Reduction of (chloro)-μ-nitrido-bis[(tetra-tert-butyl-phthalocyaninato)iron(IV)] with organic N-bases

Article abstract of DOI:10.1142/S1088424616500474

The interaction of (chloro)-μ-nitrido-bis[(tetra-Tert-butyl-phthalocyaninato)iron(IV)] Cl(FePc)₂N with organic N-bases L as electron-donors (L diethylamine, imidazole, 1-methylimidazole, 2-methylimidazole) with the formation of one-electron reduced species (L)PcFe^III-N?Fe^IVPc(L) was investigated in benzene at 298 K by UV-visible spectroscopy. The reaction was established to be stepwise process including fast reversible axial binding of two substrate molecules onto iron cations followed by slow one-electron metal-centered reduction. The results of IR, ESI-MS and EPR study support the formation of final product with Fe^?3-N?Fe^?4 unit and two substrate molecules in the first coordination sphere. The reaction kinetics was studied, the pre-equilibrium constants K_eq and rate constants κ were obtained. The K_eq and κ values were found to be linearly correlated with basicity of substrates pκa. The possibility of the transition Fe^4?→Fe^3??is promoted by electron-donor properties of substrate combined with the presence of both electron-rich macrocycle and φ-backdonation Fe →NPc.

Full text of DOI:10.1142/S1088424616500474

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2016; 20: 1–8
DOI: 10.1142/S1088424616500474
Published at http://www.worldscinet.com/jpp/
Reduction of (chloro)-m-nitrido-bis[(tetra-tert-butyl-
phthalocyaninato)iron(IV)] with organic N-bases
a
a
a
Svetlana V. Zaitseva , Sergei A. Zdanovich , ElenaY.Tyulyaeva* ,
b
a,b
Ekaterina S. Grishina and Oskar I. Koifman
a
G. A. Krestov Institute of Solution Chemistry of the Russian Academy of Science, Akademicheskaya St. 1,
Ivanovo 153045, Russian Federation
State University of Chemistry and Technology, Sheremetevskiyi Str. 7, Ivanovo 153000, Russian Federation
b
Received 11 November 2015
Accepted 3 February 2016
ABSTRACT: The interaction of (chloro)-m-nitrido-bis[(tetra-tert-butyl-phthalocyaninato)iron(IV)]
Cl(FePc) N with organic N-bases L as electron–donors (L = diethylamine, imidazole, 1-methylimidazole,
2
III
IV
2
-methylimidazole) with the formation of one-electron reduced species (L)PcFe –N=Fe Pc(L) was
investigated in benzene at 298 K by UV-visible spectroscopy. The reaction was established to be stepwise
process including fast reversible axial binding of two substrate molecules onto iron cations followed
by slow one-electron metal-centered reduction. The results of IR, ESI-MS and EPR study support the
+3
+4
formation of final product with Fe –N=Fe unit and two substrate molecules in the first coordination
sphere. The reaction kinetics was studied, the pre-equilibrium constants K and rate constants k were
eq
obtained. The K and k values were found to be linearly correlated with basicity of substrates pК . The
eq
a
4
+
3+
possibility of the transition Fe → Fe is promoted by electron–donor properties of substrate combined
with the presence of both electron-rich macrocycle and p-backdonation Fe ← NPc.
KEYWORDS: (chloro)-m-nitrido-bis[(tetra-tert-butyl-phthalocyaninato)iron(IV)], N-bases, axial
coordination, reduction, kinetics.
the complicated transformations in living organisms has
been resulted to numerous studies.
INTRODUCTION
The creation of biomimetic systems for biological
and technical processes is one of the most important
directions in the development of modern chemistry. The
study of influence of the structure and composition of
the synthetic systems on their catalytic properties and
possible transformations during a chemical reaction
remains relevant within the framework of biomimetic
approach. According to the literature reports, tetrapyrrole
complexes of transition metals can be successfully
used as active components of such systems [1–7].
These compounds play an important role in biological
processes. Many enzymes of heme and non-heme types
contain iron cations in various oxidation states as a bio-
coordination center. The ability of enzymes to encourage
Until recently the dimeric complexes had been
considered catalytically inert compared to monomeric
ones, and they had been ignored as catalysts. At present
μ-oxo dimeric complexes of iron phthalocyanines (Pc)
were shown to mediate an efficient oxidation of aromatic
compounds and alcohols. Both binuclear and mononuclear
iron complexes activate some oxidant (H O , organic
2
2
peroxides, hypervalent iodine compounds, etc.) to form
high valent oxo species with remarkable catalytic properties
[2–9]. However, despite of catalytic activity of oxo-bridged
structures, their study is hampered due to their readily
transformations during chemical reactions. m-Nitrido-
bridged diiron tetrapyrrole macrocyclic complexes are
turned out to be more stable analogs of an active center of
the natural enzymes [10–13].
*
Correspondence to: Elena Yu. Tyulyaeva, email: teu@isc-ras.
The most investigations devoted to tetrapyrrole iron
complexes deal with study of their structure and spectral
ru, tel: +7 4932-336990, fax: +7 4932-336246
Copyright © 2016 World Scientific Publishing Company

