Coordination and electrochemistry of new substituted manganese phthalocyanines

Article abstract of DOI:10.1142/S1088424612501015

A number of substituted manganese phthalocyanines PcMn have been synthesized from the corresponding phthalonitriles with rather good yields (up to 67%) and high purity. All complexes were characterized by elemental analysis, electronic absorption spectra, and some of them by redox potentials. Three coordination forms - PcMn(II), PcMn(III)X and [LPcMn(III)]₂O were fixed for all complexes. The equilibrium of three electronic isomers - Pc ^+· Mn(I) × L, PcMn(II) × L_n and Pc ^-· Mn(III) × 2L has been observed in solutions of all PcMn(II) in the presence of organic base L. Copyright

Full text of DOI:10.1142/S1088424612501015

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2012; 16: 946–957
DOI: 10.1142/S1088424612501015
Published at http://www.worldscinet.com/jpp/
Coordination and electrochemistry of new substituted
manganese phthalocyanines
Olga Dolotova*◊, Alexandr Konarev, Konstantin Volkov, Vladimir Negrimovsky◊
and Oleg L. Kaliya◊
Organic Intermediates and Dyes Institute, B. Sadovaya ¼, Moscow 123995, Russia
Dedicated to Professor Tebello Nyokong on the occasion of her 60th birthday
Received 29 February 2012
Accepted 24 April 2012
ABSTRACT: A number of substituted manganese phthalocyanines PcMn have been synthesized from
the corresponding phthalonitriles with rather good yields (up to 67%) and high purity. All complexes
were characterized by elemental analysis, electronic absorption spectra, and some of them by redox
potentials. Three coordination forms — PcMn(II), PcMn(III)X and [LPcMn(III)]2O were fixed for all
complexes. The equilibrium of three electronic isomers — Pc+· Mn(I) × L, PcMn(II) × Ln and Pc-· Mn(III)
× 2L — has been observed in solutions of all PcMn(II) in the presence of organic base L.
KEYWORDS: manganese phthalocyanines, synthesis, coordination forms, electronic isomers,
electronic absorption spectra, electrochemistry.
INTRODUCTION
RESULTS AND DISCUSSION
Metal phthalocyanines (PcM) are a very important
class of compounds because of their diverse properties
and applications. Interest in manganese phthalocyanine
(PcMn) has emerged more than half a century ago
and continues till now [1–13]. Major interest in PcMn
along with PcFe lies in the high catalytic activity of
this compound. Among the last publications on PcMn
[14–26] only a few studies deal with coordination
properties, although the variety of PcMn coordination
and valence forms makes the investigation of its
coordination chemistry of considerable importance. We
have previously suggested the full scheme of photo and
dark transformations of PcMn derivatives in solutions
(Scheme 1, [13]). Herein we wish to present the
investigation of this scheme validity for the series of new
substituted manganese phthalocyanines with diversified
electronic and steric peculiarities.
Synthesis of substituted manganese phthalocyanines
The procedure, which is based on the anhydrous
manganese acetate heating in sealed tube with
corresponding phthalonitriles 1–6, was applied to the
synthesis of new substituted in benzene rings PcMn
7–12 (where Pc = phthalocyanine dianion Pc2-, Scheme
2). For the first time complex 11 was mentioned [27]
simultaneously with our colleagues from South Africa,
who studied some properties of this complex in solution
and as self-assembled monolayers on gold [14].
In the course of the synthesis species 7–12 are formed
as Mn(II) complexes PcMn(II) (form c, Scheme 1,
2, Table 1), which oxidize to the PcMn(III)X (form a,
Scheme 1, Table 1) during purification in air. Purification
was carried out using column chromatography with
neutral alumina as column material and CHCl3 or CCl4
as eluent. Counter-ion X- in this case is chloride anion.
Complex 10 (Table 1) treatment in air does not lead to
complete Mn(II) oxidation but instead results in isolation
of stable in air form c during 10 purification done by
column chromatography with benzene. Our earlier
SPP full member in good standing
*Correspondence to: Olga Dolotova, email: oldolotova@
yandex.ru, tel: +7 (495)-408-5947, fax: +7 (499)-254-7015
Copyright © 2012 World Scientific Publishing Company

COORDINATION AND ELECTROCHEMISTRY OF NEW SUBSTITUTED MANGANESE PHTHALOCYANINES
947
Since the electronic absorption
spectra are the most informative
method of Pc characterization, it
was chosen as a main research and
description mean for our study.
Coordination chemistry of sub-
stituted manganese phthalo-
cyanines
Monomeric
manganese(III)
phthalocyanines 7a–12a. We star-
ted our investigation by focusing
on the most stable under ambient
conditions PcMn form — monomer
PcMn(III)X, form a (Scheme 1,
Table 1).
