New organo-lewis acids. Tris(β-perfluoronaphthyl)borane (PNB) as a highly active cocatalyst for metallocene-mediated ziegler-natta α-olefin polymerization

Article abstract of DOI:10.1021/om980229b

Tris(β-perfluoronaphthyl)borane (B(C₁₀F₇)₃, PNB) is synthesized from β-perfluoronaphthyllithium and BCl₃ to serve as a new strong organo-Lewis acid cocatalyst. PNB efficiently activates a variety of group 4 dimethyl complexes to form highly active homogeneous Ziegler-Natta olefin polymerization catalysts. Reaction of PNB with rac-Me₂Si(Ind)₂ZrMe₂ and CGCMMe₂ (M = Zr, Ti; CGC = Me₂Si(η⁵-Me₄C₅)( ^tBuN)) (1:1 molar ratio) rapidly produces the base-free cationic complexes rac-Me₂Si(Ind)₂ZrMe⁺MePNB^- (1) and CGCMMe⁺MePNB^- (M = Zr, 2; Ti, 3), respectively. The μ-methyl dinuclear cationic complex [(CGCTiMe)₂(μ-Me)]⁺MePNB^- (4) is formed when a 2:1 CGCTiMe₂:PNB stoichiometry is employed: In the case of group 4 dimethyl zirconocenes, L₂ZrMe₂ (L = η⁵-C₅H₅, Cp; η⁵-1,2-Me₂C₅H₃, Cp″), reaction in a 1:1 metallocene:PNB ratio affords cationic complexes L₂ZrMe⁺MePNB^- (L = Cp, 5; Cp″, 6), while the reaction with a 1:2 molar ratio affords dinuclear μ-methyl cationic complexes [(L₂ZrMe)₂(μ-Me)]⁺MePNB^- (L = Cp, 7; Cp″, 8). In both reactions, μ-F dinuclear cationic complexes [(L₂ZrMe)₂(M-F)]⁺MePNB^- (L = Cp, 9; Cp″, 10) are formed as byproducts. (C₆F₅)₃BNCCH₃ and PNBNCCH₃ were synthesized and characterized. Analysis of the PNBNCCH₃ + B(C₆F₅)₃ ? (C₆F₅)₃BNCCH₃ + PNB equilibrium yields ΔH° = +0.7(2) kcal/ mol and ΔS° = +4.3(5) eu, suggesting PNB has somewhat higher Lewis acidity and is sterically more encumbered than B(C₆F₅)₃. Solution ν(CN) values for PNBNCCH₃ and (C₆F₅)₃-BNCCH₃ are 2365.3 and 2366.5 cm^-1, respectively, which indicate strong Lewis acidity. PBBNCCH₃ cannot be detected in the reaction of (C₆F₅)₃BNCCH₃ with PBB [PBB = tris-(2,2′,2″-perfluorobipheny)lborane] over prolonged periods at 60°C. In ethylene polymerization, PNB-derived cationic complexes 5, 6, 7, and 8 have catalytic activities similar to the B(C₆F₅)₃-derived analogues, while 2 and 3 have substantially higher activities. In propylene polymerization, catalyst 1 has higher activity than the B(C₆F₅)₃ analogue. In the case of ethylene and 1-hexene copolymerization, PNB-derived cationic complex 3 exhibits higher polymerization activity with similar 1-hexene incorporation versus the B(C₆F₅)₃-derived cationic complex. In large-scale batch copolymerizations of ethylene and 1-octene mediated by CGCTiMe₂, the PNB-based catalytic systems exhibit approximately twice the activity of the B(C₆F₅)₃-based systems.

Full text of DOI:10.1021/om980229b

3996
Organometallics 1998, 17, 3996-4003
New Or ga n o-Lew is Acid s.
Tr is(â-p er flu or on a p h th yl)bor a n e (P NB) a s a High ly
Active Coca ta lyst for Meta llocen e-Med ia ted
Ziegler -Na tta r-Olefin P olym er iza tion
Liting Li and Tobin J . Marks*
Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113
Received March 26, 1998
Tris(â-perfluoronaphthyl)borane (B(C10F7)3, PNB) is synthesized from â-perfluoronaph-
thyllithium and BCl3 to serve as a new strong organo-Lewis acid cocatalyst. PNB efficiently
activates a variety of group 4 dimethyl complexes to form highly active homogeneous Ziegler-
Natta olefin polymerization catalysts. Reaction of PNB with rac-Me2Si(Ind)2ZrMe2 and
CGCMMe2 (M ) Zr, Ti; CGC ) Me2Si(η5-Me4C5)(tBuN)) (1:1 molar ratio) rapidly produces
the base-free cationic complexes rac-Me2Si(Ind)2ZrMe+MePNB- (1) and CGCMMe+MePNB-
(M ) Zr, 2; Ti, 3), respectively. The µ-methyl dinuclear cationic complex [(CGCTiMe)2(µ-
Me)]+MePNB- (4) is formed when a 2:1 CGCTiMe2:PNB stoichiometry is employed. In the
case of group 4 dimethyl zirconocenes, L2ZrMe2 (L ) η5-C5H5, Cp; η5-1,2-Me2C5H3, Cp′′),
reaction in a 1:1 metallocene:PNB ratio affords cationic complexes L2ZrMe+MePNB- (L )
Cp, 5; Cp′′, 6), while the reaction with a 1:2 molar ratio affords dinuclear µ-methyl cationic
complexes [(L2ZrMe)2(µ-Me)]+MePNB- (L ) Cp, 7; Cp′′, 8). In both reactions, µ-F dinuclear
cationic complexes [(L2ZrMe)2(µ-F)]+MePNB- (L ) Cp, 9; Cp′′, 10) are formed as byproducts.
(C6F5)3BNCCH3 and PNBNCCH3 were synthesized and characterized. Analysis of the
PNBNCCH3 + B(C6F5)3 h (C6F5)3BNCCH3 + PNB equilibrium yields ∆H° ) +0.7(2) kcal/
mol and ∆S° ) +4.3(5) eu, suggesting PNB has somewhat higher Lewis acidity and is
sterically more encumbered than B(C6F5)3. Solution ν(CN) values for PNBNCCH3 and (C6F5)3-
BNCCH3 are 2365.3 and 2366.5 cm-1, respectively, which indicate strong Lewis acidity.
PBBNCCH3 cannot be detected in the reaction of (C6F5)3BNCCH3 with PBB [PBB ) tris-
(2,2′,2′′-perfluorobipheny)lborane] over prolonged periods at 60 °C. In ethylene polymeri-
zation, PNB-derived cationic complexes 5, 6, 7, and 8 have catalytic activities similar to the
B(C6F5)3-derived analogues, while 2 and 3 have substantially higher activities. In propylene
polymerization, catalyst 1 has higher activity than the B(C6F5)3 analogue. In the case of
ethylene and 1-hexene copolymerization, PNB-derived cationic complex 3 exhibits higher
polymerization activity with similar 1-hexene incorporation versus the B(C6F5)3-derived
cationic complex. In large-scale batch copolymerizations of ethylene and 1-octene mediated
by CGCTiMe2, the PNB-based catalytic systems exhibit approximately twice the activity of
the B(C6F5)3-based systems.
In tr od u ction
MAO/catalyst precursor ratios, in the range 102-104:1,
are typically necessary for acceptable polymerization
activity. In contrast,tris(perfluorophenyl)borane,B(C6F5)3
(I), undergoes reaction with metallocene dimethyls in
1:1 catalyst:cocatalyst ratios to form highly active,
structurally characterizable catalytic species.3 Recently,
Cocatalysts for homogeneous metallocene Ziegler-
Natta olefin polymerization are of great current interest
for both technological and fundamental scientific rea-
sons.1 Cocatalysts such as methylaluminoxane (MAO)2
react with metallocenes to generate highly active “cat-
ionic” olefin polymerization catalysts. However, large
(1) For recent reviews, see: (a) Kaminsky, W.; Arndt, M. Adv. Polym.
Sci. 1997, 127, 144-187. (b) Bochmann, M. J . Chem. Soc., Dalton
Trans. 1996, 255-270. (c) Brintzinger, H.-H.; Fischer, D.; Mu¨lhaupt,
R.; Rieger, B.; Waymouth, R. M. Angew. Chem., Int. Ed. Engl. 1995,
34, 1143-1170. (d) Soga, K., Terano, M., Eds. Catalyst Design for
Tailor-Made Polyolefins; Elsevier: Tokyo, 1994. (e) Mo¨hring, P. C.;
Coville, N. J . J . Organomet. Chem. 1994, 479, 1-29. (f) Marks, T. J .
