Highly efficient one-step direct synthesis of monocyclopentadienyltitanium complexes

Article abstract of DOI:10.1021/om0508738

This report describes a highly efficient one-step synthetic strategy for monocyclopentadienyltitanium complexes by the direct reaction of TiCl ₄ with substituted cyclopentadienes, without adding any other reagents. This new synthetic method is particularly efficient for cyclopentadienes with a pendant group that can bond or coordinate to the Ti atom.

Full text of DOI:10.1021/om0508738

Organometallics 2006, 25, 631-634
631
Highly Efficient One-Step Direct Synthesis of
Monocyclopentadienyltitanium Complexes
Yuetao Zhang and Ying Mu*
Key Laboratory for Supramolecular Structure and Materials of Ministry of Education, School of
Chemistry, Jilin UniVersity, 10 Qianwei Road, Changchun 130012, People’s Republic of China
ReceiVed October 10, 2005
This report describes a highly efficient one-step synthetic strategy for monocyclopentadienyltitanium
complexes by the direct reaction of TiCl4 with substituted cyclopentadienes, without adding any other
reagents. This new synthetic method is particularly efficient for cyclopentadienes with a pendant group
that can bond or coordinate to the Ti atom.
alkane elimination,12 and Me3SiCl,13 Me2SnCl2,14 and Al2Me4-
(µ-NMe2)2 elimination reactions, as well as the oxidative
Introduction
15
Group 4 metallocene complexes have been used as catalysts
for many organic and polymerization reactions, such as the
olefin polymerization reaction,1 organosilane dehydrocoupling
reaction,2 and Diels-Alder reaction,3 as well as the hydrogena-
tion,4 hydrosilation,5 hydroamination,6 and coupling reactions
of unsaturated organic compounds,7 of which the olefin polym-
erization reaction is probably the most important one for human
society and thus has been extensively studied by scientists in
the industrial and academic communities. Group 4 metallocene-
based catalysts can produce a number of high-performance
polyolefin products, including isotactic polypropylene, syndio-
tactic polypropylene, atactic polypropylene, linear high-density
polyethylene, linear low-density polyethylene, syndiotactic
polystyrene, and cycloolefin copolymer. As we know, poly-
olefins are the largest volume synthetic materials used in the
world and have been applied in almost every aspect of our daily
lives. The global polyethylene demand is expected to increase
from about 55 million metric tons in 2002 to 87 million metric
tons in 2010, and polypropylene demand is expected to grow
from about 35 million metric tons to nearly 60 million metric
tons in the same period.8 The growing demand for high-
performance polyolefin products in recent years has further
inspired industrial and academic interest in developing efficient
synthetic methods for metallocenes and high-performance olefin
polymerization catalysts.9 Thus far, a number of synthetic
strategies, such as lithium salt elimination,10 amine elimination,11
addition reaction of cyclopentadiene with lower halides,16 have
been developed for the synthesis of metallocene complexes.
However, due to multistep syntheses, expensive reagents, and
harsh reaction conditions, present synthetic techniques are still
too complicated and expensive for commercial application of
metallocene catalysts in polyolefin industry. We herein report
a highly efficient one-step synthesis of monocyclopentadienylti-
tanium complexes by the direct reaction of TiCl4 with substituted
cyclopentadienes under mild conditions without adding any
other reagents. To the best of our knowledge, this is the first
time that metallocene complexes have been synthesized in high
yields by such an easy synthetic approach. Similar reactions of
TiCl4 with cyclopentadiene and C5H5(CH2)nN(R)H in the
presence of Et3N were reported before,17 but the introduction
of Et3N makes the isolation and purification of the products
complicated, and therefore, the cost of the products increased.
It has been known that some monocyclopentadienyltitanium
complexes,18 especially the so-called constrained-geometry
titanium complexes,19 are excellent catalysts for producing
syndiotactic polystyrene and high-molecular-weight atactic
(9) (a) Coates, G. W.; Waymouth, R. M. Science 1995, 267, 217-219.
(b) Service, R. F. Science 1997, 278, 33-34. (c) Roscoe, S. B.; Fre´chet, J.
