4
684
Organometallics 2000, 19, 4684-4686
Liga n d Exch a n ge a n d Alk yl Abstr a ction In volvin g
P er flu or oa r yl)bor a n es a n d -a la n es w ith Alu m in u m a n d
Ga lliu m Alk yls
(
,
†
,‡
J erzy Klosin,* Gordon R. Roof, and Eugene Y.-X. Chen*
Catalysis Laboratory, The Dow Chemical Company, Midland, Michigan 48674
Khalil A. Abboud
Department of Chemistry, University of Florida, Gainesville, Florida 32611
Received J uly 5, 2000
Summary: Reaction between M(C6F5)3 (M ) B, Al) and
AlR3 in hydrocarbons leads to facile aryl/ alkyl group
exchange and formation of aluminum dimers, while
reaction of (perfluoroaryl)boranes B(C6F5)3 and B(C12F9)3
with AlR3 (R ) Me, Et, octyl) or GaMe3 in ether solvents
produces alumocenium or gallocenium borates. Neutral
aluminum dimers and cationic alumocenium species
have been found to be very effective as catalyst activators
in ethylene/ 1-octene copolymerization.
reactions involving (perfluoroaryl)boranes and -alanes
1
1
with AlR3 or GaR , as well as the use of the products
3
of these reactions, neutral dimeric aluminum species
and cationic alumocenium borates, as efficient activators
for ethylene and 1-octene copolymerization catalyzed by
5
12
Me2Si(η -Me4C5)(t-BuN)Ti(1,3-pentadiene).
Stirring equimolar amounts of B(C6F5)3 and AlMe3 in
hydrocarbon solvents leads to facile aryl/alkyl group
exchange, offering a convenient and efficient synthesis
7
of Al(C6F5)3. However, monitoring this reaction by
Group 13 based activators such as methylalumin-
NMR in toluene-d8 reveals stepwise CH3/C6F5 ligand
exchange to produce a solution mixture, containing
Al(C6F5)3, dimeric aluminum species [Al(C6F5)x(CH3)3-x]2
1
2
+
- 3
oxane (MAO), B(C6F5)3, [Ph3C] [B(C6F5)4] , and
+
- 4
[
HNRR′2] [B(C6F5)4]
are key components of homoge-
5
neous single-site olefin polymerization catalyst sys-
tems. Aluminum alkyls, being less efficient activators
themselves, are often used in a polymerization system
(
0
x ) 1-2), and borane species B(C6F5)x(CH3)3-x (x )
9,13,14
-2) (Scheme 1).
This exchange reaction does not
go to completion under the conditions of the NMR
experiment to form Al(C6F5)3 in a pure form for over a
6
as scavengers or in situ alkylating reagents. Certain
reactions occurring between AlR3 and the above-
mentioned activators have been observed in many
catalytic systems,7 which raises a question regarding
the true structure of the activator when more than one
cocatalytic component is present. In this communication
2
4 h time period. In a preparative-scale reaction the
equilibrium can be shifted toward Al(C6F5)3 formation
either by precipitation of the product with aliphatic
solvents or by vacuum removal of BMe3. Other AlR3
species undergo similar ligand exchange reactions.
-9
1
0
we report
ligand exchange and alkyl abstraction
Sch em e 1
†
E-mail: klosin@dow.com.
Current address: Department of Chemistry, Colorado State
‡
University, Fort Collins, CO 80523. E-mail: eychen@lamar.colostate.edu.
1) (a) Sinn, H.; Kaminsky, W.; Vollmer, H.-J .; Woldt, R. Angew.
(
Chem., Int. Ed. Engl. 1980, 19, 390-392. (b) Sinn, H.; Kaminsky, W.
Adv. Organomet. Chem. 1980, 18, 99-149.
(
2) (a) Yang, X.; Stern, C. L.; Marks, T. J . J . Am. Chem. Soc. 1994,
1
16, 10015-10031. (b) Yang, X.; Stern, C. L.; Marks, T. J . J . Am. Chem.
Soc. 1991, 113, 3623-3625. (c) Ewen, J . A.; Elder, M. J . Eur. Patent
Appl. 0,427,697, 1991. (d) Massey, A. G.; Park, A. J . J . Organomet.
Chem. 1964, 2, 245-250.
