Metal derivatives of N1-substituted thiosemicarbazones: Synthesis, structures and spectroscopy of nickel(II) and cobalt(III) complexes

Article abstract of DOI:10.1016/j.ica.2012.09.021

Reactions of nickel(II) and cobalt(II) salts with various N ¹-substituted thiosemicarbazones [R¹R²C ²N³-N²H-C¹(S)-N¹HR ³, H₂L; R¹ = C₆H₅-, R² = H, H₂L¹(R³ = Me); H ₂L²(R³ = Ph), R¹ = 2-OHC ₆H₄-, R² = H, H₂L³(R ³ = Me), H₂L⁴(R³ = Et), H ₂L⁵(R³ = Ph); R² = Me, H ₂L⁶(R³ = Me), R² = Me, H ₂L⁷(R³ = Et) and R², R³ = H, Me, H₂L⁸(R¹ = C₄H₃S), H₂L⁹(R¹ = C₄H₃O)] are described. Reactions of Ni(OAc)₂ with the ligands having R ¹ as phenyl group at C² carbon (H₂L ¹, H₂L²) gave complexes, [Ni(κ ²-N³, S-HL)₂] (HL^- = HL¹, 1; HL², 2). Other ligands with R¹ as 2-hydroxyphenyl groups, namely, H₂L³-H₂L⁷, with Ni(OAc)₂ yielded rust colored compounds, {Ni(κ³-O, N³, S-L)} (L^2- = L³-L⁷) which after the addition of PPh₂-CH₂-PPh₂ yielded dinuclear, [Ni₂(κ³-O, N³, S-L) ₂(μ-P, P-PPh₂-CH₂-PPh₂)] (L ^2- = L³, 3; L⁴, 4; L⁵, 5) and mononuclear, [Ni(κ³-O, N³, S-L)(κ¹- P-PPh₂-CH₂-PPh₂)] (L^2- = L ⁶, 6; L⁷, 7) complexes. Likewise, {Ni(κ³- O, N³, S-L⁵} with 2-phenylpyridine(2-Phpy) has yielded a mononuclear complex, [Ni(κ³-O, N³, S-L ⁵)(κ¹-N-2-Phpy)] 8. The geometry around Ni metal center can be formally described as square planar in each of complexes 1-8. Reactions of CoCl₂ with H₂L⁸ and H ₂L⁹ involved oxidation of Co^II to Co ^III and yielded octahedral complexes, [Co(κ²-N, S-HL)₃] (HL^- = HL⁸, 9; HL⁹, 10).

Full text of DOI:10.1016/j.ica.2012.09.021

Inorganica Chimica Acta 394 (2013) 605–615
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Inorganica Chimica Acta
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Metal derivatives of N1-substituted thiosemicarbazones: Synthesis, structures
and spectroscopy of nickel(II) and cobalt(III) complexes
a
a
b
c
d
Tarlok S. Lobana a, , Poonam Kumari , Geeta Hundal , Ray J. Butcher , A. Castineiras , Takashiro Akitsu
⇑
a Department of Chemistry, Guru Nanak Dev University, Amritsar 143 005, India
b Department of Chemistry, Howard University, Washington, DC 20059, USA
c Departamento De Quimica Inorganica, Facultad de Farmacia, Universidad de Santiago, 15782 Santiago, Spain
d Department of Chemistry, Tokyo University of Science, Tokyo 1628601, Japan
a r t i c l e i n f o
a b s t r a c t
Reactions of nickel(II) and cobalt(II) salts with various N1-substituted thiosemicarbazones [R1R2C2@N3–
N2H–C1(@S)–N1HR3, H2L; R1 = C6H5-, R2 = H, H2L1(R3 = Me); H2L2(R3 = Ph), R1 = 2-OHC6H4-, R2 = H,
H2L3(R3 = Me), H2L4(R3 = Et), H2L5(R3 = Ph); R2 = Me, H2L6(R3 = Me), R2 = Me, H2L7(R3 = Et) and R2, R3 = H,
Me, H2L8(R1 = C4H3S), H2L9(R1 = C4H3O)] are described. Reactions of Ni(OAc)2 with the ligands having
Article history:
Received 8 February 2012
Received in revised form 17 September
2012
Accepted 20 September 2012
Available online 3 October 2012
R1 as phenyl group at C2 carbon (H2L1, H2L2) gave complexes, [Ni( 2-N3, S-HL)2] (HLꢀ = HL1, 1; HL2, 2).
j
Other ligands with R1 as 2-hydroxyphenyl groups, namely, H2L3–H2L7, with Ni(OAc)2 yielded rust colored
compounds, {Ni(
3-O, N3, S–L)} (L2ꢀ = L3–L7) which after the addition of PPh2-CH2-PPh2 yielded dinuclear,
[Ni2(
3-O, N3, S–L)2( -P, P–PPh2–CH2–PPh2)] (L2ꢀ = L3, 3; L4, 4; L5, 5) and mononuclear, [Ni( 3-O, N3,
S–L)(
1-P–PPh2–CH2–PPh2)] (L2ꢀ = L6, 6; L7, 7) complexes. Likewise, {Ni( 3-O, N3, S-L5} with 2-phenylpyr-
idine(2-Phpy) has yielded a mononuclear complex, [Ni(
3-O, N3, S–L5)( 1-N-2-Phpy)] 8. The geometry
j
Keywords:
Thiosemicarbazone
Nickel(II)
Bis(diphenylphosphino)methane
Cobalt(III)
2-Phenylpyridine
j
l
j
j
j
j
j
around Ni metal center can be formally described as square planar in each of complexes 1–8. Reactions
of CoCl2 with H2L8 and H2L9 involved oxidation of CoII to CoIII and yielded octahedral complexes, [Co( 2-N,
j
S–HL)3] (HLꢀ = HL8, 9; HL9, 10).
Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
di-, tri- and poly-nuclear complexes [1]. The nature of substituents
at C2 carbon, the type of anion, co-ligands and solvents all influ-
enced bonding and nuclearity of complexes [16]. For example, it
was observed that furan-2-carbaldehyde thiosemicarbazones
(R2 = H) with NiII formed trans-(R3 = Me, Et) and cis-(R3 = Ph)
Thiosemicarbazones {R1R2C2@N3–N2H–C1(@S)–N1HR3 (I)} rep-
resent an interesting class of Schiff bases due to their variable do-
nor ability and structural diversity [1–8]. Applications of
thiosemicarbazones as well as their complexes in biology form
some of the key motives to pursue their coordination chemistry
[1]. Nickel(II) was found to affect the DNA repair mechanisms by
inhibiting the base excision repair (BER) and nucleotide excision
repair (NER) processes [9,10], which may become a potential merit
in the design of antitumor agents. Several nickel(II) complexes
have been found to inhibit proliferation of diverse cancer cells
[11–13]. For example, a square planar nickel(II) complex of thio-
phene-2-carbaldehyde thiosemicarbazone was tested against Mel-
anomaB16F10 and FLC cell lines [14] and octahedral nickel(II)
complex of phenanthrenequinone thiosemicarbazone was tested
on human breast cancer cell line, T47D rich in the progesterone
receptors and has a synergistic effect on the antiproliferative activ-
ity of the cell lines [15].
square planar complexes, [Ni(
furan ring showed coordination to NiII and formed octahedral com-
plexes, [Ni(
3-O, N, S–HL)2] (R3 = Me, Et, Ph) [18]. The analogous
thiophene thiosemicarbazones (R2 = H, Me) only formed trans
square planar complexes, [Ni(
2-N, S–HL)2].
j
2-N, S–HL)2] [17]. For R2 = methyl,
j
j
Further, there are limited reports on complexes of nickel(II)
with benzaldehyde-/salicylaldehyde-based thiosemicarbazones.
