Syntheses, characterization, and crystal structures of oxovanadium(V) complexes with similar tridentate hydrazones

Article abstract of DOI:10.1134/S1070328411070141

Reactions of bis(acetylacetonato)oxovanadium(IV) with N′-[2-hydroxy- 4-diethylaminobenzylidene)]-2-methylbenzohydrazide (H₂HMB) and N′-[5-bromo-2-hydroxy-3-methoxybenzylidene)]-2-methylbenzohydrazide (H₂BMB), respectively, produce two oxovanadium(V) species with the formulas [VO(OMe)(HMB)]₂ (I) and [VO(OMe)(HOMe)(BMB)] (II). The complexes have been characterized by elemental analysis, IR spectra, and single-crystal X-ray diffraction. The crystal of I is triclinic: space group P βar 1$, a = 8.843(1), b = 9.937(1), c = 12.327(2) A, α = 96.500(2)°, β = 110.070(2)°, γ = 104.220(2)°, V = 962.8(2) A³, Z = 1. The crystal of II is monoclinic: space group P2₁/c, a = 9.908(2), b = 19.968(3), c = 11.065(3), β = 109.362(3)°, V = 2065.3(8) A³, Z = 4. Compound I is the methoxide-bridged dimeric oxovanadium(V) complex, and II is the mononuclear oxovanadium(V) complex. Each V atom in the complexes is in an octahedral coordination.

Full text of DOI:10.1134/S1070328411070141

ISSN 1070ꢀ3284, Russian Journal of Coordination Chemistry, 2011, Vol. 37, No. 8, pp. 606–612. © Pleiades Publishing, Ltd., 2011.
Syntheses, Characterization, and Crystal Structures
of Oxovanadium(V) Complexes with Similar Tridentate Hydrazones1
C. L. Yuan
Key Laboratory for Phytochemistry of Shaanxi Province, Department of Chemistry and Chemical Engineering,
Baoji University of Arts and Sciences, Baoji, Shaanxi 721013, PR. China
Eꢀmail: chunlanyuan@163.com
Received October 13, 2010
Abstract
zylidene)]ꢀ2ꢀmethylbenzohydrazide (H2HMB) and
ylbenzohydrazide (H2BMB), respectively, produce two oxovanadium(V) species with the formulas
[VO(OMe)(HMB)]2 ( ) and [VO(OMe)(HOMe)(BMB)] (II). The complexes have been characterized by eleꢀ
mental analysis, IR spectra, and singleꢀcrystal Xꢀray diffraction. The crystal of is triclinic: space group
8.843(1), = 9.937(1), = 12.327(2) = 96.500(2) = 110.070(2) = 104.220(2)
The crystal of II is monoclinic: space group 21/ = 9.908(2), = 19.968(3), = 11.065(3),
= 2065.3(8) Å3
= 4. Compound is the methoxideꢀbridged dimeric oxovanadium(V) complex, and II is the
—
Reactions of bis(acetylacetonato)oxovanadium(IV) with
N'ꢀ[2ꢀhydroxyꢀ4ꢀdiethylaminobenꢀ
N
'ꢀ[5ꢀbromoꢀ2ꢀhydroxyꢀ3ꢀmethoxybenzylidene)]ꢀ2ꢀmethꢀ
I
I
a =
, Z = 1.
P1,
= 962.8(2) Å3
= 109.362(3) ,
b
c
Å,
α
°,
β
°,
γ
°,
V
P
c,
a
b
c
β
°
V
,
Z
I
mononuclear oxovanadium(V) complex. Each V atom in the complexes is in an octahedral coordination.
