Formation of sp3-C1-bridged Cp/amido titanium and zirconium CpCN constrained-geometry Ziegler-Natta catalyst systems

Article abstract of DOI:10.1021/om010624t

Formation of sp³-C₁-bridged Cp/amido titanium and zirconium 'CpCN' constrained-geometry Ziegler-Natta catalyst systems was studied. The complexes were characterized by X-ray crystal structure analysis. Activation of the (CpCN)M(NR₂)₂ systems by treatment with a large excess of methylalumoxane in toluene solution gave homogeneous Ziegler-Natta catalysts for the polymerization of ethylene and the copolymerization of ethene with 1-octene.

Full text of DOI:10.1021/om010624t

Organometallics 2002, 21, 1031-1041
1031
F or m a tion of sp 3-C1-Br id ged Cp /Am id o Tita n iu m a n d
Zir con iu m “Cp CN” Con str a in ed -Geom etr y Ziegler -Na tta
Ca ta lyst System s
Klaus Kunz, Gerhard Erker,* Steve Do¨ring, Stephane Bredeau,
Gerald Kehr, and Roland Fro¨hlich†
Organisch-Chemisches Institut der Universita¨t Mu¨nster, Corrensstrasse 40,
D-48149 Mu¨nster, Germany
Received J uly 16, 2001
Addition of methyllithium or p-tolyllithium to the C-6 carbon atom of the lithium (N-
phenylformimidoyl)cyclopentadienide reagent 5 resulted in the formation of the dianionic
sp3-C1-alkylidene-bridged Cp/amido ligand systems [C5H4-CHR-NPh]2- (6a , R ) CH3; 6b,
R ) p-tolyl; each with Li+ cations). Transmetalation of 6a from lithium to zirconium was
achieved by treatment with ZrCl4(THF)2 (7a ) to yield the metallacyclic sp3-C1-linked spiro
constrained geometry complex (η5-C5H4-CHMe-NPh-κN)2Zr (2a ). Treatment of 6a with Cl2-
Ti(NMe2)2 (7c) gave the alkylidene-bridged Cp/amido titanium complex (η5-C5H4-CHMe-
NPh-κN)Zr(NMe2)2 (2b). Analogous treatment of Cl2Zr(NEt2)2(THF)2 (7b) with 6a or 6b
furnished the related (CpCN)Zr complexes (C5H4-CHR-NPh)Zr(NEt2)2 (2c, R ) CH3; 2d ,
R ) p-tolyl) each in g70% yield. The complexes 2a and 2b were both characterized by X-ray
crystal structure analyses. The observation that both exhibit Cp(centroid)-M-N angles that
are by ca. 10° smaller than those of their respective dimethylsilanediyl-bridged analogues
renders the CpCN group metal complexes as more constrained than their conventional
(Cp*SiN)M analogues. Lithium 4-methylanilide adds to the C-6 carbon atom of the non-
CH-acidic pentafulvene (C5H4)dCHCMe3 (13a ) to yield Li[C5H4-CH(CMe3)(NH-p-tolyl)]
(14a ), which was subsequently NH-deprotonated by treatment with LDA to yield the
dianionic reagent [C5H4-CH(CMe3)(N-p-tolyl)]2- (6c, as the dilithium compound). Analogous
addition of lithium tert-butylamide to 13a , followed by NH-deprotonation by treatment with
tert-butyllithium, yielded Li2[C5H4-CH(NCMe3)CMe3] (6d ). Lithium tert-butylamide added
to 1,2,3,4-tetramethylpentafulvene (13b) to yield Li[C5Me4-CH2-NH(CMe3)] (14c), which
was subsequently NH-deprotonated by treatment with tert-butyllithium to yield Li2[C5Me4-
CH2N(CMe3)] (6e). Transmetalation of 6c by treatment with Cl2Ti(NMe2)2 (7c) or Cl2Zr-
(NEt2)2(THF)2 (7b) cleanly gave the respective CpCN group 4 metal complexes [C5H4-
CH(CMe3)(N-p-tolyl)]M(NR2)2 (2e, M ) Ti; 2f, M ) Zr). Similarly, the sp3-C1-bridged
“constrained geometry” system [C5H4-CH(CMe3)(NCMe3)]Zr(NEt2)2 (2g) was obtained in
good yield (70%) from the reaction of 6d with 7b, and treatment of 6e with 7b furnished the
(Cp*CN)Zr complex [C5Me4-CH2-N(CMe3)]Zr(NEt2)2 (2h , 65% isolated). Activation of the
(CpCN)M(NR2)2 systems by treatment with a large excess of methylalumoxane in toluene
solution gave homogeneous Ziegler-Natta catalysts for the polymerization of ethylene
(carried out at 60 °C) and the copolymerization of ethene with 1-octene (at 90 °C).
In tr od u ction
systems 1 probably represent the first significant ex-
amples of this general development.3
Group 4 metallocene systems have attained a consid-
erable importance in homogeneous Ziegler-Natta chem-
istry.1 A variety of recent examples have demonstrated
the increasing value of nonmetallocene systems for the
development of R-olefin polymerization catalysts.2 The
silanediyl-bridged Cp/amido titanium and zirconium
(2) Gue´rin, F.; McConville, D. H.; Payne, N. C. Organometallics
1996, 15, 5085-5089. Gue´rin, F.; McConville, D. H.; Vittal, J . J .
Organometallics 1996, 15, 5586-5590. Gates, P. D.; Svejda, S. A.;
On˜ate, E.; Killian, C. M.; J ohnson, L. K.; White, P. S.; Brookhardt, M.
Macromolecules 2000, 33, 2320-2334 and references therein. Brit-
ovsek, G. J . P.; Mastroianni, S.; Solan, G. A.; Baugh, S. P. D.; Redshaw,
C.; Gibson, V. C.; White, A. J . P.; Williams, D. J .; Elsegood, M. R. J .
Chem. Eur. J . 2000, 6, 2221-2231 and references therein. Reviews:
Britovsek, G. J . P.; Gibson, V. C.; Wass, D. F. Angew. Chem. 1999,
111, 448-468; Angew. Chem., Int. Ed. 1999, 38, 428-447. Ittel, S.
D.; J ohnson, L. K.; Brookhart, M. Chem. Rev. 2000, 100, 1169-
1203.
(3) Reviews: McKnight, A. L.; Waymouth, R. M. Chem. Rev. 1998,
98, 2587-2598. Okuda, J .; Eberle, T. Half-Sandwich Complexes as
Metallocene Analogues. In Metallocenes-Synthesis, Reactivity, Ap-
plications; Togni, A., Haltermann, R. L., Eds.; Wiley-VCH: Weinheim,
Germany, 1998; Vol. 1, pp 415-453.
* To whom correspondence should be addressed. Fax: 49 251
8336503. E-mail: erker@uni-muenster.de.
† X-ray crystal structure analyses.
(1) Reviews: Marks, T. J . Acc. Chem. Res. 1992, 25, 57-65. Aulbach,
M.; Ku¨ber, F. Chem. Unserer Zeit 1994, 28, 197-208. Brintzinger, H.
H.; Fischer, D.; Mu¨lhaupt, R.; Rieger, B.; Waymouth, R. M. Angew.
Chem. 1995, 107, 1255-1283; Angew. Chem., Int. Ed. Engl. 1995, 34,
1143-1170. Bochmann, M. J . Chem. Soc., Dalton Trans. 1996, 255-
270. Kaminsky, W. J . Chem. Soc., Dalton Trans. 1998, 1413-1418.
10.1021/om010624t CCC: $22.00 © 2002 American Chemical Society
Publication on Web 02/16/2002

1032 Organometallics, Vol. 21, No. 6, 2002
Kunz et al.
Sch em e 1. Syn th esis of th e Com p lexes 1
Ch a r t 1
Ch a r t 2
The [Cp*SiMe2NCMe3]2- ligand system was devised
and first introduced to scandium chemistry by Shapiro,
Bercaw, et al.4 and shortly thereafter used by groups
in industry5 as well as academic institutions6 to prepare
the corresponding group 4 metal complexes [(Cp*SiMe2-
NCMe3)MX2] (1; M ) Ti, Zr).7 The synthesis of the
[Cp*SiMe2NCMe3]2- ligand system and the complexes
1 is straightforward, starting with silylation of [Me4C5]-
followed by base-induced amination at silicon and then
double deprotonation (Scheme 1). Activation of 1 with,
for example, excess methylalumoxane leads to active
homogeneous Ziegler-Natta catalysts for olefin polym-
erization. The 1/MAO catalysts have been found to be
especially useful for applications in ethene/1-alkene
copolymerization reactions.3-7
representative examples) were shown to exhibit inter-
esting catalytic features.
It is surprising that the chemistry of the sp3-C1-
bridged “CpCN” analogues 2 of the “CpSiN”M systems
1 seems not to have been significantly developed so far.10
We had previously reported the synthesis and catalytic
properties of a few sp2-C1-bridged Cp/amido group 4
metal systems (3) (see Chart 2).11 Inspection of the
general synthetic scheme of the synthesis of 1 reveals
that the sp3-C1-linked CpCN complexes 2 cannot be
prepared in a simple synthetic analogy. We have now
developed two synthetic routes to the new complexes 2.
These are surprisingly simple and straightforward and
make such systems available in rather high yields with
a number of variations in their substituent pattern.
Their preparation, structural features. and first experi-
ments toward a characterization of their catalytic
properties are described in this paper.
A variety of other bridged Cp/amido group 4 metal
systems have become known.8,9 Especially the C2 and
C3 hydrocarbyl-bridged systems (Chart 1 shows some
(4) Bunel, E. E.; Burger, B. J .; Bercaw, J . E. J . Am. Chem. Soc. 1988,
110, 976-978. Piers, W. E.; Shapiro, P. J .; Bunel, E. E.; Bercaw, J . E.
Synlett 1990, 2, 74-84. Shapiro, P. J .; Bunel, E. E.; Schaefer, W. P.;
Bercaw, J . E. Organometallics 1990, 9, 867-869. Shapiro, P. J .; Cotter,
W. D.; Schaefer, W. P.; Labinger, J . A.; Bercaw, J . E. J . Am. Chem.
Soc. 1994, 116, 4623-4640.
(5) 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 416815-A2, 1991 (Dow Chemical Co.). Canich, J . M., Eur. Patent
Appl. EP 420436-A1, 1991 (Exxon Chemical Co.). Canich, J . M.; Hlatky,
G. G.; Turner, H. W., PCT Appl. WO 92-00333, 1992. See also: 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. Stevens, J .
C. Stud. Surf. Sci. Catal. 1996, 101, 11-20.
Resu lts a n d Discu ssion
(6) Okuda, J . Chem. Ber. 1990, 123, 1649-1651.
