Synthesis of bis(1,2,3-substituted cyclopentadienyl)zirconium dichloride derivatives and their use in ethylene polymerization

Article abstract of DOI:10.1016/s0022-328x(99)00307-1

Catalytic Pauson-Khand reaction products with norbornadiene could be effectively transformed to trisubstituted cyclopentadienes, which have been used to synthesize a series of unbridged bis(1-R′-2-R-3-R′-trisubstituted cyclopentadienyl)zirconium dichlorid

Full text of DOI:10.1016/s0022-328x(99)00307-1

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 587 (1999) 181–190
Synthesis of bis(1,2,3-substituted cyclopentadienyl)zirconium
dichloride derivatives and their use in ethylene polymerization
Bun Yeoul Lee a, Jin Wook Han b, Young Keun Chung b,*, Soon W. Lee c
a LG Chem Ltd., Research Park, 104-1 Moonji-dong, Yusung-gu, Taejon 305-380, South Korea
b Department of Chemistry and the Center for Molecular Catalysis, College of Natural Sciences, Seoul National Uni6ersity,
Seoul 151-742, South Korea
c Department of Chemistry, Sung Kyun Kwan Uni6ersity, Suwon 440-746, South Korea
Received 25 March 1999; received in revised form 24 May 1999
Abstract
Catalytic Pauson–Khand reaction products with norbornadiene could be effectively transformed to trisubstituted cyclopentadi-
enes, which have been used to synthesize a series of unbridged bis(1-R%-2-R-3-R%-trisubstituted cyclopentadienyl)zirconium
dichlorides 3 (R=R%=Ph), 4(R=Ph, R%=Me), 21(R=n-Bu, R%=Me), 22(R=t-Bu, R%=Me), 23(R=(CH2)4OMe), R%=Me),
and 24(R=n-Bu, R%=Ph). The crystal structure of 24 was determined by X-ray crystallography. These zirconium complexes in
the presence of methylaluminoxane (MAO) show activities for the polymerization of ethylene. The activities are in the following
order: 21\4\22ꢀ23ꢀCp2ZrCl2\3ꢀ24. The activity of 21 is four times higher than that of Cp2ZrCl2 under similar
conditions. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Ethylene; Polymerization; Pauson–Khand reaction; Zirconocene
tailor the catalytic activity and product properties [5].
However, a limited range of metallocenes containing
such ligands have been prepared and studied due to the
absence of the generalized synthetic method of the
substituted cyclopentadiene. Several years ago, we re-
ported the general method of preparation of 1,2-disub-
stituted and 1,2,3-trisubstituted cyclopentadienyl
ligands via the retro-Diels–Alder reaction of the inter-
molecular Pauson–Khand reaction products (Scheme
1) [6].
1. Introduction
Cyclopentadienyl ligands are one of the most popular
ligands in organometallic chemistry and the develop-
ment of efficient approaches to the generation of highly
substituted or functionalized cyclopentadienyl ligands is
of continuing importance [1]. Substitution or function-
alization of the cyclopentadienyl ring modifies the steric
and electronic properties of the metal center and im-
plies important changes in the structural and chemical
behavior of this type of compound [2]. The chemical
and physical properties of Group 4 bent metallocenes
can be varied over a wide range by modification of the
substituents on the cyclopentadienyl ring [3]. The
Group 4 metallocene compounds have attracted much
attention due to their use as catalyst precursors for the
homogeneous polymerization of olefins [4]. Thus, many
research groups are involved in the design of ligands to
Herein we report the synthesis and characterization
of a series of unbridged bis(1,2,3-trisubstituted cyclo-
pentadienyl)zirconium dichlorides and their use in the
polymerization of ethylene.
2. Experimental
2.1. General considerations
Reactions were carried out under an argon or a
nitrogen atmosphere using standard Schlenk tech-
* Corresponding author. Fax: +82-2-8891567.
E-mail address: ykchung@plaza.snu.ac.kr (Y. Keun Chung)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00307-1

182
B. Yeoul Lee et al. / Journal of Organometallic Chemistry 587 (1999) 181–190
Table 1
analyzing curve. Melting points were measured on a
Thomas Hoover capillary melting point apparatus
6427-H 10 and not corrected. Compounds 1, 2, and 9
were described previously [6,7], but their characteriza-
tion had not been reported in detail. Thus, their charac-
terization is reported here. t-Butylacetylene has been
prepared by the known method [8].
X-ray data collection and structure refinement for 24
Formula
C42H42Cl2Zr
Formula weight
Crystal system
Space group
708.88
Monoclinic
P21/c
19.576(2)
19.129(2)
21.020(5)
97.505(9)
7804(2)
8
1.207
0.444
0.2975
0.2572
10417
,
a (A)
,
b (A)
,
c (A)
2.1.1. Compound 1
White solid; m.p. 150–153°C; H-NMR (CDCl3): l
i (°)
1
3
,
V (A )
Z
7.4–7.1 (m, 15 H), 6.46 (s, 1 H), 3.55 (s, 2 H) ppm.
13C-NMR (CDCl3): l 149.40, 142.51, 141.96, 136.95,
136.67, 136.52, 129.91, 129.34, 128.19, 128.06, 128.01,
127.75, 126.78, 126.71, 126.32 ppm. HRMS (M+) Calc.
294.1409, observed 294.1409.
Dcalc (g cm−3
)
v (mm−1
Tmax
)
Tmin
No. of reflections measured
No. of reflections with I\2|(I)
No. of parameters used
2q range (°)
10033
731
2.1.2. Compound 2
3.5–45.0
1.055
0.565, −0.479
0.0648
0.1516
1
Oil. H-NMR (CDCl3): l 7.39–7.19 (m, 5 H), 5.95
GOF
−3
(m, 1 H), 2.96 (m, 2 H), 1.99 (s, 3 H), 1.88 (m, 3 H)
ppm. 13C-NMR (CDCl3): l 143.72, 142.56, 140.43,
129.70, 128.45, 126.81, 124.73, 44.75, 15.64, 15.08 ppm.
