catena-Poly[[cyclo-tetra-[mu]-chloro­tetra­copper(I)]-bis{[mu]-3-[(2-morpholino-4-oxo-4,5-dihydro-1,3-thia­zol-5-yl­idene)methyl­phen­oxy]propene}-2[kappa]N,1'[eta]²;1[eta]²,2'[kappa]N]

Crystals of a new copper(I) [pi] complex of composition [Cu₄Cl₄(C₁₇H₁₈N₂O₃S)₂]_n have been obtained by alternating-current electrochemical synthesis. In the crystal structure, the Cu and Cl atoms form a chair-like Cu₄Cl₄ cyclic fragment. The organic ligand acts as a bridge, being connected via the C=C bond of the all­yl group to a Cu atom from one inorganic cycle and via the N atom of the thia­zole ring to a Cu atom of another copper-chloride fragment. The geometry of the [pi] center indicates that the Cu-(C=C) inter­action is moderately effective.

S1. Comment

Catalytic properties of the copper(I) halides and the possibility of their olefin π-adduct separation were a basis for early studies of the structural chemistry of copper(I) π complexes (Herberhold, 1972). Such interest has led to investigation of metal adducts with aliphatic olefin derivatives, whereas copper(I) π complexes with heterocyclic ligands have been poorly investigated. We have therefore focused our scientific interests on the structural investigation of copper(I) π complexes with the allyl derivatives of heterocyclic compounds.

Our recent studies of these compounds have shown some interesting peculiarities in stereochemistry. Sharply defined differences in three-dimensional structure are seen between small monocyclic aromatic and non-aromatic derivatives [such as morpholine (Goreshnik & Mys'kiv, 2003) or aminopyridine (Goreshnik et al., 2005a)] on the one hand, and bicyclic aromatic compounds [derivatives of benzotriazole (Goreshnik et al., 1999) or benzimidazole (Goreshnik et al., 2000, 2002)] on the other. As a logical extension of this chemistry, we chose to use more voluminous heterocyclic derivatives, including the title compound, (I).

The Cu and Cl atoms in (I) form chair-like Cu₄Cl₄ cycles (Fig. 1). Similar eight-membered rings have been reported in the structures of 2CuCl(dibenzocyclooctatetraene) (Mak et al., 1983), CuCl(allyl alcohol) (Zavalij et al., 1983), 2CuCl(1,5-hexadiene-3-ol) (Oliinik et al., 1987) and 2CuCl(C₃H₅—N═CH—R (R = 2-furyl and phenyl; Filinchuk & Mys'kiv, 1998). The ligand acts as a bridge between two Cu₄Cl₄ cycles, being coordinated to atom Cu1 of one copper–chloride cycle via π interaction with the C4═C5 bond of the allyl group, and to atom Cu2 from another inorganic fragment via the N atom of the thiazole ring. The major part of the ligand molecule is strictly flat; both benzene and thiazole aromatic rings, the non-H atoms of the allyl group, and atom N1 of the morpholine ring lie in a common plane. Each bridge actually consists of a pair of organic moieties oriented in a `head-to-tail' manner (Fig. 2). The aromatic rings within the bridge exhibit a stacking interaction with a parallel mutual orientation and typical ring–ring distances of 3.6 Å. In turn, each Cu₄Cl₄ ring is bonded to four ligands, resulting in two such bridges which connect two neighboring inorganic rings, thus forming infinite zigzag organic–inorganic chains oriented along the [111] direction. These chains are interconnected by weak interactions only.

The Cu^I—(C═C) π interaction in (I) appears to be of moderate effectiveness, as indicated by the slight elongation of the C4═C5 bond to 1.355(8 Å compared with a free C═C double bond of 1.33 Å. In addition, the value of 37.5 (3)° for the C4—Cu—C5 angle, being an important reference of copper(I)–olefin interaction efficiency, is comparable to the value of 38.0 (8)° in C₇H₅N₂S(C₃H₅)CuCl (Goreshnik et al., 2002) with the same 2Cl + C═C Cu^I atom arrangement. The π-coordinated Cu-atom environment in (I) is essentially planar (the sum of the ligand–copper–ligand angles is 359.9°), which is likewise typical for effective π interaction. On the other hand, the combination of a large inorganic fragment and organic ligand hinders achievement of the most suitable mutual orientation of the C═C group and metal center for effective Cu—(C═C) interaction. Consequently, the Cu—m distance in (I) (m is the mid-point of the C4═C5 bond) of 1.977 (7) Å is slightly longer than those found in C₇H₅N₂S(C₃H₅)CuCl [1.95 (2) Å] or C₆H₄N₃(OC₃H₅)₂CuCl [1.936 (6) Å] (Goreshnik et al., 2005b).

