Synthesis and characterization of square planar nickel(II) complexes with p-fluorobenzaldehyde thiosemicarbazone derivatives

Article abstract of DOI:10.1016/S0020-1693(00)00339-X

New thiosemicarbazone nickel complexes (1-7), derived from p-fluorobenzaldehyde and differently substituted thiosemicarbazides, were synthetized and characterized by means of NMR and IR techniques. The p-fluorobenzaldehyde 4-ethylthiosemicarbazone Et-Hfbt (1) and its complex [Ni(Et-fbt)₂] (2) were also characterized by X-ray diffractometry. Molecule 1 consists of two units: the p-fluorobenzaldehyde residue and the thiosemicarbazonic chain. In the reaction of 1 with NiAc₂·4H₂O, complex 2 was afforded. The molecular structure of 2 consists of the neutral complexes [Ni(Et-fbt)₂] with the metal not lying on a symmetry centre, with two consequently independent ligand molecules; the coordination results in a square planar geometry slightly twisted towards a tetrahedron, involving the sulfur and the hydrazine nitrogen atoms of the two ligands in a trans configuration.

Full text of DOI:10.1016/S0020-1693(00)00339-X

www.elsevier.nl/locate/ica
Inorganica Chimica Acta 312 (2001) 81–87
Synthesis and characterization of square planar nickel(II)
complexes with p-fluorobenzaldehyde thiosemicarbazone
derivatives
Marisa Belicchi Ferrari a,*, Silvia Capacchi b, Franco Bisceglie a, Giorgio Pelosi a,
Pieralberto Tarasconi a
a Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica, Uni6ersita` di Parma, Viale delle Scienze,
I-43100 Parma, Italy
b C.I.R.C.M.S.B., Unita` di Ricerca di Parma, Parma, Italy
Received 17 June 2000; accepted 2 October 2000
Abstract
New thiosemicarbazone nickel complexes (1–7), derived from p-fluorobenzaldehyde and differently substituted thiosemicar-
bazides, were synthetized and characterized by means of NMR and IR techniques. The p-fluorobenzaldehyde 4-ethylthiosemicar-
bazone Et-Hfbt (1) and its complex [Ni(Et-fbt)2] (2) were also characterized by X-ray diffractometry. Molecule 1 consists of two
units: the p-fluorobenzaldehyde residue and the thiosemicarbazonic chain. In the reaction of 1 with NiAc2·4H2O, complex 2 was
afforded. The molecular structure of 2 consists of the neutral complexes [Ni(Et-fbt)2] with the metal not lying on a symmetry
centre, with two consequently independent ligand molecules; the coordination results in a square planar geometry slightly twisted
towards a tetrahedron, involving the sulfur and the hydrazine nitrogen atoms of the two ligands in a trans configuration. © 2001
Elsevier Science B.V. All rights reserved.
Keywords: Thiosemicarbazone nickel complexes; Crystal structures; NMR spectra
1. Introduction
molecules, belonging to the class of thiosemicabazones,
able to behave as chelate ligands towards metal centres,
and their non-cisplatin-like complexes.
The discovery and the development of new, more
effective cancer medicines is one of the main goals of
present day medicine and chemical investigations. Re-
cently, the discovery of the antitumor effects of inor-
ganic and particularly of metal complexes and their use
to cure cancer diseases have received increasing atten-
tion. Metal chelation is a very important process, useful
both to remove a toxic metal from a polluted environ-
ment and to afford new chemical features to metal
complexes in order to make them suitable for practical
purposes (for instance pharmacological applications).