HRMS (M+) Calc. 170.1096, observed 170.1098.
,
Max., min. in Dz (A
)
R
wR2
a
a wR2=S[w(Fo2−Fc2)2]/S[w(Fo2)2]1/2
.
2.1.3. Compound 9
1
niques. Methylaluminoxane (MAO) was purchased
from Akzo (6.4 wt% of Al, MMAO type 4), and all
other reagents were purchased from Aldrich and used
without further purification. Diethyl ether and tetrahy-
drofuran (THF) were distilled from Na and benzoke-
tone. Hexane and toluene were purified by distillation
over Na/K alloys under argon. Ethylene was purchased
from Matheson as high purity grade (99.9%) and dried
by passing through the columns of activated molecular
sieves and copper. 1H- and 13C-NMR spectra were
recorded on a Bruker DPX-300 spectrometer. Elemen-
tal analyses were carried out at Seoul National Univer-
sity on a Carlo Erba EA 1108 elemental analyzer. Gel
permeation chromatograms (GPC) were obtained at
140°C in trichlorobenzene using Waters model 150-C+
GPC and the data were analyzed using a polystyrene
Oil; H-NMR (CDCl3): l 6.18 (m, 1 H), 6.13 (m, 1
H), 3.12 (s, 1 H), 2.74 (s, 1 H), 2.31 (d, 18 Hz, 1 H),
2.13 (m, 1 H), 1.83 (t, 8.0 Hz, 1 H), 1.59–1.20 (m, 8 H),
1.23 (d, 6.5 Hz, 3 H), 1.07 (d, 9.1 Hz, 1 H), 0.89 (t, 6.8
Hz, 3 H) ppm. 13C-NMR (CDCl3): l 219.09, 138.67,
137.87, 61.12, 54.70, 49.12, 47.11, 45.32, 44.93, 40.41,
29.56, 27.48, 23.48, 21.52, 14.39 ppm. Anal. Found: C,
81.97; H, 10.47. C15H22O Anal. Calc.: C, 82.52; H,
10.16%. HRMS (M+) Calc. 218.1671, observed
218.1678.
2.2. General procedure for the Pauson–Khand reaction
of alkyne with norbornadiene
Co2(CO)8 (1 mol%) was added to a solution of
alkyne and norbornadiene in methylene dichloride. The
Scheme 1.

B. Yeoul Lee et al. / Journal of Organometallic Chemistry 587 (1999) 181–190
183
,
Fig. 1. ORTEP drawing of 24, with atom-labeling scheme. Thermal ellipsoids are drawn at the 50% probability level. Selected bond lengths (A) and
angle (°): Zr2ꢀCl3, 2.427(2); Zr2ꢀC51, 2.486(7); Zr2ꢀC52, 2.570(7); C52ꢀC53, 1.433(9); C53ꢀC54, 1.424(10); C51ꢀC55 1.392(9); C53ꢀC67,
1.490(10); C52ꢀC71, 1.486(11); Cl3ꢀZr2ꢀCl4, 99.06(7).
solution was subjected to an appropriate pressure of
CO and heated at 120°C for 1 day. After the solution
was cooled to room temperature (r.t.), it was filtered,
concentrated, and chromatographed on a silica gel
column. After the solvent was removed, the corre-
sponding Pauson–Khand product was obtained.
and 40 ml of CH2Cl2. Column chromatography eluting
with hexane and ethyl acetate (v/v, 10:1) gave 7.0 g of
1
an oily product (67%). H-NMR (CDCl3): l 7.16 (m, 1
H), 6.28 (m, 1 H), 6.20 (m, 1 H), 2.90 (s, 1 H), 2.71 (br
s, 1 H), 2.66 (s, 1 H), 2.28 (d, 5.2 Hz, 1 H), 2.13 (t, 8.0
Hz, 2 H), 1.46–1.27 (m, 6 H), 0.91 (t, 7.3 Hz, 3 H)
ppm. 13C-NMR (CDCl3): l 210.42, 159.14, 151.12,
138.75, 52.89, 47.97, 43.95, 43.30, 41.52, 30.28, 25.04,
22.88, 14.24 ppm. Anal. Found: C, 82.77; H, 9.21.
C14H18O Anal. Calc.: C, 83.12; H, 8.97%.
2.3. Compound 3
Compound 3 was prepared by using the same
methodology as described for 21 (see Section 2.17). The
reaction time was 7 days instead of 40 h. Products were
extracted with hot toluene. Yield: 54%. Yellow solid.
2.4.2. Preparation of 6
Reaction conditions are as follows: 2.9 g of t-butyl-
acetylene (35 mmol), 7.6 ml of norbornadiene (70
mmol), 0.12 g of Co2(CO)8 (0.35 mmol), 30 atm of CO,
and 40 ml of CH2Cl2. Column chromatography eluting
with hexane and ethyl acetate (v/v, 10:1) gave 4.0 g of
1
M.p. 300°C (dec.). H-NMR (CDCl3): l 7.24–7.10 (m,
15 H), 6.41 (s, 2 H) ppm. Anal. Found: C, 73.70; H,
4.52. C46H34Cl2Zr Anal. Calc.: C, 73.78; H, 4.58%.
1
2.4. Compound 4
a white solid as a product (57%). H-NMR (CDCl3): l
7.12 (m, 1 H), 6.28 (m, 1 H), 6.19 (m, 1 H), 2.89 (s, 1
H), 2.63 (m, 2 H), 2.24 (d, 5.3 Hz, 1 H), 1.33–1.17 (m,
2 H), 1.18 (s, 9 H) ppm. 13C-NMR (CDCl3): l 207.10,
156.27, 154.73, 136.43, 135.01, 51.36, 44.34, 41.81,
41.06, 38.94, 30.07, 26.28 ppm. Anal. Found: C, 83.05;
H, 9.17. C14H18O Anal. Calc.: C, 83.12; H, 8.97%.
Compound 4 was prepared by using the same
methodology as described for 16 (see Section 2.12).
Products were extracted with hot toluene and hexane
solution (v/v, 3:1). Yield: 54%. Light yellow solid. M.p.
