Oxygenation of sulfides catalysed by SBA-15-immobilized molybdenum(VI) complex of a bis(phenol) diamine ligand using aqueous hydrogen peroxide as a green oxidant

Article abstract of DOI:10.1002/aoc.4304

A highly efficient and reusable molybdenum-based catalyst has been synthesized by covalent grafting of a bis(phenol) diamine ligand, namely 2-(((2-bromoethyl)(2-((3,5-di-tert-butyl-2-hydroxybenzyl)amino)ethyl)amino)methyl)-4,6-di-tert-butylphenol, onto functionalized ordered mesoporous silica (SBA-15) followed by complexation with MoO₂(acac)₂. The resulting organic–inorganic hybrid material was found to be a highly effective catalyst for oxygenation of various sulfides to their corresponding sulfoxides or sulfones. The catalyst was characterized using transmission and scanning electron microscopies, X-ray photoelectron, Fourier transform infrared and atomic absorption spectroscopies, Brunauer–Emmett–Teller surface area analysis and thermogravimetric analysis. Mild reaction conditions, high selectivity and easy recovery and reusability of the catalyst render the presented protocol very useful for addressing industrial needs and environmental concerns.

Full text of DOI:10.1002/aoc.4304

Received: 18 October 2017
DOI: 10.1002/aoc.4304
Revised: 6 January 2018
Accepted: 8 January 2018
F U L L P A P E R
Oxygenation of sulfides catalysed by SBA‐15‐immobilized
molybdenum(VI) complex of a bis(phenol) diamine ligand
using aqueous hydrogen peroxide as a green oxidant
Iraj Saberikia1 | Elham Safaei2
| Babak Karimi1 | Yong‐III Lee3
1 Institute for Advanced Studies in Basic
A highly efficient and reusable molybdenum‐based catalyst has been synthesized
by covalent grafting of a bis(phenol) diamine ligand, namely 2‐(((2‐bromoethyl)
(2‐((3,5‐di‐tert‐butyl‐2‐hydroxybenzyl)amino)ethyl)amino)methyl)‐4,6‐di‐tert‐
butylphenol, onto functionalized ordered mesoporous silica (SBA‐15) followed
by complexation with MoO2(acac)2. The resulting organic–inorganic hybrid
material was found to be a highly effective catalyst for oxygenation of various
sulfides to their corresponding sulfoxides or sulfones. The catalyst was character-
ized using transmission and scanning electron microscopies, X‐ray photoelec-
tron, Fourier transform infrared and atomic absorption spectroscopies,
Brunauer–Emmett–Teller surface area analysis and thermogravimetric analysis.
Mild reaction conditions, high selectivity and easy recovery and reusability of the
catalyst render the presented protocol very useful for addressing industrial needs
and environmental concerns.
Sciences (IASBS), 45137‐66731 Zanjan, Iran
2 Department of Chemistry, College of
Sciences, Shiraz University, Shiraz 71454,
Iran
3 Department of Chemistry, Changwon
National University, Changwon 641‐773,
South Korea
Correspondence
Elham Safaei, Department of Chemistry,
College of Sciences, Shiraz University,
Shiraz, 71454, Iran.
Email: e.safaei@shirazu.ac.ir
Funding information
Shiraz University, Institute for Advanced
Studies in Basic Sciences; Changwon
National University; Priority Research
Centers Program, Grant/Award Number:
NRF 2017‐0029634; National Research
Foundation of Korea
KEYWORDS
bis(phenol) diamine, molybdenum(IV) complex, SBA‐15
1 | INTRODUCTION
approaches for the oxidation of sulfides involve oxygen atom
transfer reactions using transition metal‐based catalysts
Transition metal‐catalysed oxygen atom transfer reactions or
catalytic oxidation reactions are among the most useful and
extensively studied reactions in both chemical and biological
processes. As one of the important practical applications,
oxygen atom transfer reactions have been widely employed
in the oxidation of sulfides[1] to sulfoxides and sulfones as
commodity chemicals which play an important role in
industrial processes and organic synthesis.[2] The signifi-
cance of these products can be well documented by their
widespread utility as versatile building blocks for construct-
ing chemically and biologically useful molecules, including
therapeutic agents, as well as their applications in the field
of desulfurization of fuels.[3] Traditional approaches of
sulfoxidation reactions involve the usage of peracids[4] or
halogen derivatives,[5] but they yield stoichiometric amounts
of environmentally unfriendly by‐products. Alternative
along with eco‐friendly hydrogen peroxide as an environ-
mentally benign, non‐toxic, cheap oxidant with water
produced as the only by‐product.[6,7]
Catalytic oxidation reactions are typically performed
using a variety of enzymes such as molybdoenzymes.
Molybdenum is found at the active centres of enzymes
such as aldehyde oxidase, sulfite oxidase, xanthine
oxidase and nitrate reductase and catalysts which catalyse
hydrogenation and selective oxidation.[8] The biochemical
role of molybdenum is based on its ability to facilitate
electron exchanges, forming stable complexes with
oxygen‐ and nitrogen‐containing ligands.[9] This has cre-
ated a wonderful motivation for the synthesis of a number
of model complexes mimicking the metalloproteins, espe-
cially oxotransferase molybdoenzymes.[8,9b,10] Bis(phenol)
amine ligands represent one of the most widely utilized
Appl Organometal Chem. 2018;e4304.
wileyonlinelibrary.com/journal/aoc
Copyright © 2018 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.4304

