A comparative study on the catalytic performance of heme and non-heme catalysts: Metal porphyrins versus metal Schiff bases

Article abstract of DOI:10.1002/aoc.3967

Catalytic activity and oxidative stability of a series of iron and manganese porphyrins with 2-chlorophenyl, phenyl and 4-methoxyphenyl at the meso positions and metallosalens (Mn- and Fe-salens) including N,N′-bis(salicylidene)ethylenediamine, N,N′-bis(5- chlorosalicylidene)ethylenediamine and N,N′-bis(2,4-dihydroxysalicylidene)ethylenediamine for the oxidation of olefins with tetra-n-butylammonium periodate (TBAP) and tetra-n-butyl-ammonium Oxone (TBAO) have been investigated and compared. Although the metalloporphyrins showed an increased catalytic activity relative to the Schiff base complexes, the former provided no significant catalytic advantage over the latter. Also, a comparable or slightly higher oxidative stability was observed for the Schiff base complexes under the reaction conditions. Furthermore, in spite of large difference between the oxidizing ability of TBAO and TBAP, similar patterns were observed for the order of catalytic activity and oxidative stability of the used heme and non-heme catalysts. The introduction of a methyl group at the ɑ position of styrene led to an increase in its reactivity, indicating the dominance of electronic effects over the steric ones in these catalytic systems.

Full text of DOI:10.1002/aoc.3967

Received: 5 May 2017
DOI: 10.1002/aoc.3967
Revised: 12 June 2017
Accepted: 17 June 2017
C O M M U N I C A T I O N
A comparative study on the catalytic performance of heme
and non‐heme catalysts: Metal porphyrins versus metal
Schiff bases
Atefeh Talaeizadeh | Mahdi Tofighi | Saeed Zakavi
Institute for Advanced Studies in Basic
Catalytic activity and oxidative stability of a series of iron and manganese por-
phyrins with 2‐chlorophenyl, phenyl and 4‐methoxyphenyl at the meso positions
and metallosalens (Mn‐ and Fe‐salens) including N,N′‐bis(salicylidene)
ethylenediamine, N,N′‐bis(5‐ chlorosalicylidene)ethylenediamine and N,N′‐bis
Sciences (IASBS), 45137‐66731 Zanjan,
Iran
Correspondence
Saeed Zakavi, Institute for Advanced
Studies in Basic Sciences (IASBS), 45137‐
(2,4‐dihydroxysalicylidene)ethylenediamine for the oxidation of olefins with
66731, Zanjan, Iran.
tetra‐n‐butylammonium periodate (TBAP) and tetra‐n‐butyl‐ammonium Oxone
(TBAO) have been investigated and compared. Although the metalloporphyrins
showed an increased catalytic activity relative to the Schiff base complexes, the
former provided no significant catalytic advantage over the latter. Also, a compa-
rable or slightly higher oxidative stability was observed for the Schiff base com-
plexes under the reaction conditions. Furthermore, in spite of large difference
between the oxidizing ability of TBAO and TBAP, similar patterns were observed
for the order of catalytic activity and oxidative stability of the used heme and non‐
heme catalysts. The introduction of a methyl group at the ɑ position of styrene
led to an increase in its reactivity, indicating the dominance of electronic effects
over the steric ones in these catalytic systems.
Email: zakavi@iasbs.ac.ir
https://iasbs.ac.ir/chemistry/dep=3&ef=
fa&page=personalpage.php&id=505
Funding information
Iran National Science Foundation (INSF),
Grant/Award Number: 95816928
KEYWORDS
iron and manganese complexes, olefins, oxidation, porphyrins, Schiff bases
1
| INTRODUCTION
they have found many applications in medicine, synthetic
chemistry and industry. The epoxidation of alkenes cata-
Porphyrins and Schiff bases are well known ligands which
received much attention over the past decades due to their
extensive applications in the field of homogeneous and
heterogeneous catalysis of organic and inorganic transfor-
lyzed by metalloporphyrins can proceed through the inter-
mediacy of high valent oxo‐metal intermediates analogue
to the oxoiron(V) species involved in cytochrome P450‐
[
1a]
mediated oxidations.
On the other hand, high valent
[1]
mations.
In 1979, the first article on the use of
manganese and iron oxo species were prepared using their
[
4]
metalloporphyrins as catalyst for the oxidation of alkanes
Schiff base complexes. In other words, both metal por-
phyrins and metal Schiff bases demonstrated ability to
form high valent oxo metal species under oxidative condi-
tions. Furthermore, there are some structural and chemi-
cal similarities between the Schiff bases and porphyrins
metal complexes such as the stability of the aromatic
ring, ability to form chelate rings and adopt a planar or
[1b]
and olefins was published by Groves et al.
However,
the first reports on the catalytic activity of Schiff base com-
plexes for the oxidation of hydrocarbons date back to ear-
[2]
lier than 1970. The metal complexes of Schiff bases and
porphyrins have been extensively utilized to mimic the
[3, 1a, 2b]
active site of heme and non‐heme enzymes.
Also,
Appl Organometal Chem. 2017;e3967.