Acc. Chem. Res. 1992, 25, 57-65. (g) J ordan, R. F. Adv. Organomet.
Chem. 1991, 32, 325-387. (h) Quirk, R. P., Ed. Transition Metal
Catalyzed Polymerizations; Cambridge University Press: Cambridge,
1988. (i) Kaminsky, W., Sinn, H., Eds. Transition Metals and Orga-
nometallics for Catalysts for Olefin Polymerizations; Springer: New
York, 1988.
a second strong organo-Lewis acid, the sterically en-
cumbered perfluoroarylborane, tris(2,2′,2′′-perfluorobi-
(2) (a) For recent discussions of the properties of MAO, see: Reddy,
S. S.; Sivaram, S. Prog. Polym. Sci. 1995, 20, 309-367. (b) Harlan, C.
J .; Bott, S. G.; Barron, A. R. J . Am. Chem. Soc. 1995, 117, 6465-6474.
(c) Sishta, C.; Hathorn, R.; Marks, T. J . J . Am. Chem. Soc. 1992, 114,
1112-1114. (d) Pasynkiewicz, S. Polyhedron 1990, 9, 429-453.
S0276-7333(98)00229-5 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 08/08/1998

New Organo-Lewis Acids
Organometallics, Vol. 17, No. 18, 1998 3997
F igu r e 1. Molecular structures of B(C6F5)3, PBB, and PNB computed with the AM1 model Hamiltonian.
phenyl)borane (PBB, II),4 was synthesized in our labo-
ratory. PBB generates cationic species with generally
higher catalytic activities for olefin polymerizations and
copolymerizations than does B(C6F5)3. However, in the
case of group 4 metallocene dimethyls, PBB preferen-
tially affords cationic dinuclear complexes such as [Cp2-
ZrMe(µ-Me)MeZrCp2]+ at room temperature (reflecting
the weaker coordinative tendencies of MePBB- versus
MeB(C6F5)3-), even with excess PBB and long reaction
times.4 Monomeric species can only be generated in situ
at higher temperatures. The activation of metallocene
dimethyls with PBB is also sluggish; for example, 1 h
is required to completely activate rac-Me2Si(Ind)2ZrMe2
in mmol toluene solution. For these reasons, it would
be of great interest to investigate the properties of other
sterically and electronically modified perfluoroarylbo-
ranes. Considering that the perfluoronaphthyl group
is bulkier and potentially more strongly electron with-
drawing than perfluorophenyl, we undertook a synthetic
investigation of the properties of a perfluoronaphth-
ylborane. We report here the synthesis, reactivity, and
polymerization catalytic properties of the new strong
organo-Lewis acid tris(â-perfluoronaphthyl)borane (PNB,
III) and demonstrate that it is an excellent cocatalyst
for metallocene-mediated ethylene polymerization. The
marked dimensional/shape differences between B(C6F5)3,
PBB, and PNB can be appreciated from the computed
geometries shown in Figure 1. These geometries were
optimized using the AM1 model Hamiltonian, as incor-
porated in the Gaussian 94 package, with no symmetry
constraints.
dual-manifold Schlenk line or interfaced to a high-vacuum line
(10-5 Torr), or in a nitrogen-filled vacuum atmospheres glove-
box with a high capacity recirculator (<1 ppm O2). Argon,
ethylene, and propylene (Matheson, polymerization grade)
were purified by passage through a supported MnO oxygen-
removal column and an activated Davison 4A molecular sieve
column. Ether solvents were purified by distillation from Na/K
alloy/benzophenone ketyl. Hydrocarbon solvents were distilled
under nitrogen from Na/K alloy. All solvents for high-vacuum
line manipulations were stored in vacuo over Na/K alloy in
Telflon-valved bulbs. Deuterated solvents obtained from
Cambridge Isotope Laboratories (all g99 atom % D) were
freeze-pump-thaw degassed, dried over Na/K alloy, and
stored in resealable flasks. Other nonhalogenated solvents
were dried over Na/K alloy, and halogenated solvents were
distilled from P2O5 and stored over activated Davison 4A
molecular sieves. The comonomer 1-hexene (Aldrich) was
dried over Na/K and vacuum-transferred into a storage tube
containing activated 4A molecular sieves. CH3CN (Aldrich)
was dried over CaH2 and then over activated 4A molecular
sieves. CuBr2, BCl3 (1.0 M in hexane), and nBuLi (1.6 M in
hexanes) were purchased from Aldrich and used as received.
Octafluoronaphthalene was purchased from Oakwood Prod-
ucts, Inc., and used without further purification. â-Perfluo-
ronaphthylhydrazine,5 B(C6F5)3,6 Me2Si(C5Me4)(tBuN)TiMe2
(CGCTiMe2),7 CGCZrMe2,7 rac-Me2Si(Ind)2ZrMe2,8 Cp2ZrMe2,9
10
and Cp′′2ZrMe2 (Cp′′ ) 1,2-Me2Cp) were prepared according
to literature procedures.
P h ysica l a n d An a lytica l Mea su r em en ts. NMR spectra
were recorded on either Varian VXR 300 (FT 300 MHz, 1H;
1
75 MHz, 13C), VXR 400 (FT 400 MHz, H; 100 MHz, 13C; 377
1
MHz, 19F), or Gemini-300 (FT 300 MHz, H; 75 MHz, 13C; 282
1
MHz, 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). Elemental analyses were performed
by Oneida Research Services, Inc., Whitesboro, NY, or by
Exp er im en ta l Section
Ma ter ia ls a n d Meth od s. All manipulations of air-sensi-
tive materials were performed with rigorous exclusion of
oxygen and moisture in flamed Schlenk-type glassware on a
(5) Gething, B.; Patrick, C. R.; Tatlow, J . C. J . Chem. Soc. 1962,
36, 186-190.
(3) (a) Yang, X.; Stern, C. L.; Marks, T. J . J . Am. Chem. Soc. 1991,
113, 3623-3625. (b) Ewen, J . A.; Elder, M. J . Chem. Abstr. 1991, 115,
136998g. (c) Yang, X.; Stern, C. L.; Marks, T. J . J . Am. Chem. Soc.
1994, 116, 10015-10031. (d) Gillis, D. J .; Tudoret, M.-J .; Baird, M. C.
J . Am. Chem. Soc. 1993, 115, 2543-2545. (e) Pellecchia, C.; Pappa-
lardo, D.; Oliva, L.; Zambelli, A. J . Am. Chem. Soc. 1995, 117, 6593-
6594. (f) Wu, Z.; J ordan, R. F.; Petersen, J . L. J . Am. Chem. Soc. 1995,
117, 5867-5868. (g) Bochmann, M.; Lancaster, S. J .; Hursthouse, M.
B.; Malik, K. M. A. Organometallics 1994, 13, 2235-2243. (h) Temme,
B.; Erker, G.; Karl, J .; Luftmann, H.; Fro¨hlich, R.; Kotila, S. Angew.
Chem., Int. Ed. Engl. 1995, 34, 1755-1757. (i) Sun, Y.; Spence, R. E.
v. H.; Piers, W. E.; Parvez, M.; Yap, G. P. A. J . Am. Chem. Soc. 1997,
119, 5132-5143.
(6) Massey, A. G.; Park, A. J . J . Organomet. Chem. 1964, 2, 245-
250.
(7) (a) Fu, P.-F.; Wilson, D. J .; Rudolph, P. R.; Stern, C. L.; Marks,
T. J . Submitted for publication. (b) Canich, J . M.; Hlatky, G. G.; Turner,
H. W. PCT Appl. WO 92-00333, 1992. Canich, J . M. Eur. Patent Appl.
EP 420 436-A1, 1991 (Exxon Chemical Co.). (c) Stevens, J . C.; Timmers,
F. J .; Wilson, D. R.; Schmidt, G. F.; Nickias, P. N.; Rosen, R. K.; Knight,
G. W.; Lai, S. Eur. Patent Appl. EP 416 815-A2, 1991 (Dow Chemical
Co.).
(8) (a) Herrmann, W. A.; Rohrmann, J .; Herdtweck, E.; Spaleck, W.;
Winter, A. Angew. Chem., Int. Ed. Engl. 1989, 28, 1511-1512. (b)
Herfert, N.; Fink, G. Makromol. Chem. Rapid Commun. 1993, 14, 91-
96. (c) Christopher, J . N.; Diamond, G. M.; J ordan, R. F.; Petersen, J .
L. Organometallics 1996, 15, 4038-4044.
(4) (a) Chen, Y.-X.; Stern, C. L.; Yang, S.; Marks, T. J . J . Am. Chem.
