Synthesis of hybrid ligands derived from benzil, thiosemicarbazide and heteroaromatic hydrazides and their reactivity with group 12 metals

Article abstract of DOI:10.1016/j.poly.2013.02.025

Two new dissymmetric ligands were synthesized by successive condensations of 2,3-diphenylethanedione with 2-hydrazinepyridine or 2-hydrazinequinoline and thiosemicarbazide. As hydrochloric acid was necessary for the condensation reactions, the ligands were obtained as the chloride salts. While the pyridine derivative [H₃BTsP]Cl was obtained in a reasonable yield, the quinoline-containing one [H₃BTsQ]Cl was isolated in a small amount, so its reactivity with metal salts was not explored. By contrast, three new complexes with zinc, cadmium and mercury nitrates, [ZnCl(H₂BTsP)] NO₃ (1), [Cd(H₂BTsP)(NO₃)₂] (2) and [Hg(H₂BTsP)(NO₃)]NO₃ (3), were obtained with [H₃BTsP]Cl. In all the complexes the ligand behaves as a neutral tetradentate donor giving rise to monomeric species in which the metal coordination environment is completed by chlorido or nitrato groups. The ligands and the complexes were characterized by elemental analysis, molar conductivity, mass spectrometry, IR, ¹H and ¹³C NMR spectroscopy and most of them by X-ray single crystal diffraction.

Full text of DOI:10.1016/j.poly.2013.02.025

Polyhedron 54 (2013) 39–46
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis of hybrid ligands derived from benzil, thiosemicarbazide
and heteroaromatic hydrazides and their reactivity with group 12 metals
1
⇑
David G. Calatayud , Elena López-Torres, M. Antonia Mendiola
Departamento de Química Inorgánica, C/Francisco Tomás y Valiente 7, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
a r t i c l e i n f o
Article history:
Received 11 December 2012
Accepted 9 February 2013
Available online 20 February 2013
Two new dissymmetric ligands were synthesized by successive condensations of 2,3-diphenylethanedi-
one with 2-hydrazinepyridine or 2-hydrazinequinoline and thiosemicarbazide. As hydrochloric acid was
necessary for the condensation reactions, the ligands were obtained as the chloride salts. While the pyr-
idine derivative [H3BTsP]Cl was obtained in a reasonable yield, the quinoline-containing one [H3BTsQ]Cl
was isolated in a small amount, so its reactivity with metal salts was not explored. By contrast, three new
complexes with zinc, cadmium and mercury nitrates, [ZnCl(H2BTsP)]NO3 (1), [Cd(H2BTsP)(NO3)2] (2) and
[Hg(H2BTsP)(NO3)]NO3 (3), were obtained with [H3BTsP]Cl. In all the complexes the ligand behaves as a
neutral tetradentate donor giving rise to monomeric species in which the metal coordination environ-
ment is completed by chlorido or nitrato groups. The ligands and the complexes were characterized by
elemental analysis, molar conductivity, mass spectrometry, IR, 1H and 13C NMR spectroscopy and most
of them by X-ray single crystal diffraction.
Keywords:
Dissymmetric thiosemicarbazones
Metal complexes
X-ray diffraction
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
The design and synthesis of dissymmetric double-Schiff-base li-
gands containing this TSC moiety has started during the last dec-
ade, but only a short number of research groups in the world
have developed efficient strategies. The accessibility of such asym-
metric ligands is often hampered by several synthethic problems,
which is the reason why this field is not much developed. The
problems found in the synthesis include ring-closure reactions or
the obtaining of the corresponding symmetric ligands, as well as li-
gand mixtures that are very difficult to purify [18]. The asymmetric
thiosemicarbazone molecules can be divided into two groups:
mixed bis(thiosemicarbazone) ligands containing two dissimilar
thiosemicarbazone functions [19,20], or molecules containing only
one thiosemicarbazone arm and additional functional groups in
the other one, which opens the posibility of incorporating different
types of donor atoms to fit better the metal preferences [21,22].
The synthesis of these molecules is usually carried out in two
steps. The first step is the obtaining of the open-chain [1 + 1] proli-
gand, which contains a carbonyl group available for the condensa-
tion with another amine. These reactions are complicated and it is
necessary to carefully control the reaction conditions such as the
temperature, concentration or the solvent used, since small
changes can yield undesired products, such as [1 + 1] heterocycles
or the [1 + 2] symmetric ligands, which are normally more stable
[18,23,24].
The interest in thiosemicarbazone (TSCs) ligands and their com-
plexes has increased steadily for the last years. The TSCs chemistry
is not only interesting by their versatility as ligands [1–3], but also
by their structural, optical and biological properties [2,4–6] that in-
clude antitumor, antibiotic, antifungal and antiviral activity [4,7,8].
They have been the subject of at least 12 patents mainly related to
their antibacterial properties and it is well established that transi-
tion metal complexes of TSCs are potent pharmacological agents
that normally show more activity than the free ligands. Pharmaco-
logical studies have shown that introduction of substituents in the
N4 of the TSC branch of these ligands, influences their biological
activity although it has not been established yet a relationship be-
tween activity and structure. Some ligands and complexes of thio-
semicarbazone derivatives have also activity against parasitic
protozoans, which cause diseases like malaria [9], sleeping sick-
ness [10] etc., since they inhibit the activity of the cysteine prote-
ases, which are necessary for the lifecycle of the parasite [10–12].
Recently, complexes of bis(TSC) with copper have been explored as
imaging agents in positron emission tomography (PET) studies to
identify hypoxic tissues [13–17].
In previous papers we have detailed the synthesis of the dis-
symmetric ligands obtained by reaction of 2,3-butanedione, 4-
methyl-thiosemicarbazide and 2-hydrazinepyridine [25] or 2-
hydrazinequinoline [26] and explored their reactivity with group
⇑
Corresponding author. Tel.: +34 91 497 4844; fax: +34 91 497 4833.
E-mail address: antonia.mendiola@uam.es (M. Antonia Mendiola).
1
Present address: Departamento de Electrocerámica, Instituto de Cerámica
Vidrio, CSIC, C/Kelsen 5, Cantoblanco, 28049 Madrid, Spain.
y
0277-5387/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2013.02.025

40
D.G. Calatayud et al. / Polyhedron 54 (2013) 39–46
12 metal salts under different reaction conditions. Following our
interest in the synthesis of bis(TSCs) derived from 2,3-diphenyle-
thanedione (benzil) [27–31], in this paper we report the synthesis
of the hybrid ligands obtained from benzil, thiosemicarbazide and
2-hydrazinepyridine or 2-hydrazinequinoline, as well the reactiv-
ity of the pyridine-containing ligand with zinc, cadmium and mer-
cury nitrates.
