1, 3-thiazolium-5-thiolates mesoionic compounds: Semiempirical evaluation of their first static hyperpolarizabilities and synthesis of new examples

Article abstract of DOI:10.1590/S0103-50532010000500024

Semiempirical AM1-TDHF calculations of the static first hyperpolarizabilities, β(0), of 1, 3-thiazolium-5-thiolate mesoionic derivatives were performed. Guided by these results, two new mesoionic compounds - 2-(4-nitrophenyl)-3-methyl-4-(methylphenyl)-1,

Full text of DOI:10.1590/S0103-50532010000500024

J. Braz. Chem. Soc., Vol. 21, No. 5, 934-940, 2010.
Printed in Brazil - ©2010 Sociedade Brasileira de Química
0103 - 5053 $6.00+0.00
1,3-Thiazolium-5-thiolates Mesoionic Compounds: Semiempirical Evaluation of
their First Static Hyperpolarizabilities and Synthesis of New Examples
Bruno F. Lyra,a,b Soraya A. de Morais,a Gerd B. Rocha,*,a Joseph Miller,b,c,†
Gustavo L. C. Moura,c Alfredo M. Simas,c Clovis Pepped and Petrônio F. de Athayde-Filhoa,b
aDepartamento de Química, Universidade Federal da Paraíba, 58059-900 João Pessoa-PB, Brazil
bLaboratório de Tecnologia Farmacêutica, Universidade Federal da Paraíba, CP 5009,
58051-970 João Pessoa-PB, Brazil
cDepartamento de Química Fundamental, Universidade Federal de Pernambuco,
50670-901 Recife-PE, Brazil
dDepartamento de Química, Universidade Federal de Santa Maria,
97105-900 Santa Maria-RS, Brazil
Cálculos semi-empíricos do tipo AM1-TDHF para a primeira hiperpolarizabilidade estática,
b(0), de dezesseis compostos mesoiônicos do sistema 1,3-tiazólio-5-tiolato foram realizados.
Com base nos resultados obtidos, dois novos compostos mesoiônicos, 2-(4-nitrofenil)-3-metil-4-
(metilfenil)-1,3-tiazólio-5-tiolato e 2-(4-nitrofenil)-3-metil-4-(metoxifenil)-1,3-tiazólio-5-tiolato,
foram sintetizados e caracterizados por métodos espectroscópicos e analíticos.
Semiempirical AM1-TDHF calculations of the static first hyperpolarizabilities, b(0), of
1,3-thiazolium-5-thiolate mesoionic derivatives were performed. Guided by these results, two new
mesoionic compounds - 2-(4-nitrophenyl)-3-methyl-4-(methylphenyl)-1,3-thiazolium-5-thiolate
and 2-(4-nitrophenyl)-3-methyl-4-(methoxyphenyl)-1,3-thiazolium-5-thiolate - were synthesized
and characterized by analytical and spectroscopic means.
Keywords: mesoionic compounds, 1,3-thiazolium-5-thiolate, nonlinear optical properties,
semiempirical calculations, photonic devices
Introduction
important.3 It has been computationally demonstrated
that molecules containing mesoionic rings as asymmetric
bridges have a performance for second order nonlinear
optical effects equivalent to symmetric polyenic bridges
containing more than seven conjugated double bonds.2
In a previous article3 we showed that, by employing the
Time-Dependent Hartree-Fock (TDHF) method with the
semiempiricalAM1 Hamiltonian,4 one can obtain values for
the first static hyperpolarizability, b(0), that correlate well
with the experimentally observed values for this property.
And we have also described, the synthesis and experimental
measurements of the nonlinear absorption of 1,3-thiazolium-
5-thiolatemesoioniccompounds(Figure1)usingnanosecond
laserpulseswithwavelengthsof570,605and618nm;ledtothe
observation of nonlinear absorption cross-sections s2 as large
as 10-45 cm4 s per photon.5 These compounds are seemingly
very promising for photonic applications. Guided by our
During the last few years mesoionic compounds (MIC)
have attracted the attention of chemists because of the
bonding aspects associated with their unusual structure
which can be understood as mesomeric heterocyclic
betaines, strongly stabilized by p-electron delocalization
and with large dipole moments.1 Such structures can be
regarded as equivalents of push-pull organic compounds of
the type electron-acceptor (A) - polyenic bridge - electron-
donor (D) commonly employed in nonlinear optics.2 But,
unlike these symmetric polyenic bridges, the mesoionic
rings act as asymmetric bridges and the relative positions
of the donor/acceptor groups linked to the ring are very
*e-mail: gbr@quimica.ufpb.br
† in memoriam

