INTERNATIONAL JOURNAL OF RESEARCH AND SCIENTIFIC INNOVATION (IJRSI)
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Synthesis of Derivatives of Heterobimetallic [Sn(II);Ti(IV)]-µ-oxo-
isopropoxide with Schiff Bases
Jashmer Singh
DAV College (Lahore) Ambala City-134003, Haryana, India
DOI: https://dx.doi.org/10.51244/IJRSI.2025.1210000195
Received: 02 November 2025; Accepted: 08 November 2025; Published: 15 November 2025
ABSTRACT
With an aim to enhance the stability and volatility of the heterometallic [Sn(II);Ti(IV)]-µ-oxo-isopropoxide a
number of substitution reactions of the complex are carried out with different schiff bases viz Salicylidene
aniline (HSB
1
), Salicylidene-o-toluidene (HSB
2
) and Salicylidene-p-chloroaniline (HSB
3
) have been
performed in different molar ratios in refluxing benzene resulting in to the formation of products of the type
[SnO
2
Ti
2
(O-i-Pr)
5
(SB)], [SnO
2
Ti
2
(O-i-Pr)
4
(SB)
2
], [SnO
2
Ti
2
(O-i-Pr)
3
(SB)
3
] and [SnO
2
Ti
2
(O-i-Pr)
2
(SB)
4
]. The
schiff base derivatives have been characterized by elemental, liberated isopropanol and spectral analysis (IR,
1
H ,
13
C NMR).
Keywords: Metal alkoxide, schiff base, Tin, Titanium.
INTRODUCTION
Interest in the synthesis and properties of the molecular precursors for metal oxide and nonoxide nanomaterials
are due to their inherent advantages during materials processing via soft chemical routes [Sol-Gel, Metal-
Organic Chemical Vapor Deposition (MOCVD), Metal-Organic Decomposition (MOD)]
1-8
.Design and
synthesis of heterometallic derivatives with suitable properties can be used as single source precursors for
generating advanced complex materials containing more than one metal
9-18
. Classical or functional metal
alkoxides, which have appropriate hydrolysis and condensation characteristics, are the preferred single-source
precursors for oxide ceramic materials via sol-gel processing.
19-29
Metal alkoxides are frequently employed as sol-gel molecular precursors in the fabrication of nanomaterials.
The addition of chelating ligands to metal alkoxide precursors greatly increases their stability. This, in turn,
slows the otherwise rapid hydrolysis–condensation kinetics.
30-32
The condensation rate is slowed because
bidentate or multidentate chelates also occupy other coordination sites on the metal center as well as tethering
alkoxy groups that are prone to water attack.
33
The catalytic properties of metal alkoxides have also been well established. The μ-oxo alkoxides have been
reported to be amongst the best catalysts for polymerization of heterocyclic monomers like lactones, oxiranes,
thiiranes and epoxides.
34,35
The alkoxides of molybdenum and tungsten in their middle oxidation states have
been used as model for reductive cleavage of carbon monoxide to carbides and oxides via Fisher-Tropsch
reaction.
36
The above features underline the importance and utility of μ-oxo compounds, it was therefore considered
worthwhile to synthesize schiff base derivatives of heterobimetallic [Sn(IV); Ti(IV)] -μ-oxoisopropoxide.
RESULT AND DISCUSSION
A number of reactions of heterobimetallic [Sn(II);Ti(IV)]-µ-oxo-isopropoxide with bidentate Schiff bases
(HSB) i.e. Salicylidene aniline (HSB
1
), Salicylidene-o-toluidene (HSB
2
) and Salicylidene-p-chloroaniline
(HSB
3
) have been performed in different molar ratios in refluxing benzene resulting in to the formation of
INTERNATIONAL JOURNAL OF RESEARCH AND SCIENTIFIC INNOVATION (IJRSI)
ISSN No. 2321-2705 | DOI: 10.51244/IJRSI |Volume XII Issue X October 2025
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products of the type [SnO
2
Ti
2
(O-i-Pr)
5
(SB)], [SnO
2
Ti
2
(O-i-Pr)
4
(SB)
2
], [SnO
2
Ti
2
(O-i-Pr)
3
(SB)
3
] and
[SnO
2
Ti
2
(O-i-Pr)
2
(SB)
4
]. The general reaction can be given as follows:
Where n=1-4 and HSB =Schiff bases
The isopropanol liberated during the course of reaction is collected azeotropically (isopropanol-benzene) and
estimated oxidimetrically to check the progress of the reaction and it has been observed that only four out of
six of isopropoxy groups could be replaced by Schiff bases. Further replacement of isoproxy groups could not
be achieved even with an excess of ligand (Schiff base) and prolonged refluxing time (approx. 20 hours) in
benzene.
