Syntheses and molecular structures of titanium derivatives with polymerizable ligands. Toward extended arrays

Article abstract of DOI:10.1002/zaac.200400279

The reactions between Ti(OR)₄ and allylacetatoacetate (HAAA) in 1:1 or 1:2 stoichiometry at rt gave Ti₂(OR)₆(AAA) ₂ R = Et (1), iPr (2) and Ti(OR)₂(AAA)₂ R = Et (3), iPr (4) species. A monosubstituted derivative Ti₂(OiPr) ₆(AMP)₂ (5) was isolated with allylmethylphenol (AMPH). 1 and 5 were characterized by single crystal X-ray diffraction. Their molecular structures consist of dimers with the polymerizable ligands in terminal positions and-bridging alkoxide ligands assembling five and six-coordinated metal atoms, respectively. The Ti-O bond lengths of 1 are in the range 1.76(1) to 2.11(1) A with the variation Ti-OEt < Ti-μ-OEt < Ti-η²-O (allylacetatoacetate). All compounds were characterized by FTIR and ¹H NMR.The possibility to accede to more extended arrays either by hydrolysis or by radical initiated homo- or co-polymerization reactions was investigated for the allylacetato derivatives as well as for Ti(OiPr)₂(AAEMA)₂ AAEMA = [2-(methacryloyloxy)- ethylacetoacetato] for the latter reactions.

Full text of DOI:10.1002/zaac.200400279

Syntheses and Molecular Structures of Titanium Derivatives with Polymerizable
Ligands. Toward Extended Arrays
Lauren C. Cauro-Gameta, Liliane G. Hubert-Pfalzgraf*,a, and Sylvain Lecocqb
b
Villeurbanne / France, a Institut de Recherches sur la Catalyse and Centre de Cristallographie, Universite Claude Bernard Ϫ Lyon I
´
Received July 9th 2004.
Dedicated to Professor Michael Veith on the Occasion of his 60th Birthday
Abstract. The reactions between Ti(OR)4 and allylacetatoacetate
(HAAA) in 1:1 or 1:2 stoichiometry at rt gave Ti2(OR)6(AAA)2
R ϭ Et (1), iPr (2) and Ti(OR)2(AAA)2 R ϭ Et (3), iPr (4) species.
A monosubstituted derivative Ti2(OiPr)6(AMP)2 (5) was isolated
with allylmethylphenol (AMPH). 1 and 5 were characterized by
single crystal X-ray diffraction. Their molecular structures consist
of dimers with the polymerizable ligands in terminal positions and-
bridging alkoxide ligands assembling five and six-coordinated me-
tal atoms, respectively. The Ti-O bond lengths of 1 are in the range
O (allylacetatoacetate). All compounds were characterized by FT-
IR and 1H NMR.The possibility to accede to more extended arrays
either by hydrolysis or by radical initiated homo- or co-polymeriz-
ation reactions was investigated for the allylacetato derivatives as
well as for Ti(OiPr)2(AAEMA)2 AAEMA ϭ [2-(methacryloyloxy)-
ethylacetoacetato] for the latter reactions.
Keywords: Titanium; Alkoxides; Polymerizable ligands; X-Ray
structure; Sol-gel process
2
˚
1.76(1) to 2.11(1) A with the variation Ti-OEt < Ti-µ-OEt < Ti-η -
Synthesen und Strukturen von Titan-Derivaten mit polymerisierbaren Liganden
˚
Die Bindungslängen Ti-O in 1 betragen 1.76(1) bis 2.11(1) A in
Inhaltübersicht. Ti(OiPr)4 reagiert mit Allylacetoacetate (HAAA)
im Verhältnis 1:1 oder 1:2 bei Raumtemperatur zu Ti2(O-
R)6(AAA)2 (R ϭ Et (1), iPr (2)) und Ti(OR)2(AAA)2 (R ϭ Et (3),
iPr (4)). Mit Allylmethylphenol (AMPH) wurde Ti2(OiPr)6(AMP)2
(5) isoliert. 1 und 5 wurden durch Einkristallstrukturanalyse cha-
rakterisiert. Ihre Molekülstruktur besteht aus Dimeren mit end-
ständigen, polymerisierbaren Liganden und verbrückenden Alko-
xidliganden um fünf- bzw. sechsfach-koordinierten Metallatomen.
der Reihe Ti-OEt < Ti-µ-OEt < Ti-η2-O (Allylacetoacetat). Alle
1
Verbindungen werden durch FT-IR- und H NMR-Spektroskopie
charakterisiert. Die Möglichkeit ausgedehntere Wirkgruppen so-
wohl durch Hydrolyse oder durch radikalinitiierte Homo- oder Ko-
polymerisation zu erhalten, wurde für die Allylacetato-Derivate wie
für Ti(OiPr)2(AAEMA)2 (AAEMA ϭ 2-(methacryloyloxy)ethyl-
acetoacetato) untersucht.