2
S. V. ZAITSEVA ET AL.
t
(
FePc Bu ) N, that was synthesize and isolate
4 2
according to the literature report [21]. Then solution of
t
(
FePc Bu ) N (0.05 g) in CH Cl (10 mL) was stored
4 2 2 2
at room temperature under atmospheric oxygen in the
dark for a week. The reaction completion was detected
by termination of changes of Q-band in the UV-visible
spectrum and by disappearance of the signals in the EPR
spectrum of reaction mixture. Evaporation of solvent
afforded pure Cl(FePc) N as a dark blue powder. UV-vis
2
(
(
C H ): l , nm (log e) 680 (4.21), 645 (4.90), 540
6
6
max
1
4.63), 343 (4.92). H NMR (500 MHz, C D , Me Si):
6
6
4
d, ppm 7.35–7.32 (8H, m, Ph), 7.24–7.20 (16H, m, Ph),
2
.15–2.09 (72H, m, t-Bu). ESI-MS: m/z 1599.7 (calcd. for
Chart 1. Structure of (chloro)-μ-nitrido-bis[(tetra-tert-butyl-
+
[
(FePc) N] 1599.7).
2
phthalocyaninato)iron(IV)] Cl(FePc) N
2
Spectroscopy
properties. However it is necessary to point out the
coordinating and redox properties of such compounds
in order to explain the mechanism of catalytical and
enzymatic processes with the tetrapyrrole iron complexes
participation and to create the biomimetic systems based
on these compounds.
The UV-visible and mass-spectra were measured on
Cary 50 UV-visible spectrophotometers at T = 295 K,
electrospray ionization mass-spectrometry (ESI-MS)
Bruker microTOF, respectively. NMR experiment was
performedonaBrukerAvanceIII-500NMRspectrometer.
Electron paramagnetic resonance (EPR) spectra were
obtained on a Bruker EMX EPR spectrometer.
The key to our strategy is to attach a potential ligand
ontometalcenter/centersofstablebinuclearcomplexonthe
phthalocyanine platform and follow changes in physico-
chemical and redox properties of final molecules. For this
purpose the reactions of (chloro)-m-nitrido-bis[(tetra-tert-
Methods
The kinetics of the reactions was studied spectrophoto-
metrically [22, 23]. Solutions were thermostated in a cell
installed in the spectrophotometer and heated with a
U4 standard water thermostat. The error of temperature
determination was ± 0.1 K.
butyl-phthalocyaninato)iron(IV)] Cl(FePc) N (Chart 1)
2
with organic substrates (N-bases) as electron-donors
(
diethylamine Et N, imidazole Im, 1-methylimidazole
2
1-MeIm, 2-methylimidazole 2-MeIm) were investigated
in benzene at 298 K by UV-visible technique. UV-visible,
The rate constants (k , k) were determined using
obs
1
H NMR, ESI-MS techniques and EPR study were used
dependences ln[(A – A )/(A – A )] vs. t (here are the
0
∞
t
∞
conveniently to confirm the composition of intermediates
and final products of the reaction.
absorbances of solutions at working wavelength at
time (t) equal to 0, current t, and the time of reaction
completion) and Equation 1.
The involved organic bases were used taking into
account the remarkable antibacterial, anti-tumour, anti-
ischemic and anti-allergic properties of medications
having the substrates in the structure [14, 15], and
an ability of concerned organic bases to be readily
coordinated by transition metal ions [7–9, 16–20]. The
presence of the axially coordinated base as part of the
coordination sphere of the macrocyclic complexes can
significantly affect the biological and catalytic activity
of both substrates and the molecular complex as a
whole.
.
kobs = (l/ τ) ln[(A − A )/(A − A )]
(1)
0
∞
τ
∞
The reaction of (Cl)(FePc) N with substrates was
2
studiedbyspectrophotometricaltitration.Theequilibrium
constants Keq of the reactions were calculated using
Equation 2, derived in accordance with the laws of mass
action and the Bouguer–Lambert–Beer for a mixture of
colored start compounds and products [24], where A , A ,
0
∞
and A are the absorbances of solutions of the starting
m
compound, reaction products, and their equilibrium
mixture at the operating wavelength.
EXPERIMENTAL
Am − Ao
A∞ − A
o
1
.
Materials
Keq
=
2
(2)
A∞ − A
m

