Hydrogen-Bond influenced synthesis and crystal structures of (4-Chloro-2-[(2-dimethylaminoethylimino)methyl] phenolato)dioxovanadium(V) and Bis(2-[(2-aminoethylimino)methyl]-4-bromophenolato) dioxovanadium(V)

Article abstract of DOI:10.1080/15533174.2012.754764

A mononuclear vanadium complex, [VO₂L^a] (1) (L ^a = 4-chloro- 2-[(2-dimethylaminoethylimino)methyl]phenolate), and a binuclear vanadium complex, [VO₂L^b]₂ (2) (L^b = 2-[(2-aminoethyl imino)methyl]-4-bromophenolate), were prepared and characterized by physical chemical methods (IR and UV-Vis spectra, elemental analysis), and single crystal X-ray diffraction. The V coordinate center in (1) is ligated by three NNO donor atoms of the Schiff base ligand L^a, and two oxo groups, generating pyramidal coordination. Each V coordinate center in (2) is ligated by three NNO donor atoms of the Schiff base ligand L^b, and three oxo groups, generating octahedral coordination. Close examination on the relationship between structures of Schiff base ligands and the final complexes, hydrogen bonds are the substantial influence factors in the self-assembly processes. Copyright Taylor and Francis Group, LLC.

Full text of DOI:10.1080/15533174.2012.754764

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Hydrogen-Bond Influenced Synthesis
and Crystal Structures of (4-Chloro-2-
[(2-dimethylaminoethylimino)methyl]
phenolato)dioxovanadium(V) and Bis(2-[(2-
aminoethylimino)methyl]-4-bromophenolato)
dioxovanadium(V)
Shi-Yong Liu a , Hua-Nan Hu a & Yu-Ping Ma b
a College of Chemistry & Pharmacy , Taizhou University , Taizhou Zhejiang , P. R. China
b Department of Chemistry , Liaoning Normal University , Dalian , P. R. China
Accepted author version posted online: 21 Feb 2013.Published online: 13 Mar 2013.
To cite this article: Shi-Yong Liu , Hua-Nan Hu & Yu-Ping Ma (2013) Hydrogen-Bond Influenced Synthesis and Crystal Structures
of (4-Chloro-2-[(2-dimethylaminoethylimino)methyl] phenolato)dioxovanadium(V) and Bis(2-[(2-aminoethylimino)methyl]-4-
bromophenolato) dioxovanadium(V), Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:6,
734-738, DOI: 10.1080/15533174.2012.754764
To link to this article: http://dx.doi.org/10.1080/15533174.2012.754764
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Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 43:734–738, 2013
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2012.754764
Hydrogen-Bond Influenced Synthesis and Crystal Structures
of (4-Chloro-2-[(2-dimethylaminoethylimino)methyl]
phenolato)dioxovanadium(V) and
Bis(2-[(2-aminoethylimino)methyl]-4-bromophenolato)
dioxovanadium(V)
Shi-Yong Liu,1 Hua-Nan Hu,1 and Yu-Ping Ma2
1College of Chemistry & Pharmacy, Taizhou University, Taizhou Zhejiang, P. R. China
2Department of Chemistry, Liaoning Normal University, Dalian, P. R. China
is a hot topic in supramolecular chemistry. To further explore
A mononuclear vanadium complex, [VO2La] (1) (La = 4-chloro-
2-[(2-dimethylaminoethylimino)methyl]phenolate), and a binu-
clear vanadium complex, [VO2Lb]2 (2) (Lb = 2-[(2-aminoethyl
imino)methyl]-4-bromophenolate), were prepared and character-
ized by physical chemical methods (IR and UV-Vis spectra, elemen-
tal analysis), and single crystal X-ray diffraction. The V coordinate