The Cu—Cl distances lie in a rather narrow range with the exception of the noticeably elongated Cu2—Cl1 bond (Table 1). Possibly, the presence of a Cl1···H14 contact (Cl···H = 2.864 Å) formally increases the coordination number of atom Cl1 and, consequently, leads to lengthening of the Cu—Cl distance. A tetrahedral coordinating sphere is the most suitable for σ-coordinated Cu^I atoms. However, in the case of (I), atom Cu2 occupies a trigonal environment consisting of the N atom of the thiazole ring and two Cl atoms. The large size of the rigid organic ligand may spatially hinder any additional donor atoms from entering the metal coordination sphere. On the other hand, the neutral status of the ligand limits the number of chloride anions in the formula that can therefore be involved in the metal coordination environment. Both factors result finally in the trigonal-planar arrangement of atom Cu2.

S2. Experimental

The ligand was obtained by refluxing a mixture of 4-allyloxybenzalrhodanine and morpholine in ethanol (2 h), cooling to room temperature and recrystallizing from ethanol (m.p. 486–487 K). Good quality crystals of (I) were obtained using the alternating-current electrochemical technique (Mykhalichko & Mys'kiv, 1998) starting from an ethanol solution containing copper(II) chloride and the ligand. Because of low ligand solubility, the reaction was performed at 323 K. The starting mixture was placed into a small test tube and heated to dissolve the ligand. Copper-wire electrodes in cork were then inserted, and an alternating current of 0.30 V tension (frequency 50 Hz) was applied. After heating at 323 K for 9 h, the reactor was allowed to stand at 20° (under tension) for a few days, when yellowish crystals of the title compound appeared on the copper electrodes. The density, measured by flotation method in chloroform–bromoform mixture, was found to be 1.9 Mg m⁻³.

S3. Refinement

An orientation matrix and unit-cell parameters were obtained by indexing with the CrystalClear software (Rigaku Corporation, 1999). A number of unindexed reflections were left after the indexing procedure. These reflections were subsequently indexed with the Twinsolve software, implemented in the CrystalClear program package. It was found that the twin sub-units mutually tilted on some degrees, i.e. the crystal demonstrates epitaxic twinning with a rather small volume of second twin component. The HKLF5 file was created and reflections with batch numbers 2 and −2 (reflections belonging to the second twin component and overlapped reflections, respectively) were excluded from the refinement (resulting in a decrease in data completeness to 90% at 25° in θ).

Computing details

Data collection: CrystalClear (Rigaku Corporation, 1999); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: enCIFer (Version 1.1; Allen et al., 2004), TEXSAN (Molecular Structure Corporation, 1999) and WinGX (Farrugia, 1999).

Figures

	Fig. 1. The ligand and copper–chloride cycles in (I). [Symmetry codes: (I) x − 1, y + 1, z + 1; (J) −x + 2, −y + 1, −z; (K) x − 1, y + 1, z + 1; (L) −x + 1, −y + 2, −z + 1.]
	Fig. 2. The bridging function of the ligand in (I).

catena-Poly[[cyclo-tetra-µ-chloro-tetracopper(I)]-bis{3-[(2-morpholino-4-oxo- 4,5-dihydro-1,3-thiazol-5-ylidene)methylphenoxy]propene}- 2κN,1η²;1'η²,2'κN]

Crystal data

[Cu4Cl4(C17H18N2O3S)2]	Z = 1
Mr = 1056.8	F(000) = 532
Triclinic, P1	Dx = 1.865 Mg m^−3 Dm = 1.9 Mg m^−3 Dm measured by flotation in chloroform–bromoform mixture
Hall symbol: -P 1	Mo Kα radiation, λ = 0.7107 Å
a = 8.7940 (4) Å	Cell parameters from 55 reflections
b = 9.2890 (4) Å	θ = 1.6–29.1°
c = 12.7670 (13) Å	µ = 2.68 mm^−1
α = 81.47 (2)°	T = 200 K
β = 86.40 (2)°	Prism, yellow
γ = 65.79 (2)°	0.15 × 0.05 × 0.02 mm
V = 940.66 (19) Å^3

