680
Transition Met Chem (2011) 36:679–684
t-Bu
Fig. 1 Synthesis of NiL1
c
d
f
a
t-Bu
OH
a
EtOH
t-Bu
O
O
e
NiCl2.6H2O
+
HO
O
+
t-Bu
Ni
4
N
1
b
4
N
1
b
N
NH2
N
2
2
N
S
NiL1
L
S
t-Bu
Fig. 2 Synthesis of NiL2
c
d
a
t-Bu
a
EtOH
e
t-Bu
O
O
NiCl2.6H2O
+
HO
+
t-Bu
OH
f
Ni
4
1
b
4
N
N
S
1
O
h
b
g
N
NH2
N
2
2
N
NiL2
L
S
Synthesis of 3,5-di-tert-butylsalicylaldehyde-S-
methylisothiosemicarbazone (L)
stirred for 24 h at room temperature. A mixture of L
(0.321 g, 1 mmol) and salicylaldehyde (0.122 g, 1 mmol)
in ethanol (30 mL) was added. After 24 h, the dark red
precipitate was filtered off, washed with ethanol and
diethyl ether and then dried in vacuum. Dark red yield,
0.289 g, 60%, m.p, 260–262 °C, Anal. Calc. for
(C24H29N3NiO2S) (482.26 g/mol): C, 59.77; H, 6.06; N,
8.71; S, 6.65, Found: C, 59.80; H, 6.07; N, 8.75; S, 6.45,
1HNMR (DMSO-d6, 25 °C, ppm): 8.03,(s, 1H, HC=N1),
7.84 (s, 1H, HC=N4), 7.40 (s, 1H, a), 7.03 (s, 1H, b),
7.35–7.24 (m, 3H, c, d, f), 6.62, 6.58 (m, 1H, e), 2.61 (s,
3H, S=CH3), 1.30 (s, 18H, t-Bu), 13CNMR (DMSO-d6,
25 °C): 169.8, 163.48, 161.0 ppm (C=N2, N1, N4), 156.2,
154.6, 140.6, 136.9, 136.5, 134.0, 129.8, 125.7, 123.3,
119.5, 117.0, 116.5 ppm (phenyl), 35.6, 31.2, 29.4 ppm,
(t–Bu), 15.18 ppm (S–CH3), FTIR (KBr, cm-1): m(C=N1)
1,615, m(N2=C) 1,582, m(N4=C) 1,593, m(C–H) 2,953,
2,902, 2,864 cm-1. UV–VIS (CHCl3): 247, 252 nm (p–
p*), 298, 330 nm, (n–p*), 404, 424 nm (MLCT), 498,
590 nm (d–d).
The S-methylisothiosemicarbazone of 3,5-di-tert-butylsa-
licylaldehyde was prepared with a small modification of
the general method [19].
Thus, mixing thiosemicarbazide (0.91 g, 0.01 mol) and
iodomethane (0.76 mL, 0.012 mol) were mixed in ethanol
(40 mL). The mixture was refluxed water bath for 2–3 h.
A solution of 3,5-di-tert-butylsalicylaldehyde (2.34 g,
0.01 mol) in ethanol (10 mL) was then added. The reaction
mixture was refluxed for a further 4 h, and the clear solution
was cooled to room temperature. An aqueous solution of 5%
NaHCO3 was added to the reaction mixture for neutraliza-
tion. The mixture, containing a yellowish oily layer, was poured
into water and stirred vigorously for 3 h. The resulting cream
precipitate was filtered off, washed with water and diethyl
ether and finally dried in a vacuum desiccator.
Cream yield 2.56 g, 80%, m.p, 120–122 °C, Anal. Calc.
for (C17H27N3OS) (321.48 g/mol): C, 63.51; H, 8.47;
N, 13.07; S, 9.97, Found: C, 63.59; H, 8.45; N, 13.21; S,
9.75, 1HNMR (DMSO-d6, 25 °C, ppm): 11.65 (s, 1H, OH),
8.47,8.31 (syn/anti ratio: 1/4, s, 1H, CH=N1), 5.08 (s, 2H,
NH2), 7.34, 7.23 (syn/anti ratio:1/3, s, 1H, a), 7.09,7.05 (syn/
anti ratio:1/3s, 1H, b), 2.48, 2.45 (cis/trans ratio: 3/2, s, 3H,
S–CH3), 1.28 (s, 18H, t–Bu). 13CNMR (DMSO-d6, 25 °C):
159.6, 157.2 ppm (C=N2, N1), 141.0, 136.2, 126.4, 125.8,
117.7 ppm (phenyl), 35.0, 31.4, 29.4 ppm (t–Bu), 13.0 ppm
(S–CH3), FTIR (KBr, cm-1): mas (NH2) 3,494, ms (NH2) 3,386,
3,296, m (OH) 3,130, d (NH2) 1,641, m (C=N1) 1,612, m (N2=C)
1,582, m (C–O) 1,174, m (C–H) 2,955–2,856 cm-1. UV–VIS
(CHCl3): 242–298 nm (p–p*), 310–342 nm, (n–p*).
Synthesis of N1-3,5-di-tert-butylsalicylidene-N4-2-
hydroxy-1-naphthylidene-S-methylthiosemi-
carbazidato nickel(II) (NiL2)
The complex NiL2 was obtained in a similar manner to
NiL1. Dark red yield, 0.266 g, 50%, m.p, [340 °C, Anal.
Calc. for (C28H31N3NiO2S) (531.15 g/mol): C, 63.18; H,
5.87; N, 7.89; S, 6.02, Found: C, 63.20; H, 5.85; N, 7.92;
1
S, 5.87, HNMR (DMSO-d6, 25 °C, ppm): 8.71, (s, 1H,
HC=N1), 8.11 (s, 1H, HC=N4), 7.24 (s, 1H, a), 7.15–7.06
(m, 1H, b),7.34–7.21 (m, 1H, c),7.41–7.39 (m, 1H, d),
7.94–7.90 (m, 1H, e),7.45 (m, 1H, f), 7.53–7.49 (m, 1H, g),
7.71–7.62 (m, 1H, h), 2.72 (s, 3H, S–CH3), 1.29 (s, 18H,
t–Bu), 13CNMR (DMSO-d6, 25 °C): 156.3, 156.0 ppm
(C=N2, N1), 147.0, 142.0, 137.5, 137.0, 136.0, 136.5,
134.0, 131.3, 130.0, 129.5, 126.0, 125.0, 124.5, 124.0,
119.4, 116.0 ppm (phenyl), 35.6, 34.01, 31.29 ppm (t–Bu),
29.51 ppm (S–CH3), FTIR (KBr, cm-1): m(C=N1) 1,616,
Synthesis of N1-3,5-di-tert-butylsalicylidene-N4-
salicylidene-S-methylthiosemicarbazidato-nickel(II)
(NiL1)
NiCl2Á6H2O (0.237 g, 1 mmol) was dissolved in ethanol
(25 mL) containing orthoformic ester (1.33 g, 9 mmol) and
123