Synthesis, characterization, and oxidation electrochemistry of some novel 1,2-dithiol-3-ones and 1,2-dithiol-3-thiones containing aryl and metallocenyl fragments

Article abstract of DOI:10.1016/j.jorganchem.2021.121809

A new synthesis method was established for 1,2-dithiol-3-ones and 1,2-dithiol-3-thiones, from different cyclopropenones: diphenyl (a), bis-(4-methoxyphenyl (b), diferrocenyl (c) and diruthenocenyl (d), in the presence of elemental sulfur with yields of the 5a-d (35–57%), or in the presence of the additive NaHS, with yields of the 5a-d (45–72%) and 6a-d (10–18%). The characterization of the new compounds was conducted by IR, ¹H and ¹³C NMR spectroscopy, elemental analysis, mass-spectrometry. In addition, X-ray crystallographic analysis of the compounds 5a,b,d was conducted. The redox properties of the heterocyclic compounds were investigated using cyclic (CV), differential pulse (DPV) and square wave (SWV) voltammetries.

Full text of DOI:10.1016/j.jorganchem.2021.121809

Journal of Organometallic Chemistry 944 (2021) 121809
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, characterization, and oxidation electrochemistry of some
novel 1,2-dithiol-3-ones and 1,2-dithiol-3-thiones containing aryl and
metallocenyl fragments
Jessica J. Sánchez García, Rene S. Joo-Cisneros, David García-Bassoco, Marcos Flores-Alamo,
José M. Méndez Stivalet, Jesús García-Valdés1, Elena I. Klimova∗
Facultad de Química, Universidad Nacional Autónoma de México, Cd. Universitaria, Coyoacán, C. P. 04510 México, CDMX, México
a r t i c l e i n f o
a b s t r a c t
Article history:
A new synthesis method was established for 1,2-dithiol-3-ones and 1,2-dithiol-3-thiones, from different
cyclopropenones: diphenyl (a), bis-(4-methoxyphenyl (b), diferrocenyl (c) and diruthenocenyl (d), in the
presence of elemental sulfur with yields of the 5a-d (35–57%), or in the presence of the additive NaHS,
with yields of the 5a-d (45–72%) and 6a-d (10–18%). The characterization of the new compounds was
conducted by IR, 1H and 13 C NMR spectroscopy, elemental analysis, mass-spectrometry. In addition, X-ray
crystallographic analysis of the compounds 5a,b,d was conducted. The redox properties of the hetero-
cyclic compounds were investigated using cyclic (CV), differential pulse (DPV) and square wave (SWV)
voltammetries.
Received 12 February 2021
Revised 1 April 2021
Accepted 1 April 2021
Available online 16 April 2021
Keywords:
Ferrocene
Ruthenocene
1–2-Dithiol-3-ones
1,2-Dithiol-3-thiones
Oxidation-electrochemistry
X-ray crystallography
© 2021 Elsevier B.V. All rights reserved.
1. Introduction
sidered that the toxicity of ferrocenyl compounds is derived from
the slight and reversible oxidation of ferrocene units in ferricinium
Metallocenes, which are bis(cyclopentadienyl) metal derivatives,
cations (Fc+). These processes are fast and reversible. The poten-
tials of the reduction and oxidation ruthenocenes show different
anticancer activities [6b] to ferrocenes due to their different re-
dox properties, which are more positive and less reversible [7].
1,2-Dithiole-3-ones and 1,2-dithiole-3-thiones are compounds that
have received a lot of attention from synthesis chemistry and for
their use in various applications [8]. Dithiole-3-thions are consid-
ered as promising drug agent for the prevention of cancer. Oltipraz
(4-methyl-5-pyrazinyl-3H-1,2-dithiole-3-thione) (Fig. 1) for exam-
ple showed positive results in the treatment of schistosomiasis
in humans [9]. This compound has been furthermore studied as
an effective chemo preventive agent in mouse models for the ex-
perimental treatment of carcinogenesis [10] in target organs such
as the pancreas, lung, stomach, colon, bladder, trachea, mammary
gland, and skin [11]. 5-(4-Methoxyphenyl)−1,2-dithiole-3-thione
(ADT) (Fig. 1) is another important example, which is currently
used to stimulate salivary secretion and marketed as a drug agent
[11].
are described as sandwich compounds and their formula is ex-
–
pressed as [M(η5 C5H5)2]. They are studied as a novel alternative
in medicinal chemistry and are particularly ideal for the use in
–
therapeutic agents [1]. Ferrocene [Fe(η5 C5H5)2] and ruthenocene
–
[Ru(η5 C5H5)2] are among the most studied metallocenes, due to
their characteristic as small, rigid, lipophilic molecules that can
penetrate cell membranes. Many ferrocene related organometallic
molecules have pharmacological functions. These effects can be at-
tributed mainly to the effects of cytotoxicity, lipophilicity and their
redox properties. Furthermore, they have a strong influence on the
oxidation process by reducing the redox potential [2] of the ferro-
cenyl fragments in biological targets [3]. Therefore, these ferrocene
related organometallic molecules have been widely used in the
designs of medicinal molecules and in biological research [5] as
antianemic [4], antiproliferative agents [5a], against for example
fungal infections [5b], bacterial infections [5c], malaria [5d], HIV
[5e] and cancer [6] (mainly against breast cancer [6a]). It is con-
The electrophilic [13b] and nucleophilic [13a] displacements
at a sulfur atoms is of particular interest because of the vari-
ety of synthetic applications which may be obtained [13] . Sul-
furization reactions with elemental sulfur constitute a relevant
topic in organic sulfur chemistry [12]. Given this relevance new
∗
Corresponding author.
E-mail address: eiklimova@quimica.unam.mx (E.I. Klimova).
1
Dedicated to the memory of Dr. Jesus García-Valdés, for his contributions to
teaching analytical chemistry and his love of science.
https://doi.org/10.1016/j.jorganchem.2021.121809
0022-328X/© 2021 Elsevier B.V. All rights reserved.

J.J. Sánchez García, R.S. Joo-Cisneros, D. García-Bassoco et al.
Journal of Organometallic Chemistry 944 (2021) 121809
Table 1
Optimization of the reaction conditions.a,b
.
Temperature
Additive
Yield [%]
5c
Entry
Solvent
CH2Cl2
[°C]
t [h]
6c
1
36
8
/
20
22
36
38
40
42
50
52
45
46
41
45
43
48
60
65
60
40
25
0
Fig. 1. 1,2-dithiol-3-thiones of commercial importance.
2
NaHS
/
2
3
CHCl3
60
80
80
138
65
82
78
8
8
8
8
8
8
0
4
NaHS
/
7
5
CH3CN
Benzene
Xylene
MeOH
iPrOH
EtOH
0
synthetic methods are currently being studied to obtain sulfur-
rich heterocycles: mainly the sulfurization of arylcyclopropentiones
[13a], thioketones, thiochalcones [13b], diferrocenyl ketone [14],
ferrocenifens and substituted ferrocenyl ethylenes [15], etc..
In this work a new method of synthesis of 1,2-diaryl- and 1,2-
dimetalocenyl-dithiol-3-one and 1,2-dimetallocenyl-3-thiones is in-
vestigated, starting from the reaction of 2,3-diaryl- and 2,3-
dimetalocenylcyclopropenones by the reactions with elemental sul-
fur. Furthermore, the study of the oxidation and reduction pro-
cesses of the dithiols obtained is conducted. Finally, the results of
all newly synthesized compounds are presented and discussed, as
well as the results of electrochemical investigations and X-ray anal-
ysis.
