Cationic Group 4 metal alkyl compounds containing aryloxide ligation: Synthesis, structure, reactivity and polymerization studies

Article abstract of DOI:10.1016/S0022-328X(99)00409-X

A series of bis(alkyl) derivatives of titanium and zirconium [(ArO)₂MR₂] (M=Ti, Zr; R=Me, CH₂Ph; ArO=various 2,6-di-substituted phenoxides) has been synthesized and their reactivity towards the Lewis acid [B(C₆F₅)₃] examined. The benzyl compounds generate stable zwitterionic species such as [M(OC₆HPh₂-2,6-R₂-3,5)₂(CH ₂Ph)][η⁶-C₆H₅CH ₂B(C₆F₅)₃] (M=Ti, R=H, 12; Me, 13: M=Zr, R=Me, 15). Structural studies of 12 and 15 show the boron anion π-bound to the metal center through the original benzyl phenyl ring. In contrast, treatment of the benzyl compound [Zr(OC₆H₃Bu^t₂-2,6) ₂(CH₂Ph)₂] with [B(C₆F₅)₃] leads to the cyclometallated compound [Zr(OC₆H₃Bu^t-CMe₂CH ₂)(OC₆H₃Bu^t ₂-2,6)][η⁶-C₆H₅CH ₂B(C₆F₅)₃] 16 which was structurally characterized. In contrast to this behavior the bis(methyl) species react with [B(C₆F₅)₃] to produce unstable methyl cationic intermediates which decompose to a mixture of [Ti(OAr)₂(CH₃)(C₆F₅)] and [CH₃B(C₆F₅)₂]. The titanium zwitterionic benzyl compounds will react with alkynes and α-olefins to produce mono-insertion products such as [Ti(OC₆H₃Ph₂-2,6)₂{C(CH ₃)C(Ph)CH₂(η⁶-C₆H ₅)}][PhCH₂B(C₆F₅)₃] 24. In these compounds 1,2-insertion of olefins occurs followed by chelation of the original benzyl group to the metal center. Spectroscopic studies show the boron anion is non-coordinated to the metal center. Despite their thermal instability, the methyl cations can be generated in situ in the presence of olefins to produce polymers (ethene and propene) and oligomers (1-hexene). Studies show that the molecular weight of the polymers or oligomers increases systematically with the bulk of the aryloxide ligand. Spectroscopic studies of the polypropylene indicate 1,2-insertion is occurring with β-hydrogen abstraction to produce vinylidene end groups as the termination step.

Full text of DOI:10.1016/S0022-328X(99)00409-X

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 591 (1999) 148–162
Cationic Group 4 metal alkyl compounds containing aryloxide
ligation: synthesis, structure, reactivity and polymerization studies
Matthew G. Thorn, Zac C. Etheridge, Phillip E. Fanwick, Ian P. Rothwell *
Department of Chemistry, 1393 Brown Building, Purdue Uni6ersity, West Lafayette, IN 47907-1393, USA
Received 2 June 1999; accepted 25 June 1999
Abstract
A series of bis(alkyl) derivatives of titanium and zirconium [(ArO)2MR2] (M=Ti, Zr; R=Me, CH2Ph; ArO=various
2,6-di-substituted phenoxides) has been synthesized and their reactivity towards the Lewis acid [B(C6F5)3] examined. The benzyl
compounds generate stable zwitterionic species such as [M(OC6HPh2-2,6-R2-3,5)2(CH2Ph)][h6-C6H5CH2B(C6F5)3] (M=Ti, R=
H, 12; Me, 13: M=Zr, R=Me, 15). Structural studies of 12 and 15 show the boron anion p-bound to the metal center through
the original benzyl phenyl ring. In contrast, treatment of the benzyl compound [Zr(OC6H3But2-2,6)2(CH2Ph)2] with [B(C6F5)3]
leads to the cyclometallated compound [Zr(OC6H3But-CMe2CH2)(OC6H3But2-2,6)][h6-C6H5CH2B(C6F5)3] 16 which was struc-
turally characterized. In contrast to this behavior the bis(methyl) species react with [B(C6F5)3] to produce unstable methyl cationic
intermediates which decompose to a mixture of [Ti(OAr)2(CH3)(C6F5)] and [CH3B(C6F5)2]. The titanium zwitterionic benzyl
compounds will react with alkynes and a-olefins to produce mono-insertion products such as [Ti(OC6H3Ph2-
2,6)2{C(CH3)C(Ph)CH2(h6-C6H5)}][PhCH2B(C6F5)3] 24. In these compounds 1,2-insertion of olefins occurs followed by chelation
of the original benzyl group to the metal center. Spectroscopic studies show the boron anion is non-coordinated to the metal
center. Despite their thermal instability, the methyl cations can be generated in situ in the presence of olefins to produce polymers
(ethene and propene) and oligomers (1-hexene). Studies show that the molecular weight of the polymers or oligomers increases
systematically with the bulk of the aryloxide ligand. Spectroscopic studies of the polypropylene indicate 1,2-insertion is occurring
with b-hydrogen abstraction to produce vinylidene end groups as the termination step. © 1999 Elsevier Science S.A. All rights
reserved.
Keywords: Titanium; Zirconium; Alkyl; Phenoxides; Zwitterionic polymerization
ongoing studies of bulky aryloxide ligation, we have
investigated the potential of these monodentate ligands
1. Introduction
for carrying out olefin polymerization at Group 4 metal
There has been an explosive growth of research
centers [8–10]. In this paper, we report on the forma-
interest into the use of non-cyclopentadienyl ligation
tion and chemistry of a series of cationic alkyl deriva-
for supporting organometallic chemistry at early d-
tives of titanium and zirconium. Polymerization studies
block metal centers [1]. The replacement of the ubiqui-
show that the polymer properties are dependent on the
tous cyclopentadiene ligands by ‘hard’ donor ligands
nature of the aryloxide ligands.
such as amido [2], alkoxide [3], siloxide [4] and arylox-
ide [5] groups has generated both complementary and
novel reactivity. One exciting development has been in
the use of these ligands to carry out the polymerization
of olefins by well-defined cationic catalyst systems [6].
In the case of amido ligation, new, living polymeriza-
tion catalysts have been developed [7]. As part of our
2. Results and discussion
2.1. Synthesis and characterization of alkyl precursors
There are two synthetic strategies that have been
developed for the generation of bis(alkyl), bis(arylox-
ides) of titanium and zirconium. The first method in-
* Corresponding author. Fax: +1-765-494-0239.
E-mail address: rothwell@purdue.edu (I.P. Rothwell)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00409-X

M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
149
Scheme 1.
Table 1
,
Selected bond distances (A) and angles (°) for [Ti(OC6H3Ph2-
2,6)2(CH2Ph)2] 3
Bond distances
TiꢀO(1)
TiꢀO(2)
1.797(3)
1.784(3)
TiꢀC(30)
TiꢀC(40)
2.078(5)
2.091(5)
Bond angles
O(1)ꢀTiꢀO(2)
O(1)ꢀTiꢀC(30)
O(1)ꢀTiꢀC(40)
O(2)ꢀTiꢀC(30)
O(2)ꢀTiꢀC(40)
122.6(1)
106.0(2)
109.0(2)
108.0(2)
103.2(2)
C(30)ꢀTiꢀC(40)
TiꢀO(1)ꢀC(11)
TiꢀO(2)ꢀC(21)
TiꢀC(30)ꢀC(31)
TiꢀC(40)ꢀC(41)
107.3(2)
161.4(3)
168.3(3)
102.1(3)
113.1(1)
obtained by treatment of [TiMe4] generated in situ with
two equivalents of phenol (Scheme 1) [14]. The solid-
state structure of dimethyl 8 (Fig. 2 and Table 2) again
shows a pseudo-tetrahedral metal environment. Some
of the structural parameters for 3 and 8 will be dis-
cussed in more detail below.
Fig. 1. ORTEP view of [Ti(OC6H3Ph2-2,6)2(CH2Ph)2] (3).
volves the alkylation of di-chloride precursors such as 1
[11] and 2 (Scheme 1). By this method the titanium
bis(benzyl) derivatives 3–5 can be obtained. A solid-
state structure on 3 (Fig. 1 and Table 1) shows a
pseudo-tetrahedral environment about the Ti metal
center with both benzyl ligands being h1-bound [12]. In
the case of zirconium, corresponding di-chlorides are
not available. Hence the bis(benzyl) compounds 6 and 7
can be generated by treatment of precursor
[Zr(CH2Ph)4] [13] with two equivalents of the corre-
sponding parent phenol (Scheme 1). A series of
dimethyl derivatives of titanium 8–11 has also been
2.2. Formation of cationic alkyl compound
Hydrocarbon solutions of the bis(benzyl) derivatives
3–7 react rapidly (1H-NMR) with the reagent
[B(C6F5)3] [15] to produce a series of zwitterionic
organometallic species 12–16 (Scheme 2). Four of the
compounds, 12–15, are simply the result of abstraction
of a benzyl ligand from the metal by the Lewis acidic
boron reagent. However, in the case of 16 abstraction is
followed by facile CH bond activation of an ortho-tert-