Introduction
[6], most of the compounds are thus based on polymerizab-
le ancillary ligands such as diols (for instance cis-2-butene-
1,4-diol), β-diketoesters [2-(methacryloyloxy)ethylaceto-
acetate ϭ HAAEMA] [7] or acids (acrylic, methacrylic)
[1, 4]. A large number of structurally characterized oxo or
oxohydroxo clusters of group 4 metals based on acrylate or
methacrylate (OMc) ligands such as for instance
Ti6(µ-O)2(µ3-O)2(OEt)8(OMc)8, Zr6O4(OH)4(OMc)10(PrOH),
M4(µ3-O)2(OMc)12(M ϭ Zr, Hf) [3] or Ti4Y2(µ3-O)4-
(µ-OMc)12(µ1-OMc)2(HOC2H4OMe)2 [8] have been re-
ported. Functional aryloxides such as 2-methoxy-4-allyl-
phenol, 2-MeO-C6H3-4-CHϭCH2Me (isoeugenol) have
been used as well with titanium alkoxides but incontrast to
the previous heteroleptic species, no structural characteriz-
ation was achieved [9].
Hybrid organic-inorganic materials have gained increas-
ingly attention in the last decade. When the metal coordi-
nation sphere presents a polymerizable ligand, materials
displaying an organic as well as an inorganic network and
thus combining the properties of inorganic and organic ma-
terials can be obtained. Metal alkoxides bearing polymeriz-
able ligands are often used as a means to accede to hybrid
organic-inorganic polymers [1]. Such compounds have been
developed for early transition metals mostly titanium and-
zirconium [2] and to a lower extent, hafnium [3], niobium
[4], and lanthanides [5]. Titanium is especially attractive as
nuclear diagnostic in Internal Confinement Fusion (ICF)
experiments and study of laser-material interactions. De-
rivatives based on polymerizable OR groups remain scarce
We report here the synthesis and characterization by FT-
1
IR and H NMR of titanium derivatives with allylaceta-
* Prof. Dr. Liliane G. Hubert-Pfalzgraf
Universite Lyon 1
2 avenue A. Einstein
F-69626 Villeurbanne / France
Fax: ϩϩ 33 4 72 44 53 99
E-mail: hubert@univ-lyon1.fr
toacetate (HAAA) or 2-allyl-6-methylphenol (AMPH) as li-
gands. The molecular structures of Ti2(OEt)6(n2-AAA)2 (1)
and Ti2(OPri)6(AMP)2 (5) were established by single crystal
X-ray diffraction. The hydrolytic and polymerization behav-
iour of various Ti species was investigated.
´
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DOI: 10.1002/zaac.200400279
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L. C. Cauro-Gamet, L. G. Hubert-Pfalzgraf, S. Lecocq
Table 1 FT-IR and 1H NMR data of the titanium allylacetato derivatives
Compound
HAAA
FT-IR (cmϪ1
vCϭO υCϭC υTi-OR MeCO COCHCO
)
1H NMR (CDCl3, 25 °C, ppm)
OR (R ϭ Et, iPr)
CH or CH2
OCH2
CH2ϭ
ϭCH
Me
1745
1719
1649
1636
Ϫ
2.2 (s)
3.4 (s)*
4.6 (d)
5.2 (m)
5.95 (m)
Ϫ
Ϫ
J ϭ 6 Hz
Ti2(OEt)6(AAA)2
1
1570m 1633vs 595s
1528vs 1610vs 582m
500m
1.9 8(s) 5.0 (s)
2.00 (s) 4.98 (s) 2H
6H
4.6-4.76 (m) 5.24 (td)
5.76-5.96 (m) 1.2 (t) ; 1.23 (t)
4.46 (m),
4.74 (m (2:1)
12H
4H
Jbϭ 6 Hz
4H
2H
18H
Ja ϭ 6.6 Hz
Jbϭ 12 Hz
Jcϭ 1.8 Hz
5.12-5.28
(m) 4H
Ti(OEt)2(AAA)2
3
Ti3O(OEt)8(AAA)2 1526vs 1633vs 575vs
1525vs 1635vs 600s
1613vs 595s
2.00 (s) 4.98 (s)
4.45 br
4H
5.76-5.95
(m) 2H
1.20(t), 1.18(t)
J ϭ 6.3 Hz, 6H
1.16 (t)
4.66 (m)
4H
3.8-4.4 (m)
16H
6H
2H
1.85 (s) 4.96 (s)
4.3-4.8 (m) 5.1-5.3 (m) 5.7-5.9 (m)
6a
1613vs 527m
3H
1.9 (s)
3H
4.80 (s)
2H
4H
4H
2H
24H
Ja ϭ 6 Hz
441vs
390m
350m
Ti2(OiPr)6(AAA)2
2
1578m 1637vs 633vs
1529vs 1614vs 465vs
448vs
1.96 (s) 5.0 (s),
1.92(s) 5.02 (s)
4.76 (dt)
4H
5.24 (td)
4H
5.76-5.96 (m) 1.22 (d) ; 1.26 (d) 4.76 (sept)
2H
36H
Ja ϭ 6 Hz
4.65 (br)(2:1)
6H
Ja ϭ 6 Hz
4.67 sept
2H, J ϭ 6 Hz
4.5 (sept), 4.76m
8H
6H
2H
Jbϭ 6.15 Hz Jbϭ 11 Hz
Jc ϭ 1.4 Hz
362vs
Ti(OiPr)2(AAA)2
1529 s 1629vs 625 vs 1.92 s
1610vs 575 vs 6H
5.02 s
2H
4.75 br
4H
5.28 m
4H
5.74 Ϫ 5.93 m 1.24 d, 12H
2H J ϭ 6 Hz
5.76-5.96 (m) 1.22 (d), 1.24(d)
4
Ti3O(ObPr)8(AAA)2 1547s 1634vs 600vs
1.96 (s) 5.05 (s), 5.02 (s) 4.7-4.82 (m) 5.2 (t)
1.88 s 2H 4H 4H
534 sh 6H Jbϭ 6.15 Hz Jbϭ 13 Hz
6b
1529vs 1628vs 582vs
2H
48H
Ja ϭ 6.2 Hz
Ja ϭ 6.2 Hz
452vs
395m
* CH2, (s) ϭ singlet, (m) ϭ multiplet, (t) ϭ triplet, Italics identify the most intense peaks
Results and Discussion
the CH signal of the chelate (4.98 and 5.00 ppm). Compari-
son of the spectra of the mono- and di-substituted ethoxide
species showed that the minor signals (about 20 %) resonat-
ing at 2.00 ppm for the Me groups and at 4.98 ppm for the
CH ones correspond actually to Ti(OEt)2(AAA)2. A similar
behavior was observed for the isopropoxide derivative 2.
