152
I. Sheikhshoaie et al. / Inorganica Chimica Acta 442 (2016) 151–157
In this research, the synthesis and spectral characterization of
2.4. Synthesis of triethylammonium 1,2-dicyano-2-(2-oxidoben-
zylidene)amino)vinyl)amide di-oxido vanadate(V) [NH(CH2CH3)3]
[VO2(L1)] (1)
two NNO Schiff base ligands (H2L1, H2L2) and their cis dioxido-
vanadium complexes were reported. The antimicrobial activities
of the synthesized compounds were also investigated against
Gram-positive, Gram-negative bacteria and yeast strains.
To a 5-mL propanolic solution of H2L (0.1 mmol, 0.02 g),
0.2 mmol of triethylamine (0.03 mL) was added with constant stir-
ring. After 10 min, 0.1 mmol of solid VOSO4Á5H2O (0.03 g) was
added to the mixture and the brown solution obtained was
refluxed for ca. 1 h. Reddish brown crystals were obtained by slow
evaporation of the mother liquor at room temperature for 4 days
and then were dried in a vacuum desiccator over silica gel
2. Experimental
All reagents and solvents for synthesis and analysis were com-
mercially available and purchased from Merck or Sigma and used
as received without further purifications. Elemental analyses were
Yield: 0.028 g, 70%. Molar conductance (1 Â 10À3 M, EtOH):
108
X
À1 cm2 molÀ1. Anal. Calc. for C17H22N5O3V (395.33 g molÀ1):
performed on
a Thermo Finnigan Flash Elemental Analyzer
C, 51.65; H, 5.61; N, 17.72. Found: C, 51.57; H, 5.70; N, 17.73%.
FT-IR (KBr, cmÀ1):
(NAH) 3447, (C„N) 2218–2197, (C@N)
1600, (C@C)aliphatic 1555, (C@C)aromatic 1472, (CAO) 1296,
asy(cis-VO2) 915, sym(cis VO2) 884, (VO) 539,
(VN) 497. 1H
1112EA. Melting points were measured on an Electrothermal-
9100 apparatus and uncorrected. FT-IR spectra were recorded on
a FT-IR Tensor 27 infrared spectrophotometer as KBr discs in the
range of 400–4000 cmÀ1. Molar conductance measurements were
made by means of a Metrohm 712 Conductometer in EtOH. 1H
NMR and 13C NMR spectra were recorded at 25 °C on an AVANCE
BRX 250 MHz spectrometer. Electronic spectra of the complexes
m
m
m
m
m
m
m
m
m
m
NMR (250 MHz, DMSO-d6, 25 °C, ppm): 11.25 (br, 1H, NH), 8.67
(s, 1H, ACH@N), 8.57 (s, H, NH), 7.68–6.81 (m, 4H, ArH), 3.05
(q, 6H, CH2), 1.14 (t, 9H, CH3).13C NMR (250 MHz, DMSO-d6, 25 °C,
ppm): 166.17, 152.10, 136.82, 133.35, 133.25, 122.10, 120.15,
in DMSO solutions were recorded with
spectrophotometer.
a Cary 50 UV–Vis
118.19, 115.49, 99.64, 46.20, 9.10. UV–Vis (DMSO) kmax, nm (loge,
L molÀ1 cmÀ1): 267(4.43), 383(4.21), 403(4.08), 472(3.80).
2.5. Synthesis of triethylammonium 1,2-dicyano-2-(3-methoxy-2-
oxidobenzylidene)amino) vinyl)amide di-oxido vanadate(V) [NH
(CH2CH3)3][VO2(L2)] (2)
2.1. Synthesis of the Schiff-base ligands H2L1 and H2L2
A methanolic (5 mL) solution of 1 mmol aldehyde (2-hydroxy-
benzaldehyde for (H2L1) and 3-methoxy-2-hydroxybenzaldehyde
for (H2L2) was added to 2,3-diamino-cis-2-butenedinitrile
(1 mmol, 0.11 g) in 5 mL of methanol and the mixture refluxed
for ca. 2 h while stirring constantly. The yellow precipitate which
resulted was filtered off, washed with cold methanol and dried in
desiccator over silica gel.
Triethylamine (0.2 mmol, 0.03 mL) was added dropwise to a
propanolic solution of H2L2 (0.1 mmol, 0.02 g) with constant stir-
ring. After adding VOSO4Á5H2O (0.1 mmol, 0.03 g), the color of
the solution immediately changed to red. After slow evaporation
of the solvent for 3 days, single crystals suitable for crystallography
appeared.
Yield: 0.031 g, 73%. Molar conductance (1 Â 10À3 M, EtOH):
103
X
À1 cm2 molÀ1. Anal. Calc. for C18H24N5O4V (425.36 g molÀ1):
C, 50.83; H, 5.69; N, 16.46. Found: C, 50.79; H, 5.66; N, 16.49%.
