Chlorodiphenyltin(IV) dithiocarbamate complexes as chemodosimeters and host for anions and neutral compounds in solution

Article abstract of DOI:10.1016/j.poly.2016.03.035

The chlorodiphenyltin(IV) dithiocarbamate complexes 1-5 with general formula {(Ph₂SnCl)dtc} (dtc = R₁R₂NCS₂^-; 1, R₁ = Bn, R₂ = 9-anthrylmethyl; 2, R₁ = Bn, R₂

Full text of DOI:10.1016/j.poly.2016.03.035

Polyhedron 111 (2016) 132–142
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Polyhedron
journal homepage: www.elsevier.com/locate/poly
Chlorodiphenyltin(IV) dithiocarbamate complexes as chemodosimeters
and host for anions and neutral compounds in solution
Ámbar Yuricsi Castrejón-Antúnez, Miriam Mendoza-Mendoza, Diana Iris Olea-López, Felipe Medrano,
⇑
Hugo Tlahuext, Jorge Guerrero-Álvarez, Gabriela Vargas-Pineda, Carolina Godoy-Alcántar
Centro de Investigaciones Químicas, IICBA, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, C.P. 62209 Cuernavaca, Morelos, Mexico
a r t i c l e i n f o
a b s t r a c t
Article history:
The chlorodiphenyltin(IV) dithiocarbamate complexes 1–5 with general formula {(Ph2SnCl)dtc}
(dtc = R1R2NCSꢀ2 ; 1, R1 = Bn, R2 = 9-anthrylmethyl; 2, R1 = Bn, R2 = 9-phenanthrylmethyl; 3, R1 = Bn,
R2 = 1-pyrenylmethyl; 4, R1 = 1-naphthylmethyl, R2 = 1-pyrenylmethyl; 5, R1 = R2 1-pyrenylmethyl) have
been tested as host for anions and neutral amines in acetonitrile by spectrophotometric UV/Vis titrations.
In addition, the titrations of the complexes 1 and 5 were studied in chloroform by 1H and 119Sn NMR spec-
troscopy. It was found that anions as acetate, benzoate, and dihydrogen phosphate cause a displacement
of the dithiocarbamate ligands of metallic center independently of the aromatic nature of the sub-
stituents on the nitrogen atom functioning as chemodosimeters in which the indicator is displaced.
However, some aliphatic amines and aromatic methylene amines and its aromatic analogs can act as
guests with binding constants in the range of 103 to 106 Mꢀ1. Also, in these cases compound 5 functions
as chemodosimeter without displacement of the indicator. According to 1H, 13C, 119Sn NMR data and
using DFT (B3LYP) and Poisson–Boltzmann (PB) to model the solvent, structures of the complexes are
Received 18 November 2015
Accepted 18 March 2016
Available online 25 March 2016
Keywords:
Dithiocarbamate
Organotin complexes
Anion binding
Aromatic compounds
Chemodosimeters
proposed in which the hydrophobic and
p
–
p
interactions are suggested as the dominant interactions.
Ó 2016 Elsevier Ltd. All rights reserved.
1. Introduction
been previously examined for ion recognition including macrocy-
cles, cryptand-like and calixarene shaped receptor [8,9]. An impor-
tant class of compounds is mono-, di-, and triorganotin
dithiocarbamates, which have been studied in solution and by sin-
gle-crystal X-ray diffraction analysis [10]. The uses and potential
utility of these compounds have been reviewed by Tiekink [11].