DOI: 10.1134/S1070328411070141
INTRODUCTION
zones is very important in both coordination chemistry
and medicinal chemistry. In this paper, the author reports
the synthesis, characterization, and crystal structures of two
Oxovanadium complexes, especially with biꢀ and triꢀ
dentate chelating ligands bearing pharmacological activꢀ
ity, have been extensively investigated in recent years with
respect to their remarkable efficiency as insulinꢀmimetic
compounds [1–3]. In the last few years, the Oꢀ, Nꢀ, and
Sꢀcontaining hydrazone compounds have been proved to
possess versatile biological activity [4–7]. Study on the
new oxovanadium(V) complexes, [VO(OMe)(HMB)]2 (
and [VO(OMe)(HOMe)(BMB)] (II), where HMB and
BMB are the deprotonated form of 'ꢀ[2ꢀhydroxyꢀ4ꢀ
diethylaminobenzylidene)]ꢀ2ꢀmethylbenzohydrazide
H2HMB) and 'ꢀ[5ꢀbromoꢀ2ꢀhydroxyꢀ3ꢀmethoxyꢀ
benzylidene)]ꢀ2ꢀmethylbenzohydrazide H2BMB),
I)
N
(
N
(
structures of the oxovanadium complexes with hydraꢀ respectively:
H
N
H
N
Br
N
N
O
O
Et2N
OH
(H2HMB)
OH
OMe
(H2BMB)
EXPERIMENTAL
Synthesis of H2HMB and H2BMB. The hydrazone
compounds H2HMB and H2BMB were synthesized by
the condensation of equimolar quantities of 2ꢀmethylꢀ
benzohydrazide with 4ꢀ(diethylamino)salicylaldehyde
and 5ꢀbromoꢀ3ꢀmethoxysalicylaldehyde, respectively, in
methanol, according to the literature method [8]. The
yields were 93% for H2HMB and 96% for H2BMB. IR
Materials and methods. 4ꢀ(Diethylamino)salicylalꢀ
dehyde, 5ꢀbromoꢀ3ꢀmethoxysalicylaldehyde, and 2ꢀmeꢀ
thylbenzohydrazide were purchased from Lancaster
Chemical Co. The remaining reagents and solvents were
purchased from local sources and used as received. C, H,
and N elemental analyses were determined on a Carlo
Erba MOD 1106 elemental analyzer. FTꢀIR spectra were
recorded in the range 4000–400 cm–1 on a Nicolet Avaꢀ
tarꢀ360 spectrometer using a KBr pellet.
(KBr;
, cm–1): for H2HMB – 3208 w, 1650 s, 1632 s,
ν
1588 s, 1550 m, 1521 s, 1453 w, 1418 w, 1355 s, 1303 w,
1277 m, 1245 m, 1223 w, 1197 w, 1157 w, 1136 m, 1078 w,
1068 w, 1013 w, 972 w, 916 m, 873 w, 847 w, 788 m, 737 w,
1
The article is published in the original.
606

SYNTHESES, CHARACTERIZATION, AND CRYSTAL STRUCTURES
607
719 w, 701 w, 666 w; for H2BMB – 3447 br. w, 3219 w, rier map was refined isotropically with O–H distance reꢀ
1655 s, 1604 m, 1569 m, 1541 m, 1469 s, 1441 m, 1386 w, strained to 0.85(1)
and with Uiso restrained to 0.08 Å2
Å
.
1355 m, 1318 w, 1249 s, 1155 m, 1113 w, 1097 w, 1075 w,
975 m, 896 m, 863 w, 837 w, 741 m, 694 w, 661 w.
Other hydrogen atoms were added in ideal positions and
were not refined. Crystallographic data are listed in Table 1,
and selected bond distances and angles are given in Table 2.
For H2HMB (C16H16N2O2)
Supplementary material has been deposited with
the Cambridge Crystallographic Data Centre
(no. 792715 (I) and 792716 (II); deposit@ccdc.
cam.ac.uk or http://www.ccdc.cam.ac.uk).
anal. calcd., %:
Found, %:
C, 71.62;
C, 71.45,
H, 6.01;
H, 6.13;
N, 10.44.
N, 10.63.
