Synthesis and characterization of phosphorous-bridged bisphenoxy titanium complexes and their application to ethylene polymerization

Article abstract of DOI:10.1016/j.jorganchem.2006.08.036

Phosphorous-bridged bisphenoxy titanium complexes were synthesized and their ethylene polymerization behavior was investigated. Bis[3-tert-butyl-5-methyl-2-phenoxy](phenyl)phosphine tetrahydrofuran titanium dichloride (4a) was obtained by treatment of 3 equiv of n-BuLi with bis[3-tert-butyl-2-hydroxy-5-methylphenyl](phenyl)phosphine hydrochloride salt (3a) followed by TiCl₄(THF)₂ in THF. THF-free complexes 5a-5d were synthesized more conveniently by the direct reaction of MOM-protected ligands (2a-2d) with TiCl₄ in toluene. X-ray analysis of 4a revealed that the ligand is bonded to the octahedral titanium (IV) center in a facial fashion and two chlorine atoms possess cis-geometry. Complexes 4a and 5a-5d were utilized as catalyst precursors for ethylene polymerization. Complex 5c gave high molecular weight polyethylene (M_w = 1,170,000, M_w/M_n = 2.0) upon activation with Al(ⁱBu)₃/[Ph₃C][B(C₆F₅)₄] (TB). Ethylene polymerization activity of 5d activated with Al(ⁱBu)₃/TB reached 49.0 × 10⁶ g mol (cat) ^-1 h^-1.

Full text of DOI:10.1016/j.jorganchem.2006.08.036

Journal of Organometallic Chemistry 691 (2006) 4968–4974
www.elsevier.com/locate/jorganchem
Synthesis and characterization of phosphorous-bridged
bisphenoxy titanium complexes and their application
to ethylene polymerization
*
Hidenori Hanaoka, Yuka Imamoto, Takahiro Hino, Yoshiaki Oda
Organic Synthesis Research Laboratory, Sumitomo Chemical Co., Ltd., 1-98, Kasugadenaka 3-chome, Konohana-ku, Osaka 554-8558, Japan
Received 20 January 2006; received in revised form 10 August 2006; accepted 17 August 2006
Available online 26 August 2006
Abstract
Phosphorous-bridged bisphenoxy titanium complexes were synthesized and their ethylene polymerization behavior was investigated.
Bis[3-tert-butyl-5-methyl-2-phenoxy](phenyl)phosphine tetrahydrofuran titanium dichloride (4a) was obtained by treatment of 3 equiv of
n-BuLi with bis[3-tert-butyl-2-hydroxy-5-methylphenyl](phenyl)phosphine hydrochloride salt (3a) followed by TiCl4(THF)2 in THF.
THF-free complexes 5a–5d were synthesized more conveniently by the direct reaction of MOM-protected ligands (2a–2d) with TiCl4
in toluene. X-ray analysis of 4a revealed that the ligand is bonded to the octahedral titanium (IV) center in a facial fashion and two
chlorine atoms possess cis-geometry. Complexes 4a and 5a–5d were utilized as catalyst precursors for ethylene polymerization. Complex
5c gave high molecular weight polyethylene (Mw = 1,170,000, Mw/Mn = 2.0) upon activation with Al(iBu)3/[Ph3C][B(C6F5)4] (TB). Eth-
ylene polymerization activity of 5d activated with Al(iBu)3/TB reached 49.0 · 106 g mol (cat) ꢀ1 hꢀ1
ꢀ 2006 Elsevier B.V. All rights reserved.
.
Keywords: Titanium; Phosphorous-bridged bisphenoxy ligand; Polymerization catalyst
1. Introduction
isotactic poly(ethylene-alt-styrene) [4]. A variety of bridg-
ing groups, such as SO2 [5], tellurium [6], N-heterocyclic
carbine [7], ethylene [8], 1,4-dithiabutane [9] have been
studied. Okuda recently reported 1,4-dithiabutane-bridged
bisphenoxy complex B is an excellent catalyst for isospeci-
fic styrene polymerization [9]. Kol and his group reported
that bisphenoxyamine zirconium complex C, which has a
side-arm donor, is highly active for polymerization of 1-
hexene [10], and also reported bisphenoxy zirconium com-
plex D, which has two nitrogen atoms in the bridging
group, catalyzes the isoselective living polymerization of
1-hexene [11]. Non-bridged phenoxy complexes have been
attractive catalyst precursors: Fujita and coworkers
reported that phenoxy-imine zirconium complexes show
very high activity for ethylene polymerization [12]. More-
over, Fujita and Coates independently reported that fluo-
rine substituted phenoxy-imine titanium complexes
catalyze syndiospecific living polymerization of propylene
[13].