On the basis of these observations, we had previously
synthesized and characterized polyfunctional organic
In particular, copper(II) complexes, containing aro-
matic thiosemicarbazones of important biological inter-
mediates (pyridoxal or 5-formyluracil thiosemi-
carbazone) determined the apoptosis process on human
leukemic cell lines [1]. These ligands, in their neutral or
deprotonated form, behaved as a SNO terdentate
chelate towards metal ions essential for life. Now we
have prepared new nickel complexes bearing the
lipophilic p-fluorobenzene group and differently N(4)-
substituted thiosemicarbazides (Fig. 1), in order to ver-
ify whether SN monodeprotonable ligands are able to
condition the complicated mechanisms ruling the self-
regulated cell death on the same human cell lines U937
taken as a model [2].
* Corresponding author. Fax: +39-0521-905 557.
E-mail address: chimic8@ipruniv.cce.unipr.it (M.B. Ferrari).
0020-1693/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(00)00339-X

82
M.B. Ferrari et al. / Inorganica Chimica Acta 312 (2001) 81–87
Nickel has been chosen since its trace presence is now
t, J=7.3 Hz, NHCH2CH3), 8.08 (1H, s, CHꢀN), 7.85
(2H, m, H-2), 7.28 (2H, m, H-3), 3.61 (2H, quintet,
J=7.3 Hz, CH2), 1.18 (3H, t, J=7.3 Hz, CH3). FTIR
(KBr, cm−1): w (NH) 3366 (s), 3156 (ms); w (CH) 3000
(mw); w (CꢀC) 1602 (mw); w (CN) 1550 (vs); w (CS) 831
(m). MS (CI) m/z 226 (M+1). Anal. Calc. for
C10H12N3SF: C, 53.32; H, 5.37; N, 18.66; S, 14.21.
Found: C, 53.22; H, 5.30; N, 18.75; S, 14.30%.
recognized to be essential for bacteria, plants, animals
and humans [3], and it is also known that many nickel
complexes, coordinatively unsaturated, can behave as
Lewis acids. Having free coordinative positions around
the metal ion in our products with the nickel(II) in a
trans square planar SN configuration, our compounds
(all structurally similar) have been studied to widen our
comprehension of the role played by the metal and to
find out structural criteria for nickel complexes to be
biologically effective.
This screening method is appropriate for the antitu-
mor drugs whose pharmacopoeia is still lacking, but
unfortunately our molecules, though soluble and stable
in DMSO solutions, precipitated when brought into
contact with the biological medium, giving unrepro-
ducible results and did not allow a structure–activity
correlation. However it is remarkable to notice that
among the several nickel complexes structurally known
and reported in literature only four of them, containing
SN bidentate thiosemicarbazones, presented a trans
square planar coordination [4] analogous to that found
in our complexes, where the nickel ion lies in the field
of the S2N2 chromophore.
The same procedure, as shown for compound 1, was
followed to obtain ligands Me-Hfbt (p-fluorobenzalde-
hyde N4-methylthiosemicarbazone), allyl-Hfbt (p-
fluorobenzaldehyde
N4-allylthiosemicarbazone),
Ph-Hfbt (p-fluorobenzaldehyde N4-phenylthiosemicar-
bazone), Me2-Hfbt (p-fluorobenzaldehyde N4,N4-
dimethylthiosemicarbazone) and MePh-Hfbt (p-fluoro-
benzaldehyde
[5].
N4-3-methylphenylthiosemicarbazone)
2.2. Synthesis of the complexes 2–7
2.2.1. [Ni(Et-fbt)2] (2)
To a solution of Et-Hfbt (1) (0.017 g, 7.71×10−5
mol) in 10 ml of absolute EtOH, under stirring and
reflux heating, NiAc2·4H2O (0.019 g, 7.71×10−5 mol)
was added in a 1:1 molar ratio with respect to ligand 1.