M. J.; Walzer, J. F.; Dias, A. J. Science 1998, 280, 270-273. (d) Chaffin,
K. A.; Knutsen, J. S.; Brant, P.; Bates, F. S. Science 2000, 288, 2187-
2190.
(10) Bercaw, J. E.; Marvich, R. H.; Bell, L. G.; Brintzinger, H. H. J.
Am. Chem. Soc. 1972, 94, 1219-1238.
* To whom correspondence should be addressed. Fax: (+86) 431-
5193421. Tel: (+86) 431-5168472. E-mail: ymu@mail.jlu.edu.cn.
(1) (a) Sinn, H.; Kaminsky, W.; Vollmer, H. J.; Woldt, R. Angew. Chem.,
Int. Ed. Engl. 1980, 19, 390-392. (b) Kaminsky, W.; Ku¨lper, K.;
Brintzinger, H. H.; Wild, F. R. W. P. Angew. Chem., Int. Ed. Engl. 1985,
24, 507-508. (c) McKnight, A. L.; Waymouth, R. M. Chem. ReV. 1998,
98, 2587-2598.
(11) King, W. A.; Bella, S. D.; Gulino, A.; Lanza, G.; Fragala`, I. L.;
Stern, C. L.; Marks, T. J. J. Am. Chem. Soc. 1999, 121, 355-366.
(12) Mu, Y.; Piers, W. E.; MacQuarrie, D. C.; Zaworotko, M. J.; Young,
V. G., Jr. Organometallics 1996, 15, 2720-2726.
(13) Ready, T. E.; Chien, J. C. W.; Rausch, M. D. J. Organomet. Chem.
1996, 519, 21-28.
(14) Nifant’ev, I. E.; Borzov, M. V.; Churakov, A. V. Organometallics
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108, 4059-4066.
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(3) Bondar, G. V.; Aldea, R.; Levy, C. J.; Jaquith, J. B.; Collins, S.
Organometallics 2000, 19, 947-949 and references therein.
(4) Broene, R. D.; Buchwald, S. L. J. Am. Chem. Soc. 1993, 115, 12569-
12570 and references therein.
(5) Takahashi, T.; Hasegawa, M.; Suzuki, N.; Saburi, M.; Rousset, C.
J.; Fanwick, P. E.; Negishi, E. J. Am. Chem. Soc. 1991, 113, 8564-8566
and references therein.
(6) Pohlki, F.; Doye, S. Chem. Soc. ReV. 2003, 32, 104-114 and
references therein.
(7) Pellny, P. M.; Peulecke, N.; Burlakov, V. V.; Baumann, W.;
Spannenberg, A.; Rosenthal, U. Organometallics 2000, 19, 1198-1200 and
references therein.
283.
(16) Reid, A. F.; Wailes, P. C. J. Organomet. Chem. 1964, 2, 329-335.
(17) (a) Birmingham, J. M.; Seyferth, D.; Wilkinson, G. J. Am. Chem.
Soc. 1954, 76, 4179-4179. (b) Sinnema, P. J.; Veen, L.; Spek, A. L.;
Veldman, N.; Teuben, J. H. Organometallics 1997, 16, 4245-4247.
(18) (a) Ishihara, N.; Kuramoto, M.; Uoi, M. Macromolecules 1988, 21,
3356-3360. (b) Quyoum, T.; Wang, Q.; Tudoret, M. J.; Baird, M. C.; Gillis,
D. J. J. Am. Chem. Soc. 1994, 116, 6435-6436. (c) Nomura, K.; Naga, N.;
Miki, M.; Yanagi, K. Macromolecules 1998, 31, 7588-7597.
(19) (a) Du Plooy, K. E.; Moll, U.; Wocadol, S.; Massa, W.; Okuda, J.
Organometallics 1995, 14, 3129-3131. (b) Canich, J. A. M.; Yang, H.
W.; Licciardi, G. F. U.S. Patent 5,516,848, 1996 (Exxon). (c) Chen, Y. X.;
Marks, T. J. Organometallics 1997, 16, 5958-5963.
(8) Tullo, A. H. Chem. Eng. News 2003, 81(22), 26-27.