Syn t h esis of (Cp CN)gr ou p 4 Met a l Com p lexes
St a r t in g F r om F or m im id oylcyclop en t a d ien id es.
The first synthetic route starts from the formimidoyl-
substituted cyclopentadienides 5. We had recently
shown that such systems can readily be prepared by a
fulvene route.12 We had reacted 6-(dimethylamino)-
fulvene (4)13 with lithium anilide (Scheme 2). In the
course of several hours at ambient temperature in THF
solution exchange of the -NMe2 unit by -N(Li)Ph took
place cleanly with liberation of dimethylamine. The
exchange reaction probably takes place by a two-step
reaction mechanism, initiated by nucleophilic anilide
(7) Hughes, A. K.; Meetsma, A.; Teuben, J . H. Organometallics 1993,
12, 1936-1945. du Plooy, K. E.; Moll, U.; Wocadlo, S.; Massa, W.;
Okuda, J . Organometallics 1995, 14, 3129-3131. Okuda, J .; Verch,
S.; Spaniol, T. P.; Stuermer, R. Chem. Ber. 1996, 129, 1429-1431.
Canich, J . M. PCT Int. Appl. WO 96/00244, 1996 (Exxon Chemical Co.).
Amor, F.; Okuda, J . J . Organomet. Chem. 1996, 520, 245-248. Okuda,
J .; Eberle, T.; Spaniol, T. P. Chem. Ber. 1997, 130, 209-215. Park, J .
T.; Yoon, S. C.; Bae, B.-J .; Seo, W. S.; Suh, I.-H.; Han, T. K.; Park, J .
R. Organometallics 2000, 19, 1269-1276. Dahlmann, M.; Schottek,
J .; Fro¨hlich, R.; Kunz, D.; Nissinen, M.; Erker, G.; Fink, G.; Klein-
schmidt, R. J . Chem. Soc., Dalton Trans. 2000, 1881-1886.
(8) Rieger, B. J . Organomet. Chem. 1991, 420, C17-C20. Ciruelos,
S.; Cuenca, T.; Go´mez-Sal, P.; Manzanero, A.; Royo, P. Organometallics
1995, 14, 177-185. Ciruelos, S.; Cuenca, T.; Go´mez, R.; Go´mez-Sal,
P.; Manzanero, A.; Royo, P. Organometallics 1996, 15, 5577-5585.
Trouve´, G.; Laske, D.; Meetsma, A.; Teuben, J . H. J . Organomet. Chem.
1996, 511, 255-262. Gielens, E. E. C. G.; Tiesnitsch, J . Y.; Hessen,
B.; Teuben, J . H. Organometallics 1998, 17, 1652-1654. Christie, S.
D. R.; Man, K. W.; Whitby, R. J .; Slawin, A. M. Z. Organometallics
1999, 18, 348-359. Rau, A.; Schmitz, S.; Luft, G. J . Organomet. Chem.
2000, 608, 71-75.
(10) (a) Preliminary communication: Kunz, K.; Erker, G.; Do¨ring,
S.; Fro¨hlich, R.; Kehr, G. J . Am. Chem. Soc. 2001, 123, 6181-6182.
(b) Ko¨nemann, M.; Erker, G.; Fro¨hlich, R.; Wu¨rthwein, E.-U. J . Am.
Chem. Soc. 1997, 119, 11155-11164.
(9) Hughes, A. K.; Meetsma, A.; Teuben, J . H. Organometallics 1993,
12, 1936-1945. Sinnema, P.-J .; van der Veen, L.; Speck, A. L.;
Veldman, N.; Teuben, J . H. Organometallics 1997, 16, 4245-4247.
Witte, P. T.; Meetsma, A.; Hessen, B.; Budzelaar, P. H. M. J . Am.
Chem. Soc. 1997, 119, 10561-10562. Gomes, P. T.; Green, M. L. H.;
Martins, A. M. J . Organomet. Chem. 1998, 551, 133-138. van Leusen,
D.; Beetstra, D. J .; Hessen, B.; Teuben, J . H. Organometallics 2000,
19, 4084-4089.
(11) For sp2-C1-bridged analogues see: Duda, L.; Erker, G.; Fro¨hlich,
R.; Zippel, F. Eur. J . Inorg. Chem. 1998, 1153-1162. Kunz, D.; Erker,
G.; Fro¨hlich, R.; Kehr, G. Eur. J . Inorg. Chem. 2000, 409-416.
(12) Kunz, K.; Erker, G.; Kehr, G.; Fro¨hlich, R. Organometallics
2001, 20, 392-400.
(13) Hafner, K.; Schulz, G.; Wagner, K. Liebigs Ann. Chem. 1964,
678, 39-53. See also: Hafner, K.; Vo¨pel, K. H.; Ploss, G.; Ko¨nig, C.
Org. Synth. 1967, 47, 52-54.

Ti and Zr Ziegler-Natta Catalyst Systems
Organometallics, Vol. 21, No. 6, 2002 1033
Sch em e 2
Sch em e 4
in the sp3-CH(CH3) bridging units. Therefore, a mixture
of three diastereoisomers is expected. The 1H NMR
spectrum of the isolated product revealed the presence
of a mixture of isomers. Crystallization from CH2Cl2/
pentane by the diffusion method yielded single crystals
of one diastereomer (cis-2a ) that was characterized by
X-ray diffraction (see below).
Sch em e 3
Then we reacted the reagent 6a with ZrCl2(NEt2)2-
(THF)2 (7b).18 In a 1:1 stoichiometry a clean reaction
takes place in which both chloride ligands are ex-
changed and the [CpCH(CH3)NPh] ligand becomes
attached to the group 4 transition metal center. Com-
plex 2c (M ) Zr, R ) CH3; see Scheme 4) was obtained
in ca. 70% yield. Treatment of 6a with the related
reagent TiCl2(NMe2)2 (7c)19 under analogous conditions
(THF solution, 0 °C, 2 h reaction time) gave the related
“CpCN” titanium complex 2b . Eventually we treated
ZrCl2(NEt2)2(THF) (7b ) with [CpCH(p-tolyl)NPh](Li)2
(2b). The CpCN zirconium complex 2d was isolated in
75% yield (see Scheme 4).
The complexes 2b-d to our knowledge represent the
first examples of simple sp3-C1-bridged (“CpCN”) ana-
logues of the ubiquitous silanediyl-bridged “CpSiN”
constrained-geometry Ziegler-Natta catalyst precursors
1. The complexes 2b-d each contain a chirality center
at the single bridging carbon atoms inside the Cp/amido
ligand system. Therefore, the zirconium complex 2c
exhibits two pairs of 1H NMR signals of the substituted
Cp ligand at δ 6.31 (1H), 6.00 (1H), and 6.07 (2H) and
two overlapping multiplets of the two separate ABX3
spin systems of the pair of diastereotopic -N(C2H5)2
σ-ligands at the pseudotetrahedral group 4 metal center
(δ 3.33, 3.24, 3.19, 3.07).
X-r a y Cr ysta l Str u ctu r e An a lyses. The new CpCN
group 4 metal complexes cis-2a and 2b were character-
ized by X-ray crystal structure analyses. Single crystals
of the spiro-metallocene complex cis-2a were obtained
by diffusion of pentane vapor into a solution of the
diastereomeric mixture of the metal complexes 2a in
dichloromethane solution. The complex cis-2a exhibits
a close to C2-symmetric molecular structure in the
crystal. Only one of the three possible diastereomers has
crystallized (as a racemate) under these experimental
conditions. In the crystal we observed the diastereoiso-
mer that has both the methyl substituents at the
symmetry-equivalent bridging sp3-carbon centers C6A
and C6B oriented toward the front side of the bent-
metallocene wedge (see Figure 1). Thus one of the two
possible cis stereoisomers of complex 2a is found to be
present in the crystal, which will be termed cis-2a .
addition to the electrophilic carbon atom C6 of the
fulvene followed by subsequent amine elimination.11,13
The product 5 was shown by X-ray crystal structure
analysis and dynamic NMR spectroscopy in solution to
exhibit a fully conjugated structure.12 This can be
described by a close to equal participation of the
mesomeric resonance hybrid structures 5A and 5B,
representing residual fulvenoid character (A) or imine-
functionalized cyclopentadienide properties (B) of the
product.14 Both indicate residual electrophilic features
of the sp2-hybridized functionalized C6 carbon atom.
Consequently, this is amenable to nucleophilic attack.
Thus treatment of 5 with methyllithium in THF at
room temperature proceeded smoothly.15 The reaction
went to completion during 12 h to furnish the “dian-
ionic” CpCN ligand system as the corresponding dilithio
compound [CpCH(CH3)NPh](Li)2 (6a ). The analogous
addition of p-tolyllithium cleanly gave the [CpCH(p-
tolyl)NPh](Li)2 system 6b.
Transmetalation of 6a was achieved by treatment
with ZrCl4(THF)2 (7a ) in THF at -78 °C (Scheme 3). In
each case a complete substitution of all four chloride
ligands was observed irrespective of the applied stoi-
chiometry.16,17 Therefore, treatment of the zirconium
tetrachloride reagent with 6a in a 1:2 molar ratio turned
out to be most advantageous. The spiro complex 2a was
isolated in ca. 50% yield. It contains two chiral centers
(14) For the conceptionally related [CpCOCH3]- system see: Fujisa-
wa, T.; Sakai, K. Tetrahedron Lett. 1976, 37, 3331-3334. Rogers, R.
D.; Atwood, J . L.; Rausch, M. D.; Macomber, D. W.; Hart, W. P. J .
Organomet. Chem. 1982, 238, 79-85. Kunz, D.; Fro¨hlich, R. Erker, G.
Organometallics 2001, 20, 572-574.
(15) Ziegler, K.; Scha¨fer, W. Liebigs Ann. Chem. 1934, 511, 101-
109. Ziegler, K.; Gellert, H.-G.; Martin, H.; Nagel, K.; Schneider, J .
Liebigs Ann. Chem. 1954, 589, 91-121. Sullivan, M. F.; Little, W. F.
J . Organomet. Chem. 1967, 8, 277-285. Renaut, P.; Tainturier, G.;
Gautheron, B. J . Organomet. Chem. 1978, 148, 35-42.
(16) Bo¨hme, U.; Thiele, K. H. J . Organomet. Chem. 1994, 472, 39-
41. Okuda, J .; du Plooy, K. E.; Massa, W.; Kang, H.-C.; Rose, U. Chem.
Ber. 1996, 129, 275-277. Hulztsch, K. C.; Okuda, J . Macromol. Rapid
Commun. 1997, 10, 59. Amor, F.; Spaniol, T. P.; Okuda, J . Organo-
metallics 1997, 16, 4765-4767.
