A R T I C L E S
Jones et al.
More recently, Mountford and co-workers have utilized a HTS
approach to discover imido-titanium catalysts for ethylene
polymerization,25 and GPC has been used as a screening method
to discover hetero-ligated phenoxy-imine catalysts for syndio-
tactic propylene polymerization.26 For the Group 6 metal
chromium, we have communicated the discovery of new
polymerization and oligomerization catalyst families assisted
by an HTS approach.12 Here, we describe the rationale behind
the choice of ligand library, the synthesis and characterization
of key pro-ligands and metal complexes, pre-screen validation
chemistry as well as post-validation of hits from the library
screen.
pro-ligand library, specially its ease of synthesis and its
amenability to variation at key substituent sites, combined with
the availability of straightforward complexation procedures and
catalyst screening protocols. Ligands such as phenoxy-imines,
derivable by simple Schiff base condensation chemistry, hold
special attraction for HTS programs, and have already been
shown to afford highly active olefin polymerization catalysts
for Group 422,26,27 and Group 1028 metal systems. The produc-
tivities of the Group 10 metal system have been found to be
enhanced dramatically by incorporating bulky ortho-anthracenyl
substituents in the phenoxide donor.28 The increased activities
are attributed to steric protection of the salicylaldiminato oxygen
by the ortho-anthracenyl group while the isopropyl substituents
of the arylimino donor are positioned above and below the
square plane of the nickel disfavoring associative displacement
of olefin from the metal center. Contrastingly, the Group 4 metal
systems employ salicylaldiminato (phenoxy-imine) ligands
bearing small imine substituents and bis(chelation) is required
to afford high activities. In our earlier work on salicylaldiminato
chromium complexes, we found that bis(chelate) derivatives
containing bulky imine substituents are not particularly active
for ethylene polymerization, with productivities typically <150
Ligand Library Design, Choice of Metal Precursor, and
Initial Validation Experiments. An important consideration
for high throughput catalyst screening is the accessibility of the
(9) Kotov, V. V.; Avtomonov, E. V.; Sundermeyer, J.; Aitola, E.; Repo, T.;
Lemenovskii, D. A. J. Organomet. Chem. 2001, 640, 21.
(10) (a) Matsunaga, P. T., Exxon Chemical Patents Inc., USA, WO9957159,
1999 [CAN 131: 351802]. (b) Fryzuk, M. D.; Leznoff, D. B.; Rettig, S.
J.; Young, V. G. J. Chem. Soc., Dalton Trans. 1999, 147.
(11) (a) Coles, M. P.; Dalby, C. I.; Gibson, V. C.; Clegg, W.; Elsegood, M. R.
J. Chem. Commun. 1995, 1709. (b) Gibson, V. C.; Maddox, P. J.; Newton,
C.; Redshaw, C.; Solan, G. A.; White, A. J. P.; Williams, D. J. Chem.
Commun. 1998, 1651. (c) Coles, M. P.; Dalby, C. I.; Gibson, V. C.; Little,
I. R.; Marshall, E. L.; Ribeiro da Costa, M. H.; Mastroianni, S. J.
Organomet. Chem. 1999, 591, 78. (d) Gibson, V. C.; Newton, C.; Redshaw,
C.; Solan, G. A.; White, A. J. P.; Williams, D. J. J. Chem. Soc., Dalton
Trans. 1999, 827 (e) Gibson, V. C.; Mastroianni, S.; Newton, C.; Redshaw,
C.; Solan, G. A.; White, A. J. P.; Williams, D. J. J. Chem. Soc., Dalton
Trans. 2000, 1969. (f) Gibson, V. C.; Newton, C.; Redshaw, C.; Solan, G.
A.; White, A. J. P.; Williams, D. J. Eur. J. Inorg. Chem. 2001, 1895. (g)
McGuinness, D. S.; Gibson, V. C.; Wass, D. F.; Steed, J. W. J. Am. Chem.
Soc. 2003, 125, 12716.
(12) Jones, D. J.; Gibson, V. C.; Green, S. M.; Maddox, P. J. Chem. Commun.
2002, 1038.
(13) Small, B. L.; Carney, M. J.; Holman, D. M.; O′Rourke, C. E.; Halfern, J.
A. Macromolecules 2004, 37, 4375.
(14) Ruther, T.; Braussaud, N.; Cavell, K. J. Organometallics 2001, 20, 1247.
(15) Ikeda, H.; Monoi, T.; Nakayama, Y.; Yasuda, H. J. Organomet. Chem.
2002, 642, 156.
(16) Wei, P.; Stephan, D. W. Organometallics 2002, 21, 1308.
(17) Ganesan, M.; Gabbai, F. P. Angew. Chem., Int. Ed. 2004, 43, 2263.
