144
JBIC Journal of Biological Inorganic Chemistry (2021) 26:135–147
1
manganese(I), and organic solvents were purchased from
the commercial sources and used without preliminary
purifcations. Solid-state IR spectra were recorded on a
JASCO FT/IR-4100 instrument and a Nicolet 380 FT-IR
2855 (CH), 1630, 1592, 1567, 1015, 966. HNMR ([D6]
DMSO, 400.40 MHz): δ = 8.64 (s, 1H, HC=N), 7.93 (d,
3JH,H=6.17 Hz, 1H, Ph-H6), 7.47 (m, 2H, Ph-H3/H4), 7.38
(t, 3JH,H=6.27 Hz, 1H, Ph-H5), 3.95 (s, 2H, CH2) ppm. 13
C
1
spectrometer equipped with a smart iFTR accessory. H
NMR ([D6] DMSO, 100.63 MHz): δ=158.4, 133.9, 132.6,
132.1, 129.8, 128.0, 127.4, 60.4 (CH2) ppm. C16H14Cl2N2:
C 62.97, H 4.62, N 9.18; found C 63.03, H 4.52, N 9.35.
4 (R=4-Cl). White powder, yield: 16% (447 mg,
1.46 mmol). IR (ATR, cm−1): ν = 2920 (CH), 2861
(CH), 1642, 1594, 1485, 1014, 703. 1HNMR ([D6]
DMSO, 400.40 MHz): δ = 8.33 (s, 1H, HC=N), 7.72 (d,
3JH,H=8.49 Hz, 2H, Ph-H2/H6), 7.48 (d, 3JH,H=8.59 Hz, 2H,
Ph-H3/H5), 3.87 (s, 2H, CH2) ppm. 13C NMR ([D6] DMSO,
100.63 MHz): δ = 158.6, 132.9, 132.6, 127.2, 126.5, 58.4
(CH2) ppm. C16H14Cl2N2: C 62.97, H 4.62, N 9.18; found C
63.17, H 5.24, N 9.34.
and 13C{1H} NMR spectra were run on Bruker-Advance
400 (1H, 400.40 MHz; 13C(1H), 100.70 MHz) spectrom-
eter. Electrospray ionization mass spectra, were recorded
with an Advion compact mass spectrometer. Automatic
Analyzer CHNS, Vario EL III Elementar, a Vario Micro
Cube analyzer of Elementar Analysensysteme and an EA
3000 elemental analyzer from HEKtech were used to deter-
mine the micro-elemental percentages of the studied com-
plexes. UV/Vis spectra were recorded by a Specord 210 Plus
spectrophotometer.
Synthetic procedures
5 (R=2-NO2). Yellow powder, yield: 52.0% (1048 mg,
3.21 mmol). IR (ATR, cm−1): ν = 3103 (CH), 3052 (CH),
2917 (CH), 1636, 1512, 1335, 1017. 1HNMR ([D6]
DMSO, 400.40 MHz): δ = 8.58 (s, 1H, HC=N), 7.99
Synthesis of ligands (1–6)
3
4
Compounds 1–6 were synthesized according to a modifed
literature method [45, 46] via the condensation of ethylen-
ediamine with two equivalents of ortho- and para-substi-
tuted benzaldehydes, R=OCH3, Cl and NO2, in anhydrous
ethanol for 2 h. White to yellow powders formed upon the
slow evaporation of the solvent from the reaction mixtures of
1–5, which were washed with diethyl ether and dried under
vacuum. For 6, precipitation occurred during the refux and
the product was collected by fltration, washed with ethanol,
diethyl ether and then dried.
(dd, JH,H=8.05 Hz, JH,H=1.24 Hz, 1H, Ph-H6), 7.96
3 4
(dd, JH,H=7.75 Hz, JH,H=1.30 Hz, 1H, Ph-H4), 7.76
3
4
(td, JH,H=7.45 Hz, JH,H=1.05 Hz, 1H, Ph-H3), 7.68 (td,
3JH,H=8.02 Hz, JH,H=1.64 Hz, 1H, Ph-H5), 3.94 (s, 2H,
4
CH2) ppm. 13C NMR ([D6] DMSO, 100.63 MHz): δ=158.2,
148.8, 133.4, 131.2, 129.9, 129.4, 124.1, 60.6 (CH2) ppm.
C16H14N4O4: C 58.89, H 4.32, N 17.17; found C 59.31, H
4.95, N 17.39.