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https://doi.org/10.1002/aoc.3967

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TALAEIZADEH ET AL.
approximately planar conformation and the ease of periph-
TABLE 1 The oxidation of olefins with TBAP in the presence of
[5]
metal porphyrins and metal salens in acetonitrile at room tempera-
eral substitution. The Schiff bases and their metal com-
plexes are usually prepared in higher yields using simple
and more efficient procedures and less expensive reactants
at lower temperatures in comparison with porphyrins and
metalloporphyrins. Furthermore, the former are usually
[a]
ture
[b,c]
Conversion (%)
Catalyst
no.
α‐Methyl
Styrene styrene Indene
Catalysts
[6]
prepared in greener solvent ethanol. Over the past
decades, periodate and Oxone were extensively used for
the oxidation of organic compounds in the presence of
[d]
1
2
3
4
5
MnTPP(OAc)
72 [16]
73
67
72
63
85
89
73
79
65
87
1
MnL (OAc)
27 [4]
[
7]
MnT(2‐Cl)PP(OAc)
76 [14]
65 [8]
metalloporphyrins and metal Schiff base complexes.
2
However, to date no comparative study was conducted on
the two classes of metal complexes. In the present study,
the Mn(III) and Fe(III) complexes of meso‐tetraphen
MnL (OAc)
MnT(4‐OMe)
91 [11]
PP(OAc)
ylporphyrin H TPP, meso‐tetrakis(2‐chlorophenyl)por-
3
2
6
MnL (OAc)
44 [100]
40 [72]
57 [11]
70 [6]
57
47
63
75
58
74
59
71
60
56
67
73
72
86
65
78
phyrin H T(2‐Cl)PP and meso‐tetrakis(4‐metoxyphenyl)
2
7
FeTPP(Cl)
porphyrin H T(4‐OMe)PP (Figure 1) and their similar
2
1
8
FeL (Cl)
salen‐type ligands N,N′‐Bis(salicylidene)ethylenediamine
1
9
FeT(2‐Cl)PP(Cl)
H L , N,N′‐Bis(5‐chlorosalicylidene)ethylenediamine H
2
2
2
2
L and N,N′‐Bis(2,4‐dihydroxysalicylidene)ethylenediami
10
11
FeL (Cl)
56 [9]
3
ne H L (Figure 1) were used as catalyst for the oxidation
2
FeT(4‐OMe)PP(Cl)
77 [66]
46 [38]
71 [31]
of olefins with tetra‐n‐butylammonium periodate (TBAP)
and tetra‐n‐butylammonium Oxone (TBAO) as moderate
and strong oxidants, respectively. The results of this study
show that in the catalytic oxidation of olefins with TBAP
and TBAO there is no significant advantage for the
metalloporphyrins over the Schiff base complexes and the
latter can be successfully used instead of the former.
3
12
FeL (Cl)
‐
Average conversion
(
metalloporphyrins)
‐
Average conversion
50 [28]
61
67
(
Schiff base
complexes)
a
The molar ratios of metalloporphyrin:ImH:olefin:TBAP are 1:10 (5 for the
iron porphyrins):85:170 and molar ratios of metallosalen:olefin:TBAP are
[
b]
1
:50:150. All reactions were repeated three times, analyzed by GC; the aver-
[
c]
age values with an error of ca. 5–10% are reported. Epoxide was formed as
2
2
| RESULTS AND DISCUSSION
.1 | Oxidation of olefins with TBAP
[
d]
the sole product. The data in brackets shows the oxidative stability (%) of
the catalyst evaluated on the basis of the absorbance changes (ΔA) at the λmax
of the metalloporphyrins or Schiff base complexes (ΔA/A).
The oxidation of different olefins was conducted with
TBAP (Table 1 and Figure 2) and the following orders of
catalytic activity were found:
FIGURE 2 The results for the oxidation of styrene, indene and α‐
methylstyrene with TBAP in the presence of the metalloporphyrins
(
series 1 [styrene], 3 [α‐methylstyrene] and 5 [indene]) and the
Schiff base complexes (series 2 [styrene], 4 [α‐methylstyrene] and 6
[indene]). See Table 1 for the catalyst numbers
Oxidation of styrene: MnT(4‐OMe)PP(OAc) > FeT(4‐
OMe)PP(Cl) ≈ MnT(2‐Cl)PP(OAc) ≥ MnTPP(OAc) ≈
2
1
2
FIGURE 1 Manganese and iron complexes used in this study
FeT(2‐Cl)PP(Cl) ≥ MnL (OAc) > FeL (Cl) ≈ FeL (Cl) >

TALAEIZADEH ET AL.
3
3 of 7
3
1
FeL (Cl) ≈ MnL (OAc) ≥ FeTPP(Cl) > MnL (OAc).
Running the oxidation reactions in the presence of the
metalloporphyrins and Schiff base complexes led to
average conversion values of ca. 70 and 50%, respectively.
Oxidation of ɑ‐methylstyrene: MnT(4‐OMeP)
P(OAc) > FeT(2‐ClP)P(Cl) ≈ FeT(4‐OMeP)P(Cl) ≈ MnT
1
2
PP(OAc) ≈ MnT(2‐ClP)P(OAc) > MnL (OAc) ≥ MnL
(
1
3
2
3
OAc) ≈ FeL (Cl) ≥ FeL (Cl) > FeL (Cl) ≈ MnL (OAc)
>
FeTPP(Cl). The oxidation products were achieved with
average conversion values of ca. 71 and 61% in the pres-
ence of the metalloporphyrins and Schiff base complexes,
respectively.
