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Z. Beni et al. / Inorganica Chimica Acta 358 (2005) 497–503
502
a neutral Al2O3 pad (10 cm · 6 cm2) and eluted with tol-
uene. The eluate was reduced to a small volume. The
product precipitated by n-heptane and recrystallized
from dichloromethane/heptane as red microcrystals.
Yield 0.45 g (71 %). Anal. Calc. for C78H60O6P4Pt5: C,
42.73; H, 2.76. Found: C, 42.58; H, 2.80%. IR (THF):
Anal. Calc. for C30H60O6P4Pt5: C, 22.29; H, 3.74.
Found: C, 22.15; H, 3.70%. IR (THF): 1988 vs, 1877
m, 1843 s, 1798 vs, 1776 vs, 1765 vs cmÀ1
.
5.5. Synthesis of [Pt5(CO)(l-CO)5(PCy3)4] (5)
THF solution (150 ml) containing [Pt3(l-
2003 vs, 1896 w, 1862 m, 1817 s, 1793 vs cmÀ1
.
A
CO)3(PCy3)3] (1.0 g, 0.662 mmol) and [PtCl2(CH3CN)2]
(0.19 g, 0.546 mmol) was saturated with CO (45 ml). An
excess of zinc dust (0.371 g, 5.7 mmol) was added and
the reaction mixture vigorously stirred under CO at
room temperature for 6 days. The excess of zinc dust
was filtered off and the solution was chromatographed
on a column (35 cm · 7 cm2) packed with silica gel
(70–230 mesh). Elution with THF/n-hexane (2:1)
gave a first red-brown fraction containing unreacted
[Pt3(l-CO)3(PCy3)3] together with other non identified
mono- and polynuclear carbonyl derivatives, which were
discarded. Subsequent elution with THF gave orange-
red solution. Concentration of this solution followed
by standing and cooling overnight at À22 ꢁC deposited
5 as red microcrystals. Overall yield based on Pt, 0.83 g
(72%). Anal. Calc. for C78H132O6P4Pt5: C, 41.36; H,
5.87. Found: C, 41.33; H, 5.70%. Single crystals were
grown from toluene by slow diffusion of n-hexane at 5
ꢁC. IR (THF) 1983 vs, 1868 w, 1829 m, 1794 vs, 1772
5.2. Synthesis of [Pt5(CO)(l-CO)5(PBzPh2)4] (2)
As for 1 starting with [Pt3(l-CO)3(PBzPh2)3] (0.65 g,
0.434 mmol), treated with 0.15 ml (1.5 mmol) of H2O2
(30%) and stirred for 2 days. Yield 0.51 g (87%) as red
microcrystals. Anal. Calc. for C82H68O6P4Pt5: C, 43.80;
H, 3.05. Found: C, 43.66; H, 3.05%. IR (CH2Cl2):
2001 s, 1893 w, 1847 m, 1803 vs, 1775 vs; (nujol mull):
1989 s, 1895 w, 1851 m, 1798 s, 1773 s cmÀ1
.
5.3. Synthesis of [Pt5(CO)(l-CO)5(AsPh3)4] (3)
This complex was prepared following the method re-
ported by Mingos et al. [5], starting with [PtCl2(AsPh3)2]
(2.7 g, 3.07 mmol). Yield 0.51 g (35%) as red microcrys-
tals. Anal. Calc. for C78H60As4O6Pt5: C, 39.56; H, 2.55.
Found: C, 39.82; H, 2.64%. IR (CH2Cl2): 2001 vs, 1890
w, 1856 m, 1807 vs, 1783 vs; (Nujol mull): 1996 vs, 1891
vs cmÀ1
.
w, 1853 m, 1811 s, 1783 vs cmÀ1
.
Crystal data for C78H132O6P4Pt5 Æ C7H8 Æ 0.5C6H14;
M/g molÀ1 2400.39; T/K 140(2); crystal system: mono-
˚
clinic; space group C2/c; a/A 25.9603(10); b/A
˚
3
˚
˚
17.6303(9); c/A 42.7560(15); b/ꢁ 97.012(3); V/A
19422.5(14); Z 8; Dc/g cmÀ3: 1.642; F(000) 9384; crystal
dimensions 0.43 · 0.26 · 0.18 mm3; l/mmÀ1 7.288; h
range 3.43 to 25.03ꢁ; reflections collected/unique
57147/11165 [Rint 0.0741]; R1 0.0564, wR2 [I>2r(I)]
0.0941. The crystal was analysed on a Stoe IPDS sys-
tem equipped with Mo radiation. More than 11% of
the volume of the cell is empty, this means that more
than 1 toluene and half n-hexane should be placed in
the asymmetric unit (but this is very difficult due, the
disorder affecting the solvent and the very weak dif-
fracting power of such atoms compared to the cluster).
The potential solvent molecules which occupy the void
in the cell were not detected from the electron density
map; therefore, these molecules are not included in
the final model. Intensities were integrated and cor-
rected for Lorentz and polarization effects. An absorp-
tion correction based on the crystal habitus was
computed with the help of the XPREP [20] program.
The decay during the measurements was negligible.
5.4. Synthesis of [Pt5(CO)(l-CO)5(PEt3)4] (4)
A suspension of [PtCl2(CH3CN)2] (1.6 g, 4.6 mmol)
in THF was saturated with an excess of CO for 3 h.
PEt3 (0.57 ml, 3.9 mmol) was added, the mixture stirred
for 10 h, and the reaction progress was followed by IR
spectroscopy. When the maximun concentration of
the
carbonyl
intermediate cis-[PtCl2(CO)(PEt3)]
(m(CO) = 2103 cmÀ1) was observed, zinc dust (1.5 g, 23
mmol) was added and the mixture stirred until the ini-
tially developing green colour turned red and its IR
spectrum showed the disappearance of the m(CO)
absorption at 2103 cmÀ1 and the appearance of a strong
absorption at 1989 cmÀ1 (terminal CO) together with
those of bridging COs: 1877 m, 1843 s, 1797 vs, 1776
vs and 1765 vs. After 60 h, the excess of zinc dust was
filtered off and the solvent removed in vacuo. The resi-
due was extracted with dichloromethane, transferred
to the top of a chromatographic column (18 cm · 16
cm2) packed with silica gel (70–230 mesh) and eluted
with dichloromethane. The first orange-red fraction
was reduced to ca. 20 ml and treated with methanol
(70 ml). The solution was evaporated until all the dichlo-
romethane was removed and cooled to À20 ꢁC over-
night. The red crystals of 4 were filtered, washed with
cold methanol and dried in vacuo. Yield 0.95 g (64%).
The structures were solved with the help of DIRDIF
-
99 [21] and refined by means of SHELXS-97 [22]. All
non-hydrogen atoms were refined anisotropically, ex-
cept the atoms of the solvent molecules, and all hydro-
gens were made to ride isotropically on their associated
carbons.
Béni, Zoltàn
