Inorganic Chemistry
Article
Scheme 1. Potassium Salts of the Dithiocarbamate Ligands (KL1−KL4) Used in This Work
Synthesis of Dithiocarbamate Ligands. The potassium salts of
the dithiocarbamate ligands KL1−KL4 (Scheme 1) were synthesized
by adopting the following procedure, and all ligands are characterized
by IR and NMR (1H and 13C{1H}) and UV−vis spectroscopy.
N-Ferrocenylmethyl-N-butyl Dithiocarbamate (KL1). In a typical
reaction, ferrocenecarboxaldehyde (0.214 g, 1 mmol) and n-
butylamine (0.073 g, 1 mmol) were taken in ethanol (EtOH; 15
mL) and refluxed for about 8−10 h at 70 °C. The Schiff base was
formed, reduced by using NaBH4 at 0 °C with an ice bath, and
allowed to stir for about 6 h. This yielded a secondary amine, which
was extracted using dichloromethane, followed by washing of the
dichloromethane layer with water and removal of the solvent. The
formed secondary amine was dissolved in 10 mL of tetrahydrofuran
(THF), and potassium hydroxide (KOH; 0.056 g, 1 mmol) was
added followed by the addition of carbon disulfide (CS2; 0.076 g, 1
mmol) under ice-cold conditions. The reaction mixture was stirred
further for 6 h, and the solvent was removed on a rotary evaporator.
The product obtained was washed three times with diethyl ether to
yield a reddish-brown solid of the N-ferrocenylmethyl-N-butyl
(νC−S). UV−vis [MeOH; λmax, nm (ε, M−1 cm−1)]: 260 (1.6 × 104),
290 (1.0 × 104), 440 (0.05 × 103).
N-4-Methoxybenzyl-N-3-methylpyridyl Dithiocarbamate (KL4).
The potassium salt of ligand KL4 was prepared by following the
procedure used in the synthesis of ligand KL1 by utilizing 4-
methoxybenzaldehyde (0.136 g, 1 mmol) and 3-picolylamine (0.108
1
g, 1 mmol). Yield: 0.30 g, 86%. H NMR (500 MHz, DMSO-d6): δ
8.45−8.40 (m, 2H, −C6H4N), 7.70−6.84 (m, 2H, −C6H4N, 4H,
−C6H4OCH3), 5.34 (s, 2H, −CH2−C6H5N), 5.28 (s, 2H, −CH2−
C6H4OCH3), 3.72 (s, 3H, −OCH3). 13C{1H} NMR (125 MHz,
DMSO-d6): δ 216.5 (−CS2), 55.1 (−CH2−C6H4N), 53.0 (−CH2−
C6H4OCH3), 51.0 (−OCH3), 158.1, 148.9, 147.7, 135.2, 134.3,
130.6, 128.9, 123.2, 113.6 (−C6H4N, −C6H4OCH3). IR (KBr, cm−1):
1427 (νCN), 1040 (νC−S). UV−vis [MeOH; λmax, nm (ε, M−1
cm−1)]: 260 (1.5 × 104), 295 (1.1 × 104).
Synthesis and Characterization of Complexes 1−4. The
homoleptic zinc(II) dithiocarbamate complexes 1−4 were prepared
by adopting the following general procedure.