Oxidation of indene: MnTPP(OAc) ≈ MnT(4‐OMe)
PP(OAc) ≈ FeT(4‐OMe)PP(Cl) > MnT(2‐Cl)PP(OAc) ≥
1
2
1
MnL (OAc) ≈ FeT(2‐Cl)PP(Cl) ≈ FeL (Cl) > FeL (Cl) ≈
2
3
3
MnL (OAc) ≈ FeL (Cl) > MnL (OAc) > FeTPP(Cl). Aver-
age conversion values of ca. 78 and 67% were obtained in
the presence of the metalloporphyrins and Schiff base
complexes, respectively.
Although the metalloporphyrins were usually more
efficient than the Schiff base complexes, the average con-
versions achieved in the presence of the former were only
1
0–20% greater than those observed in the case of the latter.
FIGURE 3 (top) the absorbance changes upon the addition of
TBAP to a solution containing MnTPP(OAc) and ImH in 1:10
molar ratio (blue curve), immediately after the addition of the
oxidant (red curve) and after 4 h (green curve); (down) the changes
Also, the oxidative stability of catalysts in the oxida-
1
tion of styrene with TBAP decreased as MnL (OAc) ≈
FeT(2‐Cl)PP(Cl) ≥ MnL (OAc) ≥ FeL (Cl) ≥ FeL (Cl) ≈
MnT(4‐OMe)PP(OAc) ≥ MnT(2‐Cl)PP(OAc) ≥ MnTPP
2
2
1
1
in the UV–vis spectrum of FeL (cl) (blue curve), after the addition of
TBAP (10 min, red curve and 4 h, green curve)
3
(OAc) > FeL (Cl) >> FeT(4‐OMe)PP(Cl) ≥ FeTPP(Cl) >
3
MnL (OAc). The degree of catalyst degradation was mea-
sured on the basis of the absorbance changes (ΔA) at the
λmax of the catalysts (Figures 3 and Supporting Informa-
tion). It is observed that the Schiff base complexes are as
stable as the metalloporphyrins in the oxidation reactions
performed by periodate that seems to be due to the
absence of high valent metal oxo species in these catalytic
systems (vide infra).
stronger π‐π interaction between the porphyrin core and
the iron centre in comparison with the manganese centre
was suggested to explain the higher oxidative stability of
[
7k]
the iron porphyrins.
The presence of electron‐with-
drawing substituents at different positions of the meso‐
substituents makes them more electron‐deficient.
Furthermore, the introduction of bulky substituents such
as chlorine atom at the ortho position may be utilized to
increase the electron‐deficient character of metalloporphy-
rins. It should be noted that the latter leads to an increase
in the dihedral angle between the meso aryl substituents
and porphyrin mean plane and a decrease in the π
resonance interactions between their π systems.
As was observed, the average catalytic activity of the
metalloporphyrins was slightly (10–20%) greater than that
of the metal Schiff base complexes. It was previously
shown that a periodato six coordinate complex i.e.
The oxidative degradation of metalloporphyrins
occurs through an intermolecular mechanism by the
oxidative attack at the carbon atoms with high electron
[8]
density i.e. the meso, ɑ and β positions. It is noteworthy
that according to the four orbital model of porphyrins, the
electron density of the a1u and a2u orbitals of porphyrins
are largest on the meso, β and ɑ carbons.
The catalytic activity of manganese and iron porphy-
rins depends on the steroelectronic properties of the meso
[1a, 1b, 1c, 1d, 1e]
substituents and nature of the metal centre.
As was shown in previous studies, electron‐rich manga-
nese and iron porphyrins are usually more efficient than
the electron‐demanding ones. However, the electron‐defi-
cient metalloporphyrins are often more stable towards
oxidative degradation.
Also, manganese porphyrins usually show higher
catalytic activity compared to the iron counterparts. The
(ImH)M(Porphyrin)(IO ) (M = Fe or Mn) is the main
4
active oxidant species in the metalloporphyrin catalyzed
[
1k,7d,I,j]
oxidation of olefins with periodate
in combination
with a high valent oxo metal species as the minor one.
Accordingly, the Mn(III) or Fe(III) species are responsible
for the catalytic activity of the two series of the catalyts
and therefore no large differences were observed between
[7d, 7i, 7j]

4
of 7
TALAEIZADEH ET AL.
the catalytic activity of these catalysts. Also, the low
oxidizing ability of the dominant active oxidant led to
the comparable oxidative stability of the used heme and
non‐heme catalysts.
TABLE 2 The oxidation of olefins with TBAO in the presence of
metal porphyrins and metallosalens in acetonitrile at room
[a]
temperature
[b,c]
Conversion (%)
Furthermore, the comparison of the reactivity of
styrene and ɑ‐methylstyrene shows that the steric effects
of the methyl group have no effect on the reactivity of
styrene. In the case of the Schiff base complexes, the
dominance of the electronic effects of the methyl group
over its steric effects led to the higher reactivity of
ɑ‐methylstyrene. On the other hand, higher reactivity of
indene compared to styrenes seems to be due to the more
reactivity of strained double bond of indene relative to the
Catalyst
no.