Disproportionation of [Ti(OR)3(AAA)]2 was also con-
firmed by the signal of Ti(OiPr)4 at 3.9 ppm for instance
for 2 according to eq. (1). The region of the Ti-OR signals
indicate the presence of magnetically non equivalent OR
groups in a 2:1 integration ratio for 1 and 2. The monosub-
stituted 1 and 2 derivatives were more stable in C6D6 than
in CDCl3 but the chemical shift range and structural infor-
mation were more limited by the overlapping between the
signals of the ligand and/or of the homoleptic titaniumal-
koxide especially for Ti(OEt)4. Disubstituted species were
more stable even in CDCl3 solutions. This observation is
in agreement with the use of t-butylacetatoacetate (tboac)
M(OR)2(tboac)2 (M ϭ Ti, Zr) derivatives as precursors for
liquid injection CVD [11].
Synthesis and characterization of titanium allylacetato
derivatives, molecular structure of Ti2(OEt)6(AAA)2
The reactions between Ti(OR)4 (R ϭ Et, iPr) and allylaceta-
toacetate (HAAA) were investigated in 1:1 and 1:2 stoichi-
ometry in non-polar media,hexane or toluene. The hetero-
leptic species were isolated as colourless crystals and shown
1
by elemental analysis and H NMR to have the fomulae
[Ti(OR)3(AAA)]m [R ϭ Et (1), R ϭ iPr (2)] and
Ti(OR)2(AAA)2 [Rϭ Et (3), iPr (4)]. The monosubstituted
compounds were extremely moisture sensitive giving yellow,
very soluble oxo derivatives.
The various compounds were characterized by FT-IR
and NMR (1H and 13C) data (Table 1). The presence of the
allylacetatoacetate ligand was identified by several absorp-
tion bands between 1640 and 1525 cmϪ1 characteristic of
the νCϭO and νCϭC bonds. No free ligand (νCO 1745,
1719 cmϪ1) was detected. The νTi-OR absorption bands
(600-400 cmϪ1) were more diagnostic of the various com-
pounds. The NMR spectra showed numerous peaks due to
the unsaturated ligands and were further complicated by
the fact that dilution experiments indicated the presence of
several molecular species, either geometrical isomers or de-
rivatives resulting from redistribution reactions for the
monosubstituted derivatives. Comparison of the spectra ob-
tained for [Ti(OR)3(AAA)]2 and Ti(OR)2(AAA)2 species
supported redistribution phenomena as observed for
Ti2(OR)6(AAA)2 Ǟ Ti(OR)4 ϩ Ti(OR)2(AAA)2
(1)
X-ray diffraction studies of 1 indicate its dimeric, centro-
symmetric structure Ti2(µ-OEt)2(OEt)4(η2-AAA)2 based on
six-coordinate metal atoms (fig. 1). Selected bond lengths
and angles are collected in Table 2. The Ti-O bond lengths
˚
spread over the range 1.803(2) to 2.142(2) A the variation
i
[Ti(OR)3(β-dik)]2 with R ϭ Me, Et, Pr; β-dik ϭ acac, thd
being Ti-OEt < Ti-µOEt < Ti-O(η2-AAA). The Ti-µOEt
1
˚
[10]. Indeed, the H NMR spectrum of 1 in CDCl3 at rt
distances [1.975(2) and 2.076(2) A for Ti(1)-O(4) and Ti(1)-
showed two singlets at 1.98 and 2.00 ppm for the methyl
O(4a), respectively] indicate a unsymmetrical bridge as a
groups of the unsaturated ligands as well as two singlets for
result of the trans effect of the terminal OR ligand. The
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Synthesis and Molecular Structuresof Titanium Derivatives with Polymerizable Ligands
Table 2 Selected bond lengths/A and angles/° for Ti2(OEt)6(AAA)2.
