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[(Et
3
P)
2
Pt(H)]
+
fragment. This species was produced
in situ
via chloride ion ab-
straction from
trans
-[(Et
3
P)
2
Pt(H)(Cl)] with Na
+
[3,5-(CF
3
)
2
C
6
H
3
]
4
B
-
in fluoroben-
zene. When reacted with
trans
-[(Et
3
P)
2
Pt(H)(Cl)] and 1 equiv. of Na
+
[3,5-
(CF
3
)
2
C
6
H
3
]
4
B
-
, substituted norbornenes formed
trans
-[(Et
3
P)
2
Pt(H)(
2
-norbor-
nene-R)]
+
instantaneously and quantitatively (Eq. (4)). Heating the NB-COOEt ad-
duct of (Et
3
P)
2
PtH
+
in fluorobenzene the presence of 5 equiv. of NB-COOEt led to
the formation of the product derived by the insertion of norbornene into the
Pt(II)-H bond.
4
The crystal structure of the insertion product is shown in Fig. 9.4 [10]. It is
clear that the insertion has occurred from the
endo
face of the norbornene sub-
strate. As with the structure shown in Fig. 9.1, the two Pt-P bond distances are
substantially different from one another. The Pt-P distance
trans
to the Pt-carbon
bond is significantly longer (2.355 versus 2.211 Å).
Thus far, we have confined our discussions as to the effect of coordinating func-
tionalities on metal-catalyzed polymerizations. Interestingly, vinyl halides, which
2
-C,O-(
endo,endo
)-norbornene-
Fig. 9.4
ORTEP representation of
cis
-Pt(
COOCH
2
CH
3
)(P(CH
2
CH
3
)
3
)
+
.
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