α‐Methyl
styrene Indene
Catalysts
Styrene
[d]
1
2
3
4
5
MnTPP(OAc)
37 [100]
96 [100]
99
99
98
98
95
96
93
98
97
94
1
MnL (OAc)
MnT(2‐Cl)PP(OAc)
100 [49]
91 [100]
94 [100]
2
MnL (OAc)
MnT(4‐OMe)
PP(OAc)
[1n]
non‐strained terminal double bond of styrene.
How-
3
6
7
8
9
MnL (OAc)
41 [13]
84 [88]
85
93
73
98
30
87
59
95
58
86
75
93
71
84
71
92
ever, the nearly planar structure of indene which
decreases the steric hindrance about the reaction center
may be also involved.
FeTPP(Cl)
1
FeL (Cl)
49 [100]
100 [22]
28 [100]
65 [84]
FeT(2‐Cl)PP(Cl)
2
10
11
12
‐
FeL (Cl)
2.2 | Oxidation of olefins with TBAO
FeT(4‐OMe)PP(Cl)
The oxidation of olefins was also conducted with TBAO as
a strong oxidant and the catalytic activity of the catalysts
was found to decrease as follows:
3
FeL (Cl)
16 [100]
80 [74]
Average conversion
metalloporphyrins)
(
Oxidation of styrene: MnT(2‐ClP)P(OAc) ≈ FeT(2‐
1
‐
Average conversion
Schiff base
complexes)
53 [85]
74
77
ClP)P(Cl) ≥ MnL (OAc) ≈ MnT(4‐OMeP)P(OAc) > Mn
(
2
1
L (OAc) > FeTPP(Cl) > FeT(4‐OMeP)P(Cl) > FeL (Cl)
3
2
3
>
MnL (OAc) ≥ MnTPP(OAc) > FeL (Cl) > FeL (Cl).
[
a] See the footnotes of Table 1.
Oxidation of ɑ‐methylstyrene: MnT(2‐ClP)P(OAc) ≈
2
MnL (OAc) ≈ MnTPP(OAc) ≥ MnT(4‐OMeP)P(OAc) ≈
1
1
MnL (OAc) ≈ FeT(2‐ClP)P(Cl) > FeTPP(Cl) ≈ FeT(4‐
may be considered to be nearly as stable as the Schiff base
complexes. In other words, the heme and non‐heme com-
plexes used in this study are of similar oxidative stability
in the presene of periodate and TBAO as moderate and
strong terminal oxidants, respectively. However, the
increased oxidative stability of the former seems to be
due to the more extended aromatic system of the
metalloporphyrins.
1
2
3
OMeP)P(Cl) > FeL (Cl) > FeL (Cl) > MnL (OAc) > Fe
L (Cl).
3
2
Oxidation of indene: MnT(2‐ClP)P(OAc) ≈ MnL
(OAc) ≈ MnTPP(OAc) ≥ MnT(4‐OMeP)P(OAc) ≈ Mn
L1(OAc) ≈ FeT(2‐ClP)P(Cl) > FeTPP(Cl) ≈ FeT(4‐OM
1
2
3
3
eP)P(Cl) > FeL (Cl) > FeL (Cl) > MnL (OAc) > FeL (Cl).
Furthermore, the stability of catalysts under the oxida-
3
tion conditions decreased as MnL (OAc) > FeT(2‐ClP)
P(Cl) > MnT(2‐ClP)P(OAc) > FeT(4‐OMeP)P(Cl) ≥ FeT
PP(Cl) > MnTPP(OAc) ≈ MnT(4‐OMeP)P(OAc) ≈ Mn
1
1
2
3
L (OAc) ≈ MnL2(OAc) ≈ FeL (Cl) ≈ FeL (Cl) ≈ FeL (Cl).
As may be seen from Table 2 and Figure 4, the
metalloporphyrins are again more efficient than the Schiff
base complexes with average conversion values that are
1
5–30% greater than those obtained in the case of the
Schiff base complexes. However, the former shows an
increased (ca. 10%) oxidative stability. As was shown in
a previous study [1l, 1m], the oxidation of olefins with
strong oxidants such as TBAO and iodosylbenzene in
the presence of metalloporphyrins is accompanied with
the formation of high‐valent metal oxo species as the
major active oxidant. As was observed in the case of the
oxidation of olefins with periodate, the metalloporphyrins
FIGURE 4 The results for the oxidation of styrene, indene and α‐
methylstyrene with TBAO in the presence of the metalloporphyrins
(
series 1 [styrene], 3 [α‐methylstyrene] and 5 [indene]) and Schiff
base complexes (series 2 [styrene], 4 [α‐methylstyrene] and 6
[indene]). See Table 2 for the catalyst numbers

TALAEIZADEH ET AL.
5 of 7
Also, the increased reactivity of ɑ‐methystyrene com-
pared to that of styrene gave evidence for the dominance
of the electronic effects over the steric effects of the
methyl group.
8.36 (2H, s, N = CH), 9.20 (2H, Ph‐OH),13.68 (2H,
Ph‐OH).