(17) For C1-bridged Cp/amino complex systems see: Pflug, J .;
Bertuleit, A.; Kehr, G.; Fro¨hlich, R.; Erker, G. Organometallics 1999,
18, 3818-3826. Kunz, K.; Pflug, J .; Bertuleit, A.; Fro¨hlich, R.; Wegelius,
E.; Erker, G.; Wu¨rthwein, E.-U. Organometallics 2000, 19, 4208-4216
and references therein. General reviews: Siemeling, U. Chem. Rev.
2000, 100, 1495-1526. Butenscho¨n, H. Chem. Rev. 2000, 100, 1527-
1564.
(18) Kempe, P.; Brenner, S.; Arndt, P. Z. Anorg. Allg. Chem. 1995,
621, 2021-2024.
(19) Benzing, E.; Kornicker, W. Chem. Ber. 1961, 94, 2263-2267.

1034 Organometallics, Vol. 21, No. 6, 2002
Kunz et al.
F igu r e 2. View of the molecular structure of the CpCN
titanium complex 2b. Selected bond lengths (Å) and angles
(deg): Ti-C1 ) 2.266(2), Ti-C2 ) 2.314(2), Ti-C3 )
2.402(2), Ti-C4 ) 2.424(2), Ti-C5 ) 2.351(2), Ti-N8 )
2.006(1), Ti-N15 ) 1.911(2), Ti-N18 ) 1.898(1), C1-C6
) 1.505(2), C6-N8 ) 1.476(2), N8-C9 ) 1.387(2); C1-
C6-N8 ) 99.1(1), C6-N8-C9 ) 119.1(1), C6-N8-Ti )
104.3(1), C9-N8-Ti ) 136.2(1).
F igu r e 1. Molecular structure of complex cis-2a . Selected
bond lengths (Å) and angles (deg): Zr-C1A ) 2.418(2), Zr-
C1B ) 2.416(3), Zr-C2A ) 2.485(3), Zr-C2B ) 2.489(3),
Zr-C3A ) 2.528(4), Zr-C3B ) 2.548(4), Zr-C4A )
2.500(3), Zr-C4B ) 2.515(3), Zr-C5A ) 2.454(2), Zr-C5B
) 2.444(3), Zr-N8A ) 2.142(2), Zr-N8B ) 2.143(2), C1A-
C6A ) 1.506(3), C1B-C6B ) 1.516(4), C6A-N8A )
1.473(3), C6B-N8B ) 1.478(3), N8A-C9A ) 1.389(3),
N8B-C9B ) 1.393(3); C1A-C6A-N8A ) 100.1(2) C1B-
C6B-N8B ) 100.7(2), C6A-N8A-C9A ) 118.7(2), C6B-
N8B-C9B ) 117.6(2), C6A-N8A-Zr ) 106.1(1), C6B-
N8B-Zr ) 105.7(2), C9A-N8A-Zr ) 132.0(2), C9B-N8B-
Zr ) 134.4(2).
Ch a r t 3. Com p a r ison of Cp (cen tr oid )-M-N
An gles (in P a r en th eses) of th e Com p lexes cis-2a
a n d 2b (Th is Wor k ) a n d Selected “Con str a in ed
Geom etr y” Refer en ce System s fr om th e Liter a tu r e
The monosubstituted cyclopentadienide ligands in the
complex cis-2a are η5 coordinated. The Zr-C(Cp) bond-
ing distances show a small but systematic decrease in
both rings on going from the periphery toward the ipso
carbon center. The Zr-C3/C4 bond lengths amount to
2.528(4)/2.500(3) Å in ring A (2.548(4)/2.515(2) Å in ring
B), decreasing to Zr-C2A/C5A values of 2.485(3)/2.454-
(2) Å (ring B: 2.489(3)/2.444(3) Å) and eventually to
even shorter metal-carbon values of 2.418(2) Å for the
Zr-C1A bond and 2.416(3) Å for the Zr-C1B linkage.
This decrease is likely to be due to the ring strain inside
the CpCN framework of the “constrained geometry”
complex cis-2a . The C1A-C6A bond length is 1.506(3)
Å (C1B-C6B ) 1.516(4) Å), the adjacent C6A-N8A
distance amounts to 1.473(3) Å (C6B-N8B ) 1.478(3)
Å), and the C1A-C6A-N8A angle is rather small at
100.1(2)° (C1B-C6B-N8B ) 100.7(2)°). The C1A-C6A
vector is oriented out of the plane of the adjacent η5-Cp
ring by 23.3° (C1B-C6B/CpB ) 23.2°). The nitrogen
center in the cis-2a ligand system is trigonal planar
(sum of the bonding angles: at N8A, 356.8°; at N8B,
357.7°), and the N8A-Zr bond length amounts to
2.142(2) Å (N8B-Zr ) 2.143(2) Å). The Zr-N distances
in cis-2a are markedly elongated as compared to e.g.
metrically to the central group 4 transition metal center
with the Ti-C(ipso) linkage (2.266(2) Å) being more
than 0.1 Å shorter than the distal Ti-C3/C4 bonds (for
details see Figure 2). The endocyclic Ti-N8 bond length
is rather long at 2.006(1) Å; the Ti-N15 (1.911(2) Å)
and Ti-N(18) (1.898(1) Å) bonds are markedly shorter.
The C1-C6-N8 (99.1(1)°) and C6-N-Ti (104.3(1)°)
angles in 2b are even slightly smaller than their
counterparts in the zirconium complex cis-2a . In 2b the
Cp(centroid)-Ti-N angle is 95.6°, which is again ca.
10° smaller as found in the (CpSiN)TiX2 reference
molecule 12 (see Chart 3). From a comparison of the
typical structural data we must conclude that the
(CpCN)Zr and Ti complexes 2 contain a markedly more
constrained ligand framework as compared to their
(CpSiN)M analogues. One of the most prominent struc-
tural features where this shows up is the Cp(centroid)-
M-N angle inside the bridged systems. Substituting the
Me2Si linker by the RHC moiety consistently results in
a reduction of about 10°, which must be considered a
large structural effect: the (CpCN)MX2 systems must
be regarded as substantially more “constrained” linked
Cp/amido group 4 metal complexes as compared to their
conventional (CpSiN)MX2 counterparts.
the nonbridged complex CpZr(NiPr2)3 (Zr-N
)
1.988(4)Å)20 or the endocyclicZr-N linkage in [Cp*SiMe2-
(NCMe3)ZrCl2] at 2.052(2) Å.21 The averaged Cp(cen-
troid)-Zr-N8 angle in the complex cis-2a was found
at 89.6°. This should be compared with the correspond-
ing Cp*(centroid)-Zr-N angle in the conventional
(Cp*SiN)Zr(NR2)2 reference complex 9 (see Chart 3) of
100.2°.21
The essential structural features of the (CpCN)-
titanium complex 2b are similar to those of cis-2a .10a
In 2b the η5-Cp ring is also coordinated slightly unsym-
(20) Pupi, R. M.; Coalter, J . N.; Petersen, J . L. J . Organomet. Chem.
1995, 497, 17-25.
(21) Carpenetti, D. W.; Kloppenburg, L.; Kupec, J . T.; Petersen, J .
L. Organometallics 1996, 15, 1572-1581.
Syn th esis of Cp CN Gr ou p 4 Meta l Com p lexes by
a F u lven e Rou te. Upon treatment with a suitable base

Ti and Zr Ziegler-Natta Catalyst Systems
Organometallics, Vol. 21, No. 6, 2002 1035
Sch em e 5
a stronger base. Treatment with tert-butyllithium in
THF (-78 °C to room temperature) gave the doubly
lithiated ligand system (compound 6d ) in almost quan-
titative yield as a very sensitive solid. The 1H NMR
spectrum of 6d now shows a sharp singlet of the 6-H
proton at δ 3.29 (vs a doublet at δ 3.13, 3J HH ) 7 Hz for
the monoanionic starting material 14b, see above). NH
deprotonation of 14c was achieved by treatment with
tert-butyllithium under similar reaction conditions, but
the resulting product 6e was not spectroscopically
characterized, due to its very low solubility even in THF-
d8.
Transmetalation of the alkylidene-bridged Cp/amido
dianion equivalent 6c was achieved by treatment with
the titanium(IV) reagent Cl2Ti(NMe2)2 (7c) in THF
solution. After a reaction time of 2 h at ambient
temperature, workup gave the C1-alkylidene-linked Cp/
amido titanium complex 2e in ca. 70% yield as a dark
red solid. As expected, the chiral complex 2e exhibits
four 1H NMR resonances of the Cp protons at δ 6.16,
6.12, 5.83, and 5.73 (in benzene-d6; corresponding 13C
NMR Cp-methine signals at δ 116.7, 114.8, 114.7, and
111.3), a µ-CH singlet at δ 4.85, and a pair of -NMe2
singlets at δ 3.02 and 2.87.
6-alkylfulvenes react by deprotonation at the alkyl
substituent R-carbon to yield alkenyl-substituted cyclo-
pentadienide systems. This is one of the most frequently
used synthetic entries into bis(alkenylcyclopentadienyl)-
group 4 metal complex systems.23 In the absence of
acidic R-hydrogen atoms at the C-6 substituents, alter-
native addition of a suitable nucleophile to the fulvene
C-6 carbon atom becomes feasible15 even if rather highly
basic nucleophilic reagents are used. We have here used
the “nonenolizable” fulvene 6-tert-butylpentafulvene
(13a ) as a suitable starting material for the synthesis
of an sp3-C1-bridged Cp/amido ligand system.24 Treat-
ment of 13a with in situ generated lithium p-methyl-
anilide in THF at room temperature overnight gave the
1-(arylamino)-2,2-dimethylpropyl-substituted lithium
cyclopentadienide system 14a , which was isolated as a
solid in ca. 90% yield. Similar treatment of 13a with
lithium tert-butylamide gave the corresponding (1-(tert-
butylamino)-2,2-dimethylpropyl)cyclopentadienide sys-
tem 14b as an oil in 91% yield. In 14b the substituent
Analogous treatment of 6c with Cl2Zr(Net2)2(THF2)2
(7b) gave the CpCN zirconium complex 2f as a brown
oil in >60% yield. Again, the 1H NMR spectrum exhibits
four separate Cp-methine resonances (δ 6.38, 6.10,
6.07, 5.93). Due to the chiral ligand framework, the
N-CH2- hydrogens of the Zr(NEt2)2 moiety are dia-
stereotopic, and the two zirconium-bound -NEt2 ligands
are chemically differentiated. Therefore, four distinct
multiplets of the [Zr]-NCH2- protons are observed in
1
the H NMR spectrum of complex 2f (at δ 3.31, 3.28,
3.19, 3.08), and there are two triplets observed origi-
nating from the respective -N(CH2CH3)2 methyl groups
(δ 1.06, 0.65). Treatment of the dianion reagent 6d with
Cl2Zr(NEt2)2(THF)2 (7b) furnished the (CpCN)Zr com-
plex 2g in ca. 70% yield (see Scheme 6). Complex 2g
exhibits a similar NMR behavior.
