Hexa-[mu]-chloro-[mu]₄-oxo-tetrakis­[(4,5-di­hydro-2-methyl-1,2-thiazole-[kappa]N)copper(II)]

The title compound, [Cu₄Cl₆O(C₄H₇NS)₄], was obtained by the reaction of CuCl₂·2H₂O with 2-methyl-2-thia­zoline in methanol. The complex has twofold crystallographic symmetry and contains a tetrahedron of four Cu^II atoms coordinating a central [mu]₄-O atom, with the six edges of the tetrahedron bridged by Cl atoms. Distance ranges are Cu-O 1.917 (4)-1.920 (4) and Cu-Cl 2.370 (2)-2.445 (2) Å.

S1. Comment

The magnetic properties and the presence to the active sites of biological systems of tetranuclear complexes of paramagnetic transition metal ions, have attracted the attention of inorganic and bioinorganic chemists for many years (Marsh et al., 1983; Halfen & Tolman, 1994). Among the ligands that allow the formation of tetranuclear copper(II) complexes are the thiazole derivatives, whose reaction products with CuCl₂ have been extensively studied (Hodgson, 1984; Marsh et al., 1983, 1988). In contrast, relatively little information is known about the reaction of Cu(II) with thiazoline derivatives, which have an almost similar structure to that of thiazoles. The present study is part of a systematic investigation on the reaction products of CuCl₂ and CuBr₂ with thiazolines.

The molecular structure of the title compound (I), along with the atomic numbering scheme, is shown in Fig. 1, while selected bond lengths and angles are given in Table 1. Selected intramolecular contact distances are given in Table 2. The central unit Cu₄OCl₆ is of the same type as that found in many related complexes (Bertrand, 1967; Belford et al., 1972; Gill & Sterns, 1970; Guy et al., 1988). The four copper(II) atoms are arranged tetrahedrally around a central oxygen atom, being also bridged in pairs by chlorine atoms. Each copper atom is fivefold coordinated by three chlorine atoms, the central oxygen atom and the nitrogen atom from a 2-methyl-2-thiazoline ligand (2 m-2tzn hereafter), in an arrangement close to trigonal bipyramidal (TBP). The percentage trigonal distortion from the square pyramidal (SP) geometry of the atomic arrangements around the two independent copper atoms are τ = 77.5% and τ = 77.7% for Cu1 and Cu2, respectively [τ = 0% for ideal SP and τ = 100% for ideal TBP geometries (Addison et al., 1984)].

The cluster Cu₄OCl₆ has been reported to possess various point group symmetries, as for example 43m (Bertrand,1967), 2 (Belford et al.,1972) or 1 (Gill & Sterns, 1970). In the present case, it possesses the point group symmetry 2, with the twofold axis passing through Cl2, O and Cl3 (see Fig. 1). The observed bond lengths and angles in the cluster are in fair agreement with those observed in related complexes.

The two symmetrically independent 2 m-2tzn rings, being approximately perpendicular to each other [91.7 (3)°], have almost identical geometries, with most of the corresponding bond lengths and angles coinciding within the experimental error. The only significant differences appear between the bond lengths C3—S1 and C7—S2 [1.81 (1) Å and 1.73 (2) Å, respectively], and between the bond angles C2—C3—S1 and C6—C7—S2 [104.1 (6)° and 107.8 (8)°, respectively]. The two 2 m-2tzn rings differ also in the degree of planarity. Thus, while the ring attached to Cu(1) appears slightly puckered, the maximum atomic deviation from the mean plane being 0.18 (1) Å, (atom C2), the ring attached to Cu(2) is perfectly planar within the experimental error. The two bonds C1—N1 and C5—N2 of length 1.26 (1) Å and 1.28 (1) Å, respectively, are substantially shorter than the adjacent ones C2—N1 and C6–N2 of length 1.46 (1) Å and 1.45 (1) Å, respectively, indicating that the primary resonance structures in the two 2 m-2tzn rings have the double bond located between C1 and N1 and between C5 and N2, respectively. The nitrogen atoms N1 and N2 are pyramidally coordinated by C1, C2, Cu1 and C5, C6, Cu2, respectively, the corresponding deviations from their basal planes being 0.108 (8) Å and 0.07 (1) Å.

In the crystal structure of the studied compound no unusual intermolecular contact distances are observed, so that the molecular packing may be attributed to normal van der Waals interactions.

S2. Experimental

The title compound was synthesized by mixing a solution of copper(II) chloride dihydrate (1 mmol) in methanol (10 ml) with a solution of the ligand 2-methyl-2-thiazoline (4 mmol) in methanol (5 ml), the reaction being at 291 K. The light brown solution, was left overnight at 291 K, forming brown rhombic crystals.