2.3. Synthesis of the quinoline precursor and the proligands
2.3.1. 2-Hydrazinequinoline
2-Hydrazinequinoline was synthesized by reaction of 2-chloro-
quinoline with monohydrated hydrazine, following the previously
described procedure [26].
2.3.2. [H2BP]Cl
To a solution in ethanol (65 mL) at 0 °C of benzil (1.00 g,
4.76 mmol) with conc. HCl (0.44 mL, 4.98 mmol), a solution of 2-
hydrazinepyridine (0.52 g, 4.76 mmol) in ethanol (20 mL) was
added slowly. The solution was stirred at 0 °C for 18 h then half
of the solvent was removed under vacuum. After 24 h at À18 °C
a pale yellow solid precipitated which was filtered off and dried
in vacuo. Yield: 71% (1.00 g). Elem. Anal. Calc. for C19H16N3ClO
(337.80): C, 67.56; H, 4.77; N, 12.44. Found: C, 67.45; H, 4.64; N,
2. Experimental
2.1. Materials and general methods
All reagents were obtained from standard commercial sources
and were used as received. Caution! Mercury and cadmium are
highly toxic cumulative poison, and their compounds should be han-
dled carefully.
12.39%. IR (KBr, cmÀ1): 3178(m)
m(NH), 1674(s) m(CO), 1644(s)
m
(CNpy). 1H NMR (300 MHz, DMSO-d6): d/ppm 13.92 (s, 1H, HNpy),
Microanalyses were carried out using a LECO CHNS-932 Ele-
mental Analyzer. IR spectra in the 4000–400 cmÀ1 range were re-
corded as KBr pellets on a Jasco FT/IR-410 spectrophotometer.
Fast atom bombardment mass spectra were recorded on a VG Auto
Spec instrument using Cs as the fast atom and m-nitrobenzylalco-
hol (m-NBA) as the matrix. Electrospray mass spectrometry exper-
iments were performed with an ion trap instrument LCQ Deca XP
plus (Thermo Instruments). An ESI source was used in positive ion-
ization mode. Conductivity was measured using a freshly prepared
DMF solution (ca. 10À3 M) at 25 °C with a Crison EC-Meter BASIC
30+ instrument. 1H and 13C NMR spectra were recorded on a spec-
trometer Bruker AMX-300 using DMSO-d6 or CDCl3 as solvents and
using TMS as internal reference. 13C CP/MAS NMR spectra were re-
corded at 298 K in a Bruker AV400WB spectrometer equipped with
a 4 mm MAS NMR probe (magic-angle spinning) and obtained
using cross-polarization pulse sequence. The external magnetic
field was 9.4 T, the sample was spun at 10–14 kHz and the spec-
trometer frequency was 100.61 MHz. For the recorded spectra a
contact time of 4 ms and recycle delays of 4 s were used. Chemical
shifts are reported relative to TMS, using the CH group of adaman-
tane as a secondary reference (29.5 ppm).
10.18 (s, 1H, NH), 8.22–7.14 (m, 14H, aromatic). 1H NMR (300 MHz,
CDCl3): d/ppm 13.66 (s, 1H, HNpy), 9.85 (s, 1H, NH), 8.09–6.80 (m,
14H, aromatic). MS (FAB+): m/z 302.1 ([H2BP]+, 100%).
2.3.3. [H2BQ]Cl
A solution of 2-hydrazinequinoline (0.50 g, 3.14 mmol) in meth-
anol (40 mL) with conc. HCl (0.31 mL, 3.51 mmol) was added to a
solution of benzil (0.66 g, 3.14 mmol) in methanol (50 mL) with
12 drops of conc. HCl. The solution was stirred at 15–18 °C for
24 h and partially concentrated until a yellow solid precipitated
which was filtered off, washed with cold methanol and dried in va-
cuo. Yield: 80% (0.88 g). Elem. Anal. Calc. for C23H18N3ClO (387.86):
C, 71.22; H, 4.68; N, 10.83. Found: C, 71.18; H 4.64; N, 10.75%. IR
(KBr, cmÀ1): 3220(w), 3149(w)
m(NH), 1678(m) m(CO), 1645(s)
m
(CNqui). 1H NMR (300 MHz, CDCl3): d/ppm 16.11 (s, 1H, NHqui),
3
12.48 (s, 1H, NH), 8.34 (d, JHH = 9.2 Hz, 1H, H6), 8.10–7.35 (m,
15H, aromatic). MS (FAB+): m/z 352.1 ([H2BQ]+, 100%).
A yellow solid identified as [H4BQ2]Cl2 was isolated by partial
evaporation of the mother liquor. 1H NMR (300 MHz, CDCl3): d/
3
ppm 16.42 (s, 2H, NHqui), 11.87 (s, 2H, NH), 8.17 (d, JHH = 9.4 Hz,
3
2H H6), 7.91 (d, JHH = 8.5 Hz, 2H, H9), 7.79–7.69 (m, 10H, aro-
matic), 7.58–7.45 (m, 8H, aromatic). MS (FAB+): m/z 493.1
([H3BQ2]+, 100%). Suitable crystals for X-ray diffraction were ob-
tained by slow evaporation of the mother liquor. This compound
was also obtained by direct reaction between benzil and two
equivalents of 2-hydrazinequinoline.
2.2. X-ray crystallography
Data for [H4BQ2]Cl2Á2CH3OH, [H3BTsQ]ClÁ2CH3OH, [H3-
BTsP]NO3Á2CH3OH and complexes 1 and 2ÁCH3OH were acquired
using a Bruker AXS Kappa Apex-II diffractometer equipped with
an Apex-II CCD area detector using a graphite monochromator
Under other conditions the reaction did not progress or a mix-
ture containing [H2BQ]Cl and [H4BQ2]Cl2 was obtained. If the reac-
tion was carried out at 0 °C or without conc. HCl the reagents were
recovered, and if the temperature was above 18 °C, [H4BQ2]Cl2 was
obtained as the major product.