Scheme 1. Transformations of valence and coordination forms of PcMn derivatives in
solutions [13]
Electronic absorption spectra of
7a–12a solutions are typical for PcMn(III)X derivatives [10]
and demonstrate Q-bands in region 700–800 nm, B-bands
in region 300–400 nm and ligand-to-metal charge transfer
bands near 500 nm (Table 1, Fig. 1). Spectra of compounds
9a and 11a have two charge transfer bands with maxima
449, 525 nm and 464, 534 nm, accordingly (Fig. 1).
The broadening of the Q-band in 10a spectrum in non-
coordinating organic solvents has been observed. This
effect is probably caused by the complex aggregation in
solution.
studies [13, 28] had shown that form a is the most stable
in non-coordinating solvents under ambient conditions
for PcMn bearing neutral and electron-donating groups.
It seems that in the case of complex 10 electron-
withdrawing substituents stabilize PcMn(II).
Dimeric species [LPcMn(III)]2O (form b, Scheme 1,
Table 1) have been also obtained as admixtures during
10 and 12 purification by column chromatography with
acetone (L = C3H6O).
Substituted metal-free Pcs have been isolated as the
reaction by-products in compounds 7 and 8 synthesis.
All compounds obtained possess high solubility in
non-coordinating organic solvents such as benzene,
chloroform and CCl4.
As stated in previously reported publications [13, 28]
the Q-band position of PcMn(III)X derivatives strongly
depends on the electronic nature of substituents and shift
could achieve up to 140 nm.Actually, we can see (Table 1,
Scheme 2. Synthetic route for the nitriles 1–6 and substituted PcMn 7–12
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Our results for the addition of
organic bases L to 7a–12a solutions
are puzzling. Transformation of the
form a into the corresponding form
b in this way was achieved only for
three complexes — 9b, 10b and 12b
(Scheme 1, Table 1). Unexpectedly, in
other cases reaction failed. Treatment
of compounds 7a, 8a and 11a with
coordinating organic bases in air did
not lead to the expected products 7b,
8b and 11b and starting materials were
recovered in all cases.
Complex 11b has been obtained only
by treatment of 11a chloroform solution
with Et3N-KOH-acetone mixture in
air. It is reasonable to assume that
reaction results first in 11c complex to
give then 11b.
It was rather difficult to obtain
compounds 7b and 8b. We speculated
Fig. 1. UV-vis spectra of monomers PcMn(III)Cl: 7a (a), 9a (b), 11a (c), 12a (d),
chloroform, l = 1 cm
that the reason of this effect are steric hindrances of the
bulky tert.butylsulfanyl groups in a-positions of the
benzene rings. It is known, for example that PcMn with
non-coplanar ortho-chlorphenyl groups in a-positions of
the benzene rings does not form the corresponding m-oxo
dimer under the described conditions [32]. An efficient
synthesis of the m-oxo dimers 7b and 8b has been
achieved by addition of hot water to 7a and 8a pyridine
solutions in the presence of triethylamine in air. Firstly
the reduction of form a to form c by triethylamine takes
place and only 24 h later the formation of m-oxo dimers
7b and 8b is observed. Taking into account the difficulty
of 7b and 8b formation, it is reasonable to assume that
these complexes may be of interest as catalysts for the
oxidation reactions in weakly alkaline solution where
dimerization of PcMn leads to the loss of their catalytic
activity.
Dimers 10b and 12b have been also obtained in
a mixture with 10a and 12a in course of 10 and 12
purification done by column chromatography with
acetone. The equilibrium between 12a and 12b is very
mobile; acetone shifts it to dimer and chloroform — to
monomer form. Reversible 10b formation has been
observed after isopropanol addition to the 10a chloroform
solution. Back process of monomer formation proceeded
on the diluted HCl addition. The last reaction is typical
for PcMn(III) m-oxo dimers and has been observed for all
complexes 7b–12b.
Fig. 1) that Q-bands of 7a–12a are bathochromically
shifted relatively unsubstituted analog. It is known [14,
15, 29] that sulfanyl substituents cause more significant
red shift as compared with alkoxy groups. Table 1 data
represent an unquestionable evidence of this statement:
the biggest red shift (71 nm) compared to unsubstituted
analog has been registered for compound 10a bearing
eight decylsulfanyl groups and the least shift (20 nm) has
been obtained for the complex 12a substituted with four
dodecafluoroheptyloxy groups.
If compared to the spectrum of complex 7a bearing
four tert-butylsulfanyl groups in a-positions (lmax
in chloroform 745 nm) with its earlier reported
b-substituted analog (lmax in chloroform 734 nm [28]),
it becomes evident that a-substitution causes the
more strong shift of the Q-band in comparison with
b-substitution. This observation confirms the known fact
that the a-substitution has more strong influence on Pc’s
properties as compared with b-substitution [30–32].
Q-band of 8a (lmax in chloroform 751 nm) is red
shifted as compared with 7a (lmax in chloroform 745
nm) due to the additional donating effect of tert.butyl
groups.