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SABERIKIA ET AL.
classes of ligands in model complexes of bioinorganic chem-
istry,[9,11] because substituents at the phenolate rings as well
as the position and nature of the side chain donor are easily
tunable. Hence, various electronic and steric properties are
accessible, and such ligands are capable of binding various
metal ions to give complexes with modifiable properties.
In recent decades, some homogeneous catalytic reactions
for the oxidation of sulfides have been reported.[12] To avoid
the well‐known limitations of these reactions such as poor
recyclability, catalyst contamination in the products, etc.,
supported complexes of catalytically active metals have been
synthesized in recent years.[13] In this context, many
attempts have been made for the heterogenization of metal
complexes within numerous solid supports such as ordered
mesoporous silica,[6a,13a,14] polymers,[13b] and carbon
materials.[15] The key factor of these protocols is decreasing
the energy and time used for achieving chemical transforma-
tions and separations. Organically functionalized mesopo-
rous silica materials are some of the most important solid
supports that have generated a great deal of interest for their
application in the fields of catalysis,[16] sensing[17] and
adsorption[18] due to their high surface areas and large
ordered pores ranging from 20 to 300 Å[19] with narrow size
distributions. Ordered mesoporous silica materials were first
reported in 1992.[19a] Since then, significant progress has
been made in their morphology control, pore size adjust-
ment, composition variation and application develop-
ments.[20] Recently, numerous mesoporous structures have
been synthesized, which can be classified into three catego-
ries based on pore types: approximately spherical cage, cylin-
drical channel and bi‐continuous channel.[21] Among
various ordered mesoporous silica materials, SBA‐type
silicas are the most frequently studied.[22] SBA‐15 silica)
SBA = Santa Barbara Amorphous) exhibits interesting
textural properties, such as large specific surface area (above
1000 m2 g−1), uniform‐sized pores (4–30 nm), thick frame-
work walls, variable framework compositions, small crystal-
lite size of primary particles and complementary textural
porosity and high thermal stability.[22]
CDCl3 as a solvent and tetramethylsilane (TMS) as an
internal standard.
Thermogravimetric analysis (TGA) was conducted from
room temperature to 800 °C in an oxygen flow using a
Netzsch STA 409 PC/PG instrument. The morphological
features of the prepared materials were characterized using
transmission electron microscopy (TEM; JEM2100F, JEOL,
Japan) and were verified further by nitrogen sorption analy-
sis (Belsorp, BELMAX, Japan). The electronic states of the
catalyst were evaluated using X‐ray photoelectron spectros-
copy (XPS; Multilab 2000, Thermo Scientific, Al Ka radia-
tion). The content of molybdenum in the catalyst was
determined using atomic absorption spectrometry (Varian).
Fourier transform infrared (FT‐IR) spectra were recorded
using a Bruker Vector 22 instrument after mixing the
samples with KBr. Gas chromatography analyses were
performed with a Varian CP‐3800 using a flame ionization
detector.
2.2 | Synthesis of Bis(phenol) Diamine
Ligand (2)[23]
The bis(phenol) diamine ligand precursor (1; 2.25 g, 4 mmol)
was dissolved in CHCl3 (4 ml), and a solution of PBr3 (0.2 g,
2 mmol) in CHCl3 (4 ml) was added dropwise. After stirring
the resulting solution for 1 h at 20 °C, water (10 ml) was
added. The organic phase was quickly washed three times
with water and dried over MgSO4, and the solvent was
removed by evaporation. The resulting pale‐yellow viscous
oil crystallized at 0 °C within a few days and the solid mate-
rial was air‐dried (2.1 g, 87%). 1H NMR (400 MHz, DMSO‐d6,
298 K, δ, ppm): 1.292 (s, 18H); 1.441 (s, 18H); 3.399 (t, 4H);
3.599 (t, 2H); 4.343 (t, 2H); 4.475 (s, 2H); 4.638 (s, 2H);
7.184 (d, 1H); 7.217 (d, 1H); 7.519 (d, 1H); 7.629 (d, 1H). M.
p. 138–140 °C.
2.3 | Anchoring of Mo(VI) complex to
bis(phenol) diamine ligand‐functionalized
SBA‐15
2.3.1 | Preparation of SBA‐15 (3)[24]
Herein, we report the design, synthesis and character-
ization of a new supported molybdenum‐based catalyst,
obtained by anchoring a molybdenum(VI) complex to
bis(phenol) diamine ligand‐functionalized SBA‐15. The
catalyst performance in the mild oxidation of organic
sulfides with H2O2 was evaluated.
Typically, 24 g of Pluronic P123 (MWav ≅ 5800 g mol−1
;
Aldrich) as structure‐directing agent was dissolved in a
solution containing 101 ml of HCl (conc.) and 505 ml of
distilled water. Then 54.2 ml of tetraethyl orthosilicate
was added and the resulting mixture vigorously stirred
at 35 °C for 18–20 h. After this, the resulting mixture
was aged without stirring at 80 °C for 24 h. The obtained
mesoporous silica with surfactant was filtered and washed
with deionizer water, and dried at room temperature. The
surfactant was extracted from the SBA‐15 channels using
a Soxhlet apparatus with ethanol for 72 h.
2 | EXPERIMENTAL
2.1 | Materials and Methods
All chemicals and solvents were obtained from commer-
cial suppliers. Liquid NMR spectroscopy was conducted
with a DMX‐400 MHz Bruker Avance instrument using

SABERIKIA ET AL.
3 of 14
2.3.2 | Preparation of SBA‐15@AP (4)[25]
with dry toluene and diethyl ether. The resulting material
was filtered and unreacted ligand was washed using a
Soxhlet apparatus overnight with ethanol. Following this,
5 was prepared by adding a solution of MoO2(acac)2
(0.261 g, 0.8 mmol) in ethanol (30 ml) to solid SBA‐
15@AP‐LAEB (1 g) and stirring the suspension at room
temperature for 24 h. The produced yellow solid was con-
tinuously filtered off and washed with ethanol using a
Soxhlet apparatus and dried in an oven at 80 °C overnight
to afford produce 5 (Scheme 1).
SBA‐15@AP (4) was achieved by a post‐synthesis grafting
method according to a literature procedure.[25] In a typical
procedure, to a suspension of SBA‐15 (2 g) in 70 ml of
dry toluene, (3‐aminopropyl)triethoxysilane (0.44 ml,
2 mmol) was added and the resulting mixture was
refluxed for 15 h under an inert atmosphere. The resulting
material was then filtered and unreacted (3‐aminopropyl)
triethoxysilane was washed using a Soxhlet apparatus
overnight employing ethanol. The material was dried at
80 °C for 12 h and used in the next stage.
2.4 | General Procedure for Catalytic
Oxidation of Sulfides to Sulfoxides
2.3.3 | Preparation of SBA‐15@AP‐LAEB
‐
To a solution of 1 mmol of sulfide and 2–4 mmol of 25%
H2O2 (depending on sulfide) in 2 ml of H2O–CH3CN
(1:1) was added 14–28 mg (depending on sulfide) of 5
(1–2 mol%), and the solution obtained was stirred at
25 °C for the required time. The progress of the reactions
was monitored by TLC or GC. After completion of the
Mo(VI)O2 (5)
SBA‐15@AP (1 g) was added to a solution of 2 (1 mmol,
0.602 g) in dry toluene (15 ml) and the resulting suspen-
sion was refluxed for 48 h. Then, the supported ligand
(SBA‐15@AP‐LAEB) was filtered and washed thoroughly
SCHEME 1 Anchoring of molybdenum(VI) complex to bis(phenol) diamine ligand‐functionalized SBA‐15

