Metal derivatives of N1-substituted thiosemicarbazones with divalent metal ions (Ni, Cu): Synthesis and structures

Article abstract of DOI:10.1016/j.poly.2009.12.013

Reactions of nickel(II) acetate with N¹-substituted pyridine-2-carbaldehyde- and salicylaldehyde thiosemicarbazones, {R¹(H)C²{double bond, long}N³-N²(H)-C¹({double bond, long}S)-N¹HR²}, have formed complexes of stoichiometry: (i) [Ni(κ³-N⁴, N³, S-pytscN¹-R²)₂] {R¹ = C₅H₅N, R² = Me, 1; Et, 2; Ph, 3} and (ii) [Ni(κ³-O, N³, S-stscN¹-R²)L] {R¹ = 2-HOC₆H₄, R², L: Me, PPh₃, 4; Et, PPh₃, 5, Me, py, 6; Ph, py, 7}. Likewise copper(II) has formed complexes of stoichiometry: [Cu(κ³-O, N³, S-stscN¹-R²)py] {R¹ = 2-HOC₆H₄, R² = Me, 8; Ph, 9}. These complexes have been characterized with the help of analytical data, spectroscopic techniques {IR, ¹H and ³¹P NMR, electronic absorption} and single crystal X-ray crystallography (1, 2, 4, 6 and 8). The complexes have either distorted octahedral (1-3) or square planar geometries (4-9). The magnetic susceptibility measurements revealed that complexes 1-3, 8 and 9 are paramagnetic.

Full text of DOI:10.1016/j.poly.2009.12.013

Polyhedron 29 (2010) 1130–1136
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Metal derivatives of N1-substituted thiosemicarbazones with divalent metal
ions (Ni, Cu): Synthesis and structures
a
a
b
Tarlok S. Lobana a, , Poonam Kumari , Geeta Hundal , Ray J. Butcher
*
a Department of Chemistry, Guru Nanak Dev University, Amritsar 143 005, India
b Department of Chemistry, Howard University, Washington DC 20059, USA
a r t i c l e i n f o
a b s t r a c t
Reactions of nickel(II) acetate with N1-substituted pyridine-2-carbaldehyde- and salicylaldehyde thio-
Article history:
semicarbazones, {R1(H)C2@N3–N2(H)–C1(@S)–N1HR2}, have formed complexes of stoichiometry: (i)
Received 3 October 2009
Accepted 2 December 2009
Available online 21 December 2009
[Ni(
j j
3-N4, N3, S-pytscN1-R2)2] {R1 = C5H5N, R2 = Me, 1; Et, 2; Ph, 3} and (ii) [Ni( 3-O, N3, S-stscN1-R2)L]
{R1 = 2-HOC6H4, R2, L: Me, PPh3, 4; Et, PPh3, 5, Me, py, 6; Ph, py, 7}. Likewise copper(II) has formed com-
plexes of stoichiometry: [Cu(j
3-O, N3, S-stscN1-R2)py] {R1 = 2-HOC6H4, R2 = Me, 8; Ph, 9}. These com-
plexes have been characterized with the help of analytical data, spectroscopic techniques {IR, 1H and
31P NMR, electronic absorption} and single crystal X-ray crystallography (1, 2, 4, 6 and 8). The complexes
have either distorted octahedral (1–3) or square planar geometries (4–9). The magnetic susceptibility
measurements revealed that complexes 1–3, 8 and 9 are paramagnetic.
Keywords:
Nickel(II)
Copper(II)
Pyridine-2-carbaldehyde-N1-methyl
thiosemicarbazone
Salicylaldehyde-N1-phenyl
thiosemicarbazone
Ó 2009 Published by Elsevier Ltd.
1. Introduction
at N1 nitrogen and C2 carbon atoms on the nature of complexes
with various thiosemicarbazones, the ligands shown in Chart 1
Thiosemicarbazones (R1R2C2@N3–N2(H)–C(@S)N1R3R4), a class
of Schiff bases, have exhibited variable donor properties, structural
diversity and catalytical, analytical and biological applications [1].
The formation of mono-, di- and poly-nuclear complexes including
cyclometallation has been observed [1–3]. Among transition met-
als, thiosemicarbazone complexes of nickel(II) and copper(II) have
been more intensively studied, as some of them have shown anti-
cancer, antifungal and antibacterial activities [4–8]. For example, a
nickel(II) complex with phenanthrenequinone thiosemicarbazone
was tested on human breast cancer cell line, T47D, rich in the pro-
gesterone receptors and has a synergistic effect on the antiprolifer-
ative activity of the cell line [9]. There are limited NiII/CuII
complexes reported with N1-substituted thiosemicarbazones
[10–14].
have been used for the preparation of complexes reported in this
paper.
