Syntheses of titanium μ-arylimido and μ-pyridylimido complexes bearing (un)substituted cyclopentadienyl ligand

Article abstract of DOI:10.1016/S0022-328X(99)00732-9

The reactions of (η⁵-C₅H₄CH₂CH ₂Br)TiBr₃, (η⁵-C₅H₄CH₂CH ₂OCH₃)TiCl₃, (η⁵-C₅H₄-C

Full text of DOI:10.1016/S0022-328X(99)00732-9

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 598 (2000) 339–347
Syntheses of titanium m-arylimido and m-pyridylimido complexes
bearing (un)substituted cyclopentadienyl ligand
Zheng Li 1, Jiling Huang, Tianer Yao, Yanlong Qian *, Meiyu Leng
Laboratory of Organometallic Chemistry, East China Uni6ersity of Science and Technology, Meilong Road 130, Shanghai 200237, PR China
Received 27 July 1999; received in revised form 18 November 1999; accepted 22 November 1999
Abstract
The reactions of (h5-C5H4CH2CH2Br)TiBr3, (h5-C5H4CH2CH2OCH3)TiCl3, (h5-C5H4-CH2-cyclo-C4H7O)TiCl3 and (h5-
C5H5)TiCl3 with an equivalent of 2-MeOC6H4NHLi in the presence of Et3N afford m-arylimido complexes, [(h5-
C5H4CH2CH2Br)Ti(Br)(m-NC6H4OCH3-2)]2 (1), [(h5-C5H4CH2CH2OCH3)Ti(Cl)( m-NC6H4OCH3-2)]2 (2), [(h5-C5H4-CH2-
cyclo-C4H7O)Ti(Cl)(m-NC6H4ꢀOCH3-2)]2 (3), [(h5-C5H5)Ti(Cl)(m-NC6H4OCH3-2)]2 (4), which include intramolecular titanium and
oxygen coordination. Complex 4 can also be obtained by reaction of the (h5-C5H5)2TiCl2 with 2-MeOC6H4NHLi. Meanwhile
refluxing of (h5-C5H5)2TiCl2 with an equivalent of 2-Me2NC6H4NMg·THF in toluene gives another m-arylimido complex,
[(h5-C5H5)Ti(Cl)(m-NC6H4NMe2-2)]2, which contains intramolecular titanium and nitrogen coordination. In addition, the
analogous reactions of the above substituted half-sandwich Cp titanium complexes with PhNHLi in the presence of Et3N lead to
[(h5-C5H4CH2CH2Br)Ti(Br)(m-NPh)]2, [(h5-C5H4CH2CH2OCH3)Ti(Cl)(m-NPh)]2. The addition of 2-MeC6H4NHLi to (h5-
C5H4CH2CH2OCH3)TiCl3 and (h5-C5H5)TiCl3 affords imido derivatives [(h5-C5H5)Ti(Cl)(m-NC6H4CH3-2)]2 and [(h5-
C5H4CH2CH2OCH3)Ti(Cl)(m-NC6H4CH3-2)]2. [(h5-C5H5)Ti(Cl)(m-NC6H3Me2-2,6)]2 is prepared by refluxing of (h5-C5H5)TiCl3
and 2,6-Me2C6H3NMg·THF in toluene. The titanium m-pyridylimido complexes, [(h5-C5H5)Ti(Cl)(m-NPy-2)]2, [(h5-
C5H4CH2CH2OCH3)Ti(Cl)(m-NPy-2)]2 and [(h5-C5H4CH2CH2Br)Ti(Br)(m-NPy-2)]2, are synthesized by reactions of the above
corresponding half sandwich Cp titanium complexes with an equivalent of 2-PyNHLi in the presence of Et3N, respectively.
(
,
Compound 1 crystallizes in the triclinic space group P1 (no. 2) with a=9.942(2), b=10.057(3), c=8.457(2) A, h=111.28(2),
3
,
i=106.71(2), k=98.12(2)°, V=725.5(4) A , Z=2. The catalytic activity and selectivity of compound 4 for the styrene
polymerization is also investigated. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Titanium; Imido; Pyridyl; Intramolecular coordination; Crystal structure
C5H5) in reaction with Me3SiN(H)R (R=Et, Pri, But,
1. Introduction
Ph) to yield the amido complexes CpTi(Cl)2N(H)R,
Organoimido complexes of the transition metals have
attracted considerable interest, particularly those of the
electrophilic early transition metals of Group IV. Such
complexes have shown potential in both alkane and
arene CꢀH bond activation [1] as well as 2+2 cycload-
ditions [2], catalytic amination of alkynes [3] and ad-
duct chemistry [1c,d,2a,4].
Titanium bridging imido complexes are still compar-
atively scarce. The first example was reported by
Teuben and co-workers [5]. They used CpTiCl3 (Cpꢁh5-
which reacted further by HCl abstraction to give the
corresponding centrosymmetric binuclear imido com-
plexes [Cp(Cl)Ti(m-NR)]2 (Scheme 1).
Power and co-workers [6] used organomagnesium
compound, (PhNMg·THF)6, as a transfer agent for the
imido group NPh to a transition-metal center to give
the corresponding metal imido complex; particularly
they reacted Cp2TiCl2 with (PhNMg·THF)6 to afford a
asymmetric m-phenylimido complex (h5-C5H5)(Cl)Ti(m-
NPh)2Ti(h5-C5H5)2 (Scheme 1).
To provide for systematic studies of such com-
pounds, we set out to develop general, high-yield routes
to bridging imido species of titanium. In this paper, we
report the preparation of bridging imido complexes of
* Corresponding author. Fax: +86-21-64702573.
E-mail address: qianling@online.sh.cn (Y. Qian)
1 Present address: Department of Chemistry, Northwest Normal
University, Lanzhou 730070, PR China.
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00732-9

340
Z. Li et al. / Journal of Organometallic Chemistry 598 (2000) 339–347
Scheme 1.
titanium bearing (un)substituted cyclopentadienyl. We
found that in some of such complexes, there is in-
tramolecular coordination between O and N of sub-
stituents and central metal. In this paper, we also report
the preparation of titanium m-pyridylimido complexes
as the first example of titanium bridging imido com-
plexes containing a heterocyclic group. As a part of this
study, the molecular structure of the bridging imido
complex [(h5-C5H4CH2CH2Br)Ti(Br)(m-NC6H4OCH3-
2)]2 (1) has been determined, and the catalytic behavior
of the bridging imido species [(h5-C5H5)Ti(Cl)(m-
NC6H4OCH3-2)]2 (4) has been investigated.