We have reported the spectroscopic and structural characteriza-
tion of dinuclear diorganotin(IV) dithiocarbamate macrocycles, as
well as trinuclear diorganotin cavitands and capsules, which have
been prepared from bis- and tris-dithiocarbamate ligands and
diorganotin(IV) dichlorides [12]. A further study has shown that
diorganotin dithiocarbamates are chromogenic sensors for anion
recognition [13]. In this contribution, we present the study of the
chlorodiphenyltin(IV) dithiocarbamate complexes 1–5 (Scheme 1),
as host for anions (CH3COꢀ2 , H2PO4ꢀ, HSO4ꢀ, C6H5COꢀ2 ) and neutral
amines (Scheme 2). The chlorodiphenyltin(IV) dithiocarbamate
complexes 1–5 were derived from benzyl(9-anthrylmethyl)amine,
Nowadays, there is a general interest in the design of molecular
systems (receptors) capable to selectively interact with ion or neu-
tral molecules [1]. Anions, cations, and neutral molecules can be
selectively recognized by either positively charged or neutral arti-
ficial receptors. At this respect, anions typically form complexes
with metal ions, whose stability may vary depending upon the
electronic features of the ligand and of the metal center. The metal
provides a binding site and the selectivity could be associated with
the geometrical and steric characteristics of ligand, in which the
metal is incorporated [2]. In the last years, the well-known dithio-
carbamate ligands (R2NCS2) [3] have received attention in
supramolecular chemistry. Beer and co-workers have successfully
employed dithiocarbamate of transition metal ions and shown that
they can function as receptors for a variety of cationic, anionic, and
neutral species [4]. In addition, calix [5] arenes [5], zinc–calix [6]
arene complexes [6] and bis-dithiocarbamate complexes of zinc
(II) [7] have been used as selective receptors for amine compounds.
Compounds containing tin(IV) as an electrodeficient center have
benzyl(9-phenanthrylmethyl)amine,
benzyl(1-pyrenylmethyl)
amine, 1-naphthylmethyl(1-pyrenylmethyl)amine and di(1-
pyrenylmethyl)amine (Scheme 1) [14]. The obtained complexes
contain polyaromatic rings that can act as fluorescent or colorimet-
ric reporters and a tin(IV) metal center (capable of act as Lewis
acid) as anion binding site. Therefore, these molecules can function
⇑
Corresponding author. Tel./fax: +52 (777) 329 7997.
E-mail address: cga@uaem.mx (C. Godoy-Alcántar).
http://dx.doi.org/10.1016/j.poly.2016.03.035
0277-5387/Ó 2016 Elsevier Ltd. All rights reserved.

Á.Y Castrejón-Antúnez et al. / Polyhedron 111 (2016) 132–142
133
R1
R2
1
2
3
Cl
Ph
Ph
S
Sn
R1
S
N
R2
4
5
Scheme 1. Chemical structures of the chlorodiphenyltin(IV) dithiocarbamate complexes 1–5 investigated as host herein.
as chemosensors for anions or neutral guests. This hypothesis was
explored by means of spectrophotometric titrations in solution.
Additionally, the structure of the host–guest complexes was inves-
tigated by 1H and 139Sn NMR titrations and DFT quantum chem-
istry method.
amines 1-naphthylmethyl(1-pyrenylmethyl)amine and di(1-pyrenyl-
methyl)amine were carried out by condensation of
pyrenecarboxaldehyde, with 1-naphthylmethylamine and
1-pyrenylmethylamine by heating under reflux in ethanol followed
by Schiff bases reduction with NaBH4 [15]. The sodium dithiocar-
bamate salts were prepared by treating of the secondary amines
with carbon disulfide and sodium hydroxide in methanol [16].
The subsequent addition of diphenyltin dichloride leading to the
corresponding chlorodiphenyltin(IV) dithiocarbamate complexes
[14]. The NMR studies were carried out with Varian Inova 400
instruments. Chemical shifts (dH and dSn) are given in ppm. Stan-
dard references were used: TMS (dH = 0) and SnMe4 (d 119Sn = 0).
The electronic absorption spectra were recorded at 25 °C on a
Hewlet–Packard 8452A diode array spectrophotometer.
2. Experimental
2.1. General procedures and methods
Ph2SnCl2 was commercially available and was used without fur-
ther purification. The synthesis of benzyl(9-anthrylmethyl)amine,
benzyl(9-phenanthrylmethyl)amine and benzyl(1-pyrenylmethyl)
amine were carried out by condensation of 9-anthracenecarbox-
aldehyde, 9-phenanthrenecarboxaldehyde and 1-pyrenecarbox-
aldehyde with benzylamine by heating under reflux in ethanol
followed by Schiff bases reduction with NaBH4. The secondary
For titration experiments the tetrabutylammonium (TBA) salts
of hydrogen sulfate, dihydrogen phosphate and acetate were used.
