β-Diketonate Platinum(ii) Complexes with Sulfoxide Ligands
FULL PAPER
as internal references (δ = 7.24 for CDCl3, δ = 3.30 for CD3OD
and δ = 4.65 for D2O).
diethylether (20 mL) to the filtered chloroform solution (yield
65 mg, 28%).
Starting Materials: Commercial reagent grade chemicals, acetyl-
acetone and solvents were used without further purification.
[Pt(O,OЈ-acac)2],[7] [PtCl2(DMSO)2][21] and K[PtCl3(DMSO)][22]
were prepared by previously reported procedures.
Reaction of [Pt(O,OЈ-acac)2] with DMSO: [Pt(O,OЈ-acac)2] (2 mg,
0.005 mmol), synthesised by a previously reported procedure, was
dissolved in CDCl3 (0.5 mL) and the resultant solution placed in
an NMR tube. DMSO (1 µL, 1.17 mg, 0.015 mmol) was added
and the solution was monitored by recording 1H NMR spectra
periodically over a period of two weeks. The spectra did not show
any significant change over that period of time.
[PtCl(O,OЈ-acac)(DMSO)] (1):
A solution of acetylacetone
(97.5 mg, 0.973 mmol) and KOH (19.5 mg, 0.487 mmol) in meth-
anol (5 mL) was added dropwise to a solution of K[PtCl3(DMSO)]
(204 mg, 0.487 mmol) in water (10 mL) at room temperature with
stirring. After few minutes a yellow precipitate separated from the
solution. The reaction mixture was left stirring overnight and the
pale-yellow precipitate of [PtCl(O,OЈ-acac)(DMSO)] (1) was then
isolated by filtration and dried under vacuum (yield 149 mg, 75%).
C7H13ClO3SPt (407.79): calcd. C 20.62, H 3.21; found C 20.73, H
3.28.
Single-Crystal X-ray Diffraction Study: Pale-yellow crystals of
[Pt(O,OЈ-acac)(γ-acac)(DMSO)] were obtained by crystallisation
from CHCl3/pentane. X-ray data were collected using an Enraf–
Nonius CAD4 diffractometer. A least-squares algorithm using 25
automatically centred reflections was used to refine the unit cell
dimensions. A total of 6726 independent reflections were collected
in the range –10 Յ h Յ 10, –13 Յ k Յ 14 and 0 Յ l Յ 23. Four
reflections were monitored during data collection but no decay was
observed. Crystallographic data are summarised in Table 4. The
full data set was corrected for Lorentz and polarisation effects and
an absorption correction was applied using the DIFABS pack-
age[23] at the isotropic stage of refinement. The structure was solved
Alternatively,
a
solution containing acetylacetone (97 mg,
0.966 mmol) and KOH (27 mg, 0.483 mmol) in water (5 mL) was
added dropwise to a suspension of [PtCl2(DMSO)2] (204 mg,
0.483 mmol) in water (10 mL) at room temperature with stirring.
The reaction mixture slowly became a yellow solution. After 3 h,
a pale-yellow solid started to precipitate. The suspension was left
stirring for one day and the solid was then filtered and dried under
vacuum (yield 27 mg, 26%). C7H13ClO3SPt (407.79): calcd. C
20.62, H 3.21; found C 20.51, H 3.18.
¯
by direct-methods in the P1 space group. The model was refined by
full-matrix least-squares methods. Anisotropic thermal parameters
were applied for all non-hydrogen atoms. All hydrogen atoms were
placed in their geometrically calculated positions and were included
in the full-matrix least-square cycles with isotropic thermal param-
eters (U) fixed at 1.2 and 1.5 (for methyl group) times the values
of U of the corresponding carbon atoms. Crystallographic calcula-
tions were carried out and molecular graphics designed using the
SIR97,[24] SHELXL97,[25] WinGX,[26] ORTEP for Windows[27] and
PARST97[28] packages. CCDC-172448 contains the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
[Pt(O,OЈ-acac)(γ-acac)(DMSO)] (2): A solution of acetylacetone
(358 mg, 3.576 mmol) and KOH (114 mg, 2.860 mmol) in methanol
(5 mL) was added dropwise to a suspension of [PtCl2(DMSO)2]
(302 mg, 0.715 mmol) in methanol (20 mL) at room temperature
with stirring. The reaction mixture slowly became a pale yellow
solution. After one day, the solvent was evaporated under vacuum
and the yellow residue was extracted with CHCl3 (10 mL). The
chloroform solution was then filtered to remove KCl and K(acac),
pentane (30 mL) was added and the resultant solution kept over-
night at 5 °C. Quadrangular pale-yellow crystals of [Pt(O,OЈ-
acac)(γ-acac)(DMSO)] (2) which separated out from the solution
were filtered, washed with pentane and dried under vacuum (yield
168 mg, 50%). C12H20O5SPt (471.441): calcd. C 30.57, H 4.28;
found C 30.73, H 4.34.
Supporting Information (see footnote on the first page of this arti-
cle): Figure S1, 1H-13C HETCOR and long range HETCOR NMR
spectra of 1. Figures S2, molecular structure of 2a. Figure S3,
molecular structure of 2b. Figure S4, unit cell projection of 2 along
a-axis with all atoms except hydrogens. Table S5, anisotropic dis-
placement parameters for 2 and 2a. Table S6, anisotropic displace-
ment parameters for 2b.
K[Pt(O,OЈ-acac)(γ-acac)2] (3): A solution of acetylacetone (332 mg,
3.318 mmol) and KOH (94.8 mg, 2.370 mmol) in methanol (5 mL)
was added dropwise to a suspension of [PtCl2(DMSO)2] (200 mg,
0.474 mmol) in methanol (20 mL) at room temperature with stir-
ring. After 1 h, the suspension became a pale-yellow solution which
was left stirring for three days. The solvent was then removed under
vacuum and the residual yellow oil was extracted with CHCl3
(10 mL). The chloroform solution was then filtered to separate KCl
and K(acac), and pentane (30 mL) was added causing the precipi-
tation of K[Pt(O,OЈ-acac)(γ-acac)2] (3) as a yellow solid. The pro-
duct was separated by filtration, washed with pentane and dried
under vacuum (yield 68 mg, 27%). C15H24KO6Pt (534.524): calcd.
C 33.70, H 4.53; found C 33.46, H 4.21.
Acknowledgments
The authors gratefully acknowledge Mr. Alessandro Laurita (Uni-
versity of Potenza) for the X-ray diffraction data collection. This
work was supported by the University of Lecce and the Ministero
dell’Istruzione, dell’Università e della Ricerca (M.I.U.R.), Cofin.
2003 (No. 2003039774_005).
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Alternatively, a solution of acetylacetone (129 mg, 1.284 mmol)
and KOH (48 mg, 0.856 mmol) in methanol (10 mL) was added
dropwise to
a suspension of [Pt(O,OЈ-acac)(γ-acac)(DMSO)]
(202 mg, 0.428 mmol) in diethylether (30 mL) at room temperature
with stirring. The colour of the solid in the reaction mixture slowly
turned from white to pale-yellow. After one day, the solvent was
removed under vacuum and the residue was washed with diethyl
ether (10 mL) then extracted with chloroform (10 mL). K[Pt(O,OЈ-
acac)(γ-acac)2] was obtained as a pale-yellow solid by addition of
Eur. J. Inorg. Chem. 2005, 788–796
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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De Pascali, Sandra A.
