S. Esmaielzadeh et al. / Inorganica Chimica Acta 405 (2013) 155–162
157
0
0
solvent. The NMR spectra were recorded by Bruker Avance DPX
250 MHz spectrometer using trimethylsilane as an internal stan-
dard in CDCl3 and mass spectra were obtained on Perkin Elmer R
MU-6E instrument.
(3H, s, SCH3), 2.67 (2H, t, H3 ), 2.79 (2H, t, H5 ’, J = 7.1 Hz), 3.41
0
0
0
0
(2H, t, H1 , J = 7.2 Hz), 3.48 (2H, t, H3 , J = 7.0 Hz), 5.69 (1H, s, Ha),
10.89 (1H, br, NH) and 12.40(1H, br, OH).
2.3.2. The synthesis of Ni(II) complexes
2.3. Synthesis
A novel series of mononuclear tetradentate complexes, Nic-
dXen (X = acac, acPh, acCF3), NicdacacMeen and Nicdacacpd were
synthesized as follows: To a solution of the appropriate ligand
(0.1 mmol) in 10 mL of chloroform/methanol 2:1 (V:V), was
added a solution of Ni(CH3COO)2ꢁ4H2O (0.1 mmol) in 10 mL of
methanol. The solution was stirred for 15 min and then allowed
to stand at room temperature for 24 h. After filtering, the brown
powders were recrystallized from acetonitrile/methanol 1:1
(V:V).
2.3.1. The synthesis of tetradentate ligands
The unsymmetrical NNOS donor Schiff base ligands were pre-
pared by condensation of the methyl-2-(N-20-aminoethane)
amino-1-cyclopentenedithiocarboxylate (Hcden), Methyl-2-(1-
methyl-2’-amino-ethane)amino-1-cyclopentenedithiocarboxylate
(HcdMeen) and Methyl-2-(3-aminopropyl-amino)-cyclopenten-
edithiocarboxylate (Hcdpd) were prepared by the literature
method [20–23]. (0. 3 mol) of Hcden, HcdMeen and Hcdpd (in
methanol) were added to a methanolic solution containing the
stoichiometric amount of the benzoylacetone, acetylacetone and
1,1,1-trifluoro-2,4-pentanedione. The resultant yellow powder
was recrystallized from methanol/chloroform 2:1 (V:V) (see
Scheme 1).
NiL1: {methyl-2-[N-[2-(acetonate)triflourolidynenitrilo>]ethyl}-
amiato(-1)-1-cyclopentenedithiocarboxylate nickel(II), [Ni(cdac-
CF3en)].
Yield: 75%, m.p.: 240 °C; MS Spectra: m/z = 410[M+1]+, 409[M]+,
363, 294, 279, 197, 156, 111, 83, 65; Elemental Anal. Calc. for C14-
H17N2OS2F3Ni: C, 41.10; H, 4.19; N, 6.85; S, 15.67. Found: C, 41.19;
H, 4.14; N, 6.98; S, 15.78%. 1H NMR (d, ppm, 250 MHz, CDCl3): 1.84
H2L1: Methyl-2-{N-[2-(acetone)triflourolidynenitrilo]ethyl}amino-
1-cyclopentenedithiocarboxylate, H2cdacC-F3en.
0
0
(2H, m, H4 ), 2.04 (3H, s, CH3), 2.51 (2H, t, H5 , J = 7.4 Hz), 2.54 (2H, t,
0
Yield: 73%; m.p.: 172 °C; MS Spectra: m/z = 353[M++1], 352[M+],
305, 152, 135, 97, 81, 57; Elemental Anal. Calc. for C14H19N2OS2F3:
C, 47.71; H, 5.43; N, 7.95; S, 18.19. Found: C, 47.85; H, 5.33; N,
7.94; S, 17.76%. 1H NMR (d, ppm, 250 MHz, CDCl3): 1.85 (2H, m,
H3 , J = 7.6 Hz), 2.65 (3H, s, SCH3), 3.19–3.23 (4H, s, Hen) and 5.39
(1H, s, Ha).
NiL2: {methyl-2-[N-[2-(acetonate)ethylidynenitrilo]ethyl}amina-
to(-1)-1-cyclopentenedithiocarboxylate nickel(II), [Ni(cdacacen)].