(Mo Ka radiation, k = 0.71073 Å). The substantial redundancy in
data allows empirical absorption corrections (SADABS) [32] to be ap-
plied using multiple measurements of symmetry-equivalent
reflections. The raw intensity data frames were integrated with
the SAINT program, which also applied corrections for Lorentz and
polarization effects [33]. The software package SHELXTL version
6.10 was used for space group determination, structure solution
and refinement. The structures were solved by direct methods
2.3.4. Reaction of benzil with thiosemicarbazide
Attempts to synthesize the proligand derived from benzil with
thiosemicarbazide (HBTs) were unsuccessful: if the reactions were
carried out at low temperature the reagents were recovered;
increasing the temperature above 18 °C 6-methoxy-1,6-diphenyl-
4-thio-3,4,5,6-tetrahydro-2,3,5-triazine HBTsOCH3 [36] was
formed; different solvents were tested, such as water, methanol
and ethanol, obtaining the initial reactants or the triazine-3-thione
derivative; without acid the reactions did not progress.
(SHELXS-97) [34], completed with difference Fourier syntheses, and
refined with full-matrix least squares using SHELXL-97 minimizing
2
x
(F0 À Fc2). Weighted R factors (Rw) and all Goodness-of-fit S
are based on F2; conventional R factors (R) are based on F [35].
All non-hydrogen atoms were refined with anisotropic displace-
ment parameters. CH and OH hydrogen atoms, except OH in [H3-
BTsQ]ClÁ2CH3OH, were positioned geometrically after each cycle
of refinement. The NH in all the complexes and OH in [H3-
BTsQ]ClÁ2CH3OH were located in a difference Fourier map and their
coordinates and isotropic thermal parameters subsequently re-
fined. All scattering factors and anomalous dispersions factors are
contained in the SHELXTL 6.10 program library.
2.4. Synthesis of the hybrid ligands
2.4.1. [H3BTsP]Cl
A
solution of thiosemicarbazide (0.20 g, 2.19 mmol) in
methanol (35 mL) and conc. HCl (0.10 mL, 1.13 mmol) was added
to a solution of [H2BP]Cl (0.73 g, 2.16 mmol) and conc. HCl

D.G. Calatayud et al. / Polyhedron 54 (2013) 39–46
41
Ph
N
Ph
N
Ph
Ph
N4
Ph
N
Ph
O
NH2
H3
C4
C8
C3
C2
H2
C1
HN
Ph
MeOH
Ph
N
+
HN
NH
N3
N6
N5
N2
S1
H1a
HN
S
OCH3
19 ºC, 24 h
C5
C7
N1
H2N
+
Cl-
+
NH
Cl-
NH+
+HN
Cl-
Cl-
+
NH+
C6
C9
H6a
H1b
HN
S
C12
C10 C11
8 %
Scheme 1. Synthesis of [H3BTsQ]Cl including atom labeling scheme.
(0.20 mL, 2.27 mmol) in methanol (15 mL). The solution was stir-
red at room temperature for 24 h. The yellow solid formed was fil-
tered off, washed with methanol and dried in vacuo. Yield: 47%
(0.41 g). Elem. Anal. Calc. for C20H19N6SCl (410.92): C, 58.46; H,
4.66; N, 20.45; S, 7.80. Found: C, 58.36; H, 4.50; N, 20.40; S,
semicarbazide (0.14 g, 1.54 mmol) in methanol (30 mL) with conc.
HCl (0.18 mL, 2.04 mmol) was added. The solution was stirred at
19 °C for 24 h. Then a half of the solvent was evaporated and the
solution was kept at 4 °C until a yellow solid precipitated, which
was filtered off, washed with cold methanol and dichloromethane
and dried in vacuo. Yield: 8% (0.06 g). In the mother liquor HBTs-
OCH3 [36] and the symmetric open chain molecule [H4BQ2]Cl2
can be detected in high yields (Scheme 1). Recrystallization in
methanol gave single crystals suitable for X-ray diffraction. Elem.
Anal. Calc. for C24H21N6SCl (460.98): C, 62.53; H, 4.59; N, 18.23;
S, 6.96. Found: C, 62.45; H, 4.45; N, 18.20; S, 6.90%. IR (KBr,
7.75%. IR (KBr, cmÀ1): 3332(m), 3271(m), 3160(m)
1644(s), 1607(vs), 1555(m), 1532(w)
(CS). 1H NMR (300 MHz, DMSO-d6): d/ppm 11.69 (br s, 1H, H3),
m(NH),
m(CN + thioamide II), 839(w)
m
10.21 (s, 1H, H2), 8.63 (s, 1H, H1a), 8.38 (s, 1H, H1b), 8.30 (d,
3
3
3JHH = 5.6 Hz, 1H, H8), 8.12 (ddd, JHH = 8.7 Hz, JHH = 7.2 Hz,
4JHH = 1.3 Hz, 1H, H6), 7.91–7.76 (m, 4H, Ph), 7.53–7.35 (m, 7H,
H5 + Ph), 7.20 (t, JHH = 6.3 Hz, 1H, H7). 1H NMR (300 MHz, CDCl3):
cmÀ1): 3346(m), 3262(m), 3183(m)
1581(m), 1534(m) (CN + thioamide II), 851(w)
(300 MHz, DMSO-d6): d/ppm 10.07 (br s, 1H, H3), 8.66 (s, 1H, H2),
m
(NH), 1652(vs), 1618(s),
3
d/ppm 16.08 (s, 1H, H6a), 11.91 (s, 1H, H3), 8.60 (s, 1H, H2), 8.04 (t,
m
m
(CS). 1H NMR
3
3JHH = 7.8 Hz, 1H, H6), 7.92 (d, JHH = 9.0 Hz, 1H, H5), 7.85 (d,
3JHH = 5.9 Hz, 1H, H8), 7.82 (s, 1H, H1a), 7.73 (m, 4H, Ph), 7.54–
8.42 (s, 2H, H1a + H6), 8.18 (s, 1H, H1b), 8.04–7.78(m, 6H,
3
7.33 (m, 6H, Ph), 7.01 (t, JHH = 6.5 Hz,1H, H7), 6.60 (s, 1H, H1b).
H9 + H5 + Ph), 7.66–7.32 (m, 9H, H11 + H12 + H10 + Ph). 1H NMR
(300 MHz, CDCl3): d/ppm 16.03 (s, 1H, H6a), 12.31 (s, 1H, H3),
8.61 (s, 1H, H2), 8.37 (d, 3JHH = 9.4 Hz, 1H, H6), 8.00 (d, 3JHH = 9.4 Hz,
1H, H9), 7.92 (s, 1H, H1a), 7.88–7.73 (m, 7H, H5 + H11 + H12 + Ph),
13C NMR (300 MHz, DMSO-d6): d/ppm 179.8 (C1), 150.9 (C4),
146.0, 145.1 (C2 + C3), 141.6 (C8), 138.8 (C6), 133.5, 133.0, 131.1,
130.7, 129.4, 127.6, 127.3 (Ph), 116.6 (C7), 113.1 (C5). MS (ESI+):
m/z 375.1 [H3BTsP]+.