2. Materials and techniques
Pyridine-2-carbaldehyde, salicylaldehyde, N4-methyl thiosem-
icarbazide, N4-ethyl thiosemicarbazide, N4-phenyl thiosemicar-
bazide, Ph3P, pyridine, Ni(OAc)2 and Cu(OAc)2 were procured
from Aldrich Sigma Ltd. The thiosemicarbazone ligands were
prepared by the condensation of a suitable thiosemicarbazides
with aldehydes in methanol by refluxing for about 7–8 h [16].
Elemental analysis for C, H and N were carried out using a ther-
moelectron FLASHEA1112 analyzer. The melting points were
determined with a Gallenkamp electrically heated apparatus.
The electronic absorption spectra were recorded using UV-
1601PC Shimadzu spectrophotometer. Magnetic susceptibility
was recorded using magnetic balance procured from Johnson
Matthey, Catalytic Systems Division Equipment. The IR spectra
were recorded using KBr pellets on a Pye–Unicam SP3-300 spec-
trophotometer. The 1H NMR spectra were recorded on a JEOL
AL300 FT spectrometer at 300 MHz in CDCl3 with TMS as the
internal reference. The 31P spectra were recorded on an AL –
Recently, the influence of the substituents at N1 nitrogen of
fuarn-2-carbaldehyde thiosemicarbazones {(C4H3O)–C(H)@N3–
N2H–C1(@S)N1HR, Hftsc; N1 = Me, Et, Ph} on the geometry of
nickel(II) complexes was investigated [15]. Here, a cis square pla-
nar complex for phenyl substituent at N1 nitrogen, and trans square
planar complexes for methyl and ethyl substituents were obtained.
In continuation, to further investigate the effect of the substituents
300 FT JEOL spectrometer operating at
a
frequency of
121.5 MHz, using CDCl3 with o-phosphoric acid as the external
reference.
* Corresponding author. Tel.: +91 183 2 257604; fax: +91 183 2 258820.
E-mail address: tarlokslobana@yahoo.co.in (T.S. Lobana).
0277-5387/$ - see front matter Ó 2009 Published by Elsevier Ltd.
doi:10.1016/j.poly.2009.12.013

T.S. Lobana et al. / Polyhedron 29 (2010) 1130–1136
1131
S
1
C
2
NH
R1
H
2
C
3
N
1
NHR2
R2 = CH3, Pyridine-2-carbaldehyde-N-methyl thiosemicarbazone (HpytscN-Me)
R2 = C2H5, Pyridine-2-carbaldehyde-N-ethyl thiosemicarbazone (HpytscN-Et)
R2 = C6H5, Pyridine-2-carbaldehyde-N-phenyl thiosemicarbazone (HpytscN-Ph)
R1 =
R1 =
,
N
OH R2 = CH3, Salicylaldehyde-N-methyl thiosemicarbazone (H2stscN-Me)
R2 = C2H5, Salicylaldehyde-N-ethyl thiosemicarbazone (H2stscN-Et)
,
R2 = C6H5, Salicylaldehyde-N-phenyl thiosemicarbazone (H2stscN-Ph)
Chart 1. Ligands used.
2.1. Synthesis of complexes
2.1.5. [Ni(j
3-O, N3, S-stscN-Et)(PPh3)] (5)
M.p. 198–200 °C, Yield, 53%. Anal. Calc. for C28H26NiN3OPS: C,
61.85; H, 4.97; N, 7.73. Found: C, 62.12; H, 4.67; N, 7.95%. Main
2.1.1. [Ni(
j
3-N4, N3, S-pytscN-Me)2]ÁH2O (1)
To a suspension of HpytscN-Me ligand (0.039 g, 0.200 mmol) in
acetonitrile (15 mL) was added solid Ni(OAc)2 salt (0.025 g,
0.100 mmol), and contents were refluxed for 5 h and the red com-
pound formed during refluxing was crystallized from acetonitrile
and dichloromethane (3:1: v/v). M.p. 292–294 °C, Yield: 56%. Anal.
Calc. for C16H20NiN8S2O: C, 41.45; H, 4.32; N, 24.18. Found: C,
IR peaks (KBr, cmÀ1),
m
(N–H) 3420s,
(C@N) + (C@C) 1600s, 1541s,
(C–N), 1045 m, 1026 m, 920 m,
(C–S) 841br. 1H NMR (d, CDCl3),
m
(C–H) 3078w, 3055w,
2976w, 2929w,
m
m
m
(P–C) 1097s,
m
m
d = 8.32 (d, 1H, C2H), 7.80 (m, 6H, o-H), 7.44 (m, 9H, p-H + m-H),
7.26(d, 1H, C5H), 7.07(t, 1H, C6H), 6.60 (t, 1H, C8H), 6.41 (d, 1H,
C7H), 4.71 (s, br, 1H, N1H), 3.31 (m, 2H, CH2), 1.13 (t, 3H, CH3)
41.87; H, 4.08; N, 24.40%. Main IR peaks (KBr, cmÀ1),
m
(N–H),
(C@C), 1601s,
m(C–S) 836s. Magnetic moment,
ppm. 31P NMR (CDCl3), d = À120.37 ppm.
dPPh3) = 25.29 ppm.