Solvatochromism of Pcs is well known phenomenon
[3], which manifests as Pc’s Q-band position dependence
on the solvent nature. For example, maximum of 12a
Q-band differs from 722 nm in benzene to 732 nm in
acetone and to 737 nm in CCl4 and chloroform.
Dimeric manganese(III) phthalocyanines 7b–12b.
Earlier studies have shown that monomers PcMn(III)X
react with coordinating organic bases (L) such as pyridine,
4-aminopyridine, imidazol in the presence of water in air
to give quantitative yields of the corresponding m-oxo
species [LPcMn(III)]2O (form b, Scheme 1, Table 1) [5,
6, 11, 13, 32].
Electronic absorption spectra of 7b–12b are
characteristic of PcMn(III) m-oxo species [7] and
demonstrate broadened Q-bands near 640–680 nm and
B-bands near 330 nm (Table 1). Q-bands in 7b–12b
spectra are about 100 nm blue shifted relative to Q-bands
of the corresponding forms a (Table 1). The dependence
of forms b Q-bands positions on the substituent nature is
rather significant. The biggest red shift (63 nm) relatively
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O. DOLOTOVA ET AL.
unsubstituted analog has been
registered for compound 10b
and the least shift (16 nm) has
been obtained for the complex
12a (Table 1). Interestingly,
the same dependence has been
observed in the case of forms a
(see above).
In summary, the results
described in this part of the
work show that all the six new
PcMn 7–12 can exist in two
PcMn(III) forms: monomeric
PcMn(III)X and m-oxo dimers
[LPcMn(III)]2O. Different ways
were used for each complex b
formation. Rather elusive were
complexes 7b and 8b.
Manganese(II) phthalocya-
nines 7c–12c. The next group
of PcMn valence forms are
Fig. 2. UV-vis spectrum of PcMn(II) × Pyn formation from 8a in triethylamine after Py
addition, n = 1, 2; 0.5 min (1), 0.5 h (2), l = 1 cm
PcMn(II) derivatives. The procedure, which is based
on the form a or form b reduction by triethylamine or
potassium hydroxide-water-acetone mixture in anaerobic
conditions [11, 13, 32], was applied to the synthesis of
PcMn(II) (form c, Table 1).
As usual these complexes are unstable in air in
solutions. We have previously described two compounds
which have proved to be resistant to air — complexes
with eight strong electron-withdrawing substituents —
octanitro- and octa(phenylsulfonyl) substituted PcMn(II)
(form c) [13]. This property allows use them as catalysts
in oxidation processes [33]. These compounds can be
converted into the corresponding PcMn(III)OAc (form
a) by treatment with acetic acid in air.
We now report new stable in air in solution
PcMn(II) — compound 10c bearing electron-with-
drawing substituents (Table 1). Complex 10c has been
isolated at 10 reaction mixture purification by column
chromatography over neutral alumina with benzene
as eluent (see above). The reduction of 10a or 10b
also results in stable in air in solution complex 10c.
Generally the reduction of PcMn(III) derivatives in air
results in back oxidation or in destruction of PcMn(II).
Such destruction can be very quick (for compound 12c)
or rather slow (for complex 8c).
Electronic absorption spectra of 7c–12c in non-
coordinating organic solvents are characteristic of
PcMn(II) species and demonstrate Q-bands in range
680–720 nm and B-bands in range 300–360 nm (Table
1). Charge-transfer bands at 500 nm are absent in 7c–12c
spectra. Q-bands of 7c–12c in non-coordinating organic
solvents are about 60 nm blue shifted compared to the
Q-bands of 7a–12a (Table 1). The broadening of the
complex 10c spectrum in non-coordinating organic
solvents has been observed. Probably, similar to 10a this
effect is caused by the complex aggregation in solution.
The dependence of forms c Q-bands positions on the
substituent nature is less significant in comparison with
forms a and b. The biggest red shift (49 nm) relatively
unsubstitutedanaloghasbeenregisteredforthecompound
10c and the least shift (4 nm) has been obtained for the
complex 12c (Table 1). The same regularities have been
observed in the cases of forms a and b (see above).
Electronic isomers of manganese(II) phthalo-
cyanines. As part of our continued interest in the PcMn(II)
electronic isomers existence [13, 32], we decided to
investigate the scope and limitations of this phenomenon
for the studied compounds. Complexes 7c–12c were
reacted with organic bases in inert atmosphere and
this reaction afforded the electronic isomers mixture
Pc+.Mn(I) × L, PcMn(II) × Ln and Pc-.Mn(III) × 2L. That
manifests as significant changes in 7c–12c electronic
absorption spectra (Fig. 2).