10.1021/om0508738 CCC: $33.50 © 2006 American Chemical Society
Publication on Web 01/04/2006

632 Organometallics, Vol. 25, No. 3, 2006
Zhang and Mu
1
Figure 1. Stack plot of the aromatic region of H NMR spectra
recorded from the NMR tube reaction of TiCl4 with (TCDBP)H2
at 15 min and 40 min.
Figure 2. 1H NMR spectra recorded from the free ligand
((TCDBP)H2) to the (TCDBP)TiCl2 complex at 30 °C. The initial
concentration of (TCDBP)H2 is 0.054 mol/L. Time: (a) 3 min; (b)
7 min; (c) 15 min; (d) 20 min; (e) 30 min; (f) 40 min; (g) 80 min;
(h) 180 min.
polypropylene, as well as copolymers of ethylene with propy-
lene, R-olefins, styrene, and norbornene. Some of the constrained-
geometry titanium complexes have been applied as catalysts in
the industrial production of polyolefins.20 Our new synthetic
technique is undoubtedly a breakthrough in the methodology
and concept of preparing metallocene complexes and might be
helpful in promoting the application of metallocene catalysts.
Scheme 1. Possible Mechanism for the One-Step Synthetic
Reaction
Results and Discussion
Synthesis of Constrained-Geometry Titanium Dichloride
Complexes 1-4. We reported recently a series of constrained-
geometry cyclopentadienylphenoxytitanium(IV) dichloride com-
plexes synthesized by a template lithium salt elimination
approach.21 These complexes show catalytic performance similar
to that of the constrained-geometry titanium catalysts used
currently in industry.20 To understand the reaction mechanism,
the interaction of 2-(tetramethylcyclopentadienyl)-4,6-di-tert-
butylphenol (TCDBPH2) with TiCl4 in CDCl3 was followed by
1H NMR. It was a great surprise to us that the signals of the
final products, (2-(tetramethylcyclopentadienyl)-4,6-di-tert-bu-
tylphenoxy)titanium dichlorides (TCDBPTiCl2), were observed
before the addition of nBuLi. This result promoted us to
investigate the reaction in detail on the NMR tube and flask
scales, and a highly efficient one-step synthetic method for the
monocyclopentadienyltitanium complexes was finally devel-
oped. The important feature of this new method is that the
monocyclopentadienyltitanium complexes can be easily syn-
thesized in high yields by the direct reaction of cyclopentadiene
derivatives with TiCl4 in a 1:1 molar ratio without using any
other reagents. The new method was first tested for the reactions
of TiCl4 with 2-(tetramethylcyclopentadienyl)-4,6-di-tert-but-
ylphenol ((TCDBP)H2), 2-(tetramethylcyclopentadienyl)-6-tert-
butylphenol ((TCBP)H2), 2-(tetramethylcyclopentadienyl)-6-
phenylphenol ((TCPP)H2), and 2-(tetramethylcyclopentadienyl)-
6-methylphenol ((TCMP)H2) in toluene at room temperature,
and the corresponding complexes (TCDBP)TiCl2 (1), (TCBP)-
TiCl2 (2), (TCPP)TiCl2 (3), and (TCMP)TiCl2 (4) were obtained
in high yields of 92.4, 89.3, 75.3, and 64.7%, respectively.
During the reactions of TiCl4 with free ligands in NMR tubes,
are the signals of the Ph protons of the intermediate. During
the course of the reaction, the amount of the intermediate
changed very little, as can be seen by viewing the spectra
obtained at different times (Figure 2). On the basis of our
observations on these reaction systems, the intermediates in these
reactions are presumably the reaction products of TiCl4 with
the phenol group of the free ligands. It has been reported that
the reaction of TiCl4 with a phenol can take place easily.22 The
fact that the intermediate does not accumulate during the reaction
implies that the following intramolecular reaction between the
-TiCl3 and -Me4CpH moieties is relatively fast, which is
understandable, since the two moieties are very close to each
other and the probability for reaction to take place is increased
greatly. The yields for complexes 1-4 under similar conditions
is 1 > 2 > 3 > 4, which could be attributed to the steric effects
of the R group at the ortho position of the phenolate in these
complexes. The smallest R group, methyl, results in the lowest
t
yield of 4, while the bulky Bu group leads to higher yields of
1 and 2. The more bulky the R group, the longer the distance
between the R and -TiCl3 moieties. In contrast, the -TiCl3
and -Me4CpH moieties are closer and the reaction between
them is faster. On the basis of the above discussions, a possible
reaction mechanism for the one-step synthetic reaction, as shown
in Scheme 1, could be proposed.