Also, meso‐tetraphenylporphyrin, H TPP, meso‐
2
tetrakis(4‐OCH phenyl)porphyrin, H T(4‐OMe)PP and
3
2
A comparison of the data summarized in Tables 1 and
, shows higher conversion values for the oxidation of ole-
meso‐tetrakis(2‐Clphenyl)porphyrin, H T(2‐Cl)PP have
been prepared according to the Adler et al. method
2
[10]
2
fins performed with TBAO. This observation is in accord
with higher oxidizing ability of TBAO compared to that
of TBAP. However, comparable or nearly comparable
catalytic activity and oxidative stability were found for
the used heme and non‐heme catalysts in the presence
of TBAP and TBAO as moderate and strong terminal
oxidants, respectively.
by reaction of pyrrole (5.6 ml, 0.08 mole) and benzalde-
hyde (8 ml, 0.08 mole) in 300 ml refluxing propionic acid.
After 30 min, the mixture was filtered and the filtrate
was washed thoroughly with methanol and hot water,
respectively. The air dried purple crystals, were chroma
tographed on a neutral alumina column using chloroform
1
as the eluent. H TPP. H NMR (400 MHz, CDCl , TMS),
2
3
δ/ppm: −2.71 (2H, br, s, NH), 7.77–7.83 (8Hm and 4Hp,
m), 8.26–8.28 (8H , dd), 8.90 (8H , s); UV–Vis in CH Cl ,
o
β
2
2
λmax/nm (logε): 416 (5.79), 513 (4.58), 542 (4.38), 584
3
3
| EXPERIMENTAL
1
(
4.30), 644 (4.29); H T(4‐OMeP)P. H NMR (400 MHz,
2
CDCl , TMS), δ/ppm: −2.71 (2H, br, s, NH), 4.13 (4H, s,
3
.1 | Preparation of ligands
−
OMe), 7.30–7.33 (8H , d), 8.14–8.16 (8H , d), 8.89
m
o
1
N,N′‐bis(salicylidene)ethylenediamine (H L ), N,N′‐bis(5‐
chlorosalicylidene)ethylenediamine (H L ) and N,N′‐
bis(2,4‐dihydroxysalicylidene)ethylenediamine
(8H , s); UV–Vis in CH Cl , λmax/nm (logε): 421 (5.61),
2
β
2
2
2
2
513 (4.32), 555 (4.22), 585 (4.06), 651 (4.11); H T(2‐ClP)
2
3
1
(H L )
P. H NMR (400 MHz, CDCl , TMS), δ/ppm: −2.62 (2H,
2
3
were synthesised according to the literature by the con-
densation of ethylenediamine and substituted salicyla
ldehyde in ethanol under reflux conditions; In a typical
s, NH), 7.39–7.87 (8H , 4H , m), 8.10–8.48 (4H , m),
m
p
o
8.73 (8 H , s); UV–Vis in CH Cl , λmax/nm (logε): 416
β
2
2
[9]
(5.64), 511 (4.47), 542 (4.07), 587 (4.15), 653 (3.96).
reaction, 0.2 ml (2 mmol) salicylaldehyde and 67 μl
(1 mmol) ethylenediamine were added to a round‐bottom
flask containing 30 ml ethanol and the mixture was
3.2 | Preparation of metal complexes
1
refluxed for 1 h. The yellow precipitates (H L ) obtained
2
3.2.1 | Manganese complexes
after cooling the solution, were washed with cold ethanol
and dried under air. Yield (> 90%), mp 129–131 C.
C H N O (268.31): Calcd. C 71.62, H 6.016, N 10.44.
Manganese porphyrins were prepared by refluxing
Mn(OAc) .4H O in DMF according to the procedure of
16
16
2
2
2
2
11]
[
Found C 70.73, H 6.17, N 10.25%. Selected FT‐IR data, ν
Adler et al.
The progress of reaction was monitored
−
1
(
(
cm ): 3418 (O–H), 2902 (C–H), 1629 (C = N), 1494
by UV–vis spectroscopy; MnTPP(OAc). Calcd.: C 76.03,
H 4.30, N 7.71. Found C 73.17, H 4.11, N 7.10%. UV–Vis
(λmax/nm) in CH Cl : 470 (Soret band), 575, 612; MnT(4‐
1
C = C), 1283 (C–O). UV–Vis, λ (nm): 244, 255, 316. H
NMR (δ): 3.96 (4H, s, H C‐CH ), 6.89–7.34 (8H, m, Ph),
2
2
2
2
8
.38 (2H, s, N = CH), 13.25 (2H, Ph‐OH).
OMeP)P(OAc). Calcd. C 70.92, H 4.64, N 6.62. Found C
2
The synthesis of H L was performed using the same
67.54, H 4.62, N 6.33%. UV–Vis (λmax/nm) in CH Cl :
2
2
2
procedure by using 5‐chloro‐2‐hydroxybenzaldehyde.
Yield (> 90%), mp 179–181 C. C H N O Cl (337.2):
Calc. C 56.99, H 4.18, N 8.31. Found C 56.65, H 3.95, N
475 (Soret band), 578, 614; MnT(2‐ClP)P(OAc). Calcd.: C
63.91, H 3.15, N 6.48. Found C 62.19, H 3.17, N 6.25%.
UV–Vis (λmax/nm) in CH Cl : 471 (Soret band), 574, 603.
̊
1
6
14
2
2
2
2
2
−
1
8
.73%. Selected FT‐IR data, ν (cm ): 3416 (O–H), 2900
The Mn(III)–Salen complexes were prepared by
refluxing an ethanolic solution of ligand and
manganese(II) acetate tetrahydrate in 1:1 molar ratio for
(
C–H), 1628 (C = N), 1481 (C = C), 1274 (C–O), 825 (C‐
1
Cl). UV–Vis, λ (nm): 215, 274, 307. H NMR (δ): 3.98
4H, s, H C‐CH ), 6.91–7.29 (6H, m, Ph), 8.32 (2H, s,
[
12]
(
1 h
The solution was cooled in ice‐water, filtered and
2
2
N = CH), 13.15 (2H, Ph‐OH).