Our earlier studies of such multiband spectra [13,
32] and literature data on Pc radical absorption spectra
[34–36] had shown that bands at 480 nm and 840 nm
correspond to the species Pc-. Mn(III) × 2Py, bands at 570
nm and 880 nm — to the species Pc+.Mn(I) × Py, and the
most intensive bands at 660–680 nm correspond to the
mixture of PcMn(II) × Py and PcMn(II) × 2Py (Fig. 2,
Scheme 3). The intensities of all bands in multiband
spectra relatively intensity of the B-band of neutral
molecules PcMn(II) × nPy are shown in Table 1.
The phenomenon of electronic isomers mixture
existence has a good explanation in terms of the
crystal-field theory [32]. The relative intensities of the
radical species bands depend on the substituent nature:
complexes with electron-donating groups have more
intensive cation-radical bands and vice versa complexes
with electron-withdrawing groups have more intensive
anion-radical ones (Table 2, Fig. 3). For example, the
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COORDINATION AND ELECTROCHEMISTRY OF NEW SUBSTITUTED MANGANESE PHTHALOCYANINES
951
proposed Pc-. Mn(II) as a result of the first step of
unsubstituted PcMn(II) electrochemical reduction,
based on its spectrum similarity with the spectra of
Pc-. Mg and Pc-. Zn. Such situation continued a quarter
of century until 1997, when substituted PcMn(I) was
Scheme 3. Equilibrium of electronic isomers in PcMn(II)
obtained by electrochemical reduction of [1,8,15,22-tet-
rakis(phenylsulfanyl)phthalocyaninato]manganese(II)
for the first time [13]. It was shown new species had
typical phthalocyanine spectrum. There were no other
confirmations of PcMn(I) existence during the decade
after this first report. But currently situation is changing,
for example, T. Nyokong points that both PcMn(I)
and Pc-. Mn(II) can be obtained depending on the
substituent nature [17]. The same conclusion follows
from the results of the electrochemical investigations of
substituted PcMn for the last 7 years (some of them see
in Table 3).
It is interesting to note that for complexes from
Table 3 in case if the reduction of PcMn(II) leads to
PcMn(I) the oxidation of PcMn(III) with the same
substituents leads to Pc+.Mn(III), and vice versa, the
reduction of PcMn(II) to Pc-. Mn(II) corresponds to the
oxidation of PcMn(III) to PcMn(IV). We can see also
that the potentials of Pc ring oxidation to cation-radical
are much more higher (~1 V) than these one of Mn(III)
oxidation to Mn(IV) (<0.5 V). So we can predict the
main redox sequence knowing only the potential of
PcMn(III)X oxidation.
pyridine solution
Table 2. The relationships of Pc+. Mn(I) × Py (D“570”) and
Pc-. Mn(III) × 2Py (D“480”) bands intensities in spectra 7–12 in
pyridine
Compound
10
0.55 0.25
0 0.46
7
11
9
8
12
0.05 -0.1
0.71 1.04
s*
0.10
0.59
0.05
0.67
D“570”/ D“480”
*The sum of Gammet constants for the substituents in one
benzene ring.
bands of Pc+.Mn(I) × Py are absent in compound 10
spectrum (Table 1).
So, the relationship of anion- and cation-radical bands
intensities in electronic absorption spectra of substituted
PcMn(II) pyridine solutions can serve for the estimation
of the overall electronic influence of all substituents in
one benzene ring of Pc macrocycle.
Electrochemical properties of substituted PcMn 7–12
It is necessary to note that spectroscopic interpretation
of PcMn redox forms, except PcMn(II) and PcMn(III),
is not always correct. In some publications spectra of
compounds described as PcMn(I) has a maximum in
radical region 520–575 nm. Such interpretation causes
some doubts. The position of PcMn(IV) Q band also
differs in different publications.
The authors of many articles which are devoted to
the electrochemistry of substituted PcMn refer to the
controversy of the results obtained [16–26, 37]. The
question is: what is the center of the reduction or
oxidation? Is it the metal atom or the phthalocyanine
ring? For example, in 1972 Clack and Yandle [34]
In our work electrochemical investigations were
carried out for complexes 9–12 (Table 4).
Pyridine and DMF were chosen as the solvents
for the electrochemical study of starting
PcMn(III)X. The measurements were made
under nitrogen.
The obtained cyclic differential voltam-
mograms (CDV) demonstrate three reduction
processes for complexes 9, 10, 12 and four —
for complex 11 (Table 4).
Potentiodynamic curve of compound 9 in
pyridine has a complicated form (Fig. 4), where
waves II and III demonstrate on two poorly
separated peaks. This phenomenon may occur
due to some reasons. According to literature
data it can be chemical reaction following the
electroreduction process, counterion and ligand
bonding, complex aggregation in solution [15,
17, 25]. In our opinion, existence of electronic
isomers in PcMn(II) pyridine solutions also can
Fig. 3. The dependence of the relationships of Pc+. Mn(I) × Py (D“570”) and
Pc-. Mn(III) × 2Py (D“480”) bands intensities in spectra 7–12 in pyridine
on the sum of Gammet constants for the substituents in one benzene ring
cause overlap of some processes in this region
of potentials.