The 4-fluorobenzaldehyde thiosemicarbazone formed a square pla-
nar complex, [Ni(
carbazones formed either monomers, [Ni(
(Y = PPh3, py, NH3) [20–27] or oligomers [Ni(
(n = 2, 3) [28,24]. As regards CoII/III, in literature, tetrahedral
[CoIII2( 1-S–H2L)2] (H2L = acetophenone thiosemicarbazone) or
octahedral [CoIII(
acetophenone thiosemicarbazonate), [CoIII(
j
2-N, S–HL)2] [19], and salicylaldehyde thiosemi-
j
3-O, N3, S–L)Y]
3-O, N3, S–L)]n
j
j
j
3-O, N, S–L)( 2-N, N-bipy)(N3)] (L = 2-hydroxy
j
The interaction of thiosemicarbazones with several metals such
as copper(I), silver(I), gold(I), mercury(II), palladium(II),
platinum(II), ruthenium(II) and nickel(II) have yielded mono-,
j
3-O, N, S–HL)3]ꢁ
4H2O (HL = N-(anthracen-9-yl)methyleneamino]thioureate) and
[CoIII(
j
3-O, N, S–HL)3]ꢁ2MeOH (L = N-(2-hydroxyethyl)-2-(thio-
phene-2-ylmethelene)-hydrazinecarbothioamide) complexes are
reported [29].
⇑
Corresponding author. Fax: +91 183 2 258820.
E-mail address: tarlokslobana@yahoo.co.in (T.S. Lobana).
0020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.ica.2012.09.021

606
T.S. Lobana et al. / Inorganica Chimica Acta 394 (2013) 605–615
Complexes of nickel(II) with the thio-ligands shown in Chart 1
2.2.3. [Ni2(j l-P, P–PPh2–CH2–PPh2)] (3)
3-O, N3, S–L3)2(
are synthesized using PPh2–CH2–PPh2 and 2-Phpy as co-ligands.
A few reactions of furan- and thiophene-2-carbaldehyde thiosemi-
carbazones with cobalt(II) salt are also investigated. Various com-
plexes synthesized have been characterized with the help of
analytical data, spectroscopic techniques (IR, 1H and 31P NMR)
and single crystal X-ray crystallography (1, 2, 4 and 7–9).
To a solution of H2L3 (0.021 g, 0.100 mmol) in acetonitrile was
added solid NiCl2 salt (0.025 g, 0.100 mmol) followed by the addi-
tion of Et3N base (1 mL) and the contents were stirred for 1 h. To
this was added solid PPh2–CH2–PPh2 (0.039 g, 0.100 mmol) and
the contents further stirred for about 4 h and the clear solution
was allowed to evaporate at room temperature which yielded
red crystals along with the formation of Et3NH+Clꢀ salt. Yield:
58%; m.p. 210–212 °C. Anal. Calc. for
56.36; H, 4.40; N, 9.17. Found: C, 56.18; H, 4.61; N, 9.56%. IR
(KBr, cmꢀ1, selected absorption bands): (N1–H) 3412s;
(C–H)
3049w, 2991w, 2927w, 2878m; (C@N) + (C@C) 1600s, 1541s;
(P–CPh) 1097s; (C–N) 1026s, 989s, 916s;
(C–S) 752s. 1H NMR
C43H40Ni2N6O2P2S2: C,
2. Experimental
m
m
m
m
m
2.1. Materials and techniques
m
m
(d, ppm; CDCl3): 8.00 (s, 2H, C2H), 7.87 (m, 4H, C5H & C8H), 7.15
(m, 20H, o- & p- & m-H), 6.54 (m, 4H, C6H & C7H), 4.91 (db, 2H,
N1H), 2.86 (s, 2H, CH2), 2.10 (d, 6H, CH3(N1)). 31P NMR (d, ppm;
Metal salts, namely, NiCl2, Ni(OAc)2, CoCl2, as well as N-methyl
thiosemicarbazide, N-ethyl thiosemicarbazide, N-phenyl thiosemi-
carbazide, benzaldehyde, 2-hydroxybenzaldehyde, 2-hydroxy ace-
tophenone, bis(diphenylphosphino)methane, 2-phenylpyridine
and Et3N were procured from Aldrich Sigma Ltd. The thio-ligands
were synthesized by conventional procedures [30]. Elemental anal-
ysis for C, H and N were carried out using a thermoelectron FLAS-
HEA1112 analyzer. The melting points were determined with a
Gallenkamp electrically heated apparatus. The IR spectra were re-
corded using KBr pellets on a Varian 666-IR FT-IR spectrometer. 1H
NMR spectra were recorded on a JEOL AL300 FT spectrometer at
300 MHz in CDCl3 with TMS as the internal reference. The 31P
NMR spectra were recorded at 121.5 MHz with P(OMe)3 as the
external reference.
CDCl3): ꢀ127.74; coordination shift,
D
d (dcomplex ꢀ ddppm) = 34.93
(ddppm = ꢀ162.67 dppm).
Complexes 4 and 5 were synthesized by a similar method.
2.2.4. [Ni2(j l-P, P–PPh2–CH2–PPh2)] (4)
3-O, N3, S–L4)2(
Yield: 60%; m.p. 215–217 °C. Anal. Calc. for C45H44Ni2N6O2P2S2:
C, 57.18; H, 4.66; N, 8.89. Found: C, 56.98; H, 4.45; N, 9.01%. IR
(KBr, cmꢀ1, selected absorption bands):
m
(N1–H) 3419s;
m
m
(C–H)
(C@N) + (C@C) 1600s, 1541s;
(C–N) 1045s, 1027s, 999s; m
(C–S) 764s. 1H NMR
3078w, 2963w, 2927w, 2867m;
(P–Cph) 1097s;
m
m
m
(d, ppm; CDCl3): 7.99 (m, 6H, C2H, C5H & C8H), 7.22 (m, 20H, o- &
p- & m-H), 6.50 (m, 4H, C6H & C7H), 4.43 (db, 2H, N1H), 3.27 (m,
4H, CH2(N1)), 2.01 (s, 2H, CH2), 1.14 (d, 6H, CH3(N1)). 31P NMR
(d, ppm; CDCl3): ꢀ127.55; coordination shift,
D
d
(dcomplex
ꢀ
2.2. Synthesis of complexes
ddppm) = 35.11.
2.2.1. Trans-[Ni(j
2-N3, S–HL1)2] (1)
2.2.5. [Ni2(
j
3-O, N3, S–L5)2(
l
-P, P–PPh2–CH2–PPh2)]ꢁCH3CN (5)
To a colorless solution of H2L1 (0.038 g, 0.200 mmol) in metha-
nol (10 mL) was added solid Ni(OAc)2 (0.025 g, 0.100 mmol). The
color of the solution changed to dark brown and the contents were
stirred for about 4 h. The clear solution after filtration was left for
slow evaporation at room temperature which gave brown crystals.