Synthesis of Monocyclopentadienyltitanium Trichloride
Complexes 5-7. To validate the universality of the one-step
synthetic reaction, reactions of TiCl4 with cyclopentadiene
1
a small amount of an intermediate was observed by H NMR
1
for these systems. Figure 1 shows the aromatic region of a H
NMR spectrum recorded from the NMR tube reaction of TiCl4
with (TCDBP)H2. Peaks A and B are the signals of the Ph
protons of the free (TCDBP)H2 and C and D are the signals of
the Ph protons of the (TCDBP)TiCl2 complex, while E and F
(20) (a) Stevens, J. C.; Timmers, F. J.; Wilson, D. R.; Schmidt, G. F.;
Nickas, P. N.; Rosen, R. K.; Knight, G. W.; Lai, S. Y. Eur. Pat. Appl. EP
416 815 A2, 1991 (Dow). (b) Canich, J. A. M. U.S. Patent 5,055, 438,
1991 (Exxon).
(21) Zhang, Y.; Mu, Y.; Lu¨, C.; Li, G.; Xu, J.; Zhang, Y.; Zhu, D.; Feng,
S. Organometallics 2004, 23, 540-546.
(22) (a) Nielson, A. J.; Schwerdtfeger, P.; Waters, J. M. Dalton Trans.
2000, 529-537. (b) Thorn, M. G.; Vilardo, J. S.; Lee, J.; Hanna, B.;
Fanwick, P. E.; Rothwell, I. P. Organometallics 2000, 19, 5636-5642.

Monocyclopentadienyltitanium Complexes
Organometallics, Vol. 25, No. 3, 2006 633
Figure 3. Plot of the concentration of components vs time of the
reaction of TiCl4 with (TCDBP)H2 at 30 °C: (9) (TCDBP)H2; (4)
(TCDBP)TiCl2; (O) intermediate.
Figure 4. Second-order plots of rate data of the reaction of TiCl4
with (TCDBP)H2.
(CpH), methylcyclopentadiene (Cp′H), pentamethylcyclopen-
tadiene (Cp*H), 1-butyl-2,3,4,5-tetramethylcyclopentadiene
(Cp#H), and tetramethylcyclopentadiene (Cp′′H) were also
studied. Experimental results indicated that both CpH and Cp′H
were polymerized to produce a black tar under different
conditions, which is consistent with the results previously
reported by Wilkinson et al.17a The complexes Cp*TiCl3 (5),
Cp#TiCl3 (6), and Cp′′TiCl3 (7) were obtained from the
corresponding reactions at 80 °C in yields of 58.2, 53.1, and
49.0%, respectively. NMR tube reactions indicated that the
reactions could not go to completion at room temperature. From
the synthetic reaction of Cp*TiCl3, a small amount of tetra-
1
methylfulvene, identified by H and 13C NMR spectroscopy,
was obtained as a byproduct. Freshly prepared Cp#TiCl3 was a
viscous red oil that crystallized slowly when the crude product
was allowed to stand at room temperature for several weeks.
The above results could cause us to draw the conclusion that
the one-step synthetic reaction is a versatile method for the
synthesis of monocyclopentadienyltitanium complexes and can
be applied to all multiply substituted cyclopentadienes only if
polymerization does not take place in the presence of TiCl4. A
side chain on the Cp ring, which can bond or coordinate to the
Ti atom, might accelerate the reaction between the -CpH and
-TiCln moieties and hence increase the yield of product.
