Tetra­kis(μ-chloro­acetato-κ²O:O′)bis­[(N,N-dimethyl­formamide-κO)copper(II)]

In the title dimeric complex, [Cu₂(C₂H₂ClO₂)₄(C₃H₇NO)₂], the Cu^II atom has a five-coordinate square-pyramidal environment, with the carbonyl O atom of the dimethyl­formamide ligand at the apical position. The complex mol­ecule is located on a crystallographic inversion centre, with a Cu...Cu separation of 2.6614 (4) Å. Intermolecular C—H...O hydrogen bonds are present in the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.023
• wR factor = 0.067
• Data-to-parameter ratio = 17.7

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       2.65 Ratio
PLAT230_ALERT_2_C Hirshfeld Test Diff for    O5     -   C5      ..       5.91 su
PLAT230_ALERT_2_C Hirshfeld Test Diff for    N1     -   C6      ..       5.03 su
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         N1

Alert level G
PLAT794_ALERT_5_G Check Predicted Bond Valency for Cu1         (2)       2.06

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

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   4 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
   1 ALERT type 5 Informative message, check

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S1. Comment

The structure determination of the title compound, (I), was undertaken as a continuation of earlier studies of copper(II) complexes with monochloroacetic acid (Sieroń, 2007).

The title compound (I) contains a dimeric copper(II) complex, [Cu₂(CH₂ClCOO)₄(DMF)₂], composed of two Cu^II centres, four chloroacetate and two DMF ligands (Fig. 1).

The Cu^II atom has a regular five-coordinate square-pyramidal environment, with the basal plane defined by the O atoms of four bridging bidentate carboxylate groups of monochloroacetate ligands. The Cu^II atom deviates out of the mean plane formed by the four basal O atoms towards the apical O5 atom of the DMF ligand by 0.2104 (7) Å. The O–C distances in the chloroacetate groups are approximately equal and range from 1.247 (2) to 1.262 (2) Å, indicating the distinct delocalization of their π electrons (Borthwick, 1980). The planes of the two independent bridging chloroacetate groups are perpendicular within experimental error. The apical DMF ligand is twisted by a dihedral angle of 33.8 (1)° with respect to the C1/O1/O3ⁱ mean plane. Selected bond distances and bond angles are listed in Table 1. Complex molecules are linked by two Csp³–H···O hydrogen bonds (Table 2), forming eight-membered rings described by the R₂²(8) graph-set motif (Etter et al., 1990) as shown in Fig. 2. The Cu···Cu distance of 2.6614 (4) Å is comparable to those found in other dimeric copper(II) monochloroacetates (Shi et al., 1999, 2001; Calderazzo et al., 2003).

Related literature

For related literature, see: Borthwick (1980); Calderazzo et al. (2003); Etter et al. (1990); Shi et al. (1999, 2001), Sieroń (2007).

S2. Experimental

A mixture of chloroacetic acid (1 mmol) and CuCO₃.Cu(OH)₂.H₂O (0.5 mmol) in a mixture of water (50 ml) and DMF (25 ml) was heated to boiling. The solution was filtered and allowed to cool to room temperature. Turquoise prismatic crystals of (I) were obtained after a few days.

S3. Refinement

All H atoms were initially located in a difference Fourier synthesis, but were positioned with idealized geometry, with C–H = 0.93, 0.96 and 0.97 Å, and refined using a riding model. The methyl H atoms were allowed to rotate to best fit the experimental electron density (AFIX 137). The isotropic displacement parameters of all H atoms were refined freely.

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXTL (Sheldrick, 2001); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL and Mercury (Macrae et al., 2006); software used to prepare material for publication: PLATON (Spek, 2003).

Figures

	Fig. 1. A view of (I), showing the atom-numbering scheme. Displacement ellipsoids for non-H atoms are drawn at the 40% probability level. Unlabelled atoms are related to labelled atoms by the symmetry code (-x, -y + 1, -z).
	Fig. 2. The packing of (I), showing a hydrogen-bonded chain (dashed lines) running along the a axis.