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SABERIKIA ET AL.
reaction, the product was extracted with the addition of
3 ml of ethyl acetate while the catalyst (5) remained at
the interface of the organic and aqueous phases. The
organic layer was dried with MgSO4, and then sulfide con-
version and selectivity were determined using GC. Some
of the substrate product was purified using column chro-
matography (n‐hexane–ethyl acetate (8:1)) if necessary.
conditions according to a reported procedure with slight
modification.[24] The resulting SBA‐15 was then succes-
sively functionalized with (3‐aminopropyl)triethoxysilane
(AP) to yield the corresponding aminopropyl‐functional-
ized SBA‐15 (4). SBA‐15@AP‐LAEB was synthesized by
nucleophilic reaction between 4 and 2.[11c] The highly
stable and reusable heterogeneous catalyst SBA‐15@AP‐
L
AEB‐Mo(VI)O2 (5) was prepared by adding a certain
amount of Mo(VI)O2(acac)2 to an acetonitrile solution
containing SBA‐15@AP‐LAEB, which was stirred at room
temperature for 24 h. After stirring, the solid was filtered
and washed with ethanol using a Soxhlet apparatus in
order to remove any Mo(VI)O2(acac)2 adsorbed on the sur-
face. It was then dried in an oven at 80 °C overnight to
furnish the corresponding SBA‐15‐supported complex 5.
The structures of prepared materials were character-
ized using various techniques including TEM, TGA,
XPS, FT‐IR, atomic absorption spectroscopy, diffuse
reflectance UV–visible spectroscopy and N2 adsorption–
desorption analysis. The N2 adsorption–desorption iso-
therms of parent SBA‐15 (3) and 5 are shown in
Figure 1. It exhibits typical type IV sorption isotherms
with an H1 hysteresis loop at a relative pressure 0.5 < p/
p0 < 0.8, suggesting that 5 is a kind of highly ordered
mesoporous material (pore size: 2–50 nm).[26] The struc-
tural parameters for these materials are presented in
Table 1. In addition, the Brunauer–Emmett–Teller (BET)
specific surface area is 383 m2 g−1 for 5. However, the
amount of N2 adsorbed on all the anchored samples is
lower compared to parent SBA‐15, which is reflected in
the surface areas (Table 1). The BET surface areas of 3, 4
2.5 | General Procedure for Catalytic
Oxidation of Sulfides to Sulfones
To a solution of 1 mmol of sulfide and 3–5 mmol of 25% H2O2
(depending on sulfide) was added 14 mg (depending on sul-
fide) of 5 (1 mol%), and the solution obtained was stirred at
25 °C for the required time. The progress of the reactions
was monitored by TLC or GC. After completion of the reac-
tion, the product was extracted with addition of 3 ml of ethyl
acetate while the catalyst (5) remained at the interface of the
organic and aqueous phases. The organic layer was dried
with MgSO4, and then sulfide conversion and selectivity
were determined using GC. Some of the substrate product
was purified using column chromatography (n‐hexane–
ethyl acetate (8:1)) if necessary.
2.6 | Regeneration of Catalyst
The reusability of the catalyst for subsequent catalytic
cycles was examined using methylphenyl sulfide as the
substrate. In the sulfoxidation reaction mentioned above,
after completion of the reaction, the solid catalyst was
separated from the reaction mixture by filtration, washed
with acetone and dried. The solid dried catalyst was then
added to a fresh reaction mixture of 25% H2O2 (0.226 ml,
2 mmol), substrate (1 mmol) and H2O–CH3CN (2 ml).
The progress of the reaction was monitored by TLC and
GC. In the case of the oxidation reaction of methylphenyl
sulfide to sulfone, the catalyst was similarly recovered
after completion of the reaction by separating it from
the reaction mixture and adding it to fresh 25% H2O2
(0.339 ml, 3 mmol), substrate (1 mmol) under solvent‐free
conditions, as mentioned in Section 1.5. Each of the pro-
cedures was repeated for six reaction cycles.
and 5 are 968, 660 and 383 m2
g
−1, respectively
3 | RESULTS AND DISCUSSION
3.1 | Synthesis and Characterization
The procedure for the covalent attachment of the
molybdenum(VI) complex of aminoethanol derivative of
ligand 2 onto functionalized SBA‐15 via a stepwise proce-
dure is depicted in Scheme 1. The primitive SBA‐15 (3)
was initially prepared by hydrolysis and condensation of
EtO4Si in the presence of Pluronic P123 under acidic
FIGURE 1 N2 adsorption–desorption isotherms and pore size
distributions (inset) of (a) SBA‐15, (b) SBA‐15@AP, (c) SBA‐
15@AP‐LAEB‐Mo(VI)O2 and (d) recovered SBA‐15@AP‐LAEB
‐
Mo(VI)O2 after five runs

SABERIKIA ET AL.
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TABLE 1 Textural propertiesa of various materials
molybdenum(VI) complex of bis(phenol) diamine ligand
immobilization stage (Table 1).
Vp
Dp
BET Sa Mo content
(mmol g−1 b
(cm3 g−1) (nm) (m2 g−1
)
)
The TEM images of 5 along the 001 and 110 directions
made known that the two‐dimensional hexagonal
mesostructured material was well retained during the
preparation processes (Figure 2A). A magnified TEM
image of 5 indicated that the pore diameter and the wall
thickness of pores are about 6.9 and 3.7 nm, respectively
(Figure 2A). These results are further supported by N2
adsorption–desorption analysis results presented earlier.
Moreover, field‐emission scanning electron micros-
copy (SEM) images of 5 (Figure 3) clearly illustrate that
the uniformity the fibre‐like morphology for mesoporous
SBA‐15 is retained, indicating that the macroscopic struc-
ture of fibre‐like SBA‐15 is stable.
Additionally, the presence of Mo species was also con-
firmed using energy‐dispersive spectroscopy (EDS). The
spectrum of the catalyst exhibited three distinct peaks at
around 1, 8 and 9 keV (Figure 4).
XPS is an effective technique for studying the elec-
tronic properties of the species formed on the surface.
Figure 5(A) presents the XPS spectrum of 5 and Figure 5
(B) that of Mo (3d3/2 and 3d5/2) region. The binding ener-
gies were corrected using the C (1 s) line at 284.5 eV. XPS
analysis was performed with monochromatic Al Ka
Sample
SBA‐15
1.31
0.91
0.87
9.2
968
—
—
0.6
SBA@AP
7.02 660
SBA@AP‐LAEB
Mo(VI)O2
‐
6.2
7.2
383
371
Recovered
SBA@AP‐LAEB
0.64
0.54
‐
Mo(VI)O2
aSa, surface area; Dp, pore diameter; Vp, pore volume.
bFrom inductively coupled plasma atomic emission spectroscopic analysis.
(Table 1). The decrease in surface area can be ascribed to
the surface functionalization of parent SBA‐15 with vari-
ous functional groups. Also, this indicates that the molyb-
denum complex of the bis(phenol) diamine ligand is well
established on the surface of 3. The pore size distribution
curves are shown in Figure 1 as an inset. The pores are
narrowly distributed in the range 5–8 nm, revealing the
existence of ordered mesopores. According to Barrett–
Joyner–Halenda and BET plots, the specific surface area,
pore size distributions and total pore volume of the mate-
rials were all decreased after the post‐grafting and
FIGURE 2 TEM images of (A) SBA‐15@AP‐LAEB‐Mo(VI)O2 and (B) recovered SBA‐15@AP‐LAEB‐Mo(VI)O2 after five runs