H2L was prepared by the reaction of 2,4‐
dihydroxybenzaldehyde and ethylenediamine. Yield (>
the residue was washed with cold ethanol to obtain the
brown crystalline MnL (OAc), MnL (OAc) and
3
1
2
3
1
MnL (OAc); MnL (OAc). Calcd. C 56.85, H 4.51, N 7.37.
−
1
9
9
0%), C H N O (300.31): Calcd. C 63.99, H 5.37, N
Found C 56.51, H 3.70, N 7.47%. FT‐IR data, ν (cm ):
3417 (O–H), 2922 (C–H), 1633 (C = N), 1437 (C = C),
1289 (C–O); UV–Vis (λmax/nm) in acetonitrile: 403;
16
16 2 4
.33. Found C 63.74, H 4.79, N 9.43%. Selected FT‐IR data,
−
1
ν (cm ): 3416 (O–H), 2869 (C–H), 1638 (C = N), 1468
1
2
(C = C), 1229 (C–O). UV–Vis, λ (nm): 221, 253, 326. H
MnL (OAc). Calcd. C 48.13, H, 3.37, N 6.24. Found C
−
1
NMR (δ): 3.78 (4H, s, H C‐CH ), 6.16–7.18 (6H, m, Ph),
48.81, H 3.57, N 6.34%. FT‐IR data, ν (cm ): 3417 (O–
2
2

6
of 7
TALAEIZADEH ET AL.
H), 2920 (C–H), 1632 (C = N), 1450 (C = C), 1291 (C–O),
temperature. The molar ratios of catalyst:ImH:alkene:
TBAP were 1:10:85:170 and 1:5:85:170 in the presence of
8
4
10 (C‐Cl); UV–Vis (λmax/nm) in acetonitrile/methanol:
3
[7d, 7j]
[7i]
07; MnL (OAc). Calcd. C 52.44, H 4.16, N 6.79. Found:
manganese
and iron
porphyrins, respectively.
−
1
C 53.46, H 3.76, N 7.34%. FT‐IR data, ν (cm ): 3413 (O–
H), 2923 (C–H), 1594 (C = N), 1478 (C = C), 1232 (C–
O); UV–vis (λmax/nm) in acetonitrile/methanol: 482.
After the required time, diethyl ether was added to the
flask and the reaction mixture was passed through a short
silicagel column to remove the unreacted tetra‐n‐
butylammonium periodate and the remaining catalyst.
In the oxidations with TBAO, catalyst, ImH, olefin and
oxidant were used in 1:20:50:150 molar ratios. Also, at
the end of the reaction, sodium bisulfite was added to
terminate the reaction.
3.2.2 | Iron complexes
The iron porphyrins were obtained using FeCl .4H O
2
13]
2
[
according to the procedure of of Kobayashi et al.
The
progress of reaction was monitored by UV–Vis spectros-
copy; FeTPP(Cl) Calcd. C 75.06; H 4.01; N 7.96. Found C
In the case of the Schiff base complexes, 0.01 mmol of
the complex was added to 0.5 mmol of alkene in 3 ml
acetonitrile. The reaction was initiated by the addition of
1.5 mmol (0.65 g) TBAP. After the required time (4 h),
3 ml diethyl ether was added to the reaction mixture
and the mixture was passed through a short alumina
column to eliminate the unreacted oxidant and catalyst.
The molar ratios of catalyst:alkene:TBAP are 1:50:150.
7
3
0.42, H 4.42, N 7.23%. UV–Vis (λmax/nm) in CH Cl :
78, 413 (Soret band), 509, 574, 662, 690; FeT(2‐ClP)
2
2
P(Cl) Calcd. C 62.78, H 2.87, N 6.66. Found C 60.59, H
3
.15, N 6.01%. UV–Vis (λmax/nm) in CH Cl : 372, 414
2
2
(Soret band), 506, 578, 651, 681; FeT(4‐OMeP)P(Cl);
Calcd.: C 69.95, H 4.40, N 6.80. Found C 64.01, H 4.81,
N 6.13%. UV–Vis (λmax/nm) in CH Cl 421 (Soret band),
2
2:
5
11, 572, 698.
3
.3 | Degradation of catalysts
The iron complexes of Schiff bases have been prepared
[14]
1
2
according to the literatur.
pared by refluxing the corresponding ligands (1 mmol)
with FeCl .6H O (1 mmol) in ethanol (30 ml) in the pres-
FeL and FeL were pre-
Degradation of catalysts was followed by UV–vis spectros-
copy at their λmax.
the catalysts has been compared with that of the initial
one to measure the extent of degradation of the
metalloporphyrins.
