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The crystal structure of the title compound, [Cu2Cl4(C9H7NO)2], has been determined from powder diffraction data. The crystals are built of dinuclear complex mol­ecules, with a central four-membered Cu2O2 ring located about a crystallographic inversion centre, which involves two Cu atoms, each carrying two terminal chloro ligands each [Cu—Cl = 2.213 (8) and 2.222 (8) Å] and two O atoms of the quinoline N-oxide ligand. The Cu atom has a square-planar coordination, with considerable distortions due to the four-membered ring [O—Cu—O = 78 (1)° and Cl—Cu—Cl = 100.2 (3)°].

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802020561/ya6147sup1.cif
Contains datablocks I, global

rtv

Rietveld powder data file (CIF format) https://doi.org/10.1107/S1600536802020561/ya6147Isup2.rtv
Contains datablock I

pdf

Portable Document Format (PDF) file https://doi.org/10.1107/S1600536802020561/ya6147sup3.pdf
Supplementary material

CCDC reference: 202286

Key indicators

  • Powder unknown study
  • T = 293 K
  • Mean [sigma](Please check) = 0.000 Å
  • R factor = 0.000
  • wR factor = 0.000
  • Data-to-parameter ratio = 0.0

checkCIF results

No syntax errors found

Structure: I
------------

ADDSYM reports no extra symmetry


Red Alert Alert Level A:
RADNT_01 Alert A The radiation type should contain one of the following * 'Cu K\a' * 'Mo K\a' * 'Ag K\a' * neutron * synchrotron REFLT_03 _reflns_number_total not in the CIF REFNR_01 Alert A Ratio of reflections to parameters is < 6 for a centrosymmetric structure sine(theta)/lambda 0.2961 Proportion of unique data used NaN Ratio reflections to parameters 0.0000 THETM_01 Alert A The value of sine(theta_max)/wavelength is less than 0.550 Calculated sin(theta_max)/wavelength = 0.2961 General Notes
ABSMU_01 Radiation type not identified. Calculation of _exptl_absorpt_correction_mu not performed.
3 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
0 Alert Level C = Please check

Comment top

Heteroaromatic N-oxides are unique compounds due to the fact that the N—O group can act either as an electron-acceptor or an electron-donor, depending on compound structure and conditions. Molecular complexes of heteroaromatic N-oxides demonstrate a broad spectrum of biological activity (Ponomarenko, 1999). Moreover adducts of quinoline N-oxide with CuCl2 have interesting magnetic properties (Whyman et al., 1967).

The electronic spectrum of the title complex, (I), in ethanol is almost identical to the spectrum of quinoline N-oxide; however, in CH2Cl2, which is not capable of forming donor–acceptor bonds, a new band appears [379(2.83)] and bands decrease their intensities. Such an effect is probably caused by symmetrization of the structure of the complex (decreasing logε) and formation of new Cu—O bonds.

The intensities of the N—O bands in the IR spectra (1310 and 1272 cm−1) are decreased in (I) in comparison with the spectrum of the parent quinoline N-oxide. On the other hand, in agreement with the literature findings (Garvey et al., 1968), a new bands at 1175 cm−1, caused by the formation of a donor–acceptor bond between the O atom of quinoline N-oxide and Cu atoms, appears; the 343–336 cm−1 bands corresponding to the Cu–Cl bonds are also present.

The structure of the dimeric molecule consists of a binuclear complex with a central four-membered Cu2O2 ring, formed by two Cu atoms and two quinoline N-oxide O atoms (Fig. 1). The structure is similar to that of di-m-(pyridine oxide)-bis[dichlorocopper(II)] reported by Sager et al. (1967). The Cu atom has a distorted square-planar coordination formed by two terminal chloro ligands [Cu—Cl1 = 2.222 (8) Å and Cu—Cl2 = 2.213 (8) Å] and two bridging O atoms belonging to quinoline N-oxide ligands [Cu—O1 = 2.11 (2) Å and Cu—O1i 2.00 (2) Å; symmetry code: (i) 1 − x, 1 − y, 1 − z]. The distortions of the coordination are manifested in the O1—Cu—O1i and Cl1—Cu—Cl2 bond angles [78 (1) and 100.2 (3)°, respectively], which deviate significantly from 90°, as well as in the displacement of the Cu atom from the plane through its four ligands [0.21 (3) Å]. The plane of the Cu2O2 ring forms a dihedral angle of 90 (2)° with the quinoline fragment.

Experimental top

Compound (I) was prepared in polycrystalline form by mixing saturated ethanol solutions of quinoline N-oxide dihydrate (0.181 g, 1 mmol) and CuCl2·2H2O (0.171 g, 1 mmol). A yellow precipitate, which quickly turned black, was washed with ethanol and diethyl ether. It was then dried in air (yield: 58°). The electronic spectra of (I) were recorded using a Specord UV-Vis spectrometer in ethanol and in CH2Cl2. The IR spectra were measured in KBr using a Specord M-80 spectrometer.

