Low-temperature redetermination of trans-tetra­bromidobis(dimethyl sulfide-κS)platinum(IV)

The octa­hedral molecule of the title compound, [PtBr₄(C₂H₆S)₂], lies on an inversion centre [Pt—Br = 2.4654 (4) and 2.4761 (4) Å; Pt—S = 2.3624 (9) Å]. A similar set of bond distances is predicted by density functional theory.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](S-C) = 0.004 Å
• R factor = 0.019
• wR factor = 0.048
• Data-to-parameter ratio = 29.2

checkCIF/PLATON results

No syntax errors found



Alert level B
PLAT232_ALERT_2_B Hirshfeld Test Diff (M-X)  Pt     -   Br1     ..      11.39 su

Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Pt     -   Br2     ..       9.79 su

Alert level G
FORMU01_ALERT_1_G  There is a discrepancy between the atom counts in the
            _chemical_formula_sum and _chemical_formula_moiety. This is
            usually due to the moiety formula being in the wrong format.
            Atom count from _chemical_formula_sum:   C4 H12 Br4 Pt1 S2
            Atom count from _chemical_formula_moiety:
PLAT794_ALERT_5_G Check Predicted Bond Valency for Pt          (2)       3.08

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   2 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

As part of an ongoing investigation (Muller et al., 2006; Roodt et al., 2003; Otto, 2001; Otto et al., 2000) into determining which factors govern a disordered packing mode in symmetrical square-planar complexes of Rh, Ir, Pd and Pt we set out to synthesize the starting compound trans-[PtBr₂(dms)₂], however we formed trans-[PtBr₄(dms)₂].

The current redetermination of the structure (Skvortsov et al., 1994) is accompanied by a DFT calculation to determine the optimum structure in the gas phase, similar to what we reported previously for square planar Rh complexes (Muller et al., 2006).

The title compound trans-[PtBr₄(dms)₂] (dms = SMe₂), (I), crystallizes in the monoclinic space group P2(1)/n (Z = 2) and lies on an inversion centre (Figure 1). Selected geometrical data are given in Table 2. The Pt—Br distances of the current low temperature study are slightly smaller than the previously reported, room temperature, structure (Skvortsov et al., 1994; data extracted from the Cambridge Structural Database; Version 5.27, update of August 2006), as is to be expected. No short intermolecular contacts were observed. A packing diagram is given in Figure 2.

Geometry optimization of the title compound using Density Functional Theory (DFT) calculations with the observed parameters as a starting structure converged to similar geometry. A good agreement between the calculated and observed geometry (Table 3) was found (r.m.s. deviation of all non-H atoms = 0.1684 Å). The overlay of the calculated and experimental structures is shown in Figure 3.

The geometries of trans-[PtX₄(dms)₂] (X = Cl, Br, I) which are isostructural are given in Table 3. The Pt—S distances are about the same for X = Cl and Br, 2.36 Å. The X—Pt—X angles are close to 90° for all complexes and the X—Pt—S angles are 5–7° off the 'ideal' 90°. Recently (Janse van Rensburg et al., 2007) the iodo complex has been described as being suspended by I···I contacts, and we refer to their discussion of these contacts.

Related literature

For the original room-temperature structure see: Skvortsov et al. (1994). For the isostructural chlorido analog, see: Toffoli et al. (1987) and for the iodido analog, see: Janse van Rensburg et al. (2007). For background literature, see: Muller et al. (2006); Otto (2000); Otto et al. (2001); Roodt et al. (2003).

S2. Experimental

The title compound was formed during an attempted synthesis of trans-[PtBr₂(dms)₂]. [K₂PtCl₄] (1.00 g, 2.41 mmol) was dissolved in water (50 ml). To this 5 equivalents of LiBr (g, mmol) was added. The solution was stirred for 30 min and an excess of dimethyl sulfide (4.5 ml, 60 mmol) was added and left to stir. After 3 h the complex was filtered off, washed with water and left to dry. Recrystallization from CH₂Cl₂ gave red cuboids.

DFT calculations were performed at the B3LYP level with the LANL2DZ basis set for platinum and the 6–311 G(d) basis set for bromine, sulfur, carbon and hydrogen atoms, using the Gaussian03 software package. Minima were verified via frequency analysis of the stationary point.

S3. Refinement

The methyl protons were placed in geometrically idealized positions and constrained to ride on their parent atoms with U_iso(H) = 1.5, with torsion angles refined from the electron density.

The final difference Fourier map had a large peak near Pt1.

