Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S160053680703704X/si2029sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S160053680703704X/si2029Isup2.hkl |
CCDC reference: 660045
Key indicators
- Single-crystal X-ray study
- T = 243 K
- Mean (t-C) = 0.010 Å
- R factor = 0.033
- wR factor = 0.078
- Data-to-parameter ratio = 26.5
checkCIF/PLATON results
No syntax errors found
Alert level C ABSTM02_ALERT_3_C The ratio of expected to reported Tmax/Tmin(RR) is > 1.10 Tmin and Tmax reported: 0.053 0.099 Tmin and Tmax expected: 0.042 0.099 RR = 1.248 Please check that your absorption correction is appropriate. PLAT060_ALERT_3_C Ratio Tmax/Tmin (Exp-to-Rep) (too) Large ....... 1.22 PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X) Pt1 - Br3 .. 6.90 su PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) . 1.11 Ratio
Alert level G PLAT794_ALERT_5_G Check Predicted Bond Valency for Pt2 (2) 2.23 PLAT794_ALERT_5_G Check Predicted Bond Valency for Pt3 (2) 2.26
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 4 ALERT level C = Check and explain 2 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 1 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 1 ALERT type 4 Improvement, methodology, query or suggestion 2 ALERT type 5 Informative message, check
To a solution of µ-[(1,2,5,6-η:3,4,7,8-η)-1,3,5,7-cyclooctatetraene]bis[dimethylplatinum(II)] (0.0965 g, 0.174 mmol) in CH2Cl2 (40 ml) and MeOH (5 ml) was added hydrobromic acid (48%; 0.0876 g, 0.519 mmol) and stirred for 4 h at room temparature. The solvent was removed in vacuo, the residue was washed with pentane, and dried, to give a dark yellow powder (0.0692 g). Crystals suitable for X-ray analysis were obtained by slow evaporation from a CH2Cl2 solution.
H atoms were positioned geometrically and allowed to ride on their respective carrier atoms, with C—H = 0.97 Å and with Uiso(H) = 1.5Ueq(C).
Trimethylplatinum(IV) halides, hydroxide and pseudohalides reveal structures of cubane-like clusters with the tetrameric unit, [{Pt(CH3)3L}4] (L = F, Cl, Br, I, OH, N3 etc.), and the tetrameric units show approximately -43m symmetry. F (Donath et al., 1998), Cl (Rundle & Sturdivant, 1947) and OH clusters (Cowan et al., 1968; Spiro et al., 1968; Preston et al., 1968; Donath et al., 1998) are isostructural and crystallize in the cubic achiral space group I -43m. The N3 cluster (Atam & Müller, 1974) crystallizes in the trigonal space group P -3c1. The crystal structure of trimethylplatinum(IV) bromide with toluene solvent was previously reported (Massa et al., 1988), which crystallizes in the lower symmetric monoclinic space group C 2/m. This can be explained by hydrophobic interactions or packing effects of the structure.
The title complex shows a distorted cubane-type structure of the tetrameric [{Pt(CH3)3Br}4] unit (Fig. 1), and is disposed about a mirror plane passing through atoms Pt1, Pt2, Br1, Br2, and two methyl groups C1 and C3, parallel to the a,c plane of the unit cell, which coincide with the crystallographic mirror plane m of space group C 2/m (Fig. 2). Each Pt4+ ion is coordinated by three methyl groups and three µ3-Br atoms, and the coordination geometry around respective Pt centre is distorted octahedral. Mean interatomic distances: Pt—Br 2.693 Å, Pt—C 2.028 Å, Pt···Pt 3.933 Å, Br···Br 3.668 Å. Mean bond angles: Br—Pt—Br 86.0°, Pt—Br—Pt 94.1°.
For historical background, see: Rundle & Sturdivant (1947); Atam & Müller (1974). For the corresponding tetrameric trimethylplatinum(IV) bromide with disordered toluene solvent, see: Massa et al. (1988).
For related literature, see: Cowan et al. (1968); Donath et al. (1998); Preston et al. (1968); Spiro et al. (1968).