Soc. 1996, 118, 12451-12452. (b) Chen, Y.-X.; Metz, M. V.; Li, L.; Stern,
C. L.; Marks, T. J . J . Am. Chem. Soc. 1998, 120, 6287-6305.
(9) Samuel, E.; Rausch, M. D. J . Am. Chem. Soc. 1973, 95, 6263.
(10) Smith, G. M. Ph.D. Thesis, Northwestern University, 1985.

3998 Organometallics, Vol. 17, No. 18, 1998
Li and Marks
Midwest Microlab, Indianapolis, IN. 13C NMR assays of
polymer microstructure were conducted in C2D2Cl4 at 120 °C.
Signals were assigned according to the literature for polypro-
pylene11 and ethylene/1-hexene copolymers,12 respectively.
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. Solution IR spectra were recorded
in toluene solution with a Bio-Rad FTS-60 instrument. Sample
solutions were contained in anaerobically capped, single-
crystal NaCl cavity cells (Wilmad Glass Company, Inc., Buena,
NJ ) which were filled in the glovebox and transported to the
FT-IR spectrometer in a nitrogen-filled plastic bag.
MHz): δ 0.596 (s, 3 H, CH3CN). 13C NMR (C7D8, 23 °C,
100.574 MHz): δ -0.843 (CH3CN). 19F NMR (C6D6, 23 °C,
282.330 MHz): δ -110.95 (dd, 3 F, F-1, 4J F1-F8 ) 76 Hz, 5J F1-F4
3
) 18 Hz), -130.01 (d, 3 F, F-3, J F3-F4 ) 17 Hz), -145.15 (dt,
4
5
3 F, F-8, J F1-F8 ) 76 Hz, J F8-F5 ) 3J F8-F7 ) 18 Hz), -146.91
4
3
(dt, 3 F, F-5, J F5-F4 ) 55 Hz, J F5-F6
)
5J F8-F5 ) 17 Hz),
4
3
5
-151.51 (dt, 3 F, F-4, J F4-F5 ) 58 Hz, J F4-F3 ) J F1-F4 ) 18
3
Hz), -154.79 (t, br, 3 F, F-6, J F6-F7
)
3J F6-F5 ) 18 Hz),
3
3
-157.05 (t, br, 3 F, F-7, J F7-F8 ) J F6-F7 ) 17 Hz). ν(CN) )
2365.3 cm-1 (41.3 mM toluene solution). Anal. Calcd for
C
32H3BF21N: C, 47.38; H, 0.37; N, 1.72. Found: C, 47.13; H,
0.33; N, 1.72.
Syn th esis of th e Aceton itr ile Ad d u ct of B(C6F 5)3 (CH3-
CNB(C6F 5)3). B(C6F5)3 (200 mg, 0.391 mmol) was loaded into
a 25 mL reaction flask in the glovebox. Toluene (10 mL) and
CH3CN (0.4 mL) were condensed in at -78 °C on the high-
vacuum line. The solution was next stirred at room temper-
ature for 1 h, and all the volatiles were removed by vacuum
to give white solid. The white solid was dried under vacuum
(10-5 Torr) for 4 h at room temperature. Yield: 190 mg (89%).
Spectroscopic data for (C6F5)3BNCCH3 are as follows. 1H NMR
(C6D6, 23 °C, 399.941 MHz): δ 0.242 (s, 3 H, CH3CN). 13C
NMR (C6D6, 23 °C, 100.574 MHz): δ -0.908 (CH3CN). 19F
NMR (C6D6, 23 °C, 282.330 MHz): δ -134.74 (multi, 6 F, o-F),
-155.21 (t, 3 F, p-F, 3J F-F ) 21 Hz), -163.12 (multi, 6 F, m-F).
ν(CN) ) 2366.5 cm-1 (46.9 mM toluene solution). Anal. Calcd
for C20H3BF15N: C, 43.44; H, 0.55; N, 2.53. Found: C, 43.55;
H, 0.57; N, 2.49.
Va r ia ble-Tem p er a tu r e Stu d y of th e Equ ilibr iu m P N-
BNCCH3 + B(C6F 5)3 h (C6F 5)3BNCCH3 + P NB. PN-
BNCCH3 (8.11 mg, 0.010 mmol) and B(C6F5)3 (5.12 mg, 0.010
mmol) were loaded into a J -Young NMR tube in the glovebox,
and 0.7 mL C7H8 was added to the NMR tube. The solution
turned yellow immediately, indicating the formation of free
PNB. Variable-temperature NMR studies (-16.3 °C to +41.7
°C) were carried out on the Gemini 300 or VXR 400 NMR
instrument with 3 s relaxation delay times. A separate
experiment starting with (C6F5)3BNCCH3 (5.53 mg, 0.010
mmol) and PNB (7.70 mg, 0.010 mmol) was also carried out
under similar conditions.
Syn th esis of2-Br om oh eptaflu or on aph th alen e (C10F7Br ).
This is a modified version of the literature procedure.13
â-Perfluoronaphthylhydrazine,5 copper(II) bromide, and hy-
drobromic acid were heated together under reflux for 1 h. The
mixture was then filtered after the solution had cooled to room
temperature. The residual solid was washed with water and
then extracted with CH2Cl2. The CH2Cl2 extract was next
dried over MgSO4, filtered, and evaporated to leave a brown
solid. Sublimation afforded pure 2-bromoheptafluoronaph-
thalene. Yield: 58%. The 19F NMR spectrum is identical to
that in the literature.14
Syn th esis ofTr is(â-per flu or on aph th yl)bor an e (B(C10F7)3;
P NB). In a 250 mL flask, 2-bromoheptafluoronaphthalene
(3.0 g, 9.0 mmol) was dissolved in 85 mL dry pentane. The
solution was stirred at -30 °C for 10 min, and then 5.63 mL
of n-butyllithium (1.6 M in hexanes, 9.0 mmol) was added
dropwise via syringe over the course of 1 h. A white precipitate
formed immediately. The solution was stirred between -40
and -30 °C for 80 min after the addition was complete, and
then 3.0 mL of BCl3 (1.0 M in hexanes, 3.0 mmol) was quickly
added at -40 °C. The solution immediately turned yellow and
was allowed to warm slowly to room temperature overnight.
All the volatiles were then removed in vacuo to afford a yellow
solid and LiCl. Repeated sublimation at 150 °C (0.05 Torr)
removed yellow, sticky byproducts. Next, sublimation at 220
°C (0.05 Torr) for 3 h gave analytically pure PNB as a pale-
yellow solid. Yield: 0.60 g (26%). Sublimation at 150 °C under
high vacuum (10-5 Torr) gave similar results. Spectroscopic
and analytical data for PNB are as follows. 19F NMR (C6D6,
In Situ Gen er a tion of r a c-Me2Si(In d )2Zr Me+MeP NB-
(1). rac-Me2Si(Ind)2ZrMe2 (5.0 mg, 0.013 mmol) and PNB (10.1
mg, 0.0130 mmol) were dissolved in C6D6 in a J -Young NMR
tube. Reaction occurred immediately to give rac-Me2Si-
(Ind)2ZrMe+MePNB-, which decomposes slowly at room tem-
perature. Spectroscopic data for 1 are as follows. 1H NMR
(C6D6, 23 °C, 399.941 MHz): δ 7.72-7.76 (1 H, Ind), 7.03-
4
23 °C, 282.330 MHz): δ -102.97 (dd, 3 F, F-1, J F1-F8 ) 73
5
4
Hz, J F1-F4 ) 18 Hz), -129.66 (d, 3 F, F-3, J F3-F4 ) 18 Hz),
4
3
5
-142.04 (dt, 3 F, F-8, J F8-F1 ) 73 Hz, J F8-F7 ) J F8-F5 ) 17
Hz), -145.18 (dt, 3 F, F-5, 4J F5-F4 ) 58 Hz, 3J F5-F6 ) 5J F8-F5
17 Hz), -149.33 (dt, 3 F, F-4, 4J F4-F5 ) 58 Hz, 3J F4-F3 ) 5J F1-F4
) 18 Hz), -149.60 (t, br, 3 F, F-6, J F6-F7 ) J F6-F5 ) 18 Hz),
-155.09 (t, br, 3 F, F-7, 3J F7-F8 ) 3J F6-F7 ) 17 Hz). MS: parent
ion at m/e 770. Anal. Calcd for C30BF21: C, 46.79; H, 0.00;
N, 0.00. Found: C, 46.91, H, 0.07, N, 0.00.
