Synthesis and X-ray crystal structures of N'-(2-hydroxy-5- methoxybenzylidene)-4-dimethylaminobenzohydra zide and its oxovanadium(V) complex with catalytic property

Article abstract of DOI:10.1134/S1070328413120075

A new benzohydrazone compound N'-(2-hydroxy-5-methoxybenzylidene)-4- dimethylami- nobenzohydrazide (H2L) and its oxovanadium(V) complex [VOL(BHA)] · H₂O, where HBHA is benzohy- droxamic acid, were prepared and structurally characterized by physic-chemical methods and single crystal X-ray diffraction. The benzohydrazone compound crystallizes in the monoclinic space group C2/c with a = 35.5873(12), b = 10.4628(4), c = 18.6059(6) A, β = 109.499(1)°, V = 6530.4(4) A³, Z = 16, R1 = 0.0603, and wR₂ = 0.1575. The oxovanadium(V) complex crystallizes in the triclinic space group P with a = 7.4775(4), b = 9.7837(5), c = 17.7076(8) A, a = 99.457(2)°, β = 98.699(2)°, = 101.429(2)°, V = 1229.7(1) A³, Z = 2, R1 = 0.0431, and wR₂ = 0.0937. X-ray structural analysis indicates that the benzohydrazone ligand L ²- coor- dinates to the V atom through the phenolate O, imino N, and enolic O atoms. The V atom in complex I is coordinated by one benzohydrazone ligand and one BHA ligand, as well as one oxo O atom, forming an octa- hedral coordination. The crystal structures of H₂L and I are stabilized by hydrogen bonds. Complex I is an effective catalyst for sulfoxidation. Pleiades Publishing, Ltd., 2013.

Full text of DOI:10.1134/S1070328413120075

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2013, Vol. 39, No. 12, pp. 885–890. © Pleiades Publishing, Ltd., 2013.
Synthesis and Xꢀray Crystal Structures of N'ꢀ(2ꢀHydroxyꢀ5ꢀ
Methoxybenzylidene)ꢀ4ꢀDimethylaminobenzohydra Zide
and Its Oxovanadium(V) Complex with Catalytic Property1
Y. Z. Wanga, Y. Gaoa, Y. Q. Sub, *, P. Wangb, and C. Lib
aDepartment of Chemical Science & Technology, Kunming College, Kunming, 650031 P.R. China
bFaculty of Chemistry & Chemical Engineering, Yunnan Normal University, Kunming, 650500 P.R. China
*eꢀmail: yongqing_su@163.com
Received September 17, 2012
Abstract—A new benzohydrazone compound N'ꢀ(2ꢀhydroxyꢀ5ꢀmethoxybenzylidene)ꢀ4ꢀdimethylamiꢀ
nobenzohydrazide (H2L) and its oxovanadium(V) complex [VOL(BHA)] H2O, where HBHA is benzohyꢀ
⋅
droxamic acid, were prepared and structurally characterized by physicꢀchemical methods and single crystal
Xꢀray diffraction. The benzohydrazone compound crystallizes in the monoclinic space group 2/ with
35.5873(12), = 10.4628(4), = 18.6059(6) Å, = 109.499(1) = 16, 1 = 0.0603, and
= 6530.4(4) Å3,
wR2 = 0.1575. The oxovanadium(V) complex crystallizes in the triclinic space group with = 7.4775(4),
= 1229.7(1) Å3,
= 2,
1 = 0.0431, and wR2 = 0.0937. Xꢀray structural analysis indicates that the benzohydrazone ligand L2– coorꢀ
is
coordinated by one benzohydrazone ligand and one BHA ligand, as well as one oxo O atom, forming an octaꢀ
C
c
a =
b
c
β
°
,
V
Z
R
P
V
1
a
b
= 9.7837(5),
c
= 17.7076(8) Å,
α
= 99.457(2)
°
,
β
= 98.699(2)
°
,
γ
= 101.429(2)
°
,
Z
R
dinates to the V atom through the phenolate O, imino N, and enolic O atoms. The V atom in complex
I
hedral coordination. The crystal structures of H2L and
effective catalyst for sulfoxidation.