Data collection: SMART (Bruker, 2000); cell refinement: SAINT (Bruker, 2000); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.
[Pt4Br4(CH3)12] | F(000) = 2240 |
Mr = 1280.41 | Dx = 3.428 Mg m−3 |
Monoclinic, C2/m | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2y | Cell parameters from 2875 reflections |
a = 13.8146 (12) Å | θ = 2.5–26.4° |
b = 14.0793 (12) Å | µ = 28.92 mm−1 |
c = 12.8194 (11) Å | T = 243 K |
β = 95.681 (2)° | Prism, yellow |
V = 2481.1 (4) Å3 | 0.15 × 0.10 × 0.08 mm |
Z = 4 |
Bruker SMART 1000 CCD diffractometer | 2655 independent reflections |
Radiation source: fine-focus sealed tube | 2189 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.035 |
φ and ω scans | θmax = 26.4°, θmin = 1.6° |
Absorption correction: multi-scan (SADABS; Bruker, 2000) | h = −11→17 |
Tmin = 0.053, Tmax = 0.099 | k = −17→17 |
7252 measured reflections | l = −14→16 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.033 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.078 | H-atom parameters constrained |
S = 0.98 | w = 1/[σ2(Fo2) + (0.0396P)2] where P = (Fo2 + 2Fc2)/3 |
2655 reflections | (Δ/σ)max < 0.001 |
100 parameters | Δρmax = 1.37 e Å−3 |
0 restraints | Δρmin = −1.86 e Å−3 |
[Pt4Br4(CH3)12] | V = 2481.1 (4) Å3 |
Mr = 1280.41 | Z = 4 |
Monoclinic, C2/m | Mo Kα radiation |
a = 13.8146 (12) Å | µ = 28.92 mm−1 |
b = 14.0793 (12) Å | T = 243 K |
c = 12.8194 (11) Å | 0.15 × 0.10 × 0.08 mm |
β = 95.681 (2)° |
Bruker SMART 1000 CCD diffractometer | 2655 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2000) | 2189 reflections with I > 2σ(I) |
Tmin = 0.053, Tmax = 0.099 | Rint = 0.035 |
7252 measured reflections |
R[F2 > 2σ(F2)] = 0.033 | 0 restraints |
wR(F2) = 0.078 | H-atom parameters constrained |
S = 0.98 | Δρmax = 1.37 e Å−3 |
2655 reflections | Δρmin = −1.86 e Å−3 |
100 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Pt1 | 0.26473 (3) | 0.5000 | 0.04527 (4) | 0.03258 (14) | |
Pt2 | 0.19786 (4) | 0.5000 | 0.33920 (4) | 0.03475 (14) | |
Pt3 | 0.42659 (2) | 0.36035 (2) | 0.26219 (3) | 0.03335 (12) | |
Br1 | 0.45060 (8) | 0.5000 | 0.12802 (9) | 0.0289 (3) | |
Br2 | 0.38834 (9) | 0.5000 | 0.39601 (10) | 0.0345 (3) | |
Br3 | 0.23514 (6) | 0.36904 (5) | 0.19303 (7) | 0.0321 (2) | |
C1 | 0.1250 (9) | 0.5000 | −0.0110 (14) | 0.067 (5) | |