)
3
3
3
7.18 (3 H, Ind), 6.63-6.75 (3 H, Ind), 6.52 (t, 1 H, J H-H ) 4
Hz, Ind), 6.22-6.28 (m, 1 H, Ind), 6.11-6.16 (m, 1 H, Ind),
5.94-5.96 (m, 1 H, Ind), 5.05 (d, 1 H, 3J H-H ) 4 Hz, Ind), 0.425
(s, 3 H, Me2Si), 0.248 (s, 3 H, Me2Si), -0.011 (s, br, 3 H, B-CH3),
-0.355 (s, 3 H, Zr-CH3). 13C NMR (C6D6, 23 °C, 100.577
MHz): δ 132.86 (Ind), 132.38 (Ind), 128.12 (Ind), 127.89 (Ind),
127.34 (Ind), 126.85 (Ind), 126.51 (Ind), 126.47 (Ind), 125.19
(Ind), 125.02 (Ind), 123.68 (Ind), 121.22 (Ind), 117.45 (Ind),
116.44 (Ind), 116.24 (Ind), 111.58 (Ind), 89.81 (Ind), 88.23 (Ind),
49.99 (Zr-Me), 22.51 (B-Me), -2.45 (SiMe2), -3.08 (SiMe2).
19F NMR (C6D6, 23 °C, 282.330 MHz): δ -110.21 (d, 3 F, F-1,
4J F1-F8 ) 76 Hz), -127.24 (br, 3 F, F-3), -145.99 (dt, 3 F, F-8,
Syn th esis of th e Aceton itr ile Addu ct of P NB (CH3CNB-
(C10F 7)3). PNB (50 mg, 0.065 mmol) was loaded into a 25 mL
reaction flask in the glovebox. Pentane (5 mL) and CH3CN
(0.3 mL) were then condensed in at -78 °C on the high-vacuum
line, and the solution was stirred at room temperature for 3
h. The white precipitate was collected by filtration, washed
with pentane, and dried under vacuum (10-5 Torr) for 4 h at
room temperature. Yield: 40 mg (76%). Spectroscopic data
for PNBNCCH3 are as follows. 1H NMR (C7D8, 23 °C, 399.941
3
5
4J F8-F1 ) 73 Hz, J F8-F7 ) J F8-F5 ) 17 Hz), -147.73 (dt, 3 F,
4
3
5
F-5, J F5-F4 ) 55 Hz, J F5-F6 ) J F5-F8 ) 17 Hz), -152.93 (dt,
(11) (a) Pellecchia, C.; Pappalardo, D.; D’Arco, M.; Zambelli, A.
Macromolecules 1996, 29, 1158. (b) Miyatake, T.; Miaunuma, K.;
Kakugo, M. Macromol. Symp. 1993, 66, 203. (c) Kakugo, M.; Miyatake,
T.; Miaunuma, K. Stud. Surf. Sci. Catal. 1990, 56, 517. (d) Longo, P.;
Grassi, A. Makromol. Chem. 1990, 191, 2387. (e) Randall, J . C. J .
Polym. Sci., Part B: Polym. Phys. 1975, 13, 889.
(12) (a) Soga, K.; Uozumi, T.; Park, J . R. Makromol. Chem. 1990,
191, 2853. (b) Hsich, E. T.; Randall, J . C. Macromolecules 1982, 15,
1402.
(13) Brooke, G. M.; Meara, J . M. J . Fluorine Chem. 1990, 50, 229-
242.
(14) Burdon, J .; Gill, H. S.; Parsons, I. W. J . Chem. Soc., Perkin
Trans. 1 1980, 2494-2496.
3 F, F-4, J F4-F5 ) 55 Hz, J F4-F3 ) 5J F4-F1 ) 18 Hz), -156.95
4
3
(t, br, 3 F, F-6, J F6-F7 ) 3J F6-F5 ) 18 Hz), -158.38 (t, br, 3 F,
3
3
3
F-7, J F7-F8 ) J F7-F6 ) 18 Hz).
Syn th esis of CGCZr Me+MeP NB- (2). CGCZrMe2 (100
mg, 0.270 mmol) and PNB (207.7 mg, 0.270 mmol) were loaded
into a 25 mL reaction flask in the glovebox. On the high-
vacuum line, C6H6 (10 mL) was condensed in at -78 °C. The
solution was then stirred at room temperature for 1 h, and all
the volatiles were removed under high vacuum to give a yellow
solid. Pentane was condensed in to wash the solid twice, and

New Organo-Lewis Acids
Organometallics, Vol. 17, No. 18, 1998 3999
the yellow solid was dried under vacuum (10-5 Torr) for 4 h
at room temperature. Yield: 89 mg (61%). The spectroscopic
data for 2 are as follows. 1H NMR (C6D6, 23 °C, 299.910
MHz): δ 1.81 (s, 3 H, C5Me4), 1.77 (s, 3 H, C5Me4), 1.64 (s, 3
H, C5Me4), 1.58 (s, 3 H, C5Me4), 1.43(s, br, 3 H, B-CH3), 1.13
(s, 9 H, NCMe3), 0.47 (s, 3 H, Zr-Me), 0.28 (s, 3 H, SiMe2),
0.19 (s, 3 H, SiMe2). 13C NMR (C6D6, 23 °C, 75.462 MHz): δ
150.38-155.63 (C10F7), 136.56-142.86 (C10F7), 110.90 (br,
(C6D6, 23 °C, 299.910 MHz): δ 5.57 (s,10 H, C5H5), 0.57 (s, br,
3 H, B-CH3), 0.43 (s, 3 H, Zr-CH3).13C NMR (C6D6, 23 °C,
75.416 MHz): δ 114.28 (C5H5), 40.90 (Zr-CH3), 27.23 (B-CH3).
19F NMR (C6D6, 23 °C, 282.330 MHz): δ -110.71 (d, 3 F, F-1,
4J F1-F8 ) 76 Hz), -127.59 (br, 3 F, F-3), -146.30 (d, 3 F, F-8,
4
4J F8-F1 ) 76 Hz), -147.55 (d, 3 F, F-5, J F5-F4 ) 55 Hz),
4
-152.46 (d, 3 F, F-4, J F4-F5 ) 55 Hz), -156.90 (br, 3 F, F-6),
-158.33 (br, 3 F, F-7). [Cp2ZrMe(µ-F)MeZrCp2]+[MePNB]-
(9): 1H NMR (C6D6, 23 °C, 299.910 MHz): δ 5.60 (s, 20 H,
C
10F7), 108.31 (br, C10F7), 134.40 (C5Me4), 133.67 (C5Me4),
133.19 (C5Me4), 129.46 (C5Me4), 102.24 (C5Me4), 57.89 (NC-
Me3), 44.21 (Zr-CH3), 33.07 (NCMe3), 15.10 (C5Me4), 12.85
(C5Me4), 11.42 (C5Me4), 10.69 (C5Me4), 5.58 (SiMe2), 5.12
(SiMe2). 19F NMR (C6D6, 23 °C, 282.330 MHz): δ -111.05 (br,
C5H5), 1.56 (s, br, 3 H, B-CH3), 0.26 (d, 6 H, Zr-CH3, 3J H-F
)
2.4 Hz).13C NMR (C6D6, 23 °C, 75.416 MHz): δ 114.80 (C5H5),
39.03 (Zr-CH3), 26.07 (B-CH3). 19F NMR (C6D6, 23 °C,
282.330 MHz): δ -88.32 (s, 1 F, Zr-F-Zr), -108.58 (dd, 3 F,
4
4
3 F, F-1), -127.36 (br, 3 F, F-3), -146.01 (dt, 3 F, F-8, J F8-F1
F-1, J F1-F8 ) 73 Hz), -124.24 (d, br, 3 F, F-3), -146.03 (dt, 3
3
5
4
4
) 76 Hz, J F8-F7 ) J F8-F5 ) 17 Hz), -147.82 (br, 3 F, F-5),
-152.51 (br, 3 F, F-4), -157.26 (br, 3 F, F-6), -158.64 (br, 3
F, F-7). Anal. Calcd for C48H33BF21NSiZr: C, 49.48; H, 2.92.
Found: C, 49.68, H, 3.23.
F, F-8, J F8-F1 ) 76 Hz), -149.79 (dt, 3 F, F-5, J F5-F4 ) 55
4
Hz), -155.23 (dt, 3 F, F-4, J F4-F5 ) 55 Hz), -160.50 (t, br, 3
F, F-6), -161.45 (t, br, 3 F, F-7).
In Sit u Gen er a t ion of Cp 2Zr Me(µ-Me)MeZr Cp 2+Me-
Syn th esis of CGCTiMe+MeP NB- (3). CGCTiMe2 (40 mg,
0.122 mmol) and PNB (95 mg, 0.122 mmol) were loaded into
a 25 mL reaction flask in the glovebox. On the vacuum line,
C6H6 (10 mL) was condensed in at -78 °C, and the solution
was stirred at room temperature for 1 h. Next, all the volatiles
were removed under high vacuum to give a yellow solid.
