Synthesis, crystal structure, and catalytic property of a vanadium(V) complex with mixed ligands

Article abstract of DOI:10.1134/S1070328415050061

With a tridentate hydrazone ligand N′-(3-bromo-2-hydroxybenzylidene)-2-methylbenzohy-drazide (H₂L) and a bidentate ligand benzohydroxamic acid (HL′) with VO(Acac)₂, a mononuclear vanadium(V) complex was prepared and characterized by elemental analysis, IR spectroscopy and X-ray structure determination (CIF file CCDC no. 1029909). The complex crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 27.870(2), b = 11.4893(5), c = 18.467(2) ?, β = 131.444(1)°, V = 4432.6(6) ?³, Z = 8, R ₁ = 0.0350, and wR ₂ = 0.0749. Single crystal X-ray diffraction analysis reveals that the V atom is coordinated by the phenolate O, imino N and enolate O atoms of the hydrazone ligand, and the carbonyl O and hydroxy O atoms of benzohydroxamate ligand, and one oxo O group, in an octahedral coordination. Catalytic oxidation of the complex on some olefins was performed.

Full text of DOI:10.1134/S1070328415050061

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2015, Vol. 41, No. 6, pp. 372–375. © Pleiades Publishing, Ltd., 2015.
Synthesis, Crystal Structure, and Catalytic Property
of a Vanadium(V) Complex with Mixed Ligands1
X. H. Shen*, Z. W. Zhang, L. J. Shao, Q. Lian, and C. Liu
Department of Chemistry, Hebei Normal University of Science & Technology, Qinhuangdao, 066600 P.R. China
*
eꢀmail: xihai_shen@163.com
Received October 20, 2014
Abstract—With a tridentate hydrazone ligand
N
'
ꢀ(3ꢀbromoꢀ2ꢀhydroxybenzylidene)ꢀ2ꢀmethylbenzohyꢀ
drazide (H L) and a bidentate ligand benzohydroxamic acid (HL
'
) with VO(Acac) , a mononuclear vanaꢀ
2
2
dium(V) complex was prepared and characterized by elemental analysis, IR spectroscopy and Xꢀray structure
determination (CIF file CCDC no. 1029909). The complex crystallizes in the monoclinic space group 2/
with unit cell dimensions = 27.870(2), = 11.4893(5), = 18.467(2) = 131.444(1) = 4432.6(6)
= 8, R1 = 0.0350, and wR2 = 0.0749. Single crystal Xꢀray diffraction analysis reveals that the V atom is coorꢀ
C
c
Å ,
3
a
b
c
Å,
β
°,
V
Z
dinated by the phenolate O, imino N and enolate O atoms of the hydrazone ligand, and the carbonyl O and
hydroxy O atoms of benzohydroxamate ligand, and one oxo O group, in an octahedral coordination. Cataꢀ
lytic oxidation of the complex on some olefins was performed.
DOI: 10.1134/S1070328415050061
1
INTRODUCTION
were dissolved in methanol (30 mL). The mixture was
refluxed for 30 min and the solvent was evaporated by
distillation. Colorless solid was recrysallized from
In recent years, the catalytic oxidation of olefins
has aroused much attention in the production of
chemicals and fine chemicals since epoxides are key startꢀ
ing materials for a wide variety of oily products [1–5]. Beꢀ
cause of the environment friendly nature, H O has
been regarded as the first selected oxidant in the oxiꢀ
dation of olefins. Transition metal complexes with varꢀ
ious ligands have presented interesting catalytic propꢀ Found, %:
erties [6–10]. Among the complexes, vanadium species
show efficient catalytic oxidation properties [11–16]. In
this paper, a new vanadium(V) complex with mixed
ligands
thylbenzohydrazide (H L) and a bidentate ligand benꢀ
zohydroxamic acid (HL') was prepared and its catalytꢀ
ic oxidation property was performed.
methanol to give pure product of H L. The yield
2
was 83%.
2
2
For C H BrN O
2 2
15
13
anal. calcd., %: C, 54.07;
H, 3.93;
H, 4.02;
N, 8.41.
N, 8.50.
C, 53.89;
–1
IR (KBr;
ν
, cm ): 3440
ν
(O–H); 3241 (N–H);
ν
1
646
ν
(C=O); 1608
H NMR (300 MHz; DMSOꢀd6):
2.22 (s., 1H), 8.63 (s., 1H), 7.2–7.7 (m., 5H), 6.93
ν
(C=N); 1175
ν
(C–OH).
N
'ꢀ(3ꢀbromoꢀ2ꢀhydroxybenzylidene)ꢀ2ꢀmeꢀ
2
1
δ
12.71 (s., 1H),
1
(t., 1H), 2.51 (s., 3H).
Synthesis of the complex. Equimolar quantities
(
VO(Acac)
1.0 mmol each) of H L (0.333 g), HL' (0.137 g) and
2
(0.265 g) were dissolved in methanol
EXPERIMENTAL
2
(
20 mL). The mixture was refluxed for 30 min and
Materials and methods. 3ꢀBromosalicylaldehyde,
ꢀmethylbenzohydrazide and benzohydroxamic acid
cooled to room temperature to give a deep brown soꢀ
lution. The solution was kept still in air for a week to
slow evaporate to give brown blockꢀshaped single crysꢀ
tals of the complex. The yield was 61%.
2
were purchased from Alfa Aesar. VO(Acac) and solꢀ
2
vents are commercially available and were used withꢀ
out further purification. Elemental analyses for carꢀ
bon, hydrogen, and nitrogen were carried out with an
Elementar Vario EL. Infrared spectra were measured
on KBr disks with a Hitachi Iꢀ5040 FTꢀIR spectroꢀ
For C H BrN O V
17
22
3 5
anal. calcd., %: C, 49.46;
H, 3.21;
H, 3.15;
N, 7.87.
N, 8.02.
1
Found, %:
C, 49.32;
photometer. H NMR data were recorded on a Bruker
NMR 300 MHz instrument.
–
1
IR (KBr;
ν
, cm ): 3445
(VO).
Catalytic oxidation experiment was carried out in a
50 mL glass roundꢀbottom flask fitted with a reflux
ν
(O–H); 3196
ν
(N–H);
Synthesis of H L. 3ꢀBromosalicylaldehyde (2.01 g,
2
0 mmol) and 2ꢀmethylbenzohydrazide (1.50 g, 10 mmol)
1
602
ν
(C=N); 976
ν
1
1
The article is published in the original.
372