3
7.57–7.33 (m, 7H, H10 + Ph), 7.01 (t, JHH = 6.5 Hz,1H, H7), 6.60 (s,
1H, H1b). 13C NMR (300 MHz, DMSO-d6): d/ppm 179.5 (C1), 149.6
(C4), 143.8, 142.7 (C2 + C3), 133.4 (C6), 132.9 (C8), 131.7 (C11),
131.0 (C9), 129.6, 129.3, 127.7, 127.2 (Ph), 126.3 (C12), 123.1
(C10), 119.1 (C7), 113.4 (C5). MS (ESI+): m/z 425.2 [H3BTsQ]+.
2.4.2. [H3BTsQ]Cl
To a solution of [H2BQ]Cl (0.60 g, 1.55 mmol) in methanol
(35 mL) with conc. HCl (0.18 mL, 2.04 mmol), a solution of thio-
Ph
Ph
NH2
HN
+
HN
N
O
S
H2N
Cl-
NH+
MeOH
r.t., 24 h
Ph
Ph
C2
H3
C3
H2
C1
Ph
Ph
N
Ph
N
Ph
N3
N6
N5
N4
N2
S1
H1a
Cd(NO3)2.4H2O
MeOH, r.t., 48 h
Zn(NO3)2.6H2O
C5
C7
C4
C8
N1
N
N
HN
HN
N
N
Cl-
ONO2
NH
NO3
+
C6
H6a
H1b
Zn
Cl
EtOH, reflux, 24 h
NH2
Cd
N
S
S
H
NH2
O
O
Hg(NO3)2.H2O
EtOH, r.t., 24 h
N
O
[ZnCl(H2BTsP)]NO3
1
[Cd(H2BTsP)(NO3)2]
2
Ph
Ph
N
NH
N
HN
NO3
Hg
ONO2
NH2
S
N
Hg(H2BTsP)(NO3)]NO3
3
Scheme 2. Synthesis of [H3BTsP]Cl and its complexes, including atom labeling scheme.

42
D.G. Calatayud et al. / Polyhedron 54 (2013) 39–46
2.5. Synthesis of the complexes with [H3BTsP]Cl
3303(m), 3150(m)
1531(m) m(CN + thioamide II), 817(w) m
m
(NH), 1637(m), 1611(s), 1578(w), 1558(w),
(CS). 1H NMR (300 MHz,
All the reactions were carried out following the same general
procedure: a solution of 0.15 mmol of the corresponding metal ni-
trate in 2 mL of solvent was added over a solution of 0.15 mmol of
[H3BTsP]Cl in 20 mL of the same solvent. The particular conditions
of each reaction and yields are described below and are summa-
rized in Scheme 2.
DMSO-d6): d/ppm 11.50 (br s, 1H, H3), 10.07 (s, 1H, H2), 8.60 (s,
1H, H1a), 8.40 (s, 1H, H1b), 8.21 (s, 1H, H8), 8.06 (s, 1H, H6), 7.86
3
(m, 4H, Ph), 7.50–7.37 (m, 7H, H5 + Ph), 7.13 (t, JHH = 6.5 Hz, 1H,
H7). 13C NMR (300 MHz, DMSO-d6): d/ppm 179.7 (C1), 152.2 (C4),
143.9 (C2 + C3), 142.0 (C8), 140.1 (C6), 133.4, 133.1, 131.2, 130.8,
129.5, 129.4, 127.4, 127.3 (Ph), 116.7 (C7), 113.1 (C5). MS (ESI+):
m/z 487.0 [Cd(HBTsP)]+.
2.5.1. [ZnCl(H2BTsP)]NO3 (1)
2.5.3. [Hg(H2BTsP)(NO3)]NO3 (3)
The methanolic solution was stirred under reflux for 8 h, par-
tially concentrated and then cooled at 4 °C for 1 h. The orange crys-
tals formed, suitable for X-ray diffraction, were filtered off, washed
with cold methanol and dried in vacuo. Yield: 27% (22 mg). By con-
centration of the mother liquor pale-yellow crystals corresponding
to [H3BTsP]NO3 were formed. The compound could be obtained
with better yield (51%, 41 mg) in ethanol under reflux for 24 h
and keeping the resulting yellow solution at 4 °C. When the reac-
tion was carried out at room temperature only [H3BTsP]NO3 and
The ethanolic suspension was stirred at room temperature for
24 h. The scarce amount of solid was separated by filtration and
discarded. Then the solvent was removed under reduced pressure
leading to the obtaining of an oil. Diethyl ether was added to the
oil and stirred vigorously. The pale yellow solid formed was filtered
off and dried in vacuo. Yield: 54% (54 mg). If the reaction was car-
ried out at room temperature the reactants were recovered. Mp:
117 °C (decomposition). KM = 70.1
3272(m), 3147(m), 3138(sh) (NH), 1649(s), 1616(s), 1558(m),
1531(sh) (CN + thioamide II), 803(w)
(CS). 13C CP/MAS NMR
X
À1 cm2 molÀ1. IR (KBr, cmÀ1):
ZnCl2 were formed. Mp: 197 °C (decomposition). KM = 68.0 XÀ1
-
m
cm2 molÀ1. Elem. Anal. Calc. for ZnC20H18N7SO3Cl (537.33): C,
44.71; H, 3.38; N, 18.25; S, 5.97. Found: C, 44.48; H, 3.65; N,
18.10; S, 5.72%. IR (KBr, cmÀ1): 3357(m), 3261 (m), 3234(m),
m
m
(400 MHz): d/ppm 175.1 (C1), 149.8 (C4), 146.7, 144.2 (C2 + C3),
137.7 (C8 + C6), 132.9, 128.0 (Ph), 116.3 (C7), 113.3 (C5). MS
(ESI+): m/z 575.1 [Hg(HBTsP)]+.
3171(m)
amide II), 828(w)
10.52 (br s, 1H, H3), 9.64 (s, 1H, H2), 8.56 (s, 1H, H1a), 8.29 (s, 1H,
m
(NH), 1645(m), 1616(vs), 1574(m), 1557(m)
m(CN + thio-
m
(CS). 1H NMR (300 MHz, DMSO-d6): d/ppm
3. Results and discussion
H
1b), 8.07 (s, 1H, H8), 7.80 (s, 1H, H6), 7.69 (m, 2H, Ph), 7.58 (m,
2H, Ph), 7.39–7.26 (m, 7H, H5 + Ph), 6.92 (s, 1H, H7). 13C NMR
(300 MHz, DMSO-d6): d/ppm 179.5 (C1), 154.3 (C4), 143.5
(C2 + C3), 142.2 (C8), 141.6 (C6), 134.0, 133.7, 130.7, 130.3, 129.5,
129.3, 127.4, 126.6 (Ph), 116.6 (C7), 110.7 (C5). MS (ESI+): m/z
437.1 [Zn(HBTsP)]+.