Pentane was condensed in to wash the solid twice, and the
yellow solid was dried under vacuum (10-5 Torr) for 4 h at
room temperature. Yield: 53 mg (40%). The spectroscopic
data for 3 are as follows. 1H NMR (C6D6, 23 °C, 299.910
MHz): δ 1.847 (s, 3 H, C5Me4), 1.658 (s, 3 H, C5Me4), 1.610 (s,
3 H, C5Me4), 1.466 (s, 3 H, C5Me4), 1.085 (s, 9 H, NCMe3), 1.60
(br, 6 H, Ti-Me, B-Me), 0.336 (s, 3 H, SiMe2), 0.179 (s, 3 H,
SiMe2). 13C NMR (C6D6, 23 °C, 75.462 MHz): δ 141.21 (C5-
Me4), 139.17 (d, C5Me4, J C-F ) 2.4 Hz), 138.68 (C5Me4), 136.21
(C5Me4), 105.54 (C5Me4), 66.67 (Ti-CH3), 63.40 (NCMe3), 33.03
(NCMe3), 16.07 (C5Me4), 13.91 (C5Me4), 12.04 (C5Me4), 11.58
(C5Me4), 5.13 (SiMe2), 4.54 (SiMe2). 19F NMR (C6D6, 23 °C,
P NB- (7). Cp2ZrMe2 (7.5 mg, 0.030 mmol) and PNB (11.6 mg,
0.015 mmol) were dissolved in C6D6 in a J -Young NMR tube.
+
Reaction occurred immediately to give Cp2ZrMe(µ-Me)MeZrCp2
-
MePNB- (7) and a byproduct, the µ-F bridged dimeric cationic
species (9) in a ratio of 5:1. The spectroscopic data for 7 are
as follows. 1H NMR (C6D6, 23 °C, 299.910 MHz): δ 5.65 (s,
20 H, C5H5), 1.56 (s, br, 3 H, B-CH3), -0.07 (s, 6 H, Zr-CH3),
-1.15 (s, 3 H, Zr-CH3-Zr).13C NMR (C6D6, 23 °C, 75.416
MHz): δ 113.26 (C5H5), 39.26 (Zr-CH3), 26.07 (B-CH3), 22.29-
(Zr-CH3-Zr). 19F NMR (C6D6, 23 °C, 282.330 MHz):
δ
4
-108.58 (d, 3 F, F-1, J F1-F8 ) 73 Hz), -124.24 (br, 3 F, F-3),
4
-146.03 (d, 3 F, F-8, J F8-F1 ) 76 Hz), -149.79 (d, 3 F, F-5,
4
4J F5-F4 ) 55 Hz), -155.23 (d, 3 F, F-4, J F4-F5 ) 55 Hz),
-160.50 (br, 3 F, F-6), -161.45 (br, 3 F, F-7).
In Situ Gen er a tion of Cp ′′2Zr Me+MeP NB- (6). Cp′′2-
ZrMe2 (4.6 mg, 0.015 mmol) and PNB (11.6 mg, 0.015 mmol)
were dissolved in C6D6 in a J -Young NMR tube. Reaction
occurred immediately to give Cp′′2ZrMe+MePNB- (6) and a
byproduct, the µ-F bridged dimeric cationic species Cp′′2ZrMe-
(µ-F)MeZrCp′′2+MePNB- (10) in a ratio of 7:1. The spectro-
scopic data for 6 and 10 are as follows. Cp′′2ZrMe+MePNB-
(6). 1H NMR (C6D6, 23 °C, 299.910 MHz): δ 5.82 (t, 2 H, C5H3-
4
282.330 MHz): δ -110.42 (d, br, 3 F, F-1, J F1-F8 ) 76 Hz),
-127.13 (br, 3 F, F-3), -145.94 (multi, 3 F, F-8), -148.77
(multi, 3 F, F-5), -152.63 (multi, 3 F, F-4), -157.14 (t, 3 F,
3
3
F-6, J F6-F7 ) 3J F6-F5 ) 18 Hz), -158.58 (t, 3 F, F-7, J F7-F8
)
3J F6-F7 ) 18 Hz). Anal. Calcd for C48H33BF21NSiTi: C, 51.43;
H, 3.03. Found: C, 51.48, H, 3.13.
3
3
Me2, J H-H ) 2.6 Hz), 5.47 (t, 2 H, C5H3Me2, J H-H ) 3.0 Hz),
4.88 (t, 2 H, C5H3Me2, 3J H-H ) 2.7 Hz), 1.68 (s, 6 H, C5H3Me2),
1.24 (s, 6 H, C5H3Me2), 0.44 (s, br, 3 H, B-CH3), 0.20 (s, 3 H,
Zr-CH3). 13C NMR (C6D6, 23 °C, 100.577 MHz): δ 150.67-
155.07 (C10F7), 137.16-142.55 (C10F7), 116.37 (C5H3Me2),
112.27 (C5H3Me2), 110.84 (br, 1C, C10F7), 108.45 (br, 1C, C10F7),
106.99 (C5H3Me2), 44.82 (Zr-CH3), 23.03 (B-CH3), 12.63
(C5H3Me2). 19F NMR (C6D6, 23 °C, 282.330 MHz): δ -110.40
In Situ Gen er a tion of [(CGCTiMe)2(µ-Me)]+[MeP NB]-
(4). CGCTiMe2 (9.8 mg, 0.030 mmol) and PNB (11.6 mg, 0.015
mmol) were dissolved in the C6D6 in a J -Young NMR tube.
The reaction occurred immediately to give 4. No µ-F bridged
dimeric cationic species could be detected. Spectroscopic data
for 4 are as follows. 1H NMR (C6D6, 23 °C, 299.910 MHz): δ
1.898 (s, 6 H, C5Me4), 1.574 (s, 6 H, C5Me4), 1.547 (s, 6 H,
C5Me4), 1.524 (s, 6 H, C5Me4), 1.114 (s, 9 H, NCMe3), 0.458 (s,
6 H, Ti-Me), 0.364 (br, 3 H, B-Me), 0.337 (s, 6 H, SiMe2),
0.284 (s, 6 H, SiMe2), -0.828 (s, 3 H, Ti-Me-Ti). 13C NMR
(C6D6, 23 °C, 75.462 MHz): δ 142.33 (C5Me4), 137.24 (C5Me4),
135.81 (C5Me4), 134.34 (C5Me4), 102.41 (C5Me4), 64.82 (Ti-
CH3), 61.59 (NCMe3), 44.50 (Ti-CH3-Ti), 33.70 (NCMe3),
15.67 (C5Me4), 14.57 (C5Me4), 11.90 (C5Me4), 11.65 (C5Me4), 5.44
(SiMe2), 4.26 (SiMe2). 19F NMR (C6D6, 23 °C, 282.330 MHz):
4
5
(dd, 3 F, F-1, J F1-F8 ) 73 Hz, J F1-F4 ) 16 Hz), -127.22 (br,
4
3
3 F, F-3), -146.28 (dt, 3 F, F-8, J F8-F1 ) 76 Hz, J F8-F7
)
5J F8-F5 ) 17 Hz), -146.77 (dt, 3 F, F-5, 4J F5-F4 ) 55 Hz, 3J F5-F6
4
)
5J F8-F5 ) 17 Hz), -152.59 (dt, 3 F, F-4, J F4-F5 ) 55 Hz,
3J F4-F3 ) J F1-F4 ) 18 Hz), -157.12 (t, br, 3 F, F-6, J F6-F7
)
)
5
3
3J F5-F6 ) 18 Hz), -158.53 (t, br, 3 F, F-7, J F7-F8 ) J F7-F6
3
3
18 Hz). Cp′′2ZrMe(µ-F)MeZrCp′′2+MePNB- (10): 1H NMR
3
(C6D6, 23 °C, 299.910 MHz): δ 5.61 (td, 4 H, C5H3Me2, J H-H
) 2.7 Hz, J H-F ) 1.1 Hz), 5.28 (dd, 4 H, C5H3Me2, J H-H
3
3
)
4
5
3
δ -108.29 (dd, 3 F, F-1, J F1-F8 ) 76 Hz, J F1-F4 ) 16 Hz),
3.3 Hz), 5.16 (t, 4 H, C5H3Me2, J H-H ) 2.7 Hz), 1.66 (s, br, 3
H, B-CH3), 1.64 (s, 12 H, C5H3Me2), 1.36 (s, 12 H, C5H3Me2),
0.04 (d, 6 H, Zr-CH3, 3J H-F ) 2.1 Hz). 13C NMR (C6D6, 23 °C,
100.577 MHz): δ 126.10 (C5H3Me2), 117.38 (C5H3Me2), 112.02
(C5H3Me2), 107.73 (C5H3Me2), 42.28 (Zr-CH3), 22.58 (B-CH3),
12.60 (C5H3Me2), 12.42 (C5H3Me2). 19F NMR (C6D6, 23 °C,
282.330 MHz): δ -91.20 (s, 1 F, Zr-F-Zr), -108.42 (dd, 3 F,
4
-123.18 (br, 3 F, F-3), -145.94 (dt, 3 F, F-8, J F8-F1 ) 73 Hz,
3J F8-F7 ) 5J F8-F5 ) 18 Hz), -149.99 (dt, 3 F, F-5, J F5-F4 ) 55
4
Hz, 3J F5-F6 ) 5J F8-F5 ) 17 Hz), -155.41 (dt, 3 F, F-4, 4J F4-F5
)
55 Hz, J F4-F3 ) 5J F4-F1 ) 18 Hz), -161.32 (t, 3 F, F-6, J F6-F7
) 3J F6-F5 ) 18 Hz), -162.19 (t, 3 F, F-7, 3J F7-F8 ) 3J F6-F7 ) 18
Hz).