A − A 
All N-bases were obtained from Sigma–Aldrich and used
without purification unless indicated. The solvents were
dried and distilled according to the published procedures.
o
L
o
MII
m
o
C −C
A∞ − Ao




A∞ − A
o
(
Cloro)-m-nitrido-bis[(tetra-tert-butyl-phthalocy-
K , k, k values and standard deviations were found by
eq obs
least squares using Microsoft Excel software.
aninato)iron(IV)], Cl(FePc) N was prepared from
2
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 2–8

REDUCTION OF (CHLORO)-m-NITRIDO-BIS[(TETRA-tert-BUTYL-PHTHALOCYANINATO)IRON(IV)]
3
Kinetics of the reaction was studied at 298 K
under conditions of pseudo-first order with respect to
RESULTS AND DISCUSSION
The UV-vis spectra are known to be the most common
means to examine the interaction between macrocyclic
complex of metals and various substrates. The Q-band
in the UV-vis spectra of metallophthalocyanines (MPcs)
significantly depends on the substituents in macrocycle
and the metal nature in contrast to B-band at about
Cl(FePc) N. The values of k were obtained from the
2
obs
single-exponential fitting of the absorbance – time curves
Fig. 2), optimized by means of least squares fitting
(
program and listed in the Table 1. Figure 3 shows kobs
for the reactions as a function of L concentration. The
concerned reaction was shown to be of second order with
respect to substrate concentration (Fig. 3, tan a ≈ 2). The
corresponding rate constants k, which are independent on
C , are also presented in the Table 1. Taking into account
above spectral and calculated data the kinetic equation
for the reaction under investigation should be written as:
3
40 nm, whose position does not differ noticeably among
these complexes. Furthermore the change of the position
or intensity Q-band indicating a strong interaction
between the electronic states of the chromophore and that
of substrate molecule, has been shown also to be very
sensitive to the presence of various compounds. That’s
why herein we rely on the spectrophotometric method in
order to study considered reactions.
L
−
dCCl(FePc)2 N
dτ
2
L
=
k ×C
×C
Cl(FePc) N
2
The UV-vis spectra of Cl(FePc) N in benzene exhibits
(3)
2
the Q-band at 645 nm (Fig. 1, curve 1). The interaction of
Cl(FePc) N with N-bases in question took place during
MPcs including iron derivatives has been known to
bind non-covalently the axial ligands such as N-bases
[26–31]. We assumed that in the case of diiron dimeric
2
time and was accompanied by the evolution of UV-vis
spectra. Taking into account the similarity of spectral
measurements during the reactions, Figure 1 provides
speciesCl(FePc)
also takes place. Indeed immediately after addition of the
substrate to benzene solution of Cl(FePc) N the blue-shift
Ntheaxialbindingofsubstratesinvolved
2
those upon the interaction of Cl(FePc) N with imidazole.
2
The gradual appreciable increase of narrow Q-band
blue-shifted by 1–2 nm was observed. The decrease of
the intensity of broad bands at 540 and 680 nm were
also occurred. Well-defined isosbestic points indicated
that during the course of the experiment, additional
intermediates do not accumulate in spectroscopically
significant concentrations. The final spectrum of the
reaction product was similar to that of m-nitrido-bridged
2
ofQ-bandby2nmandinsignificantincreaseofitsintensity
were observed (Fig. 1, curves 1 and 2) suggesting very
rapid reversible formation of donor–acceptor complex
Cl(FePc)
InordertoprovetheaxialbindingabilityofCl(FePc)
and determine the number of coordinated ligands, the
reactions of Cl(FePc) N with all the substrates concerned
N with N-bases [27, 30, 32–37].
2
N
2
2
+
3
+4
diiron phthalocyanine with Fe –N=Fe unit [25].
Thus the spectroscopic data suggested that addition
of the substrates in question to the benzene solution
were investigated by spectrophotometry using the molar
ratio method [36]. The spectrum transformations on
addition of 1-MeIm (as the example) in benzene solution
of Cl(FePc) N resulted in the one-electron reduction
of Cl(FePc)
2
N and curve of the spectrophotometric
2
reaction with metal-reduced species formation.
titration at lmax = 645 nm are presented on the Fig. 4.
Fig. 1. Time-evolution UV-vis spectral changes of Cl(FePc) N in benzene in the presence of imidazole at 298 K. C
=
2
Cl(FePc) N
2
. .
-6
-4
4
.13 10 M, C = 5.77 10 M. t, s: 0 (1), 45 (2)
Im
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 3–8

