Synthesis and characterization of iron(III) complexes of 5-(8-carboxy-1-naphthyl)-10, 15, 20-tritolyl porphyrin

Article abstract of DOI:10.1002/zaac.201300136

5-(8-Carboxy-1-naphthyl)-10, 5, 20-tritolyl porphyrin (H₃CNTTP) and its iron(III) complexes, [Fe(CNTTP)]₂ and [Fe(CNTTP)(N-MeIm) ₂], were synthesized and characterized. X-ray crystallography revealed that the carboxylate group is hanging over the porphyrin plane. The rigid framework makes the distance between the carboxylate oxygen and iron in the same porphyrin too long to form a coordination bond. On the other hand, the carboxylate group is not bulky enough to block the axial binding site. In the presence of OH^-, the carboxylate oxygen is coordinated to iron in the symmetry-related unit, which led to the dimeric structure, [Fe(CNTTP)]₂. In the presence of excess N-methylimidazole, a six-coordinate species, [Fe(CNTTP)(N-MeIm)₂], was obtained. In such a structure, CH···O interactions between the carboxylate group and imidazole probably play an important role to determine the orientation of imidazole plane. Two imidazole planes have relative parallel orientation. For [Fe(CNTTP)(N-MeIm)₂], ¹H NMR shows pyrrole protons at the region -10 to -25 ppm. EPR shows rhombic spectrum. Those suggest [Fe(CNTTP)(N-MeIm)₂] is a type II low-spin iron(III) porphyrinate. Copyright

Full text of DOI:10.1002/zaac.201300136

Job/Unit: Z13136
/KAP1
Date: 06-05-13 10:50:42
Pages: 9
ARTICLE
DOI: 10.1002/zaac.201300136
Synthesis and Characterization of Iron(III) Complexes of
5-(8-Carboxy-1-naphthyl)-10,15,20-tritolyl Porphyrin
Yu Zhang,[a] Jiaxun Jiang,[a] and Chuanjiang Hu*[a,b]
Keywords: Iron porphyrin; Carboxylate; Imidazole; Iron; CH···O interactions
Abstract.
5-(8-Carboxy-1-naphthyl)-10,15,20-tritolyl
porphyrin
related unit, which led to the dimeric structure, [Fe(CNTTP)]2. In the
(H3CNTTP) and its iron(III) complexes, [Fe(CNTTP)]2 and presence of excess N-methylimidazole, a six-coordinate species,
[Fe(CNTTP)(N-MeIm)2], were synthesized and characterized. X-ray [Fe(CNTTP)(N-MeIm)2], was obtained. In such a structure, CH···O
crystallography revealed that the carboxylate group is “hanging” over interactions between the carboxylate group and imidazole probably
the porphyrin plane. The rigid framework makes the distance between
play an important role to determine the orientation of imidazole plane.
the carboxylate oxygen and iron in the same porphyrin too long to Two imidazole planes have relative parallel orientation. For
form a coordination bond. On the other hand, the carboxylate group is
not bulky enough to block the axial binding site. In the presence of
[Fe(CNTTP)(N-MeIm)2], 1H NMR shows pyrrole protons at the region
–10 to –25 ppm. EPR shows rhombic spectrum. Those suggest
OH–, the carboxylate oxygen is coordinated to iron in the symmetry- [Fe(CNTTP)(N-MeIm)2] is a type II low-spin iron(III) porphyrinate.
that this strong hydrogen bond increases the basicity of the
His170 proximal ligand, thus helping to stabilize the high oxi-
dation state intermediates.[3,4]
Introduction
Iron porphyrin is the common prosthetic group in many bio-
logical systems, such as globins, whose biological function is
the reversible transport and storage of dioxygen, the perox-
idases, enzymes that catalyze the conversion of hydrogen per-
oxide to water and/or the oxidation of substrates. In these bio-
logical systems, the first coordination sphere for the central
metal (iron) atom is comprised by iron and a variety of axial
ligands, such as histidines, tyrosines, thiolates, water etc. The
functions of these systems are not only related to their first
coordination spheres, but also their second coordination
spheres. The second coordination sphere interactions, such as
hydrogen bonds, π–π stacking, cation–π interactions, CH···O
interactions etc., are commonly noncovalent interactions be-
tween surrounding molecules and the ligands.[1]
For example, globins and peroxidases have different bio-
logical functions even they both have the histidines as axial
ligands. Structures suggest in the globins a weak hydrogen
bond is formed between the coordinated histidine and a nearby
carbonyl group,[2] whereas in the peroxidases the coordinated
histidine is strongly hydrogen-bonded to a conserved aspart-
ate.[3] The role of the hydrogen bond is still one of the unre-
solved issues concerning peroxidases. It has been postulated
Besides hydrogen bonding, other non-covalent interactions
are also common in biological systems. For examples, π–π
interactions have been recognized to play an important role in
the folding[5] and the thermal stability of proteins,[6] in mRNA-
cap recognition by proteins (in combination with cation–π in-
teractions).[7] It is also admitted that the weak interactions
termed unconventional CH···O interactions contribute to the
structural stability of proteins.[8]
Model complexes have been invaluable as a means of under-
standing some general structure-function relationships. Many
model systems have been intensively investigated in the last
decades. For example, Collman and co-workers have recently
developed an efficient synthetic model of cytochrome c ox-
idases.[9] Such a model can perform the selective four-electron
reduction of oxygen to water using cytochrome c. In their stud-
ies, they also suggest, there is an axial water ligand in the distal
pocket. Such water further forms hydrogen bonds to other H2O
molecules. This slows down O2 binding as those reported for
the actual Cco enzyme.[10] Nocera and co-workers have devel-
oped a “Hangman” porphyrin, which is composed of porphyrin
and distal hydrogen bond groups. Such model can orient exog-
enous water in a controlled fashion by hydrogen bonds. Their
studies provide a useful minimalist model for the heme water
channel assembly found in the cytochrome P450 enzymes.[11]
Biotrel’s group have recently developed a porphyrin system
with both intramolecular axial carboxylic acid and pyridine.[12]
Their studies suggested the hydrogen bond might be the driv-
ing force that causes coordinated oxygen close to the iron,
therefore to form unprecedented six-coordinate high-spin
iron(II) complex. In other model systems, hydrogen bonds
* Prof. Dr. C. Hu
Fax: +86-512-65880903
E-Mail: cjhu@suda.edu.cn
[a] Key Laboratory of Organic Synthesis of Jiangsu Province
College of Chemistry, Chemical Engineering and Materials Sci-
ence
Soochow University
Suzhou 215123, P.R. China
[b] State Key Lab & Coordination Chemistry Institute
Nanjing University
Nanjing 210093, P. R. China
Z. Anorg. Allg. Chem. 0000, ᭿,(᭿), 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1

Job/Unit: Z13136
/KAP1
Date: 06-05-13 10:50:42
Pages: 9
Y. Zhang, J. Jiang, C. Hu
ARTICLE
Scheme 1. Synthetic route to H3CNTTP and its iron complexes.
