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The octahedral title complex, [PtI
4(C
2H
6S)
2] or
trans-PtI
4(dms)
2 (dms is dimethyl sulfide), crystallizes in the monoclinic space group
P2
1/
n (
Z = 2), with molecular symmetry
Ci, which is the most frequently occurring point group for
trans-Pt
X4L2 {56%, 28 structures in the Cambridge Structural Database (CSD) [Allen (2002).
Acta Cryst. B
58, 380-388]}, followed by
C1 (22%, 11 structures). The complexes form a puckered pseudo-hexagonal layer in the (10
) plane, and the layers are stacked with an interplanar distance of 7.10 Å. Density functional theory (DFT) calculations on an isolated complex with the observed parameters as a starting structure converged to
C2h. Constraints to
Ci on the observed geometry give 3-4 kJ mol
-1 higher energy compared with
C2h. DFT calculations on [PtCl
4(PzH)
2] (PzH is pyrazole), reported in the CSD in both the
cis and
trans forms, show an energy difference of 21 kJ mol
-1 in favour of the
trans complex. A CSD search for Pt
X4L2-type complexes, where
X is a halogen and
L is a ligand with a donor atom from group 14, 15 or 16, indicated a preferred
trans geometrical arrangement, with a total fraction of 68%. The dominating crystal packing operators for the
trans complexes are an inversion centre combined with a screw axis/glide plane (48%), followed by an inversion centre alone (28%).
Supporting information
CCDC reference: 677126
The title compound was obtained during an attempted synthesis of
trans-PtI2(diphenylsulfide)2, by recrystallization of
trans-PtI2(dms)2 in diphenylsulfide. It is known that triodide and
iodine formed by air oxidation of iodide may oxidize PtII to PtIV (Olsson,
1986). The synthesis of trans-PtI2(dms)2 was performed according to
a literature procedure, with a few modifications (Roulet & Barbey, 1973).
[K2PtCl4] (100 mg, 0.241 mmol) was dissolved in water (20 ml). To this, KI
(1.5 equivalents, 60 mg, 0.361 mmol) was added. The solution was stirred for
30 min, an excess of dimethyl sulfide (0.45 ml, 6.03 mmol) was added and the
mixture was left to stir. After 2 h, the complex trans-PtI2(dms)2
was filtered off (yield 93 mg, 71%). trans-PtI2(dms)2 (50 mg, 0.087 mmol) was dissolved in diphenyl sulfide (8 ml) and left in a freezer. From
this, trans-PtI4(dms)2 crystallized out as red cuboids.
DFT calculations were performed at the s-VWN level with the basis sets
def-TZVPP for Pt and I, TZVPP for Cl, and 6–31G* for C, H and N atoms, using
the software TURBOMOLE 5.5 (Alrichs et al., 1989).
The H atoms were positioned geometrically with fixed C—H distances of 0.96 Å
[Uiso(H) = 1.5Ueq(C)]. The highest residual peak is 1.65 Å3, 0.68 Å from I2 and the deepest hole -1.22 Å3, 0.69 Å from Pt
[not in accordance with values above]. A Hirshfeld test failure appeared
in the structure validation, with the U values of two iodine sites
being large in relation to the Pt centre. Suspecting compositional disorder,
from Cl in the starting material, a disordered model was introduced using the
PART instruction in SHELXL97 (Sheldrick, 1997), thus refining the
U values of a possible Cl atom at an occupancy value of 0.02. Although
the Hirshfeld test was passed, given that the occupancy is so small the values
were considered unreliable and the disorder model was not adopted. A similar
problem was previously overcome [encountered? reported?] in the crystal
structure of [PtI2(C9H21P)2] (Constable et al., 2006).
Data collection: SMART-NT (Bruker, 1998); cell refinement: SAINT-Plus (Bruker, 2004); data reduction: SAINT-Plus and XPREP (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 & Berndt, 2001); software used to prepare material for publication: WinGX (Farrugia, 1999).