Tetrakis(µ-chloroacetato-κ²O:O')bis[(N,N-δimethylformamide-κO)copper(II)]

Crystal data

[Cu2(C2H2ClO2)4(C3H7NO)2]	Z = 1
Mr = 647.24	F(000) = 326
Triclinic, P1	Dx = 1.745 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.9969 (6) Å	Cell parameters from 3751 reflections
b = 8.0326 (5) Å	θ = 2.6–31.2°
c = 10.2420 (7) Å	µ = 2.21 mm^−1
α = 87.824 (5)°	T = 294 K
β = 71.974 (6)°	Prism, blue-green
γ = 80.015 (6)°	0.45 × 0.25 × 0.20 mm
V = 616.05 (8) Å^3

Data collection

Kuma KM-4 CCD diffractometer	2814 independent reflections
Radiation source: CX-Mo12x0.4-S Seifert Mo tube	2660 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.009
Detector resolution: 8.2356 pixels mm^-1	θmax = 27.5°, θmin = 2.6°
ω scans	h = −10→10
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006)	k = −10→8
Tmin = 0.511, Tmax = 0.639	l = −11→13
6079 measured reflections

Refinement

Refinement on F^2	Hydrogen site location: difference Fourier map
Least-squares matrix: full	Only H-atom displacement parameters refined
R[F^2 > 2σ(F^2)] = 0.023	w = 1/[σ^2(Fo^2) + (0.0379P)^2 + 0.2335P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.067	(Δ/σ)max = 0.001
S = 1.07	Δρmax = 0.60 e Å^−3
2814 reflections	Δρmin = −0.35 e Å^−3
159 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0116 (18)
Primary atom site location: structure-invariant direct methods

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F² for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The observed criterion of F² > σ(F²) is used only for calculating -R-factor-obs 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
Cu1	0.10233 (3)	0.56685 (2)	−0.11043 (2)	0.0311 (1)
Cl1	0.09850 (10)	0.09076 (8)	−0.39180 (6)	0.0685 (2)
Cl2	0.41733 (10)	0.10139 (9)	0.20517 (8)	0.0734 (3)
O1	0.0899 (2)	0.35412 (17)	−0.19692 (14)	0.0464 (4)
O2	0.30126 (17)	0.44111 (18)	−0.05042 (14)	0.0444 (4)
O3	−0.08262 (19)	0.24157 (16)	−0.01133 (13)	0.0440 (4)
O4	0.12946 (18)	0.32648 (19)	0.13481 (15)	0.0469 (4)
O5	0.26071 (19)	0.66002 (18)	−0.29703 (13)	0.0454 (4)
N1	0.3366 (2)	0.6631 (2)	−0.52957 (16)	0.0482 (5)
C1	0.0121 (2)	0.2386 (2)	−0.13520 (17)	0.0348 (5)
C2	0.0355 (3)	0.0721 (3)	−0.2111 (2)	0.0499 (6)
C3	0.2762 (2)	0.3470 (2)	0.05293 (18)	0.0348 (5)
C4	0.4480 (3)	0.2523 (3)	0.0732 (2)	0.0496 (6)
C5	0.2393 (3)	0.6247 (3)	−0.4080 (2)	0.0485 (6)
C6	0.3121 (5)	0.6134 (6)	−0.6568 (3)	0.0921 (13)
C7	0.4803 (4)	0.7616 (3)	−0.5441 (3)	0.0669 (8)
H1	0.12560	−0.00930	−0.18720	0.100 (11)*
H2	−0.07580	0.02850	−0.18020	0.080 (9)*
H3	0.52120	0.19530	−0.01230	0.068 (8)*
H4	0.51300	0.33380	0.09390	0.084 (9)*
H5	0.14680	0.56640	−0.40360	0.069 (8)*
H61	0.22190	0.54310	−0.63630	0.18 (2)*
H62	0.42240	0.55170	−0.71460	0.138 (16)*
H63	0.27580	0.71250	−0.70330	0.16 (2)*
H71	0.58380	0.71390	−0.61730	0.099 (11)*
H72	0.50970	0.75850	−0.45990	0.114 (13)*
H73	0.44110	0.87660	−0.56460	0.160 (19)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0345 (1)	0.0302 (1)	0.0256 (1)	−0.0117 (1)	−0.0016 (1)	0.0007 (1)
Cl1	0.0935 (5)	0.0635 (4)	0.0471 (3)	−0.0030 (3)	−0.0226 (3)	−0.0226 (3)
Cl2	0.0839 (4)	0.0667 (4)	0.0857 (5)	−0.0212 (3)	−0.0482 (4)	0.0314 (3)
O1	0.0620 (8)	0.0387 (7)	0.0344 (7)	−0.0211 (6)	−0.0014 (6)	−0.0072 (5)
O2	0.0375 (6)	0.0468 (7)	0.0452 (7)	−0.0104 (5)	−0.0067 (5)	0.0106 (6)
O3	0.0575 (8)	0.0348 (6)	0.0368 (7)	−0.0173 (6)	−0.0046 (6)	−0.0034 (5)
O4	0.0394 (7)	0.0560 (8)	0.0429 (7)	−0.0116 (6)	−0.0090 (6)	0.0136 (6)
O5	0.0524 (8)	0.0470 (7)	0.0303 (6)	−0.0182 (6)	0.0015 (5)	0.0043 (5)
N1	0.0490 (9)	0.0533 (10)	0.0316 (8)	0.0045 (7)	−0.0043 (7)	0.0022 (7)
C1	0.0404 (8)	0.0298 (8)	0.0351 (9)	−0.0075 (6)	−0.0114 (7)	−0.0042 (6)
C2	0.0699 (13)	0.0351 (9)	0.0458 (11)	−0.0136 (9)	−0.0158 (10)	−0.0088 (8)
C3	0.0381 (8)	0.0302 (8)	0.0370 (9)	−0.0099 (6)	−0.0101 (7)	−0.0026 (6)
C4	0.0436 (10)	0.0430 (10)	0.0626 (13)	−0.0090 (8)	−0.0171 (9)	0.0097 (9)
C5	0.0437 (10)	0.0527 (11)	0.0426 (10)	−0.0095 (8)	−0.0036 (8)	0.0021 (9)
C6	0.080 (2)	0.143 (3)	0.0394 (13)	0.012 (2)	−0.0140 (13)	−0.0079 (16)
C7	0.0647 (14)	0.0596 (14)	0.0565 (14)	−0.0130 (11)	0.0101 (12)	0.0130 (11)