Dd(dcomplex–
3233s,
1514s,
m
m
(C–H), 3015w, 2928w, 2878w,
(C–N), 1099s, 1038s,
m(C@N) + m
2.1.6. [Ni(j
3-O, N3, S-stscN-Me)(py)] (6)
leff = 2.98 BM.
Complexes 2 and 3 were prepared similarly.
M.p. 192–94 °C, Yield, 69%. Anal. Calc. for C14H14NiN4OS: C,
48.69; H, 4.06; N, 16.23. Found: C, 48.52; H, 4.21; N, 16.15%. Main
IR peaks (KBr, cmÀ1),
m
(N–H) 3221s,
m
(C–H) 3084w, 3020w, 2988w,
(C–S)
2.1.2. [Ni(j
3-N4, N3, S-pytscN-Et)2] (2)
m(C@N) +
m
(C@C) 1603s, 1524s, (C–N), 1070s, 1022s, 943s, m
m
M.p. above 300 °C, Yield, 59%. Anal. Calc. for C18H22N8NiS2: C,
829s. 1H NMR (d, CDCl3), d = 8.82 (s, 1H, o-H(py)), 7.88 (s, 1H, C2H),
7.44 (t, 1H, p-H(py)), 7.31 (t, 2H, m-H(py)), 7.18 (m, 2H, C5H + C6H),
6.85(d, 1H, C8H), 6.63(t, 1H, C7H), 4.61(d, 1H, N1H), 2.90(d, 3H,
CH3).
45.64; H, 4.65; N, 23.67. Found: C, 45.59; H, 5.01; N, 23.75%. Main
IR peaks (KBr, cmÀ1),
m
(N–H) 3238s,
(C@C) 1601s, 1510s,
(C–S), 824s. Magnetic moment, eff = 3.02 BM.
m
(C–H) 3053w, 2974w, 2928w,
2868w,
923w,
m(C@N) +
m
m(C–N), 1087s, 1047s,
m
l
2.1.7. [Ni(j
3-O, N3, S- stscN-Ph)(py)] (7)
2.1.3. [Ni(j
3-N4, N3, S-pytscN-Ph)2] (3)
M.p. above 300 °C, Yield, 61%. Anal. Calc. for C26H22N8NiS2: C,
M.p. above 300 °C, Yield, 61%. Anal. Calc. for C26H22N8NiS2: C,
54.81; H, 3.86; N, 19.67. Found: C, 54.65; H, 4.08; N, 19.51%. Main
54.81; H, 3.86; N, 19.67. Found: C, 54.65; H, 4.18; N, 19.51%. Main
IR peaks (KBr, cmÀ1),
m
(N–H) 3264br, (C–H) 3053w, 3014w,
m
IR peaks (KBr, cmÀ1),
m
(N–H) 3263s,
(C@C) 1589s, 1518s, (C–N), 1128s, 1028w,
Magnetic moment, eff = 3.13 BM.
m
(C–H) 3055w, 3022w, 2888w,
2833w,
912s,
m
(C@N) +
m
(C@C) 1602s, 1544s, m(C–N), 1091s, 1022s,
m
(C@N) +
m
m
m(C–S) 894s.
m
(C–S) 839s. 1H NMR (d, CDCl3), d = 8.84 (s, br, 2H, o-
l
H(py)), 8.06 (s, 1H, C2H), 7.77 (t, 1H, p-H(py)), 7.47 (d, 2H, o-
H(Ph)), 7.24 (m, 6H, N1H + m-H(py) p-H + m-H(Ph)), 6.99(t, 1H,
C5H), 6.88(d, 1H, C8H), 6.65(t, 1H, C7H).
2.1.4. [Ni(j
3-O, N3, S-stscN-Me)(PPh3)] (4)
To a solution of H2stscN-Me (0.021 g, 0.100 mmol) in methanol
was added solid Ni(OAc)2 salt (0.025 g, 0.100 mmol) and stirred.
The rust colored precipitates formed during stirring were filtered
and allowed to dry at room temperature. The analytical data sup-
ported the formation of compound of empirical composition,
[Ni(stscN-Me)] {Anal. Calc. for C9H9NiN3OS: C, 40.65; H, 3.39; N,
15.81. Found: C, 40.84; H, 3.23; N, 15.75%}. To a suspension of
[Ni(stscN-Me)] (0.025 g, 0.094 mmol) in CH3CN was added PPh3
(0.025 g, 0.094 mmol), and contents were stirred for 1 h. The clear
solution obtained was allowed to evaporate at room temperature
which yielded red colored crystals. M.p. 180–82 °C, Yield, 57%. Ana-
l. Calc. for C27H24NiN3OPS: C, 61.34; H, 4.54; N, 7.95. Found: C,
2.1.8. [Cu(j
3-O, N3, S-stscN-Me)(py)] (8)
M.p. 244–46 °C, Yield, 62%. Anal. Calc. for C14H14N4CuOS: C,
48.01; H, 4.00; N, 16.00. Found: C, 48.30; H, 4.23; N, 15.96%. Main
IR peaks (KBr, cmÀ1),
m
(N–H) 3229s,
(C@C) 1600s, 1558s,
(C–S) 821s. Magnetic moment, eff = 1.80 BM.