S3. Refinement

For one atom, C(7), the ratio of maximum/minimum principal r.m.s. atomic displacements was found fairly large (5.54), indicating possible disorder. An attempt, however, to refine C7 as a split atom proved unsuccessful. Hence, its anisotropic displacement parameters were retained, since the refinement converged smoothly, leading to chemically reasonable positions for all atoms. The H atoms were placed geometrically at their ideal positions and allowed to ride with isotropic displacement parameters equal to 1.2 U_eq of the parent atoms. An extinction correction was deemed as not necessary. Some geometrical calculations were performed with the Xtal 3.2 package (Hall et al., 1992).

Computing details

Data collection: DIF4 (Stoe & Cie, 1988); cell refinement: DIF4; data reduction: REDU4 (Stoe & Cie, 1988); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Bergerhoff, 1996); software used to prepare material for publication: SHELXL97.

Figures

Fig. 1. DIAMOND (Bergerhoff, 1996) plot of the molecule of Cu4OCl6(C4H7NS)4 with the atomic numbering scheme. Atomic thermal ellipsoids are at 30% probability level. Symmetry operation: (i) -x, y, -z + 1/2.

µ₄-oxo-hexa-µ-chloro-tetrakis[(2-methyl-2-thiazoline)copper(II)]

Crystal data

C16H28Cl6Cu4N4OS4	F(000) = 1768
Mr = 887.52	Dx = 1.872 Mg m^−3 Dm = 1.87 Mg m^−3 Dm measured by flotation in a mixture of CCl4/CH3I
Orthorhombic, Pbcn	Mo Kα radiation, λ = 0.71070 Å
Hall symbol: -P 2n 2ab	Cell parameters from 15 reflections
a = 10.3705 (18) Å	θ = 8.2–11.5°
b = 14.903 (2) Å	µ = 3.46 mm^−1
c = 20.375 (4) Å	T = 293 K
V = 3148.9 (9) Å^3	Plate, brown
Z = 4	0.23 × 0.13 × 0.04 mm

Data collection

Upgraded Philips PW1100 diffractometer	1273 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.101
Graphite monochromator	θmax = 25.0°, θmin = 2.4°
θ/2θ scans	h = −12→12
Absorption correction: ψ-scan EMPIR (Stoe & Cie, 1988)	k = −17→17
Tmin = 0.448, Tmax = 0.652	l = 0→24
5588 measured reflections	3 standard reflections every 120 min
2775 independent reflections	intensity decay: 10%