For H2BMB (C16H15BrN2O3)
anal. calcd., %:
Found, %:
C, 52.91;
C, 52.72,
H, 4.16;
H, 4.27;
N, 7.71.
N, 7.78.
RESULTS AND DISCUSSION
Synthesis of complex I. A methanol solution (20 ml) of
H2HMB (0.134 g, 0.5 mmol) was added to a stirred methꢀ
anol solution (20 ml) of VO(Acac)2 (0.132 g, 0.5 mmol).
The mixture was stirred for 30 min at room temperature.
The deep red solution was left to slow evaporation for a
few days, yielding dark red blockꢀshaped single crystals.
The crystals were isolated by filtration. The yield was
The reaction of VO(Acac)2 with the hydrazone comꢀ
pounds readily affords the oxovanadium(V) complexes.
The vanadium in VO(Acac)2 is in the V(IV) oxidation
state; however, it appears to be V(V) in the complexes, inꢀ
dicating that it was oxidized by oxygen during the reacꢀ
tion and crystallization procedures.
83%. IR (KBr;
, cm–1): 1607 s, 1579 s, 1521 m, 1505 s,
ν
The IR spectra of the hydrazone compounds exhibit
two absorption bands in the regions 3208–3219 and
1482 m, 1446 w, 1405 m, 1378 w, 1354 s, 1320 s, 1244 s,
1190 w, 1141 s, 1079 w, 1024 m, 971 m, 825 w, 791 w, 771 w,
728 w, 714 m, 629 w, 597 w, 565 w, 478 w.
1650–1655 cm–1 due to the
ν
(N–H) and ν(C=O)
stretches. The absence of these bands in the spectra of the
complexes is consistent with the enoliation of the amide
functionality and subsequent proton replacement by the
vanadium atom. The weak band observed at 3475 cm–1 in
the spectrum of II due to the O–H stretch of the coordiꢀ
For C40H48N6O8V2
anal. calcd., %: C, 57.01;
Found, %: C, 56.78;
H, 5.74;
H, 5.81;
N, 9.97.
N, 9.90.
nated methanol molecule is absent in the spectrum of I.
Synthesis of complex II. A methanol solution (20 ml) of
H2BMB (0.182 g, 0.5 mmol) was added to a stirred methꢀ
anol solution (20 ml) of VO(Acac)2 (0.132 g, 0.5 mmol).
The mixture was stirred for 30 min at room temperature.
The deep red solution was left to slow evaporation for a few
days, yielding dark red blockꢀshaped single crystals. The
crystals were isolated by filtration. The yield was 77%. IR
The new bands appearing in the 1244–1289 cm–1 range
are assigned to the stretching vibration of the enolic
groups. The strong bands at 1607 and 1617 cm–1 in comꢀ
plexes
C=N–N=C moieties [11]. The bands observed at 971
and 976 cm–1 in
and II, respectively, are assigned to the
I and II, respectively, are assigned to the conjugate
I
(KBr;
, cm–1): 3475 w, 1617 s, 1552 s, 1518 m, 1485 w,
ν
V=O stretches [12, 13].
1459 s, 1438 s, 1423 m, 1357 s, 1289 s, 1251 s, 1213 w,
1147 w, 1121 m, 1099 w, 1040 s, 976 s, 920 w, 882 w, 838 w,
807 m, 782 m, 738 m, 702 w, 629 s, 600 s, 512 w, 466 w,
450 w.
The molecular structure of I is shown in Fig. 1. The
complex is a methoxideꢀbridged centrosymmetric dinuꢀ
clear oxovanadium(V) complex. The V···V distance is
3.391(2) Å. The dianionic tridentate ligand HMB binds
the V atom through the phenolate O, imine N, and
deprotonated amide O atoms, forming sixꢀ and fiveꢀ
membered chelate rings. Each V atom is in a distorted
NO5 octahedral coordination with the three donor atoms
of the hydrazone ligand and one methoxide O atom, deꢀ
fining the basal plane, and with one oxo O and one symꢀ
metryꢀrelated methoxide O atom, occupying the axial
positions. The mean deviation of the four basal donor atꢀ
For C18H20BrN2O6V
anal. calcd., %:
Found, %:
C, 44.01;
C, 43.80,
H, 4.10;
H, 4.05;
N, 5.70.
