Poly[[mu]₂-chloro-[mu]₂-1,4-oxathiane-[kappa]²S:S-copper(I)]

The title complex, [CuCl(C₄H₈OS)]_n, contains infinite spiral (CuS)_n chains linked by bridging Cl atoms into layers. The Cl atoms do not form polymeric fragments with Cu^I, but combine into isolated centrosymmetric Cu₂Cl₂ units. The compound is non-isomorphous with the Br-containing analogue, which contains Cu₈S₈ rings linked by Br atoms into chains. The O atom of the 1,4-oxathiane mol­ecule does not realize its coordination abilities in the known copper(I)-halide complexes, while in copper(II)-halide complexes, oxathiane is coordinated via the S and O atoms. This falls into a pattern of the preferred inter­actions, viz. weak acid (Cu^I atom) with weak base (S atom) and harder acid (Cu^II atom) with harder base (O atom).

S1. Comment

1,4-Oxathiane (xt) behaves either as a monodentate ligand in mononuclear transition metal complexes (McEwen & Sim, 1967; Barnes et al., 1977; Olmstead et al., 1982) or as a bridging ligand in polymeric complexes (Barnes & Paton, 1982, 1984; Barnes et al., 1983; Boorman et al., 1998; Salivon et al., 2006). In the latter case it may coordinate to metal atoms via both S and O atoms. The copper(I)–halide complexes [CuX(xt)], where X is Cl, (I), or Br, (II), are known to be not isomorphous (Barnes et al., 1983). However, the structure was determined only for the bromine-containing compound (II) (Barnes & Paton, 1982), while no suitable crystals were obtained for the chorine-containing analogue (Barnes et al., 1983). We have succeeded in obtaining complex (I) in the form of good quality single crystals and we report here its crystal structure.

A major factor governing structure formation in complexes (I) and (II) is the competition between the halide (X = Cl and Br) and S atoms for the coordination to Cu^I. Both structures contain polynuclear (CuS)_n fragments. In (I), the infinite spiral-like (—Cu—S—Cu'—S'—)_n chains (Fig. 1) are similar to the Zn–S chains running along [100] in the sphalerite structure; the torsion angles Cu—S—Cu'—S' = [-72.8 (2)°] and S—Cu'—S'—Cu [-67.3 (2)°] in (I) are close to the corresponding angles Zn—S—Zn'—S' and S—Zn'—S'—Zn (both -60°) in sphalerite. The Cl atoms do not form polymeric fragments with Cu^I on their own. Instead, they form isolated centrosymmetric Cu₂Cl₂ fragments (Fig. 2a). Hence, at the S:Cl ratio 1:1, the softer base (the S atom) appears to be more competitive in the formation of polymeric structures with a soft acid (Cu^I atom) than the harder base (the O atom). The Cl atoms are merely bridging the (CuS)_n chains into layers in the (100) plane (Fig. 1). Polymeric (CuCl)_n fragments appear only when the S:Cl ratio is changed in favour of the Cl atoms. For example polymeric (Cu₂Cl₂)_n strips appear in the structure of the [(CuCl)₃(xt)₂] complex (III) (Salivon et al., 2006). These strips are linked via the bridging S atoms into layers in the (010) plane (Fig. 2c). The bromine-containing compound (II) is built in a slightly different manner. The (CuS)_n fragments are represented by isolated eight-membered Cu₄S₄ rings, which are linked via Br atoms into infinite chains running along [001] (Fig. 2b).

A significant difference between the two Cu—S bond lengths in complex (I) [Cu1—S1' = 2.279 (1) Å and Cu1—S1 = 2.414 (1) Å] indicates a pyramidal deformation of the nearly tetrahedral coordination of the Cu^I atom. A similar difference between the two Cu—S distances is observed for one of the three Cu atoms in complex (III); in all other cases this asymmetry is even less noticeable (Olmstead et al., 1982; Barnes & Paton, 1982). The 1,4-oxathiane molecule has a chair conformation in all the known transition metal complexes (Fowler & Griffiths, 1978; Olmstead et al., 1982; Barnes et al., 1983; Buchholz et al., 1996; Boorman et al., 1998).

The O atoms do not realise their coordination abilities in any of the complexes mentioned here. This falls into a pattern of the preferred interaction weak acid (Cu^I atom)–weak base (S atom). On the other hand, the harder base (O atom) may form a hydrogen bond; in (I), a bond with an O···C2 distance of 3.33 (3) Å links the layers into a three-dimensional structure. However, the O atom of the 1,4-oxathiane molecule can also be involved in an interaction with a transition metal. This can be achieved either by an increase of the acid's hardness, as in the Cu^II complexes [(CuCl₂)₃(xt)₂] and [CuCl₂(xt)₂] (Barnes et al., 1983), where oxathiane becomes a bidentate ligand (coordination via the S and O atoms), or by an increase of the metal-to-ligand ratio, as in the Ag^I complex [(AgNO₃)₆(xt)] (Barnes & Paton, 1984), where oxathiane behaves as a tetradentate ligand (µ₂-S and µ₂-O).

