Synthesis and crystal structure of a phenolato-bridged dinuclear oxovanadium(V) complex derived from N'-[1-(2-hydroxyphenyl)ethylidene]-1H- indole-3-carbohydrazide

Article abstract of DOI:10.1080/15533174.2011.591343

A tridentate ligand, N'-[1-(2-hydroxyphenyl)ethylidene]-1H-indole-3- carbohydrazide (H₂L), reacts with vanadyl sulfate in methanol to give a centrosymmetric dinuclear complex, [VOL(OCH₃)]₂. The complex was characterized by

Full text of DOI:10.1080/15533174.2011.591343

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 41:1052–1055, 2011
Copyright ꢀ Taylor & Francis Group, LLC
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ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2011.591343
Synthesis and Crystal Structure of a Phenolato-bridged
Dinuclear Oxovanadium(V) Complex Derived from N’-[1-
(2-Hydroxyphenyl)ethylidene]-1H-indole-3-carbohydrazide
San-Jun Peng, Ju-Lan Zeng, Chao Wei, and Fang Fang
College of Chemistry and Biological Engineering, Changsha University of Science and Technology,
Changsha, Hunan, P. R. China
A tridentate ligand, N’-[1-(2-hydroxyphenyl)ethylidene]-1H-
indole-3-carbohydrazide (H2L), reacts with vanadyl sulfate
in methanol to give a centrosymmetric dinuclear complex,
[VOL(OCH3)]2. The complex was characterized by physicochemi-
cal and spectroscopic methods. The crystal of the complex is mon-
oclinic with space group P21/c, a = 8.345(3), b = 9.469(3), c =
24.087(4) Å, β = 96.290(3)◦, V = 1892.1(9) Å3, Z = 4. X-ray crystal-
lography indicates that each VV atom is in a distorted octahedral
coordination. The two V atoms are bridged by two phenolate O
atoms, with a distance of 3.540(2) Å.
H
NH
N
N
OH
O
SCH. 1. H2L.
complexes with Schiff bases have been reported,[13,14] but no
such complexes with hydrazone ligands. In this article the
novel centrosymmetric dinuclear oxovanadium(V) complex,
[VOL(OCH3)]2, derived from the hydrazone ligand N’-[1-(2-
hydroxyphenyl)ethylidene]-1H-indole-3-carbohydrazide (H2L;
Scheme 1), was prepared and characterized.
Keywords crystal structure, dinuclear complex, hydrazone, oxovana-
dium complex, synthesis
INTRODUCTION
EXPERIMENTAL
Metal complexes containing Schiff bases and hydrazone
ligands containing the C N functional groups have been
widely investigated due to their versatile structures and widely
applications.[1–4] Salicylaldehyde and its derivatives have been
extensively used in the preparation of Schiff bases and their
complexes. In most cases, the hydroxy groups in such lig-
ands readily bridge different metal atoms, forming dinuclear or
polynuclear complexes.[5–8] Most oxovanadium complexes crys-
tallize in mononuclear or methoxy-bridged dinuclear form.[9–12]
Until now only two phenolato-bridged polynuclear vanadium
Materials and Measurements
All chemicals were obtained from commercial sources and
were used as received without further purification with the ex-
ception of solvents. Infrared spectrum was recorded in KBr
pellets using a Nicolet 520 FT–IR spectrophotometer. Elemen-
tal analyses (C, H, N) were performed on a Perkin-Elmer 240C
elemental analyzer.
Synthesis of H2L
A mixture of 1-(2-hydroxyphenyl)ethanone (0.136 g,
1.0 mmol) and 1H-indole-3-carbohydrazide (0.189 g, 1.0 mmol)
in 50 mL methanol was stirred at room temperature for 1 h to
give a clear colorless solution. The solution was evaporated by
distillation and cooled to room temperature, yielding colorless
solid product, which was recrystallized from methanol. Yield:
83%. Anal.: Calcd. for C18H17N3O2: C, 70.3; H, 5.6; N, 13.7%.
Found: C, 70.1; H, 5.6; N, 13.8%.
Received 7 March 2011; accepted 14 March 2011.
This work was financially supported by the National Natural Sci-
ence Foundation of China (21003014), Hunan Provincial Natural Sci-
ence Foundation of China (10JJ6019), Hunan Provincial Science and
Technology Projects (2010FJ3167, 2010 GK3169), Open Project of
High School Key Laboratory of Hunan Province (2009LC 004), and
Hunan Provincial Key Laboratory of Materials Protection for Elec-
tric Power and Transportation (Changsha University of Science and
Technology, 2010CL07).
Address correspondence to San-Jun Peng, College of Chemistry
and Biological Engineering, Changsha University of Science and Tech-
nology, Changsha, Hunan 410114, P. R. China. E-mail: sanjunpeng@
163.com
Synthesis of the Complex
A methanol solution (10 mL) of vanadyl sulfate (81.5 mg, 0.5
mmol) was added dropwise to the mixture of H2L (153.5 mg,
0.5 mmol) in methanol (20 mL) with stirring. The mixture was
stirred at reflux for 30 min and then cooled to room temperature.
1052