The neutral compounds: benzylamine, 1-naphtylmethylamine
1-pyrenemethylamine, isobutylamine, n-butylamine, benzene,

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Á.Y Castrejón-Antúnez et al. / Polyhedron 111 (2016) 132–142
NH2
NH2
NH2
NH2
NH2
Scheme 2. Chemical structures of the aromatic amines, aromatic compounds, and aliphatic amines used as neutral guests in this work.
12000
10000
CH3COOTBA
H2PO4TBA
HSO4TBA
C6H5COOTBA
8000
6000
4000
2000
0
-1
0
1
2
3
4
5
6
7
8
9
10 11
[anion]/[1]
Fig. 1. Changes in absorption coefficient at 302 nm during the titration of 1 (7 ꢁ 10ꢀ5 M) with different anions as TBA (tetrabultylammonium) salts in CH3CN.
naphthalene, and pyrene were commercially available and were
used without further purification. Tetrabutylammonium benzoate
salt was prepared in situ by mixing the benzoic acid (1 ꢁ 10ꢀ2 M)
in acetonitrile with stoichiometric addition of tetrabutylammo-
nium hydroxide solution (40% in methanol). Stock solutions were
prepared freshly to carry out all titration experiments.
C6H5COꢀ2 , as TBA salts) were added to the chlorodiphenyltin(IV)
dithiocarbamate complex solutions. The concentration of hosts: 1
(7 ꢁ 10ꢀ5 M), 2 and 3 (3 ꢁ 10ꢀ5 M), 4 and 5 (2 ꢁ 10ꢀ5 M), the spec-
trums were recorded after each addition. The spectral changes
were corrected by dilution effect and by the absorbance of the
guest and plotted versus the ratio [guest]/[host] in the case of
anion guests. In the case of neutral guests the absorbance corrected
was plotted versus the guest concentration for fitting the experi-
mental points and calculate the binding constants.
2.2. UV/Vis titrations
The experimental data were fitted using non-linear least-
squares regression with Microcal Origin 5 program.
The titrations were performed at 25 °C in acetonitrile. Aliquots
of 1 ꢁ 10ꢀ2 M solution of the guest (CH3COꢀ2 , H2PO4ꢀ, HSOꢀ4 ,

Á.Y Castrejón-Antúnez et al. / Polyhedron 111 (2016) 132–142
135
12000
10000
8000
6000
4000
2000
0
CH3COOTBA
H2PO4TBA
HSO4TBA
C6H5COOTBA
0
5
10
15
20
25
30
35
40
[anion]/[4]
Fig. 2. Changes in absorption coefficient at 300 nm during the titration of 4 (2 ꢁ 10ꢀ5 M) with different anions as TBA salts in CH3CN.
15000
10000
CH3COOTBA
H2PO4TBA
HSO4TBA
C6H5COOTBA
5000
0
0
10
20
30
[anion]/[5]
Fig. 3. Changes in absorption coefficient at 300 nm during the titration of 5 (2 ꢁ 10ꢀ5 M) with different anions as TBA salts in CH3CN.
2.3. 1H NMR titrations
lamine was calculated by computational chemistry methods
according to a protocol described by Buntine et al. [17], which
has been successfully used by other authors to calculate dithiocar-
bamate organotin(IV) complexes and alkyl tin compounds [18].
Density functional theory (DFT) calculations were done with Jaguar
code [19] using the well known Becke–Lee–Yang–Parr three
parameters (B3LYP) hybrid functional [20] with LANL effective core
(ECP) for Sn and 6-311G⁄⁄ is set for other atoms implemented as
pseudospectral LACV3P⁄⁄ in Jaguar. All the calculations were done
in chloroform using a Poisson–Boltzmann model [21] in which the
solvent is represented as layer of charges at the molecular surface
(which serves as a dielectric continuum).