3.1. Proligands
The synthesis of the proligand derived from benzil and thiosem-
icarbazide is hampered by the formation of the triazine-3-thione or
by the reagents recovery. Therefore, the strategy followed was to
prepare the proligands by reaction between benzil and the aro-
matic amines, 2-hydrazinepyridine and 2-hydrazinequinoline. Un-
like to the reactions with 2,3-butanedione, in which both neutral
or protonated forms of the proligands could be synthesized
[25,26], the reactions with benzil need the presence of conc. HCl,
leading to the protonation of the aromatic ring, so only [H2BQ]Cl
and [H2BP]Cl were obtained. In addition, in the reaction of benzil
with 2-hydrazinequinoline, which yields [H2BQ]Cl, the symmetric
ligand [H4BQ2]Cl2 is always obtained as a by-product.
2.5.2. [Cd(H2BTsP)(NO3)2] (2)
The methanolic solution was stirred at room temperature for
48 h, and then the solvent was removed under reduced pressure
to approximately 2 mL and cooled to -18 °C for 48 h. A yellow solid
was obtained, which was filtered off and dried in vacuo. Yield: 52%
(50 mg). Slow evaporation of the mother liquor gave crystals of the
complex, which were suitable for X-ray diffraction. Mp: 178 °C
(decomposition). KM = 20.2
X
À1 cm2 molÀ1. Elem. Anal. Calc. for
CdC20H18N8SO6 (610.88): C, 39.32; H, 2.97; N, 18.44; S, 5.25.
The analytical data of the proligands confirm the formation of
the chloride salts, and together with the mass spectra, support
Found: C, 39.40; H, 2.75; N, 18.76; S, 5.49%. IR (KBr, cmÀ1):
Table 1
Crystal data and structure refinement for [H4BQ2]Cl2Á2CH3OH, [H3BTsQ]ClÁ2CH3OH, [H3BTsP]NO3Á2CH3OH, 1 and 2ÁCH3OH.
[H4BQ2]Cl2Á2CH3OH
36H38N6O2Cl2
[H3BTsQ]ClÁ2CH3OH
C26H29N6SO2Cl
525.06
[H3BTsP]NO3Á2CH3OH
C22H27N7SO5
501.57
1
2ÁCH3OH
CdC21H22N8SO7
642.93
Formula
M
C
ZnC20H18N7SO3Cl
537.29
657.62
Crystal system
Space group
a (Å)
b (Å)
c (Å)
triclinic
triclinic
triclinic
triclinic
triclinic
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
P1
P1
P1
P1
P1
11.3486(8)
12.4388(10)
12.9475(96)
114.246(2)
97.638(3)
92.894(3)
1640.5(2)
2
1.331
0.241
692
1.049
9.933(3)
10.761(3)
13.235(4)
95.702(8)
100.324(9)
107.491(99
1309.6(7)
2
1.332
0.261
552
1.000
8.4180(6)
10.8682(8)
13.9949(9)
85.301(3)
76.974(3)
83.806(47)
1237.95(15)
2
1.346
0.178
528
1.087
9.2420(16)
11.732(2)
11.9014(18)
89.439(7)
70.885(6)
67.999(6)
1121.3(7)
2
1.592
1.346
548
1.030
10.5055(7)
10.8453(7)
11.9664(8)
92.044(3)
100.350(3)
111.510(3)
1240.10(14)
2
1.722
1.024
648
1.094
a
(°)
b (°)
c
(°)
U (Å3)
Z
Dcalc (MgmÀ3
)
Absorption coefficient (mmÀ1
F(000)
)
Goodness-of-fit (GOF) on F2
Reflections collected
40468
12520
62188
24501
46451
Independent reflections (Rint
Final R1 and wR2 [I > 2 (I)]
Residual electron density (min. max) (e ÅÀ3
)
7193 (0.0405)
0.0649, 0.1716
À0.658, 1.275
5310 (0.0518)
0.0441, 0.1043
À0.327, 0.292
7444 (0.0369)
0.0355, 0.0968
À0.357, 0.497
5749 (0.0354)
0.0400, 0.0936
À0.597, 0.861
63769 (0.0344)
0.0264, 0.0638
À0.878, 1.142
r
)

D.G. Calatayud et al. / Polyhedron 54 (2013) 39–46
43
Fig. 1. Molecular structure of one of the [H4BQ2]Cl2 molecules. Thermal ellipsoids at 50% probability. The solvent molecules have been omitted for clarity.
Table 2
Selected ligand bond distances in [H4BQ2]Cl2Á2CH3OH, [H3BTsQ]ClÁ2CH3OH, [H3BTsP]NO3Á2CH3OH, 1 and 2ÁCH3OH.
[H4BQ2]Cl2Á2CH3OH
[H3BTsQ]ClÁ2CH3OH
[H3BTsP]NO3Á2CH3OH
1
2ÁCH3OH
N(1)–C(1)
C(1)–S(1)
C(1)–N(2)
N(2)–N(4)
N(4)–C(2)
C(2)–C(3)
C(3)–N(5)
N(5)–N(3)
N(3)–C(4)
C(4)–N(6)
–
–
–
–
1.327(3)
1.678(3)
1.360(3)
1.377(3)
1.278(3)
1.504(4)
1.291(3)
1.371(3)
1.350(3)
1.334(3)
1.3200(13)
1.6824(11)
1.3612(14)
1.3702(12)
1.2889(14)
1.5000(14)
1.2919(13)
1.3663(12)
1.3567(13)
1.3389(14)
1.314(3)
1.712(3)
1.366(3)
1.351(3)
1.291(3)
1.492(4)
1.278(3)
1.339(3)
1.383(3)
1.349(3)
1.320(3)
1.694(2)
1.365(3)
1.357(2)
1.284(3)
1.481(3)
1.288(3)
1.343(2)
1.387(3)
1.341(3)
–
1.471(5)
1.289(3)
1.370(3)
1.350(3)
1.351(4)
the formation of the open chain [1 + 1] condensation products. The
IR spectra of the compounds show one band corresponding to the
carbonyl group, indicating that one of the two CO groups from the
starting diketone remains in the proligands, and additional bands
provided by the aromatic amines. The signals observed in their
1H NMR spectra confirm the presence of the amine groups and
the expected aromatic hydrogen atoms. The formation of the chlo-
ride salts is supported in the IR spectra by the appearance of one
new NH stretching vibration and the displacement of the signals
corresponding to the pyridine or quinoline ring, as well as by the
additional NH signal observed in the 1H NMR spectra.
