An experimental and theoretical approach of spectroscopic and structural properties of the bis(diethyldithiocarbamate)-cobalt(II)

Article abstract of DOI:10.1016/j.molstruc.2012.06.041

Theoretical and experimental bands have been assigned for the Fourier Transform Infrared spectrum (FT-IR) and FT-Raman of the bis(diethydithiocarbamate)Co(II) complex, [Co(DDTC)₂]. The calculations have been based on the DFT/B3LYP method, second derivative spectrum and band deconvolution analysis. The UV-Vis experimental spectra of [Co(DDTC)₂] was measured in the solid state and in an acetonitrile solution. The calculated electronic spectrum was estimated using the TD/PBE1PBE and TD/B3LYP methods 6-311G (d,p) basis set for all atoms. The Bond Orbital Analysis was carried out with the DFT:B3LYP/PBE1PBE methods, revealing electronic delocalization effects involving CoS and CN bonds and their neighboring groups. The observed valence configurations for the alpha and beta electrons of the cobalt atom were (4s)^0.46(3d)^7.69 (B3LYP) and (4s)^0.46(3d)^7,68 (PBE1PBE), as expected for the planar structure around the Co(II) cation. The calculated infrared and UV-Vis spectra, based on the proposed geometrical structure of the bis(diethyldithiocarbamate)cobalt(II) complex, showed an excellent agreement with the experimental spectra.

Full text of DOI:10.1016/j.molstruc.2012.06.041

Journal of Molecular Structure 1029 (2012) 119–134
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Structure
journal homepage: www.elsevier.com/locate/molstruc
An experimental and theoretical approach of spectroscopic and structural
properties of the bis(diethyldithiocarbamate)–cobalt(II)
a,b
b
b
c
a
d
A.C. Costa Júnior , O. Versiane , G. Faget Ondar , J.M. Ramos , Glaucio B. Ferreira , A.A. Martin ,
C.A. Téllez Soto
a
a,d,
⇑
Departamento de Química Inorgânica, Instituto de Química, Universidade Federal Fluminense (UFF), Morro do Valonguinho s/n, Niterói-Centro CEP 24210-150, RJ, Brazil
Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro (IFRJ), Unidade de Rio de Janeiro, Rio de Janeiro, RJ, Brazil
Instituto de Química, Universidade Federal do Rio de Janeiro, CP 68563, 21945-970 Rio de Janeiro, RJ, Brazil
b
c
d
Laboratory of Biomedical Vibrational Spectroscopy, IP&D, Research and Development Institute – UNIVAP, Av. Shishima Hifumi, 2911 Urbanova, 12.224-000, São José dos Campos, SP,
Brazil
h i g h l i g h t s
"
"
"
"
"
Synthesis of bis-diethyldithiocarbamate Co (II) was carried out.
The FT-IR and Raman spectra of [Co(DDTC) ] were carried out.
The Bond Orbital Analysis was used with the DFT method.
The solid/solution UV–Vis spectra of [Co(DDTC) ] was measured.
The calculated UV–Vis spectrum was performed using TD/PBE1PBE and TD/B3LYP methods.
2
2
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 18 April 2012
Received in revised form 19 June 2012
Accepted 19 June 2012
Available online 26 June 2012
Theoretical and experimental bands have been assigned for the Fourier Transform Infrared spectrum (FT-
IR) and FT-Raman of the bis(diethydithiocarbamate)Co(II) complex, [Co(DDTC)
been based on the DFT/B3LYP method, second derivative spectrum and band deconvolution analysis.
The UV–Vis experimental spectra of [Co(DDTC) ] was measured in the solid state and in an acetonitrile
2
]. The calculations have
2
solution. The calculated electronic spectrum was estimated using the TD/PBE1PBE and TD/B3LYP meth-
ods 6-311G (d,p) basis set for all atoms.
Keywords:
Bis(diethyldithiocarbamate)cobalt(II)
complex
FT-infrared spectrum
DFT method
The Bond Orbital Analysis was carried out with the DFT:B3LYP/PBE1PBE methods, revealing electronic
delocalization effects involving CoAS and C@N bonds and their neighboring groups. The observed valence
0
.46
7.69
configurations for the alpha and beta electrons of the cobalt atom were (4s) (3d)
(B3LYP) and
0
.46
7,68
(4s) (3d)
(PBE1PBE), as expected for the planar structure around the Co(II) cation. The calculated
NBO analysis
UV–Vis spectrum
infrared and UV–Vis spectra, based on the proposed geometrical structure of the bis(diethyldithiocarba-
mate)cobalt(II) complex, showed an excellent agreement with the experimental spectra.
Published by Elsevier B.V.
1
. Introduction
stable complexes with transition and non-transition metal ions
and exhibit a variety of coordination modes both in homo and het-
The diethyldithiocarbamate ligand, known as DDTC ½ðethylÞ
eronuclear complexes [5,6]. An practical example of these proper-
ties is the association of some compounds containing dithio
ligands with cisplatin. Berry et al. [7] carried out studies motivated
by the chemoprotective action of these ligands, that allows doses
up to 160 mg/m of the drug, reducing the ototoxicity by inhibition
of the nephrotoxic effects of cisplatin [3].
2
ꢀ
NCS ꢁ, has been extensively studied in different fields, including
2
industrial applications such as vulcanization additives, stabilizers
for PVC, and also biological systems like fungicides, antibacteri-
cides and anti-cancer agent [1–4]. Dithio ligands are considered
as soft donors, showing excellent coordination ability. They form
2
A better understanding of structure-property correlations for
dithiocarbamates required several spectroscopic studies [8–10].
Bauer et al. [11] carried out a vibrational assignment of DDTC com-
plex with zinc, cadmium and lead, but did not consider the cou-
pling of the metal-sulfur stretching modes. Also, the investigation
⇑
Corresponding author at: Departamento de Química Inorgânica, Instituto de
Química, Universidade Federal Fluminense (UFF), Morro do Valonguinho s/n,
Niterói-Centro CEP 24210-150, RJ, Brazil.
E-mail address: tellez@vm.uff.br (C.A. Téllez Soto).
0
022-2860/$ - see front matter Published by Elsevier B.V.
http://dx.doi.org/10.1016/j.molstruc.2012.06.041

1
20
A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
of the mixed toluene-3,4-dithiolatodialkyldithiocarbamates of ar-
senic(III) and bismuth(III), such as [C (CH )S MS CNR ] (M@As
and Bi; R@CH , C and CH -CH ), was carried out by Chauhan
et al. [12]. In this work, the infrared spectra present bands at
2.2. Synthesis of bis-diethyldithiocarbamate Co (II)
6
H
3
3
2
2
2
3
H
2 5
2
2
To a solution of diethyldithiocarbamate (5 mmol) in 50 mL of
+
deionizated water was stirred by 20 min obtaining a pH
3
O = 10.
ꢀ1
+
ꢀ1
3
10–320 and 340–360 cm , assigned as AsAS and BiAS stretching
The pH
3 3
O was adjusted to 6.5 with HNO 6 mol L . Then col-
vibrations, respectively. However, the assignment of pure metal-
sulfur modes, existent in As and Bi complexes, is not observed in
complexes forming rings of four or five members. In fact, a large
number of studies not present conclusive assignments [10,13].
For example, San Andres et al. describe the spectrophotometric
determination of copper(II), nickel(II) and cobalt(II) with diethyldi-
thiocarbamate complexes without any detailed assignment of elec-
tronic bands [14]. Also, Mikosh et al. [15] reports a study of normal
coordinate analysis in vibrational spectra for copper and nickel
dithiocarbamate complexes, but the assignment in the region of
the metal-ligand framework was not carried out. Some theoretical
studies were also performed to understand different properties of
dimethyl- and diethyldithiocarbamate complexes of Ag(I), Ni(II),
Cu(II) and Zn(II) [13]. The calculations were based on density func-
tional theory (DFT)/B3LYP and suggested that the important vibra-
tional characteristic could be used to discern uni- and bidentate
bonding through the Raman activity of the CAS stretching. No
vibrational assignment of the framework vibrational region was
done.
balt(II) nitrate (0.914 g, 5 mmol) was added to this solution and
the pH O was maintained around 6.5. This control was done using
3
a potentiometer and all the synthesis was carried out under stir-
ring at room temperature. The agitation was maintained for
10 min until the formation of a green solid precipitate. This precip-
itate was filtered under reduced pressure and washed for three
+
times with deionized water. [Co(DDTC)
uum in a desiccator with sulfuric acid. Elemental analysis (CHN)
and atomic absorption, for C10 Co (Found C, 33.73%; N,
2
] solid was kept under vac-
20 2 4
H N S
7.89%; H, 5.69% and Co, 16.20%. Calculated: C, 33.78%; N, 7.88%;
and H, 5.67% and Co, 16.57%).
2.3. Calculations
The calculations were carried out for the neutral complex,
[Co(DDTC) ], considered it as non-interacting independent units.
2
The intermolecular interactions Metal—S and S—S were neglected
in the present work and the results were compared with similar
dithiolates [16,17]. The same approach, neglecting intermolecular
interactions, was employed in a previous theoretical work on
vibrational and UV–Vis spectroscopy of a series of anionic com-
plexes of 1,3-dithiole-2-thione-4,5-dithiolate (dmit) and 1,3-
dithiole-2-one-4,5-dithiolate (dmio), and a good agreement was
obtained between calculated and experimental data [18,19].
For geometry optimization, the density functional theory meth-
ods (B3LYP and PBE1PBE) were used in the Gaussian 03 program
2
Although the [Co(DDTC) ] complex belongs to a very important
class of coordination compounds any conclusive structural, vibra-
tional and electronic study were carried out. Due to this lack of
information, we propose for this complex a synthesis route analysis,
based on graphical method, and also complete spectroscopy study.
The structural studies of the solid powder were carried out by
means of FT-IR and Raman vibrational spectra and quantum
mechanical theoretical calculations. The natural Bond Orbital Anal-
ysis (NBO) was also used with the purpose to study the charge trans-
ference properties in the complex. UV–Vis spectra were measured
in the solid state and in acetonitrile solution. The transition energies
and oscillator strengths were calculated with Time Dependent (TD)
method to assign of charge transference (CT) electronic bands. The
theoretical–experimental study of the vibrational and electronic
properties confirms the structure proposed in this complex.
ꢂꢂ
[20]. For all calculations, we used the triple zeta 6-311G basis
set in carbon, sulfur, nitrogen, hydrogen and cobalt atoms.
All calculations have been optimized from several initial geom-
etries, in order to guarantee the global minima energy structures.
After this procedure, the vibrational calculations were performed.
No imaginary mode was observed. Characteristic normal stretch-
2 5
ing and bending modes from the AC H groups were visualized
using the graphical Chemcraft program [21]. The skeletal or frame-
work normal modes were determinate using the percentage devi-
ation of the geometrical parameters (PDPG), from its equilibrium
position. The study of the molecular orbitals was carried out using
the Mulliken population analysis and a graphical analysis with the
Chemcraft and GaussSum [22] programs. The information of the
molecular orbitals was also evaluated through the density of states
(DOS) spectra and orbital overlap population (OPDOS), using the
GaussSum and QM-Forge [23] programs. Thus, the metal-sulfur
interaction was described as bonding or antibonding.
2
. Experimental
2.1. General
Colbalt(II) nitrate, sodium diethyldithiocarbamate trihydrate
salt and HNO were purchased from Vetec Co. All solvents and re-
3
agents were used as received without further purification. Elemen-
tal analysis (CHN) was carried out in a Sinc EA 1110 analyzer. The
The calculations of the transition energies and the oscillator
strengths in the UV–Vis spectra of the optimized structures were
carried out using the TD method, implemented in the Gaussian
03 with the transition moment calculation based on B3LYP and
PBE1PBE orbitals. Evaluation of the theoretical methods was
accomplished using the first 70 lowest energy states. The analysis
of the TD/DFT states and the spectra simulation were carried out
with the GaussSum program, using Gaussian functions with half-
ꢀ
1
infrared spectra between 4000 and 370 cm were measured as a
KBr pellet and polyethylene pellet at room temperature, on a Per-
kin Elmer 2000 FT-IR spectrometer. Data was collected with a res-
ꢀ
1
ꢀ1 ꢀ1
olution of 4 cm . Scanning speed 0.2 cm
s
and 120 scans were
ꢀ1
used. The Raman spectra between 4000 and 100 cm were mea-
sured as a solid sample at room temperature, on a FT-Raman Bru-
ker model RFS 100/S spectrometer. Data was collected with a
ꢀ1
ꢀ1
resolution of 4 cm and 120 scans were used. Source setting: laser
widths of 3500 cm . The incorporation of the solvent effect in
ꢀ
1
of 9394.75 cm ; 500 mW. Aperture setting: 7.0 mm. The solid
state UV–Vis spectrum was acquired between 250 and 1000 nm,
using a Varian Cary 5000 spectrophotometer. The UV–Vis spec-
trum in acetonitrile (MeCN) solution was acquired between 200
and 800 nm in a Varian Cary 50 spectrophotometer. The percent-
the TD method, using the conductor polarizable calculation model
(CPCM), was also carried out with MeCN.
Finally, to corroborate the previous observations, the analysis of
the variation of the electronic density of this compound was car-
ried out through Natural Orbital Bond (NBO). This method allowed
us to qualitatively classify the main energy interactions among the
atoms in the complex, according to the donation and retro-dona-
tion processes. The results were evaluated for both functional used
in this study.
age of cobalt was determined by atomic absorption spectrometry
+
using a Varian-1106 spectrophotometer. The pH
3
O control during
the synthesis of the complex was carried out with the potentiom-
eter Micronal B 375.