However, by refluxing of (h5-C5H5)2TiCl2 with an
equivalent of 2-MeOC6H4NHLi in the presence of
Et3N, a dark-red solid is also afforded, which is charac-
terized as 4, the same product as is produced by
treatment of (h5-C5H5)TiCl3 with an equivalent of 2-
MeOC6H4NHLi in the presence of Et3N (Scheme 3).
This result is quite different from the analogous experi-
ment of Power and co-workers [6], and indicates the
abstraction of cyclopentadiene.
Complexes 1–4 are very sensitive to air and mois-
ture, and have good solubility in toluene, tetrahydro-
furan and chlorinated solvents, but poor solubility in
ether and hexane.
The synthetic process of 1–4 may involve formation
of an amide precursor followed by an amide abstrac-
tion step via deprotonation to give imido species [5].
Complexes 1–4 are characterized by spectral and
2. Results and discussion
1
2.1. Syntheses of titaniumv–arylimido complexes with
elemental analyses. From the H-NMR spectra, signifi-
intramolecular coordination
cant downfield shifts (ca. 0.4 ppm) are observed for the
signals of the methoxyl groups linked to aryl rings
compared with the analogous resonance for 2-
MeOC6H4NH2 in the same deuterated solvent. These
indicate the presence of intramolecular coordination
between oxygen atoms attached to aryl rings and cen-
tral metals. Meanwhile the upfield shifts for the signals
of methyl and methylene groups linked to cyclopentadi-
enyl in 2 and 3 indicate the absence of coordination
Treatment of (h5-C5H4CH2CH2Br)TiBr3, (h5-C5H4-
CH2CH2OCH3)TiCl3,
(h5-C5H4-CH2-cyclo-C4H7O)-
TiCl3 and (h5-C5H5)TiCl3 with an equivalent of 2-
MeOC6H4NHLi at −20°C in the presence of Et3N,
gives the m-arylimido complexes 1–4, with intramolecu-
lar coordination between oxygen and titanium, as dark-
red crystals (Scheme 2).
Scheme 2.

Z. Li et al. / Journal of Organometallic Chemistry 598 (2000) 339–347
341
Table 1
,
Selected bond lengths (A) and angles (°) for compound 1
Bond lengths
Ti(1)···Ti(1*)
Ti(1)ꢀN(1)
Ti(1)ꢀN(1*)
Ti(1)ꢀO(1)
Ti(1)ꢀBr(1)
N(1)ꢀC(10)
2.927(3)
1.969(6)
1.908(7)
2.348(7)
2.537(2)
1.37(1)
Ti(1)ꢀC(1)
Ti(1)ꢀC(2)
Ti(1)ꢀC(3)
Ti(1)ꢀC(4)
Ti(1)ꢀC(5)
2.40(1)
2.36(1)
2.39(1)
2.385(1)
2.398(1)
Scheme 3.
Bond angles
Ti(1)ꢀN(1)ꢀTi(1*)
N(1)ꢀTi(1)ꢀN(1*)
Ti(1)ꢀO(1)ꢀC(8)
Ti(1)ꢀO(1)ꢀC(9)
98.0(3)
82.0(3)
130.6(5)
112.4(6)
Ti(1)ꢀN(1)ꢀC(10)
Br(1)ꢀTi(1)ꢀN(1*)
Br(1)ꢀTi(1)ꢀN(1)
123.8(6)
92.0(2)
120.2(2)
between oxygen atoms of side chains and central metals,
although there is chelation of the oxygen atom to the ti-
tanium center in (h5-C5H4CH2CH2OCH3)TiCl3 and (h5-
C5H4ꢀCH2-cyclo-C4H7O)TiCl3 [7].
Complex 1 is also determined by X-ray diffraction; the
single-crystal structure is shown in Fig. 1, selected bond
lengths and angles are given in Table 1. It is a dimer with
the titanium centers linked by bridging arylimido groups
giving a central Ti2N2 heterocyclic ring. Each titanium
atom is bound to an (h5-C5H4CH2CH2Br) ring and a Br
Having prepared the titanium m-imido compounds
with intramolecular coordination between Ti and O
atom, it was decided to synthesize titanium imido com-
plexes with intramolecular coordination between the Ti
and N atom. When (h5-C5H5)TiCl3 is treated with an
equivalent of 2-Me2NC6H4NMg(THF) in refluxing
toluene, a dark-red solid is isolated, which is identified
spectroscopically as the dimer m-imido product 5
(Scheme 4).
,
atom. The Ti···Ti distance (2.927(3) A) is unusually short
for a binuclear titanium (IV) complex, and similar dis-
tances have been observed in the related species [6,8].
Both TiꢀN bond lengths for 1 are in the range reported
for other titanium–m imido compounds; so are the
TiꢀNꢀTi and NꢀTiꢀN angles. However, both TiꢀN bond
distances differ slightly from each other, indicating the
bridging m-imido ligands may be bound asymmetrically.
The 1H-NMR spectrum of 5 in CDCl3 shows a signifi-
cant downfield shift (ca. 0.5 ppm) for the signal of the
methyl groups attached to nitrogen (l 2.89 ppm) in com-
parison with the analogous resonance for 2-
Me2NC6H4NH2 (l 2.35 ppm). On the basis of this, we
propose that there is intramolecular coordination be-
tween nitrogen atoms and central metals in compound 5.
The attempt to prepare similar complexes to 5 con-
taining a substituted cyclopentadienyl was unsuccessful
due to steric effects.
,
The TiꢀO bond length of 2.348(7) is 1.33 A shorter than
,
the sum of the van der Waals radii (3.68 A) [9], indicat-
ing a strong interaction between Ti and O.
2.2. Syntheses of titanium v-arylimido complexes
containing (un)substituted cyclopentadienyl
Treatment of corresponding substituted Cp titanium
trihalides with an equivalent of PhNHLi or 2-
MeC6H4NHLi at −20°C in the presence of Et3N gave
m-arylimido complexes 6–9 as dark-red crystals (Scheme
5).