˚
Ti(1)-O(5)
Ti(1)-O(6)
Ti(1)-O(4)
Ti(1)-O(2)
Ti(1)-O(4)#1
Ti(1)-O(1)
Ti(1)ϪTi(1)#1
1.803(2)
1.809(2)
1.975(2)
1.986(2)
2.076(2)
2.142(2)
3.2461(10)
O(5)-Ti(1)-O(6)
O(5)-Ti(1)-O(4)
O(6)-Ti(1)-O(4)
O(5)-Ti(1)-O(2)
O(6)-Ti(1)-O(2)
O(4)-Ti(1)-O(2)
O(5)-Ti(1)-O(4)#1
O(6)-Ti(1)-O(4)#1
O(4)-Ti(1)-O(4)#1
O(2)-Ti(1)-O(4)#1
O(5)-Ti(1)-O(1)
O(6)-Ti(1)-O(1)
O(4)-Ti(1)-O(1)
O(2)-Ti(1)-O(1)
O(4)#1-Ti(1)-O(1)
95.92(11)
96.92(10)
102.22(9)
98.62(11)
89.84(10)
159.21(9)
166.38(10)
95.60(9)
73.51(8)
88.66(8)
85.89(10)
170.84(10)
86.43(8)
Fig. 1 Molecular structure of Ti2(µ-OEt)2(OEt)4(η2-AAA)2 show-
ing the atom numbering scheme (thermal ellipsoids at 20 % prob-
ability).
81.00(9)
83.89(8)
C(40)-O(4)-Ti(1)
C(40)-O(4)-Ti(1)#1
Ti(1)-O(4)-Ti(1)#1
C(4)-O(1)-Ti(1)
C(2)-O(2)-Ti(1)
C(50)-O(5)-Ti(1)
C(60)-O(6)-Ti(1)
125.6(2)
127.6(2)
106.49(8)
130.6(2)
135.8(2)
142.6(3)
126.6(3)
bonding of the allylacetatoacetate ligand is asymmetric as
˚
˚
well [2.142(2) A for Ti(1)-O(1) and 1.986(2) A for Ti(1)-
O(2)]. The stereochemistry around the titanium atom is
quite distorted [73.51(8)Ϫ170.84(10)°] as a result of the
acute intrabridge O(4a)-Ti(1)-O(4) angle (73.51(8)°) as well
as of the bite angle of the β-ketoesterate ligand. The Ti-O-
C angles for the terminal alkoxide ligands [126.6(3)° and
Symmetry transformations used to generate equivalent atoms:
#1 Ϫxϩ1,Ϫy,Ϫzϩ1
˚
142.6(3)°] are quite small. The Ti···Ti distance [3.246(1) A]
Ti2(µ-OiPr)2(OiPr)4(AMP)2 (fig. 2). Selected bond lengths
and angles were collected intable 3. The Ti-O bond lengths
range from 1.767(2) to 2.109(2) A, with the ranking Ti-OiPr
< Ti-O(AMP) < Ti-µOiPr. The metal atom is only five-co-
ordinated and this lower coordination number with respect
to that in 1 leads to shorter Ti-O distances. The stereochem-
istry at the titanium atom corresponds to a distorted trig-
onal bipyramid with two of theisopropoxide groups being
in the apical positions and the angles varying from
72.56(8)° (intrabridge) to 170.14(8)°. The last isopropoxide
group, in equatorial position, gives raise to a quite long Ti-
as well as all metric parameters are in agreement with the
literature [12]. The unsaturated chains are in trans positions
suggesting that they will be available for homo- or co-poly-
merisation. The structure of 1 is similar to that reported for
a TiIV glycinate derivative Ti2(OEt)6(NH2CH2CO2)2 [13].
˚
Titanium species with functional aryloxide ligands
The reaction between Ti(OiPr)4 and 2-allyl-6-methylphenol
(AMPH) in a 1:1 stoichiometry afforded yellow crystals, 5
(eq (2)). Their IR spectrum indicate strong absorption
bands at 373, 363 and 335 cmϪ1 whereas the presence of
the aryloxide was evidenced by νCϭC absorption bands at
1639 and 1590 cmϪ1. The unsaturated allyl group was best
observed in the NMR spectra at 5.02 ppm for instance for
the CH2 group, these spectra supported a Ti(OiPr)3(AMP)
formula (yield 64 %), whilst 13C NMR spectra showed two
types of isopropoxide ligands at 25.5 and 26.6 ppm.
˚
O linkage of 2.109(2) A, thus leading to an unsymmetrical
bridge [vs 1.932(2) A]. The shortest bond length, Ti-O(2) is
˚
associated to a large Ti-O-C angle [175.9(2)° vs 137.5(2)°
for the other terminal ligands). The Ti···Ti distance,
˚
3.2597(8) A, is similar to that observed for 1 or other poly-
nuclear Ti species [12]. 5 was extremely sensitive to hydroly-
sis especially in the solid state. Its hydrolysis in solution
(h ϭ 1) lead to gels andwas faster in isopropanol than in
toluene. No further reactivity studies were undertaken.
