A study on the development of CVD precursors V - Syntheses and characterization of new N-alkoxy-β-ketoiminate complexes of titanium

Article abstract of DOI:10.1016/j.jorganchem.2003.10.008

The synthesis and characterization of various new titanium N-alkoxy-β-ketoiminate complexes are reported. Reactions between N-alkoxy-β-ketoimine ligands and Ti(O- i Pr)₄ resulted in dimeric [Ti(O- i Pr)₂ (N-alkoxy-β-ketoiminate)]₂ complexes or monomeric [Ti(N-alkoxy-β-ketoiminate)₂] ones depending on the amount of ligands. Terdentate N-alkoxy-β-ketoiminate ligands do not prevent dimer complexes from undergoing disproportional rearrangement to produce Ti(O- i Pr)₄ and [Ti(N-alkoxy-β-ketoiminate)₂]. The mechanism of this behavior is too complicated but it may include the dissociation and recoordination of ligands. Crystal structures of [Ti(N-alkoxy-β-ketoiminate)₂] (MeC(O)CHC(Me)NC(Et)CH₂O (3f) and t-BuC(O)CHC(Me)NCH₂CH(Me)O (3k)) show that these are distorted octahedron and β-ketoiminate ligands appear to coordinate as a β-imino enolate. Two terdentate β-ketoiminate ligands coordinate meridionally and they are perpendicular to each other. Thermal characteristics of monomeric and dimeric titanium complexes were determined by TGA and DSC and these are reasonably volatile as potential precursors of TiO₂ thin films.

Full text of DOI:10.1016/j.jorganchem.2003.10.008

Journal of Organometallic Chemistry 689 (2004) 224–237
www.elsevier.com/locate/jorganchem
A study on the development of CVD precursors V – syntheses
and characterization of new N-alkoxy-b-ketoiminate
complexes of titanium q
a
Sunkwon Lim , Bohyun Choi , Yo-sep Min , Daesig Kim , Il Yoon ,
a
b
b
c
c
Shim Sung Lee , Ik-Mo Lee
a,
*
a
Department of Chemistry, Inha University, 253 Yonghyun-dong, Nam-ku, Inchon 402-751, Republic of Korea
Microelectronics Lab, Samsung Advanced Institute of Technology, San #24, Nongseo-Ri, Kiheung-Eup, Yongin-City,
Kyungki-Do 449-900, Republic of Korea
b
c
Department of Chemistry and Institute of Natural Sciences, Gyeongsang, National University, Chinju 660-701, Republic of Korea
Received 3 September 2003; accepted 7 October 2003
Abstract
The synthesis and characterization of various new titanium N-alkoxy-b-ketoiminate complexes are reported. Reactions between
N-alkoxy-b-ketoimine ligands and Ti(O-iPr)4 resulted in dimeric [Ti(O-iPr)2(N-alkoxy-b-ketoiminate)]2 complexes or monomeric
[Ti(N-alkoxy-b-ketoiminate)2] ones depending on the amount of ligands. Terdentate N-alkoxy-b-ketoiminate ligands do not prevent
dimer complexes from undergoing disproportional rearrangement to produce Ti(O-iPr)4 and [Ti(N-alkoxy-b-ketoiminate)2]. The
mechanism of this behavior is too complicated but it may include the dissociation and recoordination of ligands. Crystal structures
of [Ti(N-alkoxy-b-ketoiminate)2] (MeC(O)CHC(Me)NC(Et)CH2O (3f) and t-BuC(O)CHC(Me)NCH2CH(Me)O (3k)) show that
these are distorted octahedron and b-ketoiminate ligands appear to coordinate as a b-imino enolate. Two terdentate b-ketoiminate
ligands coordinate meridionally and they are perpendicular to each other. Thermal characteristics of monomeric and dimeric ti-
tanium complexes were determined by TGA and DSC and these are reasonably volatile as potential precursors of TiO2 thin films.
Ó 2003 Elsevier B.V. All rights reserved.
1. Introduction
[3]. Moreover, (Ba,Sr)TiO3 (BST) has drawn interests
due to its high dielectric constant and low leakage cur-
rent density, which can be applicable to a capacitor in
giga-bit dynamic random access memories (DRAMs)
[4].
For the successful fabrication of thin films containing
titanium oxides, suitable precursors with high volatility,
enhanced thermal and chemical stability and easy de-
composition are required. For BST thin film fabrication
by liquid source (LS) metalloorganic chemical vapor
deposition (MOCVD) method, enhanced compatibility
of titanium precursors with barium and strontium
complexes such as Ba(thd)2 and Sr(thd)2 (thd ¼ 2,2,6,6-
tetramethyl-2,5-heptanedionate) is another important
requirement [5]. However, the precursor chemistry of
titanium is far from well development.
Titanium oxide, TiO2, is an important component in
many ternary perovskites, the best known of which are
ferroelectrics, such as BaTiO3 (BT) and SrTiO3 (ST) [1].
The closely related materials [Pb(Zr,Ti)O3] (PZT) and
[(Pb,La)(Zr,Ti)O3] (PLZT) have also drawn much in-
terests due to their pyroelectric and ferroelectric prop-
erties, which have promising applications as infrared
detectors and next generation non-volatile ferroelectric-
based memory devices (FeRAMs) [2]. Recent report on
much increased dielectric constant of the material with
the addition of a small percentage of TiO2 to Ta2O5
offers the potential of improved performance DRAMs
q Supplementary data associated with this article can be found, in the
online version, at doi:10.1016/j.jorganchem.2003.10.008.
* Corresponding author. Tel.: 82328607682; fax: 82328675604.
E-mail address: imlee@inha.ac.kr (I.-M. Lee).
Up to date, several precursors such as TiCl4 [6] and
Ti(OR)4 (R ¼ Et, iPr) [7] have been used but some draw-
backs such as halide contamination of the films, high
0022-328X/$ - see front matter Ó 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2003.10.008

S. Lim et al. / Journal of Organometallic Chemistry 689 (2004) 224–237
225
fabrication temperature, and high reactivity towards
air and moisture, respectively. Several mixed ligand
complexes, such as [Ti(O-iPr)2(thd)2] [8], [Ti(O-iPr)x
(dmae)4 ꢀ x] (x ¼ 2; 3) (dmae ¼ dimethylaminoethoxide)
[9], [TiO(thd)2] [10], and [Ti(mpd)(thd)2] (mpd ¼ 2-
methyl-2,4-pentanedioxy) [5], have been recently adopted
as a titanium precursor in the liquid injection MOCVD
processes.
Recently, b-ketoiminate, b-diketiminate, and N-alk-
oxy-b-ketoiminate, a terdentate dianionic ligand, have
drawn interests and have been adopted successfully for
the preparation of MOCVD precursors [11] and cata-
lysts [12].
It was reported that Ti(OR)4 reacted with b-diketone
to produce [Ti(OR)3(b-diketonate)]2 or [Ti(OR)2(b-di-
ketonate)2] depending on the reaction conditions and
[Ti(OR)3(b-diketonate)]2 was fluxional [13]. Dispropor-
tionation of [Ti(OR)3(b-diketonate)]2 into Ti(OR)4 and
[Ti(OR)2(b-diketonate)2] was also reported [14]. Fluxi-
onality of [Ti(OR)3(b-diketonate)]2 may induce chemical
instability and transformation, which should be avoided
during storage or delivery in the MOCVD process. It is
expected that this type of disproportionation reaction
can be freezed by N-alkoxy-b-ketoiminates, terdentate
ligands, due to enhanced chelate effect and limited al-
lowed conformations. Enhanced chemical and thermal
stability of [M(OR)3(N-alkoxy-b-ketoiminate)] (M ¼
Nb, Ta) and much higher deposition rate with reduced
carbon residue in the MOCVD process [11i] is another
reason to prepare titanium complexes with alkoxide and
N-alkoxy-b-ketoiminate ligands. Contrary to this
expectation, [Ti(O-iPr)2(N-alkoxy-b-ketoiminate)]2 is
disproportionated to produce Ti(O-iPr)4 and [Ti(N-
alkoxy-b-ketoiminate)2].
In this study, new titanium complexes containing N-
alkoxy-b-ketoiminate ligands have been prepared and
characterized.
2. Results and discussion
2.1. Synthesis of ligands and complexes
As shown in Scheme 1, various N-alkoxy-b-ketoimine
ligands can be prepared by the simple dehydration re-
action between b-diketone and amino alcohols, some-
times in the presence of acid catalysts such as formic
acid or p-toluenesulfonic acid (p-TsOH). Yields are
generally high but rather low in the cases of bulky
substituents as expected.
Prepared N-alkoxy-b-ketoimine ligands react with
Ti(O-iPr)4 to produce dimeric [Ti(O-iPr)2(N-alkoxy-b-
ketoiminate)]2 complexes or monomeric [Ti(N-alkoxy-b-
ketoiminate)2] ones depending on the amount of ligands
(Schemes 2 and 3).
2.2. Structures and disproportional rearrangements of
[Ti(N-alkoxy-b-ketoiminate)(OR)2]2
In order to investigate the mechanism of the dispro-
portional rearrangement, several experiments shown in
Scheme 4 have been done.
Driving force of this disproportional rearrangements
may be thermodynamic stabilities of one of or both
homoleptic titanium complexes such as Ti(OR)4 and
[Ti(N-alkoxy-b-ketoiminate)2]. [Ti(N-alkoxy-b-ketoimi-
nate)2] was found to be stable toward the addition of
Ti(OR)4 up to 10 equivalents. However, [Ti(N-alkoxy-b-
Scheme 1.

