Glycol modified cis-diisopropoxy-bis(N-phenylsalicylideneiminato) titanium(IV). Syntheses, characterization, X-ray structures of Ti{O(C6H4)CH{double bond, long}NPh}2(OPri)2, [{Ti(O(C6H4)CH{double bond, long}NPh)2}O]3 and their low temperature transformation to pure grains of nanosized titania

Article abstract of DOI:10.1016/j.ica.2007.02.048

Ti(OPrⁱ)₄ reacts with N-phenylsalicylideneimine in anhydrous benzene in 1:2 molar ratio to afford precursor [Ti{O(C₆H₄)CH{double bond, long}NPh}₂{OPrⁱ}₂] (A). Further reactions of A with various glycols yield heteroleptic complexes of the type [Ti{O(C₆H₄)CH{double bond, long}NPh}₂{O-G-O}] [where -G- = (CH₂)₂ (1), (CH₂CHCH₃) (2), (CH₃CHCHCH₃) (3), (CH₂CHC₂H₅) (4), C(CH₃)₂C(CH₃)₂ (5), (CH₂)₃ (6), (CH₂CH₂CHCH₃) (7), (CH₃)₂CCH₂CHCH₃ (8), (CH₂)₅ (9) and (CH₂)₆ (10)]. FAB mass spectroscopic studies of some of the derivatives suggest their monomeric nature. Single crystal X-ray diffraction study of A reveals cis-orientation of the isopropoxy groups [O(3)-Ti(1)-O(4) = 102.23(11)°] and distorted octahedral geometry around the titanium atom. Crystal structure of a trinuclear titanoxane [{Ti(O(C₆H₄)CH{double bond, long}NPh)₂}O]₃, obtained from the partial hydrolysis of A, exhibit the formation of a six-membered Ti₃O₃ring. Complete hydrolysis and low temperature (300-500 °C) transformation of precursor A, as well as of 1 and 7 to pure TiO₂ have also been achieved using sol-gel technique. The XRD patterns indicate formation of anatase phase of TiO₂. The XRD and SEM observations on all the three samples indicate the formation of pure grains of nanosized titania. TGA curves of A and 7 suggest occurrence of multiple large thermal events.

Full text of DOI:10.1016/j.ica.2007.02.048

Inorganica Chimica Acta 360 (2007) 3002–3012
www.elsevier.com/locate/ica
Glycol modified cis-diisopropoxy-bis(N-phenylsalicylideneiminato)
titanium(IV). Syntheses, characterization, X-ray structures of
Ti{O(C6H4)CH@NPh}2(OPri)2, [{Ti(O(C6H4)CH@NPh)2}O]3 and
their low temperature transformation to pure grains of nanosized titania
a
a
a,
b
c
Namita Sharma , Vinita Sharma , Rakesh Bohra *, V.S. Raju , Ingo-Peter Lorenz ,
c
c
Christoph Krinninger , Peter Mayer
a
Department of Chemistry, University of Rajasthan, Jaipur 302 004, India
National Center for Compositional of Materials, Bhabha Atomic Research Center, Hyderabad 500 062, India
b
c
Department of Chemistry and Biochemistry, Ludwig Maximilian University, Munich, Germany
Received 4 December 2006; received in revised form 15 February 2007; accepted 24 February 2007
Available online 16 March 2007
Abstract
Ti(OPri)4 reacts with N-phenylsalicylideneimine in anhydrous benzene in 1:2 molar ratio to afford precursor [Ti{O(C6H4)CH@N-
Ph}2{OPri}2] (A). Further reactions of A with various glycols yield heteroleptic complexes of the type [Ti{O(C6H4)CH@NPh}2{O–
G–O}] [where –G– = (CH2)2 (1), (CH2CHCH3) (2), (CH3CHCHCH3) (3), (CH2CHC2H5) (4), C(CH3)2C(CH3)2 (5), (CH2)3 (6),
(CH2CH2CHCH3) (7), (CH3)2CCH2CHCH3 (8), (CH2)5 (9) and (CH2)6 (10)]. FAB mass spectroscopic studies of some of the derivatives
suggest their monomeric nature. Single crystal X-ray diffraction study of A reveals cis-orientation of the isopropoxy groups [O(3)–Ti(1)–
O(4) = 102.23(11)ꢀ] and distorted octahedral geometry around the titanium atom. Crystal structure of a trinuclear titanoxane
[{Ti(O(C6H4)CH@NPh)2}O]3, obtained from the partial hydrolysis of A, exhibit the formation of a six-membered Ti3O3ring. Complete
hydrolysis and low temperature (300–500 ꢀC) transformation of precursor A, as well as of 1 and 7 to pure TiO2 have also been achieved
using sol–gel technique. The XRD patterns indicate formation of anatase phase of TiO2. The XRD and SEM observations on all the
three samples indicate the formation of pure grains of nanosized titania. TGA curves of A and 7 suggest occurrence of multiple large
thermal events.
ꢁ 2007 Elsevier B.V. All rights reserved.
Keywords: Glycol modified titanium(IV) precursors; cis-Diisopropoxy-bis(N-phenylsalicylideneiminato) titanium(IV); Nanosized titanium
1. Introduction
The synthesis of metallo-organic compounds of titanium
has experienced strong advances not only due to their
applications in materials [6] and catalysis [7] but also due
to the interesting exhibition of structural variations [8].
The essential condition of the sol–gel technology for mate-
rial synthesis is good control over the rate of hydrolysis of
the precursor alkoxide to give suitable size, shape and por-
ous structures of TiO2. This could be achieved by partial
substitution of some of the alkoxy groups in Ti(OR)4
by suitable modifiers [8h,8i] such as b-diketone, N-
phenylsalicylideneimine, etc.