6 of 14
SABERIKIA ET AL.
FIGURE 5 XPS spectrum of (A) SBA‐15@AP‐LAEB‐Mo(VI)O2
and (B) Mo (3d3/2 and 3d5/2) XPS spectrum of SBA‐15@AP‐LAEB
‐
FIGURE 3 SEM images of (A) SBA‐15@AP‐LAEB‐Mo(VI)O2 and
(B) recovered SBA‐15@AP‐LAEB‐Mo(VI)O2 after five runs
Mo(VI)O2
radiation at a pressure of ca 1.5 × 10−8 Pa. The catalyst
exhibited characteristic 3d5/2 and 3d3/2 doublets with
peaks located at around 232 and 236 eV, respectively.
The binding energy values are in good agreement with
the available literature data for Mo ions in the 6+ oxida-
tion state.[27] Thus, the presence of Mo(VI) in SBA‐
15@AP‐LAEB‐Mo(VI)O2 compound has been confirmed
from the results of XPS analysis.
FT‐IR spectra of the various materials are shown in
Figure 6. In the spectrum of parent SBA‐15 (Figure 6a), a
broad band at 3200–3600 cm−1 is attributed to the νOH
stretching vibrations of surface silanol groups being present
in the host materials. Further, a sharp band near 1635 cm
−1 corresponds to the νOH bending vibration of the silanol
groups. An intense band at about 1080 cm−1 is observed,
which is due to Si―O―Si vibrations, and the other typical
FIGURE 4 EDS analysis of SBA‐
15@AP‐LAEB‐Mo(VI)O2

SABERIKIA ET AL.
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FIGURE 7 Diffuse reflectance UV–visible spectra of (a) neat
L
AEB‐Mo(VI)O2 complex and (b) SBA‐15@AP‐LAEB‐Mo(VI)O2
FIGURE 6 FT‐IR spectra of (a) SBA‐15, (b) SBA‐15@AP, (c) SBA‐
15@AP‐LAEB and (d) SBA‐15@AP‐Laeb‐Mo(VI)O2
To determine the amount of anchored material and its
stability on the catalyst, TGA was conducted (Figure 8) in
an atmosphere of air from 25 to 800 °C with a tempera-
ture ramp of 10 °C min−1, and the resultant thermograms
are shown in Figure 8. The TGA plot of SBA‐15@AP
(Figure 8b) shows two distinct weight losses. The first loss
below 200 °C is attributed to the physically adsorbed
solvent and the second loss between 200 and 380 °C corre-
sponds to the combustion of propylamine groups. In the
case of 5 (Figure 8d), weight loss of 2.11 and 29.77% in
the range 25–200 and 200–500 °C has been ascribed to
the loss of the physically adsorbed solvent and the AP‐
vibration modes of SBA‐15 (Si―O―Si, 803 cm−1; Si―OH,
956 cm−1; and Si―O, 462 cm−1) are present in all cases.[28]
After the functionalization of the parent SBA‐15 with AP
(Figure 6b(, the peaks at 3200–3600 cm−1 had disappeared,
indicating that the silanol groups on the surface of SBA‐15
are transferred into a Si―O―Si framework. In addition,
strong peaks around 2900 cm−1 have been attributed to the
stretching vibrations of the ―CH2 groups in propyl chain
of the organic modifiers which evidently supports the notion
that the aminopropyl group is attached to the SBA‐15.
The presence of C―H vibrations at 2930 cm−1 is
observed plus a series of aromatic ring vibrations in the range
1400–1600 cm−1 and C―N stretching vibration of aliphatic
amines is observed as medium or weak bands in the region
1020–1250 cm−1. These are not observed for 5 due to the
overlapping of these peaks with ν(Si―OH) vibrations, indi-
cating grafting of the molybdenum(VI) complex of
bis(phenol) diamine ligand onto functionalized SBA‐15
(Figure 6d).
L
AEB‐Mo(VI)O2 sites on SBA‐15, respectively.
The TGA result for SBA‐15@AP quantitatively shows
15% weight loss, strongly supporting the successful
anchoring of AP on SBA‐15. Further, 5 shows 32% weight
loss, which is greater than the loss observed for SBA‐
The diffuse reflectance UV–visible spectra of the neat
L
AEB‐Mo(VI)O2 complex and catalyst 5 are presented in
Figure 7 to obtain further information about the coordina-
tion environment and the oxidation state of molybdenum.
The spectra of SBA‐15 and 5 (Figure 7b) exhibit a peak at
225 nm, typical for siliceous materials.[29] In both com-
pounds, namely the neat
L
AEB‐Mo(VI)O2 complex
(Figure 7a) and 5, a peak at 285 nm is assigned to π →
π* transitions of the aromatic ring. Moreover, a broad
band at 430 nm is attributed to N → Mo(VI) and O →
Mo(VI) ligand‐to‐metal charge‐transfer transitions.[30]
The absence of a d–d transition in the visible region (400
to 800 nm) confirms the 4d0 electron configuration of
the molybdenum sites.[31]
FIGURE 8 TGA patterns of (a) SBA‐15, (b) SBA‐15@AP, (c) SBA‐
15@AP‐LAEB and (d) SBA‐15@AP‐LAEB‐Mo(VI)O2