226
S. Lim et al. / Journal of Organometallic Chemistry 689 (2004) 224–237
Scheme 2.
Scheme 3.
ketoiminate)2] produced dimer complexes in an hour in
the presence of 4 equivalents of Ti(OR)4 and 10 equiv-
alents of isopropanol. It is also found that sublimation of
these dimeric complexes under reduced pressure (around
10ꢀ2 Torr) induces disproportional rearrangement to
produce Ti(O-iPr)4 and [Ti(N-alkoxy-b-ketoiminate)2].
From these experiments, it indicates that free isopropa-
nol or isoproxide ion may involve in this disproportional
process. In order to find some supporting evidences,
variable temperature (VT) NMR (1H and 13C) experi-
ments of 2a and 2d have been done. The spectra were too
complicated to be interpreted reasonably (supplemen-
tary information) but many peaks for C(O)CHC(N) of
N-alkoxy-b-ketoiminate ligands (ꢁ5 ppm in 1H, 160–180
ppm in 13C) and for MeÕs of N-alkoxy-b-ketoiminate and
nate ligands and Ti(OR)4. Based on these observations,
the possible pathways involving isomerization and ex-
change of isopropoxides are described in Scheme 5. Even
though [Ti(OR)3(b-diketonate)]2 is reported to undergo
disproportional rearrangement via a nondissociative
pathway where exchange of bridging OR and b-diketo-
nate ligands occurs [14], the dissocitation of isopropox-
ide and/or possibly N-alkoxy-b-ketoiminate ligands is
proposed due to faster exchange rates in polar solvents
(toluene < CHCl3 < CH3CN). Possible involvement of a
5-coordinate monomeric complex can be effectively ex-
cluded by no change in the presence of pyridine, THF
and CH3CN.
2.3. Crystal structures of [Ti(N-alkoxy-b-ketoiminate)2]
1
isoproxide ligands (1–2 ppm in H and 20–70 ppm in
13C) indicate that more than 2 isomers must be involved
in this rearrangement. Also addition of Ti(OR)4 (1
equivalent) to this solution retards the exchange rate
possibly due to formation of starting dimeric complex by
the reaction between dissociated N-alkoxy-b-ketoimi-
Crystal structures of Ti(CH3C(O)CHC(NCH(CH2
CH3)CH2O)CH3)2 (3f) and Ti((CH3)3CC(O)CHC(N
CH2CH(Me)O)CH3)2 (3k) are determined by single
crystal X-ray crystallography and these structures are
shown in Figs. 1 and 2, respectively. Selected bond

S. Lim et al. / Journal of Organometallic Chemistry 689 (2004) 224–237
227
Scheme 4.
Scheme 5.
lengths and angles are also given in Tables 1 and 2, re-
spectively and summary of crystal data is shown in
Table 3.
The crystal structure of 3f contains two ligands and
one metal center in an asymmetric unit. Two tridentate
NO2 donor units occupy an approximately meridional
arrangement around titanium, with its overall coordi-
nation number 6 to yield a distorted octahedral TiN2O4
coordination sphere (Fig. 1). The four oxygens of two
different ligands form an equatorial plane with maxi-
N(1)–Ti–N(2) 176.6°). A similar coordinating behavior
has been observed by Doherty et al. [12] for the related
ligand, MeC(O)CHC(Me)N(CH2CH2O). The potential
symmetry of 3f may be broken by the arrangement of
two coordinating ligands which are arrayed in the same
direction.
In unit-cell of the corresponding dissymmetric b-ke-
toiminate compound, 3k, it contains a pair of unusual
crystallographcally independent molecules (A and B),
which are structural isomers to each other (Fig. 2). In
both complexes (A and B), the four oxygens of two dif-
ferent ligands form equatorial plane with the maximum
ꢀ
mum deviation of 0.345 A and two N atoms occupy the
ꢀ
axial positions (Ti–N(1) 2.185 A, Ti–N(2) 2.173 A,
ꢀ

228
S. Lim et al. / Journal of Organometallic Chemistry 689 (2004) 224–237
ꢀ
deviation of 0.353 and 0.348 A, and two N atoms oc-
cupy the axial positions [molecule A: Ti(1)–N(1) 2.155
ꢀ
ꢀ
A, Ti(1)–N(2) 2.168 A, N(1)–Ti(1)–N(2) 172.6°; mole-
ꢀ
cule B: Ti(2)–N(3) 2.154 A, N(1)–Ti(2)–N(2) 177.4°],
respectively. A remarkable conformational difference of
two molecules in 3k is an arrangement of two coordi-
nating ligands. In molecule A, the two ligands around
metal center array in the same direction similar to that
of 3f. However, molecule B has a crystallographic 2-fold
axis. As a consequence of this symmetry, each t-butyl
group separates as far as possible. This effect is related
to the greater distortion of the molecule A than that of
molecule B, which is coordinated fairly symmetrically to
the ligands.
The distortions from regular octahedral symmetry
are reflected by the considerable variation of bond
lengths and angles, which occur about the titanium
atom in each complex. The repulsive interaction be-
tween two t-butyl groups of molecule B in 3k produces a
marked distortion from the regular geometry: the O(4)–
Ti(1)–N(2) angle is increased to 97.02(9)°. In each
complex (Figs. 1 and 2), the axial positions are likely
occupied by two nitrogen donors, but the distances of
Ti–N bonds are quite different. For examples, each of
Fig. 1. Crystal structure of 3f with atom-numbering scheme. Dis-
placement ellipsoids are drawn at 30% probability level and H atoms
have been omitted for clarity.
ꢀ
the titanium to nitrogen bonds (2.154–2.168 A) in 3k is
ꢀ
marginally shorter than the mean (2.185 A, with stan-
Fig. 2. Crystal structures of two isomer forms (A and B) of 3k with atom-numbering scheme. Displacement ellipsoids are drawn at 30% probability
level and H atoms have been omitted for clarity.
Table 1
ꢀ
Selected bond lengths (A) and angles (°) for 3f
Ti–O(1)
Ti–O(4)
1.950(2)
1.848(2)
1.300(3)
1.403(4)
Ti–O(2)
Ti–N(1)
1.851(2)
2.185(2)
1.315(3)
1.350(5)
Ti–O(3)
Ti–N(2)
1.962(2)
2.173(2)
1.370(5)
1.426(4)
N(1)–C(4)
C(12)–C(13)
N(2)–C(13)
C(2)–C(3)
C(11)–C(12)
C(3)–C(4)
O(4)–Ti–O(2)
O(4)–Ti–O(3)
O(4)–Ti–N(2)
O(3)–Ti–N(2)
O(1)–Ti–N(1)
95.31(10)
158.77(9)
77.31(8)
81.48(9)
81.69(8)
O(4)–Ti–O(1)
O(2)–Ti–O(3)
O(2)–Ti–N(2)
O(4)–Ti–N(1)
O(3)–Ti–N(1)
93.42(10)
91.17(10)
105.24(8)
104.89(8)
96.25(9)
O(2)–Ti–O(1)
O(1)–Ti–O(3)
O(1)–Ti–N(2)
O(2)–Ti–N(1)
N(2)–Ti–N(1)
158.68(8)
87.63(10)
95.63(8)
77.29(8)
176.58(9)