center in (1) is ligated by three NNO donor atoms of the Schiff
base ligand La, and two oxo groups, generating pyramidal coor-
dination. Each V coordinate center in (2) is ligated by three NNO
donor atoms of the Schiff base ligand Lb, and three oxo groups,
generating octahedral coordination. Close examination on the re-
lationship between structures of Schiff base ligands and the final
complexes, hydrogen bonds are the substantial influence factors in
the self-assembly processes.
the role in the self-assembly and structures of vanadium com-
plexes, a mononuclear vanadium complex, [VO2La] (1) (La = 4-
chloro-2-[(2-dimethylaminoethylimino)methyl]phenolate), and
a binuclear vanadium complex, [VO2Lb]2 (2) (Lb = 2-[(2-
aminoethylimino)methyl]-4-bromophenolate), were prepared
and discussed.
EXPERIMENTAL
Materials and Measurements
All chemicals used were commercially available with AR
grade. Elemental analyses (CHN) were performed using a
Perkin-Elmer 240 elemental analyzer (Taizhou University,
China). The IR spectra were measured with a Nicolet FT-IR 170-
SX spectrophotometer (Liaoning Normal University, China) us-
ing KBr pellets in the 4000–400 cm–1 region. UV-Vis spectra
were recorded on a Perkin-Elmer Lambda 9 instrument (Taizhou
University, China). The EPR spectra of the complexes were
measured using a Bruker EMX Micro Premium X spectrometer
(Liaoning Normal University, China).
Keywords hydrogen bonding, self-assembly, Schiff base, vanadium,
X-ray diffraction
INTRODUCTION
In the last few decades, tremendous attention has been fo-
cused on Schiff bases and their complexes in the fields of coor-
dination chemistry and bioinorganic chemistry.[1–3] Vanadium
compounds present innumerous pharmacological applications
as antitumorals, antimicrobials, and insulin-mimics.[4–6] It has
been demonstrated that the insulin effects of promoting glucose
uptake and inhibiting lipolysis can be duplicated by vanadium.
It has been known that there exists trigonal bipyramidal vana-
dium within the phosphate-metabolizing enzyme.[7,8] The de-
sign and self-assembly of complexes with predicated structures
Synthesis of the Schiff Bases HLa and HLb
The two Schiff bases were synthesized according to the
general method. A methanol solution (50 mL) of aldehyde
(1.0 mmol) was added dropwise to a stirred methanol solu-
tion (50 mL) of primary amine (1.0 mmol). The mixture was
stirred for 30 minutes and the solvent was then evaporated to
give yellow oil product with quantitative yield. Anal. Calcd. for
HLa (%) C, 58.3; H, 6.7; N, 12.4. Found (%): C, 58.2; H, 6.6; N,
12.3. Anal. Calcd. for HLb (%): C, 44.5; H, 4.6; N, 11.5. Found
(%): C, 44.3; H, 4.7; N, 11.5. Characteristic IR data (KBr, cm–1):
HLa, 1637 (νC N); HLb, 3221 (νN-H), 1632 (νC N).
Received 25 June 2012; accepted 28 November 2012.
The authors acknowledge the Natural Science Foundation of China
(21244008) and the Zhejiang Provincial Natural Science Foundation
of China (LY12B02004) for funding this work.
Address correspondence to Hua-Nan Hu, College of Chemistry &
Pharmacy, Taizhou University, Taizhou Zhejiang 317000, P. R. China.
E-mail: huhuanan2012@yahoo.cn
Synthesis of the Complex [VO2La] (1)
A methanol solution (5 mL) of VO(acac)2 (0.1 mmol,
26.5 mg) was added to a methanol solution (10 mL) of HLa
734