have also been shown to adjust the microenvironment around [Fe(CNTTP)]2 and [Fe(CNTTP)(N-MeIm)2] were measured
metal ions, and even change the electron configuration of by X-ray crystallography.
metal ion.[13]
In this paper, we have designed a ligand, 5-(8-carboxy-1-
naphthyl)-10,15,20-tritolyl-porphyrin (H3CNTTP), as shown
Molecular Structures
in Scheme 1. The 8-position substituent, carboxylate group, is
“hanging” over the porphyrin plane. Because of the rigid
framework, carboxylate oxygen could not coordinate directly
to the central iron atom in the same porphyrin, also leave some
spaces for axial ligands, such as water, imidazole etc., to coor-
dinate to central iron atom. We are interested in the interactions
between such carboxylate group and axial ligands. The two
iron species, [Fe(CNTTP)]2 and [Fe(CNTTP)(N-MeIm)2],
were also characterized by X-ray crystallography. The struc-
ture of [Fe(CNTTP)(N-MeIm)2] has revealed some interac-
tions between the carboxylate group and the imidazole ligand.
¯
The crystal structure of [Fe(CNTTP)]2 was solved in P1.
The ORTEP diagram of [Fe(CNTTP)]2 is presented in Fig-
ure 1. It is a dimeric structure formed by two symmetry-related
Results and Discussion
The iron complexes, [Fe(CNTTP)]2 and [Fe(CNTTP)-
(N-MeIm)2], were synthesized as shown in Scheme 1.
5-(8-Ethoxycarbonyl-1-naphthyl)-10,15,20-tritolyl-porphyrin
(H2ENTTP) and H3CNTTP were prepared according to our
previous method.[14,15] The resulting (H3CNTTP) was further
metalated according to the literature[16] and the formed iron(II)
complex is eventually converted into iron(III) species
[Fe(HCNTTP)Cl]. In the presence of OH–,
a dimer
[Fe(CNTTP)]2 was obtained. When [Fe(HCNTTP)Cl] was
treated with excess N-methylimidazole, a bis(imidazole) lig-
Figure 1. ORTEP view for [Fe(CNTTP)]2 at 50% probability thermal
ellipsoids. The hydrogen atoms and tolyl groups are omitted for clarity.
ated species, [Fe(CNTTP)(N-MeIm)2] was obtained. Both Symmetry operator a: –x + 2, –y + 2, –z + 1.
2
www.zaac.wiley-vch.de © 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Z. Anorg. Allg. Chem. 0000, 0–0

Job/Unit: Z13136
/KAP1
Date: 06-05-13 10:50:42
Pages: 9
Iron(III) Complexes of 5-(8-Carboxy-1-naphthyl)-10,15,20-tritolyl Porphyrin
iron(III) porphyrinates. In the porphyrin unit, there are three
tolyl groups and one naphthyl at meso positions. The carboxyl-
ate group at the 8-position of naphthyl is hanging over the
porphyrin plane. One of the carboxylate oxygen is coordinated
to iron in the symmetry-related unit. So the overall arrange-
ment for iron is square pyramidal. The average Fe–Np distance
is 2.060(12) Å, which is similar to those in five-coordinate
iron(III) porphyrinates.[17] Iron is not in the porphyrin plane,
but out of 24 atom plane with displacement 0.63 Å. The large
iron displacement and the long Fe–Np distance suggest
iron(III) is in the high-spin state. Related distances are listed
in Table 1. The Fe–O distance is 1.886(4) Å, which is similar
to those in carboxylate linked dimeric structures.[18] The
Fe···Fe distance in the dimer is 6.045 Å.
Table 1. Selected bond lengths /Å and angles /° for [Fe(CNTTP)]2 and
[Fe(CNTTP)(N-MeIm)2].
[Fe(CNTTP)]2
Figure 2. Formal diagram of the porphyrinato core of [Fe(CNTTP)]2.