Reactivity: toward the formation of extended arrays
Hydrolysis-polycondensation reactions
The Ti-AAA bond is quite labile: free allylacetatoacetate is
detected by NMR for hydrolysis ratio h [h ϭ molar ratio
water/M(OR)n] as low as 0.05. The loss of the AAAH li-
gand (also evidenced by FT-IR) by hydrolysis leads to the
formation of yellow, highly soluble oxo species (broad Ti-
The solid state structure of the allylmethylphenoxide deriva-
tive 5 confirmed its stoichiometry. It corresponds to a dimer
Z. Anorg. Allg. Chem. 2004, 630, 2071Ϫ2077
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L. C. Cauro-Gamet, L. G. Hubert-Pfalzgraf, S. Lecocq
Fig. 2 Molecular structure of Ti2(OiPr)6(AMP)2 showing the atom
numbering scheme (thermal ellipsoids at 20 % probability).
Scheme 1 First steps of the hydrolytic condensation of the mono-
substituted Ti allylacetato derivatives
˚
Table 3 Selected bond lengths/A and angles/deg for
Ti2(OiPr)6(AMP)2.
extensive hydrolysis. Such formula confirm the partial loss
of the β-ketoesterate ligand and can result from hydrolysis-
condensation according to eq 3 and 4
Ti(1)-O(2)
Ti(1)-O(5)
Ti(1)-O(4)
Ti(1)-O(3)
Ti(1)-O(3)#1
Ti(1)-Ti(1)#1
1.767(2)
1.799(2)
1.854(2)
1.932(2)
2.109(2)
3.2597(8)
3 Ti2(OR)6(AAA)2 ϩ 2 H2O Ǟ 2 Ti3O(OR)8(AAA)2
ϩ 2 HAAA ϩ R2O
(3)
(4)
2 Ti2(OR)6(AAA)2 ϩ 3 H2O Ǟ Ti4O3(OR)8(AAA)2
ϩ 2 HAAA ϩ 4 ROH
O(2)-Ti(1)-O(5)
O(2)-Ti(1)-O(4)
O(5)-Ti(1)-O(4)
O(2)-Ti(1)-O(3)
O(5)-Ti(1)-O(3)
O(4)-Ti(1)-O(3)
O(2)-Ti(1)-O(3)#1
O(5)-Ti(1)-O(3)#1
O(4)-Ti(1)-O(3)#1
O(3)-Ti(1)-O(3)#1
C(20)-O(2)-Ti(1)
C(6)-O(3)-Ti(1)
C(6)-O(3)-Ti(1)#1
Ti(1)-O(3)-Ti(1)#1
99.90(9)
97.61(9)
113.31(9)
98.15(8)
118.26(9)
121.92(8)
170.14(8)
87.69(8)
84.98(8)
72.56(8)
175.9(2)
134.9(2)
117.6(2)
107.44(8)
Unfortunately all attempts to get crystals suitable for X-ray
analysis ofthe yellow species obtained under various hydro-
lytic conditions of 1 or 2 were unsuccessful. NMR data sug-
gest magnetically non equivalent alkoxide ligands but useful
structural information could not be reached due to overlap-
ping between the OR and AAA signals at low temperature.
Numerous and diverse polynuclear Ti oxo cores have been
reported. Trinuclear titanium oxo species such as for in-
stance Ti3(µ3-O)(OiPr)7(O3C9H15) in which the tridentate
ligand results from coupling of acetone [14] or Ti3(µ3-O)(µ-
OAc)2(µ-ONp)2(ONp) [15] (ONp ϭ neopentoxide) are
known. Tetranuclear Ti oxo cores are represented for in-
stance by Ti4(µ3-O)2(µ-OR)2(OR)8(acac)2 [16] or by Ti4(µ3-
C(7)-O(4)-Ti(1)
C(10)-O(5)-Ti(1)
138.7(2)
138.9(2)
Symmetry transformations used to generate equivalent atoms:
#1 Ϫxϩ2,Ϫy,Ϫz
O)(µ-O)2(η2-dmae)2(η1-dmae)4(µ,η2-dmae)2 (dmae
ϭ
OC2H4NMe2) [17]. The bridging OR ligands of the
Ti2(OR)6(AAA)2 species being the most nucleophilic
centres for the attack of water [18], condensation is likely
to proceed via an hydroxyalkoxide Ti2(OR)5(OH)(AAA)2
intermediate. It can react either according to eq. (3), or with
a Ti(OR)4 moiety (resulting from redistribution reactions
eq. (1)) or dimerize after loss of a AAAH ligand by intra-
molecular H transfert. Scheme 1 represents simple possible
structural cores based on 6-coordinate titanium for the
early hydrolytic products.
Controlled hydrolysis of 1 was also done on 0.2 M solu-
tions in THF by adding water in the same solvent and for
various hydrolysis ratios. Colloidal yellow solutions were
obtained for h ϭ 0 to 4 for freshly hydrolyzed solutions.
Particles size (hydrodynamic diameters) were determined by
dynamic light scattering. Particles of 203 and 290 nm
O-Ti absorption bands between 890 and 700 cmϪ1). Com-
parison of the hydrolytic behaviour of titanium complexes
with various saturated and unsaturated ligands indicate that
the Ti-O(AAA) bond is more susceptible to hydrolysis than
the Ti-O(acac) one. The bridging 2-butene-1,4-diolate for
instance is retained up to h ϭ 1 for [Ti4(OPri)8(µ,η2-
OCH2CHϭCHCH2O)2(µ3,η2-OCH2CHϭCHCH2O)2] [7].