[
7i, 7j, 8a]
The absorbance at the λmax of
3
2
ence of 5 drops of triethylamine. At the end of the reaction
30 min), the solution was cooled and the solid product
(
3
was filtered off and dried in air. In the case of FeL ,
ml acetone was used in addition to 30 ml ethanol and
5
3
.3.1 | Instrumental
the solution was refluxed for 1 h under argon
atomosphere. At the end of the reaction, air was bubbled
through the solution for 10 min. FeL (Cl). Calcd. C 53.74,
A Varian‐3800 gas chromatograph equipped with a HP‐5
capillary column (phenylmethyl siloxane 30 m × 320 μm
×
1
H 3.95, N 7.83. Found C 48.77, H 3.57, N 8.38%. FT‐IR
0.25 μm) or a packed column (Chromosorb WHP 80–
−
1
data, ν (cm ): 3413 (O–H), 2927 (C–H), 1627 (C = N),
443 (C = C), 1266 (C–O); UV–Vis (λmax/nm) in acetoni-
100 Mesh, 4 mm × ¼ × 2 m) and a flame‐ionization detec-
1
1
tor was used to analyze the reactions. H NMR spectra
were obtained on a Bruker Avance DPX‐400 MHz spec-
trometer. The absorption spectra were recorded on a
Pharmacia Biotech Ultrospec 4000 UV–Vis spectro
photometer.
2
trile: 472; feL (Cl). Calcd. C 45.06, H 2.84, N 6.57. Found
−
1
C 44.55, H 2.56, N 7.02%; FT‐IR data, ν (cm ): 3413 (O–
H), 2920 (C–H), 1628 (C = N), 1422 (C = C), 1298 (C–
O); UV–Vis (λmax/nm) in acetonitrile/methanol: 508;
feL (Cl). Calcd. C 49.33, H 3.62, N 7.19. Found C 44.82,
H 3.96, N 6.52%. FT‐IR data, ν (cm ): 3414 (O–H), 2849
3
−
1
(
(
C–H), 1590 (C = N), 1479 (C = C), 1245 (C–O); UV–vis
λmax/nm) in acetonitrile/methanol: 475.
4 | CONCLUSION
The oxidation of olefins with TBAP and TBAO in the pres-
ence of a series of manganese and iron porphyrins and
their similar Schiff bases complexes was conducted in
acetonitrile at room temperature and found that: (a) the
Schiff base complexes showed their optimum catalytic
activity at a concentration approximately equal to that of
the metalloporphyrins; (b) the Schiff base ligands and
complexes may be prepared under milder conditions.
Also, the purification of these compounds was more
simple than that of the porphyrins and metalloporphyrins;
3
.2.3 | Catalytic oxidation of alkenes
Stock solutions of the metalloporphyrins (0.003 M) and
ImH (0.5 M) were prepared in acetonitrile. In a typical
reaction, alkene (0.25 mmol), metalloporphyrin
(0.003 mmol, 1 ml) and ImH (0.03 mmol, 60 μl) were
added into a 10 ml round bottom flask containing 1 ml
of CH CN. Then, 0.5 mmol (0.217 g) TBAP has been
added. The mixture was stirred thoroughly for 4 h at room
3

TALAEIZADEH ET AL.
7 of 7
(
c) while the Schiff base complexes were less soluble
2015, 4, 119; c) K. C. Gupta, A. K. Sutar, Coor. Chem. Rev.
2008, 252, 1420.
compared to the metalloporphyrins, the former showed
catalytic activities comparable to those of the
metalloporphyrin; (d) the results of this study show that
in the catalytic oxidation of olefins with TBAP and TBAO,
the metalloporphyrins are to some extent (10–30%) more
efficient and more stable (ca. 10%) than the Schiff base
complexes. However, there is no preference for the
metalloporphyrins over the Schiff base complexes and
therefore the latter may be successfully used instead of
the former for the catalysis of the oxidation reactions.
[7] a) D. Mohajer, S. Tangestaninejad, J. Chem. Soc., Chem.
Commun. 1993, 240; b) D. Mohajer, S. Tangestaninejad, Tetra-
hedron lett. 1994, 35, 945; c) D. Mohajer, A. Rezaeifard,
Tetrahedron Lett. 2002, 43, 1881; d) D. Mohajer, G. Karimipour,
M. Bagherzadeh, New J. Chem. 2004, 28, 740; e) S.
Tangestaninejad,
M.
Moghadam,
V.
Mirkhani,
I.
Mohammadpoor‐Baltork, M. Saeedi, Appl. Catal. A: Gen.
2010, 381, 233; f) V. Mirkhani, M. Moghadam, S.
Tangestaninejad, I. Mohammdpoor‐Baltork, H. Kargar, M.
Araghi, Appl. Catal. A: Gen. 2009, 353, 61; g) V. Mirkhani, M.
Moghadam, S. Tangestaninejad, B. Bahramian, Polyhedron
2006, 25, 2904; h) M. Mirkhani, S. Moghadam, B.
ACKNOWLEDGEMENTS
Tangestaninejad, J. Bahramian, Iran. Chem. Soc. 2008, 5, 375;
i) S. Zakavi, T. Mokaryyazdeli, J. Mol. Catal. A: Chem. 2013,
Financial support of this work by the Iran National
Science Foundation (INSF) under grant No. 95816928
and IASBS is acknowledged.
368, 108; j) S. Zakavi, A. G. Mojarrad, S. Rayati, J. Mol. Catal.
A: Chem. 2012, 363, 153.
[
8] a) I. D. Cunningham, T. N. Danks, J. N. Hay, I. Hamerton, S.