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spectrum of chemically obtained 11c in
pyridine (Fig. 8-2). So, the first stage
(E1/2 = -0.05 V) corresponds to the pair
PcMn(III)/PcMn(II). The presence of
Mn(III) species in spectrum (Fig. 7–2)
was caused by back oxidation reaction
even in nitrogen atmosphere. It was
shown earlier that deep vacuo required
to prevent this reaction for complexes
with electron-donating substituents [13].
Unfortunately, other products were not
stable at UV-vis spectra registration
out of electrochemical cell and their
identification requires further study.
Peak separations of the first and
second reduction processes for studied
complexes are limited by the range 0.50–
0.59 V (Table 4). According to published
data [16, 25] this fact supports the metal-
Fig. 4. CDV of the compound 9 in pyridine, 2.5 × 10-4 M, 0.1 TBAP. Scan rate
based assignment of the second reduction
20 mV/s vs. HgCl2
leading to PcMn(I) formation. Reliable
determination of these and others products requires
further spectroelectrochemical studies.
Process I is reversible, relationship ic1/2/ia1/2 is about 1
and the difference of the wave potentials at the forward
and reverse scan is less 100 mV (Fig. 4).
Compound 12 in DMF demonstrates three reduction
waves. Increase of 12 concentration (curves 1, 2, and 3
Fig. 5a) slightly changes the limiting current of the
process I, while the current of the reverse process I′
increased proportionally to 12 concentration. Scanning
to the anodic range from -0.5 to 0.0 V and back without
electrode clearance showed the intensities of waves I
and I′ been equal (Fig. 5b). It means that process I′ is
irreversible 12 electrooxidation. The processes II and III
are reversible.
TheprocessesI–IVregisteredatthe11potentiodynamic
curve are reversible. Reversibility was illustrated by the
similarity in the forward and reverse CDV scans (Fig. 6)
with ic1/2/ ia1/2 relationship equal 1 and independent on the
potential scan rate.
EXPERIMENTAL
Materials
4-nitrophthalonitrile, tetrachlorophthalonitrile, 1-buta-
nethiol, 2-methyl-2-propanethiol, 1-decanethiol, triethy-
lamine were obtained from Sigma-Aldrich, 2,2,3,3,-
4,4,5,5,6,6,7,7-dodecafluoroheptan-1-ol was obtained
from Fisher Scientific and used as received. The synthesis
andcharacterizationof3-bromo-5-tert-butylphthalonitrile
has been reported before [38]. Substituted PcMn (7–12)
have been prepared by heating anhydrous manganese
acetate with the corresponding phthalodinitrile in a sealed
tube. The time and the temperature of the reactions varied
for different compounds within 1 h–1 h 40 min and 175–
250 °C. All organic solvents used for the synthesis were
of analytical grade and used as received without further
purification.
The UV-vis spectrum (Fig. 7-2) of the product which
has been obtained at the first stage of 11a electroreduction
in pyridine (Fig. 6, peak I) showed its identity with the
Table 4. Voltammetric data for 9–12 redox couples on glassy carbon electrode in pyridine,
0.1 M TBAP
Complex Concentration, M
Half-wave potentials -E1/2, V
Process I
Process II
Process III Process IV
9
2.5∙10–4
1.3∙10–3
1.6∙10–4
3.3∙10–4
0.07
not measured
0.05
0.66, 0.82
0.42
1.07, 1.32
1.00
—
1.54
1.50
—
10
11
12
0.55
1.20
0.09
0.66, 0.75
1.20
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as internal reference. The compositions of
reactions mixtures and the purity of isolated
compounds were monitored byTLC on Silufol
UV-254 plates. The electronic absorption
spectra (UV-vis) were recorded by HP 8453
spectrometer. Voltammetry was carried out in
three-electrode cell in nitrogen atmosphere.
Glassy carbon electrode SU – 2000 prepared
by method [39] was used as a working
electrode. A standard calomel electrode was
used as a reference. Coulometric potentials
were generated using polarograph PU-1 and
two-coordinate recorder PDS-021. As base
electrolyte TBAP (tetrabuthylammonium
perchlorate) was used.
Syntheses
Preparation of 3-(tert-butylsulfanyl)-
phthalonitrile (1). The 3-nitrophthalonitrile
(3.46 g, 20.0 mmol) was dissolved in DMF
(30 mL), and 2-methyl-2-propanethiol
(2.50 mL, 22.2 mmol) was added. After
stirring for 5 min triethylamine (3.10 mL,
22.2 mmol) was added in portions during
15 min with efficient stirring. The reaction
mixture was stirred at 50 °C for 1 h, cooled to
room temperature, poured into ice-water, the
formed precipitate was filtered off, washed
with water, dried and recrystallized twice from
hexane. Yield 3.14 g (72.7%), mp 64–65 °C.