[Bis{(N-ferrocenylmethyl-N-butyldithiocarbamate-S^S}zinc(II)]
(1). To a stirred 15 mL MeOH solution of the potassium salt of the
ligand KL1 (0.385 g, 1 mmol) was slowly added at room temperature
10 mL of a MeOH/water (90:10, v/v) solution of Zn(CH3COO)2·
2H2O (0.110 g, 0.5 mmol), and the reaction mixture was further
stirred for 2 h. A brown precipitate thus obtained was filtered off,
washed with a MeOH/water mixture (3 times), followed by diethyl
ether, and dried in air. The auburn needle-shaped single crystals of the
complex suitable for X-ray diffraction analysis were obtained from a
dichloromethane solution of the compound layered with MeOH
within 2 weeks. Empirical formula: [Zn(L1)2]. Yield: 0.61g, 81%. Mp:
152−156 °C. 1H NMR (500 MHz, CDCl3): δ 4.84 (s, 4H, −CH2Fc),
4.40 (s, 4H, C5H4), 4.18 (s, 4H, C5H4), 4.17 (s, 10H, C5H5), 3.70 (t, J
= 5.0 Hz, 4 H, −N−CH2−CH2−CH2−CH3), 1.68−1.29 (m, 8H,
−N−CH2−CH2−CH2−CH3), 0.92 (t, J = 7.4 Hz, 6H, −N−CH2−
CH2−CH2−CH3). 13C{1H} NMR (125 MHz, CDCl3): δ 202.7
(−CS2), 53.6 (−CH2Fc), 81.3, 70.0, 69.0, 68.8 (−Fc), 53.0, 28.7,
20.2, 13.9 (N−CH2−CH2−CH2−CH3). IR (KBr, cm−1): 1498
(νCN), 1005 (νC−S). Anal. Calcd for C32H40N2S4Fe2Zn: C, 50.70;
H, 5.32; N, 3.70. Found: C, 50.45; H, 5.30; N, 3.68. UV−vis
[CH2Cl2; λmax, nm (ε, M−1 cm−1)]: 265 (1.4 × 104), 450 (0.29 ×
103).
[Bis{(N-ferrocenylmethyl-N-ethylmorpholine)dithiocarbamate-
S^S}zinc(II)] (2). Complex 2 was prepared following the procedure
used in the synthesis of complex 1 by utilizing ligand KL2 (0.351 g, 1
mmol) and Zn(CH3COO)2·2H2O (0.110 g, 0.5 mmol). Complex 2
was obtained as a brown precipitate. Empirical formula: [Zn(L2)2].
Yield: 0.68 g, 78%. Mp: 150−155 °C. 1H NMR (500 MHz, CDCl3): δ
4.93 (s, 4H, −CH2Fc), 4.39 (s, 4H, C5H4), 4.19 (s, 4H, C5H4), 4.19
(s, 10H, C5H5), 3.85 (t, J = 5.0 Hz, 4H, −N−CH2−CH2−N−
(C4H8)−O), 2.64 (t, J = 5.0 Hz, 4H, −N−CH2−CH2−N−(C4H8)−
O), 3.71−3.69 (m, 8H, −N−CH2−CH2−N−(C2H4−C2H4)−O),
2.62−2.48 (m, 8H, −N−CH2−CH2−N−(C2H4−C2H4)−O).
13C{1H} NMR (125 MHz, CDCl3): δ 203.6 (−CS2), 55.1
1
dithiocarbamate (KL1) ligand. Yield: 0.31 g, 82%. H NMR (500
MHz, D2O): δ 5.15 (s, 2H, −CH2Fc), 4.46 (s, 2H, C5H4), 4.24 (s,
2H, C5H4), 4.29 (s, 5H, C5H5), 4.01−3.97 (m, 2H, −N−CH2−CH2−
CH2−CH3), 1.67−1.64 (m, 2H, −N−CH2−CH2−CH2−CH3),
1.33−1.29 (m, 2H, −N−CH2−CH2−CH2−CH3), 0.92 (t, J = 7.3
Hz, 3H, −N−CH2−CH2−CH2−CH3). 13C{1H} NMR (125 MHz,
D2O): δ 207.5 (−CS2), 52.9 (−CH2Fc), 83.6, 69.6, 69.0, 68.2 (−Fc),
52.6, 28.2, 19.7, 13.4 (N−CH2−CH2−CH2−CH3). IR (KBr, cm−1):
1462 (νCN), 1025 (νC−S). UV−vis [MeOH; λmax, nm (ε, M−1
cm−1)]: 260 (1.3 × 104), 290 (1.1 × 104), 437 (0.07 × 103).