All the Schiff base derivative of [Sn(II);Ti(IV))]-µ-oxo-isopropoxide are found to be brownish yellow highly
viscous liquid to gel type, soluble in common organic solvents (benzene, chloroform, hexane), susceptible to
hydrolysis and decompose on heating above 200
0
C.
Infrared Spectral Studies
The spectra of the 1:1 to 1:3 Schiff base derivative of [SnO
2
Ti
2
(O-i-Pr)
6
] shows absorption bands in the region
1360-1340 cm
-1
, 1165-1150 cm
-1
and 1090-1020 cm
-1
are the characteristics of gem-dimethyl
37
portion and
combination bands v(C-O +O-i-Pr) of the terminal and bridging isopropoxy groups respectively. No peak is
observed at 1165 cm
-1
in the spectrum of 1:4 schiff base derivative indicates the absence of terminal
isopropoxy groups. This suggest that probably bridging isopropoxy groups could not be replaced. A band
appeared at approx. 950cm
-1
is due to v(C-O) stretching of bridging isopropoxy group.
37,38
The IR spectra of Schiff base display a broad band at ~3400-3100 cm
-1
due to v(O-H) stretch. Further these
ligands show intense bands in the region ~1565 cm
-1
and 1270-1240 cm
-1
due to v(C=N) of azomethine group
and v(C-O) vibrations of the phenolic group respectively. Disappearance of v(O-H) stretch at ~ 3400-3100 cm
-
1
in the IR spectra of Schiff base derivatives and downward shift in v(C=N) stretch and upward shift in v(C-O)
i.e. ~ 1565 cm
-1
by ~ 15-25 cm
-1
and 1240-1270 cm
-1
by ~20-30 cm
-1
respectively indicate that azomethine
‘N’is coordinated to metal atom and bond formation of phenolic oxygen
39
to the metal atom. While some
vibrations are observed below700 cm
-1
are due to M-O and M-N stretching vibrations in the Schiff base
derivatives which are difficult to assign exactly due to the overlapping of bands in this region.
NMR Spectral Studies
1
H NMR Spectra
1
H NMR spectraof all the Schiff base derivatives of heterobimetallic [Sn(II);Ti(IV))]-µ-oxo-isopropoxide
show a number of peaks centered between δ 0.6-1.5 ppm due to the intermixing of methyl protons of terminal
and bridgingisopropoxy groups. A multiplet at 4.2 ppm is due to the methine proton of isopropoxy groups in
the spectra of all derivatives.
In the
1
H NMR spectra of all derivatives, the signals observed between δ 7.1-7.8 ppm are due to phenyl ring
proton. Apeak observed in the
1
H NMR spectra of Schiff base at δ 11.2 ppm due to phenolic (O-H) proton is
found absent in its derivative of heterobimetallic [Sn(II);Ti(IV))]-µ- oxo-isopropoxide indicates the
deprotonation of these ligands. In the case of salicylidene-o-toluidene derivatives an additional signal at δ 2.3
ppm has been observed due to methyl protons
39,40
substituted on the benzene ring.
13
C NMR Spectra
The
13
C NMR spectra of 1:1 to 1:3 Schiff base derivative of heterobimetallic [Sn(II);Ti (IV))]-µ- oxo-
isopropoxide compound shows two prominent peaks at δ ~26.9 ppm and δ ~27.4 ppm assignable to the methyl
INTERNATIONAL JOURNAL OF RESEARCH AND SCIENTIFIC INNOVATION (IJRSI)
ISSN No. 2321-2705 | DOI: 10.51244/IJRSI |Volume XII Issue X October 2025
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carbon of terminal and bridged isopropoxy moiety and two different types of methine carbons of isopropoxy
groups is confirmed by the two signals observed at δ ~62.6-62.8 ppm and δ~63.1-63.3 ppm. Further the 1:4
schiff base derivatives of µ- oxo-isopropoxide indicate the absence of terminal isopropoxy groups.
Two signal observed in the range δ 160.3-164.0 ppm and δ 148.0-150.16 ppm are due to carbonyl carbon and
methine carbon attached to nitrogen of ligand moiety in all the Schiff derivatives of µ- oxo-isopropoxide
compound.