Related literature

For related literature, see: Barnes & Paton (1982, 1984); Barnes et al. (1977, 1983); Boorman et al. (1998); Buchholz et al. (1996); Fowler & Griffiths (1978); McEwen & Sim (1967); Olmstead et al. (1982); Salivon et al. (2006).

S2. Experimental

CuCl (1 mmol) was added to a solution of 1,4-oxathiane (1 mmol) in benzene (2 ml) at 5°. The resulting product was mainly composed of light-brown crystals of complex (I). Detailed examination of some batches revealed also some dark-brown plate-like crystals of complex (III) (Salivon et al., 2006).

S3. Refinement

H atoms were treated using a riding model (C—H = 0.97 Å), with isotropic displacement parameters 1.2 times U_eq of the neighbouring non-H atom.

Computing details

Data collection: EXPOSE in IPDS Software (Stoe & Cie, 1999); cell refinement: CELL in IPDS Software; data reduction: TWIN in IPDS Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The title compound, as seen in the bc projection. Cu—Cl bonds are shown as thick solid lines while Cu—S bonds are represented as dashed lines.
	Fig. 2. The polymeric structure of complexes (a) [CuCl(xt)], (I), (b) [CuBr(xt)], (II), and (c) [(CuCl)3(xt)2], (III). Thick and dashed lines are used to highlight the copper–halide fragments.

Poly[µ₂-chloro-µ₂-1,4-oxathiane-κ²S:S-copper(I)]

Crystal data

[CuCl(C4H8OS)]	F(000) = 408
Mr = 203.17	Dx = 1.974 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 1892 reflections
a = 9.5068 (12) Å	θ = 7.3–55.7°
b = 6.5035 (10) Å	µ = 3.79 mm^−1
c = 11.4259 (16) Å	T = 293 K
β = 104.572 (15)°	Prism, light brown
V = 683.71 (17) Å^3	0.17 × 0.09 × 0.07 mm
Z = 4

Data collection

Stoe IPDS diffractometer	1658 independent reflections
Radiation source: fine-focus sealed tube	892 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.061
ϕ oscillation scans	θmax = 28.1°, θmin = 3.6°
Absorption correction: numerical (X-RED; Stoe & Cie, 1999)	h = −12→10
Tmin = 0.739, Tmax = 0.859	k = −8→8
4497 measured reflections	l = −13→15

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)] = 0.034	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.070	H-atom parameters constrained
S = 0.77	w = 1/[σ^2(Fo^2) + (0.0294P)^2] where P = (Fo^2 + 2Fc^2)/3
1600 reflections	(Δ/σ)max = 0.044
43 parameters	Δρmax = 0.53 e Å^−3
0 restraints	Δρmin = −0.37 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	−0.01359 (7)	0.55929 (8)	0.86419 (5)	0.03878 (17)
Cl1	0.15683 (12)	0.65605 (14)	1.04318 (9)	0.0371 (3)
S1	0.11153 (12)	0.29782 (13)	0.77934 (9)	0.0291 (2)
O1	0.4328 (4)	0.1343 (5)	0.8666 (3)	0.0499 (8)
C1	0.1952 (5)	0.1440 (6)	0.9110 (4)	0.0367 (10)
H1A	0.2330	0.2339	0.9794	0.044*
H1B	0.1224	0.0557	0.9310	0.044*
C2	0.3166 (5)	0.0141 (6)	0.8882 (4)	0.0410 (11)
H2A	0.3538	−0.0738	0.9577	0.049*
H2B	0.2786	−0.0737	0.8189	0.049*
C3	0.3919 (5)	0.2477 (7)	0.7570 (5)	0.0478 (11)
H4A	0.3526	0.1541	0.6908	0.057*
H4B	0.4775	0.3121	0.7417	0.057*
C4	0.2809 (5)	0.4105 (6)	0.7604 (4)	0.0440 (11)
H5A	0.2610	0.4889	0.6858	0.053*
H5B	0.3197	0.5041	0.8268	0.053*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0447 (3)	0.0384 (3)	0.0310 (3)	0.0011 (3)	0.0053 (2)	0.0052 (2)
Cl1	0.0455 (7)	0.0340 (4)	0.0292 (5)	−0.0120 (4)	0.0048 (5)	0.0000 (4)
S1	0.0350 (6)	0.0256 (4)	0.0252 (5)	0.0025 (4)	0.0046 (4)	−0.0011 (4)
O1	0.043 (2)	0.0495 (16)	0.0529 (19)	0.0014 (14)	0.0047 (17)	0.0142 (15)
C1	0.046 (3)	0.0343 (18)	0.026 (2)	0.0011 (19)	0.002 (2)	0.0047 (16)
C2	0.042 (3)	0.035 (2)	0.041 (2)	0.0046 (18)	0.001 (2)	0.0091 (17)
C3	0.040 (3)	0.047 (2)	0.058 (3)	−0.008 (2)	0.016 (2)	0.008 (2)
C4	0.053 (3)	0.035 (2)	0.042 (2)	−0.0043 (19)	0.009 (2)	0.0075 (18)