trans-bis(dimethyl sulfide)tetraiodidoplatinum(IV)
top
Crystal data top
[PtI4(C2H6S)2] | Z = 2 |
Mr = 826.95 | F(000) = 716 |
Monoclinic, P21/n | Dx = 3.71 Mg m−3 |
Hall symbol: -P 2yn | Mo Kα radiation, λ = 0.71073 Å |
a = 7.5635 (15) Å | µ = 18.06 mm−1 |
b = 7.4984 (15) Å | T = 293 K |
c = 13.346 (3) Å | Rod, red |
β = 102.06 (3)° | 0.17 × 0.05 × 0.03 mm |
V = 740.2 (3) Å3 | |
Data collection top
Bruker SMART 1K CCD diffractometer | 1479 reflections with I > 2σ(I) |
Radiation source: rotating anode | Rint = 0.040 |
ω scans | θmax = 28°, θmin = 2.9° |
Absorption correction: multi-scan SADABS (Bruker, 2004) | h = −9→9 |
Tmin = 0.149, Tmax = 0.613 | k = −9→7 |
6602 measured reflections | l = −16→17 |
1774 independent reflections | |
Refinement top
Refinement on F2 | 0 restraints |
Least-squares matrix: full | H-atom parameters constrained |
R[F2 > 2σ(F2)] = 0.029 | w = 1/[σ2(Fo2) + (0.0272P)2 + 0.602P] where P = (Fo2 + 2Fc2)/3 |
wR(F2) = 0.065 | (Δ/σ)max < 0.001 |
S = 1.06 | Δρmax = 1.07 e Å−3 |
1774 reflections | Δρmin = −0.95 e Å−3 |
54 parameters | |
Crystal data top
[PtI4(C2H6S)2] | V = 740.2 (3) Å3 |
Mr = 826.95 | Z = 2 |
Monoclinic, P21/n | Mo Kα radiation |
a = 7.5635 (15) Å | µ = 18.06 mm−1 |
b = 7.4984 (15) Å | T = 293 K |
c = 13.346 (3) Å | 0.17 × 0.05 × 0.03 mm |
β = 102.06 (3)° | |
Data collection top
Bruker SMART 1K CCD diffractometer | 1774 independent reflections |
Absorption correction: multi-scan SADABS (Bruker, 2004) | 1479 reflections with I > 2σ(I) |
Tmin = 0.149, Tmax = 0.613 | Rint = 0.040 |
6602 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.029 | 0 restraints |
wR(F2) = 0.065 | H-atom parameters constrained |
S = 1.06 | Δρmax = 1.07 e Å−3 |
1774 reflections | Δρmin = −0.95 e Å−3 |
54 parameters | |
Special details top
Experimental. The intensity data were collected on a Siemens SMART 1 K CCD
diffractometer using an exposure time of 30 s/frame. A total of 1315 frames
were collected with a frame width of 0.3° covering up to θ = 28.00° with
100% completeness accomplished. The first 50 frames were recollected at the
end of each data collection to check for decay; none was found. We screened the CSD for the crystal class distribution [Belsky, V. K., Zorkaya,
O. N. & Zorky, P. M. (1995). Acta Cryst. A51, 473–481],which contains
information about the molecular point group symmetry. The search was done
using the CONQUEST software package (Bruno et al., 2002). DFT-calculations were done using Turbomole 5.5 (Alrichs et al., 1989) |
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 (Å2) top | x | y | z | Uiso*/Ueq | |
Pt1 | 1 | 0 | 1 | 0.03096 (11) | |
I1 | 0.86489 (6) | 0.08880 (7) | 1.16451 (3) | 0.04635 (14) | |
I2 | 0.72171 (6) | 0.17370 (7) | 0.87853 (4) | 0.05010 (15) | |
S1 | 1.1315 (2) | 0.2911 (2) | 1.02060 (14) | 0.0422 (4) | |
C1 | 1.1860 (11) | 0.3703 (11) | 0.9039 (6) | 0.058 (2) | |
H1A | 1.2408 | 0.486 | 0.9152 | 0.087* | |
H1B | 1.0775 | 0.3783 | 0.8518 | 0.087* | |
H1C | 1.2687 | 0.2891 | 0.8823 | 0.087* | |
C2 | 1.3581 (10) | 0.2808 (12) | 1.0972 (7) | 0.061 (2) | |
H2A | 1.425 | 0.1898 | 1.0708 | 0.092* | |
H2B | 1.3531 | 0.2534 | 1.1669 | 0.092* | |
H2C | 1.4166 | 0.3939 | 1.0948 | 0.092* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Pt1 | 0.02545 (16) | 0.0390 (2) | 0.02898 (17) | 0.00422 (14) | 0.00694 (12) | 0.00138 (15) |
I1 | 0.0446 (2) | 0.0603 (4) | 0.0380 (2) | 0.0054 (2) | 0.01724 (19) | −0.0030 (2) |
I2 | 0.0371 (2) | 0.0593 (3) | 0.0506 (3) | 0.0123 (2) | 0.0016 (2) | 0.0076 (2) |
S1 | 0.0395 (8) | 0.0416 (11) | 0.0481 (10) | −0.0003 (7) | 0.0152 (7) | −0.0022 (8) |
C1 | 0.060 (5) | 0.064 (6) | 0.055 (5) | −0.006 (4) | 0.023 (4) | 0.010 (4) |