H1A | 0.1200 | 0.5000 | −0.0870 | 0.100* | |
H1B | 0.0935 | 0.5563 | 0.0133 | 0.100* | |
C2 | 0.2882 (7) | 0.3993 (7) | −0.0637 (8) | 0.051 (3) | |
H2A | 0.3563 | 0.3815 | −0.0564 | 0.077* | |
H2B | 0.2707 | 0.4246 | −0.1334 | 0.077* | |
H2C | 0.2486 | 0.3439 | −0.0530 | 0.077* | |
C3 | 0.0533 (8) | 0.5000 | 0.2947 (11) | 0.045 (3) | |
H3A | 0.0180 | 0.5000 | 0.3564 | 0.067* | |
H3B | 0.0364 | 0.4437 | 0.2532 | 0.067* | |
C4 | 0.1728 (8) | 0.4010 (7) | 0.4491 (8) | 0.056 (3) | |
H4A | 0.1798 | 0.3379 | 0.4203 | 0.084* | |
H4B | 0.1073 | 0.4087 | 0.4690 | 0.084* | |
H4C | 0.2192 | 0.4092 | 0.5102 | 0.084* | |
C5 | 0.4531 (7) | 0.2591 (6) | 0.1556 (8) | 0.051 (3) | |
H5A | 0.4689 | 0.2892 | 0.0914 | 0.076* | |
H5B | 0.3957 | 0.2197 | 0.1408 | 0.076* | |
H5C | 0.5072 | 0.2199 | 0.1836 | 0.076* | |
C6 | 0.4019 (8) | 0.2560 (7) | 0.3638 (8) | 0.054 (3) | |
H6A | 0.3857 | 0.2836 | 0.4292 | 0.081* | |
H6B | 0.4598 | 0.2171 | 0.3769 | 0.081* | |
H6C | 0.3482 | 0.2168 | 0.3342 | 0.081* | |
C7 | 0.5703 (7) | 0.3580 (7) | 0.3175 (9) | 0.055 (3) | |
H7A | 0.5817 | 0.4026 | 0.3751 | 0.082* | |
H7B | 0.6094 | 0.3756 | 0.2618 | 0.082* | |
H7C | 0.5880 | 0.2945 | 0.3420 | 0.082* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Pt1 | 0.0258 (3) | 0.0422 (3) | 0.0296 (3) | 0.000 | 0.0016 (2) | 0.000 |
Pt2 | 0.0380 (3) | 0.0323 (2) | 0.0361 (3) | 0.000 | 0.0144 (2) | 0.000 |
Pt3 | 0.0380 (2) | 0.03095 (18) | 0.0316 (2) | 0.00585 (14) | 0.00579 (16) | 0.00379 (14) |
Br1 | 0.0270 (6) | 0.0359 (6) | 0.0242 (6) | 0.000 | 0.0049 (5) | 0.000 |
Br2 | 0.0397 (7) | 0.0398 (6) | 0.0237 (6) | 0.000 | 0.0027 (5) | 0.000 |
Br3 | 0.0328 (5) | 0.0284 (4) | 0.0363 (5) | −0.0031 (3) | 0.0093 (4) | −0.0019 (3) |
C1 | 0.026 (7) | 0.087 (11) | 0.081 (13) | 0.000 | −0.021 (8) | 0.000 |
C2 | 0.045 (6) | 0.066 (6) | 0.040 (6) | −0.004 (5) | −0.005 (5) | −0.011 (5) |
C3 | 0.028 (7) | 0.050 (8) | 0.059 (10) | 0.000 | 0.015 (7) | 0.000 |
C4 | 0.076 (8) | 0.051 (6) | 0.043 (7) | −0.012 (5) | 0.023 (6) | 0.011 (5) |
C5 | 0.059 (7) | 0.039 (5) | 0.055 (7) | 0.008 (5) | 0.008 (5) | −0.001 (5) |
C6 | 0.065 (7) | 0.050 (6) | 0.050 (7) | 0.001 (5) | 0.011 (5) | 0.024 (5) |
C7 | 0.049 (7) | 0.061 (7) | 0.053 (7) | 0.017 (5) | 0.003 (5) | 0.001 (5) |
Pt1—C1 | 1.993 (13) | C1—H1A | 0.9700 |
Pt1—C2 | 2.038 (9) | C1—H1B | 0.9700 |