Vol. 21, No. 5, 2010
Lyra et al.
935
AM1-TDHF calculations, we have been further designing
and synthesizing mesoionic compounds in our laboratories
for photonic applications.6,7
SCF convergence criteria) and XYZ (to describe the
optimized geometry in Cartesian coordinates). The
nonlinear optical properties were calculated analytically
using the TDHF methodology, implemented in the MOPAC
module, using the following keywords to predict first static
hyperpolarizability: POLAR(E=(0.0), BETA=1, IWFLB=0,
TOL=1.D-9, BTOL=1.D-9). We used E=(0.0) to specify
the energy of the incident radiation as zero electron volts,
BETA=1 and IWFLB=0 for the iterative calculation of
the first static hyperpolarizability, TOL and BTOL are,
respectively, the cutoff tolerance for the calculation of the
polarizability and first hyperpolarizability. The calculated
b(0) values are given in Table 1.
RD
H3C
N
S
S
RA
Figure 1. Structure of 1,3-thiazolium-5-thiolate mesoionic compounds.
Table 1. AM1-TDHF first static hyperpolarizabilities, b(0), and
experimental nonlinear absorption cross-sections, s2, for MIC-1 to
MIC-16
Accordingly, we synthesized new examples of
1,3-thiazolium-5-thiolate mesoionic compounds, especially
those with largeAM1-TDHF calculated values for b(0).
Figure 1 shows that the mesoionic ring possesses two
charged regions separated by what are essentially single
bonds.8 It is this charge separation (asymmetry) that is
responsible for the large values of b(0) obtained for this
class of compounds. Recently, it was proposed by Kuzyk
and co-workers9,10 that conjugated bridges with sites of
reduced conjugation may be excellent prototypes for
increasing the values of b(0). It is worthwhile to mention
that the mesoionic compounds that we have been studying
for nonlinear optics applications since 1996,3 can be
considered as an early example of this paradigm.
Figure 1 shows two groups, RA and RD, linked to the
para positions of two phenyl groups. The group containing
RD is bound to the anionic region of the mesoionic ring and
the group containing RA is bound to the cationic region.
In order to enhance the donating properties of the anionic
region of the mesoionic ring, we are studying compounds
where RD is an electron-donor group. Similarly, we are
using electron-acceptor groups in RA in order to enhance
the accepting properties of the cationic region of the ring.3
MIC
RA
RD
b(0) /
s2 / (10-45 cm4 s
per photon)a
(10-30 esu)
MIC-1
MIC-2
MIC-3
MIC-4
MIC-5
MIC-6
MIC-7
MIC-8
MIC-9
MIC-10
MIC-11
MIC-12
MIC-13
MIC-14
MIC-15
MIC-16
H
H
H
CH3
i-Pr
OCH3
H
23.16
25.90
25.17
28.44
24.81
27.73
28.08
30.82
34.25
38.11
38.89
41.69
51.59
56.06
57.22
61.49
-
-
H
-
H
-
Cl
-
Cl
CH3
i-Pr
OCH3
H
18
-
Cl
Cl
-
CF3
CF3
CF3
CF3
NO2
NO2
NO2
NO2
-
CH3
i-Pr
OCH3
H
30
49
-
-
CH3
i-Pr
OCH3
-
345
-
avalues from reference 5.
Results and Discussion
Theoretical details
The dependence of b(0) on the electronic character of
the aromatic substituents directly attached to the mesoionic
ring is given in Figure 2. The left part of Figure 2 gives b(0)
as a function of the Hammett sp electronic parameters of the
RD groups on the aromatic substituents (p-C6H4RD, RD= H,
Me, i-Pr, OMe ) attached to carbon four of the mesoionic
ring;12 the graph clearly shows that the larger the electron
donating ability of the RD group, the larger is the first static
hyperpolarizabily b(0) with an almost linear trend for each
p-C6H4RA group attached to carbon two of the mesoionic
ring. Correlation of b(0) with the positive sp parameter of
Initially, consider the semiempirical AM1-TDHF
calculations of b(0) for a set of sixteen mesoionic molecules
(MIC-1 to MIC-16) containing the 1,3-thiazolium-5-
thiolate ring (Figure 1).
The ground state geometries of the molecules
were optimized using the AM1 semiempirical method
implemented in MOPAC module of the Scigress Explorer
7.7 package.11 The MOPAC keywords used during
geometry optimization were: GNORM=0.01 (to guarantee
an energy minimum), SCFCRT=1.D-8 (to increase the