The solutions of guests and chlorodiphenyltin(IV) dithiocarba-
mate complex were prepared in CDCl3. The 1H NMR titrations were
carried out by adding aliquots of the guest stock solutions prepared
at maximum possible concentrations allowed by their solubilities
to 1 ꢁ 10ꢀ2 M of dithiocarbamate complex.
2.4. Computational details
The molecular structure of complexes 5-pyrene, 5-1-pyren-
emethylamine, 5-benzylamine, 5-n-butylamine, and 1-n-buty-

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2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
200 220 240 260 280 300 320 340 360 380 400
200 220 240 260 280 300 320 340 360 380 400
λ (nm)
λ (nm)
a
b
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
220
240
260
280
300
320
340
360
380
400
λ (nm)
c
Fig. 4. Typical UV/Vis titration spectra of 5 (2 ꢁ 10ꢀ5 M) with (a) benzylamine (b) n-butylamine and (c) naphthalene in CH3CN at 25 °C. In each plot the lines in almost 0.0 a.u.
corresponds to the spectrum of the lower and higher concentration of free amine used in the titration experiment.
3. Results and discussion
Table 1
Binding constants of 5 to neutral guest in CH3CN at 25 °C obtained by spectropho-
tometric titrations.a
The chlorodiphenyltin(IV) dithiocarbamate complexes 1–5
(Scheme 1) were synthesized and characterized previously by
our group [14]. In this communication, we would like to report
the use of these compounds as hosts for anions (CH3COꢀ2 , H2PO4ꢀ,
HSOꢀ4 , C6H5COꢀ2 ) and amine guests (Scheme 2) using acetonitrile
(UV/Vis spectroscopy) and chloroform (1H and 119Sn NMR spec-
troscopy) as solvents.
Guest
K or K11 (Mꢀ1
)
Benzene
Naphtalene
Pyrene
3.1 ꢁ 104 2.7 ꢁ 103
1.5 ꢁ 105 2.1 ꢁ 104
K11: 8.3 ꢁ 105 1.4 ꢁ 105
K12: ꢂ20b
Benzyl amine
K11 = 1.4 ꢁ 104 4.9 ꢁ 103
K12 = 3.5 ꢁ 105 1.2 ꢁ 105b
3 ꢁ 104 2.9 ꢁ 103
1-Naphtylmethyl amine
1-Pyrenemethylamine
n-Butylamine
2.2 ꢁ 106 9.3 ꢁ 104
K11 = 6.7 ꢁ 104 9.3 ꢁ 103
K12 = 1.6 ꢁ 105 4.9 ꢁ 103b
4.6 ꢁ 103 3.6 ꢁ 102c
4.7 ꢁ 103 3.0 ꢁ 102c
2.3 ꢁ 103 2.3 ꢁ 102d
3.1. UV/Vis titrations
The aromatic nature of the substituents on the nitrogen atom
give to the chlorodiphenyltin(IV) dithiocarbamate complexes
(1–5) an electronic spectrum with characteristic bands in the range
Isobutylamine
of 200 to 400 nm that can be ascribed to p–
p⁄ and n-p⁄ transitions
a
No interaction was detected for dithiocarbamates 1, 2, and 3 with the aromatic
[14]. Figs. 1–3 show the absorptivity change as a function of ratio
[anion]/[complex] for chlorodiphenyltin(IV) dithiocarbamate
amines tested.
K12 (Mꢀ2).
b
c
complexes 1,
4 and 5, respectively, as typical examples;
Binding constant for complex 1.
Binding constant for complex 2.
