cis-Bis(acetato-[kappa]O)bis­(dimethyl sulfide-[kappa]S)platinum(II)

The title compound, cis-[Pt(CH₃COO)₂(C₂H₆S)₂], crystallizes in the P2₁/c space group with a pseudo-square-planar coordination geometry. The complex forms centrosymmetric dimeric packing units, with C-H...O-Pt inter­actions and a short Pt...Pt distance [3.5868 (2) Å]. The coordination mode of the acetate ligands is monodentate and they are oriented almost perpendicular to the coordination plane. Cambridge Structural Database [Allen (2002). Acta Cryst. B58, 380-388] data show a preferred staggered conformation with respect to the coordination plane for Me₂S in complexes with Pt^II.

S1. Comment

No diacetatoplatinum(II) complex with sulfur donor ligands has previously been reported to the Cambridge Structural Database (CSD; Version 5.28 of November 2006; Allen, 2002). Out of 13 acetatoplatinum(II) complexes found in the CSD, eight contain acetate ligands that bridge two platinum(II) ions (in one case one acetate ligand coordinates to three platinum ions), two are cis- and two trans-complexes, and one complex contains a single acetate ligand. Only one diacetatoplatinum(II) complex with nonbridging acetate ligands and identical nonchelating neutral ligands is reported, trans-[Pt(CH₃COO)₂(PPh₃)₂] (Basato et al., 2003). Acetate and nitrate ions are topologically related, and the structure of cis-[Pt(Me₂S)₂(NO₃)₂] has recently been reported (Hansson & Oskarsson, 2007). We report here the crystal structure of the title compound with emphasis on (i) the coordination mode of the acetate ion compared with the nitrate ion; (ii) the packing of the title compound in relation to other PtX₂L₂ compounds, X being a ligand with charge -1 and L being a neutral ligand; and (iii) the coordination mode of dimethyl sulfide (dms) in relation to other Pt^IIA_4-n(Me₂S)_n (where A is any ligand and n = 1–4) complexes.

cis-[Pt(CH₃COO)₂(Me₂S)₂], (I), has a pseudo-square-planar coordination geometry (Fig. 1). The Pt—O and Pt—S bonds (Table 1) illustrate the different trans influence of the O and S atoms, which was previously observed in cis-[Pt(Me₂S)₂(NO₃)₂] (Hansson & Oskarsson, 2007). The Pt—O distances are elongated by ~0.04 Å compared with those in [Pt(NO₃)₄]^2- (Elding & Oskarsson, 1985) and the Pt—S distances are shortened ~0.06 Å compared with [Pt(Me₂S)₄]²⁺ (Bugarcic et al., 1991)

The two acetate ligands coordinate in a monodentate fashion via one of the O atoms, as shown by the differences in the Pt1—O1/Pt1—O2 and Pt1—O3/Pt1—O4 distances being more than 1 Å and thus fulfilling the criterion of a difference of more than 0.6 Å suggested by Kleywegt et al. (1985) for monodentate nitrate ligands. This is further supported by the differences in the C5—O1/ C5—O2 and C7—O3/C7—O4 distances, which are approximately 0.1 Å (Table 1). Both acetate ligands are oriented almost perpendicular to the coordination plane, as shown by the torsion angles S2—Pt1—O1—C5 [-81.8 (3)°] and S1—Pt1—O3—C7 [79.9 (3)°], and both the noncoordinated O2 and O4 atoms are on the same side of the coordination plane. In the corresponding cis-[PtL₂(NO₃)₂] complexes, seven have nitrate ions on opposite sides, five on the same side and two in the plane (Hansson & Oskarsson, 2007). The most striking difference in behavior between acetate and nitrate in these systems is the greater tendency of the acetate ion to form bridging polynuclear complexes compared with the nitrate ion.

The dms ligands are oriented similarly and coordinate to the platinum in a semi-staggered conformation, with C—S1—Pt1—S2 and C—S2—Pt1—O1 torsion angles of ~79 and ~-27°.

The packing of the title compound features centrosymmetric dimers (Fig. 2) across (1/2, 0, 0) and (1/2, 1/2, 1/2), which are held together by C—H···O—Pt interactions (H2B—O1ⁱ = 2.58 Å and H4B—O3ⁱ = 2.60 Å; all symmetry codes as in Table 2). The Pt1···Pt1ⁱ distance is 3.5868 (2) Å, which probably also represents an attractive interaction, since the stabilizing energy of the dimer is 57 kJ mol^-1 monomer according to density functional theory (DFT) calculations. The centers of gravity of the dimers form an I-centered monoclinic unit cell (easily seen after a suitable unit-cell transformation), i.e. each dimer is surrounded by 14 others. It is interesting to note that such a packing is common for centrosymmetric trans-[PtX₂L₂] compounds (Hansson et al., 2006). The four carbonyl O atoms point towards neighbouring dimers and are directed along the c axis. These atoms take part in C—H···O═C interactions with H2A—O4ⁱⁱ = 2.50 Å, H4C—O2ⁱⁱⁱ = 2.62 Å and H3A—O2ⁱⁱⁱ = 2.65 Å. Voids are formed at (0, 0, 0), (0, 0, 1/2) and (1/2, 0, 1/2). Six-membered rings are formed around the voids with C—H···O interactions.