SYNTHESIS, CRYSTAL STRUCTURE, AND CATALYTIC PROPERTY
373
Table 1. Crystallographic data and and structure refineꢀ condenser and placed in an oil bath at prearranged
ment for the complex
temperature under continuous stirring. The oxidation
was carried out as follows: the complex (0.032 mmol) was
dissolved in 10 mL 1,2ꢀdichloroethane. Then 10 mmol
alkene was added to the reaction mixture and 30 mmol
TBHP was added. The reaction mixture was refluxed
for 1 h. The reaction products were monitored at periꢀ
odic time intervals using gas chromatography. The oxꢀ
idation products were identified by comparison with
authentic samples (retention times in GC).
Parameter
Value
Formula weight
Crystal system
Space group
534.2
Monoclinic
C2/c
a
, Å
, Å
27.870(2)
11.4893(5)
18.467(2)
131.444(1)
4432.6(6)
8
b
Xꢀray structure determination. Data collection for
the complex was performed with a Bruker Apex II
CCD diffractometer at 298 K. The structure was solved
c
, Å
β
V
Z
ρ
, deg
, Å3
by direct methods with SHELXSꢀ97 and refined by fullꢀ
2
matrix least squares (SHELXLꢀ97) on
F
[17]. All nonꢀ
hydrogens were refined anisotropically. The hydrogen
atom of N(3) was located from a difference Fourier
map and refined isotropically, with N–H distance reꢀ
, g cm–3
1.601
calcd
F
(000)
, mm–1
2144
strained to 0.90(1)
placed geometrically and refined with a riding model, with
isotropic displacement coefficients (H) = 1.2 (C) or
.5 (C). Crystallographic data for the complex are
Å. The remaining hydrogens were
μ
2.289
U
U
θ
Range, deg
2.86–26.06
1
U
summarized in Table 1. Selected bond lengths and anꢀ
gles are listed in Table 2.
Index ranges hkl
–32
13
22
≤
h
k
≤
≤
≤
34,
14,
22
–
≤
Supplementary material for complex has been deꢀ
posited with the Cambridge Crystallographic Data
Centre (no. 1029909; deposit@ccdc.cam.ac.uk or http://
www.ccdc.cam.ac.uk).
–
≤
l
Reflections collected/unique
18693/4373
0.0279
Rint
Observed with
Parameters
I
> 2
σ
(
I
)
3500
RESULTS AND DISCUSSION
293
The vanadium complex was prepared by reaction of
equimolar quantities of the hydrazone ligand, benzoꢀ
Rastraints refined
Final index ( > 2
index (all data)
Goodnessꢀofꢀfit on F2
Δρmax/Δρmin,
Å–3
1
R
I
σ
(
I
))
0.0350, 0.0749
0.0506, 0.0835
1.040
hydroxamic acid and VO(Acac) in methanol. Crystals
2
of the complex are stable in air, and soluble in methaꢀ
nol, ethanol, DMF and DMSO, insoluble in water.
The hydrazone ligand and the complex have been
characterized by infrared spectroscopy. In the spectra
R
e
0.442/–0.361
Table 2. Selected bond distances (Å) and angles (deg) for the complex
Bond
d
, Å
Bond
d, Å
V(1)–O(1)
V(1)–O(3)
V(1)–O(5)
1.8697(18)
2.1904(19)
1.5855(19)
V(1)–O(2)
V(1)–O(4)
V(1)–N(1)
1.9755(17)
1.8655(17)
2.057(2)
Angle
ω
, deg
Angle
ω
, deg
O(5)V(1)O(4)
O(4)V(1)O(1)
O(4)V(1)O(2)
O(5)V(1)N(1)
O(1)V(1)N(1)
O(5)V(1)O(3)
O(1)V(1)O(3)
N(1)V(1)O(3)
95.00(9)
107.93(8)
88.95(7)
96.27(9)
84.72(8)
170.93(9)
82.16(8)
92.79(8)
O(5)V(1)O(1)
O(5)V(1)O(2)
O(1)V(1)O(2)
O(4)V(1)N(1)
O(2)V(1)N(1)
O(4)V(1)O(3)
O(2)V(1)O(3)
98.99(9)
100.76(9)
152.70(8)
161.51(8)
74.58(8)
76.16(7)
81.30(7)
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 41
No. 6
2015