Anal. calcd. for C12H12N2S: C, 66.67; H, 5.56;
N, 12.96; S, 14.81%. Found: C, 67.10; H,
5.52; N, 12.94; S, 14.87. IR (KBr): lmax, cm-1
2236 (CN). MS: m/z 216 [M]+.
Fig. 5. CDV of the compound 12 in DMF, 0.1 TBAP: 1 – 1.4 × 10-4 M, 2
– 2.7 × 10-4 M, 3 – 3.9 × 10-4 M (a), without electrode clearance (b). Scan
rate 20 mV/s vs. HgCl2
Preparation of 5-tert-butyl-3-(tert-butyl-
sulfanyl)phthalonitrile (2). The phthalonitrile
2 was prepared by method [28], but insted
of thiophenol 2-methyl-2-propanethiol was
used. The 3-bromo-5-tert-butylphthalonitrile
(2.63 g, 10.0 mmol) was dissolved in DMF
(20 mL), and 2-methyl-2-propanethiol (1.30
mL, 11.5 mmol) was added. After stirring for
5 min triethylamine (1.60 mL, 11.5 mmol)
was added in portions during 15 min with
efficient stirring. The reaction mixture was
stirred at 20 °C for 0.5 h. The mixture was
Fig. 6. CDV of the compound 11 in pyridine, 1.6 × 10-3 M, 0.1 TBAP.
Scan rate 20 mV/s vs. HgCl2
poured into ice-water, the formed precipitate was filtered
off, washed with water, dried, dissolved in benzene,
purified by column chromatography on silica gel using
benzene as eluent and recrystallized from hexane. Yield
1.70 g (62.5%), mp 94–95 °C. Anal. calcd. for C16H20N2S:
C, 70.59; H, 7.35; N, 10.29; S, 11.76%. Found: C, 70.61;
H, 7.42; N, 10.25; S, 11.68. IR (KBr): lmax, cm-1 2235
(CN). MS: m/z 272 [M]+.
Equipment
Elemental analysis was performed on a Hewlett-
Packard HP-185B C,H,N analyzer. IR-spectra were
registered on a FMS-1201 FT spectrometer in KBr
pellets. The mass spectra (electron impact, 70 eV)
were obtained on an MKh-1321 instrument. H and 19F
1
NMR spectra were recorded on a Varian INOVA 500
MHz spectrometer using DMSO-d6 as solvent and TMS
Preparation of 4-(butylsulfanyl)phthalonitrile (3).
The phthalonitrile 3 was prepared by method [28], but
Copyright © 2012 World Scientific Publishing Company
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COORDINATION AND ELECTROCHEMISTRY OF NEW SUBSTITUTED MANGANESE PHTHALOCYANINES
955
Preparation of 3,6-dichloro-4,5-
bis(decylsulfanyl)phthalonitrile (4).
The phthalonitrile 4 was synthesised
as previously reported [40]. Isolated
yield 87% of yellow oil that very slowly
changes to amorphous solid.
Preparation of 4,5-bis(phenylsulf-
anyl)phthalonitrile (5). The phthalon-
itrile 5 was synthesised from 4-bromo-
5-nitrophthalonitrile
by
modified
method previously reported in the
literature [41]. The 4-bromo-5-nitro-
phthalonitrile (1.26 g, 5.0 mmol)
was dissolved in DMF (20 mL), and
thiophenol (1.10 mL, 10.8 mmol)
was added. After stirring for 5 min
triethylamine (1.50 mL, 10.8 mmol) was
added in portions during 15 min with
efficient stirring. The reaction mixture
was stirred at 80 °C for 3 h, cooled to
room temperature, poured into ice-
water, and the formed precipitate was
filtered off, washed several times with
water and recrystallized from ethanol.
Yield 1.20 g (69.8%), mp 146–148 °C.
Anal. calcd. for C20H12N2S2: C, 69.74;
H, 3.51; N, 8.13; S, 18.62%. Found:
C, 70.09; H, 3.62; N, 8.00; S, 18.54.
IR (KBr): lmax, cm-1 2232 (CN). MS:
Fig. 7. UV-vis spectrum of the 11a (1) and the product of the first electroreduction
in pyridine, 0.1 TBAP (2), l = 1 cm
1
m/z 344 [M]+. H NMR: d, ppm 7.72
(s, 2H, 3,6-H), 7.51 (d, 4H, ortho-H
of SPh), 7.43–738 (m, 6H, meta and
para-H of SPh).
