Bis[1-hydroxypyridine-2(1H)-thion­ato-S,O]copper(II)

The crystal structure of the widely used title fungicidal material, [Cu(C₅H₄NOS)₂], has been determined at 150 (2) K from a microcrystalline fragment using synchrotron radiation. The mol­ecule adopts a trans-square-planar configuration, with the Cu atom sited at a crystallographic centre of inversion.

S1. Comment

Cyclic thiohydroxamic acids such as 1-hydroxy-2(1H)-pyridinethione (pyrithione) find extensive use as fungicides (Paulus, 1993). In particular, complexes of pyrithione with Zn and Cu are highly active broad-spectrum antimicrobial agents. Zinc pyrithione is the active ingredient in most antidandruff shampoos (Arch Chemicals, 2000a). Copper pyrithione is sold extensively (outside the USA) as a marine antifouling product; marine paints containing copper pyrithione are easy to formulate and are extremely stable even when subjected to extreme thermal conditions (Arch Chemicals, 2000b). The crystal structure of zinc pyrithione has been known for almost 25 years (Barnett et al., 1977), and a considerable number of pyrithione complexes have been prepared and their crystal structures determined (Chen et al., 1991; Hu et al., 1991; Xu et al., 1995; Wen et al., 1996). Despite this extensive research, the crystal structure of copper pyrithione has remained elusive. This may undoubtedly be attributed to the fact that copper pyrithione does not readily form large single crystals suitable for diffraction analysis with laboratory instruments. We report here the crystal structure of copper pyrithione, (I), determined from a microcrystalline fragment using the additional brightness of the Synchrotron Radiation Source at Daresbury, England (Cernik et al., 1997). \sch

Compound (I) adopts a trans square-planar arrangement, with Cu1 sited at a centre of inversion in the space group P1 (Fig. 1). The Cu1—S1 and Cu1—O1 bond distances (Table 1) are shorter than those in zinc pyrithione [average 2.308 (3) and 2.115 (6) Å, respectively] Query - 2.092 (7) Å for (I) from CIF data. Molecules of (I) are linked into chains by C—H···O interactions, forming an R₂²(8) hydrogen-bond motif [H5···O1ⁱⁱ 2.41 Å and C5—H5···O1ⁱⁱ 164.4°; symmetry code (ii): -x, -1 - y, -z] (Fig. 2). The same motif exists in the divalent Ni complex of pyrithione (Chen et al., 1991), in which a cis square-planar geometry leads to the formation of discrete dimers rather than extended chains.

Molecules of (I) in adjacent chains are stacked such that S1 in one molecule lies directly above Cu1 in an adjacent molecule, with Cu1···S1ⁱⁱⁱ 3.4447 (13) Å [symmetry code (iii): 1 - x, -y, -z]. The same arrangement exists below Cu1 [Cu1···S1^iv; symmetry code (iv): -1 - x, -y, -z], such that the coordination geometry around it may be considered to be a tetragonally distorted octahedron (Fig. 3), i.e. a Jahn-Teller distorted octahedral geometry about Cu^II (d⁹). Molecules of (I) therefore form extended stacks containing edge-sharing octahedra along the [100] direction. Within these stacks, pyrithione rings of adjacent molecules are coplanar, with interplanar separations of 3.25 Å.

S2. Experimental

1-Hydroxy-2(1H)-pyridinethione (HPT) was obtained as the hydrated sodium salt, Na(PT).xH₂O, from Aldrich. The Cu^II complex was prepared by the combination of aqueous solutions of CuCl₂ and Na(PT) in a 1:2 molar ratio at room temperature. The resulting green precipitate was removed by filtration under gravity and dried in air at room temperature. Attempts to prepare single crystals of (I) suitable for X-ray diffraction using laboratory instruments were unsuccessful, since the material consistently crystallizes as florets of fine needles. Data were therefore collected at Station 9.8, Daresbury SRS, England, from a needle cut from a floret grown by slow evaporation of a solution of (I) in dimethylsulfoxide.