m
(C–H) 3081w, 3018w, 2977w,
2883w,
m(C@N) +
m
m
(C–N), 1070s, 1028s, 912s,
m
l
2.1.9. [Cu(j
3-O, N3, S-stscN-Ph)(py)] (9)
M.p. 212–14 °C, Yield, 58%. Anal. Calc. for C25.66H31.64CuN5O3.66S:
C, 54.57; H, 5.61; N, 12.40. Found: C, 54.46; H, 5.64; N, 12.26%.
Main IR peaks (KBr, cmÀ1),
m
(N–H) 3249s,
(C@C) 1610s, 1533s,
(C–S) 849s. Magnetic moment, eff = 1.82 BM.
m
(C–H) 3045s, 2988w,
61.56; H, 4.39; N, 7.89%. Main I.R peaks (KBr, cmÀ1),
3428s, (C–H) 3070w, 3047w, 2887w, 2885w, (C@N) +
1607s, 1528s, (P–C) 1097s, (C–N), 1024s, 1001s, 916s,
m
m
m
(N–H)
(C@C)
(C–S)
2920w,
946s,
m(C@N) +
m
m(C–N) 1067s, 1022s,
m
m
m
l
m
m
829s. 1H NMR (d, CDCl3), d = 8.34 (d, 1H, C2H), 7.79 (m, 6H, o-H),
7.46 (m, 9H, p-H + m-H), 7.24 (dd, 1H, C5H), 7.06 (t, 1H, C6H),
6.59 (t, 1H, C8H), 6.41 (d, 1H, C7H), 4.74 (d, br, 1H, N1H), 2.90 (d,
2.1.10. 1H NMR spectra of ligands: H2stscN-Me
1H NMR (d, CDCl3), d = 10.95 (s, 1H, OH), 9.61 (s, 1H, N2H), 8.23
(s, 1H, C2H), 7.56 (s, br, N1H), 7.36 (dd, 1H, C5H), 7.26 (t, 1H, C6H),
6.90 (m, 2H, C7H + C8H), 3.12 (d, 3H, CH3) ppm. H2stscN-Et, 1H NMR
(d, CDCl3), d = 10.73 (s, 1H, OH), 9.68 (s, 1H, N2H), 8.18 (s, 1H, C2H),
3H, CH3) ppm. 31P NMR (CDCl3), d = À88.04 ppm.
Dd(dcomplex –
dPPh3) = 25.11 ppm.
Compounds 5–9 were prepared similarly.

1132
T.S. Lobana et al. / Polyhedron 29 (2010) 1130–1136
3
N
N4
S
Ni(OAc)2
HpytscN-R2
R2 = CH3 1, C2H5 2, C6H5 3
Ni
N3
4
N
S
3
3
S
S
N
N
H2stscN-R2
Ni
M
Ph3P
O
py
O
M(OAc)2
M = Ni, R2 = CH3 6, C6H5 7
R2 = CH3 4, C2H5 5
M = Cu, R2 = CH3 8, C6H5 9
py
Ph3P
[M(stscN-R2)]
Scheme 1. Synthesis of complexes.
7.30 (m, 2H, C5H + C6H), 7.08 (s, br, 1H, N1H), 6.91 (m, 2H,
C7H + C8H), 3.31 (m, 2H, CH2), 3.74 (m, 2H, CH2), 1.28 (t, 3H, CH3)
ppm. H2stscN-Ph, 1H NMR (d, CDCl3), d = 10.97 (s, 1H, OH), 9.61
(s, 1H, N2H), 8.95 (s, 1H, N1H), 8.27 (s, 1H, C2H), 7.59 (d, 2H, o-
H(Ph), 7.39 (m, 3H, m-H + p-H(Ph)), 7.27 (m, 2H, C5H + C6H), 6.93
(q, 2H, C7H + C8H).
of HpytscN-R2 ligand to a solution of Ni(OAc)2 in methanol yielded
complexes of stoichiometry, [Ni(
3-N4, N3, S-pytscN-R2)] {R2 = Me,
j
1; Et, 2; Ph, 3}. Similar reactions of Ni(OAc)2/Cu(OAc)2 with
H2stscN-R2 yielded insoluble compounds of stoichiometry,
[M(stscN-R2)] {M = Ni, Cu; R2 = CH3, C2H5, C6H5}, which after reac-
tions with Ph3P or py gave crystalline compounds, [M(j
3-O, N3, S-
stscN1-R2)L] {M, R2, L: Ni, Me, PPh3, 4; Ni, Et, PPh3, 5; Ni, Me, py, 6;
Ni, Ph, py, 7; Cu, Me, py, 8; Cu, Ph, py, 9}. Complexes with 2-hydro-
xy phenyl substituent at C2 carbon of thiosemicarbazones were
insoluble and addition of triphenylphosphine or pyridine solubi-
lized them and hence gave good crystals for study (4–9). The com-
plexes with pyridyl substituent at C2 carbon were soluble in
organic solvents and triphenylphosphine or pyridine did not
change the stoichiometry or geometry.