936
1,3-Thiazolium-5-thiolates Mesoionic Compounds
J. Braz. Chem. Soc.
RA (right) shows that, the larger the electron withdrawing
ability of RA is, the larger is b(0), but, this time, the increase
follows a quadratic function.
the C6H4RD grouptends to destabilize the HOMO (anionic
region).
In Figure 3 we have a drawing of the HOMO and
LUMO of a representative molecule (MIC-1). We can
clearly see that these orbitals are asymmetrically localized
in the molecule. The most important electronic excitation in
mesoionic compounds is a charge transfer transition from
the HOMO to the LUMO involving a large dipole moment
change.3 Both the decrease of the excitation energy and
the increase of the magnitude of dipole moment change
upon excitation determine the magnitude of b(0), which
in turn determines the nonlinear optical properties of the
compound.
In Table 1 we also have some experimental values for
the nonlinear absorption cross-sections s2 of some of the
molecules, measured using nanosecond laser pulses with a
wavelength of 570 nm.5 We can see that, as the calculated
values of b(0) increase, the experimentally observed values
of s2 also increase and that thebests2 value(345×10-45cm4 s
perphoton)wasproducedforthe2-(4-nitrophenyl)-3-methyl-
4-(4-isopropylphenyl)-1,3-thiazolium-5-thiolate (MIC-15,
b(0) = 57.22 × 10-30 esu).
Our calculations indicate that 2-(4-nitrophenyl)-3-
methyl-4-(methoxyphenyl)-1,3-thiazolium-5-thiolate
(MIC-16) has an even larger first static hyperpolarizability
(b(0) of 61.49 × 10-30 esu) than MIC-15. Therefore,
aiming at producing this improved material for photonic
applications, we set up to establish a synthetic protocol
leading to it; and, through this route, we also synthesized
MIC-14 [2-(4-nitrophenyl)-3-methyl-4-(methylphenyl)-
1,3-thiazolium-5-thiolate] which displayed an appreciable
b(0) value.
Figure 2. Dependence of theAM1-TDHF b(0) magnitude on the electronic
character of the aromatic substituents attached to the mesoionic ring (RA
and RD groups).
Figure 2 shows that the calculated hyperpolarizabilities
are much more susceptible to substitutions in RA than to
substitutions in RD, i.e., varying the group RA for a fixed
RD results in much larger variations in the calculated
hyperpolarizabilities than when we vary RD for a fixed RA.
This result is not unexpected considering that the exocyclic
group of the mesoionic ring already acts as a strong
electron-donor group, while the cationic region of the
ring does not have a well defined electron-accepting atom
and needs a group in RA to direct the electron-accepting
properties of the region.
Mesoionic compounds are conveniently described by a
two molecular orbital (MO) model3; one MO is associated
with the delocalized negative p-charge (HOMO) and linked
to the C6H4RD group and the second MO is associated
with the delocalized positive p-charge (LUMO) linked to
the C6H4RA aryl group. An electron-withdrawing group
attached to the LUMO (cationic region) decreases the
energy of this MO, while the electron-donating group of
The synthetic route leading to these new mesoionics
was essentially the same used previously and involves the
in situ 1,3-dipolar cycloaddition/cycloreversion with CS2
of the corresponding 1,3-oxazolinium-5-olates prepared by
N-aroylation of C-aryl-methylglicines (Figure 4).13
Figure 3. Drawing of the (a) HOMO and (b) LUMO of a representative molecule (MIC-1) where we can see the asymmetry of these orbitals.