Preparation of 3-(2,2,3,3,4,4,5,5,-
6,6,7,7-dodecafluoroheptyloxy)
phthalonitrile (6). The mixture of
3-nitrophthalonitrile (1.00 g, 5.8
mmol), 2,2,3,3,4,4,5,5,6,6,7,7-dodeca-
fluoroheptan-1-ol (1.93 g, 5.8 mmol),
anhydrous K2CO3 (0.80 g, 5.8 mmol)
and DMF (30 mL) was stirred under
nitrogen at 120 °C for 2 h. Then the
mixture was poured into ice-water, the
Fig. 8. UV-vis spectrum of 11a (1) transformation into 11c (2) in pyridine in the
presence of thriethylamine, l = 1 cm
precipitate was filtered off, washed with water, dried and
then recrystallized twice from hexane/benzene (1:1).
Yield 2.19 g (82.6%), mp 103–105 °C. Anal. calcd. for
C15H6F12N2O: C, 39.32; H, 1.32; F, 49.76; N, 6.11%.
instead of 2-methyl-2-propanethiol 1-butanethiol was
used. The 4-nitrophthalonitrile (1.73 g, 10.0 mmol)
was dissolved in DMF (15 mL), and 1-butanethiol
(1.80 mL, 16.8 mmol) was added. After stirring for
5 min triethylamine (2.20 mL, 15.8 mmol) was added in
portions during 15 min with efficient stirring. Reaction
mixture was stirred at 20 °C for 0.5 h. The mixture was
poured into ice-water, the formed precipitate was filtered
off, washed with water, dried and recrystallized from
hexane. Yield 1.93 g (89.4%), mp 60–61 °C. Anal. calcd.
for C12H12N2S: C, 66.67; H, 5.56; N, 12.96; S, 14.81%.
Found: C, 66.74; H, 5.60; N, 13.03; S, 14.75. IR (KBr):
Found: C, 39. 21; H, 1.34; F, 50.01; N, 6.13. IR (KBr):
1
l
max, cm-1 2234 (CN). MS: m/z 458 [M]+. H NMR: d,
ppm 7.94 (dd, 1H, 5-H), 7.83 (d, 1H, 6-H), 7.80 (d, 1H,
4-H), 7.18 (tt, 1H, CF2H; JHF = 51.1 Hz, a-F; JHF = 5.3
Hz, β-F), 5.20 (t, 2H, CH2, JHF = 13.4 Hz). 19F NMR: d,
ppm -118.7 (m, 2F), -122.15 (m, 2F), -122.58 (m, 2F),
-123.09 (m, 2F), -129.0 (m, 2F), -138.43 (m, 2F).
SynthesisofsubstitutedPcMn7–12.SubstitutedPcMn
7–12havebeenpreparedbyheatinganhydrousmanganese
acetate with the corresponding phthalodinitriles 1–6 and
l
max, cm-1 2234 (CN). MS: m/z 216 [M]+.
Copyright © 2012 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2012; 16: 955–957

956
O. DOLOTOVA ET AL.
ammonium molybdate as a catalyst in a sealed tube [28].
Reaction time and temperature are indicated for each
complex. Cooled reactive mixture has been dissolved
and purified using column chromatography with neutral
alumina (silica gel for 10) as column material. Eluents
are indicated for each compound.
Synthesis of chloro[1,8,15,22-tetrakis(tert-butyl-
sulfanyl)phthalocyaninato]manganese(III) (7a). The
mixture of (1) (0.20 g, 0.9 mmol) and manganese(II)
acetate (0.078 g, 0.3 mmol), 0.5 h at 175 °C, 1 h at
195 °C. Benzene, washing out yellow colored impurity
and blue colored metal-free Pc, chloroform. Yield 0.073
g (30%). Anal. calcd. for C48H48N8S4MnCl: C, 60.33; H,
5.06; N, 11.72; S, 13.42%. Found: C, 60.01; H, 5.22; N,
11.40; S, 13.17. UV-vis (CHCl3): lmax, nm (log e) 359
(4.59), 528 (4.08), 745 (4.85).
Synthesis of chloro[3,10,17,24-tetra-tert-butyl-1,8,-
15,22-tetrakis(tert-butylsulfanyl)phthalocyaninato]-
manganese(III) (8a). The mixture of (2) (0.15 g, 0.55
mmol) and manganese(II) acetate (0.05 g, 0.20 mmol),
1 h at 180 °C, 15 min at 210 °C, 15 min at 200 °C.
Benzene, washing out yellow colored organic impurities
and blue colored metal-free Pc, chloroform, collecting
red-brown main product. Yield 0.08 g (48%). Anal.
calcd. for C64H80N8S4MnCl: C, 65.14; H, 6.83; N, 9.49;
S, 10.86; Cl, 3.00; Mn, 4.65%. Found: C, 65.56; H, 6.85;
N, 9.33; S, 10.30; Cl, 3.20; Mn, 4.35. UV-vis (CHCl3):
(11a). The mixture of (5) (0.115 g, 0.33 mmol) and
manganese(II) acetate (0.03 g, 0.11 mmol), 40 min at
200 °C, 30 min at 250 °C. Benzene, washing out yellow
colored organic impurities, chloroform, collecting cherry
colored main product.Yield 0.083 g (67.5%). Anal. calcd.
for C80H48N8S8MnCl: C, 65.44; H, 3.29; N, 7.63; Cl, 2.41;
S, 17.46; Mn 3.74%. Found: C, 65.64; H, 3.32; N, 6.92;
Cl, 1.95; S, 17.67; Mn, 4.01. UV-vis (CCl4): lmax, nm (log
e) 330 (4.63), 464 (4.43), 524 (4.34), 773 (4.87).