monoketones about 1700–1665 cmÀ1 and the presence of more
bands between 3346–3160 cmÀ1 corresponding to the N-H
stretching vibrations, together with the thioamide bands, confirm
the formation of the hybrid ligands. The changes produced by the
protonation of the aromatic nitrogen can be clearly observed, in
particular by the presence of a new signal between 1644 and
1652 cmÀ1. The 1H NMR spectra were registered in DMSO-d6 and
CDCl3 in which the H6a hydrogen can be clearly observed, confirm-
ing the protonation of the heteroaromatic ring. The 1H NMR spec-
tra with some drops of D2O were also recorded for the
unambiguous assignment of the acidic hydrogens. Schemes 1 and
2 show the numeration scheme used in the assignment of the sig-
nals. 13C NMR spectra of both ligands show the absence of the cor-
responding ketone carbon, confirming the formation of the double
Schiff-bases. Moreover, the presence of one signal over 176 ppm
corresponding to the CS group, signals corresponding to the CN
groups between 158 and 145 ppm and several signals correspond-
ing to the aromatic carbons, support the formation of the hybrid
ligands.
3.2. Dissymmetric ligands
The hybrid thiosemicarbazone ligands containing 2-hydrazone-
pyridine and 2-hydrazonequinoline arms were obtained in the pro-
tonated forms by reaction of thiosemicarbazide with the
corresponding protonated proligand in the presence of hydrochlo-
ric acid. The reaction with the pyridine-containing proligand
yielded the desired dissymmetric ligand in a reasonable yield.
However, the quinoline derivative is only obtained as a by-product
in a reaction in which the symmetric ligand [H4BQ2]Cl2 and the tri-
azine-3-tione HBTsOCH3 are the major compounds (Scheme 1).
The mass spectra of the ligands show the peaks corresponding
to [M]+, confirming the formation of the open chain [1 + 2] hybrid
ligands, as well as other peaks corresponding to successive frag-
3.3. Complexes
Analytical data of complexes 1 and 2 confirm the 1:1 stoichiomÀ-
etry. In addition, data of complex 1 show the presence of a NO3
group and suggest substitution of the other nitrate by a chloride,
and therefore that the ligand is a neutral donor. Nevertheless, ana-
lytical data of complex 2 show the presence of two nitrate groups,
mentations. The absence in the spectra of the m(CO) of the starting

44
D.G. Calatayud et al. / Polyhedron 54 (2013) 39–46
m
(CN) shows coordination of these groups tÀo the metal. Moreover,
a band at 1385 cmÀ1 corresponding to NO3 can be observed. The
1H NMR spectra of complexes 1 and 2 show two signals corre-
sponding to the acidic hydrogen atoms, confirming that the ligand
behaves as a neutral donor. It was not possible the acquisition of a
well-resolved spectrum for complex 3 in any solvent, probably due
to its decomposition in solution. 13C NMR spectra of complexes 1
and 2 were recorded in solution, while for complex 3 it was ac-
quired in the solid state. In spite of these data do not clearly sup-
port the N3S coordination of the ligand, it could be confirmed in
the crystal structure determination of complexes 1 and 2. Taking
into account the data obtained by different techniques and the
structures found in related complexes [25,26], in the structure pro-
posed for complex 3 the mercury atom is bounÀd to one neutral tet-
radentate ligand and one monodentate NO3 in the apex of a
square-base pyramid with one nitrate as counterion.
3.4. X-ray diffraction
Crystallographic and refinement data are summarized in Ta-
ble 1. Full lists of bond lengths and angles, as well as the hydrogen
bond tables, are in the Supplementary data. The molecule [H4BQ2]-
Cl2Á2CH3OH crystallizes in the triclinic system. The asymmetric
unit of the compound is formed by two crystallographically differ-
ent half molecules, which grow by symmetry to give two [H4BQ2]-
Cl2 molecules (Fig. 1). There are not important differences in the
bond distances and angles in both molecules, so only selected bond
distances of one of them are shown in Table 2. The dihedral angles
of the phenyl rings with respect to the quinoline arms are around
60°. The N–N distances are shorter than 1.44 Å and the azomethine
C@N bond lengths are likewise short enough to imply a partial
double bond. The chloride ions are linked to the ligands by hydro-
Fig. 2. Molecular structure of [H3BTsQ]ClÁ2CH3OH. Thermal ellipsoids at 50%
probability.
so the ligand is also neutral. Conductivity measurements in DMF
show complex 2 is a molecular species, while complexes 1 and 3
are 1:1 electrolytes [37]. Mass spectra show a peak corresponding
to [M(HBTsP)]+, supporting the 1:1 stoichiometry and the calcu-
lated and theoretical isotopic splitting patterns are identical. In
gen bonds with N(3), N(6), N(7) and N(9), and there are p–p inter-
actions between the quinoline rings leading a 3D structure.
The crystal structure of [H3BTsQ]Cl is made up by one [H3BTsQ]+
cation, one chloride and two methanol molecules (Fig. 2), linked by
hydrogen bonds (see ESI). The compound is in the thione form,
the IR spectra, the shift of the bands corresponding to m(CS) and
Fig. 3. Molecular structure of [H3BTsP]NO3Á2CH3OH. Thermal ellipsoids at 50% probability. The solvent molecules have been omitted for clarity.

D.G. Calatayud et al. / Polyhedron 54 (2013) 39–46
45
Table 3
which is supported by the C(1)–S(1) bond distance (Table 2) and
Selected bond distances (Å) and angles (°) in complexes 1 and 2ÁCH3OH.