Olefin polymerization by metallocene [1] and post metal-
locene catalysis [2] has attracted much interest in the past
two decades. Among these catalyst systems, early transi-
tion metal complexes with phenoxy ligands have been
one of the most attractive and extensively studied target
catalysts in polymerization chemistry [3]. Titanium com-
plexes with bridged bis(aryloxo) ligands also have been
studied due to their unique polymerization behavior:
Kakugo and Miyatake reported pioneering work in this
field using Ti(tbmp)Cl2 (A), tbmp = 2,20-thiobis(2-tert-
butyl-4-methylphenoxy), which is a highly active catalyst
for not only homo polymerization but also copolymeriza-
tion of a-olefins, resulting in high molecular weight poly-
ethylene and polypropylene, syndiotactic polystyrene and
*
Corresponding author.
E-mail address: oday2@sc.sumitomo-chem.co.jp (Y. Oda).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.08.036

H. Hanaoka et al. / Journal of Organometallic Chemistry 691 (2006) 4968–4974
4969
Cl Cl
Ti
O
Cl Cl
Ti
1) n-BuLi (3 MR)
2) TiCl4(THF)2
O
O
O
Ti
O
3a
P
S
S
O
O
THF
Cl
Cl
S
4a
Scheme 2.
Bn
Bn
Zr
white solid (65% yield). The lithiation proceeded selectively
at ortho position due to the MOM protected group [17].
Treatment of 2a with HCl in methanol deprotected the
MOM group to give an HCl salt of phenol derivative 3a
in 90% yield. It is notable that the formation of the salt
3a caused phosphorous moiety to be stable in air, leading
to easy handling on a large scale.
Bn
Bn
O
N
O
Zr
N
O
O
N
N
We prepared a titanium complex 4a by reaction of the
dilithium salt of 3a, which was obtained by treating with
3 equiv of n-BuLi and TiCl4(THF)2 in THF (Scheme 2).
Compound 4a was characterized by NMR and mass spec-
troscopy, together with X-ray analysis. The 1H NMR spec-
trum of 4a displayed signals due to diphenolic phosphine
ligand and THF in an exact 1:1 ratio, indicating that one
THF coordinated to the titanium center. In the 31P{1H}
NMR spectrum of 4a, a singlet signal was observed at
18.5 ppm. The chemical shift value was shifted downfield,
typically indicating that the phosphorous atom coordi-
nated to the titanium atom [14,18]. It is assumed likely that
the titanium atom adopted octahedral geometry with two
oxygen atoms and a phosphine atom in a facial geometry
and two chlorines and one oxygen of THF occupying the
remaining three coordination sites. Thus, two chloride
We have been interested in phosphorous incorporated
complexes, whose unique properties are recently reported
for phenoxyimine [14] and half-metallocenes of group 4
metals [15] as well as rare earth metals [16]. Herein we
report the synthesis of phosphorous-bridged bisphenoxy
titanium complexes and their catalytic behavior for ethyl-
ene polymerization. Additionally, we found an efficient
synthesis of the complexes and the effect of a side-arm
donor on the phosphorus atom on polymerization
behavior.
2. Results and discussion
Scheme 1 shows the synthesis of a new ligand bis[3-
tert-butyl-2-hydroxy-5-methylphenyl](phenyl)phosphine
hydrochloride salt (3a) from 2-tert-butyl-1-(methoxymeth-
oxy)-4-methylbenzene (1). Lithiation of 1 using n-BuLi at
ꢀ78 ꢁC followed by addition of a half equivalent of
dichlorophenylphosphine afforded bis[3-tert-butyl-2-meth-
oxymethoxy-5-methylphenyl](phenyl)phosphine (2a) as a
O
O
O
O
O
O
1) n-BuLi (1MR)
2) PhPCl2
HCl
P
2
1
2a
OH
OH
P
HCl
3a
Fig. 1. ORTEP drawing of the molecular structure of 4a. All hydrogen
Scheme 1.
atoms are omitted for clarity. Key atoms are labeled.

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H. Hanaoka et al. / Journal of Organometallic Chemistry 691 (2006) 4968–4974
Table 1
Cl Cl
Ti
˚
O
O
Selected bond lengths (A) and angles (ꢁ) for 4a
˚
Bond lengths (A)
O
O
O
O
TiCl4
P
R
P
R
Ti(1)–Cl(1)
Ti(1)–P(1)
Ti(1)–O(2)
2.321(2)
2.620(2)
1.864(4)
Ti(1)–Cl(2)
Ti(1)–O(1)
Ti(1)–O(3)
2.281(2)
1.822(3)
2.143(4)
Toluene
2b:
2c:
2d:
5b:
5c:
5d:
R = tert-Bu
R = C6H4-2-CH2NMe2
R = C6F5
R = tert-Bu
R = C6H4-2-CH2NMe2
R = C6F5
Bond angles (ꢁ)
Cl(1)–Ti(1)–Cl(2)
Cl(1)–Ti(1)–O(1)
Cl(1)–Ti(1)–O(3)
Cl(2)–Ti(1)–O(1)
Cl(2)–Ti(1)–O(3)
P(1)–Ti(1)–O(2)
O(1)–Ti(1)–O(2)
103.18(7)
89.7(1)
84.7(1)
100.0(1)
93.4(1)
73.8(1)
96.3(2)
Cl(1)–Ti(1)–P(1)
Cl(1)–Ti(1)–O(2)
Cl(2)–Ti(1)–P(1)
Cl(2)–Ti(1)–O(2)
P(1)–Ti(1)–O(1)
P(1)–Ti(1)–O(3)
O(1)–Ti(1)–O(3)
86.53(6)
157.1(1)
169.38(7)
97.5(1)
75.4(1)
91.8(1)
Scheme 4.