Illustrated are the displacements of each atom from the mean plane of
the 24 atom in units of 0.01 Å. Positive values of displacement are
toward the carboxylate group.
Fe(1)–O(1a)
Fe(1)–N(1)
Fe(1)–N(2)
Fe(1)–N(3)
Fe(1)–N(4)
1.886(4)
2.052(5)
2.060(5)
2.052(5)
2.077(5)
C(1)–O(1)
C(1)–O(2)
O(1a)–Fe(1)–N(1)
O(1a)–Fe(1)–N(2)
O(1a)–Fe(1)–N(3)
O(1a)–Fe(1)–N(4)
1.307(7)
1.227(8)
105.87(19)
111.10(2)
103.94(19)
95.80(2)
reported by Barthel et al.[20] It suggests the [Fe(CNTTP)-
(N-MeIm)2] is a neutral species rather than an ionic compound.
The following NMR and EPR studies suggest the iron’s oxi-
dation state is +3. So the porphyrin ligand should be –3
charged, which means three protons of H3CNTTP (two from
NH and one from COOH group) were deprotonated during the
reaction. Obviously, the excess of the imidazole removes one
equivalent of HCl, and deprotonates the carboxylic acid.
C(M1)-C(10) 1.510(8)
C(1)–C(17) 1.520(8)
[Fe(CNTTP)(N-MeIm)2]
Fe(1)–N(1)
Fe(1)–N(2)
Fe(1)–N(3)
Fe(1)–N(4)
Fe(1)–N(5)
Fe(1)–N(7)
C(1)–O(1)
C(1)–O(2)
C(1)–C(17)
1.982(4)
1.997(3)
1.994(4)
2.001(3)
1.970(3)
1.998(3)
1.191(11)
1.259(10)
1.518(9)
N(5)–Fe(1)–N(1)
N(5)–Fe(1)–N(2)
N(5)–Fe(1)–N(3)
N(5)–Fe(1)–N(4)
N(7)–Fe(1)–N(1)
N(7)–Fe(1)–N(2)
N(7)–Fe(1)–N(3)
N(7)–Fe(1)–N(4)
N(5)–Fe(1)–N(7)
N(1)–Fe(1)–N(2)
N(1)–Fe(1)–N(3)
N(1)–Fe(1)–N(4)
N(2)–Fe(1)–N(3)
N(2)–Fe(1)–N(4)
N(3)–Fe(1)–N(4)
88.64(15)
92.07(14)
91.25(15)
87.59(14)
89.86(15)
89.34(14)
90.25(15)
91.00(14)
177.94(16)
89.60(15)
179.81(15)
90.42(15)
90.26(15)
179.66(15)
89.73(15)
C(M1)-C(10) 1.501(6)
C(2)···O(1)
C(2)···O(2)
3.35
3.35
Symmetry operator a: –x + 2, –y + 2, –z + 1
The displacement diagram in Figure 2 shows clearly that the
porphyrin core is nonplanar. It shows large displacements for
meso carbons with alternate sign, which is typical for the
ruffled core conformation.[19] Such ruffled conformation could
be due to the crowded dimeric structure. The closest nonbond-
ing distance between O(2) and C(M1) is 2.90 Å, which is
much smaller than the corresponding distance in H2ENTTP
(3.17 Å).[14] The repulsion interactions could be the driving
force to make C(M1) away from porphyrin plane to form
ruffled conformation.
Figure 3. ORTEP view for [Fe(CNTTP)(N-MeIm)2] at 50% prob-
ability thermal ellipsoids. The hydrogen atoms [except H(2)] and tolyl
groups are omitted for clarity.
The crystal structure of [Fe(CNTTP)(N-MeIm)2] is
shown in Figure 3. In order to verify the formula, we measured
In the structure of [Fe(CNTTP)(N-MeIm)2], the iron atom
molar conductivity on 1ϫ10–3 mol·L–1 solution of is six-coordinate and in the center of porphyrin plane with dis-
[Fe(CNTTP)(N-MeIm)2] and N(Bu)4Br in CH3CN. For placement 0.04 Å. The porphyrin core has slightly ruffling
[Fe(CNTTP)(N-MeIm)2], the molar conductivity is conformation with maxium displacements on meso carbon
37 S·cm2·mol–1, which is much smaller than 166 S·cm2·mol–1 atoms as shown in Figure 4. The average Fe–Np distance is
for N(Bu)4Br and also smaller than those 1,1-electrolytes 1.994(8) Å, such distance is similar to those six-coordinate
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
3

Job/Unit: Z13136
/KAP1
Date: 06-05-13 10:50:42
Pages: 9
Y. Zhang, J. Jiang, C. Hu
ARTICLE
low-spin iron(III) porphyrinates, which have effectively planar is towards the carboxylate group and nearly bisecting the
porphyrin core conformations.[21] Related distances and angles O–C–O angle. In this arrangement, the closest C···O distance
are also listed in Table 1.
is 3.35 Å. Such a distance is within the range for common
CH···O interactions.[28] It suggests the existence of CH···O in-
teractions between the carboxylate group and imidazole ligand.
But because we can not get accurate hydrogen positions from
X-ray data, it is hard to tell its strength. Such interactions are
common in biological systems,[8] and could contribute to stabi-
lize the orientation of this imidazole. On the other hand, the
parallel orientation of two imidazole ligands could be related
to the porphyrin core conformation. Patra et al. have recently
reported porphyrin nonplanarity may have some influence on
the stabilization of parallel axial orientations.[29] In our case,
the porphyrin core has slightly ruffling conformation, which
may contribute to the parallel axial orientation.
