Di-μ-chloro-bis{chloro­[1,2-di­phenyl-2-(phenyl­amino)­ethano­ximato]copper(II)}

The title compound, [Cu₂Cl₄(C₂₀H₁₈N₂O)₂], is a centrosymmetric dimer bridged through the Cl atoms. The bridging Cu₂Cl₂ unit is planar and each Cu^II ion has two different distances to the bridging Cl atom. The Cu^II ions are coordinated to three Cl and two N atoms in a square-pyramidal disposition. Hydro­gen bonds are formed by –OH and –NH with the Cl atoms.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.027
• wR factor = 0.062
• Data-to-parameter ratio = 15.5

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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      0.597
          Tmax scaled      0.597 Tmin scaled      0.502

---

S1. Comment

The synthesis and characterization of binuclear copper(II) complexes has made an impact on bio-inorganic chemistry (Solomon et al., 1996). Copper(II) compounds with imidazoles have been used as models to mimic biological systems (Kitajima & Moro-Oka, 1994). Copper(II)–carboxylate adducts with imidazole ligands have a variety of pharmacological properties (Tamura & Imai, 1987). Recently, some attention has been paid to the study of Cu^II complexes with –N—C—C—N–, which has a flexible backbone that enables it to act as a bis-chelating ligand (Bernhardt & Shape, 1998; Haidar et al., 1997; Urtiaga et al., 1997; Comba et al., 1995). Our study is focused on the determination of the bio-active properties of Cu^II complexes with –N—C—C═N– ligands. While trying to synthesize CuN₄ compounds with that ligand from the reaction of 1,2-diphenyl-2-(phenylamino)ethanoxime with CuCl₂ in ethanol, we obtained a new compound of the type Cu₂Cl₄N₄, as shown by the crystallographic study, namely di-µ-chloro-bis{chloro[1,2-diphenyl-2-(phenylamino)ethanoximato]copper(II)}, (I).

The determination of the crystal structure from data recorded at 100 K shows that (I) consists of binuclear molecules with Cl acting as the bridging atoms (Fig. 1). This compound is centrosymmetric with only one half independent molecule per asymmetric unit. Each metal centre has a square-pyramidal coordination. The four short bonds are to two N atoms, a terminal Cl atom and a bridging Cl atom. The long apical bond involves the other bridging Cl atom. So, in (I) there are two types of Cl atoms, bridging and non-bridging.

The bridging Cu₂Cl₂ unit is planar. The Cu1—Cl1 and Cu1—Cl1ⁱ [symmetry code: (i) -x, -y, -z] distances are not equal (Table 1); the larger distance corresponding to the Cl in the apex of the square pyramid and the smaller one to the basal Cl.

The copper–copper distance (Table 1) is similar to the value [3.518 (3) Å] found by Menger et al. (1991) in di-µ-chloro-bis[chloro(2,9-didodecyl-1,10-phenanthroline-N,N')copper], and it is close to the mean copper–copper distance (3.525 Å) found in the di-µ-chloro pentacoordinated Cu^II complexes registered in the April 2001 version of the Cambridge Structural Database (Allen & Kennard, 1993).

The OH group is involved in a bifurcated hydrogen bond (Jeffrey et al., 1985) with Cl1ⁱ and Cl2ⁱ, and –NH forms an intermolecular hydrogen bond with Cl2ⁱⁱ [symmetry code: (ii) 1 - x, -y, -z] (Table 2).

S2. Experimental

Compound (I) was obtained by slow addition of 30 ml of an absolute ethanol solution (0.001 M) of 1,2-diphenyl-2-phenylamine-ethanoxime to 30 ml of an absolute ethanol solution (0.001 M) of CuCl₂·2H₂O. The resulting green precipitate was left overnight, filtered and washed several times with water, followed by ethanol and ether. Recrystallization from absolute ethanol after drying in vacuum gave crystals suitable for X-ray structural analysis; m.p. 456–457 K.

S3. Refinement

All H atoms were located in difference Fourier maps and refined freely except the H atom bonded to O1, which was calculated in an ideal position and refined using a riding model via the SHELXL97 HFIX 83 facility.