ilar to thiobisphenoxy titanium complex [19]. It is notable
that TiCl4 induced the C–O cleavage and selective Ti–O
bond formation when an appropriate protecting group
was chosen [20].
166.4(2)
atoms possessed cis-geometry, required as a polymerization
catalyst. These structural features were revealed by X-ray
analysis of 4a (Fig. 1).
A single crystal of 4a suitable for X-ray diffraction study
was grown from toluene at room temperature. Fig. 1 shows
an ORTEP diagram, and Table 1 lists selected bond
parameters. The ligand is bonded to the octahedral tita-
nium (IV) center in a facial fashion with titanium–phoso-
phine distance 2.620 A, a value comparable to that found
for TiCl4(dppe) (average 2.650 A) [18]. The titanium–oxy-
gen bond distances (1.822 and 1.864 A) are slightly shorter
than those (average 1.888 A) observed for [Ti(tbm-
p)(OiPr)2]2 [19]. The angle of O(1)–Ti(1)–O(2) is 96.3ꢁ, a
value which is a little larger than that observed for [Ti(tbm-
p)(OiPr)2]2 (92.5ꢁ) [19]. Titanium–chlorine bond distances
lie in a range of 2.281–2.321 A, and the angle of Cl(1)–
Ti(1)–Cl(2) is 103.18ꢁ.
We assumed that other bisphenoxy titanium complexes
with different substituents could be synthesized by this
method (Scheme 4). Compounds 2b–2d, prepared in the
same manner as for 2a (68%, 42% and 62% yield, respec-
tively), were applied to the tandem deprotection and Ti–
O bond formation reaction, giving a tert-butylphosphine
complex 5b (62% yield), a 2-(dimethylaminomethyl)-phe-
nylphosphine complex 5c (56% yield), and a pentafluor-
ophenyl complex 5d (69% yield), respectively. In the
31P{1H} NMR spectra of these complexes, 5b–5d, the
chemical shift values were shifted downfield, indicating that
the phosphorous atom also coordinated to the titanium
atom. Complex 5c is expected to show unique properties,
because it has a nitrogen atom as a side-arm donor. Methyl
groups on the nitrogen atom of 5c are observed as two sin-
glet peaks in its 1H NMR spectrum, suggesting the coordi-
nation of the nitrogen atom to the titanium atom.
˚
˚
˚
˚
˚
THF-free titanium complex 5a was prepared by the
reaction of 2a with TiCl4 in toluene in 60% yield. This reac-
tion was more convenient and economical because the
deprotection process, forming 3a, was eliminated. Meth-
oxymethylchloride was observed in the reaction mixture
The complexes obtained were utilized as catalyst precur-
sors for ethylene polymerization. The polymerization
experiments were carried out in a 20 mL autoclave. MMAO
or Al(i-Bu)3/[Ph3C][B(C6F5)4] (TB) was employed as an
activator. The results of ethylene homo polymerization
reaction with 4a and 5a–d are summarized in Table 2. The
1
by H NMR analysis, indicating C–O cleavage selectively
occurred at the aryl methoxymethyl ether position. The
same treatment for the methyl ether derivative, bis(3-tert-
butyl-2-methoxy-5-methylphenyl)(phenyl)phosphine (6),
did not give 5a, but an unidentified mixture, which is prob-
ably due to the strong C–O bond strength of Ar–OMe
(Scheme 3). Complex 5a is expected to exist as a dimer sim-
Table 2
Polymerization of ethylene catalyzed by phosphorous-bridged bis-
phenoxytitanium complexes with co-catalystsa
Co-catalystb
Activityc
Mwd·10ꢀ3
Mw/Mn
d
Entry
Catalyst
1
2
3
4
5
4a
5a
5b
5c
5d
I
1.0
1.3
1.2
36.2
59.9
–
–
–
1700
166
–
–
–
6.2
7.0
Cl Cl
Ti
OR
OR
O
O
P
6
7
8
9
10
a
4a
5a
5b
5c
5d
II
1.3
1.9
3.7
8.8
49.0
–
–
–
1170
34
–
–
–
2.0
2.7
TiCl4
P
Toluene
2a:
R = MOM
6: R = Me
Conditions: toluene; 5 mL, ethylene; 0.6 MPa, temperature; 40 ꢁC.