1H NMR Spectroscopy
1H NMR spectra were measured and are shown in Figure 5.
For H2ENTTP and H3CNTTP, the signals of eight protons are
located at around 8.6–8.8 ppm, which are similar to the corre-
sponding values for meso-5,10,15,20-tetraphenylporphyrin. So
they are assigned to pyrrole protons. The 2:1:1 ratio of pyrrole
protons is consistent with the low symmetry related to the 1:3
ratio of naphthyl to phenyl substituents on the meso-positions.
For H2ENTTP, there are two resonances at 0.48 and
–0.68 ppm, which are similar to those for 5-(8-ethoxycarbonyl-
1-naphthyl)-10,15,20-triphenyl-porphyrin.[4] So they are as-
signed to the ethyl protons, which are shifted upfield by 3.98
Figure 4. Formal diagram of the porphyrinato core of
[Fe(CNTTP)(N-MeIm)2]. Illustrated are the displacements of each
atom from the mean plane of 24 atom in units of 0.01 Å. Positive
values of displacement are toward the carboxylate group. The diagram
also shows the orientation of the imidazole ligands with respect to
the atoms of the porphyrin core. The location of the methyl group is
represented by the circle.
According to the nomenclature introduced by Walker,[22] and 2.12 ppm comparing with naphthalene-1-carboxylic acid
there are three types of low-spin iron(III) porphyrin centers: ethyl ester.[30] It suggests the ethyl group is located above the
type I, which have (dxy)2(dxz,dyz)3 electronic ground states porphyrin plane in solution, the shielding effect of the ring
with axial ligands aligned in perpendicular planes; type II, current causes such upfield shifts. When it is hydrolyzed, the
which also have (dxy)2(dxz,dyz)3 electronic ground states, but resonances of ethyl group disappeared, instead a signal at
with axial ligands aligned in parallel planes; and type III, δ = 10.35 ppm appeared, which is assigned to the COOH
which have (dxz,dyz)4(dxy)1 electronic ground states with axial proton.
ligands in any orientation. In [Fe(CNTTP)(N-MeIm)2], the rel-
For the paramagnetic FeIII species, the signals are broader
ative orientation between two imidazole planes is relative par- and expanded. For typical five-coordinate high-spin (tet-
allel with a dihedral angle 17.3°. Fe–NIm distances are 1.970(3) raphenyl-porphyrinato)iron(III) complex, the pyrrole protons
and 1.998(3) Å, which are also in the range of the correspond- signals are around 80 ppm.[31] In our case for both
ing distances observed in other bis(imidazole-ligated) iron(III) [Fe(HCNTTP)Cl] and [Fe(CNTTP)]2, the spectra show reso-
porphyrinates with unhindered imidazoles [1.975 and 1.965 Å nances in the far-downfield region at 79.49 or 78.91 ppm,
in Fe(TMP)(N-MeIm)2]ClO4,[23] 1.977 and 1.964 Å in which are assigned to the pyrrole protons.
[Fe(TPP)(HIm)2]Cl·CHCl3,[24] 1.975 and 1.987 Å in
[Fe(TPP)(4-MeHIm)2]Cl,[25]
1.974 and 1.995 Å
For [Fe(CNTTP)(N-MeIm)2] as a low-spin iron(III) por-
in phyrinates, the NMR spectrum is much different from the
[Fe(TPP)(N-MeIm)2]ClO4,[26] 1.970 and 1.982 Å in para- above high-spin species. The above mentioned three types of
[Fe(TMP)(5-MeHIm)2]ClO4[27]], where these iron(III) species low-spin iron(III) porphyrinates have distinguished NMR
have been confirmed as type II species with a relative parallel properties. For type I, NMR spectra show pyrrole-H reso-
orientation of the two imidazole planes. The above structural nances in the –10 to –20 ppm range. In comparison, type II
feature also suggests [Fe(CNTTP)(N-MeIm)2] is a type II spe- centers have NMR spectra including pyrrole-H resonances in
1
cies. H NMR and EPR studies have further confirmed such the –15 to –30 ppm region. Type III centers have NMR spectra
point. (vide infra)
including pyrrole-H resonances in the 0 to 10 ppm region.[22]
For such a structure, we are more interested in the influence In our case, the 1H NMR spectrum of [Fe(CNTTP)(N-MeIm)2]
of the carboxylate group on the coordination and orientation has shown four well resolved pyrrole-H resonances at –10.22,
of the imidazole ligands. The existence of two axial ligands –11.98, –22.29, and –25.01 ppm (Figure 5), which is very sim-
indicates the carboxylate is not bulky enough to block the sixth ilar to those signals of [(2,3-MoOL)(TTP)FeIII(N-MeIm)2]–
coordination site. On the carboxylate side, the imidazole plane (a type II species).[31,32] So their resonances are assigned to
4
www.zaac.wiley-vch.de
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 0000, 0–0

Job/Unit: Z13136
/KAP1
Date: 06-05-13 10:50:42
Pages: 9
Iron(III) Complexes of 5-(8-Carboxy-1-naphthyl)-10,15,20-tritolyl Porphyrin
shown typical rhombic spectrum with g1 = 1.67, g2 = 2.31,
g3 = 2.86. Some small bumps could be caused by some impuri-
ties. The solution EPR in CH2Cl2 was measured (see Support-
ing Information), it also shows the rhombic spectrum. But
there is an extra resonance at g = 6.20. It suggests that the
dissociation occurs in the solution, which leads to high-spin
iron(III) species. These g values for the rhombic spectrum are
similar to those for [Fe(TPP)(HIm)2]+ (g1 = 1.59, g2 = 2.32,
g3 = 2.84),[33] [Fe(TPP)(4-MeHIm)2]+ (g1 = 1.82, g2 = 2.24,
g3 = 2.60),[34] [Fe(TFPPCl8)(Im)2]ClO4 (g1 = 1.57, g2 = 2.30,
g3 = 2.88),[29] and para-[Fe(TMP)(5-MeHIm)2]ClO4 (g1
=
1.66, g2 = 2.38, g3 = 2.72).[27] Those complexes are all type II
species, it further confirms [Fe(CNTTP)(N-MeIm)2] is a type
II species.