Compounds 6–9 are more sensitive to air and mois-
ture than compounds 1–4, but have similar solubility in
Fig. 1. Molecular structure of compound 1.
Scheme 4.

342
Z. Li et al. / Journal of Organometallic Chemistry 598 (2000) 339–347
Scheme 5.
Scheme 7.
toluene, tetrahydrofuran and chlorinated solvents.
(Py=pyridyl), which is prepared by the reaction of
2-aminopyridine with n-BuLi in THF, at −20°C in the
presence of Et3N, respectively, gives m-pyridylimido
complexes 11–13 in good yields as dark-red crystals
(Scheme 7).
Complexes 11–13 are more sensitive to air and mois-
ture than m-arylimido complexes. However, they have
similar solubility to 1–4.
However, 7 and 9 are intermediately soluble in hexane.
1
An interesting feature in the H-NMR spectra of 7
and 9 in CDCl3 is the upfield shifts (ca. 0.2–0.3 ppm)
for the signals of the methyl groups attached to oxygen
atoms (l 3.21, 3.12 ppm) compared with the analogous
resonance for (h5-C5H4CH2CH2OCH3)TiCl3, (l 3.43
ppm) in the same deuterated solvent. Even more signifi-
cant is the shifts to upfield (ca. 0.3–0.5 ppm) of the
signals for the methylene groups linked to oxygen
atoms (l 3.39, 3.18 ppm) which are comparable to the
value in (h5-C5H4CH2CH2OCH3)TiCl3, (l 3.67 ppm).
These differences indicate an important change in the
environment of the oxygen atoms. Therefore, we pro-
pose that there is no intramolecular coordination be-
tween oxygen atoms of side chains and central metals in
7 and 9 although there is chelation of the oxygen atom
to the titanium center in the starting material (h5-
C5H4CH2CH2OCH3)TiCl3 [7].
Complexes 11–13 are characterized by spectral and
elemental analyses. Upfield shifts of signals of the
methyl and methylene groups attached to oxygen atoms
1
in the H-NMR spectra of 12 in CDCl3 are also ob-
served. Therefore, there is no intramolecular coordina-
tion between oxygen atoms of side chains and central
metals in 12. In addition, a slightly change of proton
signals for the pyridyl in 11–13 compared to the 2-
aminopyridine is also observed.
Refluxing (h5-C5H5)TiCl3 with an equivalent of 2,6-
Me2C6H3NMg(THF) in a solution of toluene affords
titanium imido complex 10 as a dark-red solid in high
yield (Scheme 6).
We even tried to synthesize compound 10 by treating
(h5-C5H5)TiCl3 with an equivalent of 2,6-Me2C6H3-
NHLi in the presence of Et3N, but no pure product was
obtained because of separation problems.
2.4. Styrene polymerization study of compound 4
A preliminary styrene polymerization of the typical
compound 4 activated by methylaluminoxane (MAO)
shows 4–MAO has catalytic activity of 9.0×104 g of
PS/(mol of Ti · mol of S · h) (S=styrene, PS=
polystyrene) and 64.2% of the PS has syndiotactic
structure (s-PS, insoluble in refluxing 2-butanone) un-
der the conditions Al–Ti=2000 and Tp=50°C. In
comparison, under the same conditions, (h5-
C5H5)TiCl3–MAO has activity of 2.1×107 g of PS/
(mol of Ti·mol of S·h) with 98.3% yield of s-PS.
2.3. Syntheses of titanium v-pyridylimido complexes
containing (un)substituted cyclopentadienyl
Treatment of the above corresponding substituted Cp
titanium trihalides with an equivalent of 2-PyNHLi
3. Conclusions
The work described in this paper represents two new
approaches to the syntheses of m-arylimido and m-
pyridylimido complexes via treatment of (un)sub-
stituted cyclopentadienyl titanium complexes with
ArNHLi–Et3N, PyNHLi–Et3N or ArNMg·THF, re-
spectively. Supposing there are coordinatable atoms,
such as oxygen and nitrogen, in the ortho-position of
aryl, m-arylimido complexes containing intramolecular
coordination are given.
Scheme 6.

Z. Li et al. / Journal of Organometallic Chemistry 598 (2000) 339–347
343
4. Experimental
C6H4). IR (KBr, cm−1): w 2939 (s), 2679 (s), 2491 (m),
1603 (m), 1489 (vs), 1456 (m), 1434 (m), 1398 (w), 1262
(s), 1171 (w), 1114 (w), 1036 (m), 804 (vs), 753 (vs), 622
(s), 591 (s). MS: m/z 668 (M−C5H4CH2CH2Br, 5), 576
(M-C5H4CH2CH2Br−CH2Br, 3), 339 (M/2−Br, 4),
325 (M/2−CH2Br, 17), 246 (M/2−C5H4CH2CH2Br,
9), 91 (C5H4CH2CH2, 100).
4.1. General considerations
All manipulations were carried out under an argon
atmosphere using standard Schlenk techniques. Sol-
vents (THF, toluene, and n-hexane) were dried over the
sodium–benzophenone ketyl. Halogenated solvents
were distilled from P2O5. C6H5NH2, 2-MeOC6H4NH2,
2-MeC6H4NH2, 2,6-Me2C6H3NH2 were distilled from
CaH2 prior to use. 2-Me2NC6H4NH2 was prepared by
the reaction of 2-O2NC6H4NMe2 with Fe–HCl. 2-
Aminopyridine was available commercially and used as
received. n-Bu2Mg was prepared according to the
Kamienski method [10]. (h5-C5H5)TiCl3 [11], (h5-
C5H4CH2CH2Br)TiBr3 [12], (h5-C5H4CH2CH2OCH3)-
TiCl3, (h5-C5H4-CH2-cyclo-C4H7O)TiCl3 [7] and (h5-
C5H5)2TiCl2 [13] were prepared according to literature
procedures. 1H-NMR spectra were measured on a
Gemini-300 NMR Spectrometer using CDCl3 as sol-
vent and Me4Si as an internal standard. Mass spectra
were performed on a Hitachi-80 Mass Spectrometer. IR
4.4. Preparation of 2
To a solution of 0.45 g (1.62 mmol) of (h5-
C5H4CH2CH2OMe)TiCl3 in 50 ml of THF, 0.25 g (1.94
mmol) of 2-MeOC6H4NHLi in 10 ml of THF was
added dropwise at −20°C. A rapid color change from
orange to red was observed. After addition, the mixture
was warmed to r.t. and stirred for 4 h. Then 0.20 g
(1.94 mmol) of Et3N in 5 ml of THF was added at r.t.