6
NaHS
/
7
7
0
8
NaHS
/
12
10
20
0
9
10
11
12
13
14
15
16
17
18
19
NaHS
/
NaHS
/
15
0
NaHS
/
17
0
6
6
NaHS
NaHS
NaHS
NaHS
20
25
39
65
8
12
16
a
Reaction conditions: 0.3 mmol of 3a-d and 0.15 mmol of sulfur in 3.0 mL of
solvent.
2. Results and discussion
b
with 50 mol% of additive.
Cyclopropenones have recently been used as building blocks for
N- [16], O- [17] and S-containing heterocycles [18]. Previous stud-
ies have discussed the synthesis of diferrocenyl substituted hetero-
cycles from 2,3-diferrocenylcyclopropenones and diferrocenylcyclo-
propenilium cations [19-23].
Table 2
Reaction of cyclopropenones 3a-d with elemental sulfur.
The cyclopropenones 2,3-diaryl- (phenyl 3a and 4-
methoxyphenyl 3b) and dimetallocenyl [24]- (ferrocenyl 3c
and ruthenocenyl 3d [24b]) were synthesized (Scheme 1) by
Friedel-Crafts alkylation of arenes and metallocenes with tetra-
chlorocyclopropene, following the procedure established by our
group [20].
Yield [%]
Entry
R
substituent Additive
5a-d
6a-d
1
2
a
/
55
58
0
NaHS
14
The use of thionation agents for the conversion of carbonyl
groups (C=O) to thiocarbonyl (C=S) in the cyclopropenones 3a-d
(Scheme 2) lead to high yields [22].
3
4
b
c
/
57
72
0
NaHS
18
5
6
/
50
52
0
In the first stage of the study of the reactivity of the cyclo-
propenones 3a-d and elemental sulfur, or with the presence of an
additive (NaHS), in different solvents and reaction times, to find
the best reaction conditions, as shown in Table 1, among the tested
solvents, with the protic solvent etanol/water have the best reac-
tion yields. Reaction in ethanol with an additive (NaHS) for 12 h
(entry 18), is obtained with a yield in the proportion of approxi-
mately 1:1 (5c:6c) and when the reaction time is increased to 16 h
with additive, obtains a higher yield of 4,5-diferrocenyl-1,2-dithiol-
3-thione 6c with a yield of 65% (entry 19).
NaHS
12
7
8
d
/
35
45
0
NaHS
10
[a] Reaction conditions: 0.3 mmol of 3a-d, 0.15 mmol of sulfur in 3.0 mL of ben-
zene.
[b] with 50 mol% of additive, isolated yield.
ration of the electron donor group increases the reactivity of
cyclopropenone. The presence of ferrocene fragments in 2,3-
It can be seen in Table 1 that the use of benzene during 8 h
of reaction time in the absence of the additive, leads to a yield
of 50% of compound 5c (entry 7), whereas in the presence of the
additive the yields of compound 5c are 52% and of 6c 12% respec-
tively (entry 8, Table 1). These results indicate that the presence of
the additive has a particular influence on the formation of 6c. In
addition a conversion of the carbonyl groups to the thiocarbonyl is
observed when longer reaction times are used.
dimetalocenyl cyclopropenones leads to
a higher reactivity,
whereas the presence of ruthenocene reduces the reactivity.
The mixtures of 5a-d and 6a-d were separated using thin-layer
chromatography (Al2O3, Brockmann activity III). The 1,2-dithiol-3-
ones (5a,b) are crystalline compounds, which are stable at room
temperature.
Another synthesis method for 4,5-diferrocenyl-1,2-dithiol-3-
thiones 6c (Table 3) was carried out by using 1,2-diferrocenyl-
cyclopropenthione 4c in combination with elemental sulfur in dif-
ferent types of solvents (benzene, xylene, ethanol) under reflux
(reaction time of 8 h) in the presence of the additive, resulting in
a yield of 75%.
The reactivity of the cyclopropenones in this protocol
was examined under the identified reaction conditions, as
shown in Table 2. It is observed that the use of 1,2-diaryl
cyclopropenones results in
a
higher yield with 2,3-bis(4-
methoxyphenyl)cyclopropenone, indicating that the incorpo-
2

J.J. Sánchez García, R.S. Joo-Cisneros, D. García-Bassoco et al.
Journal of Organometallic Chemistry 944 (2021) 121809
Scheme 1. Synthesis of 2,3-diaryl- (3a-b) and 2,3-dimetallocenyl (3c-d) cyclopropenones.
Scheme 2. Reaction of thionation of the 2,3-diarylcyclopropenones.
Table 3
Scheme 3. Reactivity of the 1,2-dithiol-3-ones 5c and 1,2-dithiol-3-thiones 6c.
Reaction conditions: 6c (1 equivalent) and hydrazine hydrate (1 equivalent) in
ethanol (0.2 M), isolated yield.
Reaction of cyclopropenthione 4c with sulfur.
elemental analysis, mass spectrometry, and X-ray analysis (for 5a,
5b and 5d). The collected data are in complete agreement with the
proposed structures.
Entry
Solvent
Temperature
Additive
Yield [%]
The 1H NMR spectrum of compounds: I) 4,5-diphenyl-1,2-
dithiol-3-one 5a [13a] showed resonances at δ = 7.12 – 7.32 ppm,
corresponding to the aromatic protons, II) The 1H NMR spectrum
of compound 2,3-bis(4-methoxyphenyl)−1,2-dithiol-3-one 5b con-
1
2
3
4
5
6
Benzene 80
/
60
75
55
70
48
55
NaHS
/
Xylene
EtOH
138
78
NaHS
/
–
tains two singlets for two O CH3 methoxy groups (δ = 3.79 and
NaHS
3.81 ppm), resonances at (δ = 6.83 – 7.21 ppm), which corre-
spond to the aromatic protons, III) 4,5-diferrocenyl-1,2-dithiol-3-
one 5c showed two singlets for the two C5H5 ferrocenyl fragments
(δ = 4.06 and 4.24 ppm) and IV) 4,5-diruthenocenyl-1,2-dithiol-3-
one 5c two singlets in (δ = 4.49 and 4.68 ppm) for the two C5H5
ruthenocenyl protons.
The13C NMR spectrum of compounds: I) 5a [24a] shows four
singlets for two C6H5 phenyl groups, one signal for carbonyl group
C=O (δ = 193.47 ppm) and two signals for CipsoPh (δ = 128.13
and 130.48 ppm) belonging to two phenyl fragments, II) 5b shows
two singlets for CH3O- (δ = 55.18 and 55.32 ppm), four sin-
glets for two C6H4 aromatics, one signal for carbonyl group C=O
(δ = 193.94 ppm) and two signals for Cipsoanysil (δ = 125.04 and
126.43 ppm), III) 5c [24a] shows two singlets for two C5H5 ferro-
cenyl groups (δ = 69.57 and 70.55 ppm), one signal for carbonyl
group (C=O) (δ = 192.31 ppm), two signals for CipsoFc (δ = 78.32
and 79.94 ppm), IV) 5d shows two singlets for two C5H5 rutheno-
cenyl groups, two signals for CipsoRc (δ = 81.37 and 85.42 ppm)
belonging to two ruthenocenyl fragments. All quaternary carbon
atoms of all compounds were accounted for.