d
chlorodiphenyltin(IV) dithiocarbamate complexes 2 and 3 presents

Á.Y Castrejón-Antúnez et al. / Polyhedron 111 (2016) 132–142
137
0.82
0.80
0.78
0.76
0.74
0.72
0.95
0.90
0.85
0.80
0.75
0.70
0.65
0.60
0.55
0.00000 0.00001 0.00002 0.00003 0.00004 0.00005 0.00006 0.00007
0.00000 0.00001 0.00002 0.00003 0.00004 0.00005 0.00006
[Benzylamine], M
[Benzene], M
0.74
0.73
0.72
0.71
0.70
0.69
0.68
0.67
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.00000 0.00001 0.00002 0.00003 0.00004 0.00005 0.00006 0.00007
0.00000 0.00001 0.00002 0.00003 0.00004 0.00005 0.00006 0.00007
[Naphthalene], M
[1-Naphthylmethylamine], M
0.86
0.84
0.82
0.80
0.78
0.76
0.74
0.72
0.42
0.40
0.38
0.36
0.34
0.32
1.0x10-5
2.0x10-5
3.0x10-5
4.0x10-5
0.0
0.000000 0.000002 0.000004 0.000006 0.000008 0.000010 0.000012
[1-Pyrenemethylamine], M
[Pyrene], M
Fig. 5. Typical UV/Vis titration plots of 5 (2 ꢁ 10ꢀ5 M) with aromatic amines and aromatic compounds in CH3CN at 25 °C. Solid lines are the fitting curves in accordance with
Eqs. (1) or (2), see details in the text and in Table 1.
the same behavior, however they were not studied in the same
extension.
The analysis of these plots shows that the different complexes
are sensitive to almost all anions added, however, the changes
are in the band near 300 nm which has been demonstrated previ-
ously [13,14] that corresponds to the displacement of dithiocarba-
mate moiety of the complex. These chlorodiphenyltin(IV)
dithiocarbamates complexes can function as chemodosimeters
[22] for CH3COꢀ2 , H2PO4ꢀ and PhCOꢀ2 anions in which the indicator
(dithiocarbamate ligand) is displaced. However, for HSOꢀ4 is not
observed the displacement of the ligand, which can be explained
considering that HSOꢀ4 is a conjugated base (weak) of a strong acid.

138
Á.Y Castrejón-Antúnez et al. / Polyhedron 111 (2016) 132–142
0.26
0.25
0.24
0.23
0.22
0.21
0.20
0.26
0.25
0.24
0.23
0.22
0.21
0.20
0.19
0.0000
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0.0000
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
[n-butylamine], M
[Isobutylamine], M
0.51
0.50
0.49
0.48
0.47
0.46
0.45
0.17
0.16
0.15
0.14
0.13
0.0000
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0.00000 0.00001 0.00002 0.00003 0.00004 0.00005 0.00006
[Isobutylamine], M
[n-butylamine], M
Fig. 6. Typical UV/Vis titration plots of 1 (7 ꢁ 10ꢀ5 M), 2 (3 ꢁ 10ꢀ5 M), 5 (2 ꢁ 10ꢀ5 M) with aliphatic amines in CH3CN at 25 °C. Solid lines are the fitting curves in accordance
with Eqs. (1) or (2), see details in the text and in Table 1.
The profiles observed in Figs. 1–3 cannot be fitted to calculate
binding constants. Then, we decided to test neutral compounds
in order to find guests for the complexes 1–5, i.e., a compounds that
not displaced the dithiocarbamate moiety. The compounds
selected were aromatic compounds (benzene, naphthalene, pyr-
ene), aromatic amines (benzylamine, naphthylmethylamine,
pyrenemethylamine) and aliphatic amines (n-butylamine, isobuty-
lamine) (Scheme 2) which were tested as neutral guest of chloro-
diphenyltin(IV) dithiocarbamate complex 5. For these guests
there were not observed any change in the band close to 300 nm
(Fig. 4), which indicate that the integrity of the complex is main-
tained, then the chlorodiphenyltin(IV) dithiocarbamate complex
5 can act as a host for the neutral guests tested and was possible
to calculate their binding constants.
tin(IV) dithiocarbamate complex 5 and its 1:1 and 1:2 complexes,
respectively, K11 and K12 are stepwise formation constants and [5]t
is the total concentration of 5 [23].
2
A ¼ ððe0
þ
e
1K11½guestꢃ þ
e
2K11K12½guestꢃ Þ½5ꢃtÞ=
ð2Þ
2
ð1 þ K11½guestꢃ þ K11K12½guestꢃ Þ
The values of K, K11 and K12 were calculated from the fitting of
titration plots at several wavelengths to Eqs. (1) or (2) using non-
linear squares regression implemented in Microcal Origin 5 pro-
gram and averaged; the mean values are given in Table 1 and Figs. 5
and 6 present typical plots showing the experimental data and pro-
files of fitting.
