S.S. Tan et al. / Polyhedron 68 (2014) 287–294
289
Fig. 1. The structure of benzoylthiourea ligands with the atomic numbering scheme for NMR structure elucidation.
2
3
167;
m
(CH) 2978, 2940,
m
(C@O) 1683;
m
(C@S) 1230. kmax, nm (CH2-
2.3.2. Tris(1-benzoyl-(3-propyl-3-methyl)thiourea)cobalt(III) Co(L )
Dark green. Yield: 54.96%, m.p: 121.50–122.0 °C; eff = 0, dia;
Elemental Anal. Calc. for C, 56.53; H, 5.93; N, 10.99. Found: C,
3
ꢁ1
ꢁ1
Cl ) (
2
e
, L mol cm ): 279 (20100), 237 (36600).
l
ꢁ1
2
55.92; H, 5.40; N, 10.65%. FTIR (cm ),
v
(C@O) 1481,
v
(C@S)
2.2.2. 1-Benzoyl-(3-propyl-3-methyl)thiourea HL
ꢁ1
ꢁ1
1
208; kmax, nm (CH
2 2
Cl ) (e, L mol cm ): 279 (19900), 470
Yield: 55.97%. Elemental Anal. Calc. for C, 60.99; H, 6.83; N,
2
2
+
ꢁ1
(700), 613 (700). MS (m/z): 529.2 [Co(HL ) ]; 295.1 [Co(HL )] ;
1
3
1.85. Found: C, 60.69; H, 6.56; N, 12.81%. FTIR (cm ):
247; (CH) 2967, 2876, (C@O) 1669; (C@S) 1222. kmax, nm
Cl
m(NH)
2
1
05.1 [benzaldehyde]; 77.1 [benzene ring].
m
2
m
m
ꢁ1
ꢁ1
(
CH
2
) (e
, L mol cm ): 280 (9,600), 239 (20100).
2
.3.3. Tris(1-benzoyl-(3-cyclohexyl-3-methyl)thiourea)cobalt(III)
3
3
Co(L )
3
2.2.3. 1-Benzoyl-(3-cyclohexyl-3-methyl)thiourea HL
Green. Yield: 47.88%, m.p: 151.0–151.5 °C;
leff = 0, dia; Elemen-
tal Anal. Calc. for C, 61.06; H, 6.49; N, 9.49. Found: C, 60.93; H, 5.57;
Yield: 68.23%. Elemental Anal. Calc. for C, 65.18; H, 7.29; N,
ꢁ1
1
3
0.14. Found: C, 64.36; H, 7.71; N, 11.04%. FTIR (cm ):
314; (CH) 2927, 2856, (C@O) 1683; (C@S) 1226. kmax, nm
Cl
m(NH)
ꢁ
ꢁ1
1
N, 9.12%. FTIR (cm ),
v
(C@O) 1474,
v(C@S) 1168; kmax, nm (CH2-
m
2
m
m
ꢁ1
ꢁ1
ꢁ1
Cl ) (e, L mol cm ): 279 (21000), 480 (1100), 616 (900).
2
(
CH
2
) (e
, L mol cm ): 281 (13900), 240 (30100).
4
2
.3.4. Tris(1-benzoyl-(3-phenyl-3-methyl)thiourea)cobalt(III), Co(L )
3
4
2
.2.4. 1-Benzoyl-(3-methyl-3-phenyl)thiourea HL
Yield: 55.51%. Elemental Anal. Calc. for C, 66.64; H, 5.22; N,
Bright green. Yield: 46.01%, m.p: 141.3–141.7 °C; eff = 0, dia;
l
Elemental Anal. Calc. for C, 62.24; H, 4.53; N, 9.69. Found: C,
ꢁ1
1
3
Cl
0.36. Found: C, 66.42; H, 5.07; N, 11.27%. FTIR (cm ):
195; (CH) 2976, 2890, (C@O) 1694; (C@S) 1259. kmax, nm (CH2-
) (
m(NH)
ꢁ1
ꢁ1
6
k
(
1.05; H, 4.03; N, 9.86%. FTIR (cm ),
v
(C@O) 1491,
v
(C@S) 1168;
m
m
m
ꢁ
max, nm (CH
2
Cl
2
) (e
, L mol 1 cm ): 281 (13600), 475 (500), 614
ꢁ1
ꢁ1
2
e
, L mol cm ): 293 (11200), 243 (16300).