[a] Reaction conditions: 0.3 mmol of 4c and 0.15 mmol of sul-
fur in 3.0 mL of solvent, [b] with 50 mol% of additive, isolated
yield.
The reactivity of 4,5-diferrocenyl-1,2-dithiol-3-one 5c was stud-
ied using hydrazine hydrate (Scheme 3). The results of these
experiments showed that compound 5c was not reactive. Only
in the presence of hydrazine the 4,5-diferrocenyl-1,2-dithiol
−3-thione 6c is reactive forming (4,5-diferrocenyl-1,2-dithiol-3-
ylidene)hydrazine 7c.
2.1. Spectral characterization
All newly synthesized compounds were found to be stable
at room temperature for a prolonged time and could safely be
handled in air. However, like other phenyl, anisyl, ferrocene and
ruthenocene derivatives, they need to be stored in closed con-
tainers. Detailed spectral characterization was conducted to con-
firm their structure. The structures of cyclopropenones 3a-d were
confirmed by standard spectroscopic techniques (IR, and 1H- and
13C NMR). All spectral data are fully consistent with the proposed
structures.
The 1,2-dithiol-3-thiones 6a-d are stable toward air, light and
moisture in their solid state as is the case with most common or-
ganic solvents. The components and formula of 6a-d were deter-
mined by FTIR, NMR, mass spectrometry and elemental analysis
(see supplementary material).
All the synthesized 1,2-dithiol-3-ones 5a-d were characterized
by standard spectroscopic techniques (IR, and 1H- and 13C NMR),
3

J.J. Sánchez García, R.S. Joo-Cisneros, D. García-Bassoco et al.
Journal of Organometallic Chemistry 944 (2021) 121809
Fig. 2. A perspective view of the compounds 5a, with the atomic labeling scheme.
Fig. 3. A perspective view of the compound 5b, with the atomic labeling scheme.
Displacement ellipsoids are shown at the 50% probability level.
Displacement ellipsoids are shown at the 70% probability level.
The 1H NMR spectra of 6a-d contain characteristic signals of
the aromatic (for phenyl, anysil), ferrocenyl and ruthenocenyl pro-
tons located in the expected regions. In this context, the moiety
of ferrocene and ruthenocene exhibit two slightly shielded singlets
at (δ = 4.12, 4.19 ppm for ferrocene) and (δ = 4.11, 4.16 ppm for
rutheneocene), which are assigned to the hydrogens of the unsub-
stituted cyclopentadiene ring (Cp). In the 13C NMR spectra of 1,2-
dithiol-3-thiones 6a-d, the signals of methyl, aromatic, ferrocenyl
and rutenocenyl, thiocarbonyl groups are identified in their appro-
priate regions.
The 1H NMR spectra of the compound (4,5-diferrocenyl-1,2-
dithiol-3-ylidene) hydrazine 7c, contain the characteristic signals
of the ferrocenyl protons located in the expected regions and the
signal corresponding to the amino group NH2 (δ = 5.02 ppm). In
the 13C NMR spectra, the signals of the ferrocenyl group are lo-
cated in the expected region together with and the C=N group
(δ = 157.03 ppm). The data from the NMR spectroscopy of these
compounds are completely in accord with the proposed structures.
The main common feature of the IR spectra of the synthesized
1,2-dithiol-3-ones 5a-d is the strong single band at 1600- 1650
cm−1, which is attributed to the C=O stretching. The 1,2-dithiol-
3-thiones 6a-d contain bands at 700 - 850 cm−1 and 1418 - 1470
cm−1, which are attributed to the fragments C-S and C=S.
molecule is not planar. The phenyl rings are rotated relative to the
1,2-dithiol-3-one bridge Cg3/Cg1 and Cg3/Cg2, with dihedral angles
of 40.03(2) and 67.35(1)° respectively, in fact the Cg1/Cg2 show a
dihedral angle of 65.58(2)°. As a result of a search in the Cam-
bridge Crystallographic Database (CSD), it was found that the bond
˚
distance C1-S1 is 3.3% longer than the average value of 1.793 A,
while the C1-O1 bond distance is 6.3% shorter than the average
˚
value of 1.219 A.
In crystal packing (Fig. S-2 see supplementary material), there
are two type of intermolecular interactions: one of no-classical
C−H…O hydrogen bond and other σ…π intermolecular contact
˚
mainly. The first contact C13−H13…O1(2.83 A) has the symme-
try operations:−1/2 + x, 1/2-y,-z and is observed along the plane
formed by the c-b axes, while the second intermolecular interac-
˚
tion C12−H12…π (2.72 A) is representing an extremely weak in-
teraction, but it is essential to stabilize the crystalline arrangement.
The intermolecular contacts of type hydrogen bond and σ…π con-
tact form a tridimensional complex array along the b-c plane.
In the asymmetric unit of compound 5b (Fig. 3), the maximum
˚
deviation from the mean plane of 0.035 A for atom S1 in the 1,2-
dithiol-3-one ring (Cg3) unit including O1, in fact this plane has
arms of 0.0258, note that there is a double bond between car-
bon atoms C2 and C3. The aryl rings C4/C9 (Cg1) and C10/C15
(Cg2) bonded to C3 and C2 respectively are rotated relative to
the 1,2-dithiol-3-one ring (Cg3) with dihedral angles of 28.44(2)
for Cg3/Cg1 and 72.19(1)° for Cg3/Cg2, while the aromatic rings
Cg1 and Cg2 have a dihedral angle between them of 67.42 (1)°. A
search of the Cambridge Crystallographic Database found that the
C2-C1-S1 and C1-C2-C3 bond angles are an unusual 2.64 and 5.12%
longer than the average value of 110.24 and 111.04° respectively.
In crystal packing (Fig. S-12 see supplementary material), there
are four type of intermolecular interactions: two of no-classical
C−H…O, C−H…S hydrogen bond and two σ…π intermolecular
2.2. Description of crystal structures
Suitable single crystal of compounds 1,2-dithiol-3-ones 5a,b,d
for X-ray diffraction analysis have been obtained by recrystalliza-
tion from a dichloromethane solution layered with hexane at room
temperature.
The ORTEP views of 4,5-diphenyl-1,2-dithiol-3-one 5a, 4,5-bis-
(4-methoxyphenyl)−1,2-dithiol-3-one 5b and 4,5-diruthenocenyl-
1,2-dithiol-3-one 5d are illustrated in Figs. 2-4 respectively. The se-
lected bond lengths and bond angles are given in Table 4.
The compound 1,2-diphenyl-dithiol-3-one 5a, has been previ-
ously reported [13a] with the crystallographic parameters collected
at a temperature of 293 K. In contrast, the X-ray diffraction data
presented in this work were taken at a temperature of 130 K.
The asymmetric unit of compound 5a may be described in
three parts: the planar fragment formed by the 1,2-dithiol-3-
one C1/C3-S2−S1 ring (Cg3) and the planes stablish by two six-
membered aromatic ring C4/C9 (Cg1) and C10/C15 (Cg2). The 5a
˚
˚
contact mainly. The C6−H6…O1 (2.60 A) C12−H12…S1 (3.57 A)
interactions form the R22(13) motif along the a axis, while the
˚
˚
C12−H12…S1, C17−H17A…O1 (2.60 A), C16−H16A…O1 (3.02 A)
˚
and C8−H8…Cg1 (3.00 A) interactions establish a R43(18) motif in
the b-c plane, it should be noted that the interactions C8−H8…Cg1
C17-H17B…Cg2 represent the two σ…π intermolecular contacts
mainly in the crystalline array. All the intermolecular contacts
forming a tridimensional complex array along the b-c plane.