A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
121
3
. Results
and subsequente decomposition into carbon disulfide and proton-
+
ated amine. The composition is favoured when the pH
3
O
of the
0
þ
3.1. General
reational mean is lower than pK
a
of the R RNH
2
ion. The pK of
a
diethyldithiocarbamate acid derived from diethylamine is 3.95 in
Monosodium DDTC salt is easily prepared by treatment of car-
19 °C [24]. Thus, the synthesis must be performed in optimum
+
bon disulfide with diethylamine in the presence of sodium hydrox-
ide. This compound is a stable reagent in solid state, but the most
important property of this ion is its protonation in acid solution
pH
3
O range between 5.0 and 7.5. This prevents the decomposition
of DDTC and the metal hydroxide formation.
The definition of these optimal conditions of synthesis was
+
evaluated in different pH
3
O conditions. These data were obtained
from the graphical method [25], presented in Fig. 1. The graph
+
3
shows the region of optimum pH O to performer the synthesis
of the complex around 6.5. This allowed us to obtain the complex
with a adequate yield and a purity satisfactory.
The solid obtained after purification was characterized through
typical bands of the ligand in the infrared region, as
m
CAH stretch-
C@N stretchings between
500 and 1400 cm , presented in Fig. 2 for the IR and Raman
spectra.
Also, UV–Vis experimental spectra are shown in Fig. 3. The solid
ꢀ1
ings between 3000 and 2900 cm and
m
ꢀ1
1
state spectrum presents an appreciable enhancement of intensity
in the region between 450 and 800 nm. This region was detached
in the same figure, where we evidenced these transitions increas-
ing by ten times the absorbance of the spectrum of [Co(DDTC)
solution of MeCN. Fig. 4 shows the deconvolution band analysis
DBA) of the UV–Vis spectra in the solid state and solution. In this
figure is detached the UV–Vis spectrum of the [Co(DDTC) ] com-
2
], in
(
2
plex after further dilution with the purpose to demonstrate the
CT bands lower to 250 nm.
2
Fig. 1. Species distribution diagram of DDTC and of Co(OH) . The detached region
represents the great pH O of synthesis.
3
+
Fig. 2. Experimental spectra of [Co(DDTC)
2
]: (a) FT-IR spectra and (b) FT-Raman spectra.

1
22
A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
3.2. Optimization of the geometrical parameters
Ab initio optimization of the geometrical parameters, and the
structural analysis of the [CoDDTC ] complex, was carried out
2
employing the methods described above which are similar to the
procedures found in the literature [26–30]. The B3LYP theoretical
values for the CoAS, C@N and CAS bond lengths were of 2.29,
1
.34 and 1.74 Å, without symmetry restrictions. The bond angles
S(8)ACoAS(11) and S(9)ACoAS(10) were of 179.17° and 179.73°,
respectively, showing a little deviation from the planar structure
of the CoS
are given in Table 1. The complete structure of the [Co(DDTC)
complex is represented in Fig. 5. Results were also evaluated with
2V symmetry for both methods (B3LYP and PBE1PBE) and are de-
4
framework. Selected bond lengths and bond angles
2
]
C
scribed in Table 1S of the Supplementary material. The values were
similar to those observed with the calculations without symmetry,
with fluctuations of less than two percent. These theoretical results
were corroborated by crystallographic data of analogous dithio-
lates (iso-maleonitrile-dithiolate [16] and carbodiphosphorane
2
CS adduct [17]) coordinated with cobalt (III). In these dithiolates,
2
Fig. 3. UV–Vis spectra of [Co(DDTC) ]: (a) solid state; (b) acetronitrile solution.
the CoAS bonds observed are between 2.250 and 2.279 Å and the
SAC bonds are between 1.689 and 1.717 Å. Another important
structural parameter is the distance SAS that is responsible for
the bite angle of the ligand to the metal. The theoretical calcula-
tions show an average value of 2.85 Å. This average value is higher
Exp.
Fit
Gauss
11
10
than the values found in dithiolates, which were reported between
9
8
7
6
5
4
3
2
1
0
2
þ
2
.781 and 2.811 Å [16,17], as well as for S8 cations which have S—S
distances of 2.83 Å [31].
The charge distributions and bond order were also evaluated in
this study. The results were obtained from the Mulliken population
analysis and Mayer bond order. The results are described in Table
1
0
2
S of the Supplementary material. The bond order for CAS and
2
00 210 220 230 240 250 260 270 280 290 300
Wavenumber (nm)
C@N confirm the electronic delocalization expected for this type
of ligand with a planar characteristic. The values obtained for bond
orders showed intermediate values between single and double
bonds. The charge distributions within the complex was also
important, especially the charge on the metal. According to Gorel-
6 5
sky et al. [32] for compounds [ML(SC F )] (M = first-row transition
300
400
500
600
700
800
900
1000
metal), the ionic contribution to the M-S bonds is related to the
distribution of metal atomic charge and the thiolate ligand. For sys-
tems with a large metal charge, large ionic contributions and lower
MAS bond orders are expected. The same tendency was found in
Wavenumbers (nm)
Solid
2
1
1
0
0
,0
,5
,0
,5
,0
Exp
ꢀ1
the study of [M(LAL)
2
]
(M@Sb or Bi; LAL = dmit or dmio) at
Fit
Gauss
RHF and DFT levels [33] and is also observed for the complex used
in this work.
Table 1
Calculated parameters with B3LYP using 6-311G (d,p) and no symmetry for the
[Co(DDTC)
2
] complex.
Atoms
i, j
Bond
Atoms
Bond angles Atoms
Bond
angles (°)
lengths i, j, k
Å)
(°)
i, j, k
(
R(1–8)
R(1–9)
2.28
2.29
2.29
2.28
1.34
1.73
1.74
1.47
1.47
A(8–1–9)
A(8–1–10)
A(8–1–11)
A(1–8–2)
A(9–1–10)
A(9–1–11)
A(1–9–2)
A(10–1–11) 78.31
A(1–10–12) 84.30
A(1–11–12) 84.57
78.33
A(2–3–4)
A(2–3–5)
A(8–2–9)
A(4–3–5)
A(10–12–11) 112.78
A(10–12–13) 123.42
A(11–12–13) 123.80
A(12–13–14) 120.61
A(12–13–15) 120.91
A(14–13–15) 118.48
120.60
120.91
112.79
118.48
101.68
179.17
84.57
179.73
101.68
84.29
2
00
300
400
500
600
700
800
R(1–10)
R(1–11)
R(2–3)
R(2–8)
R(2–9)
R(3–4)
R(3–5)
R(12–13) 1.34
R(13–14) 1.48
R(13–15) 1.47
Wavenumbers (nm)
2
Fig. 4. Band deconvolution analysis of the UV–Vis spectra of [Co(DDTC) ].
A more detailed analysis of spectroscopic information of the
complex was carried out through an theoretical-experimental
assignment, considering structural parameters calculated by the
proposal obtained by geometry optimization.
A(3–2–8)
A(3–2–9)
123.79
123.42

A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
123
2
Fig. 5. DFT:B3LYP/6-311G (d,p) calculated structure for the [Co(DDTC) ] complex.
3
.3. Vibrational assignments
spectra are found in Fig. 1S of the Supplementary material. For the
discussion of the vibrational assignment, we took the DFT values
corrected by the scale factor of 0.9613 as a base for comparison
[34] in all fundamental vibrational modes, 3n ꢀ 6 = 105. These ad-
justed data were associated with the second derivative spectrum
and with DBA of the infrared bands of the [Co(DDTC) ] complex.
2
For an accurate description of the normal modes in the metal-li-
gand spectral range, we use the percentage of deviation of the geo-
Vibrational assignments were carried out with support of Den-
sity Functional Theory (DFT) calculations using the B3LYP method
with a 6-311-G(d,p) basis set having the structural geometry ob-
tained by the same method as the starting point. The calculated
values with and without symmetry did not present imaginary fre-
quencies and are described in Table 2. The simulated IR and Raman
Table 2
] complex (wavenumber in cm 1).
ꢀ
Experimental FT-IR and FT-Raman and DFT-B3LYP/6-311G (d,p) calculated spectra for the [Co(DDTC)
2
*
**
*
**
Wncalc
B3LYP
I
IR
I
R
Wncor
(C2v
Symm. Wncalc
B3LYP
I
IR
I
R
Wncor
IR
WnExp
(%T)
IR
DBA
Raman
WnExp
Raman
DBA
Assignment (internal coordinate)
(C2v
)
(C2v
)
)
(C
1
)
1
(C )
1
(C )
(
C
2v
)
1
(C )
3127
3127
3123
3123
3107
3107
3104
3104
3097
0.09
102.29
0.00
20.68 3006
17.99 3006
0.54 3002
5.26 3002
a
1
b
2
a
2
b
1
a
1
b
2
b
1
a
2
a
1
3128
3128
3124
3123
3108
3108
3105
3105
3099
23.51
76.95
3.71
16.31 3007
16.27 3007
2.89 3003
2.41 3002
m
m
m
m
m
m
m
m
m
as(CH)(CH
as(CH)(CH
as(CH)(CH
as(CH)(CH
3
3
3
3
) +
) +
) +
) +
m
m
m
m
as(CH)(CH
as(CH)(CH
as(CH)(CH
as(CH)(CH
2
2
2
2
)
)
)
)
5.42
3.07
2990
22.27 139.22 2987
7.98
68.56
0.00 250.46 2984
7.88 53.66 2977
19.75 118.42 2988
9.67
46.20
16.04 164.13 2985
8.44 47.64 2979
2984
s
s
s
s
(CH)(CH
(CH)(CH
(CH)(CH
(CH)(CH
3
3
3
3
) +
) +
) +
) +
m
as(CH)(CH
as(CH)(CH
as(CH)(CH
as(CH)(CH
2
)
)
)
)
1.11 2987
0.93 2984
19.37 2988
58.07 2985
m
m
m
2
2
2
2979 2974
2971
2975
2973
as(CH)(CH
3
) +
m
as(CH)(CH
2
)
(
60)
3
3
3
097
092
092
16.38 180.46 2977
b
a
b
2
2
1
3099
3093
3093
16.83 170.23 2979
2961
m
m
m
as(CH)(CH
as(CH)(CH
as(CH)(CH
3
3
3
) +
) +
) +
m
m
m
as(CH)(CH
as(CH)(CH
as(CH)(CH
2
2
2
)
)
)
0.00
11.10
68.84 2972
50.02 2972
2.64
11.15
72.49 2973
54.77 2973
2953
31)
2928
84)
2957
2956
2932
(
3
059
43.01 651.71 2941
a
1
3060
44.30 597.49 2942
63.44 105.25 2942
2930 2931
m
s
(CH)(CH
2
)
(
3059
3053
3053
3041
3041
3038
3038
1533
66.61
0.00
2.02
74.36 2941
0.62 2935
11.60 2935
b
2
a
2
b
1
a
1
b
2
b
1
a
2
a
1
3060
3054
3053
3041
3041
3039
3039
1533
2913
m
m
m
m
m
m
m
m
s
(CH)(CH
2
)
0.77
1.19
4.93 2936
6.98 2935
2907
2906
as(CH)(CH
as(CH)(CH
2
)
)
2900
2891
2869
2902 2895
2883 2886
2867 2870
2862
2
27.28 701.11 2923
27.35 647.97 2923
s
(CH)(CH
3
)
62.27
18.97
0.00
13.49 2923
0.02 2920
82.13 2920
52.44 1474
60.14
13.43
6.46
39.18 2923
30.41 2921
54.80 2921
50.31 1474
2868
2861
2847
1500
as(CH)(CH
as(CH)(CH
as(CH)(CH
3
3
3
)
)
)
2848
13.96
18.62
1505
1506
s
(C@N) + d(HCH)(CH
)
2 sciss.
(
21)(sh)
1495
12)
1
530
449.06
4.43 1471
b
2
1530
436.16
4.29 1471
1497 1498
1497
m
as(C@N) + d(HCH)(CH
2
)
sciss.
(
1
1
507
506
2.12
119.24
42.95 1449
6.40 1448
a
b
1
1507
1506
2.01
111.99
41.31 1449
5.71 1448
1488
1486 1481
1489
1483
d(HCH)(CH
d(HCH)(CH
3
) +
) +
m
m
s
(C@N)
as(C@N)
2
1485
18)
3
(
1
1
1
1
502
502
500
500
0.00
13.04
1.96
1.21 1444
3.92 1444
43.49 1442
9.23 1442
a
b
a
b
2
1
1
2
1502
1502
1500
1500
4.60
7.63
1.53
1.56
6.77 1444
4.43 1444
34.02 1442
13.58 1442
d(HCH)(CH
d(HCH)(CH
d(HCH)(CH
d(HCH)(CH
3
3
3
3
),(CH
),(CH
),(CH
),(CH
2
2
2
2
)
)
)
)
1466
1460
0.00
1458
30)
1451
33)
(
1
1
490
490
0.00
0.16
5.31 1432
4.84 1432
a
2
1
1490
1490
0.07
0.14
5.04 1432
4.70 1432
1450 1452
1441
d(HCH)(CH
3
3
),(CH
2
)
)
(
b
1447
d(HCH)(CH
),(CH
2
(
continued on next page)