S. Lim et al. / Journal of Organometallic Chemistry 689 (2004) 224–237
229
Table 2
Selected bond lengths (A) and angles (°) for 3k
ꢀ
Ti(1)–O(1)
Ti(1)–O(2)
Ti(2)–O(5)
Ti(2)–O(6)
N(1)–C(5)
C(5)–C(6)
C(17)–C(18)
1.842(2)
1.936(2)
1.842(2)
1.939(2)
1.305(4)
1.416(5)
1.342(5)
Ti(1)–O(3)
Ti(1)–N(1)
Ti(2)–O(5A)
Ti(2)–N(3A)
N(2)–C(16)
C(6)–C(7)
1.843(2)
2.155(2)
1.842(2)
2.154(2)
1.294(4)
1.356(5)
1.413(4)
Ti(1)–O(4)
Ti(1)–N(2)
Ti(2)–O(6A)
Ti(2)–N(3)
N(3)–C(27)
C(16)–C(17)
C(28)–C(29)
1.934(2)
2.168(2)
1.939(3)
2.154(2)
1.302(4)
1.417(4)
1.352(5)
C(27)–C(28)
O(1)–Ti(1)–O(3)
O(1)–Ti(1)–O(2)
O(1)–Ti(1)–N(1)
O(2)–Ti(1)–N(1)
O(4)–Ti(1)–N(2)
O(5)–Ti(2)–O(5A)
O(5)–Ti(2)–O(6)
O(5)–Ti(2)–N(3A)
O(6)–Ti(2)–N(3A)
O(6A)–Ti(2)–N(3)
94.72(11)
158.36(10)
77.54(10)
81.00(9)
O(1)–Ti(1)–O(4)
O(3)–Ti(1)–O(2)
O(3)–Ti(1)–N(1)
O(1)–Ti(1)–N(2)
O(2)–Ti(1)–N(2)
O(5)–Ti(2)–O(6A)
O(5A)–Ti(2)–O(6)
O(5A)–Ti(2)–N(3A)
O(5)–Ti(2)–N(3)
O(6)–Ti(2)–N(3)
90.44(12)
93.40(11)
104.90(10)
109.47(10)
91.87(9)
O(3)–Ti(1)–O(4)
O(4)–Ti(1)–O(2)
O(4)–Ti(1)–N(1)
O(3)–Ti(1)–N(2)
N(1)–Ti(1)–N(2)
O(5A)–Ti(2)–O(6A)
O(6A)–Ti(2)–O(6)
O(6A)–Ti(2)–N(3A)
O(5A)–Ti(2)–N(3)
N(3A)–Ti(2)–N(3)
158.08(10)
89.45(12)
97.02(9)
77.40(9)
80.79(9)
172.58(10)
158.28(9)
87.77(19)
81.23(9)
96.82(16)
158.28(9)
100.88(10)
100.48(10)
100.48(10)
91.59(12)
91.59(12)
77.54(9)
77.54(9)
81.23(9)
100.88(10)
177.66(13)
Table 3
Summary of crystal data and structure refinement for compounds 3f and 3k
3f
3k
Emperical formula
Formula weight
Temperature (K)
C18H30N2O4Ti
386.34
298(2)
C22H38N2O4Ti
442.44
298(2)
ꢀ
Wavelength (A)
0.71073
orthorhombic
P212121
0.71073
monoclinic
P2=n
Crystal system
Space group
Unit cell dimensions
ꢀ
a (A)
10.2436(7)
12.4074(9)
12.9406(10)
13.4335(10)
22.6426(16)
90
ꢀ
b (A)
ꢀ
c (A)
15.7268(11)
90
a (°)
b (°)
c (°)
90
90
99.105(2)
90
3
ꢀ
Volume (A )
1998.8(2)
4
1.284
3886.5(5)
6
1.134
Z
Density (calculated) (Mg/m3)
Absorption coefficient (mmꢀ1
F ð000Þ
)
0.451
824
0.356
1428
Crystal size (mm3)
0.30 ꢂ 0.40 ꢂ 0.50
2.09–28.28
13, 8, 20
0.30 ꢂ 0.40 ꢂ 0.50
1.52–28.30
16, 17, 30
24917
Theta range for data collection (°)
Max index range h; k; l
Reflections collected
13219
Independent reflections
Completeness to theta
Absorption correction
Refinement method
4858 [Rint ¼ 0:0445]
28.28 °C, 99.6%
None
9373 [Rint ¼ 0:0551]
28.30°C, 96.9%
None
Full-matrix least-squares on F2
Data/restraints/parameters
Goodness-of-fit on F2
4858/0/227
1.042
9373/0/423
1.058
Final R indices [I > 2rðIÞ]
R indices (all data)
R1 ¼ 0:0434, wR2 ¼ 0:1126
R1 ¼ 0:0641, wR2 ¼ 0:1235
0.55(3)
R1 ¼ 0:0614, wR2 ¼ 0:1799
R1 ¼ 0:1267, wR2 ¼ 0:2107
Absolute structure parameter
Largest diff. peak and hole
ꢀ3
ꢀ3
ꢀ
ꢀ
0.291 and )0.231 e A
0.356 and )0.292e A
ꢀ
dards deviation 0.015 A) of 13 such bonds taken from
ꢀ
the X-ray literature, while those (2.185 and 2.173 A) of
3f are comparable to the literature values [15].
It is interesting that steric bulkiness of alkyl groups in
the five-membered ring does not affect the bite angles of
the chelate rings. The six-membered chleate rings are
nearly planar and two rings are close to perpendicular
with diheral angles of 89.31(8) (3f), 89.64(8) (3k, Ti(1)),
and 89.86(8)° (3k, Ti(2)), respectively. The bonding in
the six-membered rings is localized and can be described

230
S. Lim et al. / Journal of Organometallic Chemistry 689 (2004) 224–237
as a N-hydroxyalkylimine-enolate. The C–N bond dis-
ꢀ
tances (1.294–1.315 A) in each complex are comparable
to the distances of such bonds in the ketoiminate com-
plexes taken from the X-ray literature [12,16].
The locality of bonding within the ketoiminate ligand
is supported by the differences in the two C–C bond
lengths in the six-membered ring of 0.033 (3f), 0.075,
ꢀ
0.060 (3k, Ti(1)), and 0.061 A (3k, Ti(2)), which are
substantially larger than the comparable differences in
the bis(iminate) ([Zr{MeC(NPh)CH(NPh)Me}2Cl2],
ꢀ
0.005 A) [16] and b-diketonate complexes ([Ti{Me-
ꢀ
C(O)CH(O)Me}(O-iPr2)3]2, 0.003 A) [13], respectively.
In addition, the titanium ketoiminate bond length is
considerably longer than its alkoxide counterparts (3f:
1.950(2), 1.962(2) vs. 1.848(2), 1.851(2); 3k: Ti(1)
1.934(2), 1.936(2) vs. 1.842(2), 1.843(2), Ti(2) 1.939(2)
vs. 1.842(2)). However, these values are not as marked
as those observed in the b-diketonate complex ([Ti{MeC
ꢀ
(O)CH(O)Me}(O-iPr2)3]2, 2.073(4) vs. 1.782(4) A) [13].
These results clearly reflect the different p-donor ability
of OR compared with NR2 [12,17]. In each structure,
two terdentate b-ketoiminate ligands occupy a meridi-
onal coordination environment.
In 3k, thermal disorder of carbon atoms in five-mem-
bered rings are monitored [C(2):Cð20Þ ¼ 69:31, C(13):
Cð130Þ ¼ 59:41, C(24):Cð240Þ ¼ 55:45] and these prevent
meaningful discussion of the ligand conformation.
Fig. 3. Dynamic and isothermal (200 °C) TGA thermodiagrams of 2b.
2.4. Thermal properties of [Ti(N-alkoxy-b-ketoimi-
nate)(O-iPr)2]2 and [Ti(N-alkoxy-b-ketoiminate)2]
Thermal properties of [Ti(N-alkoxy-b-ketoimi-
nate)(O-iPr)2]2 and [Ti(N-alkoxy-b-ketoiminate)2] are
characterized by dynamic and isothermal TGA. In
Fig. 3, 2b shows two different regions in the dynamic
TGA and constant decrease of weight is observed in the
isothermal TGA (200 °C). Considering that dimer
complexes undergo disproportional rearrangement (vide
supra), this behavior can be explained as follows; as
temperature goes up, dimer disproportionally rear-
ranges to Ti(O-iPr)4 and [Ti(N-alkoxy-b-ketoiminate)2]
at first and then evaporation of Ti(O-iPr)4 occurs at the
lower temperature while [Ti(N-alkoxy-b-ketoiminate)2]
vaporizes at the higher temperature. In the isothermal
TGA experiment, a constant slope after 20 min is
maintained, which indicates only one compound, pos-
sibly [Ti(N-alkoxy-b-ketoiminate)2], vaporizes. Even
though the volatility of 2b is not very good (in dynamic
TGA, the amount of residue at 550 °C is 23%), constant
vapor pressure at 200 °C leads to the LS MOCVD ex-
periments using laboratory-made MOCVD apparatus.
Detailed description of this apparatus can be obtained
elsewhere [11j]. As shown in Fig. 4, 2c shows higher
deposition rate than commercially available Ti(mpd)
(thd)2 (Ashai Denka Chemical Co.). Since this may be
due to high volatility of Ti(O-iPr)4, thermal character-
Fig. 4. Deposition rate of TiO2 layer with several Ti precursors as a
function of deposition temperature (deposition conditions(2b, 2c,
Ti(mpd)(thd)2) solvent: n-butyl acetate (0.05 M, 5 ml), n-butyl acetate
(0.05 M, 3 ml), MeOH (0.05 M, 5 ml); temperature of evaporation:
260, 230, 260 °C; temperature of substrate: 400–500 °C).
istics of [Ti(N-alkoxy-b-ketoiminate)2] were investi-
gated. The results are summarized in Table 4. Melting
points of these complexes are generally high around 200
°C and introduction of alkyl substituents on the alkoxy
backbones tends to lower vaporization temperature and