4

J.J. Sánchez García, R.S. Joo-Cisneros, D. García-Bassoco et al.
Journal of Organometallic Chemistry 944 (2021) 121809
Table 4
˚
Selected bond lengths [A] and angles [°] for compounds 5a,b and 5d.
5a
5b
5d
Bond
Lengths
Bond
Lengths
Bond
Lengths
S(1)-C(1)
S(1)-S(2)
O(1)-C(1)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
1.853(6)
2.049(2)
1.143(8)
1.514(9)
1.357(8)
1.472(9)
S(1)-C(1)
S(1)-S(2)
O(1)-C(1)
O(2)-C(7)
O(2)-C(16)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
1.783(4)
2.048(14)
1.229(4)
1.361(4)
1.428(5)
1.459(5)
1.361(5)
1.487(5)
angles
Ru(1)-C(10)
Ru(2)-C(4)
S(1)-C(1)
O(1)-C(1)
C(1)-C(2)
C(2)-C(3)
C(3)-C(4)
2.180(4)
2.183(4)
1.803(4)
1.184(5)
1.482(5)
1.354(5)
1.471(5)
angles
angles
C(1)-S(1)-S(2)
C(3)-S(2)-S(1)
O(1)-C(1)-C(2)
C(10)-C(2)-C(1)
C(2)-C(3)-C(4)
C(2)-C(3)-S(2)
98.1(2)
95.4(2)
129.8(6)
115.7(5)
127.6(6)
119.2(5)
C(1)-S(1)-S(2)
C(3)-S(2)-S(1)
C(7)-O(2)-C(16)
O(1)-C(1)-C(2)
C(1)-C(2)-C(10)
C(2)-C(3)-C(4)
C(2)-C(3)-S(2)
96.22(13)
95.43(13)
117.5(3)
127.6(3)
117.1(3)
127.3(3)
117.9(3)
C(1)-S(1)-S(2)
C(3)-S(2)-S(1)
O(1)-C(1)-C(2)
C(10)-C(2)-C(1)
C(2)-C(3)-C(4)
C(2)-C(3)-S(2)
97.18(14)
94.45(14)
128.9(4)
119.0(3)
126.4(3)
120.1(3)
anistic pathways, were sulfur elemental acts as the nucleophile
[13b] (Scheme 4a-c) and where sulfur acts as the electrophile
[13a] (Scheme 4d). As a first step, an attack by the elemental sul-
fur molecule electrons towards the carbon atoms C(1) of cyclo-
propenones takes place, obtaining the intermediate 8a-d. Subse-
quently, a loss of the sulfur molecule (S6) results in the interme-
diate species 9a-d, which promotes a second nucleophilic attack of
cyclopropene on the sulfur atom of 9a-d resulting in the formation
of intermediary 10a-d. The stabilization of 10a-d, due to the pres-
ence of the oxygen atom will promote the rupture of the three-
membered ring and a new formation to obtain the 1,2-dithiol-3-
ones 5a-d. An excess of elemental sulfur will be used to carry
out the changing of the functional group from carbonyl (C=O) to
thione (C=S) to obtain compound 6a-d. (Scheme 4a).
Fig. 4. A perspective view of the compound 5d, with the atomic labeling scheme.
A first nucleophilic attack by the sulfur molecule can be carried
out on the C(2) atom of the three-membered ring, obtaining the
intermediate 11a-d, which after opening the ring forms interme-
diate 12a-d. Subsequent stabilization will lead to the formation of
compound 5a-d (Scheme 4b).
Displacement ellipsoids are shown at the 70% probability level.
The compound 5d crystallizes in monoclinic crystal system with
space group P21/c, unlike the compound 5c, which has been a
previously reported [13a] compound, which crystallizes in a tri-
clinic crystal system with space group P-1; but both present an
analogous molecular arrangement, which allows us to propose that
they are isomorphic. The asymmetric unit of 5d is constituted by
a pair of ruthenocenyl units bonded to C2 and C3 atoms of the
1,2-dithiol-3-one ring; note that there is a double bond between
carbon atoms C2 and C3 (Fig. 4). A cyclopentadienyl ring shows
disorder over five carbon atoms with 0.74:0.26 of occupation. In
the ruthenocenyl fragments, the cyclopentadienyl (Cp) rings are al-
most parallel, making dihedral angles of 3.16(3) and 0.90(2)°. The
dihedral angles between the 1,2-dithiol-3-one ring and the sub-
stituted cyclopentadienyl (Cp) rings are 41.24 (3)° for C2-Cp1 and
60.65(1) for C3-Cp2, while the dihedral angle between Cp1 and
Cp2 is 58.38(2)°. The cyclopentadienyl rings of the ruthenocenyl
Scheme 4c shows the possible formation of the products of
compounds 5a-d involves the initial unstable intermediates 10a-d,
which undergo a ring opening resulting in the vinylcarbene species
11a-d, whose subsequent intramolecular transformations give rise
to cyclic 5a-d products.
Moreover, the feasible mechanism for the formation of com-
pounds 6a-d: the nucleophilic attack by electrons of sulfur atom
of the thiocarbonyl groups of compounds 4a-d towards the sul-
fur atom of (S8) takes place, the intermediate 14a-d is obtained.,
which with loss of a molecule of (S6) the intermediates 15a-
d and bicyclic intermediates 16a-d are formed. The intramolec-
ular transformation of the 16a-d with the opening of the three-
membered ring will carry out the formation of the compounds 6a-
d (Scheme 4d).
–
–
moieties adopts an eclipsed conformation. The C C, C-S, C O bond
lengths and bond angles are within the observed values in the
Cambridge Crystallographic Database.
2.4. Electrochemistry
In the crystal structure (Fig. S-35 see supplementary material),
the molecules of organometallic complex are linked via no-classical
C—H…O hydrogen bond, between the Cp rings and the O atoms of
the 1,2-dithiole-3-one moieties. The C22-H22…O1 interaction with
a graph-set C11(8) along the c axis in the b-c plane.
The 4,5-diferrocenyl-1,2-dithiol-3-ones 5c and 4,5-diferrocenyl-
1,2-dithiol-3-thiones 6c, with structure Fc-C=C-Fc compounds
show the typical two-step monoelectron transfer process accord-
ing to Scheme 5:
Most of the polyferrocenyl species undergo an additional chem-
ical reaction of comproportionation. This reaction Kcom occurs be-
tween the Fc+-C=C-Fc+, produced after the second oxidation reac-
tion, and the Fc-C=C-Fc species that are present at the electrode
surface (Scheme 6).
2.3. Mechanisms
The plausible mechanisms for the formation of compounds 5a-
d are shown in Schemes 4a-d where there can be two mech-
5

J.J. Sánchez García, R.S. Joo-Cisneros, D. García-Bassoco et al.