The absorptions recorded at different wavelengths were plotted
versus the guest concentration and analyzed using Eq. (1) which
considers the stoichiometry 1:1, where Aobs is the observed absor-
bance, A0 is the absorbance of the dithiocarbamate derivative, A1 is
the maximum absorbance change induced by the presence of the
guest, [G]T is the total concentration of the guest, and K is the bind-
ing constant of the host–guest complex [23].
Table 1 compares the calculated binding constants. The analysis
of binding constants shows that the dithiocarbamate complex 5 is
able to bind neutral guests. In the case of the aromatic guests the
binding constants increase with the number of fused rings. The
same trend was observed for the aromatic amines. This fact sug-
gests that dithiocarbamate complex 5 prefers to bind guests with
a larger surface of contact which in turn offer a more effective
van der Waals interaction.
Although the binding constants for aromatic compounds and
aromatic amines are in the same order of magnitude, is important
to remark the notorious spectroscopic effect caused by their addi-
tion on the bands of dithiocarbamate complex.
Aobs ¼ ðA0 þ A K½Gꢃ =ð1 þ K½Gꢃ Þ
ð1Þ
1
T
T
In some cases, the experimental data were fitted using the Eq.
(2) which considers the stoichiometry 1:2. Where A is the absor-
bance, e0, e1 and e2 are molar absorptivities of free chlorodiphenyl-

Á.Y Castrejón-Antúnez et al. / Polyhedron 111 (2016) 132–142
139
Fig. 7. Geometry optimized structures for the complexes in chloroform (a) 5-benzylamine and (b) 5-pyrenemethylamine in chloroform. The calculations were done with DFT
(B3LYP) and Poisson–Boltzmann (PB) to model the solvent.
A close inspection of the spectra obtained as a result of titra-
tions with the tested guests. (Fig. 4) show that the aromatic com-
pounds cause a minimum disturb on the pyrene bands of 5,
however, the aromatic amines and n-butylamine cause a signifi-
cant hyperchromic displacement and small hypsochromic effect
in the pyrene bands. This effect is more evident in the case of ben-
zylamine, naphthylamine, and n-butylamine which do not have
absorption bands in this spectral region as can be observed in
Fig. 4. These results let us suggest that dithiocarbamate 5 can func-
tion as chemodosimeter for aromatic and aliphatic amines but
without displacement of indicator because the indicator is the pyr-
ene moiety whose bands suffer a hyperchromic effect.
For complex 5 the addition of two or three equivalents of acet-
ate anion cause a shift in 119Sn NMR signal to high field by
D
dSn = 53 ppm, i.e., for free dithiocarbamate 5 the 119Sn signal is
located at ꢀ316.24 ppm and after the first acetate addition the sig-
nal shifted to ꢀ369.24 ppm and remains without change up to
three equivalents of acetate The presence of only one 119Sn signal
indicate that there is not an equilibrium process between 5 and
the product. Similar displacement was observed in more simple
dithiocarbamate complexes but in a lower [acetate]/[dithiocarba-
mate] molar ratio [12a,13]. Which in turn suggest that in the
complex 5, Sn nucleus is less accessible to acetate anion.
In contrast, the addition of aromatic amines as benzylamine or
naphtylmethyl amine up to six equivalents let to observe an equi-
librium between the free dithiocarbamate 5 and its complex 5-aro-
matic amine. In the 1H NMR spectra dithiocarbamate 5 shows only
one signal for their both methylene groups however in the com-
plex 5-aromatic amine arises a new signal corresponding also to
the methylene group of the dithiocarbamate ligand, which is
shifted to high field by almost 1 ppm. This new signal comes up
as a consequence of the difference that it is established when the
guest interact with one arm of the dithiocarbamate ligand through
3.2. NMR titrations
In order to obtain structural information about the interaction
of the chlorodiphenyltin(IV) dithiocarbamate complex with the
studied guests, 1H and 119Sn NMR titrations in CDCl3 were con-
ducted. These experiments were carried out in CDCl3 due in this
solvent is possible to obtain solutions with higher concentrations
suitable to acquire good NMR spectra.