1
24
A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
Table 2 (continued)
*
**
*
**
Wncalc
B3LYP
I
IR
I
R
Wncor
(C2v
Symm. Wncalc
B3LYP
I
IR
I
R
Wncor
IR
WnExp
(%T)
IR
DBA
Raman
WnExp
Raman
DBA
Assignment (internal coordinate)
(C2v
)
(C2v
)
)
(C
1
)
1
(C )
1
(C )
(
C
2v
)
1
(C )
1
482
0.00
8.12 1425
a
2
1482
0.69
8.85
9.14 1425
1434
1433 1436
1434
1383
d(HCH)(CH
3
),(CH
2
)
)
(
37)
1
1
482
473
8.66
15.82
20.62 1425
20.96 1416
b
a
1
1482
1472
20.14 1425
23.35 1415
1406 1391
1378 1376
d(HCH)(CH
d(HCH)(CH
3
),(CH
2
1
15.00
1376
71)
2
) +
) +
m
m
s
(C@N)
(
1
1
1
471
417
416
435.54
31.05
33.41
21.02 1414
31.15 1362
0.68 1361
b
2
a
1
b
2
1471
1417
1416
401.85
30.55
33.41
18.67 1414
29.83 1362
1.08 1361
d(HCH)(CH
d(HCH)(CH
d(HCH)(CH
2
3
3
as(C@N)
1371
1360 1363
1370
1363
),(CH
),(CH
2
)
)
1359
67)
1353
65)
1341
88)
2
(
1
1
411
411
0.00
3.54 1356
1.11 1356
a
2
1
1410
1410
6.31
6.55
2.24 1355
2.26 1355
1353
d(HCH)(CH
3
),(CH
),(CH
2
)
)
(
12.70
b
1349 1345
d(HCH)(CH
3
2
(
1
1
400
399
0.60
161.31
4.53 1346
1.18 1345
a
b
1
1400
1400
1.10
150.32
4.67 1346
1.06 1346
1330
1300 1305
d(HCH)(CH
d(HCH)(CH
3
),(CH
),(CH
2
) +
) +
m
m
s
(C@N)
as(C@N)
2
1300
88)
1294
75)
1273
13)
1266
27)
1213
52)
3
2
(
1383
1383
1341
1341
0.00
5.41
3.51 1329
0.00 1329
0.22 1289
21.05 1289
a
2
b
1
b
1
a
2
1383
1383
1341
1341
3.22
2.95
1.20 1329
1.70 1329
0.26 1289
20.85 1289
1293 1293
1277 1270
1268
1294
1271
1263
1218
d(HCH)(CH
3
),(CH
),(CH
2
)
)
(
d(HCH)(CH
3
2
(
44.32
0.00
44.15
0.06
das(HCH)(CH
3
),(CH
2
2
)
)
(
1213 1214
das(HCH)(CH
3
),(CH
(
1
1
1
315
311
236
2.71
422.69
91.37
63.12 1264
2.41 1260
0.19 1188
a
b
b
1
2
1
1315
1312
1235
2.77
402.97
92.86
63.22 1264
2.17 1261
0.21 1187
d(HCH)(CH
d(HCH)(CH
d(CNC) + d(HCH)(CH
3
),(CH
),(CH
2
) +
) +
m
m
),(CH
s
(C@N)
as(C@N)
1209
1199
3
2
1148
46)
1134
10)
1149 1149
1135 1137
3
2
)
(
1
234
0.00
3.96 1186
a
2
1233
0.18
4.72 1185
1173
d(CNC) + d(HCH)(CH
3
),(CH
2
)
(
1
1
174
173
1.35
142.16
8.18 1129
0.81 1128
a
b
1
1174
1172
1.92
138.44
9.23 1129
1.00 1127
1169
1152
d(HCH)(CH
d(HCH)(CH
3
),(CH
),(CH
2
) +
m
m
s
(C@N)
as(C@N)
2
1113
17)
1114 1108
1098
3
2
) +
(
1
1
109
109
10.04
39.10
7.64 1066
0.42 1066
a
b
1
1110
1109
11.55
47.97
6.68 1067
0.64 1066
d(HCH)(CH
d(HCH)(CH
3
),(CH
),(CH
2
)
)
1
1098
80)
3
2
(
1
1
109
109
0.00
60.54
0.60 1066
0.10 1066
a
b
2
1108
1108
18.35
27.24
0.78 1065
0.89 1065
1085
1077
d(HCH)(CH
d(HCH)(CH
3
),(CH
),(CH
2
) +
) +
m
m
as(CN)
as(CN)
2
1077
63)
1060
80)
1075 1078
1065
3
2
(
1
084
15.64
0.00 1042
6.98 1042
b
1
1084
15.98
0.03 1042
6.78 1041
1067
1050
q
(CH
(CH
3
)
)
(
1
1
084
015
0.00
1.20
a
a
2
1083
1015
0.01
7.42
1060
1013 1005
q
3
41.39
6.81
1.19
9.65
7.58
8.40
976
976
972
965
882
882
1
22.28
21.54
1.31
976
976
968
958
882
880
1014
88)
1001
77)
920
18)
914
74)
912
80)
880
97)
m
(CC) +
stretching)
(CC) + (CN) (NACH
stretching)
d(NCS) + d(CCS) +
m
(CN) (NACH
2
ACH
ACH
3
, ass.
, ass.
(
1
1
1
015
011
004
15.65
43.94
0.00
b
2
b
1
a
2
b
1
a
2
1015
1007
997
7.47
49.04
0.02
999
922
914
990
915
m
m
2
3
(
941
914
889
s
m
(CN)
(CN)
(
14.22
7.45
d(NCS)as + d(CCS) + m
(
9
9
18
20.38
0.00
918
23.92
0.00
q(CH
q(CH
q(CH
3
3
3
)
(
17
915
12.47
)
(
8
8
56
56
0.34
33.71
8.66
4.05
823
823
a
b
1
855
855
0.29
37.14
5.71
4.20
822
822
850
851
) +
q(CH
2
)
2
)
2
847
74)
844
q
(CH
3
) +
q
(CH
(
7
7
7
7
85
85
80
80
4.33
0.00
0.01
0.24
2.61
18.78
0.41
755
755
750
750
b
a
a
b
1
2
1
2
785
784
780
779
3.58
0.82
0.08
0.69
2.22
16.64
0.47
755
754
750
749
829
803
q
q
q
(CH
(CH
(CH
3
3
3
) +
) +
) +
q
q
q
(CH
(CH
(CH
2
2
2
)
)
)
804
785
602
585
791
785
20.06
17.96
785
82)
604
89)
582
70)
566
71)
556
73)
489
74)
782
607
592
579
560
3 2 twisting
d(HCH)(CH )wagging + d(HCH)(CH )
(
611
610
567
565
469
468
1.78
3.50
5.92
0.12
16.26
0.09
587
586
545
543
451
450
a
1
b
2
a
1
b
2
b
1
a
2
615
613
568
567
469
467
1.54
2.31
4.26
0.15
15.08
0.16
0.38
0.05
591
589
546
545
451
449
q(CH
q(CH
q(CH
q(CH
q(CH
q(CH
3
) +
3
) +
3
) +
3
) +
3
) +
3
) +
q(CH
q(CH
q(CH
q(CH
q(CH
q(CH
2
)
2
)
2
)
2
)
2
)
2
)
(
(
0.00
0.21
(
10.69
14.54
0.00
11.41
15.49
0.02
557
(
0.29
0.00
(