Pt1—C2i | 2.038 (9) | C2—H2A | 0.9700 |
Pt1—Br1 | 2.6794 (12) | C2—H2B | 0.9700 |
Pt1—Br3i | 2.7034 (9) | C2—H2C | 0.9700 |
Pt1—Br3 | 2.7034 (9) | C3—H3A | 0.9700 |
Pt2—C3 | 2.021 (12) | C3—H3B | 0.9700 |
Pt2—C4i | 2.035 (9) | C4—H4A | 0.9700 |
Pt2—C4 | 2.035 (9) | C4—H4B | 0.9700 |
Pt2—Br2 | 2.6599 (13) | C4—H4C | 0.9700 |
Pt2—Br3 | 2.7143 (9) | C5—H5A | 0.9700 |
Pt2—Br3i | 2.7143 (9) | C5—H5B | 0.9700 |
Pt3—C6 | 2.015 (8) | C5—H5C | 0.9700 |
Pt3—C5 | 2.034 (9) | C6—H6A | 0.9700 |
Pt3—C7 | 2.041 (10) | C6—H6B | 0.9700 |
Pt3—Br1 | 2.6546 (8) | C6—H6C | 0.9700 |
Pt3—Br2 | 2.6958 (9) | C7—H7A | 0.9700 |
Pt3—Br3 | 2.7076 (9) | C7—H7B | 0.9700 |
Br1—Pt3i | 2.6546 (8) | C7—H7C | 0.9700 |
Br2—Pt3i | 2.6958 (9) | ||
C1—Pt1—C2 | 88.1 (5) | Pt3i—Br1—Pt3 | 95.58 (4) |
C1—Pt1—C2i | 88.1 (5) | Pt3i—Br1—Pt1 | 94.60 (3) |
C2—Pt1—C2i | 88.1 (6) | Pt3—Br1—Pt1 | 94.60 (3) |
C1—Pt1—Br1 | 177.9 (5) | Pt2—Br2—Pt3i | 94.40 (3) |
C2—Pt1—Br1 | 93.4 (3) | Pt2—Br2—Pt3 | 94.40 (3) |
C2i—Pt1—Br1 | 93.4 (3) | Pt3i—Br2—Pt3 | 93.66 (4) |
C1—Pt1—Br3i | 92.6 (4) | Pt1—Br3—Pt3 | 92.85 (3) |
C2—Pt1—Br3i | 178.8 (3) | Pt1—Br3—Pt2 | 94.16 (3) |
C2i—Pt1—Br3i | 92.9 (3) | Pt3—Br3—Pt2 | 92.90 (3) |
Br1—Pt1—Br3i | 85.87 (3) | Pt1—C1—H1A | 109.5 |
C1—Pt1—Br3 | 92.6 (4) | Pt1—C1—H1B | 109.5 |
C2—Pt1—Br3 | 92.9 (3) | H1A—C1—H1B | 109.5 |
C2i—Pt1—Br3 | 178.8 (3) | Pt1—C2—H2A | 109.5 |
Br1—Pt1—Br3 | 85.87 (3) | Pt1—C2—H2B | 109.5 |
Br3i—Pt1—Br3 | 86.01 (4) | H2A—C2—H2B | 109.5 |
C3—Pt2—C4i | 87.9 (4) | Pt1—C2—H2C | 109.5 |
C3—Pt2—C4 | 87.9 (4) | H2A—C2—H2C | 109.5 |
C4i—Pt2—C4 | 86.4 (6) | H2B—C2—H2C | 109.5 |
C3—Pt2—Br2 | 179.5 (4) | Pt2—C3—H3A | 109.5 |
C4i—Pt2—Br2 | 92.4 (3) | Pt2—C3—H3B | 109.5 |
C4—Pt2—Br2 | 92.4 (3) | H3A—C3—H3B | 109.5 |
C3—Pt2—Br3 | 93.1 (3) | Pt2—C4—H4A | 109.5 |
C4i—Pt2—Br3 | 178.9 (3) | Pt2—C4—H4B | 109.5 |
C4—Pt2—Br3 | 94.0 (3) | H4A—C4—H4B | 109.5 |
Br2—Pt2—Br3 | 86.49 (3) | Pt2—C4—H4C | 109.5 |
C3—Pt2—Br3i | 93.1 (3) | H4A—C4—H4C | 109.5 |
C4i—Pt2—Br3i | 94.0 (3) | H4B—C4—H4C | 109.5 |
C4—Pt2—Br3i | 178.9 (3) | Pt3—C5—H5A | 109.5 |
Br2—Pt2—Br3i | 86.49 (3) | Pt3—C5—H5B | 109.5 |
Br3—Pt2—Br3i | 85.58 (4) | H5A—C5—H5B | 109.5 |
C6—Pt3—C5 | 88.6 (4) | Pt3—C5—H5C | 109.5 |
C6—Pt3—C7 | 89.1 (4) | H5A—C5—H5C | 109.5 |
C5—Pt3—C7 | 89.4 (4) | H5B—C5—H5C | 109.5 |
C6—Pt3—Br1 | 177.4 (3) | Pt3—C6—H6A | 109.5 |