Gunathilagan, C. J. Janczak, J. Mol. Catal. A: Chem. 2002,
1
85, 25; b) A. C. Serra, E. C. Marçalo, A. M. d.’ A.
REFERENCES
RochaGonsalves, J. Mol. Catal. A Chem. 2004, 215, 17; c)
S. L. H. Rebelo, M. M. Pereira, M. M. Q. Simões, P. M. A. Graça,
M. G. P. M. S. Neves, J. A. S. Cavaleiro, J. Catal. 2005, 234, 76; d)
C. Bruckner, E. D. Sternberg, J. K. MacAlpine, S. J. Rettig, D.
Dolphin, J. Am. Chem. Soc. 1999, 121, 2609.
[
1] a) B. Meunier, World Scientific 2000, 3; b) J. T. Groves, T. E.
Nemo, R. S. Myers, J. Am. Chem. Soc. 1979, 101, 1032; c) T.
Katsuki, J. Mol. Catal. A: Chem. 1996, 113, 87; d) T. Katsuki,
Coord. Chem. Rev. 1995, 140, 189; e) B. Meunier, Chem. Rev.
1
992, 92, 1411; f) B. Huang, Y. Wang, S. Zhan, J. Ye, Appl.
[9] a) T. Katsuki, J. Mol. Catal. A: Chem. 1996, 113, 87. b) T.
Surface Sci. 2017, 396, 121; g) J. R. Lindsay Smith, in
Metalloporphyrins in Catalytic Oxidations, (Ed: R. A. Sheldon),
Marcel Dekker Inc., New York 1994; h) M. Sedighipoor, A. H.
Kianfar, W. A. K. Mahmood, M. H. Azarian, Inorg. Chim. Acta
Katsuki, Coord. Chem. Rev. 1995, 140, 189.
[
[
10] A. D. Adler, F. R. Longo, J. D. Finarelli, J. Org. Chem. 1967, 32,
76.
4
11] A. D. Adler, F. R. Longo, F. Kampas, J. Kim, J. Inorg. Nucl.
Chem. 1970, 32, 2443.
2
017, 457, 116; i) J. B. Fenga, X. F. Wua, Appl. Organometal.
Chem. 2015, 29, 63; j) Y. Li, B. Sun, Y. Zhou, W. Yang, Appl.
Organometal. Chem. 2017, 31 In press; k) S. Zakavi, Z.
Kayhomayoon, S. Rayati, J. Iran. Chem. Soc. 2015, 12, 863; l)
R. Nasrollahi, S. Zakavi, Eur. J. Inorg. Chem. 2002, 2017; m)
J. T. Groves, T. E. Nemo, J. Am. Chem. Soc. 1983, 105, 5786; n)
S. Zakavi, A. S. Ashtiani, S. Rayati, Polyhedron 2010, 29, 1492.
[12] K. Srinivasan, P. Michaud, J. K. Kochi, J. Am. Chem. Soc. 1986,
108, 2309.
[
13] H. Kobayashi, T. Higuchi, Y. Kaizu, H. Osada, M. Aoki, Bull.
Chem. Soc. Jpn. 1975, 48, 3137.
[
14] a) D. Brahman, B. Sinha, J. Serb. Chem. Soc. 2014, 79, 225; b) S.
Routier, H. Vezin, E. Lamour, J. L. Bernier, J. P. Catteau, C.
Bailly, Nucleic Acids Res. 1999, 27, 4160.
[
2] a) H. Nozaki, H. Takaya, S. Moriuti, R. Noyori, Tetrahedron
1
968, 24, 3655; b) R. A. Sheldon, J. K. Kochi, Metal‐Catalyzed
Oxidations of Organic Compounds, Academic Press Inc., New
York 1981; c) A. Nishinaga, H. Tomita, T. Shimizu, T.
Matsuura, in Fundamental Research in Homogeneous Catalysis,
SUPPORTING INFORMATION
(
Eds: Y. Ishii, M. Tsutsui) Vol. 2, Plenum, New York 1978 241.
Additional Supporting Information may be found online
in the supporting information tab for this article.
[
3] W. Nam, Acc. Chem. Res. 2007, 40, 522.
[
4] a) G. Olivo, O. Lanzalunga, S. D. Stefano, Adv. Synth. Catal.
2
016, 358, 843; b) C. A. McAuliffe, R. V. Parish, Inorg. Chim.
Acta 1986, 115, 91; c) D. D. Agarwal, R. P. Bhatnagar, R. Jain,
S. Srivastava, J. Chem. Soc., Perkin Trans. 2 1990, 989.
How to cite this article: Talaeizadeh A, Tofighi
M, Zakavi S. A comparative study on the catalytic
performance of heme and non‐heme catalysts:
Metal porphyrins versus metal Schiff bases. Appl
Organometal Chem. 2017;e3967. https://doi.org/
[
[
5] C. N. Cornell, M. S. Sigman, in Activation of Small Molecules:
Organometallic and Bioinorganic Perspectives, (Ed: W. B.
Tolman), Wiley‐VCH Verlag GmbH & Co. 2006 159.
6] a) P. G. Cozzi, Chem. Soc. Rev. 2004, 33, 410; b) A. M. Abu‐
Diefa, I. M. A. Mohamed, Beni‐Suef Univ. J. Basic Appl. Sci.
10.1002/aoc.3967