A CONQUEST (Bruno et al., 2002) search of the CSD for Pt^II compounds with one or more dms molecules coordinated to the metal centre resulted in 44 complexes of the type [Pt^IIA_4-n(Me₂S)_n] (where A is any ligand), containing in total 79 dm s ligands (deposited material). Complexes with bridging dms ligands and compounds without atomic coordinates reported in the database were excluded. The angle between the two Me—S bonds and the coordination plane was estimated using the C—S—Pt—A torsion angle (where A is cis to the Me₂S ligand, and n = 1–4). Three different behaviours are observed. Four Me₂S (5%) ligands have both methyl groups on the same side of the coordination plane, and 15 (19%) are close to eclipsed with one torsion angle in the range 2–12°. However, the staggered conformation with torsion angle 35–55° dominates strongly (69% of the 79 reported Me₂S ligands).

Related literature

For related literature, see: Allen (2002); Alrichs et al. (1989); Basato et al. (2003); Bruno et al. (2002); Bugarcic et al. (1991); Elding & Oskarsson (1985); Hansson & Oskarsson (2007); Hansson et al. (2006); Kleywegt et al. (1985).

S2. Experimental

Pt(Me₂S)₂I₂ (0.317 g, 0.554 mmol) was dissolved in 15 ml of acetone. Ag(CH₃COO) (0.192 g, 1.15 mmol) was added, and the reaction mixture was stirred for 90 min. Solid AgI was then removed by filtration. The pale-yellow acetone solution was left to evaporate slowly, which resulted in a yellow solid. Crystals suitable for X-ray diffraction experiments were obtained from recrystallization in a diethyl ether–ethanol mixture (2:1 in volume). DFT calculations were performed at the s-VWN level with the basis sets def-TZVPP for Pt, TZVPP for S and O, and 6–31G* for C and H atoms, using the software TURBOMOLE 5.5 (Alrichs et al., 1989).

S3. Refinement

H-atoms were positioned geometrically and treated as riding on the adjacent C atom [C—H = 0.96 Å and U_iso(H) = 1.5U_eq(C)].

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SHELXTL (Sheldrick, 1998); program(s) used to refine structure: SHELXTL (Sheldrick, 1998); molecular graphics: DIAMOND (Brandenburg, 2000); software used to prepare material for publication: CRYSTALS (Betteridge et al., 2003) and enCIFer (Allen et al., 2004).

Figures

	Fig. 1. The numbering scheme for the title compound. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. A stereoscopic view of the packing of the title compound. One centrosymmetric dimeric pair of complexes is visible at the center of the cell.

cis-Bis(acetato-κO)bis(dimethyl sulfide-κS)platinum(II)

Crystal data

[Pt(C2H3O2)2(C2H6S)2]	F(000) = 832
Mr = 437.43	Dx = 2.156 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 6622 reflections
a = 8.7306 (5) Å	θ = 2.4–32.5°
b = 10.3274 (5) Å	µ = 10.71 mm^−1
c = 15.5205 (9) Å	T = 295 K
β = 105.623 (3)°	Plate, yellow
V = 1347.69 (13) Å^3	0.28 × 0.12 × 0.05 mm
Z = 4

Data collection

Oxford Diffraction XCALIBUR3 diffractometer	4530 independent reflections
Radiation source: Sealed tube	3389 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.059
ω–scans	θmax = 32.5°, θmin = 2.4°
Absorption correction: numerical (CrysAlis RED; Oxford Diffraction, 2006)	h = −12→12
Tmin = 0.115, Tmax = 0.629	k = −15→10
12845 measured reflections	l = −22→23

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)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.073	H-atom parameters constrained
S = 0.97	w = 1/[σ^2(Fo^2) + (0.0352P)^2] where P = (Fo^2 + 2Fc^2)/3
4530 reflections	(Δ/σ)max = 0.002
136 parameters	Δρmax = 1.71 e Å^−3
0 restraints	Δρmin = −1.15 e Å^−3

Special details

Experimental. The intensity data was collected on an Oxford Diffraction Xcalibur3 diffractometer at 295 K. Exposure time was 20 s and frame width 0.75°. For each crystal, 552 frames were collected with one reference frame every 50t h frame. No decay was observed.