39
A number of peaks are observed between δ 128.0-125.0 ppm in
13
C NMR spectrum of schiff base
derivatives are due to different types of phenyl ring carbons.
Experimental
Synthesis of derivatives of heterobimetallic [Sn(II);Ti(IV)]-µ-oxo-isopropoxide with Schiff bases
Synthesis of 1:1 salicylidene-aniline derivative of µ-oxo compound.
The compound [SnO
2
Ti
2
(O-i-Pr)
6
] (0.383g, 0.637mmol) and salicylidene-aniline (0.106g, 0.536 mmol) were
refluxed in (~50ml) benzene for 4 hrs at ~100 °C in a flask connected to short distillation column. The
liberated isopropanol was collected continuously at 72-78 °C as a binary azeotrope of isopropanol-benzene.
The reaction can be depicted as:
Where n=1-4 and
HSB =Salicylidene-aniline
The isopropanol in azeotrope was estimated oxidimetrically to check the completion of the reaction. The
excess of the solvent was then removed under reduced pressure (45 °C/ 1mm) yielding a yellowish red highly
viscous product.
Similar procedure was adopted for the preparation of other derivatives of [SnO
2
Ti
2
(O-i-Pr)
6
] with Schiff bases
(HSB) i.e. Salicylidene-aniline (HSB
1
), Salicylidene-o-toluidene (HSB
2
) and Salicylidene p-chloroaniline
(HSB
3
) in different stoichiometric ratio of 1:1, 1:2, 1:3 and 1:4. All the derivatives were found to be brownish
yellow highly viscous liquid to gel type product, soluble in common organic solvents (benzene, chloroform,
hexane), susceptible to hydrolysis. The details are given in (Table-1) along with the analytical data.
Table-1: Analytical data
S.No
Compound
g(mmol)
Ligand
g(mmol)
Molar
Ratio
Product g(%)
Anal. Calcd. (found)
HO-i-Pr (g)
Sn (%)
Ti (%)
1
[SnO
2
Ti
2
(O-i-Pr)
6
]
0.383 (0.637)
HSB
1
0.106 (0.536)
1:1
[SnO
2
Ti
2
(O-i-
Pr)
5
(SB
1
)]
0.409 (87.0)
0.038
(0.030)
16.09
(15.83)
12.98
(12.60)
2
[SnO
2
Ti
2
(O-i-Pr)
6
]
0.390 (0.649)
HSB
1
0.215 (1.09)
1:2
[SnO
2
Ti
2
(O-i-
Pr)
4
(SB
1
)
2
]
0.493 (86.7)
0.078
(0.072)
13.57
(13.05)
10.95
(10.60)
3
[SnO
2
Ti
2
(O-i-Pr)
6
]
0.385 (0.641)
HSB
1
0.318 (1.617)
1:3
[SnO
2
Ti
2
(O-i-
Pr)
3
(SB
1
)
3
]
0.559 (86.3)
0.011
(0.095)
11.73
(11.42)
9.46
(9.05)
4
[SnO
2
Ti
2
(O-i-Pr)
6
]
0.372 (0.619)
HSB
1
0.410 (2.08)
1:4
[SnO
2
Ti
2
(O-i-
Pr)
2
(SB
1
)
4
]
0.611 (85.9)
0.148
(0.140)
10.33
(9.98)
8.33
(7.94)
5
[SnO
2
Ti
2
(O-i-Pr)
6
]
0.382 (0.636)
HSB
2
0.113 (0.534)
1:1
[SnO
2
Ti
2
(O-i-
Pr)
5
(SB
2
)]
0.421 (86.4)
0.038
(0.032)
15.43
(15.10)
12.47
(12.12)
6
[SnO
2
Ti
2
(O-i-Pr)
6
]
0.387 (0.644)
HSB
2
0.228 (1.082)
1:2
[SnO
2
Ti
2
(O-i-
Pr)
4
(SB
2
)
2
]
0.524 (87.1)
0.077
(0.071
12.70
(12.11)
10.24
(9.85)
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7
[SnO
2
Ti
2
(O-i-Pr)
6
]
0.386 (0.642)
HSB
2
0.341 (1.617)
1:3
