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The crystal structure of the title compound, [Cu(C2O4)(C10H8N2)]n, is reported. The CuII atom is six-coordinated with distorted octahedral geometry and the bi­pyridine ligand acts as a chelating ligand. The oxalate anion bridges the metal ions forming infinite chains.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536801011874/wn6031sup1.cif
Contains datablocks I, a

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536801011874/wn6031Isup2.hkl
Contains datablock I

CCDC reference: 170872

Key indicators

  • Single-crystal X-ray study
  • T = 293 K
  • Mean [sigma](C-C) = 0.015 Å
  • R factor = 0.051
  • wR factor = 0.108
  • Data-to-parameter ratio = 9.0

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


Yellow Alert Alert Level C:
ABSTM_02 Alert C The ratio of expected to reported Tmax/Tmin(RR) is > 1.10 Tmin and Tmax reported: 0.408 0.458 Tmin and Tmax expected: 0.531 0.666 RR = 1.117 Please check that your absorption correction is appropriate. STRVAL_01 From the CIF: _refine_ls_abs_structure_Flack 0.350 From the CIF: _refine_ls_abs_structure_Flack_su 0.040 Alert C Flack test results are ambiguous. PLAT_369 Alert C Long C(sp2)-C(sp2) Bond C(1) - C(2) = 1.55 Ang. General Notes
ABSTM_02 When printed, the submitted absorption T values will be replaced by the scaled T values. Since the ratio of scaled T's is identical to the ratio of reported T values, the scaling does not imply a change to the absorption corrections used in the study. Ratio of Tmax expected/reported 1.455 Tmax scaled 0.666 Tmin scaled 0.593 REFLT_03 From the CIF: _diffrn_reflns_theta_max 25.05 From the CIF: _reflns_number_total 1545 Count of symmetry unique reflns 1053 Completeness (_total/calc) 146.72% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 492 Fraction of Friedel pairs measured 0.467 Are heavy atom types Z>Si present yes WARNING: Large fraction of Friedel related reflns may be needed to determine absolute structure
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
3 Alert Level C = Please check

Comment top

Oxalate-bridged polymeric compounds have attracted much attention due to their interesting magnetic properties (Decurtins et al., 1994, and references therein). By reacting CuCl2, 2,2'-bipyridine (2,2'-bipy) and tetrahydroxy-1,4-benzoquinone, the title complex, [Cu(C2O4)(2,2'-bipy)]n, was obtained, with oxalate anions as bridging ligands. So far, there have been only a few such compounds reported, viz. [Cu(C2O4)(2,2'-bipy)].2H2O (Fitzgerald et al., 1982), [Mn(C2O4)(2,2'-bipy)]n (Deguenon et al., 1990) and [Fe(C2O4)(2,2'-bipy)]n (Fun et al., 1999).

The crystal structure of the title compound, which is isostructural with the FeII compound, consists of neutral [Cu(C2O4)(2,2'-bipy)] units, with the Cu atoms linked by C2O4 ligands to form infinite zigzag chains along the a axis. The Cu atom has a distorted octahedral coordination consisting of two N atoms from the chelating 2,2'-bipy ligand, two O atoms of the oxalate ligands in equatorial positions, and two O atoms of the oxalate ligands in axial positions. The largest deviation from the plane defined by Cu, N1, N2, O2 and O3i is -0.089Å at atom N1 [symmetry code: (i) x-1/2, -y+1/2, z]. The Cu—N bond lengths [1.991 (7) and 2.018 (7)Å] and the Cu—N—Cu bite angle [80.4 (3)°] are comparable to the corresponding values in [Cu2(bipy)2(H20)2(C2O4)]X2.[Cu(bipy)(C2O4)] (X = NO3-, BF4 or ClO4), [1.992 (2), 1.987 (2)Å and 82.92°; Gleizes et al., 1992]. The Cu—O distances [1.972 (6)–2.369 (7) Å] and the O—Cu—O bite angles [90.6 (2) and 85.3 (3)°] are in agreement with those in [Cu2(bipy)2(C2O4)(H20)2][Cu(bipy)(C2O4)](NO3)2 [1.971 (1)–2.247 (1)Å and 84.64 (3)°; Shi et al., 1997]; the bite angles are also close to those in [Mn(C2O4)(2,2'-bipy)]n (Deguenon et al., 1990) and [Fe(C2O4)(2,2'-bipy)]n (Fun et al., 1999). The dihedral angle between the planar pyridyl rings is 2.01°. The shortest Cu···Cu distances within the chain is 5.507Å. Neighbouring chains are connected to each other by van der Waals interactions, with the bipyridyl ligands stacked between the chains. The shortest Cu···Cu distance between adjacent chains is 7.793Å.