1
221–222°C. H-NMR (CDCl3): l 7.40–7.25 (m, 5 H),
5.91 (s, 2 H), 2.16 (s, 6 H) ppm. 13C-NMR (75 MHz,
CDCl3): l 133.53, 131.44, 130.97, 130.61, 127.98,
127.19, 108.60, 15.69 ppm. Anal. Found: 61.98; H, 5.39.
C26H26Cl2Zr. Anal. Calc.: C, 62.38; H, 5.23%.
2.4.3. Preparation of 7
The reaction conditions are as follows: 4.7 ml
of 5-hexyn-1-ol (39 mmol), 8.6 ml of norbornadiene
(80 mmol), 0.14 g of Co2(CO)8 (0.40 mmol), 30 atm of
CO, and 40 ml of CH2Cl2. Column chromatography
eluting with hexane and ethyl acetate (v/v, 4:1) gave 7.6
2.4.1. Preparation of 5
Reaction conditions are as follows: 4.6 ml of
1-hexyne (40 mmol), 8.6 ml of norbornadiene (80
mmol), 0.14 g of Co2(CO)8 (0.40 mmol), 30 atm of CO,
1
g of an oily product (89%). H-NMR (CDCl3): l 7.19
(m, 1 H), 6.28 (m, 1 H), 6.21 (m, 1 H), 3.68 (br s,

184
B. Yeoul Lee et al. / Journal of Organometallic Chemistry 587 (1999) 181–190
Table 2
Table 2 (Continued)
Fractional atomic coordinates (×104) and equivalent isotropic dis-
2
3
a
,
placement coefficients (A ×10 ) for 24
x
y
z
Ueq
a
x
y
z
Ueq
C64
C65
C66
C67
C68
C69
C70
C71
C72
C73
C74
C75
C76
C77
C78
C79
C80
C81
C82
C83
C84
C85
C86
C87
C88
C89
C90
C91
C92
−1820(5)
−1607(5)
−924(4)
782(4)
8858(7)
8476(6)
8467(5)
1900(6)
1420(6)
1321(4)
1824(4)
1209(4)
1313(5)
667(8)
1497(4)
949(5)
862(6)
1324(7)
1870(6)
1970(5)
4250(3)
4394(4)
5003(4)
5466(4)
5321(4)
4718(4)
3455(3)
3896(5)
4156(6)
4639(7)
2198(3)
1960(3)
1529(3)
1306(4)
1527(4)
1965(4)
117(4)
120(4)
96(3)
73(2)
100(3)
121(3)
211(7)
76(2)
98(3)
122(4)
133(5)
123(4)
102(3)
63(2)
76(2)
92(3)
95(3)
96(3)
74(2)
63(2)
107(3)
141(4)
170(5)
55(2)
62(2)
71(2)
84(2)
90(3)
72(2)
Zr1
Cl1
Cl2
C1
C2
C3
C4
C5
C6
C7
6191(1)
7316(1)
6349(1)
5586(4)
6185(4)
6763(4)
6498(4)
5817(4)
5048(3)
5132(4)
5658(4)
5894(3)
5531(3)
4848(4)
4620(4)
3911(5)
3462(5)
3704(5)
4396(4)
6212(5)
6245(9)
6410(2)
6463(17)
7510(4)
7813(4)
8520(5)
8867(5)
8565(5)
7889(4)
5843(4)
5326(5)
5491(9)
6165(9)
6690(7)
6531(5)
6337(4)
5876(4)
6274(5)
5805(6)
5593(4)
6223(4)
6265(5)
5687(6)
5063(6)
5007(5)
1139(1)
1383(1)
2294(1)
1266(4)
1451(4)
841(4)
10021(1)
10476(1)
8837(1)
9708(5)
9278(4)
9745(5)
10456(5)
10439(5)
10531(5)
10007(5)
10199(4)
10879(4)
11094(4)
9477(5)
8963(5)
8783(5)
9116(6)
9609(6)
9797(5)
8509(5)
8387(9)
7790(2)
8086(17)
9549(5)
9031(5)
8845(6)
9194(7)
9710(7)
9891(5)
9818(4)
9514(5)
9162(7)
9100(7)
9355(6)
9720(5)
11352(4)
11787(5)
12183(5)
12619(7)
11766(4)
12067(4)
12706(5)
13044(5)
12758(6)
12125(6)
8230(1)
9250(1)
7756(1)
8214(4)
8901(4)
9242(4)
8736(4)
8102(4)
7694(4)
8003(4)
7629(4)
7070(4)
7117(4)
8827(4)
9208(4)
9227(5)
2958(1)
2813(1)
2574(1)
3899(4)
3994(3)
4090(4)
4077(4)
3970(4)
2593(4)
2161(4)
1785(4)
2009(4)
2519(4)
3806(4)
3367(4)
3264(5)
3606(5)
4047(5)
4148(4)
4087(4)
4864(8)
4920(2)
5828(16)
4266(4)
3946(5)
4157(6)
4665(6)
4957(5)
4768(4)
1235(4)
792(5)
65(1)
78(1)
94(1)
77(2)
72(2)
79(2)
81(2)
80(2)
76(2)
82(2)
72(2)
68(2)
71(2)
75(2)
85(2)
100(3)
106(3)
110(3)
95(3)
102(3)
188(6)
510(3)
425(18)
81(2)
99(3)
114(3)
112(4)
113(4)
90(3)
79(2)
109(3)
142(5)
143(5)
129(4)
103(3)
78(2)
92(3)
112(3)
150(4)
73(2)
80(2)
99(3)
109(3)
117(4)
103(3)
55(1)
77(1)
77(1)
67(2)
69(2)
64(2)
63(2)
69(2)
56(2)
60(2)
59(2)
55(2)
55(2)
71(2)
72(2)
95(3)
10008(4)
10417(5)
11207(5)
11608(9)
9227(4)
9115(5)
9447(7)
9875(8)
9983(6)
9652(5)
7912(4)
7962(4)
8150(5)
8298(5)
8257(5)
8070(4)
6570(4)
6029(5)
5506(6)
5037(7)
6514(4)
6160(4)
5618(4)
5428(4)
5781(5)
6311(4)
788(5)
796(6)
776(9)
2128(4)
2416(4)
3032(6)
3352(6)
3088(5)
2476(5)
1229(4)
1933(4)
2222(5)
1815(6)
1114(6)
823(4)
1585(3)
1271(5)
1764(6)
1384(7)
436(3)
C8
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
C23
C24
C25
C26
C27
C28
C29
C30
C31
C32
C33
C34
C35
C36
C37
C38
C39
C40
C41
C42
Zr2
Cl3
Cl4
C51
C52
C53
C54
C55
C56
C57
C58
C59
C60
C61
C62
C63
967(3)
851(4)
180(5)
−351(4)
−229(4)
a Equivalent isotropic U defined as one third of the trace of the
orthogonalized Uij tensor.