S. Lim et al. / Journal of Organometallic Chemistry 689 (2004) 224–237
231
Table 4
Thermal characteristics of [Ti(N-alkoxy-b-ketoiminate)2]
tautomer. Two terdentate b-ketoiminate ligands coor-
dinate meridianally and they are perpendicular to each
other. Thermal characteristics determined by TGA and
DSC show that dimeric complexes undergo dispropor-
tionation, evaporation of Ti(O-iPr)4 and [Ti(N-
alkoxy-b-ketoiminate)2] successively and volatility of
monomeric ones depends on the substituents on the
backbone of alkoxy part.
Complex
Melting
point (°C)
Evaporation
temperature (°C)
Residue (%)
3a
3b
3c
3d
3e
3h
3i
199
199
60
323
290
295
290
270
285
295
290
8
0.5
3.3
13.7
26.6
8.3
3.6
0.5
218
178
185
175
220
3k
4. Experimental
All manipulations were performed under a nitrogen
atmosphere using standard Schlenk techniques unless
stated otherwise. The solvents were reagent grade and
were distilled under nitrogen over appropriate drying
agents prior to use. Reagent grade chemicals were
purchased from Aldrich Chemical Co., Inc. and Strem
Chemicals Inc. and used without further purification
unless stated otherwise. N-hydroxyalkyl-b-ketoimines,
CH3C(O)CH2C(NCH2CHR0OH)CH3 (R0 ¼ H, 1a;
R0 ¼ Me, 1b) and Ti[CH3C(O)CH2C(NCH2CHR0OH)
CH3]2 (R0 ¼ H, 3a; R0 ¼ Me, 3b) were prepared ac-
cording to published procedures [12]. 1H and 13C
NMR spectra were recorded by using 5 mm tube on a
Bruker AC-250 (VT NMR experiments, 250.133 and
62.896 MHz, respectively) or Varian Gemini 2000 (RT
NMR experiments, 199.976 and 50.289 MHz, respec-
tively) FT NMR spectrometer and were referenced to
tetramethylsilane (TMS). Variable temperature NMR
spectra were obtained using toluene-d8 as a solvent in
the range of 213–353 K. Elemental analyses were per-
formed with EA-1110 (CE Instruments) in the Inha
University.
Thermal analysis (TGA and DSC) was done with
NETZSCH STA 449C (1 atm and 1.3 mbar, heating
rate ¼ 10 °C/min, N2 flow rate ¼ 20 ml/min) in Samsung
Advanced Institute of Technology.
A laboratory-made liquid delivery MOCVD appa-
ratus was employed for the testing of the synthesized Ti
precursors in the deposition of TiO2 thin films. The
detailed description of apparatus and experimental
conditions were given elsewhere [11j].
amount of residue. Methyl group on the carbon next to
N leads to higher vaporization temperature and residue
amount than methyl group on the carbon next to O.
Residue of 3a is much less than that of 3e while melting
point and vaporization temperature of 3a are lower than
those of 3e. This indicates that 6,5 chelate rings (3a) lead
to better thermal stability and higher volatility than 6,6
ones (3e). Weight decrease rates of 3a and 3b were
measured by isothermal TGA at 150, 200, and 250 °C
and it is found that these are less than that of com-
mercially available Ti(mpd)(thd)2. This represents en-
hanced compatibility with not much volatile precursors
of barium and strontium in the fabrication of BST thin
films. Performance of these complexes as precursors of
LSMOCVD was already reported elsewhere [5].
2.5. Other properties of [Ti(N-alkoxy-b-ketoiminate)2]
These complexes showed much improved chemical
stability toward hydrolysis. After the exposure to air for
3 months, these complexes do not show any extra peaks
in NMR spectra. 3a is slightly soluble in n-butyl acetate,
while 3b shows much higher solubility in the same sol-
vent (0.08 M in n-butyl acetate and 0.4 M in THF).
However, 3b shows ligand dissociation in MeOH, which
should be improved for the application to LSMOCVD.
3. Conclusions
Various N-alkoxy-b-ketoimine ligands have been
prepared with high yields and reactions between these
ligands and Ti(O-iPr)4 resulted in dimeric [Ti(O-iPr)2(N-
alkoxy-b-ketoiminate)]2 complexes or monomeric [Ti(N-
alkoxy-b-ketoiminate)2] ones depending on the amount
of ligands. Dimer complexes undergo disproportional
rearrangement to produce Ti(O-iPr)4 and [Ti(N-alkoxy-
b-ketoiminate)2]. The mechanism of this behavior is too
complicated but it may include the dissociation and
recoordination of ligands. Crystal structures of 3f and
3k show that b-ketoiminate ligands appear to coordi-
nate as a b-imino enolate, rather than as its b-ketoamide
4.1. X-ray data collection, structure determination and
refinement
Crystals suitable for X-ray diffraction were moun-
ted on a Siemens SMART diffractometer equipped
with a graphite monochromated Mo Ka (k ¼ 0:71073
ꢀ
A) radiation source and a CCD detector and 45
frames of two-dimensional diffraction images were
collected and processed to deduce the cell parameter
and orientation matrix. A total of 1271 frames of two-
dimensional diffraction images were collected, each of
which was measured for 10 s. The frame data were

232
S. Lim et al. / Journal of Organometallic Chemistry 689 (2004) 224–237
processed to give structure factors by the program
SAINT [18]. The intensity data were corrected for
Lorentz and polarization effects. The structures were
solved by a combination of the direct method and the
difference Fourier methods provided by the program
package SHELXTL [19], and refined using a full-matrix
least-square against F 2 for all data. All the non-H
atoms were refined anisotropically. All hydrogen at-
oms were included in calculated positions with iso-
tropic thermal parameters 1.2 times those of attached
atoms.
5.4. 2-N-(1,1-dimethyl-2-Hydroxyethylimino)-4-penta-
none (1d), CH3C(O)CHC(HNC(CH3)2CH2OH)CH3
2-Amino-2-methyl-1-propanol (13.35 g, 149.8 mmol)
and 2,4-pentanedione (10.0 g, 99.88 mmol) were dis-
solved in 100 ml of CH3OH with 0.51 g of HCOOH and
the mixture was refluxed for a day while stirring vigor-
ously. The solvent was removed under reduced pressure
and the solid was purified with recrystallization using
200 ml of ethylether at room temperature. Yield: 10.95 g
(64%).
1H NMR (CDCl3): 11.32(br s, 1H, C(O)CH@
C(NH)), 4.88(s, 1H, C(O)CH@C(NH)), 4.35(br s, 1H,
HNC(Me)2CH2OH), 3.53(s, 2H, NC(Me)2CH2OH),
2.04(s, 3H, CH ¼ C(N)CH3), 1.94(s, 3H, CH3C(O)),
1.33(s, 6H, (HNC(CH3)2CH2OH). 13C NMR (CDCl3):
194.24(s, CH3C(O)CH), 163.88(s, CH@C(NH)CH3),
97.07(s, C(O)CH@(NH)), 70.93(s, NHC(Me)2CH2OH),
56.44(s, HNC(Me)2CH2OH), 28.67(s, CH@C(NH)
CH3), 25.72(s, HNC(CH3)2CH2OH), 20.96(s, CH3
C(O)CH). Anal. Calc. for C9H17NO2: C, 63.13; H,
10.01; N, 8.18. Found: C, 63.38; H, 10.57; N, 8.23%.
5. Ligand synthesis
5.1. 2-N-(2-Hydroxyethylimino)-4-pentanone (1a),
CH3C(O)CHC(HNCH2CH2OH)CH3
Yield: 12.88 g (90%).
5.2. 2-N-(2-Hydroxy-2-methylethylimino)-4-pentanone
(1b), CH3C(O)CHC(HNCH2CH(CH3)OH)CH3
5.5. 2-N-(3-Hydroxypropylimino)-4-pentanone (1e),
CH3C(O)CHC(HNCH2CH2CH2OH)CH3
Yield: 29.83 g (95%).
The same procedure as described in Section 5.3 was
adopted except 3-amino-1-propanol (9.0 g, 119.8 mmol)
and 2,4-pentanedione (10.0 g, 99.88 mmol). The product
was purified with a silica column, eluting with ethylac-
etate/hexane (80%). Yield: 14.00 g (93%).
5.3. 2-N-(2-Hydroxy-1-methylethylimino)-4-pentanone
(1c), CH3C(O)CHC(HNCH(CH3)CH2OH)CH3
D/L-2-Amino-1-propanol (10.0 g, 13.31 mmol) and
1H NMR (CDCl3): 10.86(br s, 1H, C(O)CH@
C(NH)), 4.96(s, 1H, C(O)CH@C(NH)), 3.74 (t, 2H,
NCH2CH2CH2OH), 3.38(dt, 2H, NCH2 CH2CH2OH),
2.67(br s, 1H, NCH2CH2CH2OH), 1.98 (s, 3H, CH@C
(NH)CH3), 1.94(s, 3H, CH3C(O)CH), 1.83(m, 2H,
NCH2CH2CH2OH). 13C NMR (CDCl3): 194.94(s, CH3
C(O)CH), 163.80(s, CH@C(NH)CH3), 95.46(s, C(O)
CH@C(NH)), 59.62(s, HNCH2CH2 CH2OH), 39.92(s,
HNCH2CH2CH2OH), 32.85(s, HN CH2CH2CH2OH),
28.85(s, CH3C(O)CH), 18.99(s, CH@C(NH)CH3). Anal.
Calc. for C8H15NO2: C, 61.12; H, 9.62; N, 8.91. Found:
C, 60.90; H, 9.94; N, 9.09%.
2,4-pentanedione (11.11 g, 111.0 mmol) were dissolved
in 100 ml of CH3OH with 0.51 g of HCOOH and the
mixture was refluxed for a day while stirring vigorously.
After cooling down to room temperature, the solvent
was removed under reduced pressure. The product was
extracted to the organic layer with H2O/CH2Cl2 (20/150
ml) mixture. The product remained in the aqueous layer
was extracted with 100 ml of CH2Cl2 three times. After
the solution was dried with MgSO4, the solvent was
removed under reduced pressure. The product was pu-
rified with a silica column, eluting with ethylacetate.
Yield: 15.52 g (89%).
1H NMR (CDCl3): 10.8(br s, 1H, C(O)CH@C(NH)),
4.93(s, 1H, C(O)CH@C(NH)), 3.72(m, 1H, HNCH
(Me)CH2OH), 3.62(dd, 1H, NCHMeCHaHbOH), 3.52
(dd, 1H, NCHMeCHaHbOH), 3.35(br s, 1H, NCH
(Me)CH2OH), 1.98(s, 3H, CH@C(NH)CH3), 1.97(s,
3H, CH3C(O)CH), 1.18(d, 3H, HNCH(CH3)CH2OH).
13C NMR (CDCl3): 192.45(s, CH3C(O)CH), 160.69(s,
CH@C(NH)CH3), 93.19(s, C(O)CH@C(NH)), 64.57(s,
HNCH(Me)CH2OH), 48.45(s, HNCH(Me)CH2OH),
26.19(s, CH3C(O)CH), 16.69(s, CH@C(NH)CH3), 15.7
(s, NHCH(CH3)CH2OH). Anal. Calc. for C8H15NO2:
C, 61.12; H, 9.62; N, 8.92. Found: C, 61.15; H, 10.76; N,
9.07%.
5.6. 2-N-(2-Hydroxy-1-ethylethylimino)-4-pentanone
(1f), CH3C(O)CHC(HNCH(CH2CH3)CH2OH)CH3
The same procedure as described in Section 5.3 was
adopted except 2-amino-1-butanol (11.0 g, 119.8 mmol)
and 2,4-pentanedione (10.0 g, 99.88 mmol). The product
was purified with a silica column, eluting with ethylac-
etate/hexane (80%). Yield: 14.71 g (86%).
1H NMR (CDCl3): 10.85(br d, 1H, C(O)CH@
C(NH)), 4.96(s, 1H, C(O)CH@C(NH)), 3.66–3.55
(m, 1H, HNCH(Et)CH2OH), 3.66–3.55(m, 1H, NCH(Et)
CHaHbOH), 3.25(br s, 1H, NCH(Et) CH2OH), 2.06(s,