150
M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
Fig. 2. ORTEP view of [Ti(OC6H3Ph2-2,6)2(CH3)2] (8).
Table 2
Selected
[Ti(OC6H3Ph2ꢀ2,6)2(CH3)2] 8
ence of the cyclometallated ring results in non-equiva-
lent ortho and meta aromatic protons and
,
bond
distances
(A)
and
angles
(°)
for
Bond distances
TiꢀO(10)
TiꢀO(20)
1.795(1)
1.791(1)
TiꢀC(1)
TiꢀC(2)
2.069(2)
2.052(2)
Bond angles
O(10)ꢀTiꢀO(20)
O(10)ꢀTiꢀC(1)
O(10)ꢀTiꢀC(2)
O(20)ꢀTiꢀC(1)
126.19(7)
107.06(9)
106.67(8)
104.29(9)
O(20)ꢀTiꢀC(2)
C(1)ꢀTiꢀC(2)
TiꢀO(10)ꢀC(11)
TiꢀO(20)ꢀC(21)
106.77(8)
103.9(1)
162.6(1)
164.5(1)
butyl group leading to elimination of toluene and for-
mation of six-membered, oxa-metallacycle ring
a
(Scheme 2). The cyclometallation of 2,6-di-tert-
butylphenoxide by a variety of early d-block metal
systems has been well documented and studied [16]. In
all five compounds there is spectroscopic evidence for
the presence of an [(ArCH2)B(C6F5)3]− anion p-bound
to the metal center through the benzyl arene ring.
1
Hence in the H-NMR spectra of compounds 12, 14
and 15 three multiplets are observed upfield of the
aromatic region which can be assigned to the ortho,
meta and para protons on the p-bound C6H5ꢀCH2B
ring. In 4-methylbenzyl derivative 13 only a pair of
doublets is observed due to the presence of the methyl
substituent. The presence of equivalent ortho and meta
protons combined with the presence of singlets for the
TiꢀCH2Ar and ArCH2B protons implies the presence of
a mirror plane through the molecule in solution. This
contrasts with the observed solid-state structures (vide
infra), which would produce non-equivalent ortho and
meta protons and diasterotopic methylene protons.
Hence, either a higher symmetry structure is adopted in
solution or more likely there is facile rotation of the
p-bound arene on the NMR time-scale. In the case of
the 2,6-di-tert-butylphenoxide derivative 16, the pres-
Scheme 2.

M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
151
Fig. 3. ORTEP view of [Ti(OC6H3Ph2-2,6)2(CH2Ph)][h6-C6H5CH2B(C6F5)3] (12) with C6F5 groups omitted for clarity.
,
A found for the other five Ti–C distances. Similarly in
diastereotopic PhCH2ꢀB protons for the p-bound an-
ion. In this case even facile anion rotation cannot
generate a mirror plane of symmetry.
,
15 the ZrꢀC(ipso) distance of 2.821(4) A is also longer
,
than the other distances of 2.653(4)–2.764(4) A. A
In the 13C-NMR spectra of the zwitterionic benzyl
compounds 12–15, the TiꢀCH2 carbon atom resonates
only slightly downfield of its position for the neutral
precursors. Hence this signal is found at l 101.2 and
70.6 for Ti and Zr species 12 and 15 compared to l 94.0
and 68.7 for corresponding precursors 3 and 6. In the
case of the cyclometallated compound 16, the non-
equivalence of the aryloxide ligands is demonstrated by
the presence of two ZrꢀOꢀC resonances compared to
only one corresponding signal in 12–15.
The solid-state structures of the zwitterionic species
12, 15 and 16 were determined (Figs. 3–5 and Tables
3–5). In all three compounds the anion can be seen to
be p-bound to the metal center through the benzyl
arene ring. However, the MꢀC distances in these d0-
complexes are much longer than reported for lower-va-
lent arene derivatives of these metals. In the anion
[Ti(h6-C6H5Ph)2]− the average TiꢀC(arene) distance is
similar assymmetry in the bonding of benzyl boron
anions to zirconium metal centers in compounds
[Zr(CH2Ph)3{h6-PhCH2B(C6F5)3}] [22] and [CpZr-
(CH2Ph)2{h6-PhCH2B(C6F5)3}] [23] has been noted. In
one case the distortion was interpreted as representing
an h5-interaction. However, it can be seen in 16, which
contains the bulkiest aryloxide, that there is a definite
elongation of two adjacent ZrꢀC(arene) distances,
,
2.803(3) and 2.851(3) A compared with distances to
other carbon atoms. It would, therefore, appear in
these compounds that the non-symmetric bonding of
the arene rings reflects simple steric factors with the
rings slipping to minimize unfavorable interactions.
6
i
+
,
2.27(2) A [17], while in the cation [Ti(h -C6H3Pr3)2]
,
the range is 2.27(2)–2.33(2) A [18]. This compares with
values of 2.538(7)–2.627(6) A found for 12 (Table 3).
These distances are comparable to the values of
,
6
+
,
2.46(1)–2.52(1) A reported for [(h -C6Me6)TiCl3]
cation [19]. For the 18-electron zirconium complex
[(h6-C6H3Me3)2Zr(m-Cl)2AlCl2][Al2Cl7] [20] the average
,
ZrꢀC(arene) distances are reported as 2.54 A compared
with the ranges of 2.653(4)–2.821(4) and 2.670(4)–
,
2.851(3) A for 15 and 16, respectively [21]. It can also
be seen that in all three compounds the metal to
carbon(arene) distances are not equivalent. In the tita-
nium compound 12 the TiꢀC(ipso) distance of 2.627(6)
Fig. 4. ORTEP view of [Zr(OC6HPh2-2,6-Me2-3,5)2(CH2Ph)][h6-
C6H5CH2B(C6F5)3] (15) with C6F5 groups omitted for clarity.
,
A is slightly longer than the values of 2.538(7)–2.566(7)

152
M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
Fig. 5. ORTEP view of [Zr(OC6H3ButꢀCMe2CH2)(OC6H3Bu2t -2,6)][h6-C6H5CH2B(C6F5)3] (16) with C6F5 groups omitted for clarity.
Table 3
The MꢀOAr distances in the zwitterionic compounds
12 and 15 (Tables 3 and 4) are among the shortest for
these types of ligands bound to titanium and zirconium.
This presumably is a reflection of the high electrophilic-
ity of the cationic metal center. In both the neutral
precursors and zwitterionic compounds the MꢀOꢀAr
angles are almost linear. Previous work has shown that
this parameter cannot be used as a measure of the
amount of oxygen-p to metal-d p-bonding [24]. This is
highlighted by the cyclometallated compound 16 (Table
5) where the chelated phenoxide, 137° (average for two
independent molecules) angle, has an essentially identi-
cal ZrꢀO distance to that found for the terminal arylox-
ide which has a larger, 165° (av.), ZrꢀOꢀAr angle.
The addition of [B(C6F5)3] to C6D6 solutions of the
pale yellow dimethyl compounds 8 and 9 immediately
results in formation of dark red solutions. Analysis by
1H-NMR of these solutions showed the presence of the
expected abstraction products 17 and 18 (Scheme 3).
Equal intensity, broad resonances for the TiꢀMe and
MeꢀB protons were observed. However, both reaction
mixtures contained varying amounts of other species.
Over the course of 1 h at ambient temperature, peaks
due to the initial abstraction compounds 17 and 18
were replaced by a set of signals due to three other
species. In both cases an equimolar mixture of
[(ArO)2Ti(Me)(C6F5)] (20 or 23) along with the boron
compound [MeB(C6F5)2] 21 were observed as the major
decomposition products (Scheme 3). These compounds
arise via abstraction of a perfluorophenyl group from
the [MeB(C6F5)3]− anion by the electrophilic titanium
metal center. The mono-methyl compounds 20 and 23
are characterized in the 1H-NMR by a well-resolved
,
Selected bond distances (A) and angles (°) for [Ti(OC6H3Ph2ꢀ2,6)2-
(CH2Ph)(h6ꢀC6H5CH2B{C6F5}3)] 12
Bond distances
TiꢀO(2)
TiꢀO(3)
TiꢀC(40)
TiꢀC(1)
TiꢀC(2)
TiꢀC(3)
TiꢀC(4)
1.761(5)
1.795(4)
2.159(9)
2.627(6)
2.555(6)
2.543(7)
2.566(7)
TiꢀC(5)
TiꢀC(6)
C(40)ꢀC(41)
C(1)ꢀC(10)
C(10)ꢀB(10)
O(2)ꢀC(21)
O(3)ꢀC(31)
2.538(7)
2.558(7)
1.53(1)
1.488(8)
1.692(9)
1.376(8)
1.374(7)
Bond angles
O(2)ꢀTiꢀO(3)
O(2)ꢀTiꢀC(40)
O(3)ꢀTiꢀC(40)
C(21)ꢀO(2)ꢀ Ti
C(31)ꢀO(3)ꢀ Ti
110.0(2)
96.6(3)
97.8(3)
158.9(5)
158.8(4)
C(41)ꢀC(40)ꢀTi
C(1)ꢀC(10)ꢀB(10)
C(10)ꢀB(10)ꢀC(111)
120.6(6)
116.5(5)
101.9(5)
Table 4
,
Selected bond distances (A) and angles (°) for [Zr(OC6HPh2ꢀ2,6ꢀ
Me2ꢀ3,5)2(CH2Ph)(h6ꢀC6H5CH2B{C6F5}3)] 15
Bond distances
ZrꢀO(2)
ZrꢀO(3)
ZrꢀC(40)
ZrꢀC(1)
ZrꢀC(2)
ZrꢀC(3)
ZrꢀC(4)
1.893(3)
1.900(3)
2.230(4)
2.821(4)
2.653(4)
2.662(4)
2.681(5)
ZrꢀC(5)
ZrꢀC(6)
C(40)ꢀC(41)
C(1)ꢀC(10)
C(10)ꢀB(10)
O(2)ꢀC(21)
O(3)ꢀC(31)
2.694(4)
2.764(4)
1.495(6)
1.482(6)
1.691(6)
1.380(5)
1.365(5)
Bond angles
O(2)ꢀZrꢀO(3)
O(2)ꢀZrꢀC(40)
O(3)ꢀZrꢀC(40)
C(21)ꢀO(2)ꢀZr
C(31)ꢀO(3)ꢀZr
113.6(1)
99.4(2)
99.6(1)
165.3(3)
170.5(3)
C(41)ꢀC(40)ꢀZr
C(1)ꢀC(10)ꢀB(10)
C(10)ꢀB(10)ꢀC(111)
117.4(3)
111.4(3)
109.8(3)

