl1	122.0 (6)
C3—N2—C6	115.4 (6)	N4—C5—Cl1	121.6 (6)
C2—N2—C6	119.2 (6)	N2—C6—H6A	109.5
C3—N3—C4	120.1 (6)	N2—C6—H6B	109.5
C3—N3—C7	118.8 (6)	H6A—C6—H6B	109.5
C4—N3—C7	121.0 (6)	N2—C6—H6C	109.5
C5—N4—C4	98.7 (6)	H6A—C6—H6C	109.5
Cu1—O3—H3A	109.4	H6B—C6—H6C	109.5
Cu1—O3—H3B	132.7	N3—C7—H7A	109.5
H3A—O3—H3B	112.4	N3—C7—H7B	109.5
H4A—O4—H4B	118.2	H7A—C7—H7B	109.5
C4—C1—C2	128.2 (7)	N3—C7—H7C	109.5
C4—C1—N1	104.3 (7)	H7A—C7—H7C	109.5
C2—C1—N1	127.5 (7)	H7B—C7—H7C	109.5
O1—C2—C1	131.0 (7)

Symmetry code: (i) −x+1, −y, −z+2.

Hydrogen-bond geometry (Å, º) top

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

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

Experimental details

Crystal data
Chemical formula	[Cu(C₇H₆ClN₄O₂)₂(H₂O)₂]·2H₂O
M_r	562.82
Crystal system, space group	Triclinic, P1
Temperature (K)	293
a, b, c (Å)	8.377 (5), 8.533 (8), 8.830 (3)
α, β, γ (°)	67.999 (2), 64.180 (7), 78.388 (6)
V (Å³)	526.2 (6)
Z	1
Radiation type	Mo Kα
µ (mm⁻¹)	1.35
Crystal size (mm)	0.36 × 0.24 × 0.16

Data collection
Diffractometer	Bruker SMART CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 1996)
T_min, T_max	0.685, 0.802
No. of measured, independent and observed [I > 2σ(I)] reflections	3811, 1834, 936
R_int	0.099
(sin θ/λ)_max (Å⁻¹)	0.595

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.058, 0.102, 0.99
No. of reflections	1834
No. of parameters	153
No. of restraints	19
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.54, −0.66

Computer programs: SMART (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Selected geometric parameters (Å, º) top

Cu1—O3ⁱ	1.934 (5)	Cu1—N1	1.986 (6)
Cu1—O3	1.934 (5)	Cu1—N1ⁱ	1.986 (6)

O3ⁱ—Cu1—O3	180.0 (3)	O3ⁱ—Cu1—N1ⁱ	89.5 (2)
O3ⁱ—Cu1—N1	90.5 (2)	O3—Cu1—N1ⁱ	90.5 (2)
O3—Cu1—N1	89.5 (2)	N1—Cu1—N1ⁱ	180.000 (1)

Symmetry code: (i) −x+1, −y, −z+2.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3A···O2ⁱⁱ	0.8200	1.9769	2.729 (7)	154
O3—H3B···O4ⁱⁱⁱ	0.8388	1.8135	2.612 (8)	159
O4—H4A···O1^iv	0.8242	2.0700	2.897 (9)	176
O4—H4B···N4	0.8243	2.0294	2.839 (8)	170

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

Acknowledgements

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

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