Computing details

Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus (Bruker, 2004); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. The structure (I), showing 50% probability displacement ellipsoids. H atoms have been omitted for clarity. Primed atoms were generated by symmetry (-x, -y + 1, -z).
	Fig. 2. Packing diagram of (I).
	Fig. 3. Overlay of calculated and observed structures of (I)

trans-tetrabromidobis(dimethyl sulfide-κS)platinum(IV)

Crystal data

[PtBr4(C2H6S)2]	F(000) = 572
Mr = 638.99	Dx = 3.356 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 7741 reflections
a = 7.1993 (2) Å	θ = 3.0–28.3°
b = 7.0922 (2) Å	µ = 24.01 mm^−1
c = 12.6033 (3) Å	T = 100 K
β = 100.674 (1)°	Cuboid, red
V = 632.38 (3) Å^3	0.14 × 0.07 × 0.06 mm
Z = 2

Data collection

Bruker X8 APEXII 4K Kappa CCD diffractometer	1577 independent reflections
Graphite monochromator	1503 reflections with I > 2σ(I)
Detector resolution: 8.3 pixels mm^-1	Rint = 0.037
ϕ and ω scans	θmax = 28.3°, θmin = 3.0°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −9→9
Tmin = 0.098, Tmax = 0.239	k = −8→9
12836 measured reflections	l = −16→16

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.019	w = 1/[σ^2(Fo^2) + (0.0206P)^2 + 0.9733P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.048	(Δ/σ)max = 0.001
S = 1.25	Δρmax = 0.60 e Å^−3
1577 reflections	Δρmin = −2.31 e Å^−3
54 parameters

Special details

Experimental. The intensity data was collected on a Bruker X8 Apex II 4 K Kappa CCD diffractometer using an exposure time of 20 s/frame. A total of 2528 frames were collected with a frame width of 0.5° covering up to θ = 28.3° with 100% completeness accomplished.

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Pt	0	0.5	0	0.00571 (7)
Br1	0.12665 (5)	0.42300 (6)	−0.16361 (3)	0.01208 (10)
Br2	0.26367 (5)	0.32209 (5)	0.10955 (3)	0.01170 (9)
S	0.14169 (12)	0.80085 (13)	0.02722 (7)	0.00895 (18)
C1	0.2075 (6)	0.8796 (6)	−0.0964 (3)	0.0152 (8)
H1A	0.2529	1.0099	−0.0878	0.023*
H1B	0.0974	0.8733	−0.1551	0.023*
H1C	0.308	0.7984	−0.1136	0.023*
C2	0.3716 (5)	0.7772 (6)	0.1094 (3)	0.0162 (8)
H2A	0.4487	0.6927	0.0737	0.024*
H2B	0.3599	0.7246	0.1797	0.024*
H2C	0.4323	0.9012	0.1196	0.024*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Pt	0.00420 (10)	0.00743 (12)	0.00574 (11)	0.00062 (7)	0.00159 (7)	0.00040 (6)
Br1	0.01282 (18)	0.0146 (2)	0.01001 (18)	0.00212 (15)	0.00527 (14)	−0.00004 (14)
Br2	0.00882 (18)	0.01303 (19)	0.01265 (18)	0.00292 (14)	0.00047 (14)	0.00183 (13)
S	0.0078 (4)	0.0087 (4)	0.0109 (4)	−0.0010 (3)	0.0033 (3)	−0.0007 (3)
C1	0.018 (2)	0.015 (2)	0.0149 (19)	−0.0038 (16)	0.0078 (16)	0.0043 (16)
C2	0.0117 (18)	0.018 (2)	0.018 (2)	−0.0045 (16)	−0.0012 (15)	−0.0021 (16)

Geometric parameters (Å, º)

Pt—S	2.3624 (9)	S—C1	1.799 (4)
Pt—S^i	2.3624 (9)	C1—H1A	0.98
Pt—Br1^i	2.4654 (4)	C1—H1B	0.98
Pt—Br1	2.4654 (4)	C1—H1C	0.98
Pt—Br2	2.4761 (4)	C2—H2A	0.98
Pt—Br2^i	2.4761 (4)	C2—H2B	0.98
S—C2	1.790 (4)	C2—H2C	0.98
S—Pt—S^i	180	C2—S—C1	99.6 (2)
S—Pt—Br1^i	83.98 (2)	C2—S—Pt	109.11 (15)
S^i—Pt—Br1^i	96.02 (2)	C1—S—Pt	109.30 (14)
S—Pt—Br1	96.02 (2)	S—C1—H1A	109.5
S^i—Pt—Br1	83.98 (2)	S—C1—H1B	109.5
Br1^i—Pt—Br1	180	H1A—C1—H1B	109.5
S—Pt—Br2	96.52 (2)	S—C1—H1C	109.5
S^i—Pt—Br2	83.48 (2)	H1A—C1—H1C	109.5
Br1^i—Pt—Br2	90.607 (12)	H1B—C1—H1C	109.5
Br1—Pt—Br2	89.393 (12)	S—C2—H2A	109.5
S—Pt—Br2^i	83.48 (2)	S—C2—H2B	109.5
S^i—Pt—Br2^i	96.52 (2)	H2A—C2—H2B	109.5
Br1^i—Pt—Br2^i	89.393 (12)	S—C2—H2C	109.5
Br1—Pt—Br2^i	90.607 (12)	H2A—C2—H2C	109.5
Br2—Pt—Br2^i	180	H2B—C2—H2C	109.5
Br1^i—Pt—S—C2	91.04 (15)	Br1^i—Pt—S—C1	−161.04 (15)
Br1—Pt—S—C2	−88.96 (15)	Br1—Pt—S—C1	18.96 (15)
Br2—Pt—S—C2	1.11 (15)	Br2—Pt—S—C1	109.04 (15)
Br2^i—Pt—S—C2	−178.89 (15)	Br2^i—Pt—S—C1	−70.96 (15)

Symmetry code: (i) −x, −y+1, −z.