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)] = 0.064	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.127	H-atom parameters constrained
S = 0.90	w = 1/[σ^2(Fo^2) + (0.054P)^2] where P = (Fo^2 + 2Fc^2)/3
2775 reflections	(Δ/σ)max = 0.020
162 parameters	Δρmax = 0.71 e Å^−3
0 restraints	Δρmin = −0.60 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
C1	0.2640 (8)	0.3495 (6)	0.4212 (4)	0.035 (2)
C2	0.2378 (9)	0.4632 (6)	0.3483 (5)	0.050 (3)
H2A	0.1611	0.4964	0.3360	0.060*
H2B	0.2925	0.4581	0.3099	0.060*
C3	0.3096 (9)	0.5138 (6)	0.4023 (4)	0.054 (3)
H3A	0.2516	0.5528	0.4264	0.064*
H3B	0.3789	0.5497	0.3840	0.064*
C4	0.2571 (9)	0.2591 (7)	0.4518 (5)	0.054 (3)
H4A	0.1689	0.2447	0.4614	0.081*
H4B	0.3062	0.2589	0.4918	0.081*
H4C	0.2918	0.2153	0.4221	0.081*
C5	0.3496 (10)	0.1194 (9)	0.1237 (5)	0.063 (3)
C6	0.2292 (11)	−0.0072 (7)	0.1350 (5)	0.078 (4)
H6A	0.1447	−0.0136	0.1152	0.094*
H6B	0.2317	−0.0440	0.1742	0.094*
C7	0.3324 (15)	−0.0392 (9)	0.0868 (6)	0.122 (6)
H7A	0.2925	−0.0591	0.0463	0.147*
H7B	0.3802	−0.0889	0.1055	0.147*
C8	0.3933 (9)	0.2119 (10)	0.1308 (6)	0.099 (5)
H8A	0.3199	0.2510	0.1340	0.149*
H8B	0.4439	0.2285	0.0932	0.149*
H8C	0.4448	0.2173	0.1697	0.149*
Cl1	0.2729 (2)	0.20436 (17)	0.28580 (12)	0.0534 (7)
Cl2	0.0000	0.4174 (2)	0.2500	0.0549 (10)
Cl3	0.0000	0.0296 (2)	0.2500	0.0483 (9)
Cl4	0.0481 (2)	0.22807 (16)	0.10777 (11)	0.0457 (6)
N1	0.2014 (6)	0.3738 (4)	0.3710 (3)	0.0338 (18)
N2	0.2508 (8)	0.0859 (6)	0.1524 (3)	0.051 (2)
O1	0.0000	0.2263 (5)	0.2500	0.0222 (17)
S1	0.3727 (2)	0.42602 (17)	0.45479 (13)	0.0548 (7)
S2	0.4347 (4)	0.0500 (3)	0.07156 (19)	0.1196 (16)
Cu1	0.09508 (9)	0.29778 (6)	0.31167 (5)	0.0324 (3)
Cu2	0.12283 (9)	0.15368 (7)	0.20396 (5)	0.0371 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.031 (5)	0.042 (5)	0.032 (5)	−0.008 (5)	0.007 (5)	−0.009 (5)
C2	0.049 (6)	0.045 (6)	0.057 (7)	−0.008 (5)	0.004 (6)	−0.003 (5)
C3	0.066 (7)	0.052 (7)	0.044 (7)	−0.013 (6)	0.005 (6)	−0.015 (5)
C4	0.043 (6)	0.062 (7)	0.056 (7)	0.005 (5)	−0.021 (6)	0.001 (5)
C5	0.029 (6)	0.114 (10)	0.046 (7)	0.029 (6)	−0.005 (6)	−0.010 (7)
C6	0.106 (10)	0.067 (8)	0.062 (8)	0.048 (7)	−0.016 (8)	−0.015 (6)
C7	0.190 (16)	0.116 (11)	0.062 (9)	0.133 (12)	−0.014 (10)	−0.031 (9)
C8	0.026 (6)	0.190 (16)	0.082 (10)	−0.022 (8)	0.015 (6)	−0.017 (10)
Cl1	0.0275 (12)	0.0781 (18)	0.0546 (16)	0.0097 (13)	−0.0077 (11)	−0.0240 (14)
Cl2	0.078 (3)	0.0347 (19)	0.052 (2)	0.000	−0.025 (2)	0.000
Cl3	0.045 (2)	0.0370 (19)	0.063 (2)	0.000	−0.0043 (19)	0.000
Cl4	0.0431 (14)	0.0592 (15)	0.0348 (14)	0.0112 (12)	0.0090 (12)	0.0010 (12)
N1	0.039 (5)	0.033 (4)	0.029 (5)	−0.006 (4)	0.001 (4)	−0.005 (3)
N2	0.043 (5)	0.076 (7)	0.034 (5)	0.030 (5)	−0.004 (5)	−0.013 (4)
O1	0.018 (4)	0.037 (4)	0.011 (4)	0.000	0.009 (3)	0.000
S1	0.0498 (18)	0.0566 (16)	0.0579 (17)	−0.0109 (13)	−0.0131 (15)	−0.0107 (13)
S2	0.091 (3)	0.196 (4)	0.071 (3)	0.082 (3)	0.019 (2)	−0.019 (3)
Cu1	0.0304 (6)	0.0361 (6)	0.0308 (6)	−0.0037 (5)	−0.0005 (5)	−0.0018 (5)
Cu2	0.0306 (6)	0.0451 (6)	0.0355 (6)	0.0074 (5)	0.0023 (5)	−0.0064 (5)

Geometric parameters (Å, º)

