Di-μ-chloro-bis­[aqua­(caffeine)chloro­copper(II)]

The title compound, di-μ-chloro-bis­[aqua­chloro­(3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione)copper(II)], [Cu₂Cl₄(C₈H₁₀N₃O₂)₂(H₂O)₂], has the same chemical empirical formula as another compound [Bandoli et al. (1976). Inorg. Chim. Acta, 20, 71–78]. However, the title compound is a dimer arranged around an inversion centre, whereas Bandoli's compound is a chiral polymer. In the title compound, the Cu^II atom has a distorted tetra­gonal pyramidal coordination, formed by three Cl atoms, one N atom of the caffeine ligand and one O atom of a water mol­ecule.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.030
• wR factor = 0.060
• Data-to-parameter ratio = 13.9

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Cu     -   Cl2_a   ..       5.31 su

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: XSCANS (Siemens, 1994); cell refinement: XSCANS; data reduction: SHELXTL; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996), ORTEP-3 for Windows (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXTL (Bruker, 1998).

Di-µ-chloro-bis[aquachloro(3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6- dione)copper(II)]

Crystal data

[Cu2Cl4(C8H10N3O2)2(H2O)2]	F(000) = 700
Mr = 693.33	Dx = 1.794 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 34 reflections
a = 9.761 (2) Å	θ = 6.1–14.3°
b = 12.891 (3) Å	µ = 2.12 mm^−1
c = 10.901 (2) Å	T = 296 K
β = 110.64 (2)°	Prism, green
V = 1283.6 (5) Å^3	0.32 × 0.30 × 0.30 mm
Z = 2

Data collection

Siemens P4 diffractometer	1569 reflections with I > 2σ(I)
Radiation source: normal-focus sealed tube	Rint = 0.050
Graphite monochromator	θmax = 25.5°, θmin = 2.4°
ω scans	h = 0→11
Absorption correction: ψ scan (North et al., 1968)	k = 0→15
Tmin = 0.504, Tmax = 0.536	l = −13→12
2763 measured reflections	3 standard reflections every 97 reflections
2393 independent reflections	intensity decay: 0.5%

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.060	H atoms treated by a mixture of independent and constrained refinement
S = 0.80	w = 1/[σ^2(Fo^2) + (0.0292P)^2] where P = (Fo^2 + 2Fc^2)/3
2392 reflections	(Δ/σ)max < 0.001
172 parameters	Δρmax = 0.30 e Å^−3
3 restraints	Δρmin = −0.33 e Å^−3

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 (Ų)