Experimental top

A solution of CuCl2·6H2O (0.085 g, 0.5 mmol) and tetrahydroxy-1,4-benzoquinone (0.10 g, 0.5 mmol) in methanol solution (20 ml) was stirred for 30 min at room temperature, then 2,2'-bipyridine (0.5 mmol) was added and the mixture was stirred for 1 h to give a green solution; this was filtered. Deep-green crystals were obtained by keeping the solution exposed to air for about a week. A green single-crystal was selected for X-ray diffraction.

Refinement top

H-atom positions were generated geometrically and the H atoms were allowed to ride on their respective parent C atoms.

Computing details top

Data collection: SMART (Siemens, 1994); cell refinement: SMART; data reduction: SMART; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXL97; software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. Part of the polymer chain of (I), showing 50% probability displacement ellipsoids and the labelling of the asymmetric unit.
Poly[(2,2'-bipyridine)copper(II)-µ4-oxalato] top
Crystal data top
[Cu(C2O4)(C10H8N2)]Dx = 1.799 Mg m3
Mr = 307.74Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pna21Cell parameters from 172 reflections
a = 8.0762 (11) Åθ = 2.5–25.1°
b = 9.9366 (13) ŵ = 1.93 mm1
c = 14.1558 (19) ÅT = 293 K
V = 1136.0 (3) Å3Plate, green
Z = 40.35 × 0.28 × 0.21 mm
F(000) = 620
Data collection top
Siemens SMART CCD
diffractometer
1545 independent reflections
Radiation source: fine-focus sealed tube1084 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.060
ω scansθmax = 25.1°, θmin = 2.5°
Absorption correction: empirical (using intensity measurements)
(SADABS; Sheldrick, 1996)
h = 99
Tmin = 0.408, Tmax = 0.458k = 116
3348 measured reflectionsl = 169
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.051H-atom parameters constrained
wR(F2) = 0.109 w = 1/[σ2(Fo2) + (0.0407P)2 + 0.3497P]
where P = (Fo2 + 2Fc2)/3
S = 1.05(Δ/σ)max < 0.001
1545 reflectionsΔρmax = 0.41 e Å3
172 parametersΔρmin = 0.46 e Å3
1 restraintAbsolute structure: Flack (1983), 100 Friedel pairs treated independently
Primary atom site location: structure-invariant direct methodsAbsolute structure parameter: 0.35 (4)
Crystal data top
[Cu(C2O4)(C10H8N2)]V = 1136.0 (3) Å3
Mr = 307.74Z = 4
Orthorhombic, Pna21Mo Kα radiation
a = 8.0762 (11) ŵ = 1.93 mm1
b = 9.9366 (13) ÅT = 293 K
c = 14.1558 (19) Å0.35 × 0.28 × 0.21 mm
Data collection top
Siemens SMART CCD
diffractometer
1545 independent reflections
Absorption correction: empirical (using intensity measurements)
(SADABS; Sheldrick, 1996)
1084 reflections with I > 2σ(I)
Tmin = 0.408, Tmax = 0.458Rint = 0.060
3348 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.051H-atom parameters constrained
wR(F2) = 0.109Δρmax = 0.41 e Å3
S = 1.05Δρmin = 0.46 e Å3
1545 reflectionsAbsolute structure: Flack (1983), 100 Friedel pairs treated independently
172 parametersAbsolute structure parameter: 0.35 (4)
1 restraint
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
xyzUiso*/Ueq
Cu10.12533 (13)0.43841 (8)0.13972 (12)0.0312 (3)
N10.2076 (10)0.5805 (6)0.2270 (5)0.0292 (18)
N20.0617 (10)0.6035 (6)0.0650 (5)0.0295 (17)
C10.3229 (14)0.2147 (10)0.1817 (6)0.027 (2)
C20.4065 (15)0.2653 (9)0.0896 (8)0.037 (3)
C30.2798 (14)0.5587 (9)0.3112 (6)0.041 (2)
H10.29960.47060.33010.049*