Refinement top

X-ray powder diffraction patterns were obtained with two X-ray powder instruments, i.e. a Guinier-de Wolff camera and a DRON-4.07 diffraction system equipped with a standard resolution goniometer GUR-9 and scintillation counter. The first pattern was used for indexing and the second pattern was measured for structure solution and refinement. The powder was sprinkled on the sample to avoid preferred orientation. During the exposures, the specimen was spun in its plane to improve particle statistics. The unit-cell dimensions were determined using the indexing program TREOR (Werner et al., 1985) with M20 = 39 and F29 = 59 (0.0076, 65) using the positions of the first 66 peaks.

The correct solution was found in monoclinic space group P21/n. The structure was determined using the MRIA program (Zlokazov & Chernyshev, 1992), using grid search (Chernyshev & Schenk, 1998) and simulated annealing (Zhukov et al., 2001) techniques. The strength of the restraints was a function of interatomic separation and, for intramolecular bond lengths, corresponds to an r.m.s. deviation of 0.03 Å. An additional restraint was applied to the planarity of the quinoline N-oxide fragment. Isotropic atomic displacement parameters were refined for Cu and Cl, and an overall Uiso parameter was used for the rest of non-H atoms. H atoms were placed in geometrically calculated positions and allowed to refine using bond restraints, with a common isotropic displacement parameter Uiso(H) fixed at 0.051 Å2. The diffraction profiles are shown in Fig. 2.

Computing details top

Data collection: local program; cell refinement: LSPAID (Visser, 1986); data reduction: local program; program(s) used to solve structure: MRIA (Zlokazov & Chernyshev, 1992); program(s) used to refine structure: MRIA; molecular graphics: PLATON (Spek, 2000); software used to prepare material for publication: MRIA, SHELXL97 (Sheldrick, 1997) and PARST (Nardelli, 1983).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I) with the atomic numbering.
[Figure 2] Fig. 2. The Rietveld plot for (I), showing the observed and difference profiles. The reflection positions are shown above the difference profile.
(I) top
Crystal data top
[Cu2Cl4(C9H7NO)2]F(000) = 556
Mr = 559.02Dx = 1.767 Mg m3
Monoclinic, P21/nMelting point: 208(1) K
a = 11.780 (3) ÅFe Kα radiation, λ = 1.93728 Å
b = 14.872 (5) ÅT = 293 K
c = 6.061 (2) ÅParticle morphology: no specific habit
β = 98.27 (2)°black
V = 1050.8 (6) Å3flat_sheet, 12 × 12 mm
Z = 2
Data collection top
X-ray powder diffraction system DRON-4.07
diffractometer
Data collection mode: reflection
Radiation source: BSV-28, line-focus sealed tubeScan method: step
Pyrolitic graphite crystal monochromator2θmin = 10°, 2θmax = 70°, 2θstep = 0.1°
Specimen mounting: The powder was sprinkled on the sample holder.
Refinement top
Refinement on Inet77 parameters
Least-squares matrix: full with fixed elements per cycle1 constraint
Rp = 0.064H-atom parameters constrained
Rwp = 0.081 w = 1/Ymeas2
Rexp = 0.029(Δ/σ)max = 0.02
χ2 = 7.840Background function: Chebyshev polynomial up to the 5th order
601 data pointsPreferred orientation correction: Spherical harmonics expansion (Ahtee et al., 1989) up to the 6th order
Profile function: split-type pseudo-Voigt (Toraya, 1986)
Crystal data top
[Cu2Cl4(C9H7NO)2]β = 98.27 (2)°
Mr = 559.02V = 1050.8 (6) Å3
Monoclinic, P21/nZ = 2
a = 11.780 (3) ÅFe Kα radiation, λ = 1.93728 Å
b = 14.872 (5) ÅT = 293 K
c = 6.061 (2) Åflat_sheet, 12 × 12 mm
Data collection top
X-ray powder diffraction system DRON-4.07
diffractometer
Scan method: step
Specimen mounting: The powder was sprinkled on the sample holder.2θmin = 10°, 2θmax = 70°, 2θstep = 0.1°
Data collection mode: reflection
Refinement top
Rp = 0.064601 data points
Rwp = 0.08177 parameters
Rexp = 0.029H-atom parameters constrained
χ2 = 7.840
Special details top