A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
125
Table 2 (continued)
*
**
*
**
Wncalc
B3LYP
I
IR
I
R
Wncor
(C2v
Symm. Wncalc
B3LYP
I
IR
I
R
Wncor
IR
WnExp
(%T)
IR
DBA
Raman
WnExp
Raman
DBA
Assignment (internal coordinate)
(C2v
)
(C2v
)
)
(C
1
)
1
(C )
1
(C )
(
C
2v
)
1
(C )
4
45
42
32
32
73
64
61
19
14
08
04
67
28
4.81
1.04
1.37
4.06
136.22
1.13
0.30
0.00
8.95
0.02
3.39
0.23
0.03
0.00
15.93
6.97
0.50
0.01
0.56
0.00
0.91
428
425
415
415
359
350
347
307
302
296
292
257
219
a
1
b
2
a
1
b
2
b
2
b
1
a
1
a
2
b
1
b
2
a
2
b
1
a
1
444
443
443
432
371
353
345
315
313
304
302
266
228
5.60
0.14
1.11
1.84
7.99
0.08
3.93
1.46
0.05
0.02
427
426
426
415
357
339
332
303
301
292
290
256
219
459
463
447
427
416
d(SCS)
s
(
73)
442
73)
435
73)
419
72)
397
69)
361
52)
4
4
4
3
3
3
3
3
3
3
2
2
d(SCS)as
d(CNC)
d(CNC)
(
434
421
(
(
146.43
1.61
0.20
0.01
7.00
3.77
0.01
0.33
0.00
396
361
354
36.7%
51.3%
m
m
as(CoS) + 15.8% d(SCS)
(
as(CoS) + 14.4% d(CoSC) + 8.9%
(
d(SCoS)
23.4%
d(SCS) + 18.1% d(SCN)
28.7% (CoS) + 17.4% d(NCS) + 17.2%
d(SCN) + 8.7% d(CoSC)
22.70
6.93
0.52
0.01
1.83
0.01
0.57
352
320
352
319
s
m (CoS) + 27.9% d(CoSC) + 19.7%
m
s
6.38
0.68
0.00
303
78)
280
68)
25.2% d(NCS) + 21.7% d(SCoS)ang + 11.2%
d(SCoS)lin
32.0% d(CSCo) + 17.5% d(SCoS) + 12.3%
d(SCS)
(
282
(
276
256
242
276
256
31.2%
s
m (CoS) + 28.2% d(CoSC) + 19.5%
d(CNC)
0.07
0.00
254
80)
224
71)
249
224
23.4% d(SCN) + 22.4% d(SCoS)ang + 11.5%
d(SCoS)lin
(
s(CH
3
)
(
2
2
28
25
0.00
0.18
0.32
0.07
219
216
a
b
2
225
223
0.11
0.01
0.11
0.40
216
214
s
s
(CH
(CH
3
)
)
2
202
81)
204
176
3
(
1
1
92
92
0.11
1.76
0.03
3.59
185
185
b
a
1
192
185
0.07
2.22
0.05
1.29
185
178
s(CH
3
)
1
178
79)
177
37.7% d(SCoS)lin + 16.7% d(SCoS)ang
(
1
1
1
1
1
9
8
8
6
4
4
3
2
1
67
61
51
34
04
5
6
5
0
5
4
2
7
5
1.94
0.00
0.00
1.40
0.00
0.22
1.30
0.19
2.77
0.00
0.00
0.20
0.00
3.50
11.09
1.02
0.22
3.51
0.03
0.15
1.92
4.07
1.49
0.00
0.25
0.04
0.35
0.47
161
155
145
129
100
91
83
82
58
43
a
1
a
2
b
2
a
1
a
2
b
2
b
1
a
1
b
1
b
2
a
2
b
1
a
2
a
1
161
158
151
134
95
94
86
84
59
42
42
33
28
1.15
1.06
0.00
1.35
0.26
0.44
0.98
0.22
2.73
0.07
0.02
0.25
0.01
3.46
5.65
2.43
0.19
3.72
0.24
0.03
2.24
3.82
1.27
0.32
0.09
0.05
0.24
0.34
155
152
145
129
91
90
83
81
57
40
40
32
27
163
145
118
163
150
s
s
s
s
s
(HCCH)(H
3
CACH
CACH
2
A)
A)
130
118
111
105
95
142
119
112
106
96
93
88
84
75
(HCCH)(H
3
2
(CCNC)(ACH
(CCNC)(ACH
(CCNC)(ACH
3
ACH
3
ACH
3
ACH
2
ANACH
2
ANACH
2
ANACH
2
2
2
A)
A)
A)
44.5% d(SCoS)lin
s
s
s
s
s
s
s
s
(CNCS)
(CCNC)(CH
(CNCS)
(CCNC)(CH
(CoSCN)
(CNCC)
87
75
66
54
3
ACH
2
ANACH
ANACH
2
A)
ꢀ)
3
ACH
2
2
42
31
26
14
64
(CNCC)
(SCNC)
14
13
m
: stretching mode. d: bending mode.
Calculated infrared intensities (IIR) are in Debye2 Å amu
Calculated Raman intensities (I ) are in Å amu .
R
s
: torsion mode.
q
: rocking mode.
*
ꢀ2
ꢀ1
.
**
4
ꢀ1
metrical parameters (PDGP) from the equilibrium position as de-
scribed in others works [35–38]. The PDGP can also be normalized
to obtain the percentage of participation of each internal vibra-
tional coordinate that describes the framework vibrations, at all
In the FT-IR spectrum, Fig. 2a, we visualize in the region between
3000 and 2850 cm large bands with four peaks at 2973, 2928,
ꢀ1
ꢀ
1
ꢀ1
2900, 2869 cm and two shoulders at 2955 and 2895 cm . In
the Raman spectrum, Fig. 2b, we visualize four well defined bands
ꢀ1
2
6 coordinates (10 stretching and 16 bending). Assuming C2v sym-
metry for the [Co(DDTC) ] complex, the vibrational irreducible rep-
resentation is vibrational = 28a + 25a + 25b + 27b , where a
at 2974, 2931, 2870 and 2848 cm . We obtained the second deriv-
ative spectrum followed by DBA to achieve the maximum of obser-
vable bands. We emphasize eight fundamental bands by this
procedure. Calculated and experimental wave numbers of the
ACH stretching are given in Table 2.
2
C
1
2
1
2
2
vibrational modes are not active in the infrared spectrum. There-
fore 105 vibrational modes are expected in the Raman spectrum,
1 1 2
from which 80 are infrared active (a , b and b ). The results with
and without symmetry were compatible with the experimental
data. The intensity variations between calculated and experimental
FT-IR results are related with the nature of the experimental mea-
sure in the solid state and the calculations carried out in the vac-
uum, neglecting molecular interactions.
3.3.2. C@N stretching
The C@N stretching bands were found in the FT-IR spectrum at
ꢀ
1
ꢀ1
1
1505 and 1495 cm and by DBA at 1506 and 1497 cm . In the FT-
ꢀ
Raman spectrum these bands were found at 1498 cm and by DBA
at 1500 and 1497 cm . These bands were assigned with support of
the calculated DFT vibrational spectrum. The comparison between
ꢀ1
3.3.1. CH stretching
In the [Co(DDTC)
2
] complex, there are four ACH
3
groups and
calculated and experimental values for the
m(C@N) stretching was
four ACH groups totalizing 20 stretching m(CH) vibrational modes.
2
excellent, showing that these modes are coupled among different

1
26
A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
internal coordinates. The scissoring d(HCH)(CH
pates in the description of these normal mode.
2
) mode partici-
ꢃ 359 corr. (b
CoS) + 15.8% d (SCS).
ꢃ 350 corr. (b ), 361 (exp.IR), 364 (DBA/IR): 51.3%
CoS) + 14.4% d(CoSC) + 8.9% d(SCoS).
ꢃ 347 corr. (a ): 354 (DBA/IR), 352(exp.R), 352(DBA/R): 23.4%
(CoS) + 27.9% d(CoSC) + 19.7% d(SCS) + 18.1% d(SCN).
ꢃ 307 corr. (a ): 320 (exp.R), 320 (DBA/R): 28.7%
(CoS) + 17.4% d(NCS) + 17.2% d(SCN) + 8.7% d(CoSC).
ꢃ 302 corr. (b ), 303 (exp.IR): 25.2% d(NCS) + 21.7% d(SCo-
S)ang + 11.2% d(SCoS)lin
ꢃ 296 corr. (b ), 280 (exp.IR), 282 (DBA/IR): 32.0%
d(CSCo) + 17.5% d(SCoS) + 12.3% d(SCS).
ꢃ 292 corr. (a ): 276 (exp.R), 276 (DBA/R): 31.2%
(CoS) + 28,2% d(CoSC) + 19,5% d(CNC).
ꢃ 257 corr. (b ), 254 (exp.IR), 249 (DBA/IR), 256 (exp.R), 256
DBA/R): 23.4% d(SCN) + 22.4% d(SCoS)ang + 11.5% d(SCoS)lin
), 178 (exp.IR), 176 (DBA/IR), 177 (exp.R):
2
), 397 (exp.IR), 396 (DBA/IR): 36.7%
m
as(-
1
mas(-
3
.3.3. HCH bending
In general terms, the HCH bending vibrations are considered as
characteristic wavenumbers. In the infrared spectrum, Fig. 2a, we
1
m
s
2
ꢀ1
can observe in the region between 1497 and 1040 cm , 28 bands
with support of DBA. In the Raman spectrum, Fig. 2b, we observe
m
s
1
2
6 bands with DBA support. These bands were assigned as HCH
.
bending and are listed in Table 2. The rocking vibrations in both
spectra were found in the region between 1060 and 785 cm with
the DBA support, and the assignments are also presented in Table
2
ꢀ1
2
2. A plot between bending and rocking experimental vibrations
m
s
versus the calculated modes give the following results: correlation
coefficients R = 0.9852, with SD = 22.24 for the bending and
R = 0.9926, with SD = 13.84 for the rocking vibrations.
1
(
.
ꢃ 185 corr. (a
1
3
7.7% d(SCoS)linear + 16.7% d(SCoS)Ang
.
2
ꢃ 91 corr. (b ), 95 (exp.IR), 96 (DBA/IR): 44.5% d(SCoS)linear.
3.3.4. Skeletal framework vibrations
The identification of the metal-ligand vibrations was not
straightforward as we have pointed out in other publications
35–38]. This is due to the higher mixture of the different internal
3
.3.5. Torsional vibrations
The characterization of these torsional modes using the DFT re-
[
coordinates that take part in the description of the normal modes.
Thus, we studied the distorted geometry of each normal mode,
observing the extension to which the equilibrium configuration
parameters are dislocated. This procedure helps us to assign the
low-energy bands.
In this approach, we used 10 stretching and 16 bending internal
coordinates, which are inside of the skeletal framework of the com-
plex in the description of the normal modes. The results presented
below obey the following nomenclature: in bold characters we
wrote (exp.IR) for experimental observation in the infrared spec-
trum, and (exp. R) for the Raman spectrum. The Deconvolution
Band Analysis was written concisely as (DBA/IR; R). The abbrevia-
tion corr., means that the calculated wave number by the
DFT:B3LYP/6-311G (d,p) procedure was scaled by 0.9613. The per-
centage (%) indicates the percentage variation of the bond lengths
and bond angle.
sults of the normal modes was rather complicated. To obtain an
approximate assignment of these normal modes, we used the 3D
computerized visualization. Eighteen torsional internal coordi-
nates were defined in [Co(DDTC) ]. From the infrared spectrum
2
we were able to associate 16 bands of weak intensity whose
description are given in Table 2.
2
3.4. Molecular orbitals for [Co(DDTC) ]
The ground states of the complex show many occupied molec-
ular orbitals, distributed between ꢀ5 and ꢀ10 eV in the vacuum.
Table 3 presents the DFT orbitals, the Koopmans’ energy and the
Mulliken analysis of the occupied orbitals. Plots of the low energy
occupied and virtual frontier orbitals in the ground state of
2
[Co(DDTC) ] are presented in Fig. 6.
Table 3
2
Koopmans’ energy (eV), Mulliken population analysis and assignment for the frontier orbitals of [Co(DDTC) ], with the B3LYP method.
Orbital
Symm.
Energy (eV)
B3LYP Alpha
Orbital
Symm.
Energy (eV)
B3LYP Beta
Mulliken population
Mulliken population
ꢂ
ꢂ
L + 11
L + 10
L + 9
L + 8
L + 7
L + 6
L + 5
L + 4
L + 3
L + 2
b
a
a
b
a
b
a
b
a
b
1
2
1
2
1
1
1
2
1
2
1.86
1.85
1.68
1.52
1.30
1.25
0.96
0.92
0.40
ꢀ0.73
r
r
r
r
r
r
r
r
[Ethyl 93.1%]
[Ethyl 97.7%]
[Ethyl 89.7%]
[Ethyl 85.0%]
+ Co 4s [Co 55.6%; Ethyl 54.8%]
[S 62.3%; C 18.6%; Ethyl 16.9%]
+ Co 4s [Ethyl 48.2%; Co 22.8%; S 18.8%]
[Ethyl 91.9%]
L + 11
L + 10
L + 9
L + 8
L + 7
L + 6
L + 5
L + 4
L + 3
L + 2
a
a
b
a
b
a
b
a
b
b
2
1
2
1
1
1
2
1
1
2
1.86
1.69
1.52
1.32
1.24
0.96
0.92
0.43
r
r
r
r
r
r
r
[Ethyl 97.1%]
[Ethyl 89.0%]
[Ethyl 84.6%]
+ Co 4s [Co 56.3%; Ethyl 53.9%]
[S 62.5%; C 18.7%; Ethyl 16.6%]
+ Co 4s [Ethyl 49.8%; Co 20.7%; S 19.7%]
[Ethyl 91.9%]
CAH
ꢂ
CAH
ꢂ
CAH
ꢂ
CAH
ꢂ
CAH
ꢂ
CAH
ꢂ
CAH
ꢂ
CAH
ꢂ
CAH
ꢂ
SAC
ꢂ
SAC
ꢂ
CAH
ꢂ
CAH
ꢂ
CAH
ꢂ
p
[S 57.0%; Co 20.7%; Ethyl 23.1%]
CAH
SACo
ꢂ
p
p
p
[S 56.7%; Co 22.3%]
ꢀ0.62
Co 3d [Co 94.0%]
SACo
ꢂ
ꢂ
[C 46.5%; S 30.9%]
ꢀ0.72
p
[C 45.7%; S 31.6%]
SAC@
N
SAC@
N
ꢂ
L + 1
a
1
2
ꢀ1.19
ꢀ1.58
[C 47.7%; S 29.3%]
N
L + 1
a
2
1
ꢀ0.80
ꢀ1.20
Co 3d [Co 60.9%; S 36.7%]
SAC@
ꢂ
LUMO
a
Co 3d [Co 52.2%; S 45.9%]
LUMO
a
p
[C 47.5%; S 29.6%]
SAC@
N
HOMO
H-1
H-2
H-3
H-4
H-5
H-6
H-7
H-8
b
2
a
1
b
1
a
2
b
1
a
1
b
2
a
1
b
2
a
2
b
1
a
1
ꢀ5.57
ꢀ5.88
ꢀ5.96
ꢀ6.16
ꢀ6.37
ꢀ7.02
ꢀ7.22
ꢀ7.24
ꢀ7.42
ꢀ7.70
ꢀ8.17
ꢀ9.10
Co 3d [Co 67.4%; S 15.2%]
Co 3d [Co 95.5%]
HOMO
H-1
H-2
H-3
H-4
H-5
H-6
H-7
H-8
b
2
a
1
a
2
b
1
b
1
a
1
a
1
b
2
a
2
b
2
a
1
a
2
ꢀ4.96
ꢀ5.21
ꢀ6.12
ꢀ6.42
ꢀ6.59
ꢀ6.64
ꢀ7.01
ꢀ7.12
ꢀ7.38
ꢀ7.43
ꢀ9.06
ꢀ9.64
Co 3d [Co 79.6%]
Co 3d [Co 95.7%]
p
p
p
p
r
S
S
S
S
[S 78.9%; Co 19.5%]
[S 98.4%]
[S 95.9%]
p
p
p
S
S
S
[S 98.5%]
[S 95.8%]
[S 94.7%]
[S 47.9%; N 36.4%]
Co 3d [Co 94.6%]
S
[S 48.0%; N 36.4%; Ethyl 14.1%]
CoAS [S 54.5%; Co 16.1%. N 16.4%]
Co 3d [Co 93.2%]
CoAS [S 61.0%; Co 13.6%; N 14.2%]
CoAS [S 62.6%; Co 32.3%]
Co 3d [Co 79.9%; S 19.8%]
CoAS [S 68.9%; Co 20.7%]
p
r
r
r
r
r
CoAS [S 41.1%; N 29.7%; Co 14.5%]
CoAS [S 70.4%; Co 25.8%]
CoAS [S 81.8%]
CoAS [S 72.0%; Co 17.9%]
SAC [S 44.7%; C 22.3%; Ethyl 21.2%]
r
r
H-9
H-10
H-11
H-9
H-10
H-11
r