259(6)
161(6)
599(6)
2 H), 2.91 (s, 1 H), 2.71 (br s, 1 H), 2.67 (s, 1 H), 2.29
(m, 1 H), 2.21 (m, 2 H), 1.59 (m, 3 H), 1.37 (m, 2 H),
1.20 (d, 8.5 Hz, 1 H) ppm. 13C-NMR (CDCl3): l
209.77, 158.99, 150.03, 138.05, 136.52, 61.65, 52.19,
47.32, 47.30, 42.55, 40.79, 31.98, 24.34, 23.76 ppm.
HRMS (M+) Calc. 218.1307, observed 218.1311.
1130(5)
1658(4)
1153(4)
715(5)
233(6)
2867(4)
3083(4)
3401(5)
3512(5)
3312(6)
2993(5)
2543(1)
3223(1)
2608(1)
1382(3)
1562(3)
1713(3)
1651(3)
1435(3)
3606(3)
3287(3)
2742(3)
2682(3)
3228(3)
1733(4)
2222(4)
2297(5)
2.5. Methylation of 7 to 8
A total of 0.31 g of NaH (2.0 equivalents) was added
2to a solution of 7 (1.4 g, 6.6 mmol) in 15 ml of THF
at r.t. under N2. After the solution was stirred for 30
min, MeI was added. After the resulting solution was
stirred for 12 h, the reaction mixture was poured into
water and extracted with diethyl ether (50 ml×2). The
organic layer was separated, dried over anhydrous
MgSO4, concentrated, and chromatographed on a silica
gel column eluting with hexane and ethyl acetate (v/v,
4:1). After the solvent was removed, an oily product
302(4)
573(4)
886(3)
278(3)
66(3)
542(3)
1045(3)
1
was obtained in 90% yield (1.4 g). H-NMR (CDCl3): l
7.18 (m, 1 H), 6.28 (m, 1 H), 6.20 (m, 1 H), 3.38 (t, 6.1
Hz, 2 H), 3.33 (s, 3 H), 2.90 (s, 1 H), 2.71 (br s, 1 H),
2.66 (s, 1 H), 2.28 (d, 5.0 Hz, 1 H), 2.18 (t, 7.4 Hz, 2
H), 1.61–1.54 (m, 4 H), 1.37 (d, 9.3 Hz, 1 H), 1.20 (d,
9.3 Hz, 1 H) ppm. 13C-NMR (CDCl3): l 210.32, 159.36,
−440(4)
−664(4)
−1352(4)

B. Yeoul Lee et al. / Journal of Organometallic Chemistry 587 (1999) 181–190
185
150.75, 138.75, 137.36, 72.79, 58.96, 52.88, 48.01, 43.95,
43.27, 41.53, 29.76, 25.11, 24.70 ppm. Anal. Found: C,
77.54; H, 8.94. C15H20O Calc.: C, 77.55; H, 8.68.
7.4–7.1 9m, 5 H), 6.15 (dd, 5.6, 2.9 Hz, 1 H), 6.08
(dd, 5.6, 2.9 Hz, 1 H), 3.21 (br s, 1 H), 2.81 9br s, 1
H), 2.86–2.76 (m, 1 H), 2.52–2.45 (m, 2 H), 2.28 (t,
8.3 Hz, 1 H), 1.7–0.9 (m, 8 H), 0.76 (t, 6.9 Hz, 3 H)
ppm. 13C-NMR (CDCl3, 75 MHz): l 217.18, 114.68,
138.22, 137.47, 128.70, 127.99, 127.50, 126.61, 124.52,
60.59, 54.14, 52.28, 49.83, 46.60, 44.64, 44.57, 28.76,
27.14, 22.73, 13.76 ppm. HRMS (M+) Calc. 280.1827,
observed 280.1823.
2.6. Compound 10
To a Schlenk flask containing CuI (4.74 g, 24.9
mmol) and diethyl ether (55 ml) was added MeLi (33
ml, 1.5 M in diethyl ether solution, 50 mmol) at
−20°C. The solution was stirred at −20°C for 30
min and lowered to −78°C. A solution of 5 (4.07 g,
20.1 mmol) in 10 ml of diethyl ether was added via
cannula to the cold solution. The resulting solution
was allowed to warm to r.t.. After the solution was
stirred at r.t. for 3 h, the solution was poured into
chilled water (50 ml). The mixture was filtered over
celite and the etheral solution was separated. The
aqueous solution was extracted with diethyl ether (50
ml). The etheral solutions were combined, dried over
anhydrous MgSO4, and evaporated to dryness. Chro-
matography of the residue on a silica gel column elut-
ing with hexane and ethyl acetate (v/v, 5:1) gave a
white solid 10 in 86% yield (3.76 g). M.p. 62–63°C.
1H-NMR (CDCl3): l 6.16 (dd, 5.6, 2.9 Hz, 1 H), 6.11
(dd, 5.5, 2.9 Hz, 1 H), 3.09 (br s, 1 H), 2.75 (br s, 1
H), 2.20 (d, 8.7 Hz, 1 H), 2.02–1.98 (m, 1 H), 1.68–
1.60 (m, 2 H), 1.32–1.07 (m, 5 H), 0.99 (s, 9 H) ppm.