C1—N1	1.264 (10)	C7—H7A	0.9700
C1—C4	1.487 (11)	C7—H7B	0.9700
C1—S1	1.743 (8)	C8—H8A	0.9600
C2—N1	1.460 (10)	C8—H8B	0.9600
C2—C3	1.527 (11)	C8—H8C	0.9600
C2—H2A	0.9700	Cl1—Cu1	2.370 (2)
C2—H2B	0.9700	Cl1—Cu2	2.402 (2)
C3—S1	1.812 (10)	Cl2—Cu1^i	2.393 (2)
C3—H3A	0.9700	Cl2—Cu1	2.393 (2)
C3—H3B	0.9700	Cl3—Cu2^i	2.434 (3)
C4—H4A	0.9600	Cl3—Cu2	2.434 (3)
C4—H4B	0.9600	Cl4—Cu2	2.381 (3)
C4—H4C	0.9600	Cl4—Cu1^i	2.445 (2)
C5—N2	1.282 (12)	N1—Cu1	1.991 (7)
C5—C8	1.458 (16)	N2—Cu2	1.972 (7)
C5—S2	1.726 (11)	O1—Cu2^i	1.917 (4)
C6—N2	1.448 (12)	O1—Cu2	1.917 (4)
C6—C7	1.528 (14)	O1—Cu1	1.920 (4)
C6—H6A	0.9700	O1—Cu1^i	1.920 (4)
C6—H6B	0.9700	Cu1—Cl4^i	2.445 (2)
C7—S2	1.728 (16)
Cu1···Cu2	3.083 (1)	Cu1···Cu2^i	3.133 (1)
Cu1···Cu1^i	3.195 (1)	Cu2···Cu2^i	3.164 (1)
N1—C1—C4	125.0 (8)	H8A—C8—H8C	109.5
N1—C1—S1	117.6 (7)	H8B—C8—H8C	109.5
C4—C1—S1	117.3 (6)	Cu1—Cl1—Cu2	80.51 (8)
N1—C2—C3	110.4 (8)	Cu1^i—Cl2—Cu1	83.73 (11)
N1—C2—H2A	109.6	Cu2^i—Cl3—Cu2	81.08 (10)
C3—C2—H2A	109.6	Cu2—Cl4—Cu1^i	80.96 (8)
N1—C2—H2B	109.6	C1—N1—C2	112.6 (7)
C3—C2—H2B	109.6	C1—N1—Cu1	127.8 (6)
H2A—C2—H2B	108.1	C2—N1—Cu1	118.0 (5)
C2—C3—S1	104.1 (6)	C5—N2—C6	112.7 (9)
C2—C3—H3A	110.9	C5—N2—Cu2	125.5 (8)
S1—C3—H3A	110.9	C6—N2—Cu2	121.2 (7)
C2—C3—H3B	110.9	Cu2^i—O1—Cu2	111.2 (3)
S1—C3—H3B	110.9	Cu2^i—O1—Cu1	109.53 (4)
H3A—C3—H3B	108.9	Cu2—O1—Cu1	106.99 (4)
C1—C4—H4A	109.5	Cu2^i—O1—Cu1^i	106.99 (4)
C1—C4—H4B	109.5	Cu2—O1—Cu1^i	109.53 (4)
H4A—C4—H4B	109.5	Cu1—O1—Cu1^i	112.6 (3)
C1—C4—H4C	109.5	C1—S1—C3	90.4 (4)
H4A—C4—H4C	109.5	C5—S2—C7	92.1 (6)
H4B—C4—H4C	109.5	O1—Cu1—N1	176.4 (2)
N2—C5—C8	124.9 (10)	O1—Cu1—Cl1	85.88 (13)
N2—C5—S2	117.1 (10)	N1—Cu1—Cl1	92.2 (2)
C8—C5—S2	118.0 (9)	O1—Cu1—Cl2	81.83 (18)
N2—C6—C7	110.4 (10)	N1—Cu1—Cl2	97.1 (2)
N2—C6—H6A	109.6	Cl1—Cu1—Cl2	129.89 (8)
C7—C6—H6A	109.6	O1—Cu1—Cl4^i	83.78 (10)
N2—C6—H6B	109.6	N1—Cu1—Cl4^i	99.8 (2)
C7—C6—H6B	109.6	Cl1—Cu1—Cl4^i	111.86 (10)
H6A—C6—H6B	108.1	Cl2—Cu1—Cl4^i	114.74 (7)
C6—C7—S2	107.8 (8)	O1—Cu2—N2	176.1 (3)
C6—C7—H7A	110.2	O1—Cu2—Cl4	85.62 (11)
S2—C7—H7A	110.2	N2—Cu2—Cl4	91.1 (2)
C6—C7—H7B	110.2	O1—Cu2—Cl1	85.02 (8)
S2—C7—H7B	110.2	N2—Cu2—Cl1	95.5 (2)
H7A—C7—H7B	108.5	Cl4—Cu2—Cl1	129.46 (10)
C5—C8—H8A	109.5	O1—Cu2—Cl3	83.85 (18)
C5—C8—H8B	109.5	N2—Cu2—Cl3	99.7 (3)
H8A—C8—H8B	109.5	Cl4—Cu2—Cl3	120.05 (7)
C5—C8—H8C	109.5	Cl1—Cu2—Cl3	108.08 (7)

Symmetry code: (i) −x, y, −z+1/2.