The use of Ti(OR)4 in sol–gel [1] and CVD [2] processes
for materials is very well known. TiO2 (the anatase TiO2 is
the most active phase in comparison to rutile and brukite
phases) an n-type semiconductor, finds a variety of applica-
tions in microelectronic devices [3] as well as in catalytic [4]
and photo- catalytic processes [5].
*
Corresponding author. Tel./fax: +91 141 2700364.
E-mail address: rkbohra@satyam.net.in (R. Bohra).
0020-1693/$ - see front matter ꢁ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.02.048

N. Sharma et al. / Inorganica Chimica Acta 360 (2007) 3002–3012
3003
Our previous studies on N-phenylsalicylideneimine
2.1.2. Preparation of Ti{O(C6H4)CH@NPh}2-
[OCH2CH2O] (1)
substituted aluminium(III)isopropoxide complexes indi-
cated that the modified ligand is capable of stabilizing alu-
minium(III) atoms in hexa- and tetra-coordination states in
the dinuclear complexes [9].
To the benzene solution of A (1.68 g, 3.01 mmol), 0.19 g
(3.06 mmol) of ethylene glycol was added. The reaction
mixture was refluxed and the progress of the reaction was
monitored by estimating liberated isopropanol. Remaining
solution was dried in vacuo to give a yellow solid [1.50 g,
m.p. 70 ꢀC].
All other derivatives have been prepared by a similar
route and their synthetic and analytical details are summa-
rized in Table 1.
In order to modify Ti(OPri)4, amenable for sol–gel
applications, we carried out the reactions of Ti(OPri)4 with
N-phenylsalicylideneimine to give a precursor material,
[Ti{O(C6H4)CH@NPh}2{OPri}2] (A). Further modifica-
tion of A with a variety of glycols yields heteroleptic deriv-
atives. Herein, we report the syntheses, characterization,
X-ray structures of Ti{O(C6H4)CH@NPh}2(OPri)2, [{Ti-
(O(C6H4)CH@NPh)2}O]3 and their low temperature trans-
formation to pure grains of nanosized titania by the sol–gel
technique.
2.2. Hydrolytic studies
2.2.1. Partial hydrolysis of A
When partial hydrolysis of A (ꢀ0.8 g) was carried out in
dichloromethane (ꢀ4 ml) with a few droplets of water
hanging on the inner surface of the stopper of the flask
some good quality crystals of [{Ti(O(C6H4)CH@N-
Ph)2}O]3 appeared in the following day. These were charac-
terized by single crystal X-ray diffraction analysis and
NMR spectroscopy. [1H NMR (in d ppm): 7.03 (m, N–
Ph); 6.72–7.45 (m, C6H4); 8.02 (s, CH@N), 13C{1H}
NMR (in d ppm): 117.2–133.1 (all aromatic carbons);
161.1 (CH@N)].
2. Experimental
All manipulations for the synthesis of A and 1–10
were carried out in strictly anhydrous conditions. Sol-
vents and reagents used were dried by conventional meth-
ods and distilled prior to use. Due precautions were taken
to handle health hazard chemicals, like benzene. Ti(OPri)4
[10] and N-phenylsalicylideneimine [11] were prepared as
reported in the literature. Titanium was estimated as
TiO2 [12] and the liberated isopropanol by oxidimetric
method [13].
2.2.2. Complete hydrolysis of A
Compound A (ꢀ3 g) was dissolved in isopropanol
(ꢀ31 ml). To this, a drop of water was added and stirred
for 24 h. Gelation occurred immediately. Some more quan-
tity of water (one drop) was added and the mixture was
stirred for 3 days. The whole mixture was dried in an oven
(at 100 ꢀC) overnight. A yellow coloured powder was
obtained. This was washed several times with n-hexane
and with isopropanol and sintered at 300 ꢀC for 2 h to give
a white powder, which was characterized as pure TiO2 [C,
0.25%; H, 1.11%; N, Nil].
IR spectra were recorded on SHIMADZU, FTIR
8400 Spectrometer in dry KBr powder. NMR [1H and
13C{1H}] data were collected on JEOL FX 300 FT NMR
spectrometer in CDCl3 solutions at 300.4 and 75.45 MHz
frequencies for H and 13C{1H} NMR, respectively. FAB
1
mass spectra of some of the complexes were obtained on
a JEOL SX 102/DA-6000 mass spectrometer using m-
nitrobenzyl alcohol matrix. Microanalyses were carried
out on a Heraeus Carlo Erba 1108 analyzer. XRD patterns
were obtained on a Philips-1840 diffractometer using Fe
˚
source at k 1.937 A. SEM images have been taken on a Phi-
2.2.3. Complete hydrolysis of 1 and 7
lips XL30 Scanning Electron Microscope with the powders
spread thin on a conducting carbon tape. Thermogravimet-
ric analysis was performed on Mettler Toledo Star SW 701
with the heating rate of 25–900/10 ꢀC.
Two more compounds Ti{O(C6H4)CH@NPh}2[OCH2-
CH2O] (1) and [Ti(OC6H4CH@NPh)2(OCH2CH2CHO-
CH2)] (7) were hydrolyzed using a similar path as adopted
for the complete hydrolysis of A, with the only difference
being drying it in an oven at 100 ꢀC. The yellow powder
was washed three times with acetone–n-hexane mixture to
remove the free ligand present in the system and sintered
at 500 ꢀC for 2 h. The organic content was almost nil [C,
0.26% and 0.60%; H, 0.77% and 1.08% in 1 and 7,
respectively].
2.1. Synthesis
2.1.1. Preparation of Ti{O(C6H4)CH@NPh}2(OPri)2 (A)
A benzene solution of Ti(OPri)4 (1.71 g, 6.02 mmol) was
added to a benzene solution of N-phenylsalicylideneimine
(2.38 g, 12.07 mmol). The mixture was heated up to reflux.