Figure 6. X-band EPR spectrum of polycrystalline sample of
[Fe(CNTTP)(N-MeIm)2] at 77 K.
Conclusions
H3CNTTP and its iron complexes were synthesized and
characterized. The X-ray crystal structures of [Fe(CNTTP)]2
and [Fe(CNTTP)(N-MeIm)2] revealed that the carboxylate
group is “hanging” over the porphyrin plane. Such group can
not coordinate to iron in the same porphyrin, but can coordi-
nate to iron in symmetry-related porphyrin, which is the case
for [Fe(CNTTP)]2. When excess N-methylimidazole was used,
six-coordinate species, [Fe(CNTTP)(N-MeIm)2], was ob-
tained. In such structure, CH···O interactions between the carb-
oxylate group and imidazole play an important role to deter-
mine the orientation of imidazole plane. One the other hand,
the ruffling core conformation could contribute to the parallel
axial orientation of two imidazole ligands. All the X-ray crys-
tallography, 1H NMR, and EPR spectroscopy confirm that
1
Figure 5. H NMR spectra of (a) H2ENTTP in CDCl3, (b) H3CNTTP
in [D6]DMSO, (c) [Fe(HCNTTP)Cl] in CDCl3, (d) [Fe(CNTTP)]2 in
CDCl3, (e) [Fe(CNTTP)(N-MeIm)2] in CDCl3 at 293 K. X: signal from
impurity.
pyrrole protons. The experimental results from both the
structural features and NMR spectroscopic data confirm
[Fe(CNTTP)(N-MeIm)2] is a type II species.(vide supra)
EPR Study
The above mentioned three types of low-spin iron(III) por- [Fe(CNTTP)(N-MeIm)2] is a type II low-spin iron(III) por-
phyrinates have also distinguished EPR properties. Type I phyrinate.
centers are characterized by “large gmax” EPR spectra with
g Ͼ 3.3 in most cases; type II centers have well-resolved
Experimental Section
The 1H NMR spectra were recorded with a Bruker AVANCE 400 spec-
rhombic EPR spectra; type III centers have axial EPR spectra
with gЌ = 2.6 (or smaller) and gʈ = 0.9–1.95 (but with gʈ often
not resolved). As shown in Figure 6, in our case, the EPR spec-
trometer in the solvents indicated with tetramethylsilane (TMS) as the
trum of polycrystalline sample of [Fe(CNTTP)(N-MeIm)2] internal standard at 293 K. Chemical shifts are expressed in ppm rela-
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de 5

Job/Unit: Z13136
/KAP1
Date: 06-05-13 10:50:42
Pages: 9
Y. Zhang, J. Jiang, C. Hu
[Fe(HCNTTP)Cl]: To the mixture of anhydrous FeCl2 (1.74 g,
ARTICLE
tive to chloroform (δ = 7.26 ppm) or dimethyl sulfoxide (δ =
2.50 ppm). UV/Vis spectra were measured with a Shimadzu UV-3150 8.75 mmol) and H3CNTTP (0.3 g, 0.4 mmol) in anhydrous tetra-
spectrometer. FT-IR spectra were recorded with a Varian Scimitar 1000 hydrofuran (150 mL), 380 uL of pyridine was added. The mixture was
spectrometer. Mass spectra were taken with a Agilent 6220 Accurate- heated under reflux for overnight. It was filtered and the crude
Mass TOF LC/MS. EPR spectrum of polycrystalline sample of
[Fe(CNTTP)(N-MeIm)2] was obtained with a EMX 10/12 EPR spec-
product was further purified by silica gel chromatography
[CH2Cl2/EtOAc(2:1)]. Yield 0.29 g (86.4%). UV/Vis(CH2Cl2); λmax
trometer operating at X band at 77 K at Nanjing University. Molar (m–1·cm–1): 420 (7.29ϫ104), 515 (1.04ϫ104), 587 (2.71ϫ103), 702
conductivity was measured with a Mettler Toledo Conductivity Meter
(2.41ϫ103) nm. IR (KBr): ν˜ = 3427 (m), 3048 (w), 3020 (w), 2962
FE30 at 288 K. Methylene chloride was distilled over CaH2, and THF (m), 2918 (w), 2850 (w), 1736(m), 1695 (w), 1577 (w), 1496 (m),
was distilled over sodium. All other chemicals and solvents were of 1448 (w), 1404 (w), 1331 (m), 1261 (s), 1181 (m), 1108 (m), 1021
analytical grade available commercially and were used as received.
(w), 997 (w), 873 (w), 807 (s), 722 (m), 622 (m), 525 (m) cm–1.
