(
)
18
P. Espinet et al.rJournal of Organometallic Chemistry 551 1998 9–20
Ž
.
(
) [
.
.
(
)
] (
)
evaporated to dryness. Addition of ethanol 25 ml to
the residue and filtration gave a white solid, which was
5.2.2. Preparation of NBu4 Pt2 m-I 2 R4 9b
w
Ž
2x
Ž
.
A mixture of PtR2 COD 1.5 g, 2.13 mmol and
NBu4 I 0.788 g, 2.13 mmol was refluxed in toluene
60 ml for 4 h. The resulting colorless solution was
evaporated to dryness and the residue washed with
pentane 2=30 ml to remove the free COD. After a
new addition of toluene 60 ml , the mixture was re-
fluxed for 3 h and concentrated in vacuo to dryness.
Addition of isopropanol to the resulting residue gave a
white solid, which was filtered, washed with iso-
Ž
.
Ž
washed with ethanol, and air-dried 2a, 93% .
Ž
.
(
) [ )
5.1.3. Preparation of NBu4 PtR4 2b and NBu4
2
] (
)
(
2
Ž
.
{
[
]}
trans- PtCl2 r2
To a solution of LiR 9 mmol in Et2O 50 ml at
Ž
.
Ž
.
Ž
.
Ž
.
y788C, under N2 , was added PtCl2 0.266 g, 1 mmol .
The reaction mixture was allowed to warm to room
Ž
.
temperature and stirred overnight. Et2O 10 ml , moist-
ened with some drops of water, was added and the
solution was evaporated. The residue was treated with
acetone 50 ml , filtered and the resulting solution
evaporated to dryness. The solid obtained was extracted
with ethanol 20 ml , and NBu4 Br 0.645 g, 2 mmol
was added to the filtrate to give a white solid, which
was filtered, washed with ethanol, and air-dried 2b,
76% . A similar procedure starting from LiR 11.28
mmol , PtCl2 1.5 g, 5.64 mmol , and NBu4 Br 3.63 g,
11.28 mmol gave a mixture of yellow 3b and 2b 10:1
proportion . The separation of 3b 65% from the mix-
Ž
.
propanol, and dried 9b, 88% .
Ž
.
(
) [ )
(
)
] (
5.2.3. Preparation of NBu4 M2 m-Cl 2 R4 10a, 10b
2
w
Ž
.
x
Ž
.
To a solution of NBu4 PtR4 1.48 g, 1 mmol in
2
Ž
.
Ž
.
Ž
.
a methanolracetone 30:30, 50 ml mixture was added
Ž
.
dropwise a solution of HCl 4.5 ml, 2 mmol in
methanol. The solution was stirred for 90 min at room
temperature, then concentrated to 5 ml. The white pre-
Ž
.
Ž
.
Ž
.
Ž
Ž
cipitate was filtered, and washed with methanol 10b,
94% . 10a was prepared similarly 90% . An alternative
and more convenient synthesis of 10a is to reflux
NBu4 PdR4 1.39 g, 1 mmol and PdCl2 0.178 g, 1
mmol in acetone for 8 h.
.
Ž
.
Ž
.
.
Ž
.
Ž
.
w
x
Ž
.
Ž
ture was achieved by recrystallization in acetone.
2
.
[
] (
) (
)
.
5.1.4. Preparation of MR2 L2 Lstht, SMe2 4-7
Ž
.
Ž
[
(
) ] (
Ž
)
Ž
To a solution of LiR 8.48 mmol in Et2O 50 ml at
5.2.4. Preparation of MR2 THF 2 8a, 8b
w
Ž
.
2 x
Ž
Ž
.
w
.
x
.
y788C, under N2 , was added PdCl2 tht
1.5 g, 4.24
To a solution of NBu4 M2 m-X R4 0.7 mmol
in dry THF 25 ml under N2 was added AgClO4 0.29
g, 1.4 mmol . After 12 h stirring the precipitate AgX
was filtered off and the solution evaporated to dryness.
The residue was extracted with dry Et2O 2=70 ml
2
2
.
Ž
.
Ž
mmol , and the mixture was allowed to warm to room
temperature and stirred for 4 h. The resulting suspen-
.
Ž
.
Ž
.
sion was hydrolized with moist Et2O 10 ml , and
evaporated to dryness. The residue was extracted with
CH2Cl2 100 ml , and the filtrate was evaporated to 5
ml, treated with ethanol 5 ml , and concentrated to 5
ml. The resulting suspension was filtered and the solid
washed with cold ethanol and air-dried mixture of 4a
Ž
.
Ž
.
under N2 , and the insoluble NBu4ClO4 was removed.
The clear solution was vacuum-concentrated to ca. 5 ml.
Ž
.
Ž
.
Upon addition of pentane 10 ml , a white precipitate
Ž
Ž
.
appeared 8a, 84%; 8b, 77% .
.
and 5a, 80% . The solid mixture was first extracted with
Ž
.
CH2Cl2 2=30 ml yielding a residue of pure trans
isomer 5a. The organic solution, which still contained
cis- and trans complexes, was evaporated to dryness
[
(
) ] ( )
7b
5.2.5. Preparation of trans- PtR SMe2
2
Ž
.
w
2 x
Ž
.
.
A mixture of NBu4 PtCl2 R2 0.450 g, 0.39 mmol
and AgNO3 0.133 g, 0.78 mmol in acetonitrile 40 ml
was stirred for 10 min, and then SMe2 1 ml, 13.6
mmol was added. After 2 h stirring, the AgCl was
2
Ž
.
Ž
Ž
and the solid was chromatographied silica gel 60,
Ž
.
CH2Cl2:n-hexane 1:5 giving pure fractions of 4a and
.
5a.
filtered off, and the solution evaporated to dryness.
w
Ž
.
2 x
Ž
.
A mixture of cis- and trans- PdR2 SMe2
and the analogous Pt complexes 4b–7b were prepared
similarly see Table 1 . Pure 7a can be separated from
the mixture of isomers by extraction in Et2O.
6a, 7a ,
Ž
.
Addition of methanol 10 ml to the residue gave a
white solid that was recrystallized from CH2Cl2–
Ž
.
Ž
.
Ž
.
methanol 7b, 65% .
[
] ( )
5.2.6. Preparation of cis- MR2 L2 11-14
5.2. Complexes with two R groups bonded to the metal
center
w
Ž
.
2 x
Ž
.
0.15 mmol in
To a solution of cis- MR2 THF
Ž
.
Ž
.
CH2Cl2 30 ml was added L 0.30 mmol , and the
mixture was stirred for 15 min. The resulting colorless
solution was evaporated to dryness to give white cis-
(
) [
(
Ž
)
] (
)
5.2.1. Preparation of NBu4 Pd m-Br 2 R4 9a
2
w
Ž
.
x2
.
w
x
To a solution of PdR2 COD 0.8 g, 1.3 mmol in
acetone 40 ml , was added NBu4 Br 0.52 g, 1.6 mmol .
After 10 min the solvent was evaporated, and the
MR2 L2 , which was washed with n-pentane and air-
Ž
.
Ž
.
Ž
.
dried quantitative yields . An alternative and more
w
x
Ž
Ž
.
convenient synthesis of cis- PdR2 L
12a–14a is
2 x
Ž
.
w
Ž
.
residue was stirred with isopropanol 10 ml to give a
achieved starting from cis- PdR2 COD 0.092 g, 0.15
Ž
.
.
Ž
.
pale yellow solid 9a, 96% .
mmol and L 0.30 mmol , with similar work up.
Espinet, Pablo