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Á.Y Castrejón-Antúnez et al. / Polyhedron 111 (2016) 132–142
van der Waals interactions (vide infra). This interaction is also
observed in the protons of amine because their signals are broad.
The amine does not interact with the metal center as the 119Sn
NMR spectra show no change in the chemical shift of its signal, giv-
ing evidence that the number of coordination around the tin atom
in the new complex remains.
In order to confirm the formation of the complex dithiocarba-
mate 5-naphtylmethyl amine, it was analyzed the 13C NMR spec-
trum of the mixture and was observed two signals for the carbon
of methylene group of 5 shifted to high field, one of them remains
H
N
H
Cl
Sn
S
Cl
Sn
S
Ph
Ph
-313.58
Ph
Ph
R2
S
R2NH2
R2NH2
+
4.57
198.42
S
N
-
Ph
I
N
6.04
1
R1
R1
Ph
H
R2
almost in the chemical shift of the dithiocarbamate
5
R2NH2
H
N
H
N
(D
d = 0.044 ppm) and the second one shifted by d = 3.8 ppm
D
Ph
Ph
ascribed to the complex 5-naphtylmethylamine. A similar experi-
ment with pyrenemethyl amine was not possible to carry out
because of its poor solubility.
R2
Sn
-491.47
R2
H
S
S
N
Sn
S
R2NH
-
2
Ph
Ph
198.42
S
R2NH2Cl
Fig. 7 shows the optimized calculated structures for the com-
plexes 5-benzylamine and 5-1-pyrenemethylamine. As can be
observed the metallic center is not accessible to amine moiety of
the guest, however, the aromatic amine guests induce a conforma-
tional change of one arm of pyrene groups that can explain the
spectral changes observed in the spectrophotometric titrations
and the presence of two signals for the methylene groups of dithio-
carbamate 5.
R2NH
+
2
N
6.11
4.68
N
R1
Ph
Ph
III
R2NH2
H
II
R1
S
2
R
Similar 1H and 119Sn NMR experiments with the aromatic com-
pounds as benzene, naphthalene and pyrene were carried out with
the complex 5 as a comparison. The addition up to six equivalents
group of dit of benzene did not induce any change in the chemical
shift of proton and Sn nucleus. In 1H NMR experiments, the addi-
tion up to eight equivalents of naphthalene generates a new signal
for the methylene hiocarbamate ligand located to higher field
N
2
R1
NHR
N
Ph
Ph
HS
Sn
N
+
Ph
2
R
H
V
IV
a
D
d = 0.414 ppm which intensity increases with the amount of
naphthalene present in the mixture. In addition, it is possible to
observe the broadening of aromatic signals of dithiocarbamate
ligand without a change in the chemical shift of the signal of
119Sn. On the other hand, the addition up to six equivalents of pyr-
ene cause the broadening of the dithiocarbamate signals: the
methylene signals are slightly shifted to the high field by 0.035
and 0.027 ppm while the 119Sn nucleus did not show any change.
These results suggest that the guests are included between the aro-
matic arms of amine of dithiocarbamate 5 because of the broaden-
ing of the signals and in consequence 5 is able to distinguish the
aromatic compounds by their surface area.
Fig. 8 presents the geometry optimized of the complex 5-pyrene
according to NMR data. The proposed structure of the complex
explain the changes observed in the 1H NMR spectra, suggesting
b
c
Scheme 3. (a) Mechanism suggested for the addition of n-butylamine to
1
(R1 = anthracene, R2 = n-butyl). (b) 119Sn and (c) 13C NMR spectra corresponding
Fig. 8. Geometry optimized structures for the complex 5-Pyrene in chloroform. The
calculations were done with DFT (B3LYP) and Poisson–Boltzmann (PB) to model the
solvent.
to
1
(1 ꢁ 10ꢀ2
M in CDCl3) with different equivalents of n-butylamine, i.e.,
1:n-butylamine. In blue chemical shifts of 119Sn NMR, in red chemical shifts of
13C NMR and in green chemical shifts of 1H NMR. (Color online.)