I are stabilized by hydrogen bonds. Complex I is an
DOI: 10.1134/S1070328413120075
1
INTRODUCTION
N
Schiff base complexes of transition metals have
H
attracted much attention in metalloꢀorganic and
coordination chemistry because of their interesting
structures and diverse range of applications [1–4],
especially for their catalytic properties [5–7]. Sulfoxꢀ
ides are widely used as drug intermediates in pharmaꢀ
ceutical industries, and also sulfinyl groups have
been used as auxiliaries in a variety of highly diastereꢀ
oselective carbon–carbon bond forming reactions,
MeO
N
N
O
OH
(H2L)
EXPERIMENTAL
All chemicals were of reagent grade and used as
including the synthesis of
αꢀbranched amines,
α
ꢀ
and ꢀamino acids, aziridines, and amino phosphonic
β
acids [8, 9]. Sulfoxidation catalyzed by complexes
of transition metals, such as titanium, manganese,
iron, molybdenum, and vanadium, have produced
interesting results in the synthesis of various sulfoxides
[10–12]. As a continuation to explore effective cataꢀ
lysts used in sulfoxidation, in the present paper, a new
benzohydrazone compound N'ꢀ(2ꢀhydroxyꢀ5ꢀmethoxyꢀ
benzylidene)ꢀ4ꢀdimethylaminobenzohydrazide (H2L)
purchased. Microanalyses of C, H, N were performed
on a PerkinElmerꢀ2400 Series II CHN analyser.
FTꢀIR spectra (4000–200 cm–1) of the ligand and the
complex were recorded on a PerkinElmer Spectrum
RX I FTꢀIR system with solid KBr pellets. H NMR
spectra were recorded on Bruker Avance 200 specꢀ
trometer.
1
and its oxovanadium(V) complex [VOL(BHA)]
⋅
H2O
Synthesis of H2L. Equimolar quantities of 5ꢀmethꢀ
oxysalicylaldehyde (0.152 g, 1 mmol) and 4ꢀdimeꢀ
thylaminobenzohydrazide (0.179 g, 1 mmol) were
mixed in 50 mL methanol. The mixture was stirred at
reflux for 30 min and the solvent was evaporated to give
(
I), where HBHA is benzohydroxamic acid, were preꢀ
pared and investigated for their peroxidic oxidation on
sulfides.
1
The article is published in the original.
885

886
WANG et al.
colorless crystalline product of H2L, which was used methoxybenzene (0.1 mol/L) as internal standard.
without further purification.
The resulting solution was cooled to 283 K and H2O2
(35% w/w) added dropwise (0.125 M). An aliquot of
the reaction solution (2.0 mL) was quenched with
5 mL of a stock 0.1 M solution of Na2SO3 at 60 min
and 2 h and extracted with dichlormethane (three
times 4 mL). From the collected organic phases, the
solvent was removed under reduced pressure to comꢀ
plete dryness and the residue redissoived in deuterated
For C17H19N3O3
anal. calcd., %: C, 65.16;
H, 6.11;
H, 6.19;
N, 13.41.
N, 13.54.
Found, %:
C, 65.02;
Synthesis of complex I. H2L (31.3 mg, 0.1 mmol)
and benzohydroxamic acid (13.7 mg, 0.1 mmol) were
dissolved in 15 mL methanol. The solution was then
added dropwise to a 10 mL gently warmed methanol
solution of VO(Acac)2 (26.5 mg, 0.1 mmol). The mixꢀ
ture was refluxed for 30 min and cooled to room temꢀ
perature. The resulting deep brown solution was filꢀ
tered and left undisturbed. After a few days, brown
block shaped Xꢀray diffraction quality single crystals
were formed and isolated by filtration. The yield was
28.2 mg (53%).
1
chloroform (0.6 mL) and analyzed by H NMR to
determine the yields with reference to the internal
standard 1,3,5ꢀtrimethoxybenzene.
RESULTS AND DISCUSSION
The condensation of 5ꢀmethoxysalicylaldehyde
with 4ꢀdimethylaminobenzohydrazide in methanol
with 1 : 1 stoichiometric ratio gave H2L. The benzohyꢀ
drazone ligand reacts with VO(Acac)2 in the presence
of benzohydroxamic acid yielded the oxovanadium
complex. Elemental analyses were found to be in
good agreement with the formulae calculated from the
Xꢀray determination.
For C24H25N4O7V
anal. caicd., %: C, 54.14;
Found, %: C, 54.23;
H, 4.73;
H, 4.82;
N, 10.52.
N, 10.37.
The sharp absorption bands located at 3281 cm–1 in
the infrared spectrum of H2L and at 3332 cm–1 in the
infrared spectrum of the complex are attributed to the
N–H stretches. The broad and weak bands indicative
Xꢀray crystallography. Diffraction quality single
crystals of H2L and complex were mounted on a Broꢀ
ker AXS SMART diffractometer with a graphite
I
of the (O–H) vibrations of the hydroxyl groups of the
ν
monochromator and Mo
K
radiation ( = 0.71073 Å).