A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
127
(α)
(α)
(β)
(β)
Fig. 6. Orbital representation of the HOMO (a), HOMO (b), LUMO (a) and LUMO (b), at PBE1PBE method of [Co(DDCT)
2
]. The contour values of the orbitals are all 0.02 a.u.
The Koopmans’ energy difference between the highest occupied
and the lowest unoccupied orbitals, HOMO(b)–LUMO( ) gap, was
.38 eV for the B3LYP and 4.05 eV for the PBE1PBE. For both calcu-
a
3
lations, HOMO(b) orbital (b
2
symmetry) was characterized by 3d
) orbital (a symmetry) was
metal (ꢄ76% to 79%). The LUMO(
a
2
characterized by 3d metal (ꢄ52%) with the participation of the sul-
ꢂ
fur (46%) and could be interpreted as
r
. The orbital energies
CoAS
were similar in both methods. However, we see that the energy
of the PBE1PBE orbitals is a few tenths higher than the B3LYP re-
sults. This is probably due to variations in methods and is also no-
ticed for the HOMO–LUMO gap. Other orbitals are shown in Fig. 7.
ꢂ
Also, the
p
S
and p orbitals are identified in the same order in
SAC@N
this figure.
The participation of the metal orbitals were consistent with the
evaluation of multiplicity adopts for d7 cobalt (II), duplet for one
unpaired electron. This was confirmed by Mulliken atomic spin
density analysis, which found a concentration of spin density on
the metal, and compatible with the value of an unpaired electron.
Fig. 2S describes the representation of the total spin density for
B3LYP results, indicating low participation of spin density on the
sulfur atoms of the DDTC ligand.
The analysis of the molecular orbitals obtained with the CPCM
methodology, which incorporate the solvent effect, present some
differences of HOMO–LUMO energy in both methods. However,
the order of the frontier orbitals was not changed. This is clear
by the analysis of the molecular orbital diagram obtained with
the calculation carried out in MeCN, as displayed in Fig. 3S. The
variation in the HOMO(b)–LUMO(
.28 and 3.97 eV for B3LYP and PBE1PBE, respectively.
From the final analysis obtained through the density of states, it
is possible to rationalize the valence electronic structure of
Co(DDTC) ]. These results are shown in Table 3S and Fig. 8, where
a) gap with solvent, was of
3
[
2
the degree of positive/negative overlap for frontier orbitals was
detached in the OPDOS diagram. The frontier orbitals are popu-
lated by non-bonding orbitals, representing the isolated electron
2
Fig. 7. Energy levels diagrams of [Co(DDTC) ], with SCF molecular orbitals within
the PBE1PBE and B3LYP methods.

1
28
A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
PBE1PBE
Beta
PBE1PBE
0,2
0,1
0,0
Alpha
0
0
0
,2
,1
,0
-
0,1
0,2
0,3
0,4
0,5
-
-
0,1
0,2
-0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
1,1
1,2
1,3
1,4
1,5
1,6
1,7
1,8
-
-
S and Co
S and C=N
C=N
-
S and Co
S and C=N
C=N
-
-
-0,6
-0,7
-
-
-
0,8
0,9
1,0
1,1
1,2
1,3
-
-
-
-
-
-
-
-
-
-
-
-
-1,4
-1,5
-1,6
-1,7
-1,8
-
-
-
-
-
Ethyl
Total
Ethyl
Total
4
2
0
4
2
0
N (C=N)
N (C=N)
C (C=N)
Co
S
C (C=N)
Co
S
HOMO
LUMO
HOMO
LUMO
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
Energy (eV)
Energy (eV)
B3LYP
Beta
B3LYP
Alpha
0
,2
0
0
0
,2
,1
,0
0,1
0,0
-
-
-
-
0,1
0,2
0,3
0,4
-0,1
-0,2
-0,3
-0,4
-0,5
-0,6
-0,7
-0,8
-0,9
-1,0
-1,1
-1,2
-1,3
-1,4
-1,5
-1,6
-1,7
-1,8
S and Co
S and C=N
C=N
S and Co
S and C=N
C=N
-0,5
-0,6
-0,7
-0,8
-0,9
-1,0
-1,1
-1,2
-1,3
-1,4
-1,5
-1,6
-1,7
-1,8
Ethyl
Total
N (C=N)
C (C=N)
Co
Ethyl
Total
4
2
0
4
2
0
N (C=N)
C (C=N)
Co
S
S
HOMO
LUMO
HOMO
LUMO
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
Energy (eV)
Energy (eV)
2
Fig. 8. Molecular orbital diagram, density of states diagram (DOS) and orbital overlap population diagram (OPDOS) of the [Co(DDTC) ] complex, with the PBE1PBE and B3LYP
methods.
ꢂ
of sulfur (
firmed by the negative values and
p
S
) and d metal orbitals. The
p
orbitals are con-
3.5. Natural bond orbital analysis (NBO)
SAC@
N
r
CoAS are confirmed by the po-
sitive values. This analysis was important, especially to evaluate
the nature of the electronic valence transitions.
NBO analysis [39], at the B3LPY/6-311G (d,p) and PBE1PBE/6-
311G (d,p) level were carried out to rationalize the factors contrib-

A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
129
Table 4
B3LYP/6-311G(d,p) donor–acceptor interactions between orbitals and stabilization energy (kcal/mol).
Donor orbital number
Description
Acceptor orbital number
Description
Stabilization energy (kcal/mol)
Alpha electrons
1
2
BD (1)Co1AS8
BD (1)Co1AS9
LP (2) S8
451
451
452
452
100
100
450
449
472
469
472
469
BDꢂ(1) C2AN3
BDꢂ(1) C2AN3
BDꢂ(2) C2AN3
BDꢂ(2) C2AN3
RYꢂ(4)Co1
5.51
5.51
25.22
25.22
6.36
8
8
0
9
LP (2) S9
4
4
49
50
BDꢂ(1)Co1AS8
BDꢂ(1)Co1AS9
LP (2) S10
LP (3) S11
LP (2) S10
LP (2) S11
LP (3) S11
LP (1) N13
RYꢂ(7)Co1
6.36
8
9
8
9
9
9
9
5
9
1
2
3
BDꢂ(1)Co1AS9
BDꢂ(1)Co1AS8
BDꢂ(1) C12AN13
BDꢂ(1) S10AC12
BDꢂ(1) C12AN13
BDꢂ(1) S10AC12
36.55
36.54
6.00
30.75
6.00
54.24
Beta electrons
1
2
2
BD (1)Co1AS8
BD (1)Co1AS9
BD (1) S8AS9
BDꢂ(1)Co1AS8
BDꢂ(1)Co1AS9
BDꢂ(1) C2AN3
LP (2) S10
LP (2) S11
BD (1) S10AS11
LP (2) S10
451
451
452
99
BDꢂ(1) C2AN3
BDꢂ(1) C2AN3
BDꢂ(2) C2AN3
RYꢂ(6)Co1
5.67
5.67
59.23
5.60
5.60
5.90
34.64
34.64
59.23
6.12
6.12
5.90
2
4
4
4
49
50
51
4
6
4
4
6
99
RYꢂ(6)Co1
125
450
449
472
471
471
271
RY (1) C2
9
9
2
9
9
BDꢂ(1)Co1AS9
BDꢂ(1)Co1AS8
BDꢂ(2) C12AN13
BDꢂ(1) C12AN13
BDꢂ(1) C12AN13
RYꢂ(1) C12
LP (2) S11
BDꢂ(1) C12AN13
4
71
BD for 2-center bond, LP for 1-center valence lone pair, RYꢂ for 1-center Rydberg, and BDꢂ for 2-center antibond, the unstarred and starred labels corresponding to Lewis and
non-Lewis NBOs, respectively.
Table 5
PBE1PBE/6-311G(d,p) donor–acceptor interactions between orbitals and stabilization energy (kcal/mol).
Donor orbital number
Description
Acceptor orbital number
Description
Stabilization energy (kcal/mol)
Alpha electrons
1
2
BD (1)Co1AS8
BD (1)Co1AS9
LP (2) S8
451
451
452
452
86
99
86
99
450
449
472
469
472
469
BDꢂ(1) C2AN3
BDꢂ(1) C2AN3
BDꢂ(2) C2AN3
BDꢂ(2) C2AN3
LPꢂ(7) Co1
5.94
5.94
27.37
27.37
5.49
6.00
5.49
6.00
39.77
39.76
6.56
33.18
6.55
8
8
0
9
LP (2) S9
4
4
4
4
49
49
50
50
2
5
2
4
5
6
BDꢂ (1) Co1AS8
BDꢂ (1) Co1AS8
BDꢂ (1) Co1AS9
BDꢂ (1) Co1AS9
LP (2) S10
LP (3) S11
LP (2) S10
LP (2) S11
LP (2) S11
RYꢂ(3) Co1
RYꢂ(3) Co1
RYꢂ(3) Co1
9
9
9
9
9
9
BDꢂ(1)Co1AS9
BDꢂ(1)Co1AS8
BDꢂ(1) C12AN13
BDꢂ(1) S10AC12
BDꢂ(1) C12AN13
BDꢂ(1) S10AC12
LP (1) N13
57.34
Beta electrons
1
2
2
BD (1)Co1AS8
BD (1)Co1AS9
BD (1) S8AS9
BD (1) C2AN3
LP (5) Co1
LP (5) Co1
BD (1) S10AS11
LP (2) S10
LP (2) S11
LP (2) S10
LP (2) S11
BDꢂ(1) C12AN13
451
451
452
125
244
261
472
450
449
471
471
271
BDꢂ(1) C2AN3
BDꢂ(1) C12AN3
BDꢂ(2) C2AN3
RYꢂ(1) C2
6.12
6.12
65.13
7.12
5.17
5.17
65.13
37.32
37.32
6.69
6.69
7.12
2
4
51
8
8
2
9
9
9
9
6
6
4
4
6
4
6
RYꢂ(8) S10
RYꢂ(8) S11
BDꢂ(2) C12AN 13
BDꢂ(1)Co1AS9
BDꢂ(1)Co1AS8
BDꢂ(1) C12AN13
BDꢂ(1) C12AN13
RYꢂ(1) C2
4
71
BD for 2-center bond, LP for 1-center valence lone pair, RYꢂ for 1-center Rydberg, and BDꢂ for 2-center antibond, the unstarred and starred labels corresponding to Lewis and
non-Lewis NBOs, respectively.
uting to the total conformational energy. Using B3LYP/6-311G (d,p)
93.75% p and 0.15% d) orbital on the sulfur atom; for beta electrons,
the Co(1)AS(8) bond is formed by interaction between a sp0
.03 1.10
d
procedure, for alpha electrons, the Co(1)AS(8) bond is formed by
interaction between a sp0
.03
d
1.09
(47.12% s, 1.49% p and 51.38% d)
(46.74% s, 1.60% p and 51.65% d) orbital centered on the cobalt ion
1
5.37 0.02
12.20 0.02
orbital centered on the cobalt ion and a sp
d
(6.10% s,
and a sp
d
(7.56% s, 92.29% p and 0.14% d) orbital on the sul-