Computing details

Data collection: SHELXTL (Bruker, 1997) [AUTHOR: was SHELXTL really used for data collection, cell refinement and data reduction ?]; cell refinement: SHELXTL; data reduction: SHELXTL; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. The molecular structure of (I) showing the atomic numbering scheme. Displacement ellipsoids are drawn at the 50% probability level [symmetry code: (i) -x, -y, -z].

Di-µ-chloro-bis{chloro[1,2-diphenyl-2-(phenylamino)ethanoximato]copper(II)}

Crystal data

[Cu2Cl4(C20H18N2O)2]	Dx = 1.561 Mg m^−3
Mr = 873.61	Melting point = 456–457 K
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
a = 9.1739 (3) Å	Cell parameters from 6428 reflections
b = 22.1696 (7) Å	θ = 2.4–28.5°
c = 9.4404 (3) Å	µ = 1.47 mm^−1
β = 104.592 (1)°	T = 100 K
V = 1858.07 (10) Å^3	Rhombohedral, dark-green
Z = 2	0.42 × 0.38 × 0.35 mm
F(000) = 892

Data collection

Bruker SMART CCD 1K area-detector diffractometer	4707 independent reflections
Radiation source: fine-focus sealed tube	4187 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
Detector resolution: 8 pixels mm^-1	θmax = 28.5°, θmin = 1.8°
ω scans	h = −12→12
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	k = −29→29
Tmin = 0.842, Tmax = 1.000	l = −12→12
21701 measured reflections

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)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.063	H atoms treated by a mixture of independent and constrained refinement
S = 1.07	w = 1/[σ^2(Fo^2) + (0.0227P)^2 + 1.7471P] where P = (Fo^2 + 2Fc^2)/3
4707 reflections	(Δ/σ)max = 0.008
303 parameters	Δρmax = 0.45 e Å^−3
0 restraints	Δρmin = −0.40 e Å^−3

