New Activators for Olefin Polymerization
Organometallics, Vol. 21, No. 20, 2002 4161
desired diboraanthracene product was then collected by sub-
limation at 90 °C/10-5 Torr, affording 8a as a yellow polycrys-
talline solid (1.15 g, 53% yield). 19F NMR (C6D6): δ -122.7
(m, 4F), -143.9 (m, 4F) ppm. 13C NMR (CDCl3): δ 152.6 (d,
1J CF ) 262 Hz), 144.6 (d, 1J CF ) 260 Hz), 122.8 (br, B-C) ppm.
MS (EI, 8.7 V; m/z (% intensity)): 392 (16), 391 (18), 390 (67),
389 (M+, 47), 388 (100), 387 (51), 342 (21), 318 (22), 304 (28),
250 (25), 201 (30). Anal. Calcd for C12F8B2Cl2: C, 37.1; H, 0.0.
Found: C, 38.2; H, 0.3.
Exp er im en ta l Section
Ma ter ia ls a n d Meth od s. Manipulations of air-sensitive
materials were carried out with rigorous exclusion of oxygen
and moisture in flamed Schlenk-type glassware on a dual-
manifold Schlenk line or interfaced to a high-vacuum line (10-6
Torr), or in a nitrogen-filled glovebox with a high-capacity
recirculator (<1 ppm of O2). Argon, ethylene, and propylene
(Matheson, polymerization grade) were purified by passage
through supported MnO oxygen removal and activated Davi-
son 4A molecular sieve columns. Ether solvents were purified
by distillation from Na/K alloy/benzophenone ketyl, and
hydrocarbon solvents were distilled from Na/K alloy. All
solvents for high-vacuum-line manipulations were stored in
vacuo over Na/K alloy in Teflon-valved bulbs. Deuterated
solvents obtained from Cambridge Isotope Laboratories (all
>99 atom % D) were freeze-pump-thaw degassed, dried over
Na/K alloy, and stored in resealable flasks. Other nonhaloge-
nated solvents were dried over Na/K alloy, while halogenated
solvents were distilled from P2O5 and stored over activated
Davison 4A molecular sieves. CH3CN (Aldrich) was dried over
CaH2 and then over activated 4A molecular sieves before
vacuum transfer. The precatalysts Cp2ZrMe2,11 CGCTiMe2,12
Syn th esis of C12F 8B2(C6F 5)2 (8b). A thick-walled tube
fitted with a J . Young valve was charged with 0.265 g of 8a
15
(0.68 mmol) and 0.33 g of (C6F5)2SnMe2 (0.68 mmol). The
flask was then attached to the vacuum line and cooled to -78
°C, 20 mL of toluene was condensed in, and the valve was
closed. The reaction solution was next heated to 140 °C for 72
h, affording a bright yellow solution. After the mixture was
cooled to room temperature, the solvent was removed by bulb-
to-bulb distillation under dynamic vacuum. The Me2SnCl2
reaction product was also removed under dynamic vacuum
(10-5 Torr/12 h). The crude 8b was then recrystallized twice
from 10 mL of toluene (slow cooling to -78 °C), giving the
desired product as a light yellow crystalline solid (0.35 g, 80%
yield). 19F NMR (toluene-d8): δ -118.2 (br, 4F, ortho C6F4),
14
Me2Si(Ind)2ZrMe2,13 and (C5Me5)2ZrMe2 were prepared by
3
4
-133.9 (dd, J FF ) 25.1 Hz; J FF ) 7.9 Hz, 4F, ortho C6F5),
published procedures.
3
-138.9 (m, 4F, meta C6F4), -152.1 (t, J FF ) 21 Hz, 2F, para
3
3
5
P h ysica l a n d An a lytica l Mea su r em en ts. NMR spectra
were recorded on Varian VXR 300 (FT 300 MHz, 1H; 75 MHz,
13C), Unity 400 (FT 400 MHz, 1H; 100 MHz, 13C; 377 MHz,
C6F5), -161.4 (ddd, J FF ) 22 Hz; J FF ) 22 Hz, J FF ) 7 Hz,
4F, meta C6F5) ppm. 13C NMR (CDCl3): δ 156.1 (d, 1J CF ) 267
1
1
Hz), 145.9 (d, J CF ) 265 Hz), 144.3 (d, J CF ) 241 Hz), 141.6
1
19F), or Gemini-300 (FT 300 MHz, H; 75 MHz, 13C; 282 MHz,
1
1
(d, J CF ) 265 Hz), 137.6 (d, J CF ) 253 Hz), 128.3 (br), 123.7
(br) ppm. Anal. Calcd for C24F18B2: C, 44.22; H, 0.00. Found:
C, 42.61; H, 0.52. This compound proved difficult to combust,
resulting in consistently low C analyses, despite attempts with
X-ray-quality crystals.
1
19F) instruments. Chemical shifts for H and 13C spectra were
referenced using internal solvent resonances and are reported
relative to tetramethylsilane. 19F NMR spectra were referenced
to external CFCl3. NMR experiments on air-sensitive samples
were conducted in Teflon valve sealed sample tubes (J . Young).
Melting temperatures of polymers were measured by DSC
(DSC 2920, TA Instruments, Inc.) from the second scan with
a heating rate of 10 °C/min.
Equ ilibr a tion of Aceton itr ile betw een B(C6F 5)3 a n d 8b.