13C-NMR (CDCl3, 75 MHz): l 218.75, 138.72, 137.69,
69.93, 54.82, 49.17, 47.75, 45.91, 4461, 37.41, 33.13,
28.55, 25.09 ppm. HRMS (M+) Calc. 218.1671, ob-
served 218.1668. Anal. Found: C, 82.36; H, 10.30.
C15H22O Anal. Calc.: C, 82.52; H, 10.16%.
2.9. Compound 13
A U-shaped quartz tube containing 85 g of quartz
chips was placed in a furnace. One of the glass joints
of the quartz tube was connected to a dropping funnel
containing 9 (5.40 g, 24.9 mmol) and the other joint
was connected to a vacuum line via a trap which was
immersed in a liquid nitrogen bath. As 9 was slowly
dropped to the quartz chip bed, the product and cy-
clopentadiene were produced and immediately col-
lected in a trap. After the addition was completed, the
trap was connected to a aspirator to remove volatile
cyclopentadiene. The remaining liquid was transferred
to a flask and refluxed with 100 ml of 0.5% (w/w)
KOH aqueous solution for 12 h. The product was
extracted with ethyl acetate. The extracted organic so-
lution was dried over anhydrous MgSO4 and the or-
ganic solvent was removed by rotary evaporation.
Product 13 was purified by vacuum distillation
(55–60°C, 0.2 torr). Yield: 2.65 g (70%). 1H-NMR
(CDCl3): l 2.45–2.35 (m, 2 H), 2.35–2.25 (m, 2 H),
2.12 (t, 7.0 Hz, 2 H), 2.00 (s, 3 H), 1.33–1.16 (m, 4
H), 0.84 (t, 7.0 Hz, 3 H) ppm. 13C-NMR (CDCl3, 75
MHz): l 209.76, 170.10, 140.65, 34.25, 31.44, 30.49,
22.68, 22.63, 17.14, 13.82 ppm.
2.7. Compound 11
Compound 11 was prepared by following the proce-
dure outlined for 10 and purified by column chro-
matography eluting with hexane and ethyl acetate
2.10. Compound 14
1
(v/v, 10:1). Yield: 85%. Oil. H-NMR (CDCl3): l6.11
Pyrolysis was done by the same method as the syn-
thesis of 13. However, the isomerization was done as
follows. To the flask containing the pyrolyzed com-
pound (generated by the pyrolysis of 10 (3.19 g, 14.7
mmol)) was added MeOH (50 ml) and NaOMe (0.50
g). The mixture was heated at reflux for 12 h. Vacuum
distillation (35–40°C, 0.2 torr) gave the product in
(dd, 5.6, 2.9 Hz, 1 H), 6.06 (dd, 5.6, 2.9 Hz, 1 H), 3.30
(t, 6.4 Hz, 2 H), 3.25 (s, 3 H), 3.04 (br s, 1 H), 2.67
(br s, 1 H), 2.23 (d, 9.0 Hz, 1 H), 2.22–2.05 (m, 1 H),
1.76 (t, 8.0 Hz, 1 H), 1.6–1.2 (m, 8 H), 1.16 (d, 6.5
Hz, 3 H), 1.00 (d, 9.1 Hz, 1 H) ppm. 13C-NMR
(CDCl3, 75 MHz): l 218.10, 138.18, 137.34, 72.55,
60.55, 58.42, 54.15, 48.65, 46.58, 44.83, 44.38, 39.94,
29.90, 27.15, 23.54, 20.98 ppm. HRMS (M+H)+
Calc. 249.1855, observed. 249.1857.
1
50% yield. H-NMR spectrum showed about 15% of
the unisomerized compound. However, the mixture
was used for further reaction without trouble. The
analytically pure compound could be obtained by
chromatography on a silica gel column eluting with
pentane and diethyl ether (v/v, 10:1). 1H-NMR
(CDCl3): l 2.43–2.40 (, 2 H), 2.29–2.25 (m, 2 H), 2.20
(s, 3 H), 1.28 (s, 9 H) ppm. 13C-NMR (CDCl3, 75
MHz): l 210.16, 167.78, 145.73, 35.34, 33.97, 33.80,
29.94, 20.08 ppm. HRMS (M+) Calc. 152.1201, ob-
served 152.1195.
2.8. Compound 12
Compound 12 was prepared by following the proce-
dure outlined for 10 except using PhLi instead of
MeLi and purified by eluting with hexane and ethyl
acetate (v/v, 50:1) instead of hexane and ethyl acetate
(v/v, 5:1). Yield: 83%. oil. 1H-NMR (CDCl3): l

186
B. Yeoul Lee et al. / Journal of Organometallic Chemistry 587 (1999) 181–190
1
2.11. Compound 15
ing signals are also present in the H-NMR spectrum.
These peaks are omitted from the following list.
1H-NMR (CDCl3): l 5.81 (s, 1 H), 2.76 (s, 2 H), 2.23
(t, 7.0 Hz, 2 H), 1.93 (s, 6 H), 1.4–1.3 (m, 4 H), 0.92
(t, 6.7 Hz, 3 H) ppm. 13C-NMR (CDCl3, 75 MHz):
l 143.86, 140.46, 136.90, 123.61, 43.74, 32.10, 25.43,
22.81, 14.29, 14.07, 13.75 ppm. HRMS (M+H)+
Calc. 151.1487, observed. 151.1478.
Compound 15 was prepared by using the same
methodology as described above for 13. The product
was purified by vacuum distillation (80–85°C, 0.2
torr). Yield: 65%. 1H-NMR (CDCl3): l 3.29 (t, 6.3
Hz, 2 H), 3.24 (s, 3 H), 2.42–2.38 (m, 2 H),
2.30–2.25 (m, 2 H), 2.12 (t, 7.4 Hz, 2 H), 1.98 (s, 3
H), 1.50–1.32 (m, 4 H) ppm. 13C-NMR (CDCl3, 75
MHz): l 209.45, 170.22, 140.22, 72.51, 58.42, 34.18,
31.40, 29.39, 24.79, 22.63, 17.12 ppm. HRMS (M+)
Calc. 182.1307, observed 182.1305.