M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
153
Table 5
2.3. Stoichiometric reacti6ity towards olefins and alkynes
t
,
Selected bond distances (A) and angles (°) for [Zr(OC6H3Bu2ꢀ2,6)-
(OC6H3But-2-{CH2CMe2}-6)(h6-C6H5CH2B{C6F5}3)] 16
The zwitterionic compounds 12 and 14, either iso-
lated or generated in situ, will react stoichiometrically
with one equivalent of added alkyne or olefin (Scheme
4). In all cases the resulting products are salts that
contain the [PhCH2B(C6F5)3]− anion, whose BꢀCH2
protons can be observed in the 1H-NMR spectrum
(C6D6) as a broad resonance at l 3.1–3.3 ppm. Unfor-
tunately all of these salt products have resisted all
attempts at crystallization. However, the spectroscopic
properties of their cations is consistent with their for-
mulation as shown (Scheme 4). The mono-insertion of
one equivalent of alkyne or olefin into the Ti+ꢀCH2Ph
bond has occurred followed by chelation to the cationic
metal center by the phenyl ring originally contained in
the benzyl ligand. There is excellent precedent in the
literature for the formation of similar chelate rings.
Specifically, the work of Pellechia et al. has shown that
single insertion of a-olefins into the ZrꢀC bonds of
cationic benzyls [Zr(CH2Ph)3]+ and [CpZr(CH2Ph)2]+
leads to analogous compounds. One such derivative
[Cp*Zr{CH2CH(Me)CH2(h6-C6H5)}(CH2Ph)] [PhCH2-
B(C6F5)3] was structurally characterized [25]. The
phenyl ring was found to be h6-bound to the zirconium
Molecule 1
Zr(1)ꢀO(141)
Zr(1)ꢀO(111)
Zr(1)ꢀC(122)
Zr(1)ꢀC(11)
Zr(1)ꢀC(12)
Zr(1)ꢀC(13)
Zr(1)ꢀC(14)
Zr(1)ꢀC(15)
Zr(1)ꢀC(16)
C(121)ꢀC(122)
1.920(2)
1.922(2)
2.240(4)
2.670(4)
2.671(4)
2.717(3)
2.851(3)
2.803(3)
2.725(4)
1.563(3)
C(17)ꢀB(1)
1.693(5)
O(111)ꢀZr(1)ꢀO(141)
O(111)ꢀZr(1)ꢀC(122)
O(141)ꢀZr(1)ꢀC(122)
Zr(1)ꢀO(111)ꢀC(111)
Zr(1)ꢀO(141)ꢀC(141)
Zr(1)ꢀC(122)ꢀC(121)
C(121)ꢀC(112)ꢀC(111)
C(112)ꢀC(111)ꢀO(111)
114.4(1)
84.9(1)
103.9(1)
138.8(2)
166.5(2)
115.3(3)
122.4(3)
117.1(3)
Molecule 2
Zr(2)ꢀO(241)
Zr(2)ꢀO(211)
Zr(2)ꢀC(222)
Zr(2)ꢀC(21)
Zr(2)ꢀC(22)
Zr(2)ꢀC(23)
Zr(2)ꢀC(24)
Zr(2)ꢀC(25)
Zr(2)ꢀC(26)
C(221)ꢀC(222)
1.916(2)
1.907(2)
2.236(4)
2.657(4)
2.721(4)
2.803(3)
C(27)ꢀB(2)
1.680(5)
O(211)ꢀZr(2)ꢀO(241)
O(211)ꢀZr(2)ꢀC(222)
O(241)ꢀZr(2)ꢀC(222)
Zr(2)ꢀO(211)ꢀC(211)
Zr(2)ꢀO(241)ꢀC(241)
Zr(2)ꢀC(222)ꢀC(221)
C(221)ꢀC(212)ꢀC(211)
C(212)ꢀC(211)ꢀO(211)
111.4(1)
85.5(1)
107.3(1)
137.5(2)
164.1(2)
115.3(2)
122.1(3)
116.6(3)
2.722(3)
2.661(4)
1.574(5)
,
metal center with ZrꢀC distances of 2.42(2)–2.69(2) A.
These distances are similar to those found in zwitteri-
onic arene compounds such as 15 and 16. Spectroscop-
ically the insertion of phenylpropyne leads to cations 24
and 25 that contain a plane of symmetry. This gener-
ates three resolvable multiplets upfield of the normal
1
aromatic region in the H-NMR spectra for the ortho,
meta and para protons of the p-bound phenyl ring. The
presence of a single TiꢀOꢀC resonance in the 13C-NMR
spectrum indicates equivalent aryloxide ligands. The
TiꢀC(Me)ꢁC(Ph) carbon for 24 resonates at l 231.6
ppm in the 13C-NMR spectrum. This is a region typical
for TiꢀC(vinyl) groups. The proposed regiochemistry
for 24 and 25 is based upon the upfield shift of the
methyl protons within the alkyl chain. This is consistent
with this methyl group being attached to the a-carbon,
TiꢀC(Me)ꢁC(Ph), and being upfield shifted by the adja-
cent 2,6-diphenylphenoxide ligands in 24. This signal is
shifted even more upfield on changing the aryloxide
ligands to the meta-methyl-substituted 2,6-diphenylphe-
noxide 25. Previous studies have shown that the intro-
duction of meta-substituents onto the central nucleus of
2,6-diphenylphenoxide ligands causes a decrease in con-
formation flexibility for the ortho-phenyl rings. This
generates a greater amount of diamagnetic shielding by
the ortho-phenyl ring of protons attached to other
ligands within the coordination sphere [5c].
Scheme 3.
triplet for the TiꢀMe protons, which are weakly
coupled to the two ortho-F substituents of the adjacent
perfluorophenyl group. In the boron compound
[MeB(C6F5)2], it is possible to resolve a broad pentet
structure for the methyl group, again due to coupling to
four ortho-F substituents. A minor component of these
reaction mixtures was identified as the mono-methyl
compounds [(ArO)3TiMe] 19, 22. These compounds can
be independently synthesized by adding one equivalent
of phenol to dimethyl compounds 8 and 9. Crystals of
2,6-diphenylphenoxide 19 were obtained from one of
the reaction mixtures and structurally characterized
(Fig. 6, Table 6). The origins of this decomposition
by-product are presently unknown.
The addition of a-olefins to zwitterions 12 and 14
leads to cations 26–30, where the alkyl chelate back-