374
SHEN et al.
C(18)
C(17)
N(3) C(16)
Br(1)
O(4)
C(19)
C(20)
C(4) C(3) O(1)
V(1)
C(22) C(21)
O(3)
O(2)
x
C(2)
C(5)
C(6)
O(5)
C(1)
C(7)
C(14)
C(13)
N(1)
N(2)
C(9)
C(8)
C(12)
C(11)
C(10)
C(15)
0
z
Fig. 1. The molecular structure of the complex with 30%
probability thermal ellipsoids.
of both H L and the complex, the broad bands cenꢀ
2
Fig. 2. Molecular packing structure of the complex, viewed
–1
along the
lines.
y
axis. Hydrogen bonds are shown as dashed
tered at about 3440 cm are assigned to the O–H viꢀ
brations of the water molecules. In the spectra of H2L
and the complex, the typical bands due to the N–H viꢀ
–1
–1
brations are observed at 3241 and 3196 cm , respecꢀ observed at 1602 cm [18], and the C=O absorption
tively. In the infrared spectrum of H L, absorption in the spectrum of H L is disappeared in that of the
2
2
bands appear attributed to N–H, C=O, C=N, and complex. The V=O stretching mode occur as a single
–1
–1
C–OH at 3241, 1646, 1608, and 1175 cm , respecꢀ sharp band at 976 cm [19].
tively. As a comparison, in the spectrum of the comꢀ
The molecular structure of the complex is shown in
plex, the strong band indicative of the C=N group is Fig. 1. The coordination geometry around vanadium
Table 3. Catalytic oxidation results*
Substrate
Product
Conversion, %**
O
6
9
7
Cl
7
Cl
O
O
86
93
82
O
Cl
Cl
O
*
The molar ratio of catalyst : substrate : TBHP is 1 : 300 : 1000. The reactions were performed in mixture of CH OH–CH Cl (V : V = 6 : 4;
3 2 2
1.5 mL).
** The GC conversion (%) was measured relative to the starting substrate after 1 h.
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 41
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2015