Journal of Organometallic Chemistry 944 (2021) 121809
a)
b)
c)
d)
Scheme 4. a-d. The plausible mechanisms for the formation of 1,2-dithiol-3-ones and 2-dithiol-3-thiones by nucleophilic [13b] (Schemes 6a-c) and electrophilic [13a]
(Scheme 6d) attacks of sulfur atoms.
rents (Ox1 and Ox2) and their corresponding reduction currents
(Red1 and Red2). Both processes are electrochemically reversible
with 1e− and 1e−exchanges, respectively, which were confirmed
by Square Wave Voltammetry (SWV) traces. However, the com-
pound 6c showed an additional signal that we speculate is the ox-
idation of the ring that forms the link between the ferrocenyl moi-
Scheme 5. Two mono-electronic transfer processes for diferrocenyl compounds.
eties. Fig. 5 shows cyclic (top) and square wave (bottom) voltam-
mograms of 6c.
In contrast compound 5d synthesized with ruthenocene
showed
a different behavior: two irreversible and overlapped
mono-electronic steps of oxidation. According to the literature,
a possible mechanism involves a chemical coupled reaction be-
tween the product of the first oxidation step and the solvent [25-
26], which facilitates the second ruthenocenyl oxidation step, be-
sides the posterior oxidation of the organic structure (third signal
at more anodic potential values). As a consequence of the cou-
pled reaction, the electrochemical processes are irreversible, and
it does not show the characteristic signals of metallocene centers.
Fig. 5 shows the CV and SWV recordings for 5d SWV shows a small
Scheme 6. Two mono-electronic transfer processes for diferrocenyl compounds.
The half wave potential for each oxidation steps are E1/2(1)
and E1/2(2) depend on some important factors such as support-
ing electrolyte and solvent combination. The last is fundamen-
tal for the formation of ion-pairs, the donor or acceptor number,
and the polarity of the solvent. Cyclic voltammetry for diferrocenyl
compounds 5c and 6c showed two well-resolved oxidation cur-
6

J.J. Sánchez García, R.S. Joo-Cisneros, D. García-Bassoco et al.
Journal of Organometallic Chemistry 944 (2021) 121809
Fig. 5. Representative voltammograms of compond 5c (1.28 × 10−3 mol/L), 5d (1.5 × 10−3 mol/L) and 6c (0.87 × 10−3 mol/L) in 0.1 M NBu4PF6 in CH3CN acetonitrile. The
−
1
scan rate for CV (red line) was 0.1 V s
Ag(I)/Ag0. Normalized current = I/Ipa.
and the frequency for SWV (black line) was 20 Hz. The electrodes were: working, glassy carbon (GCE); counter; Pt; and reference,
Table 5
3. Conclusions
Electrochemical data for compounds 5a, 5b, 5c, 5d, and 6c.
Conc
I
II
III
Log
The 1,2-diaryl- and 1,2-dimetalocenyl-dithiol-3-one and 1,2-
dimetallocenyl-3-thiones have been synthesized and fully charac-
terized by a combination of spectroscopic, X-ray crystallography
and electrochemical measurements. The experiments conducted
in this work showed that hydrazone 7c (4,5-diferrocenyl-1,2-
dithiol-3-ylidenehydrazine) was synthesized from 4,5-diferrocenyl-
1,2-dithiol-3-thione 6c in high yields. The 4,5-diferrocenyl-1,2-
dithiol-3-one 5c in the same conditions did not form any reaction
products with hydrazine (in contrast with thione 6c).
Compound
(mM)
E1/2
E1/2
E1/2
ꢀE1/2
kcom
5a
5b
5c
5d
6c
1.5
1.8
–
–
–
1.5
−0.919
0.023
0.359
−0.009
–
–
0.671
0.254
0.231
0.193
1.28
1.5
0.277
0.411
0.269
–
4.54
–
0.615
0.462
0.87
4.98
Their oxidation potentials were affected by the type and num-
ber of the linker groups attached to the metallocenyl unit. The
electrochemical behavior of 5a-d and 6c was studied by cyclic and
square-wave voltammetry, the ࢞Ep values obtained from 1 to 2
oxidation processes for metallocenyl moieties for 5c, 6c and 5d,
are mainly caused by electrostatic interactions of the metallocenyl
group. It is speculated that the additional signal of compound 6c
is the oxidation of the ring that forms the link between the ferro-
cenyl moieties.
signal close to 0.0 V which is a putative adsorption pre-peak. This
adsorption was confirmed by a decrease of the peak signals with
the recording of consecutive scans.
Organic compounds were also investigated by the CV and SWV
techniques. 5a shows an irreversible signal around 1.5 V, which
is very close to the anodic wall followed by a very small peak
that is almost imperceptible since it is close to the anodic wall.
Meanwhile 5b shows three main signals: one of them is a quasi-
reversible system (~ −0.8 V). The other electronic exchanges be-
gin in a potential value very close to the cathodic barrier. It seems
that there is adsorption of the compound in the electrode surface,
which is evident because the signals in CV voltammograms are
decreasing after consecutive sweeps. Additionally, traces show an
intersection of currents between forward and reverse sweeps that
confirm surface effects.
Their redox properties make 1,2-diaryl- and 1,2-dimetalocenyl-
3-one and 1,2-dimetallocenyl-3-thiones interesting products from a
pharmacological point of view. Further investigation of these com-
pounds may lead to the development of effective and safe agents
for the prevention of diseases in humans by the synergistic combi-
nation of electrochemical and biological approaches.
The electrochemical parameters for compounds are shown in
Table 5. Here the cyclic voltammogram parameters are summa-
rized for each compound at a 100 mV/s scan rate. The ࢞Ep val-
ues obtained from the 1 to 2 oxidation processes for diferrocenyl
moieties for 5c and 6c range from 0.056 V to 0.065 V. E1/2(1) and
E1/2(2) values are used to calculate the characteristic compropor-
tionation constant Kcom [27-29], which is very common in ferro-
cenyl compounds. According to the Kcom values, the diferrocenyl
compounds 5c and 6c were categorized as type II in accordance
with the Robin-Day classification since 106 > Kcom > 102 (partially
delocalized electronic charge in the mixed-valence state generated
electrochemically (Table 9 see supplementary material)) [30-31].
Evaluation of the diruthenocenyl Kcom compound 5d was not pos-
sible due to its irreversibility pattern.
4. Experimental
4.1. Materials and instrumentation
All the solvents were dried according to the standard proce-
dures and freshly distilled before use. Column chromatography
was carried out on alumina (Brockmann activity III). The 1H and
13C NMR spectra were recorded on a Unity Inova Varian spec-
trometer (400-MHz and 100 MHz) for solutions in CDCl3 with
Me4Si as the internal standard. Chemical shifts (δ in ppm) were
reported with respect to the residual solvent peaks as internal
standard (1H: CDCl3, δ= 7.26 ppm, 13C: CDCl3, δ= 77.2 ppm),
δ values were measured with precision 0.01 ppm. The IR spec-
7

J.J. Sánchez García, R.S. Joo-Cisneros, D. García-Bassoco et al.
Journal of Organometallic Chemistry 944 (2021) 121809
tra were measured on a spectrophotometer FT-IR (Spectrum RXI
Perkin Elmer 400 instruments) using KBr pellets. The mass spectra
were obtained on a Varian MAT CH-6 instrument (EI MS, 70 eV).