1
1-H proton H NMR signal is observed as a doublet due
3
to its vicinal J HH ) 7 Hz coupling with the remaining
Eventually, the Cp*-derived dianion reagent 6e was
reacted with the dichloro(diamido)zirconium complex 7b
to give the (Cp*CN)Zr complex 2h , which was isolated
in ca. 65% yield as a colorless oil. The 1H NMR spectrum
of complex 2h shows a µ-CH2 singlet at δ 4.34 (13C NMR
signal at δ 68.6) and a set of two Cp-CH3 resonances
(δ 2.08, 2.06). The two diethylamido ligands at zirco-
nium are symmetry equivalent, but their N-CH2-
hydrogen atoms are each diastereotopic, giving rise to
amino proton (see Scheme 5).
We prepared the tetramethylpentafulvene 13b25 by
a variation of a literature route26 via hydride abstraction
from pentamethylcyclopentadienide by treatment with
triphenylchloromethane.27 Subsequent addition of lithium
tert-butylamide25 cleanly gave the anionic reagent 14c
(75% isolated yield). Compound 14c shows two Cp-CH3
1H NMR singlets at δ 1.86 and 1.82 and a Cp-CH2-
doublet at δ 4.37 (3J HH ) 7 Hz) due to coupling with
the adjacent NH proton.
1
a complex H NMR multiplet centered at δ 3.32 (N-
CH2CH3 triplet at 0.97).
Deprotonation of the NH group in the monoanion
equivalent 14a could be achieved by treatment with the
amide base LDA in tetrahydrofuran to yield the dianion
equivalent 6c (as the dilithio compound; see Scheme 5).
Deprotonation of the aliphatic amino groups in the
alkylamino-substituted cyclopentadienide 14b required
We briefly attempted to convert the bis(diethylamido)-
zirconium complex 2h into the corresponding (Cp*CN)-
ZrCl2 complex 2i. Treatment of 2h with excess (un-
28
purified) trimethylchlorosilane in dichloromethane-d2
led to a ca. 40% conversion to the zirconium dichloride
complex admixed with a complicated mixture of as yet
unidentified additional reaction (or decomposition) prod-
ucts. From this mixture single crystals were obtained
that were identified by X-ray diffraction as the µ-oxo
complex 15: i.e., the H2O addition product to two
molecules of 2i (see Scheme 7).29
(22) Diaz, H. V. R.; Wang, Z.; Bott, S. G. J . Organomet. Chem. 1996,
508, 91-99.
(23) Erker, G.; Wilker, S.; Kru¨ger, C.; Goddard, R. J . Am. Chem.
Soc. 1992, 114, 10983-10984. Erker, G.; Wilker, S.; Kru¨ger, C.; Nolte,
M. Organometallics 1993, 12, 2140-2151.
(24) Stone, K. L.; Little, R. D. J . Org. Chem. 1984, 49, 1849-1853.
(25) Heidemann, T.; J utzi, P. Synthesis 1994, 777-778.
(26) Hashimoto, H.; Tobita, H.; Ogino, H. Organometallics 1993, 12,
2182-2187.
(28) Warren, T. H.; Erker, G.; Fro¨hlich, R.; Wibbeling, B. Organo-
metallics 2000, 19, 127-134.
(27) Do¨ring, S.; Erker, G. Synthesis 2001, 43-45.

1036 Organometallics, Vol. 21, No. 6, 2002
Kunz et al.
Sch em e 6
F igu r e 3. Projection of the molecular structure of complex
15. Selected bond lengths (Å) and angles (deg): Zr-C1 )
2.419(5), Zr-C2 ) 2.460(5), Zr-C3 ) 2.543(6), Zr-C4 )
2.559(6), Zr-C5 ) 2.502(6), Zr-N7 ) 2.500(4), Zr-Cl1 )
2.483(1), Zr-Cl2 ) 2.426(2), Zr-O1 ) 1.954(1), C1-C6 )
1.504(8), C6-N7 ) 1.488(7), N7-C8 ) 1.515(7); Zr-O1-
Zr* ) 168.2(3), C1-C6-N7 ) 104.6(4), C6-N7-C8 )
115.3(4), C6-N7-Zr ) 97.4(3), C8-N7-Zr ) 135.6(3).
equivalent zirconium centers is distorted square-
pyramidal, with a pair of cis chloride ligands (Zr-Cl1
) 2.483(1) Å; Zr-Cl2 ) 2.426(2) Å), the µ-oxo ligand,
and the protonated Cp*CN nitrogen making up the base
of the coordination polyhedron. The Zr-N7 distance
amounts to 2.500(4) Å, which is much longer than the
Zr-N distances observed in the related spiro system 2a
(see above). In 15 the C6-N7-Zr angle amounts to
97.4(3)°. The ammonium nitrogen center in complex 15
is markedly pyramidalizedsthe sum of the three heavy-
atom bond angles around nitrogen in 15 is 348.3°. The
N7-C6-C1 angle in 15 amounts to 104.6(4)°. The C5-
Me4 ligand is again slightly unsymmetrically η5-
coordinated to zirconium, with the Zr-C1 distance
(2.419(5) Å) being markedly shorter than the adjacent
Zr-C2/C5 (2.460(5) Å/2.502(6) Å) and the distal Zr-C3/
C4 bonds (2.543(6) Å/2.559(6) Å).
Sch em e 7
Olefin P olym er iza tion Rea ction s. Ethylene po-
lymerization reactions were carried out with the new
CpCN titanium systems 2b,e and with the CpCN
zirconium complexes 2d ,f,g,h . The group 4 metal com-
plexes were in each case activated by treatment with a
large excess of methylalumoxane1,31 (for Al/M ratios and
further details see Table 1). For a comparison, ethylene
polymerization reactions were carried out under similar
conditions, employing the (Cp*SiN)Zr “constrained ge-
ometry” systems [(C5Me4)SiMe2CMe2]ZrCl2 (1) and [(C5-
Me4)SiMe2CMe3]Zr(NMe2)2 (9). Some of these experi-
ments were repeated several times under similar reaction
conditions to check for general reproducibility. Tables
1 and 2 provide representative data of single examples
The X-ray crystal structure analysis of the crystalline
product 15 (Figure 3) revealed that the treatment of the
tetramethylfulvene 13b with lithium tert-butylamide
had indeed produced the respective Cp*CN ligand
system and that it was successfully attached to the
group 4 metal. The -NEt2 vs -Cl exchange reaction had
apparently taken place, but the resulting product (2i)
had added 1 equiv of water under the applied reaction
conditions to form a [Zr]-µ-O-[Zr] dimer (15). In this
case, elimination of HCl had not yet taken place, but
the doubly N-protonated product was observed. The Zr-
O-Zr* angle in complex 15 amounts to 168.2(3)°, which
is only by 12° away from the linear arrangement that
is often observed in µ-oxo-group 4 metal complex
systems. The Zr-O bond in 15 is short at 1.954(1) Å,
indicating some oxygen to metal π-back-bonding.30 The
coordination geometry around the two symmetry-
(31) Dyachkowskii, F. S.; Shilova, A. K.; Shilov, A. E. J . Polym. Sci.
C 1967, 16, 2333-2339. Andresen, A.; Cordes, H. G.; Herwig, H.;
Kaminsky, W.; Merk, A.; Mottweiler, R.; Pein, J .; Sinn, H.; Vollmer,
H. J . Angew. Chem. 1976, 88, 689-690; Angew. Chem., Int. Ed. Engl.
1976, 15, 630-631. Sinn, H. J .; Kaminsky, W.; Vollmer, H. J .; Woldt,
R. Angew. Chem. 1980, 92, 396-402; Angew. Chem., Int. Ed. Engl.
1980, 19, 390-396. Fink, G.; Zoller, W. Makromol. Chem. 1981, 182,
3265-3278. Kaminsky, W.; Miri, M.; Sinn, H. J .; Woldt, R. Macromol.
Chem. Rapid Commun. 1983, 4, 417-421. Kaminsky, W.; Ku¨lper, K.;
Brintzinger, H. H.; Wild, F. R. W. P. Angew. Chem. 1985, 97, 507-
508; Angew. Chem., Int. Ed. Engl. 1985, 24, 507-508. Chien, J . C.
W.; Sugimoto, R. J . Polym. Sci., Polym. Chem. 1991, 29, 459-470.
Rieger, B.; J aniak, C. Angew. Makromol. Chem. 1994, 215, 35. Barron,
A. R. Macromol. Symp. 1995, 97, 15. Review: Sinn, H.; Kaminsky, W.
Adv. Organomet. Chem. 1980, 18, 99-149.
(29) For a related H2O-addition product to a Ti-amino complex
see: Bertuleit, A.; Ko¨nemann, M.; Duda, L.; Erker, G.; Fro¨hlich R. Top.
Catal. 1999, 7, 37-44.
(30) Erker, G.; Dorf, U.; Kru¨ger, C.; Tsay, Y.-H. Organometallics
1987, 6, 680-682 and references therein.

Ti and Zr Ziegler-Natta Catalyst Systems
Organometallics, Vol. 21, No. 6, 2002 1037
Ta ble 1. Eth en e P olym er iza tion Rea ction s
Em p loyin g Cp CN Gr ou p 4 Meta l/Meth yla lu m oxa n e
Ca ta lysts (a t 60 °C a n d 2 ba r of Eth en e P r essu r e in
Tolu en e Solu tion )a
metal complexes. Both routes are conceptually related,
and both make use of the C-6 electrophilicity of pen-
tafulvenes or pentafulvenoid systems. Given the ease
of formation of the various (CpCN)group 4 metal
complexes, whose syntheses were carried out in the
course of our study, it is surprising that the chemistry
of such (CpCN)M systems has remained so largely
undeveloped as compared to their ubiquitous (Cp*SiN)M
relatives.
amt of
amt of
no. compd
M
cat. (mg)b Al/M PE (g) mp (°C) actc
1
2
3
4
5
6
7
8
2b
2e
2d
2f
2g
2h
1d
9d
Ti
Ti
Zr
Zr
Zr
Zr
Zr
Zr
21
19
20
20.5
21.5
10
17
16
500
660
820
760
680
1470
800
890
2.0
4.2
1.3
1.1
6.3
2.2
2.1
2.4
120
125
123
126
128
131
123
122
15
42
12
13
101
97
We were able to show that the CpCN group 4 metal
systems can be used for generating active ethylene
polymerization catalysts as well as ethylene/R-olefin
copolymerization catalysts. 1-Octene incorporation in
the resulting copolymers is often quite high in these
homogeneous (CpCN)M/MAO Ziegler-Natta catalyst
systems, but their activities seem to be somewhat lower
as compared to the conventional (Cp*SiN)Zr-derived
catalyst systems under the applied specific conditions.
