A R T I C L E S
Kawaoka and Marks
ꢀ-caprolactone.6h The block copolymer of polyethylene and poly-
(MMA) represents a polymer with improved dyeability over
nonfunctionalized polyethylene. The ability of organolanthanides
to form polar and nonpolar monomer block copolymers thereby
incorporates functionality into an otherwise inert polymer such
as polyethylene and imparts improved physical polymer proper-
ties such as paintability, adhesion, and compatibility with other
materials.
Another way of incorporating functionality7-9 into polyolefins
is by employing a chain-transfer agent.10-14 However, there are
few examples of efficient chain-transfer agents for organolan-
thanide-catalyzed olefin polymerization. Previously, our group
reported that organosilanes act as efficient chain-transfer agents
for organolanthanide-catalyzed olefin polymerizations as well
as for ethylene and R-olefin copolymerizations.13 Olefin poly-
merizations conducted in the presence of primary silanes
nBuSiH3, C6H5SiH3, and C6H5CH2SiH3 produce silane-capped
polymers with narrow molecular weight distributions. Unfor-
tunately, secondary organosilanes do not act as efficient chain-
transfer agents. Teuben and co-workers subsequently took
advantage of the fact that lanthanocenes cleanly effect aryl C-H
activation and synthesized Cp′2Y(2-pyridyl) from [Cp′2YH]2 and
pyridine (eq 1). In the presence of excess pyridine and ethylene,
2-ethylpyridine was produced catalytically using Cp′2Y(2-
pyridyl) (eq 2).15 Unfortunately, only trace amounts of polymer
were detected.
(6) Organolanthanide-mediated copolymerization of polar and nonpolar mono-
mers: (a) Yasuda, H.; Desurmont, G. Polym. Int. 2004, 53, 1017. (b)
Bonnet, F.; Barbier-Baudry, D.; Dormon, A.; Visseaux, M. Polym. Int. 2002,
51, 986. (c) Yasuda, H. J. Organomet. Chem. 2002, 647, 128. (d) Gromada,
J.; Mortreux, A.; Chenal T.; Ziller, J. W.; Leising, F.; Carpentier, J.-F.
Chem. Eur. J. 2002, 8, 3773. (e) Desurmont, G.; Tanaka, M.; Li, Y.; Yasuda,
H.; Tokimitsu, T.; Tone, S.; Yanagase, A. J. Polym. Sci., Part A: Polym.
Chem. 2000, 38, 4095. (f) Desurmont, G.; Tokimitsu, T.; Yasuda, H.
Macromolecules 2000, 33, 7679. Desurmont, G.; Li, Y; Yasuda, H.; Maruo,
T.; Kanehisa, N.; Kai, Y. Organometallics 2000, 19, 1811. (g) Boffa, L.
S.; Novak, B. M. Macromolecules 1997, 30, 3494. (h) Yasuda, H.; Ihara,
E. Macromol. Chem. Phys. 1995, 196, 2417. (i) Yasuda, H.; Furo, M.;
Yamamoto, H.; Nakamura, A.; Miyake, S.; Kibino, N. Macromolecules
1992, 25, 5115.
More recently, Hessen and co-workers investigated a similar
transformation with thiophene and demonstrated the application
of this heterocycle as a chain-transfer agent for organolan-
thanide-mediated ethylene polymerization (eq 3).12 However,
high ethylene pressures and high reaction temperatures are
required to obtain modest polymerization activities and product
molecular weights. With ethylene polymerizations conducted
in the presence of thiophene or pyridine, the stability of the
(7) Postpolymerization modification: (a) Sheng, Q.; Sto¨ver, H. D. H. Mac-
romolecules 1997, 30, 6451. (b) Chung, T. C.; Lu, H. L.; Li, C. L.
Macromolecules 1994, 27, 7533. (c) Shiono, T.; Kurosawa, H.; Ishida, O.;
Soga, K. Macromolecules 1993, 26, 2085.
(8) Olefin copolymerization with functionalized monomers by d0 polymerization
catalysts: (a) Jensen, T. R.; Yoon, S. C.; Dash, A. K.; Luo L.; Marks, T.
J. J. Am. Chem. Soc. 2004, 125, 14482. (b) Dong, J. Y.; Manias, E.; Chung,
T. C. Macromolecules 2002, 35, 3439. (c) Imuta, J.-I.; Kashiwa, N.; Toda,
Y. J. Am. Chem. Soc. 2002, 124, 1176. (d) Byun, D.-J.; Choi, K.-Y.; Kim,
S. Y. Macromol. Chem. Phys. 2001, 202, 992. (e) Chung, T. C.; Xu, G.
Macromolecules 2000, 33, 5803. (f) Stehling, U. M.; Stein, K. M.; Fisher,
D.; Waymouth, R. M. Macromolecules 1999, 32, 14. (g) Hakala, K.;
Lo¨fgren, B.; Helaja, T. Eur. Polym. J. 1998, 34, 1093. (h) Behr, A. In
Industrial Application of Homogeneous Catalysts; Mortreux, A., Petit, F.,
Eds.; D. Reidel Publishing Co.: Dordrecht, 1998; pp 156-167. (i)
Schneider, M. J.; Scha¨fer, R.; Mu¨lhaupt, R. Polymer 1997, 38, 2455. (j)
DiRenzo, G. M.; White, P. S.; Brookhart, M. J. Am. Chem. Soc. 1996,
118, 6225. (k) Aaltonen, P.; Fink, G.; Lo¨fgren, B.; Seppa¨la¨, J. Macromol-
ecules 1996, 29, 5255. (l) Wile´n, C. -E.; Na¨sman, J. H. Macromolecules
1994, 27, 4051. (m) Kesti, M. R.; Coates, G. W.; Waymouth, R. M. J. Am.