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SABERIKIA ET AL.
15@AP, strongly supporting a 17% loading of neat LAEB
Mo(VI)O2 sites in SBA‐15. All these results confirm that
the material was synthesized and the LAEB‐Mo(VI)O2 sites
are directly anchored on the modified SBA‐15.
‐
Interestingly, we also found that the presence of water was
indispensable for ensuring satisfactory conversion using this
catalytic system. The reason that sulfoxide formation is more
prominent in water in the case of substrates bearing an addi-
tional polar hydroxyl substituent is possibly due to the more
favourable hydrophilic–hydrophilic interaction of the sulfox-
ide products and water, which facilitates their departure
from the hydrophobic catalyst nanospaces, thus strongly
preventing their over‐oxidation to the corresponding
sulfones, as occurred did in pure solvent such as CH3CN.
In the next step, the effect of the catalyst loading was
examined. The amount of catalyst had a considerable
influence on the rate of reaction, as evident from the data
presented (Table 2, entries 7 and 10). Decreasing the cata-
lyst amount reduced the reaction rate and increased the
reaction time without compromising the selectivity, but
increasing the catalyst amount did not affect the reaction
rate and the reaction time with a slight decrease at the
selectivity. In this case, when the amount of catalyst was
decreased from 1 to 0.5 mol%, the yield of the sulfoxides
considerably reduced (Table 2, entry 10), but the use of
2 mol% of the catalyst did not affect the yield; however,
the selectivity of the sulfoxides was significantly reduced
(Table 2, entry 11). The vital role of the catalyst in the for-
mation of the preferred product was confirmed by
conducting a blank experiment in the absence of the cat-
alyst (Table 2, entry 12). Therefore, the best result was
3.2 | Catalytic Activity of Supported
Molybdenum‐Based Catalyst (5)
3.2.1 | Oxidation of sulfides to sulfoxides
and sulfones
The catalytic activity of the supported molybdenum‐based
catalyst has been explored for the oxidation of sulfides to
sulfoxides with H2O2 as oxidant. The effect of various
reaction parameters, such as catalyst concentration, sub-
strate‐to‐H2O2 stoichiometry, type of solvent, etc., was
estimated using butylphenyl sulfide as a difficult‐to‐oxi-
dize model substrate, in order to optimize the reaction
conditions. The reactions were performed at ambient tem-
perature under magnetic stirring.
Initially, we planned to determine whether the product
selectivity of the present oxidation protocol using 5 might
be affected by reaction solvent (Table 2, entries 1–6). Our
results indicated that for the various solvents, namely water,
acetone, CH3CN, EtOH, acetone–H2O and CH3CN–H2O,
the highest selectivity was obtained if CH3CN–H2O (1:1)
mixture was used as a solvent system (Table 2, entry 9).
TABLE 2 Optimization of reaction conditions for oxidation of sulfides to sulfoxidesa
Entry
Substrate
Solvent (1 ml)
H2O2 (eq.)
Catalyst (mol%)
Conv. (%)
SO (%)
SO2 (%)
Time (min)
1
2
3
4
5
6
7
8
H2O
Acetone
CH3CN
EtOH
2
2
2
2
2
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1
1
11
75
88
96
90
98
98
96
54
>99
28
<19
59
<18
45
5
31
33
47
35
65
70
75
45
60
26
18
40
17
35
6
44
50
49
55
33
28
21
9
40
2
<1
19
<1
10
70
70
70
70
70
70
45
30
30
30
70
120
120
120
70
Acetone–H2O; 1:1
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
9
0.5
2
—
10
11
12
13
14
15
(14 mg)b
(14 mg)c
(14 mg)d
1
16
17
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
2
2
1e
1f
98
73
65
44
33
29
70
70
aReaction conditions: sulfide (1 mmol), H2O2 (25%), solvent (1 ml), SBA‐15@AP‐LAEB‐Mo(VI)O2 (1–2 mol%), reaction mixture stirred at 25 °C for the required
time.
bSBA‐15@AP‐LAEB (14 mg).
cSBA‐15@AP (14 mg).
dSBA‐15 (14 mg).
eMoO2(acac)2 (1 mol%, 3.28 mg).
fLaeb/MoO2(acac)2 (1 mol%, 7.15 mg).

SABERIKIA ET AL.
9 of 14
obtained when 14 mg of catalyst was used in a CH3CN–
H2O (1:1) mixture and two equivalents of 25% H2O2 at
room temperature (Table 2, entry 9). The results of the
sulfoxidation reactions catalysed by SBA‐15@AP‐LAEB
,
SBA‐15@AP and SBA‐15 are also presented in Table 2
(entries 12–14). Afterwards, decreasing the amount of
H2O2 (Table 2, entry 15) decreased the yield. Also, we per-
formed the reaction with MoO2(acac)2 and homogeneous
molybdenum complex (Table 2, entries 16 and 17). In
both cases, the yield was moderate but the results showed
that the catalyst was not recyclable. As shown in Figure 9,
the conversion increased with reaction time and reached
>99% in 30 min. Also, the selectivity was 93% (Figure 9).
In order to investigate the generality of the catalyst, fur-
ther studies using more sulfides were performed. With the
optimized conditions in hand, we examined the substrate
scope for the molybdenum‐based catalysed sulfoxidation
reaction (Table 3). The desired sulfoxidation products could
be obtained in moderate to excellent yields. Also, the selec-
tivity for other sulfides was appropriate.
FIGURE 9 Conversion and selectivity changes over time for
oxidation reaction of methylphenyl sulfide
TABLE 3 Oxidation of various sulfides to sulfoxidesa
Entry
Substrate
Solvent (1 ml)
H2O2 (eq.)
Conv. (%)b
SO (%)
TON
TOF (h−1 c
)
Time (min)
1
H2O
2
100
93
119
238
170
228
153
156
159
30
2
3
4
5
6
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
2
2
2
2
2
95
96
75
75
75
70
80
113
114
115
117
119
40
30
45
45
45
97
98
100
7
8
CH3CN–H2O; 1:1
CH3CN–H2O; 1:1
2
3
97
90
84
80
115
107
173
54
40
120
9
CH3CN
CH3CN
CH3CN
4
4
4
100d
70d
80
40
60
119
83
30
14
15
240
360
360
10
11
80d
95
aAll reactions carried out with sulfide (1 mmol), 2–4 mmol of 25% H2O2, 14 mg of SBA‐15@AP‐LAEB‐Mo(VI)O2 (1 mol%) and the solution was stirred at 25 °C for
the required time.
bGC yield using internal standard method.
cTON = (substrate/catalyst) × conversion.
dIsolated yield.