1
30
A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
Table 6
Main singlet transition energies (eV) and the oscillator strength from the ground state of the [Co(DDTC)
2
] complex, with the PBE1PBE and B3LYP methods.
State
PBE1PBE
B3LYP
Dominant configurationꢂ
HOMO(A) ? LUMO(A) (35%)
H-5(B) ? L + 3(B) (59%)
Wavelength (nm)
1039
Oscillator strength
0.0000
State
Dominant configurationꢂ
HOMO(A) ? LUMO(A) (38%)
H-5(B) ? L + 3(B) (62%)
Wavelength (nm)
Oscillator strength
0.0000
B
1
B
1
1047
745
A
A
2
2
H-7(A) ? LUMO(A) (38%)
H-5(B) ? L + 2(B) (71%)
796
654
0.0000
0.0000
H-7(A) ? LUMO(A) (26%)
H-5(B) ? L + 1(B) (64%)
A
2
2
0.0000
H-7(A) ? LUMO(A) (33%)
H-2(A) ? LUMO(A) (26%)
H-7(A) ? LUMO(A) (43%)
H-1(A) ? LUMO(A) (21%)
A
647
629
0.0000
0.0000
B
B
1
2
H-5(B) ? L + 3(B) (48%)
627
508
0.0000
0.0001
B
1
H-5(B) ? L + 3(B) (48%)
H-10(A) ? LUMO(A) (31%)
H-1(A) ? LUMO(A) (68%)
H-10(A) ? LUMO(A) (25%)
H-2(A) ? LUMO(A) (74%)
B
2
B
2
B
2
535
452
364
0.0001
0.0225
0.0512
B
B
B
2
2
2
HOMO(B) ? LUMO(B) (91%)
HOMO(A) ? L + 1(A) (79%)
H-4(A) ? LUMO(A) (79%)
415
337
314
0.0221
0.0630
0.1622
HOMO(B) ? LUMO(B) (94%)
HOMO(A) ? L + 1(A) (85%)
H-4(A) ? LUMO(A) (77%)
H-3(B) ? L + 1(B) (20%)
B
2
337
0.1248
B
1
H-1(A) ? L + 1(A) (22%)
H-3(B) ? LUMO(B) (24%)
280
0.0156
H-6(A) ? LUMO(A) (19%)
H-2(A) ? L + 1(A) (22%)
H-2(B) ? L + 2(B) (17%)
B
B
B
1
1
2
294
280
258
0.0118
0.0100
0.0280
B
B
B
1
2
1
H-6(A) ? LUMO(A) (53%)
H-3(A) ? L + 2(A) (19%)
263
253
246
0.0174
0.0235
0.0234
H-6(A) ? LUMO(A) (57%)
H-3(A) ? L + 2(A) (19%)
H-3(B) ? L + 2(B) (26%)
H-2(B) ? L + 3(B) (69%)
HOMO(A) ? L + 3(A) (21%)
H-5(B) ? L + 2(B) (51%)
H-4(B) ? LUMO(B) (55%)
H-3(A) ? L + 2(A) (30%)
H-9(B) ? L + 1(B) (21%)
H-2(B) ? L + 2(B) (28%)
B
1
2
255
254
0.0491
0.7403
B
B
1
2
H-3(A) ? L + 2(A) (27%)
H-2(B) ? L + 1(B) (38%)
241
237
0.0491
0.7388
B
H-3(B) ? L + 1(B) (51%)
H-3(B) ? L + 2(B) (44%)
H-2(B) ? L + 3(B) (15%)
HOMO(A) ? L + 3(A) (18%)
H-8(B) ? L + 3(B) (28%)
H-5(B) ? L + 2(B) (29%)
B
2
2
252
227
0.0712
0.1666
B
B
2
2
H-8(A) ? L + 1(A) (16%)
H-6(A) ? L + 1(A) (36%)
236
234
0.0744
0.0610
H-7(A) ? L + 2(A) (31%)
H-7(B) ? LUMO(B) (20%)
B
H-6(A) ? L + 1(A) (16%)
H-8(B) ? L + 3(B) (42%)
B
B
1
2
H-7(B) ? L + 2(B) (80%)
220
216
0.0139
0.3227
H-8(A) ? L + 1(A) (32%)
H-9(B) ? LUMO(B) (21%)
H-7(B) ? LUMO(B) (25%)
A
1
HOMO(B) ? L + 5(B) (77%)
215
214
0.0010
0.0126
B
1
H-4(A) ? L + 3(A) (43%)
H-3(B) ? L + 4(B) (31%)
A = alpha.
B = beta.
fur atom. The occupancy of the alpha and beta electrons in the
Co(1)AS(8) bond was 1.93 electrons. The polarization coefficient
for the formation of the bonding was 19.29% on the cobalt ion
and 80.71% on the sulfur atom of the Co-S bond.
Using PBE1PBE/6-311G (d,p) procedure, for the alpha electrons,
the Co(1)AS(8) bond was formed by interaction between a
Results obtained by the methods DFT/B3LYP e DFT/PBE1PBE
showed one bridge interaction with one electron of occupancy
between the 3pz orbitals from the sulfur atoms of the diethyldithio-
carbamate anion. The description of this interaction follows as
procedure: NBO/B3LYP; S(8)AS(9) bridge with 0.70732 electrons
0
1 0
occupancy giving an hybrid orbital s p d with 99.96% orbital p par-
ticipation without appreciable polarization between the two sulfur
atoms. The same results were found for the S(10)AS(11) interac-
tion. In the PBE1PBE procedure, the occupancy was of 0.703736
electrons for the S(8)AS(9) and S(10)AS(11) interactions between
0
.03 1.09
sp
the cobalt ion and a sp
orbital on the sulfur atom; for beta electrons, the Co(1)AS(8) bond
d
(47.15% s, 1.64% p and 51.20% d) orbital centered on
1
4.52 0.03
d
(6.43% s, 93.40% p and 0.16% d)
was formed by interaction between a sp0
and 51.38% d) orbital centered on the cobalt ion and a sp
7.96% s, 91.89% p and 0.15% d) orbital on the sulfur atom. The
.04 1.10
d
(46.85% s, 1.76% p
1
1.54 0.02
d
the p orbitals. For C(2)@N(3) and C(12)@N(13) double bonds, the
CN = 0.6069(sp1
.85
(
molecular orbital can be described as
r
d
C
) +
1
.68
99.99 0.97
99.99
sum of the alpha and beta electrons occupancy was 1.93. The
polarization coefficient for the formation of the bonding was
0.7948(sp
)
N
and
p
CN = 0.5181(sp
C
) + 0.8553(sp
0
.32
d
) , with occupancy of 1.972 alpha electrons. For the beta
N
1
9.37% on the cobalt ion and 80.63% on the sulfur atom of the CoAS
electrons, the orbital wave function can be described as
r
CN
99.99 16.80
=
+
1
.82
1.68
bond. In both cases, the results showed a higher polarization
through the sulfur atom indicating a strong ionic character for
the bond, and little difference in the hybrid bond description.
0.6067(sp
0.8557(sp
)
C
+ 0.7949(sp
)
N
and
p
CN = 0.5175(sp
d
)
C
9
9.99 0.31
d
N
) , with occupancy of 1.972 beta electrons. The
polarization coefficients for the C and N atoms were of 31.83% for