	x	y	z	Uiso*/Ueq
Cu	0.61575 (4)	0.57731 (3)	0.62619 (4)	0.02983 (12)
Cl1	0.70757 (9)	0.69624 (7)	0.52602 (8)	0.0411 (2)
Cl2	0.66492 (9)	0.43860 (7)	0.52109 (8)	0.0365 (2)
O1	0.9899 (3)	0.60924 (17)	1.1641 (2)	0.0439 (6)
O2	0.6652 (2)	0.36421 (18)	1.1901 (2)	0.0408 (6)
O3	0.5620 (3)	0.68995 (17)	0.7277 (2)	0.0368 (6)
H3A	0.489 (2)	0.674 (2)	0.748 (3)	0.044*
H3B	0.550 (3)	0.7501 (13)	0.694 (3)	0.044*
N1	0.6228 (3)	0.48816 (19)	0.7815 (2)	0.0282 (6)
N2	0.8182 (3)	0.55930 (18)	0.9716 (2)	0.0257 (6)
N3	0.8227 (3)	0.4911 (2)	1.1749 (2)	0.0299 (6)
N4	0.5312 (3)	0.37820 (19)	0.8901 (2)	0.0280 (6)
C1	0.7000 (3)	0.4966 (2)	0.9128 (3)	0.0238 (7)
C2	0.8838 (3)	0.5570 (2)	1.1070 (3)	0.0297 (8)
C3	0.7062 (3)	0.4223 (3)	1.1218 (3)	0.0290 (7)
C4	0.6461 (3)	0.4307 (2)	0.9812 (3)	0.0237 (6)
C5	0.5229 (3)	0.4142 (3)	0.7733 (3)	0.0334 (8)
H5	0.4553	0.3907	0.6945	0.040*
C6	0.8815 (3)	0.6284 (3)	0.8987 (3)	0.0363 (8)
H6A	0.8654	0.5997	0.8135	0.054*
H6B	0.9848	0.6354	0.9455	0.054*
H6C	0.8358	0.6953	0.8895	0.054*
C7	0.8927 (4)	0.4938 (3)	1.3194 (3)	0.0480 (10)
H7A	0.9888	0.4640	1.3446	0.072*
H7B	0.8346	0.4549	1.3582	0.072*
H7C	0.9002	0.5644	1.3491	0.072*
C8	0.4419 (4)	0.2951 (2)	0.9136 (3)	0.0393 (9)
H8A	0.3645	0.2781	0.8330	0.059*
H8B	0.4007	0.3175	0.9771	0.059*
H8C	0.5018	0.2350	0.9460	0.059*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu	0.0320 (2)	0.0299 (2)	0.0296 (2)	−0.0022 (2)	0.01328 (17)	0.0015 (2)
Cl1	0.0404 (5)	0.0419 (5)	0.0437 (5)	−0.0147 (4)	0.0181 (4)	0.0026 (4)
Cl2	0.0334 (5)	0.0413 (5)	0.0366 (5)	0.0025 (4)	0.0147 (4)	−0.0044 (4)
O1	0.0474 (15)	0.0378 (14)	0.0385 (14)	−0.0134 (12)	0.0052 (12)	−0.0049 (12)
O2	0.0484 (15)	0.0461 (15)	0.0361 (13)	−0.0055 (13)	0.0251 (12)	0.0047 (12)
O3	0.0442 (15)	0.0278 (14)	0.0445 (15)	0.0010 (12)	0.0233 (12)	0.0035 (12)
N1	0.0303 (15)	0.0273 (15)	0.0264 (15)	−0.0019 (13)	0.0095 (12)	0.0013 (12)
N2	0.0261 (14)	0.0222 (15)	0.0306 (14)	−0.0025 (12)	0.0122 (12)	0.0008 (12)
N3	0.0338 (15)	0.0328 (16)	0.0237 (14)	−0.0017 (13)	0.0109 (12)	−0.0016 (12)
N4	0.0275 (15)	0.0252 (14)	0.0333 (16)	0.0008 (12)	0.0134 (13)	0.0010 (12)
C1	0.0243 (17)	0.0225 (16)	0.0277 (17)	0.0036 (14)	0.0131 (14)	0.0008 (14)
C2	0.0295 (18)	0.0262 (19)	0.0326 (18)	0.0014 (15)	0.0100 (15)	−0.0028 (15)
C3	0.0319 (18)	0.0277 (17)	0.0316 (17)	0.0062 (17)	0.0165 (15)	−0.0003 (17)
C4	0.0227 (15)	0.0199 (15)	0.0306 (16)	−0.0001 (14)	0.0120 (13)	−0.0019 (15)
C5	0.0291 (18)	0.0332 (19)	0.0360 (19)	−0.0016 (16)	0.0089 (15)	−0.0029 (17)
C6	0.0326 (19)	0.0340 (19)	0.044 (2)	−0.0064 (16)	0.0155 (17)	0.0067 (16)
C7	0.055 (2)	0.058 (3)	0.0266 (18)	−0.009 (2)	0.0081 (18)	−0.0033 (18)
C8	0.035 (2)	0.0281 (19)	0.053 (2)	−0.0064 (16)	0.0141 (18)	−0.0002 (17)

Geometric parameters (Å, º)