This is surprising in view of the markedly decreased
Cp(centroid)-M-N angles that we have observed in our
X-ray diffraction analysis for the (CpCN)Ti and -Zr
examples investigated in the course of this study. The
new (CpCN)MIV systems show by ca. 10° smaller such
angles at the central group 4 metal as compared to their
directly related (CpSiN)MIV analogues, which should
render the (CpCN)M systems as more constrained than
the conventional dimethylsilanediyl-bridged Cp/amido
group 4 metal complexes.34
29
27
a
In most cases typical single examples out of a series of several
analogous experiments are reported. b Milligrams of group 4 metal
component. c In (g of PE)/((mmol of group 4 metal catalyst) h (bar
of ethene)). The reaction time was in all cases 1 h. 1, [(C5Me4)-
d
SiMe2NCMe3]ZrCl2; 9, [(C5Me4)SiMe2NCMe3]Zr(NMe2)2.
out of these series. The first experiments showed that
the systems 2f/MAO and 2g/MAO were close to inactive
at 25 °C under the selected standard conditions (2 bar
of ethylene in toluene solution). Therefore, the ethene
polymerization reactions with the selected examples of
the complexes 2 (see Table 1) were carried out at higher
temperature. At 60 °C in toluene at a constant ethylene
pressure of 2 bar, polyethylene was formed by the
2/MAO catalyst. Both the CpCN titanium and zirconium
systems showed catalyst activities in ethene polymer-
ization under these conditions that were largely in the
same range as observed for the Cp*SiN zirconium/MAO
reference systems, under our conditions, with the (CpC-
N)Zr (2g)/MAO and the (Cp*CN)Zr (2h )/MAO Ziegler-
Natta catalysts being the best in this zirconium series
(see Table 1).
Ethene/1-octene copolymerization reactions were car-
ried out under slightly optimized reaction conditions.
Most of the CpCN group 4 metal complexes give
Ziegler-Natta catalysts upon MAO activation that are
active in the ethylene/R-olefin copolymerization reaction,
and they all produce copolymers that contain reasonable
amounts of the extended 1-alkene incorporated (see
Table 2). Generally it appears that the (Cp*CN)Zr
system (2h /MAO) incorporates slightly less 1-octene
than the (CpCN)M/MAO systems featuring the smaller
C5H4 ligand subunit. The latter produced copolymers
under these experimental conditions that contained
almost as much of the 1-octene component as was
incorporated by employing the (Cp*SiN)Zr reference
system 9 under these conditions (the copolymer com-
position was determined by a standard 13C NMR
analysis;32,33 see Figure 4 for a selected example).
However, the new (CpCN)M/MAO catalysts seem to be
less active ethene/1-octene copolymerization catalysts
under the conditions applied here (see Table 2) as
compared to the Cp*SiN zirconium (9)/MAO catalyst.
There are several possible explanations for our ob-
servation, of which the simplest would be that the CpCN
catalysts might exhibit different temperature profiles.
Our findings could alternatively indicate that the co-
polymerization activities of such systems, contrary to
common belief,9,34 might not be related to their “con-
strained geometry” qualities but that steric and elec-
tronic effects in Cp/amido group 4 metal catalyst
systems in a subtle combination are determining the
essential properties of such catalyst systems and their
specific action. It could also be that our new catalysts
are “too constrained” to allow for a simple extension of
the catalytic activities in the general series of such
compounds, since they might offer such an open and
exposed active catalytic site that toluene solvent (or
[X-MAO]- anion) interaction begins to effectively com-
pete with monomer about the available coordination
space at the active metal center.35 In that case, alterna-
tive pathways of activation36 and the use of other, less
coordinative solvents could be indicated. Investigations
(34) Woo, T. K.; Margl, P. M.; Lohrenz, J . C. W.; Blochl, P. E.;
Ziegler, T. J . Am. Chem. Soc. 1996, 118, 13021-13030. Chen, Y.-X.;
Marks, T. J . Organometallics 1997, 16, 3649-3657. Chen, Y.-X.; Fu,
P.-F.; Stern, C. L.; Marks, T. J . Organometallics 1997, 16, 5958-5963.
Lanza, G.; Fragala`, I. L.; Marks, T. J . J . Am. Chem. Soc. 1998, 120,
8257-8258 and references therein.
(35) Spence, R. E. v. H.; Piers, W. E. Organometallics 1995, 14,
4617-4624. Chen, Y.-X.; Stern, C. L.; Marks, T. J . J . Am. Chem. Soc.
1997, 119, 2582-2583. Chen, Y.-X.; Metz, M. V.; Li, L.; Stern, C. L.;
Marks, T. J . J . Am. Chem. Soc. 1998, 120, 6287-6305. Beswick, C. L.;
Marks, T. J . Organometallics 1999, 18, 2410-2412. Beck, S.; Lieber,
S.; Schaper, F.; Geyer, A.; Brintzinger, H.-H. J . Am. Chem. Soc. 2001,
123, 1483-1489.
Con clu sion s
In this study we have developed two rather simple
routes to alkylidene (sp3-C1)-bridged Cp/amido group 4
(36) Temme, B.; Erker, G.; Karl, J .; Luftmann, H.; Fro¨hlich, R.;
Kotila, S. Angew. Chem. 1995, 107, 1867-1869; Angew. Chem., Int.
Ed. Engl. 1995, 34, 1755-1757. Dahlmann, M.; Erker, G.; Fro¨hlich,
R.; Meyer, O. Organometallics 2000, 19, 2956-2967. Dahlmann, M.;
Erker, G.; Bergander, K. J . Am. Chem. Soc. 2000, 122, 7986-7998.
Reviews: Chen, E. Y.-X.; Marks, T. J . Chem. Rev. 2000, 100, 1391-
1434. Erker, G. Acc. Chem. Res. 2001, 34, 309-317.
(32) Randall, J . C. J MS-Rev. Macromol. Chem. Phys. 1989, C29 (2
& 3), 201-317. See also: Wang, W.-J .; Kolodka, E.; Zhu, S.; Hamielec,
A. E. J . Polym. Sci. A 1999, 37, 2949-2957. Liu, W.; Ray III, D. G.;
Rinaldi, P. L. Macromolecules 1999, 32, 3817-3819.
(33) See also: Knu¨ppel, S.; Erker, G.; Fro¨hlich, R. Angew. Chem.
1999, 111, 2048-2051; Angew. Chem., Int. Ed. 1999, 38, 1923-1926.

1038 Organometallics, Vol. 21, No. 6, 2002
Kunz et al.
Ta ble 2. Eth en e/1-Octen e Cop olym er iza tion Rea ction s Usin g Cp CN Gr ou p 4 Meta l/MAO Ca ta lysts (in
Tolu en e Solu tion a t 90 °C)a
no.
compd
M
amt of cat. (mg)
t (h)
Al/M
amt of polym (g)
ethene:octeneb
mp (°C)
Mw
Mw/Mn
actc
2 bar of Ethene/20% 1-Octene
1
2
3
2c
2g
2h
Zr
Zr
Zr
23
20
21
1
1
1
600
730
690
4.8
7.8
15.4
21:1
13:1
25:1
93
89
98
25 000
10 000
20 000
2.8
3.1
d
46
86
162
2 bar of Ethene/50% 1-Octene
4
5
6
7
8
2e
2f
2g
2h
9e
Ti
Zr
Zr
Zr
Zr
20
20.5
20
19
16
1
1
1
1
630
760
730
770
870
2.9
2.1
3.6
4.2
27.0
4:1
5:1
7:1
13:1
4:1
oil
oil
oil
96
oil
54
25
40
47
480
3000
29 000
2.9
2.8
0.75
1 bar of Ethene/50% 1-Octene
9
10
11
12
2e
2f
2g
9e
Ti
Zr
Zr
Zr
15
25
30
20
0.75
820
640
490
660
5.1
1.8
3.3
3:1
4.5:1
5.5:1
3:1
oil
oil
oil
oil
170
34
37
1
1
1
15 000
2.4
20.8
400
a
b
In most cases typical examples of a series of several analogous experiments are reported. The ethene:1-octene ratio in the copolymer
was determined by 13C NMR spectroscopy.32 c Catalyst activities in (g of copolymer)/((mmol of group 4 metal cat.) h (bar of ethene)).d Not
determined. e [(C5Me4)SiMe2NCMe3]Zr(NMe2)2.
F igu r e 4. 13C NMR spectrum of the ethene/1-octene copolymer (Table 2, entry 11) in benzene-d6 solution (with signal
assignment according to ref 32).
P r ep a r a tion of Lith iu m [1-(p-Tolyla m in o)-2,2-d im eth -
ylp r op yl]cyclop en ta d ien id e (14a ). Samples of 800 mg (7.46
mmol) of LDA and 800 mg (7.46 mmol) of 4-methylaniline were
dissolved in 100 mL of THF, and the mixture was stirred for
2 h. The in situ generated lithium 4-methylanilide solution
was then added to 1.00 g (7.46 mmol) of 6-tert-butylpentaful-
vene (13a ), dissolved in 50 mL of THF, and the mixture was
stirred for 12 h at room temperature. Solvent was removed in
vacuo to give a brown viscous oil. A 50 mL portion of pentane
was added and subsequently removed to solidify the product.
A total of 2.12 g (7.00 mmol, 89%) of a pale brown solid was
isolated. 1H NMR (200.13 MHz, THF-d8, 298 K): δ 6.90 (m,
2H, tol H), 6.56 (m, 2H, tol H), 5.68 (b, 4H, Cp H), 4.09 (b, 1H,
CH), 2.23 (s, 3H, tol CH3), 1.02 (s, 9H, C(CH3)3), NH not
observed.
aimed at clarifying these points are currently being
carried out in our laboratory.
Exp er im en ta l Section
All reactions were carried out under argon using Schlenk-
type glassware or in a glovebox. Solvents were dried and
distilled prior to use. NMR spectra were measured using a
Bruker AC 200 P or Varian Unity Plus 600 NMR spectrometer.
Most assignments were based on a series of 2D NMR experi-
ments.37 Pentafulvenes 4 and 13a and the reagents ZrCl4-
(THF)2 (7a ), Cl2Zr(NEt2)2(THF)2 (7b),18 and Cl2Ti(NMe2)2 (7c)19
were prepared according to literature procedures. Lithium (N-
phenylimidoyl)cyclopentadienide (5)12 and 1,2,3,4-tetrameth-
ylpentafulvene (13b)27 were synthesized as described in recent
publications.