The mixture was stirred for another 4 h. After that, the
solvent was removed in reduced pressure, the dark-red
residue was extracted with 50 ml of toluene and the
resulting extract was concentrated to ca. 30 ml. Dark-
red crystals (0.40 g) were obtained upon slow cooling to
−20°C (75% yield based on Ti). M.p. 167°C. Anal.
Calc. for C30H36Cl2N2O4Ti2: C, 54.99; H, 5.54; N, 4.27.
Found: C, 54.90; H, 5.53; N, 4.24. 1H-NMR (300 MHz,
CDCl3) l 2.67 (m, 4H, CH2), 3.15 (s, 6H, CH3), 3.31
(m, 4H, CH2), 4.22 (s, 6H, CH3), 5.79 (m, 2H, C5H4),
6.00 (m, 2H, C5H4), 6.13 (m, 2H, C5H4), 6.23 (m, 2H,
C5H4), 6.85 (m, 2H, C6H4), 6.91 (m, 4H, C6H4), 7.02
(m, 2H, C6H4). IR (KBr, cm−1): w 3091 (w), 2929 (m),
2868 (s), 1626 (w), 1478 (vs), 1383 (w), 1281 (m), 1256
(vs), 1219 (s), 1180 (m), 1112 (vs), 1038 (m), 1007 (s),
820 (s), 743 (s), 660 (vs). MS: m/z 619 (M−Cl, 29), 531
(M−C5H4CH2CH2OCH3, 100), 327 (M/2, 28), 91
(C5H4CH2CH2, 19).
spectra were recorded on
Spectrometer.
a
Magna-IR550 IR
4.2. Preparation of 2-MeOC6H4NHLi
To a solution of 4.43 g (36 mmol) of o-anisidine in 50
ml of n-hexane, 22.5 ml (1.6 M in n-hexane, 36 mmol)
of n-BuLi was added dropwise at 0°C. A white precipi-
tate appeared immediately. Then the reaction mixture
was stirred for 2 h at room temperature (r.t.). After
filtration of the mixture, the residue was washed with
3×25 ml of n-hexane, and 4.3 g of white solid was
given in 93% yield.
4.3. Preparation of 1
4.5. Preparation of 3
To
a
solution of 0.5
g
(1.1 mmol) of (h5-
To a solution of 0.4 g (1.82 mmol) of (h5-C5H4ꢀCH2-
cyclo-C4H7O)TiCl3 in 20 ml of THF, 0.28 g (2.18
mmol) of 2-MeOC6H4NHLi in 10 ml of THF was
added dropwise at −20°C. A rapid color change from
orange to red was observed. After addition, the mixture
was warmed to r.t. and stirred for 4 h. Then 0.22 g
(2.18 mmol) of Et3N in 5 ml of THF was added at r.t.
The mixture was stirred for another 4 h. After that, the
solvent was removed in reduced pressure, the dark-red
residue was extracted with 50 ml of toluene and the
resulting extract was concentrated to ca. 30 ml. 0.30 g
of dark-red crystals were obtained upon slow cooling to
−20°C (61% yield based on Ti). M.p. 182°C. Anal.
Calc. for C32H34Cl2N2O4Ti2: C, 57.73; H, 5.70; N, 3.96.
Found: C, 57.43; H, 6.23; N, 4.64. 1H-NMR (300 MHz,
CDCl3) 6.80 (m, 10H, C6H4), 6.21 (m, 2H, C5H4), 6.08
(m, 2H, C5H4), 5.98 (m, 2H, C5H4), 5.80 (m, 2H, C5H4),
4.19 (s, 6H), 3.84 (s, 2H), 3.65 (m, 4H), 3.08 (m, 4H),
C5H4CH2CH2Br)TiBr3 in 50 ml of THF, 0.17 g (1.3
mmol) of 2-MeOC6H4NHLi in 10 ml of THF was
added dropwise at −20°C. A rapid color change from
orange to red was observed. After addition, the mixture
was warmed to r.t. and stirred for 4 h. Then 0.13 g (1.3
mmol) of Et3N in 5 ml of THF was added at r.t. The
mixture was stirred for another 4 h. After that, the
solvent was removed in reduced pressure, the dark-red
residue was extracted with 50 ml of toluene and the
resulting extract was concentrated to ca. 30 ml. Dark-
red crystals (0.15 g) were obtained upon slow cooling to
−20°C (69% yield based on Ti). M.p. 132°C. Anal.
Calc. for C28H30Br4N2O2Ti2: C, 39.94; H, 3.59; N, 3.33.
Found: C, 39.95; H, 3.82; N, 3.28. 1H-NMR (300 MHz,
CDCl3) l 2.87 (m, 4H, CH2), 3.30 (m, 4H, CH2), 4.29
(s, 6H, CH3), 5.89 (m, 2H, C5H4), 6.18 (m, 2H, C5H4),
6.24 (m, 2H, C5H4), 6.35 (m, 2H, C5H4), 7.01 (m, 8H,

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Z. Li et al. / Journal of Organometallic Chemistry 598 (2000) 339–347
2.53 (m, 4H), 1.66 (m, 4H). IR (KBr, cm−1): 3431 (m),
3088 (w), 2943 (m), 2863 (m), 1587 (s), 1475 (s), 1397
(m), 1279 (s), 1250 (s), 1217 (s), 1175 (m), 1110 (s), 1035
(s), 1000 (s), 808 (s), 741 (s), 653 (s), 499 (s). MS: m/z
657 (M−CH3ꢀCl, 8), 507 (M−C5H9OꢀCpꢀCH3ꢀCl,
94), 352 (M/2−1, 59), 151 (C5H9OꢀCp+2, 100), 108
(C6H5OCH3+1, 53), 71 (C4H8O, 72).
precipitate via filtration, the filtrate was concentrated to
ca. 20 ml. 0.43 g of dark-red solid was obtained upon
slow cooling to −20°C (56% yield). M.p. 260°C. Anal.