Yield: 77%; m.p. 192–195 °C. Anal. Calc. for C18H20N6NiS2: C, 48.73;
Yield: 59%; m.p. 180–182 °C. Anal. Calc. for C55H47Ni2N7O2P2S2:
C, 61.09; H, 4.35; N, 9.07. Found: C, 69.24; H, 4.49; N, 8.87%. IR
(KBr, cmꢀ1, selected absorption bands):
m
(N1–H) 3433br;
m
(C–H)
(P–CPh) 1097s;
m
(C–S) 745s. 1H NMR (d, ppm; CDCl3):
3052m, 2998w;
m(C@N) + m(C@C) 1602s, 1535s; m
m
(C–N) 1020s, 996s, 902w;
8.20 (s, 2H, C2H), 7.96 (m, 12H, C5H & C8H & N1Ph-Hs), 7.48–6.94
(m, 20H, o- & p- & m-H), 6.52 (s, 4H, C6H & C7H), 6.45 (sb, 2H,
N1H), 3.21 (s, 2H, CH2). 31P NMR (d, ppm; CDCl3): ꢀ126.61; coordi-
H, 4.51; N, 18.95. Found: C, 48.54; H, 4.33; N, 19.01%. IR (KBr, cmꢀ1
,
selected absorption bands):
2876m; (C@N) + (C@C) 1548s, 1497s;
875s;
m
(N1–H) 3387br;
(C–N) 1067s, 1013s,
m(C–H), 2987m,
m
m
m
(C–S) 768s. 1H NMR (d, ppm; CDCl3): 8.05 (d, 4H, C4H &
nation shift,
D
d (dcomplex ꢀ ddppm) = 36.06.
m
C8H), 7.45 (s, 2H, C2H), 7.37 (m, 6H, C5–7H), 5.03 (sb, 2H, N1H),
3.00 (d, 6H, CH3).
2.2.6. [Ni(
j
3-O, N3, S–L6)( 1-P–PPh2–CH2–PPh2)] (6)
j
To a light yellow solution of H2L6 (0.022 g, 0.100 mmol) in
CH3CN (10 mL) was added solid Ni(OAc)2 (0.025 g, 0.100 mmol)
and the contents stirred for 2 h. During stirring rust colored com-
pound got separated and to this was added solid dppm (0.034 g,
0.100 mmol) with a further stirring for 15 min. The color of the
solution changed to reddish brown and slow evaporation of the
solution formed sticky mass, which was crystallized in methanol.
Yield: 69%; m.p. 176–178 °C. Anal. Calc. for C35H33N3NiOP2S: C,
63.28; H, 4.97; N, 6.33. Found: C, 63.45; H, 5.14; N, 6.19%. IR
Complex 2 was synthesized by a similar method.
2.2.2. Trans-[Ni(j
2-N3, S–HL2)2] (2)
Yield: 73%; m.p. 210–212 °C. Anal. Calc. for C28H24N6NiS2: C,
59.22; H, 4.23; N, 14.81. Found: C, 58.99; H, 4.35; N, 14.95%. IR
(KBr, cmꢀ1, selected absorption bands):
m
(N1–H) 3398br;
m(C–H)
3012m, 2998m;
m(C@N) + m(C@C) 1545s, 1478s; m(C–N) 1058s,
1017s; m
(C–S) 771s. 1H NMR (d, ppm; CDCl3): 8.01 (d, 4H, C4H &
C8H), 7.61 (s, 2H, C2H), 7.35 (m, 14H, C5H & C7H & o- & p- & m-
(KBr, cmꢀ1, selected absorption bands):
3051m, 2925m, 2856w;
m
(N1–H) 3420br;
m(C–H)
H), 7.09 (t, 2H, C6H), 6.89 (sb, 2H, N1H).
m
(C@N) +
m
(C@C) 1542s, 1483s;
m(P–CPh
)
5
4
5
5
4
OH
S
6
S
4
3
1
C
S
N2H
6
7
3
1
C
N2H
3
C2
1
C
N2H
7
3
N
6
8
3
N
C2
3
N
C2
X
8
N1HR3
R2
N1HR3
N1HR3
H
H
R3 = Me; X = S, H2L8; O, H2L9
R2 =H; R3 = Me, H2L3; Et, H2L4; Ph, H2L5
R2 = Me; R3 = Me, H2L6; Et, H2L7
R3 = Me, H2L1; Ph, H2L2
Chart 1.

T.S. Lobana et al. / Inorganica Chimica Acta 394 (2013) 605–615
607
1099s;
m
(C–N) 1068s, 1025m, 915s;
m
(C–S) 758s. 1H NMR (d, ppm;
stirred for 2 h followed by refluxing for 15 min. During refluxing a
black compound got separated along with Et3NH+Cl- salt. Both com-
pounds were separated and crystals for X-ray were grown in CH2Cl2
and CH3OH mixture (3:1::v/v). Yield: 71%; m.p. 150–152 °C. Anal.
Calc. for C21H26N9CoOS6: C, 37.51; H, 3.87; N, 18.76. Found: C,
37.89; H, 4.09; N, 18.68%. IR (KBr, cmꢀ1, selected absorption bands):
CDCl3): 7.95 (d, 1H, C5–H), 7.82 (dd, 1H, C8–H), 7.72–6.97 (m, 20H,
o- & p- & m-H), 6.92 (s, 2H, C6H & C7H), 4.42 (sb, 1H, N1H), 3.45 (d,
2H, CH2), 2.88 (s, 3H, CH3(C2)), 2.71 (s, 3H, CH3(N1)). 31P NMR (d,
ppm; CDCl3): ꢀ127.73, ꢀ166.59; coordination shift,
Dd (dcomplex -
ꢀ ddppm) = 34.94, ꢀ3.92.
Complexes 7 and 8 were synthesized by a similar method.
m
(N–H) 3396s;
m(C–H) 3048m, 2957m, 2929br; m(C@N) + m(C–C)
1510s, 1403s;
m
(C–N) 1045s; m
(C–S) 767s. 1H NMR (d, ppm; CDCl3):
7.56 (d, 3H, C2H), 7.40 (m, 3H, C6H), 7.23 (m, 3H, C4H), 7.05 (m, 3H,
C5H), 5.22 (sb, 3H, N1H), 3.25 (d, 9H, CH3).
2.2.7. [Ni(j j
3-O, N3, S–L7)( 1-P–PPh2–CH2–PPh2)] (7)
Yield: 65%; m.p. 198–200 °C. Anal. Calc. for C36H35N3NiOP2S: C,
Complex 10 was synthesized by a similar method.
63.68; H, 5.16; N, 6.19. Found: C, 63.97; H, 4.98; N, 6.27%. IR (KBr,
cmꢀ1, selected absorption bands):
m
(N1–H) 3451br;
m
(C–H) 3043m,
(P–CPh) 1100s;
m
(C–S) 763s. 1H NMR (d, ppm; CDCl3): 7.81 (dd,
2.2.10. [Co(j
2-N3, S–L9)3] (10)
2927m, 2878w;
(C–N) 1024s;
m(C@N) + m(C@C) 1548s, 1480s; m
m
Yield: 65%; m.p. 210–212 °C. Anal. Calc. for C21H26N9CoO3S3: C,
1H, C5H), 7.58 (dd, 1H, C8H), 7.42–6.78 (m, 20H, o- & p- & m-H),
6.59 (m, 1H, C6H), 6.45 (dd, 1H, C7H), 4.48 (sb, 1H, N1H), 3.30 (m,
2H, CH2(N1)), 3.17 (d, 2H, CH2), 2.73 (s, 3H, CH3(C2)), 1.15 (t, 6H,
CH3(N1)). 31P NMR (d, ppm; CDCl3): ꢀ122.46, ꢀ165.14; coordina-
37.51; H, 3.87; N, 18.76. Found: C, 37.89; H, 4.09; N, 18.68%. IR
(KBr, cmꢀ1, selected absorption bands):
m
(N–H) 3404br;
m
m
(C–H)
(C–N)
3005w, 2959m, 2887w;
1084s, 1011s, 945m;
m(C@N) + m(C–C) 1502s, 1402s;
m
(C–S) 750s. 1H NMR (d, ppm; CDCl3): 8.53
(d, 3H, C2H), 7.63 (q, 3H, C6H), 7.42 (t, 3H, C4H), 6.59 (t, 3H, C5H),
5.25 (sb, 3H, N1H), 3.09 (d, 9H, CH3).
tion shift,
D
d(dcomplex ꢀ ddppm) = 40.21, ꢀ2.47.