I: catalyst; 0.1 lmol, MMAO; 100 lmol. II: catalyst; 0.1 lmol, TIBA;
5a
b
60% yield (from 2a)
0% yield (from 6)
40 lmol, TB; 0.3 lmol.
c
In kg mmol (cat)ꢀ1 hꢀ1
Determined by GPC against polystyrene standards.
.
d
Scheme 3.

H. Hanaoka et al. / Journal of Organometallic Chemistry 691 (2006) 4968–4974
4971
ethylene polymerization activities were found to be quite
3.2. Bis[3-tert-butyl-2-methoxymethoxy-5-
methylphenyl](phenyl)phosphine (2a)
excellent in all cases and comparable to those observed in
Ti(tbmp)Cl2 [4,5] and phosphinophenoxyimine titanium
[14] systems. THF seemed to be liberated from 4a when it
was activated by aluminium co-catalyst, as the activity of
4a was almost the same as that of THF free complex 5a.
It is of interest that fluorophenyl-substituted complex 5c
and dimethylaminobenzyl-substituted complex 5d showed
greater activities than hydrocarbon-substituted complexes
5a and 5b (entries 4, 5, 9, and 10). We assumed that a het-
eroatom of the aromatic ring attached to phosphorus coor-
dinated to the active titanium cation species, resulting in the
stabilization of catalytically active species. Polymers with
narrow molecular distribution (Mw/Mn = 2.0 and 2.7) were
obtained when 5c and 5d were activated with TB (entries 9
and 10), showing single site catalysts were generated
through the polymerization systems. Molecular weight of
polyethylene obtained with 5c was very high (>1,000,000),
indicating that b-elimination of active species derived from
5c was thought to be restrained by side-arm nitrogen atom.
To confirm the efficiency of 5c, larger scale polymerization
was carried out in a 300 mL autoclave. The polymerization
gave similarly high molecular weight polyethylene
(Mw = 1,129,000, Mw/Mn = 2.0) with high activity
(28.8 · 106 gmol (cat)ꢀ1 hꢀ1). Further application of the
phosphorous-bridged bisphenoxy titanium complexes and
combinations of these ligands with other metals are cur-
rently in progress.
To a solution of 2-tert-butyl-1-(methoxymethoxy)-4-
methylbenze (10.41 g, 50.0 mmol) in THF (100 mL) was
added a 1.60 M hexane solution of n-BuLi (31.3 mL,
50.0 mmol) at ꢀ78 ꢁC. The mixture was allowed to warm
to 20 ꢁC and additionally stirred for 12 h. Dichlorophenyl-
phosphine (4.47 g, 25.0 mmol) was added to the reaction
mixture cooled at ꢀ78 ꢁC. The mixture was allowed to
warm to 20 ꢁC and stirred for 2 h. Water and toluene were
added to the mixture, and the organic layer was separated.
The organic layer was washed with saturated aqueous
NaCl and dried over Na2SO4. Removal of the solvent fol-
lowed by chromatography on silica (hexane/EtOAc) gave
1a as white solid (8.50 g, 65% yield).
1H NMR (CDCl3) d 1.40 (s, 18H, Ar–t-Bu), 2.13 (s, 6H,
Ar–CH3), 3.51 (s, 6H, OMe), 5.14–5.23 (m, 4H, ArO–CH2–
OMe), 6.39 (dd, 2H, J = 4, 2 Hz, Ar–H), 7.14 (d, 2H,
J = 2 Hz, Ar–H), 7.23–7.31 (m, 5H, Ar–H); 13C{1H}
NMR (CDCl3) d 21.1 (Ar–CH3), 30.8 (Ar–CMe3), 35.1
(Ar–CMe3), 57.3 (ArOCH2OMe), 99.5 (ArOCH2OMe),
128.2 (ArC–H), 129.5 (ArC–H), 131.7, 133.1, 133.2
(ArC–H), 133.6 (ArC–H), 142.8 (ArC–P), 156.2 (ArC–
OCH2OMe); 31P{1H} NMR (CDCl3) d ꢀ18.6. Anal. Calc.
for C32H43O4P: C, 73.54; H, 8.29. Found: C, 73.33; H,
8.27%.
3.3. Bis[3-tert-butyl-2-methoxymethoxy-5-
methylphenyl](tert-butyl)phosphine (2b)
3. Experimental
3.1. General
Reaction of 2-tert-butyl-1-(methoxymethoxy)-4-methyl-
benze with tert-butyldichlorophosphine produced 2b as
white solid (8.54 g, 68% yield).