C52H36ClFeN4O2: calcd. C 74.34; H 4.32; N 6.67%; found C 74.58;
H 4.52; N 6.59%.
H2ENTTP: The free-base porphyrin ligand 5-(8-ethoxycarbonyl-1-
naphthyl)-10,15,20-tritolyl porphyrin (H2ENTTP) were prepared ac-
cording to our previous method.[14] The reaction was carried out under
anaerobic condition. Acenaphthenequinone (1.26 g, 6.9 mmol), p-
methyl benzaldehyde (2.5 mL, 21 mmol) and pyrrole (1.9 mL,
28 mmol) were dissolved in a solution of ethanol in chloroform (7%,
500 mL). BF3·OEt2 (1.0 mL, 7.9 mmol) was added to the above solu-
tion and stirred for 1 h at room temperature, afterwards tetrachloro-1,4-
benzoquinone(6.81 g, 27.6 mmol) was added. After 2 h under reflux,
triethylamine (4.0 mL) was added, and the mixture was stirred for an-
other half hour. When it was cooled down to room temperature, it was
filtered by sintered glass funnel. The filtrate was rotoevaporated to
dryness. The black solid was further purified by column chromatog-
raphy (silica, CH2Cl2/petroleum ether = 1:1). The second purple band
was collected, and the solvents evaporated to dryness. Purple product
was obtained, yield 0.36 g (6.9%). 1H NMR (400 MHz. CDCl3;
Me4Si): δH = 8.92 (s, 4 H, pyrr-H), 8.85 (s, 2 H, pyrr-H), 8.67 (s, 2
H, pyrr-H), 8.30–8.07 (m, 9 H), 7.86 (t, J = 7.5 Hz, 1 H), 7.59 –7.54
(m, 7 H), 7.38 (d, J = 6.7 Hz, 1 H), 2.74 (s, 3 H, phenyl-CH3), 2.71
(s, 6 H, phenyl-CH3), 0.48 (s, 2 H, CH2CH3), –0.68 (t, J = 7.1 Hz, 3
H, CH2CH3), –2.56 (s, 2 H, NH) ppm. IR (KBr): ν˜ = 3437 (m), 3319
(m), 2920 (m), 2850 (m), 1724(s), 1630 (m), 1559 (m), 1506 (m), 1473
(m), 1401 (m), 1347 (m), 1275 (m), 1195 (s), 1146 (m), 1105 (m),
1024 (m), 972 (s), 800 (s), 735 (s), 522 (w) cm–1. UV/Vis (CH2Cl2):
λmax, (m–1·cm–1): 422 (6.58ϫ105), 519 (2.74ϫ104), 554 (1.46ϫ104),
593 (1.04ϫ104), 650 (7.78ϫ103) nm. LC-ESI-MS: m/z calcd. for
C54H42N4O2 778.33 found 779.33 [M + H]+. C54H42N4O2·0.7CH2Cl2:
calcd. C 78.36; H 5.22; N 6.68%; found C 78.28; H 5.40; N 6.38%.
[Fe(CNTTP)]2: [Fe(HCNTTP)Cl] (0.30 g, 0.36 mmol) was dissolved
in CH2Cl2 (100 mL), further washed by 2 mol·L–1 NaOH for 4–6
times. The organic layer was collected, dried with sodium sulfate, and
concentrated under reduced pressure. The residue was purified on sil-
ica gel with CH2Cl2/ dimethylformamide (95:5) to give the final com-
pound (0.19 g, yield 66%). IR (KBr): ν˜ = 3338 (m), 3048 (w), 3020
(m), 2962 (m), 2919 (m), 2858 (w), 1811 (w), 1701 (m), 1649 (m),
1609 (w), 1529 (w), 1496 (m), 1448 (w), 1331 (m), 1261 (m), 1204
(m), 1094 (m), 1000 (s), 799 (s), 720 (m), 559 (m), 511 (m) cm–1. UV/
Vis (CH2Cl2); λmax, (m–1·cm–1): 421 (2.28ϫ105), 508 (2.05ϫ104),
571 (9.74ϫ103), 658 (6.31ϫ103) nm. C105H74Fe2N8O4·DMF: calcd.
C 76.47; H 4.62; N 7.50%; found C, 76.12; H 4.24; N 7.48%. X-ray
quality crystals were obtained by liquid diffusion of n-hexane into the
CH2Cl2 solution in 8 mm diameter glass tubes.
[Fe(CNTTP)(N-MeIm)2]: In
a 10 mL flask, [Fe(HCNTTP)Cl]
(100 mg, 0.12 mmol) was dissolved in methylene dichloride (5 mL).
N-methylimidazole (98 mg, 1.2 mmol) was added to it, and the mixture
was stirred for 30 min at room temperature. The resulting solution
was concentrated and dissolved in chlorobenzene solution, filtered to
remove any solid residue and carefully layered with n-hexane. Upon
standing for 7–8 d, dark red crystalline solid was formed, which was
collected by filtration, washed with n-hexane, and dried under vacuum.