Single needle-shaped blue crystals of [Ni(Et-fbt)2] (2)
were grown by slow evaporation of the alcoholic solu-
tion of 2. 1H NMR (300 MHz, DMSO): l 8.27 (2H, dd,
J=7.7, 4.9 Hz, H-2), 7.62 (1H, bs, NHCH2CH3), 7.44
(1H, s, CHꢀN), 7.25 (2H, t, J=7.7 Hz, H-3), 3.24 (2H,
m, CH2), 1.13 (3H, t, J=7.3 Hz, CH3). FTIR (KBr,
cm−1): w (NH) 3439 (vs); w (CꢀC)+w (CN) 1596 (m); w
(CN) 1580 (m), 1530 (vs); w (CS) 822 (mw). Anal. Calc.
for C20H24NiN6F2S2: C, 47.24; H, 4.76; N, 16.54; S,
12.59. Found: C, 47.14; H, 4.68; N, 16.66; S, 12.70%.
2. Experimental
All materials and solvents were obtained from com-
mercial suppliers and used without further purification.
p-Fluorobenzaldehyde was from Sigma, and thiosemi-
carbazide and its derivatives were from Janssen.
1H NMR were obtained at room temperature (r.t.) on a
Brucker AMX-300 spectrometer, and chemical shifts
are given in units of l relative to TMS as an internal
reference. For all compounds, dissolved in DMSO-d6,
the two signals of DMSO and water arose at 2.5 and
3.4 ppm, respectively. Infrared (IR) spectra were
recorded on a Nicolet 5PCFT-IR spectrophotometer in
the frequency range 4000–400 cm−1. CI-MS (m/z, 70
eV) were obtained on a Finnegan 1020 6c mass spec-
trometer. Elemental analyses were performed by the
Microanalytical Laboratory of the University of Parma
(Dipartimento di Chimica Generale ed Inorganica).
2.2.2. Ni(Me-fbt)2] (3)
To a solution of Me-Hfbt (0.011 g, 5.44×10−5 mol)
in 10 ml of EtOH 95%, under stirring and reflux
heating, was added, in a 1:2 molar ratio with respect to
the ligand, NiAc2·4H2O (0.007 g, 2.72×10−5 mol).
Green crystals of [Ni(Me-fbt)2] (3) were grown by slow
1
evaporation of the alcoholic solution. H NMR (300
MHz, DMSO): l 8.31 (1H, bs, NHCH3), 7.57 (2H, dd,
J=7.15, 5.6 Hz, H-2), 7.46 (1H, s, CHꢀN), 7.26 (2H, t,
2.1. Synthesis of the p-fluorobenzaldehyde
N4-ethylthiosemicarbazone Et-Hfbt (1)
To a solution of 4-ethylthiosemicarbazide (0.151 g,
1.27×10−3 mol) in 10 ml of EtOH 95%, at r.t. and
under stirring, was added p-fluorobenzaldehyde (0.134
ml, 1.27×10−3 mol) in 5 ml of EtOH 95%. Single
needle-shaped and transparent crystals of Et-Hfbt (1,
80%), suitable for X-ray analysis, were grown by slow
1
evaporation of the alcoholic solution of 1. H NMR
(300 MHz, DMSO): l 11.50 (1H, s, NHCS), 8.53 (1H,
Fig. 1.

M.B. Ferrari et al. / Inorganica Chimica Acta 312 (2001) 81–87
83
Table 1
heating, was added, in a 1:2 molar ratio with respect to
the ligand, NiAc2·4H2O (0.008 g, 3.35×10−5 mol).
Single needle-shaped yellow crystals of [Ni(Ph-fbt)2] (5)
were grown by slow evaporation of the alcoholic solu-
tion. 1H NMR (300 MHz, DMSO): l 9.78 (1H, s,
NHPh), 8.28 (2H, m, H-2), 7.77 (1H, s, CHꢀN), 7.55
(2H, m, H-3), 7.33 (2H, m, H meta phenyl), 7.25 (3H,
m, H ortho phenyl+H para phenyl). FTIR (KBr,
cm−1): w (NH) 3414 (vs); w (CH) 2950 (s); w (CꢀC) 1624
(m); w (CN) 1596 (m); w (CS) 820 (w). Anal. Calc. for
C28H22NiN6F2S2: C, 55.81; H, 3.68; N, 13.96; S, 10.62.