FT-IR (KBr, cmÀ1):
(NAH) 3445, (C„N) 2219, 2195 2218–2197,
(C@N) 1596, (C@C)aliphatic 1561, (C@C)aromatic 1442, (CAO)
1296, asy(cis-VO2) 912, sym(cis VO2) 884, (VO) 575, (VN) 435.
2.2. 2-Amino-3-((E)-(2-hydroxybenzylidene)amino)maleonitrile (H2L1)
m
m
m
m
m
m
Yield: 0.18 g, 85%. m.p.: 245 °C. Anal. Calc. for
(212.21 g molÀ1): C, 62.26; H, 3.80; N, 26.40. Found: C, 62.18; H,
3.71; N, 26.43%. FT-IR (KBr, cmÀ1):
asy(NH2) 3462, sy(NH2)
3341, (OH) 3185, (C„N) 2240, 2204, (C@N) 1622,
(C@C)aliphatic 1559, (C@C)aromatic 1494, (CAO) 1369, doopb(OH)
C11H8N4O
m
m
m
m
1H NMR (250 MHz, DMSO-d6, 25 °C, ppm): 11.21 (br, 1H, NH),
8.73 (s, 1H, ACH@N), 8.55 (s, 1H, NH), 7.25–6.76 (m, 3H, ArH),
3.74 (s, 3H, AOCH3), 3.01 (q, 6H, CH2), 1.13 (t, 9H, CH3).13C NMR
(250 MHz, DMSO-d6, 25 °C, ppm): 156.95, 152.11, 149.95, 136.73,
124.60, 122.06, 117.70, 115.47, 114.76, 114.17, 99.66, 55.98,
m
m
m
m
m
m
m
m
763. 1H NMR (250 MHz, DMSO-d6, 25 °C, ppm): d = 10.41 (s, 1H,
AOH), 8.55 (s, 1H, ACH@N), 8.02–6.85 (m, 4H, ArH), 7.84 (s, 2H,
ANH2). 13C NMR (250 MHz, DMSO-d6, 25 °C, ppm): 158.54,
153.64, 153.29, 133.63, 132.92, 130.78, 129.34, 126.37, 121.61,
46.20, 9.08. UV–Vis (DMSO) kmax, nm (loge
, L molÀ1 cmÀ1): 275
(4.42), 378(4.57), 391(4.44), 474(3.66).
119.88, 116.80, 114.94, 114.38. UV–Vis (DMSO) kmax, nm (loge,
2.6. Crystal structure determination
L molÀ1 cmÀ1): 262 (4.60), 380 (4.75), 398 (4.65).
Orange crystals of 1 and 2 were attached to MiTeGen loops with
a drop of heavy oil and placed in a cold nitrogen stream on the
diffractometer (Bruker D8 Venture for 1 and Bruker Smart APEX
for 2). For 1, a hemisphere of data was collected while for 2 a full
sphere was obtained, both under control of the APEX2 software
[14]. The raw intensities were converted to F2 values with SAINT
[14] which also performed a global refinement of unit cell param-
eters (in the case of 2, it was determined (CELL_NOW) [15] that the
crystal was twinned by a 180° rotation about the a axis and the
2.3. 2-Amino-3-((E)-(2-hydroxy-3-methoxybenzylidene)amino)
maleonitrile (H2L2)
Yield: 0.20 g, 82%. m.p.: 260 °C. Anal. Calc. for C12H10N4O2
(242.23 g molÀ1): C, 59.50; H, 4.16; N, 23.13. Found: C, 59.60; H,
4.07; N, 23.14%. FT-IR (KBr, cmÀ1):
m
asy(NH2) 3409,
(C„N) 2244, 2202, (C@N) 1643,
(C@C)aromatic 1469, (CAO) 1386, doopb(OH)
msy(NH2)
3325,
m
(OH) 3208,
m
m
m
(C@C)aliphatic 1601,
m
m
generation of F2 values used the multi-component version of SAINT
.
777. 1H NMR (250 MHz, DMSO-d6, 25 °C, ppm): d = 9.85 (s, 1H,
AOH), 8.57 (s, 1H, ACH@N), 7.85–6.78 (m, 3H, ArH), 7.63 (s, 2H,
NH2), 3.81 (s, 3H, AOCH3). 13C NMR (250 MHz, DMSO-d6, 25 °C,
ppm): 153.27, 148.31, 121.95, 120.60, 119.54, 115.17, 114.39,
The data were corrected for absorption and equivalent reflections
merged using SADABS [14] for 1 and TWINABS [16] for 2. The structures
were solved by a combination of Patterson and direct methods
(
(
SHELXT) [14] and refined by full-matrix, least-squares methods
SHELXL-2014) [17]. Hydrogen atoms attached to carbon were placed
56.40. UV–Vis (DMSO) kmax, nm (loge
, L molÀ1 cmÀ1): 275(4.42),
375(4.78), 397(4.64).
in calculated positions (CAH = 0.95–0.98 Å) while those attached