SYNTHESIS, CRYSTAL STRUCTURE, AND CATALYTIC PROPERTY
375
can be described as octahedral with the phenolate O,
imine N and enolate O atoms of the hydrazone ligand,
and the hydroxy O atom of the benzohydroxamate
ligand in the equatorial plane, and with the carbonyl O
atom of the benzohydroxamate ligand and one oxo O
group in the axial positions. The O(5)=V(1)–O(3) axꢀ
2. Amarante, T.R., Neves, P., Gomes, A.C., et al., Inorg.
Chem., 2014, vol. 53, no. 5, p. 2652.
3. Gomes, A.C., Bruno, S.M., Abrantes, M., et al.,
J. Organomet. Chem., 2014, vol. 760, p. 205.
4. Terfassa, B., Schachner, J.A., Traar, P., et al., Polyheꢀ
dron, 2014, vol. 75, p. 141.
5. Musacchio, A.J., Nguyen, L.Q., Beard, G.H., et al.,
is is almost linear with bond angle of 170.93(9)
°
. Beꢀ
cause of the trans influence of the oxo O group, the
distance of V(1)–O(3) is much longer than the other
bonds. Such elongation has previously been observed
in other complexes with similar structures [20, 21].
The V atom deviates from the equatorial plane by
J. Am. Chem. Soc., 2014, vol. 136, no. 35, p. 12217.
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6
7
8
9
0.255(1) Å. All the bond values are in good agreement
. Quintard, A. and Rodriguez, J., Angew. Chem. Int. Ed.
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0. Amini, M., Haghdoost, M.M., and Bagherzadeh, M.,
,
with those observed in vanadium(V) complexes with
hydrazone ligands [20–23].
In the crystal structure of the complex, molecules
are linked through intermolecular hydrogen bonds of
2
,
1
i
i
N(3)–H(3)⋅⋅⋅O(2) (N(3)–H(3) 0.90(1), H(3)⋅⋅⋅O(2)
i
Coord. Chem. Rev., 2014, vol. 268, p. 83.
2
.05(2), N(3)⋅⋅⋅O(2) 2.915(3)
i
Å
, N(3)–H(3)⋅⋅⋅O(2)i 11. Li, A.ꢀM., J. Coord. Chem., 2014, vol. 67, no. 12,
p. 2076.
1
60(3)°; symmetry code: –x, 1 – y, –z) and C(4)–
ii
ii
H(4)⋅⋅⋅O(5) (C(4)–H(4) 0.93, H(4)⋅⋅⋅O(5) 2.56(2), 12. Romanowski, G., Kira, J., and Wera, M., Polyhedron
,
ii
ii
2014, vol. 67, p. 529.
13. Maurya, M.R. and Kumar, N., J. Mol. Catal. A, 2014,
vol. 383, p. 172.
4. Ebrahimipour, S.Y., Abaszadeh, M., Castro, J., et al.,
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C(4)⋅⋅⋅O(5) 3.253(3)
ii
Å
symmetry code: –1/2 –
, C(4)–H(4)⋅⋅⋅O(5) 131(3)°;
, –1/2 + , –1/2 – ) to
x
form 1D chains, as shown in Fig. 2.
y
z
1
1
1
1
The catalytic results are given in Table 3. Effective
epoxide yields and 100% selectivity were observed for
all aliphatic and aromatic substrates. In general, oxiꢀ
dation of aromatic substrates gave the corresponding
epoxides in over 82% yields, while in the oxidation of
aliphatic substrates, the conversion is lower than 77%.
Based on this consideration, it can be observed that
the isolated double bonds are less reactive than the
conjugated ones. For both aliphatic and aromatic subꢀ
strates, the conversion for the chloroꢀsubstituted speꢀ
cies is higher than the methyl or no substituted ones.
7. Sheldrick, G.M., SHELXLꢀ97
ment of Crystal Structures, G ttingen (Germany): Univ.
of G ttingen, 1997.
, Program for the Refineꢀ
ö
ö
1
1
2
2
2
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Acta, 2010, vol. 363, no. 11, p. 2574.
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no. 7, p. 1689.
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ACKNOWLEDGMENTS
This work was supported by the Hebei Normal
University of Science & Technology.
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No. 6
2015

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