Data collection

Mercury CCD (2x2 bin mode) diffractometer	3730 independent reflections
Radiation source: Sealed Tube	2552 reflections with I > 2σ(I)
Graphite Monochromator monochromator	Rint = 0.015
Detector resolution: 14.7059 pixels mm^-1	θmax = 29.1°, θmin = 1.6°
ϕ and ω scans	h = −12→5
Absorption correction: multi-scan (Blessing, 1995)	k = −12→11
Tmin = 0.814, Tmax = 0.95	l = −17→16
4221 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)] = 0.055	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.161	H atoms treated by a mixture of independent and constrained refinement
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0577P)^2] where P = (Fo^2 + 2Fc^2)/3
3719 reflections	(Δ/σ)max < 0.001
262 parameters	Δρmax = 1.45 e Å^−3
0 restraints	Δρmin = −0.79 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
Cu1	0.76456 (8)	0.53178 (7)	−0.15479 (5)	0.0394 (2)
Cu2	0.85833 (9)	0.52242 (7)	0.18104 (6)	0.0457 (2)
Cl1	0.75869 (19)	0.48818 (18)	0.02244 (12)	0.0506 (4)
Cl2	0.90376 (17)	0.68206 (15)	−0.22491 (12)	0.0447 (4)
S1	0.48283 (17)	0.97733 (15)	0.29900 (11)	0.0384 (3)
O1	0.6689 (5)	0.5260 (4)	0.3844 (3)	0.0430 (10)
O2	−0.0988 (5)	1.2534 (4)	0.6817 (3)	0.0419 (9)
O3	0.7883 (5)	1.0877 (4)	−0.0452 (3)	0.0491 (11)
N1	0.7045 (6)	0.9332 (5)	0.1428 (4)	0.0382 (11)
N2	0.7092 (5)	0.7020 (5)	0.2512 (3)	0.0330 (10)
C1	0.0688 (7)	0.9900 (6)	0.6604 (4)	0.0415 (14)
H4	0.0160	0.9584	0.7190	0.042 (16)*
C2	0.0217 (7)	1.1523 (6)	0.6253 (4)	0.0386 (13)
C3	0.2736 (7)	0.9194 (6)	0.5212 (4)	0.0349 (12)
C4	−0.3808 (7)	1.4332 (7)	0.7853 (4)	0.0455 (14)
H1	−0.3315	1.3234	0.8045	0.048 (18)*
H15	−0.4717	1.4955	0.8233	0.07 (2)*
C5	−0.3202 (7)	1.5024 (7)	0.7021 (4)	0.0385 (13)
H17	−0.3728	1.6125	0.6853	0.07 (2)*
C6	−0.1764 (7)	1.4161 (6)	0.6356 (4)	0.0403 (13)
H3	−0.2141	1.4225	0.5646	0.07 (2)*
H7	−0.0967	1.4645	0.6308	0.060 (19)*
C7	0.4046 (6)	0.7931 (6)	0.4690 (4)	0.0349 (12)
H5	0.4280	0.6897	0.5012	0.052 (18)*
C8	0.4958 (7)	0.8046 (6)	0.3816 (4)	0.0343 (12)
C9	0.6484 (6)	0.8618 (6)	0.2234 (4)	0.0346 (12)
C10	0.6397 (8)	1.1089 (6)	0.1211 (5)	0.0423 (14)
H6	0.7120	1.1454	0.1534	0.020 (12)*
H9	0.5293	1.1558	0.1518	0.09 (3)*
C11	0.6315 (7)	1.1610 (7)	0.0036 (5)	0.0472 (15)
H14	0.5503	1.1339	−0.0273	0.048 (17)*
H18	0.5949	1.2758	−0.0099	0.08 (2)*
C12	0.6282 (6)	0.6648 (6)	0.3422 (4)	0.0342 (11)
C13	0.1035 (7)	1.1972 (6)	0.5379 (4)	0.0410 (13)