An Elementar Analysensysteme LECO CHNS-900 was used for el-
emental analyses. The following reagents were purchased from
Aldrich: ferrocene, 98%; aluminum chloride, 99.99%; tetrachlorocy-
clopropene, 98%, sulfur 99%, sodium hydrosulfide hydrate; Lawes-
son reagent, 97%; bis(cyclopentadienyl)ruthenium, 97%; anisole an-
hydrous, 99.7%; benzene anhydrous, 99.8%; hydrazine monohy-
drate, 98%.
C17 H14 O3S2 (330): C, 61.79; H, 4.27; S, 19.41; Found: C, 61.58; H,
4.37; S, 19.45%. MS (El, 70 eV): m/z 330 [M]+.
4,5-Diferrocenyl-1,2-dithiol-3-one 5c: red crystals, yield
3.0 mmol (60%), m.p. 196 °C (lit. [24a]) 195–197 °C). IR (KBr):
ν 485, 539, 661, 749, 817, 1000, 1027, 1108, 1141, 1255, 1296, 1410,
1459, 1506, 1602, 2837, 2927, 3082 cm−1 1H NMR (400 MHz,
.
CDCl3): δ 4.06 (5H, s, C5H5), 4.24 (5H, s, C5H5), 4.17 (2H,
m, C5H4), 4.22 (2H, m, C5H4), 4.40 (4H, m, C5H4). 13C NMR
(100 MHz, CDCl3): δ 69.56, 70.53 (2C5H5), 67.89, 68.97, 69.47,
70.59 (2C5H4), 78.33, 79.98 (2CipsoFc), 128.28, 161.77 (2C), 192.31
(C=O). Anal. calcd. for C23H18 Fe2OS2 (486): C, 56.80; H, 3.73; S,
13.19; Found: C, 56.80; H, 3.70; S, 13.23%. MS (El, 70 eV): m/z
486 [M]+.
4.2. General procedure for the synthesis of cyclopropenones
4,5-Diruthenocenyl-1,2-dithiol-3-one 5d: yellow crystals, yield
2.5 mmol (50%), m.p. 214–215 °C. IR (KBr): ν 424, 460, 614, 722,
744, 808, 995, 1009, 1070, 1099, 1173, 1246, 1296, 1408, 1461,
The AlCl3 (0.67 g, 5 mmol) was added by portions to a solu-
tion of one of the compounds 2a-d (25 mmol) and tetrachloro-
cyclopropene (12.5 mmol) in anhydrous CH2Cl2 (200 mL) un-
der continuous stirring for 30 min. The stirring was continued
for another 90 min at room temperature, then the mixture was
poured in cold water (200 mL). The organic layer was sepa-
rated, washed with water (2 × 50 mL) and dried with MgSO4.
After the solvent was distilled off in vacuo, the residue was
1522, 1562, 1649, 2850, 2924, 2969, 3079, 3199 cm−1 1H NMR
.
(400 MHz, CDCl3): δ 4.49 (s, 5H, C5H5), 4.68 (s, 5H, C5H5), 4.54
(m, 2H, C5H4) 4.60 (m, 1H, C5H4), 4.72 (m, 2H, C5H5), 4.75 (m,
1H, C5H4), 4.83 (m, 2H, C5H4). 13C NMR (100 MHz, CDCl3): δ
71.50, 72.67 (2C5H5), 70.04, 70.79, 71.35, 73.17 (2C5H4), 81.37,
85.42 (2CipsoRc), 129.19, 160.24 (2C), 201.01 (C=O). Anal. calcd. for
C23H18 ORu2S2 (576.5): C, 47.91; H, 3.14; S, 11.10; Found: C, 47.80;
H, 3.28; S, 11.20%. MS (El, 70 eV): m/z 577 [M]+.
chromatographed on Al2O3 using
a hexane-CH2Cl2 (3:1) mix-
ture as eluent to afford compounds 2,3-diphenylcyclopropenone
3a, yield, 1.64 g, 7.8 mmol (63%), m.p. 120–121 °C (lit.: m.p.
121–121.5 °C [32]), 2,3-bis(4-methoxyphenyl)cyclopropenone 3b,
yield, 2.23 g, 8.4 mmol (67%), m.p. 153–154 °C (lit.: m.p.153–
155 °C [33]), 2,3-diferrocenyl-cyclopropenone 3c, yield, 4.5 g,
10.6 mmol (85.3%), m.p. 182–184 °C (lit.: m.p. 182–183 °C [20]),
2,3-diruthenocenylcyclopropenone 3d, yield, 3.8 g, 7.5 mmol (60%),
m.p. 256–258 °C (lit.: m.p. 256–257 °C [24b]).
The 2,3-diferrocenylcyclopropenthione 4c was prepared from
2,3-diferrocenylcyclopropenone 3c and Lawesson reagent [22a] in
benzene [22b], yield 76%, m.p. 207–209 °C (lit.: m.p. 208–209 °C
[22b]).
4,5-Diphenyl-1,2-dithiol-3-thione 6a: red crystals, yield
0.5 mmol (10%), m.p. 159–161 °C (lit [13a, 34]), 159.0–160 °C). IR
(KBr): ν 460, 480, 525, 670, 750, 810, 830, 880, 900, 1010, 1050,
1080, 1120, 1200, 1310, 1340, 1380, 1420, 1455, 1570, 1640, 1725,
2930, 2960, 3006, 3028, 3079, 3105 cm−1 1H NMR (400 MHz,
.
CDCl3): δ 7.12–7.17 (m, 2H, C6H4), 7.22–7.25 (m, 2H, C6H5), 7.28–
7.39 (m, 6H, C6H5), 13C NMR (100 MHz, CDCl3): δ 133.10, 134.20
(2C), 128.36, 128.45, 128.84, 128.96, 130.53, 131.0 (2C6H5), 145.74,
170.60 (2C), 215.30 (C=S), Anal. calcd. for C15H10S3 (286): C, 62.90;
H, 3.52; S, 33.59; Found: C, 62.85; H, 3.53; S, 33.63%. MS (El,
70 eV): m/z 286 [M]+.
4,5-bis(4-methoxyphenyl)−1,2-dithiol-3-thione 6b: White crys-
tals, yield 0.6 mmol (12%), m.p. 180 °C (lit. [35]), m.p.179 °C). IR
(KBr): ν 506, 615, 690, 736, 765, 796, 845, 1031, 1071, 1102, 1299,
4.3. Reactions of 2,3-diaryl- and 2,3-dimetallocenylcyclopropenone
3a,b with elemental sulfur
1442, 1483, 1559, 1640, 1654, 3058 cm−1 1H NMR (400 MHz,
.
An elemental sulfur (5 mmol) in benzene (80 mL) was added to
corresponding 2,3-diaryl- or 2,3-dimetallocenylcyclopropenone 3a-
d (5.0 mmol). The reaction mixture was stirred and was heated to
refluxing conditions (8 h). The solvent was removed in vacuo and
the residue was dissolved in dichloromethane (30 mL). The solu-
tion was mixed with Al2O3 (20 g) and the solvent was evaporated
in the air. This material was placed on the top of a column with
Al2O3 (the height of alumina is ca. 20 cm) and the elution was
performed first with hexane and then with hexane - diethyl–ether
(1:1) as eluent to afford compounds 5a-d.