Yield: 63 mg (55%). UV/Vis (CH2Cl2); λmax
,
(m–1·cm–1): 422
(1.06ϫ105), 553 (6.84ϫ103), 588 (4.32ϫ103), 648 (1.45ϫ103), 700
(7.57ϫ102) nm. C60H47FeN8O2·0.5C6H5Cl: calcd. C 73.88; H 4.87;
N 10.94%; found C 73.45; H 5.04; N 10.55%. IR (KBr): ν˜ = 3406
(m), 3127 (m), 3021 (m), 2918 (m), 2849 (m), 1806 (m), 1686 (m),
1630 (w), 1581 (m), 1508 (m), 1450 (m), 1420 (m), 1340 (m), 1284
H3CNTTP: H2ENTTP (0.30 g, 0.39 mmol) was dissolved in glacial
acetic acid (16.8 mL), deionized water (6 mL) and concentrated sulfu- (m), 1237 (m), 1205 (m), 1181 (m), 1096 (s), 1002 (s), 959 (m), 917
ric acid (6 mL) were added. The bright green solution was stirred at
388 K for 3 d. Afterwards, CHCl3 (50 mL) was added to the mixture,
(w), 799 (s), 714 (m), 662 (m), 615 (m), 526 (m) cm–1.
and the solution was washed with water. The organic layer was col- X-ray Crystallography: X-ray data collections were made with a Ri-
lected, dried with magnesium sulfate, and concentrated under reduced gaku Mercury CCD X-ray diffractometer by using graphite monochro-
pressure. The residue was purified on silica gel with dichloromethane/ mated Mo-Kα (λ = 0.071073 nm) at 293(2) K. Both structures were
1
methanol (98:2) to give light purple solid. Yield 0.27 g (93.4%). H solved by direct methods and refined on F2 using full-matrix least-
NMR (400 MHz, [D6]DMSO) : δH = 10.35 (s, 1 H, COOH), 8.80 (s,
4 H, pyrr-H), 8.68 (s, 2 H, pyrr-H), 8.53 (s, 2 H, pyrr-H), 8.43 (d, J =
squares methods with SHELXTL version 97.[35] All non-hydrogen
atoms were refined anisotropically. All hydrogen atoms were idealized
6.5 Hz, 1 H), 8.36 (d, J = 7.6 Hz, 1 H), 8.29 (d, J = 0.8 Hz, 1 H), with the standard SHELXL-97 idealization methods. Complete crystal-
8.19–7.84 (m, 7 H), 7.73–7.43 (m, 7 H), 7.39 (s, 1 H), 2.60 (s, 9 H, lographic details, atomic coordinates, anisotropic thermal parameters,
phenyl-CH3), –2.72 (s, 2 H, NH) ppm. IR (KBr): ν˜ = 3429 (m), 3317 and hydrogen atom coordinates are given in the cif file. Both structures
(m), 3124 (w), 3044 (w), 3021 (w), 2921 (m), 2849 (w), 1709 (s), have badly disordered solvate molecules. SQUEEZE[36] was used to
1558 (m), 1507 (m), 1472 (m), 1346 (m), 1298 (m), 1223 (m), 1183
(m), 1151 (m), 1022 (m), 971 (m), 800 (s), 733 (s), 523 (m) cm–1. UV/
Vis (CH2Cl2); λmax, (m–1·cm–1): 422 (6.55ϫ105), 519 (2.54ϫ104),
555 (1.30ϫ104), 593 (8.64ϫ103), 650 (6.28ϫ103) nm . LC-ESI-MS:
model disordered solvate molecules. The residue electron count in the
interporphyrins voids amounted to 24 electrons per unit-cell for
[Fe(CNTTP)]2 (corresponding roughly to 0.6 molecule of CH2Cl2 per
porphyrin), 116 electrons per unit-cell for [Fe(CNTTP)(N-MeIm)2]
m/z calcd. for C52H38N4O2 750.30; found 751.30 [M
+
H]+. (corresponding to 0.5 molecule of chlorobenzene per porphyrin) A
C52H38N4O2·0.6CH2Cl2: calcd. C 78.79; H 4.93; N 6.99%; found C
78.36; H 4.98; N 7.15%.
summary of the key crystallographic information of the complexes are
given in Table 2.
6
www.zaac.wiley-vch.de
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 0000, 0–0

Job/Unit: Z13136
/KAP1
Date: 06-05-13 10:50:42
Pages: 9
Iron(III) Complexes of 5-(8-Carboxy-1-naphthyl)-10,15,20-tritolyl Porphyrin
[9] a) R. A. Decreau, J. P. Collman, A. Hosseini, Chem. Soc. Rev.
Table 2. Crystallographic data for [Fe(CNTTP)]2 and [Fe(CNTTP)(N-
2010, 39, 1291–1301; b) J. P. Collman, S. Ghosh, Inorg. Chem.
2010, 49, 5798–5810; c) J. P. Collman, R. A. Decréau, A. Dey,
Y. Yang, Proc. Natl. Acad. Sci. USA 2009, 106, 4101–4105.
[10] S. Ferguson-Miller, G. T. Babcock, Chem. Rev. 1996, 96, 2889–
2907.
MeIm)2].
[Fe(CNTTP)]2
[Fe(CNTTP)(N-MeIm)2]
Empirical formula
Formula weight /g·mol–1 1607.38
T /K
λ /Å
Space group
a /Å
b /Å
c /Å
α /°
β /°
C104H70Fe2N8O4 C60H47FeN8O2
967.91
293(2)
0.71073
P21/c
16.890(3)
15.524(3)
24.498(8)
90
124.35(2)
90
5303(2)
4
[11] Y. Yeh, C. J. Chang, D. G. Nocera, J. Am. Chem. Soc. 2001, 123,
1513–1514.
293(2)
0.71073
[12] I. Hijazi, T. Roisnel, P. Even-Hernandez, E. Furet, J.-F. Halet, O.
Cador, B. Boitrel, J. Am. Chem. Soc. 2010, 132, 10652–10653.