154
M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
Fig. 6. ORTEP view of [Ti(OC6H3Ph2-2,6)3(CH3)] (19).
Table 6
that the insertion of a-olefins is taking place in a
1,2-fashion
,
Selected bond distances (A) and angles (°) for [Ti(OC6H3Ph2-
2,6)3(CH3)] 19
2.4. Polymerization studies
Bond distances
TiꢀO(1)
TiꢀO(2)
1.793(2)
1.798(2)
TiꢀO(3)
TiꢀC(4)
1.793(3)
2.070(4)
The zwitterionic benzyl species 12–16 fail to act as
active catalysts for the polymerization of olefins. The
reasons for this undoubtedly rest in the stability of the
cations such as 26–30 (Scheme 4) formed after initial
insertion of one equivalent of olefin. Although cationic
methyl species such as 17 and 18 (Scheme 3) undergo
facile decomposition, activation of the dimethyl com-
pounds 8–11 with [B(C6F5)3] in the presence of olefin
does lead to the formation of polymers and oligomers.
Table 7 contains information concerning the polymer-
ization of ethylene and propene by these catalyst sys-
tems. In all cases it can be seen that the polydispersities
are low and consistent with the presence of a single
active site. Furthermore, the polymer molecular weight
can be seen to be highly dependent on the nature of the
aryloxide ligand within the catalyst precursor. As the
bulk of the aryloxide increases, it can be seen that the
polymer molecular weight increases. Analysis of the
Bond angles
O(1)ꢀTiꢀC(4)
O(2)ꢀTiꢀC(4)
O(3)ꢀTiꢀC(4)
O(1)ꢀTiꢀO(2)
O(1)ꢀTiꢀO(3)
103.5(1)
101.9(4)
106.0(1)
119.5(1)
110.4(1)
O(2)ꢀTiꢀO(3)
TiꢀO(1)ꢀC(11)
TiꢀO(2)ꢀC(21)
TiꢀO(3)ꢀC(31)
113.7(2)
159.8(2)
169.7(2)
162.5(2)
bone lacks a plane of symmetry. Hence in these species
five multiplets can be resolved for the h6-C6H5 protons
1
in the H-NMR spectrum. Two separate TiꢀOꢀC sig-
nals are also present in the 13C-NMR spectra due to
non-equivalent aryloxides. The regiochemistry shown
for a-olefin insertion is assigned due to the presence if
TiꢀCH2 carbon resonances being observed in the 13C-
NMR spectra as well as the following results.
Although the methyl cations 17 and 18 undergo facile
decomposition (Scheme 3), they can be intercepted by
the addition of allylbenzene (Scheme 4). The resulting
cations also contain chelated h6-arene rings. The cation
in 28 obtained by insertion of propene into the Ti+
ꢀCH2Ph bond of 12 is identical (NMR) to that within
31, which is obtained by inserting allylbenzene into the
Ti+ꢀMe bond of generated 17. The only spectroscopic
difference between 28 and 31 relates to the anions
[PhCH2B(C6F5)3]− and [MeB(C6F5)3]− present in each.
The identical nature of the cations in 28 and 31 shows
1
polypropylene polymers by H- and 13C-NMR shows
the presence of vinylidene (H2CꢁC) end groups. Specifi-
cally the protons resonate at l 4.72 and 4.79 ppm while
the two carbons resonate at l 144.7 and 112.1 ppm.
This is consistent with a 1,2-insertion pathway for
polymer propagation with termination by b-hydrogen
abstraction. This, combined with the similar activities
(Table 7) implies that the aryloxide ligands that gener-
ate the highest molecular weights do so by slowing
down b-hydrogen abstraction.

M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
155
dards. Mass spectra, elemental analyses and molecular
structures were obtained in-house at Purdue University.
3.2. [Ti(OC6HPh2-2,6-Me2-3,5)2Cl2] (2)
A sample of 2,6-diphenyl-3,5-dimethylphenol (10.0 g,
36.5 mmol) was added to a solution containing [TiCl4]
(1.9 ml, 17.4 mmol) and benzene (40 ml). The resulting
red solution was refluxed for 2 h to drive off HCl gas
and then slowly allowed to cool, affording an orange–
red solid. The solvent was decanted away from this
solid, which was subsequently washed with hexane
three times and dried under vacuum affording an or-
ange solid (9.6 g, 90.0%). Anal. Calc. for
C40H34Cl2O2Ti: C, 71.98; H, 5.15; Cl, 10.67. Found: C,
71.98; H, 4.89; Cl, 10.89. 1H-NMR (C6D6, 30°C): l 6.74
(s, para-H); 7.1–7.3 (other aromatics); 2.01 (s, CH3).
3.3. [Ti(OC6H3Ph2-2,6)2(CH2Ph)2] (3)
A sample of [Ti(OC6H3Ph2-2,6)2Cl2] (1.00 g, 1.46
mmol) was dissolved in a benzene solution along with
1.3 equivalents of [Mg(CH2Ph)2(thf)2] (0.66 g, 1.89
mmol). The dark red solution was stirred for several
hours and then evacuated to dryness. The resulting red
solid was redissolved in benzene, filtered, and evacuated
to dryness, affording a red solid that was redissolved in
a minimal amount of benzene and layered with hexane,
affording red crystals (1.89 g, 89%). Anal. Calc. for
C50H40O2Ti: C, 83.32; H, 5.59; Found: C, 82.39; H,
Scheme 4.
In the case of 1-hexene, catalysts derived from 8–10
were found to produce only oligomers (Table 8). The
distribution of dimers to pentamers was determined by
GC analysis. It can be seen (Table 8) that a similar
trend is present to that obtained for the polymerization
of ethylene and propylene. There is a definite increase
in average oligomer molecular weight on moving down
the series. In the case of 11, a polymer of much higher
molecular weight is obtained. The oligomerization of
1-hexene by chelating phenoxides activated by MAO
has been reported.
1
5.44. H-NMR (C6D6, 30°C): l 6.70–7.30 (aromatics);
6.63 (d, ortho-CH2Ph); 1.91 (s, TiꢀCH2). Selected 13C-
NMR (C6D6, 30°C): l 159.8 (TiꢀOꢀC); 94.0 (TiꢀCH2).
3.4. [Ti(OC6H3Ph2-2,6)2(CH2C6H4-Me-4)2] (4)
A sample of [Ti(OC6H3Ph2-2,6)2Cl2] (3.00 g, 4.37
mmol) was dissolved in toluene and cooled to −78°C
using dry ice–acetone. To this vigorously stirred orange
solution was slowly added 4-methylbenzylmagnesium-
chloride (10.9 ml, 10.9 mmol) (prepared as a 1 M
solution in ether from the reaction of 4-methylben-
zylchloride with 3 equivalents of magnesium). The solu-
tion turned a dark red color and was allowed to slowly
warm to room temperature (r.t.) with continued stirring
for 1 day. The solution was then evacuated to dryness
and the resulting dark solid dissolved in benzene and
filtered to remove MgCl2. The filtrate was evacuated to
dryness affording a red solid that was recrystallized
from benzene–pentane, affording a red powder (2.72 g,
83%). Anal. Calc. for C52H44O2Ti: C, 83.41; H, 5.92.
3. Experimental
3.1. General
All operations were carried out under a dry nitrogen
atmosphere using standard Schlenk Techniques [26].
The hydrocarbon solvents were distilled from sodium
benzophenone and stored over sodium ribbons under
nitrogen until use. Reagents were purchased from
Aldrich Chemical Co., Inc. and used without further
purification. The 1H- and 13C-NMR spectra were
recorded on a Varian Associates Gemini-200 spectrom-
eter and referenced to protio impurities of commercial
benzene-d6 or deuterated chloroform as internal stan-
1
Found: C, 80.09; H, 5.87. H-NMR (C6D6, 30°C): l
3
6.80–7.30 (aromatics); 6.57 [d, J(1Hꢀ1H) 8.1 Hz, or-
tho-PhMe)]; 2.09 (s, CH2PhMe); 1.90 (s, TiCH2). Se-
lected 13C-NMR (C6D6, 30°C): l 160.2 (TiꢀOꢀC); 94.0
(TiCH2); 34.5 (p-CH3).

156
M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
Table 7
Polymer properties and catalyst activities for the polymerization of ethylene and propene by [(ArO)2TiMe2] activated by [B(C6F5)3] a
Precursor
8
Polyethylene
103 Mn
2.59
Polypropylene
OAr
103 Mw
Mw/Mn
Activity b
3
103 Mn
103 Mw
Mw/Mn
Activity b
6
5.64
2.2
1.53
1.97
1.3
9
2.61
8.23
4.91
11.80
23.50
1.9
1.4
1.9
4
3
2
1.72
3.45
2.17
4.65
1.3
1.4
2.0
5
3
2
10
11
12.50
14.50
28.98
a Conditions: 0.089 mmol of 8–11; 0.097 mmol of B(C6F5)3; 3 ml of toluene; 0°C; 1 atm; 15 min reaction time.
b kg mol−1 h−1 atm−1
.
3.5. [Ti(OC6HPh2-2,6-Me2-3,5)2(CH2Ph)2] (5)
benzene solution layered with pentane (0.61 g, 34%).
Anal. Calc. for C54H48O2Zr: C, 79.08; H, 5.90. Found:
C, 79.05; H, 6.09. H-NMR (C6D6, 30°C): l 6.8–7.3
(aromatics); 6.78 (s, para-CH); 6.44 (d, ortho-Ph); 2.13
(s, meta-CH3); 1.05 (s, ZrꢀCH2). Selected 13C-NMR
(C6D6, 30°C): l 158.0 (ZrꢀOꢀC); 68.7 (ZrꢀCH2); 21.3
(meta CH3).
1
An identical procedure to that used in the synthesis
of 3 was used for 5 starting with [Ti(OC6HPh2-2,6-Me2-
3,5)2Cl2] (1.00 g, 1.50 mmol). The synthesis afforded 5
as a red powder (1.04 g, 87%). Anal. Calc. for
C54H48O2Ti: C, 83.49; H, 6.23; Found: C, 83.15; H,
1
6.17. H-NMR (C6D6, 30°C): l 6.80–7.50 (aromatics);
6.64 (d, ortho-CH2Ph); 2.13 (s, meta CH3); 1.34 (s,
TiꢀCH2). Selected 13C-NMR (C6D6, 30°C): l 160.8
(TiꢀOꢀC); 92.7 [TiꢀCH2, 1J(13Cꢀ1H)=131 Hz]; 20.8
(meta CH3).
3.7. [Ti(OC6H3Ph2-2,6)2(CH3)2] (8)
A procedure identical to the one used for 9 was used
to prepare 8. The amounts of reagents used were as
follows: [TiCl4] (1 ml, 9.12 mmol); [MeLi] (26.1 ml, 36.5
mmol); 2,6-diphenylphenol (4.35 g, 17.1 mmol). 8 was
isolated as a yellow solid (3.84 g, 74%). Recrystalliza-
tion from benzene–hexane afforded X-ray quality crys-
tal. Anal. Calc. for C38H32O2Ti: C, 80.28; H, 5.67.
3.6. [Zr(OC6HPh2-2,6-Me2-3,5)2(CH2Ph)2] (6)
To a solution of [Zr(CH2Ph)4] (1.0 g, 2.20 mmol) in
toluene (20 ml) was added 2,6-diphenyl-3,5-
dimethylphenol (1.2 g, 4.40 mmol). The resulting mix-
ture was stirred for 12 h before the solvent was
removed in vacuo to yield the crude product. The crude
product was recrystallized as a brown solid from a
1
Found: C, 80.14; H, 5.69. H-NMR (C6D6, 30°C): l
6.70–7.50 (aromatics); 0.60 (TiꢀCH3). Selected 13C-
NMR (C6D6, 30°C): 66.1 (TiꢀCH3, 1J(13Cꢀ1H)=125
Hz).