All manipulations of air- and moisture-sensitive com-
pounds were carried out under dry nitrogen using a Braun
drybox or standard Schlenk line technique. 2-tert-Butyl-1-
(methoxymethoxy)-4-methylbenze (1) [21] and dichloro-
(pentafluorophenyl)phosphine [22] were synthesized by
published methods. Dichloro(2-dimethylaminomethylphe-
nyl)phosphine was prepared by the reaction of phosphorus
trichloride and the lithium salt of N,N-dimethylbenzyl-
amine [23]. Solvents were purchased from Kanto Chemi-
cals Co., Ltd. as anhydrous grade and stored in a drybox
over molecular sieves. Dichloromethane-d2 was purchased
from Aldrich and stored in a drybox over molecular sieves.
1H NMR (270 MHz), 13C NMR (68 MHz) and 31P NMR
(109 MHz) spectra were measured on a JEOL EX270 spec-
trometer. Mass spectra were recorded on a JEOL AX-
505 W. Elemental analyses were performed on an ELE-
MENTAR element analyzer at Sumika Chemical Analysis
Service Ltd. Gel permeation chromatographic analyses
were carried out at 160 ꢁC using a Symyx RapidsGPCꢂ,
equipped with three PLgel 10MICRO METER MIXED-
B columns, and a Tosoh HLC-8121GPC/HT, equipped
with TSKgel GMHHR-H(S)HT. GPC columns were cali-
brated against commercially available polystyrene stan-
dards (Polymer Laboratories).
1H NMR (CDCl3) d 1.11 (d, 9H, JP–H = 13 Hz, P–t-Bu),
1.42 (s, 18H, Ar–t-Bu), 2.25 (s, 6H, Ar–CH3), 3.62 (s, 6H,
OMe), 5.12–5.18 (m, 2H, ArO–CH2–OMe), 5.48–5.54 (m,
2H, ArO–CH2–OMe), 7.01 (t, 2H, J = 2 Hz, Ar–H), 7.14
(d, 2H, J = 2 Hz, Ar–H); 13C{1H} NMR (CDCl3) d 21.3
(Ar–CH3), 29.6 (d, JP–C = 15 Hz, P–CMe3), 30.9 (Ar–
CMe3), 32.6 (d, JP–C = 18 Hz, P–CMe3), 35.1 (Ar–CMe3),
57.4 (ArOCH2OMe), 99.7 (ArOCH2OMe), 129.1 (ArC–
H), 130.9, 132.0, 133.5 (ArC–H), 143.0, 157.0 (ArC–O);
31P{1H} NMR (CDCl3)
d
ꢀ4.7. Anal. Calc. for
C30H47O4P: C, 71.68; H, 9.42. Found: C, 71.65; H, 9.40%.
3.4. Bis[3-tert-butyl-2-methoxymethoxy-5-methylphenyl]-
[2-(dimethylaminomethyl)-phenyl]phosphine (2c)
Reaction of 2-tert-butyl-1-(methoxymethoxy)-4-methyl-
benze with dichloro(2-dimethylaminomethylphenyl)phos-
phine produced 2c as white solid (6.08 g, 42% yield).
1H NMR (CDCl3) d 1.40 (s, 18H, Ar–t-Bu), 2.09 (s, 6H,
Ar–CH3 or NMe2), 2.11 (s, 6H, Ar–CH3 or NMe2), 3.50 (s,
6H, ArOCH2OMe), 3.56 (s, 2H, CH2NMe2), 5.10–5.28 (m,
4H, ArO–CH2–OMe), 6.36 (dd, 2H, J = 4, 3 Hz, Ar–H),
6.88 (ddd, 1H, J = 8, 4, 1 Hz, Ar–H), 7.08–7.16 (m, 3H,

4972
H. Hanaoka et al. / Journal of Organometallic Chemistry 691 (2006) 4968–4974
Ar–H), 7.24–7.34 (m, 1H, Ar–H), 7.44–7.52 (m, 1H, Ar–
H); 13C{1H} NMR (CDCl3) d 21.2 (Ar–CH3), 30.8 (Ar–
CMe3), 35.1 (Ar–CMe3), 45.1 (NMe2), 57.3 (ArO-
CH2OMe), 62.3 (CH2NMe2), 99.2 (ArOCH2OMe), 126.9
(ArC–H), 128.4 (ArC–H), 128.6 (ArC–H), 129.1 (ArC–
H), 131.5, 132.9, 133.5 (ArC–H), 142.6, 155.9 (ArC–O);
for 12 h, the solvent was removed under reduced pressure.
Toluene was added to the residue, subsequently the insolu-
ble material was filtrated off. Evaporation of solvent fol-
lowed by crystallization from toluene gave 4a as red
crystals (0.15 g, 45% yield).