Chem. Soc. 1992, 114, 9679. (n) Klabunde, U.; Ittel, S. D. J. Mol. Catal.
1987, 41, 123.
chelating monoinsertion products, Cp′2LnCH2CH2(C4H3S) (Ln
) Y, La) and Cp′2YCH2CH2(2-C5H4N), is believed to inhibit
facile chain propagation.
(9) Graft polymerization: (a) Dong, J. Y.; Hong, H.; Chung, T. C.; Wang, H.
C.; Datta, S. Macromolecules 2003, 36, 6000. (b) Passaglia, E.; Coiai, S.;
Aglietto, M.; Ruggeri, G.; Ruberta`, M.; Ciardelli, F. Macromol. Symp. 2003,
198, 147. (c) Dolatkhani, M.; Cramail, H.; Deffieux, A.; Santos, J. M.;
Ribeiro, M. R.; Bordado, J. M. Macromol. Chem. Phys. 2003, 204, 1889.
(d) Bowden, N. B.; Dankova, Wiyatno, W.; Hawker, C. J.; Waymouth, R.
M. Macromolecules 2002, 35, 9246. Ciolino, A. E.; Failla, M. D.; Valle´s,
E. M. J. Polym. Sci., Part A: Polym. Chem. 2002, 40, 3950. (e) Uozumi,
T.; Tian, G.; Ahn, C.-H.; Jin. J.; Tsubaki, S.; Sano, T.; Soga, K. J. Polym.
Sci., Part A: Polym. Chem. 2000, 38, 1844.
As noted above, it had previously been shown that electron-
deficient or electron-neutral reagents, such as boranes,10
alanes,11 and silanes,13 can be used as chain-transfer agents for
single-site f n/d0-mediated olefin polymerizations; however, at
the outset of the present study, the application of electron-rich
reagents (e.g. groups 15, 16) as chain-transfer agents to afford
polyolefins capped with electron-rich functional groups had not
yet been efficiently realized. Organolanthanide complexes are
efficient ethylene polymerization as well as hydroamination16
and hydrophosphination17,18 catalysts; therefore, an intriguing
question arises as to whether the two types of transformations
could be coupled to utilize phosphines or amines as chain-
transfer agents for olefin polymerization. This would represent
a new, efficient way of delivering an electron-rich and chemi-
cally versatile fragment to the terminus of a polyolefin chain.
(10) Borane chain transfer: (a) Chung, T. C.; Xu, G.; Lu, Y.; Hu, Y.
Macromolecules 2001, 34, 8040. (b) Xu, G.; Chung, T. C. J. Am. Chem.
Soc. 1999, 121, 6763. (c) Xu, G.; Chung, T. C. Macromolecules 1999, 32,
8689. (d) Lu, B.; Chung, T. C. Macromolecules 1998, 31, 5943.
(11) Aluminum chain transfer: (a) Go¨tz, C.; Rau, A.; Luft, G. Macromol. Mater.
Eng. 2002, 287, 16. (b) Kukral, J.; Lehmus, P.; Klinga, M.; Leskela¨, M.;
Rieger, B. Eur. J. Inorg. Chem. 2002, 1349. (c) Han, C. J.; Lee, M. S.;
Byun, D. -J.; Kim, S. Y. Macromolecules 2002, 35, 8923. (d) Liu, J.;
Støvneng, J. A.; Rytter, E. J. Polym. Sci., Part A: Polym. Chem. 2001,
39, 3566. (e) Po’, R.; Cardi, N.; Abis, L. Polymer 1998, 39, 959. (f) Kang,
K. K.; Shiono, T.; Ikeda, T. Macromolecules 1997, 30, 0, 1231. (g) Mogstad,
A. -L.; Waymouth, R. M. Macromolecules 1992, 25, 2282. (h) Resconi,
L.; Piemontesi, F. Franciscono, G.; Abis, L.; Fiorani, T. J. Am. Chem. Soc.
1992, 114, 1025.
(12) Thiophene C-H chain transfer: Ringelberg, S. N.; Meetsma, A.; Hessen,
B.; Teuben, J. H. J. Am. Chem. Soc. 1999, 121, 6082.
(13) Silane chain transfer: (a) Koo, K.; Marks, T. J. J. Am. Chem. Soc. 1999,
121, 1, 8791. (b) Koo, K.; Fu, P.-F.; Marks, T. J. Macromolecules 1999,
32, 981. (c) Fu, P.-F.; Marks, T. J. J. Am. Chem. Soc. 1995, 117, 10747.
(14) Various chain-transfer agents: (a) Gaynor, S. G. Macromolecules 2003,
36, 4692. (b) Dong, J. Y.; Chung, T. C. Macromolecules 2002, 35, 1622.
(c) Chung, T. C.; Wang, Z. M.; Hong, H.; Chung, T. C. Macromolecules
2002, 35, 9352. (d) Chung, T. C.; Dong, J. Y. J. Am. Chem. Soc. 2001,
123, 4872. (e) Byun, D.-J.; Kim, S. Y. Macromolecules 2000, 33, 1921.
(15) Deelman, B.-J.; Stevels, W. M.; Teuben, J. H.; Lakin, M. T.; Spek, A. L.
Organometallics 1994, 13, 3881.
9
6312 J. AM. CHEM. SOC. VOL. 127, NO. 17, 2005