λ
The crystallographic dataβcollection was performed
using multiscan technique at 298(2) K. Data collecꢀ
tion and the unit cell refinement were performed using
CrysAlisPRO software [13]. The structures of the
compounds were solved by direct method procedures
with SHELXS [14] and refined by fullꢀmatrix least
squares based on F2 with SHELXL [14]. The nonꢀ
hydrogen atoms were refined with anisotropic factors.
The amino H atoms in H2L and the water H atoms in
ligand and water molecules are in the range 3350–
3480 cm–1. The strong band observed at 1613 cm–1 is
attributed to the conjugated C=N–N=C moiety of
the benzohydrazone ligand. The middle band at
970 cm–1 is assigned to the V=O stretch [15]. The
bands due to
ν
(V–O) and (V–N) are occurred at
ν
440, 533, and 598 cm–1, respectively.
Figures 1 and 2 give perspective views of H2L and
the oxovanadium(V) complex. H2L crystallizes in the
monoclinic space group
C2/c
and complex
I crystalꢀ
complex I were located in difference Fourier maps and
refined isotropically with N–H, O–H, and H⋅⋅⋅H disꢀ
tances restrained to 0.90(1), 0.85(1), and 1.37(2) Å,
respectively. The remaining hydrogen atoms were
positioned geometrically treated as riding on their parꢀ
ent atoms. The O(6)–C(24) methoxy group of H2L is
disordered over two sites, with occupancies of 0.475(3)
and 0.525(3), respectively. The data collection and
refinement parameters are listed in Table 1. Selected
bond lengths and angles are given in Table 2. Geometꢀ
ric parameters of hydrogen bonds for compounds are
in Table 3.
lizes in the triclinic space group
P
1.
In the asymmetric unit of H2L, there contains two
independent molecules. In each of the molecules,
there is an intramolecular O–H⋅⋅⋅N hydrogen bond,
which contributes to the planarity of the benzene ring
and the methylidene unit. The dihedral angle between
the two benzene rings are 25.1(3)
°
for one molecule
, derived from
and 64.7(3) for the other. Complex
°
I
H2L and benzohydroxamic acid, is a mononuclear
compound. The benzohydrazone ligand L2– forms one
fiveꢀ and one sixꢀmembered chelate rings with bite
Supplementary material for structures H2L and
angles of 74.77(8)
amic acid ligand BHA– forms one fiveꢀmembered
chelate ring with bite angle of 74.86(7) . The V atom is
°
and 84.10(8)
°
. The benzohydroxꢀ
complex
Crystallographic Data Centre (nos. 901042 (H2L),
901043 ); deposit@ccdc.cam.ac.uk or http://
www.ccdc.cam.ac.uk).
I has been deposited with the Cambridge
°
(I
in a distorted octahedral O5N coordination sphere.
The phenolate O(l) atom, imine N(l) atom, and enolic
Catalytic oxidation. The oxovanadium complex O(2) atom of the benzohydrazone ligand L2–, and the
(0.001 mol/L) and phenyl methyl sulfide (0.1 mol/L) O(5) atom of the benzohydroxamic acid ligand BHA–
were dissolved at room temperature in a mixture of constitute the equatorial plane of the octahedral coorꢀ
CH2Cl2 and CH3OH (6 : 4) together with 1,3,5ꢀtriꢀ dination. The axial positions of the octahedral coordiꢀ
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
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SYNTHESIS AND XꢀRAY CRYSTAL STRUCTURES
Table 1. Crystal data and structure refinement for H2L and complex
887
I
Value
Parameter
H2L
I
Formula weight
Crystal system
313.4
532.4
Monoclinic
2/
Triclinic
Space group
C c
P
1
Crystal color/shape
Unit cell dimensions:
Colorless/block
Brown/block
a
, Å
, Å
, Å
, deg
, deg
, deg
35.5873(12)
10.4628(4)
18.6059(6)
90
7.4775(4)
9.7837(5)
17.7076(8)
99.457(2)
98.699(2)
101.429(2)
1229.66(11)
2
b
c
α
β
109.4990(10)
90
γ
Volume, Å3
6530.4(4)
16
Z
ρcalcd, g cm–3
1.275
1.438
Absorption coefficient, mm–1
0.089
0.455
F(000)
2656
552
θ
Range for data collection, deg
2.23–25.00
32616
2.17–25.50
13531
Reflections collected
Independent reflections
5587
4562
Observed reflections,
Restraints
I
> 2
σ
(
I
)
3226
3048
31
4
Parameters
447
337
Max and min transmission
0.9850 and 0.9894
1.031
0.9105 and 0.9226
1.032
Goodnessꢀofꢀfit on F2
Final
indices, all data
Largest diff. peak and hole,
R
indices,
I
> 2
σ
(
I
)
0.0603
0.0431
R
0.1575
0.0937
e
Å–3
0.421 and –0.351
0.217 and –0.312
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
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888
WANG et al.