3
3
In Situ Gen er a tion of Cp 2Zr Me+MeP NB- (5). Cp2ZrMe2
(3.8 mg, 0.015 mmol) and PNB (11.6 mg, 0.015 mmol) were
dissolved in C6D6 in a J -Young NMR tube. Reaction occurred
immediately to give Cp2ZrMe+MePNB- (5) and a byproduct,
the µ-F bridged dimeric cationic species [Cp2ZrMe(µ-F)-
MeZrCp2]+MePNB- (9) in a ratio of 5:1. The spectroscopic data
for 5 and 9 are as follows. Cp2ZrMe+MePNB- (5). 1H NMR
F-1, J F1-F8 ) 73 Hz, J F1-F4 ) 16 Hz), -123.76 (d, br, 3 F,
3 4
4
5
F-3, J F3-F4 ) 16 Hz), -145.95 (dt, 3 F, F-8, J F8-F1 ) 76 Hz,
3J F8-F7 ) 5J F8-F5 ) 17 Hz), -149.89 (dt, 3 F, F-5, J F5-F4 ) 55
4
Hz, 3J F5-F6 ) 5J F8-F5 ) 17 Hz), -155.34 (dt, 3 F, F-4, 4J F4-F5
)
3
55 Hz, J F4-F3
)
5J F1-F4 ) 19 Hz), -160.96 (t, br, 3 F, F-6,
3
3J F6-F7 ) J F6-F5 ) 18 Hz), -161.87 (t, br, 3 F, F-7, J F7-F8
)
5
3J F7-F6 ) 18 Hz).

4000 Organometallics, Vol. 17, No. 18, 1998
Li and Marks
+
In Sit u Gen er a t ion of Cp ′′2Zr Me(µ-Me)MeZr Cp ′′2
-
Sch em e 1
MeP NB- (8). Cp′′2ZrMe2 (9.2 mg, 0.030 mmol) and PNB (11.6
mg, 0.015 mmol) were dissolved in C6D6 in a J -Young NMR
tube. Reaction occurred immediately to give [Cp′′2ZrMe(µ-Me)-
MeZrCp′′2]+MePNB- (8) and the byproduct, a µ-F bridged
dimeric cationic species (10) in a ratio of 5:1. The spectroscopic
data for 8 are as follows. 1H NMR (C6D6, 23 °C, 299.910
3
MHz): δ 5.44 (t, 4 H, C5H3Me2, J H-H ) 2.7 Hz), 5.40 (t, 4 H,
3
3
C5H3Me2, J H-H ) 3.3 Hz), 5.11 (t, 4 H, C5H3Me2, J H-H ) 2.7
Hz), 1.66 (s, 12 H, C5H3Me2), 1.45 (s, 12 H, C5H3Me2), 1.65 (s,
br, 3 H, B-CH3), -0.32 (s, 6 H, Zr-CH3), -1.59 (s, 3 H, Zr-
CH3-Zr). 13C NMR (C6D6, 23 °C, 100.577 MHz): δ 126.01
(C5H3Me2), 125.63 (C5H3Me2), 113.92 (C5H3Me2), 111.38 (C5H3-
Me2), 106.46 (C5H3Me2), 41.77 (Zr-CH3), 22.58 (B-CH3), 22.34
(Zr-CH3-Zr), 12.93 (C5H3Me2), 12.66 (C5H3Me2). 19F NMR
4
(C6D6, 23 °C, 282.330 MHz): δ -108.42 (dd, 3 F, F-1, J F1-F8
5
3
) 73 Hz, J F1-F4 ) 16 Hz), -123.76 (d, br, 3 F, F-3, J F3-F4
)
16 Hz), -145.95 (dt, 3 F, F-8, 4J F8-F1 ) 76 Hz, 3J F8-F7 ) 5J F8-F5
4
3
) 17 Hz), -149.89 (dt, 3 F, F-5, J F5-F4 ) 55 Hz, J F5-F6
)
5J F5-F8 ) 17 Hz), -155.34 (dt, 3 F, F-4, 4J F4-F5 ) 55 Hz, 3J F4-F3
5
3
3
) J F4-F1 ) 18 Hz), -160.96 (t, br, 3 F, F-6, J F6-F7 ) J F6-F5
3
5
) 18 Hz), -161.87 (t, br, 3 F, F-7, J F7-F8 ) J F7-F8 ) 18 Hz).
Eth ylen e, P r op ylen e P olym er iza tion Exp er im en ts.
This procedure is designed to minimize mass transfer (gas to
solution; catalyst entrainment) and exotherm effects while at
the same time maintaining strictly anaerobic/anhydrous
conditions.3a,c On a high-vacuum line (10-5 Torr), ethylene and
propylene polymerization were carried out in 250 mL round-
bottom three-neck flasks equipped with a large magnetic
stirring bar and a thermocouple probe. In a typical experi-
ment, a measured quantity of dry toluene (and 1-hexene in
the case of ethylene and 1-hexene copolymerization) was
vacuum-transferred into the flask, presaturated under 1.0 atm
of rigorously purified ethylene or propylene (pressure control
using a mercury bubbler), and equilibrated at the desired
reaction temperature using an external bath. The catalytically
active species was freshly generated (within 1.0 min) using a
solution having a 1:1 metallocene/cocatalyst ratio in 1.5 mL
of toluene. The solution of catalyst was then quickly injected
into the rapidly stirred flask using a gastight syringe equipped
with a spraying needle. The temperature of the toluene
solution in representative polymerization experiments was
monitored using a thermocouple (OMEGA Type K thermo-
couple with a model HH21 microprocessor thermometer). The
reaction exotherm temperature rise was invariably less than
5 °C during these polymerizations. After a measured time
interval (short to minimize mass transport and exotherm
effects), the polymerization was quenched by the addition of
15 mL of 2% acidified methanol. Another 30 mL of methanol
was then added, and the polymer was collected by filtration,
washed with methanol, and dried on the high-vacuum line
overnight to a constant weight. Uncertainties in activities
reported in Table 1 are the average of 3 trials.
La r ge-Sca le Ba tch P olym er iza tion s. In a typical po-
lymerization, a 2 L stirred Parr reactor was charged with 740
g of Isopar E solvent and 118 g of 1-octene. Hydrogen was
added for molecular weight control by differential pressure
expansion from a 75 L addition tank at 25 psi. The reactor
was heated to 140 °C and saturated with ethylene at 500 psig.
Then 2.0 µmol each of catalyst and cocatalyst (0.005 M in
toluene) were premixed in the glovebox; the solution was
transferred to a catalyst addition tank and injected into the
reactor. Polymerization conditions were maintained for 15 min
with ethylene on demand. The resulting polymer solutions
were removed from the reactor, and a phenol antioxidant
(Irganox 1010) was added. Polymers were recovered by
removal of solvent in vacuo at 120 °C for 20 h.
F igu r e 2. 19F COSY NMR spectrum of PNB in toluene-
d8.
fluoronaphthylhydrazine using a modified literature
procedure.13 Low-temperature lithium-halogen ex-
n
change using BuLi produced â-perfluoronaphthyllith-
ium, which was then reacted with BCl3 at low temper-
ature to afford, after solvent removal, yellow tris(â-
perfluoronaphthyl)borane (PNB; 1; Scheme 1). The
product was purified by repeated vacuum sublimation.