3. X-ray crystallography
The single crystals of compounds were mounted on Bruker AXS
SMART APEX CCD (1, 6, 8), Oxford Diffraction Gemini (2), and Sie-
mens P4 X-ray (4) diffractometers, each equipped with a graphite
monochromator and Mo K
Supplementary data).
a radiation (k = 0.71073 Å) [17–20] (see
In all these complexes, the thiosemicarbazone ligands are coor-
dinating via X, N3, S (X = N4, 1–3; O, 4–9) donor atoms (X-ray crys-
tallography, vide infra). In complexes 1–3, HpytscN-R2 ligands are
uninegative (deprotonation of –N2H) and in complexes 4–9, the
H2stscN-R2 ligands are dinegative (deprotonation of –N2H and –
4. Results and discussion
4.1. Synthesis, magnetism and IR spectra
OH). The room temperature magnetic moments,
3.02 (2), 3.13 (3) BM support high spin nickel(II) octahedral
leff = 2.98 (1),
Scheme 1 depicts the formation of complexes 1–9 with a series
of the thiosemicarbazone ligands. The addition of two equivalents
Table 1
Crystallographic data for complexes 1, 2, 4, 6 and 8.
1
2
4
6
8
Empirical formula
Formula weight
T (K)
C16H19N8NiOS2
463.23
100(2)
C18H22N8NiS2
473.27
200(2)
C27H24N3NiOPS
528.23
295(2)
C14H14N4NiOS
345.06
100(2)
C14H14CuN4OS
349.91
100(2)
Crystal system
Space group
Unit cell dimensions (mm3)
a (Å)
b (Å)
c (Å)
monoclinic
P21/n
monoclinic
P121/n1
triclinic
P21/n
triclinic
P1
triclinic
P1
ꢀ
ꢀ
0.5 Â 0.26 Â 0.11
13.3482(8)
10.7234(6)
14.5093(9)
90
108.0920(10)
90
1974.2(2)
4
0.53 Â 0.47 Â 0.25
9.3015(4)
13.3920(6)
17.0488(8)
90
94.199(4)
90
2117.99(16)
4
0.20 Â 0.20 Â 0.10
0.51 Â 0.26 Â 0.11
5.4014(3)
8.4760(4)
15.3007(8)
99.8020(10)
93.1620(10)
92.3570(10)
688.31(6)
2
0.27 Â 0.10 Â 0.04
5.1251(19)
9.099(3)
15.117(6)
97.837(5)
92.680(5)
92.932(6)
696.4(4)
9.372(1)
10.267(2)
14.680(2)
71.99(1)
78.95(1)
67.74(1)
1238.8(3)
2
1.416
a
(°)
b (°)
c
(°)
V (Å3)
Z
2
Dcalc (mg mÀ3
)
1.555
1.220
1.484
1.135
1.665
1.564
1.669
1.721
l
(mmÀ1
)
0.957
Reflections collected
Unique reflections
Reflections with [I > 2
R indices (all data)
17837
4896 [R(int) = 0.0223]
4633
R1 = 0.0285,
wR2 = 0.0696
R1 = 0.0269,
wR2 = 0.0682
18515
6929 [R(int) = 0.0657]
3923
R1 = 0.1343,
wR2 = 0.1562
R1 = 0.0772,
wR2 = 0.1562
4855
7140
6894
4533 [R(int) = 0.0305]
2593
R1 = 0.1327,
wR2 = 0.2654
R1 = 0.0815,
wR2 = 0.2254
3399 [R(int) = 0.0155]
3164
R1 = 0.0311,
wR2 = 0.0752
R1 = 0.0288,
wR2 = 0.0733
3395 [R(int) = 0.0369]
2815
R1 = 0.0658,
wR2 = 0.1458
R1 = 0.0539,
wR2 = 0.1356
r(I)]
Final R indices [I > 2r(I)]

T.S. Lobana et al. / Polyhedron 29 (2010) 1130–1136
1133
Table 2
Selected bond lengths and bond angles.