(18) Huang, C.; Ahn, J.; Kwon, S.; Kim, J.; Lee, J.; Han, Y.; Kim, H. Appl.
Catal. A 2004, 258, 173.
g‚mmol-1h-1bar-1 11e
We reasoned that the relatively poor
.
performance of the chromium system was most likely due to
the unfavorable coordination environment afforded by binding
two bulky N-O chelate ligands and that more highly active
systems may be attainable by binding just one N-O chelate
ligand decorated with judiciously selected ligand substituents.
It is relevant at this point to consider the relative merits of
small versus large ligand substituents in salicylaldiminato
ligands. It has generally been recognized that a bulky substituent
such as anthracenyl positioned ortho to the phenoxide O-donor
is beneficial since it disfavors interactions with the Lewis acidic
centers of the activator or possibly other catalyst centers, both
(19) (a) Kohn, R. D.; Haufe, M.; Kociok-Kohn, G.; Grimm, S.; Wasserscheid,
P.; Keim, W. Angew. Chem., Int. Ed. 2000, 39, 4337. (b) Wass, D. F. BP
Chemicals Limited, UK, WO. 2002004119, 2002. (c) Carter, A.; Cohen,
S. A.; Cooley, N. A.; Murphy, A.; Scutt, J.; Wass, D. F. Chem. Commun.
2002, 858. (d) Emrich, R.; Heinemann, O.; Jolly, P. W.; Krueger, C.;
Verhovnik, G. P. J. Organometallics 1997, 16, 1511. (e) McGuinness, D.;
Wasserscheid, P.; Keim, W.; Morgan, D.; Dixon, J. T.; Bollmann, A.;
Maumela, H.; Hess, F.; Englert, U. J. Am. Chem. Soc. 2003, 125, 5272. (f)
McGuinness, D. S.; Wasserscheid, P.; Keim, W.; Hu, C.; Englert, U.; Dixon,
J. T.; Grove, C. Chem Commun. 2003, 334.
(20) Bollmann, A.; Blann, K.; Dixon, J. T.; Hess, F. M.; Killian, E.; Maumela,
H.; McGuinness, D. S.; Morgan, D. H.; Neveling, A.; Otto, S.; Overett,
M.; Slawin, A. M. Z.; Wasserscheid, P.; Kuhlmann, S. J. Am. Chem. Soc.
2004, 126, 14712.
(21) (a) Murphy, V.; Volpe, A. F.; Weinberg, W. H. Curr. Op. Chem. Biol.
2003, 7, 427. (b) Stambuli, J. M.; Hartwig, J. F. Curr. Op. Chem. Biol.
2003, 7, 420.
(22) Tian, J.; Coates, G. W. Angew. Chem., Int. Ed. 2000, 39, 3626.
(23) Boussie, T. R.; Diamond, G. M.; Goh, C.; Hall, K. A.; Lapointe, A. M.;
Leclerc, M. K.; Lund, C.; Murphy, V. Symyx Technologies, Inc., USA,
W. 2002038628, 2002.
(24) (a) Boussie, T.; Goh, C.; Diamond, G. M.; Hall, K.; LaPointe, A. M.;
Leclerc, M. K.; Lund, C.; Murphy, V.; Turner, H. W. Polym. Mater. Sci.
Eng. 2002, 86, 306. (b) Boussie, T. R.; Bruemmer, O.; Diamond, G.; Goh,
C.; Lapointe, A. M.; Leclerc, M. K.; Shoemaker, J. A. Symyx Technologies,
Inc., USA, WO. 2003091262, 2003. (c) Boussie, T. R.; Diamond, G. M.;
Goh, C.; Lapointe, A. M.; Leclerc, M. K.; Lund, C. (Symyx Technologies,
Inc., USA), EP. 1308450, 2003. (d) Boussie, T. R.; Diamond, G. M.; Goh,
C.; Hall, K. A.; LaPointe, A. M.; Leclerc, M.; Lund, C.; Murphy, V.;
Shoemaker, J. A. W.; Tracht, U.; Turner, H.; Zhang, J.; Uno, T.; Rosen,
R. K.; Stevens, J. C. J. Am. Chem. Soc. 2003, 125, 4306. (e) Diamond, G.
M.; Goh, C.; Leclerc, M. K.; Murphy, V.; Turner, H. W. Symyx
Technologies, Inc., USA, WO. 2001098371, 2001. (f) Goh, C.; Diamond,
G. M.; Murphy, V.; Leclerc, M. K.; Hall, K.; Lapointe, A. M.; Boussie, T.
R.; Lund, C.; Uno, T. Symyx Technologies, Inc., USA, WO. 2001074910,
2001. (g) Murphy, V.; Bei, X.; Boussie, T. R.; Brummer, O.; Diamond, G.
