Heteropolymetallic complexes containing ReO4-: Catalytic oxidation of sulfide

Article abstract of DOI:10.1016/j.ica.2012.12.020

Heteropolymetallic complexes [(salen)Ti(ReO₄)₂] (1) and [{(salen)Ti(ReO₄)}₂(μ-O)] (2) are easily obtained in high yields via reaction of [(salen)TiCl₂] and [{(salen)TiCl ₂}₂(μ-O)] with (Me₃SiO)ReO₃, respectively (where, salen = (S,S)-N,N′-bis(3,5-di-tert-butylsalicylidene) cyclohexane-1,2-diamine dianion). The structure of complex 2 was established by single-crystal X-ray diffraction. The tetrahedral geometry of the ReO ₄^- anion links the dititanium unit of {(salen)Ti} ₂(μ-O) in the axial positions. The Re-O-Ti bridge angles range from 146.1(2) to 162.6(2) with a Re?Ti separation of 3.780 A?. Complexes 1 and 2 are capable of catalytic oxidation of sulfides with ^tBuOOH.

Full text of DOI:10.1016/j.ica.2012.12.020

Inorganica Chimica Acta 398 (2013) 113–116
Contents lists available at SciVerse ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
ꢀ
Heteropolymetallic complexes containing ReO : Catalytic oxidation of sulfide
4
a
b,c
a
d
a,d,
⇑
Chen Li , Xiao Peng , Shou-Chun Zhang , Li-Yuan Chai , Xiao-Yi Yi
a
School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha,
Hunan 410083, PR China
College of Life Sciences, Shen Zhen University, Shen Zhen 518060, PR China
b
c
Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shen Zhen University,
Shen Zhen 518060, PR China
d
Institute of Environmental Engineering, Central South University, Changsha, Hunan 410083, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 19 October 2012
Received in revised form 4 December 2012
Accepted 5 December 2012
Available online 29 December 2012
Heteropolymetallic complexes [(salen)Ti(ReO ) ] (1) and [{(salen)Ti(ReO )} (
2
l
-O)] (2) are easily obtained
SiO)ReO , respectively
4
2
4
in high yields via reaction of [(salen)TiCl
2
] and [{(salen)TiCl
2
}
2
(
l
-O)] with (Me
3
3
0
(where, salen = (S,S)-N,N -bis(3,5-di-tert-butylsalicylidene)cyclohexane-1,2-diamine dianion). The struc-
ture of complex 2 was established by single-crystal X-ray diffraction. The tetrahedral geometry of the
ꢀ
ReO
4
2
anion links the dititanium unit of {(salen)Ti} (l-O) in the axial positions. The Re–O–Ti bridge
angles range from 146.1(2) to 162.6(2) with a Reꢁ ꢁ ꢁTi separation of 3.780 Å. Complexes 1 and 2 are capa-
Keywords:
Perrhenate
Heteropolymetallic
Sulfide oxidation
t
ble of catalytic oxidation of sulfides with BuOOH.
Ó 2012 Elsevier B.V. All rights reserved.
1
. Introduction
Zr, U) [17–20] or RuII
the Mn–Re complex [Mn
/ReVII [21] have been reported. For instance,
2
2 4 2
(saltmen) (ReO )
] (saltmen2 = N,N -
ꢀ
0
2
Heteropolymetallic complexes have recently proven active in a
(1,1,2,2-tetramethylethylene)bis(salicylideneiminate)) unambigu-
ously exhibits single-molecule magnetic behavior [22]. The Cu–
Re complexes [Cu(pc)(ReO )] and [Cu(pc)(ReO ) ] (pc = phthalocy-
4 4 2
anine) display a localized distribution of charge, that is contrary to
expected metallic conductivity [11,12].