Geometric parameters (Å, º)

Cu1—S1^i	2.2792 (10)	C1—H1A	0.9700
Cu1—Cl1	2.3529 (12)	C1—H1B	0.9700
Cu1—Cl1^ii	2.3793 (12)	C2—H2A	0.9700
Cu1—S1	2.4139 (12)	C2—H2B	0.9700
S1—C1	1.815 (4)	C3—C4	1.502 (6)
S1—C4	1.831 (5)	C3—H4A	0.9700
O1—C3	1.420 (6)	C3—H4B	0.9700
O1—C2	1.425 (5)	C4—H5A	0.9700
C1—C2	1.505 (6)	C4—H5B	0.9700
S1^i—Cu1—Cl1	120.71 (4)	H1A—C1—H1B	108.0
S1^i—Cu1—Cl1^ii	123.01 (5)	O1—C2—C1	112.6 (3)
Cl1—Cu1—Cl1^ii	96.71 (4)	O1—C2—H2A	109.1
S1^i—Cu1—S1	110.11 (3)	C1—C2—H2A	109.1
Cl1—Cu1—S1	103.67 (4)	O1—C2—H2B	109.1
Cl1^ii—Cu1—S1	99.15 (4)	C1—C2—H2B	109.1
Cu1—Cl1—Cu1^ii	83.29 (4)	H2A—C2—H2B	107.8
C1—S1—C4	95.9 (2)	O1—C3—C4	112.5 (4)
C1—S1—Cu1^iii	103.63 (14)	O1—C3—H4A	109.1
C4—S1—Cu1^iii	113.55 (15)	C4—C3—H4A	109.1
C1—S1—Cu1	102.29 (14)	O1—C3—H4B	109.1
C4—S1—Cu1	107.61 (14)	C4—C3—H4B	109.1
Cu1^iii—S1—Cu1	127.96 (5)	H4A—C3—H4B	107.8
C3—O1—C2	112.7 (4)	C3—C4—S1	111.4 (3)
C2—C1—S1	111.2 (3)	C3—C4—H5A	109.3
C2—C1—H1A	109.4	S1—C4—H5A	109.3
S1—C1—H1A	109.4	C3—C4—H5B	109.3
C2—C1—H1B	109.4	S1—C4—H5B	109.3
S1—C1—H1B	109.4	H5A—C4—H5B	108.0
S1^i—Cu1—Cl1—Cu1^ii	135.07 (5)	Cl1^ii—Cu1—S1—Cu1^iii	62.93 (6)
Cl1^ii—Cu1—Cl1—Cu1^ii	0.0	C4—S1—C1—C2	−52.2 (3)
S1—Cu1—Cl1—Cu1^ii	−101.15 (4)	Cu1^iii—S1—C1—C2	63.9 (3)
S1^i—Cu1—S1—C1	174.22 (16)	Cu1—S1—C1—C2	−161.7 (3)
Cl1—Cu1—S1—C1	43.77 (16)	C3—O1—C2—C1	−66.5 (5)
Cl1^ii—Cu1—S1—C1	−55.49 (16)	S1—C1—C2—O1	63.2 (4)
S1^i—Cu1—S1—C4	73.83 (15)	C2—O1—C3—C4	66.1 (5)
Cl1—Cu1—S1—C4	−56.62 (15)	O1—C3—C4—S1	−62.5 (5)
Cl1^ii—Cu1—S1—C4	−155.88 (15)	C1—S1—C4—C3	52.1 (4)
S1^i—Cu1—S1—Cu1^iii	−67.36 (7)	Cu1^iii—S1—C4—C3	−55.6 (4)
Cl1—Cu1—S1—Cu1^iii	162.19 (5)	Cu1—S1—C4—C3	157.0 (3)

Symmetry codes: (i) −x, y+1/2, −z+3/2; (ii) −x, −y+1, −z+2; (iii) −x, y−1/2, −z+3/2.