Synthesis of chloro[1,8,15,22-tetrakis(2,2,3,3,4,4,5,-
5,6,6,7,7-dodecafluoroheptyloxyl)phthalocyaninato]-
manganese(III) (12a). The mixture of (6) (0.30 g, 0.65
mmol) and manganese(II) acetate (0.048 g, 0.20 mmol),
30 min at 200 °C, 1 h at 240 °C.Acetone-benzene mixture,
benzene, washing out yellow colored organic impurities,
acetone, collecting product as mixture of two forms —
a and b. Dried product was dissolved in chloroform,
resulting in 12a. Yield 0.163 g (52%). Anal. calcd. for
C60H24N8O4F48MnCl: C, 37.47; H, 1.25; N, 5.82%.
Found: C, 37.77; H, 1.51; N, 5.54. UV-vis (CCl4): lmax
nm (log e) 355 (4.45), 515 (4.00), 737 (4.70).
,
CONCLUSION
New substituted manganese phthalocyanines
7–12 have been synthesized from the corresponding
phthalonitriles 1–6 with rather good yields (up to 67%)
and high purity. Main coordination and valence forms:
a — PcMn(III)X, b — [LPcMn(III)]2O and c — PcMn(II)
were observed for all complexes. Different ways were
used for each complex b formation. Rather elusive were
complexes 7b and 8b. The equilibrium of three electronic
isomers: Pc+. Mn(I) × L, PcMn(II) × nL and Pc-. Mn(III) ×
2L has been observed in the solutions of all PcMn(II)
in the presence of organic base L. The relationship of
anion- and cation-radical bands intensities in electronic
absorption spectra of such solutions can serve for an
estimation of the substituent’s electronic properties.
The electronic absorption spectra of each coordination
form in solution for all new compounds were registered.
The potentials of electrochemical transformations for
complexes 9–12 have been obtained.
l
max, nm (log e) 367 (4.63), 535 (4.15), 751 (4.80).
Synthesisofchloro[2,9,16,23-tetrakis(butylsulfanyl)-
phthalocyaninato]manganese(III) (9a). The mixture of
(3) (0.34 g, 1.57 mmol) and manganese(II) acetate (0.13
g, 0.53 mmol), 40 min at 170 °C, 40 min at 200 °C, 0.5
h at 210 °C. Benzene, washing out organic impurities,
chloroform, collecting red-brown main product. Yield
0.165 g (43.9%). Anal. calcd. for C48H48N8S4MnCl: C,
60.33; H, 5.06; N, 11.72; S, 13.42; Cl 3.71; Mn, 5.74%.
Found: C, 60.69; H, 5.33; N, 11.30; S, 12.98; Cl 3.51;
Mn, 5.64. UV-vis (CHCl3): lmax, nm (log e) 337 (4.59),
449 (4.41), 525 (4.28), 750 (4.85).
Synthesis of chloro[1,4,8,11,15,18,22,25-octachloro-
2,3,9,10,16,17,23,24-octakis(decylsulfanyl)phthalo-
cyaninato]manganese(III) (10a). The mixture of (4)
(0.54 g, 1.0 mmol) and manganese(II) acetate (0.08 g,
0.33 mmol), 1 h at 200 °C, 40 min at 250 °C. Cooled
reactive mixture firstly has been washed with isopropanol
(100 mL), then has been dissolved in CCl4 and purified
using column chromatography over silica gel (100/160)
with benzene, washing out yellow colored organic
impurities and some quantity of 10c and then with CCl4,
collecting brown colored main product 10a. Yield 0.09
g (16%). Anal. calcd. for C112H168N8S8Cl9Mn: C, 59.59;
H, 7.50; N, 4.96%. Found: C, 60.41; H, 8.43; N, 4.32.
UV-vis (CCl4): lmax, nm (log e) 300 (4.28), 522 (3.71),
787 (4.18). Column chromatography performed with
acetone as eluent results in 10a and 10b mixture isolation.
Synthesis of chloro[2,3,9,10,16,17,23,24-octakis-
(phenylsulfanyl)phthalocyaninato]manganese(III)
Acknowledgements
We thank Moscow Government for financial
support and also we thank A.M. Perepukhov, post-
graduate student of the Moscow Institute of Physics
and Technology, Department of Molecular Physics, for
performing NMR.
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