number of catalytic transformations that are not accessible with
analogous monometallic complexes [1,2]. Many heterometallic
complexes have been prepared, including a few that show catalytic
activity [3–6]. For example, the Ru–Cr complexes [Ru(N)(CH2-
ꢀ
3
SiMe )
2
(l-O)
2
CrO
2
]
with chromate group coordinating to nitri-
Recently, Chaudhury groups have reported heterometallic com-
0
do(dialkyl)metal center through two oxo ligands, catalyze the
selective oxidation of alcohols with molecular oxygen. The hydride
abstraction by a chromium oxo group is observed in the concerted
b-hydrogen elimination mechanism [7]. So, it seems like that me-
tal-oxo anions are excellent candidates for forming the heterome-
tallic complexes.
plex [(metsalen)VO(ReO
cylideneimine)), of which ReO
4
)]ꢁH
2
O (metsalen = N,N -ethylene bis(sali-
ꢀ
4
coordinates axially to the
vanadium metal centers [23]. Redox behavior of this compound
V
indicates the reducing electron enters the V center and remains
V
VII
partially delocalized between the V and Re centers. That gives
an opportunity to solubilize a perrhenate anion in organic solvents
for its potential use as catalyst for various oxidation reactions on
organic substrates. In our research, we have found the perrhenate
4ꢀ
The perrhenate group (ReO ) is a weak coordinating anion,
which is not only used as a couterion, but also directly coordinates
other metal to form Re–O–M framework. The coordination chemis-
try of the perrhenate anion has received increasing attention due
to their applications in catalytic organic oxidations, magnetic and
supramolecular structure study. To date, the bimetallic complexes
0
anion can be activated by coordination with d metal center, nota-
IV
IV
4 3
bly Ti , Zr . The perrhenate group in [LOEtTi(ReO ) ] and [LOEt-
ꢀ
ꢀ
Zr(ReO ) (H O)] (where LOEt = [CpCo{P(O)(OEt) } ] ) are capable
4 3 2 2 3
of catalyzing oxidation of methyl p-tolyl sulfide in presence of oxi-
dant [19]. We set out to extend heterometallic perrhenate coordi-
nation chemistry into asymmetric oxidation reaction. Herein we
describe the synthesis and structural studies of heteropolymetallic
I
VII
II
VII
IV
VII
with Ag /Re [8], M /Re (M = Fe, Ni, Cu) [9–16], M /Re (M = Ti,
⇑
Corresponding author at: School of Chemistry and Chemical Engineering, Key
Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education,
Central South University, Changsha, Hunan 410083, PR China. Tel./fax: +86 731
8879616.
E-mail address: xyyi@csu.edu.cn (X.-Y. Yi).
complexes [(salen)Ti(ReO
4
)
2
] (1) and [{(salen)Ti(ReO
4
)}
2
(
l
-O)] (2)
0
(salen = (S,S)-N,N -bis(3,5-di-tert-butylsalicylidene)cyclohexane-1,2-
t
diamine dianion) The catalytic oxidation of sulfides under BuOOH
is also reported.
8
0
020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2012.12.020

1
14
C. Li et al. / Inorganica Chimica Acta 398 (2013) 113–116
Table 1
2
. Experimental
Crystallographic data and experimental details for complex [2]
2
ꢁ4Et
2
O.
2.1. General
Complex
Formula
[2]
2
ꢁ4Et
2
O
C
80
H
124
4
N O
15Re
2
Ti
2
Formula weight
Crystal system
Space group
a (Å)
b (Å)
c (Å)
1850.03
Monoclinic
P2
19.9022(1)
17.8522(1)
24.9096(1)
90.652(1)
8849.76(8)
4
All manipulations were carried out under nitrogen by standard
Schlenk techniques unless otherwise stated. Solvents were puri-
1
1
fied, distilled and degassed prior to use. H NMR spectra were re-
corded on a Bruker AV 400 spectrometer operating at 400 MHz,
and chemical shifts (d, ppm) were reported with reference to
b (°)3
SiMe
PC FT-IR spectrophotometer. Elemental analyses were performed
by a PE240C elemental analyzer. The startings [(salen)TiCl ] and
{(salen)TiCl} -O)] were prepared according to literature meth-
4
. Infrared spectra (KBr) were recorded on a Perkin-Elmer 16
V (Å )
Z
q
ꢀ
3)
2
calc, (g cm
1.389
T (K)
133(2)
1.5418
7.174
[
2
(l
k (Å)
l
ods [26]. tert-Butyl hydroperoxide (TBHP, 5 M in decane) and sul-
fides were obtained from J&K Scientific Ltd.
