2178 Yuvaraj et al.
Asian J. Chem.
freshly prepared DMF solutions (10-3 M) at 25 °C with a
EQUIP-TRONICS model-660A instrument. The H NMR
Synthesis of the metal complexes:A solution of nickel(II)
chloride hexahydrate (0.713 g, 0.003 mol), cobalt(II) chloride
hexahydrate (0.713 g, 0.003 mol), copper(II) chloride dehydrate
(0.511 g, 0.003 mol), zinc(II) chloride (0.408 g, 0.003 mol)
and manganese(II) chloride tetrahydrate (0.593 g, 0.003 mol)
in ethanol was added to a solution of the parent ligand (IF)
(1.741 g, 0.003 mol) in ethanol to obtain corresponding metal
complexes. The resulting reaction mixture was refluxed for
8 h. The solid product was collected by filtration and washed
with 4-5 mL of hot methanol and dried in a vacuum over
anhydrous calcium chloride in a desiccator. The obtained metal
complexes were characterized by melting point, molar
conductance and spectral techniques.
[NiCl2(L)2]H2O complex (IF1): C24H18N8O6S2NiCl2;
Yield: 68 %; Colour: Brown; m.p: 278-270 °C; m.w.: 726.18;
Anal. calcd. and found (%): C; 40.70 (41.43), H; 2.56 (2.83),
N; 15.82 (15.85), S; 9.06 (9.67), Ni; 8.29.. IR (KBr, νmax, cm-1):
3456 ν(H2O), 3370 (N4-H), 3141 (N1-H), 1595 (C=N), 1527
(C1=O), 1010 (N-N), 862 (C=S), 464 (M-O), 412 (M-S). Molar
conductance: 24.67 ohm-1 cm2 mol-1. Mass spectrum (M+) at
m/z: 730.10.
1
spectra have been recorded as 400 MHz Varian-AS NMR
spectrometer in DMSO-d6 using tetramethylsilane (TMS) as
the internal standard. The thermal analysis (DTA and TGA)
were carried out on a Shimadzu DT-30 and TG-50 thermal
analyzers in the range 27-800 °C at the heating rate of 10 °C
min-1 in nitrogen atmosphere. The magnetic susceptibility
measured at the room temperature using the Gouy method
with mercuric tetrathiocyanatocobaltate(II) as the standard.
Mass spectra was recorded using the instrument Code; SC/
AD/10-014.
The chemicals furan-2-carbonyl chloride, NH4SCN and
acetone were purchased from the Sigma Aldrich, Laboratory
chemicals, Bangalore, Karnataka, India. Nickel(II) chloride
hexahydrate, cobalt(II) chloride hexahydrate, copper(II) chloride
dehydrate, anhydrous zinc(II) chloride and manganese(II)
chloride were purchased from MERCK, Sudha Traders,
Shivamogga, Karnataka, India. The metal chlorides were used
in their hydrated form. The ethanol, methanol, acetone and
dimethylformamide were used before distilled and dried by
following the reported method [11].
[CoCl2(L)2] complex (IF2): C24H18N8O6S2CoCl2; Yield:
64 %; Colour: Green; m.p: 300-302 °C; m.w.: 708.42; Anal.
calcd. and found (%): C; 40.69 (40.99), H; 2.56 (2.65), N;
15.82 (15.90), S; 9.05 (9.11) Co ; 8.32. IR (KBr, νmax, cm-1):
3445 ν(H2O), 3312 (N4-H), 3230 (N1-H), 1614 (C=N), 1579
(C1=O), 1043 (N-N), 837 (C=S), 458 (M-O), 414 (M-S); Molar
conductance: 36.51 ohm-1 cm2 mol-1. Mass spectra (M+) at m/z:
712.39.