The formation of oxo species is favoured for the monosub-
stituted species 1 and 2 either in the solid state by adven-
titious hydrolysis or in solution by long reactions times and
1
trace amounts of water in the AAAH ligand. H NMR
spectra of the yellow isolated species display an OR/AAA
integration ratio of 4/1. Analytical data are in agreement
with formula such as [Ti3O(OEt)6(AAA)2]m (6) (ν Ti-O
786 cmϪ1 for instance) or [Ti4O3(OR)8(AAA)2]m for more
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Synthesis and Molecular Structuresof Titanium Derivatives with Polymerizable Ligands
Scheme 2 Homo and co-polymerization reactions of compound 7. For sake of clarity, the modification of only one polymerizable ligand
is represented. The growth of the inorganic network (formation of Ti-O-Ti bonds) will result from the subsequent hydrolytic reactions by
addition of water.
respectively were observed for instance for h ϭ 1 and h ϭ
1.5. As expected, the particle size increases with the hy-
drolysis ratio (700 nm for h ϭ 2). Reversible gels, which
became progressively irreversible, were formed after one
week for h ϭ 4. Similar observations were made in 0.2 M
toluene but the stability of the sols was higher in polar me-
dia, THF or ethanol. Complete hydrolysis with excess of
water (h ϭ 50) gave colorless powders analyzing as
TiO(OH)0.5(AAA)0.5 thus confirming partial loss of the
functional ligand. As a general feature, the yellow color of
the sols changed to orange and orange-red by increase of h
as well as by aging. This increase of coloration suggests
complex reactions as observed for the reaction between ace-
tone and titanium alkoxides [14]. Indeed, allylacetatoacetate
can undergo re-esterification or cleavage reactions in the
presence of alcohol and under hydrolytic conditions with
formation of various organics such as allyl alcohol, 3-oxo
butanoic acid and acetone [19]. IR and 1H NMR data
of aged solutions or gels support such features (vCO 1765,
1735 cmϪ1 in the FT-IR) but were not fully investigated.
the poor hydrolytic stability of the allylacetato species ham-
pered easy differentiation of the inorganic, namely hydroly-
sis, and organic polymerisation reactions. Better resultswere
obtained with 7 with the acrylate functionality and with 8.
Homopolymerization of 7was achieved in toluene at 75 °C
in the presence of AIBN as initiator. After 4 h, the initial
solution was transformed into a glassy gelindicating cross-
linking. The M-OR absorption bands at 623, 600, 580,
525 cmϪ1 were unchanged with respect to those of 7 indi-
cating that gelation was not due to hydrolysis and formation
of the Ti-O-Ti network.
Copolymerization of 7 with styrene was also achieved in
toluene in the presence of AIBN. After 2 h at 55 °C, a soft
gel was obtained. Scheme 2 is a cartoon of the homo and
copolymerization reactions of 7. Formation of the poly-
styrene (PS) network was evidenced by its characteristic
sharp absorption bands at 464 cmϪ1 and by the harmonics
at 1943, 1858, 1803 cmϪ1 for instance. Longer reaction
times lead to growth of the organic network with hardening
and shrinkage of the gel as a glassy, transparent insoluble
polymer whereas the Ti-OR absorption bands remained un-
affected. No metallic species was found in the mother liquor
nor extracted by washing the polymer with isopropanol in-
dicating that the AAEMA moiety was anchored to the PS
backbone. Elemental analysis of the polymeric material ob-
tained after washing with toluene in order to remove non
reacted PS confirmed the presence of titanium (2.6 %). Hy-
drolysis of the Ti-polystyrene copolymer and subsequent
washing with ethanol and toluenelead to formation of the
Ti-O-Ti network (broad absorptions from 880 to 450 cmϪ1
in the FT-IR). Besides those absorptions, the spectra dis-
Homo and copolymerisation reactions
The feasibility of homo and copolymerisation reactions wa-
sinvestigated for Ti(OEt)3-x(AAA)x species (x ϭ 1, 2) and
compared to those of other titanium derivatives bearing
polymerizable ligands such as Ti(OiPr)2(AAEMA)2 7 or
Ti(OiPr)3(oleate) 8 [7]. Thermal activation appeared better
than photochemical one due to lower degradation of most
complexes (<5 %). Monitoring was achieved by FT-IR or
NMR [20]. The coordinated AAA ligands showed a low