Vol. 21, No. 5, 2010
Lyra et al.
937
H
N
O
CHO
OH
KCN, [CH3NH3]Cl
p-NO2C6H4CHO
HCl, ∆
NaOH(aq)
1
1
14, RD= CH3, 65%
16, RD= OCH3, 66%
RD
RD
O2N
C6H4RD
O
N
CS2
Ac2O
N
OH
- CO2
55 oC
O
O2NC6H4
C6H4RD
O
O
2
2
14, RD= CH3, 52%
16, RD= OCH3, 45%
C6H4RD
MIC-14, RD= CH3, 37%
MIC-16, RD= OCH3, 56%
N
S
O2NC6H4
S
Figure 4. Preparation of 1,3-thiazolium-5-thiolate mesoionics.
Compounds MIC-14 and MIC-16 are air stable
solids, which had their molecular formulae established
by elemental microanalysis and confirmed by mass
spectrometry. Other spectroscopic data (1H, 13C NMR and
infra red) are in complete agreement with the proposed
structures.All these details are in the Experimental section.
chemical shift at low field, 148 and 160.4 ppm, are affected
by deshielding effects caused, respectively, by the existence
of the nitro and methoxy groups.
The 13C NMR (APT, 50 MHz, DMSO-d6) study of the
compound MIC-14 showed thirteen chemical shifts. Of
these, seven were assigned to the quaternary carbons, two to
the primary aliphatic carbons and four to the aromatic tertiary
carbons. The carbons of the mesoionic ring of MIC-14 have
chemical shifts in 152.1; 141.4 and 161.9 ppm assigned,
respectively, to C2, C4 e C5 (see Figure 5a). The carbons
C10 and C15 have chemical shifts of 40.6 and 21.4 ppm,
while the aromatic carbons have chemical shifts of 132.7
(C6); 129.4 (C7, 7’); 123.8 (C8, 8’); 148.5(C9); 129.6 (C11);
129.8 (C12, 12’); 128.2 (C13, 13’) and 139.1 (C14).
1
Studies of H NMR of mesoionic compounds are not
very informative when there are not any hydrogen in the
heterocyclic ring, however are important in the detection
of hydrogens in the substituent groups. In contrast, the
13C NMR spectroscopy is an important tool to characterize
the structure of mesoionic compounds due to the large
difference in electronic densities between the two regions
of the betainic ring (HOMO and LUMO). This difference
in electronic density manifests itself in shielding or
deshielding effects of the carbons of the heterocyclic ring
and of the carbons of aromatic or aliphatic groups linked
to the mesoionic ring. The three peaks at ca 160, 150, and
140 ppm are attributed to C5, C2, and C4 respectively
(see Figures 5a and 5b). The reason that C4 is at high field
compared with C5; although both are in the negative region
of the mesoionic ring can be related to the significant partial
double bond character of the carbon-thiolate bond (C5–S5).
The methylic carbon linked to N3 is characterized by a
peak at 40 ppm and the methylic protons have chemical
shifts around the 3.60 ppm, there is a down-field shift as a
result of the positive charge on N3. The carbon atoms with
1
The H NMR (200 MHz, DMSO-d6) spectrum of
MIC-14 shows six hydrogen signals. Of these, two intense
singlets were observed in the aliphatic region with an
integral of 6H for the hydrogens H10 and H15 of the
methyl groups, respectively in 3.64 and 2.38 ppm. There
was also a signal between 8.27 and 7.23 assigned to the
eight aromatic hydrogens.
For compound MIC-16 we observed a similar chemical
behavior. The 13C NMR (APT, 50 MHz, DMSO-d6)
spectrum showed thirteen signals. The carbons of the
mesoionic ring showed chemical shifts of 148.7; 142.5
and 162.5 for C2, C4 and C5, respectively (see Figure 5b).
Carbons C10 and C15 show values of chemical shifts