S3. Refinement

The absorption correction was applied by SADABS (Sheldrick, 1997). However, note that the transmission factors are not real, since they include corrections for beam decay and possibly crystal decay (the two cannot be distinguished). The numbers listed in the CIF are those calculated by SHELXL97 (Sheldrick, 1997). H atoms were placed geometrically and allowed to ride during subsequent refinement, with a C—H distance of 0.95 Å and an isotropic displacement parameter fixed at 1.2 times U_eq for the carbon to which they were attached. For subsequent discussion of the structure, the H-atom positions derived from the X-ray results were normalized to standard neutron-derived values (Allen et al., 1987) along the C—H vector.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: LSCELL (Clegg, 1997); data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP in SHELXTL (Siemens, 1996) and CAMERON (Watkin et al., 1996); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. The molecular unit in (I), showing displacement ellipsoids at the 50% probability level and H atoms as small spheres of arbitrary radii [symmetry code (i): -x, -y, -z].
	Fig. 2. The projection onto (100) showing chains of (I) linked via C—H···O interactions.
	Fig. 3. The coordination geometry around Cu1, illustrating the axial Jahn-Teller distortion.

Bis(1-hydroxy-2(1H)-pyridinethiolato-S²,O)copper(II)

Crystal data

[Cu(C5H4NOS)2]	Z = 1
Mr = 315.84	F(000) = 159
Triclinic, P1	Dx = 1.917 Mg m^−3
a = 4.0545 (7) Å	Synchrotron radiation, λ = 0.6884 Å
b = 7.5723 (12) Å	Cell parameters from 1797 reflections
c = 9.0629 (14) Å	θ = 3.2–29.1°
α = 81.096 (4)°	µ = 2.37 mm^−1
β = 86.190 (4)°	T = 150 K
γ = 85.197 (4)°	Needle, green
V = 273.53 (8) Å^3	0.04 × 0.02 × 0.01 mm

Data collection

Bruker SMART CCD diffractometer	1430 independent reflections
Radiation source: Daresbury SRS, Station 9.8	1074 reflections with I > 2σ(I)
Silicon 111 monochromator	Rint = 0.044
Detector resolution: 8.192 pixels mm^-1	θmax = 29.2°, θmin = 2.2°
thin slice ω–scans	h = −5→5
Absorption correction: multi-scan (SADABS; Sheldrick, 1997)	k = −10→10
Tmin = 0.911, Tmax = 0.977	l = −12→12
2505 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)] = 0.061	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.161	H-atom parameters constrained
S = 1.01	w = 1/[σ^2(Fo^2) + (0.1051P)^2] where P = (Fo^2 + 2Fc^2)/3
1430 reflections	(Δ/σ)max = 0.011
79 parameters	Δρmax = 1.29 e Å^−3
0 restraints	Δρmin = −1.04 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	0.0000	0.0000	0.0000	0.0156 (3)
S1	0.3100 (3)	0.08589 (14)	−0.20927 (12)	0.0220 (3)
O1	0.0855 (8)	−0.2449 (4)	−0.0387 (3)	0.0202 (7)
N1	0.3049 (9)	−0.2690 (5)	−0.1544 (4)	0.0162 (7)
C1	0.4313 (11)	−0.1253 (6)	−0.2437 (5)	0.0163 (8)
C2	0.6546 (10)	−0.1627 (6)	−0.3620 (5)	0.0178 (9)
H2	0.7483	−0.0665	−0.4267	0.021*
C3	0.7394 (12)	−0.3346 (7)	−0.3859 (5)	0.0234 (10)
H3	0.8884	−0.3574	−0.4674	0.028*
C4	0.6059 (12)	−0.4779 (6)	−0.2897 (5)	0.0224 (9)
H4	0.6656	−0.5982	−0.3044	0.027*
C5	0.3904 (12)	−0.4416 (6)	−0.1754 (5)	0.0194 (9)
H5	0.2982	−0.5372	−0.1095	0.023*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0202 (4)	0.0153 (4)	0.0118 (4)	−0.0028 (3)	0.0023 (3)	−0.0045 (3)
S1	0.0284 (7)	0.0167 (6)	0.0205 (6)	−0.0027 (5)	0.0067 (5)	−0.0040 (5)
O1	0.0260 (16)	0.0195 (15)	0.0146 (15)	−0.0034 (13)	0.0077 (13)	−0.0045 (12)
N1	0.0149 (16)	0.0232 (19)	0.0124 (17)	−0.0029 (15)	−0.0004 (13)	−0.0082 (14)
C1	0.0154 (18)	0.020 (2)	0.0136 (19)	−0.0007 (16)	−0.0043 (16)	−0.0007 (15)
C2	0.0131 (18)	0.024 (2)	0.015 (2)	−0.0021 (17)	0.0008 (16)	−0.0006 (16)
C3	0.025 (2)	0.026 (2)	0.020 (2)	0.0003 (19)	0.0013 (19)	−0.0074 (18)
C4	0.027 (2)	0.018 (2)	0.021 (2)	−0.0022 (19)	0.0023 (19)	−0.0025 (17)
C5	0.026 (2)	0.0161 (19)	0.016 (2)	−0.0014 (18)	−0.0054 (18)	−0.0025 (15)