CDCl3): δ 3.80 (s, 3H, CH3), 3.88 (s, 3H, CH3), 6.86 (d, 2H,
J = 8.0 Hz, C6H4), 7.06 (d, 2H, J = 8.0 Hz, C6H4), 7.44 (d, 2H,
J = 8.0 Hz, C6H4), 7.92 (d, 2H, J = 8.0 Hz, C6H4,). 13C NMR
(100 MHz, CDCl3): δ 55.45, 55.62 (2CH3), 114.47, 114.60, 130.34,
131.91 (2C6H4), 115.79, 119.04, 126.88, 131.57, 132.36, 179.75 (6C),
215.68 (C=S). Anal. calcd. for C17 H14 O2S3 (346.5): C, 58.93; H, 4.07;
S, 27.76; Found: C, 58.80; H, 4.10; S, 27.80%. MS (El, 70 eV): m/z 346
[M]+.
4,5-Diferrocenyl-1,2-dithiol-3-thione 6c: Black powder, yield
0.75 mmol (15%), m.p. 225–226 °C. IR (KBr): ν 467, 482, 705,
749, 813, 887, 1008, 1026, 1071, 1105, 1169, 1195, 1246, 1260,
1295, 1389. 1410, 1457, 1494, 1536, 1650, 1725, 2855, 2922, 2956,
4,5-Diphenyl-1,2-dithiol-3-one 5a: yellow crystals, yield
3.0 mmol (60%), m.p. 117–118 °C (lit. [13a]), 116 °C). IR (KBr):
ν 506, 615 690, 764, 796, 1070, 1101, 1299, 1441, 1559, 1639, 1959,
3087 cm−1 1H NMR (400 MHz, CDCl3): δ 4.12 (s, 5H, C5H5),
.
3057 cm−1 1H NMR (400 MHz, CDCl3): δ 7.12–7.15 (m, 2H, C6H5),
.
7.24–7.32 (m, 8H, C6H5). 13C NMR (100 MHz, CDCl3): δ 128.13,
128.46, 128.49, 128.91, 130.22, 130.48 (2C6H5), 130.69, 132.55,
133.92, 165.69 (4C), 193.67 (C=O). Anal. calcd. for C15H10OS2
(270): C, 66.63; H, 3.73; S, 23.72; Found: C, 66.78; H, 3.70; S,
23.68%. MS (El, 70 eV): m/z 270 [M]+.
4.19 (s, 5H, C5H5), 4.20 (m, 2H, C5H4), 4.35 (m, 2H, C5H4) 4.39
(m, 2H, C5H4), 4.40 (m, 2H, C5H4). 13C NMR (100 MHz, CDCl3):
δ 69.66, 70.87 (2C5H5), 67.40, 69.69, 70.09, 71.40 (2C5H4), 79.58,
80.02 (2CipsoFc), 141.32, 170.59 (2C), 213.95 (C=S). Anal. calcd. for
C23H18 Fe2S3 (502): C, 55.02; H, 3.61; S, 19.15; Found: C, 55.10; H,
3.71; S, 19.22%. MS (El, 70 eV): m/z 502 [M]+.
4,5-bis(4-methoxyphenyl)−1,2-dithiol-3-one 5b: white crystals,
yield 3.25 mmol (65%), m.p.144–145 °C. IR (KBr): ν 474, 827, 1026,
1044, 1059, 1105, 1230, 1254, 1325, 1408, 1447, 1532, 1621, 1731,
4,5-Diruthenocenyl-1,2-dithiol-3-thione 6d: Yellow powder,
yield 0.6 mmol (12%), m.p. 184–185 °C. IR (KBr): ν 467, 481,
812, 1007, 1209, 1409, 1457, 1649, 1724, 2854, 2921, 2956, 3087,
2950, 3099 cm−1 1H NMR (400 MHz, CDCl3): δ 3.79 (s, 3H, CH3),
.
3309, 3923.cm−1 1H NMR (400 MHz, CDCl3): δ 4.11 (s, 5H, C5H5),
.
3.80 (s, 3H, CH3), 6.80 (d, 2H, J = 4.0 Hz, C6H4), 6.83 (d, 2H,
J = 4.0 Hz, C6H4), 7.07 (d, 2H, J = 8.0 Hz, C6H4), 7.19 (d, 2H,
J = 8.0 Hz, C6H4). 13C NMR (100 MHz, CDCl3): δ 55.19, 55.34
(2CH3), 114.05, 114.33, 129.95, 131.44 (2C6H4), 125.02, 126.39,
129.32, 159.25, 161.2, 164.70 (6C), 193.94 (C=O). Anal. calcd. for
4.16 (s, 5H, C5H5), 4.24 (m, 2H, C5H4) 4.33 (m, 2H, C5H4), 4.41
(m, 2H, C5H4), 4.54 (m, 2H, C5H4). 13C NMR (100 MHz, CDCl3):
δ 68.92, 70.10 (2C5H5), 67.47, 68.21, 68.79, 70.59 (2C5H4), 78.56,
82.81 (2CipsoFc), 135.79, 165.24 (2C), 204.89 (C=S). Anal. calcd. for
8

J.J. Sánchez García, R.S. Joo-Cisneros, D. García-Bassoco et al.
Journal of Organometallic Chemistry 944 (2021) 121809
C23H18 Ru2S3 (592.5): C, 46.62; H, 3.06; S, 16.20; Found: C, 46.50;
H, 3.06; S, 16.30%. MS (El, 70 eV): m/z 593 [M]+.
are referred to as Ferrocenium/Ferrocene (Fc+/Fc) couple [36]. Elec-
trodes were: 1) working, 2 mm diameter glassy carbon electrode
(GCE); 2) the reference was a AgNO3/Ag electrode (a silver wire
immersed in 0.01 mol/L AgNO3 + 0.1 mol/L tetrabutylammonium
hexafluorophosphate / acetonitrile), and 3) counter was a platinum
wire. In some recordings, cleaning the GCE with CH2Cl2 or CH3CN
was sufficient, however when this was not sufficient, the electrode
surface was polished with 0.5 μm alumina (Buehler, master prep),
rinsed with water, sonicated for 8 min in deionized water, rinsed
once again with water and/or dichloromethane and dried with a
clean tissue (Kimtech). The anhydrous solvents were kept in 4A
molecular sieve and handled using cannulas. Solutions were deaer-
ated with ultra-high purity argon (Infra, previously saturated with
CH3CN) for at least 5 min before starting the recordings. Cyclic
voltammograms were recorded in Bu4NPF6 0.1 mol/L /CH3CN at
0.03 to 0.18 V/s. In DPV, the pulse amplitude was from 10 mV
to 100, each 10 mV. In SWV, the frequencies were 5, 10, 15, 20,
30, and 50 Hz. In CV, experimental anodic and cathodic peak po-
tentials determined the half-wave potentials (E1/2 = (Epa + Epc)/2)
[37]. In the case of DPV, the formal potential E0 ≈ E1/2 was eval-
uated using the expression E1/2 = Ep + ࢞E/2; for SWV, E1/2 = Ep.
The potentials are referred to as Ferrocenium/Ferrocene (Fc+/Fc)
couple [29]. A Faraday cage (BAS) shielded the cell. The CHI660A
or EDAQ 161 potentiostats commanded by their commercial soft-
ware elicited all recordings.