A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
131
Table 7
Main singlet transition energies (eV) and the oscillator strength from the ground state of the [Co(DDTC)
2
] complex, with the PBE1PBE and B3LYP -CPCM methods.
State
PBE1PBE (MeCN)
B3LYP (MeCN)
Dominant configuration
Wavelength (nm)
1098
Oscillator strength
0.0000
State
Dominant configuration
Wavelength (nm)
1104
Oscillator strength
B
1
HOMO(A) ? LUMO(A) (38%)
H-4(B) ? L + 3(B) (45%)
B
1
HOMO(A) ? LUMO(A) (41%)
H-4(B) ? L + 3(B) (49%)
0.0000
0.0000
0.0000
A
A
2
2
H-7(A) ? LUMO(A) (32%)
H-4(B) ? L + 2(B) (63%)
858
713
0.0000
0.0000
A
A
2
2
H-1(A) ? LUMO(A) (23%)
H-4(B) ? L + 1(B) (50%)
805
696
H-7(A) ? LUMO(A) (39%)
H-1(A) ? LUMO(A) (20%)
H-7(A) ? LUMO(A) (51%)
H-4(B) ? L + 1(B) (27%)
B
B
1
2
H-4(B) ? L + 3(B) (63%)
631
518
0.0000
0.0001
B
B
1
2
H-4(B) ? L + 3(B) (63%)
632
546
0.0000
0.0001
H-10(A) ? LUMO(A) (33%)
H-2(A) ? LUMO(A) (66%)
H-10(A) ? LUMO(A) (27%)
H-2(A) ? LUMO(A) (72%)
B
B
B
2
2
1
HOMO(B) ? LUMO(B) (93%)
HOMO(A) ? L + 1(A) (82%)
422
346
316
0.0471
0.1718
0.0236
B
2
HOMO(B) ? LUMO(B) (96%)
H-1(B) ? LUMO(B) (100%)
HOMO(A) ? L + 1(A) (90%)
460
429
371
0.0487
0.0052
0.1362
A
1
H-3(A) ? L + 2(A) (20%)
H-2(A) ? L + 1(A) (64%)
B
2
B
B
B
2
2
2
H-4(A) ? LUMO(A) (94%)
H-1(A) ? L + 2(A) (54%)
313
285
282
0.2957
0.0110
0.0125
B
B
B
2
1
1
H-4(A) ? LUMO(A) (92%)
H-2(A) ? L + 1(A) (72%)
H-6(A) ? LUMO(A) (38%)
335
327
290
0.2552
0.0272
0.0171
H-1(A) ? L + 2(A) (26%)
H-6(B) ? L + 1(B) (11%)
HOMO(B) ? L + 4(B) (17%)
B
1
H-6(A) ? LUMO(A) (16%)
H-2(A) ? L + 1(A) (18%)
H-5(B) ? LUMO(B) (24%)
H-2(B) ? L + 1(B) (26%)
276
0.1195
B
1
H-4(A) ? L + 1(A) (40%)
H-3(B) ? LUMO(B) (38%)
289
0.0238
B
1
H-6(A) ? LUMO(A) (60%)
265
0.1173
B
1
H-6(A) ? LUMO(A) (32%)
H-4(A) ? L + 1(A) (25%)
284
0.0393
B
B
B
1
2
1
H-8(A) ? LUMO(A) (78%)
H-3(B) ? L + 2(B) (89%)
H-3(A) ? L + 2(A) (69%)
255
249
242
0.0922
0.7362
0.1704
B
B
B
1
1
2
H-3(B) ? LUMO(B) (35%)
H-8(A) ? LUMO(A) (72%)
281
270
270
0.0465
0.0930
0.2523
H-3(B) ? L + 1(B) (59%)
H-2(B) ? L + 3(B) (37%)
B
B
B
B
B
2
2
2
2
2
H-5(B) ? L + 2(B) (84%)
241
236
236
234
231
0.0389
0.1968
0.1749
0.0213
0.0537
B
B
B
B
B
2
2
2
1
2
H-3(B) ? L + 1(B) (26%)
H-2(B) ? L + 3(B) (56%)
264
263
261
256
242
0.5216
0.0275
0.1655
0.1860
0.0782
H-2(B) ? L + 3(B) (41%)
HOMO(B) ? L + 5(B) (42%)
HOMO(A) ? L + 3(A) (86%)
H-5(B) ? L + 1(B) (78%)
H-3(A) ? L + 2(A) (64%)
H-2(B) ? L + 3(B) (45%)
HOMO(B) ? L + 5(B) (45%)
H-8(A) ? L + 1(A) (33%)
H-6(A) ? L + 1(A) (37%)
H-9(B) ? LUMO(B) (35%)
H-7(B) ? LUMO(B) (23%)
H-8(A) ? L + 1(A) (46%)
H-6(A) ? L + 1(A) (37%)
B
B
2
1
H-8(B) ? L + 3(B) (78%)
227
225
0.0563
0.0296
B
B
1
2
H-7(B) ? L + 1(B) (88%)
242
240
0.0392
0.1442
H-2(A) ? L + 3(A) (30%)
H-7(B) ? L + 2(B) (54%)
H-9(B) ? LUMO(B) (44%)
H-7(B) ? LUMO(B) (29%)
B
B
1
2
H-2(A) ? L + 3(A) (55%)
H-7(B) ? L + 2(B) (32%)
224
223
0.0222
0.3358
B
B
2
1
H-8(A) ? L + 1(A) (28%)
H-9(B) ? LUMO(B) (42%)
232
227
0.3728
0.0728
H-8(A) ? L + 1(A) (27%)
H-9(B) ? LUMO(B) (42%)
H-9(B) ? L + 1(B) (29%)
H-6(B) ? L + 3(B) (66%)
B
B
1
1
H-1(B) ? L + 6(B) (95%)
220
213
0.0129
0.2074
H-4(A) ? L + 3(A) (27%)
H-9(B) ? L + 2(B) (41%)
H-3(B) ? L + 4(B) (19%)
A = alpha.
B = beta.
carbon and 68.17% for nitrogen. This shows a strong polarization
directed toward the N atom. Similar results were found through
the B3LYP procedure. For C(2)AS(8) bond, the molecular orbital
electrons. The polarization coefficients for the C and S atoms were
of 75.00% for carbon and 43.74% for sulfur. This shows a little polar-
ization directed toward the C atom. Considering the similarity of
the electronegativities in the C and S atoms, the slight polarization
toward the carbon atom can be justified by the inductive effect pro-
duced by the vicinal C@N bond. Similar results were found through
the PBE1PBE procedure.
CS = 0.7494(sp2
.09
)
C
+ 0.6622(sp
4.26
can be described as
occupancy of 0.99147 for alpha electrons. For the beta electrons,
CS
the orbital wave function can be described as r =
r
S
) , with
2
.10
4.15
0
.7500(sp
)
C
+ 0.6614(sp
S
) , with occupancy of 0.99167 beta

1
32
A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
3.5.1. Donor–acceptor interactions: Second Order Perturbation Theory
Analysis of the Fox Matrix in NBO basis
A filled bonding or lone pair orbital can act as an electronic den-
sity donor. Conversely, an empty or filled bonding, anti-bonding
orbital can act as an electronic density acceptor. The strength
and weakness of bonds can be studied through these interactions.
Tables 4 and 5 listed the donor and acceptor orbitals, electron
ꢀ1
ꢀ1
occupancies and energy in kcal mol , higher than 5.0 kcal mol
.
The more representative interactions in the NBO/B3LYP calcula-
tions are between the orbitals: LP(1)N 13 to BDꢂ(1) S10AC12; LP
(
2) S10 to BDꢂ(1) Co1AS9; LP (3) S11 to BDꢂ(1) Co1AS8, with sta-
ꢀ1
bilization energy of 54.24, 36.55 and 36.54 kcal mol for alpha
electrons, respectively. For beta electrons, the more representative
interactions are between the orbitals BD (1) S8AS9 to BDꢂ(2)
C2AN3; LP (2) S10 to BDꢂ(1) Co1AS9; BD (1) S10AS11 to BDꢂ(2)
C12AN13, with stabilization energy of 59.23, 34.64, 34.64 and
ꢀ1
5
9.23 kcal mol , respectively. For NBO/PBE1PBE, representative
interactions were found between the orbitals: LP(2) S8 to BDꢂ(2)
C2AN3; LP (2) S9 to BDꢂ(2) C2AN3; LP (2) S10 to BDꢂ(1) Co1AS9;
LP (3) S11 to BDꢂ(1) Co1AS8; LP(2) S11 to BDꢂ(1) S10AC12 and LP
Fig. 9. UV–Vis TD-PBE1PBE, TD-B3LYP, TD-PBE1PBE–CPCM and TD-B3LYP-CPCM
simulated spectra (190–900 nm) of [Co(DDTC) ], using the GaussSun program.
2
(
1) N13 to BDꢂ(1) S10AC12 with stabilization energy of 27.37,
ꢀ1
2
7.37, 39.77, 39.77, 33.18 and 57.34 kcal mol for alpha electrons,
and dmio were studied by various singlet states with multi-config-
uration character using TD methods. This characteristic was also
respectively. For beta electrons, representative interactions are be-
tween the orbitals: BD (1) S8AS9 to BDꢂ(2) C2AN3; BD (1)
S10AS11 to BDꢂ(2) C12AN13; LP (2) S10 to BDꢂ(1) Co1AS9; LP
2
observed for the data obtained in [Co(DDTC) ] by the analysis of
the coefficients of the dominant configuration.
(
6
2) S11 to BDꢂ(1) Co1AS8, with stabilization energy of 65.13,
Fig. 9 shows a comparison between the simulated data in solu-
tion and in vacuum. Also the two different DFT methods were com-
pared and showed a delay of 19 nm. CPCM values were more
realistic when compared to the intensity of the experimental data
in the Fig. 3. The data obtained in the deconvolution of experimen-
tal spectra in Fig. 4, were used in comparison with theoretical data.
Thus, the following discussion will be carried:
ꢀ1
5.13, 37.32 and 37.32 kcal mol , respectively.
3.6. Electronic UV–Visible spectra
Calculations of the transition energies and the oscillator
strengths in the UV–Vis spectra of the optimized structures with
2v symmetry were realized with TD and TD-CPCM methods, using
C
orbitals calculated with PBE1PBE and B3LYP. These calculations
were carried out considering 70 singlet states and the results are
presented in Fig. 4S and 5S as Supplemental material. Data from
states with oscillator strengths greater than 0.01 a.u. are shown
in a reduced form in Tables 6 and 7. The analysis of the states
and the simulation of the spectra were carried out using the the
Chemcraft and GaussSum programs, and the obtained results are
presented in Fig. 9. The first three calculated states were assigned
as d ? d transitions, with negative values indicating effect of spin
contamination for those excited states due to triplet coupled single
excitations. However, this did not interfere in the evaluation of
other calculated states [40].
(a) The observed low-intensity bands at 656 and 581 nm in the
solid state and 821 and 638 nm in MeCN solution were com-
pared with the theoretical data in 858 and 713 nm for
PBE1PBE and 805 and 696 nm for B3LYP. These states of A
2
symmetry were defined as d ? d transitions with zero oscil-
lator strengths, as expected for compounds with C2v, sym-
metry. The intensity of these bands in the solid state is
higher than the observed in solution, as we can see in
Fig. 3. This can be explained by the existence of interactions
in the solid state that allows the symmetry breaking.
(b) The observed low-intensity bands at 492 nm in solid state
and 475 nm were compared with the theoretical data in
518 nm for PBE1PBE with d ? d and 546 nm for B3LYP with
The literature doesn’t have information about the charge trans-
ference spectrum for the bands in the [Co(DDTC)
ever, for [Cu(DDTC) ], Cesur [41] proposes an analytic procedure for
Cu(II) determination using displacement reactions of the metal cat-
ion Pb(II) in the complex [Pb(DDBC) ]. The effectiveness of the pro-
cedure was accompanied using UV–Vis spectroscopy, so the
concentration of Cu(II) dissolved in chloroform was determined,
but no assignment of the bands was done. San Andres et al. [42] re-
ported a spectrophotometric determination of Cu(II), Ni(II) and
Co(II) complexes with DDTC as ligand, but no assignment was done.
2
] complex. How-
S
p ? d. Again, the intensity of the band observed in the solid
2
state was higher. Those observable are similar in shape and
in intensity to the bands assigned for Urbach et al. [43], and
in principle can be assigned as d ? d transitions.
(c) The bands observed at 417 and 359 nm in the solid state and
397, 392 and 354 nm in solution were compared with the
theoretical data in 422 and 346 nm for PBE1PBE and 460
and 371 nm for B3LYP. These states of oscillator strengths
between 0.04 and 0.17 a.u. were classified as MLCT
transitions.
(d) The band at 307 nm in solid state and 320 nm in solution
was represented by state in 313 nm for PBE1PBE and
335 nm for B3LYP. The oscillator strength was calculated
between 0.25 and 0.29 a.u. and was classified as LMCT
transition.
2
2
In [Co(DDTC) ], the calculated framework structure was square
7
planar with Co(II) bound to four sulfur atoms. Co(II) is a d system
and had the possibility to achieve a low spin configuration. This
was confirmed by analysis of molecular orbitals in the previous
section. Urbach et al. [43] also discussed the circular dichroism
spectra of low-spin square-planar schiff base cobalt (II) complexes.
In this work, several additional transitions were observed and as-
signed as d ? d transitions based on the energy and low intensity.
Other similar works with metal complex, using sulphurated li-
gands, was informed recently by Ferreira et al. [33,44]. In these
studies, the complexes of zinc, antimony and bismuth with dmit
(e) Finally, the other bands observed in the solid state between
262 and 226 nm and in solution between 276 and 213 nm
were classified as LMCT and MLCT transitions. The values
calculated for the oscillator strengths were between 0.2
and 0.7 a.u.