The structure was solved using Patterson and difference Fourier methods, and the structure was refined with full-matrix least-square calculations. All non-H atoms were refined anisotropically.

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
Pt1	0.434083 (16)	0.095433 (13)	0.900324 (9)	0.03304 (5)
S1	0.65690 (11)	0.02181 (10)	0.86853 (6)	0.0391 (2)
S2	0.27365 (13)	−0.05173 (10)	0.81290 (7)	0.0431 (2)
O1	0.2535 (4)	0.1649 (3)	0.94666 (18)	0.0479 (7)
O3	0.5713 (4)	0.2267 (3)	0.98561 (18)	0.0485 (7)
O2	0.1427 (5)	0.2960 (4)	0.8336 (2)	0.0688 (10)
O4	0.5971 (5)	0.3568 (4)	0.8767 (2)	0.0695 (10)
C7	0.6168 (5)	0.3325 (4)	0.9550 (3)	0.0412 (8)
C5	0.1497 (5)	0.2469 (4)	0.9055 (3)	0.0427 (9)
C2	0.6406 (6)	−0.1478 (4)	0.8385 (3)	0.0516 (10)
H2A	0.5595	−0.1589	0.7833	0.077*
H2B	0.6133	−0.1966	0.8849	0.077*
H2C	0.7405	−0.1779	0.8314	0.077*
C1	0.6592 (7)	0.0864 (5)	0.7605 (4)	0.0615 (14)
H1A	0.7410	0.0444	0.7401	0.092*
H1B	0.6798	0.1778	0.7657	0.092*
H1C	0.5579	0.0714	0.7184	0.092*
C4	0.1166 (6)	−0.0896 (5)	0.8629 (4)	0.0623 (14)
H4A	0.0627	−0.0115	0.8711	0.093*
H4B	0.1603	−0.1303	0.9199	0.093*
H4C	0.0425	−0.1475	0.8246	0.093*
C8	0.6983 (7)	0.4268 (5)	1.0266 (4)	0.0656 (15)
H8A	0.7311	0.5015	0.9994	0.098*
H8B	0.7899	0.3863	1.0657	0.098*
H8C	0.6261	0.4527	1.0603	0.098*
C3	0.1627 (7)	0.0336 (5)	0.7156 (3)	0.0614 (13)
H3A	0.0723	−0.0172	0.6851	0.092*
H3B	0.2291	0.0488	0.6764	0.092*
H3C	0.1272	0.1149	0.7332	0.092*
C6	0.0294 (6)	0.2790 (5)	0.9570 (4)	0.0610 (12)
H6A	−0.0526	0.3331	0.9209	0.092*
H6B	0.0816	0.3238	1.0111	0.092*
H6C	−0.0170	0.2005	0.9714	0.092*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pt1	0.03463 (8)	0.03450 (8)	0.03047 (8)	0.00007 (6)	0.00960 (6)	0.00010 (5)
S1	0.0342 (5)	0.0454 (5)	0.0381 (5)	0.0001 (4)	0.0102 (4)	−0.0028 (4)
S2	0.0391 (5)	0.0388 (5)	0.0502 (6)	−0.0039 (4)	0.0101 (4)	−0.0053 (4)
O1	0.0521 (18)	0.0533 (17)	0.0442 (15)	0.0164 (14)	0.0233 (14)	0.0079 (13)
O3	0.0639 (19)	0.0463 (15)	0.0335 (13)	−0.0093 (15)	0.0099 (13)	−0.0051 (12)
O2	0.074 (2)	0.087 (3)	0.0485 (18)	0.033 (2)	0.0219 (17)	0.0194 (17)
O4	0.093 (3)	0.070 (2)	0.0440 (18)	−0.028 (2)	0.0160 (19)	0.0047 (17)
C7	0.038 (2)	0.044 (2)	0.043 (2)	−0.0018 (16)	0.0136 (17)	−0.0095 (17)
C5	0.038 (2)	0.046 (2)	0.043 (2)	0.0012 (17)	0.0095 (17)	−0.0055 (17)
C2	0.049 (3)	0.043 (2)	0.060 (3)	0.007 (2)	0.011 (2)	−0.006 (2)
C1	0.070 (4)	0.069 (3)	0.058 (3)	0.011 (2)	0.039 (3)	0.016 (2)
C4	0.041 (2)	0.083 (4)	0.060 (3)	−0.020 (2)	0.009 (2)	0.008 (2)
C8	0.073 (4)	0.065 (3)	0.059 (3)	−0.018 (3)	0.019 (3)	−0.027 (2)
C3	0.077 (4)	0.065 (3)	0.035 (2)	−0.008 (3)	0.003 (2)	−0.003 (2)
C6	0.050 (3)	0.068 (3)	0.073 (3)	0.014 (2)	0.030 (2)	0.005 (3)