2.14. Compound 18
Compound 18 was prepared by using the same
methodology as described above for 17. Purification
of the crude product was done by chromatography
on a silica gel column eluting with hexane and ethyl
acetate (v/v, 10:1). No side product was found. Yield:
2.12. Compound 16
A quartz tube containing 12 (1.127 g, 4.0 mmol)
was connected via a flexible tube to a Schlenk flask.
After the system was purged with argon, the quartz
tube was placed into a furnace whose temperature
has been set at 420°C and the Schlenk flask was im-
mersed in liquid nitrogen bath. After 5 min, the
quartz tube was removed from the furnace and was
cooled to r.t.. Purification of the crude product was
carried out by chromatography on a silica gel column
eluting with hexane and ethyl acetate (v/v, 10:1).
1
76%. H-NMR (CDCl3): l 5.82 (s, 1 H), 2.73 (br s, 2
H), 2.11 (d, 1.7 Hz, 3 H), 2.10 (s, 3 H), 1.29 (s, 9 H)
ppm. 13C-NMR (CDCl3, 75 MHz): l 145.29, 135.73,
126.93, 46.41, 34.76, 31.30, 19.09, 17.20 ppm. HRMS
(M+H)+ Calc. 151.1487, observed 151.1480.
2.15. Compound 19
Compound 19 was prepared by using the same
methodology as described above for 17. Purification
of the crude product was done by chromatography
on a silica gel column eluting with hexane and ethyl
acetate (v/v, 10:1). Product was obtained as an 8:1
mixture with the isomerized product. Yield: 84%.
1H-NMR (CDCl3): l 5.79 (s, 1 H), 3.36 (t, 6.5 Hz, 2
H), 3.30 (s, 3 H), 2.73 (s, 2 H), 2.45 (t, 7.6 Hz, 2 H),
1.91 (s, 6 H), 1.60–1.40 (m, 4 H) ppm. 13C-NMR
(CDCl3, 75 MHz): l 143.58, 139.94, 137.15, 123.62,
72.76, 58.45, 43.66, 29.52, 26.20, 25.31, 14.18, 13.71
ppm. HRMS (M+H)+ Calc. 181.1592, observed
181.1578.
1
Yield: 0.58 g (67%). H-NMR (CDCl3): l 7.45–7.26,
2.88–2.83 (m, 2 H), 2.51–2.46 (m, 2 H), 2.35 (t, 7.8
Hz, 2 H), 1.48–1.22 (m, 4 H), 0.85 (t, 7.2 Hz, 3 H)
ppm. 13C-NMR (CDCl3, 75 MHz): l 209.66, 166.96,
141.25, 136.69, 129.21, 128.58, 127.12, 34.19, 30.38,
29.77, 23.75, 22.89, 13.75 ppm. HRMS (M+) Calc.
214.1358, observed 214.1356.
2.13. Compound 17
To a Schlenk flask containing 13 (0.607 g, 3.99
mmol) in 10 ml of Et2O at −78 °C was added MeLi
(4.0 ml, 1.5 M in Et2O, 6.0 mmol). The solution was
allowed to warm to r.t.. After the solution was stirred
for 5 h, 10 ml of water was added. Diethyl ether was
removed by rotary evaporator while keeping the bath
temperature below 25°C. Ethyl acetate (40 ml) was
added to the residue. The mixture was poured into a
separating funnel. The aqueous layer was removed
and aqueous 2 N HCl solution (40 ml) was added.
The separating funnel was vigorously shaken for 3
min. The aqueous layer was removed and the organic
layer was washed with concentrated aqueous
NaHCO3 solution (30 ml). The organic layer was col-
lected and dried over anhydrous MgSO4. After re-
moval of the solvent by rotary evaporator while
keeping the bath temperature at 0°C, the residue was
purified by column chromatography on a short (5
cm) silica gel eluting with pentane. Yield: 0.50 g
(85%). Since this compound was obtained as an 8:1
mixture with the isomerized product, the correspond-
2.16. Compound 20
Compound 20 was prepared by using the same
methodology as described above for 17. PhLi was
used instead of MeLi. Dehydration was done by
shaking with 6 N HCl solution for 10 min instead of
shaking with 2 N HCl solution for 3 min. Purifica-
tion of the crude product was done by chromatogra-
phy on a silica gel column eluting with hexane and
ethyl acetate (v/v, 40:1). Yield: 86%. 1H-NMR
(CDCl3): l7.4–7.2 (m, 10 H), 6.34 (s, 1 H), 3.39
(s, 2 H), 2.58 (t, 7.0 Hz, 2 H), 1.2–1.1 (m, 4 H), 0.67
(t, 7.0 Hz, 3 H) ppm. 13C-NMR (CDCl3, 75 MHz):
l 150.00, 142.02, 141.20, 138.15, 129.41, 128.12,
127.96, 127.90, 126.88, 1267.15, 43.30, 31.22, 26.18,
22.54, 13.59 ppm. HRMS (M+) Calc. 274.1722, ob-
served 274.1718.

B. Yeoul Lee et al. / Journal of Organometallic Chemistry 587 (1999) 181–190
187
2.17. Compound 21
2.21. X-ray crystal structure determination of 24
To a Schlenk flask containing 17 (0.302 g, 2.04
mmol) in 10 ml of THF at −78 °C was added n-BuLi
(0.82 ml, 2.5 M in hexane, 2.1 mmol). The solution was
allowed to warm to r.t. After the solution was stirred
for 4 h, solid ZrCl4(THF)2 (0.38 g, 1.0 mmol) was
added. The mixture was stirred at 60°C for 40 h. After
removal of the solvent, the residue was treated with hot
anhydrous hexane. The hot filtered hexane solution was
kept in a freezer (ca. −30°C) for 1 day. Solids were
deposited, collected by removing the hexane solution,
and dried in a vacuum. Yield: 0.32 g (70%). White
Single crystals of 24 suitable for X-ray structure
determination were grown in a hexane solution of 24 at
−30°C. A yellow crystal of 24, shaped as a block of
approximate dimensions 0.42×0.40×0.32 mm, was
used for crystal and intensity data collection. Data were
collected on a Siemens P4 diffractometer with Mo–Ka
radiation (graphite monochromator). Details of the
crystal and intensity data are given in Table 1. The
intensities were corrected for Lorentz and polarization
effects. The structure was solved by the heavy atom
method and refined against F2 by full-matrix least-
squares with the SHELXYL program, initially isotropic
and finally anisotropic temperature factors for all non-
hydrogen atoms except the carbons in the butyl groups.