C5—Pt3—Br1 | 92.4 (3) | Pt3—C6—H6B | 109.5 |
C7—Pt3—Br1 | 93.3 (3) | H6A—C6—H6B | 109.5 |
C6—Pt3—Br2 | 93.7 (3) | Pt3—C6—H6C | 109.5 |
C5—Pt3—Br2 | 177.3 (3) | H6A—C6—H6C | 109.5 |
C7—Pt3—Br2 | 92.1 (3) | H6B—C6—H6C | 109.5 |
Br1—Pt3—Br2 | 85.24 (3) | Pt3—C7—H7A | 109.5 |
C6—Pt3—Br3 | 91.3 (3) | Pt3—C7—H7B | 109.5 |
C5—Pt3—Br3 | 92.7 (3) | H7A—C7—H7B | 109.5 |
C7—Pt3—Br3 | 178.0 (3) | Pt3—C7—H7C | 109.5 |
Br1—Pt3—Br3 | 86.28 (3) | H7A—C7—H7C | 109.5 |
Br2—Pt3—Br3 | 85.92 (3) | H7B—C7—H7C | 109.5 |
C5—Pt3—Br1—Pt3i | −177.2 (3) | C6—Pt3—Br2—Pt3i | 178.4 (3) |
C7—Pt3—Br1—Pt3i | −87.7 (3) | C7—Pt3—Br2—Pt3i | 89.2 (3) |
Br2—Pt3—Br1—Pt3i | 4.04 (4) | Br1—Pt3—Br2—Pt3i | −3.97 (4) |
Br3—Pt3—Br1—Pt3i | 90.25 (3) | Br3—Pt3—Br2—Pt3i | −90.57 (3) |
C5—Pt3—Br1—Pt1 | 87.7 (3) | C1—Pt1—Br3—Pt3 | 176.7 (4) |
C7—Pt3—Br1—Pt1 | 177.2 (3) | C2—Pt1—Br3—Pt3 | 88.5 (3) |
Br2—Pt3—Br1—Pt1 | −91.04 (3) | Br1—Pt1—Br3—Pt3 | −4.74 (2) |
Br3—Pt3—Br1—Pt1 | −4.84 (3) | Br3i—Pt1—Br3—Pt3 | −90.88 (3) |
C2—Pt1—Br1—Pt3i | 176.2 (3) | C1—Pt1—Br3—Pt2 | −90.2 (4) |
C2i—Pt1—Br1—Pt3i | 87.8 (3) | C2—Pt1—Br3—Pt2 | −178.4 (3) |
Br3i—Pt1—Br1—Pt3i | −4.85 (3) | Br1—Pt1—Br3—Pt2 | 88.37 (3) |
Br3—Pt1—Br1—Pt3i | −91.14 (3) | Br3i—Pt1—Br3—Pt2 | 2.23 (4) |
C2—Pt1—Br1—Pt3 | −87.8 (3) | C6—Pt3—Br3—Pt1 | −176.1 (3) |
C2i—Pt1—Br1—Pt3 | −176.2 (3) | C5—Pt3—Br3—Pt1 | −87.4 (3) |
Br3i—Pt1—Br1—Pt3 | 91.14 (3) | Br1—Pt3—Br3—Pt1 | 4.79 (3) |
Br3—Pt1—Br1—Pt3 | 4.85 (3) | Br2—Pt3—Br3—Pt1 | 90.27 (3) |
C4i—Pt2—Br2—Pt3i | −89.7 (3) | C6—Pt3—Br3—Pt2 | 89.6 (3) |
C4—Pt2—Br2—Pt3i | −176.3 (3) | C5—Pt3—Br3—Pt2 | 178.2 (3) |
Br3—Pt2—Br2—Pt3i | 89.90 (3) | Br1—Pt3—Br3—Pt2 | −89.53 (3) |
Br3i—Pt2—Br2—Pt3i | 4.12 (3) | Br2—Pt3—Br3—Pt2 | −4.04 (3) |
C4i—Pt2—Br2—Pt3 | 176.3 (3) | C3—Pt2—Br3—Pt1 | 90.7 (3) |
C4—Pt2—Br2—Pt3 | 89.7 (3) | C4—Pt2—Br3—Pt1 | 178.8 (3) |
Br3—Pt2—Br2—Pt3 | −4.12 (3) | Br2—Pt2—Br3—Pt1 | −88.97 (3) |
Br3i—Pt2—Br2—Pt3 | −89.90 (3) | Br3i—Pt2—Br3—Pt1 | −2.23 (4) |
C6—Pt3—Br2—Pt2 | −86.9 (3) | C3—Pt2—Br3—Pt3 | −176.2 (3) |
C7—Pt3—Br2—Pt2 | −176.1 (3) | C4—Pt2—Br3—Pt3 | −88.1 (3) |
Br1—Pt3—Br2—Pt2 | 90.73 (3) | Br2—Pt2—Br3—Pt3 | 4.10 (3) |
Br3—Pt3—Br2—Pt2 | 4.13 (3) | Br3i—Pt2—Br3—Pt3 | 90.84 (3) |
Symmetry code: (i) x, −y+1, z. |
Experimental details
Crystal data | |
Chemical formula | [Pt4Br4(CH3)12] |
Mr | 1280.41 |