2.2.8. [Ni(
j
3-O, N3, S–L5)( 1-N-2-Phpy)] (8)
j
Yield: 72%; m.p. 175–177 °C. Anal. Calc. for C25H20NiN4OS: C,
62.08; H, 4.14; N, 11.59. Found: C, 61.92; H, 4.11; N, 12.10%. IR
2.3. X-ray crystallography
(KBr, cmꢀ1, selected absorption bands):
m
(N1–H) 3436br;
m
m
(C–H)
(C–N)
A single crystal was mounted on a glass fiber and used for data
collection using a Siemens P4 (1), Bruker X8 Kappa APEXII (2), Bru-
ker APEX-II CCD (4) and Xcalibur, Ruby, Gemini (7, 8) and Bruker
SMART CCD 1000 (9) diffractometers, equipped with Graphite
3105w, 3080w, 2986w;
1075s, 1019s, 942w;
m(C@N) + m(C@C) 1598s, 1517s;
m
(C–S) 763s. 1H NMR (d, ppm; CDCl3): 9.56
(s, 1H, C2H), 8.65 (dd, 2H, C9H & C5H), 8.62 (d, 1H, C12H), 8.00–
7.15 (m, 10H, o- & p- & m-H), 7.14 (m, 1H, N1H), 7.08 (m, 2H,
C10H & C11H), 6.71 (m, 3H, C8H & C6H & C7H).
monochromated Mo Ka (k = 0.71073 Å). Crystal data were col-
lected at 298(2) (1), 100(2) (2), 128(2) (4), 293(2) (7), 123(2) (8)
and 110(2) (9) K. For complex 1, structure was solved by direct
methods and refined by full-matrix least-squares refinement tech-
niques on F2 using SIR-92 and SHELXL-97 in the Wingx package of
programs [31]. Data reduction, structure solution, refinement and
2.2.9. [Co(
j
2-N3, S–L8)3]ꢁH2O (9)
To a suspension of H2L8 (0.063 g, 0.315 mmol) in toluene (10 mL)
was added solid CoCl2ꢁ6H2O (0.025 g, 0.105 mmol) and the contents
Table 1
Crystallographic data for compounds 1, 2, 4 and 7–9.
1
2
4
7
8
9
Empirical formula
Formula weight
T (K)
Crystal system
Space group
C
18H20N6NiS2
C28H24N6NiS2
567.36
100(2)
C45H44N6Ni2O2P2S2
944.34
128(2)
monoclinic
C2/c
C36H35N3NiOP2S
678.38
293(2)
monoclinic
P21/c
C25H20N4NiOS
483.22
123(2)
monoclinic
P21/c
C21H26CoN9OS6
671.80
100(2)
monoclinic
P21/c
443.23
295(2) K
monoclinic
C2/c
triclinic
ꢀ
P1
Unit cell dimensions
a (Å)
b (Å)
c (Å)
19.749(5)
7.474(5)
14.628(5)
90.00
109.480(5)
90.00
2035.6(2)
4
1.446
9.447(5)
10.750(6)
12.636(6)
84.357(2)
75.071(2)
84.480(2)
1230.63(1)
2
19.444(2)
8.829(1)
24.684(3)
90.00
95.10(2)
90.00
4220.6(8)
4
1.486
12.007(1)
10.239(1)
27.191(4)
90.00
100.80(2)
90.00
3283.4(8)
4
1.372
21.158(4)
6.069(1)
16.845(3)
90.00
90.83(2)
90.00
2162.5(7)
4
1.484
10.738(1)
29.112(3)
9.992(1)
90.00
114.96(2)
90.00
2831.7(5)
4
1.576
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (g cmꢀ3
)
1.531
0.990
l
(mmꢀ1
)
1.173
1.114
0.786
1.020
1.083
F (000)
920
588
1960
1416
1000
1384
Crystal size (mm3)
Reflections collected
Unique reflections
0.20 ꢂ 0.10 ꢂ 0.10 0.67 ꢂ 0.08 ꢂ 0.08
0.40 ꢂ 0.30 ꢂ 0.25
0.46 ꢂ 0.35 ꢂ 0.24
0.49 ꢂ 0.23 ꢂ 0.18
0.37 ꢂ 0.30 ꢂ 0.29
1946
25885
5042 (0.0518)
12649
30228
27298
33631
1889 (0.0226)
4848 (0.0271)
11040 (0.0789)
13819 (0.0249)
6068 (0.0512)
(Rint
)
Data/restraints/
parameters
1889/0/128
5042/0/334
4848/0/272
11040/0/399
13819/0/289
6068/0/343
Index ranges
0 6 h 6 23,
ꢀ11 6 h 6 11,
ꢀ13 6 k 6 13,
0 6 l 6 15
ꢀ22 6 h 6 25,
ꢀ11 6 k 6 9,
ꢀ31 6 l 6 32
R1 = 0.0340,
wR2 = 0.1038
R1 = 0.0428,
ꢀ13 6 h 6 17,
ꢀ15 6 k 6 15,
ꢀ36 6 l 6 41
R1 = 0.0645,
wR2 = 0.1445
R1 = 0.1231,
ꢀ38 6 h 6 32,
ꢀ11 6 k 6 11,
ꢀ30 6 l 6 30
R1 = 0.0424,
wR2 = 0.0901
R1 = 0.0624,
ꢀ13 6 h 6 12,
0 6 k 6 36,
0 6 k 6 9, -
17 6 l 6 16
0 6 l 6 12
Final R
indices[I > 2
R indices (all data)
R1 = 0.0463,
wR2 = 0.1201
R1 = 0.0657,
wR2 = 0.1267
0.732 and ꢀ0.640
R1 = 0.0343,
R1 = 0.0365,
wR2 = 0.0793
R1 = 0.0525,
wR2 = 0.0856
0.807 and ꢀ0.397
r
(I)]
wR2 = 0.0696
R1 = 0.0505,
wR2 = 0.0779
0.362 and ꢀ0.372
wR2 = 0.1133
0.499 and ꢀ0.249
wR2 = 0.1577
1.457 and ꢀ0.491
wR2 = 0.0988
0.634 and ꢀ0.493
Largest difference
peak and hole
(e Åꢀ3
)

608
T.S. Lobana et al. / Inorganica Chimica Acta 394 (2013) 605–615
Table 2
Table 3
Bond parameters of compounds 1, 2, 4 and 7–9.
Hydrogen bonds (Å) for Complexes 1, 2, 4 and 7–9.
Compound 1
Ni–N(1)
C(7)–N(1)
Complex
No.