Geometric parameters (Å, º)

Cu1—O1^i	1.939 (3)	C1—C2	1.405 (6)
Cu1—O1	1.939 (3)	C2—C3	1.365 (6)
Cu1—S1^i	2.2445 (11)	C2—H2	0.9500
Cu1—S1	2.2445 (11)	C3—C4	1.405 (7)
S1—C1	1.703 (4)	C3—H3	0.9500
O1—N1	1.354 (5)	C4—C5	1.356 (7)
N1—C5	1.362 (6)	C4—H4	0.9500
N1—C1	1.366 (6)	C5—H5	0.9500
O1^i—Cu1—O1	180.0	C2—C1—S1	123.6 (3)
O1^i—Cu1—S1^i	87.96 (9)	C3—C2—C1	121.2 (4)
O1—Cu1—S1^i	92.04 (9)	C3—C2—H2	119.4
O1^i—Cu1—S1	92.04 (9)	C1—C2—H2	119.4
O1—Cu1—S1	87.96 (9)	C2—C3—C4	119.8 (4)
S1^i—Cu1—S1	180.0	C2—C3—H3	120.1
C1—S1—Cu1	95.67 (15)	C4—C3—H3	120.1
N1—O1—Cu1	115.7 (3)	C5—C4—C3	118.9 (4)
O1—N1—C5	116.6 (4)	C5—C4—H4	120.6
O1—N1—C1	120.6 (4)	C3—C4—H4	120.6
C5—N1—C1	122.8 (4)	C4—C5—N1	120.5 (4)
N1—C1—C2	116.7 (4)	C4—C5—H5	119.7
N1—C1—S1	119.6 (3)	N1—C5—H5	119.7
O1^i—Cu1—S1—C1	174.65 (17)	Cu1—S1—C1—N1	4.5 (4)
O1—Cu1—S1—C1	−5.35 (17)	Cu1—S1—C1—C2	−176.5 (4)
S1^i—Cu1—O1—N1	−173.5 (3)	N1—C1—C2—C3	0.0 (7)
S1—Cu1—O1—N1	6.5 (3)	S1—C1—C2—C3	−179.0 (3)
Cu1—O1—N1—C5	174.5 (3)	C1—C2—C3—C4	−0.9 (7)
Cu1—O1—N1—C1	−5.3 (5)	C2—C3—C4—C5	0.9 (7)
O1—N1—C1—C2	−179.3 (4)	C3—C4—C5—N1	0.0 (7)
C5—N1—C1—C2	0.9 (6)	O1—N1—C5—C4	179.3 (4)
O1—N1—C1—S1	−0.3 (6)	C1—N1—C5—C4	−0.9 (7)
C5—N1—C1—S1	179.9 (3)

Symmetry code: (i) −x, −y, −z.