conversion intocarbon-carbon bond formation. Moreover,
played those of the acrylate moiety (vCO2 at 1720 cmϪ1
)
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L. C. Cauro-Gamet, L. G. Hubert-Pfalzgraf, S. Lecocq
Table 4 Crystallographic data of Ti2(OEt)4(µ-OEt)2(η2-AAA)2 and of Ti2(OiPr)4(µ-OiPr)2(AMP)2 (at 123K)
Chemical formula
Formula weight
C26H48O12Ti2(1)
648.44
9.9670(3)
10.8730(5)
15.8520(5)
C38H64O8Ti2 (5)
744.68
˚
a/A
9.8690(2)
9.9530(2)
12.3110(4)
84.564(1)
75.066(1)
63.768(2)
1047.83(5)
1
˚
b/A
˚
c/A
α/°
β/°
γ/°
93.568(2)
3
˚
V/A
1714.57(11)
2
Z
Crystal system
monoclinic
P21/c
0.518
0.71070
triclinic
P1
0.425
0.71070
¯
Space group
Absorption coefficient/mmϪ1
˚
Wavelength λ/A
qrange for data collection/°
Reflections collected
3.11-27.48
11719
3.24-24.72
14777
Independent reflections
Refinement method
3820
3534
Full-matrix least-squares on F2
3820 / 2 / 181
Full-matrix least-squares on F2
3534 / 0 / 217
Data / restraints / parameters
Goodness of fit on F2
Final R indices [I>2Σ(I)]
R indices (all data)
1.022
1.051
R1 ϭ 0.0696, wR2 ϭ 0.1969
R1 ϭ 0.0829, wR2 ϭ 0.2205
Ϫ0.537 0.665
R1 ϭ 0.0549, wR2 ϭ 0.1492
R1 ϭ 0.0622, wR2 ϭ 0.1550
Ϫ0.521 0.596
Ϫ3
˚
∆ρ min Ϫ ∆ρ max/e.A
Ti(OR)2(AAA)2(R؍Et (3), iPr (4)). The same procedure as for 1
but applied to 2.64 ml (19.26 mmol) of HAAA and 2.4 ml of Ti-
(OEt)4 (9.63 mmol) gave 3 at Ϫ10 °C (2.36 g; 58 %). soluble in us-
ual organic solvents. Anal. for C18H28O8Ti Found C, 51.23 (calc.
51.44); H, 6.65 (6.71) %.
and of the PS backbone at 1603, 1495, 1453, 760, 709.6
cmϪ1 whereas elemental analysis accounted for 2.5 % of Ti.
The Ti doped polystyrene was slightly more stable ther-
mally than the non-doped one as shown by TGA [7b].
Same procedure for 4, anal. for C20H32O8Ti (448.35) found C 53.10
(calc.53.58), H 7.03 (7.19) %
Experimental Section
Ti3O(OR)8(AAA)2 (R ؍ Et (6a), iPr (6b)). Hydrolysis of 1 as a
solid gave a yellow pasty material. Drying under high vacuum gave
a yellow solid, 6a very soluble in hydrocarbons, soluble in ethanol.
Hydrolysis of 1 in toluene (hϭ 0.5) gave the same compound after
48 h. Anal. for C30H58O15Ti3, found C, 39.96 (39.69), H: 5.07
(5.09) %.
All experiments were performed under dry nitrogen using Schlenk
tubes and vacuum line techniques. Solvents were purified by stand-
ards methods. Allylacetatoacetate and HAAEMA (Aldrich) were
dried over molecular sieves whereas 2-allyl-6-methylphenol (Ald-
rich) was purified by chromatography over alumina. The titanium
alkoxides were distilled under vacuum. Ti(OiPr)2(AAEMA)2 was
synthesized as reported [7]. Analyses were obtained from the Cen-
tre de microanalyses du CNRS. FT-IR spectra were obtained as
Nujol mulls with a Perkin-Elmer Paragon 500 spectrometer or as
KBr pellets (for the polymeric materials) whereas NMR data were
obtained with a AC-300 Bruker spectrometer. The spectroscopic
(FT-IR, NMR) data of the Ti allylacetatoacetate complexes are
collected in table 1. Particle sizes were measured in solution with a
Coulter N4 Plus submicron particle sizer.
The isopropoxide derivative was best obtained by reacting 0.92 ml
(6.73 mmol) of commercial HAAA with 1.91 g of Ti(OiPr)4
(6.73 mmol) in 23 ml hexane at rt for 70 h (53 %). Anal
C38H74O15Ti3 (914.35) found C 49.25 (49.87) H, 7.97 (8.16) %
Ti(OiPr)3(AMP) (5) 2-allylmethylphenol (0.41 g, 2.69 mmol) was
added to Ti(OPri)4 (1.15 g, 2.69 mmol) in 10 ml of toluene. The
medium became yellow immediately. After 2 h, it was evaporated
to dryness. Yellow crystals were obtained by recrystallization in
petroleum ether (1.19 g, 64 %). 5 is extremely moisture sensitive
giving an orange oil.
Syntheses
IR (cmϪ1): 1638 m, 1590 w (νCϭC); 1266 vs, 1214 s, 1196 m, 1128 vs, 1013 s,
1000 sh, 951 m, 912 s, 800 sh, 754 s, 735 s, 680 s; 652 s, 640 sh, 630 s; 545 m
(νTi-OR), 1H NMR (CDCl3): δ ϭ1.27 d (J ϭ 6 Hz, 18H, Me(iPr); 2.31 s
[3H, Me(Ar)]; 3.47d (2H, Jϭ6.6 Hz, CH2ϭCHCH2)], 4.58 sept br (J ϭ 6 Hz,
Ti(OR)3(AAA) (R ؍ Et (1), iPr (2)). 1.64 ml (11.5 mmol) of HAAA
diluted in 7 ml of hexane were added to 2.64 g of Ti(OEt)4
(11.5 mmol) in 23 ml of hexane. Concentration after 24 h gave1 at
Ϫ20 °C (2.98 g, 80 %) as colourless crystals. Anal. for C13H24O6Ti,
C 47.75 (calc. 48.16), H 7.21 (7.46) %. 1 was soluble in usual sol-
vents including aliphatic hydrocarbons.