(mm 1
ꢀ
)
F(000)
3784
No. of reflections
58968
No. of independent reflections
26226
0.0424
1.008
0.0359, 0.0836
0.0397, 0.0849
2
.2. Synthesis of [(salen)Ti(ReO
4
)
2
] (1)
Rint
a
Goodness-of-fit (GOF)
b
c
R
R
1
, wR
, wR
2
[I > 2
r
(I)]
To a solution of (Me
4 mL) was added solution of [(salen)TiCl
CH Cl (8 mL). The reaction mixture was stirred overnight. The sol-
vent was removed in vacuum and the brown-red solid was washed
with Et Cl –Et O–hexane
1:15:4 mL) afforded the needle brown-red crystals. Yield: 80 mg
3
SiO)ReO
3
(138 mg, 0.43 mmol) in CH
2 2
Cl
1
2
(all data)
(
2
] (73 mg, 0.11 mmol) in
a
b
c
|) /(Nobs ꢀ Nparam)]½
2
GOF = [
R
w(|F
| ꢀ |F
w|F
| ꢀ |F
o
| ꢀ |F
c
.
2
2
R
1
=
R
||F
o
c
||/ |F
R
o
|.
2
2
|2]½.
wR
2
[(
R
o
c
|) /
R
w |F
o
2
O (3 ꢂ 3 mL). Recrystallization from CH
2
2
2
(
(
1
67%). H NMR (CDCl
3
): d 1.38 (s, 18H, tBu), 1.56 (s, 18H, tBu),
.52–1.58 (m, 4H, –CH ), 2.15 (m, 2H, –CH ), 2.65 (m, 2H, –CH ),
.65 (m, 2H, –CH ), 7.41 (d, J = 1.2, 2H, Ph), 7.68 (d, J = 1.2, 2H,
Table 2
Selected bond distances (Å) and angles (°).
1
3
2
2
2
2
ꢀ
1
Re1–O11
Re1–O12
Re1–O13
Re1–O14
Re2–O15
Re2–O16
Re2–O17
Re2–O18
Re3–O19
Re3–O20
Re3–O21
Re3–O22
Re4–O23
Re4–O24
Re4–O25
Re4–O26
Ti1–O1
1.738(4)
1.712(6)
1.698(7)
1.680(7)
1.776(5)
1.710(5)
1.697(5)
1.701(5)
1.756(4)
1.700(5)
1.719(6)
1.698(6)
1.750(4)
1.725(5)
1.695(6)
1.714(6)
1.851(4)
1.853(4)
1.806(4)
2.137(5)
Ti1–N1
Ti1–N2
Ti2–O3
Ti2–O4
Ti2–O9
Ti2–O15
Ti2–N3
Ti2–N4
Ti3–O5
Ti3–O6
Ti3–O10
Ti3–O19
Ti3–N5
Ti3–N6
Ti4–O7
Ti4–O8
Ti4–O10
Ti4–O23
Ti4–N7
Ti4–N8
2.137(4)
2.128(5)
1.859(4)
1.850(4)
1.824(4)
2.105(4)
2.148(5)
2.140(5)
1.850(4)
1.852(4)
1.827(4)
2.098(4)
2.133(5)
2.140(4)
1.864(4)
1.852(4)
1.804(4)
2.149(4)
2.132(4)
2.145(5)
Ph), 8.41 (s, 2H, N = CH) ppm. IR (KBr, cm ): 605(m), 658(w),
7
1
1
3
23(w), 764(m), 819(vs), 849(s), 872(s), 918(vs), 1025(w),
183(w), 1206(w), 1248(s), 1270(m), 1298(w), 1324(w), 1361(w),
392(w), 1440(w), 1463(w), 1558(m), 1610(s), 2868(m), 2958(s),
ꢀ
1
2
442(br, w). UV–vis(CH3CN) [kmax, nm (
e
O
, mol
TiRe
0.38; H, 5.08; N, 2.48. Found: C, 40.86; H, 5.27; N, 2.26%.