Found: C, 55.69; H, 3.59; N, 14.08; S, 10.73%.
Crystallographic data for ligand Et-Hfbt (1) and complex [Ni(Et-
fbt)2] (2) a
Et-Hfbt (1)
[Ni(Et-fbt)2] (2)
Formula
M
Crystal symmetry
Space group
Unit cell dimensions
C10H12N3FS
225.28
monoclinic
P21/c
C20H24NiN6F2S2
509.28
monoclinic
P21/n
,
a (A)
4.726(2)
25.369(8)
9.784(4)
90.0
103.50(3)
90.0
1140.6(8)
4
1.31
472
24.2
1.54184
Cu Ka
3–70
11.206(6)
14.186(9)
14.241(9)
90.0
95.19(7)
90.0
2255(2)
4
1.50
1056
10.8
0.71069
Mo Ka
3–30
,
b (A)
,
c (A)
h (°)
i (°)
2.2.5. [Ni(Me2-fbt)2] (6)
k (°)
V (A )
Z
To a solution of Me2-Hfbt (0.018 g, 8.00×10−5 mol)
in 10 ml of EtOH 95%, under stirring and reflux
heating, was added, in a 1:2 molar ratio with respect to
the ligand, NiAc2·4H2O (0.010 g, 4.00×10−5 mol).
Single needle-shaped brown crystals of [Ni(Me2-fbt)2]
(6) were grown by slow evaporation of the alcoholic
3
,
Dcalc (g cm−3
F(000)
)
v (cm−1
)
,
u (A)
Radiation
1
q Range (°)
No. of unique reflections
R
solution. H NMR (300 MHz, DMSO): l 8.24 (1H, s,
1347
0.053
2531
0.036
CHꢀN), 7.45 (2H, m, H-2), 7.20 (2H, m, H-3), 3.29 and
3.16 (6H, 2s, 3H each, CH3N). FTIR (KBr, cm−1): w
(NH) 3468 (ms, br); w (CH) 2925 (w); w (CꢀC)+w (CN)
a
,
Data for compound 1: Cu Ka radiation (u=1.54184 A); Siemens-
AED diffractometer, T=29391 K, P=[Max(Fo2, 0)+2Fc2]/3. Data
1600 (m);
w
(CS) 826 (mw). Anal. Calc. for
,
for complex 2: Mo Ka radiation (u=0.71069 A); Philips diffractome-
C20H22NiN6F2S2: C, 47.42; H, 4.38; N, 16.60; S, 12.64.
Found: C, 47.30; H, 4.29; N, 16.72; S, 12.71%.
ter, T=29391 K, P=[Max(Fo2, 0)+2Fc2]/3.
J=7.15 Hz, H-3), 2.83 (3H, d, J=4.6 Hz, CH3NH).
FTIR (KBr, cm−1): w (NH) 3432 (m), 3230 (m); w (CH)
3010 (m); w (CꢀC) 1604 (m); w (CN) 1597 (m); w (CS)
827 (m). Anal. Calc. for C18H18NiN6F2S2: C, 45.18; H,
3.79; N, 17.58; S, 13.38. Found: C, 45.07; H, 3.70; N,
17.70; S, 13.49%.
2.2.6. [Ni(MePh-fbt)2] (7)
To a solution of MePh-Hfbt (0.012 g, 4.18×10−5
mol) in 10 ml of EtOH 95%, under stirring and reflux
heating, was added, in a 1:2 molar ratio with respect to
the ligand, NiAc2·4H2O (0.005 g, 2.09×10−5 mol).