D–Hꢁ ꢁ ꢁA
d(D–
H)
d(Hꢁ ꢁ ꢁA) d(Dꢁ ꢁ ꢁA) h(DHA)
1.906(3)
1.296(5)
85.26(9)
180
Ni–S(1)
2.1819(1)
1.744(4)
94.74(9)
180
C(8)–S(1)
1
C(9)–H(9A)ꢁ ꢁ ꢁNi
N(3)–H(31)ꢁ ꢁ ꢁN(2)#1
C(9)–H(9C)ꢁ ꢁ ꢁS(1)#1
N(24)–H(24A)ꢁ ꢁ ꢁS(1)
C(15)–H(15)ꢁ ꢁ ꢁC(22)
C(15)–H(15)ꢁ ꢁ ꢁC(21)
C(10)–H(10)ꢁ ꢁ ꢁC(26)
C(19) –H(19)ꢁ ꢁ ꢁS(2)
N(3)–H(3D)ꢁ ꢁ ꢁC(19)
C(10)–
0.960
0.825
0.960
0.890
0.950
0.950
0.950
0.950
0.711
0.980
2.620
2.450
2.920
3.010
2.865
2.763
2.826
2.881
2.734
2.865
3.540(5) 160.62
3.201(5) 151.75
3.843(5) 161.50
3.676(2) 133.20
N(1)–Ni–S(1)
N(1)#1–Ni–S(1)
S(1)–Ni–S(1)#1
N(1)#1–Ni–N(1)
Compound 2
Ni(1)–N(12)
Ni(1)–S(1)
N(12)–C(17)
S(1)–C(18)
N(12)–Ni(1)–S(1)
N(12)–Ni(1)–S(2)
S(1)–Ni(1)–S(2)
2
1.924(2)
2.175(6)
1.297(3)
1.739(2)
85.55(5)
95.27(5)
175.89(3)
Ni(1)–N(22)
Ni(1)–S(2)
N(22)–C(27)
S(2)–C(28)
N(22)–Ni(1)–S(2)
N(22)–Ni(1)–S(1)
N(22)–Ni(1)–N(12)
1.9223(2)
2.179(6)
1.301(3)
1.736(2)
85.47(5)
93.80(5)
178.62(8)
3.766
3.578
3.300
3.533
3.432
3.797
158.70
144.26
111.85
126.86
167.43
159.41
4
H(10B)ꢁ ꢁ ꢁC(22)
C(15)–H(15A)ꢁ ꢁ ꢁN(2)
C(10B)–H(8BA)ꢁ ꢁ ꢁS
C(1B)–
7
8
0.929
0.950
0.950
2.450
2.971
2.769
3.375
3.837
3.320
173.04
152.34
117.80
Compound 4
Ni(1)–O(1)
Ni(1)–S(2)
1.845(1)
2.122(6)
1.756(2)
95.62(6)
82.62(4)
176.51(5)
Ni(1)–N(1)
Ni(1)–P(1)
N(1)–C(7)
N(1)–Ni(1)–S(2)
S(2)–Ni(1)–P(1)
N(1)–Ni(1)–P(1)
1.889(2)
2.197(5)
1.297(2)
87.40(5)
94.20(2)
174.49(5)
H(1BA)ꢁ ꢁ ꢁC(1A)
S(2)–C(8)
C(1B)–
0.950
0.950
0.950
0.950
0.950
0.880
0.880
0.949
0.750
2.784
2.851
2.883
2.873
2.847
2.864
2.725
2.766
2.830
3.474
3.730
3.831
3.710
3.488
3.470
3.547
3.625
130.14
154.38
175.42
147.63
125.67
127.48
156.01
150.91
O(1)–Ni(1)–N(1)
O(1)–Ni(1)–P(1)
O(1)–Ni(1)–S(2)
H(1BA)ꢁ ꢁ ꢁC(2A)
C(1B)–
H(1BA)ꢁ ꢁ ꢁC(3A)
Compound 7
Ni–O(1)
Ni–S
C(1B)–
1.838(2)
2.143(9)
1.745(3)
95.07(9)
85.55(6)
174.73(7)
Ni–N(1)
Ni–P(1)
N(1)–C(7)
N(1)–Ni–S
S–Ni–P(1)
N(1)–Ni–P(1)
1.902(2)
2.196(8)
1.304(3)
88.19(7)
90.97(3)
176.82(7)
H(1BA)ꢁ ꢁ ꢁC(4A)
C(1B)–
S–C(9)
H(1BA)ꢁ ꢁ ꢁC(5A)
O(1)–Ni–N(1)
O(1)–Ni–P(1)
O(1)–Ni–S
C(1B)–
H(1BA)ꢁ ꢁ ꢁC(6A)
N(3A)–
H(3AB)ꢁ ꢁ ꢁC(12A)
Compound 8
Ni–O(1A)
Ni–N(1B)
N(3A)–
1.854(8)
1.930(9)
1.742(1)
96.06(4)
87.34(3)
172.15(4)
Ni–N(1A)
Ni–S
1.861(9)
2.147(3)
H(3AB)ꢁ ꢁ ꢁC(13A)
C(14A)–
S–C(8A)
H(14A)ꢁ ꢁ ꢁC(9A)
O(1A)–Ni–N(1A)
N(1A)–Ni–S
N(1A)–Ni–N(1B)
O(1A)–Ni–N(1B)
N(1B)–Ni–S
O(1A)–Ni–S
86.18(4)
91.65(3)
170.40(3)
9
N(14)–
3.566(2) 167.80
H(14A)ꢁ ꢁ ꢁS(32)
N(34)–H(34A)ꢁ ꢁ ꢁO(1) 0.880
2.060
2.850
2.891(3) 158.20
3.811(3) 177.50
Compound 9
Co(1)–N(22)
Co(1)–N(32)
Co(1)–S(32)
S(11)–C(11)
S(12)–C(16)
N(32)–C(35)
N(22)–Co(1)–N(12)
N(12)–Co(1)–N(32)
N(12)–Co(1)–S(12)
N(32)–Co(1)–S(32)
N(22)–Co(1)–S(22)
S(12)–Co(1)–S(22)
N(32)–Co(1)–S(12)
N(12)–Co(1)–S(22)
O(1)–H(1B)ꢁ ꢁ ꢁS(32)
0.960
1.949(2)
1.973(2)
2.223(7)
1.711(3)
1.743(3)
1.305(3)
93.73(8)
93.19(8)
86.11(6)
85.82(6)
84.94(6)
91.04(3)
175.39(6)
176.83(7)
Co(1)–N(12)
Co(1)–S(12)
Co(1)–S(22)
S(11)–C(14)
N(22)–C(25)
N(12)–C(15)
N(22)–Co(1)–N(32)
N(22)–Co(1)–S(12)
N(12)–Co(1)–S(32)
S(12)–Co(1)–S(32)
N(32)–Co(1)–S(22)
S(32)–Co(1)–S(22)
N(22)–Co(1)–S(32)
1.954(2)
2.221(7)
2.231(7)
1.722(3)
1.299(3)
1.289(3)
93.24(8)
91.35(6)
89.71(6)
89.62(3)
89.76(6)
91.65(3)
176.47(6)
methanol formed a clear brown solution in each case which on
slow evaporation yielded complexes of stoichiometry, [Ni(
2-N,
j
S–HL)2] (HLꢀ = HL1, 1; HL2, 2). Here, the deprotonation of –N2H–
group occurred and the ligands coordinate as uninegative biden-
tate anions. The same products were obtained when reactions
were performed in 1:1 M ratios. The PPh2–CH2–PPh2 did not show
coordination to NiII in complexes 1 and 2. Reactions of NiCl2 with
the thio-ligands, H2L3, H2L4 and H2L5 in the presence of Et3N base
using PPh2–CH2–PPh2 as co-ligand gave clear solutions in each case
and from which crystals of dinuclear complexes, [Ni2(
L)2(
-P, P–PPh2–CH2–PPh2)] (L = L3, 3; L4, 4; and L5, 5) were ob-
tained. For R2 = Me, the addition of PPh2–CH2–PPh2 to the brown
suspension of {Ni(
3-O, N3, S–L)} (L2ꢀ = L6, L7) in CH3CN (obtained
from Ni(OAc)2 and the thio-ligands, H2L6, H2L7) formed reddish
brown solution from which complexes of stoichiometry, [Ni(j3
O, N3, S–L)( 1-P–PPh2–CH2–PPh2)] (L2- = L6, 6; L7, 7) were obtained.
