50
GRINGOLTS et al.
Quadricyclane was synthesized by photochemical IR spectroscopy, and NMR. The exo conformation of
isomerization of norbornadiene in a diethyl ether solu-
tion in the presence of a sensitizer (acetophenone) [4].
The reaction of quadricyclane with trans-bis(trichlo-
rosilyl)ethylene was carried out in an inert atmosphere
at 95°C and the ratio quadricyclane : olefin = 2 : 3. The
the cyclobutane fragment was confirmed by means of
2D NMR: the COSY spectrum lacks cross-peaks due to
coupling of the protons at C-2 (C-5) with the protons at
C-1 (C-6), which is typical of the exo derivatives of nor-
bornene [5]. Two upfield signals in the 1H NMR spec-
trum at 0.00 ppm (9H) and –0.03 ppm (9H) are evi-
dence of the trans arrangement of the Me3Si substitu-
ents.
1
conversion of quadricyclane was monitored by H
NMR. The basic side reaction is the thermal isomeriza-
tion of quadricyclane into norbornadiene. Synthesized
3,4-bis(trichlorosilyl)tricyclo[4.2.1.02,5]non-7-ene and
3,4-bis(trimethylsilyl)tricyclo[4.2.1.02,5]non-7-ene
(BSTN) were isolated as individual compounds and
BSTN was successfully involved in both metathesis
characterized by chromatography/mass spectrometry, (A) and addition (B) polymerizations (Scheme 3).
8
7
8
7
9
9
1
n
SiMe3
n
1
6
9
6
1
6
4
(B)
(A)
5
7
Nf2Ni–MAO
Ru, W
2
3
5
4
2
3
5
4
3
8
2
SiMe3
Me3Si
SiMe3
Me3Si
SiMe3
36%
80–98%
Scheme 3.
Metathesis polymerization (Scheme 3A) was car- reoselectivity and WCl6/TMSB exhibits the lowest ste-
ried out in different catalytic systems, including the
Grubbs catalyst [6], by methods described in [2, 7].
Polymerization yielded amorphous polymers soluble in
aromatics and chlorohydrocarbons. Metathesis poly-
mers obtained from BSIN were characterized by NMR,
IR spectroscopy, gel permeation chromatography
(GPC), and differential scanning calorimetry (DSC).
reoselectivity. An analogous situation was previously
observed for metathesis poly(trimethylsilylnor-
bornene)s [7]. The synthesized silicon-substituted
polytricyclononenes have a lower glass transition tem-
perature (Tg = 130°C) than poly(5,6-bis(trimethylsilyl)-
2-norbornene) (Tg = 167°C) [7].
As distinct from 5,6-bis(trimethylsilyl)-2-nor-
bornene, BSTN is capable of addition homopolymer-
ization (Scheme 3B) over the nickel naphthenate
(Nf2Ni)–methylalumoxane (MAO) catalyst. The poly-
merization was carried out as described in [2]. This
polymerization is slower than metathesis polymeriza-
tion and provides lower yields: at the molar ratio mono-
mer : Ni : MAO = 400 : 1 : 100, the polymer yield is
36%, Mw = 40 000, Mw/Mn = 1.6, and Tg = 168°ë. Such
a behavior of monomers is typical of these polymeriza-
tion schemes since metathesis polymerization is con-
siderably more favorable than addition polymerization.
1
The H NMR spectrum of the polymer shows signals
due to the double bond protons (m, 5.25–5.00 ppm), the
cyclopentane protons (m, 3.06, 2.78, 2.47–1.73, 1.33,
1.08 ppm), and the exo-SiMe3 and endo-SiMe3 protons
(m, 0.01 to –0.07 ppm). Due to different stereoselectiv-
ities of the catalysts used, we were able to identify 1H
NMR signals due to the protons at C-1 (C-6) in the allyl
position to the cis (3.06 ppm) and trans (2.77 ppm)
double bonds. The characteristics of the resulting poly-
mers are summarized in the table. As follows from the
table, the RuCl3–EtOH catalyst exhibits the highest ste-
Metathesis polymerization of 3,4-bis(trimethylsilyl)tricyclo[4.2.1.02.5]non-7-ene
Catalyst
BSTN/catalyst
cis/trans ratio of
double bonds**, %
*
Yield, %
Mw , g/mol
Mw/Mn
Tg, °C
(application conditions) (mol/mol) ratio
RuCl3–EtOH (65°C, 15 h)
Cl2(PCy3)2Ru=C(H)Ph
(20°C, 24 h)
50
500
80
98
98
98
65
8 × 105
4 × 105
8 × 105
1 × 106
2 × 106
2.1
1.6
1.8
1.6
1.4
131
123
5
22
1500
WCl6–TMSB (20°C, 24 h)
100
129
47
500 (30 min)
1
Note: TMSB is 1,1,3,3-tetramethyl-1,3-disilacyclobutane; * determined by GPC using polystyrene standards; ** determined from H
NMR spectra.
DOKLADY CHEMISTRY Vol. 424 Part 2 2009