Brown crystals of [Ni(MePh-fbt)2] (7) were grown by
1
slow evaporation of the alcoholic solution. H NMR
2.2.3. [Ni(allyl-fbt)2] (4)
(300 MHz, DMSO): l 9.70 (1H, s, NHPh), 8.30 (2H,
m, H-2), 7.77 (1H, s, CHꢀN), 7.51 (2H, m, H ortho
phenyl+H meta phenyl), 7.25 (3H, m, H-3+H para
phenyl), 6.87 (1H, d, J=7.15 Hz, H ortho phenyl), 2.29
(3H, s, CH3). FTIR (KBr, cm−1): w (NH) 3386 (vs); w
(CH) 2930 (w); w (CꢀC)+w (CN) 1598 (m); w (CS) 831
(m). Anal. Calc. for C30H26NiN6F2S2: C, 57.13; H, 4.16;
N, 13.33; S, 10.15. Found: C, 57.00; H, 4.07; N, 13.45;
S, 10.28%.
To a solution of allyl-Hfbt (0.066 g, 2.78×10−4
mol) in 10 ml of EtOH 95%, under stirring and reflux
heating, was added, in a 1:2 molar ratio with respect to
the ligand, NiAc2·4H2O (0.034 g, 1.39×10−4 mol).
Brown crystals of [Ni(allyl-fbt)2] (4) were grown by
1
slow evaporation of the alcoholic solution. H NMR
(300 MHz, DMSO): l 8.28 (1H, t, J=1.8 Hz,
NHCH2), 7.81 (2H, m, H-2), 7.47 (1H, s, CHꢀN), 7.24
(2H, m, H-3), 5.92 (1H, m, CH2ꢀCH–CH2), 5.21 (1H,
dd, J=16.0, 2.0 Hz, CH2ꢀCH, H-b), 5.11 (1H, dd,
J=8.0, 2.0 Hz, CH2ꢀCH, H-a), 3.86 (2H, dd, J=6.0,
1.8 Hz, CH–CH2NH). FTIR (KBr, cm−1): w (NH)
3429 (vs); w (CH) 3020 (ms); w (CꢀC) 1633 (m); w (CN)
2.3. X-ray crystallography
Crystal data and details of structure refinement are
given in Table 1. The single crystal diffraction measure-
ments for compound 1 were carried out on a Siemens
AED three circle diffractometer with the q–2q scan
technique, using the Ni-filtered Cu Ka radiation (u=
1596 (m);
w
(CS) 823 (mw). Anal. Calc. for
C22H22NiN6F2S2: C, 49.81; H, 4.18; N, 15.85; S, 12.06.
Found: C, 49.72; H, 4.10; N, 15.97; S, 12.17%.
,
1.54184 A). For complex 2 the intensity data were
2.2.4. [Ni(Ph-fbt)2] (5)
carried out on a Philips diffractometer using the Mo
To a solution of Ph-Hfbt (0.018 g, 6.70×10−5 mol)
in 10 ml of EtOH 95%, under stirring and reflux
Ka radiation (u=0.71069 A). Intensities were mea-
sured following a modified version [6] of the method of
,

84
M.B. Ferrari et al. / Inorganica Chimica Acta 312 (2001) 81–87
Table 2
1H NMR (300 MHz, DMSO) chemical shifts of compounds 1–7
Compound
NHCS
NHR
CHꢀN
H-2
H-3
1
2
3
4
5
6
7
11.50 (1H, s)
8.53 (1H, t)
7.62 (1H, bs)
8.31 (1H, bs)
8.28 (1H, t)
9.78 (1H, s)
–
8.08 (1H, s)
7.44 (1H, s)
7.46 (1H, s)
7.47 (1H, s)
7.77 (1H, s)
8.24 (1H, s)
7.77 (1H, s)
7.85 (2H, m)
8.27 (2H, dd)
7.57 (2H, dd)
7.81 (2H, m)
8.28 (2H, m)
7.45 (2H, m)
8.30 (2H, m)
7.28 (2H, m)
7.25 (2H, t)
7.26 (2H, t)
7.24 (2H, m)
7.55 (2H, m)
7.20 (2H, m)
7.25 (2H, m)
–
–
–
–
–
–
9.70 (1H, s)
profile analysis by Lehmann and Larsen [7], and were
corrected for Lorentz and polarization effects. The
structures of all compounds were solved by direct meth-
ods using SIR-92 [8]. Refinements were carried out by
full-matrix least-squares cycles using SHELXL-97 [9] for
compounds 1 and 2. The hydrogen atoms, located on a
difference map, were refined for both products. Only in
compound 1 were the hydrogen atoms of the ethyl
group placed in calculated positions. Analytical expres-
sions of neutral-atom scattering factors were employed
according to the International Tables [10]. All calcula-
tions were performed on an ENCORE 91 computer at
the Centro di Studio per la Strutturistica Diffrattomet-
rica del C.N.R. (Parma). Molecular geometry calcula-
tions were carried out by using the computer program
PARST [11] and the structure drawings by using the
ORTEP [12] and PLUTO [13] programs.