The anisotropic refinements including the carbon atoms
in the butyl groups were unstable and therefore they
(C17−C19, C33–C36, C67–C70, and C83–C86) were
isotropically refined. All hydrogen atoms were gener-
ated in idealized positions and refined using a riding
model. Tables of complete bond lengths and angles,
anisotropic displacement parameters, and hydrogen
atom positional and displacement parameters for 24 are
available from the authors.
1
solid, M.p. 169–170°C. H-NMR (CDCl3): l 5.79 (s, 2
H), 2.44 (t, 7.6 Hz, 2 H), 2.04 (s, 6 H), 1.37–1.30 (m, 4
H), 0.89 (t, 7.0 Hz, 3 H) ppm. 13C-NMR (CDCl3, 75
MHz): l 131.32, 128.75, 108.28, 31.61, 26.08, 22.88,
14.54, 14.01 ppm. HRMS (M+) Calc. 458.1085, ob-
served 458.1082. Anal. Found: C, 57.35; H, 7.28.
C22H34Cl2Zr Anal. Calc.: C, 57.36; H, 7.44%.
2.18. Compound 22
Compound 22 was prepared by using the same
methodology as described above for 21. Yield: 69%.
White solid. M.p. 193–194°C. 1H-NMR (CDCl3): l
5.68 (s, 2 H), 2.67 (s, 6 H), 1.37 (s, 9 H) ppm. 13C-NMR
(CDCl3, 75 MHz): l 136.47, 131.11, 110.45, 35.97,
31.12, 19.21 ppm. Anal. Found: 56.94; H, 7.09.
C22H34Cl2Zr Anal. Calc.: C, 57.36; H, 7.44%.
2.22. Polymerization of ethylene
To a dried 500 ml glass reactor was added hexane
(200 ml). The solution was degassed by ethylene. After
the reactor was immersed in an oil bath (80°C) for 15
min, the preactivated catalyst (prepared by mixing of
MAO (1.4 ml, 2.9 mmol Al, 6.4 w% Al in toluene) with
zirconocene complex (0.5 mmol) in 10 ml of toluene for
15 min at room temperature) was added via syringe.
While the solution was stirring, ethylene was fed contin-
uously under a pressure of 40 psig for 15 min. The
reaction was quenched by addition of 5 ml of MeOH.
After the solution was filtered, polymers were obtained
and dried under vacuum at 80°C. For comparison,
bis(cyclopentadienyl)zirconium dichloride was also
studied.
2.19. Compound 23
Compound 23 was prepared by using the same
methodology as described above for 21. Yield: 85%.
White solid. M.p. 101–102°C; 1H-NMR (CDCl3): l
5.79 (s, 2 H0, 3.35 (t, 6.4 Hz, 2 H), 3.29 (s, 3 H), 2.46
(t, 7.8 Hz, 2 H), 2.03 (s, 6 H), 1.6–1.4 (m, 4 H) ppm.
13C-NMR (CDCl3, 75 MHz): l 130.89, 128.88, 108.29,
75.52, 58.58, 29.67, 26.02, 25.92, 14.56 ppm. HRMS
(M+H)+, Calc. 519.1374, observed 519.1368. Anal.
Found: 55.23; H, 6.83. C24H38Cl2O2Zr Anal. Calc.: C,
55.36; H, 7.36%.
3. Results and discussion
2.20. Compound 24
3.1. Synthesis of catalyst precursors
Compound 24 was prepared by using the same
methodology as described above for compound 20.
Yield: 73%. Light yellow solid. M.p. 151–152°C. H-
NMR (CDCl3): l 7.44–7.20 (m, 10 H), 5.76 (s, 2 H),
2.90 (t, 7.0 Hz, 2 H), 0.89–0.76 (m, 4 H), 0.41 (t, 7.1
Hz, 3 H) ppm. 13C-NMR (CDCl3, 75 MHz): l 136.59,
135.12, 129.02, 128.54, 127.82, 127.53, 113.78, 30.37,
26.29, 22.02, 13.35 ppm. Anal. Found: C, 71.43; H,
5.75. C42H42Cl2Zr Anal. Calc.: C, 71.16; H, 5.97%.
The precursors 1 and 2 were prepared by the known
procedures (Scheme 1) [6]. To use the reaction proce-
dures in Scheme 1, the presence of one phenyl group
was required. Complexes 3 and 4 were prepared by
deprotonation of 1 and 2 in THF followed by addition
of 0.5 equivalents of ZrCl4(THF)2 in the same solvent.
Crystallization of the products from toluene or toluene
and hexane gave 3 and 4 in 54% yield, respectively.
1

188
B. Yeoul Lee et al. / Journal of Organometallic Chemistry 587 (1999) 181–190
Scheme 2.
Other precursors were prepared by the general pro-
The trisubstituted cyclopentadiene was deproto-
nated with 1 equivalent of butyl-lithium in THF, and
0.5 equivalents of ZrCl4(THF)2 was added in the
same solvent. Recrystallization of the complexes from
hexane gave 21–24 in 69–73% yield.
cedures in Scheme 2. The catalytic intermolecular
Pauson–Khand reaction [9] between norbornadiene
and appropriately substituted alkynes afforded cyclo-
pentenone derivatives 5–7. Compound 8 was pre-
pared by methylation of 7 [6]. Nucleophilic 1,4-addi-
When we follow the reaction sequences in Scheme
1, the 1,4–nucleophilic addition and isomerization
steps in Scheme 2 can be skipped. Thus, it seems that
the reaction sequences in Scheme 1 are more conve-
nient than those in Scheme 2. However, to use the
reaction sequences in Scheme 1, in many cases we
have to synthesize internal alkynes in laboratories.