1
Ni–S(1)
2.422(4)
Ni–N(1)
2.113(12)
Ni–N(2)
Ni–N(5)
2.022(11)
2.103(12)
1.292(18)
1.742(14)
78.99(5)
Ni–S(2)
Ni–N(6)
2.437(4)
2.031(11)
1.291(18)
1.733(14)
80.67(3)
80.25(3)
86.36(5)
159.56(3)
C(6)–N(2)
C(7)–S(1)
N(1)–Ni–N(2)
N(5)–Ni–N(6)
S(1)–Ni–S(2)
N(2)–Ni–N(6)
N(5)–Ni–S(2)
C(14)–N(6)
C(15)–S(2)
N(2)–Ni–S(1)
N(6)–Ni–S(2)
N(1)–Ni–N(5)
N(1)–Ni–S(1)
78.85(5)
97.14(13)
172.88(4)
158.27(3)
2
Ni–S(1)
Ni–N(2)
Ni–N(5)
2.409(13)
2.036(4)
2.137(4)
Ni–N(1)
Ni–S(2)
Ni–N(6)
2.100(4)
2.413(13)
2.037(4)
C(6)–N(2)
C(7)–S(1)
N(1)–Ni–N(2)
N(5)–Ni–N(6)
S(1)–Ni–S(2)
N(2)–Ni–N(6)
N(5)–Ni–S(2)
1.288(5)
1.725(5)
C(15)–N(6)
C(16)–S(2)
N(2)–Ni–S(1)
N(6)–Ni–S(2)
N(1)–Ni–N(5)
N(1)–Ni–S(1)
1.293(5)
1.724(4)
80.11(11)
80.20(11)
86.13(14)
158.76(11)
Fig. 1. Molecular structure of complex [Ni(pytscN-Me)2]ÁH2O (1).
78.72(14)
78.54(14)
96.38(4)
175.80(14)
157.10(11)
complexes. Similarly, magnetic moments (leff) of copper(II) com-
plexes 8 and 9 {1.80, 1.84 BM, respectively} are close to the spin-
only value of 1.73 BM for d9 system, Cu(II) [21].
4
The ligands show IR bands due to
moieties in the region 3432–3249 cmÀ1 and in complexes, the
(N2–H) (1–9) as well as the
(O–H) (4–9) bands disappear. This
reveals that the ligands are coordinated to the metal center in
the anionic forms. The diagnostic (C–S) bands lie in the range,
841–821 cmÀ1 in the complexes (cf. free ligands, 899–867 cmÀ1).
m m m(O–H)
(N1–H), (N2–H) and
Ni–N(1)
Ni–S(1)
C(25)–N(1)
N(1)–Ni–S(1)
O(1)–Ni–N(1)
O(1)–Ni–S(1)
1.879(6)
2.128(18)
1.302(9)
87.77(18)
94.60(3)
177.40(2)
Ni–O(1)
Ni–P(1)
C(26)–S(1)
P(1)–Ni–S(1)
P(1)–Ni–O(1)
P(1)–Ni–N(1)
1.855(6)
2.186(2)
1.759(7)
93.81(8)
83.90(2)
177.99(18)
m
m
m
6
The presence of PPh3 is confirmed by their characteristic m(P–C)
Ni–N(1)
Ni–S(1)
C(12)–N(2)
N(2)–Ni–O(1)
O(1)–Ni–N(1)
N(1)–Ni–N(2)
1.907(14)
2.144(5)
1.303(2)
96.64(6)
85.62(5)
177.73(6)
Ni–N(2)
Ni–O(1)
C(13)–S(1)
N(2)–Ni–S(1)
N(1)–Ni–S(1)
S(1)–Ni–O(1)
1.856(14)
1.867(12)
1.745(17)
87.64(4)
90.10(4)
bands at 1096 and 1097 cmÀ1 in 4 and 5, respectively.
4.2. Structures of complexes
175.71(4)
The detailed structural parameters of complexes 1, 2, 4, 6 and 8
are given in Table 1. The selected bond angles and bond lengths are
listed in Table 2.
8
Cu–N(1)
Cu–S(1)
C(7)–N(1)
N(1)–Cu–O(1)
O(1)–Cu–N(4)
N(1)–Cu–N(4)
1.951(3)
2.257(11)
1.302(4)
95.19(11)
86.49(11)
175.67(12)
Cu–N(4)
Cu–O(1)
C(8)–S(1)
N(4)–Cu–S(1)
N(1)–Cu–S(1)
O(1)–Cu–S(1)
2.041(3)
1.906(2)
1.754(3)
93.07(9)
85.71(9)
173.46(8)
4.3. Octahedral complexes
The atomic numbering scheme for complex [Ni(pytscN-
Me)2]ÁH2O (1) is given in Fig. 1. Complex crystallized in the mono-
Fig. 2. Packing diagram of complex 1.

1134
T.S. Lobana et al. / Polyhedron 29 (2010) 1130–1136
Fig. 3. Packing diagram of complex 2.
clinic crystal system. In this complex two uninegative pytscN-MeÀ
moieties are coordinated to nickel with sulfur and pyridyl nitrogen
atoms occupying cis positions of the octahedron [22]. The azome-
thine nitrogen atoms are in trans positions. The trans angles,
N(1)–Ni(1)–S(1) {159.56(3)}, N(5)–Ni(1)–S(2) {158.27(3)} and
N(2)–Ni(1)–N(6) {172.88(4)°}, suggest considerable distortion
from an octahedral geometry around the Ni(II) center (Table 2).