P r ep a r a t ion of Lit h iu m [1-(ter t-Bu t yla m in o)-2,2-d i-
m eth ylp r op yl]cyclop en ta d ien id e (14b). Lithium tert-but-
ylamide was formed in situ by reaction of 545 mg (7.46 mmol)
of tert-butylamine with 800 mg (7.46 mmol) of LDA in 80 mL
of THF. A 1.00 g (7.46 mmol) amount of 6-tert-butylfulvene
(37) Braun, S.; Kalinowski, H. O.; Berger, S. 150 and More Basic
NMR Experiments, VCH: Weinheim, Germany, 1998, and references
therein.

Ti and Zr Ziegler-Natta Catalyst Systems
Organometallics, Vol. 21, No. 6, 2002 1039
(13a ) in 50 mL of THF was added and the reaction mixture
stirred for 12 h. A 1.44 g amount (6.79 mmol, 91%) of the oily
product was isolated after evaporation of the solvent. 1H NMR
(200.13 MHz, THF-d8, 298 K): δ 5.56 (m, 2H, Cp H), 5.52 (m,
2H, Cp H), 3.18 (d, 3J ) 7.0 Hz, 1H, CH), 0.95 (s, 9H, C(CH3)3),
0.83 (s, 9H, C(CH3)3), NH not observed. 13C{1H} NMR (50.3
MHz, THF-d8, 298 K): δ 125.4 (ipso Cp), 103.1 (Cp), 101.1 (Cp),
62.4 (CH), 50.9 (N(C(CH3)3), 36.2 (C(C(CH3)3), 30.5 (C(CH3)3),
27.9 (C(CH3)3). 7Li NMR (232.8 MHz, THF-d8, 298 K): δ -7.5.
Syn t h esis of Lit h iu m 1-[(ter t-Bu t yla m in o)m et h yl]-
2,3,4,5-tetr a m eth ylcyclop en ta d ien id e (14c). Lithium tert-
butylamide (200 mg, 2.53 mmol) was dissolved in 50 mL of
pentane and 2 mL of THF and reacted with 2.5 g of a 9:1
mixture of toluene and 1,2,3,4-tetramethylpentafulvene (13b)
at room temperature. Over 12 h a white solid precipitated.
The solid was collected by filtration, washed with 20 mL of
pentane twice, and dried in vacuo to give 440 mg (1.90 mmol,
75%) of 14c. 1H NMR (200.13 MHz, THF-d8, 298 K): δ 4.37
time, and 30 mL of pentane was added. The mixture was
stirred for 15 min, and the pale solid was collected by filtration
and dried in vacuo to yield 1.21 g (5.53 mmol, 98%) of 6d . H
1
NMR (200.13 MHz, THF-d8, 298 K): δ 5.7-5.5 (b, 4H, Cp H),
3.29 (s, 1H, CH), 1.13 (s, 9H, C(CH3)3), 0.95 (s, 9H, C(CH3)3).
P r ep a r a tion of Dilith iu m 1-[(ter t-Bu tyla m id o)m eth yl]-
2,3,4,5-tetr a m eth ylcyclop en ta d ien id e (6e). A 1.56 M solu-
tion of tert-butyllithium in hexane (0.63 mL) was added
dropwise to a solution of 200 mg (0.98 mmol) of lithium 1-[(tert-
butylamino)methyl]-2,3,4,5-tetramethylcyclopentadienide (14c)
in 50 mL of THF at -78 °C. The reaction mixture was stirred
for 12 h and the precipitated product collected by filtration,
washed with 10 mL of pentane, and dried in vacuo. A 130 mg
amount (0.61 mmol, 62%) of a white solid was isolated which
was insoluble even in THF.
P r ep a r a t ion of Bis[η5-[1-(p h en yla m id o)et h yl]cyclo-
p en ta d ien yl-KN]zir con iu m (2a ). A solution of 750 mg (2.8
mmol) of dilithium [1-(phenylamido)ethyl]cyclopentadienide
(6a ) in 50 mL of THF was added slowly to a solution of 1.06 g
(2.8 mmol) of ZrCl4(THF)2 (7a ) in 50 mL of THF at -78 °C.
The mixture was warmed to 0 °C, and the solvent was removed
subsequently. A 40 mL amount of dichloromethane was added,
and the precipitated LiCl was filtered off. The solvent was
evaporated and the brown solid dried in vacuo to yield 652
mg (1.42 mmol, 51%) of 2a . Single crystals for X-ray diffraction
were obtained by slow diffusion of pentane into a concentrated
solution of 2a in dichloromethane. 1H NMR (200.13 MHz, THF-
d8, 298 K): δ 7.08 (m, Ph), 6.90-6.70 (m, Ph), 6.59, 6.52, 6.03,
5.69 (each m, Cp), 5.16-5.11 (m, 6-H), 1.50-1.38 (m, 7-H).
Anal. Calcd for C26H26N2Zr (457.7): C, 68.23; H, 5.73; N, 6.12.
Found: C, 68.56; H, 6.20; N, 6.28.
3
(d, J ) 7.0 Hz, 2H, CH2), 1.86 (s, 6H, Cp CH3), 1.82 (s, 6H,
Cp CH3), 1.19 (s, 9H, C(CH3)3), NH not observed. 13C{1H} NMR
(50.3 MHz, THF-d8, 298 K): δ 111.0 (ipso Cp), 107.3 (Cp), 107.2
(Cp), 50.6 (C(CH3)3), 38.5 (CH2), 29.7 (C(CH3)3), 10.8 (Cp CH3),
10.6 (Cp CH3).
P r ep a r a tion of Dilith iu m 1-[(P h en yla m id o)eth yl]cy-
clop en ta d ien id e (6a ). A sample of 3.00 g (12.10 mmol) of
lithium (N-phenylimidoyl)cyclopentadienide (5) in 50 mL of
diethyl ether was treated with 7.40 mL of a 1.63 M solution of
methyllithium in diethyl ether at room temperature, and the
mixture was stirred for 12 h. After evaporation of the solvent,
2.93 g (11.60 mmol, 96%) of a pale brown solid was isolated in
acceptable purity, containing 0.75 equiv of THF. 1H NMR
(200.13 MHz, THF-d8, 298 K): δ 6.69 (m, 2H, m-Ph), 6.29 (m,
2H, o-Ph), 5.80 (m, 1H, p-Ph), 5.66 (bm, 4H, Cp), 4.25 (q, 3J H-H
) 6.0 Hz, 1H, 6-H), 1.26 (d, 3J ) 6.0 Hz, 3H, 7-H). 13C{1H}
NMR (50.3 MHz, THF-d8, 298 K): δ 161.2 (ipso-Ph), 129.6 (Ph),
128.7 (Ph), 114.1 (Ph), 107.9 (C-1), 102.7 (Cp), 102.6 (Cp), 50.6
(C-6), 19.8 (C-7). 7Li NMR (232.8 MHz, THF-d8, 298 K): δ -3.5
(br).
Syn t h esis of Dilit h iu m 1-(P h en yla m id o)-1-(p -t olyl-
m eth yl)cyclop en ta d ien id e (6b). A solution of 390 mg (4.00
mmol) of p-tolyllithium in 30 mL of THF was added to 990
mg (4.00 mmol) of lithium (N-phenylimidoyl)cyclopentadienide
(5), dissolved in 50 mL of THF, and stirred overnight. The
solvent was removed and the remaining oil solidified by
treatment with 50 mL of pentane and subsequent evaporation.
A 1.03 g amount (3.76 mmol, 94%) of a brown solid was
isolated. 1H NMR (200.13 MHz, THF-d8, 298 K): δ 7.25 (m,
2H, tol H), 6.88 (m, 2H, tol H), 5.80 (m, 2H, m-Ph H), 6.00 (b,
3H, o- and p-Ph H), 5.67 (m, 2H, Cp H), 5.53 (b, 2H, Cp H),
5.12 (s, 1H, CH), 2.22 (s, 3H, tol CH3).
X-r a y Cr ysta l Str u ctu r e An a lysis of cis-2a . Crystal data
are as follows: formula C26H26N2Zr, Mr ) 457.71, yellow
crystal, 0.35 × 0.30 × 0.30 mm, a ) 12.346(1) Å, b ) 20.442-
(1) Å, c ) 8.422(1) Å, V ) 2125.5(3) Å3, Fcalcd ) 1.430 g cm-3
,
µ ) 5.32 cm-1, empirical absorption correction via SORTAV
(0.836 e T e 0.857), Z ) 4, orthorhombic, space group Pna21
(No. 33), λ ) 0.710 73 Å, T ) 198 K, ω and æ scans, 11 065
reflections collected ((h, (k, (l), (sin θ)/λ ) 0.65 Å-1, 3745
independent (Rint ) 0.029) and 3429 observed reflections (I g
2σ(I)), 264 refined parameters, R1 ) 0.026, wR2 ) 0.061,
maximum residual electron density 0.22 (-0.33) e Å-3, Flack
parameter -0.04(3), hydrogens calculated and refined as riding
atoms.
P r ep a r a tion of Bis(d im eth yla m id o)[η5-[1-(p h en yla m i-
d o)eth yl]cyclop en ta d ien yl-KN]tita n iu m (2b). A solution
of 300 mg (1.12 mmol) of dilithium 1-[(phenylamido)ethyl]-
cyclopentadienide (6a ) in 50 mL of THF was added dropwise
to 231 mg (1.12 mmol) of Cl2Ti(NMe2)2 (7c) in 50 mL of THF
at 0 °C. Over 2 h the reaction mixture was warmed to room
temperature. The solvent was removed in vacuo, and the oily
residue was treated with 40 mL of pentane. After filtration of
LiCl and evaporation of the solvent 246 mg (77 mmol, 69%) of
2b was obtained as a red solid. Single crystals were obtained
from a concentrated solution of 2b in dichloromethane at -20
F or m a tion of Dilith iu m [1-(p-Tolyla m id o)-2,2-d im eth -
ylp r op yl]cyclop en ta d ien id e (6c). A sample of 2.12 g (7.00
mmol) of lithium [1-(p-tolylamino)-2,2-dimethylpropyl]cyclo-
pentadienide (14a ) was dissolved in 50 mL of THF and treated
with 756 mg (7.00 mmol) of LDA in 30 mL of THF at 0 °C for
3 h. The solvent was removed, and the product was solidified
by several treatments of the remaining oil with 20 mL of
pentane and subsequent evaporation to give 1.34 g (87%, 6.10
1
°C after several days. H NMR (200.13 MHz, THF-d8, 298 K):
δ 7.04 (m, 2H, m-Ph H), 6.77 (m, 2H, o-Ph H), 6.52 (m, 1H,
p-Ph H), 6.42, 6.03 (each m, each 1H, Cp H), 6.20 (m, 2H, Cp
1
3
mmol) of 6c. H NMR (200.13 MHz, THF-d8, 298 K): δ 6.38
H), 4.97 (q, J ) 6.2 Hz, 1H, CH), 3.08, 3.06 (each s, each 6H,
3
(m, 2H, tol H), 6.05 (b, 2H, tol H), 5.63 (b, 4H, Cp H), 4.05 (s,
1H, CH), 2.01 (s, 3H, tol CH3), 0.98 (s, 9H, C(CH3)3). 13C{1H}
NMR (50.3 MHz, THF-d8/benzene-d6 1:1, 298 K): δ 161.2 (ipso
tol), 129.9, 129.3, 115.7 (tol), 102.7, 101.8 (Cp), (C-6), 37.5 (C-
7), 28.8 (C-8), 20.2 (tol CH3). 7Li NMR (232.8 MHz, THF-d8,
298 K): δ -3.5 (br).
NCH3), 1.45 (d, J ) 6.2 Hz, 3H, CCH3). 13C{1H} NMR (50.3
MHz, THF-d8, 298 K): δ 152.6 (ipso Ph), 129.3 (Ph), 118.2,
116.1, 115.4, 115.1, 113.6, 113.4, 113.2 (Ph and Cp), 53.0 (CH),
49.1, 47.4 (both NCH3), 17.1 (CCH3). Anal. Calcd for C17H25N3-
Ti (319.3): C, 63.95; H, 7.89; N, 13.16. Found: C, 63.88; H,
8.18; N, 13.52.