1). A behaviour similar to compound 2 has also been
detected for the nickel complexes 3–7.
3.2. IR spectra
The IR spectra of compound 1 shows two bands in
the frequency range 4000–3000 cm−1, one due to the
stretching frequencies w (NH2) (at 3366 cm−1) and the
other one to the hydrazine NH (at 3156 cm−1, Table
3). On this basis, we have hypothesized that product 1
would form, during the crystallization, coupled dimers
stabilized by an intramolecular hydrogen bond (N–
Hterminal···Niminic), as found by the X-ray analysis.
A different spectral behaviour was observed for com-
pound 2 [Ni(Et-fbt)2]. In fact, when ligand 1 is coordi-
nated via N, S to the nickel atom, just one strong band
w (NH) occurs at 3439 cm−1, together with a separation
of 50 cm−1 of the w (CꢀN) (at 1580 and at 1530 cm−1),
and a 9 cm−1 shift of the band w (CS) appearing at 822
cm−1 (Table 3).
3. Results and discussion
This means that ligand 1 deprotonated before coordi-
nating the metal, thus determining a square planar
surrounding. As can be easily seen from Table 3, the IR
spectra of products 3, 4, 5, 6 and 7 are analogous to
that of complex [Ni(Et-fbt)2] (2). In this way, and in
agreement with the microanalyses data, we have hy-
pothesized that these ligands, after deprotonation and
coordination with the metal, should present a S2N2
square planar configuration.
3.1. NMR spectra
1
The H NMR spectrum of compound Et-Hfbt 1 (300
MHz, DMSO) shows, at r.t., the NHCS singlet, very
deshielded, at 11.50 ppm, the NHCH2CH3 triplet at
8.53 ppm, and the signal of the proton on the CꢀN
double bond at 8.08 ppm. The aromatic protons are
found in the range 7.85–7.28 ppm (Table 2).
The complex [Ni(Et-fbt)2] (2) (300 MHz, DMSO),
obtained from ligand 1 and NiAc2·4H2O, exhibits the
aromatic protons at 8.27 and 7.25 ppm, the NH signal
at 7.62 ppm, and the proton on the CꢀN double bond
at 7.44 ppm (Table 2). The substituted NH proton
(found at 8.53 ppm in the free ligand 1) is shielded with
respect to compound 1, as well as the proton on the
CꢀN double bond (observed at 8.08 ppm in the free
ligand 1): probably these two groups fall inside the
benzene shielding cone (Table 2).