4
S. V. ZAITSEVA ET AL.
Fig. 3. Dependence of observed rate constant (logk ) on
obs
substrate concentration (logC ) for the reduction of Cl(FePc) N
L
2
in the presence of substrates L at 298 K. L = Im (1), 1-MeIm (2),
2
Et N (3), 2-MeIm (4). R are equal 0.98 ÷ 0.99
2
Fig. 2. Absorbance (ln(C /C ) – time (t)) dependence for the
0
t
reaction of Cl(FePc) N with imidazole in benzene at 298 K. C ,
2
Im
-
3
-3
-4
M: 9.07 × 10 (1), 5.85 × 10 (2), 5.77 × 10 (3)
Table 1. Observed rate constants (k ) and rate constants (k) of
obs
the reduction of Cl(FePc) N in the presence of N-bases (L) in
2
benzene at 298 K
6
3
4
-1
-3 -1
C
× 10 , M C × 10 , M kobs × 10 , s
k, M s
Cl(FePc) N
L
2
L = Et N
2
4
.82
0.8
0.86
3.73
7.02
46.77
20.18
1
2
.57
.53
L = 1-MeIm
.52
Fig. 4. UV-vis spectra of Cl(FePc)
-methylimidazole in benzene at 298 K and curves of the
spectrophotometric titration at l = 645 nm; C1-MeIm = 0 ÷ 5.1 ×
2
N on addition of
1
4
0.59
1.1
6.9
max
–
3
1
2
4
.80
.36
.75
10 M
10.1
33.1
Im
4
.13
0.58
1.5
42.6
16.98
6.54
5
9
.85
.07
127.4
2
6
-MeIm
.89
0.64
5.2
13.9
50.3
1
2
.30
.61
Am − Ao
− Am
Fig. 5. Dependence of indicator ratio
(
log
A
)
on N-bases
∞
concentration (log C ) for the reaction between Cl(FePc) N and
L
2
Figure 5 shows the plots of log[(A –A )/(A –A )]
m
0
∞
m
N-bases (L) in benzene at 298 K. L = 2-MeIm (1), Im (2), 1-MeIm
as a function of the logC for all the reactions studied.
2
L
(3), Et N (4). R = 0.99
2
The slope of the straight lines on Fig. 5 is equal to 2 that
designate the coordination of two substrate molecules on
the metal centers of initial compound. The corresponding
equilibrium constants Keq of the studied reactions are
listed in the Table 2. The values of equilibrium constants
are demonstrated to be linearly correlated with basicity
-
1
n , located at frequency of 938 cm , is sensitive
as
to the presence of axial bound ligands. Thus, when
Cl(FePc) N interacts with diethylamine, imidazole,
1-methylimidazole, the N-bridge marker bands are red
shifted and observed at 851, 896 и 921 cm , respectively
2
-
1
of substrates pК [37] (Fig. 6).
a
In the IR spectra of Cl(FePc) N the band attributed
to asymmetric stretching vibrations of m-nitrido-bridge
(Fig. 7). In the region of macrocycle vibrational modes
(350–1500 cm ) of adducts the spectra are similar with
2
-
1
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 4–8