400).
5
2
.2.5. 1-Benzoyl-(3-benzyl-3-ethyl)thiourea HL
5
2
.3.5. Tris(1-benzoyl-(3-benzyl-3-ethyl)thiourea))cobalt(III) Co(L )
Dark green. Yield: 53.47%, m.p: 72.3–72.7 °C;
3
Yield: 52.27%. Elemental Anal. Calc. for C, 68.42; H, 6.08; N, 9.39.
leff = 0, dia; Ele-
ꢁ
1
Found: C, 69.28; H, 5.95; N, 9.47%. FTIR (cm ):
986, 2940, (C@O) 1688; (C@S) 1263. kmax, nm (CH
L mol cm ): 283 (6,700), 243 (11700).
m
(NH) 3170;
m
2
(CH)
) (
mental Anal. Calc. for C, 64.40; H, 5.40; N, 8.84. Found: C, 64.33;
(C@S) 1198; kmax
2 2
nm (CH Cl ) (e, L mol cm ): 279 (22700), 475 (1000), 616 (800).
2
m
m
2
Cl
e
,
ꢁ1
ꢁ1
H, 5.62; N, 8.52%. FTIR (cm ),
v
(C@O) 1478,
v
,
ꢁ1
ꢁ1
ꢁ1
2.3. Synthesis of the complexes
2.4. X-ray crystallography
The cobalt complexes were synthesized according to previously
reported literature methods [1,12] with some modifications. A
solution of cobalt(II) acetate and benzoylthiourea with a ratio of
The X-ray crystallographic data was collected with a Bruker
2
SMART CCD for HL (Mo K
a, k = 0.71073 Å) and an Oxford Diffrac-
4
tion Gemini for Co(L ) (Cu K
3
a, k = 1.54178 Å) area-detector
1
:3 in methanol was stirred at room temperature for 5 h. The sol-
diffractometers.
vent was removed under reduced pressure and the residue was
purified by chromatography on a silica gel column with DCM/n-
hexane (7:3) as the eluent. The main green fraction was separated
from the top yellowish band (benzoylthiourea ligand). Upon re-
moval of the solvent, a pure green solid cobalt(III) benzoylthiourea
complex was obtained. Scheme 1b shows the schematic reactions
for the synthesis of the benzoylthiourea ligands and their respec-
tive cobalt complexes.
3
. Results and discussion
.1. General
All ligands and complexes were analyzed on the basis of CHN
3
elemental analysis, IR and UV–Vis and NMR spectroscopy. Besides,
the magnetic property of all complexes was tested qualitatively by
recording their magnetic susceptibility measurements. In addition,
1
4
2.3.1. Tris(1-benzoyl-(3-ethyl-3-methyl)thiourea)cobalt(III), Co(L )
3
the structure of complex Co(L )
3
was determined by single crystal
Light green. Yield: 78.90%, m.p.: 176.8–177.2 °C;
l
eff = 0, dia;
X-ray diffraction. The X-ray structure confirmed that the cobalt
complexes were neutral and during the complexation reaction,
Elemental Anal. Calc. for C, 54.83; H, 5.44; N, 11.63. Found: C,
ꢁ
1
2+
3+
5
1
(
1
5.41; H, 4.60; N, 11.55%. FTIR (cm ),
v
(C@O) 1495,
v
(C@S)
Co ions were oxidized to Co species. The X-ray structure also
confirmed that the amidic proton on the benzoylthiourea ligand
was deprotonated prior to the complexation reaction. Hence, 1-
ꢁ
1
ꢁ1
173; kmax, nm (CH Cl ) (e, L mol cm ): 278 (24400), 470
300), 615 (200). MS (m/z): 501.2 [Co(HL )
05.1 [benzaldehyde]; 77.1 [benzene ring].
2 2
1
1 +
2
]; 281.1 [Co(HL )] ;
1
–5
benzoyl-(3,3-disubstituted)thiourea (HL ) behaved as bidentate