Use of a superstoichiometric amount of AlMe3 ac-
celerates the ligand exchange considerably, and the final
(3) (a) Chien, J . C. W.; Tsai, W.-M.; Rausch, M. D. J . Am. Chem.
Soc. 1991, 113, 8570-8571. (b) Ewen, J . A.; Elder, M. J . Eur. Pat. Appl.
6 5 3
(8) For M(C F ) (M ) Al, B) and MAO (MMAO) exchange, see: (a)
EP 0,426,637, 1991.
Chen, E. Y.-X.; Kruper, W. J .; Roof, G. PCT Int. Appl. WO 0009515
(Dow Chemical Co.). (b) Lee, C. H.; Lee, S. J .; Park, J . W.; Kim, K. H.;
Lee, B. Y.; Oh, J . S. J . Mol. Catal., A: Chem. 1998, 132, 231-239. (c)
Carnahan, E. M.; Chen, E. Y.-X.; J acobsen, G. B.; Stevens, J . C. PCT
Int. Appl. WO 99/15534 (Dow Chemical Co.).
(4) (a) Hlatky, G. G.; Upton, D. J .; Turner, H. W. PCT Int. Appl.
WO 91/09882, 1991. (Exxon Chemical Co.). (b) Yang, X.; Stern, C. L.;
Marks, T. J . Organometallics 1991, 10, 840-842. (c) Turner, H. W.
Eur Pat. Appl. EP 0,277,004 A1, 1988 (Exxon Chemical Co.).
+
-
(5) For recent reviews, see: (a) Gladysz, J . A.; Ed. Chem. Rev. 2000,
(9) For reaction of [Ph C] [B(C F ) ] with AlR , see: Bochmann,
3 6 5 4 3
1
7
00, 1167-1682. (b) Marks, T. J .; Stevens, J . C.; Eds. Top. Catal. 1999,
M.; Sarsfield, M. J . Organometallics 1998, 17, 5908-5912.
(10) For patent applications, see: (a) Klosin, J . PCT Int. Appl. WO
0011006 (Dow Chemical Co.). (b) Chen, E. Y.-X.; Kruper, W. J . PCT
Int. Appl. WO 0015642 (Dow Chemical Co.).
(11) During submission of this paper a separate report describing
some aspects of Al/B exchange chemistry has also appeared: Kim, J .
S.; Wojcinski, L. M., II; Liu S.; Sworen, J . C.; Sen, A. J . Am. Chem.
Soc. 2000, 122, 5668-5669.
(12) Devore, D. D.; Timmers, F. J .; Hasha, D. L.; Rosen, R. K.;
Marks, T. J .; Deck, P. A.; Stern, C. L. Organometallics 1995, 14, 3132-
3134.
, 1-208. (c) Britovsek, G. J . P.; Gibson, V. C.; Wass, D. F. Angew.
Chem., Int. Ed. 1999, 38, 428-447. (d) J ordan, R. F.; Ed. J . Mol. Catal.
1
1
998, 128, 1-337. (e) McKnight, A. L.; Waymouth, R. M. Chem. Rev.
998, 98, 2587-2598. (f) Piers, W. E. Chem. Eur. J . 1998, 4, 13-18.
(g) Kaminsky, W.; Arndt, M. Adv. Polym. Sci. 1997, 127, 144-187. (h)
Bochmann, M. J . Chem. Soc., Dalton Trans. 1996, 255-270. (i)
Brintzinger, H.-H.; Fischer, D.; M u¨ lhaupt, R.; Rieger, B.; Waymouth,
R. M. Angew. Chem., Int. Ed. Engl. 1995, 34, 1143-1170.
(
(
6) Chen, E. Y.-X.; Marks, T. J . Chem. Rev. 2000, 100, 1391-1434.
7) For preparation of Al(C by ligand exchange between B(C
, see: Biagini, P.; Lugli, G.; Abis, L.; Andreussi, P. U. S. Patent
,602,269, 1997 (Enichem).
6
F
5
)
3
6 5 3
F )
and AlR
5
3
(13) For NMR data of MeB(C
ing Information.
6 5 2 2 6 5
F ) and Me B(C F ) see the Support-
1
0.1021/om000573k CCC: $19.00 © 2000 American Chemical Society
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