Kinetic Studies on the Reaction of TiCl4 with (TCDBP)-
H2. By following the reaction of TiCl4 with (TCDBP)H2 (1:1)
with 1H NMR, it was found that the signals for the free ligand
(TCDBP)H2, the product 1, and the intermediate in the aromatic
region of the 1H NMR spectrum of the reaction mixture can be
identified clearly (Figure 1) and the concentrations of these
species can be calculated, which is suitable for kinetic studies.
We therefore studied the kinetics of the reaction at different
temperatures. Figure 2 shows the 1H NMR spectra obtained at
different times at 30 °C. After the resulting integrals were scaled
by the initial concentration, a plot of the concentration of
components vs time (Figure 3) was obtained, which shows that
the concentration of the intermediate is very low during the
whole reaction, indicating the following reaction is relatively
fast. Since the concentration of (TCDBP)H2 is equivalent to
that of TiCl4 and the plot of 1/(concentration of the free ligand,
mol/L) vs time gives a good straight line, the reaction should
be a second-order reaction and the slope of the line is the rate
constant (k). The experiment was repeated for several temper-
atures (15, 20, 25, 30, and 35 °C), each leading to similar linear
plots (Figure 4), and the resulting rate constants (Table 1) were
used to construct the Arrhenius plot that is shown in Figure 5.
Figure 5. Arrhenius plot of the reaction of TiCl4 with (TCDBP)-
H2.
Table 1. Rate Constants and Activation Parameters for the
Reaction of TiCl4 with (TCDBP)H2
T (K) 105k (L/(mol S)) Ea (kJ/mol) ∆Hq (kJ/mol) ∆Sq (J/(mol K))
288
293
298
303
308
262 ( 2.3
452 ( 2.4
1123 ( 9.0
1789 ( 22.8
3496 ( 27.4
96.7 ( 4.9
94.3 ( 4.9
33.0 ( 16.5
The kinetic results are consistent with the 1H NMR observations
and support the proposed mechanism shown in Scheme 1. The
bimolecular reaction of TiCl4 with the phenol group of the free
ligand should be the rate-controlling step of the whole reaction.
The apparent activation energy (Ea ) 96.7 kJ/mol) is in a
reasonable range for a reaction that can go to completion at
room temperature.23 The activation enthalpy (∆Hq ) 94.3 kJ/
mol) and entropy (∆Sq ) 33.0 J/(mol K)) for the reaction were
also calculated according to the transition-state theory expression
for the rate constant. A plot of ln(hk/kBT) vs 1/T gives a straight
line. The activation enthalpy is obtained from the slope and the
activation entropy from the intercept (see the Supporting
Information). The rate constants and activation parameters are
given in Table 1.
(23) Silbey, R. J.; Alberty, R. A. Physical Chemistry, 3rd ed.; Wiley:
New York, 2001.

634 Organometallics, Vol. 25, No. 3, 2006
Zhang and Mu
same way as described above for the synthesis of 1. Pure 3 (0.92
g, 75%) was obtained as a red crystalline solid. Mp: 289-291 °C.
Anal. Calcd for C21H20Cl2OTi (407.16): C, 61.95; H, 4.95.
Conclusions
We have developed a highly efficient synthetic method for
the monocyclopentadienyltitanium complexes by the direct
reaction of TiCl4 with substituted cyclopentadienes that do not
polymerize under the reaction conditions. This new method is
versatile and especially efficient for cyclopentadienes with a
side chain containing a group that can bond or coordinate to
the Ti atom. At present, further investigations exploring
possibilities of applying this method to synthesizing cyclopen-
tadienyl complexes of other metals are under way.
1
Found: C, 61.89; H, 4.92. H NMR (CDCl3, 300 MHz; 298 K):
δ 7.24-7.64 (m, 8H, Ph), 2.44 (s, 6H, C5Me4), 2.11 (s, 6H, C5-
Me4). 13C NMR (CDCl3, 75.4 MHz; 298 K): δ 171.97, 145.85,
142.68, 136.44, 130.76, 130.24, 129.26, 129.01, 128.36, 127.81,
127.38, 126.61, 124.23, 13.60, 13.12 ppm.