N-Ferrocenylmethyl-N-ethylmorpholine Dithiocarbamate (KL2).
The potassium salt of ligand KL2 was prepared by the following
procedure used in the synthesis of ligand KL1 by utilizing
ferrocenecarboxaldehyde (0.214 g, 1 mmol) and 4-(2-aminoethyl)-
1
morpholine (0.130 g, 1 mmol). Yield: 0.35 g, 79%. H NMR (500
MHz, DMSO-d6): δ 5.12 (s, 2H, −CH2Fc), 4.40 (s, 2H, C5H4), 4.05
(s, 2H, C5H4), 4.13 (s, 5H, C5H5), 4.00 (t, J = 5.0 Hz, 2H, −N−
CH2−CH2−N−(C4H8)−O), 2.50−2.44 (m, 2H, −N−CH2−CH2−
N−(C4H8)−O), 3.54−3.40 (m, 4H, −N−CH2−CH2−N−(C2H4−
C2H4)−O), 2.44−2.35 (m, 4H, −N−CH2−CH2−N−(C2H4−
C2H4)−O). 13C{1H} NMR (125 MHz, DMSO-d6): δ 213.3
(−CS2), 54.6 (−CH2Fc), 84.9, 69.4, 67.9, 66.8, 65.9, 67.0 (−Fc),
53.4, 53.0, 50.3, 47.3 (−N−CH2−CH2−N−(C4H8)−O). IR (KBr,
cm−1): 1457 (νCN), 1036 (νC−S). UV−vis [MeOH; λmax, nm (ε, M−1
cm−1)]: 260 (1.9 × 104), 290 (1.3 × 104), 437 (0.11 × 103).
N-Ferrocenylmethyl-N-2-(diethylamino)ethylamine Dithiocarba-
mate (KL3). The potassium salt of ligand KL3 was synthesized by
adopting the procedure used in the synthesis of ligand KL1 by using
ferrocenecarboxaldehyde (0.214 g, 1 mmol) and 2-(diethylamino)-
1
ethylamine (0.116 g, 1 mmol). Yield: 0.34 g, 81%. H NMR (500
MHz DMSO-d6): δ 5.11 (s, 2H, −CH2Fc), 4.38 (s, 2H, C5H4), 4.06
(s, 2H, C5H4), 4.12 (s, 5H, C5H5), 3.93 (t, J = 5.0 Hz, 2H, −N−
CH2−CH2−N(CH2−CH3)2), 2.53 (t, J = 5.0 Hz, 2H, −N−CH2−
CH2−N(CH2−CH3)2), 2.43 (q, J = 6.9 Hz, 4H, −N−CH2−CH2−
N(CH2−CH3)2), 0.94 (t, J = 7.1 Hz, 6H, −N−CH2−CH2−N(CH2−
CH3)2). 13C{1H} NMR (125 MHz, DMSO-d6): δ 213.0 (−CS2), 50.7
(−CH2Fc), 85.0, 69.3, 68.00, 67.00 (−Fc), 48.6, 46.8, 12.00 (N−
CH2−CH2−N(CH2−CH3)2. IR (KBr, cm−1): 1449 (νCN), 1043
(−CH2Fc), 81.2, 70.0, 68.9, 68.8, 67.1 (−Fc), 54.8, 53.9, 49.9
(−N−CH2−CH2−N−(C4H8)−O). IR (KBr, cm−1): 1486 (νCN),
1005 (νC−S). Anal. Calcd for C36H46O2N4S4Fe2Zn: C, 49.58; H, 5.32;
N, 6.42. Found: C, 49.15; H, 5.35; N, 6.35. UV−vis [CH2Cl2; λmax
,
nm (ε, M−1 cm−1)]: 265 (1.4 × 104), 440 (0.22 × 103).
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Inorg. Chem. 2021, 60, 6446−6462