M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
157
Table 8
Oligomerization of 1ꢀhexene by [(ArO)2TiMe2] activated by [B(C6F5)3] a
Precursor
1ꢀHexene oligomers
Oar
% Dimer (C12
)
% Trimer (C18
)
% Tetramer (C24
13
)
% Pentamer (C30
–
)
8
62
24
9
42
32
18
7
10
34
34
21
11
b
11
–
–
–
–
a Conditions: 0.089 mmol of 54–57; 0.097 mmol of B(C6F5)3; 3 ml of toluene; 25°C; 2 ml (17.8 mmol) 1ꢀhexene; 24 h reaction time.
b Catalyst precursor 57 gave too high Mw (1H-NMR) to be measured by GC analysis.
(TiꢀCH3). Selected 13C-NMR (C6D6, 30°C): l 160.7
(TiꢀOꢀC); 64.7 (TiꢀCH3); 21.2 (meta CH3).
3.8. [Ti(OC6HPh2-2,6-Me2-3,5)2(CH3)2] (9)
A 1 l three-neck flask fitted with a nitrogen adapter
was charged with distilled anhydrous diethylether (400
ml), [TiCl4] (2 ml, 18.2 mmol) and cooled to −78°C
using dry ice–acetone. Once the desired temperature
was achieved, 4 equivalents of [MeLi] (1.4 M in Et2O,
52.11 ml, 73 mmol) was slowly added to the stirred
solution. The solution turned red upon [MeLi] addition.
After 15 min of stirring the dark solution at −78°C, 2
equivalents of 2,6-diphenyl-3,5-dimethylphenol (9.86 g,
36.0 mmol) were added with continued stirring. The
dark solution was slowly allowed to warm to r.t. The
diethyl ether was removed in vacuo and the resulting
dark residue was dissolved in benzene, filtered to re-
move LiCl, and evacuated to dryness. The resulting
dark solid was recrystallized from a benzene–hexane
mixture (3:7) affording 9 as a dark green powder (5.61
3.9. [Ti(OC6HPh2-2,6-But2-3,5)2(CH3)2] (10)
A procedure identical to the one used for 9 was used
to prepare 10. The amounts of reagents used was as
follows: [TiCl4] (1 ml, 9.12 mmol); [MeLi] (26.1 ml, 36.5
mmol); 3,5-di-tert-butyl-2,6-diphenylphenol (4.35 g,
17.1 mmol). [Ti(OC6HPh2-2,6-But2-3,5)2(CH3)2] (10) was
isolated as a yellow solid (3.84 g, 27%)). 1H-NMR
(C6D6, 30°C): l 7.69 (s, para-OC6H); 6.90–7.40 (aro-
matics); 1.31 [s, C(CH3)3]; 0.06 (s, TiꢀCH3). Selected
13C-NMR (C6D6, 30°C): l 162.4 (TiꢀOꢀC); 64.9
1
(TiꢀCH3, J(13Cꢀ1H)=125.2 Hz); 37.5 [C(CH3)3]; 33.1
[C(CH3)3].
3.10. [Ti(OC6HPh-2-But2-4,6)2(CH3)2] (11)
1
g, 50%). H-NMR (C6D6, 30°C): l 6.90–7.40 (aromat-
ics); 6.83 (s, para-OC6H); 2.12 (s, meta CH3); 0.24
A procedure identical to the one used for 9 was used
to prepare 11. The amounts of reagents used was as

158
M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
follows: [TiCl4] (1 ml, 9.12 mmol); [MeLi] (26.1 ml, 36.5
mmol); 4,6-di-tert-butyl-2-phenylphenol (4.35 g, 17.1
mmol). [Ti(OC6HPh-2-But2-4,6)2(CH3)2] (11) was iso-
h6-C6H5); 4.75 (br t, meta Ti-h6-C6H5); 3.49 (br, para
Ti-h6-C6H5); 2.93 (br, BꢀCH2); 1.89 (s, TiꢀCH2); 1.86
(s, meta CH3). For subsequent reactions 14 was gener-
ated in situ and found to undergo similar chemistry as
solid 12, thereby further confirming its synthesis here.
1
lated as a green solid (3.84 g, 47%). H-NMR (C6D6,
30°C): l 7.59 (d), 7.33 (d, meta-H); 6.80–7.30 (aromat-
ics); 1.71 [s, ortho-C(CH3)3]; 1.31 [s, para-C(CH3)3];
1.10 (s,TiꢀCH3). Selected 13C-NMR (C6D6, 30°C): l
160.3 (TiꢀOꢀC); 67.6 (TiꢀCH3, 1J(13Cꢀ1H)=124.0 Hz);
35.9 [ortho-C(CH3)3]; 34.7 [para-C(CH3)3]; 31.8 [ortho-
C(CH3)3]; 30.9 [para-C(CH3)3].
3.14. [Zr(OC6HPh2-2,6-Me2-3,5)2-
(CH2Ph)][p6-C6H5CH2B(C6F5)3] (15)
A sample of [Zr(OC6HPh2-2,6-Me2-3,5)2(CH2Ph)2]
(6) (200 mg, 0.24 mmol) was placed in a solvent sealed
flask along with one equivalent of [B(C6F5)3] (125 mg,
0.24 mmol) and benzene (1 ml). The flask was left
undisturbed for 12 h and then the solution was evacu-
ated to dryness. The resulting material was re-dissolved
in a minimal amount of benzene and layered with
hexane, affording yellow crystals (252 mg, 79%). Anal.
Calc. for C60H56BF15O2Zr: C, 60.25; H, 4.72. Found: C,
55.47; H, 4.60. 1H-NMR (C6D6, 30°C): l 6.91 [t,
3J(1Hꢀ1H)=7.7 Hz, meta-Ph)]; 6.72 [t, 3J(1Hꢀ1H)=7.4
3.11. [Ti(OC6H3Ph2-2,6)2(CH2Ph)]-
[p6-C6H5CH2B(C6F5)3] (12)
A sample of [Ti(OC6H3Ph2-2,6)2(CH2Ph)2] 3. (1.00 g,
1.39 mmol) was placed in a solvent sealed flask along
with 1.3 equivalents of [B(C6F5)3] (0.92 g, 1.80 mmol)
and benzene (5 ml). The reaction solution immediately
turned red in color. The flask was left undisturbed for
12 h and then the solution was evacuated to dryness.
The resulting red solid was re-dissolved in minimal
benzene and layered with hexane, affording dark red
crystals (1.07 g, 63%). Anal Calc. for C68H40BF15O2Ti:
3
Hz, para-Ph)]; 6.34 [d, J(1Hꢀ1H)=7.2 Hz, ortho-Ph)];
3
6.10 [d, J(1Hꢀ1H)=7.3 Hz, ortho Zr-h6-C6H5]; 5.00 [t,
3J(1Hꢀ1H)=7.4 Hz, meta Zr-h6-C6H5]; 4.71 [t,
3J(1Hꢀ1H)=7.3 Hz, para Zr-h6-C6H5]; 2.97 [(br),
BCH2]; 1.88 (s, meta-CH3); 0.83 (s, ZrꢀCH2). Selected
13C-NMR (C6D6, 30°C): l 163.0 (ZrꢀOꢀC); 70.6
(ZrꢀCH2); 20.7 (meta CH3).
1
C, 66.26; H, 3.27. Found: C, 66.32; H, 3.28. H-NMR
(C6D6, 30°C):
l 6.75–7.30 (aromatics); 6.65 [d,
3J(1Hꢀ1H)=7.0 Hz, ortho TiꢀCH2Ph]; 6.07 [d,
3J(1Hꢀ1H)=6.7 Hz, ortho Ti-h6-C6H5]; 4.78 [t,
3J(1Hꢀ1H)=7.5 Hz, meta Tiꢀh6ꢀC6H5]; 4.43 [t,
3J(1Hꢀ1H)=7.3 Hz, para Ti-h6-C6H5]; 2.77 (br,
BꢀCH2); 2.12 (s, TiꢀCH2). Selected 13C-NMR (C6D6,
30°C): l 161.9 (TiꢀOꢀC); 101.2 (TiCH2).
3.15. [Zr(OC6H3ButꢀCMe2CH2)(OC6H3But2ꢀ2,6)]-
[p6-C6H5CH2B(C6F5)3] (16)
A sample of [Zr(OC6H3But2-2,6)2(CH2Ph)2] (7) (180
mg, 0.29 mmol) and [B(C6F5)3] (165 mg, 0.32 mmol)
were dissolved in benzene (2 ml) in a solvent sealed
flask forming a yellow solution. The solution was left
undisturbed for 16 h and then evacuated to dryness,
affording a yellow glassy solid. This solid was re-dis-
solved in fresh benzene and layered with pentane, af-
fording 16 as yellow crystals (260 mg, 75%). Anal. Calc.
for C60H56BF15O2Zr: C, 60.25; H, 4.72. Found: C,
58.85; H, 4.50. 1H-NMR (C6D6, 30°C): l 7.05–7.20
3.12. [Ti(OC6H3Ph2-2,6)2(CH2C6H4-
Me-4)][p6-(C6H4Me-4)CH2B(C6F5)3] (13)
Procedure used was similar to that used in the syn-
thesis of 12. Anal Calc. for C70H44BF15O2Ti: C, 66.86;
1
H, 3.47. Found: C, 63.73; H, 3.46. H-NMR (C6D6,
30°C): l 6.80–7.40 (aromatics); 6.65 (d), 6.15 [d,
3J(1Hꢀ1H)=7.7, 8.0 Hz, ortho-TiꢀCH2C6H4Me-4]; 6.08
3
(d), 4.92 [d, J(1Hꢀ1H)=7.6, 7.4 Hz, ortho and meta
Ti-h6-C6H4]; 2.95 (br, BꢀCH2); 2.02 (s, TiꢀCH2-
C6H4Me)); 1.35 (s, TiCH2); 0.57 (s, Ti-h6-C6H4Me).
Selected 13C-NMR (C6D6, 30°C): l 161.7 (TiꢀOꢀC);
101.6 (TiCH2); 20.7(TiꢀCH2C6H4Me); 18.7 (Ti-h6-
C6H4Me).
(aromatics); 6.98 (d), 6.87 [d, J(1Hꢀ1H)=7.7 and 7.9
3
3
Hz, ortho Zr-h6-C6H5]; 6.81 (t), 6.75 [t, J(1Hꢀ1H)=7.8
and 7.9 Hz, meta-TiꢀOꢀPh)]; 6.16 (t), 5.89 (t), 5.66 [t,
3J(1Hꢀ1H)=7.6, 7.6, and 7.3 Hz, meta and para Zr-h6-
C6H5]; 3.39 (br), 3.19 (br, BꢀCH2); 1.98 (AB, 17.2 and
t
21.5 Hz); 1.23 (s), 1.18 (s, Bu). Selected 13C-NMR
3.13. [Ti(OC6HPh2-2,6-Me2-3,5)2-
(CH2Ph)][p6-C6H5CH2B(C6F5)3] (14)
(C6D6, 30°C): l 163.9, 161.2 (ZrꢀOꢀC); 82.0 (ZrꢀCH2);
35.4, 35.3 [Cꢀ(CH3)3]; 32.3, 31.2 [Cꢀ(CH3)3].
An identical procedure to that used for the synthesis
of 12 was attempted for the synthesis of 14 using 5 as
the Ti starting material; however, only reddish oils
could be isolated, which were found to have broad
1H-NMR resonances with similar chemical shifts as
that of 12. H-NMR (C6D6, 30°C): l 6.60–7.40 (aro-
matics); 6.39 (d, ortho TiꢀCH2Ph); 5.85 (br, ortho Ti-
3.16. [Ti(OC6H3Ph2-2,6)2(CH3)][CH3B(C6F5)3] (17),
[Ti(OC6H3Ph2-2,6)3(CH3)] (19), [Ti(OC6H3Ph2-
2,6)2(CH3)(C6F5)] (20) and [CH3B(C6F5)2] (21)
Equimolar amounts of 8 and B(C6F5)3 were placed in
an NMR tube along with C6D6. Only small amounts of
the initial abstraction product 17 were observed in the
1