PNB is an air-sensitive yellow solid that is thermally
stable at room temperature. It exhibits low solubility
in pentane and high solubility in toluene. It was
characterized by standard spectroscopic and analytical
techniques (see Experimental Section for details). At-
tempts to grow crystals of PNB from various solvents
for X-ray diffraction studies were unsuccessful.
Figure 2 shows the 2D NMR (19F-19F) COSY spec-
trum of PNB. There is a characteristically large cou-
pling between peri-fluorines in PNB (4J F8-F1 ) 73 Hz,
4J F5-F4 ) 17 Hz) as in other polyfluoronaphthalenes.14
A strong coupling between para-fluorines (5J F8-F5 ) 17
Hz) is also observed in the spectrum. However, the
coupling between meta-fluorines is too small to resolve.
There is also characteristic weak coupling between F7
and F3.
B. Meta llocen e Ca tion s Gen er a ted fr om P NB.
Metallocene cations are rapidly generated by reaction
of PNB with metallocene dimethyls in aromatic hydro-
carbon solvents (Scheme 2). The reaction of PNB with
bis-Cp types of dimethyl zirconocenes forms either
monomeric cationic species (with a 1:1 reactant ratio)
having the generalized formula L2ZrMe+MePNB- (L )
Cp, 5; Cp′′, 6) or dimeric cationic species (with a 1:2
Resu lts a n d Discu ssion
A. Syn th esis of P NB. The starting material, â-bro-
moheptafluoronaphthalene, was synthesized from â-per-

New Organo-Lewis Acids
Sch em e 2
Organometallics, Vol. 17, No. 18, 1998 4001
CGCZrMe2, and rac-SBIZrMe2, reactions with PNB lead
to clean formation of cationic species, presumably
because the relatively open ancillary ligation promotes
stronger MePNB- coordination to the cation, which may
stabilize the cation-anion pair. All of these cationic
species are somewhat thermally unstable at room
temperature and decompose rapidly at higher temper-
atures. When there is free L2ZrMe2 (L ) Cp, Cp′′)
available in solution, MePNB- and L2ZrMe2 compete for
the electrophilic L2ZrMe+ cations. The formation of
dimeric species 7 and 8 argues that MePNB- is less
coordinating than the neutral Cp2ZrMe2 and Cp′′2ZrMe2
dimethyl complexes. As suggested by the upfield 19F
NMR spectral shifts versus free PNB, the negative
charge of MePNB- is delocalized over both rings of the
perfluoronaphthyl moiety, which is certainly a favorable
property to render the MePNB- anion less coordinating.
The 19F NMR data for the MePNB- anion in both
dimeric complexes 7 and 9 or 8 and 10 are identical,
which supports the very loose contact between the cation
and the anion. In comparing MePNB- to PNB, position
F-6, which is pseudo-para relative to the B position, is
displaced most upfield in 19F NMR relative to the other
fluorine nuclei in MePNB- (e.g., 7.52 ppm upfield in 6
and 11.36 ppm upfield in 8 versus δ F-6 in neutral
PNB). It has been reported in several cases that the
“pseudo-para” site 6 is the most reactive site in hep-
tafluoro-2-naphthyllithium,14 2-methoxyheptafluoronaph-
thalene,16 and 2-methylthioheptafluoronaphthalene.15
This may be a reason PNB-derived cationic metallocene
species are less stable than the B(C6F5)3-derived and
PBB-derived analogues. Thermal decomposition of the
monomeric cationic species (5 or 6) or dimeric cationic
species (7 or 8) at room temperature slowly forms the
corresponding µ-F bridged dimeric cationic species (9
or 10) and other unidentified complexes. Attempts to
grow crystals of PNB-derived cationic species have to
date been unsuccessful. Solutions of these cationic
complexes form oils upon slow cooling or slow diffusion
in of a nonsolvent.
reactant ratio) such as [L2ZrMe(µ-Me)MeZrL2]+MePNB-
(L ) Cp, 7; Cp′′, 8). These cation-anion complexes were
characterized by 1H, 13C, and 19F NMR spectroscopy.
1
The H and 13C NMR spectra of the cationic portions of
5 or 6 are very similar to those of the B(C6F5)3-derived
complexes,3c while the1H and 13C NMR spectra of the
cationic portions of 7 or 8 are very similar to those of
the PBB-derived analogues (that of 8 has been charac-
terized by diffraction4). Due to the thermal instability,
dynamic NMR studies of ion pair reorganization/
symmetrization3a,c,4,18 (e.g., eq 1) could not be carried
out for 2, 3, and 6. Presumably as a consequence of local
C. Qu a n tita tive Com p a r ison of P NB a n d B(C6F 5)3
Lew is Acid ities. Both PNB and B(C6F5)3 react with
NCCH3 to cleanly afford adducts. The coordination of
NCCH3 with PNB or B(C6F5)3 is so strong that NCCH3
cannot be removed under high vacuum (10-5 Torr). The
addition of B(C6F5)3 to a solution of PNBNCCH3 in
toluene-d8 yields the equilibrium illustrated in eq 2. No
free actonitrile is detected in the solution. At these
PNB ring current effects, the Me resonance of the
1
MePNB- anion in the H NMR is generally downfield
of that in MeB(C6F5)3 and MePBB-. The µ-methyl
-
dimeric species react further with PNB to form the
corresponding monomeric species. The µ-F bridged
dimeric cationic species [L2ZrMe(µ-F)MeZrL2]+MePNB-
(L ) Cp, 9; Cp′′, 10) are also detected in these reactions
and could not be separated from the desired products.
concentrations, the exchange rate of actonitrile between
boranes is approximately on the order of the NMR time
scale, as indicated by the broadening of NMR peaks as
the solution temperature is increased from 19.5 to 55
°C. The process depicted in eq 1 reaches equilibrium
Asimilar µ-F-bridged species,[Cp′′2ZrMe(µ-F)MeZrCp′′2]+-
- 3c
MeB(C6F5)3
,
reported to be the thermolysis product
of Cp′′2ZrMe+MeB(C6F5)3-, has been characterized by
X-ray diffraction.3c There is a distinctive µ-F signal in
1
within 10 min at 19.5 °C. The H NMR spectra of the
the 19F NMR spectra of 9 and 10, while the H NMR
1
(15) Brooke, G. M. J . Fluorine Chem. 1989, 43, 393.
(16) Bolton, R.; Sandall, J . P. B. J . Chem. Soc., Perkin Trans. 2 1977,
746-750.
spectra show coupling between the µ-F and Zr-Me
groups in these complexes. In the case of CGCTiMe2,

4002 Organometallics, Vol. 17, No. 18, 1998
Li and Marks
acetonitrile, the most dramatic change in the IR bands
is an increase in the ν(CN) frequency. The ν(CN)
frequency of free acetonitrile is 2253.3 cm-1, while the
reported ν(CN) frequencies of BX3‚NCCH3 (X ) F, Cl,
and Br) are 2376.2, 2369.0, and 2362.0 cm-1, respec-
tively. The measured ν(CN) frequencies of (C6F5)3-
BNCCH3 and PNBNCCH3 in toluene solution are 2366.5
and 2365.3 cm-1, respectively, which suggests that both
boranes are very strong Lewis acids and have similar
Lewis acidity. Since ν(CN) frequencies have been shown
to depend on both electronic and kinematic effects,19c
these data do not allow rigorous differentiation of the
relative PNB and B(C6F5)3 acidities.
F igu r e 3. Least-squares van’t Hoff plot for the equilibrium
PNB(NCCH3) + B(C6F5)3 h (C6F5)3B(NCCH3) + PNB in
toluene-d8.
D. Olefin P olym er iza tion Ca ta lysis. Olefin po-
lymerization experiments were carried out with rigorous
exclusion of air and moisture and in a way such as to
minimize mass-transfer effects.3a,c The results (Table
1) show that both monomeric and dimeric cationic
species generated with PNB are highly active catalysts.