Completion of the reaction was monitored by estimating
the liberated isopropanol oxidimetrically in the azeotrope.
The resulting mixture was concentrated in vacuo to give a
yellow solid [3.33 g, m.p. 110 ꢀC]. This was recrystallized
from isopropanol to give single crystals suitable for X-ray
diffraction analysis.
2.3. Crystal structure analyses of Ti{O(C6H4)CH@NPh}2
(OPri)2 (A) and its hydrolysis product [{Ti(O(C6H4)-
CH@NPh)2}O]3
X-ray data were collected at 200 K with a Nonius Kap-
paCCD diffractometer equipped with a rotating anode and
graded multilayer X-ray optics to obtain monochrome

Table 1
Physical and analytical data for Ti{O(C6H4)CH@NPh}2(OPri)2 (A) and glycolatobis(N-phenylsalicylideneiminato) titanium(IV) complexes
Reactants (g)
Complexes
Colour (yield, g)
Elemental analyses (%) found (calc.)
M.p. (ꢀC)
Ti(OPri)4 HO(C6H4)CH@NPh
Liberated PriOH
C
H
N
Ti
1.71
A
2.38
HO–G–OH
0.19
0.22
0.31
0.31
0.48
0.29
0.33
Ti{O(C6H4)CH@NPh}2(OPri)2 (A)
Ti{O(C6H4)CH@NPh}2{OCH2–CH2–O} (1)
Yellow (3.33)
Yellow (1.49)
0.70 (0.72)
0.34 (0.36)
68.7 (68.8) 6.0 (6.1) 5.0 (5.0) 8.5 (8.6) 110
67.0 (67.2) 4.9 (4.8) 5.7 (5.6) 9.5 (9.6)
70
1.67
1.65
1.94
1.91
2.25
2.15
2.03
2.09
1.15
1.73
a
Ti{O(C6H4)CH@NPh}2{OCH2–CH(O)–CH3} (2)
Ti{O(C6H4)CH@NPh}2{CH3–CH(O)–CH(O)–CH3} (3)
Ti{O(C6H4)CH@NPh}2{OCH2–CH(O)–CH2–CH3} (4)
Ti{O(C6H4)CH@NPh}2{OC(CH3)2–C(CH3)2O} (5)
Ti{O(C6H4)CH@NPh}2{OCH2–CH2–CH2O} (6)
Ti{O(C6H4)CH@NPh}2{OCH2–CH2–CH(O)–CH3} (7)
Ti{O(C6H4)CH@NPh}2{(CH3)2C(O)–CH2–CH(O)–CH3} (8) Yellow (2.07)
Ti{O(C6H4)CH@NPh}2{OCH2–(CH2)3–CH2O} (9)
Ti{O(C6H4)CH@NPh}2{OCH2–(CH2)4–CH2O} (10)
Yellow (1.51)
Dark Yellow (1.82) 0.38 (0.42)
Dark Yellow (1.80) 0.39 (0.42)
Yellow (2.22)
Yellow (1.97)
Yellow (1.91)
0.32 (0.35)
67.5 (67.7) 5.4 (5.1) 5.7 (5.4) 9.3 (9.3)
67.9 (68.2) 5.1 (5.3) 5.2 (5.3) 9.1 (9.1)
68.1 (68.2) 5.7 (5.3) 5.1 (5.3) 9.0 (9.1)
80
75
74
0.38 (0.48)
0.41 (0.46)
0.44 (0.43)
0.40 (0.45)
0.24 (0.25)
0.32 (0.37)
68.9 (69.1) 5.7 (5.8) 4.9 (5.0) 8.6 (8.6) 100
67.3 (67.7) 5.4 (5.1) 5.3 (5.4) 9.3 (9.3) 138
68.1 (68.2) 5.4 (5.3) 5.5 (5.3) 9.0 (9.1)
69.0 (69.1) 5.7 (5.8) 5.0 (5.0) 8.6 (8.6)
68.5 (68.6) 5.6 (5.6) 5.1 (5.2) 8.9 (8.8)
69.0 (69.1) 5.8 (5.8) 4.9 (5.0) 8.6 (8.6)
69
a
0.44
0.21
0.36
a
Yellow (1.13)
Yellow (1.72)
98
Hydrolyzed during measurements.

N. Sharma et al. / Inorganica Chimica Acta 360 (2007) 3002–3012
3005
Table 2
Crystallographic data of compounds Ti{O(C6H4)CH@NPh}2(OPri)2 (A) and [{Ti(O(C6H4)CH@NPh)2}O]3 Æ 2CH2Cl
Ti{O(C6H4)CH@NPh}2(OPri)2
[{Ti(O(C6H4)CH@NPh)2}O]3 Æ 2CH2Cl2
Empirical formula
Formula weight (g molꢁ1
Crystal size (mm)
Crystal colour, habit
Crystal system
C32H34N2O4Ti
558.490
0.21 · 0.15 · 0.09
200(2)
C80H64Cl4N6O9Ti3
1538.81
0.17 · 0.14 · 0.1
yellow platelet
monoclinic
P2(1)/c
23.153(5)
14.121(3)
23.025
90
92.86(3)
90
7519(3)
)
triclinic
ꢀ
Space group
P1
˚
a (A)
11.4790(2)
13.3095(3)
21.3403(4)
106.1305(12)
92.5176(14)
107.7134(8)
2953.98(10)
4
˚
b (A)
˚
c (A)
a (ꢀ)
b (ꢀ)
c (ꢀ)
3
˚
Volume (A )
Z
4
Dcalc (g cmꢁ3
)
1.25581(4)
0.327
1176
1.3594(5)
0.514
3168
Absorption coefficient (mmꢁ1
F(000)
)
Index ranges
ꢁ14 6 h 6 14,
ꢁ16 6 k 6 16,
ꢁ26 6 l 6 26
3.20–26.00
21759
11535
6999
701/2
ꢁ26 6 h 6 26,
ꢁ16 6 k 6 15,
ꢁ26 6 l 6 26
3.16–24.12
43233
11926
8850
904/0
h Range (ꢀ)
Reflections collected
Independent reflections
Observed reflections
Parameter/restrains
R1/wR2 (all data)
R1/wR2 (final)
0.1091/0.1607
0.0567/0.1432
1.016
0.0530/0.1277
0.0755/0.1389
1.035
Goodness of fit
3
˚
Minimum/maximum qe (e A )
Temperature (K)
Diffractometer used
Scan type
Solution
Refinement
ꢁ0.591/0.547
ꢁ1.014/1.107
200(2)
200(2)
Nonius Kappa CCD
area detection
SHELXS-97
SHELXL-97
Nonius Kappa CCD
area detection
SHELXS-97
SHELXL-97
˚
MoKa radiation (k = 0.71073 A). Data collection and cell
refinement gave cell constants corresponding to triclinic
cells for (A) and monoclinic cells for [{Ti(O(C4H4)CH@N-
Ph)2}O]3 whose dimensions and other experimental param-
eters are given in Table 2. The structures were solved with
direct methods with SIR-97 and refined with SHELXL-97 by
full-matrix least-squares on F2. All but the disordered
non-hydrogen atoms were refined anisotropically, the
hydrogen atoms were calculated in geometrically optimized
positions.