Further, reactions of 2-Phpy with {Ni(
3-O, N3, S–L5)} in acetoni-
trile gave crystals of composition, [Ni(
3-O, N3, S–L5)( 1-N-2-
j
3-O, N3, S–
l
molecular graphics were performed using SHELXTL-PC [32] and WINGX
[33]. The data were processed with APEX2 and corrected for absorp-
tion using SADABS [34] for complexes 2, 4 and CRYSALISPRO CCD (data col-
lection), CRYSALISPRO RED (cell refinement, data reduction) [35] for
complexes 7 and 8. For complex 9, data were processed with SAINT
[36] and corrected for absorption using SADABS [34]. The structures
were solved by direct methods using the program SHELXS-97 and re-
fined by full-matrix least-squares techniques against F2 using SHEL-
XL-97 [31]. Atomic scattering factors were taken from
‘‘International Tables for Crystallography’’ [37]. Molecular graphics
were taken from PLATON [38] and SCHAKAL [39]. The crystallographic
data and important bond parameters and H-bonds of complexes
(1, 2, 4, 7, 8 and 9) are given in Tables 1–3 respectively.
j
-
j
j
j
j
Phpy)] 8. This coordination behavior is similar to that of pyridine
[20]. Reactions of CoCl2 with heterocyclic thiosemicarbazones
(H2L8, H2L9) in the presence of triethyl amine base was anticipated
to form tetrahedral complexes of composition, [Co(
j
2-N, S–HL)2].
However, during crystallization, CoII got oxidized to CoIII and
yielded octahedral complexes of stoichiometry, [Co(
j
2-N, S–HL)3]
(HLꢀ = HL8, 9; HL9, 10).
IR spectroscopy revealed deprotonation of –N2H– group in com-
plexes 1–10. In addition, the –OH group is also deprotonated dur-
ing formation of complexes 3–8 which is further confirmed by the
single crystal X-ray crystallography (vide infra). The diagnostic
3. Results and discussion
3.1. Syntheses and IR spectroscopy
m
(C–S) bands (745–771 cmꢀ1) show low energy shift vis-à-vis the
Schemes 1–3 depict the formation of complexes 1–10. The reac-
free ligands (809–821 cmꢀ1
) and suggested that thio-ligands
tions of Ni(OAc)2 with H2L1 and H2L2 in 1:2 M ratio (M:L) in

T.S. Lobana et al. / Inorganica Chimica Acta 394 (2013) 605–615
609
P
S
P
5
Ni
N3
6
7
N3
S
S
4
3
H
S
N3
1
C
N2
(i)
X
Ni(OAc)2
3
N
2
C2
Ni
S
N3
8
N1HR3
Expected
H
R3 = Me 1, Ph 2
1 & 2
(i)
P
P, PPh2-CH2-PPh2
Scheme 1.
5
OH
C2
4
6
7
H
S
1
C
N2
3
N3
3
N
O
Ni(OAc)2
8
R2 = Me
(i)
N1HR3
{Ni(κ3-O,N3,S-L)}n
Ni
R2
S
R3 = Me, 6; Et, 7
NiCl2
Et3N
(i)
R2 = H
O
P
R2 = H
R2 = H
P
2-Phpy
(i)
S
N3
S
O
N3
Ni
P
P
N3
Ni
Ni
N-2-Phpy
R3 = Ph, 8
S
O
R3 = Me, 3; Et, 4; Ph 5
(i) =
P = PPh2-CH2-PPh2
.
P
Scheme 2.
3
N
5
4
S
S
H
S
1
C
toluene, Et3N
- Et3NH+Cl-
N2
3
C2
Co
6
3
N
N3
X
N3
3
+
N1HMe
Co2+
CoCl2·6H2O
air oxidation
Co3+
H
S
X = S, 9; O, 10
Scheme 3.
coordinate to the metal centers through thiolato sulfur atoms
[17,20]. The presence of tertiary phosphine is supported by its
characteristic
Section 2).
a square planar geometry with nickel(II) located on inversion cen-
ter with perfectly coplanar NiSCN2 planes.On changing R3 = Ph in
place of Me at N1 nitrogen in H2L2, again trans square planar com-
m
(P–CPh) bands in the range, 1097–1100 cm–1 (see
plex, [Ni(j
2-N, S–HL2)2] 2 has been obtained, which is similar to 1
(Fig. 2). In complex 2, the trans bond angles N–Ni–N and S–Ni–S
are 178.62(8)° and 175.89(3)° respectively suggesting a slight devi-
ation from the regular square planar geometry. Other bond param-
eters are similar to those found in 1.
3.2. Crystal structures
The crystal structure of [Ni(j
2-N, S–HL1)2] 1 complex has shown
that two uninegative (HL1)ꢀ ligands chelate to nickel(II) metal cen-
ter through azomethine nitrogen (N) and thiolato sulfur (S) atoms
For R2 = H at C2 carbon and R3 = Et at N1 atom, H2L4, the dinucle-
ar complex, [Ni2(j l-P, P–PPh2–CH2–PPh2)] 4 has
3-O, N, S–L4)2(
in trans-N2S2 fashion forming the five membered rings (Fig. 1). The
been obtained. Here, each nickel(II) ion is coordinated to a dinega-
tive (L4)2ꢀ thio-ligand through O, N and S atoms and two such
three coordinated units are bridged by PPh2–CH2–PPh2 ligand
(Fig. 3). The bond distances around two nickel centers are similar
{Ni(1)–O(1), 1.845(1); Ni(1)–N(1), 1.889(2); Ni(1)–S(2), 2.122(6);
Ni(1)–P(1), 2.197(5) Å}. These parameters are similar to those of
0
bond distances, Ni–N1 {1.906(3) Å} and Ni–S1 {2.182(1) ÅA}, are
similar to those in a related complex, [Ni(j
2-N, S–HL9)2] {Ni–N,
0
1.926(2); Ni–S, 2.175(9) ÅA} [17,40]. The parameters, C8–S1 bond
length, the N1ꢁꢁꢁC8 distance and the N1–N2–C8 angle, have been
used for distinguishing between anionic and neutral coordinated
thiosemicarbazone ligands. These parameters {angle N1–N2–C8,
110.64°; distance N1ꢁ ꢁ ꢁC8, 2.231 Å and bond length C8–S1,
1.74 Å} are similar to those for complexes with anionic thiosemi-
complex, [Ni(j
3-O, N, S–L3)(PPh3)], reported in the literature [19].
