Tetra-μ-acetato-bis­[(pyridine N-oxide)copper(II)](Cu—Cu)

Abstract

The mol­ecule of the title binuclear copper(II) complex, [Cu₂(CH₃COO)₄(C₅H₅NO)₂], occupies a special position on a crystallographic inversion centre; the coordination environment of the Cu^II atom is slightly distorted square-pyramidal and is made up of four O atoms belonging to four acetate groups in the basal plane with the O atom of pyridine N-oxide ligand in the apical position. The Cu—Cu distance is 2.6376 (6) Å.

Related literature

For the biological activity of binuclear copper(II) compounds, see: Li et al. (2007 ▶). For a related structure, see: Zhang (2009 ▶).

Experimental

Crystal data

• [Cu₂(C₂H₃O₂)₄(C₅H₅NO)₂]

• M _r = 553.46

• Monoclinic,

• a = 9.6737 (11) Å

• b = 13.5886 (16) Å

• c = 8.5236 (10) Å

• β = 99.970 (2)°

• V = 1103.5 (2) ų

• Z = 2

• Mo Kα radiation

• μ = 1.98 mm⁻¹

• T = 296 K

• 0.2 × 0.2 × 0.2 mm

Data collection

• Bruker SMART CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Bruker, 1998 ▶) T _min = 0.673, T _max = 0.680

• 5445 measured reflections

• 1936 independent reflections

• 1713 reflections with I > 2σ(I)

• R _int = 0.015

Refinement

• R[F ² > 2σ(F ²)] = 0.025

• wR(F ²) = 0.070

• S = 1.07

• 1936 reflections

• 145 parameters

• H-atom parameters constrained

• Δρ_max = 0.43 e Å⁻³

• Δρ_min = −0.33 e Å⁻³

Data collection: SMART (Bruker, 1998 ▶); cell refinement: SAINT (Bruker, 1998 ▶); 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.

Supplementary Material

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

supplementary crystallographic information

Comment

The crystal structures of binuclear copper(II) complexes have been extensively studied because of their possible anticarcinogen properties (Li et al., 2007), and numerous papers dealing with binuclear copper complexes have been published (Zhang, 2009). Herein, we report the synthesis and crystal structure of a new binuclear copper complex.

The molecule of the title binuclear copper(II) complex, [Cu₂(C₂H₃O₂)₄(C₅H₅ON)₂], occupies a special position in the crystallographic inversion centre; coordination environment of the Cu^II atom represents a slightly distorted tetragonal pyramid and is made up of four oxygen atoms belonging to four acetato-group in the basal plane as well as the oxygen atom of pyridine N-oxide ligand in the apical position. The Cu—O bond distance between Cu^II atom and acetato O atoms vary from 1.9605 (18) Å to 1.9710 (18) Å, while the Cu—O bond distance involving Cu^II atom and the O atom of the pyridine N-oxide ligand is 2.1507 (18) Å. The Cu1—Cu1ⁱ distance is 2.6376 (6) Å [symmetry code (i): 1 - x, -y, -z].

Experimental

A solution containing a 1:2:5 molar ratio of picolinic acid N-oxide (0.0139 g, 0.1 mmol), CuCO₃ (0.0247 g, 0.2 mmol) and acetic acid (1 ml, 0.5 mmol/ml) in a mixture of ethanol(5 ml) and water (10 ml) was sealed in a 25 ml teflon reactor and kept at 453 K for 3 days, then slowly cooled to 373 k and kept at this temperature for 24 h more. After cooling to room temperature, the mixture was filtered and the filtrate was allowed to stand at room temperature. Block crystals suitable for the X-ray investigation were collected.

Refinement

All H atoms were placed geometrically (C-H = 0.93-0.96 Å) and included into refinement in the riding motion approximation with U_iso(H) = 1.2U_eq(C) [1.5U_eq(C) for methyl H atoms].

Figures

Fig. 1.

Molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level; hydrogen atoms are shown as small circles of arbitrary radius. The unlabelled atoms are derived by the symmetry transformation -x + 1, -y, -z.

Crystal data

[Cu2(C2H3O2)4(C5H5NO)2]	F(000) = 564
Mr = 553.46	Dx = 1.666 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3911 reflections
a = 9.6737 (11) Å	θ = 2.6–27.9°
b = 13.5886 (16) Å	µ = 1.98 mm−1
c = 8.5236 (10) Å	T = 296 K
β = 99.970 (2)°	Block, blue
V = 1103.5 (2) Å3	0.2 × 0.2 × 0.2 mm
Z = 2

Data collection

Bruker SMART CCD area-detector diffractometer	1936 independent reflections
Radiation source: fine-focus sealed tube	1713 reflections with I > 2σ(I)
graphite	Rint = 0.015
φ and ω scans	θmax = 25.0°, θmin = 2.1°
Absorption correction: multi-scan (SADABS; Bruker, 1998)	h = −10→11
Tmin = 0.673, Tmax = 0.680	k = −16→9
5445 measured reflections	l = −10→9