S. Lim et al. / Journal of Organometallic Chemistry 689 (2004) 224–237
233
3H, CH@C(NH)CH3), 1.99(s, 3H, CH3C(O)CH),
1.56(m, 3H, HNCH(CH2CH3)CH2OH), 0.95(t, 7.4 Hz,
HNCH(CH2CH3)CH2OH). 13C NMR (CDCl3): 195.15
(s, CH3C(O)CH), 163.86(s, CH@C(NH)CH3), 95.87(s,
C(O)CH@C(NH)), 65.91(s, HNCH(Et)CH2 OH), 57.23
(s, HNCH(Et)CH2OH), 28.90(s, CH3C (O)CH), 25.54(s,
CH@C(NH)CH3), 19.66(s, NHCH (CH2CH3)CH2OH),
10.56(s, NHCH(CH2CH3)CH2 OH). Anal. Calc. for
C9H17NO2: C, 63.13; H, 10.01; N, 8.18. Found: C,
63.41; H, 10.23; N, 8.12%.
1H, HNCH2CHMeOH), 3.42(br s, 1H, NCH2CH2OH),
3
3.22(m, 2H, HNCH2CHMeOH), 2.70 (h, JHH ¼ 7.00
3
Hz, 1H, HNCCHMe2), 2.42 (h, JHH ¼ 7.00 Hz, 1H,
3
Me2CHC(O)CH), 1.23 (d, JHH ¼ 6.00 Hz,, 3H, NCH2
3
CH(CH3)OH), 1.10 (d, JHH ¼ 7.00 Hz, 6H, HNCCH
3
(CH3)2), 1.05 (d, JHH ¼ 7.00 Hz, 6H, (CH3)2CHC(O)
CH). 13C NMR (CDCl3): 200.82(s, Me2CHC(O)CH),
171.90(s, HNCCHMe2), 86.42(s, C(O)CH@CN), 65.13
(s, NCH2CHMeOH), 47.92(s, HNCH2CHMeOH), 38.12
(s, Me2CHC(O)CH), 26.85(s, HNCCHMe2), 19.56(s,
HNCCH(CaH3)(CbH3)), 19.47(s, HNCCH(CaH3)(CbH3)),
19.20(s, NCH2 CH(HH3)OH), 18.27(s, (CH3)2CHC(O)
CH). Anal. Calc. for C12H23NO2: C, 67.57; H, 10.87; N,
6.56. Found: C, 67.44; H, 11.33; N, 6.48%.
5.7. 2,6-Dimethyl-3-N-(2-hydroxyethylimino)-5-hepta-
none (1g), (CH3)2CHC(O)CHC(HNCH2CH2OH)
CH(CH3)2
Ethanolamine(4.30 g, 70.4 mmol) and 2,6-dimethyl-
3,5-heptanedione (10.0 g, 64.0 mmol) were dissolved in
180 ml of benzene with 0.63 g of H2SO4 0.63 g (1 drop).
The mixture in a Dean and Stark apparatus was refluxed
for 6 h while stirring vigorously. After cooling down to
room temperature, the solvent was removed under re-
duced pressure. The product was extracted to the or-
ganic layer with H2O/benzene (20/200 ml) mixture. The
product remained in the aqueous layer was extracted
with 100 ml of benzene three times. After the solution
was dried with MgSO4, the solvent was removed under
reduced pressure. The product was purified by recrys-
tallization in 100 ml of n-hexane at )20 °C. Yield: 10.72
g (84%).
5.9. 2,6-Dimethyl-3-N-(2-hydroxy-1-methylethylimino)-
5-heptanone (1i), (CH3)2CHC(O)CHC(HNCH(CH3)
CH2OH)(CH(CH3)2)
The same procedure as described in Section 5.6 was
adopted except D/L-2-amino-1-propanol (7.21 g, 95.99
mmol) and 2,6-dimethyl-3,5-heptanedione (10.0 g, 64.0
mmol). The product was purified with a silica column,
eluting with ethylacetate/hexane (80%). Yield: 11.65 g
(81%).
1H NMR (CDCl3): 11.12(br d, 1H, C(O)CH ¼
C(NHCH(Me))), 5.03(s, 1H, C(O)CH@C(NH)), 3.79(m,
1H, HNCH(Me)CH2OH), 3.59(br m, 2H, NCHMeCH2
OH) 2.89(br s, 1H, NCH(Me)CH2OH), 2.78(m, 1H,
CH@C(NH)CH (CH3)2), 2.45(m, 1H, (CH3)2 CH
C(O)CH), 1.22(d, 3H, NCH(CH3)CH2OH), 1.15(d, 6H,
CH@C(N)CH(CH3)2), 1.07(dd, 6H(CH3)2CHC (O)).
13C NMR (CDCl3): 202.57 (s, Me2CH C(O)CH),
173.73(s, HNCCHMe2), 88.24(s, C(O) CH@CN), 67.28
(s, HNCHMeCH2OH), 50.00(s, NCH MeCH2OH),
39.93(s, Me2CHC(O)CH), 28.75(s, HNC CHMe2),
22.03(s, HNCCH(CaH3)(CbH3)), 21.72(s, HN CCH
(CaH3)(CbH3)), 20.16(s, (CH3)2CHC (O)CH), 18.90(s,
NCH(CH3)CH2OH). Anal. Calc. for C12H23NO2: C,
67.57; H, 10.87; N, 6.56. Found: C, 67.44; H, 11.70; N,
6.52%.
1H NMR (CDCl3): 11.20(br s, 1H, C(O)CH@CNH),
3
5.05(s, 1H, C(O)CH@CNH), 3.79 (t, JHH ¼ 5.60 Hz,
3
2H, HNCH2CH2OH), 3.44 (dt, JHH ¼ 5.60 Hz, 5.40
3
Hz, 2H, HNCH2CH2OH), 2.73 (h, JHH ¼ 7.00 Hz, 1H,
HNCCH Me2), 2.45 (h, 3JHH ¼ 7.00 Hz, 1H,
Me2CHC(O)CH), 2.35(br s, 1H, NCH2CH2OH), 1.14
3
(d, JHH ¼ 7.00 Hz, 6H, HNCCH(CH3)2), 1.08 (d,
3JHH ¼ 7.00 Hz, 6H, (CH3)2CHC(O)CH). 13C NMR
(CDCl3): 200.86(s, Me2CHC(O)CH), 172.13(s, HNC
CHMe2), 86.45(s, C(O)CH@CNH), 59.91(s, NCH2
CH2OH), 42.75(s, NCH2CH2OH), 38.09(s, Me2CH-
C(O)CH), 26.91(s, HNCCHMe2), 19.52(s, HNCCH(C
H3)2), 18.27(s, (CH3)2CHC(O)CH). Anal. Calc. for
C11H21NO2: C, 66.29; H, 10.62; N, 7.03. Found: C,
66.10; H, 10.84; N, 7.09%.
5.10. 5,5-Dimethyl-2-N-(2-hydroxyethylimino)-4-hexa-
none (1j), (CH3)3CC(O)CHC(HNCH2CH2OH)CH3
5.8. 2,6-Dimethyl-3-N-(2-hydroxy-2-methylethylimino)-
The same procedure as described in Section 5.3
was adopted except ethanolamine(1.30 g, 21.3 mmol)
and 2,2-dimethyl-3,5-hexanedione (2.02 g, 14.2 mmol).
The product was purified with a silica column, elut-
ing with ethylacetate/hexane (80%). Yield: 1.56 g
(59%).
5-heptanone
CH(CH3)OH)(CH(CH3)2)
(1h),
(CH3)2CHC(O)CHC(HNCH2
The same procedure as described in Section 5.6 was
adopted except 1-amino-2-propanol (5.77 g, 76.8 mmol)
and 2,6-dimethyl-3,5-heptanedione (10.0 g, 64.0 mmol).
The product was purified with a silica column, eluting
with ethylacetate/hexane (80%). Yield: 11.61 g (85%).
1H NMR (CDCl3): 11.21(br s, 1H, C(O)CH ¼ CNH),
1H NMR (CDCl3): 11.04(br s, 1H, C(O)CH@CNH),
3
5.14(s, 1H, C(O)CH@CNH), 3.76 (t, JHH ¼ 5.60 Hz,
3
2H, HNCH2CH2OH), 3.39 (dt, JHH ¼ 5.60, 5.40 Hz,
2H, HNCH2CH2OH), 3.11(br s, 1H, HNCH2CH2OH),
1.97(s, 3H, HNCCH3), 1.11(s, 9H, (CH3)3CC(O)CH).
3
5.01(s, 1H, C(O)CH@CNH), 3.95 (q, JHH ¼ 6.00 Hz,