Cationic complexes 5, 6, 7, and 8 are approximately as
active as the B(C6F5)3 analogues for ethylene polymer-
ization (entries 5-10).4 Comparing monomeric cationic
species (5 and 6) to dimeric cationic species (7 and 8),
the polyethylenes produced have similar molecular
weights and polydispersities. These results may indi-
cate that MePNB- is only slightly less coordinating
toward the cation than the neutral Cp2ZrMe2 or Cp′′2-
ZrMe2 complexes. In the case of “constrained geometry”
catalysts (CGC), complex 3 is ∼3× more active than the
B(C6F5)3 analogue for ethylene polymerization and
yields high molecular weight polyethylene with a nar-
rower polydispersity (entries 3, 4). The study of ethyl-
ene and 1-hexene copolymerization with catalyst 3
shows that the activity is substantially higher than that
of the CGCTiMe+MeB(C6F5)3- catalyst (entries 15, 16).4
In the isospecific polymerization of propylene, catalyst
1 exhibits slightly higher activity than the B(C6F5)3-
derived analogue (entries 11-14). However, compared
to the polymers produced by the analogous B(C6F5)3-
derived catalysts at various temperatures, the polymer
produced by 1 at 23 °C has a similar melting temper-
ature and isotacticity index, while the polymer produced
at 60 °C by catalyst 1 exhibits a higher melting
temperature and higher molecular weight.4
mixture shows that the methyl resonance of NCCH3
coordinated to PNB is displaced downfield of that in
(C6F5)3BNCCH3, the difference in chemical shift being
0.173 ppm. Assuming similar diamagnetic shielding
anisotropies, this argues that the Lewis acidity of PNB
is higher than that of B(C6F5)3.17 The equilibrium
constant Keq was measured over a temperature range
of 58 °C in toluene-d8. ∆H° and ∆S° were then
calculated from a plot of ln(Keq) versus 1/T (Figure 3),
which yields ∆H° ) +0.7(2) kcal/mol and ∆S° ) +4.3-
(5) eu. The experiment starting with (C6F5)3BNCCH3
and PNB affords similar results. The positive reaction
enthalpy ∆H° indicates the coordination of NCCH3 with
PNB is stronger than that with B(C6F5)3; that is, PNB
is a slightly stronger Lewis acid than B(C6F5)3. The
reaction entropy ∆S° favors the formation of (C6F5)3-
BNCCH3, possibly reflecting some release of steric
crowding effects (constrained degrees of freedom). In
identical experiments with more sterically encumbered
PBB, no PBBNCCH3 is detected in C6D6 over periods
as long as 2 days when a PBB and (C6F5)3BNCCH3
mixture is stored at 60 °C.
The addition of 1 equiv of PNB to a C6D6 solution of
-
[Cp′′2ZrMe(µ-Me)MeZrCp′′2]+ MeB(C6F5)3 (8) or the
addition of an equimolar mixture of PNB and B(C6F5)3
to a C6D6 solution of Cp′′2ZrMe2 yields the equilibrium
indicated in eq 3, where K ) 0.47 at 21 °C. The greater
Cp′′2ZrMe+MeB(C6F5)3- + PNB y
z
K ) 0.47
Cp′′2ZrMe+MePNB- + B(C6F5)3 (3)
Several large-scale batch polymerizations were car-
ried out in a 2 L Parr reactor. In the copolymerization
of ethylene and 1-octene, the activity of catalyst 3 is
approximately 60% greater than that of the B(C6F5)3-
Lewis acidity and steric bulk of PNB, combined with
the greater delocalization of negative charge in MePNB-,
renders the coordination between Cp′′2ZrMe+ and
MePNB- weaker than that between Cp′′2ZrMe+ and
MeB(C6F5)3-. On the other hand, weaker coordination
between Cp′′2ZrMe+ and MePNB- may also destabilize
the cation-anion ion pair with respect to intramolecular
C-F or C-H scission.3a,c,18
Vibrational spectra have been studied for various
Lewis acid-acetonitrile adducts including MX5‚NCCH3
(M ) As, X ) F;19d M ) Sb, X ) Cl,19d F19c) and BX3‚
NCCH3 (X ) F,19a Cl,19b Br19b). Compared to the free
derived CGCTiMe+MeB(C6F5)3 catalyst (Table 1, en-
-
tries 17, 18).
Con clu sion s
The new organo-Lewis acid, tris(â-perfluoronaphthyl)-
borane (B(C10F7)3, PNB) has been synthesized and
characterized. It is a potent cocatalyst which activates
a variety of dimethyl group 4 complexes efficiently and
rapidly to form highly active cationic olefin polymeri-
(17) (a) Childs, R. F.; Mulholland, L. D.; Nixon, A. Can. J . Chem.
1992, 60, 801-808. (b) Childs, R. F.; Mulholland, L. D.; Nixon, A. Can.
J . Chem. 1992, 60, 809-812.
(18) J ia, L.; Yang, X.; Stern, C. L.; Marks, T. J . Organometallics
1997, 16, 842-857.
(19) (a) Swanson, B.; Shriver, D. F. Inorg. Chem. 1970, 9, 1406. (b)
Shriver, D. F.; Swanson, B. Inorg. Chem. 1971, 10, 1354. (c) Byler, D.
M.; Shriver, D. F. Inorg. Chem. 1973, 12, 1412. (d) Byler, D. M.;
Shriver, D. F. Inorg. Chem. 1974, 13, 2697.

New Organo-Lewis Acids
Organometallics, Vol. 17, No. 18, 1998 4003
Ta ble 1. Olefin P olym er iza tion Da ta for Meta llocen es Activa ted by P NBa
temp cat.
monomerb (°C) (µmol) (mL, min) yield (g)
condc
polymer activityd
Mw
e
entry
1
catalyst
× 105
× 103 Mw/Mn
0.037(6) 1480
remarks
CGCZrMe+MePNB- (2)
E
23
25
23
25
23
25
23
25
23
23
24
24
60
60
23
25
140
140
15
15
15
15
15
15
15
15
15
15
10
10
10
10
15
25
100, 70
100, 20
100, 10
100, 10
100, 1.0
100, 1.0
100, 0.5
100, 1.0
100, 1.0
100, 0.5
50, 2.5
50, 2.5
50, 1.5
50, 1.75
25, 10
25, 10
g
0.065
0
2.47
2h CGCZrMe+MeB(C6F5)3
E
E
E
E
E
E
E
E
E
P
P
P
-
3
CGCTiMe+MePNB- (3)
0.72
0.21
0.92
1.00
1.01
1.50
0.75
0.95
0.88
0.73
0.70
0.63
2.04
0.05
2.9(2)
0.84
37(5)
40.0
81(15)
60.0
34(5)
76(5)
21(2)
18
32(4)
22
8.1(6)
0.12
34(1)
54(4)
1330
1058
97
124
87
321
96
76
3.20
9.54
1.67
2.03
1.88
1.42
1.54
1.61
4h CGCTiMe+MeB(C6F5)3
Cp2ZrMe+MePNB- (5)
-
5
6h Cp2ZrMe+MeB(C6F5)3
-
7
Cp′′2ZrMe+MePNB- (6)
8h Cp′′2ZrMe+MeB(C6F5)3
-
9
10
11
(Cp2ZrMe)2(µ-Me)+MePNB- (7)
(Cp′′2ZrMe)2(µ-Me)+MePNB- (8)
rac-Me2Si(Ind)2ZrMe+MePNB- (1)
42
2.23 Tm ) 146 °C % mmmm ) 93
2.40 Tm ) 146 °C % mmmm ) 93
12h rac-Me2Si(Ind)2ZrMe+MeB(C6F5)3
33
-
13
rac-Me2Si(Ind)2ZrMe+MePNB- (1)
5.0 1.64 Tm ) 128 °C % mmmm ) 86
14h rac-Me2Si(Ind)2ZrMe+MeB(C6F5)3
P
2.7 1.39 Tm ) 122 °C % mmmm ) 86
-
f
15
CGCTiMe+MePNB- (3)
E/H
E/H
E/Og
E/Og
76
2.20 67% H
16h CGCTiMe+MeB(C6F5)3-
63.2% Hf
-
17
18
CGCTiMe+MeB(C6F5)3
1.0
1.0
28.8
46.1
CGCTiMe+MePNB- (3)
g
a
All polymerizations carried out on a high-vacuum line (10-5 Torr); uncertainties in activities are the average of 3 runs; reproducibility
between runs ≈10-15%. Ethylene (E) and propylene (P) 1 atm pressure; 44.0 mmol of 1-hexene (H). c Conditions given as milliliters of
b
toluene, reaction time in minutes. Gram of polymer/[(mole of cationic metallocene)‚atm‚h]. e GPC relative to polystyrene standards.
d
f 1-Hexene incorporation in E/H copolymer. Ethylene (E), 500 psig; 740 g of Isopar E solvent, and 118 g of 1-octene (O), polymerization
g
h
time 15 min. Data from ref 4.
zation catalysts. PNB is a stronger Lewis acid than
B(C6F5)3. Furthermore, the MePNB- anion exhibits less
coordinative tendency than MeB(C6F5)3 with respect
Ack n ow led gm en t. The research was supported by
the U.S. Department of Energy (Grant DE-FG02-86 ER
13511). We thank Drs. You-Xian Chen and Albert Israel
-
to metallocenium cations. The PNB-generated catalysts
have similar or higher olefin polymerization activities
than the B(C6F5)3-derived analogues.
for helpful discussions.
OM980229B