Yield: 63%, m.p.: 233 °C; MS Spectra: m/z = 356[M+1]+, 355[M]+,
309, 294, 279, 189, 111, 97, 57; Elemental Anal. Calc. C14H20N2OS2-
Ni: C, 47.35; H, 5.68; N, 7.89; S, 18.05. Found: C, 47.05; H, 5.78; N,
7.68; S, 18.23%. 1H NMR (d, ppm, 250 MHz, CDCl3): 1.77 (3H, s,
0
0
0
H4 ), 2.09 (3H, s, CH3), 2.57 (3H, s, SCH3), 2.64–2.80 (4H, m, H3 ,5 ),
3.48-3.61 (4H, m, Hen), 5.35 (1H, s, Ha), 11.23 (1H, br, NH) and
12.39 (1H, br, OH).
H2L2: Methyl-2-{N-[2-(acetone)ethylidynenitrilo]ethyl}amino-1-
cyclopentenedithiocarboxylate, H2cdacacen.
0
0
CH3), 1.85 (2H,m, H4 ), 2.03 (3H, s, CH3), 2.47 (2H, t, H5 ,
0
Yield: 75%; m.p.: 139 °C; MS Spectra: m/z = 299[M++1], 298[M+],
251, 236, 199, 152, 135, 111, 83, 75, 57; Elemental Anal. Calc. for
J = 7.5 Hz), 2.50 (2H, t, H3 , J = 7.6 Hz), 2.63 (3H, s, SCH3), 3.17–
3.74 (4H, s, Hen) and 4.89 (1H, s, Ha).
C
14H22N2OS2: C, 56.34; H, 7.43; N, 9.39; S, 21.00. Found: C,
NiL3: {methyl-2-[N-[2-(acetonate)phenylidynenitrilo]ethyl}ami-
nato(-1)-1-cyclopentenedithiocarboxylate nickel(II), [Ni(cdacPhen)].
Yield: 61%, m.p.: 223 °C; MS Spectra: m/z = 418[M+1]+, 417[M]+,
370, 333, 318, 265, 194, 111, 73, 57; Elemental Anal. Calc. C19H22-
N2OS2Ni: C, 54.70; H, 5.31; N, 6.71; S, 15.37. Found: C, 54.85; H,
5.48; N, 6.87; S, 15.12%. 1H NMR (d, ppm, 250 MHz, CDCl3): 1.84
56.31; H, 7.67; N, 9.07; S, 21.80%. 1H NMR (d, ppm, 250 MHz,
0
CDCl3): 1.83 (2H, m, H4 ), 1.89 (3H, s, CH3), 2.00 (3H, s, CH3), 2.58
0
0
(3H,s, SCH3), 2.64 (2H, t, H5 , J = 7.2 Hz), 2.78 (2H, t, H3 ,
J = 7.0 Hz), 3.48–3.55 (4H, m, Hen), 4.99 (1H, s, Ha), 10.93 (1H, br,
NH) and 12.41(1H, br, OH).
0
0
0
H2L3: Methyl-2-{N-[2-(acetone)phenylidynenitrilo]ethyl}amino-1-
cyclopentenedithiocarboxylate, H2cdacPhen.
(2H,m, H4 ), 2.08 (3H, s, CH3), 2.50 (2H, t, H5 ), 2.61 (2H, t, H3 ),
2.67 (3H, s, SCH3), 3.24–3.50 (4H, s, Hen), 5.06 (1H, s, Ha), 7.29
00
00 00
Yield: 60%; m.p.: 123 °C; MS Spectra: m/z = 361[M++1],
360[M+], 313, 199, 152, 135, 105, 77, 55; Elemental Anal. Calc.
for C19H24N2OS2: C, 63.30; H, 6.71; N, 7.77; S, 17.78. Found: C,
(1H, m, H1 Ph) and 7.61 (4H, d, H2 ,3 Ph).
NiL4: {methyl-2-{[1-methyl-2-(acetonate)ethylidynenitrilo]ethyl}-
amin-ato(-1)-1-cyclopentenedithiocarboxylate nickel(II), [Ni(cdacac-
Meen)].