234
S. Lim et al. / Journal of Organometallic Chemistry 689 (2004) 224–237
13C NMR (CDCl3): 202.39(s, Me3CC(O)CH), 162.54(s,
HNCCH3), 89.32(s, C(O)CH@CNH), 60.02(s, NCH2
CH2OH), 43.63(s, HNCH2CH2OH), 39.58(s, (CH3)3
CC(O)CH), 26.25(s, (CH3)3CC(O)CH), 17.82(s, HNC
CH3). Anal. Calc. for C10H19NO2: C, 64.83; H, 10.34; N,
7.56. Found: C, 64.76; H, 10.82; N, 7.60%.
Anal. Calc. for C26H50N2O8Ti2: C, 50.86; H, 8.21; N,
4.56. Found: C, 50.54; H, 8.24; N, 4.65%.
6.1.2. [Ti(CH3C(O)CHC(NCH2CH(Me)O)CH3)(O-
iPr)2]2 (2b)
The same procedure as described in Section 6.1.1 was
adopted except ligand 1b (2.76 g, 17.59 mmol). Recrys-
tallization in mixed solvents (40 ml of n-hexane/5 ml of
CH2Cl2) at )20 °C produced yellow solid. Yield: 5.42 g
(96%).
5.11. 5,5-Dimethyl-2-N-(2-hydroxy-2-methylethylimino)-
4-hexanone (1k), (CH3)3CC(O)CHC(HNCH2CH
(CH3)OH)CH3
1H NMR (CDCl3): 5.24(s, 2H, CH), 4.72(m, 2H,
NCH2CH(Me)O), 4.60(br m, 4H, OCH(Me)2), 3.96(dd,
2H, NCHaHbCH(Me)O), 3.43(dd, 2H, NCHaHbCH(-
Me)O), 1.98(s, 6H, C(N)CH3), 1.96(s, 6H, CH3C(O)),
1.20(d, 24H, OCH(CH3)2). 13C NMR (CDCl3): 176.30(s,
CH3C(O), 169.80(s, C(N)CH3)), 102.89(s, C(O)CHC
(N)), 77.86(s, NCH2CH(Me)O), 75.86(s, OCH(CH3)2),
65.65(s, NCH2CH(Me)O), 26.06(s, OCH(CH3)2), 24.41
(s, C(N)CH3), 22.66(s, CH3C(O)), 22.10(s, NCH2CH
(CH3)O).
The same procedure as described in Section 5.3 was
adopted except 1-amino-2-propanol (6.34 g, 84.38
mmol) and 2,2-dimethyl-3,5-hexanedione (2.02 g, 14.2
mmol). Ethanol was employed as a solvent. The product
was purified with recrystallization in 80 ml of n-hexane
at )20 °C. Yield: 10.93 g (78%).
1H NMR (CDCl3): 11.04(br s, 1H, C(O)CH@CNH),
5.13(s, 1H, C(O)CH@CNH), 3.96(m, 1H, HNCH2
CH(Me)OH), 3.26 (dd, 1H, HNCHaHbCH(Me)OH),
3.20(dd, 1H, HNCHaHbCH(Me)OH), 3.19 (br s, 1H,
HNCH2CH(Me)OH), 1.96(s, 3H, HNCCH3), 1.23(d,
3H, HNCH2CH(CH3)OH), 1.11(s, 9H, (CH3)3CC(O)
CH). 13C NMR (CDCl3): 204.16(s, Me3CC(O)CH),
164.20(s, HNCCH3), 91.18(s, C(O)CH@CNH), 67.11(s,
NCH2CH(Me)OH), 50.71(s, HNCH2CH(Me)OH),
41.46(s, (CH3)3CC(O)CH), 28.16(s, (CH3)3CC(O)CH),
21.00(s, HNCCH3), 19.77(s, HNCH2CH(CH3)OH).
Anal. Calc. for C11H21NO2: C, 66.29; H, 10.62; N, 7.03.
Found: C, 65.72; H, 11.08; N, 7.12%.
6.1.3. [Ti(CH3C(O)CHC(NCH(Me)CH2O)CH3)(O-
iPr)2]2 (2c)
The same procedure as described in Section 6.1.1 was
adopted except ligand 1c (1.66 g, 10.55 mmol) and Ti(O-
iPr)4 (3.0 g, 10.55 mmol). Removal of solvent under re-
duced pressure at )40 °C produced viscous red liquid.
Yield: 3.18 g (94%).
1H NMR (CDCl3): 5.21(s, 2H, C(O)CHC(N)),
4.62(m, 4H, OCH(Me)2), 4.60(dd, 2H, NCH(Me)CHa
HbO), 4.23(m, 2H, NCH(Me)CH2O), 3.91(dd, 2H,
NCH(Me)CHaHbO), 2.05(s, 6H, C(N)CH3), 1.96(s, 6H,
CH3C(O)), 1.30(d, 6H, NCH(CH3)CH2O), 1.20(d, 24H,
OCH(CH3)2). 13C NMR (CDCl3): 173.6(s, CH3C(O)),
166.1(s, C(N)CH3), 100.6(s, C(O)CHC(N)), 73.9(s,
OCH(Me)2), 73.81(s, NCH(Me)CH2O), 61.89(s, NCH
(Me)CH2O), 23.44(s, OCH(CH3)2), 21.85(s, CH3C(O)),
19.1(s, C(N)CH3), 18.2(s, NCH(CH3)CH2O).
6. Preparation of metal complexes
6.1. Dimeric N-alkoxy-b-ketoiminato titanium diisoprop-
oxide complexes
6.1.1. [Ti(CH3C(O)CHC(NCH2CH2O)CH3)(O-iPr)2]2
(2a)
Ligand 1a (2.52 g, 17.59 mmol) in 25 ml of CH2Cl2
was added dropwise to the solution containing Ti(O-
iPr)4 (5.0 g, 17.59 mmol) in 20 ml of CH2Cl2 over 4 h
via cannular at )78 °C. After the addition was com-
pleted, the solution turned to yellow. The solution was
stirred for one more hour and the solvent was re-
moved at )20 °C. Recrystallization in 40 ml of n-
hexane at )20 °C produced yellow solid. Yield: 4.88 g
(90%).
1H NMR (CDCl3): 5.27(s, 2H, C(O)CHC(N)),
4.65(br m, 4H, OCH), 4.43(t, 4H, NCH2CH2O), 3.84(t,
4H, NCH2CH2O), 1.99(s, 12H, C(N)CH3), 1.95(s, 12H,
CH3C(O)), 1.18(d, 24H, OCH(CH3)2). 13C NMR
(CDCl3): 173.17(s, CH3C(O)CH), 167.18(s, CHC(N)
CH3), 100.15(s, C(O)CHC(N)), 75.24(s, OCH(Me)2),
67.49(s, NCH2CH2O), 56.35(s, NCH2CH2O), 23.36(s,
OCH(CH3)2), 21.88(s, C(N)CH3), 20.12(s, CH3C(O)).
6.1.4. [Ti((CH3)2CH)C(O)CHC(CH(CH3)2)(NCH2
CH2O)(O-iPr)2]2 (2d)
The same procedure as described in Section 6.1.1 was
adopted except ligand 1d (2.10 g, 10.55 mmol) and Ti(O-
iPr)4 (3.0 g, 10.55 mmol). Recrystallization in 25 ml of n-
hexane at )20 °C produced yellow solid. Yield: 3.41 g (89%).
1H NMR (CDCl3): 5.23(s, 2H, C(O)CHC(N)),
4.62(br m, 4H, OCH(Me)2), 4.32(br t, 4H, NCH2
CH2O), 3.84(br t, 4H, NCH2CH2O), 2.89(m, 2H, C(N)
CH(Me)2), 2.41(m, 2H, (Me)2CHC(O)), 1.15(d, 24H,
C(N)CH(CH3)2), 1.14(d, 24H, (CH3)2CHC(O)). 13C
NMR (CDCl3): 182.60(s, (CH3)2CHC(O)), 177.15
(C(N)(CH(CH3)2)), 93.70(s, C(O)CHC(N)), 77.23(s,
OCH(CH3)2), 70.29(s, NCH2CH2O), 56.48(s, NCH2
CH2O), 36.80(s, (CH3)2CHC(O)), 31.46(s, C(N)C(CH
(CH3)2)), 25.88(s, O(CH(CH3)2)), 20.78(s, C(N)(CH
(CH3)2)) 20.78(s, (CH3)2CHC(O)).