[SnO
2
Ti
2
(O-i-
Pr)
3
(SB
2
)
3
]
0.604(85.4)
0.196
(0.189)
10.77
(10.22)
8.69
(8.15)
8
[SnO
2
Ti
2
(O-i-Pr)
6
]
0.371 (0.617)
HSB
2
0.438 (2.076)
1:4
[SnO
2
Ti
2
(O-i-
Pr)
2
(SB
2
)
4
]
0.666 (85.0)
0.148
(0.142)
9.35
(9.04)
7.55
(7.14)
9
[SnO
2
Ti
2
(O-i-Pr)
6
]
0.362 (0.603)
HSB
3
0.117 (0.506)
1:1
[SnO
2
Ti
2
(O-i-
Pr)
5
(SB
3
)]
0.394(84.8)
0.036
(0.030)
15.37
(14.95)
12.40
(11.89)
10
[SnO
2
Ti
2
(O-i-Pr)
6
]
0.370 (0.616)
HSB
3
0.240 (1.036)
1:2
[SnO
2
Ti
2
(O-i-
Pr)
4
(SB
3
)
2
]
0.495 (85.3)
0.074
(0.069)
12.58
(12.26)
10.14
(9.79)
11
[SnO
2
Ti
2
(O-i-Pr)
6
]
0.365 (0.608)
HSB
3
0.385 (1.533)
1:3
[SnO
2
Ti
2
(O-i-
Pr)
3
(SB
3
)
3
]
0.584 (86.2)
0.109
(0.098)
10.64
(10.24)
8.58
(8.13)
12
[SnO
2
Ti
2
(O-i-Pr)
6
]
0.389 (0.648)
HSB
3
0.504 (2.176)
1:4
[SnO
2
Ti
2
(O-i-
Pr)
2
(SB
3
)
4
]
0.740 (88.9)
0.155
(0.148)
9.22
(8.87)
7.44
(7.16)
On the basis of aforesaid spectral studies and elemental analysis the following tentative structures (Fig. 1-4) of
the Schiff base derivatives of heterobimetallic [Sn(II);Ti(IV))]-µ-oxo-isopropoxide of the type [SnO
2
Ti
2
(O-i-
Pr)
5
(SB)
1
],[SnO
2
Ti
2
(O-i-Pr)
4
(SB)
2
], [SnO
2
Ti
2
(O-i-Pr)
3
(SB)
3
] and [SnO
2
Ti
2
(O-i-Pr)
2
(SB)
4
] has been depicted:
Fig. 1: [SnO
2
Ti
2
(O-i-Pr)
5
(SB)
1
]
Fig. 2: [SnO
2
Ti
2
(O-i-Pr)
4
(SB)
2
]
Fig. 3: [SnO
2
Ti
2
(O-i-Pr)
3
(SB)
3
]
INTERNATIONAL JOURNAL OF RESEARCH AND SCIENTIFIC INNOVATION (IJRSI)
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Fig. 4: [SnO
2
Ti
2
(O-i-Pr)
2
(SB)
4
]
REFERENCES
1. S. Mishra, S. Daniele. Chem. Rev., 115, 8379 (2015).
2. L. John, P. Sobota. Acc. Chem. Res., 47, 470 (2014).
3. G.A. Seisenbaeva, V.G. Kessler. Nanoscale, 6, 6229 (2014).
4. A. Devi. Coord. Chem. Rev., 257, 3332 (2013).
5. L.G. Bloor, C. J. Carmalt, D. Pugh. Coord. Chem. Rev., 255, 1293 (2011).
6. S. Mishra, S. Daniele, L.G. Hubert-Pfalzgraf. Chem. Soc. Rev., 36, 1770 (2007).
7. L.G. Hubert-Pfalzgraf. J. Mater. Chem., 14, 3113 (2004).
8. L.G. Hubert-Pfalzgraf. Inorg. Chem. Commun., 6, 102 (2003).
9. S. Mishra, E. Jeanneau, S. Mangematin, H. Chermette, M. Poor Kalhor, G. Bonnefont, G. Fantozzi, S.
Le Floch, S. Pailhes, S. Daniele. Dalton Trans., 44, 6848 (2015).
10. Y. Chen, S. Mishra, G. Ledoux, E. Jeanneau, M. Daniel, J. Zhang, S. Daniele. Chem. Asian J., 9, 2415
(2014).
11. Z. Wei, A.S. Filatov, E.V. Dikarev. J. Am. Chem. Soc., 135, 12216 (2013).
12. S.Mishra, V. Mendez, E. Jeanneau, V. Caps, S. Daniele. Eur. J. Inorg. Chem., 500 (2013).
13. S. Mishra, G. Ledoux, E. Jeanneau, S. Daniele, M.-F. Joubert. Dalton Trans., 41, 1490 (2012).
14. A. Navulla, A.A. Tsirlin, A.M. Abakumov, R.V. Shpanchenko, H. Zhang, E.V. Dikarev. J. Am. Chem.
Soc., 133, 602 (2011).