HYDROGEN-BOND INFLUENCED VANADIUM COMPLEXES
735
TABLE 2
(0.1 mmol, 22.6 mg) under stirring at room temperature for
30 min to give a yellow solution. The resulting solution was
allowed to stand in air for a few days. Yellowish brown needle-
like crystals suitable for X-ray single crystal diffraction were
formed at the bottom of the vessel. The isolated product was
washed with cold methanol, and dried in air. Yield: 37%. Anal.
Calcd. for C11H14ClN2O3V (%): C, 42.8; H, 4.6; N, 9.1. Found
(%): C, 42.6; H, 4.7; N, 9.0%. IR data (cm–1): 3438 (m), 3327
(w), 3125 (m), 1656 (s), 1612 (s), 1453 (m), 1398 (s), 1165
(w), 1123 (w), 1073 (w), 927 (w), 823 (w), 770 (w), 712 (w),
590 (w), 534 (w), 449 (w). UV-Vis spectra data in DMSO [nm
(ε, M–1 cm–1)]: 261 (1.27 × 104), 376 (3.1 × 103), 535 (213).
Coordinate bond lengths (Å) and bond angles (◦) for the
complexes
(1)
V1-O1
V1-O3
1.899 (2)
1.624 (2)
2.161 (2)
109.3 (1)
98.6 (1)
140.0 (1)
96.3 (1)
154.1 (1)
V1-O2
V1-N1
1.612 (2)
2.159 (2)
V1-N2
O2-V1-O3
O3-V1-O1
O3-V1-N1
O2-V1-N2
O1-V1-N2
O2-V1-O1
O2-V1-N1
O1-V1-N1
O3-V1-N2
N1-V1-N2
104.6 (1)
108.6 (1)
83.7 (1)
88.5 (1)
75.1 (1)
Synthesis of the Complex [VO2Lb]2 (2)
(2)
Needle-like single crystals of (2) was prepared and crystal-
lized according to the same method as presented for (1), with
HLa replaced by HLb (0.1 mmol, 24.3 mg). Yield: 41%. Anal.
Calcd. for C18H20Br2N4O6V2 (%): C, 33.3; H, 3.1; N, 8.6. Found
(%): C, 33.2; H, 3.1; N, 8.7. IR data (cm–1): 3443 (br, m), 3278
(w), 3198 (w), 2923 (w), 1625 (s), 1527 (w), 1453 (m), 1380
(m), 1294 (s), 1184 (w), 963 (w), 920 (w), 834 (m), 804 (w), 688
(w), 651 (w), 485 (w), 461 (w). UV-Vis spectra data in DMSO
[nm (ε, M–1 cm–1)]: 253 (1.36 × 104), 362 (3.5 × 103), 546
(171).
V1-O1
V1-O3
V1-N2
1.903 (2)
1.669 (2)
2.130 (2)
108.2 (1)
99.4 (1)
92.6 (1)
95.6 (1)
84.3 (1)
169.1 (1)
84.2 (1)
75.9 (1)
V1-O2
V1-N1
1.617 (2)
2.176 (2)
2.385 (2)
102.1 (1)
92.4 (1)
157.1 (1)
154.4 (1)
76.7 (1)
79.2 (1)
79.0 (1)
V1-O3i
O2-V1-O3
O3-V1-O1
O3-V1-N2
O2-V1-N1
O1-V1-N1
O2-V1-O3i
O1-V1-O3i
N1-V1-O3i
O2-V1-O1
O2-V1-N2
O1-V1-N2
O3-V1-N1
N2-V1-N1
O3-V1-O3i
N2-V1-O3i
TABLE 1
Crystal data for the complexes
Symmetry code: (i) 1 – x, – y, – z.
(1)
(2)
Crystal Structure Determination
Formula
C11H14ClN2O3V C18H20Br2N4O6V2
Diffraction intensities for the complexes were collected at
298(2) K using a Bruker APEX2 CCD area-detector (Liaoning
Normal University, China) with MoKα radiation (λ = 0.71073
Å). The collected data were reduced by SAINT software,[9] and
empirical absorption corrections were performed by SADABS
software.[10] The final structures of both complexes were solved
by direct methods and refined against F2 by full-matrix least-
squares methods by SHELXTL software.[11] All non-hydrogen
atoms were refined anisotropically. The amino H atoms in (2)
were located from an electronic density map and refined isotrop-
ically, with N−H and H···H distances restrained to 0.90(1) and
1.43(2) Å, respectively, and with Uiso(H) set to 0.08 Å2. All
other H atoms in the complexes were placed in calculated po-
sitions and constrained to ride on their parent atoms. The crys-
tallographic data for the complexes are summarized in Table 1.
Selected bond lengths and angles are listed in Table 2. Hydrogen
bonds are presented in Table 3.
FW
308.6
Block/yellow
Monoclinic
P21/n
6.672 (1)
11.693 (2)
16.485 (2)
98.624 (2)
1271.5 (3)
4
298 (2)
1.612
632
0.991
0.819
0.826
2744/165
2240
650.1
Block/yellow
Monoclinic
P21/c
10.301 (3)
14.667 (4)
7.370 (2)
100.442 (3)
1095.0 (5)
2
298 (2)
1.972
640
4.546
0.342
0.373
2366/145
1807
Crystal shape/color
Crystal system
Space group
a/Å
b/Å
c/Å
β/◦
V/Å3
Z
T/K
Dc/g cm—3
F(000)
μ/mm–1 (Mo-Kα)
Tmin
Tmax
Reflections/parameters
Independent reflections
Restraints
TABLE 3
0
0
Hydrogen-bond geometry (Å, ◦) for (2)
Goodness of fit on F2
R1, wR2 [I ≥ 2σ(I)]a
R1, wR2 (all data)a
1.028
1.023
0.0329, 0.0847
0.0426, 0.0913
ꢀ
0.0312, 0.0647
0.0480, 0.0715
ꢀ
D−H···A
D−H
0.90
0.90
H···A
2.31
2.08
D···A
3.024 (3)
2.896 (3)
D−H···A
N2−H2A···O1i
136
150
ꢀ
ꢀ
aR1 = ||Fo| – |Fc||/ |Fo|, wR2 = [ w(Fo2 – Fc2)2/ w(Fo2)2]1/2
,
N2−H2B···O2ii
w1 = [σ2 Fo2 + (0.0431(Fo2 + 2Fc2)/3)2 + 0.5496(Fo2 + 2Fc2)/3]–1,
w2 = [σ2 Fo2 + (0.0280(Fo2 + 2Fc2)/3)2 + 0.4812(Fo2 + 2Fc2)/3]–1.
Symmetry codes: (i) 1 – x, – y, – z; (ii): 1 – x, – y, 1 – z.