Á.Y Castrejón-Antúnez et al. / Polyhedron 111 (2016) 132–142
141
that the guests interact with the dithiocarbamate 5 through
hydrophobic (C–H– ) and interactions.
13C spectra and the two signals for 119Sn result of the presence of 1
and III in the mixture while I and II are suggested as intermediated
p
p–p
The addition of aliphatic amines was studied with the chlorodi-
phenyltin(IV) dithiocarbamate 1. For 1 there are two different sig-
nals for the methylene groups, the addition of up to five
equivalents of isobutylamine to dithiocarbamate 1 generate one
additional signal for each methylene group and broadening of the
signal of 119Sn, giving evidence that the number of coordination
around the tin atom in the complex 1-isobutylamine is not chang-
ing. However the addition of n-butyl amine up to five equivalents
results in diverse changes: in the proton spectrum, new signals for
methylene groups and duplicated signals for the rest of the protons
were observed. While in 119Sn NMR spectra comes up two signals
at ꢀ313.2 (broad) and ꢀ491.784 ppm (sharp) and in 13C spectrum
duplicated signals for the dithiocarbamate 1 and a new signal at
151.84 ppm. The changes observed in NMR spectra can be
explained by the equilibria shown in Scheme 3 which includes
the 13C and 119Sn NMR spectra (1H NMR in Supplementary Data).
The addition of one equivalent of n-butylamine to the metallic cen-
ter of dithiocarbamate 1 gives species I with amine coordinated to
metallic center continued by the departure of Clꢀ and a deprotona-
tion of amine to forms species II while the addition of second
equivalent of n-butylamine changes the coordination of Sn from
penta- to hexacoordinated to form the III complex which prefers
the cis arrangement of phenyl groups [24]. The equilibria shown
in Scheme 3 let explain the broad signals for the protons of n-buty-
lamine and ditihiocarbamate 1 and the duplicated signals in 1H and
species but were not isolated. The new signal at 151.84 ppm in 13
C
can be assigned to a carbon of thiourea (V) which formation was
incipient in this process and can be the result of the degradation
of species III accompanied by the species IV. Thiourea V can result
from nucleophilic attack of an amine on the dithiocarbamate car-
bon of on species III, a similar mechanism had been reported for
the reaction of primary amines with zinc dithiocarbamates [25].
By UV/Vis titrations only slight changes were observed.
In contrast, the addition of n-butylamine to the dithiocarbamate
5, as above has been mentioned, causes a hyperchromic and slight
hypsochromic effect on the pyrene bands. Fig. 9a shows the geom-
etry optimized for the complex 5- n-butylamine which in turn can
explain the spectrophotometric results. In addition shows that the
metallic center is not equally accessible for nucleophilic attack as
in the dithiocarbamate 1 (Fig. 9b).
4. Conclusion
The clorodiphenyltin(IV) dithiocarbamates complexes studied
as potential host of anions and neutral aromatic amines and aro-
matic compounds show that the guest with negative charge that
causes a displacement of the ligands of metallic center function
as a chemodosimeters in which the indicator is displaced and it
is observed as a new signal at approximately 300 nm in acetoni-
trile. However can act as a host of neutral compounds as aliphatic
or aromatic amines or aromatic compounds with binding constants
in acetonitrile in the range of 103 to 106 Mꢀ1. In addition, dithiocar-
bamates can function as chemodosimeters for amines without dis-
placement of an indicator because the indicator is the pyrene
moiety whose bands suffer a hyperchromic effect. Finally, the
NMR studies carried out and geometry optimized structures of
the complexes host–guest generated let explain the results
obtained and suggest that the hydrophobic and
p–p interactions
are the interactions that stabilize the complexes dithiocarba-
mate-guest.
Acknowledgments
This work was supported by CONACYT – México, projects
60747, CB2010/158098 and CB2011/168952. The authors thank
LANEM Laboratory for the use of NMR spectrometers.
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.poly.2016.03.035.
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