10 of 14
SABERIKIA ET AL.
To further highlight the synthetic usefulness of our
demonstrated that the best result was achieved when
14 mg of catalyst was used under solvent‐free conditions
with 3 equivalents of 25% H2O2 at room temperature
(Table 4, entry 3). To explore the substrate scope, several
organic sulfides were analysed for the preparation of sul-
fones (Table 5). In all cases, the reaction proceeded with
high selectivity and we obtained the highest yield of sul-
fone at the appropriate times (Table 5). Moreover, the oxi-
dation of dibenzothiophene gave an overall yield of
dibenzothiophene sulfone of 95% (Table 5, entry 10).
procedure, the selective oxidation of sulfides to sulfones
was also carried out by varying the amount of oxidant.
The reaction conditions were optimized by using
methylphenyl sulfide as substrate and 5 as catalyst
(Table 4). Eventually the selective oxidation of
methylphenyl sulfide to pure sulfone was achieved using
3–4 equivalents of 25% H2O2 (depending on sulfide),
under the conditions mentioned in Table 4 (entry 3).
Monitoring of the reaction in various solvents such as
water and EtOH and also solvent‐free conditions
3.2.2 | Proposed mechanism
TABLE 4 Optimization of reaction conditions for oxidation of
sulfides to sulfonesa
The proposed mechanism of sulfoxidation is shown in
Scheme 2. The oxotransfer takes place from an oxoperoxo
complex either by direct oxygen transfer or coordination
of the sulfide to the metal followed by oxygen transfer is
proposed.[32]
Solvent H2O2 Conv. SO SO2 Time
Entry Substrate (1 ml)
(eq.) (%)
(%) (%) (min)
1
2
3
4
5
H2O
EtOH
—
—
—
5
5
3
5
5
100
100
100
100
28
62 38 120
0
0
0
100 180
100 120
100 110
3.3 | Recyclability of Catalyst
26
2
100
The most important advantage of heterogeneous catalysis
is the considerable increase of complex stability in the
reaction media and the possibility of reusing the catalyst
aReaction conditions: sulfide (1 mmol), H2O2 (25%), solvent (1 ml), 14 mg of
SBA‐15@AP‐LAEB‐Mo(VI)O2 (1 mol%) and the solution was stirred at 25 °C
for the required time.
TABLE 5 Oxidation of various sulfides to sulfonesa
Entry
Substrate
H2O2 (eq.)
Conv. (%)b
SO2 (%)
TON
TOF (h−1
)
Time (min)
1
3
100
>99
60
30
120
2
3
4
5
6
7
3
3
3
3
3
3
100
100
100
100
100
100
>99
>99
>99
>99
>99
>99
60
60
60
60
60
60
30
36
40
40
40
60
120
100
90
90
90
60
8
9
3
3
100
100
>99
>99
60
60
52
8
70
480
10c
5
100d
>95
30
2
840
aAll reactions carried out with sulfide (1 mmol), 3 mmol of 25% H2O2, 14 mg of SBA‐15@AP‐LAEB‐Mo(VI)O2 (1 mol%) and the solution was stirred at 25 °C for
the required time.
bGC yield using internal standard method.
cSulfide (1 mmol), catalyst (2 mol%, 28 mg), and reaction at 70 °C in CH3CN (1 ml).
dIsolated yield.

SABERIKIA ET AL.
11 of 14
SCHEME 2 Proposed mechanism for oxidation of sulfides
after reaction by simple filtration. The catalyst (SBA‐
15@AP‐LAEB‐Mo(VI)O2) could be easily filtered and
recycled (Figure 10), due to its heterogeneous characteris-
tics. In this case, the oxidation of methylphenyl sulfide
was performed for up to six runs with slight loss of activ-
ity. The recyclability was examined for six cycles by
adding the spent catalyst to H2O2, methylphenyl sulfide
and CH3CN–H2O (solvent‐free conditions for sulfone
preparation) after each cycle of reaction. It is evident from
FIGURE 11 Sheldon's hot filtration test in oxidation of
FIGURE 10 Recyclability of the catalyst
methylphenyl sulfide

12 of 14
SABERIKIA ET AL.
TABLE 6 Comparison of activity of various catalysts in the oxidation of methylphenyl sulfide using H2O2
Entry Catalyst
Solvent
Temperature (°C) Time (min) Yield (%) Reusability Ref.
1
2
3
4
5
(L)Mo(VI)O2@SBA‐15
[MoO2(O2)(L)2]2−‐MR
CH3CN
MeOH
26
180
40
89
98
95
94
87
4
[13a]
[13b]
[13c]
[34a]
[34b]
25
6
(C19H42N)2[MoO(O2)2(C2O4)].H2O H2O
25
25
30
4
MoO2(Sal‐His)/Al‐MCM‐41
CH3CN
60
‐
Nanomagnetic‐based
N‐propylsulfamic acid
Solvent‐free 25
80
10
6
7
8
MCM‐Mo
CH3CN
CH3CN
H2O
40
40
25
60
10
30
>99
57
4
4
5
[35]
GO/[Fe3O4]/Co3O4–MoO3
SBA‐15@AP‐LAEB‐Mo(VI)O2
[36]
93
This work
Figure 10 that the activity and the selectivity of the cata-
lyst slightly change after six reaction cycles. To investigate
the effect of reaction conditions on the catalyst structure,
a sample of the separated catalyst from the last cycle was
characterized using N2 sorption and TEM analysis
techniques.
Various heterogeneous catalysts based on molybde-
num have been developed for the oxidation of sulfides
(Table 6).[13,34] In contrast to those, our catalytic system
operated under mild conditions such as room tempera-
ture, with small amounts of H2O2 (25%). Also, the present
system covered a large scope of substrates and showed
considerable functional group tolerance.
N2 adsorption–desorption analysis of the recovered
catalyst shows a typical type IV isotherm with H1 hyster-
esis loop, suggesting that the recovered catalyst is still
characterized as an ordered mesoporous material
(Figure 1d). The BET data show a surface area of
371 m2 g−1 and pore volume of 0.64 cm3 g−1 (Table 1).
The catalyst specifically shows a considerable hydrother-
mal stability during the recycling process. Additionally,
TEM images of the recovered catalyst after the fifth reac-
tion cycle indicate the stability and robustness of the
catalyst under the described reaction conditions and
recycling procedure after three reaction cycles (Figure 2
B), which is in good agreement with N2 adsorption–
desorption analysis of the recovered catalyst. The high
recyclability of the catalyst can also be understood from
the low leaching of molybdenum, which was found to
be less than 0.07 mmol g−1 using inductively coupled
plasma atomic emission spectroscopy.
Moreover, to corroborate the heterogeneity and stabil-
ity of the catalyst, Sheldon's hot filtration test[33] was
carried out, indicating that there is practically no molyb-
denum content leaching into the reaction solution under
the applied reaction conditions. To perform Sheldon's
hot filtration test in the oxidation of methylphenyl sulfide
(Figure 11) at room temperature for 120 min, the catalyst
was filtered from the reaction mixture after 20 min during
the reaction and the reaction was continued in the
absence of catalyst for 120 min. It was observed that about
67% of methylphenyl sulfide was converted after 20 min
and the conversion of methylphenyl sulfide remained
unchanged up to 2 h. Results of both reactions confirm
that our catalyst is heterogeneous.
4 | CONCLUSIONS
Immobilization of
a molybdenum(VI) complex of
aminoethanol derivative of aminophenol ligand on an
amino‐modified ordered mesoporous silica (SBA‐15) led
to the production of a highly effective heterogeneous
catalyst for the selective oxidation of sulfides to their
corresponding sulfoxides and sulfones using green
oxidant H2O2. It is worth noting that our catalyst
enabled a good conversion of sulfides to the correspond-
ing sulfoxides and sulfones with high purity especially
in the case of dibenzothiophene. The synthetic protocols
are straightforward, safe, environmentally clean and free
from any other additives such as a co‐catalyst or acid. In
addition, the oxidation is chemoselective for sulfides or
sulfoxides, leaving a benzylic C―H or olefin linkage
unaffected. The simplicity of the preparation method
of the catalyst from commercially available starting
materials and the easy recovery and reusability of the
catalyst for several catalytic cycles with unaltered activ-
ity and selectivity are other significant and attractive
features.
5 | SPECTROSCOPIC DATA
Diphenyl sulfoxide. 1H NMR (400 MHz; CDCl3; TMS; δH,
ppm): 7.62–7.66 (m, 4H), 7.33–7.45 (m, 6H) (Figure S1).