1H NMR (CD2Cl2) d 1.32 (s, 18H, Ar–t-Bu), 1.71–1.78
(m, 4H, THF), 2.14 (s, 3H, Ar–CH3), 4.04–4.14 (m, 4H,
THF), 6.78–6.88 (m, 2H, Ar–H), 7.02–7.12 (m, 2H, Ar–
H), 7.35–7.52 (m, 3H, Ar–H), 7.58–7.68 (m, 2H, Ar–H);
13C{1H} NMR (CD2Cl2) d 23.0 (Ar–Me), 25.7 (THF),
29.5 (Ar–CMe3), 35.2 (Ar–CMe3), 74.7 (THF), 129.4
(ArC–H), 130.5 (ArC–H), 131.3 (ArC–H), 131.9 (ArC–H),
132.7 (ArC–H), 132.9, 133.9, 136.7, 139.5, 170.8 (ArC–O);
31P NMR (CDCl3) d 18.5. EI-MS: m/z 550 (M+ꢀTHF),
515 (M+ꢀTHFꢀCl). Anal. Calc. for C32H41Cl2O3PTi: C,
61.65; H, 6.63. Found: C, 61.40; H, 6.37%.
31P{1H} NMR (CDCl3)
d
ꢀ27.1. Anal. Calc. for
C35H50NO4P: C, 72.51; H, 8.69; N, 2.42. Found: C,
72.58; H, 8.68; N, 2.21%.
3.5. Bis[3-tert-butyl-2-methoxymethoxy-5-
methylphenyl](pentafluorophenyl)phosphine (2d)
Reaction of 2-tert-butyl-1-(methoxymethoxy)-4-methyl-
benze with dichloro(pentafluorophenyl)phosphine pro-
duced 2d as white solid (9.50 g, 62% yield).
1H NMR (CDCl3) d 1.40 (s, 18H, Ar–t-Bu), 2.18 (s, 6H,
Ar–CH3), 3.50 (s, 6H, ArOCH2OMe), 5.15–5.28 (m, 4H,
ArO–CH2–OMe), 6.50–6.55 (m, 2H, Ar–H), 7.16–7.20
(m, 2H, Ar–H); 13C{1H} NMR (CDCl3) d 21.2 (Ar–
CH3), 30.9 (Ar–CMe3), 35.1 (Ar–CMe3), 57.3 (ArO-
CH2OMe), 99.5 (ArOCH2OMe), 127.9, 128.2, 130.4
(ArC–H), 132.1 (ArC–H), 133.6, 143.1, 155.7 (ArC–O);
3.8. Bis[3-tert-butyl-5-methyl-2-phenoxy](phenyl)-
phosphine titanium dichloride (5a)
To a solution of 2a (0.52 g, 1.0 mmol) and toluene
(20 mL) was added a solution of titanium tetrachloride
(0.23 g, 1.2 mmol) in toluene (20 mL) at ꢀ78 ꢁC. The mix-
ture was allowed to warm to 20 ꢁC and was stirred for 20 h.
After removal of the solvent by evaporation to 5 mL, com-
plex deposited was collected by filtration. Recrystallization
from toluene gave 5a (0.33 g, 60% yield) as red solid.
1H NMR (CD2Cl2) d 1.36 (s, 18H, Ar–t-Bu), 2.25 (s, 6H,
Ar–CH3), 6.98–7.06 (m, 2H, Ar–H), 7.10–7.62 (m, 7H, Ar–
H); 13C{1H} NMR (CD2Cl2) d 20.4 (Ar–CH3), 28.8 (Ar–
CMe3), 34.5 (Ar–CMe3), 128.6 (ArC–H), 130.4 (ArC–H),
130.7 (ArC–H), 131.9 (ArC–H), 132.3 (ArC–H), 133.9,
136.1, 137.1, 167.0 (ArC–O); 31P{1H} NMR (CD2Cl2) d
13.3. HRMS: m/z calcd 550.1074, found 550.1089. Anal.
Calc. for C28H33Cl2O2PTi: C, 61.00; H, 6.03. Found: C,
60.90; H, 5.93%.
31P{1H} NMR (CDCl3)
d
ꢀ31.0. Anal. Calc. for
C32H38F5O4P: C, 62.74; H, 6.25. Found: C, 62.74; H,
6.23%.
3.6. Bis[3-tert-butyl-2-hydroxy-5-methylphenyl](phenyl)-
phosphine hydrochloride salt (3a) by deprotection of 2a
To the solution of 2a (3.62 g, 6.9 mmol) in a mixture of
methanol (40 mL) and EtOAc (40 mL) was added acetyl
chloride (2.72 g, 34.6 mmol) at 0 ꢁC. The mixture was
allowed to warm to 20 ꢁC and additionally stirred for
12 h. Removal of the solvent followed by recrystallization
from toluene gave 3a as white solid (2.72 g, 90% yield).