C2 | 0.049 (4) | 0.068 (6) | 0.063 (5) | −0.014 (4) | 0.003 (4) | −0.007 (4) |
Geometric parameters (Å, º) top
Pt1—S1i | 2.3904 (18) | S1—C2 | 1.805 (7) |
Pt1—S1 | 2.3904 (18) | C1—H1A | 0.96 |
Pt1—I1 | 2.6918 (7) | C1—H1B | 0.96 |
Pt1—I1i | 2.6918 (7) | C1—H1C | 0.96 |
Pt1—I2i | 2.7070 (8) | C2—H2A | 0.96 |
Pt1—I2 | 2.7070 (8) | C2—H2B | 0.96 |
S1—C1 | 1.793 (8) | C2—H2C | 0.96 |
| | | |
S1i—Pt1—S1 | 180.00 (9) | C1—S1—C2 | 98.2 (4) |
S1i—Pt1—I1 | 95.74 (4) | C1—S1—Pt1 | 111.6 (3) |
S1—Pt1—I1 | 84.26 (4) | C2—S1—Pt1 | 110.4 (3) |
S1i—Pt1—I1i | 84.26 (4) | S1—C1—H1A | 109.5 |
S1—Pt1—I1i | 95.74 (4) | S1—C1—H1B | 109.5 |
I1—Pt1—I1i | 180 | H1A—C1—H1B | 109.5 |
S1i—Pt1—I2i | 83.23 (5) | S1—C1—H1C | 109.5 |
S1—Pt1—I2i | 96.77 (5) | H1A—C1—H1C | 109.5 |
I1—Pt1—I2i | 90.62 (2) | H1B—C1—H1C | 109.5 |
I1i—Pt1—I2i | 89.38 (2) | S1—C2—H2A | 109.5 |
S1i—Pt1—I2 | 96.77 (5) | S1—C2—H2B | 109.5 |
S1—Pt1—I2 | 83.23 (5) | H2A—C2—H2B | 109.5 |
I1—Pt1—I2 | 89.38 (2) | S1—C2—H2C | 109.5 |
I1i—Pt1—I2 | 90.62 (2) | H2A—C2—H2C | 109.5 |
I2i—Pt1—I2 | 180 | H2B—C2—H2C | 109.5 |
Symmetry code: (i) −x+2, −y, −z+2. |
Experimental details
Crystal data |
Chemical formula | [PtI4(C2H6S)2] |
Mr | 826.95 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 293 |
a, b, c (Å) | 7.5635 (15), 7.4984 (15), 13.346 (3) |
β (°) | 102.06 (3) |
V (Å3) | 740.2 (3) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 18.06 |
Crystal size (mm) | 0.17 × 0.05 × 0.03 |
|
Data collection |
Diffractometer | Bruker SMART 1K CCD diffractometer |
Absorption correction | Multi-scan SADABS (Bruker, 2004) |
Tmin, Tmax | 0.149, 0.613 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6602, 1774, 1479 |
Rint | 0.040 |
(sin θ/λ)max (Å−1) | 0.661 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.065, 1.06 |
No. of reflections | 1774 |
No. of parameters | 54 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.07, −0.95 |
Selected geometric parameters (Å, º) topPt1—S1 | 2.3904 (18) | S1—C1 | 1.793 (8) |
Pt1—I1 | 2.6918 (7) | S1—C2 | 1.805 (7) |
Pt1—I2 | 2.7070 (8) | | |
| | | |
S1—Pt1—I1 | 84.26 (4) | C1—S1—C2 | 98.2 (4) |
S1—Pt1—I2 | 83.23 (5) | C1—S1—Pt1 | 111.6 (3) |
I1—Pt1—I2 | 89.38 (2) | C2—S1—Pt1 | 110.4 (3) |
Comparative geometric data (Å, °) for trans-
tetrahalide PtIV(dms)2 compounds topX | Pt-X1 | Pt-X2 | Pt-S | S-C1 | S-C2 | X1-Pt-S | X2-Pt-S | X1-Pt-X2 | X1···X2 | S···S |
Cl(i) | 2.313 (3) | 2.319 (33) | 2.363 (10) | 1.784 (48) | 1.794 (6) | 95.68 (5) | 83.43 (4) | 90.42 (5) | 3.759 (2) | 3.58 (1) |
Br(ii) | 2.475 (1) | 2.467 (1) | 2.364 (2) | 1.76 (1) | 1.804 (13) | 96.05 (7) | 83.75 (6) | 90.57 (4) | 3.922 (2) | 3.57 (1) |
I(iii) | 2.6918 (7) | 2.7070 (8) | 2.3904 (18) | 1.793 (8) | 1.805 (7) | 96.77 (5) | 83.23 (5) | 89.38 (1) | 3.923 (58) | 3.69 (1) |
I(iv) | 2.70 | 2.70 | 2.36 | 1.79 | 1.79 | 98.8 | 81.1 | 89.7 | — | — |
(i) Toffoli et al. (1987);
(ii) Skvortsov et al. (1994);
(iii) this work;
(iv) DFT results. |
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The principal nonzero oxidation states of Pt are II and IV. cis/trans- PtIIX2L2 complexes, where X is a halogen and L a ligand with a donor atom from groups 14, 15 or 16, have been extensively studied in the solid state, with 316 entries in the Cambridge Structural Database (Allen, 2002). Data for PtIVX4L2 are scarce, and here we report the structure of the title compound together with data mining for this class of compounds in the CSD (2006 release), with emphasis on the following: (i) Is there a preference for cis- or trans-complexes in the solid state? (ii) What molecular symmetries are retained in the solid state? (iii) Which are the dominating crystal packing operators?