6 (R=4-NO2). Orange powder, yield: 35% (1218 mg,
3.73 mmol). IR (ATR, cm−1): ν = 3100 (CH), 2911 (CH),
2885 (CH), 2855 (CH), 1645, 1515, 1335, 1016. 1HNMR
([D6] DMSO, 400.40 MHz): 8.51 (s, 1H, HC=N), 8.27 (d,
3JH,H=8.97 Hz, 2H, Ph-H3/H5), 7.97 (d, 3JH,H=8.86 Hz, 2H,
Ph-H2/H6), 3.99 (s, 2H, CH2) ppm. 13C NMR ([D6] DMSO,
100.63 MHz): δ = 160.7, 148.5, 141.5, 128.8, 123.9, 60.7
(CH2) ppm. C16H14N4O4:C 58.89, H 4.32, N 17.17; found C
59.00, H 4.63, N 17.61.
1 (R=2-OCH3). Yellow powder, yield: 21% (600 mg,
2.02 mmol). IR (ATR, cm−1): ν = 2926 (CH), 2897 (CH),
2841 (CH), 1632, 1285, 1242, 1016. 1HNMR ([D6]
DMSO, 400.40 MHz): δ = 8.61 (s, 1H, HC=N), 7.79
3
4
(dd, JH,H=5.91 Hz, JH,H=1.77 Hz, 1H, Ph-H6), 7.40
3
3
(td, JH,H=7.21 Hz, JH,H=1.94 Hz, 1H, Ph-H4), 7.05 (d,
3JH,H=8.19 Hz, 1H, Ph-H3), 6.96 (t, JH,H=7.77 Hz, 1H,
3
Ph-H5), 3.84 (s, 2H, CH2), 3.78 (s, 3H, CH3) ppm. 13C
NMR ([D6] DMSO, 100.63 MHz): δ=158.3, 157.1, 132.0,
126.6, 124.0, 120.4, 111.8, 61.3 (CH3), 55.5 (CH2) ppm.
C18H20N2O2: C 72.95, H 6.80, N 9.45; found C 72.70, H
6.86, N 9.66.
Synthesis of tricarbonyl manganese(I) complexes (7–12)
Schiff-base (SB) ligands (1–6) [0.18 mmol; 53 mg (1,
2), 55 mg (3, 4) and 58.6 mg (5, 6)] and [MnBr(CO)5]
(0.18 mmol; 50 mg) were dissolved in chloroform (10 mL)
and then the reaction mixtures were heated to refux in the
dark for 3 h. The precipitates were collected by fltration,
washed with diethyl ether (3×5 mL) and then dried under
vacuum.
2 (R=4-OCH3). Yellow powder, yield: 18% (690 mg,
2.32 mmol). IR (ATR, cm−1): ν = 2919 (CH), 2842 (CH),
1639, 1602, 1508, 1281, 1248, 1017. 1HNMR ([D6]
DMSO, 400.40 MHz): δ = 8.24 (s, 1H, HC=N), 7.64 (d,
3JH,H=8.76 Hz, 2H, Ph-H2/H6), 6.96 (d, 3JH,H=8.73 Hz, 2H,
Ph-H3/H5), 3.80 (s, 2H, CH2), 3.78 (s, 3H, CH3) ppm. 13
C
7: [MnBr(CO)3(SB-2OCH3)]. Yellow powder, yield:
39% (36 mg, 0.069 mmol). IR (ATR, cm−1): ν = 2937
(CH), 2841 (CH), 2018 (vs, C≡O), 1908 (vs, C≡O), 1622,
NMR ([D6] DMSO, 100.63 MHz): δ=161.1, 161.0, 129.3,
128.9, 114.0, 61.0 (CH3), 55.2 (CH2) ppm. C18H20N2O2: C
72.95, H 6.80, N 9.45; found C 72.61, H 7.01, N 10.29.
3 (R=2-Cl). White powder, yield: 21% (808 mg,
2.65 mmol). IR (ATR, cm−1): ν = 2919 (CH), 2898 (CH),
1
1295, 1252, 1020. HNMR ([D6] DMSO, 400.40 MHz):
δ = 9.13 (s, 1H, HC=N), 9.07 (s, 1H, HC=N), 7.81 (d,
3JH,H=1.94 Hz, 1H, Ph-H6), 7.57 (m, 3H, Ph-H4/H6),
1 3