13C{1H} NMR (C6D6, ppm): δ S ϭ18.7, 25.5 Me(Et); 65.3 (MeCO); 68.6,
71.2 OCH2 (Et); 73.4 (OCH2CHϭ); 88.4 (CHCO); 117.2 (ϭCH2); 133.5
(CHϭ); 172.4 (MeCO); 185 (CO2).
3H, CH(iPr)]; 5.02 d (J ϭ 9.1 Hz, 2H, CH2ϭ), 6.0 td (Jb ϭ 6.6 Hz, Jc
ϭ
9.1 Hz, 1 H, CHϭ), 6.76 t (J ϭ 7.3 Hz, 1 H, CH(Ar)], 6.97 overlapping of d
(J ϭ 7.3 Hz, 2H, CH(Ar). 13C{1H} NMR: δ ϭ 17.2 Me(Ar), 25.1, 26.3 Me-
(iPr), 36.0 (CH2CHϭCH2); 116.4 (ϭCH2); 121.2 CH(Ar); 127.0, 129.2
C(Ar); 137.4 (CHϭ); 153.7 OC(Ar).
Homo and copolymerization experiments
The same procedure applied to 2.79 g (9.84 mmol) of Ti(OiPr)4 and
1.35 ml (9.84 mmol) of HAAA in toluene gavea yellow oil. Colour-
less crystals of 2 were obtained by adding hexane-isopropanol (4/
1 ml), filtration and washing with isopropanol (2.9 g, 82 %). Anal.
C16H30O6Ti, found C, 52.32 (calc. 52.47), H, 8.15 ( 8.26) %
They were achieved under inert atmosphere in the presence of 2,2Ј-
azobis(2-methylpropionitrile) (AIBN) (2 % molar / C ϭ C) at 50 °C
in THF or toluene for 1 h or induced by UV-radiation (Heraus
lamp TQ 150, 280-360 and 460-510 nm, 150 W) in the presence of
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Z. Anorg. Allg. Chem. 2004, 630, 2071Ϫ2077

Synthesis and Molecular Structuresof Titanium Derivatives with Polymerizable Ligands
benzophenone (3 %M) in toluene. Polymerization reactions were
quenched by adding the parent alcohol. Styrene was distilledin or-
der to remove the stabilizing reagent. Typical conditions are as fol-
lows:
Copolymerization of styrene: Ti(OiPr)2(AAEMA)27 (0.334 g,
0.53 mmol) was dissolved ina mixture of styrene (0.5 ml,
4.36 mmol) and toluene (0.5 ml). 1 mg of AIBN were added. The
medium was heated in a Parr bomb at 75 °C. After quenching, the
material was washed 3 times with toluene in order to remove PS.
The resulting solid was separated by centrifugation and dried un-
der vacuum.
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Homopolymerization of 7: 0.403 g (0.686 mmol) of 7 were dis-
solved in 0.5 ml of toluene containing 2 mg of AIBN. Heating was
achieved at 75 °C in a Parr bomb. The polymeric insoluble material
was separated, washed with the parent alcohol orethanol and dried
under vacuum.
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X-Ray structure dermination of 1 and of 5
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Suitable crystals of 1 were grown from the reaction medium, those
of 5 were obtained by recrystallization in petroleum ether. The crys-
tals were fixed at a glass fibre with paratone. Data collection was
doneon a Nonius CCD diffractometer at 123 K. 11 828 reflections
of which 3856 were unique were measured for 1 and 14 777 reflec-
tions of which 3534 were unique were measured for 5. Cell param-
eters were refined using DENZO [21]. Absorption corrections were
applied with NUMABS for both compounds [22]. The structures
weresolved by Patterson methods and refined by least squares using
SHELXTL [23]. All non-H atoms were refined anisotropically giv-
ing the values of R listed in table 4. For 1, C(7) and C(51) display
quite high thermal motion and constraints were imposed in order
to obtain reasonable C-C distances. C(1) was disordered over two
positions (50 % occupation). Hydrogen atoms positions were calcu-
lated at theoretical positions and refined isotropically riding on C.
´
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4824; T. P. Vaid, J. M. Tanski, J. M. Pette, E. B. Lobkowsky, G.
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Full details for 1 and 5 have been deposited at the Cambridge Crys-
tallographic Data Centre, CCDC numbers: 175650 for 1 and 175
651 for 5. Copies of the data can be obtained free of charge on
application to The Director CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK.
Acknowledgment. LGHP is grateful to CEA-DAM (centre of Val-
duc) for financial support and a fellowship to LCCG
[20] G. Allen, J. C. Bevington, Comprehensive Polymer Science, Per-
´
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307, C. W. Carter, Jr. & R. M. Sweet, Ed. Academic Press,
1997.
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Z. Anorg. Allg. Chem. 2004, 630, 2071Ϫ2077
zaac.wiley-vch.de
 2004 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
2077