Table 2. Selected bond lengths and bond angles for H2L Table 3. Geometric parameters of hydrogen bonds for H2L
and complex
I
and complex
I
Bond
d
, Å
Bond
d, Å
Distance, Å
⋅⋅⋅
Angle
DHA, deg
D–H⋅⋅⋅
A
H2L
D–H
H
A
D⋅⋅⋅A
C(8)–N(1)
N(2)–C(9)
1.275(4)
1.362(4)
1.280(4)
1.364(4)
N(1)–N(2)
C(9)–O(2)
N(4)–N(5)
C(26)–O(5)
1.371(4)
1.239(4)
1.381(4)
1.232(3)
H2L
N(2)–H(2)⋅⋅⋅O(5)i 0.90(1) 1.98(2) 2.825(3) 155(3)
N(5)–H(5)⋅⋅⋅O(2) 0.90(1) 2.09(2) 2.954(3) 162(3)
C(25)–N(40)
N(5)–C(26)
I
O(4)–H(4)⋅⋅⋅N(4) 0.82
O(1)–H(1)⋅⋅⋅N(1) 0.82
1.86
1.88
2.579(4) 145
2.598(4) 145
V(1)–O(1)
V(1)–N(1)
V(1)–O(5)
C(8)–N(1)
N(2)–C(9)
1.8520(19) V(1)–O(2)
2.079(2) V(1)–O(4)
1.8604(17) V(1)–O(6)
1.9315(19)
2.2440(19)
1.5875(19)
1.390(3)
I
O(7)–H(72)⋅⋅⋅O(4) 0.85(1) 2.05(2) 2.866(3) 163(3)
O(7)–H(71)⋅⋅⋅O(3)ii 0.85(1) 2.07(2) 2.884(3) 161(3)
1.292(3)
1.299(3)
N(1)–N(2)
C(9)–O(2)
1.316(3)
N(4)–H(4)⋅⋅⋅O(7)
0.90(1) 1.89(2) 2.775(3) 167(3)
Angle
ω
, deg
Angle
ω
, deg
i
ii
* Symmetry codes:
x, 1 –
y, –1/2 +
z;
–1 +
x, 1 +
y,
z.
H2L
C(8)N(1)N(2) 118.9(3)
N(2)C(9)O(2) 120.7(3)
N(4)N(5)C(26) 117.4(2)
N(1)N(2)C(9) 118.1(3)
C(25)N(4)N(5) 118.6(3)
N(5)C(26)O(5) 119.2(3)
dination [16–18]. In the benzohydrazone ligand of
complex , the dihedral angle between the two benꢀ
zene rings is 7.3(3)
I
°
.
The coordination of H2L to the V atom can be
reflected by the changes of the corresponding bond
lengths and angles (Table 2). The bond lengths of
I
O(6)V(1)O(1)
99.61(10) O(6)V(1)O(5) 96.07(9)
C(8)=N(1) and N(1)–N(2) in complex
longer than those observed in H2L. However, the disꢀ
tance between atoms C(9) and N(2) in complex is
I are much
O(1)V(1)O(5) 107.15(8) O(6)V(1)O(2) 101.65(10)
O(1)V(1)O(2) 151.81(9) O(5)V(1)O(2) 88.81(8)
I
much shorter than those in H2L, and the distance
between atoms C(9) and O(2) in the complex is much
longer than those in H2L, indicating the enolisation of
the N(2)–C(9)–O(2) group.