938
1,3-Thiazolium-5-thiolates Mesoionic Compounds
J. Braz. Chem. Soc.
Figure 5. Schematic representation of the compounds synthesized in the present report. The numbers are employed in the assignment of the peaks of the
1H and 13C NMR spectra. (a) MIC-14 and (b) MIC-16.
that are compatible with the N-methyl group in 40.8 and
the methoxy group in 55.2. The aromatic carbons have
chemical shifts of 132.6 (C6); 130.4 (C7, 7’); 124.6 (C8,
8’); 148.5 (C9); 121.3 (C11); 132.6 (C12, 12’); 114.3 (C13,
13’) and 160.4 (C14).
internal TMS) were recorded on a Varian Unity Plus 300
MHz spectrometer. ElementalAnalysis was carried out on a
Perkin Elmer Elemental Microanalyser. Melting points were
determined on a Kofler hot-plate apparatus combined with
a Carl-Zeiss microscope and are uncorrected.
1
The H NMR (200 MHz, DMSO-d6) spectrum of
MIC-16 has six hydrogen signals. Of these, two intense
singlets were observed in the aliphatic region with an
integral of six hydrogens, three hydrogens were assigned
to the N-methyl group of the heterocyclic ring in 3.69 ppm
and three were assigned to the methoxy group in 3.90 ppm.
In the region between 8.34 and 7.07 ppm we observed
corresponding signals the eight aromatic hydrogens.
The results above are in agreement with the results
observed by Athayde-Filho et al.14
Preparation of N-methyl-C-arylglycines - general
procedure
KCN (12.50 g, 250 mmol) and methylammonium
chloride were dissolved in distilled H2O (100 mL). An
equimolar amount of the aromatic aldehyde dissolved in
MeOH (100 mL) was added, in portions, with vigorous
stirring. The mixture was kept under stirring for 2 h. H2O
(250 mL) was added, followed by addition of toluene
(250 mL). The toluene phase was separated and extracted
with HCl(aq) 6 mol L-1 (3 × 100 mL). The combined acid
extract was refluxed for 8 h giving the products as white
crystals formed on cooling. These were filtered off, washed
with CHCl3 and dried under the air.
Conclusions
In this short report we performed theoretical calculations
of the static first hyperpolarizability of sixteen mesoionic
compounds of the 1,3-thiazolium-5-thiolate system. Based
on our calculations, we synthesized and characterized two
novel mesoionic compounds that showed large values
for this property. Our next step will be the experimental
measurement of the nonlinear optical properties of the
two synthesized compounds in order to test our theoretical
predictions.
N-Methyl-C-(4-methylphenyl)-glycine (114)
28.30g(0.16mol), IR(KBr)νmax/cm-1:3250, 2510, 3032,
2955, 2795, 2722, 1737; 1H NMR (300 MHz, DMSO-d6):
d 2.27 (s, 3H), 2.37 (s, 3H), 4.96 (s, 1H), 7.24 (d, J 8.1 Hz,
2H), 7.36 (d, J 8.1 Hz, 2H), 9.64 (s, 2H); 13C NMR (75 MHz,
DMSO-d6) d 169.5, 139.9, 130.1, 129.0, 128.2, 63.1, 31.0,
21.1; MS (EI, 70eV): m/z (%) = 135 (10.16), 134 (100),
120 (4.94), 119 (1.66), 91 (14.83), 77 (2.73), 51 (3.30), 42
(34.69); Anal. Calc. (%) for C10H14ClNO2 = C, 55.69; H,
6.54; N, 6.49. Found: C, 56.07; H, 6.85; N 6.27; yield 65%;
mp 214-216 oC (recryst. EtOH:H2O (1:1, v/v)).
Experimental
Allreagentsandsolventswereobtainedfromcommercial
sources and used as supplied. Mass spectra were obtained on
a Finnigan GCQ Mat type quadrupole-ion trap spectrometer.
IR spectra (KBr) were obtained on a Bruker IFS66
N-Methyl-C-(4-methoxyphenyl)-glycine, (116)
1
spectrometer. H and 13C NMR spectra (DMSO-d6 with
32.00 g, (0.16 mol), IR (KBr) νmax/cm-1: 3188, 2501,