PHENOLATO-BRIDGED DINUCLEAR OXOVANADIUM(V) COMPLEX
1053
TABLE 1
Crystallographic data for the complex
Formula
FW
Crystal shape/color
Crystal size, mm
Crystal system
Space group
a, Å
b, Å
C19H18N3O4V
403.30
Block/green
0.32 × 0.30 × 0.27
Monoclinic
P21/c
8.345 (3)
9.469 (3)
24.087 (4)
96.290 (3)
1892.1 (9)
4
T, K
298 (2)
0.554
0.8427
0.8649
14593
µ, mm−1 (Mo-Kα)
Tmin
Tmax
Number of measured reflections
Number of unique reflections and Rint
Number of observed reflections
Data/restraints/parameters
F(000)
4111 and 0.0343
3166
4111/1/249
832
1.032
0.0396, 0.0828
0.0596, 0.0927
c, Å
β, ◦
Goodness of fit on F2
R1, wR2 [I ≥ 2σ(I)]
R1, wR2 (all data)
V, Å3
Z
λ (MoKα), Å
0.71073
Green block-shaped crystals were formed after slow evaporation (THF); however, well-shaped single crystals were obtained only
of the solution in air for a few days. Crystals were filtered out with methanol.
and air-dried. Yield: 38%. Anal. Calcd. for C19H18N3O4V: C,
56.6; H, 4.5; N, 10.4%. Found: C, 56.8; H, 4.6; N, 10.3%.
IR Spectrum
In the infrared (IR) spectrum of the complex, the shifting
DATA COLLECTION, STRUCTURAL DETERMINATION,
AND REFINEMENT
of νC
of H2L to lower wavenumber in the complex (1605
N
cm−1) indicates the coordination of the azomethine N atom to
the V atom.[17,18] A new band appearing at 1232 cm−1 in the
complex is attributed to the νC–O(enolic) mode. The bands at 505
and 427 cm−1 can be attributed to the stretching vibrations of
the V–O and V–N coordinate bonds, respectively. The weak
band (3421 cm−1) indicative of the O–H vibration is absent in
the complex, indicating the deprotonation of the phenol group
when complexation. The spectrum of the complex exhibits a
typical band at 972 cm−1, which can be assigned to the V O
stretching.[19,20]
Crystal Structure Determination
A high-quality crystal of the complex was selected and
mounted on the top of a glass fiber. The data was collected
on a Bruker Smart 1000 CCD area diffractometer at 298(2) K.
Graphite-monochromatized MoKα radiation (λ = 0.71073 Å)
and the ω scan technique were used to collect the data sets.
Absorption corrections were applied using SADABS.[15] The
crystal structure was solved with direct methods and refined
with a full-matrix least-squares technique using the SHELXTL
package.[16] Anisotropic thermal parameters were applied to all
non-hydrogen atoms. H1 atom attached to N1 was located from
a difference Fourier map. The remaining H atoms were gener-
ated geometrically. The crystallographic data as well as details
of the data collection and refinement for the complex are listed
in Table 1. Selected bond lengths and angles are given in Table 2.
Crystallographic data for the complex has been deposited with
the Cambridge Crystallographic Data Centre (CCDC 814022).
TABLE 2
Selected bond lengths (Å) and angles (◦) for the complex
Bond lengths
V1–O1
V1–O3
V1–O2A
1.939 (2)
1.770 (2)
2.458 (2)
V1–O2
V1–O4
V1–N3
1.888 (2)
1.586 (2)
2.135 (2)
Bond angles
O4–V1–O3
O3–V1–O2
O3–V1–O1
O4–V1–N3
O2–V1–N3
O4–V1–O2A
O2–V1–O2A
N3–V1–O2A
RESULTS AND DISCUSSION
102.3 (1)
102.3 (1)
93.2 (1)
96.5 (1)
81.6 (1)
172.0 (1)
71.6 (1)
81.6 (1)
O4–V1–O2
O4–V1–O1
O2–V1–O1
O3–V1–N3
O1–V1–N3
O3–V1–O2A
O1–V1–O2A
100.4 (1)
104.1 (1)
147.4 (1)
159.7 (1)
74.6 (1)
80.9 (1)
83.0 (1)
Synthesis
The Schiff base H2L was readily prepared by the re-
action of 1-(2-hydroxyphenyl)ethanone with 1H-indole-3-
carbohydrazide in methanol. The deprotonated phenol group
of H2L has a strong tendency to bridge different metal atoms,
forming polynuclear complexes. Furthermore, the solvent used
in the synthesis is also important. We have tried to use the po-
lar solvents methanol, ethanol, acetonitrile, and tetrahydrofuran
Symmetry code for A: 2 – x, 1 – y, –z.