1H NMR (CDCl3) d 1.42 (s, 18H, Ar–t-Bu), 2.23 (s, 6H,
Ar–CH3), 6.63 (dd, 2H, J = 13, 2 Hz, Ar–H), 7.41 (d, 2H,
J = 2 Hz, Ar–H), 7.46–7.61 (m, 4H, Ar–H), 7.64–7.73 (m,
1H, Ar–H), 8.40 (br, 2H, ArO–H), 13.18 (br, 1H, HCl);
13C{1H} NMR (CDCl3) d 20.0 (Ar–CH3), 29.8 (Ar–
CMe3), 35.2 (Ar–CMe3), 129.8 (ArC–H), 130.8 (ArC–H),
131.6, 133.4 (ArC–H), 133.6, 133.7 (ArC-H), 134.9 (ArC–
H), 142.2, 157.1 (2 C, ArC–O); 31P{1H} NMR (CDCl3) d
ꢀ14.9. Anal. Calc. for C28H36ClO2P: C, 71.40; H, 7.70.
Found: C, 71.52; H, 7.76%.
3.9. Bis[3-tert-butyl-5-methyl-2-phenoxy](tert-butyl)-
phosphine titanium dichloride (5b)
1
Yield (62%). H NMR (CD2Cl2) d 1.37 (s, 18H, Ar–t-
Bu), 1.43 (d, 9H, JP–H = 17 Hz, P–t-Bu), 2.34 (s, 6H, Ar–
CH3), 7.26–7.29 (m, 2H, Ar–H), 7.33–7.37 (m, 2H, Ar–
H); 13C{1H} NMR (CD2Cl2) d 20.5 (Ar–CH3), 26.6 (d,
JP–C = 6 Hz, P–CMe3), 28.9 (Ar–CMe3), 31.3 (Ar–CMe3),
34.6 (d, JP–C = 2 Hz, P–CMe3), 130.8 (ArC–H), 132.3
(ArC–H), 133.8, 136.2, 138.6, 168.3 (ArC–O); 31P{1H}
NMR (CD2Cl2) d 31.0. HRMS: m/z calcd 530.1388, found
530.1409. Anal. Calc. for C26H37Cl2O2PTi: C, 58.77; H,
7.02. Found: C, 59.16; H, 7.03%.
3.7. Bis[3-tert-butyl-5-methyl-2-phenoxy](phenyl)-
phosphine tetrahydrofuran titanium dichloride (4a)
To a solution of 3a (0.25 g, 0.5 mmol) in tetrahydrofu-
ran (10 mL) was added a 1.60 M hexane solution of n-BuLi
(0.63 mL, 1.0 mmol) at ꢀ78 ꢁC. The mixture was stirred for
12 h at 20 ꢁC then cooled again to ꢀ78 ꢁC. To the mixture
was added a solution of titanium tetrachloride tetrahydro-
furan complex (0.18 g, 0.5 mmol) in tetrahydrofuran
(5 mL) then warmed to 20 ꢁC. After the mixture was stirred
3.10. Bis[3-tert-butyl-5-methyl-2-phenoxy][2-(dimethyl-
aminomethyl)-phenyl] phosphine titanium dichloride (5c)
1
Yield (56%). H NMR (CD2Cl2) d 1.38 (s, 18H, Ar–t-
Bu), 2.21 (s, 6H, Ar–CH3), 2.68 (s, 3H, NMe), 2.70 (s,
3H, NMe), 4.32 (m, 2H, Ar–CH2–NMe2), 6.73–6.77 (m,

H. Hanaoka et al. / Journal of Organometallic Chemistry 691 (2006) 4968–4974
4973
Table 3
2H, Ar–H), 7.10–7.12 (m, 2H, Ar–H), 7.45–7.63 (m, 3H,
Ar–H), 7.98–8.02 (m, 1H, Ar–H); 13C{1H} NMR (CD2Cl2)
d 20.5 (Ar–CH3), 28.8 (Ar–CMe3), 34.5 (Ar–CMe3), 43.8
(NMe2), 62.7 (ArCH2N), 126.9 (ArC–H), 127.8 (ArC–H),
127.9 (ArC–H), 128.6 (ArC–H), 128.9 (ArC–H), 130.6,
130.7 (ArC–H), 131.5, 135.9, 137.3, 171.8 (ArC–O);
31P{1H} NMR (CD2Cl2) d 16.4. HRMS: m/z calcd
607.1653, found 607.1659.