M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
159
1H-NMR spectrum, which was dominated by the de-
composition products 20 and 21 along with a small
amount of 19. [Ti(OC6H3Ph2-2,6)2(CH3)][CH3B(C6F5)3]
C6D6. After several minutes excess 1-phenylpropyne
1
was added. H-NMR (C6D6, 30°C): l 6.60–7.60 (aro-
3
matics); 6.53 [t, J(1Hꢀ1H)=8.0 Hz, meta Ti-h6-C6H5];
1
3
(17): H-NMR (C6D6, 30°C): l 6.80–7.30 (aromatics);
5.99 [d, J(1Hꢀ1H)=6.0 Hz, ortho Ti-h6-C6H5]; 4.51 [t,
1.22 (br, BꢀCH3); 0.39 (br, TiꢀCH3). [Ti(OC6H3Ph2-
3J(1Hꢀ1H)=8.0 Hz, para Ti-h6-C6H5]; 3.32 (br s,
BꢀCH2); 3.21 (s, CH2); 1.88 (s, meta CH3); 1.03 (s,
CH3). Attempts to isolate 25 as a solid and not as an oil
have thus far been unsuccessful.
1
2,6)3(CH3)] (19): H-NMR (C6D6, 30°C): l 6.75–7.30
(aromatics); −0.36 [s, (ArO)3TiCH3]. [Ti(OC6H3Ph2-
1
2,6)2(CH3)(C6F5)] (20): H-NMR (C6D6, 30°C): l 6.75–
5
7.30 (aromatics); 0.75 (t, J(19Fꢀ1H)=1.5 Hz, TiꢀCH3).
1
[CH3B(C6F5)2] (21): H-NMR (C6D6, 30°C): l 1.27 [p,
3.20. Synthesis of [Ti(OC6H3Ph2-2,6)2{CH2CH-
(CH2Ph)CH2(p6-C6H5)}][PhCH2B(C6F5)3] (26)
5J(19Fꢀ1H)=1.7 Hz, CH3B(C6F5)2].
3.17. [Ti(OC6HPh2-2,6-Me2-3,5)2(CH3)][CH3B(C6F5)3]
(18), [Ti(OC6HPh2-2,6-Me2-3,5)3(CH3)] (22) and
[Ti(OC6HPh2-2,6-Me2-3,5)2(CH3)(C6F5)] (23)
A
sample
of
[Ti(OC6H3Ph2-2,6)2(CH2Ph)]-
[B(C6F5)3(CH2{h6-C6H5})] (12) (20 mg, 0.016 mmol)
was placed in an NMR tube along with deuterated
benzene and 1.5 equivalents of allylbenzene (3.22 ml,
0.024 mmol), resulting in a red solution. 1H-NMR
(C6D6, 30°C): l 6.50–7.50 (aromatics); 6.16 (d), 6.08 [d,
3J(1Hꢀ1H)=7.5 and 7.6 Hz, ortho Ti-h6-C6H5]; 5.43 (t),
A sample of 9 was placed in an NMR tube along
with [B(C6F5)3] and C6D6 forming a red solution of 18:
1H-NMR (C6D6, 30°C): l 6.80–7.30 (aromatics); 6.77
(s, para-H); 1.92 (s, meta-CH3); 1.27 (br, BꢀCH3); 0.01
(br, TiꢀCH3). Within an hour, the decomposition prod-
ucts 23 and 21 had formed along with a minor amount
of [Ti(OC6HPh2-2,6-Me2-3,5)3(CH3)] (22): 1H-NMR-
(C6D6, 30°C): l 6.70–7.50 (aromatics); 1.90 (s, meta
CH3); −0.97 (s, TiꢀCH3). [Ti(OC6HPh2-2,6-Me2-3,5)2-
5.27 (t), 5.12 [t, J(1Hꢀ1H)=6.9, 7.8, and 7.4 Hz, meta
3
and para Ti-h6-C6H5]; 3.28 (s, BꢀCH2Ph); 1.40–2.60
(aliphatics); 0.26 (dd, TiꢀCH2). Selected 13C-NMR
(C6D6, 30°C): l 161.9, 161.6 (TiꢀOꢀC); 58.3 (TiꢀCH2);
45.0 (TiꢀCH2CH); 40.5, 39.7 (CH2Ph, CH2{h6-C6H5});
32.7 (br, BꢀCH2). Attempts to isolate 26 as a solid and
not as an oil have thus far been unsuccessful.
1
(CH3)(C6F5)] (23): H-NMR (C6D6,30°C): l 6.70–7.50
5
(aromatics); 2.04 (s, meta CH3); 0.52 (t, J(19Fꢀ1H)=
1.5 Hz, TiꢀCH3).
3.21. [Ti(OC6HPh2-2,6-Me2-3,5)2{CH2CH-
(CH2Ph)CH2(p6-C6H5)}][B(C6F5)3(CH2Ph)] (27)
3.18. [Ti(OC6H3Ph2-2,6)2{C(CH3)C(Ph)CH2-
(p6-C6H5)}][PhCH2B(C6F5)3] (24)
A sample of [Ti(OC6HPh2-2,6-Me2-3,5)2(CH2Ph)2] (5)
(200 mg, 0.026 mmol) and 1.3 equivalents of [B(C6F5)3]
(171 mg, 0.33 mmol) were dissolved in benzene and
after 10 min 1.1 equivalents of allylbenzene (37.5 ml,
0.28 mmol) were added to this stirred red solution. The
solution was stirred for an additional 30 min and then
evacuated to dryness, leaving a yellow–orange solid.
1H-NMR (C6D6, 30°C): l 6.65–7.40 (aromatics); 6.58
(d), 6.37 [d, 3J(1Hꢀ1H)=7.6 and 7.0 Hz, ortho
A
sample of [Ti(OC6H3Ph2-2,6)2(CH2Ph)][h6-
C6H5CH2B(C6F5)3] (12) (130 mg, 0.105 mmol) was dis-
solved in benzene (2 ml) in a round-bottomed flask. To
this solution was added 1.0 equivalents of 1-phenyl-
propyne (13.2 ml, 0.105 mmol). The color of this solu-
tion slowly turned from red to orange over the course
of an hour. This orange solution was evacuated to
dryness, affording a red glassy solid (90 mg, 64%).
Anal. Calc. for C77H48BF15O2Ti: C, 68.56; H, 3.59.
3
Ti-h6-C6H5]; 6.14 (t), 5.63 (t), 5.03 [t, J(1Hꢀ1H)=6.8,
7.7, and 6.9 Hz, meta and para Ti-h6-C6H5]; 3.35 (s,
BꢀCH2Ph); 1.94 (s), 1.82 (s, meta CH3); 1.40–2.50
(aliphatics); 0.00 (dd, TiꢀCH2). Selected 13C-NMR
(C6D6, 30°C): l 162.5, 161.6 (TiꢀOꢀC); 58.4 (TiꢀCH2);
44.9 (TiꢀCH2CH); 40.2 (CH2Ph, CH2{h6-C6H5}); 20.8,
20.6 (meta CH3).
1
Found: C, 65.59; H, 3.87. H-NMR (C6D6, 30°C): l
6.60–7.40 (aromatics); 6.29 [t, 3J(1Hꢀ1H)=7.6 Hz,
3
meta Ti-h6-C6H5]; 5.82 [d, J(1Hꢀ1H)=7.4 Hz, ortho
3
Ti-h6-C6H5]; 4.29 [t, J(1Hꢀ1H)=7.4 Hz, para Ti-h6-
C6H5]; 3.22 (s, CH2); 3.17 (s, BꢀCH2); 1.87 (s, CH3).
Selected 13C-NMR (C6D6, 30°C): l 231.6 (TiꢀC{CH3});
163.8 (TiꢀOꢀC); 45.7 (CH2); 34.3 (TiꢀC{CH3}). At-
tempts to isolate 24 as a crystalline solid have thus far
been unsuccessful.
3.22. [Ti(OC6H3Ph2-2,6)2{CH2CH(CH3)-
CH2(p6-C6H5)}][PhCH2B(C6F5)3] (28)
A sample of 12 was placed in an NMR tube along
with C6D6, causing the formation of a red solution.
Propene (1 atm) was added to the solution via a glass
manifold, causing the solution to become orange in
color after a few minutes. Excess propene was then
removed by evacuation of the solution, leaving an
3.19. [Ti(OC6HPh2-2,6-Me2-3,5)2{C(CH3)C(Ph)CH2-
(p6-C6H5)}][PhCH2B(C6F5)3] (25)
A sample of [Ti(OC6HPh2-2,6-Me2-3,5)2(CH2Ph)2] (5)
was placed in an NMR tube along with [B(C6F5)3] and