N, 5.82.
XꢀRay structure determination. Diffraction intenꢀ
sities for the complexes were collected at 298(2) K on
a Bruker SMART APEXꢀII CCD diffractometer
equipped with a graphiteꢀmonochromatized Mo
K
α
oms from the leastꢀsquares plane is 0.029(3)
placement of the V atom towards the oxo group from the
plane is 0.323(2) . The distances of V=O and other coꢀ
Å. The disꢀ
radiation ( = 0.71073 Å). Absorption corrections were
λ
applied using SADABS [9]. The structures were solved by
direct methods and refined with the fullꢀmatrix leastꢀ
squares technique using the SHELXSꢀ97 and SHELXLꢀ97
programs [10]. All nonꢀhydrogen atoms were refined
with anisotropic thermal parameters. The methanol hydroꢀ
Å
ordination bonds in the complex are comparable to those
observed in other similar oxovanadium(V) complexes
[14, 15]. The molecules are stacked along the x axis with
gen atom in II found in an electronꢀdensity difference Fouꢀ no obvious short contacts (Fig. 2).
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Table 1. Crystallographic data and details of the experiment and refinement of structures I and II
Value
Parameter
I
II
Fw
842.72
491.21
Crystal shape/colour
Crystal size, mm
Crystal system
Space group
Block/red
Block/red
0.32
×
0.30
×
0.30
0.28
Monoclinic
21/
×
0.27 0.26
×
Triclinic
P1
P
c
a
, Å
, Å
8.8430(10)
9.9370(10)
12.327(2)
96.500(2)
110.070(2)
104.220(2)
962.8(2)
1
9.908(2)
19.968(3)
11.065(3)
90
b
c
, Å
, deg
, deg
, deg
α
β
109.362(3)
90
γ
V
Z
μ
, Å3
2065.3(8)
4
(Mo
K
), mm–1
0.547
2.451
α
Tmin
Tmax
0.8444
0.5470
0.8531
0.5683
Reflections/parameters
Independent reflections
4015/257
3047
4362/259
2876
F(000)
440
992
Goodness of fit on F2
1.024
1.037
R1
,
,
wR2
(
I
≥
2
σ
(
I
))
*
0.0538, 0.1129
0.0751, 0.1234
0.0481, 0.1026
0.0851, 0.1173
R1
wR2 (all data)
*
1/2
2
2
* R
=
∑
||F
| – |F
||/
∑
|
F
|, wR = [
∑
w
[(Fo2 – Fc2) /Σw(Fo2) ]
.