15. S. Mishra, E. Jeanneau, S. Daniele, V. Mendez. Dalton Trans., 39, 7440 (2010).
16. S. Mishra, E. Jeanneau, M.-H. Berger, J.-F. Hochepied, S. Daniele. Inorg. Chem., 49, 11184 (2010).
17. S. Mishra, S. Daniele, G. Ledoux, E. Jeanneau, M.-F. Joubert. Chem. Commun., 46, 3756 (2010).
18. S. Mishra, J. Zhang, L.G. Hubert-Pfalzgraf, D. Luneau, E. Jeanneau. Eur. J. Inorg. Chem., 602 (2007).
19. D.C. Bradley, R.C. Mehrotra, I.P. Rothwell, A. Singh, Alkoxo and Aryloxo derivatives of Metals,
Academic Press, New York (2001).
20. N.Ya. Turova, E.P. Turevskaya, V.G. Kessler, M.I. Yanovskaya, The Chemistry of Metal Alkoxide,
Kluwer Academic Publishers, Boston (2002).
21. L.G. Bloor, C.J. Carmalt, D. Pugh. Coord. Chem. Rev., 255, 1293 (2011).
22. V.G. Kessler. J. Sol-Gel Sci. Technol., 51, 264 (2009).
23. S. Szafert, L. John, P. Sobota. Dalton Trans., 6509 (2008).
24. R.C. Mehrotra, A. Singh. Polyhedron, 17, 689 (1998).
25. R.C. Mehrotra, A. Singh. Prog. Inorg. Chem., 46, 239 (1997).
26. R.C. Mehrotra, A. Singh, S. Sogani. Chem. Rev., 94, 1643 (1994).
27. R.C. Mehrotra, A. Singh, S. Sogani. Chem. Soc. Rev., 23, 215 (1994).
28. R.C. Mehrotra, A. Singh, U.M. Tripathi. Chem. Rev., 91, 1287 (1991).
29. K.G. Kaulton, L.H. Hubert-Pfalzgraf. Chem. Rev., 90, 969 (1990).
30. A. Saini, D. Singh, V. Dhayal, Structural and optical properties of titania nanostructures obtained from
oxime-modified titanium(IV) precursor, 10.1080/ 14328917.2021.1963577 26 (2021) 276–284.
31. J.L. Sharma, A. Saini, V. Dhayal, Chemically modified germanium(IV) alkoxides: molecular
precursors for nano-sized germania, 10.1080/ 14328917.2019.1612603 24 (2019) 123–128.
INTERNATIONAL JOURNAL OF RESEARCH AND SCIENTIFIC INNOVATION (IJRSI)
ISSN No. 2321-2705 | DOI: 10.51244/IJRSI |Volume XII Issue X October 2025
Page 2202
www.rsisinternational.org
32. A. Saini, D. Singh, B.L. Choudhary, V. Dhayal, Low temperature mullitization of oxime- modified
aluminosiloxane by sol-gel process, 10.1080/ 14328917.2021.1903702 26 (2021) 91–99.
33. U. Schubert, Chemical modification of titanium alkoxides for sol–gel processing, J. Mater. Chem 15,
3701–3715 (2005).
34. K.J. Klabunde, J.V.Stark, O.Koper, C.Mohs, D.G.Park, S.Decker, Y.Jiang, I.Lagadic and D.Zhang, J.
Phys. Chem., 100, 12142 (1996) .
35. O.Koper, I.Lagadic and K.J.Klabunde, Chem. Mater., 9, 838 (1997).
36. M.H.Chisholm, J. Organomet. Chem., 334, 77 (1987).
37. C. T. Lynch, K.S. Masdiyanni, J. S. Smith and W. J. Grawford, Anal. Chem., 36, 2332, (1964).
38. V. A. Koznov, N. I. Kuzlova, N. Y. Turova and Y.S. Nekrasov, Zh. Neorg. Khim., 24, 1526, (1979).
39. H. K. Sharma and P. N. Kapoor, Indian J. Chem., 43A, 566, (2004).
40. H.K. Sharma, Jashmer Singh, Rajesh Kumar and Amardeep; J.Indian, Chem.Soc.; 90,669-676 (2013).