Special details

Experimental. The data collection nominally covered full sphere of reciprocal Space, by a combination of 5 sets of ω scans each set at different ϕ and/or 2θ angles and each scan (25 s exposure) covering 0.3° in ω. Crystal to detector distance 4.51 cm.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Cu1	0.17994 (2)	0.033141 (8)	0.04072 (2)	0.01209 (6)
Cl1	−0.05756 (4)	0.018429 (18)	−0.18538 (4)	0.01537 (8)
Cl2	0.31650 (4)	−0.045273 (17)	−0.00170 (5)	0.01608 (8)
O1	−0.02507 (13)	0.12175 (5)	0.13696 (13)	0.0167 (2)
H1	−0.0747	0.0895	0.1260	0.025*
N1	0.31781 (16)	0.09236 (6)	−0.03444 (15)	0.0132 (3)
N2	0.10730 (15)	0.11295 (6)	0.09524 (15)	0.0131 (3)
C1	0.34128 (18)	0.14598 (7)	0.06463 (18)	0.0140 (3)
C2	0.19444 (18)	0.15914 (7)	0.10667 (17)	0.0129 (3)
C3	0.47135 (18)	0.13359 (7)	0.19754 (18)	0.0152 (3)
C4	0.4560 (2)	0.09314 (8)	0.30557 (19)	0.0186 (3)
C5	0.5784 (2)	0.08049 (9)	0.4230 (2)	0.0225 (4)
C6	0.7157 (2)	0.10865 (9)	0.4334 (2)	0.0238 (4)
C7	0.7308 (2)	0.14934 (9)	0.3269 (2)	0.0228 (4)
C8	0.6092 (2)	0.16166 (8)	0.2086 (2)	0.0191 (3)
C9	0.16510 (19)	0.22071 (7)	0.15414 (18)	0.0145 (3)
C10	0.0205 (2)	0.24575 (8)	0.1131 (2)	0.0186 (3)
C11	−0.0031 (2)	0.30448 (8)	0.1526 (2)	0.0212 (4)
C12	0.1153 (2)	0.33832 (8)	0.2355 (2)	0.0209 (4)
C13	0.2584 (2)	0.31401 (8)	0.2761 (2)	0.0226 (4)
C14	0.2844 (2)	0.25564 (8)	0.2352 (2)	0.0196 (4)
C15	0.25378 (18)	0.10360 (7)	−0.18925 (18)	0.0145 (3)
C16	0.16326 (19)	0.15342 (8)	−0.2383 (2)	0.0177 (3)
C17	0.0977 (2)	0.15973 (9)	−0.3881 (2)	0.0211 (4)
C18	0.1210 (2)	0.11698 (9)	−0.4864 (2)	0.0215 (4)
C19	0.2114 (2)	0.06716 (8)	−0.4356 (2)	0.0199 (3)
C20	0.2789 (2)	0.06052 (8)	−0.28719 (19)	0.0172 (3)
H2	0.400 (2)	0.0746 (9)	−0.019 (2)	0.014 (5)*
H3	0.364 (2)	0.1803 (9)	0.011 (2)	0.009 (4)*
H4	0.363 (3)	0.0753 (10)	0.304 (2)	0.021 (5)*
H5	0.566 (3)	0.0540 (11)	0.494 (3)	0.026 (6)*
H6	0.796 (3)	0.1007 (10)	0.510 (3)	0.026 (6)*
H7	0.822 (3)	0.1684 (10)	0.331 (2)	0.023 (6)*
H8	0.619 (2)	0.1876 (10)	0.135 (2)	0.020 (5)*
H9	−0.059 (2)	0.2231 (10)	0.060 (2)	0.019 (5)*
H10	−0.102 (3)	0.3208 (10)	0.122 (2)	0.025 (6)*
H11	0.097 (3)	0.3785 (11)	0.264 (3)	0.030 (6)*
H12	0.336 (3)	0.3373 (10)	0.329 (3)	0.025 (6)*