SABERIKIA ET AL.
13 of 14
4,4′‐Bis(hydroxy)diphenyl sulfoxide. 1H NMR
2011, 30, 1219. e) I. Saberikia, E. Safaei, M. H. Kowsari, Y.‐I.
Lee, P. Cotic, G. Bruno, H. A. Rudbari, J. Mol. Struct. 2012,
1029, 60. f) T. Karimpour, E. Safaei, A. Wojtczak, Z. Jagličić,
Inorg. Chim. Acta 2013, 405, 309.
(400 MHz; DMSO‐d6; TMS; δH, ppm): 10.85 (s, 2H), 7.41
(d, J = 8.5 Hz 4H), 6.86 (d, J = 8.5 Hz 4H) (Figure S2).
Dibenzothiophene sulfone. 1H NMR (400 MHz;
CDCl3; TMS; δH, ppm): 7.83–7.78 (m, 4H), 7.66–7.62 (m,
2H), 7.55–7.51 (m, 2H) (Figure S3).
[12] a) R. D. Chakravarthy, K. Suresh, V. Ramkumar, D. K. Chand,
Inorg. Chim. Acta 2011, 376, 57. b) C. Yang, Q. Jin, H. Zhang, J.
Liao, J. Zhu, B. Yu, J. Deng, Green Chem. 2009, 11, 1401.
[13] a) A. Lazar, W. R. Thiel, A. P. Singh, RSC Adv. 2014, 4, 14063. b)
J. J. Boruah, S. P. Das, S. R. Ankireddy, S. R. Gogoi, N. S. Islam,
Green Chem. 2013, 15, 2944. c) R. Deepaná Chakravarthy, D.
Kumará Chand, Green Chem. 2014, 16, 2190.
ACKNOWLEDGEMENTS
The authors are grateful to Shiraz University, Institute for
Advanced Studies in Basic Sciences (IASBS) and
Changwon National University for their valuable help.
Yong‐Ill Lee acknowledges support by the Priority
Research Centers Program (NRF 2017‐0029634) through
the National Research Foundation of Korea (NRF).
[14] a) B. Karimi, A. Zamani, S. Abedi, J. H. Clark, Green Chem.
2009, 11, 109. b) B. Karimi, A. Zamani, Org. Biomol. Chem.
2012, 10, 4531. c) B. Karimi, S. Abedi, J. H. Clark, V. Budarin,
Angew. Chem. Int. Ed. 2006, 45, 4776.
[15] Z. Li, S. Wu, D. Zheng, J. Liu, H. Liu, H. Lu, Q. Huo, J. Guan, Q.
Kan, Appl. Organometal. Chem. 2014, 28, 317.
[16] a) B. Karimi, A. Biglari, J. H. Clark, V. Budarin, Angew. Chem.
Int. Ed. 2007, 46, 7210. b) B. Karimi, H. M. Mirzaei, A.
Mobaraki, Catal. Sci. Technol. 2012, 2, 828.
ORCID
Elham Safaei http://orcid.org/0000-0002-3019-274X
[17] a) P. Xu, H. Yu, X. Li, Anal. Chem. 2011, 83, 3448. b) L. Gao, Y.
Wang, J. Wang, L. Huang, L. Shi, X. Fan, Z. Zou, T. Yu, M. Zhu,
Z. Li, Inorg. Chem. 2006, 45, 6844.
REFERENCES
[1] S. Patai, Z. Rappoport, Syntheses of Sulphones, Sulphoxides and
Cyclic Sulphides, John Wiley 1994.
[18] a) A. Popat, J. Liu, Q. Hu, M. Kennedy, B. Peters, G. Q. Lu, S. Z.
Qiao, Nanoscale 2012, 4, 970. b) N. Gargiulo, A. Peluso, P.
Aprea, F. Pepe, D. Caputo, J. Chem. Eng. Data 2014, 59, 896.
[2] J.‐E. Bäckvall, Modern Oxidation Methods, John Wiley 2011.
[19] a) C. T. Kresge, M. E. Leonowicz, W. J. Roth, J. C. Vartuli, J. S.
Beck, Nature 1992, 359, 710. b) J. S. Beck, J. C. Vartuli, W. J.
Roth, M. E. Leonowicz, C. T. Kresge, K. D. Schmitt, C. T. W.
Chu, D. H. Olson, E. W. Sheppard, J. Am. Chem. Soc. 1992,
114, 10834.
[3] J. Xu, S. Zhao, W. Chen, M. Wang, Y.‐F. Song, Chem. – Eur. J.
2012, 18, 4775.
[4] B. M. Trost, T. N. Salzmann, K. Hiroi, J. Am. Chem. Soc. 1976,
98, 4887.
[5] P. Kowalski, K. Mitka, K. Ossowska, Z. Kolarska, Tetrahedron
2005, 61, 1933.
[20] a) J. Y. Ying, C. P. Mehnert, M. S. Wong, Angew. Chem. Int. Ed.
1999, 38, 56. b) F. Schüth, Chem. Mater. 2001, 13, 3184. c) Y.
Wan, D. Zhao, Chem. Rev. 2007, 107, 2821.
[6] a) B. Karimi, M. Khorasani, ACS Catal. 2013, 3, 1657. b) K.
Kaczorowska, Z. Kolarska, K. Mitka, P. Kowalski, Tetrahedron
2005, 61, 8315. c) M. K. Panda, M. M. Shaikh, P. Ghosh, Dalton
Trans. 2010, 39, 2428.
[21] Y. Han, D. Zhang, Curr. Opin. Chem. Eng. 2012, 1, 129.
[22] a) W. J. Stevens, K. Lebeau, M. Mertens, G. Van Tendeloo, P.
Cool, E. F. Vansant, J. Phys. Chem. B 2006, 110, 9183. b) F.
Zhang, Y. Yan, H. Yang, Y. Yan, C. Yu, B. Tu, D. Zhao,
J. Phys. Chem. B 2005, 109, 8723. c) N. Rahmat, A. Z. Abdullah,
A. R. Mohamed, Am. J. Appl. Sci. 2010, 7, 1579.
[7] a) C. W. Jones, Applications of Hydrogen Peroxide and Deriva-
tives, Vol. 2, Royal Society of Chemistry 1999. b) R. Noyori, M.
Aoki, K. Sato, Chem. Commun. 1977–1986, 2003. c) B. S. Lane,
K. Burgess, Chem. Rev. 2003, 103, 2457. d) G. Grigoropoulou, J.
H. Clark, J. A. Elings, Green Chem. 2003, 5, 1.
[23] A. Sokolowski, J. Müller, T. Weyhermüller, R. Schnepf, P.
Hildebrandt, K. Hildenbrand, E. Bothe, K. Wieghardt, J. Am.
Chem. Soc. 1997, 119, 8889.
[8] R. H. Holm, Chem. Rev. 1987, 87, 1401.
[9] a) C. J. Hinshaw, G. Peng, R. Singh, J. T. Spence, J. H. Enemark,
M. Bruck, J. Kristofzski, S. L. Merbs, R. B. Ortega, P. A. Wexler,
Inorg. Chem. 1989, 28, 4483. b) Y.‐L. Wong, Y. Yan, E. S. H.
Chan, Q. Yang, T. C. W. Mak, D. K. P. Ng, J. Chem. Soc. Dalton
Trans. 1998, 3057.
[24] D. Zhao, Q. Huo, J. Feng, B. F. Chmelka, G. D. Stucky, J. Am.
Chem. Soc. 1998, 120, 6024.
[25] K. Inumaru, T. Ishihara, Y. Kamiya, T. Okuhara, S. Yamanaka,
Angew. Chem. Int. Ed. 2007, 46, 7625.
[26] R. Ryoo, I.‐S. Park, S. Jun, C. W. Lee, M. Kruk, M. Jaroniec,
J. Am. Chem. Soc. 2001, 123, 1650.
[10] R. H. Holm, E. I. Solomon, A. Majumdar, A. Tenderholt, Coord.
Chem. Rev. 2011, 255, 993.
[27] a) Y. Li, X. Fu, B. Gong, X. Zou, X. Tu, J. Chen, J. Mol. Catal. A
2010, 322, 55. b) J. Moulder, W. Stickle, P. Sobol, K. Bomben,
Handbook of X‐ray Photoelectron Spectroscopy, PerkinElmer
Corporation, Eden Prairie, MN 1992 52.
[11] a) R. R. Chowdhury, A. K. Crane, C. Fowler, P. Kwong, C. M.
Kozak, Chem. Commun. 2008, 94. b) R. Mayilmurugan, M.
Sankaralingam, E. Suresh, M. Palaniandavar, Dalton Trans.
2010, 39, 9611. c) E. Safaei, I. Saberikia, A. Wojtczak, Z. Jagličić,
A. Kozakiewicz, Polyhedron 2011, 30, 1143. d) E. Safaei, H.
Sheykhi, A. Wojtczak, Z. Jagličić, A. Kozakiewicz, Polyhedron
[28] G. D. Chukin, V. I. Malevich, J. Appl. Spectrosc. 1977, 26, 223.
[29] S. Shylesh, A. Singh, J. Catal. 2004, 228, 333.