O(6)V(1)N(1)
98.15(9) O(1)V(1)N(1) 84.10(8)
O(5)V(1)N(1) 160.11(8) O(2)V(1)N(1) 74.77(8)
O(6)V(1)O(4) 170.67(9) O(1)V(1)O(4) 81.34(8)
In the crystal structure of H2L, benzohydrazone
O(5)V(1)O(4)
N(1)V(1)O(4)
74.86(7) O(2)V(1)O(4) 80.67(7)
91.17(7) C(8)N(1)N(2) 115.9(2)
molecules are linked through intermolecular N–H⋅⋅⋅
hydrogen bonds, forming chains running along the
axis (Fig. 3). In the crystal structure of the oxovanaꢀ
dium complex, the complex molecules are linked by
water molecules through intermolecular O–H⋅⋅⋅
hydrogen bonds, forming chains running along the
O
z
N(1)N(2)C(9) 108.9(2)
N(2)C(9)O(2) 121.2(2)
O
y
axis (Fig. 4).
nation are occupied by the O(4) atom of the benzohyꢀ
droxamic acid ligand and one oxo O(6) atom. The disꢀ
placement of the V atom from the equatorial plane
towards the axial oxo group is 0.289(1) Å. The cis bond
The catalytic oxidation test of complex
I on the
oxidation of sulfide under homogeneous conditions in
solution using methyl phenyl sulfide as a substrate is
the following:
angles are in the range 74.8(1)
trans bond angles are in the range 151.8(1)
170.7(1) , indicating the octahedral coordination is
°
–107.2(1)
°
, and the
°
–
O
°
S
S
much distorted. The V–O and V–N bond lengths in
the complex are similar to those observed in other simꢀ
ilar oxovanadium(V) complexes with octahedral coorꢀ
Complex
H O /TMB
2
2
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SYNTHESIS AND XꢀRAY CRYSTAL STRUCTURES
889
O(3)
C(6)
C(17)
C(16)
C(14)
C(8)
C(15)
C(1)
C(7)
N(3)
C(5)
C(10)
N(2)
C(13)
N(1)
C(2)
C(4)
C(9)
O(2)
C(12)
C(11)
C(3)
C(24)
O(1)
C(33)
C(22) C(23)
C(31)
C(32)
N(6)
O(6)
C(25)
C(18)
C(27)
C(30)
C(29)
C(21)
N(5)
C(34)
C(20)
C(19)
O(4)
N(4)
C(26)
O(5)
C(28)
Fig. 1. Molecular structure with atomic numbering for H L. Hydrogen atoms which not related to hydrogen bonding (dashed
2
lines) are omitted for clarity.
C(7)
C(16)
C(14)
C(13)
C(15)
N(3)
C(17)
N(2)
C(6)
C(2)
C(8)
C(5)
C(3)
C(10)
C(9)
O(3)
C(4)
C(12)
C(1)
O(6)
N(1)
C(11)
O(2)
V(1)
O(1)
O(4)
C(24)
O(5)
N(4)
C(19)
C(20)
C(18)
C(21)
C(23)
C(22)
O(7)
Fig. 2. Molecular structure with atomic numbering for complex I.
As oxidant hydrogen peroxide was used in a slight version of a total amount of sulfide was complete.
Under the given conditions no over oxidation to the
sulfone could be detected. It can be seen that the comꢀ
plex has effective catalytic property for the sulfoxidaꢀ
tion.
excess of 1.25 equivalents based on the sulfide subꢀ
strate. Reactions were run with 1 mol % of catalyst
based on the substrate at a temperature of 10 C. NMR
°
techniques have been used to monitor the formation of
the sulfoxides with 1,3,5ꢀtrimethoxybenzene as interꢀ
nal standard to determine the yields. The reaction was
started by the addition of hydrogen peroxide. A conꢀ
trol reaction under the same condition without any
complex present leads to less than 1% sulfide converꢀ
sion within 4 h. In the presence of the complex conꢀ
version of 85% of sulfide to sulfoxide within 60 min
Thus, in the present work, a new benzohydrazone
compound N'ꢀ(2ꢀhydroxyꢀ5ꢀmethoxybenzylidene)ꢀ
4ꢀdimethylaminobenzohydrazide and a new oxovanaꢀ
dium(V) complex derived from the benzohydrazone
compound and benzohydroxamic acid have been sucꢀ
cessively prepared and structurally characterized. The
benzohydrazone ligand coordinates to the V atom
reaction time were observed. After about 2 h the conꢀ through the phenolate O, imino N, and enolic O
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
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890
WANG et al.
atoms. The complex is an effective catalyst for the sulꢀ
foxidation reaction of sulfide to sulfoxide.
x
ACKNOWLEDGMENTS
The authors would like to acknowledge the support
from Department of Yunnan Province Education for
the fund of Science Research (grant no. ZD2010003).
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Fig. 4. Molecular packing diagram of complex
I, viewed along
the axis. Hydrogen bonds are shown as dashed lines.
x
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 39
No. 12
2013