160
M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
orange oil. This oil was re-dissolved in C6D6. The
7.3, and 7.0 Hz, meta and para Ti-h6-C6H5]; 3.37 (s,
BꢀCH2Ph); 1.94 (s), 1.87 (s, meta CH3); 0.00–2.50
(aliphatics). Evacuation of this solution to dryness af-
forded a yellow–orange glassy solid, which only pro-
duced an oil from recrystallization attempts.
1
1H-NMR spectrum matches exactly with the H-NMR
spectrum of 31 except for the signal for the boron-con-
taining anion which was l 3.28 for BꢀCH2 for 28.
3.23. Synthesis of [Ti(OC6H3Ph2-2,6)2{CH2CH-
((CH2)3CH3)CH2(p6-C6H5)}][PhCH2B(C6F5)3] (29)
3.25. [Ti(OC6H3Ph2-2,6)2{CH2CH-
(CH3)CH2(p6-C6H5)}][CH3B(C6F5)3] (31)
A sample of [Ti(OC6H3Ph2-2,6)2(CH2Ph)][B(C6F5)3-
(CH2{h6-C6H5})] (12) (40 mg, 0.03 mmol) was placed in
an NMR tube along with deuterated benzene and 2
equivalents of 1-hexene (8.1 ml, 0.06 mmol), resulting in
A sample of 8 (50 mg, 0.09 mmol) was placed in an
NMR tube along with 2 equivalents of allylbenzene (24
ml, 0.18 mmol) and C6D6 (0.5 ml). To this solution was
added [B(C6F5)3] (60 mg, 0.11 mmol) dissolved in C6D6
(0.5 ml) resulting in a dark red solution. 1H-NMR
(C6D6, 30°C): l 6.80–7.50 (aromatics); 6.49 (d), 6.33 [d,
3J(1H-1H)=8.0 and 7.8 Hz, ortho Ti-h6-C6H5]; 5.79 (t),
1
an orange solution. H-NMR (C6D6, 30°C): l 6.50–
3
7.50 (aromatics); 6.37 (d), 6.30 [d, J(1Hꢀ1H)=7.9 and
7.8 Hz, ortho Ti-h6-C6H5]; 5.63 (t), 5.16 (t), 4.86 [t,
3J(1Hꢀ1H)=7.6, 7.4, and 7.6 Hz, meta and para Ti-h6-
C6H5]; 3.22 (s, BꢀCH2Ph); 0.20–1.50 (aliphatics). Se-
3
5.24 (t), 4.79 [t, J(1Hꢀ1H)=7.7, 7.3, and 7.5 Hz, meta
lected 13C-NMR (C6D6, 30°C):
l
161.9, 161.4
and para Ti-h6-C6H5]; 1.35 (m, CH2Ph); 1.18 (m,
CHCH3); 0.98 (br, BꢀCH3); 0.21 (m, TiꢀCH2); 0.21 [d,
3J(1Hꢀ1H)=5.9 Hz, CHCH3). Selected 13C-NMR
(C6D6, 30°C): l 162.1, 161.3 (TiꢀOꢀC); 70.4 (TiꢀCH2);
53.2 (TiꢀCH2CH); 33.2 (CH2ꢀh6-C6H5); 24.5 (BꢀCH3);
13.6 (CHCH3).
(TiꢀOꢀC); 58.7 (TiꢀCH); 44.1 (CH2CH2{h6-C6H5});
39.7 (TiꢀCHCH2); 36.8 (CH2CH2{h6-C6H5}); 29.8
(TiꢀCHCH2CH2); 23.3 (TiꢀCHCH2CH2CH2); 14.3
(TiꢀCHCH2 CH2CH2CH3).
3.24. [Ti(OC6HPh2-2,6-Me2-3,5)2{CH2CH-
((CH2)3CH3)CH2(p6-Ph)}][PhCH2B(C6F5)3] (30)
3.26. [Ti(OC6HPh2-2,6-Me2-3,5)2{CH2CH(CH3)-
CH2(p6-C6H5)}][CH3B(C6F5)3] (32)
A sample of [Ti(OC6HPh2-2,6-Me2-3,5)2(CH2Ph)2] (5)
(60 mg, 0.08 mmol) was placed in an NMR tube along
with [B(C6F5)3] (50 mg, 0.10 mmol), deuterated ben-
zene, and 2 equivalents of 1-hexene (19.3 ml, 0.15 mmol)
A sample of 9 (50 mg, 0.08 mmol) was placed in an
NMR tube along with 2 equivalents of allylbenzene (21
ml, 0.16 mmol) and C6D6 (0.5 ml). To this solution was
added [B(C6F5)3] (50 mg, 0.10 mmol) dissolved in C6D6
(0.5 ml), resulting in a dark red solution. 1H-NMR
(C6D6, 30°C): l 6.75–7.40 (aromatics); 6.66 (d), 6.52 [d,
3J(1Hꢀ1H)=7.7 and 7.4 Hz, ortho Ti-h6-C6H5]; 5.71 (t),
1
resulting in a red solution. H-NMR (C6D6, 30°C): l
6.95–7.60 (aromatics); 6.77(s), 6.73 (s, para OC6H);
6.87 (d), 6.58 [d, 3J(1Hꢀ1H)=7.3 and 7.3 Hz, ortho
3
Ti-h6-C6H5]; 5.81 (t), 5.68 (t), 5.08 [t, J(1Hꢀ1H)=7.3,
Table 9
Crystal data and data collection parameters
3
8
12
15
16
19
Formula
Formula weight
TiO2C50H40
720.78
TiO2C38H32
568.58
TiBF15O2C60H40 ZrBF15O2C84H55
1232.76 1483.38
ZrBF15O2C56H51
1143.04
TiO3C55H42
798.85
(
(
(
Space group
P2l/c (No. 14)
10.4608(9)
18.8946(17)
19.9761(15)
90
97.118(5)
90
3917.9(10)
4
P1 (No. 2)
P1 (No. 2)
P1 (No. 2)
P2l/c (No. 14)
15.5437(2)
19.0909(3)
36.6115(6)
90
101.1696(8)
90
10658.4(5)
8
P2l/c (No. 14)
10.3321(3)
20.6823(8)
20.2955(8)
90
103.376(2)
90
4219.3(5)
4
,
a (A)
9.8108(3)
10.7880(5)
14.9475(6)
93.1218(18)
106.605(2)
93.597(2)
1508.7(2)
2
12.917(2)
13.045(2)
19.600(2)
84.757(12)
77.580(12)
61.871(13)
2844.0(8)
2
13.3579(17)
14.722(4)
20.596(7)
71.45(2)
77.548(19)
72.175(17)
3624.1(17)
2
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
Z
zcalc (g cm−3
)
1.222
1.252
1.444
1.359
1.425
1.257
Temperature (K)
203.
203.
295.
203.
203.
203.
Radiation (wave-
Mo–Ka (0.71073 Mo–Ka (0.71073 Mo–Ka (0.71073 Mo–Ka (0.71073
Mo–Ka (0.71073
Mo–Ka (0.71073
,
,
,
,
,
,
length)
A)
A)
A)
A)
A)
A)
R
0.080
0.168
0.050
0.113
0.069
0.178
0.055
0.160
0.055
0.135
0.093
0.226
RW