H20.37920.64100.42550.049*
H30.31250.86070.38760.049*
H40.19870.90180.23800.049*
H50.06770.92320.09680.049*
H60.05370.92060.04970.049*
H70.10460.71670.12450.049*
H80.02450.52320.04970.049*
C40.3246 (14)0.6604 (12)0.3692 (8)0.058 (3)
C50.2896 (18)0.7907 (12)0.3463 (9)0.055 (3)
C60.2177 (13)0.8146 (8)0.2582 (8)0.045 (3)
C70.1746 (13)0.7099 (10)0.2020 (7)0.031 (2)
C80.0942 (13)0.7189 (9)0.1094 (6)0.030 (3)
C90.0485 (13)0.8425 (8)0.0659 (7)0.038 (2)
C100.0240 (14)0.8408 (9)0.0207 (8)0.048 (3)
C110.0542 (18)0.7206 (11)0.0654 (8)0.046 (3)
C120.0070 (13)0.6056 (9)0.0195 (7)0.043 (3)
O10.3684 (9)0.1046 (5)0.2147 (5)0.0405 (16)
O20.2098 (9)0.2882 (6)0.2169 (4)0.0379 (16)
O30.5154 (8)0.1896 (5)0.0536 (4)0.0361 (16)
O40.3647 (8)0.3769 (5)0.0591 (4)0.0355 (15)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cu10.0360 (5)0.0233 (4)0.0343 (5)0.0008 (5)0.0004 (7)0.0027 (7)
N10.041 (5)0.025 (4)0.021 (4)0.003 (4)0.000 (4)0.002 (3)
N20.032 (4)0.025 (4)0.031 (4)0.001 (3)0.000 (4)0.004 (3)
C10.030 (6)0.027 (5)0.026 (5)0.001 (5)0.004 (4)0.006 (4)
C20.040 (8)0.028 (6)0.043 (6)0.003 (5)0.004 (5)0.001 (5)
C30.055 (7)0.042 (5)0.025 (5)0.005 (6)0.005 (5)0.002 (5)
C40.063 (9)0.073 (8)0.038 (6)0.006 (6)0.008 (6)0.006 (6)
C50.056 (10)0.061 (8)0.049 (8)0.009 (7)0.001 (7)0.027 (7)
C60.046 (7)0.030 (5)0.058 (7)0.006 (5)0.015 (6)0.016 (5)
C70.031 (6)0.035 (5)0.027 (6)0.013 (5)0.005 (5)0.015 (5)
C80.037 (7)0.019 (4)0.033 (7)0.005 (4)0.008 (5)0.003 (4)
C90.047 (6)0.020 (4)0.046 (6)0.009 (5)0.010 (6)0.004 (5)
C100.051 (7)0.042 (6)0.050 (6)0.009 (5)0.009 (6)0.016 (6)
C110.058 (9)0.047 (6)0.032 (6)0.006 (6)0.000 (6)0.010 (5)
C120.053 (7)0.032 (5)0.043 (6)0.006 (5)0.003 (6)0.006 (5)
O10.038 (4)0.035 (3)0.049 (4)0.002 (3)0.006 (4)0.017 (3)
O20.047 (5)0.033 (3)0.033 (4)0.008 (3)0.007 (3)0.005 (3)
O30.046 (4)0.031 (3)0.031 (4)0.014 (3)0.007 (3)0.008 (3)
O40.047 (4)0.024 (3)0.035 (3)0.001 (3)0.003 (4)0.013 (3)
Geometric parameters (Å, º) top
Cu1—O21.972 (6)C2—O41.237 (10)
Cu1—O3i1.973 (6)C2—O31.265 (11)
Cu1—N11.991 (7)C3—C41.352 (13)
Cu1—N22.018 (7)C4—C51.365 (15)
Cu1—O42.327 (6)C5—C61.395 (16)
Cu1—O1i2.369 (7)C6—C71.355 (13)
N1—C31.343 (11)C7—C81.466 (12)
N1—C71.360 (11)C8—C91.423 (12)
N2—C121.319 (12)C9—C101.359 (14)
N2—C81.334 (11)C10—C111.373 (14)
C1—O11.245 (10)C11—C121.369 (14)
C1—O21.271 (11)O1—Cu1ii2.369 (7)
C1—C21.552 (10)O3—Cu1ii1.973 (6)
O2—Cu1—O3i90.6 (2)O2—C1—C2117.1 (8)
O2—Cu1—N194.5 (3)O4—C2—O3125.6 (11)
O3i—Cu1—N1172.4 (3)O4—C2—C1117.8 (9)
O2—Cu1—N2173.6 (3)O3—C2—C1116.6 (8)
O3i—Cu1—N294.9 (3)N1—C3—C4122.3 (9)
N1—Cu1—N280.4 (3)C3—C4—C5120.6 (10)
O2—Cu1—O477.6 (2)C4—C5—C6117.4 (10)
O3i—Cu1—O484.3 (2)C7—C6—C5120.0 (9)
N1—Cu1—O4102.3 (3)C6—C7—N1121.5 (10)
N2—Cu1—O499.7 (2)C6—C7—C8126.3 (10)
O2—Cu1—O1i85.3 (3)N1—C7—C8112.2 (9)
O3i—Cu1—O1i76.5 (2)N2—C8—C9119.2 (9)
N1—Cu1—O1i98.2 (3)N2—C8—C7117.1 (9)
N2—Cu1—O1i99.1 (3)C9—C8—C7123.7 (9)
O4—Cu1—O1i154.15 (17)C10—C9—C8119.4 (8)
C3—N1—C7117.9 (8)C9—C10—C11120.2 (9)
C3—N1—Cu1125.5 (6)C12—C11—C10117.3 (11)
C7—N1—Cu1116.3 (7)N2—C12—C11124.1 (9)
C12—N2—C8119.8 (8)C1—O1—Cu1ii104.4 (6)
C12—N2—Cu1126.6 (6)C1—O2—Cu1117.8 (6)
C8—N2—Cu1113.7 (6)C2—O3—Cu1ii116.6 (7)
O1—C1—O2124.8 (9)C2—O4—Cu1106.9 (7)
O1—C1—C2118.2 (8)
Symmetry codes: (i) x1/2, y+1/2, z; (ii) x+1/2, y+1/2, z.