736
S.-Y. LIU ET AL.
FIG. 1. View of the molecular structure of (1) with atom labels. Displacement ellipsoids are shown at 30% probability level.
other similar dioxovanadium complexes.[12,13] The τ value for
the complex is 0.24, indicating a distorted square pyramidal
coordination.[14]
RESULTS AND DISCUSSION
Preparation of the Schiff Bases and the Complexes
The Schiff bases were prepared via the reaction of equimolar
quantities of 5-chlorosalicylaldehyde with N,N-dimethylethane-
1,2-diamine, and 5-bromosalicylaldehyde with ethane-1,2-
diamine, respectively, in methanol. It should be reminded that
the ligand HLb can only be produced by 5-bromosalicylaldehyde
added dropwise to ethane-1,2-diamine in a highly diluted
solution. If ethane-1,2-diamine was added dropwise to 5-
bromosalicylaldehyde, it can give a mixture of mono-Schiff base
HLb and bis-Schiff base N,Nꢁ-bis(5-bromosalicylidene)ethane-
1,2-diamine. Both vanadium complexes were readily prepared
by the standard procedure as widely described in literature. Both
complexes crystallized as yellowish brown needle-like single
crystals, which are stable in air at room temperature. Single
crystals of the complexes are soluble in DMSO, DMF, MeCN,
MeOH, and EtOH. The valence of the vanadium in both com-
plexes is +5 oxidation state and therefore EPR silent.
Structure Description of (2)
The molecular structure of (2) is presented in Figure 2. The
complex is a centrosymmetric dinuclear dioxovanadium(V)
compound, with the inversion center located at the midpoint of
the two V atoms, which has a distance of 3.156(1) Å. Each V
atom in the complex is six-coordinated through three bonds to
oxo groups and through bonds to Lb, generating an octahedral
geometry. The V atom lies 0.340(2) Å from the mean plane
defined by the equatorial donor atoms, in the direction of the
axial oxo group, O2. The V1-O2 and V1-O3 distances in the
complex are 1.617(2) and 1.669(2) Å, respectively, indicating
they are typical V O double bonds. The O3 atom is involved
in the bridge between V1 and V1A, strongly coordinated to O3
and weakly coordinated to O3A. The coordinate bond lengths
are comparable to those observed in (1) and other similar
dimeric oxovanadium complexes.[15–17] The distortion of the
octahedral coordination can be observed by the coordinate
bond angles, ranging from 75.9(1) to 108.2(1)◦ for the vertical
angles, and from 154.4(1) to 169.1(1)◦ for the diagonal angles.
There form two intermolecular N−H···O hydrogen bonds
between the two [VO2Lb] units in the complex. In the crystal
structure of (2), the dinuclear [VO2Lb]2 molecules are linked
through intermolecular N−H···O hydrogen bonds, to form 1D
chains running along the c-axis, as presented in Figure 3.
Structure Description of (1)
The molecular structure of (1) is presented in Figure 1. The
complex is a mononuclear dioxovanadium(V) compound. The
V atom in the complex is five-coordinated in a distorted square
pyramidal geometry. The basal plane of the coordination is com-
posed of the three donor atoms the Schiff base ligand, and an
oxo group, O3. The apical position is occupied by a second oxo
group, O2. The V atom lies 0.483(2) Å from the mean plane
defined by the basal donor atoms, in the direction of the apical
oxo group. The V1-O2 and V1-O3 distances in the complex are
1.612(2) and 1.624(2) Å, respectively, indicating they are typi-
cal V O double bonds. The distortion of the square pyramidal
coordination can be observed by the coordinate bond angles,
SUPPLEMENTARY MATERIALS
Crystallographic data in CIF format have been deposited
ranging from 96.3(1) to 109.3(1)◦ for the vertical angles, and with the Cambridge Structural Database (CCDC-858862 and
from 140.0(1) to 154.1(1)◦ for the diagonal angles. The coor- CCDC-858863 for (1) and (2), respectively). Copies of the data
dinate bond lengths in the complex are comparable to those in can be obtained free of charge, on application to CCDC, 12

HYDROGEN-BOND INFLUENCED VANADIUM COMPLEXES
737
FIG. 2. View of the molecular structure of (2) with atom labels. Displacement ellipsoids are shown at 30% probability level. Atoms labeled with suffix A and
those unlabeled are related to the symmetry operation 1 – x, – y, – z. Hydrogen bonds are drawn as dotted lines.
FIG. 3. Hydrogen bond (dotted lines) linked 1D chain structure of (2). Viewed down the b axis.

738
S.-Y. LIU ET AL.
Union Road, Cambridge, CB2 IEZ, UK, fax: +44 1223 336
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11. Sheldrick, G. M. SHELXTL V5.1, Software Reference Manual; Bruker AXS,
Inc: Madison, Wisconsin, USA, 1997.
033, e-mail: deposit@ccdc.cam.ac.uk.
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