Table 3
Fragmented molecular ions/m/e values of Ti{O(C6H4)CH@NPh}2{OPri}2 (A) and Ti{O(C6H4)CH@NPh}2{CH3–CH(O)–CH(O)–CH3} (3)
Complex
Fragmented ions
m/e Value
Ti{O(C6 H4)CH@NPh}2{OPri}2 (A)
[Ti{O(C6H4)CH@NPh}2{OPri}2
[Ti{O(C6H4)CH@NPh}2{OPri}{OCH3}]+
[Ti{O(C6H4)CH@NPh}2{O}]+
[Ti{O(C6H4)CH@NPh}2]+
558
530
456
440
349
260
244
[Ti{O(C6H4)CH@NPh}{O(C6H4)CH}]+
[Ti{O(C6H4)CH@NPh}{O}]+
[Ti{O(C6H4)CH@NPh}]+
Ti{O(C6H4)CH@NPh}2{CH3–CH(O)–CH(O)–CH3} (3)
[Ti{O(C6H4)CH@NPh}2{CH3–CH(O)–CH(O)–CH3}]1+
[Ti{O(C6H4)CH@NPh}2{CH3–CH(O)–OH}]+
[Ti{O(C6H4)CH@NPh}2{CH(O)–OH}]+
[Ti{O(C6H4)CH@NPh}{O(C6H4)CH}{CH(O)–OH}]+
[Ti{O(C6H4)CH@NPh}{(C6H4)CH}{CH(O)–OH}]+
[Ti{O(C6H4)CH@NPh}{(C6H4)CH}{H2O}]+
[Ti{O(C6H4)CH@NPh}{(C6H4)]+
529
501
486
395
379
351
320
244
[Ti{O(C6H4)CH@NPh}]+

3006
N. Sharma et al. / Inorganica Chimica Acta 360 (2007) 3002–3012
Table 4
Some important IR absorption of Ti{O(C6H4)CH@NPh}2{OPri}2 (A) and glycolatobis(N-phenylsalicylideneiminato) titanium(IV) complexes
m(C@N)
m(C–O)
m(Ti–O)(glycol)
m(Ti–N)
Ti{O(C6H4)CH@NPh}2(OPri)2 (A)
Ti{O(C6H4)CH@NPh}2{OCH2–CH2–O} (1)
1545
1558
1557
1553
1560
1558
1555
1550
1555
1557
1554
985
1030
1025
1015
1000
1000
1032
1022
1032
1030
1080
609
610
610
625
615
627
615
625
622
620
615
478
475
478
472
480
488
470
472
478
480
480
Ti{O(C6H4)CH@NPh}2{OCH2–CH(O)–CH3} (2)
Ti{O(C6H4)CH@NPh}2{CH3–CH(O)–CH(O)–CH3} (3)
Ti{O(C6H4)CH@NPh}2{OCH2–CH(O)–CH2–CH3} (4)
Ti{O(C6H4)CH@NPh}2{OC(CH3)2–C(CH3)2O} (5)
Ti{O(C6H4)CH@NPh}2{OCH2–CH2–CH2O} (6)
Ti{O(C6H4)CH@NPh}2{OCH2–CH2–CH(O)–CH3} (7)
Ti{O(C6H4)CH@NPh}2{(CH3)2C(O)–CH2–CH(O)–CH3} (8)
Ti{O(C6H4)CH@NPh}2{OCH2–(CH2)3–CH2O} (9)
Ti{O(C6H4)CH@NPh}2{OCH2–(CH2)4–CH2O} (10)
a
All these absorptions are of strong intensity.
TifOðC6H4ÞCH@NPhg ðOPriÞ þ HO–G–OH
3. Results and discussion
2
2
benzene
ƒƒƒ! TifOðC6H4ÞCH@NPhg2ðO–G–OÞ þ 2PriOH "
Reactions of N-phenylsalicylideneimine with Ti(OPri)4
in 1:2 molar ratio in anhydrous benzene yield
Ti{O(C6H4)CH@NPh}2(OPri)2 (A):
ð1–10Þ
[where –G– = (CH2)2 (1), (CH2CHCH3) (2), (CH3CHCH-
CH3) (3), (CH2CHC2H5) (4), C(CH3)2C (CH3)2 (5),
(CH2)3 (6), (CH2CH2CHCH3) (7), (CH3)2CCH2CHCH3-
(8), (CH2)5 (9), (CH2)6 (10).]