A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
133
Table 8
2
Electronic transitions assignment for the [Co(DDTC) ] complex.
Solid spectra (nm)
Solution spectra in MeCN (nm)
821/638
PBE1PBE (MeCN) (nm)
858/713
Assignment
B3LYP (MeCN) (nm)
805/696
Assignment
ꢂ
ꢂ
6
56/581
p
r
S
!
CoAS
p
p
S
!
p
SAC@
N
SAC@
N
ꢂ
!
p
Co 3d ? Co 3d
SAC@
N
4
4
92
17
475
397/392
518
422
Co 3d ? Co 3d
546
460
p
S
? Co 3d
ꢂ
ꢂ
Co 3d ?
p
Co 3d ?
p
SAC@
N
SAC@
ꢂ
N
ꢂ
3
59
354
346
Co 3d ?
p
371
Co 3d ?
p
SAC@
N
SAC@
N
3
2
07
62
320
276/274
313
276/265
p
S
? Co 3d
335
270/264
p
p
S
? Co 3d
? Co 3d
ꢂ
Co 3d ?
p
S
SAC@
N
rCoAS ? Co 3d
p
p
r
r
S
? Co 3d
ꢂ
2
43
26
250
249/242
p
S
? Co 3d
256/240
S
!
CoAS
p
SAC@
N
ꢂ
!
!
p
p
SAC@
N
N
ꢂ
2
223
223
213
r
CoAS ? Co 3d
232
227
CoAS
SAC@
ꢂ
ꢂ
2
17
r
CoAS
!
p
Co 3d !
p
SAC@
N
SAC@
N
Final electronic transitions assignments in the UV–Vis spectra,
based on the experimental data and theoretical results, are sum-
marized in Table 8.
Acknowledgments
We are grateful to the Brazilian agencies CNPq, FAPERJ, FAPESP
for financial support, and to CAPES (PNPD). Thanks are given to the
Consejo Superior de Investigaciones Científicas (CSIC) of Spain for
the award of a license for the use of the Cambridge Crystallo-
4
. Conclusions
a
Synthesis, elementary CHN analysis, UV–Vis, and infrared
graphic Data Base (CSD). We thank Prof . Dr. Nadia M. Comerlato
a
spectrum of the [Co(DDTC)
cal calculations concerning structural analysis show a pseudo
planar framework structure for the CoS chromosphere. Vibra-
tional assignments of bands in the infrared spectrum of the
Co(DDTC) complex have been done based on the DFT:
2
] complex were presented. Theoreti-
and Prof . Dr. Cássia C. Turci for theirs valuable suggestions about
the text.
4
Appendix A. Supplementary material
[
2
]
B3LYP/6-311G(d,p) quantum mechanical calculation. The most
probable assignment for the skeletal vibrations was based on
the interpretation of the distorted geometry of the normal
modes, having as focus the study of the percentage of deviation
of the geometrical parameters. The results suggest the structure
depicted in Fig. 6 as the most probable, and the full assignment
for the complex is presented in Table 2. The NBO results using
B3LYP/6-311G (d,p) procedure, for alpha electrons, indicates that
2
The UV–Vis theoretical results of [Co(DDTC) ] and the infrared
band deconvolution analysis are available as Supplementary data
associated with this article can be found, in the online version, at
http://dx.doi.org/10.1016/j.molstruc.2012.06.041.
References
[
[
1] J.M. Yuhas, F. Culo, Cancer Treat. Rep. 64 (1980) 57.
2] S.B. Howell, R. Taetle, Cancer Treat. Rep. 64 (1980) 611.
[3] K. Lemma, S.K.C. Elmroth, L.I. Elding, J. Chem. Soc., Dalton Trans. (2002) 1281–
1286.
the Co(1)AS(8) bond is formed by interaction between
a
spd0
.03
d
1.09
(47.12% s, 1.49% p and 51.38% d) orbital centered
15.37 0.02
on the cobalt ion and a sp
d
(6.10% s, 93.75% p and
[
4] Z. Rehman, N. Muhammad, S. Ali, I.S. Butler, A. Meetsma, Inorg. Chim. Acta 376
2011) 381–388.
0
.15% d) orbital on the sulfur atom; for beta electrons, the
(
0.03 1.10
Co(1)AS(8) bond is formed by interaction between a spd
d
[
5] G. Faraglia, S. Sitran, D. Montagner, Inorg. Chim. Acta 358 (2005)
971–980.
(
46.74% s, 1.60% p and 51.65% d) orbital centered on the cobalt
1
2.20 0.02
[6] N. Singh, S. Bhattacharya, J. Organomet. Chem. 700 (2012) 69–77.
7] J.M. Berry, C. Jacobs, B. Sikic, J. Halsey, R.F. Borch, J. Clin. Oncol. 8 (1990) 1585–
590.
[8] Y.C. Zhang, G.Y. Wang, X.Y. Hu, Q.F. Shi, T. Qiao, Y. Yang, J. Cryst. Growth 284
3/4) (2005) 554–560.
ion and a sp
d
(7.56% s, 92.29% p and 0.14% d) orbital
[
on the sulfur atom. The occupancy of the alpha and beta elec-
trons in the Co(1)AS(8) bond was of 1.93 electrons. Similar re-
sults were found for the PBE1PBE/6-311G (d,p). The NBO
results also indicate an interaction between SAS atoms in each
diethylditiocarbamate ligands. The donor–acceptor interactions
based on the Second Order Perturbation Theory Analysis of the
Fox Matrix were also carried out.
1
(
[
9] T.K. Jana, D.P. Kumar, R. Pradhan, S. Dinda, P.N. Ghosh, C. Simmonet, J. Marrot, I.
Imaz, A. Wattiaux, J.-P. Sutter, F. Secheresse, R. Bhattacharyya, Inorg. Chim.
Acta 362 (10) (2009) 3583–3594.
10] I.M. Oglezneva, L.N. Mazalov, J. Struct. Chem. 43 (2) (2002) 352–354.
11] G. Bauer, G.S. Nikolov, N. Trendafilova, J. Mol. Struct. 415 (1997) 123–134.
12] H.P.S. Chauhan, N.M. Shaik, J. Inorg. Biochem. 99 (2) (2005) 538–545.
[
[
[
The UV–Vis spectra of the [Co(DDTC)
2
] complex were mea-
[13] I. Georgieva, N. Trendafilova, J. Phys. Chem. A 111 (50) (2007) 13075–13087.
[
[
14] M.P. San Andres, M.L. Marina, S. Vera, Talanta 41 (2) (1994) 179–185.
15] H. Mikosch, G. Bauer, R. Kellner, N. Trendafilova, G. Nikolov, J. Mol. Struct. 142
sured in the solid state and in acetonitrile solution. The multi-
configurational nature of several excited states of complex involv-
ing intra-ligand transitions are also observed. The calculated re-
sults are in agreement with the experimental spectra,
confirming the existence of several LMCT and MLCT transitions.
Analyses of the transition energies, using the TD-B3LYP and TD-
PBE1PBE methods, are in excellent agreement with the experi-
mental results. The CI calculations allowed a more precise analy-
sis than the previous one obtained from simple analysis of the
boundary orbitals. The calculations, carried out with solvent ef-
fect, described the energies with a larger precision than in the
vacuum system, although the intensity was not properly
represented.
(
1986) 473–476.
[16] B.S. Kang, Z.N. Chen, Z. Lin, H.X. Zhang, H.Q. Liu, X.Y. Huang, J. Coord. Chem. 46
1999) 409.
(
[
[
17] W. Petz, B. Neumuller, J. Hehl, Z. Anorg, Allg. Chem. 632 (2006) 2232.
18] G.B. Ferreira, N.M. Comerlato, J.L. Wardell, E. Hollauer, J. Braz. Chem. Soc. 15
(2004) 951–963.
[19] G.B. Ferreira, N.M. Comerlato, J.L. Wardell, E. Hollauer, Spectrochim. Acta Part
A 61 (2005) 2663–2676.
[
20] Gaussian 03, Revision C.02, M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E.
Scuseria, M.A. Robb, J.R. Cheeseman, J.A. Montgomery, Jr., T. Vreven, K.N.
Kudin, J.C. Burant, J.M. Millam, S.S. Iyengar, J. Tomasi, V. Barone, B. Mennucci,
M. Cossi, G. Scalmani, N. Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara,
K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H.
Nakai, M. Klene, X. Li, J.E. Knox, H.P. Hratchian, J.B. Cross, V. Bakken, C. Adamo,
J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C.

1
34
A.C. Costa Júnior et al. / Journal of Molecular Structure 1029 (2012) 119–134
Pomelli, J.W. Ochterski, P.Y. Ayala, K. Morokuma, G.A. Voth, P. Salvador, J.J. [31] D.F. Shriver, P.W. Atkins, Inorganic Chemistry, fourth ed., Oxford University
Dannenberg, V.G. Zakrzewski, S. Dapprich, A.D. Daniels, M.C. Strain, O. Farkas,
D.K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G.
Baboul, S. Clifford, J. Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I.
Komaromi, R.L. Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A.
Nanayakkara, M. Challacombe, P.M.W. Gill, B. Johnson, W. Chen, M.W. Wong,
C. Gonzalez, J.A. Pople, Gaussian, Inc., Wallingford, CT, 2004.
Press, New York, 2006.
[32] S.I. Gorelsky, L.B. Basumallick, J. Vura-Weis, R. Sarangi, K.O. Hodgson, B.
Hedman, K. Fujisawa, E.I. Solomon, Inorg. Chem. 44 (2005) 4947.
[33] G.B. Ferreira, E. Hollauer, N.M. Comerlato, J.L. Wardell, Spectrochim. Acta Part
A 71 (2008) 215–229.
[34] L. Radom, A.P. Scott, J. Phys. Chem. 100 (1996) 16502.
[35] B.A. Almeida, J.M. Ramos, O. Versiane, M. Souza, C.A. Téllez Soto, A.L.R. Mercê,
A.S. Mangrich, Polyhedron 27 (2008) 3662–3668.
[
[
21] Chemcraft Software. <http://www.chemkraftprog.com/order.html>.
22] N.M. O’Boyle, A.L. Tenderholt, K.M. Langner, J. Comp. Chem. 29 (2008)
8
39–845.
[36] J.M. Ramos, M.T.M. Cruz, A.C. Costa Jr., O. Versiane, C.A. Téllez Soto, ScienceAsia
37 (2011) 247–255.
[37] J.M. Ramos, O. Versiane, C.A. Téllez Soto, Spectrochim. Acta A 68 (2007) 1370–
1378.
[38] J.M. Ramos, O. Versiane, C.A. Téllez Soto, Spectrochim. Acta A 72 (2009) 182–
189.
[39] F. Weinhold, C. Landis, Valency and Bonding: A natural Bond Orbital Donor–
Acceptor Perspective, Cambridge University Press, 2005.
[40] Z. Li, W. Liu, J. Chem. Phys. 135 (2011) 194106.
[41] H. Cesur, Chem. Pap. 61 (2007) 342–347.
[
[
[
23] Tenderholt, Adam L. QMForge, Version 2.1. <http://qmforge.sourceforge.net>.
24] R. Zahradnik, P. Zuman, Chem. Commun. 24 (1959) 1132.
25] H. Freiser, Q. Fernando, Ionic Equilibria in Analytical Chemistry, John Wiley &
Sons, Inc., New York, 1963.
26] J.M. Ramos, R.M. Viana, C.A. Téllez Soto, W.C. Pereira, A.O. Izolani, M.I.P. Silva,
Spectrochim. Acta A 65 (2006) 433–438.
27] C.A. Téllez Soto, J.M. Ramos, R.S. Rianelli, M.C.B.V. Souza, V.F. Ferreira,
Spectrochim. Acta A 67 (2007) 1080–1087.
28] J.M. Ramos, O. Versiane, C.A. Téllez Soto, Spectrochim. Acta A 67 (2007) 1046–
[
[
[
[
[
1
054.
29] O. Versiane, B.L. Rodrigues, J.M. Ramos, C.A. Téllez Soto, Spectrochim. Acta A 65
2006) 1112–1119.
30] J.M. Ramos, G.F. Ondar, O. Versiane, C.A. Téllez Soto, Spectrochim. Acta A 71
2008) 1364–1370.
[42] M.P. San Andres, M.L. Marina, S. Vera, Analyst 120 (1995) 255.
[43] F.L. Urbach, R.D. Bereman, J.A. Topich, M. Hariharan, B.J. Kalbacher, J. Am.
Chem. Soc. 96 (16) (1974) 5063–5069.
[44] G.B. Ferreira, E. Hollauer, N.M. Comerlato, J.L. Wardell, Inorg. Chim. Acta 359
(2006) 1239–1247.
(
(