REDUCTION OF (CHLORO)-m-NITRIDO-BIS[(TETRA-tert-BUTYL-PHTHALOCYANINATO)IRON(IV)]
5
Fig. 6. Dependence of equilibrium constants (K ) on N-bases
eq
basicity (pК ) for the reaction between Cl(FePc) N and N-bases
a
2
in benzene at 298 K
Table 2. N-bases basicity (pК ) in water and
a
equilibrium constants (K) of the reaction
between Cl(FePc) N and N-bases (L) in
2
benzene at 298 K
Complex
pКa
lgK
(
(
(
(
Et N) (FePc) N
10.67
7.33
6.65
5.89
4.31
3.93
3.76
3.03
2
2
2
1-MeIm) (FePc) N
2
2
Im) (FePc) N
2
2
2-MeIm) (FePc) N
2
2
that of the initial compound. However, most of the
bands are shifted, indicating the interaction between
Fig. 7. IR spectra (in benzene solution) of Cl(FePc)
(
(
coordinated substrates; (*) asymmetric stretching vibrations of
μ-nitrido-bridge
N before
a) and after reaction with diethylamine (b), imidazole
c), 1-methylimidazole (d); (•) characteristic frequencies for the
2
Cl(FePc) N and substrates. Moreover these spectra
2
are complicated due to the presence of new bands
attributed to ligated substrates. Our IR spectra results
are quite similar to those observed previously for axial
ligation of m-oxo-bridged structures m-O(FePc) [38]
2
2
-
and m-O(FeTPTAP) (TPTAP — tetra-phenyl-tetra-
2
C[(L)
+
−
(FePc) N] Cl
2
2
azaporphyrin dianion) [39].
Keq
=
(6)
2
L
(CCl(FePc)2N × C
According to spectroscopic and reactivity data obtained
the one-electron metal-centered reduction of Cl(FePc) N
2
and k is the constant of the rate-determining step of the
process (5) with corresponding kinetic Equation 7:
on N-bases addition is two-step process involving fast
reversible binding of substrate molecules to iron followed
by slow generation of one-electron reduced species (L)
2
III
IV
−dC[(L)2 (FePc)2
dτ
+
−
PcFe –N=Fe Pc(L) (Equations 4, 5):
N] Cl
(
7)
=
k2 ×C[(L)
+
−
(FePc) N] Cl
2
2
Keq k1
IV
IV
+
−

 →
Cl(Fe Pc) N + 2L
[(L) (Fe Pc) N] Cl
2
←  
2
2
The definitive rate equation (8) may be founded by
(4)
derivation of C[
+
-
from Equation 6:
(L) (FePc) N] Cl
2
2
IV
+
−
[
(L) (Fe Pc) N] Cl
2
2
−dC[(L)
+
−
(FePc)2 N] Cl
2
L
2
k
III
IV
(8)
2
= k × K ×C
× C


−
→ (L)PcFe − N = Fe Pc(L)
k2 ꢀ k1 (5)
2
eq
Cl(FePc)2 N]
−
Cl
dτ
Here K is the pre-equilibrium constant characterizing
It is obvious that Equations 3 and 8 are similar and k =
k × К . Moreover, the rate of metal-centered reduction is
eq
IV
+
-
the stability of intermediate [(L) (Fe Pc) N] Cl
2
2
2
eq
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 5–8