Calc. for C26H30Cl2N4Ti2: C, 55.25; H, 5.35; N, 9.91.
Found: C, 54.45; H, 5.12; N, 9.76. 1H-NMR (300 MHz,
CDCl3) l 2.89 (s, 12H, CH3), 6.26 (s, 10H, C5H5), 6.81
(m, 4H, C6H4), 7.16 (m, 4H, C6H4). IR (KBr, cm−1): w
3055 (w), 2903 (w), 1579 (m), 1469 (s), 1308 (m), 1281
(s), 1261 (m), 1240 (m), 1149 (m), 1097 (m), 1029 (m),
914 (s), 806 (s), 750 (s), 644 (s), 614 (m). MS: m/z 499
(M−C5H5, 1.2), 430 (M−C10H8N2, 0.7), 91 (C6H4−
N, 100), 65 (C5H5, 15).
4.6. Preparation of 4
Method A: to a solution of 0.4 g (1.82 mmol) of
(h5-C5H5)TiCl3 in 40 ml of THF, 0.28 g (2.18 mmol) of
2-MeOC6H4NHLi in 10 ml of THF was added drop-
wise at −20°C. A rapid color change from yellow to
red was observed. After addition, the mixture was
warmed to r.t. and stirred for 4 h. Then 0.22 g (1.94
mmol) of Et3N in 5 ml of THF was added at r.t. The
mixture was stirred for another 4 h. After that, the
solvent was removed in reduced pressure, the dark-red
residue was extracted with 50 ml of toluene and the
resulting extract was concentrated to ca. 30 ml. Dark-
red crystals (0.30 g) were obtained upon slow cooling to
−20°C (61% yield based on Ti). M.p. (dec.) 238°C.
Anal. Calc. for C24H24Cl2N2O2Ti2: C, 53.47; H, 4.49; N,
4.9. Preparation of PhNHLi
To a solution of 2.70 g (29 mmol) of aniline in 50 ml
of n-hexane, 20 ml (1.45 M in n-hexane, 29 mmol) of
n-BuLi was added dropwise at 0°C. A white precipitate
appeared immediately. Then the reaction mixture was
stirred for 2 h at r.t. After filtration of mixture, the
residue was washed with 3×25 ml of n-hexane, and
2.75 g of white solid was given in 96% yield.
4.10. Preparation of 6
1
5.20. Found: C, 53.41; H, 4.54; N, 4.83. H-NMR (300
MHz, CDCl3) l 4.25 (s, 6H, CH3), 6.21 (s, 10H, C5H5),
6.85 (m, 2H, C6H4), 6.94 (m, 4H, C6H4), 7.05 (m, 2H,
C6H4). IR (KBr, cm−1): w 3099 (w), 2941 (w), 1587 (w),
1475 (s), 1448 (m), 1319 (w), 1279 (m), 1254 (s), 1111
(m), 1008 (s), 899 (w), 813 (vs), 745 (s), 664 (s). MS:
m/z 538 (M, 46), 503 (M−Cl, 67), 473 (M−C5H5,
100), 458 (M−C5H5−CH3, 39), 148 (C5H5TiCl, 20).
Method B: a suspension of 0.8 g (3.2 mmol) of
To a solution of 1.29 g (2.8 mmol) of (h5-
C5H4CH2CH2Br)TiBr3 in 50 ml of THF, 0.28 g (1.3
mmol) of PhNHLi in 10 ml of THF was added drop-
wise at −20°C. A rapid color change from orange to
red was observed. After addition, the mixture was
warmed to r.t. and stirred for 4 h. Then 0.31 g (3.4
mmol) of Et3N in 5 ml of THF was added at r.t. The
mixture was stirred for another 4 h. After that, the
solvent was removed in reduced pressure, the dark-red
residue was extracted with 50 ml of toluene and the
resulting extract was concentrated to ca. 30 ml. Dark-
red crystals (0.7 g) were obtained upon slow cooling to
−20°C (64% yield based on Ti). M.p. 140°C. Anal.
Calc. for C26H26Br4N2Ti2: C, 39.94; H, 3.35; N, 3.58.
Found: C, 39.94; H, 3.39; N, 3.52. 1H-NMR (300 MHz,
(h5-C5H5)2TiCl2 and 0.45
g (3.52 mmol) of 2-
MeOC6H4NHLi in 50 ml of toluene was refluxed for 8
h. Then 0.39 g (3.53 mmol) of Et3N was added at 90°C.
The mixture was refluxed for another 5 h. After re-
moval of precipitate via filtration, the filtrate was con-
centrated to ca. 30 ml. 0.45 g of dark-red solid was
obtained upon slow cooling to −20°C (52% yield
based on Ti).
3
CDCl3) l 2.92 (t, 4H, J=6.98 Hz, CH2), 3.35 (t, 4H,
3
3J=6.98 Hz, CH2), 6.15 (t, 4H, J=2.70 Hz, C5H4),
3
4.7. Preparation of 2-Me2NC6H4NMg·THF
6.41 (t, 4H, J=2.70 Hz, C5H4), 6.70 (m, 4H, C6H5),
7.04 (m, 2H, C6H5), 7.26 (m, 4H, C6H5). IR (KBr,
cm−1): w 2878 (s), 2589 (w), 1564 (m), 1494 (s), 1474 (s),
1235 (s), 862 (s), 805 (vs), 767 (s), 693 (m), 628 (m). MS:
m/z 782 (M, 46), 703 (M−Br, 75), 620 (M−2Br, 43),
529 (M−2Br−C6H5N, 25), 391 (M/2, 23), 91
(C5H4CH2CH2, 100).
A total of 30 ml (18.4 mmol in ether solution) of
n-Bu2Mg was added dropwise to 2.5 g (18.4 mmol) of
2-Me2NC6H4NH2 in 20 ml of THF at r.t., and the
solution was stirred for 12 h. The resulting white solid
was filtered and washed with hexane (3×15 ml) to
yield 3.5 g of 2-Me2NC6H4NMg·THF in 93% yield.