H13	0.385 (3)	0.2396 (10)	0.261 (2)	0.022 (5)*
H14	0.146 (2)	0.1838 (10)	−0.174 (2)	0.022 (5)*
H15	0.038 (3)	0.1932 (10)	−0.421 (2)	0.025 (6)*
H16	0.075 (2)	0.1208 (10)	−0.589 (2)	0.023 (6)*
H17	0.225 (3)	0.0371 (10)	−0.506 (3)	0.025 (6)*
H18	0.338 (2)	0.0250 (10)	−0.254 (2)	0.022 (5)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.01278 (10)	0.01011 (9)	0.01385 (10)	−0.00086 (7)	0.00420 (7)	−0.00073 (7)
Cl1	0.01524 (18)	0.01635 (18)	0.01429 (18)	−0.00248 (13)	0.00332 (14)	0.00197 (13)
Cl2	0.01434 (18)	0.01154 (17)	0.0226 (2)	0.00126 (13)	0.00510 (15)	0.00041 (14)
O1	0.0127 (6)	0.0170 (6)	0.0228 (6)	−0.0030 (4)	0.0089 (5)	−0.0045 (5)
N1	0.0130 (7)	0.0111 (6)	0.0156 (7)	0.0011 (5)	0.0035 (5)	−0.0012 (5)
N2	0.0114 (6)	0.0156 (6)	0.0129 (6)	0.0003 (5)	0.0043 (5)	−0.0012 (5)
C1	0.0134 (7)	0.0122 (7)	0.0162 (8)	−0.0008 (6)	0.0034 (6)	−0.0016 (6)
C2	0.0119 (7)	0.0135 (7)	0.0126 (7)	0.0009 (5)	0.0017 (6)	−0.0004 (6)
C3	0.0135 (8)	0.0159 (7)	0.0159 (8)	0.0011 (6)	0.0031 (6)	−0.0044 (6)
C4	0.0150 (8)	0.0219 (8)	0.0181 (8)	−0.0012 (6)	0.0026 (7)	−0.0017 (7)
C5	0.0221 (9)	0.0242 (9)	0.0190 (9)	0.0026 (7)	0.0010 (7)	−0.0003 (7)
C6	0.0169 (9)	0.0313 (10)	0.0195 (9)	0.0043 (7)	−0.0021 (7)	−0.0062 (7)
C7	0.0124 (8)	0.0300 (10)	0.0247 (9)	−0.0011 (7)	0.0025 (7)	−0.0085 (7)
C8	0.0152 (8)	0.0224 (9)	0.0203 (9)	−0.0009 (6)	0.0055 (7)	−0.0029 (7)
C9	0.0160 (8)	0.0119 (7)	0.0158 (8)	0.0003 (6)	0.0045 (6)	−0.0011 (6)
C10	0.0145 (8)	0.0179 (8)	0.0221 (9)	0.0001 (6)	0.0020 (7)	−0.0036 (7)
C11	0.0176 (9)	0.0194 (9)	0.0265 (9)	0.0052 (7)	0.0054 (7)	−0.0016 (7)
C12	0.0265 (9)	0.0145 (8)	0.0211 (9)	0.0029 (7)	0.0047 (7)	−0.0045 (6)
C13	0.0217 (9)	0.0181 (8)	0.0233 (9)	−0.0017 (7)	−0.0031 (7)	−0.0050 (7)
C14	0.0149 (8)	0.0168 (8)	0.0248 (9)	0.0009 (6)	0.0005 (7)	−0.0028 (7)
C15	0.0099 (7)	0.0179 (8)	0.0156 (8)	−0.0033 (6)	0.0031 (6)	0.0016 (6)
C16	0.0154 (8)	0.0193 (8)	0.0187 (8)	0.0000 (6)	0.0048 (7)	−0.0006 (6)
C17	0.0145 (8)	0.0268 (9)	0.0206 (9)	0.0036 (7)	0.0017 (7)	0.0041 (7)
C18	0.0158 (8)	0.0330 (10)	0.0141 (8)	−0.0017 (7)	0.0008 (7)	0.0017 (7)
C19	0.0190 (8)	0.0238 (9)	0.0175 (8)	−0.0037 (7)	0.0056 (7)	−0.0020 (7)
C20	0.0172 (8)	0.0175 (8)	0.0174 (8)	−0.0009 (6)	0.0053 (7)	0.0010 (6)