6
S. V. ZAITSEVA ET AL.
important to confirm that the resulting complex actually
have biscoordination of the ligand. The composition of
final complex was supported by ESI-MS spectrometry
after reaction between Cl(FePc) N and Im as an example
2
(
[
1
Fig. 9). In addition to the prominent signal of starting
+
(FePc) N] at m/z = 1599.7268, a new signal at m/z =
2
735.7568 was detected due to (Im) (FePc) N. The high
2 2
basicity index pК of the substrates in question (Table 1)
a
and the spectrophotometric titration data (Fig. 2) coupled
with mass-spectrometry data allowed to established
exactly two substrate molecules in the product of the
reactions (9). The presence of another additional signal
in ESI-MS spectrum at m/z = 1667.7169 assigned to
Fig. 8. Dependence of reduction rate constant (k) of [Cl(FePc) N
2
2
on N-bases basicity (pК ) at 298 K. R = 0.98
a
(
Im)(FePc) N (Fig. 9) may assume the fragmentation
2
+
of the intermediat [(Im) (FePc) N] and/or during mass-
2
2
found to be dependent on the basicity of the axial ligand L
spectral experiment.
The formation of the product with Fe –N=Fe unit
were supported by the EPR spectral data. In contrast to
the EPR spectrum of initial diamagnetic Fe –N=Fe
species that of the isolated solid adduct with imidazole
exhibited a signal due to the presence of Fe –N=Fe
species in the material (Fig. 10).
+3
+4
(
Fig. 8). In order to prove this correlation the reaction
IV
of Cl(Fe Pc) N in the presence of dimethylformamide
2
+
4
+4
having pK ≈ 2 was carried out. The spectroscopic data
a
suggested that there is indeed no reduction occurs.
IV
+3
+4
Thus the overall reaction of Cl(Fe Pc) N with
2
substrates under investigation may be written as a whole:
Thus considering the data obtained by UV-vis, IR,
IV
ESI-MS and EPR techniques, the addition of N-bases
(
Cl)(Fe Pc) N + 2L
2
to Cl(FePc) N benzene solution induces the reversible
(9)
2
k
III
IV


−
→ (L)PcFe − N = Fe Pc(L)
−
Cl
successive coordination of two electron–donor molecules
4
+
onto the different sites Fe (Equation 4) by means of
-
It should be noted that the N-bridged diiron complex
retains its binuclear structure during the reaction in the
presence of reducing agent in contrast to iron m-oxo-
dimers of porphyrin or phthalocyanine which have
undergone decomposition with the monomeric species
formation in similar reaction [40]. Furthermore, it was
donor–acceptor bonding. Simultaneously the axial Cl
readily displaces to the second coordination sphere.
Further slow reaction (Equation 5) results in one-
IV
+
-
electronreductionoftheintermediate[(L) (Fe Pc) N] Cl
2
2
III
IV
[41,42]with(L)PcFe –N=Fe Pc(L)formation.Probably
the transition Fe → Fe is promoted by electron–donor
4
+
3+
-6
-3
Fig. 9. Mass-spectrum of Cl(PcFe) N in acetonitryl solution in the presence of imidazole. C
= 4.13 × 10 M, C = 5.85 × 10 M
2
(FePc) N
Im
2
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 6–8