Synthesis of (N-{[2-(pyridin-4-ylcarbonyl)hydrazinyl]-
carbonothioyl}furan-2-carboxamide) (IF): A solution of
furan-2-carbonyl chloride (2.61 g, 0.02 mol) in 20 mL dry
acetone was mixed to a solution of ammonium thiocyanate
(1.90 g, 0.025 mol) in 10 mL dry acetone in a round bottom
flask. The reaction mixture was stirred on magnetic stirrer
for 8 h at 35 °C. After the reaction completed, the white solid
of NH4Cl was removed by filtration. The filtrate furan-2-
carbonyl isothiocyanate (3.06 g, 0.02 mol) was added to the
solution of isonicotinic acid hydrazide (3.42 g, 0.025 mol) in
20 mL dry acetone with constant stirring. The mixture was
refluxed at the same temperature for 6 h. The progress of the
reaction was monitored by TLC (chloroform:methanol in the
ratio 0.9:0.1). After the reaction, the reaction product was
poured into ice cold water when the cream coloured precipitate
obtained was filtered, washed with ice cold water and recrys-
tallized from the methanol (Scheme-I). m.f. C16H13N5O5S:
Yield: 88 %; Colour: Cream; m.p.: 160-162 °C; m.w.: 290.29;
Anal. calcd. and found (%): C; 49.65 (49.75), H; 3.47 (3.62),
N; 19.30 (19.42), S; 11.05 (11.32): IR (KBr, νmax, cm-1): 3222
(N4-H), 2953 (N2-H), 2753 (N1-H), 2656 (Ar-C-H), 1667
[Cu(L)2]Cl2 complex (IF3): C24H18N8O6S2CuCl2; Yield:
68 %; Colour: Brown; m.p: 270-272 °C; m.w.: 713.03; Anal.
calcd. and found (%): C; 40.43 (40.52), H; 2.54 (2.71), N;
15.72 % (15.69), S; 8.99 (found 9.10), Cu; 8.91. IR (KBr,
νmax, cm-1): 3475 ν(H2O), 3366 (N4-H), 3178 (N1-H), 1595
(C=N), 1493 (C1=O), 1011 (N-N), 857 (C=S), 465 (M-O),
413 (M-S). Molar conductance: 145.61 ohm-1 cm2 mol-1.
[ZnCl(L)2]Cl complex (IF4): C24H18N8O6S2ZnCl2;Yield:
72 %; Colour: Orange; m.p: 309-310 °C; m.w.: 714.89; Anal.
calcd. and found (%): C; 40.32 (40.83), H; 2.54 (2.62), N;
15.67 (15.70), S; 8.97 (9.22), Zn; 9.15. IR (KBr, νmax, cm-1):
3447 ν(H2O), 3329 (N4-H), 3229 (N1-H), 1612 (C=N), 1549
1
(C1=O), 1008 (N-N), 878 (C=S), 467 (M-O), 415 (M-S); H
NMR (DMSO-d6, 400 MHz): δ ppm 12.10 (s, 2H, N4H), 11.58-
11.42 (s, 2H, N1H), 6.80-6.76 (t, 2H, 2-furan), 7.86-7.77 (s,
4H, 2-furan), 8.08-7.78 (s, 4H, 4-pyridine), 8.80-8.75 (s, 4H,
4-phyridine). Molar conductance: 90.61 ohm-1 cm2 mol-1.
[MnCl2(L)2] complex (IF5): C24H18N8O6S2MnCl2.Yield:
74 %; Colour: Light yellow; m.p: 295-297 °C; m.w.: 704.42;
Anal. calcd. and Found (%): C; 40.92 (40.99), H; 2.58 (2.79),
N; 15.91 (15.96), S; 9.10 (9.43), Mn; 7.80. IR (KBr, νmax, cm-1):
3461 ν(H2O), 3312 (N4-H), 3104 (N1-H) 1616 (C=N), 1518
1
(C6=O), 1578 (C1=O), 1009 (N-N), 849 (C=S). H NMR
(DMSO-d6, 400 MHz): δ ppm 12.09 (s, 1H, N4H), 11.58 (s,
1H, N2H), 11.41 (s,1H, N1H), 6.77 (t, 1H, 2-furan), 7.86-7.81
(s, 2H, 2-furan), 8.08-8.07 (s, 2H, 4-phyridine), 8.80-8.79 (s,
2H, 4-phyridine). 13C NMR (100 MHz, DMSO-d6): δ ppm
180.79 (C=S), 163.21 (C6=O), 157.03 (C1=O), 150.34, 148.46,
144.48, 139.28 (5C, 4-pyridine), 121.46, 118.84, 112.47 (4C,
2-furan). Mass spectrum (M+) at m/z: 290.9.
O
O
O
O
ACETONE
Reflux
ISONIAZID
C
NH SCN
NH
NH
4
NH Cl
N
+
+
4
S
O
NH
ACETONE
Cl
O
O
S
N
Scheme-I: Synthesis of IF ligand