H2	0.0757	1.3045	0.5143	0.07 (2)*
C14	0.8397 (8)	0.9183 (7)	−0.0306 (5)	0.0482 (15)
H10	0.9451	0.8693	−0.0668	0.07 (2)*
H11	0.7577	0.8928	−0.0620	0.06 (2)*
C15	0.1918 (7)	0.8771 (6)	0.6095 (4)	0.0384 (13)
H8	0.2213	0.7699	0.6343	0.027 (13)*
C16	0.8589 (7)	0.8518 (7)	0.0839 (5)	0.0439 (14)
H12	0.8846	0.7388	0.0914	0.048 (17)*
H16	0.9508	0.8649	0.1132	0.043 (16)*
C17	0.2252 (7)	1.0827 (6)	0.4867 (4)	0.0407 (13)
H13	0.2770	1.1143	0.4276	0.057 (19)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0375 (4)	0.0381 (4)	0.0353 (4)	−0.0074 (3)	−0.0004 (3)	−0.0067 (3)
Cu2	0.0463 (5)	0.0308 (4)	0.0539 (5)	−0.0110 (3)	0.0098 (4)	−0.0049 (3)
Cl1	0.0478 (9)	0.0664 (10)	0.0333 (8)	−0.0180 (7)	−0.0008 (6)	−0.0094 (7)
Cl2	0.0441 (8)	0.0339 (8)	0.0503 (9)	−0.0108 (6)	−0.0051 (7)	−0.0016 (6)
S1	0.0421 (8)	0.0279 (7)	0.0359 (8)	−0.0070 (6)	0.0072 (6)	−0.0009 (6)
O1	0.055 (2)	0.028 (2)	0.041 (2)	−0.0136 (17)	−0.0022 (19)	0.0039 (17)
O2	0.051 (2)	0.039 (2)	0.032 (2)	−0.0181 (18)	0.0092 (17)	−0.0023 (16)
O3	0.051 (2)	0.037 (2)	0.047 (3)	−0.0105 (19)	0.012 (2)	0.0025 (18)
N1	0.037 (2)	0.028 (2)	0.041 (3)	−0.0057 (19)	0.007 (2)	−0.0011 (19)
N2	0.037 (2)	0.024 (2)	0.030 (2)	−0.0061 (18)	−0.0015 (18)	−0.0002 (17)
C1	0.052 (4)	0.037 (3)	0.034 (3)	−0.019 (3)	0.001 (3)	0.002 (3)
C2	0.043 (3)	0.047 (3)	0.032 (3)	−0.024 (3)	0.004 (2)	−0.008 (2)
C3	0.042 (3)	0.039 (3)	0.027 (3)	−0.020 (2)	−0.001 (2)	0.000 (2)
C4	0.046 (3)	0.049 (4)	0.037 (3)	−0.015 (3)	0.004 (3)	−0.006 (3)
C5	0.035 (3)	0.038 (3)	0.034 (3)	−0.008 (2)	−0.002 (2)	−0.001 (2)
C6	0.047 (3)	0.039 (3)	0.031 (3)	−0.015 (3)	0.003 (2)	−0.002 (2)
C7	0.038 (3)	0.035 (3)	0.029 (3)	−0.013 (2)	−0.004 (2)	0.001 (2)
C8	0.040 (3)	0.022 (3)	0.039 (3)	−0.012 (2)	−0.007 (2)	−0.001 (2)
C9	0.036 (3)	0.034 (3)	0.027 (3)	−0.009 (2)	−0.005 (2)	0.000 (2)
C10	0.048 (3)	0.024 (3)	0.047 (4)	−0.009 (2)	0.007 (3)	0.000 (2)
C11	0.039 (3)	0.044 (4)	0.048 (4)	−0.010 (3)	0.004 (3)	0.003 (3)
C12	0.035 (3)	0.038 (3)	0.028 (3)	−0.011 (2)	−0.004 (2)	−0.008 (2)
C13	0.048 (3)	0.033 (3)	0.036 (3)	−0.013 (3)	0.010 (3)	−0.003 (2)
C14	0.051 (4)	0.042 (4)	0.047 (4)	−0.016 (3)	0.013 (3)	−0.010 (3)
C15	0.044 (3)	0.028 (3)	0.043 (3)	−0.016 (2)	−0.002 (3)	0.001 (2)
C16	0.043 (3)	0.039 (3)	0.043 (3)	−0.012 (3)	0.006 (3)	−0.001 (3)
C17	0.045 (3)	0.037 (3)	0.037 (3)	−0.015 (3)	0.005 (3)	−0.003 (2)