the presence of the hydrazinic hydrogen H(2). The azomethine
C@N bonds are 1.278(3) and 1.291(3) Å, which are in agreement
with double bonds and the N–N bonds are shorter than 1.44 Å,
which agrees well with those of similar thiosemicarbazones. The
two arms of the molecule are at the same side of the C(2)–C(3)
bond, probably due to the formation of hydrogen bonds with the
solvent molecules and the ClÀ ions, and the conformation around
the C(1)–N(2) is E. N(2) forms hydrogen bonds with the S(1) of a
neighbor molecule, giving dimers that are linked through double
1
2ÁCH3OH
M(1)–S(1)
M(1)–N(4)
M(1)–N(5)
M(1)–N(6)
2.3669(8)
2.149(2)
2.157(2)
2.088(2)
2.5469(6)
2.4236(17)
2.4106(16)
2.3261(19)
–
M(1)–Cl(1)
2.2951(9)
M(1)–O(1)
M(1)–O(4)
M(1)–O(6)
–
–
–
2.3659(16)
2.4174(15)
2.6625(16)
68.63(6)
132.93(6)
64.80(6)
152.50(4)
138.79(4)
74.48(4)
–
N(6)–M(1)–N(5)
N(6)–M(1)–N(4)
N(5)–M(1)–N(4)
N(6)–M(1)–S(1)
N(5)–M(1)–S(1)
N(4)–M(1)–S(1)
N(6)–M(1)–Cl(1)
N(4)–M(1)–Cl(1)
N(5)–M(1)–Cl(1)
Cl(1)–M(1)–S(1)
N(6)–M(1)–O(6)
O(1)–M(1)–O(6)
N(5)–M(1)–O(6)
O(4)–M(1)–O(6)
N(4)–M(1)–O(6)
S(1)–M(1)–O(6)
O(1)–M(1)–N(5)
N(6)–M(1)–O(4)
O(1)–M(1)–O(4)
N(5)–M(1)–O(4)
O(1)–M(1)–N(4)
N(6)–M(1)–O(1)
O(4)–M(1)–N(4)
O(1)–M(1)–S(1)
O(4)–M(1)–S(1)
74.97(8)
139.74(9)
71.05(8)
117.99(6)
144.57(6)
81.29(6)
105.74(6)
102.41(8)
p–p interactions between the quinoline rings (distance between
centroids 3.667 Å) and an extended network of hydrogen bonds
involving N(1), N(3), N(6), the chloride ions and the solvent mole-
cules, leading to the formation of a 3D network.
As it was previously described, in the reaction of [H3BTsP]Cl
with Zn(NO3)2.6H2O, crystals in which the chloride present in the
free ligand was replaced by a nitrate were obtaiÀned. The crystal
structure consists on a [H3BTsP]+ cation, one NO3 anion and two
methanol molecules (Fig. 3). As the ligand [H3BTsQ]Cl, it is in the
imine-thione form, although with some electronic delocalization
(Table 2), and the conformation around C(1)–N(2) is E. Both thio-
semicarbazone and hydrazonepyridine limbs are almost planar
with a dihedral angle of 82.22°. This disposition is very close to
the one found in [H3BTsQ]Cl. There is an extended network of
hydrogen bonds between the amine groups, the sulfur atom, the
nitrate group and the methanol molecules, giving rise to a tridi-
mensional structure.
In complexes 1 and 2ÁCH3OH the ligand behaves as a N3S che-
late, leading to the formation of three five-member chelate rings
that confers high stability. The asymmetric unit of complex 1 is
made up by a [ZnCl(H2BTsP)]+ cation and one nitrate as counterion
(Fig. 4, Table 3). The zinc is penta-coordinate by one neutral ligand
occupying the base of a square-base pyramid (sbp) with the chlor-
–
–
–
103.03(7)
104.22(3)
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
81.67(5)
141.68(5)
122.74(4)
50.25(5)
130.10(6)
79.22(4)
88.24(6)
80.80(6)
164.67(5)
76.70(5)
81.18(6)
91.10(6)
94.78(6)
91.75(5)
101.46(4)
Complex [Cd(H2BTsP)(NO3)2] 2 crystallizes with one methanol
molecule. The cadmium is hepta-coordinated to one N3S neutral li-
gand, one monodentate and one bidentate nitrato groups in a
capped octahedral environment (Fig. 5). As can be observed in Ta-
ble 3, the bidentate nitrato group exhibits a significant asymmetry,
ido in the apex, with
s = 0.081 (s = 0 for sbp and s = 1 for trigonal
bipyramid) [38]. The ligand is slightly buckled with the sulfur
0.039 Å under the least-square plane defined by C(1)–N(2)–N(4)–
C(2)–C(3)–N(5)–N(3)–C(4)–N(6), and with the Zn 0.546 Å above
the same plane. There is a hydrogen bond between N(3) and
Cl(1) of a neighboring molecule, giving rise to the formation of di-
mers that are linked by hydrogen bonds between N(1) and N(2)
with the oxygen atoms of the nitrate group, leading to infinite
chains running along the (1,0,À1) direction.
Fig. 4. Molecular structure of [ZnCl(H2BTsP)]NO3. Thermal ellipsoids at 50%
probability.
Fig. 5. Molecular structure of [Cd(H2BTsP)(NO3)2]ÁCH3OH. Thermal ellipsoids at 50%
probability. The solvent molecule has been omitted for clarity.

46
D.G. Calatayud et al. / Polyhedron 54 (2013) 39–46
À
as is usually observed in cadmium complexes with NO3 as a li-
gand [39]. To difference to complex 1, the ligand is significantly
buckled. The [Cd(H2BTsP)(NO3)2] units are linked through hydro-
gen bonds between all the NH and the nitrate groups, leading
sheets in the ac plane.
References
[1] J.S. Casas, M.S. García-Tasende, J. Sordo, Coord. Chem. Rev. 209 (2000) 197.
[2] D.X. West, S.B. Padhey, P.B. Sonawane, Struct. Bonding 76 (1991) 1.
[3] T.S. Lobana, R. Sharma, G. Bawa, S. Khanna, Coord. Chem. Rev. 253 (2009) 977.
[4] D.X. West, A.E. Liberta, S.B. Padhey, R.C. Chitake, P.B. Sonawane, A.S. Kumbar,
R.G. Yerade, Coord. Chem. Rev. 123 (1993) 49.
[5] R. Noto, F. Buccheri, G. Cusmano, M. Gruttadauria, G. Werber, J. Heterocycl.
Chem. 33 (1996) 863.
4. Conclusions
[6] H. Beraldo, D. Cambino, Mini-Rev. Med. Chem. 4 (2004) 31.
[7] M.C. Rodríguez-Arguelles, P. Touron-Touceda, R. Cao, A.M. García-Deibe, P.
Pelagatti, C. Pelizzi, F. Zani, J. Inorg. Biochem. 103 (2009) 35.
[8] M.C. Rodríguez-Arguelles, E.C. López-Silva, J. Sanmartín, P. Pelagatti, F. Zani, J.
Inorg. Biochem. 99 (2005) 2231.
[9] D.C. Greenbaum, Z. Mackey, E. Hansell, P. Doyle, J. Gut, C.R. Caffrey, J. Lehrman,
P.J. Rosenthal, J.H. McKerrow, K. Chibale, J. Med. Chem. 47 (2004) 3212.