M.; Goh, C.; Hall, K. A.; Lapointe, A. M.; Leclerc, M.; Longmire, J. M.;
Shoemaker, J. A. W.; Turner, H.; Weinberg, W. H. Chem. Rec. 2002, 2,
278.
(25) Adams, N.; Arts, H. J.; Bolton, P. D.; Cowell, D.; Dubberley, S. R.;
Friederichs, N.; Grant, C. M.; Kranenburg, M.; Sealey, A. J.; Wang, B.;
Wilson, P. J.; Cowley, A. R.; Mountford, P.; Schroder, M. Chem. Commun.
2004, 434.
(26) Mason, A. F.; Coates, G. W. J. Am. Chem. Soc. 2004, 126, 10798.
(27) Recent review: (a) Suzuki, Y.; Terao, H.; Fujita, T. Bull. Chem. Soc. Jpn.
2003, 76, 1493. and references therein (b) Makio, H.; Kashiwa, N.; Fujita,
T. AdV. Synth. Catal. 2002, 344, 477, (c) Suzuki, Y.; Kashiwa, N.; Fujita,
T. Stud. Surf. Sci. Catal. 2003, 145, 525. (d) Mitani, M.; Fujita, T. ACS
Symp. Ser. 2003, 857, 26. (e) Nakayama, Y.; Bando, H.; Sonobe, Y.; Suzuki,
Y.; Fujita, T. Chem. Lett. 2003, 32, 766. (f) Bando, H.; Nakayama, Y.;
Sonobe, Y.; Fujita, T. Macromol. Rapid Comm. 2003, 24, 732. (g)
Nakayama, Y.; Bando, H.; Kaneko, H.; Sonobe, Y.; Mitani, M.; Kojoh,
S.-i.; Kashiwa, N.; Fujita, T. Stud. Surf. Sci. Catal. 2003, 145, 517. (h)
Nakayama, Y.; Mitani, M.; Bando, H.; Fujita, T. Yuki Gosei Kagaku
Kyokaishi 2003, 61, 1124. (i) Mitani, M.; Furuyama, R.; Mohri, J.; Saito,
J.; Ishii, S.; Terao, H.; Nakano, T.; Tanaka, H.; Fujita, T. J. Am. Chem.
Soc. 2003, 125, 4293. (j) Makio, H.; Tohi, Y.; Saito, J.; Onda, M.; Fujita,
T. Macromol. Rapid Comm. 2003, 24, 894. (k) Ishii, S.-i.; Mitani, M.; Saito,
J.; Matsuura, S.; Furuyama, R.; Fujita, T. Stud. Surf. Sci. Catal. 2003, 145,
49. (l) Furuyama, R.; Saito, J.; Ishii, S.-I.; Mitani, M.; Matsui, S.; Tohi,
Y.; Makio, H.; Matsukawa, N.; Tanaka, H.; Fujita, T. J. Mol. Catal., A
Chem. 2003, 200, 31. (m) Fujita, M.; Seki, Y.; Miyatake, T. Polym. Mater.
Sci. Eng. 2003, 89, 372. (n) Yoshida, Y.; Nakano, T.; Tanaka, H.; Fujita,
T. Isr. J. Chem. 2003, 42, 353. (o) Nakayama, Y.; Bando, H.; Sonobe, Y.;
Fujita, T. Bull. Chem. Soc. Jpn. 2004, 77, 617. (p) Nakayama, Y.; Mitani,
M.; Fujita, T. Kogyo Zairyo 2004, 52, 66. (q) Prasad, A. V.; Makio, H.;
Saito, J.; Onda, M.; Fujita, T. Chem. Lett. 2004, 33, 250. (r) Suzuki, Y.;
Inoue, Y.; Tanaka, H.; Fujita, T. Macromol. Rapid Comm. 2004, 25, 493.
(28) (a) Wang, C. M.; Friedrich, S.; Younkin, T. R.; Li, R. T.; Grubbs, R. H.;
Bansleben, D. A.; Day, M. W. Organometallics 1998, 17, 3149. (b)
Younkin, T. R.; Conner, E. F.; Henderson, J. I.; Friedrich, S. K.; Grubbs,
R. H.; Bansleben, D. A. Science 2000, 287, 460. (c) Chan, M. S. W.; Deng,
L. Q.; Ziegler, T. Organometallics 2000, 19, 2741. (d) Bansleben, D. A.;
Connor, E. F.; Grubbs, R. H.; Henderson, J. I.; Younkin, T. R. Cryovac,
Inc., USA, WO. 0056785, 2000. (e) Connor, E. F.; Younkin, T. R.;
Henderson, J. I.; Waltman, A. W.; Grubbs, R. H. Chem. Commun. 2003,
2272.
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