Vol. 21, No. 5, 2010
Lyra et al.
939
3006, 2960, 2839, 2776, 2782, 1735; 1H NMR (300 MHz,
DMSO-d6): d 2.35 (s, 3H), 3.75 (s, 3H), 4.98 (s, 1H), 7.01
(d, J 8.8 Hz, 2H), 7.43 (d, J 8.8 Hz, 2H), 9.81 (s, 2H);
13C NMR (75 MHz, DMSO-d6) d 169.4, 160.2, 130.5,
122.9. 114.6, 62.4. 55.5, 30.5; MS (EI, 70eV): m/z (%) =
196 [M - Cl]+ (11.59), 195 (1.28), 165 (6.43), 150 (100),
135 (2.64), 107 (4.85), 77 (2.79), 51 (1.37), 42 (25.70);
Anal. Calc. (%) for C10H14ClNO3 = C, 51.84; H, 6.09;
N, 6.05. Found: C, 52.12; H, 5.95; N, 5.93; yield 66%;
mp 257-258 oC (recryst. EtOH:H2O (1:1, v/v)).
Preparation of mesoionics compounds - general procedure
The N-aroyl-N-methyl-C-arylglycine (214 or 216)
(1.4 mmol) was dissolved in Ac2O (20 mL) and heated,
with stirring, at 55 °C for 15 min. After cooling to ambient
temperature, CS2 (20 mL) was added and the reaction
mixture allowed to stand for 48 h. MeOH/H2O (1:1) was
then added until the mixture became cloudy.After standing
for 24 h, the desired products precipitated as orange-red
crystals, which were recrystallized from MeOH.
Preparation of N-amidoacids - general procedure
2-(4-Nitrophenyl)-3-methyl-4-(4-methyphenyl)-1,3-
thiazolium-5-thiolate, (MIC-14)
N-Methyl-C-arylglycines (114,16) (0.30 mol) were
dissolved in the minimum amount of NaOH(aq) (10%)
with continuous stirring kept for 2 h. Equimolar amounts
of 4-nitro-benzoyl chloride were added dropwise and the
reaction stirred for 2 h. During this time, the crude product
precipitated. The mixture was neutralized with HCl(aq)
(10%). The white crystalline products were filtered, washed
with H2O, air-dried, and used without further purification:
0.19 g, (0.51 mmol); IR (KBr) νmax/cm-1: 3117, 3062,
2994, 1607, 1542, 1495, 1429, 1351, 1294; 1H NMR (300
MHz, CDCl3): d 2.38 (s, 3H), 3.64 (s, 3H), 7.23 (d, J 8.2 Hz,
2H), 7.28 (d, J 8.2 Hz, 2H), 7.64 (d, J 8.8 Hz, 2H), 8.27 (d,
J 8.8 Hz, 2H); 13C NMR (75 MHz, CDCl3): d 161.9, 152.1,
141.4. 139.1, 148.5, 132.7, 129.8, 129.6, 129.4, 128.2, 123.8,
40.6, 21.4; MS (EI, 70 eV): m/z (%) = 343 [M+1] (17.74),
+
342 [M • ] (100), 327 (8.07), 296 (19.94), 281 (15.43), 179
(20.14), 166 (2.99), 135 (9.43), 119 (4.41), 91 (4.23), 75
(2.08);Anal. Calc. for C17H14N2O2S2:C, 59.63; H, 4.12; N,
8.18; S, 18.73. Found: C, 60.04; H, 4.71; N, 8.27; S, 19.03;
yield 37%, mp 183-185 °C (recryst. EtOH:H2O (1:1, v/v)).
N-(4-Nitrobenzoyl)-N-methyl-C-(4-methylphenyl)-glycine,
(214)
5.37 g, (0.16 mol), IR (KBr) νmax/cm-1: 3168, 3114,
3082, 2985, 2859, 2861, 1702, 1632; 1H NMR (300 MHz,
CDCl3): d 2.35 (s, 3H), 2.69 (s, 3H), 6.38 (s, 1H). 7.20 (d, J
8.2 Hz, 2H), 7.25 (d, J 8.2 Hz, 2H), 7.61 (d, J 8.4 Hz, 2H),
2-(4-Nitrophenyl)-3-methyl-4-(4-metoxyphenyl)-1,3-
thiazolium-5-thiolate, (MIC-16)
13
8.24 (d, J 8.4 Hz, 2H), 7.90 (s, 1H); C NMR (75 MHz,
0.29 g, (0.78 mmol); IR (KBr) νmax/cm-1: 3009, 2967,
1
CDCl3): d 173.9, 170.6, 148.5, 141.4, 139.1, 129.7, 129.6,
129.4, 128.1, 123.8, 60.8, 34.6, 21,1; MS (EI, 70 eV): m/z
(%) = 327 (1.74), 283 [M-CO2H]+ (15.02), 178 (100), 150
(27.48), 133 (13.91), 132 (73.93), 122 (2.19), 117 (2.55),
91 (9.44); Anal. Calc. for C17H16N2O5: C, 62.19; H, 4,91;
N, 8,53. Found: C, 61.88; H, 4.93; N, 8.67; yield 53%,
mp 169-171 oC.
2897,1590, 1489, 1513, 1426, 1334, 1282; H NMR
(300 MHz, CDCl3): d 3.90 (s, 3H), 3.69 (s; 3H), 7.07 (d,
J 8.8 Hz, 2H), 7.48 (d, J 8.8 Hz, 2H), 7.88 (d, J 8.4 Hz,
2H), 8.34 (d, J 8.4 Hz, 2H); 13C NMR (75 MHz, CDCl3):
d 162.5, 160.4, 148.7, 148.5, 142.5, 132.6, 130.4, 124.6,
121.3, 114.3, 55.2, 40.8; MS (EI, 70 eV): m/z (%) = 359
+
+
[M+1] (17), 358 [M] • (94.62), 343 (9.58), 312 (47.77),
297 (32.37), 282 (11.51), 210 (9.95), 195 (100), 166 (6.64),
163 (18.62), 151 (29.44), 135 (40.27), 63 (17.59); Anal.
Calc. for C17H14N2O3S2, C, 56.96; H, 3.94; N, 7.82; S 17.89.
Found: C, 57.13; H, 3.87; N, 8.03; S, 18.03; 56%, mp 215-
217 °C (recryst. EtOH:H2O (1:1, v/v)).
N-(4-Nitrobenzoyl)-N-methyl-C-(4-methoxyphenyl)-
glycine, (216)
4.72 g, (0.13 mol); IR (KBr) νmax/cm-1: 3001, 2956,
2839, 1699, 1631, 1537, 1349; 1H NMR (300 MHz, CDCl3):
d 2.67 (s, 3H), 3.77 (s, 3H), 6.32 (s, 1H), 6.88 (d, J 8.3
Hz, 2H), 7.24 (d, J 8.3 Hz, 2H), 7.58 (d, J 8.2 Hz, 2H),
Supplementary Information
13
8.21 (d, J 8.2 Hz, 2H), 8.67 (s, 1H); C NMR (75 MHz,
CDCl3): d 173.8, 170.6, 160.0, 148.4, 141.3, 130.9, 128.1,
124.4, 123.8, 114.4, 60.6, 55.3, 34.6; MS (EI, 70 eV): m/z
(%) = 344 [M] • (1.01), 300 (55.6), 299 (38.35), 194 (100),
Supplementary data are available free of charge at
http://jbcs.sbq.org.br, as PDF file.
+
150 (37.31), 149 (70.32), 148 (95.21), 133 (11.36), 122
(9.56), 107 (2.32); Anal. Calc. for C17H16N2O6: C, 59.30;
H, 4.68; N, 8.14. Found: C, 60.02; H, 4.61; N, 8.03; yield
44.60%, mp 181-183 oC.
Acknowledgments
The authors would like to thank CNPq (Brazil) for
research grants and for scholarships.