Experimental details

Crystal data
Chemical formula[Cu(C2O4)(C10H8N2)]
Mr307.74
Crystal system, space groupOrthorhombic, Pna21
Temperature (K)293
a, b, c (Å)8.0762 (11), 9.9366 (13), 14.1558 (19)
V3)1136.0 (3)
Z4
Radiation typeMo Kα
µ (mm1)1.93
Crystal size (mm)0.35 × 0.28 × 0.21
Data collection
DiffractometerSiemens SMART CCD
diffractometer
Absorption correctionEmpirical (using intensity measurements)
(SADABS; Sheldrick, 1996)
Tmin, Tmax0.408, 0.458
No. of measured, independent and
observed [I > 2σ(I)] reflections
3348, 1545, 1084
Rint0.060
(sin θ/λ)max1)0.596
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.051, 0.109, 1.05
No. of reflections1545
No. of parameters172
No. of restraints1
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.41, 0.46
Absolute structureFlack (1983), 100 Friedel pairs treated independently
Absolute structure parameter0.35 (4)

Computer programs: SMART (Siemens, 1994), SMART, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXL97.

Selected geometric parameters (Å, º) top
Cu1—O21.972 (6)Cu1—N22.018 (7)
Cu1—O3i1.973 (6)Cu1—O42.327 (6)
Cu1—N11.991 (7)Cu1—O1i2.369 (7)
O2—Cu1—O3i90.6 (2)N2—Cu1—O499.7 (2)
O2—Cu1—N194.5 (3)O2—Cu1—O1i85.3 (3)
O3i—Cu1—N294.9 (3)O3i—Cu1—O1i76.5 (2)
N1—Cu1—N280.4 (3)N1—Cu1—O1i98.2 (3)
O2—Cu1—O477.6 (2)N2—Cu1—O1i99.1 (3)
O3i—Cu1—O484.3 (2)
Symmetry code: (i) x1/2, y+1/2, z.
 

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