[10] N. Fujii, J.P. Mallari, E.J. Hansell, Z. Mackey, P. Doyle, Y.M. Zhou, J. Gut, P.J.
Rosenthal, J.H. McKerrow, R.K. Guy, Bioorg. Med. Chem. Lett. 15 (2005) 121.
[11] D.X. West, C.S. Carlson, A.C. Whyte, Transition Met. Chem. 15 (1990) 43.
[12] D.X. West, I. Thientanavanich, A.E. Liberta, Transition Met. Chem. 20 (1995)
303.
Reaction of 2,3-diphenylethanedione with 2-hydrazinequino-
line or 2 hydrazinepyridine in the presence of hydrochloric acid
yielded the corresponding Schiff base with one carbonyl group
ready to a second condensation reaction with thiosemicarbazide,
leading to the obtaining of two new hybrid ligands as the corre-
sponding chloride salts.
The pyridine derivative could be obtained with a reasonable
yield, while the quinoline derivative was obtained as a by-product
in a reaction yielding the benzil bis(2-hydrazidequinolinium) chlo-
ride salt and the corresponding triazine-3-thione.
[13] B.M. Paterson, J.A. Karas, D.B. Scanlon, J.M. White, P.S. Donnelly, Inorg. Chem.
49 (2010) 1884.
[14] P.D. Bonnitcha, S.R. Bayly, M.B.M. Theobald, H.M. Betts, J.S. Lewis, J.R. Dilworth,
J. Inorg. Biochem. 104 (2010) 126.
Reaction of [H3BTsP]Cl with group 12 nitrates lead to the forma-
tion of three new metal complexes in which the ligand coordinates
as a neutral tetradentate chelate. In the zinc derivative the coordi-
nation sphere is completed by a chlorido provided by the ligand in
the apex of a square-base pyramid. The cadmium complex contains
two nitrato groups, one monodentate and one bidentate giving rise
to a capped octahedron. The mercury complex could not be crystal-
lographically characterized but we propose a structure similar to
the one described for complex 1 in which the chloride was re-
placed by a monodentate nitrato group, which is analogous to
other complexes structurally characterized with related ligands.
[15] A.L. Vavere, J.S. Lewis, Dalton Trans. (2007) 4893.
[16] B.M. Paterson, P.S. Donnelly, Chem. Soc. Rev. 40 (2011) 3005. and references
therein.
[17] J.R. Dilworth, R. Hueting, Inorg. Chim. Acta 389 (2012) 3.
[18] M. Christlieb, J.R. Dilworth, Chem. Eur. J. 12 (2006) 6194.
[19] L.J. Ackerman, P.E. Fanwick, M.A. Green, E. John, W.E. Running, J.K. Swearingen,
J.W. Webb, D.X. West, Polyhedron 18 (1999) 2759.
[20] J.K. Lim, C.J. Mathias, M. Green, J. Med. Chem. 40 (1997) 132.
[21] A. Roth, A. Buchholz, M. Rudolph, E. Schütze, E. Kothe, W. Plass, Chem. Eur. J. 14
(2008) 1571.
[22] A.R. Cowley, J.R. Dilworth, P.S. Donelly, J.M. White, Inorg. Chem. 45 (2006) 496.
[23] L. Alsop, A.R. Cowley, J.R. Dilworth, P.S. Donnelly, J.M. Peach, J.T. Rider, Inorg.
Chim. Acta 358 (2005) 2770.
[24] M. Christlieb, H.J. Claughton, E.R. Cowley, J.M. Heslop, J.R. Dilworth, Transition
Met. Chem. 31 (2006) 88.
[25] D.G. Calatayud, E. López-Torres, J.R. Dilworth, M.A. Mendiola, Inorg. Chim. Acta
381 (2012) 150.
[26] D.G. Calatayud, E. López-Torres, M.A. Mendiola, Eur. J. Inorg. Chem. (2013) 80.
[27] E. López-Torres, M.A. Mendiola, C.J. Pastor, B. Souto Pérez, Inorg. Chem. 43
(2004) 5222.
Acknowledgements
We thank César J. Pastor from ‘‘Servicio Interdepartamental de
Investigación’’ (SidI) of the Universidad Autónoma de Madrid
(Spain) for the crystal measurements. We also thank MINECO,
Instituto de Salud Carlos III, for funding (Project PS09/00963).
[28] D.G. Calatayud, E. López-Torres, M.A. Mendiola, C.J. Pastor, J.R. Procopio, Eur. J.
Inorg. Chem. (2005) 4401.
[29] E. López-Torres, M.A. Mendiola, Inorg. Chim. Acta 363 (2010) 1735.
[30] D.G. Calatayud, E. López Torres, M.A. Mendiola, Polyhedron 27 (2008) 2277.
[31] D.G. Calatayud, E. López Torres, M.A. Mendiola, Inorg. Chem. 46 (2007) 10434.
[32] G.M. Sheldrick, SADABS Version 2.03, Program for Empirical Absorption
Corrections, Universität Göttingen, Göttingen, Germany, 1997–2001.
[33] G.M. Sheldrick, SAINT+NT, Version 6.04, SAX Area-Detector Integration Program,
Bruker AXS, Madison, WI, 1997–2001.
[34] G.M. Sheldrick, SHELXTL, Version 6.10, Structure Determination Package, Bruker
AXS, Madison, WI, 2000.
[35] G.M. Sheldrick, Acta Crystallogr., Sect. A 46 (1990) 467.
[36] M.A. Blanco, E. López-Torres, M.A. Mendiola, E. Brunet, M.T. Sevilla,
Tetrahedron 58 (2002) 1525.
[37] W.J. Geary, Coord. Chem. Rev. 7 (1971) 81.
[38] A.W. Addison, T.N. Rao, J. Reedijk, J. Van Rijn, G.C. Verschoor, J. Chem. Soc.,
Dalton Trans. (1984) 1349.
[39] A. Tamayo, E. Oliveira, B. Covelo, J. Casabó, L. Escrische, C. Lodeiro, Z. Anorg.
Allg. Chem. 633 (2007) 1809.
Appendix A. Supplementary material
CCDC 908407–908411 contain the supplementary crystallo-
graphic data for [H3BTsQ]ClÁ2CH3OH, [H4BQ2]Cl2Á2CH3OH, [H3-
BTsP]NO3,
1
and 2ÁCH3OH respectively. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336
033; or e-mail: deposit@ccdc.cam.ac.uk. Supplementary data asso-
ciated with this article can be found, in the online version, at
http://dx.doi.org/10.1016/j.poly.2013.02.025.