REDUCTION OF (CHLORO)-m-NITRIDO-BIS[(TETRA-tert-BUTYL-PHTHALOCYANINATO)IRON(IV)]
7
4
+
3+
to suppose the possibility of the transition Fe → Fe in
Cl(FePc) N in the presence of any substrate.
2
Acknowledgements
The reported study was supported by the Russian
Scientific Foundation, agreement No. 14-23-00204. This
work was carried out with the help of the centre of the
scientific equipment collective use “The upper Volga
region centre of physicochemical research”.
REFERENCES
1
. Ren QZ, Yao Y, Ding X-J, Hou Z-S and Yan D-Y.
Chem. Commun. 2009; 4732–4734. (DOI: 10.1039/
B904199K).
Fig. 10. EPR spectrum of Cl(FePc) N in CH Cl solution after
interaction with imidazole
2
2
2
2
. Afanasiev P, Kudrik EV, Sorokin AB, Koifman OI,
Albrieux F and Briois V. Chem. Commun. 2012;
6
088–6090. (DOI: 10.1039/C2CC31917A).
properties of substrate combined with the presence
of both electron-rich macrocycle and p-backdonation
Fe ← NPc.
The solution reduction in the presence of piperidine
and N-hydroxypiperidine have been presented earlier for
3. Silaghi-Dumitrescu R, Uta MM, Makarov SV,
Dereven’kovIAandStuzhinPA. NewJ. Chem. 2011;
35: 1140–1145. (DOI: 10.1039/C0NJ00827C).
4. Yusubov MS, Celik C, Geraskina MR,YoshimuraA,
Zhdankin VV and Nemykin VN. Tetrahedron
Lett. 2014; 55: 5687–5690. (DOI: 10.1016/j.tetlet.
2014.08.070).
5. Geraskin IM, Luedtke MW, Neu HM, Nemykin
VN and Zhdankin VV. Tetrahedron Lett. 2008; 49:
7410–7412. (DOI: 10.1016/j.tetlet.2008.10.060).
6. Harischandra DN, Lowery G, Zhang R and
Newcomb M. Org. Lett. 2009; 11: 2089–2092.
(DOI: 10.1021/ol900480p).
7. Neu HM,Yusupov MS, Zhdankin VV and Nemykin
VN. Adv. Synth. Catal. 2009; 351: 3168–3174.
(DOI: 10.1002/adsc.200900705).
8. Saka ET, Cakir D, Biyikliogli Z and Kantekin H.
Dyes Pigm. 2013; 98: 255–262. (DOI: 10.1016/j.
dyepig.2013.02.021).
(
chloro)(tetra-phenylporphinato)iron(III) and suggested
by NMR spectroscopy [43]. In that reaction the reducing
agent has been identified as the piperidine base by
detecting the previously characterized piperidine-1-oxyl
radical.
IV
It is noteworthy that in the case of [(L)PcFe –
IV
+
-
N=Fe Pc(L)] Cl only one axial ligand L, coordinated on
4
+
Fe belonging to Fe–N bond, facilitates the reduction of
4
+
iron cation while the second L, bound to Fe belonging
to Fe=N bond, does not participate in the reduction.
Obviously there is no an electron transfer in latter case
due to weak electron–donor binding metal-substrate.
9
. Sorokin AB and Tuel A. Catal. Today 2000; 57:
5–59. (DOI: 10.1016/S0920-5861(99)00312-0).
CONCLUSION
4
We have described the transformation of (chloro)-μ-
nitrido-bis[(tetra-tert-butyl-phthalocyaninato)iron(IV)]
10. Sorokin AB and Kudrik EV. Catal. Today 2011;
159: 37–46. (DOI: 10.1016/j.cattod.2010.06.020).
11. Kudrik EV, Afanasiev P, Alvarez LX, Dubour-
deaux P, Clémancey M, Latour J-M, Blondin G,
Bouchu D, Albrieux F, Nefedov SE and Sorokin
AB. Nat. Chem. 2012; 4: 1024–1029. (DOI: 10.
1038/nchem.1471).
12. Makarova AS, Kudrik EV, Makarov SV and Koif-
man OI. J. Porphyrins Phthalocyanines 2014; 18:
604–613. (DOI: 10.1142/S1088424614500369).
13. Li M and Scheidt WR. J. Porphyrins Phthalo-
cyanines 2014; 18: 380–384. (DOI: 10.1142/
S1088424614500096).
Cl(FePc) N in the presence of organic electron–donor
2
N-bases and generation of one-electron reduced species
III
IV
(
L)PcFe –N=Fe Pc(L). On the basis of the available
spectroscopic and reactivity data obtained the possible
reaction mechanism was proposed. The reaction is
the stepwise process including the pre-equilibrium of
axial coordination of two substrate molecules onto iron
cations followed by slow one-electron metal-centered
reduction. The latter may be interpreted in terms of
a base-assisted intramolecular electron transfer. The
+
3
+4
formation of final product with Fe –N=Fe unit and two
substrate molecules in the first coordination sphere was
supported by UV-vis, IR, ESI-MS and EPR methods. The
found correlations between pre-equilibrium constants,
reduction rate constants and basicity of substrates allow
14. Khatami MH, Bromberek M, Saika-Voivod I
and Booth V. Biochim. Biophys. Acta, Bio-
membr. 2014; 1838: 2778–2787. (DOI: 10.1016/j.
bbamem.2014.07.013).
Copyright © 2016 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2016; 20: 7–8