1
o
c
o
2
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SYNTHESES, CHARACTERIZATION, AND CRYSTAL STRUCTURES
609
Table 2. Selected bond lengths (Å) and bond angles (deg) for
I
and II*
Bond
d
, Å
Bond
d, Å
I
V(1)–O(1)
V(1)–O(3)
V(1)–N(1)
1.838(2)
1.578(2)
2.099(2)
V(1)–O(2)
V(1)–O(4)
1.9212(19)
1.8230(19)
2.353(2)
V(1)–O(4A)
II
V(1)–O(1)
V(1)–O(4)
V(1)–O(6)
1.852(2)
1.575(3)
2.334(3)
V(1)–O(2)
V(1)–O(5)
V(1)–N(1)
1.942(3)
1.776(2)
2.136(3)
Angle
ω
, deg
Angle
ω
, deg
I
O(3)V(1)O(4)
O(4)V(1)O(1)
O(4)V(1)O(2)
O(3)V(1)N(1)
O(1)V(1)N(1)
100.48(10)
102.08(9)
93.75(8)
96.69(11)
83.09(9)
172.48(9)
81.14(9)
90.50(8)
O(3)V(1)O(1)
O(3)V(1)O(2)
O(1)V(1)O(2)
O(4)V(1)N(1)
O(2)V(1)N(1)
101.86(11)
99.27(10)
150.68(9)
160.56(9)
74.42(9)
72.08(9)
O(3)V(1)O(4
A
)
O(4)V(1)O(4
A
)
O(1)V(1)O(4
A
)
O(2)V(1)O(4
A
)
80.50(8)
N(1)V(1)O(4A)
II
O(4)V(1)O(5)
O(5)V(1)O(1)
O(5)V(1)O(2)
O(4)V(1)N(1)
O(1)V(1)N(1)
O(4)V(1)O(6)
O(1)V(1)O(6)
N(1)V(1)O(6)
101.23(13)
100.58(11)
96.89(11)
92.37(13)
83.29(11)
174.79(12)
78.05(11)
82.52(11)
O(4)V(1)O(1)
O(4)V(1)O(2)
O(1)V(1)O(2)
O(5)V(1)N(1)
O(2)V(1)N(1)
O(5)V(1)O(6)
O(2)V(1)O(6)
100.44(14)
99.37(14)
150.38(11)
164.84(12)
74.09(11)
83.97(11)
80.24(11)
* Symmetry formation used to generate equivelant atoms: (
A) – x, 1 – y, – z.
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C(18)
C(19)
C(20)
V(1A)
N(3)
C(4)
O(4)
O(4A)
C(3)
C(2)
O(1)
C(16)
C(15)
C(10)
V(1)
O(3)
C(17)
O(2)
C(5)
C(1)
C(7)
C(9)
C(6)
N(1)
C(8)
C(11)
N(2)
C(14)
C(12)
C(13)
Fig. 1. Molecular structure of
I
with 30% thermal ellipsoids. Unlabelled atoms are related to the symmetry operation –x, 1 – y, –z.
x
0
z
y
Fig. 2. Molecular packing structure of
I
viewed along the x axis.
The molecular structure of II is shown in Fig. 3. The anol O atom, occupying the axial positions. The mean
methoxide group lies in the trans position to the imine N deviation of the four basal donor atoms from the leastꢀ
atom. The methanol ligand is transꢀcoordinated to the
oxo group. The dianionic tridentate ligand BMB binds
the V atom through the phenolate O, imine N, and
deprotonated amide O atoms, forming a sixꢀ and a fiveꢀ
membered chelate rings. The V atom is in a distorted
NO5 octahedral coordination with the three donor atoms
squares plane is 0.059(3)
om towards the oxo group from the plane is 0.289(2)
The distances of V=O and other coordination bonds in
the complex are comparable with those observed in and
other similar oxovanadium(V) complexes [14, 16, 17]. In
the crystal structure of the complex, the molecules are
Å. The displacement of the V atꢀ
Å.
I
of the hydrazone ligand and one methoxide O atom, deꢀ linked through intermolecular O–H···N hydrogen bonds,
fining the basal plane, and with one oxo O and one methꢀ forming 1D chains running along the z axis (Fig. 4).
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SYNTHESES, CHARACTERIZATION, AND CRYSTAL STRUCTURES
611
Br(1)
C(5)
C(13)
C(12)
C(6)
C(14)
C(9)
C(7)
N(2)
C(1)
O(4)
C(11)
N(1)
O(6)
C(4)
C(8)
C(2)
C(10)
C(3)
O(2)
O(1)
V(1)
C(15)
O(3)
C(16)
O(5)
C(17)
C(18)
Fig. 3. Molecular structure of II with 30% thermal ellipsoids.
x
0
z
y
Fig. 4. Molecular packing structure of II, viewed along the
x
axis. Intermolecular hydrogen bonds are drawn as dashed lines.
ACKNOWLEDGMENTS
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