On the contrary, the H-2 aromatic hydrogens result
deshielded at 8.27 ppm in complex 2 (at 7.85 ppm in
compound 1), presumably being outside the shielding
cone, while the H-3 protons do not show any significant
changes in the chemical shift (7.25 versus 7.28 ppm in
Table 3
IR (cm−1) principal bands for compounds 1–7
Compound
w(NH)
w(CN)
w(CS)
1
2
3
4
5
6
7
3366(s), 3156(ms)
3439(vs), –
3432(m), 3230(m), –
3429(vs), –
3414(vs), –
3468(ms,br), –
3386(vs), –
1550(vs)
1580(vs)
1597(m)
1596(m)
1596(m)
1600(m)
1598(m)
831(m)
822(mw)
827(m)
823(mw)
820(w)
826(mw)
831(m)

M.B. Ferrari et al. / Inorganica Chimica Acta 312 (2001) 81–87
85
Fig. 2. Perspective view of Et-Hfbt (1) with thermal ellipsoids at the 50% probability level.
ligand still behaves as bidentate with the sulfur and the
nitrogen atoms in cis position with respect to the C–N
bonds, and the right conformation for the complexa-
tion can be obtained from a 180° rotation (with respect
to the free ligand 1) around the C1–N2 and the C11–
N5 bonds, respectively, for the two ligand molecules.
3.3. X-ray crystallography
The structures of p-fluorobenzaldehyde N4-ethylth-
iosemicarbazone Et-Hfbt (1) has been determined. In
Fig. 2 an ORTEP [12] drawing of the molecule of com-
pound 1 is shown. The molecular conformation of the
sulfur atom and the hydrazine nitrogen N3 (crystallo-
graphic numbering) is trans with respect to the C1–N2
bond, and the packing is determined by the presence of
the strong intramolecular hydrogen bond N1–
,
The bond distances Ni–S1 2.172(2) A, Ni–S2 2.171(2)
,
,
,
A, Ni–N3 1.927(3) A and Ni–N6 1.926(3) A (Table 4)
Table 4
,
Comparison between bond distances (A) and angles (°) for 1, 2 and
[Ni(fbt)2] [5]
,
H···N3=2.607(4) A. The angle between the thiourea
group and the aromatic ring is small (6.4(2)°), and
therefore the whole molecule is fairly planar. The bond
distances of the benzene ring and the thiosemicarba-
zonic chain remain analogous to those found in similar
fluorurated compounds (Table 4) [14]. Pairs of inter-
molecular hydrogen bonds N2–H···S(1−x, −y, 1−
Et-Hfbt (1) [Ni(Et-fbt)2] (2)
[Ni(fbt)2] [5]
Bond
lengths
Ni–S1
2.172(2)
1.927(3)
1.727(4)
1.363(5)
1.348(5)
1.452(6)
1.381(4)
1.302(4)
1.299(5)
1.455(5)
1.396(5)
1.385(5)
1.367(6)
1.368(6)
1.342(7)
1.383(6)
1.493(7)
2.171(2) a
2.2075(12)
1.934(4)
1.750(4)
1.370(6)
1.363(5)
Ni–N3
S1–C1
F1–C6
N1–C1
N1–C9
N2–N3
N2–C1
N3–C2
C2–C3
C3–C4
C3–C8
C4–C5
C5–C6
C6–C7
C7–C8
C9–C10
1.926(3) a
1.722(4) a
1.360(5) a
1.341(5) a
1.438(6) a
1.388(4) a
1.311(5) a
1.307(5) a
1.462(5) a
1.380(5) a
1.395(5) a
1.382(6) a
1.362(6) a
1.344(7) a
1.372(7) a
1.501(7) a
,
z)=3.394(3) A promote the dimers formation, linked
1.679(4)
1.356(5)
1.320(5)
1.447(6)
1.370(4)
1.351(4)
1.273(4)
1.466(5)
1.384(5)
1.393(5)
1.382(6)
1.372(7)
1.356(7)
1.383(6)
1.416(8)
by weak hydrogen bonds C10–H10···F(x+2, 1/2−y,
,
z+1/2)=3.523(8) A, with an angle C10–H10···F=
,
155° and H···F=2.630 A [15,16]. Weak interactions
1.409(4)
1.324(5)
1.312(5)
1.480(6)
1.406(6)
1.418(6)
1.403(7)
1.390(6)
1.377(6)
1.400(7)
,
C2···C8(1+x, y, z) (3.556(6) A) arise along the x axis
that is particularly short.