63.12; H, 6.77; N, 7.77; S, 17.92%. 1H NMR (d, ppm, 250 MHz,
0
CDCl3): 1.83 (2H, m, H4 ), 2.08 (3H, s, CH3), 2.58 (3H, s, SCH3),
Yield: 61%, m.p.: 201 °C; MS Spectra: m/z = 369[M]+, 368, 279,
185, 167, 149, 131, 113, 97, 81, 57; Elemental Anal. Calc. C15H22N2-
OS2Ni: C, 48.80; H, 6.01; N, 7.59; S, 17.37. Found: C, 48.75; H, 6.06;
0
0
2.67–2.82 (4H, m, H3 ,5 ), 3.43-3.62 (4H, m, Hen), 5.69 (1H, s, Ha),
00
00 00
7.39 (1H, m, H1 Ph), 7.82 (4H, m, H2 ,3 Ph), 11.57 (1H, br, NH)
and 12.45 (1H, br, OH).
N, 7.65; S, 17.57%. 1H NMR (d, ppm, 250 MHz, CDCl3): 1.38 (3H, d,
0
H2L4: Methyl-2-{[1-methyl-2-(acetone)ethylidynenitrilo]ethyl}amino-
1-cyclopentenedithiocarboxylate, H2cdac-acMeen.
Me), 1.76 (3H, s, CH3), 1.85 (2H, m, H4 ), 1.97 (3H, s, CH3), 2.44 (2H,
0
0
m, H3 ), 2.64 (3H, s, SCH3), 2.79 (2H, t, H5 , J = 7.5 Hz), 3.28–3.37
(3H, m, Hen), and 4.85 (1H, s, Ha).
Yield: 61%; m.p.: 95 °C; MS Spectra: m/z = 313[M++1], 312[M+],
286, 257, 240, 140, 111, 83, 57; Elemental Anal. Calc. for C15H24N2-
OS2: C, 57.66; H, 7.74; N, 8.96; S: 20.52. Found: C, 57.34; H, 7.70; N,
NiL5: {methyl-2-{[3-(acetonate)ethylidynenitrilo]propyl}aminato-
(-1)-1-cyclopentenedithiocarboxylate nickel(II), [Ni(cdacacsalpd)].
Yield: 58%, m.p.: 235 °C; MS Spectra: m/z = 369[M]+, 368, 279,
185, 167, 149, 131, 113, 97, 81, 57; Elemental Anal. Calc. C15H22N2-
OS2Ni: C, 48.80; H, 6.01; N, 7.59; S, 17.37. Found: C, 49.07; H, 5.94;
N, 7.86; S, 17.58%. 1H NMR (d, ppm, 250 MHz, CDCl3): 1.86–1.92
(4H,m, H3’,4’), 1.94 (3H, s, CH3), 2.00 (3H, s, CH3), 2.38 (2H, m,
9.24; S: 20.22%. 1H NMR (d, ppm, 250 MHz, CDCl3): 1.30 (3H, d,
0
Me), 1.83 (2H, m, H4 ), 1.92 (3H, s, CH3), 1.99 (3H, s, CH3), 2.58
0
0
(3H, s, SCH3), 2.65 (2H, t, H3 , J = 7.3 Hz), 2.76 (2H, t, H5 ,
J = 7.2 Hz), 3.37–3.78 (3H, m, Hen), 4.99 (1H, s, Ha), 11.03 (1H, br,
NH) and 12.48 (1H, br, OH).
0
00
H2L5: Methyl-2-{[1-methyl-2-(acetone)ethylidynenitrilo]propyl}-
amino-1-cyclopentenedithiocarboxylate, H2cd-acacpd.
H5 ), 2.62 (3H, s, SCH3), 2.70 (2H, t, H3 , J = 7.4 Hz), 3.41–3.48 (4H,
00 00
m, H1 ,2 ) and 5.21 (1H, d, Ha).
Yield: 57%; m.p.: 96 °C; MS Spectra: m/z = 313[M++1], 312[M+],
265, 221, 166, 138, 112, 96, 69; Elemental Anal. Calc. for C15H24N2-
OS2: C, 57.66; H, 7.74; N, 8.96; S, 20.52. Found: C, 57.50; H, 7.67; N,
8.68; S, 20.83%. 1H NMR (d, ppm, 250 MHz, CDCl3): 1.86 (2H, m,
2.4. Thermodynamic studies
The formation constants, Kf, of the complexation were deter-
mined by spectrophotometric titration of the ligands with the
0
00
H4 ), 1.89 (2H, m, H2 ), 1.95 (3H, s, CH3), 2.00 (3H, s, CH3), 2.61