However, when we use the reaction sequences in
Scheme 2, most of the terminal alkynes are commer-
cially available or easily synthesized. Furthermore,
terminal alkynes can be effectively transformed to the
corresponding cyclopentenones with norbornadiene
by the catalytic reaction while the internal alkynes
are sluggish in the catalytic reaction [12]. Thus,
Scheme 2 seems to be a more general and effective
reaction scheme. Furthermore, to synthesize 20, the
reaction sequences in Scheme 1 cannot be applicable
due to the regioselectivity of the Pauson–Khand reac-
tion. Thus, Schemes 1 and 2 can complement each
other.
tion of R%CuLi (R%=Me, Ph) [7] to 5, 6, and 8 led
2
to isolation of 9–12 in 83–86% yields. Compound 9
was previously reported by Schore [10]. Pyrolysis of
9–12 and isomerization [11] of the pyrolyzed products
gave compounds 13–16 in 50–70% yields. Nucle-
ophilic addition of R%Li to 13–16 and followed by
dehydration yielded 17–20 in 76–86% yields. Interest-
ingly, treatment of 4,5-disubstituted cyclopentenones
with MeLi and followed by dehydration did not give
the corresponding dehydrated products. Thus, the iso-
merization step is prerequisite to perform a dehydra-
tion reaction. One notable thing is that treatment of
17 and 19 were obtained with a small amount of side
1
products, presumably 17% and 19% by H-NMR.

B. Yeoul Lee et al. / Journal of Organometallic Chemistry 587 (1999) 181–190
189
3.2. X-ray crystal structure of 24
groups. When we compare the polymerization activities
for 3, 4, 21–24, and Cp2ZrCl2, the order is 21\4\
22ꢀ23ꢀCp2ZrCl2\3ꢀ24. Thus, substitution by
phenyl, n-butyl, t-butyl, and (CH2)4OCH3 on the C-2
position of the Cp ring leads to a catalyst with decreas-
ing activity in the order of n-Bu\Ph\(CH2)4OCH3\
t-Bu. The relatively low activity of 23 having
(CH2)4OCH3 might be due to the coordination of the
oxygen atom to the metal center [15]. The t-butyl group
reduced the activity and molecular weight of the poly-
mer. Significant reduction of activity and molecular
weight by introduction of a t-butyl group in the cy-
clopentadienyl ligand was also reported [16].
Molecular weights and molecular weight distribu-
tions of the polymers were determined by GPC analy-
sis. As shown in Table 3, 4, 21, and 23 produced
polymers with higher molecular weights than Cp2ZrCl2.
The order of the molecular weight with the variation of
the substituent on C-2 was (CH2)4OCH3\n-Bu\
Ph\t-Bu. While the molecular weight distribution
(Mw/Mn=2.3–2.4) of the polymers obtained by cata-
lysts 4, 21, 22 showed a characteristic feature of the
single site catalyst, 23 having an ether bond produced
polymers of rather broad molecular weight distribution
(Mw/Mn=3.4) [15].
There are two crystallographically independent
molecules in the asymmetric unit. One of the two
molecular structures of 24 with the atomic numbering
scheme is shown in Fig. 1. The two molecules are
chemically equivalent. Details on the crystal and inten-
sity data are given in Table 1 and the fractional atomic
coordinates appear in Table 2. The molecules have a
pseudo 2-fold (C2) axis running Zr2 and the two Cp
rings are approximately in eclipsed conformation where
the substituents on the Cp rings are on the cross way to
each other to reduce the steric congestion. Due to the
steric bulkiness of the substituents on the Cp rings, the
angle (99.06(7)°) between Cl3ꢀZrꢀCl4 is relatively wide.
The steric interaction between substituents on the Cp
ring leads to the lengthening of the CꢀC bonds connect-
ing the two phenyl rings and the butyl group. Thus, the
bond distances of C52ꢀC53, C53ꢀC54 and C53ꢀC54 are
longer than those of C51ꢀC52 and C51ꢀC55. The bond
,
distances (2.230 and 2.226 A) of CpcentꢀZr and angle
(130.8°) between CpcentꢀZrꢀCpcent in 24 are similar to
those found in bis-(2-phenylindenyl)zirconium dichlo-
rides [13] and bis(indenyl)zirconium dichloride [14].
3.3. Polymerization results
Acknowledgements
Precursors were activated with MAO and used to
polymerize ethylene. Gaseous ethylene (40 psig pres-
sure) reacts with the activated complexes of 3, 4, and
21–24 with MAO in hexane under vigorously anhy-
drous, anaerobic conditions. Cp2ZrCl2 was studied to
compare the activity. The activity of the catalysts and
the molecular weight distribution of the produced poly-
mer are shown in Table 3 The yields (Table 3), as
determined by quenching the polymerization reactions
(addition of MeOH) after a measured time interval (15
min), suggest that the activities of complexes 4 and 21
are higher than that of Cp2ZrCl2 under similar condi-
tions. The activity of 21 containing two methyl groups
and one n-butyl group was almost four times higher
than that of Cp2ZrCl2. Compounds 22 and 23 showed
similar activities to Cp2ZrCl2. However, two or three
phenyl substitution as in 3 and 24 exhibit negligible
activities, presumably due to the steric effect of phenyl
Y.K.C. thanks the Korea Science and Engineering
Foundation (KOSEF) (96-0501-03-01-3), the Ministry
of Education (1998-015-D00165), and the KOSEF
through the Center for Molecular Catalysis for finan-
cial support.
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Yield (g)
Mw (×10+3
)
Mw/Mn
4
21
22
23
4.1
6.0
1.9
1.5
1.5
269
319
37
369
110
2.4
2.3
2.3
3.4
2
Cp2ZrCl2

190
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