The progress of the above reactions was monitored by
estimating liberated isopropanol in the benzene-
isopropanol azeotrope by oxidimetric method. All these
reactions were found to be quite facile and quantitative
yielding yellow coloured sharp melting solids. These com-
plexes are soluble in common organic solvents. The FAB
TiðOPriÞ þ 2HOðC6H4ÞCH@NPh
4
benzene
TifOðC H ÞCH@NPhg ðOPriÞ þ 2PriOH "
ƒƒƒ!
6
4
ðAÞ 2
2
Further reaction of A with glycols in 1:1 molar ratio affor-
ded heteroleptic complexes of the type Ti{O(C6H4)CH@N-
Ph}2(O–G–O) (1–10)
Table 5
1H and 13C{1H} NMR spectral data for Ti{O(C6H4)CH@NPh}2(OPri)2 (A) and glycolatobis(N-phenylsalicylideneiminato) titanium(IV) complexes
Complex
1H NMR data (d ppm)
1.22 (d, 12H, J = 6.08 Hz, CH3); 4.94 (m, 2H, CH); 7.00 (m, 39.7 (CH3); 76.6 (CH); 116.4–148.0 (all
10H, N–Ph); 6.54–7.46 (m, 8H, C6H4); 7.93 (s, 2H, CH@N) aromatic carbons); 160.7 (CH@N)
Ti{O(C6H4)CH@NPh}2{OCH2–CH2– 4.43 (b, 4H, OCH2); 7.01 (m, 10H, N–Ph); 7.21–7.47 (m, 8H, 76.4 (OCH2); 117.0–148.5 (all aromatic
13C{1H} NMR data (d ppm)
Ti{O(C6H4)CH@NPh}2(OPri)2 (A)
O} (1)
C6H4); 7.89 (s, 2H, CH@N)
carbons); 160.9 (CH@N)
Ti{O(C6H4)CH@NPh}2{OCH2–
CH(O)–CH3} (2)
1.21 (d, 3H, 6.04 Hz, CH3); 4.50 (br, 2H, OCH2); 4.83 (br, 1H, 25.0 (CH3); 56.0 (OCH2); 79.5 (OCH); 117.2–
OCH); 6.97 (m, 10H, N–Ph); 7.19–7.48 (m, 8H, C6H4); 8.30 (s, 148.4 (all aromatic carbons); 161.1 (CH@N)
2H, CH@N)
Ti{O(C6H4)CH@NPh}2{CH3–
CH(O)–CH(O)–CH3} (3)
1.27 (m, 6H, CH3); 5.50 (br, 2H, OCH); 7.09 (m, 10H, N–Ph); 24.8 (CH3); 76.4 (OCH); 117.0–148.2 (all
7.21–7.36 (m, 8H, C6H4); CH@N (not observed)
aromatic carbons); 162.5 (CH@N)
Ti{O(C6H4)CH@NPh}2{OCH2–
CH(O)–CH2–CH3} (4)
1.10 (m, 3H, CH3); 1.40 (m, 2H, CH2); 4.57 (br, 2H, OCH2); 25.2 (CH3); 27.7 (CH2); 63.9 (OCH2); 80.0
4.87 (m, 1H, OCH); 7.06(m, 10H, N–Ph); 7.23–7.45 (m, 8H, (OCH); 117.2–148.4 (all aromatic carbons);
C6H4); 7.91 (s, 2H, CH@N)
1.28 (s, 12H, CH3); 7.04 (m, 10H, N–Ph); 7.13–7.44 (m, 8H, 24.7 (CH3); 101.4 (CO); 117.2–148.4 (all
C6H4); 8.10 (s, 2H, CH@N) aromatic carbons); 161.0 (CH@N)
161.0 (CH@N)
Ti{O(C6H4)CH@NPh}2{OC(CH3)2–
C(CH3)2O} (5)
Ti{O(C6H4)CH@NPh}2{OCH2–CH2– 2.19 (m, 2H, CH2); 4.72, 4.83 (br, 4H, each OCH2); 6.95 (m, 32.1 (CH2); 73.9 (OCH2); 117.1–148.3 (all
CH2O} (6)
10H, N–Ph); 7.24–7.40 (m, 8H, C6H4); 8.02 (s, 2H, CH@N)
aromatic carbons); 161.0 (CH@N)
Ti{O(C6H4)CH@NPh}2{O CH2–
CH2–CH(O)–CH3} (7)
1.21 (d, 3H, 5.86 Hz, CH3); 2.49 (m, 2H, CH2); 4.70 (m, 2H, 23.3 (CH3); 32.0 (CH2); 53.0 (OCH2); 79.6
OCH2); 5.00 (m, 1H, OCH); 6.92 (m, 10H, N–Ph); 7.15–7.45 (OCH); 117.2–149.0 (all aromatic carbons);
(m, 8H, C6H4); 7.96 (s, 2H, CH@N)
162.6 (CH@N)
Ti{O(C6H4)CH@NPh}2{(CH3)2C(O)– 1.38 (br, 9H, all CH3); 2.01 (br, 2H, CH2); 5.12 (br, 1H, OCH); 23.6, 26.3, 27.4 (each CH3); 31.5 (CH2); 51.5
CH2–CH(O)–CH3} (8)
6.95 (m, 10H, N–Ph); 7.25–7.45 (m, 8H, C6H4); 8.00 (s, 2H,
(OCH); 83.7 (CO); 117.2–150.1 (all aromatic
CH@N)
carbons); 162.6 (CH@N)
Ti{O(C6H4)CH@NPh}2{OCH2–
(CH2)3–CH2O} (9)
1.36 {br, 2H, CH2 (3)}; 1.49 {br, 4H, CH2 (2,4)}; 3.55 {br, 4H, 21.9 {CH2 (3)}; 33.3 {CH2 (2,4)}; 62.6 {OCH2
OCH2 (1,5)}; 6.84 (m, 10H, N–Ph); 7.16–7.34 (m, 8H, C6H4); (1,5)}; 117.2–148.4 (all aromatic carbons); 161.0
7.51 (s, 2H, CH@N)
(CH@N)
Ti{O(C6H4)CH@NPh}2{OCH2–
(CH2)4–CH2O} (10)
1.72 {br, 4H, CH2 (3)}; 2.00 {br, 4H, CH2 (2)}; 5.84 {br, 4H, 25.0 {CH2 (3)}; 31.0 {CH2 (2)}; 73.1 (OCH2);
CH2 (1)}; 7.06 (m, 10H, N–Ph); 7.26–7.44 (m, 8H, C6H4); 7.97 117.1–148.3 (all aromatic carbons); 161.0
(s, 2H, CH@N)
(CH@N)

N. Sharma et al. / Inorganica Chimica Acta 360 (2007) 3002–3012
3007
Table 6
mass spectral studies of two of the representative com-
i
˚
pounds Ti{O(C6H4)CH@NPh}2(OPri)2 (A) and Ti{O(C6H4)-
CH@NPh}2(CH3CH(O)CH(O)CH3) (3) (Table 3) indicate
their monomeric nature. Appearance of some molecular
ion peaks at higher m/e than the molecular ion in the
FAB mass spectra may be due to reassociation of the
fragments.