Also, a complex derived from the reaction of ligand
1 with NiAc2, the bis(p-fluorobenzaldehyde ethylth-
iosemicarbazonato)nickel(II) ([Ni(Et-fbt)2], 2) has been
structurally characterized (Fig. 3). Differently from the
similar previously synthesized complex [Ni(fbt)2] [5], the
nickel atom is not placed in a special position, and two
independent ligand molecules are present. The coordi-
nation results in a square planar configuration slightly
twisted towards a tetrahedron, involving the sulfur and
the hydrazine nitrogen atoms of the two ligands in a
trans configuration, with the Ni atom displaced by 0.06
Bond angles
S1–Ni–N3
N3–Ni–S2
85.35(11)
94.08(10)
85.57(11) a 84.90(10)
94.90(10) a 95.10(10)
a Corresponding values found for the second independent molecule
,
A from the coordination plane. The monodeprotonated
of complex 2. The atomic numbering is shown in Fig. 3.

86
M.B. Ferrari et al. / Inorganica Chimica Acta 312 (2001) 81–87
Fig. 3. Perspective view of complex [Ni(Et-fbt)2] (2) with thermal ellipsoids at the 50% probability level.
agree with the correspondent values found for square
planar and slightly twisted coordinations [4d,14]. The
chelation ring NiN3N2C1S1 presents an en6elope con-
4. Supplementary material
Crystallographic data for the structures reported in
this paper have been deposited with the Cambridge
Crystallographic Data Centre, CCDC no. 145284 for
Et-Hfbt (1) and CCDC no. 145285 for [Ni(Et-fbt)2] (2).
Copies of this information may be obtained free of
charge from the Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (fax: +44-1223-336-033;
,
formation (puckering parameters: q2=0.130(2) A, €2=
−176(1)°)), while the conformation of the other ring
NiN6N5C11S2 is intermediate between twist and en6el-
,
ope (q2=0.085(2) A, €2= −11(1)°) [17], showing an
interplanar angle of 4.7°. In this case the deprotonation
of the nitrogen atoms N2 and N5 produces a charge
delocalization
in
the
C2N3N2C1N1S1
and
e-mail:
deposit@ccdc.cam.ac.uk
or
http://
C12N6N5C11N4S2 systems (Table 4), but less strong
www.ccdc.cam.ac.uk).
than in complex [Ni(fbt)2] [5]. In fact the distances
,
,
S1–C1=1.727(4) A and S2–C11=1.722(4) A (thiolic
Acknowledgements
,
,
form), C1–N2=1.302(4) A and C11–N5=1.311(5) A,
,
,
C2–N3=1.299(5) A and C12–N6=1.307(5) A were
detected for complex 2, while the corresponding values
for the free ligand Et-Hfbt (1) resulted in S1–C1=
1.679(4) A (thionic form), C1–N2=1.351(4) A and
C2–N3=1.273(4) A (due to a major localization of the
double bond). The angle between the thiourea group
and the aromatic ring is 17.5(1)° and 15.0(1)°, respec-
tively, for the two ligand molecules: both values are
larger than that observed in the free ligand (6.4(2)°),
which is almost planar. The packing is determined by
hydrogen bonds between the aminic nitrogen atoms
and the fluorine atoms (N1···F1(x+1, y, z)=3.267(4)
This work was supported by Italian MURST
(COFIN 98) in the frame of the Project ‘Pharmacologi-
cal and Diagnostic Properties of Metal Complexes’
(Coordinator Professor G. Natile). The authors ac-
knowledge the Centro Interfacolta` di Misure ‘Giuseppe
Casnati’ dell’Universita` di Parma for NMR and MS
instrumental facilities, and D. Belletti, A. Cantoni and
G. Pasquinelli for their valuable technical assistance.
,
,
,
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