One-Step Synthesis of (TCMP)TiCl2 (4). The reaction of
(TCMP)H2 (3.0 mmol) and TiCl4 (3.0 mmol) was carried out in
the same way as described above for the synthesis of 1. Pure 4
(0.67 g, 65%) was obtained as a red crystalline solid. Mp: 155-
157 °C. Anal. Calcd for C16H18Cl2OTi (345.09): C, 55.69, H; 5.26.
Found: C, 55.60; H, 5.20. 1H NMR (CDCl3, 300 MHz; 298 K): δ
7.19-7.23 (m, 1H, Ph), 7.04-7.12 (m, 2H, Ph), 2.43 (s, 6H, C5-
Me4), 2.18 (s, 3H, Ph-Me), 2.06 (s, 6H, C5Me4). 13C NMR (CDCl3,
75.4 MHz; 298 K): δ 173.65, 145.95, 143.16, 131.22, 130.55,
128.01, 126.20, 123.67, 123.55, 15.31, 13.53, 13.12 ppm.
Experimental Section
All operations were performed under an inert atmosphere of
nitrogen using standard Schlenk-line or glovebox techniques.
Solvents were dried and distilled prior to use. TiCl4, Cp′′H, and
Cp*H were purchased from Aldrich. (TCDBP)H2, (TCBP)H2,
(TCPP)H2, and (TCMP)H2 were prepared according to literature
One-Step Synthesis of Cp*TiCl3 (5). A solution of Cp*H (1.0
g, 7.3 mmol) in CH2Cl2 (20 mL) was added dropwise to a solution
of TiCl4 (7.3 mmol) in CH2Cl2 at room temperature. The mixture
was heated with stirring at 80 °C overnight. The precipitate was
filtered off, and the solvent was removed in vacuo. Then the red
residue was dried in vacuo at 100 °C to leave a red crystalline
solid (1.23 g, 58%). Mp: 223-225 °C. Anal. Calcd for C10H15-
21
procedures. All NMR experiments were carried out in sealed
NMR tubes on a Varian Mercury-300 NMR spectrometer. Kinetic
experiments were performed with a delay time (d1) of 12 s, a
number of data points (np) of 32 k, an acquisition time (at) of 2.666
s, and a pulse width (pw) of 90°.
Synthesis of 1-Butyl-2,3,4,5-tetramethylcyclopentadiene
(Cp#H). A solution of 2,3,4,5-tetramethyl-2-cyclopentenone (2.64
mL, 17.5 mmol) in Et2O (60 mL) was added dropwise to a solution
1
Cl3Ti (289.45): C, 41.49; H, 5.22. Found: C, 41.45; H, 5.20. H
NMR (CDCl3, 300 MHz; 298 K): δ 2.38 (s, 15H, Cp-CH3). 13C
NMR (CDCl3, 75.4 MHz; 298 K): δ 138.18 (Cp), 14.70 (Cp-CH3)
ppm.
n
of BuLi (17.5 mmol) in Et2O (40 mL) at -15 °C. The mixture
was slowly warmed to room temperature and stirred overnight. The
reaction mixture was hydrolyzed with 20 mL of saturated NH4Cl-
(aq). The organic layer was separated and treated three times with
20 mL of concentrated HCl and then washed three times with water
(50 mL), dried over MgSO4, filtered, and evaporated to dryness,
affording a brown oil. Pure product (2.1 g, 67%) was obtained by
column chromatography over silica (hexanes/CH2Cl2, 5:1) as a
One-Step Synthesis of Cp#TiCl3 (6). The reaction of Cp#H (5.0
mmol) with TiCl4 (5.0 mmol) was carried out in the same way as
described above for the synthesis of 5. Pure 6 (0.88 g, 53%) was
obtained as a red crystalline solid. Mp: 106-108 °C. Anal. Calcd
for C13H21Cl3Ti (331.53): C, 47.10; H, 6.38. Found: C, 47.06; H,
6.35. 1H NMR (CDCl3, 300 MHz; 298 K): δ 2.85 (t, 2H, nBu CH2),
yellow oil. H and 13C NMR spectroscopic analysis indicates that
the samples are mixtures of three isomers.