Selected bond lengths (A) and angles (ꢀ) of Ti{O(C6H4)CH@NPh}3(OPr )2
(A)
Ti1–O1
Ti1–O2
Ti1–O3
Ti1–O4
Ti1–N1
Ti1–N2
O1–C1
O2–C14
O3–C27
O4–C30
N1–C7
N1–C8
N2–C21
N2–C20
C1–C6
1.920(2)
1.903(2)
1.805(2)
1.790(2)
2.286(3)
2.320(3)
1.321(3)
1.311(4)
1.403(6)
1.383(5)
1.296(4)
1.441(4)
1.442(4)
1.283(4)
1.408(5)
C1–C2
C2–C3
C3–C4
C4–C5
C5–C6
C6–C7
C8–C9
C8–C13
C9–C10
1.403(4) O1–Ti1–O2
1.364(4) O1–Ti1–O3
1.389(5) O1–Ti1–O4
1.362(4) O1–Ti1–N1
1.408(4) O1–Ti1–N2
1.431(4) O2–Ti1–O3
1.384(4) O2–Ti1–O4
1.374(5) O2–Ti1–N1
1.393(6) O2–Ti1–N2
162.55(10)
95.62(9)
96.57(9)
81.11(9)
86.41(8)
95.47(10)
94.19(10)
85.07(9)
IR spectra of all these derivatives have been recorded
in KBr and some relevant data are summarized in Table
4. Absence of hydroxyl group absorption of N-phenylsal-
icylideneimine as well as of glycols in the IR spectra of
all these derivatives indicates deprotonation and concom-
itant bond formation of the ligand moieties with the tita-
nium atom. Strong intensity absorption at around
575 cmꢁ1 in all the derivatives may be assigned to
m(Ti–O)(salen). Absorption in the region 610–627 cmꢁ1
in the spectrum of all the glycolato derivatives (1–10)
is due to m(Ti–O)(glycol) mode [14]. A downfield shift
of m(C@N) was observed in all the complexes as com-
pared to the free ligand indicating the chelating mode
of attachment of the ligand moiety. This fact was further
supported by the appearance of a new absorption band
in the region 470–488 cmꢁ1, due to m(Ti–N) mode in all
these complexes [15].
80.86(9)
C10–C11 1.365(6) O3–Ti1–O4
C11–C12 1.376(6) O3–Ti1–N1
C12–C13 1.375(6) O3–Ti1–N2
O4–Ti1–N1
102.23(11)
166.93(9)
86.57(10)
90.74(10)
170.34(10)
80.61(9)
O4–Ti1–N2
N1–Ti1–N2
corresponding oxygen atoms of both chelates are also
trans-positioned. The bond lengths of Ti–O within the che-
˚
late ring (Ti1–O1 1.920(2), Ti1–O2 1.903(2) A) are about
i
˚
0.10 A longer than those towards the OPr -ligands (Ti1–
˚
˚
O3/O4 ꢂ 1.80 A). The distances Ti–N differ only slightly
1H and 13C{1H} NMR spectra of all these derivatives
have been recorded in CDCl3 and the data are given in
Table 5. Consistent with the IR spectral observations, the
hydroxyl proton resonances of the free N-phenylsalicylide-
neimine (at d 13.31 ppm) and of the glycols (around d 2.0–
around 2.30 A, whereby the shorter one (Ti1–N1
˚
2.286(3) A) corresponds with the longer O–C bonds (O3–
C27 1.403(6) A) and vice versa Ti1–N2 2.320(3), O4–C30
1.383(5) A. The distortion from regular octahedron
arises from the smaller angles than 180ꢀ (O1–Ti1–O2
162.55(10), O3–Ti1–N1 166.93(9), O4–Ti1–N2 170.34(10)ꢀ),
O3–Ti1–N1 166.93(9), as well as from the different angles
(O3–Ti1–O4 102.23(11), N1–Ti1–N2 80.61(9)ꢀ). The six-
membered titanacyclic system is exactly planar, the N-
˚
˚
1
3.5 ppm) were absent in the H NMR spectra of all these
derivatives. A significant downfield shift in the CH@N pro-
ton resonance (0.31–1.10 ppm) of N-phenylsalicylidenei-
mine moiety on complexation suggests bidentate mode of
attachment of this ligand via O and N in all these com-
plexes which gets further support from X-ray diffraction
study of A. Appearance of only one doublet for isopro-
pyl-Me groups in the 1H NMR of A, indicates its fluxional
behaviour in solution. These methyl groups appear to be
diastereotopic from the crystal structure analysis.