Refinement

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)] = 0.025	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.070	H-atom parameters constrained
S = 1.07	w = 1/[σ2(Fo2) + (0.0352P)2 + 0.7718P] where P = (Fo2 + 2Fc2)/3
1936 reflections	(Δ/σ)max = 0.001
145 parameters	Δρmax = 0.43 e Å−3
0 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
O3	0.55087 (19)	−0.15687 (13)	−0.0542 (2)	0.0457 (5)
O4	0.69513 (18)	−0.02840 (14)	0.1692 (2)	0.0411 (4)
Cu1	0.38549 (3)	0.01927 (2)	0.05882 (3)	0.02846 (12)
O5	0.50246 (19)	0.00354 (14)	0.2694 (2)	0.0424 (4)
O2	0.35940 (18)	−0.12383 (13)	0.0480 (2)	0.0408 (4)
N1	0.11758 (19)	0.11134 (15)	0.1808 (2)	0.0330 (4)
C8	0.6302 (3)	−0.01859 (17)	0.2828 (3)	0.0335 (5)
O1	0.18110 (19)	0.03795 (15)	0.1215 (3)	0.0520 (5)
C6	0.4409 (3)	−0.18155 (18)	−0.0051 (3)	0.0349 (5)
C1	0.1856 (3)	0.1945 (2)	0.2326 (3)	0.0409 (6)
H1A	0.2801	0.2014	0.2261	0.049*
C5	−0.0186 (2)	0.1004 (2)	0.1894 (3)	0.0406 (6)
H5A	−0.0653	0.0428	0.1529	0.049*
C9	0.7115 (3)	−0.0358 (2)	0.4475 (3)	0.0506 (7)
H9A	0.8070	−0.0518	0.4408	0.076*
H9B	0.6700	−0.0892	0.4966	0.076*
H9C	0.7096	0.0228	0.5102	0.076*
C2	0.1170 (3)	0.2692 (2)	0.2948 (3)	0.0499 (7)
H2A	0.1650	0.3265	0.3302	0.060*
C4	−0.0892 (3)	0.1741 (2)	0.2519 (4)	0.0509 (7)
H4A	−0.1835	0.1658	0.2581	0.061*
C3	−0.0225 (3)	0.2599 (2)	0.3054 (4)	0.0545 (8)
H3A	−0.0702	0.3102	0.3474	0.065*
C7	0.4047 (3)	−0.2887 (2)	−0.0104 (4)	0.0530 (7)
H7A	0.3190	−0.2983	0.0300	0.080*
H7B	0.4789	−0.3249	0.0539	0.080*
H7C	0.3930	−0.3117	−0.1184	0.080*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
O3	0.0419 (10)	0.0288 (9)	0.0715 (13)	−0.0013 (8)	0.0238 (9)	−0.0027 (9)
O4	0.0337 (9)	0.0532 (12)	0.0363 (9)	0.0075 (8)	0.0062 (7)	0.0057 (8)
Cu1	0.02487 (17)	0.02651 (18)	0.03512 (19)	0.00156 (11)	0.00833 (12)	0.00071 (11)
O5	0.0362 (10)	0.0558 (12)	0.0356 (9)	0.0061 (8)	0.0071 (7)	−0.0015 (8)
O2	0.0409 (10)	0.0286 (9)	0.0557 (11)	−0.0019 (7)	0.0158 (8)	0.0008 (8)
N1	0.0279 (10)	0.0374 (11)	0.0350 (10)	−0.0006 (9)	0.0088 (8)	−0.0034 (9)
C8	0.0374 (13)	0.0264 (12)	0.0364 (13)	−0.0007 (10)	0.0055 (10)	0.0015 (10)
O1	0.0339 (10)	0.0484 (12)	0.0788 (14)	−0.0019 (8)	0.0237 (9)	−0.0203 (10)
C6	0.0356 (13)	0.0277 (12)	0.0402 (13)	−0.0017 (10)	0.0034 (10)	0.0044 (10)
C1	0.0319 (13)	0.0444 (15)	0.0470 (15)	−0.0119 (11)	0.0089 (11)	−0.0035 (12)
C5	0.0275 (12)	0.0444 (15)	0.0512 (15)	−0.0077 (11)	0.0106 (11)	−0.0127 (12)
C9	0.0508 (16)	0.0627 (19)	0.0368 (15)	0.0086 (14)	0.0031 (12)	0.0055 (13)
C2	0.0540 (17)	0.0408 (15)	0.0554 (18)	−0.0122 (13)	0.0108 (13)	−0.0108 (13)
C4	0.0308 (14)	0.0589 (18)	0.0654 (18)	−0.0008 (12)	0.0146 (12)	−0.0178 (15)
C3	0.0526 (17)	0.0506 (18)	0.0626 (19)	0.0068 (14)	0.0162 (14)	−0.0180 (15)
C7	0.0568 (18)	0.0282 (14)	0.077 (2)	−0.0029 (12)	0.0187 (15)	0.0036 (14)

Geometric parameters (Å, °)