cm )]: 249
ꢁ0.5Et O: C,
(
43300), 302 (14200). Anal. Calc. for C36
H
52
10
N
2
2
2
4
4 2 2
2.3. Synthesis of [{(salen)Ti(ReO ) } (l-O)] (2)
A
3
mixture of (Me SiO)ReO
3
(71 mg, 0.22 mmol) and
Cl (10 mL) was
[
{(salen)TiCl -O)] (127 mg, 0.10 mmol) in CH
2
}
2
(l
2
2
stirred overnight, of which color changed from orange to darkish
red. The solvent was removed in vacuum and the resulted dark-
ish-red solid was washed with hexane. Extraction of CH
layered with Et O–hexane to afford single needle red crystals
which were suitable for the X-ray diffraction study. Yield:
Ti1–O2
Ti1–O9
Ti1–O11
2 2
Cl was
2
O12–Re1–O11
O13–Re1–O11
O13–Re1–O12
O14–Re1–O11
O14–Re1–O12
O14–Re1–O13
O16–Re2–O15
O17–Re2–O15
O17–Re2–O16
O17–Re2–O18
O18–Re2–O15
O18–Re2–O16
Ti1–O9–Ti2
110.1(3)
109.7(3)
107.9(3)
109.5(3)
109.1(4)
110.5(4)
107.9(2)
109.5(2)
109.4(3)
109.0(3)
111.0(2)
109.9(3)
170.9(3)
160.9(2)
150.9(2)
O20–Re3–O19
O20–Re3–O21
O21–Re3–O19
O22–Re3–O19
O22–Re3–O20
O22–Re3–O21
O24–Re4–O23
O25–Re4–O23
O25–Re4–O24
O25–Re4–O26
O26–Re4–O23
O26–Re4–O24
Ti4–O10–Ti3
111.0(2)
108.4(3)
109.4(3)
109.2(3)
109.6(3)
109.2(3)
110.1(2)
110.3(2)
108.9(3)
108.6(4)
109.3(2)
109.7(3)
166.8(2)
162.6(2)
146.1(2)
1
1
42 mg (85%). H NMR (CDCl
tBu), 1.35 (s, 18H, tBu), 1.41 (s, 18H, tBu), 1.55 (m, 8H, –CH
.69 (m, 4H, –CH ), 1.92 (m, 2H, –CH ), 2.47 (m, 2H, –CH ), 2.37
m, 4H, –CH ), 7.20 (d, J = 1.0, 2H, Ph), 7.26 (2H, Ph), 7.50 (d,
J = 1.0, 2H, Ph), 7.59 (d, J = 1.0, 2H, Ph), 8.07 (s, 2H, N = CH), 8.24
3
): d 1.19 (s, 18H, tBu), 1.34 (s, 18H,
2
),
1
(
2
2
2
2
ꢀ
1
(
s, 2H, N = CH) ppm. IR (KBr, cm ): 551(m), 593(s), 646(m),
7
1
1
3
16(vs), 761(s), 801(s), 850(s), 917(s), 1020(s), 1097(s), 1180(m),
202(m), 1254(vs), 1393(s), 1359(m), 1393(m), 1440(m),
464(m), 1555(m), 1615(vs), 2864(m), 2911(m), 2959(vs),
ꢀ
1
2
435(br, w). UV–vis(CH3CN) [kmax
,
nm
(e
,
mol cm )]: 256
Ti Re : C, 50.82;
H, 6.16; N, 3.29. Found: C, 50.16; H, 5.85; N, 3.42%.