4.11. Preparation of 7
4.8. Preparation of 5
To a solution of 0.63 g (2.27 mmol) of (h5-
C5H4CH2CH2OMe)TiCl3 in 20 ml of THF, 0.27 g (2.72
mmol) of PhNHLi in 10 ml of THF was added drop-
wise at −20°C. A rapid color change from orange to
A suspension of 0.6 g (2.73 mmol) of (h5-C5H5)TiCl3
and 0.63 g (2.73 mmol) of 2-Me2NC6H4NMg·THF in
35 ml of toluene was refluxed for 12 h. After removal of

Z. Li et al. / Journal of Organometallic Chemistry 598 (2000) 339–347
345
red was observed. After addition, the mixture was
warmed to r.t. and stirred for 4 h. Then 0.28 g (2.72
mmol) of Et3N in 5 ml of THF was added at r.t. The
mixture was stirred for another 4 h. After that, the
solvent was removed in reduced pressure, the dark-red
residue was extracted with 50 ml of toluene and the
resulting extract was concentrated to ca. 30 ml. Dark-
red crystals (0.45 g) were obtained upon slow cooling to
−20°C (68% yield based on Ti). M.p. 74°C. Anal.
Calc. for C28H32Cl2N2O2Ti2: C, 56.50; H, 5.42; N, 4.71.
Found: C, 56.40; H, 5.44; N, 4.86. 1H-NMR (300 MHz,
CDCl3) l 2.66 (t, 4H, J=6.46 Hz, CH2), 3.21 (s, 6H,
CH3), 3.39 (t, 4H, J=6.46 Hz, CH2), 6.01 (t, 4H,
J=2.65 Hz, C5H4), 6.35 (t, 4H, J=2.65 Hz, C5H4),
6.67 (m, 4H, C6H5), 7.00 (m, 2H, C6H5), 7.25 (m, 4H,
C6H5). IR (KBr, cm−1): w 2869 (vs), 2588 (s), 2868 (s),
1631 (w), 1600 (m), 1525 (m), 1494 (vs), 1461 (m), 1381
(m), 1197 (w), 1116 (s), 1031 (m), 843 (s), 796 (vs), 743
(s), 617 (s). MS: m/z 559 (M−Cl, 32), 484 (M−Cl−
C6H5, 15), 471 (M−C5H4CH2CH2OCH3, 8), 297 (M/2,
100), 91 (C5H4CH2CH2, 8).
(M−C5H5, 17), 404 (M−Cl−C5H5, 96), 368 (M−
C5H5TiCl−Cl, 100), 148 (C5H5TiCl, 37).
4.14. Preparation of 9
To a solution of 0.69 g (2.49 mmol) of (h5-
C5H4CH2CH2OMe)TiCl3 in 20 ml of THF, 0.28 g (2.49
mmol) of 2-MeC6H4NHLi in 10 ml of THF was added
dropwise at −20°C. A rapid color change from orange
to red was observed. After addition, the mixture was
warmed to r.t. and stirred for 4 h. Then 0.25 g (2.72
mmol) of Et3N in 5 ml of THF was added at r.t. The
mixture was stirred for another 4 h. After that, the
solvent was removed in reduced pressure, the dark-red
residue was extracted with 50 ml of toluene and the
resulting extract was concentrated to ca. 30 ml. Dark-
red crystals (0.5 g) were obtained upon slow cooling to
−20°C (64% yield). M.p. 96°C. Anal. Calc. for
C30H36Cl2N2O2Ti2: C, 57.81; H, 5.82; N, 4.49. Found:
C, 57.66; H, 5.71; N, 4.40. 1H-NMR (300 MHz, CDCl3)
l 2.24 (s, 6H, CH3), 2.46 (m, 4H, CH2), 3.12 (s, 6H,
CH3), 3.18 (m, 4H, CH2), 5.99 (s, 2H, C5H4), 6.02 (s,
2H, C5H4), 6.39 (d, 2H, C5H4), 6.56 (s, 2H, C5H4), 6.96
(m, 2H, C6H4), 7.14 (m, 2H, C6H4), 7.70 (m, 2H, C6H4).
IR (KBr, cm−1): w 2916 (s), 2851 (s), 2607 (s), 2015 (w),
1579 (w), 1488 (s), 1459 (m), 1380 (w), 1116 (s), 1036
(m), 843 (s), 793 (s), 752 (s), 618 (m). MS: m/z 589
(M−Cl, 1), 499 (M−C5H4CH2CH2OCH3, 3), 311 (M/
2, 100), 206 (M/2−C7H7N, 34).
4.12. Preparation of 2-MeC6H4NHLi
To a solution of 9.7 g (58 mmol) of 2-MeC6H4NH2 in
50 ml of n-hexane, 40 ml (1.45 M in n-hexane, 58
mmol) of n-BuLi was added dropwise at 0°C. A white
precipitate appeared immediately. Then the reaction
mixture was stirred for 2 h at r.t. After filtration of
mixture, the residue was washed with 3×25 ml of
n-hexane, and 9.6 g of white solid was given in 95%
yield.
4.15. Preparation of 2,6-Me2C6H3NMg·THF
A total of 35 ml (0.61 M in ether solution, 21.4
mmol) of n-Bu2Mg was added dropwise to 2.6 g (21.4
mmol) of 2,6-Me2C6H3NH2 in 20 ml of THF at r.t.,
and the solution was stirred for 12 h. The resulting
white solid was filtered and washed with hexane (3×15
ml) to yield 2.0 g of 2,6-Me2C6H3NMg·THF (65%
yield).
4.13. Preparation of 8
To a solution of 0.63 g (2.87 mmol) of (h5-
C5H5)TiCl3 in 40 ml of THF, 0.32 g (2.87 mmol) of
2-MeC6H4NHLi in 10 ml of THF was added dropwise
at −20°C. A rapid color change from yellow to red
was observed. After addition, the mixture was warmed
to r.t. and stirred for 4 h. Then 0.29 g (2.87 mmol) of
Et3N in 5 ml of THF was added at r.t. The mixture was
stirred for another 4 h. After that, the solvent was
removed in reduced pressure, the dark-red residue was
extracted with 50 ml of toluene and the resulting extract
was concentrated to ca. 30 ml. Dark-red crystals (0.57
g) were obtained upon slow cooling to −20°C (78%
yield). M.p. 248°C. Anal. Calc. for C24H24Cl2N2Ti2: C,
56.84; H, 4.77; N, 5.52. Found: C, 57.02; H, 4.77; N,
4.16. Preparation of 10
A suspension of 0.3 g (1.43 mmol) of (h5-C5H5)TiCl3
and 0.21 g (1.43 mmol) of 2,6-Me2C6H3NMg·THF in
35 ml of toluene was refluxed for 12 h. After removal of
precipitate via filtration, the filtrate was concentrated to
ca. 20 ml. Dark-red solid (0.25 g) was obtained upon
slow cooling to −20°C (65% yield). M.p. 214°C. Anal.