Crystal system, space group | Monoclinic, C2/m |
Temperature (K) | 243 |
a, b, c (Å) | 13.8146 (12), 14.0793 (12), 12.8194 (11) |
β (°) | 95.681 (2) |
V (Å3) | 2481.1 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 28.92 |
Crystal size (mm) | 0.15 × 0.10 × 0.08 |
Data collection | |
Diffractometer | Bruker SMART 1000 CCD |
Absorption correction | Multi-scan (SADABS; Bruker, 2000) |
Tmin, Tmax | 0.053, 0.099 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7252, 2655, 2189 |
Rint | 0.035 |
(sin θ/λ)max (Å−1) | 0.626 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.033, 0.078, 0.98 |
No. of reflections | 2655 |
No. of parameters | 100 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.37, −1.86 |
Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SAINT, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2003), SHELXL97.
Trimethylplatinum(IV) halides, hydroxide and pseudohalides reveal structures of cubane-like clusters with the tetrameric unit, [{Pt(CH3)3L}4] (L = F, Cl, Br, I, OH, N3 etc.), and the tetrameric units show approximately -43m symmetry. F (Donath et al., 1998), Cl (Rundle & Sturdivant, 1947) and OH clusters (Cowan et al., 1968; Spiro et al., 1968; Preston et al., 1968; Donath et al., 1998) are isostructural and crystallize in the cubic achiral space group I -43m. The N3 cluster (Atam & Müller, 1974) crystallizes in the trigonal space group P -3c1. The crystal structure of trimethylplatinum(IV) bromide with toluene solvent was previously reported (Massa et al., 1988), which crystallizes in the lower symmetric monoclinic space group C 2/m. This can be explained by hydrophobic interactions or packing effects of the structure.
The title complex shows a distorted cubane-type structure of the tetrameric [{Pt(CH3)3Br}4] unit (Fig. 1), and is disposed about a mirror plane passing through atoms Pt1, Pt2, Br1, Br2, and two methyl groups C1 and C3, parallel to the a,c plane of the unit cell, which coincide with the crystallographic mirror plane m of space group C 2/m (Fig. 2). Each Pt4+ ion is coordinated by three methyl groups and three µ3-Br atoms, and the coordination geometry around respective Pt centre is distorted octahedral. Mean interatomic distances: Pt—Br 2.693 Å, Pt—C 2.028 Å, Pt···Pt 3.933 Å, Br···Br 3.668 Å. Mean bond angles: Br—Pt—Br 86.0°, Pt—Br—Pt 94.1°.