Geometric parameters (Å, º)

Cu1—O1	1.9856 (14)	N1—C7	1.473 (4)
Cu1—O2	1.9823 (15)	C1—C2	1.527 (3)
Cu1—O3^i	1.9719 (13)	C3—C4	1.520 (3)
Cu1—O4^i	1.9879 (16)	C2—H1	0.97
Cu1—O5	2.1304 (14)	C2—H2	0.97
Cl1—C2	1.769 (2)	C4—H3	0.97
Cl2—C4	1.769 (2)	C4—H4	0.97
O1—C1	1.249 (2)	C5—H5	0.93
O2—C3	1.262 (2)	C6—H61	0.96
O3—C1	1.259 (2)	C6—H62	0.96
O4—C3	1.247 (2)	C6—H63	0.96
O5—C5	1.250 (2)	C7—H71	0.96
N1—C5	1.306 (3)	C7—H72	0.96
N1—C6	1.456 (4)	C7—H73	0.96
Cu1···Cu1^i	2.6614 (4)
O1—Cu1—O2	88.42 (6)	O5—C5—N1	125.1 (2)
O1—Cu1—O5	93.93 (6)	Cl1—C2—H1	109
O1—Cu1—O3^i	167.75 (6)	Cl1—C2—H2	109
O1—Cu1—O4^i	90.31 (6)	C1—C2—H1	109
O2—Cu1—O5	97.35 (6)	C1—C2—H2	109
O2—Cu1—O3^i	90.21 (6)	H1—C2—H2	108
O2—Cu1—O4^i	167.87 (6)	Cl2—C4—H3	109
O3^i—Cu1—O5	98.32 (5)	Cl2—C4—H4	109
O4^i—Cu1—O5	94.78 (6)	C3—C4—H3	109
O3^i—Cu1—O4^i	88.48 (6)	C3—C4—H4	109
Cu1—O1—C1	125.19 (12)	H3—C4—H4	108
Cu1—O2—C3	122.57 (12)	O5—C5—H5	117
Cu1^i—O3—C1	120.41 (12)	N1—C5—H5	117
Cu1^i—O4—C3	122.77 (13)	N1—C6—H61	109
Cu1—O5—C5	119.27 (15)	N1—C6—H62	109
C5—N1—C6	123.4 (2)	N1—C6—H63	109
C5—N1—C7	120.42 (19)	H61—C6—H62	109
C6—N1—C7	116.1 (2)	H61—C6—H63	109
O1—C1—O3	126.43 (16)	H62—C6—H63	110
O1—C1—C2	119.16 (16)	N1—C7—H71	109
O3—C1—C2	114.37 (15)	N1—C7—H72	109
Cl1—C2—C1	113.61 (15)	N1—C7—H73	109
O2—C3—O4	126.68 (17)	H71—C7—H72	109
O2—C3—C4	113.55 (16)	H71—C7—H73	109
O4—C3—C4	119.78 (16)	H72—C7—H73	109
Cl2—C4—C3	114.60 (15)

Symmetry code: (i) −x, −y+1, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4···O2^ii	0.97	2.48	3.394 (3)	158

Symmetry code: (ii) −x+1, −y+1, −z.