The O, N and S donor atoms have formed six and five membered
chelate rings with the bite angles, O(1)–Ni(1)–N(1) and N(1)–
Ni(1)–S(2) of 95.62(6)° and 87.40(5)° respectively and are similar
to those reported in the literature [19]. The trans bond angles
O(1)–Ni(1)–S(2) and N(1)–Ni(1)–P(1) are 176.51(5)° and
174.49(5)° respectively and suggest a distortion from a regular
carbazone ligands reported in literature [40a]. Further C8–S1 bond
0
distance {1.744(04) ÅA} shows a partial double bond character {C–S,
1.81; C@S 1.62 ÅA) as observed earlier for such thiosemicarbazone
complexes [1,40]. Trans angles, N–Ni–N and S–Ni–S {180}, suggest

610
T.S. Lobana et al. / Inorganica Chimica Acta 394 (2013) 605–615
(R2 = Me in place of H) at C2 carbon with R3 = Et, the thio-ligand
H2L7 formed a mononuclear complex, [Ni( 3-O, N, S–L7)( 1-P–
j
j
PPh2–CH2–PPh2)] 7. In this complex, the dinegative thio-ligand
(L7)2- coordinated to the metal center through O, N and S donor
atoms. The fourth coordination site is occupied by P atom of
PPh2–CH2–PPh2 co-ligand (Fig. 4). Unlike that in complex 4, here
one PPh2 group is pendant. The bond distances, Ni–O(1)
{1.838(2) Å}, Ni–N(1) {1.902(2) Å}, Ni–S {2.143(9) Å}, Ni–P(1)
{2.196(8) Å} are close to those found in complex 4. Trans angles
{174.73(7), 176.82(7)°} suggest a distorted square planar geometry
around the metal center.
The 2-pyridylphenyl co-ligand is coordinated to Ni(II) in com-
plex, [Ni(j j
3-O, N, S–L5)( 1-N-2-Phpy)] 8. Here, the dinegative thio-
semicarbazone ligand (L5)2ꢀ is bonded to the nickel(II) center
through O, N, S donor atoms and formed six and five membered che-
late rings (Fig. 5). It was expected that nickel(II) might metallate to
2-pyridylphenyl and form C, N-chelate bond or simply show coordi-
nation similar to pyridine. It however showed simple coordination
by pyridyl nitrogen and formed a square planar complex (8) similar
Fig. 1. Molecular structure of complex [Ni(j
2-N, S–HL1)2] 1 (Note: The carbon and
nitrogen atoms are numbered differently in Chart 1 and Schemes 1–3 from those in
molecular structures of 1, 2, 4, and 7–9).
to pyridine complex [Ni(j j
3-O, N, S–L3)( 1-N-py] [20]. However, the
bond parameters in 8 are slightly different than those found in pyr-
idine complex in literature [20]. For example, the bond distance, Ni–
O {1.853(8) Å}, is smaller and Ni–N2-Phpy {1.930(9) Å} is longer
{1.907(1) and 1.745(2) Å} [20]. The trans angles, 172.15(4)° and
170.40(3)°, suggest distorted square planar geometry.
Finally, X- ray crystal structure of complex, [Co(
j
2-N, S–HL8)3]ꢁ
H2O (9), shows that three uninegative (HL8)- ligands are coordi-
nated to cobalt(III) center via sulfur and azomethine nitrogen
atoms (Fig. 6). The bond lengths Co–N(azomethine) {1.954(2),
1.949(2), 1.973(2) Å} and Co–S {2.221(7), 2.231(7), 2.223(7) Å}
are close to those observed in bis complex, [CoL2](NO3)ꢁH2O
(L = pyridine-2-carbaldehyde-N-phenylethylthiosemicarbazonate)
{Co–N, 1.885(5), 1.876(5); Co–S, 2.232(2), 2.204(2) Å} [42]. The C–S
bond distances, (1.711(3), 1.722(3), 1.743(3) Å) are close to those
found in the literature [42]. The trans angles, N(32)–Co(1)–S(12),
175.39(6)°; N(32)–Co(1)–S(32), 176.47(6)° and N(12)–Co(1)–
S(22), 176.83(7)°, reveal a slight distortion from an octahedral
geometry.
Fig. 2. Molecular structure of complex [Ni(j
2-N, S–HL2)2] 2.
3.3. H-bonded networks
square planar geometry. Further, Niꢁ ꢁ ꢁNi separation (5.573 Å) is
much longer than twice the sum of the van der Waals radius of
nickel atoms, 3.26 Å [41]. The introduction of methyl group
In complex 1, the phenyl group present at C(7) carbon is not
engaged in the intermolecular interactions and the polymeric
Fig. 3. Molecular structure of complex [Ni2(j l-P, P–PPh2–CH2–PPh2)] 4.
3-O, N, S–L4)2(

T.S. Lobana et al. / Inorganica Chimica Acta 394 (2013) 605–615
611
Fig. 4. Molecular structure of complex [Ni(j j
3-O, N, S–L7)2( 1-P–PPh2–CH2–PPh2)] 7.
Fig. 5. Molecular structure of complex [Ni(j j
3-O, N, S–L5)2( 1-N–Phpy)] 8.
network is formed via N(3)–H(31)ꢁ ꢁ ꢁN(2)#1 (2.450 Å), C(9)–
H(9C)ꢁ ꢁ ꢁS(1)#1 (2.920 Å) and C(9)–H(9A)ꢁ ꢁ ꢁNi (2.620 Å) interac-
tions between adjacent molecules (Fig. 7). Polymeric network of
this complex shows the presence of cavities. In complex 2, interac-
tions between phenyl ring at C(17) carbon atom of one indepen-
dent molecule with phenyl ring at C(27) carbon atom of the
dinuclear unit with the phenyl group of PPh2–CH2–PPh2 ligand of
the adjacent dinuclear unit {C(19)–H(19)ꢁ ꢁ ꢁS(2), 2.881; N(3)–
H(3D)ꢁ ꢁ ꢁ
p(C(19)), 2.734 Å}. This 1D chain is linked with the similar
chain through C(10)–H(10B)ꢁ ꢁ ꢁ
p(C(22)), 2.865 Å interaction and
formed 2D sheet (Fig. 9). Complex 7 exists as a linear H-bonded
polymer which is formed through intermolecular interactions be-
tween phenyl ring of PPh2–CH2–PPh2 co-ligand and hydrazinic
nitrogen atom, C(15)–H(15A)ꢁ ꢁ ꢁN(2), 2.450 Å (Fig. 10).
adjacent molecule {C(15)–H(15)ꢁ ꢁ ꢁ
H(15)ꢁ ꢁ ꢁ (C(21)), 2.763 Å} led to the formation of 1D chain. Two
adjacent 1D chains are connected via phenyl groups at N(14) and
C(27) atoms {(C(26))ꢁ ꢁ ꢁ (C(110)), 3.300; C(10)–H(10)ꢁ ꢁ ꢁ (C(26)),
2.826 Å} which formed a 2D sheet (Fig. 8).
p(C(22)), 2.865; C(15)–
p
In complex 8, one molecule is connected with the adjacent mol-
p
p
ecule via C(10B)–H(8BA)ꢁ ꢁ ꢁS, 2.971 and C(1B)–H(1BA)ꢁ ꢁ ꢁ
p
p
p
(C(1A)),
(C(3A)),
(C(5A)),
2.769; C(1B)–H(1BA)ꢁ ꢁ ꢁ
2.851; C(1B)–H(1BA)ꢁ ꢁ ꢁ
p
p
(C(2A)), 2.784; C(1B)–H(1BA)ꢁ ꢁ ꢁ
(C(4A)), 2.883; C(1B)–H(1BA)ꢁ ꢁ ꢁ
Packing diagram of complex 4 shows that 1D chain is formed by
interactions between thioamide moiety of one independent
2.873; C(1B)–H(1BA)ꢁ ꢁ ꢁ
p(C(6A)), 2.847 Å interactions, and formed

612
T.S. Lobana et al. / Inorganica Chimica Acta 394 (2013) 605–615
Fig. 6. Molecular structure of complex [Co(j
2-N, S–HL8)3] (9).