S. Lim et al. / Journal of Organometallic Chemistry 689 (2004) 224–237
235
6.1.5. [Ti((CH3)2CH)C(O)CHC(CH(CH3)2)(NCH2
CH(Me)O)(O-iPr)2]2 (2h)
20.35, 20.08, 19.30, 18.35(NCH(CH3)CH2O). Anal.
Calc. for C16H26N2O4Ti: C, 53.64; H, 7.32; N, 7.82.
Found: C, 53.32; H, 7.66; N, 7.79%.
The same procedure as described in Section 6.1.1 was
adopted except ligand 1h (2.25 g, 10.55 mmol) and Ti(O-
iPr)4 (3.0 g, 10.55 mmol). Recrystallization in 20 ml of n-
hexane at )20 °C produced yellow solid. Yield: 3.65 g
(95%).
6.2.4. Ti(CH3C(O)CHC(NC(Me)2CH2O)CH3)2 (3d)
The same procedure as described in Section 6.2.1 was
adopted except ligand 1d (3.01 g, 17.58 mmol) and Ti(O-
iPr)4 (2.50 g, 8.79 mmol). Yield: 3.19 g (94%).
1H NMR (CDCl3): 5.30(s, 2H, C(O)CHC(N)), 4.65(m,
4H, OCH(Me)2), 4.65(m, 2H, NCH2CH(Me)O), 4.02(dd,
2H, NCHaHbCH(Me)O), 3.55(dd, 2H, NCHaHbCH(-
Me)O), 2.89(m, 2H, C(N)CH(Me)2), 2.43(m, 2H,
(Me)2CHC(O)), 1.17(d, 24H, C(N)CH (CH3)2), 1.10(d,
24H, (CH3)2CHC(O)), 1.08(d, 6H, NCH2CH(CH3)O).
13C NMR (CDCl3): 181.10(s, ((CH3)2CH)C(O)), 175.37
(s, C(N)(CH(CH3)2)), 91.51(s, C(O)CHC(N)), 74.65(s,
O(CH(CH3)2)), 73.56(s, NCH2CH(Me)O), 60.92(s, NCH2
CH(Me)O), 34.18(s, (CH3)2CH)C(O)), 28.89(s, C(N)
(CH(CH3)2)), 23.42(s, O(CH(CH3)2)), 19.43(s, NCH2CH
(CH3)O), 18.41(s, C(N)(CH(CaH3)(CbH3)), 18.19(s,
C(N)(CH(CaH3) (CbH3)), 18.13(s, (CH3)2CHC(O)).
1H NMR (CDCl3): 5.13(s, 2H, C(O)CHC(N)), 4.32
(d, 2H, NC(Me)2CHaHbO), 4.01 (d, 2H, NC(Me)2-
CHaHbO), 2.21(s, 6H, C(N)CH3), 1.92(s, 6H,
CH3C(O)), 1.56 (s, 6H, NC(CH3)a(CH3)bCH2O),
1.38(s, 6H, NC(CH3)a(CH3)bCH2O). 13C NMR
(CDCl3): 174.70(s, CH3H(O)), 169.31(s, H(N)CH3),
104.71(s, C(O)HHC(N)), 84.79(s, NH(Me)2CH2O),
71.41(s, NC(Me)2HH2O), 25.69(s, H H3C(O)), 25.1(s,
C(N)HH3), 24.5(s, NCCa H3CbH3CH2O), 24.4(s,
NCCaH3Cb H3CH2O). Anal. Calc. for C18H30N2O4Ti:
C, 55.96; H, 7.83; N, 7.25. Found: C, 55.59; H, 8.22; N,
6.87%.
6.2. Monomeric bis titanium complexes
6.2.5. Ti(CH3C(O)CHC(NCH2CH2CH2O)CH3)2 (3e)
The same procedure as described in Section 6.2.1 was
adopted except ligand 1e (1.11 g, 7.04 mmol) and Ti(O-
iPr)4 (1.0 g, 3.52 mmol). Yield: 1.20 g (95%).
6.2.1. Ti(CH3C(O)CHC(NCH2CH2O)CH3)2 (3a)
Ligand 1a (3.67 g, 25.61 mmol) in 20 ml of CH2Cl2
was added dropwise to the solution containing Ti(O-
iPr)4 (3.31 g, 11.64 mmol) in 25 ml of CH2Cl2 over 4 h
via cannular at room temperature. After the addition
was completed, the solution turned to yellow. The so-
lution was stirred for one more hour and the solvent was
removed under reduced pressure. Recrystallization in 40
ml of n-hexane at )20 °C produced yellow solid. Yield:
3.72 g (95%).
1H NMR (CDCl3): 5.14(s, 2H, C(O)CHC(N)), 4.36(t,
4H, NCH2CH2CH2O), 3.64(t, 4H, NCH2CH2CH2O),
2.07(m, 4H, NCH2CH2CH2O), 2.00(s, 6H, C(N)CH3),
1.90(s, 6H, CH3C(O). 13C NMR (CDCl3): 176.05(s,
CH3C(O)), 168.01(s, C(N)CH3), 103.64(s, C(O)CHC
(N)), 73.23(s, NCH2CH2CH2O), 50.19(s, NCH2CH2
CH2O), 32.34(s, NCH2CH2CH2O), 25.33(s, CH3C(O)),
22.41(s, C(N)CH3). Anal. Calc. for C16H26N2O4Ti: C,
53.64; H, 7.32; N, 7.82. Found: C, 53.33; H, 7.49; N,
7.97%.
6.2.2. Ti(CH3C(O)CHC(NCH2CHMeO)CH3)2 (3b)
The same procedure as described in Section 6.2.1 was
adopted except ligand 1b (11.06 g, 70.36 mmol) and
Ti(O-iPr)4 (10.0 g, 35.18 mmol). Yield: 12.18 g (96%).
6.2.6. Ti(CH3C(O)CHC(NCH(CH2CH3)CH2O)CH3)2
(3f)
The same procedure as described in Section 6.2.1 was
adopted except ligand 1f (2.30 g, 13.44 mmol) and Ti(O-
iPr)4 (1.91 g, 6.72 mmol). Yield: 2.41 g (93%).
1H NMR (CDCl3): 5.28, 5.25, 5.09(s, 2H, C(O)
CHC(N)), 4.69 (dd, 1H, NCH(Et)CHabHcdO), 4.65(dd,
1H, NCH(Et)CHabHcdO), 4.18(dd, 1H, NCH(Et)CH-
abHcdO), 4.17(dd, 1H, NCH(Et)CHabHcdO), 4.03(m,
2H, NCH(Et)CH2O), 2.21(m, 2H, NCH(CHaHb CH3)
CH2O), 2.11, 2.06(s, 6H, C(N)CH3), 1.92, 1.89, 1.80(s,
6H, CH3C(O)), 1.66(m, 2H, NCH (CHaHbCH3)CH2O),
0.97 (t, 6H, NCH(CH2CH3) CH2O). 13C NMR
(CDCl3): 175.89(s, CH3H(O)), 167.13(s, C(N)CH3),
102.04(s, C(O)CHC(N)), 74.46(s, NCH(Et)CH2O),
72.78(s, NCH(Et)CH2O), 27.47(s, CH3C(O)), 24.67(s,
C(N)CH3), 21.99(s, NCH(CH2CH3) CH2O), 11.77(s,
NCH(CH2CH3)CH2O). Anal. Calc. for C18H30N2O4Ti:
C, 55.96; H, 7.83; N, 7.25. Found: C, 56.76; H, 8.30; N,
7.27%.
6.2.3. Ti(CH3C(O)CHC(NCHMeCH2O)CH3)2 (3c)
The same procedure as described in Section 6.2.1 was
adopted except ligand 1c (8.0 g, 50.89 mmol) and Ti(O-
iPr)4 (7.23 g, 25.44 mmol). Yield: 8.38 g (92%).
1H NMR (CDCl3): 5.27, 5.24, 5.08, 5.08(s, 2H,
C(O)CHC(N)), 4.79(dd, 1H, NCH(Me)CHabHcdO),
4.58(dd, 1H, NCH(Me)CHbHcdO), 4.35(m, 2H,
NCH(Me)CH2O), 4.00(dd, 1H, NCH(Me)CHabHcdO),
3.83(dd, 1H, NCH(Me)CHabHcdO), 2.14, 2.12, 2.11,
2.07(s, 6H, C(N)CH3), 1.94, 1.92, 1.88, 1.80(s, 6H,
CH3C(O)), 1.51, 1.37, 1.32, 1.24, 1.17(d, 6H,
NCH(CH3)CH2O). 13C NMR (CDCl3): 176.72, 175.83,
175.40(s, CH3C(O)), 167.89, 167.27, 166.76(s,
C(N)CH3), 103.30, 103.20, 102.01(s, C(O)CHC(N)),
78.07, 78.00, 77.14(s, NCH(Me)CH2O), 66.14, 65.73,
65.24, 64.96(s, NCH(Me)CH2O), 24.92, 24.58, 24.40,
24.25(H H3C(O)), 21.82, 21.59, 21.43, 20.74(C(N)CH3),