Re1–O11–Ti1
Re2–O15–Ti2
Re3–O19–Ti3
Re4–O23–Ti4
(
30270), 384 (9730). Anal. Calc. for C72
H
104
O
13
N
4
2
2
2.4. Catalytic oxidation of sulfides with TBHP
2.5. X-ray crystallography
Typically,
a
mixture of sulfide (0.10 mmol), oxidant
mol) in 2 mL of CH Cl
Complex [2]
GeminiTMS Ultra with CCD Area Detector with monochromatized
Cu-K radiation (k = 1.54178 Å). Data collection and reduction
were carried out using CrysAlisPro 171.32.5. Absorption correction
was performed using SADABS built-in the CrysAlisPro program suite
2
ꢁ4Et
2
O were collected on an Oxford Diffraction
(
0.50 mmol), and 1.0 mol% of catalyst (1.0
l
2
2
was stirred at room temperature under nitrogen. The organic prod-
ucts were determined by GLC analysis using iodobenzene as inter-
nal standard.
a

C. Li et al. / Inorganica Chimica Acta 398 (2013) 113–116
115
ꢀ
1
ꢀ1
1
m
248 cm (for 1) and 1615, 1254 cm (for 2) regions due to the
(C@N) and (C–O/phenolate) stretching modes of the coordinated
Shiff base moieties, respectively. A sharp strong band at 918 cm
m
ꢀ
4ꢀ
1
ꢀ1
for 1, and 917 cm for 2 are observed due to the presence of ReO
anion in the unidentate mode of coordination [6,13,24]. The 1
NMR spectrum of complex 1 in CDCl displays two singlet at
d = 1.38, 1.56 ppm due to the Bu protons along with a singlet at
d = 8.41 ppm assignable to imino proton in the salen ligand. In
complex 2, the singlet peaks at 1.19, 1.34, 1.35 and 1.41 ppm are
H
3
t
t
assigned to Bu, and peaks at 8.07 and 8.24 ppm are attributed to
imino protons.
The crystallographic data and experimental details for complex
[
2]
2
ꢁ4Et
2
O are shown in Table 1. The selected bond distances and
angles are listed in Table 2. The perspective view of complex 2 is
displayed in Fig. 1. The complex crystallizes in a monoclinic space
1
group P2 with two molecular units of 2 and four cocrystallized
IV
ether molecules per cell. 2 is non-centrosymmetric. The Ti is
equatorially hexa-coordinated by two O atoms and two N atoms
from salen ligand, and axially coordinated with two O atoms con-
tributed by bridged-oxo from Ti–O–Ti and O–ReO
respectively. Ti atoms move out of the N least-squares meridian
plane by 0.359–0.385 Å toward the apical bridged O9 or O10
atoms, which is similar that of [{(salen)Ti(CH CO)} -O)] [25]. In
3
fragments,
Fig. 1. The molecular structure of complex 2 (The hydrogen atoms are omitted for
clarity. Probability of ellipsoids of 50% is shown).
2 2
O
3
2
(l
the basal plane, the average Ti–Ophenoxo and Ti–Nimino bond lengths
are 1.854 and 2.138 Å, respectively, comparable with those previ-
ously reported complexes containing (salen)Ti species. The average
bond of Ti–O(Ti) (1.815 Å) is significantly shorter than that of Ti–
[
30]. Structures were solved by direct methods and refined by full-
2
matrix least-squares on F using the SHELXTL software package [31].
Atomic positions of non-hydrogen atoms were refined with aniso-
tropic parameters. All hydrogen atoms were introduced at their
O
itive
(ReO4) (2.122 Å), which could be attituded to the stronger compet-
geometric positions and refined as riding atoms. In [2]
2
ꢁ4Et
2
O, four
VI
p
-bonding of the Ti with O atom from bridged-oxo of Ti–O–
ether molecules were co-crystallized. Two of them are disordered
and refined with appropriate partial occupancies. The butyl groups
of salen ligands were also found to be disordered. Carbon atoms
C73, C74, C75 are 70:30 disordered, C123, C124, C125 are 50:50
disordered and C173, C174 and C175 on butyl groups are 60:40
disordered.