However, no significant shift in the CH@N carbon res-
onance in the 13C{1H} NMR spectra of all these deriva-
tives was observed.
Table 7
˚
Selected bond lengths (A) and angles (ꢀ) of [{Ti(O(C6H4)CH@NPh)2}O]3
Ti1–O8 1.812(3) O8–Ti1–O9
Ti1–O9 1.823(3) O8–Ti2–O10
Ti2–O8 1.852(3) O9–Ti3–O10
Ti2–O10 1.826(3) Ti1–O8–Ti2
Ti3–O9 1.808(3) Ti1–O9–Ti3
96.53(12) O5–Ti2–O8
96.67(12) O5–Ti2–O10 98.61(12)
97.32(12) N5–Ti2–O8 86.76(12)
138.86(16) N5–Ti2–O10 176.59(12)
142.25(16) N5–Ti2–N1 83.77(12)
97.55(12)
Ti3–O10 1.835(3) Ti2–O10–Ti3 136.87(15) N1–Ti2–O10 92.85(12)
Other proton and carbon resonances for N-
phenylsalicylideneimine [9] and glycolate [14] moieties
appeared at the expected positions and with desirable mul-
tiplicities in all these derivatives.
Selected bond lengths and angles for Ti{O(C6H4)-
CH@NPh}2(OPri)2 (A) and its hydrolysis product
[{Ti(O(C6H4)CH@NPh)2}O]3 are summarized in Tables 6
and 7 and their ORTEP plots are displayed in Figs. 1
and 2, respectively.
The molecular structure of A reveals two formula units
in the asymmetric cell. They show a distorted octahedrally
configurated Ti centre with cis-orientation of both isoprop-
oxy and both N-phenylsalicylideneimine ligands. Each
nitrogen atom of the five-membered N,O-chelate lies in
trans-position to the oxygen atom of the OPri ligand, the
Ti1–O2 1.916(3) O1–Ti2–O5
Ti1–O3 1.902(3) O1–Ti2–N1
Ti1–N2 2.326(3) O1–Ti2–N5
Ti1–N3 2.351(3) O1–Ti2–O8
Ti2–O1 1.907(3) O1–Ti2–O10
Ti2–O5 1.886(3) O5–Ti2–N1
Ti2–N1 2.317(3) O5–Ti2–N5
Ti2–N5 2.318(4)
Ti3–O4 1.913(3)
Ti3–O6 1.896(3)
Ti3–N4 2.322(3)
Ti3–N6 2.295(4)
156.79(12) N1–Ti2–O8 170.46(12)
80.28(12) Ti2–N1–C7 124.6(3)
82.64(12) Ti2–N1–C1 119.8(2)
97.46(12) N1–C7–C8
97.14(12) C7–N1–C1
82.02(12) C7–C8–C9
80.61(12) C8–C9–O1
126.7(4)
115.3(4)
122.8(4)
120.9(4)
C9–O1–Ti2 140.2(3)
N1–C1
N1–C7
C7–C8
C8–C9
O1–C9
1.447(5)
1.290(5)
1.439(6)
1.408(6)
1.331(5)

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N. Sharma et al. / Inorganica Chimica Acta 360 (2007) 3002–3012
bonded phenyl substituent is turned off the chelate plane of
about 62ꢀ.
atoms of the ring and the N and O atoms of two chelating
N-phenylsalicylideneiminato ligands in cis-position. The
bonds Ti–O within the titanoxane ring lie between 1.80
The trinuclear titanoxane obtained by partial hydrolysis
of A crystallizes together with two molecules of CH2Cl2. Its
molecular structure reveals a non-planar six-membered
ring system of alternating three titanium and three oxygen
atoms. It is interesting to note here that in a similar tita-
noxane, Ti(acac)2O (with O,O0-chelating ligand) a dimer
with planar Ti2O2 ring was obtained [8h]. Each Ti centre
exhibits a distorted octahedral configuration with two O
˚
˚
and 1.85 A (Ti3–O10 1.808(3), Ti2–O8 1.852(3) A) and
are a little bit shorter than those towards the chelate system
˚
˚
with 1.88–1.91 A (Ti2–O5 1.886(3), Ti1–O2 1.916(3) A).
Within the bent ring system the three Ti-centred
angles are about 97ꢀ (O8–Ti–O9 96.53(12)ꢀ, O9–Ti3–O10
97.32(12)ꢀ), whereas the angles Ti–O–Ti differ more,
namely between 136.87(15)ꢀ for Ti2–O10–Ti3 and
142.25(16)ꢀ for Ti1–O9–Ti3. In the following lines, only
the bond lengths and angles around Ti2 centre are
discussed according to the labels as shown in Fig. 2. The
values for Ti2 are representative also for Ti1 and Ti3.
The very long Ti–N distances vary similarly as Ti–O do
˚
with values between 2.29 and 2.35 A (Ti3–N6 2.295(4),
˚
Ti1–N3 2.351(3) A). The distortion of ideal octahedral
geometry mainly derives from the three trans-angles
O1–Ti2–O5 156.79(12)ꢀ, N1–Ti2–O8 170.46(12)ꢀ and N5–
Ti2–O10 176.59(12)ꢀ as well as from all cisoide angles.