1054
S.-J. PENG ET AL.
FIG. 3. The two-dimensional structure of the complex, viewed down the b
axis.
a result of the five-membered chelate ring V1–N3–N2–C10–O1,
the six-membered chelate ring V1–O2–C14–C13–C11–N3, and
the four-membered chelate ring V1–O2–V1A–O2A (symmetry
code for A: 2 – x, 1 – y, – z). The greatest distortion from
the ideal octahedral coordination is observed for the coordinate
FIG. 1. The structure of the complex with 30% probability level. The atoms
labeled with the suffix A are at the symmetry position 2 – x, 1 – y, –z.
Structure Description of the Complex
The complex is a phenolato-bridged centrosymmetric dinu- bond angles. The three trans angles in the octahedral coordina-
clear oxovanadium(V) compound, as shown in Figure 1. The tion are in the range 147.4(1)–172.0(1)◦; the remaining bond
inversion center is located at the midpoint of the two V atoms, angles are in the range 71.6(1)–104.1(1)◦. The relatively short
which with a distance of 3.540(2) Å. The complex crystallizes C10–N2 and C11–N3 bond lengths of 1.295(3) and 1.301(3)
in the monoclinic crystal system with space group P21/c. The Å, respectively, and the relatively long N2–N3 bond length of
V atom is six-coordinate in a distorted octahedral geometry, in 1.409(2) Å indicate that there is conjugation along the backbone
which the equatorial plane is defined by the phenolate O, azome- of the ligand.
thine N, and enolic O atoms of L, and the methoxy O atom of
In the crystal structure of the complex, molecules are linked
methoxide; the axial positions are occupied by the oxo O atom through intermolecular N−H . . . O hydrogen bonds, forming
and the symmetry-related phenolate O atom. The V–O and V–N 2D layers along the bc direction, as shown in Figures 2 and 3,
bond lengths agree well with the corresponding values reported respectively.
in similar oxovanadium(V) complexes.[21–23] The V atom is dis-
placed 0.363(2) Å from the least-squares plane defined by the
CONCLUSIONS
four equatorial donor atoms, torward the oxo O atom. The obvi-
We have successfully synthesized the first novel cen-
ous distortion from an ideal octahedron for the V atom could be
trosymmetric dinuclear oxovanadium(V) complex with
the ligand N’-[1-(2-hydroxyphenyl)ethylidene] -1H-indole-3-
carbohydrazide. The elemental analyses, IR spectra, and single
crystal x-ray diffraction support the dinuclear structure of the
complex.
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