8
S. V. ZAITSEVA ET AL.
1
1
5. Blindauer CA. J. Inorg. Biochem. 2008; 102: 507–
29. Geng H and Zhang X-F. Spectrochim. Acta, Part A
2015;139:13–19.(DOI:10.1016/j.saa.2014.12.010).
30. BikramCKC, SubbaiyanNKandD’SouzaF. J. Phys.
Chem. C 2012; 116: 11964–11972. (DOI:10.1021/
jp303227s).
5
21. (DOI: 10.1016/j.jinorgbio.2007.10.032).
6. Satterlee JD, La Mar GN and Frye JS. J. Amer.
Chem. Soc. 1976; 98: 7275–7281. (DOI: 10.1021/
ja00439a027).
1
1
1
7. Ikeue T, Ohga Y, Vicente MGH and Nakamura M.
Inorg. Chem. 2003; 42: 5560–5571. (DOI: 10.1021/
ic0300969).
8. Praneeth VKK, Nather C, Peters G and Lehnert N.
Inorg. Chem. 2006; 45: 2795–2811. (DOI: 10.1021/
ic050865j).
31. Rossi G, Goedken VL and Ercolani C. J. Chem.
Soc., Chem. Commun. 1988: 46–47. (DOI: 10.1039/
C39880000046).
32. Zaitzeva SV, Zdanovich SA, Ageeva TA, Ochere-
tovi AS and Golubchikov OA. Molecules 2000; 5:
786–796. (DOI: 10.3390/50600786).
33. Zaitseva SV, Zdanovich SA, Koifman OI and
SemeikinAS. Russ. J. Gen. Chem. 2008; 78: 493–502.
34. Mamardashvili GM, Mamardashvili NZh and Koif-
man OI. Russ. J. Coord. Chem. 2011; 37: 195–201.
35. Mamardashvili NZh, Mamardashvili GM and Weiss
J. Russ. J. Inorg. Chem. 2005; 50: 218–224.
36. Jelikić-Stankov M, Veselinović D, Malešev D and
Radović Z. J. Pharm. Biomed. Anal. 1989; 7: 1571–
1577. (DOI: 10.1016/0731–7085(89)80167-0).
37. Sieversten S, Murray KS and Moubaraki B.
Z. Anorg. Allgem. Chem. 1994; 620: 1203.
9. Mamardashvili GM, Mamardashvili NZh and Koif-
man OI. Macroheterocycles 2013; 6: 67–73. (DOI:
1
0.6060/mhc130226m).
2
2
2
0. Zaitseva SV, Zdanovich SA and Golubchikov OA.
Russ. J. Coord. Chem. 2002; 28: 843–847.
1. SorokinAB, Kudrik EV and Bouchu D. Chem. Com-
mun. 2008: 2562–2564. (DOI: 10.1039/B804405H).
2. Wojciechowski BW and Rice N. Experimental
Methods in Kinetic Studies, 1nd Edition, Elsevier
Science: Amsterdam, 2003; p. 322.
3. Denisov ET and Sarkisov OM. Chemical Kinetics.
Fundamentals and New Developments, Elsevier:
Amsterdam, 2003; p. 547.
2
38. Stuzhin PA, Migalova IS and Berezin BD. Russ.
J. Inorg. Chem. 1998; 43: 1536–1541.
2
2
4. Lomova TN, Zaitseva SV, Molodkina OV and Age-
eva TA. Russ. J. Coord. Chem. 1999; 25: 397–401.
5. Afanasiev P, Bouchu D, Kudrik EV, Millet J-MM
and Sorokin AB. Dalton Trans. 2009: 9828–9836.
39. Bélanger S, Keefe MH, Welch JL and Hupp JT.
Coord. Chem. Rev. 1999; 190–192: 29–45. (DOI:
10.1016/S0010-8545(99)00062-4).
40. TrofimovaNS, SafronovAYandIkedaO. Inorg. Chem.
2003; 42: 1945–1951. (DOI: 10.1021/ic025830n).
41. Patra R, Sahoo D, Dey S, Sil D and Rath SP. Inorg.
Chem. 2012; 51: 11294–11305. (DOI: dx.doi.
org/10.1021/ic300229u).
42. Balch AL, Noll BC, Olmstead MM and Phillips SL.
Inorg. Chem. 1996; 35: 6495–6506.
43. Gaudio JD and La Mar GN. J. Amer. Chem. Soc.
1978; 100: 1112–1119.
(
DOI: 10.1039/B916047G).
2
2
2
6. Fukuzumi S, Honda T, Ohkubo K and Kojima T.
Dalton Trans. 2009: 3880–3889. (DOI: 10.1039/
B901191A).
7. Bandi V, El-Khouly ME, Nesterov VN, Karr PA,
Fukuzumi S and D’Souza F. J. Phys. Chem. C 2013;
1
17: 5638−5649. (DOI:10.1021/jp400046b).
8. Jacobs R, Stranius K, Maligaspe E, Lemmetyinen
H, Tkachenko NV, Zandler ME and D’Souza F.
Inorg. Chem. 2012; 51: 3656−3665. (DOI:10.1021/
ic202574q).
Copyright © 2016 World Scientific Publishing Company
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