Geometric parameters (Å, º)

Cu1—N2	2.0031 (14)	C7—C8	1.392 (3)
Cu1—N1	2.0686 (14)	C7—H7	0.93 (2)
Cu1—Cl2	2.2371 (4)	C8—H8	0.93 (2)
Cu1—Cl1^i	2.2814 (4)	C9—C10	1.399 (2)
Cu1—Cl1	2.6582 (4)	C9—C14	1.400 (2)
Cu1—Cu1^i	3.5172 (4)	C10—C11	1.386 (2)
Cl1—Cu1^i	2.2814 (4)	C10—H9	0.92 (2)
O1—N2	1.3816 (17)	C11—C12	1.388 (3)
O1—H1	0.8400	C11—H10	0.95 (2)
N1—C15	1.453 (2)	C12—C13	1.380 (3)
N1—C1	1.494 (2)	C12—H11	0.96 (2)
N1—H2	0.83 (2)	C13—C14	1.388 (2)
N2—C2	1.287 (2)	C13—H12	0.92 (2)
C1—C3	1.523 (2)	C14—H13	0.96 (2)
C1—C2	1.525 (2)	C15—C20	1.388 (2)
C1—H3	0.964 (19)	C15—C16	1.389 (2)
C2—C9	1.482 (2)	C16—C17	1.397 (3)
C3—C8	1.390 (2)	C16—H14	0.95 (2)
C3—C4	1.392 (2)	C17—C18	1.380 (3)
C4—C5	1.393 (3)	C17—H15	0.93 (2)
C4—H4	0.94 (2)	C18—C19	1.392 (3)
C5—C6	1.387 (3)	C18—H16	0.96 (2)
C5—H5	0.92 (2)	C19—C20	1.390 (2)
C6—C7	1.383 (3)	C19—H17	0.97 (2)
C6—H6	0.91 (2)	C20—H18	0.97 (2)
N2—Cu1—N1	78.42 (5)	C5—C6—H6	120.4 (15)
N2—Cu1—Cl2	165.92 (4)	C6—C7—C8	120.28 (17)
N1—Cu1—Cl2	90.77 (4)	C6—C7—H7	121.2 (14)
N2—Cu1—Cl1^i	92.47 (4)	C8—C7—H7	118.5 (14)
N1—Cu1—Cl1^i	163.53 (4)	C3—C8—C7	120.16 (18)
Cl2—Cu1—Cl1^i	95.736 (16)	C3—C8—H8	118.8 (13)
N2—Cu1—Cl1	93.23 (4)	C7—C8—H8	121.0 (13)
N1—Cu1—Cl1	104.52 (4)	C10—C9—C14	119.18 (15)
Cl2—Cu1—Cl1	98.258 (15)	C10—C9—C2	120.87 (15)
Cl1^i—Cu1—Cl1	89.528 (15)	C14—C9—C2	119.87 (15)
N2—Cu1—Cu1^i	94.04 (4)	C11—C10—C9	119.96 (16)
N1—Cu1—Cu1^i	144.25 (4)	C11—C10—H9	120.0 (13)
Cl2—Cu1—Cu1^i	99.984 (13)	C9—C10—H9	120.0 (13)
Cu1^i—Cl1—Cu1	90.472 (15)	C10—C11—C12	120.41 (17)
N2—O1—H1	109.5	C10—C11—H10	118.5 (14)
C15—N1—C1	116.82 (13)	C12—C11—H10	121.1 (14)
C15—N1—Cu1	109.07 (10)	C13—C12—C11	119.97 (16)
C1—N1—Cu1	107.11 (10)	C13—C12—H11	120.7 (14)
C15—N1—H2	111.9 (14)	C11—C12—H11	119.3 (14)
C1—N1—H2	106.8 (14)	C12—C13—C14	120.30 (17)
Cu1—N1—H2	104.3 (14)	C12—C13—H12	119.0 (14)
C2—N2—O1	115.84 (13)	C14—C13—H12	120.7 (14)
C2—N2—Cu1	118.98 (11)	C13—C14—C9	120.15 (16)
O1—N2—Cu1	124.84 (10)	C13—C14—H13	119.7 (13)
N1—C1—C3	109.38 (13)	C9—C14—H13	120.1 (13)
N1—C1—C2	108.52 (13)	C20—C15—C16	120.71 (16)
C3—C1—C2	112.34 (13)	C20—C15—N1	117.32 (15)
N1—C1—H3	108.5 (11)	C16—C15—N1	121.85 (15)
C3—C1—H3	110.2 (11)	C15—C16—C17	119.03 (17)
C2—C1—H3	107.8 (11)	C15—C16—H14	122.2 (13)
N2—C2—C9	127.00 (15)	C17—C16—H14	118.8 (13)
N2—C2—C1	113.37 (14)	C18—C17—C16	120.79 (17)
C9—C2—C1	119.63 (14)	C18—C17—H15	119.9 (14)
C8—C3—C4	119.45 (16)	C16—C17—H15	119.3 (14)
C8—C3—C1	119.38 (15)	C17—C18—C19	119.54 (17)
C4—C3—C1	121.14 (15)	C17—C18—H16	121.0 (13)
C3—C4—C5	120.16 (17)	C19—C18—H16	119.5 (13)
C3—C4—H4	121.3 (13)	C20—C19—C18	120.45 (17)
C5—C4—H4	118.5 (13)	C20—C19—H17	121.0 (14)
C6—C5—C4	120.10 (18)	C18—C19—H17	118.5 (13)
C6—C5—H5	120.9 (14)	C15—C20—C19	119.48 (16)
C4—C5—H5	119.0 (14)	C15—C20—H18	121.3 (13)
C7—C6—C5	119.84 (18)	C19—C20—H18	119.2 (13)
C7—C6—H6	119.8 (15)

Symmetry code: (i) −x, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···Cl2^i	0.84	2.44	3.1516 (12)	143
O1—H1···Cl1^i	0.84	2.68	3.2042 (13)	122
N1—H2···Cl2^ii	0.83 (2)	2.64 (2)	3.4473 (15)	164.7 (18)

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