The title compound, trans-PtI4(dms)2 (dms is dimethyl sulfide), crystallizes in the monoclinic space group P21/n (Z = 2), with molecular symmetry Ci (Fig. 1). The Pt—I distances (Table 1) are slightly larger than those observed in cis-[PtI4(net)2] [net is ethylamine, NC2H5; Pt—I = 2.65 Å for I atoms in trans positions and 2.61 Å for I atoms trans to N (Thiele et al., 1999)]. Geometry optimization of the title compound, using density functional theory (DFT) calculations with the observed parameters as a starting structure, converged to C2h. Constraints to Ci on the observed geometry give 3–4 kJ mol-1 higher energy compared with C2h, which would require a space group that hampers close packing, indicating that intermolecular forces determine the point group for the complex. There is good agreement between the calculated and observed geometry (Table 2), and the deviation from 90° of the I—Pt—S angle observed in the crystal structure is even larger in the calculated one, suggesting that it is the result of an intramolecular effect.
The geometries of isostructural trans-PtX4(dms)2 (X= Cl, Br or I) are given in Table 2. The Pt—S distances are about the same for X = Cl and Br (2.36 Å) but significantly larger for X = I [2.390 (2) 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°, which further supports the idea that this is an intramolecular effect. The intermolecular X···X contact of 3.92 (6) Å is on the short side for X = I and on the long side for X = Cl and Br. However I···I contacts as short as 3.48 Å have been observed in cis-[PtI4(net)2].
trans-PtX4(dms)2 forms a puckered pseudo-hexagonal close-packed layer in the (101) plane, with four I···I contacts [3.92 (1) Å] and two S···S contacts [3.69 (1) Å; Fig. 2]. Halogen–halogen interactions are known for stabilizing supramolecular structures (Desiraju, 1995). The stacking layers are parallel-displaced, resulting in a pseudo-close packing with an inter-layer distance of 7.10 Å, with notable inter-layer contacts [H···I = 3.23 Å and C—H···I = 153.12°] and also some soft H···H contacts (2.86 Å). For the isostructural compounds, the distortion from an ideal close packing is about the same for the bromide but much more severe for the chloride, as manifested by the Pt···Pt···Pt angles within a layer, which are close to 120° for both the iodide and bromide but only about 100° for the chloride.
The CSD was searched using CONQUEST (Bruno et al., 2002) for cis/trans-PtX4L2 complexes, where X is a halogen and L a ligand containing donor atoms from groups 14, 15 or 16. Simple solvates are included, but no chelates or structures with no coordinates, obscure connectivity or disorder. The majority of these 50 complexes (68%) preferred the trans configuration (Tables A and B, deposited material), compared with 50% in the system trans-PtX2L2 (Hansson et al., 2006). The complex [PtCl4(PzH)2] (PzH is pyrazole, N2C3H4) is reported in the CSD as both the cis and the trans isomers (Khripun et al., 2006). DFT calculations on these complexes show a difference between the cis and trans isomers of 21 kJ mol-1 in favour of the trans complex in the gas phase, also indicating a preference for the trans configuration.
Complexes trans-PtX4L2 may adopt the molecular point groups C1, Ci, Cs, C2, C2v and C2h. Table C (deposited material) shows that Ci is retained in 56% of cases, followed by C1 (22%), Cs (12%), C2 (8%) and C2 h (2%), with no representatives for C2v; the order of preference is Ci (78%), C1 (16%), C2 (11%) and C2h (2%) for trans-PtX2L2 (Hansson et al., 2006). C2v is not represented in any of the systems and C2h has very low frequency, in accordance with Kitaigorodsky's rule (Kitaigorodsky, 1973) that C2v requires space groups that hamper close packing and C2h may adopt maximal density in space group C2/m, which is actually observed in both systems.
The dominating crystal-packing operator is an inversion centre as the sole packing operator in 28% of cases (neglecting pure translations which are always present), an inversion centre together with a screw axis/glide plane in 48% and an inversion centre in combination with other operators in 6% (Table C, deposited). It is interesting to note that P21 and P212121 only represent 6% os cases, in contrast to the situation for organic molecules, where these space groups are relatively frequent (Brock & Dunitz, 1994; Oskarsson, 2007).