Geometric parameters (Å, º)

Pt1—O1	2.032 (3)	C2—H2C	0.9600
Pt1—O3	2.043 (3)	C1—H1A	0.9600
Pt1—S2	2.2559 (10)	C1—H1B	0.9600
Pt1—S1	2.2633 (10)	C1—H1C	0.9600
S1—C2	1.808 (4)	C4—H4A	0.9600
S1—C1	1.809 (5)	C4—H4B	0.9600
S2—C3	1.791 (5)	C4—H4C	0.9600
S2—C4	1.792 (5)	C8—H8A	0.9600
O1—C5	1.278 (5)	C8—H8B	0.9600
O3—C7	1.296 (5)	C8—H8C	0.9600
O2—C5	1.213 (5)	C3—H3A	0.9600
O4—C7	1.207 (5)	C3—H3B	0.9600
C7—C8	1.504 (6)	C3—H3C	0.9600
C5—C6	1.517 (6)	C6—H6A	0.9600
C2—H2A	0.9600	C6—H6B	0.9600
C2—H2B	0.9600	C6—H6C	0.9600
Pt1···Pt1^i	3.5868 (2)
O1—Pt1—O3	84.94 (13)	H1A—C1—H1B	109.5
O1—Pt1—S2	92.04 (10)	S1—C1—H1C	109.5
O3—Pt1—S2	176.24 (9)	H1A—C1—H1C	109.5
O1—Pt1—S1	171.97 (9)	H1B—C1—H1C	109.5
O3—Pt1—S1	88.61 (9)	S2—C4—H4A	109.5
S2—Pt1—S1	94.21 (4)	S2—C4—H4B	109.5
C2—S1—C1	97.9 (2)	H4A—C4—H4B	109.5
C2—S1—Pt1	111.66 (16)	S2—C4—H4C	109.5
C1—S1—Pt1	107.61 (18)	H4A—C4—H4C	109.5
C3—S2—C4	99.8 (3)	H4B—C4—H4C	109.5
C3—S2—Pt1	106.43 (17)	C7—C8—H8A	109.5
C4—S2—Pt1	108.07 (18)	C7—C8—H8B	109.5
C5—O1—Pt1	124.8 (3)	H8A—C8—H8B	109.5
C7—O3—Pt1	120.4 (3)	C7—C8—H8C	109.5
O4—C7—O3	124.7 (4)	H8A—C8—H8C	109.5
O4—C7—C8	121.3 (4)	H8B—C8—H8C	109.5
O3—C7—C8	114.0 (4)	S2—C3—H3A	109.5
O2—C5—O1	126.1 (4)	S2—C3—H3B	109.5
O2—C5—C6	121.5 (4)	H3A—C3—H3B	109.5
O1—C5—C6	112.4 (4)	S2—C3—H3C	109.5
S1—C2—H2A	109.5	H3A—C3—H3C	109.5
S1—C2—H2B	109.5	H3B—C3—H3C	109.5
H2A—C2—H2B	109.5	C5—C6—H6A	109.5
S1—C2—H2C	109.5	C5—C6—H6B	109.5
H2A—C2—H2C	109.5	H6A—C6—H6B	109.5
H2B—C2—H2C	109.5	C5—C6—H6C	109.5
S1—C1—H1A	109.5	H6A—C6—H6C	109.5
S1—C1—H1B	109.5	H6B—C6—H6C	109.5
O3—Pt1—S1—C2	150.75 (19)	O3—Pt1—O1—C5	100.4 (3)
S2—Pt1—S1—C2	−26.75 (17)	S2—Pt1—O1—C5	−81.8 (3)
O3—Pt1—S1—C1	−102.9 (2)	O1—Pt1—O3—C7	−104.8 (3)
S2—Pt1—S1—C1	79.6 (2)	S1—Pt1—O3—C7	79.9 (3)
O1—Pt1—S2—C3	79.1 (2)	Pt1—O3—C7—O4	−7.4 (6)
S1—Pt1—S2—C3	−105.9 (2)	Pt1—O3—C7—C8	172.3 (3)
O1—Pt1—S2—C4	−27.3 (2)	Pt1—O1—C5—O2	−0.3 (6)
S1—Pt1—S2—C4	147.70 (19)	Pt1—O1—C5—C6	179.6 (3)

Symmetry code: (i) −x+1, −y, −z+2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2B···O1^i	0.96	2.58	3.216 (5)	124
C4—H4B···O3^i	0.96	2.60	3.392 (6)	139
C2—H2A···O4^ii	0.96	2.50	3.425 (6)	163
C4—H4C···O2^iii	0.96	2.62	3.479 (6)	150
C3—H3A···O2^iii	0.96	2.65	3.552 (7)	156
C1—H1B···S2^iv	0.96	3.12	3.996 (6)	153

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