1
n
n
2.38 (s, 12H, Cp-Me), 1.38 (m, 4H, Bu CH2), 0.94 (t, 3H, Bu
Me). 13C NMR (CDCl3, 75.4 MHz; 298 K): δ 142.48, 138.36,
137.66, 32.34, 29.41, 23.03, 14.64, 14.15 ppm.
One-Step Synthesis of (TCDBP)TiCl2 (1). A solution of
(TCDBP)H2 (1.0 g, 3.1 mmol) in toluene (20 mL) was added
dropwise to a solution of TiCl4 (3.1 mmol) in toluene (40 mL) at
room temperature. The mixture was heated with stirring at 40 °C
overnight. The precipitate was filtered off, and the solvent was
removed to leave a red crystalline solid (1.28 g, 93%). Mp: 238-
240 °C. Anal. Calcd for C23H32Cl2OTi (443.27): C, 62.32; H, 7.28.
Found: C, 62.23; H, 7.24. 1H NMR (400 MHz, CDCl3, 298 K): δ
7.33 (s, 1H, Ph), 7.11 (s, 1H, Ph), 2.42 (s, 6H, C5Me4), 2.04 (s,
6H, C5Me4), 1.353 (s, 9H, tBu), 1.347 (s, 9H, tBu). 13C NMR (100.5
MHz, CDCl3, 298 K): δ 171.60, 146.86, 145.72, 143.59, 134.82,
130.14, 128.88, 123.40, 123.11, 35.02, 34.76, 31.72, 29.52, 13.49,
13.00 ppm.
One-Step Synthesis of Cp′′TiCl3 (7). The reaction of Cp′′H (6.0
mmol) with TiCl4 (6.0 mmol) was carried out in the same way as
described above for the synthesis of 5. Pure 7 (0.81 g, 49%) was
obtained as a red crystalline solid. Mp: 145-147 °C. Anal. Calcd
for C9H13Cl3Ti (275.43): C, 39.25; H, 4.76. Found: C, 39.19; H,
1
4.73. H NMR (CDCl3, 300 MHz; 298 K): δ 6.65 (s, 1H, Cp H),
2.41 (s, 6H, Cp-Me), 2.36 (s, 6H, Cp-Me). 13C NMR (CDCl3,
75.4 MHz; 298 K): δ 139.30, 138.11, 124.54, 16.61, 14.26 ppm.
Kinetic Experiment on the Reaction of TiCl4 with (TCDBP)-
H2. A solution of TiCl4 (0.03 mmol) in CDCl3 (0.25 mL) was added
to a solution of (TCDBP)H2 (10 mg, 0.03 mmol) in CDCl3 (0.25
mL) in a NMR tube. The reaction was followed immediately by
1H NMR at the appropriate temperature (15, 20, 25, 30, and 35
°C, respectively).
One-Step Synthesis of (TCBP)TiCl2 (2). The reaction of
(TCBP)H2 (3.5 mmol) and TiCl4 (3.5 mmol) was carried out in
the same way as described above for the synthesis of 1. Pure 2
(1.21 g, 89%) was obtained as a red crystalline solid. Mp: 138-
140 °C. Anal. Calcd for C19H24Cl2OTi (387.17): C, 58.94; H, 6.25.
Acknowledgment. This work was supported by the National
Natural Science Foundation of China (No. 20374023).
1
Found: C, 58.89; H, 6.20. H NMR (CDCl3, 300 MHz; 298 K):
δ 7.33-7.36 (m, 1H, Cp), 7.11-7.13 (m, 2H, Ph), 2.43 (s, 6H,
C5Me4), 2.04 (s, 6H, C5Me4), 1.35 (s, 9H, tBu). 13C NMR (CDCl3,
75.4 MHz; 298 K): δ 174.18, 146.05, 143.43, 136.53, 130.62,
129.47, 126.93, 126.79, 123.97, 35.14, 29.68, 13.73, 13.31 ppm.
One-Step Synthesis of (TCPP)TiCl2 (3). The reaction of
(TCPP)H2 (3.0 mmol) and TiCl4 (3.0 mmol) was carried out in the
Supporting Information Available: Figures giving 1H and 13
NMR spectra for the complexes in this article. This material is
available free of charge via the Internet at http://pubs.acs.org.
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OM0508738