Geometric parameters (Å, º)

Cu1—C4^i	2.085 (6)	C4—C5	1.354 (7)
Cu1—C5^i	2.111 (6)	C4—Cu1^iii	2.085 (6)
Cu1—Cl1	2.2399 (19)	C4—H1	0.9300
Cu1—Cl2	2.268 (3)	C4—H15	0.9300
Cu2—N2	1.951 (5)	C5—C6	1.483 (8)
Cu2—Cl2^ii	2.207 (4)	C5—Cu1^iii	2.111 (6)
Cu2—Cl1	2.369 (2)	C5—H17	0.9300
Cl2—Cu2^ii	2.207 (4)	C6—H3	0.9700
S1—C9	1.747 (6)	C6—H7	0.9700
S1—C8	1.750 (5)	C7—C8	1.349 (7)
O1—C12	1.233 (6)	C7—H5	0.9300
O2—C2	1.346 (7)	C8—C12	1.475 (8)
O2—C6	1.428 (6)	C10—C11	1.504 (8)
O3—C11	1.415 (7)	C10—H6	0.9700
O3—C14	1.433 (7)	C10—H9	0.9700
N1—C9	1.320 (7)	C11—H14	0.9700
N1—C16	1.476 (7)	C11—H18	0.9700
N1—C10	1.479 (6)	C13—C17	1.374 (8)
N2—C9	1.354 (6)	C13—H2	0.9300
N2—C12	1.398 (7)	C14—C16	1.492 (8)
C1—C15	1.370 (8)	C14—H10	0.9700
C1—C2	1.398 (7)	C14—H11	0.9700
C1—H4	0.9300	C15—H8	0.9300
C2—C13	1.394 (7)	C16—H12	0.9700
C3—C15	1.393 (7)	C16—H16	0.9700
C3—C17	1.404 (7)	C17—H13	0.9300
C3—C7	1.475 (8)
C4^i—Cu1—C5^i	37.7 (2)	H3—C6—H7	108.3
C4^i—Cu1—Cl1	108.76 (18)	C8—C7—C3	129.9 (5)
C5^i—Cu1—Cl1	146.41 (17)	C8—C7—H5	115.1
C4^i—Cu1—Cl2	135.52 (16)	C3—C7—H5	115.1
C5^i—Cu1—Cl2	97.94 (18)	C7—C8—C12	122.9 (5)
Cl1—Cu1—Cl2	115.52 (11)	C7—C8—S1	127.9 (4)
N2—Cu2—Cl2^ii	134.15 (15)	C12—C8—S1	109.2 (4)
N2—Cu2—Cl1	116.33 (17)	N1—C9—N2	124.2 (5)
Cl2^ii—Cu2—Cl1	109.05 (14)	N1—C9—S1	119.1 (4)
Cu1—Cl1—Cu2	145.23 (9)	N2—C9—S1	116.7 (4)
Cu2^ii—Cl2—Cu1	89.38 (9)	N1—C10—C11	109.9 (5)
C9—S1—C8	89.8 (3)	N1—C10—H6	109.7
C2—O2—C6	117.5 (4)	C11—C10—H6	109.7
C11—O3—C14	109.9 (5)	N1—C10—H9	109.7
C9—N1—C16	123.9 (5)	C11—C10—H9	109.7
C9—N1—C10	121.2 (5)	H6—C10—H9	108.2
C16—N1—C10	113.3 (4)	O3—C11—C10	111.5 (5)
C9—N2—C12	110.2 (5)	O3—C11—H14	109.3
C9—N2—Cu2	133.0 (4)	C10—C11—H14	109.3
C12—N2—Cu2	116.2 (3)	O3—C11—H18	109.3
C15—C1—C2	120.8 (5)	C10—C11—H18	109.3
C15—C1—H4	119.6	H14—C11—H18	108.0
C2—C1—H4	119.6	O1—C12—N2	121.2 (5)
O2—C2—C13	125.2 (5)	O1—C12—C8	124.7 (5)
O2—C2—C1	116.0 (5)	N2—C12—C8	114.1 (5)
C13—C2—C1	118.7 (5)	C17—C13—C2	119.9 (5)
C15—C3—C17	117.2 (5)	C17—C13—H2	120.0
C15—C3—C7	119.3 (5)	C2—C13—H2	120.0
C17—C3—C7	123.5 (5)	O3—C14—C16	111.4 (5)
C5—C4—Cu1^iii	72.2 (4)	O3—C14—H10	109.3
C5—C4—H1	120.0	C16—C14—H10	109.3
Cu1^iii—C4—H1	108.2	O3—C14—H11	109.3
C5—C4—H15	120.0	C16—C14—H11	109.3
Cu1^iii—C4—H15	89.6	H10—C14—H11	108.0
H1—C4—H15	120.0	C1—C15—C3	121.5 (5)
C4—C5—C6	125.0 (5)	C1—C15—H8	119.3
C4—C5—Cu1^iii	70.1 (4)	C3—C15—H8	119.3
C6—C5—Cu1^iii	110.1 (4)	N1—C16—C14	110.7 (5)
C4—C5—H17	117.5	N1—C16—H12	109.5
C6—C5—H17	117.5	C14—C16—H12	109.5
Cu1^iii—C5—H17	89.7	N1—C16—H16	109.5
O2—C6—C5	109.2 (4)	C14—C16—H16	109.5
O2—C6—H3	109.8	H12—C16—H16	108.1
C5—C6—H3	109.8	C13—C17—C3	121.9 (5)
O2—C6—H7	109.8	C13—C17—H13	119.1
C5—C6—H7	109.8	C3—C17—H13	119.1

Symmetry codes: (i) x+1, y−1, z−1; (ii) −x+2, −y+1, −z; (iii) x−1, y+1, z+1.