14 of 14
SABERIKIA ET AL.
[30] J. H. Enemark, C. G. Young, Adv. Inorg. Chem. 1994, 40, 2.
[31] C. S. J. Chang, J. H. Enemark, Inorg. Chem. 1991, 30, 683.
SUPPORTING INFORMATION
Additional Supporting Information may be found online
in the supporting information tab for this article.
[32] R. D. Chakravarthy, K. Suresh, V. Ramkumar, D. K. Chand,
Inorg. Chim. Acta 2011, 376, 57.
[33] H. Lempers, R. Sheldon, J. Catal. 1998, 175, 62.
How to cite this article: Saberikia I, Safaei E,
Karimi B, Lee Y‐III. Oxygenation of sulfides
catalysed by SBA‐15‐immobilized molybdenum(VI)
complex of a bis(phenol) diamine ligand using
aqueous hydrogen peroxide as a green oxidant.
Appl Organometal Chem. 2018;e4304. https://doi.
org/10.1002/aoc.4304
[34] a) E. Zamanifar, F. Farzaneh, J. Simpson, M. Maghami, Inorg.
Chim. Acta 2014, 414, 63. b) A. Rostami, B. Tahmasbi, F. Abedi,
Z. Shokri, J. Mol. Catal. A 2013, 378, 200. c) A. Fuerte, M.
Iglesias, F. Sánchez, A. Corma, J. Mol. Catal. A 2004, 211, 227.
[35] A. Fuerte, J. Mol. Catal. A 2004, 211, 227.
[36] M. Khoshroo, H. Hosseini‐Monfared, J. Inorg. Organomet.
Polym. Mater. 2017, 27, 165.