236
S. Lim et al. / Journal of Organometallic Chemistry 689 (2004) 224–237
6.2.7. Ti((CH3)2CHC(O)CHC(CH(CH3)2)(NCH2CH
(Me)O))2 (3h)
The same procedure as described in Section 6.2.1 was
adopted except ligand 1h (1.5 g, 7.03 mmol) and Ti(O-
iPr)4 (1.0 g, 3.52 mmol). Yield: 1.57g (95%).
1H NMR (CDCl3): 5.23, 5.22, 5.20, 5.15(s, 2H,
(CH3)3CC(O)). 13C NMR (CDCl3): 184.48(s, (CH3)3
CC(O)), 168.87(s, C(N)CH3), 97.01(s, C(O)CHC(N)),
70.89(s, NCH2CH2O), 60.18(s, NCH2CH2O), 37.84(s,
(CH3)3CC(O)), 28.04(s, (CH3)3 CC(O)), 22.87(s,
C(N)CH3). Anal. Calc. for C20H34N2O4Ti: C, 57.97; H,
8.27; N, 6.76. Found: C, 57.87; H, 8.63; N, 6.70%.
C(O)CHC(N)),
4.87(m,
2H,
NCH2CHMeO),
4.22(dd, 1H, NCHabHcdCH(Me)O), 4.13(dd, 1H,
NCHabHcdCH(Me)O), 3.88(dd, 1H, NCHabHcdCH
(Me)O), 3.76(dd, 1H, NCHabHcdCH(Me)O), 2.92(m,
2H, C(N)CH(Me)2), 2.30(m, 2H, CH(Me)2C(O)),
1.11–1.23(4d, 12H, C(N)CH(CH3)2), 1.21(3d, 6H,
NCH2CH(CH3)O), 0.88–0.98 (4d, 12H, (CH3)2CHC
(O)). 13C NMR (CD2 Cl2): 183.51, 183.35, 183.02(s,
(CH3)2CHC(O)), 177.05, 176.49, 175.91, 175.70(s,
C(N)(CH(CH3)2)), 93.46, 93.30, 93.19(s, C(O)CHC(N)),
76.99, 76.52, 76.40, 76.12(s, NCH2CH(Me)O), 65.96,
65.60, 64.79(s, NCH2CH(Me) O), 36.35, 36.27, 36.13
(s, (CH3)2CHC(O)), 31.46, 31.40, 31.24(s, C(N)(CH
(CH3)2)), 21.66–20.18 (3s, (CH3)2 CHC(O)CHC
(NCH2CH(CH3)O)(CH(CH3)2)). Anal. Calc. for
C24H42N2O4Ti: C, 61.27; H, 9.00; N, 5.95. Found: C,
61.18; H, 9.23; N, 6.00%.
6.2.10. Ti((CH3)3CC(O)CHC(NCH2CH(Me)O)CH3)2
(3k)
The same procedure as described in Section 6.2.1 was
adopted except ligand 1k (4.0 g, 20.06 mmol) and Ti(O-
iPr)4 (2.85 g, 10.03 mmol). Yield: 3.91 g (88%).
1H NMR (CDCl3): 5.30, 5.28, 5.23, 5.19(s, 2H,
C(O)CHC(N)), 4.91, 4.82(m, 2H, NCH2CH(Me)O),
4.16(dd, 1H, NCHabHcdCH(Me)O), 3.98(dd, 1H,
NCHabHcdCH(Me)O), 3.77(dd, 1H, NCHabHcdCH
(Me)O), 3.63(dd, 1H, NCHabHcdCH(Me)O), 2.07,
2.06, 2.04(s, 6H, C(N)CH3), 1.22–1.14(d, 6H, NCH2CH
(CH3)O), 1.02, 1.01, 1.00, 1.00(s, 18H, (CH3)3CC(O)).
13C NMR (CDCl3): 185.12(s, (CH3)3CC(O)), 168.79,
168.46, 168.17(s, C(N)CH3), 97.47, 97.00, 96.89(s,
C(O)CHC(N)), 77.31, 76.80, 76.36(s, NCH2CH(Me)O),
67.53, 66.95, 66.57, 66.36(s, NCH2CH(Me)O), 38.29,
38.22(s, C(N)CH3), 28.50(s, (CH3)3CC(O)), 23.13,
22.02, 21.18, 20.73(s, NCH2CH(CH3)O). Anal. Calc. for
C22H38N2O4Ti: C, 59.73; H, 8.66; N, 6.33. Found: C,
59.44; H, 8.78; N, 6.84%.
6.2.8. Ti(CH3C(O)CHC(NCH(CH2CH3)CH2O)CH3)2
(3f)
The same procedure as described in Section 6.2.1 was
adopted except ligand 1i (6.0 g, 28.14 mmol) and Ti(O-
iPr)4 (4.0 g, 14.07 mmol). Yield: 6.22 g (94%).
1H NMR (CDCl3): 5.34, 5.17, 5.13(s, 2H,
C(O)CHC(N)), 4.83(dd, 1H, NCH(Me)CHabHcdO),
4.79(dd, 1H, NCH(Me)CHabHcdO), 4.56(m, 1H,
NCHa(Me)CH2O), 4.38(m, 1H, NCHb(Me)CH2O),
4.03(dd, 1H, NCH(Me)CHabHcdO), 3.95(dd, 1H,
NCH(Me)CHabHcdO), 3.03(m, 2H, C(N)(CH(CH3)2),
2.39(m, 1H, (CH3)2CHa C(O)), 2.30(m, 1H, (CH3)2CHb
C(O)), 1.51, 1.41, 1.37(d, 6H, NCH(CH3)CH2O), 1.24–
1.13(4d, 12H, C(N)(CH(CH3)2), 1.04–0.85(5d, 12H,
(CH3)2CHC(O)). 13C NMR (CDCl3): 183.45, 182.98,
182.81(s, CH3C(O)), 175.95, 175.70, 175.32(s, C(N)
CH3), 94.31, 93.84, 93.59(s, C(O)CHC(N)), 76.80, 76.69,
76.36(s, NCH(Me)CH2O), 64.77, 64.36, 63.59(s, NCH
(Me)CH2O), 36.46, 36.36, 36.22(s, (CH3)2CHC(O)),
31.20, 31.00, 30.90(s, C(N)CH(CH3)2), 22.32, 22.17,
22.10, 22.05(s, NCH(CH3)CH2O), 21.87, 21.66, 21.60,
21.50(s, C(N)CH(CH3)2), 20.89, 20.78, 20.63, 20.52(s,
(CH3)2CHC(O)). Anal. Calc. for C24H42N2O4Ti: C, 61.27;
H, 9.00; N, 5.95. Found: C, 61.33; H, 9.48; N, 5.72%.
7. Supplementary material
Variable temperature 1H NMR spectra of 2a (250
MHz, 213–297 K, toluene-d8), Variable temperature
13C NMR spectra of 2a (250 MHz, 215–297 K,
CDCl3). Crystallographic data for the structural anal-
ysis have been deposited with the Cambridge Crystal-
lographic Data Centre, CCDC No. 218803 and 218804
for compound 3f and 3k, respectively. Copies of this
information may be obtained free of the charge from
The Director, CCDC, 12 Union Road, Cambridge,
CB2 1EZ, UK (Fax: +44-1223-336033; e-mail: de-
posit@ccdc. cam.ac.uk or http://www.ccdc.cam.ac.uk).
Acknowledgements
This work is financially supported by Korea Research
Foundation Grant (KRF-2000-015-DP0230) in 2000.
6.2.9. Ti((CH3)3CC(O)CHC(NCH2CH2O)CH3)2 (3j)
The same procedure as described in Section 6.2.1 was
adopted except ligand 1j (4.98 g, 26.88 mmol) and Ti(O-
iPr)4 (3.82 g, 13.44 mmol). Yield: 5.05 g (91%).
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NCH2CH2O), 2.00(s, 6H, C(N)CH3), 0.92(s, 18H,
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