Whereas the four O–Ti–O angles are enlarged to 97–98ꢀ,
all O–Ti–N angles within the titanacyle are reduced to
80–82ꢀ. Those, however, between imine N atoms and tita-
noxane O atoms lie about 90ꢀ (N5–Ti2–O8 86.76(12)ꢀ, N1–
Ti2–O10 92.85(12)ꢀ). The bond lengths and angles of the
chelate ring are very similar to those found for A. The
imine distance N1–C7 1.290(5) pm is shorter than the phe-
nolic one O1–C9 1.331(5) as well as the aromatic bond C8–
˚
˚
C9 1.408(6) A is shorter than C7–C8 1.439(6) A. Within the
six-membered titanacycle, the largest angle is 140.2(3)ꢀ
for C9–O1–Ti2, whereas the smallest is 89.28(12)ꢀ for
O1–Ti2–N1.
Fig. 1. Ortep plot of Ti{O(C6H4)CH@NPh}2(OPri)2 (A) (25% probability,
H atoms are omitted).
Fig. 2. Ortep plot of [{Ti(O(C6H4)CH@NPh)2}O]3 (25% probability) with only one complete chelate ligand on Ti2, the phenyl groups of the other five are
omitted.

N. Sharma et al. / Inorganica Chimica Acta 360 (2007) 3002–3012
3009
The interplanar angle between the chelating plane O1–
O
Ti
O
O
Ti
O
Ti2–N1 and that of the planar chelate ligand is about
11ꢀ. The N-phenyl substituent is turned off the major plane
of the chelate by about 46ꢀ.
OPri
OPri
6 HOH
N
OH
OH
N
3
3
N
N
Modification of Ti(OPri)4 with N-phenylsalicylidenei-
mine provides some stability to the product, A, towards
hydrolysis. An intermediate hydrolysis product, [{Ti(O-
(C6H4)CH@NPh)2}O]3, was obtained when controlled
hydrolysis of A was carried out. It is interesting to mention
here that the formation of the same product is reproduc-
ible. This suggests that it is a kinetically stable species dur-
ing hydrolysis pathway of A (Scheme 1). Complete
hydrolysis of A and sintering at 300 ꢀC yields pure TiO2
(as confirmed from its XRD—Fig. 3a). Similarly, complete
hydrolysis of further glycol modified 1 and 7 afforded pure
TiO2 at a sintering temperature of 500 ꢀC (Fig. 3b and c).
It is worthwhile to mention here that a comparison of
the XRD patterns of the three samples of pure TiO2
obtained during the course of the present investigation
reveals formation of pure anatase phase at low tempera-
tures (at 300 ꢀC for A, at 500 ꢀC for 1 and 7 as compared
to >600 ꢀC reported in the literature) [6a].
- 3 H2O
N
N
O
O
O
Ti
N
O
(TiO2)n
Ti
O
O
N
O
O
Ti
O
N
N
Scheme 1.
Calculations of the average particle size of TiO2 grains
obtained from A, 1 and 7 using Debye Scherrer equation
[16] for the longest peak in the XRD-spectra reveals aver-
age particle size 12.3 nm for A, 9.7 nm for 1 and 8.9 nm
for 7. Both Secondary electron and backscattered electron
images of TiO2obtained from A were recorded at magnifi-
cations of 1000·, 4000· and 10000· to compare the grain
sizes (Fig. 4a–d).
Fig. 3. XRD patterns for pure TiO2 obtained from (a) A, (b) 1 and (c) 7.

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N. Sharma et al. / Inorganica Chimica Acta 360 (2007) 3002–3012
Fig. 5. SEM images of pure TiO2 obtained from (a) A, (b) 1 and (c) 7.
sized grains. Only slight variation of the grains at two differ-
ent temperatures was observed. The minimum particle sizes
of TiO2 grains appeared to be obtained from 7.
Thermal gravimetric analysis (TGA) was undertaken on
two of the derivatives, A and 7 (Fig. 6a and b). Appearance
of multiple weight loss steps in the TGA curves of both A
and 7 indicate multiple thermal events due to organic pyro-
lysis. It is of interest to note that compound 7 is thermally
less stable as compared to A.
Fig. 4. SEM images of pure TiO2 obtained from A sintered at 300 ꢀC: (a)
1000· SE image, (b) 4000· SE image, (c) 10000· SE image and (d) 10000·
BSE image.
4. Conclusion
Further, scanning electron micrograph of the products
obtained from A (300 ꢀC), 1 (500 ꢀC) and 7 (500 ꢀC)
(Fig. 5a–c) showed agglomerated particles made up of nano-
The single crystal X-ray diffraction studies of two of the
derivatives Ti{O(C6H4)CH@NPh}2(OPri)2 (A) and [{Ti(O-
(C4H4)CH@NPh)2}O]3 revealed cis-orientation of the N, O

N. Sharma et al. / Inorganica Chimica Acta 360 (2007) 3002–3012
3011
Fig. 6. TGA curves (weight % vs. temperature ꢀC) of (a) A and (b) 7.
atoms of salicylideneimine moiety. Complete hydrolysis of
Acknowledgements
some of the derivatives in isopropanol, afforded pure nano-
crystalline anatase TiO2 as reflected by XRD and SEM
studies. It may be inferred from the above results that the
modified glycolatobis(N-phenylsalicylideneiminato) tita-
nium(IV) complexes are potential precursors for material
synthesis by sol–gel technology.
We are thankful to UGC- and DST-New Delhi, for
financial support. V.S. is thankful to UGC for PDF. We
thank the Department of Physics, University of Rajasthan,
Jaipur, for XRD and CSMCRI, Bhavnagar for TGA. We
also thank Bernd Neumann, LMU Munich, for his helpful
calculations (X-ray analysis).
5. Supplementary material
References
CCDC 623848 and 628329 contain the supplementary
crystallographic data for Ti{O(C6H4)CH@NPh}2(OPri)2
(A) and [{Ti(O(C4H4)CH@NPh)2}O]3. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223-336-033; or e-mail: deposit
@ccdc.cam.ac.uk.
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