The bond parameters are analogous to [NiL2]Á0.5EtOH 10 (L =
2-acetylpyridine thiosemicarbazonate) [23], and [NiL2] 11 (L = iso-
quinoline-1-carbaldehyde thiosemicarbazonate) [24]. Further, it
was noted that the replacement of methyl group at N1 nitrogen
(HpytscN1-Me) by ethyl group (HpytscN1-Et), has also formed sim-
ilar octahedral complex, [Ni(pytscN-Et)2] 2 with slight variations in
the bond parameters compared to complex 1 (Table 2).
present in the crystal lattice and is involved in H-bonding, while
in 2 there is no water. In complex 1, the N1H and CH3 groups of
–N1HCH3 moiety are engaged in H-bonding with water molecule
{N1HÁ Á ÁOH2, 1.99; H3CÁ Á ÁHOH, 2.85 Å}, while in complex 2, the
N1H proton of –N1HCH2CH3 moiety is engaged in H-bonding with
sulfur atom of thioamide moiety {C–SÁ Á ÁHN1, 2.58 Å}, but ethyl
group shows no interaction with any electronegative atom. Fur-
ther, in complex 1, there are interactions of water with N2 and
CH3 groups {HOHÁ Á ÁN2(hydrazinic), 2.06 Å; HOHÁ Á ÁCH3, 2.85 Å}.
The oxygen atom of this water molecule further interacts strongly
with the adjacent Ni(pytscN-Me)2 molecule via H2OÁ Á ÁHN1 interac-
tion (1.99 Å). Similarly, there is an intermolecular C–HpyÁ Á ÁS = C
(2.78 Å) interaction leading to the formation of a zig-zag polymeric
chain. This polymeric chain interacts with another similar poly-
An analysis of the packing diagrams of 1 and 2 reveals interest-
ing trends of intermolecular interactions. In complex 1, water is
meric chain via C–SÁ Á ÁHN1(2.69 Å), H2C–HÁ Á Á
p(py, 2.89, 2.87 Å)
interactions forming a 2D polymer (Fig. 2).
While in complex 2, the deprotonated hydrazinic nitrogen,
(–N2–) and N1H hydrogen atom of one Ni(pytscN-Et)2 molecule
interacts with the adjacent Ni(pytscN-Et)2 molecule via (hydrazi-
nic)N2Á Á ÁHN1(substituted amino), and C–SÁ Á ÁHN1 interactions
(2.25 Å and 2.58 Å, respectively) forming a long polymeric 1D
chain. This polymeric chain interacts with another chain via C–
SÁ Á Á
p(py) interaction (2.94 Å), and forms a 2D polymer (Fig. 3).
4.4. Square planar complexes
The atomic numbering schemes for complexes 4 and 6 are gi-
ven in Figs. 4 and 5, respectively. Compounds 4 and 6 crystallized
in the triclinic system. The molecular structures of complexes,
[Ni(stscN-Me)Ph3P] (4) and [Ni(stscN-Me)py] (6) have shown that
the dinegative thiosemicarbazone ligands (stscN-MeÀ) bind to the
nickel(II) center via O, N3, S-donor atoms. The fourth coordination
site around nickel(II) is occupied by PPh3 ligand in complex 4 and
by pyridine in 6, forming distorted square planar complexes. In
both the complexes, the trans angles, {N1–Ni1–P1, 175.71(4);
S1–Ni–O1 177.73(6)° 4 and N1–Ni1–N2, 177.73(6); S1–Ni–O1,
175.71(4)° 6}, are similar and deviate less from linearity. The
Ni–P1 bond distance in complex 4 is similar to that in the analo-
gous complex, [Ni(L)(PPh3)] 12 (L = salicylaldehyde-N-phenylthi-
osemicarbazone) [25]. The Ni–N1(pyridine) bond distance in
complex 6 {1.907(14) Å} is similar to that in the analogous
Fig. 4. Molecular structure of complex [Ni(stsc-N-Me)(PPh3)] (4).

T.S. Lobana et al. / Polyhedron 29 (2010) 1130–1136
1135
Fig. 5. Molecular structure of complex [Ni(stsc-N-Me)(py)] (6).
complex, [Ni(L)py]NO3 (L = pyridoxal thiosemicarbazone) 13
{1.919(21) Å} [26]. Complex, [Cu(stscN-Me)py] (8), also has a
square planar geometry with the bond distances and angles, sim-
ilar to that in complex 6 (Table 2).
The packing diagrams of the square planar complexes revealed
that the methyl group at N1 nitrogen is involved in the intermolec-
ular interactions in 4 and 6. This behavior is similar to that in the
octahedral complexes discussed above. In complex 4, the
Fig. 6. Packing diagram of complex 4.
Fig. 7. Packing diagram of complex 6.