940
1,3-Thiazolium-5-thiolates Mesoionic Compounds
J. Braz. Chem. Soc.
References
8. de Oliveira, M. B.; Miller, J.; Pereira, A. B.; Galembeck, S. E.;
de Moura, G. L. C.; Simas, A. M.; Phosphorus, Sulfur Silicon
Relat. Elem. 1996, 108, 75.
1. de Athayde, P. F.; Miller, J.; Simas, A. M.; Synthesis 2000, 11,
1565.
9. Zhou, J. F.; Kuzyk, M. G.; Watkins, D. S.; Opt. Lett. 2006, 31,
2891.
2. Silva, A. M. S.; da Rocha, G. B.; Menezes, P. H.; Miller, J.;
Simas, A. M.; J. Braz. Chem. Soc. 2005, 16, 583.
3. Moura, G. L. C.; Simas, A. M.; Miller, J.; Chem. Phys. Lett.
1996, 257, 639.
10. Perez-Moreno, J.; Zhao,Y.; Clays, K.; Kuzyk, M. G.; Opt. Lett.
2007, 32, 59.
11. Scigress Explorer version 7.7; Fujitsu: Tokyo, Japan, 2008.
12. Hansch, C.; Leo, A.; Taft, R.W.; Chem. Rev. 1991, 91, 165.
13. Lira, B. F.; de Athayde, P. F.; Miller, J.; Simas, A. M.; Dias, A.
D.; Vieira, M. J.; Molecules 2002, 7, 791.
4. Dewar, M. J. S.; Zoebisch, E. G.; Healy, E. F.; Stewart, J. J. P.;
J. Am. Chem. Soc. 1985, 107, 3902.
5. Pilla, V.; de Araújo, C. B.; Lira, B. F.; Simas, A. M.; Miller, J.,
Athayde-Filho, P.F.; Opt. Commun. 2006, 264, 225.
6. Rakov, N.; de Araújo, C. B.; da Rocha, G. B.; Simas, A. M.;
Athayde-Filho, P. A. F.; Miller J.; Chem. Phys. Lett. 2000, 332,
13.
14. Athayde-Filho P. F.; Miller J.; Simas A. M.; Lira B. F.; Luis, J.
A. S.; Zuckerman-Schpector, J.; Synthesis 2003, 5, 685.
Received: May 15, 2009
7. Bezerra Jr, A. G.; Gomes, A. S. L.; Athayde-Filho, P. F; da
Rocha G. B.; Miller, J.; Simas A. M.; Chem.Phys. Lett. 1999,
309, 421.
Web Release Date: February 4, 2010