4.4. Reactions of 4,5-diferrocenyl-1,2-dithiol-3-thione 6c with
hydrazine hydrate
To compound 6c (5.0 mmol) in ethanol (80 mL) was added
hydrazine hydrate (5.0 mmol). The reaction mixture was stirred
and was heated to refluxing conditions (8 h). The solvent was re-
moved in vacuo and the residue was dissolved in dichloromethane
(30 mL). The solution was mixed with Al2O3 (20 g) and the solvent
was evaporated in the air. This material was placed on the top of
a column with Al2O3 (the height of alumina is ca. 20 cm) and the
elution was performed first with hexane and then with hexane -
diethyl–ether (1:1) as eluent to afford hydrazone 7c.
(4,5-diferrocenyl-1,2-dithiol-3-ylidene) hydrazine 7c: Yellow
powder, yield 2.25 mmol (45%), m.p. 190–192 °C. IR (KBr): ν 467,
482, 705, 749, 813, 887, 1008, 1026, 1071, 1105, 1169, 1195, 1246,
1260, 1295, 1378, 1410, 1457, 1494, 1660, 1724, 2855, 2922, 3088,
3310 cm−1 1H NMR (400 MHz, CDCl3): δ 4.01 (s, 5H, C5H5), 4.22
.
(s, 5H, C5H5), 4.12 (m, 2H, C5H4), 4.21 (m, 1H, C5H4), 4.27 (m, 1H,
C5H4), 4.32 (m, 4H, C5H4), 5.08 (bs, 2H, NH2). 13C NMR (100 MHz,
CDCl3): δ 69.51, 70.12 (2C5H5), 67.34, 68.80, 70.09, 70.57 (4C5H4),
79.60, 79.80 (2Cipso Fc), 128.78, 130.88 (2C), 157.03 (C=N). Anal.
calcd. for C23H20Fe2N2S2 (500): C, 55.24; H, 4.03; N, 5.60; S, 12.78;
Found: C, 55.40; H, 4.02; N, 5.44; S, 12.70%. MS (El, 70 eV): m/z
500 [M]+.
4.5.1. Single crystal X-ray diffraction
A suitable single crystal of compounds 5a, 5b and 5d were
mounted on a glass fiber and crystallographic data were col-
lected with an Oxford Diffraction Gemini "A" diffractometer
with a CCD area detector with monochromator of graphite for
4.5. Electrochemical measurements
Compounds were studied using three different voltammetries:
Cyclic (CV), differential pulse (DPV), and square wave (SWV)
voltammetries were carried out in a conventional three-electrode
cell shielded by a Faraday cage (BAS). All potentials reported here
˚
λMoKα = 0.71073 A. CrysAlisPro and CrysAlis RED software pack-
ages were used for data collection and integration [38]. The double
pass method of scanning was used to exclude any noise. The col-
Table 6
Crystal data and structure refinement for compounds 5a, 5b and 5d.
Identification code
5a
5b
5d
Empirical formula
Formula weight
Temperature
C15 H10 O S2
270.35
C17 H14 O3 S2
330.40
C23 H18 O Ru2 S2
576.63
130(2) K
130(2) K
130(2) K
˚
˚
˚
Wavelength
0.71073 A
0.71073 A
0.71073 A
Crystal system
Space group
Orthorhombic
P 21 21 21
Orthorhombic
P 21 21 21
Monoclinic
P 21/c
˚
˚
˚
Unit cell dimensions
a = 6.0597(6) A
a = 5.5429(4) A
a = 5.7774(3) A
˚
˚
˚
b = 11.9488(12) A
b = 15.9788(13) A
b = 17.4334(7) A
˚
˚
˚
c = 17.490(2) A
c = 17.1104(11) A
c = 19.1127(11) A
α= 90°
α= 90°
β= 90°
α= 90°
β= 90°
β= 93.019(5)°.
γ = 90°
γ = 90°
γ = 90°
3
3
3
˚
˚
˚
Volume
1266.4(2) A
1515.45(19) A
1922.35(17) A
Z
4
4
4
Density (calculated)
Absorption coefficient
F(000)
1.418 Mg/m3
0.403 mm-1
560
1.448 Mg/m3
0.360 mm-1
688
1.992 Mg/m3
1.800 mm-1
1136
Crystal size (mm3)
0.400 × 0.180 × 0.020
0.540 × 0.090 × 0.080
3.489 to 29.411°
0.580 × 0.050 × 0.050
3.409 to 29.525°
Theta range for data collection 3.558 to 29.476°
Index ranges
−8<=h<=5, −16<=k<=10, −23<=l<=22 −5<=h<=7, −12<=k<=20, −23<=l<=14 −7<=h<=7, −24<=k<=23, −25<=l<=24
Reflections collected
5073
4964
13,075
Independent reflections
Completeness to theta =
Absorption correction
Max. and min. transmission
Refinement method
2866 [R(int) = 0.0414]
99.7%
3243 [R(int) = 0.0337]
99.7%
4602 [R(int) = 0.0396]
99.8%
Analytical
Analytical
Analytical
0.647 and 0.067
Full-matrix least-squares on F2
2866 / 0 / 163
0.973 and 0.955
Full-matrix least-squares on F2
3243 / 0 / 201
1.043
0.916 and 0.613
Full-matrix least-squares on F2
4602 / 0 / 229
1.082
Data / restraints / parameters
Goodness-of-fit on F2
Final R indices [I>2sigma(I)]
R indices (all data)
1.076
R1 = 0.0662, wR2 = 0.1384
R1 = 0.1075, wR2 = 0.1725
−0.04(11)
R1 = 0.0469, wR2 = 0.1018
R1 = 0.0563, wR2 = 0.1078
0.03(6)
R1 = 0.0378, wR2 = 0.0790
R1 = 0.0481, wR2 = 0.0843
n/a
Absolute structure parameter
Largest diff. peak and hole
-3
-3
-3
˚
˚
˚
0.758 and −0.454 e.A
0.532 and −0.318 e.A
1.053 and −0.753 e.A
9

J.J. Sánchez García, R.S. Joo-Cisneros, D. García-Bassoco et al.
Journal of Organometallic Chemistry 944 (2021) 121809
lected frames were integrated by using an orientation matrix de-
termined from the narrow frame scans. Final cell constants were
determined by a global refinement; collected data were corrected
for absorbance by using analytical numeric absorption correction
using a multifaceted crystal model based on expressions upon
the Laue symmetry with equivalent reflections [39]. Structures so-
lutions and refinement were carried out with the SHELXS-2014
[40] and SHELXL-2014 [41] packages. WinGX v2018.3 [42]. and
Mercury CSD 4.1.3 [43]. Software was used to prepare material for
publication. Full-matrix least-squares refinement was carried out
by minimizing (Fo2 – Fc2)2. All non-hydrogen atoms were refined
anisotropically. H atoms attached to C atoms were placed in geo-
metrically idealized positions and refined as riding on their parent
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Declaration of Competing Interest
The authors declare that they have no known competing finan-
cial interests or personal relationships that could have appeared to
influence the work reported in this paper.
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Acknowledgments
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This research was funded by DGAPA–UNAM (Mexico, grant IN
217421) and CONACyT (Mexico, grant CB-2015/251437). We ac-
knowledge the personal and instrumental support of the Unit for
Industry and Research Support (USAII) at the Faculty of Chem-
istry of the UNAM, México. We are grateful for the technical assis-
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Supplementary materials
Supplementary material associated with this article can be
found, in the online version, at doi:10.1016/j.jorganchem.2021.
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