Fig. 7. Packing interactions in complex 1.
Fig. 8. Packing interactions in complex 2.

T.S. Lobana et al. / Inorganica Chimica Acta 394 (2013) 605–615
613
Fig. 9. Packing interactions in complex 4.
Fig. 10. The intermolecular interactions between adjacent molecules of complex 7.
Fig. 11. Packing interactions in complex 8.
1D polymeric chain. Interactions between these 1D chains
through phenyl ring and amino hydrogen {N(3A)–H(3AB)ꢁ ꢁ ꢁ
p
(C(12A)), 2.864; N(3A)–H(3AB)ꢁ ꢁ ꢁ
p
(C(13A)), 2.725; C(14A)–
H(14A)ꢁ ꢁ ꢁ
p(C(9A)), 2.766 Å} formed 2D sheet (Fig. 11).

614
T.S. Lobana et al. / Inorganica Chimica Acta 394 (2013) 605–615
Fig. 12. Packing interactions in complex 9.
In complex 9, thiophene ring is engaged in intramolecular inter-
in the range, d 7.63–6.59 ppm. The N1HCH3 methyl protons appear
as a doublet at d 3.25 (9), 3.09 (10) ppm.
action with deprotonated hydrazinic hydrogen, S(11)ꢁ ꢁ ꢁN(13),
2.745; S(21)ꢁ ꢁ ꢁN(23), 2.743; S(31)ꢁ ꢁ ꢁN(33), 2.740 Å. One indepen-
dent molecule interacts with the adjacent molecule either directly
{N(14)–H(14A)ꢁ ꢁ ꢁS(32), 2.830 Å} or through water molecule pres-
ent in the crystal lattice {N(34)–H(34A)ꢁ ꢁ ꢁO(1), 2.060; O(1)–
H(1B)ꢁ ꢁ ꢁS(32), 2.850 Å} and formed a dinuclear unit. Two such
dinuclear units are connected through water molecule in the lat-
tice via N(34)–H(34A)ꢁ ꢁ ꢁO(1), 2.060 and C(11)–H(11)ꢁ ꢁ ꢁO(1),
2.613 Å interactions and formed polymeric chain (Fig. 12).
The 31P NMR spectra of complexes 3–7 confirmed the different
types of coordination behavior shown by PPh2-CH2-PPh2 co-ligand.
In complexes 3–5, a single peak is observed at d ꢀ127.74(3),
ꢀ127.55(4), ꢀ126.61(5) ppm (coordination shift ꢃ 35) which dem-
onstrated the equivalence of P atoms of the bridging PPh2–CH2–
PPh2 ligand [43]. However, complexes 6 and 7 showed two signals
which supported the presence of non equivalent phosphorus
atoms in these complexes. The presence of two different peaks is
assigned as follows: the signal at d ꢀ166.59 (6), ꢀ165.14 (7) ppm
is due to pendant P atom and that at d ꢀ127.73 (6), ꢀ122.46
3.4. Solution phase behavior
(7) ppm is due to coordinated P atom of
these complexes. The coordination shifts (
j
1-PPh2–CH2–PPh2 in
Dd) are 34.94 ppm in 6
The 1H NMR spectrum of the free thio-ligand shows a strong
signal at d 9.41 ppm, due to hydrazinic N2H hydrogen. The absence
of this signal in complex 1 confirms the deprotonation of N2H
hydrogen during complex formation [17]. Further, in this complex,
signal due to N1H proton at d 5.03 ppm showed upfield shift vis-à-
vis the free ligand (d 7.49 ppm). The C2H signal merges with phenyl
ring proton C4H and appears as doublet at d 8.05 ppm. The N1CH3
protons appear as doublet at d 3.00 ppm and show upfield shift rel-
ative to the free ligand (d 3.27 ppm). Complex 2 showed a similar
behavior (see Section 2).
and 40.21 ppm in 7 [43].
4. Conclusion
Benzaldehyde thiosemicarbazones (H2L1, H2L2) have shown N3,
S-chelation and formed only trans square planar nickel(II) com-
plexes 1 and 2, a behavior which is similar to that reported with
4-fluorobenzaldehyde thiosemicarbazone [19]. Salicylaldehyde
thiosemicarbazones (H2L3–H2L7) have formed dppm bridged dinu-
clear (3–5) complexes when R2 substituent at C2 was hydrogen and
mononuclear (6, 7) complexes with one PPh2 group of dppm pen-
dant when R2 substituent at C2 was methyl. The difference could be
attributed to the enhanced Lewis basicity of thio-ligands coupled
with steric effect of methyl group altering the mode of dppm li-
gand. 2-Pyridylphenyl in 8 behaves in the same way as does pyri-
dine. Complexes 3–7 report first examples of nickel(II) complexes
of thiosemicarbazones with a diphosphine as a co-ligand. The thio-
ligands H2L8 and H2L9 have formed tris octahedral complexes 9 and
10 [1].
In free ligand, H2L3, signals due to OH and N2H groups appear at
d 10.95 and 9.61 ppm respectively, but in complex 3, the disap-
pearance of these proton signals suggested their deprotonation
during complexation [20]. The N1H proton signal at d 4.91 ppm
in complex showed upfield shift relative to the free ligand (d
7.56 ppm). The signals of dppm ligand due to phenyl ring protons
are present as multiplets at d 7.15 ppm and –CH2– protons as sin-
glet at d 2.86 ppm. The methyl group at N1 nitrogen {d 2.10 ppm}
moved upfield relative to the free ligand {d 3.12 ppm}. Complexes
4–8 also showed the similar behavior. The characteristic signals
due to groups at N1 and C2 atoms of these complexes are listed
in Section 2.
Acknowledgements
The most characteristic signal due to N2H group in the free li-
gands {d 9.15, H2L8; 10.80, H2L9 ppm} is absent in complexes 9
and 10, which revealed the deprotonation of this group during
complexation [17]. The broad signal due to N1H proton in com-
plexes (9, d 5.22; 10, 5.25, ppm) showed upfield shift relative to
the free ligands (d 7.06, 6.48 ppm). Similarly, C2H signal at d 7.56
(9), 8.53 (10) ppm, showed up- and down- field shifts vis-à-vis
the free ligands, d 7.93, 7.86 ppm. The ligand ring protons appear
Financial assistance from CSIR, (Letter No. 09/254(0188)/2009-
EMR-I), New Delhi is gratefully acknowledged.
Appendix A. Supplementary material
CCDC 863154–863159; contains the supplementary crystallo-
graphic data for complexes 1, 2, 4 and 7–9. These data can be

T.S. Lobana et al. / Inorganica Chimica Acta 394 (2013) 605–615
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