O3—C6	1.254 (3)	C1—C2	1.369 (4)
O4—C8	1.250 (3)	C1—H1A	0.9300
Cu1—O5	1.9605 (18)	C5—C4	1.370 (4)
Cu1—O2	1.9610 (18)	C5—H5A	0.9300
Cu1—O4i	1.9685 (17)	C9—H9A	0.9600
Cu1—O3i	1.9710 (18)	C9—H9B	0.9600
Cu1—O1	2.1507 (18)	C9—H9C	0.9600
Cu1—Cu1i	2.6376 (6)	C2—C3	1.373 (4)
O5—C8	1.257 (3)	C2—H2A	0.9300
O2—C6	1.251 (3)	C4—C3	1.372 (4)
N1—O1	1.317 (3)	C4—H4A	0.9300
N1—C5	1.340 (3)	C3—H3A	0.9300
N1—C1	1.344 (3)	C7—H7A	0.9600
C8—C9	1.504 (3)	C7—H7B	0.9600
C6—C7	1.496 (3)	C7—H7C	0.9600
C6—O3—Cu1i	123.11 (16)	O3—C6—C7	117.3 (2)
C8—O4—Cu1i	126.30 (16)	N1—C1—C2	120.5 (2)
O5—Cu1—O2	89.09 (8)	N1—C1—H1A	119.7
O5—Cu1—O4i	167.89 (7)	C2—C1—H1A	119.7
O2—Cu1—O4i	89.45 (8)	N1—C5—C4	120.1 (2)
O5—Cu1—O3i	89.38 (8)	N1—C5—H5A	120.0
O2—Cu1—O3i	167.91 (7)	C4—C5—H5A	120.0
O4i—Cu1—O3i	89.55 (8)	C8—C9—H9A	109.5
O5—Cu1—O1	101.25 (8)	C8—C9—H9B	109.5
O2—Cu1—O1	90.70 (7)	H9A—C9—H9B	109.5
O4i—Cu1—O1	90.79 (8)	C8—C9—H9C	109.5
O3i—Cu1—O1	101.35 (7)	H9A—C9—H9C	109.5
O5—Cu1—Cu1i	86.37 (6)	H9B—C9—H9C	109.5
O2—Cu1—Cu1i	83.97 (5)	C1—C2—C3	120.3 (3)
O4i—Cu1—Cu1i	81.52 (5)	C1—C2—H2A	119.8
O3i—Cu1—Cu1i	83.97 (5)	C3—C2—H2A	119.8
O1—Cu1—Cu1i	170.66 (6)	C5—C4—C3	120.9 (3)
C8—O5—Cu1	120.79 (16)	C5—C4—H4A	119.6
C6—O2—Cu1	123.67 (16)	C3—C4—H4A	119.6
O1—N1—C5	117.7 (2)	C4—C3—C2	117.8 (3)
O1—N1—C1	121.9 (2)	C4—C3—H3A	121.1
C5—N1—C1	120.3 (2)	C2—C3—H3A	121.1
O4—C8—O5	124.9 (2)	C6—C7—H7A	109.5
O4—C8—C9	117.0 (2)	C6—C7—H7B	109.5
O5—C8—C9	118.0 (2)	H7A—C7—H7B	109.5
N1—O1—Cu1	134.01 (15)	C6—C7—H7C	109.5
O2—C6—O3	125.2 (2)	H7A—C7—H7C	109.5
O2—C6—C7	117.5 (2)	H7B—C7—H7C	109.5
O2—Cu1—O5—C8	82.77 (19)	O5—Cu1—O1—N1	76.0 (2)
O4i—Cu1—O5—C8	−0.3 (5)	O2—Cu1—O1—N1	165.2 (2)
O3i—Cu1—O5—C8	−85.24 (19)	O4i—Cu1—O1—N1	−105.3 (2)
O1—Cu1—O5—C8	173.30 (19)	O3i—Cu1—O1—N1	−15.6 (3)
Cu1i—Cu1—O5—C8	−1.25 (18)	Cu1—O2—C6—O3	1.9 (4)
O5—Cu1—O2—C6	−88.0 (2)	Cu1—O2—C6—C7	−178.14 (19)
O4i—Cu1—O2—C6	79.9 (2)	Cu1i—O3—C6—O2	−0.8 (4)
O3i—Cu1—O2—C6	−5.3 (5)	Cu1i—O3—C6—C7	179.25 (19)
O1—Cu1—O2—C6	170.7 (2)	O1—N1—C1—C2	−179.5 (2)
Cu1i—Cu1—O2—C6	−1.59 (19)	C5—N1—C1—C2	0.0 (4)
Cu1i—O4—C8—O5	−3.5 (4)	O1—N1—C5—C4	179.2 (3)
Cu1i—O4—C8—C9	175.76 (18)	C1—N1—C5—C4	−0.3 (4)
Cu1—O5—C8—O4	3.1 (3)	N1—C1—C2—C3	0.1 (4)
Cu1—O5—C8—C9	−176.22 (18)	N1—C5—C4—C3	0.5 (5)
C5—N1—O1—Cu1	172.94 (19)	C5—C4—C3—C2	−0.3 (5)
C1—N1—O1—Cu1	−7.5 (4)	C1—C2—C3—C4	0.0 (5)

Symmetry codes: (i) −x+1, −y, −z.