Calc. for C26H28Cl2N2Ti2: C, 58.35; H, 5.27; N, 5.23.
Found: C, 58.40; H, 5.30; N, 5.44. 1H-NMR (300 MHz,
CDCl3) l 2.70 (s, 12H, CH3), 6.34 (s, 10H, C5H5), 6.97
(m, 6H, C6H3). IR (KBr, cm−1): w 2985 (s), 2851 (s),
2734 (s), 2556 (s), 2237 (m), 1976 (w), 1623 (m), 1585
(m), 1525 (s), 1474 (s), 1441 (m), 1263 (w), 1179 (w),
1093 (w), 1017 (s), 856 (s), 789 (s), 620 (s). MS: m/z 534
(M, 5), 499 (M−Cl, 2), 433 (M−C5H5−Cl, 12), 414
(M−C8H9N, 18), 267 (M/2, 8).
1
5.29. H-NMR (300 MHz, CDCl3) l 2.22 (s, 6H, CH3),
6.32 (s, 5H, C5H5), 6.62 (s, 5H, C5H5), 6.80 (m, 2H,
C6H4), 6.95 (m, 2H, C6H4), 7.06 (m, 2H, C6H4), 7.16
(m, 2H, C6H4). IR (KBr, cm−1): w 2854 (s), 2063 (s),
1978 (m), 1801 (w), 1589 (m), 1498 (s), 1460 (m), 1307
(w), 1144 (w), 1067 (w), 858 (s), 792 (s), 752 (s), 620 (s),
530 (s). MS: m/z 506 (M, 85), 471 (M−Cl, 57), 441

346
Z. Li et al. / Journal of Organometallic Chemistry 598 (2000) 339–347
4.17. Preparation of 2-PyNHLi
(m), 998 (w), 838 (m), 770 (s), 626 (m), 511 (s). MS: m/z
561 (M−Cl, 17), 473 (M−C5H4CH2CH2OCH3, 53),
396 (M−C5H4CH2CH2OCH3−C5H4N, 100), 360
(M−C5H4CH2CH2OCH3−C5H4N−Cl, 22).
To a solution of 3.29 g (35 mmol) of 2-aminopyridine
in 50 ml of THF, 35 ml (1.0 M in n-hexane, 35 mmol)
of n-BuLi was added dropwise at −20°C. Then the
reaction mixture was warmed to r.t. and stirred for 2 h.
After filtration of mixture, the residue was washed with
3×25 ml of n-hexane, and 3.3 g of reddish solid was
given in 94% yield.
4.20. Preparation of 13
To a solution of 0.7 g (1.52 mmol) of (h5-
C5H4CH2CH2Br)TiBr3 in 50 ml of THF, 0.15 g (1.52
mmol) of 2-PyNHLi and 0.15 g (1.52 mmol) Et3N in 10
ml of THF was added dropwise at −20°C. A rapid
color change from yellow to red was observed. After
addition, the mixture was warmed to r.t. and stirred for
4 h. Then the solvent was removed in reduced pressure,
the dark-red residue was extracted with 50 ml of
toluene and the resulting extract was concentrated to
ca. 30 ml. Red crystals were (0.70 g) obtained upon
slow cooling to −20°C (58% yield based on Ti). M.p.
156°C. Anal. Calc. for C24H24Br4N4O2Ti2: C, 36.78; H,
3.09; N, 7.15. Found: C, 36.66; H, 3.20; N, 7.01.
4.18. Preparation of 11
To a solution of 0.38 g (1.73 mmol) of (h5-
C5H5)TiCl3 in 40 ml of THF, 0.17 g (1.73 mmol) of
2-PyNHLi and 0.17 g (1.73 mmol) Et3N in 10 ml of
THF was added dropwise at −20°C. A rapid color
change from yellow to red was observed. After addi-
tion, the mixture was warmed to r.t. and stirred for 4 h.
Then the solvent was removed in reduced pressure, the
dark-red residue was extracted with 50 ml of toluene
and the resulting extract was concentrated to ca. 30 ml.
Red crystals (0.21 g) were obtained upon slow cooling
to −20°C (51% yield based on Ti). M.p. 162°C. Anal.
Calc. for C20H18Cl2N4Ti2: C, 49.94; H, 3.77; N, 11.65.
Found: C, 49.87; H, 3.67; N, 11.54. 1H-NMR (300
MHz, CDCl3) l 6.57 (m, 4H, C5H5), 6.66 (m, 6H,
C5H5), 6.68 (m, 2H, C5H4N), 6.90 (m, 2H, C5H4N),
7.48 (m, 2H, C5H4N), 8.05 (m, 2H, C5H4N). IR (KBr,
cm−1): w 3147 (s), 2970 (s), 1665 (s), 1621 (s), 1546 (w),
1477 (m), 1381 (m), 1325 (w), 1017 (m), 997 (m), 862
(s), 796 (s), 768 (s), 622 (s), 528 (s). MS: m/z 480 (M, 5),
445 (M−Cl, 10), 415 (M−Cp, 100), 338 (M−Cp−
C5H4N, 17).
3
1H-NMR (300 MHz, CDCl3) l 2.89 (t, 4H, J=6.84
3
Hz, CH2), 3.39 (t, 4H, J=6.84 Hz, CH2), 6.16 (t, 4H,
3
3J=2.66 Hz, C5H4), 6.36 (t, 4H, J=2.66 Hz, C5H4),
6.63 (m, 2H, C5H4N), 6.75 (m, 2H, C5H4N), 7.66 (m,
2H, C5H4N), 8.10 (m, 2H, C5H4N). IR (KBr, cm−1): w
3170 (s), 1666 (vs), 1622 (s), 1477 (w), 1429 (w), 1381
(w), 1325 (w), 1237 (w), 1166 (w), 1053 (w), 998 (w),
832 (m), 791 (s), 626 (m), 535 (s). MS: m/z 614 (M−
C5H4CH2CH2Br, 2), 532 (M−C5H4CH2CH2Br−Br,
1), 455 (M−C5H4CH2CH2Br−Br−C5H4N, 6), 391
(M/2, 24), 311 (M/2−Br, 100).