Experimental. specimen was rotated in its plane

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cu0.6088 (3)0.4852 (3)0.3751 (5)0.048 (1)*
Cl10.6301 (5)0.3910 (4)0.0995 (12)0.074 (3)*
Cl20.7791 (6)0.5509 (5)0.4219 (9)0.081 (3)*
O10.4408 (15)0.4384 (10)0.384 (3)0.087 (3)*
N10.3980 (18)0.3627 (13)0.304 (4)0.087 (3)*
C20.330 (2)0.3629 (18)0.098 (5)0.087 (3)*
C30.286 (2)0.283 (2)0.002 (4)0.087 (3)*
C40.312 (2)0.2013 (19)0.107 (5)0.087 (3)*
C50.404 (2)0.1175 (16)0.427 (4)0.087 (3)*
C60.471 (2)0.1138 (17)0.636 (5)0.087 (3)*
C70.517 (2)0.194 (2)0.735 (4)0.087 (3)*
C80.492 (2)0.2761 (16)0.627 (4)0.087 (3)*
C90.424 (2)0.2820 (18)0.416 (4)0.087 (3)*
C100.380 (2)0.2001 (19)0.317 (4)0.087 (3)*
H20.31320.41720.02070.051*
H30.24130.28440.14230.051*
H40.28110.14760.04470.051*
H50.37400.06460.35800.051*
H60.48830.05870.70660.051*
H70.56170.19210.87520.051*
H80.52360.32900.69350.051*
Geometric parameters (Å, º) top
Cu—O12.11 (2)C7—C81.40 (4)
Cu—O1i2.00 (2)C9—N11.39 (3)
Cu—Cl22.213 (8)C9—C81.41 (3)
Cu—Cl12.222 (8)C9—C101.42 (4)
O1—N11.30 (2)C2—H20.94
C2—N11.38 (3)C3—H30.93
C2—C31.40 (4)C4—H40.93
C4—C31.40 (4)C5—H50.93
C4—C101.40 (4)C6—H60.93
C5—C61.40 (4)C7—H70.93
C5—C101.41 (4)C8—H80.94
C7—C61.40 (4)
O1i—Cu—O178 (1)C5—C10—C9121 (2)
O1i—Cu—Cl1169.2 (6)C6—C5—C10121 (2)
O1—Cu—Cl2168.8 (5)C6—C7—C8120 (3)
O1i—Cu—Cl290.6 (5)C7—C8—C9122 (2)
O1—Cu—Cl191.1 (5)C8—C9—C10117 (2)
Cl2—Cu—Cl1100.2 (3)N1—C2—H2120
Cui—O1—Cu101.8 (1)C3—C2—H2118
N1—O1—Cu126.3 (15)C4—C3—H3121
N1i—O1—O1164.8 (5)C2—C3—H3120
N1—C9—C8124 (2)C3—C4—H4120
N1—C9—C10119 (2)C10—C4—H4120
N1—C2—C3121 (2)C6—C5—H5120
O1—N1—C2119 (2)C10—C5—H5119
O1—N1—C9121 (2)C5—C6—H6120
C2—N1—C9120 (2)C7—C6—H6120
C3—C4—C10120 (2)C6—C7—H7120
C4—C3—C2119 (3)C8—C7—H7120
C4—C10—C5119 (2)C7—C8—H8120
C4—C10—C9120 (2)C9—C8—H8118
C5—C6—C7119 (2)
Cl1—Cu—O1—N120 (2)Cu—O1—N1—C2100 (2)
Symmetry code: (i) x+1, y+1, z+1.

Experimental details

Crystal data
Chemical formula[Cu2Cl4(C9H7NO)2]
Mr559.02
Crystal system, space groupMonoclinic, P21/n
Temperature (K)293
a, b, c (Å)11.780 (3), 14.872 (5), 6.061 (2)
β (°) 98.27 (2)
V3)1050.8 (6)
Z2
Radiation typeFe Kα, λ = 1.93728 Å
Specimen shape, size (mm)Flat_sheet, 12 × 12
Data collection
DiffractometerX-ray powder diffraction system DRON-4.07
diffractometer
Specimen mountingThe powder was sprinkled on the sample holder.
Data collection modeReflection
Scan methodStep
2θ values (°)2θmin = 10 2θmax = 70 2θstep = 0.1
Refinement
R factors and goodness of fitRp = 0.064, Rwp = 0.081, Rexp = 0.029, χ2 = 7.840
No. of data points601
No. of parameters77
No. of restraints?
H-atom treatmentH-atom parameters constrained

Computer programs: local program, LSPAID (Visser, 1986), MRIA (Zlokazov & Chernyshev, 1992), PLATON (Spek, 2000), MRIA, SHELXL97 (Sheldrick, 1997) and PARST (Nardelli, 1983).

Selected geometric parameters (Å, º) top
Cu—O12.11 (2)Cu—Cl22.213 (8)
Cu—O1i2.00 (2)Cu—Cl12.222 (8)
O1i—Cu—O178 (1)Cl2—Cu—Cl1100.2 (3)
O1—Cu—Cl2168.8 (5)Cui—O1—Cu101.8 (1)
O1—Cu—Cl191.1 (5)N1—O1—Cu126.3 (15)
Cl1—Cu—O1—N120 (2)Cu—O1—N1—C2100 (2)
Symmetry code: (i) x+1, y+1, z+1.
 

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