M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
161
3
5.52 (t), 5.30 [t, J(1Hꢀ1H)=8.0, 6.7, and 7.3 Hz, meta
and para Ti-h6-C6H5]; 1.93 (s), 1.89 (s, meta CH3); 0.98
(br, BꢀCH3); 0.00–2.10 (other aliphatics). Selected 13C-
NMR (C6D6, 30°C): l 162.1, 161.7 (TiꢀOꢀC); 70.5
(TiꢀCH2); 53.1 (TiꢀCH2CH); 33.2 (CH2-h6-C6H5); 24.5
(BꢀCH3); 24.0 (CHCH3); 20.8, 20.5 (meta CH3).
Acknowledgements
The authors wish to thank the National Science
Foundation (Grant CHE-9700269) for financial sup-
port of this research.
References
3.27. Oligomerization of 1-hexene by
[(ArO)2TiMe][MeB(C6F5)3]
[1] (a) G.J.P. Britovsek, V.C. Gibson, D.F. Wass, Angew. Chem.
Int. Ed. Engl. 38 (1999) 428 and references therein. (b) V.C.
Gibson, Angew. Chem. Int. Ed. Engl. 33 (1994) 1565.
[2] (a) Polyhedron Symposium in Print c19 (M.H. Chisholm, Ed.)
Polyhedron, 17 (1998) 623–1034. (b) M.F. Lappert, P.P. Power,
A.R. Sanger, R.C. Srivastava, Metal and Metalloid Amides,
John Wiley, New York, 1980.
[3] (a) Polyhedron Symposium in Print c16 (M.H. Chisholm, I.P.
Rothwell, Eds.) Polyhedron, 14 (1995) 3177–3366. (b) D.C.
Bradley, R.C. Mehrotra, D.P. Gaur, Metal Alkoxides, Academic
Press, New York, 1978. (c) M.H. Chisholm, Chemtracts 4 (1992)
273.
In the drybox a sample of [(ArO)2TiMe2] (8–11)
(0.089 mmol) was dissolved toluene in (0.5 ml) along
with 200 equivalents of 1-hexene (2 ml). This solution
was stirred as [B(C6F5)3] (0.097 mmol) dissolved in
toluene (1 ml) was quickly added. The mixture was
stirred for 24 h and analyzed by gas chromatography
using the parent phenol as an internal reference to
determine product distribution. The heavier polyhexene
samples were isolated as described for polyethylene and
polypropylene in heading 6.3.22 and subsequently ana-
[4] P.T. Wolczanski, Polyhedron 14 (1995) 3335.
[5] (a) I.P. Rothwell, Chem. Commun. (Cambridge) (Feature Arti-
cle) (1997) 1331. (b) V.M. Visciglio, J.R. Clark, M.T. Nguyen,
D.R. Mulford, P.E. Fanwick, I.P. Rothwell, J. Am. Chem. Soc.
119 (1997) 3490. (c) J.S. Vilardo, M.A. Lockwood, L.G. Hanson,
J.R. Clark, B.C. Parkin, P.E. Fanwick I.P. Rothwell, J. Chem.
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Waratuke, E.S. Johnson, P.E. Fanwick, I.P. Rothwell, J. Am.
Chem. Soc. 119 (1997) 8630. (e) E.S. Johnson, G.J. Balaich, I.P.
Rothwell, J. Am. Chem. Soc. 119 (1997) 7685.
[6] (a) M. Bochmann, J. Chem. Soc. Dalton Trans. (1996) 255. (b)
H.-H. Brintzinger, D. Fischer, R. Mu¨lhaupt, B. Rieger, R.M.
Waymouth, Angew. Chem. Int. Ed. Engl. 34 (1995) 1143. (c)
P.C. Mo¨hring, N.J. Coville, J. Organomet. Chem. 479 (1994) 1.
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Int. Ed. Engl. 24 (1985) 507.
1
lyzed by H- and 13C-NMR in order to determine end
groups. For lighter polyhexene samples the original
solutions were dried on a rotary evaporator and ana-
lyzed by NMR.
3.28. Polymerization of ethene and propene by
[(ArO)2TiMe][MeB(C6F5)3]
In the drybox a solvent sealed flask containing a stir
bar was charged with a sample of [(ArO)2TiMe2] (8–
11) (0.089 mmol), toluene (3 ml) and [B(C6F5)3] (0.097
mmol). The flask was quickly brought out of the dry-
box and chilled to 0°C using an ice–acetone bath. One
atmosphere of monomer was placed upon the contents
of the flask for 15 min while the mixture was vigor-
ously stirred. After this time methanol was added to
quench the reaction and precipitate any polymer
formed. The polymers that formed were washed with
methanol and dried under vacuum, affording either
viscous colorless oils (polypropylene) or white solids
(polyethylene).
[7] (a) J.D. Scollard, D.H. McConville, J. Am. Chem. Soc. 118
(1996) 10008. (b) R. Baumann, W.M. Davis, R.R. Schrock, J.
Am. Chem. Soc. 119 (1997) 3830.
[8] For the polymerization of olefins by bidentate aryloxides see (a)
T. Miyatake, K. Mizunuma, M. Kakugo, Marcomol. Chem.
Macromol. Symp. 66 (1993) 203. (b) A. van der Linden, C.J.
Schaverien, N. Meijboom, C. Grant, A.G. Orpen, J. Am. Chem.
Soc. 117 (1995) 3008. (c) S. Fokken, T.P. Spaniol, H.-C. Kang,
W. Massa, J. Okuda, Organometallics 15 (1996) 5069. (d) For
cationic zirconium alkyls supported by chelating phenoxides see
P.G. Cozzi, E. Gallo, C. Floriani, A. Chiesi-Villa, C. Rizzoli,
Organometallics 14 (1995) 4994.
[9] M.G. Thorn, Z.C. Etheridge, P.E. Fanwick, I.P. Rothwell,
Organometallics 17 (1998) 3636.
3.29. Crystallographic studies
[10] Mixed cyclopentadienyl aryloxide compounds have also been
studied, see (a) K. Nomura, N. Naga, M. Miki, K. Yanagi,
Macromolecules 31 (1998) 7588. (b) S.W. Ewart, M.J. Sarsfield,
D. Jeremic, T.L. Tremblay, E.F. Williams, M.C. Baird,
Organometallics 17 (1998) 1502. (c) M.J. Sarsfield, S.W. Ewart,
T.L. Tremblay, A.W. Roszak, M.C. Baird, J. Chem. Soc. Dalton
Trans. (1997) 3097. (d) T.L. Tremblay, S.W. Ewart, M.J.
Sarsfield, M.C. Baird, Chem. Commun. (Cambridge) (1997) 831.
(e) For linked Cp-phenoxide derivatives see Y.-X. Chen, P.-F.
Fu, C.L. Stern, T.J. Marks, Organometallics 16 (1997) 5958. (f)
J.S. Vilardo, M.G. Thorn, P.E. Fanwick, I.P. Rothwell, Chem.
Commun. (Cambridge) (1998) 2425. (g) M.G. Thorn, J.S. Vi-
lardo, P.E. Fanwick, I.P. Rothwell, Chem. Commun. (Cam-
bridge) (1998) 2427.
Crystal data and data collection parameters are con-
tained in Table 9. Crystallographic data for the struc-
tural analyses have been deposited with the Cambridge
Crystallographic Data Centre, CCDC nos. 127153 (3),
127154 (8), 127155 (12), 127156 (15), 12757 (16) and
12758 (19). Copies of this information may be obtained
free of charge from The Director, CCDC, 12 Union
Road, Cambridge, CB2 1EZ (fax +44(1223)336-033
or
e-mail:
deposit@ccdc.cam.ac.uk
or
http://
www.ccdc.cam.ac.uk).

162
M.G. Thorn et al. / Journal of Organometallic Chemistry 591 (1999) 148–162
[11] J.R. Dilworth, J. Hanich, M. Krestel, J. Organomet. Chem. 315
(1986) 9.
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