1136
T.S. Lobana et al. / Polyhedron 29 (2010) 1130–1136
molecules pack in a linear fashion along the a-axis with no interac-
tions with the adjacent molecules (Fig. 6). There are inter-chain
diagonal interactions between the molecules involving the methyl
Acknowledgements
Financial assistance from CSIR, New Delhi {Scheme no.
01(1993)/05/EMR II} and research facilities to one of us (Poonam)
by the university are gratefully acknowledged. The authors thank
Matthias Zeller of Youngstown State University, USA for his useful
suggestions and in X-ray crystallography.
substituent at N1 nitrogen {(CH3)C–HÁ Á Á
p
(C@N, azomethine),
(Ph–P),
2.835; (CH3)C–HÁ Á Á
p
(C6H4O–), 2.815, 2.891; (CH3)C–HÁ Á Á
p
2.826 Å} and form 2D polymeric network. In complex 6, the mole-
cules interact in a linear fashion along the a-axis involving methyl,
phenolate and pyridyl groups {(CH3)C–HÁ Á Á
r(C–H, CH3, 2.369 Å);
(py)C–HÁ Á Á (Ph, 2.895 Å) (Fig. 7).
p
Appendix A. Supplementary data
5. Solution phase studies
CCDC 747915, 747914, 747916, 747917 and 747913 contain the
supplementary crystallographic data for 1, 2, 4, 6 and 8. These data
can be obtained free of charge via http://www.ccdc.cam.ac.uk/con-
ts/retrieving.html, or from the Cambridge Crystallographic Data
Center, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-
336-033; or e-mail: deposit@ccdc.cam.ac.uk. Supplementary data
associated with this article can be found, in the online version, at
doi:10.1016/j.poly.2009.12.013.
The 1H NMR spectra of the diamagnetic complexes (4–7), re-
vealed that the –N2H (hydrazinic) and –OH (hydroxyl) moieties
were deprotonated. The –N1H-proton signals in complexes are up-
field relative to the free ligands {d: 4.74 (methyl, 4), 4.61(methyl,
6); 4.71 (ethyl, 5) and 7.24 ppm (phenyl, 7); free ligands’ –N1H-
protons: 7.56 (H2stscN-Me), 7.08(H2stscN-Et) and 8.95 ppm
(H2stscN-Ph)}. This trend is in line with the literature studies
[16]. It shows that the position of –N1H- proton signal changes
with the nature of the substituent. Finally, the C2H signals in com-
plexes are downfield (4, 5) or upfield (6, 7) depending on the type
of co-ligand (PPh3 versus py). The 31P NMR spectra showed coordi-
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D
d(dcomplex À dligand)} of 25.11 and 25.29 ppm in
complexes 4 and 5, respectively. These shifts show that the PPh3
is coordinating relatively strongly [27].
In the N, S-donor ligand, HpytscN-Et, two intense absorption
bands at 210 and 319 nm are assigned to
p ?
p* and n ? p* tran-
sitions, respectively. These bands in complex 2 appear at 226 and
301 nm. Two bands at 342 and 359 nm are assigned to S ? Ni
charge transfer transitions, while the bands at 800 and 407 nm
are assigned to the d–d transitions: A2g(F) ? 3T1g(F) and
3
3A2g(F) ? 3T1g(P), respectively. The various transitions in com-
plexes 1 and 3 are assigned as follows:
p ?
p* (224, 1; 209, 255,
3), n ? p* (301, 1; 320, 3), S ? Ni(CT) (345, 362, 1; 375, 3),
3A2g(F) ? 3T1g(P) (402, 1; 420, 3) and A2g(F) ? 3T1g(F) (800 nm,
3
1, 3) [21]. Similarly, in the O, N, S-donor ligand, H2stscN-Me, the
p
?
p* (211, 237 nm) and n ? p* transitions (293, 304, 331 nm)
shift to 233 and 301 nm in square planar complex 4. The S ? Ni
charge transfer transition in this complex appears to merge with
the 1A1g ? 1Eg transition at 363 nm. The band at 409 nm is as-
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p* (293,
8; 288, 9), n ?
* + O ? Cu (327, 8; 318, 9) and S ? Cu + 2B1g ? 2Eg
p ? p p
*), 302–320 (n ? *),
p
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p
(397, 8; 393, 9) [28].
6. Conclusion
In this investigation, two types of N1-subtituted thiosemicarba-
zone ligands have been used with pyridyl and 2-hydroxy phenyl
substituents at C2 carbon. Pyridyl based ligands act as uninegative
tridentate and formed bis-octahedral complexes, while 2-hydroxy
phenyl based ligands act as dinegative tridentate and formed
square planar complexes. The substituents at N1 nitrogen did not
affect geometry of nickel(II) complexes, however, they influenced
the packing arrangements as described in this paper. Here methyl
substituent participates in packing while ethyl group showed no
interaction. Finally the PPh3 ligand showed coordination to nicke-
l(II), but did not show any binding to copper(II).
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