Cu—O3	2.004 (2)	N3—C7	1.480 (4)
Cu—N1	2.027 (2)	N4—C5	1.331 (4)
Cu—Cl1	2.2442 (10)	N4—C4	1.384 (4)
Cu—Cl2	2.2646 (10)	N4—C8	1.459 (4)
Cu—Cl2^i	2.6503 (11)	C1—C4	1.353 (4)
Cl2—Cu^i	2.6503 (11)	C3—C4	1.439 (4)
O1—C2	1.208 (4)	C5—H5	0.9300
O2—C3	1.219 (3)	C6—H6A	0.9600
O3—H3A	0.844 (10)	C6—H6B	0.9600
O3—H3B	0.847 (10)	C6—H6C	0.9600
N1—C5	1.344 (4)	C7—H7A	0.9600
N1—C1	1.367 (3)	C7—H7B	0.9600
N2—C1	1.369 (4)	C7—H7C	0.9600
N2—C2	1.386 (4)	C8—H8A	0.9600
N2—C6	1.468 (3)	C8—H8B	0.9600
N3—C2	1.392 (4)	C8—H8C	0.9600
N3—C3	1.397 (4)
O3—Cu—N1	83.58 (10)	O1—C2—N3	121.1 (3)
O3—Cu—Cl1	90.04 (7)	N2—C2—N3	117.1 (3)
N1—Cu—Cl1	153.12 (8)	O2—C3—N3	122.1 (3)
O3—Cu—Cl2	174.15 (7)	O2—C3—C4	126.8 (3)
N1—Cu—Cl2	91.38 (8)	N3—C3—C4	111.1 (3)
Cl1—Cu—Cl2	95.80 (4)	C1—C4—N4	106.6 (3)
O3—Cu—Cl2^i	88.55 (8)	C1—C4—C3	122.8 (3)
N1—Cu—Cl2^i	100.68 (8)	N4—C4—C3	130.5 (3)
Cl1—Cu—Cl2^i	105.25 (4)	N4—C5—N1	112.7 (3)
Cl2—Cu—Cl2^i	89.46 (4)	N4—C5—H5	123.7
Cu—Cl2—Cu^i	90.54 (4)	N1—C5—H5	123.7
Cu—O3—H3A	112 (2)	N2—C6—H6A	109.5
Cu—O3—H3B	117 (2)	N2—C6—H6B	109.5
H3A—O3—H3B	110 (2)	H6A—C6—H6B	109.5
C5—N1—C1	104.2 (2)	N2—C6—H6C	109.5
C5—N1—Cu	122.4 (2)	H6A—C6—H6C	109.5
C1—N1—Cu	132.3 (2)	H6B—C6—H6C	109.5
C1—N2—C2	118.9 (2)	N3—C7—H7A	109.5
C1—N2—C6	123.4 (2)	N3—C7—H7B	109.5
C2—N2—C6	117.7 (2)	H7A—C7—H7B	109.5
C2—N3—C3	127.3 (3)	N3—C7—H7C	109.5
C2—N3—C7	115.3 (3)	H7A—C7—H7C	109.5
C3—N3—C7	117.4 (3)	H7B—C7—H7C	109.5
C5—N4—C4	106.0 (3)	N4—C8—H8A	109.5
C5—N4—C8	125.8 (3)	N4—C8—H8B	109.5
C4—N4—C8	128.0 (3)	H8A—C8—H8B	109.5
C4—C1—N1	110.4 (3)	N4—C8—H8C	109.5
C4—C1—N2	122.7 (3)	H8A—C8—H8C	109.5
N1—C1—N2	126.9 (3)	H8B—C8—H8C	109.5
O1—C2—N2	121.8 (3)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C5—H5···Cl1^i	0.93	2.62	3.544 (3)	172
O3—H3A···O2^ii	0.84 (1)	1.92 (1)	2.758 (3)	175 (3)
O3—H3B···O1^iii	0.85 (1)	1.90 (2)	2.708 (3)	159 (3)

Symmetry codes: (i) −x+1, −y+1, −z+1; (ii) −x+1, −y+1, −z+2; (iii) x−1/2, −y+3/2, z−1/2.