J. Braz. Chem. Soc., Vol. 21, No. 5, S1-S5, 2010.
Printed in Brazil - ©2010 Sociedade Brasileira de Química
0103 - 5053 $6.00+0.00
1,3-Thiazolium-5-thiolates Mesoionic Compounds: Semiempirical Evaluation of
their First Static Hyperpolarizabilities and Synthesis of New Examples
Bruno F. Lyra,a,b Soraya A. de Morais,a Gerd B. Rocha,*,a Joseph Miller,b,c,†
Gustavo L. C. Moura,c Alfredo M. Simas,c Clovis Pepped and Petrônio F. de Athayde-Filhoa,b
aDepartamento de Química, Universidade Federal da Paraíba, 58059-900 João Pessoa-PB, Brazil
bLaboratório de Tecnologia Farmacêutica, Universidade Federal da Paraíba, CP 5009,
58051-970 João Pessoa-PB, Brazil
cDepartamento de Química Fundamental, Universidade Federal de Pernambuco,
50670-901 Recife-PE, Brazil
dDepartamento de Química, Universidade Federal de Santa Maria,
97105-900 Santa Maria-RS, Brazil
Figure S1. 13C (APT) NMR spectrum for MIC-14 (CDCl3, 50 MHz).
*e-mail: gbr@quimica.ufpb.br
† in memoriam

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1,3-Thiazolium-5-thiolates Mesoionic Compounds
J. Braz. Chem. Soc.
Figure S2. Expanded version of 13C (APT) NMR spectrum for MIC-14 (CDCl3, 50 MHz).
Figure S3. 1H NMR spectrum for MIC-14 (CDCl3, 200 MHz).

Vol. 21, No. 5, 2010
Lyra et al.
S3
Figure S4. Expanded version of 1H NMR spectrum for MIC-14 (CDCl3, 200 MHz).
Figure S5. 13C (APT) NMR spectrum for MIC-16 (CDCl3, 50 MHz).

S4
1,3-Thiazolium-5-thiolates Mesoionic Compounds
J. Braz. Chem. Soc.
Figure S6. Expanded version of 13C (APT) NMR spectrum for MIC-16 (CDCl3, 50 MHz).
Figure S7. 1H NMR spectrum for MIC-16 (CDCl3, 200 MHz).

Vol. 21, No. 5, 2010
Lyra et al.
S5
Figure S8. Expanded version of 1H NMR spectrum for MIC-16 (CDCl3, 200 MHz).