4.21. Styrene polymerization of 4
4.19. Preparation of 12
To a 20 ml reaction flask equipped with a septum
cap, 2 ml of styrene, 5.8 g of MAO, 5 mmol of com-
pound 4 and 10 ml of toluene were added by syringe,
and the mixture equilibrated at 50°C using an external
temperature bath. After a measured time interval with
stirring, the polymerization was quenched by the addi-
tion of 10% acidified ethanol. The precipitated polymer
was then collected by filtration, washed three times with
ethanol and dried on the high-vacuum line overnight.
After weighing, the polymer was refluxed in butanone
for 2 h, then filtered, dried and weighed to give syndio-
tactic polystyrene.
To a solution of 0.38 g (1.37 mmol) of (h5-
C5H4CH2CH2OMe)TiCl3 in 50 ml of THF, 0.15 g (1.51
mmol) of 2-PyNHLi and 0.15 g (1.51 mmol) Et3N in 10
ml of THF was added dropwise at −20°C. A rapid
color change from yellow to red was observed. After
addition, the mixture was warmed to r.t. and stirred for
4 h. Then the solvent was removed in reduced pressure,
the dark-red residue was extracted with 50 ml of
toluene and the resulting extract was concentrated to
ca. 30 ml. Red crystals (0.20 g) were obtained upon
slow cooling to −20°C (49% yield based on Ti). M.p.
124°C. Anal. Calc. for C26H30Cl2N4O2Ti2: C, 52.29; H,
5.06; N, 9.38. Found: C, 51.97; H, 5.37; N, 9.06.
1H-NMR (300 MHz, CDCl3) l 2.59 (t, 4H, J=6.45
Hz, CH2), 3.21 (s, 6H, CH3), 3.40 (t, 4H, J=6.45 Hz,
CH2), 6.11 (t, 4H, J=2.61 Hz, C5H4), 6.27 (t, 4H,
J=2.61 Hz, C5H4), 6.62 (m, 2H, C5H4N), 6.87 (m, 2H,
C5H4N), 7.66 (m, 2H, C5H4N), 8.05 (m, 2H, C5H4N).
IR (KBr, cm−1): w 3147 (s), 2921 (m), 1665 (s), 1621 (s),
1547 (w), 1476 (w), 1381 (w), 1325 (w), 1165 (w), 1117
4.22. X-ray structure determination of 1
A suitably sized dark-red crystal of 1 was obtained
by crystallization from methylene dichloride–n-hexane
(1:4). The crystal was mounted in a glass capillary. All
measurements were made on a Rigaku AFC7R diffrac-
tometer with graphite monochromated Mo–Ka radia-
,
tion (u=0.71069 A) and a 12 W rotating anode
generator. Crystallographic and experimental details

Z. Li et al. / Journal of Organometallic Chemistry 598 (2000) 339–347
347
Table 2
obtained free of charge from: The Director, CCDC, 12
Union Road, Cambridge, CB2 1EZ UK (Fax: +44-
1223-336033 or e-mail: deposit@ccdc.cam.ac.uk or
www:http//www.ccdc.cam.ac.uk)
Crystal data and structure refinement details for compound 1
Empirical formula
Temperature (°C)
TiBr2NOC14H15
25
,
Wavelength (A)
0.71069
0.22×0.23×0.35
Triclinic
Crystal dimensions (mm)
Crystal system
Acknowledgements
Lattice parameter
,
a (A)
9.9429(2)
10.057(3)
8.457(2)
111.28(2)
106.71(2)
98.12(2)
725.5(4)
We are grateful to the National Natural Science
Foundation of China (NNSFC) and Sino-Pec
(29734145) and NNSFC (29871010), The Research
Fund for The Doctoral Program of Higher Education
(RFDP), and State Key Laboratory of Coordination
Chemistry, Nanjing University for financial support of
this research.
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
(
Space group
Z value
P1 (no. 2)
2
Dcalc. (g cm−3
F(000)
)
1.927
412.00
61.04
v(Mo–Ka) (cm−1
)
Reflections measured
Total 2028
Unique 1895
(Rint=0.053)
1098
References
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Observations (I\3.00|(I))
Variables
172
Scan width (°)
Residuals: R; Rw
Goodness-of-fit indicator
(1.68+0.35 tan q)
0.036; 0.030
1.68
Maximum peak in final difference map
0.36
−3
,
(e A
)
Minimum peak in final difference map
0.51
−3
,
(e A
)
[3] (a) P.J. Walsh, A.M. Baranger, R.G. Bergman, J. Am. Chem.
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are summarized in Table 2. The data were collected at
a temperature of 25°C using the ꢀ−2q technique to a
maximum 2q value of 45.0°. The structure was solved
by heavy-atom Patterson methods, expanded using
Fourier techniques and refined by full-matrix least-
squares. The non-hydrogen atoms were refined an-
isotropically. Hydrogen atoms were included but not
refined. All calculations were performed using the
TEXSAN crystallographic software package of Molecu-
lar Structure Corporation.
5. Supplementary material
[9] A. Bondi, J. Phys. Chem. 68 (1964) 441.
[10] C.W. Kamienski, US Patent No. 646 231, CA 76:113360, 1968.
[11] D.M. Curtis, J.J.D. Errico, D.N. Duffy, P.S. Epstein, L.G. Bell,
Organometallics 2 (1983) 1808.
[12] Z. Li, J. Huang, Y. Qian, A.S.C. Chan, W.T. Wong, Inorg.
Chem. Commun. 2 (1999) 396.
The X-ray crystallographic data for the structural
analysis have been deposited with the Cambridge Crys-
tallographic Data Center (CCDC), CCDC no. 135667
for compound 1. Copies of this information may be
[13] D.F. Herman, W.K. Nelson, J. Am. Chem. Soc. 74 (1952) 2693.
.