Crystal data and data collection parameters of 4a
Empirical formula
Formula weight
Crystal system
C32H41Cl2O3PTi
623.45
Triclinic
9.0430(5)
9.7206(4)
19.1903(9)
101.701(1)
94.308(1)
89.917(3)
1647.0(1)
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3.11. Bis[3-tert-butyl-5-methyl-2-phenoxy](pentafluoro-
phenyl)phosphine titanium dichloride (5d)
3
˚
V (A )
ꢀ
Space group
Z value
Dcalc (g/cm3)
Diffractometer
Radiation
P1 (#2)
2
1
1.257
Yield (69%). H NMR (CD2Cl2) d 1.33 (s, 18H, Ar–t-
Rigaku RAXIS-RAPID
Cu Ka (k = 1.54178 A)
Bu), 2.26 (s, 6H, Ar–CH3), 6.95–7.05 (m, 2H, Ar–H),
7.13–7.21 (m, 2H, Ar–H); 13C{1H} NMR (CD2Cl2) d
20.5 (Ar–CH3), 28.7 (Ar–CMe3), 34.6 (Ar–CMe3), 121.5,
122.5, 128.4, 129.5 (ArC–H), 131.7 (ArC–H), 134.0,
136.4, 145.6, 146.1, 167.0 (ArC–O); 31P{1H} NMR
(CD2Cl2) d 2.2. HRMS: m/z calcd 640.0604, found
640.0582.
˚
Graphite monochromated
2hmax (ꢁ)
No. of reflections measured
136.3
Total: 34,762
Unique: 5499 (Rint = 0.037)
Structure solution
Direct methods (SHELX97)
Refinement
Full-matrix least-squares on F
No. observations (I > 3.00r(I))
Residuals: R (I > 3.00r(I))
Residuals: Rw (I > 3.00r(I))
3929
0.069
0.086
3.12. Crystallographic analysis of 4a
A red block crystal of 4a was mounted in glass and the
intensity data were collected on a Rigaku RAXIS-RAPID
Imaging Plate diffractometer with graphite monochro-
mated Cu Ka radiation. The structure was solved by a
direct method (SHELX97) and refined by the full-matrix
least-squares methods [24]. Crystal data and details of
refinement are summarized in Table 3. The final
discrepancy indices are R = 0.069 and Rw = 0.086. All
calculations were performed using the CrystalStructure
crystallographic software package (Rigaku/MSC).
pressure in the cell was slowly vented. The glass vial insert
was then removed from the pressure cell and the volatile
components were removed using a centrifuge vacuum
evaporator to give polymer product.
3.14. Polymerization of ethylene catalyzed by titanium
complexes 5c in 300 mL autoclave
An autoclave having an inner volume of 300 mL was
dried under vacuum and purged with nitrogen. The vessel
was then charged with toluene (150 mL) and heated to
40 ꢁC. After ethylene was introduced (0.6 MPa), tri-
isobutylaluminium (0.60 mmol, 1.0 M toluene solution)
was added. Subsequently, a catalyst precursor (1.0 lmol,
1 mM toluene solution) and TB (6.0 lmol, 6 mM toluene
solution) were added. Polymerization was carried out at
40 ꢁC for 5 min, and the reaction was quenched by adding
methanol (5 mL). The reaction mixture was then poured
into acidic methanol (500 mL with 1 mL of 5% HCl).
The polymer was collected by filtration and washed with
methanol, and dried in a high vacuum oven at 80 ꢁC for
2 h to constant weight.
3.13. Polymerization of ethylene catalyzed by titanium
complexes 4a and 5a–5d in 20 mL autoclave
A pre-weighed glass vial insert and disposable stirring
paddle were fitted to each reaction vessel of the reactor.
The reactor was then closed, and 0.25 M triisobutylalumin-
ium (160 lL) and toluene were injected into each reaction
vessel through a valve. The total volume of reaction mix-
ture was adjusted to 5 mL with toluene. The temperature
was then set to 40 ꢁC, the stirring speed was set to
800 rpm, and the mixture was pressurized to 0.6 MPa. Tol-
uene solution of titanium complex (0.1 lmol, 1 mM tolu-
ene solution) was added, followed by toluene solution of
TB (0.3 lmol, 1 mM toluene solution). When MMAO
was used as a co-catalyst, MMAO (100 lmol, 0.25 M tolu-
ene solution) and a catalyst precursor (0.1 lmoL, 1 mM
toluene solution) were added. Ethylene pressure in the cell
and the temperature setting were maintained by computer
control until the end of the polymerization experiment.
The polymerization reactions were allowed to continue
for 20 min unless consumption of ethylene reached pre-
set levels. After polymerization reaction, the temperature
was allowed to drop to room temperature and the ethylene
Acknowledgement
The authors thank for Dr. K. Yanagi (Dainippon Sumi-
tomo Pharma Co., Ltd.) for X-ray analysis of 4a.
Appendix A. Supplementary data
Supplementary data associated with this article can
be found, in the online version, at doi:10.1016/
j.jorganchem.2006.08.036.

4974
H. Hanaoka et al. / Journal of Organometallic Chemistry 691 (2006) 4968–4974
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