P r ep a r a t ion of Dilit h iu m [1-(ter t-Bu t yla m id o)-2,2-
d im eth ylp r op yl]cyclop en ta d ien id e (6d ). A sample of 1.20
g (5.64 mmol) of lithium [1-(tert-butylamino)-2,2-dimethyl-
propyl]cyclopentadienide (14b) in 30 mL of THF was treated
with 3.70 mL of a 1.52 M solution of tert-butyllithium in
hexane at -78 °C. The solvent was removed after 12 h reaction
X-r a y Cr ysta l Str u ctu r e An a lysis of 2b. Crystal data are
as follows: formula C17H25N3Ti, Mr ) 319.30, orange crystal,
0.35 × 0.20 × 0.10 mm, a ) 8.164(1) Å, b ) 22.073(1) Å, c )
10.037(1) Å, â ) 113.41(1)°, V ) 1659.8(3) Å3, Fcalcd ) 1.278 g
cm-3, µ ) 5.13 cm-1, empirical absorption correction via
SORTAV (0.841 e T e 0.951), Z ) 4, monoclinic, space group

1040 Organometallics, Vol. 21, No. 6, 2002
Kunz et al.
P21/c (No. 14), λ ) 0.710 73 Å, T ) 198 K, ω and æ scans, 6561
reflections collected ((h, (k, (l), (sin θ)/λ ) 0.65 Å-1, 3754
independent (Rint ) 0.021) and 3220 observed reflections (I g
2σ(I)), 195 refined parameters, R1 ) 0.036, wR2 ) 0.087,
maximum residual electron density 0.25 (-0.25) e Å-3, hydro-
gens calculated and refined as riding atoms.
Cl2Zr(NEt2)2(THF)2 (7b; 450 mg, 1 mmol) was dissolved in 50
mL of THF and treated with a solution of 325 mg (1 mmol) of
dilithium [1-(p-tolylamido)-2,2-dimethylpropyl]cyclopentadi-
enide (6c) in 30 mL of tetrahydrofuran for 2 h. Evaporation of
the solvent, addition of 40 mL of pentane, and filtration of LiCl,
followed by removal of pentane, led to a brown oily product,
which was dried in vacuo to give 313 mg (0.66 mmol, 66%) of
P r ep a r a tion of Bis(d ieth yla m id o)[η5-[1-(p h en yla m i-
d o)eth yl]cyclop en ta d ien yl-KN]zir con iu m (2c). A solution
of 2.50 g (5.6 mmol) of Cl2Zr(NEt2)2(THF)2 (7b) in 100 mL of
THF was treated with 1.50 g (5.6 mmol) of dilithium [1-(phe-
nylamido)ethyl]cyclopentadienide (6a ), dissolved in 60 mL of
THF at 0 °C. The mixture was stirred for 2 h, and the solvent
was removed subsequently. A 60 mL portion of pentane was
added to the oily residue, and LiCl was filtered by means of a
frit. The solvent was evaporated, and the remaining brown
oil was dried in vacuo to yield 1.60 g (3.84 mmol, 69%) of 2c.
1H NMR (599.8 MHz, benzene-d6, 298 K): δ 7.26 (m, 2H,
m-Ph), 6.87 (m, 2H, o-Ph), 6.74 (m, 1H, p-Ph), 6.31, 6.00 (m,
1
2f. H NMR (599.8 MHz, benzene-d6, 298 K): δ 6.98 (m, 2H,
m-tol H), 6.94 (m, 2H, o-tol H), 6.38, 5.93 (each m, each 1H,
Cp H), 6.10, 6.07 (each m, each 1H, Cp H), 4.96 (s, 1H, CH),
3.31, 3.28, 3.19, 3.08 (each m, each 2H, NCH2), 2.19 (s, 3H, tol
CH3), 1.19 (s, 9H, C(CH3)3), 1.06 (t, 3J ) 4.8 Hz, 6H, NCH2CH3),
0.65 (t, 3J ) 4.8 Hz, 6H, NCH2CH3). 13C{1H} NMR (150.8 MHz,
benzene-d6, 298 K): δ 152.3 (ipso tol), 129.7 (m-tol), 127.4 (p-
tol), 119.0 (o-tol), 115.5 (Cp), 113.0 (Cp), 112.8 (ipso Cp), 111.6
(Cp), 109.7 (Cp), 66.2 (CH), 43.6, 43.2 (both NCH2), 38.7
(C(CH3)3), 28.8 (C(CH3)3), 20.8 (tol CH3), 15.7, 15.3 (both
NCH2CH3). Anal. Calcd for C25H41N3Zr (474.9): C, 63.23; H,
8.70; N, 8.85. Found: C, 63.03; H, 8.01; N, 8.34.
P r ep a r a t ion of Bis(d iet h yla m id o)[η5-[1-(ter t-b u t yl-
a m id o)-2,2-d im eth ylp r op yl]cyclop en ta d ien yl-KN]zir con -
iu m (2g). A solution containing 219 mg (1 mmol) of dilithium
[1-(tert-butylamido)-2,2-dimethylpropyl]cyclopentadienide (6d )
in 50 mL of THF was added to a solution of 450 mg (1 mmol)
of Cl2Zr(NEt2)2(THF)2 (7b) in 50 mL of THF at 0 °C and stirred
for 2 h. The solvent was evaporated, 50 mL of pentane was
added, and LiCl was removed by filtration. The product was
isolated as a pale green oil (313 mg, 0.71 mmol, 71%) after
evaporation of the solvent. 1H NMR (599.8 MHz, dichlo-
romethane-d2, 298 K): δ 6.30, 5.73 (each m, each 1H, Cp H),
6.13, 5.99 (each m, each 1H, Cp H), 4.40 (s, 1H, CH), 3.40,
3.19, 3.14, 3.07 (each m, each 2H, NCH2), 1.30 (s, 9H, NC-
(CH3)3), 1.19 (s, 9H, CC(CH3)3), 0.96 (t, 3J ) 4.8 Hz, 6H,
NCH2CH3), 0.92 (t, 3J ) 4.8 Hz, 6H, NCH2CH3). 13C{1H} NMR
(150.8 MHz, dichloromethane-d2, 298 K): δ 113.8 (Cp), 112.6
(Cp) 110.6 (Cp), 107.6 (Cp), 68.6 (CH), 55.2 (NC(CH3)3), 45.2,
42.1 (both NCH2), 35.6 (CC(CH3)3), 31.1 (NC(CH3)3), 29.7 (CC-
(CH3)3), 15.4, 13.9 (both NCH2CH3), ipso Cp not observed. Anal.
Calcd for C22H43N3Zr (440.8): C, 59.94; H, 9.83; N, 9.53.
Found: C, 60.01; H, 10.11; N, 10.15.
3
each 1H, Cp), 6.07 (m, 2H, Cp), 5.00 (q, J HH ) 6.6 Hz, 1H,
6-H), 3.33, 3.24, 3.19, 3.07 (each m, each 2H, NCH2), 1.52 (d,
3J HH ) 6.6 Hz, 3H, 7-H), 1.00 (t, 3J HH ) 6.6 Hz, 6H, NCH2CH3),
3
0.77 (t, J HH ) 6.6 Hz, 6H, NCH2CH3). 13C{1H} NMR (150.8
MHz, benzene-d6, 298 K): δ 152.0 (ipso-Ph), 129.2 (m-Ph),
117.1 (p-Ph), 115.1 (o-Ph), 114.3, 111.6, 111.2, 109.6 (Cp), 51.4
(C-6), 43.8, 43.0 (NCH2), 17.8 (C-7), 16.1, 15.9 (NCH2CH3).
Anal. Calcd for C21H33N3Zr (418.7): C, 60.23; H, 7.94; N, 10.04.
Found: C, 59.28; H, 8.32; N, 9.41.
P r epar ation of Bis(dieth ylam ido)[η5-[1-[(ph en ylam ido)-
p-tolylm eth yl]cyclop en ta d ien yl-KN]zir con iu m (2d ). To a
stirred solution of 900 mg (2 mmol) of Cl2Zr(NEt2)2(THF)2 (7b)
in 50 mL of THF was added a solution of 548 mg of dilithium
[1-[(phenylamido)-p-tolylmethyl]cyclopentadienide (6b) in 50
mL of THF at 0 °C. The solvent was removed after 2 h reaction
time, and the oily residue was treated with 50 mL of pentane.