ꢀ
Ti than that with O from ReO
4
. The bond angle of Ti–O–Ti (168.9°)
is more linear than that of Ti–O–Re (147.6°). The rhenium atoms
are pseudotetrahedral and are surrounded by three terminal oxy-
gens and one oxygen bonded to the titanium atom. The Re–Obridg-
ing distances of (1.738(4)–1.776(5) Å) are longer than that of Re–
Oterminal (1.680(7)–1.719(6) Å). The O–Re–O angles vary from
1
3
07.9(2) to 111.3(2)°. The average Tiꢁ ꢁ ꢁRe separation in 2 is
.780 Å. The bond distances and angles around the Re atoms are
3
. Results and discussions
very similar to those of bimetallic complexes containing coordi-
nated ReO
ꢀ
group [9–21].
No reaction happened in presence of NaReO
4
in the solution of
] with
led to isolation of 1 in low yield, as evi-
denced by NMR spectroscopy. 1 could be isolated in ca. 67% yield
by treatment of excess of (SiMe O) ReO with [(salen)TiCl ] in CH2-
Cl . Complex 2 was obtained in ca. 85% yield under the similar pro-
cedure. The driving force of these reactions is the formation of
Me SiCl. Complex 1 and 2 are soluble in common organic solvent
such as CH Cl and tetrahydrofuran, but insoluble in ether and
4
IV
VII
The catalytic activity of Ti /Re complex 1 was examined
using methyl phenyl sulfide as a representative substrate under
different reaction conditions. Variations in catalyst loading, oxi-
dants, reaction times and solvents are summarized in Table 3.
Among the solvents examined, the optical yield showed a remark-
able solvent dependence (entry 1–4). CH Cl seemed to be suitable
2 2
for the reaction. The yield of sulfoxide did not significantly rise
with an increase of the loading of catalyst (entry 4,5). Thus,
[
(salen)TiCl
2 2 2 2
] in CH Cl , whereas treatment of [(salen)TiCl
two equivalents of AgReO
4
3
3
2
2
3
2
2
1
mol% of catalyst loading was chosen. The reaction provided an
hexane. The complexes 1 and 2 are medium air stable. It decom-
posed into brown solid after exposed in air for few weeks. The IR
spectra of 1 and 2 shows a couple of strong bands at 1610,
excellent selectivity when the oxidant was cumene hydroperoxide,
whereas more catalyst loading (2.5 mol%) and longer reaction time
Table 3
a
Catalytic oxidation of methyl phenyl sulfide.
Entry
Catalyst
Catalyst loading (mol%)
Oxidant
Time (h)
Solvent
CH CH
THF
Sulfoxide (%)b
Sulfone (%)b
1
2
3
4
5
6
7
8
1
1
1
1
1
1
1
1
1
1
TBHP
TBHP
TBHP
TBHP
TBHP
CHP
TBHP
TBHP
TBHP
TBHP
1
1
1
1
1
2
2
2
144
3
3
2
OH
20
25
22
52
67
59
2
3
61
2
5
7
4
16
20
1
Trace
Trace
Trace
Trace
C
6
H
5
CH
3
CH
2
CH
2
CH
2
CH
2
CH
2
CH
2
CH
2
Cl
2
Cl
2
Cl
2
Cl
2
Cl
2
Cl
2
Cl
2
5
2.5
2.5
2.5
4.5
5
[(salen)TiCl
2
]
[{(salen)TiCl}
2
(
l
l
-O)]
-O)]
c
0
9
[{(salen )TiCl}
2
(
n
1
0
4 4
[ Bu N][ReO ]
a
b
c
Reaction conditions: 0.1 mmol methyl phenyl sulfide, 2 mL solvent, room temperature, TBHP = t-butyl hydroperoxide, CHP = cumene hydroperoxide.
Determined by GC.
0
0
0
Ref. [26], salen = (R,R )-N,N -(disalicylidene)cyclohexane-1,2-diamine dianion.

1
16
C. Li et al. / Inorganica Chimica Acta 398 (2013) 113–116
VII
Table 4
Re complexes can efficiently catalyze oxidation of sulfides with
Oxidation of various sulfide catalyzed by complexes 1 and 2.a
t
BuOOH. Presumably, Re peroxo species as the reactive intermedi-
ates are involved in the Ti /Re catalyst system.
IV
VII
O
O
O
S
S
S
TBHP, CH Cl2
2
Acknowledgements
R
R
+
R
RT, 1 mol% cat.