A J . Young NMR tube was charged with 8b (0.0100 g, 0.015
3g
mmol) and CH3CNfB(C6F5)3 (0.0085 g, 0.015 mmol) in the
glovebox, and C7D8 was added. The temperature of the NMR
spectrometer was set to the desired temperature and the
temperature confirmed by the line separation of ethylene glycol
or methanol temperature calibration standards. The 8b + CH3-
CN + B(C6F5)3 solution was placed into the spectrometer and
allowed to equilibrate for 1.0 h, and the spectrum was then
recorded. This procedure was repeated until spectra had been
obtained at 40, 30, 21, 0, -10, -22, -27, and -47 °C.
Integration of the para fluorine signals on B(C6F5)3 and CH3-
CNfB(C6F5)3 was used to determine the equilibrium concen-
trations. At no time during the equilibrations, at any temper-
ature, were any peaks assignable to a bis(acetonitrile) adduct
of 8b detected. All peaks in the spectra can be readily assigned
to resonances of B(C6F5)3, CH3CNfB(C6F5)3, 8b, or 8brNCCH3.
Syn th esis of C12F 8B2(C6F 5)2rNCCH3, (8brNCCH3). A
J . Young NMR tube was charged with 8b (0.0100 g, 0.015
Syn th esis of C12F 8B2Cl2 (8a ). On the vacuum line, excess
BCl3 (5.0 g, 44 mmol) was condensed at -196 °C into a thick-
walled reaction tube fitted with a J . Young valve and contain-
ing 5.3 g (11.1 mmol) of 1,2-C6F4(SnMe3)2.18 The flask was then
evacuated to 0.05 Torr, the valve was closed, and the reaction
mixture was heated at 180 °C for 18 h. (Caution! In addition
to evacuating the system prior to heating, the reaction tube
should be enclosed in a steel pipe behind a blast shield.) After
the reaction mixture was cooled to 25 °C, excess BCl3 was
removed under dynamic vacuum, yielding a beige, slightly
moist crude product. The crude product was extracted with
pentane (3 × 20 mL), leaving behind after filtration ca. 65%
of the Me3SnCl reaction product. The remaining Me3SnCl was
removed by vacuum sublimation at 40 °C/10-5 Torr. The
(12) Samuel, E.; Rausch, M. D. J . Am. Chem. Soc. 1973, 95, 6263-
6267.
3g
mmol) and CH3CNfB(C6F5)3 (0.0085 g, 0.015 mmol) in the
glovebox, and C7D8 was added. The mixture was allowed to
stand at room temperature for 1 week, affording colorless
needles of CH3CNf8b (0.0071 g, 67% yield). 19F NMR
(13) (a) Stevens, J . C.; Timmers, F. J .; Wilson, D. R.; Schmidt, G.
F.; Nickias, P. N.; Rosen, R. K.; Knight, G. W.; Lai, S. Y. Constrained
Geometry Addition Polymerization Catalysts, Processes for Their
Preparation, Precursors Therefor, Methods of Use, and Novel Polymers
Formed Therewith; (Dow Chemical Co.). Eur. Patent EP0416815,
March 13, 1991. (b) Canich, J . M.; Hlatky, G. G.; Turner, H. W.
Aluminum-Free Monocyclopentadienylmetallocene Catalysts for Olefin
Polymerization; (Exxon Chemical Patents, Inc.). WO-9200333 A2, J an
9, 1992. (c) Canich, J . A. M. Olefin Polymerization Catalysts (Exxon
Chemical Patents, Inc.). Eur. Patent EP-420436A1, April 3, 1991.
(14) (a) Herrmann, W. A.; Herdtweck, E.; Winter, A.; Spaleck, W.;
Rohrmann, J . Angew. Chem., Int. Ed. Engl. 1989, 28, 1511-1512. (b)
Herfert, N.; Fink, G. Makromol. Chem., Rapid Commun. 1993, 14, 91-
96.
3
(toluene-d8): δ -122.5 (d, 2 F, J FF ) 18 Hz), -132.9 (d, 2 F,
3
3J FF ) 18 Hz), -134 (br, 2 F), -136.4 (d, 2 F, J FF ) 23 Hz),
3
4
-144.2 (dd, 2 F, J FF ) 29 Hz, J FF ) 13 Hz), -154.3 (t, 1 F,
3J FF ) 20 Hz), -154.9 (d, 2F, J FF ) 20 Hz), -156.4 (t, 1 F,
3
3J FF ) 21 Hz), -162 (br, 2 F), -163.0 (dd, 2 F, J FF ) 21, J FF
3
4
) 8 Hz). 1H NMR (toluene-d8): δ 2.18 (s, 3 H). Anal. Calcd for
C
26H3B2NF18: C, 45.07; H, 0.44; N, 2.02. Found: C, 44.86; H,
0.53; N, 1.94.
In Situ Gen er a tion a n d Sp ectr oscop y of Ion P a ir 10.
In the glovebox, 8b (0.0051 g, 8.0 µmol) and Cp2ZrMe2 (0.0020
g, 8.0 µmol) were charged into a J . Young NMR tube. The tube
was removed from the glovebox and interfaced to the high-
vacuum line, and CD2Cl2 was condensed in at -78 °C. The
solution was maintained at -78 °C until introduction into the
spectrometer probe. 19F NMR (CD2Cl2, 25 °C): δ -123.1 (br,
(15) Manriquez, J . M.; McAlister, D. R.; Sanner, R. D.; Bercaw, J .
E. J . Am. Chem. Soc. 1978, 100, 2716-2724.
(16) Fenton, D. E.; Massey, A. G.; J olley, K. W.; Sutcliffe, L. H.
Chem. Commun. 1967, 1097-1098.
(17) Sheldrick, G. M. SHELXS-97; University of Go¨ttingen, Go¨ttin-
gen, Germany, 1990.
(18) Sheldrick, G. M. SHELXL-97; University of Go¨ttingen, Go¨ttin-
gen, Germany, 1997.