After filtration of LiCl and evaporation of the solvent, 741 mg
(1.5 mmol, 75%) of the brown oily product was obtained. 1H
NMR (599.8 MHz, benzene-d6, 298 K): δ 7.37 (m, 2H, o-tol
H), 7.18 (m, 2H, m-Ph H), 7.02 (m, 2H, m-tol H), 6.91 (m, 2H,
o-Ph H), 6.70 (m, 1H, p-Ph H), 6.14, 5.90 (each m, each 1H,
Cp H), 6.00, 5.96 (each m, each 1H, Cp H), 6.03 (s, 1H, CH),
3.38, 3.37, 3.28, 3.16 (m, each 2H, NCH2), 2.12 (s, 3H, tol CH3),
P r ep a r a t ion of Bis(d iet h yla m id o)[η5-1-[(ter t-b u t yl-
amido)methyl]-2,3,4,5-tetramethylcyclopentadienyl-KN]zir-
con iu m (2h ). A sample of 219 mg (1 mmol) of dilithium
1-[(tert-butylamido)methyl]-2,3,4,5-tetramethylcyclopentadien-
ide (6e) was suspended in 50 mL of THF and added to a
solution of 450 mg (1 mmol) of Cl2Zr(NEt2)2(THF)2 (7b) in 50
mL of THF at 0 °C. A clear, colorless solution was obtained
after 30 min. The mixture was stirred for 90 min before the
solvent was removed. Addition of 40 mL of pentane followed
by filtration and evaporation of the solvent gave 290 mg (0.66
mol, 66%) of the colorless, oily product. 1H NMR (200.13 MHz,
THF-d8, 298 K): δ 4.34 (s, 2H, CH), 3.52-3.20 (m, 8H, NCH2),
2.08 (s, 6H, Cp-CH3), 2.06 (s, 6H, Cp-CH3), 1.15 (s, 9H,
3
3
1.01 (t, J ) 6.6 Hz, 6H, NCH2CH3), 0.87 (t, J ) 6.6 Hz, 6H,
NCH2CH3).13C{1H} NMR (150.8 MHz, benzene-d6, 298 K): δ
152.2 (ipso Ph), 139.7 (p-tol), 136.2 (ipso tol), 129.4 (m-tol),
129.1 (m-Ph), 127.0 (o-tol), 117.2 (p-Ph), 115.4 (o-Ph), 114.4
(ipso Cp), 114.3, 114.0 (both Cp), 111.0, 110.5 (both Cp), 60.2
(CH), 43.7, 43.1 (both NCH2), 21.1 (tol-CH3), 16.0 (NCH2CH3).
Anal. Calcd for C27H37N3Zr (494.8): C, 65.54; H, 7.53; N, 8.49.
Found: C, 65.85; H, 7.97; N, 8.52.
Syn th esis of Bis(d im eth yla m id o)[η5-[1-(p-tolyla m id o)-
2,2-d im eth ylp r op yl]cyclop en ta d ien yl-KN]tita n iu m (2e).
A solution of 231 mg (1.12 mmol) of Cl2Ti(NMe2)2 (7c) in 50
mL of THF was treated with a solution of 370 mg (1.12 mmol)
of dilithium [1-(p-tolylamido)-2,2-dimethylpropyl]cyclopenta-
dienide (6c) in 40 mL of THF at 0 °C. After 2 h the solvent
was removed, 40 mL of pentane was added, and LiCl was
removed by filtration. After evaporation of the solvent, the
residue was dried in vacuo to obtain 276 mg (0.80 mmol, 71%)
3
C(CH3)3), 0.97 (t, J ) 4.8 Hz, 12H, NCH2CH3). 13C{1H} NMR
(50.3 MHz, THF-d8, 298 K): δ 119.5 (ipso Cp), 55.6 (NC(CH3)3),
43.5 (NCH2CH3), 41.9 (NCH2), 29.4 (NC(CH3)3), 15.2 (NCH2-
CH3), 11.2, 10.5 (both Cp-CH3). Anal. Calcd for C22H43N3Zr
(440.8): C, 59.94; H, 9.83; N, 9.53. Found: C, 59.10; H, 10.54;
N, 9.67.
Rea ction of Bis(d ieth yla m id o)[η5-1-[(ter t-bu tyla m id o)-
m et h yl]-2,3,4,5-t et r a m et h ylcyclop en t a d ien yl-KN]zir co-
n iu m (2h ) w ith Me3SiCl: F or m a tion of 15. A sample of
500 mg (1.13 mmol) of bis(diethylamido)[η5-1-{(tert-butylami-
do)methyl]-2,3,4,5-tetramethylcyclopentadienyl-κN]zirconi-
um (2h ) was dissolved in 50 mL of THF and treated with 8
equiv (980 mg, 9.02 mmol) of Me3SiCl at room temperature.
The mixture was stirred for 12 h, the solvent was removed in
vacuo, and the pale yellow residue was analyzed by NMR
spectroscopy. As determined by integration, only ca. 40% of
product had been formed. 1H NMR (200.13 MHz, THF-d8, 298
1
of a dark red powder. H NMR (599.8 MHz, benzene-d6, 298
K): δ 7.02 (m, 2H, m-tol), 6.99 (m, 2H, o-tol), 6.16, 5.73 (each
m, each 1H, 2-H and 5-H), 6.12, 5.83 (each m, each 1H, 3-H
and 4-H), 4.85 (s, 1H, 6-H), 3.02, 2.87 (each s, each 6H, NCH3),
2.19 (s, 3H, tol CH3), 1.14 (s, 9H, 8-H). 13C{1H} NMR (150.8
MHz, benzene-d6, 298 K): δ 154.0 (ipso tol), 129.1 (m-tol), 128.5
(p-tol), 119.2 (o-tol), 116.7, 114.8 (C-2 and C-5), 114.8 (C-1),
114.7, 111.3 (C-3 and C-4), 68.1 (C-6), 48.9, 47.0 (NCH3), 38.0
(C-7), 28.6 (C-8), 20.8 (tol CH3). Anal. Calcd for C21H33N3Ti
(375.4): C, 67.19; H, 8.86; N, 11.19. Found: C, 67.90; H, 8.24;
N, 10.99.
P r ep a r a tion of Bis(d ieth yla m id o)[η5-[1-(tolyla m id o)-
2,2-d im eth ylp r op yl]cyclop en ta d ien yl-KN]zir con iu m (2f).

Ti and Zr Ziegler-Natta Catalyst Systems
Organometallics, Vol. 21, No. 6, 2002 1041
K): δ 4.45 (s, 2H, CH2), 2.12, 2.06 (each s, each 6H, Cp-CH3),
1.10 (s, 9H, C(CH3)3).
and 20 mL of a 10% solution of MAO in toluene and then
thermostated for 1 h and the solution saturated with ethene
(at 1 bar) for 30 min. The catalyst was dissolved in toluene
and directly injected in the autoclave. The polymerization
reaction was stopped by quenching with 20 mL of aqueous HCl/
methanol (1:1 v/v). The reaction mixture was poured into HCl
(100 mL) and stirred overnight. The mixture was filtered,
washed with water, and dried at 80 °C in vacuo overnight.
P olym er Ch a r a cter iza tion s. 13C NMR spectra of copoly-
mer samples (100 mg) were obtained in benzene-d6 (0.5 mL)
at 25 °C (oils) or tetrachloroethane-d2 (0.5 mL) at 80 °C (solids).
Melting point analysis of the polyethylene samples was carried
out on a DSC. The ethene:1-octene ratio was determined by
integration of 13C NMR signals (see Figure 4):
X-r a y Cr ysta l Str u ctu r e An a lysis of 15. After several
days single crystals were obtained in the NMR tube, which
were analyzed by X-ray diffraction as the hydrolyzed product
15. Crystal data are as follows: formula C28H48N2OCl4Zr2‚2CH2-
Cl2, Mr ) 922.78, light yellow crystal, 0.10 × 0.10 × 0.05 mm,
a ) 20.865(1) Å b ) 9.373(1) Å, c ) 20.754(1) Å, V ) 4058.8(5)
Å3, Fcalcd ) 1.510 g cm-3, µ ) 10.66 cm-1, empirical absorption
correction via SORTAV (0.901 e T e 0.949), Z ) 4, ortho-
rhombic, space group Pbcn (No. 60), λ ) 0.710 73 Å, T ) 198
K, ω and æ scans, 7715 reflections collected ((h, (k, (l), (sin
θ)/λ ) 0.62 Å-1, 4103 independent (Rint ) 0.065) and 2655
observed reflections (I g 2σ(I)), 202 refined parameters, R1 )
0.061, wR2 ) 0.139, maximum residual electron density 0.80
(-0.65) e Å-3, hydrogens calculated and refined as riding
atoms.
a ) I(Cδδ+, C3B)/I(CRδ+, C6B) ) I(Cδδ+, C3B)/I(Câδ+, C5B) (1)
Data sets were collected with a Nonius KappaCCD diffrac-
ethene/1-octene ) [(3a - 1)/2] + 2
(2)
tometer, equipped with
a Nonius FR591 rotating anode
generator. Programs used: data collection, COLLECT (Nonius
BV, 1998); data reduction, Denzo-SMN;38 absorption correc-
tion, SORTAV;39 structure solution, SHELXS-97;40 structure
refinement, SHELXL-97;41 graphics, DIAMOND.42
Selected 13C NMR data (for polymer number, see Table 2) for
sample 3 (solid) (50.3 MHz, tetrachlorethane-d2, 353 K): δ 37.6
(C7), 34.0 (CRδ+, C6B), 31.8 (Cγδ+, C4B), 29.6 (Cδδ+, C3B), 26.9
(Câδ+, C5B), 22.5 (C2B), 13.9 (C1B). Integration of signals (Cδδ+
3B), (CRδ+, C6B), and (Câδ+, C5B) leads to an ethene:1-octene
ratio of 13:1. 13C{1H} NMR for sample 13 (oil) (50.3 MHz,
benzene-d6, 298 K): δ 38.0 (C7), 34.3 (CRδ+, C6B), 32.4 (Cγδ+
,
P olym er iza tion Rea ction s. (a ) Eth en e P olym er iza tion .
A glass autoclave was charged with 200 mL of toluene and 20
mL of a 10% solution of MAO in toluene and then thermostated
for 1 h and the solution saturated with ethene (at 1 bar) for
30 min. The catalyst was dissolved in toluene and directly
injected in the autoclave. The polymerization reaction was
stopped by quenching with 20 mL of aqueous HCl/methanol
(1:1 v/v). The resulting polymer was collected by filtration,
washed subsequently with HCl and water, and dried at 80 °C
in vacuo overnight.
C
,
C
4B), 30.3 (Cδδ+, C3B), 27.3 (Câδ+, C5B), 23.1 (C2B), 14.4 (C1B).
Integration of signals (Cδδ+, C3B), (CRδ+, C6B), and (Câδ+, C5B
leads to an ethene:1-octene ratio of 5.5:1.
)
Ackn owledgm en t. Financial support from the Fonds
der Chemischen Industrie and the Deutsche For-
schungsgemeinschaft is gratefully acknowledged. We
thank Dr. J o¨rg Schottek for helping us with the molec-
ular weight determination.
(b) Eth en e-1-Octen e Cop olym er iza tion . A glass auto-
clave was charged with 30 mL of toluene, 50 mL of 1-octene,
(38) Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307-
326.
(39) Blessing, R. H. Acta Crystallogr. 1995, A51, 33-37. Blessing,
R. H. J . Appl. Crystallogr. 1997, 30, 421-426.
(40) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467-473.
(41) Sheldrick, G. M. SHELXL-97; Universita¨t Go¨ttingen, Go¨ttingen,
Germany, 1997.
(42) Brandenburg, K. DIAMOND; Universita¨t Bonn, Bonn, Ger-
many, 1997).
Su p p or tin g In for m a tion Ava ila ble: Details of the X-ray
crystal structure analyses of the complexes cis-2a , 2b, and 15.
This material is available free of charge via the Internet at
http://pubs.acs.org.
OM010624T