This work was supported by the National Natural Science Foun-
dation of China (Project 21001118), China Postdoctoral Science
Foundation (2011M500129), The Postdoctoral Science Foundation
of Central South University, the Fundamental Research Funds for
the Central Universities and Foundation of Hu’nan Educational
Substrate
Yield (%)b
Sulfoxide
77
Sulfone
1
2
3
S
22
25
(1)
(2)
⁄⁄
7
4
Committee (S2012R1040). Electronic supplementary information
ESI) available: Copies of the data can be obtained free of charge on
(
application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK.
S
66
17
15
(1)
(2)
6
2
Appendix A. Supplementary material
S
S
72
27
19
(1)
(2)
8
0
UV data of complexes 1 and 2; Crystallographic data for 2,
which has been deposited with the Cambridge Crystallographic
Data Centre as supplementary publication No. CCDC 903068. These
data can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via http://www.ccdc.cam.ac.uk/data_request/
cif. Supplementary data associated with this article can be found,
in the online version, at http://dx.doi.org/10.1016/j.ica.2012.
Br
Br
4
63
20
22
(1)
(2)
6
4
5
6
S
55
12
15
(1)
(2)
5
9
1
2.020.
S
57
18
14
(1)
(2)
4
9
References
a
Reaction condition: N
catalyst, 2 mL CH Cl , room temperature; reaction time 2 h.
Determined by GC.
2
atmosphere, 0.1 mmol sulfide, 0.5 mmol TBHP, 1.0 mol%
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[
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2 2
alyst in CH Cl (2 mL). The results are shown in Table 4. It was
[
[
found that complexes 1 and 2 have the similar reactivity and selec-
tivity for the reactions. All of aryl methyl sulfides, para-methyl-,
bromo-phenyl methyl sulfides were efficiently converted to the
corresponding sulfoxide and sulfone with high yields (Table 4, en-
tries 1–4). The conversion of diphenyl and t-butylmethyl sulfide
proceeded considerably slower, typically completed in more than
[
[
[
[
[
[
[
[
[
2
[
h under same conditions (Table 4, entries 5–6). Interestingly,
n
(salen)TiCl2], [{(salen)TiCl}
tive catalysts for the sulfide oxidation (Table 3). So, it suggests that
the coordinated ReO group in complexes 1 and 2 should be the po-
tential active component in the catalytic procedure. Lewis acid Ti
2 4
(l-O)] and [ BuN][ReO ] are not ac-
4
IV
ꢀ
IV
VII
center coordinates ReO
include ReO fragment as in methyl trioxorhenium (MTO). It is
noted that MTO and its derivatives are typical powerful oxidation
catalyst with H as the reagent [27–29]. So, presumably Re per-
4
3
to form (Ti –O)–Re O species, which
3
2 2
O
IV
oxo species as the reactive intermediates are involved in the Ti /
Re catalyst system. None of sulfoxide products with enantiose-
VII
[
[
[
[
lectivity are observed.
4
. Conclusion
In summary, we have shown that replacement of the chloride
ligand in the complexes [(salen)TiCl
by the perrhenate group generates heteropolymetallic complexes
and 2. Structural studies indicate Lewis acid Ti center coordi-
to form (Ti –O)–Re O species, which include ReO
3 3
fragment as in methyl trioxorhenium (MTO). The resulting Ti /
(
2002) 3301.
2 2
] and [{(salen)TiCl} (l-O)]
[
[
27] S. Yamazaki, Bull. Chem. Soc. Jpn. 69 (1996) 2955.
28] D.W. Lahti, J.H. Espenson, Inorg. Chem. 39 (2000) 2164.
[29] W. Adam, C.M. Mitchell, C.R. Saha-Möller, Tetrahedron 50 (1994) 13121.
[30] G.M. Sheldrick, University of Göttingen, Germany, 1997.
IV
1
ꢀ
IV
VII
nates ReO
4
[
31] G.M. Sheldrick, Bruker AXS Inc., Madison, Wisconsin, USA, 1997.
IV