[13] a) G. E. Wuenschell, C. Tetreau, D. Lavalette, C. A. Reed, J. Am.
Chem. Soc. 1992, 114, 3346–3355; b) N. Suzuki, T. Higuchi, Y.
Urano, K. Kikuchi, H. Uekusa, Y. Ohashi, T. Uchida, T. Kita-
gawa, T. Nagano, J. Am. Chem. Soc. 1999, 121, 11571–11572; c)
C. Hu, B. C. Noll, P. M. Piccoli, A. J. Schultz, C. E. Schulz, W. R.
Scheidt, J. Am. Chem. Soc. 2008, 130, 3127–3136.
[14] J. Yang, J. Jiang, W. Fang, X. Kai, C. Hu, Y. Yang, J. Porphyr.Ph-
thal. 2011, 15, 197–201.
[15] B. Ma, J. Jiang, C. Hu, Z. Anorg. Allg. Chem. 2013, published
online, DOI: 10.1002/zaac.201200558.
[16] A. D. Adler, F. R. Longo, F. Kampus, J. Kim, J. Inorg. Nucl.
Chem. 1970, 32, 2443–2445.
¯
P1
12.688(3)
12.854(3)
12.861(3)
86.48(3)
82.67(3)
82.51(3)
2060.5(8)
1
γ /°
V /Å3
Z
ρ /g·cm–3
F(000)
μ /mm–1
1.295
834
0.413
1.212
2020
0.334
9292 / 0 / 645
Data / restraints / param- 7158 / 0 / 536
eters
[17] a) W. R. Scheidt, M. G. Finnegan, Acta Crystallogr., Sect. C 1989,
45, 1214–1216; b) T. Ikeue, Y. Ohgo, A. Uchida, M. Nakamura,
H. Fujii, M. Yokoyama, Inorg. Chem. 1999, 38, 1276–1291; c)
R. A. Ghiladi, R. M. Kretzer, I. Guzei, A. L. Rheingold, Y. M.
Neuhold, K. R. Hatwell, A. D. Zuberbuhler, K. D. Karlin, Inorg.
Chem. 2001, 40, 5754–5767; d) B. Song, K. Park, B. Yu, J. Ko-
rean Chem. Soc. 1997, 41, 495–501; e) M. O. Senge, Acta Crys-
tallogr., Sect. E 2005, 61, m399–m400.
[18] a) S. Pagola, P. W. Stephens, D. S. Bohle, A. D. Kosar, S. K.
Madsen, Nature 2000, 404, 307–310; b) D. S. Bohle, E. L. Dodd,
A. J. Kosar, L. Sharma, P. W. Stephens, L. Surez, D. Tazoo, An-
gew. Chem. Int. Ed. 2011, 50, 6151–6154; c) T. Straasø, S. Kap-
ishnikov, K. Kato, M. Takata, J. Als-Nielsen, L. Leiserowitz,
Cryst. Growth Des. 2011, 11, 3342–3350.
GOF
1.097
1.037
R1 [I Ͼ 2σ(I)]a)
wR2 [I Ͼ 2σ(I)]a)
R1 (all data)a)
wR2 (all data)a)
Largest diff. peak and
hole /e·Å–3
0.0812
0.2494
0.1160
0.2692
0.0781,
0.2154
0.1205
0.2420
0.917 and –0.461 0.477 and –0.303
2
2
2 3
a) w = 1/[σ2 (Fo )+(aP)2+bP], where P = (Fo + 2Fc ) .
Crystallographic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallographic
Data Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies
of the data can be obtained free of charge on quoting the depository
numbers CCDC-926708 and CCDC-926709. (Fax: +44-1223-336-033;
E-Mail: deposit@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.uk)
[19] W. R. Scheidt, Y. J. Lee, Struct. Bonding (Berlin) 1987, 64, 1–70.
[20] J. Barthel, L. Iberl, J. Rossmaier, H. J. Gores, B. Kaukal, J. Solu-
tion Chem. 1990, 19, 321–337.
[21] W. R. Scheidt, in: The Porphyrin Handbook (Eds.: K. Kadish, K.
Smith, R. Guilard), Academic Press, New York, 2000, vol. 3, ch.
16.
[22] F. A. Walker, Coord. Chem. Rev. 1999, 185–186, 471–534.
[23] M. K. Safo, G. P. Gupta, F. A. Walker, W. R. Scheidt, J. Am.
Chem. Soc. 1991, 113, 5497–5510.
Acknowledgements
This work was supported by the National Natural Science Foundation
of China (No. 20971093 and 21271133) and the Priority Academic
Program Development of Jiangsu Higher Education Institutions.
[24] W. R. Scheidt, S. R. Osvath, Y. J. Lee, J. Am. Chem. Soc. 1987,
109, 1958–1963.
[25] J. Silver, P. J. Marsh, M. C. R. Symons, D. A. Svistunenko, C. S.
Frampton, G. R. Fern, Inorg. Chem. 2000, 39, 2874–2881.
[26] T. Higgins, M. K. Safo, W. R. Scheidt, Inorg. Chim. Acta 1990,
178, 261–267.
[27] O. Q. Munro, J. A. Serth-Guzzo, I. Turowska-Tyrk, K. Mohanrao,
T. K. Shokhireva, F. A. Walker, P. G. Debrunner, W. R. Scheidt,
J. Am. Chem. Soc. 1999, 121, 11144–11155.
[28] a) R. Taylor, O. Kennard, J. Am. Chem. Soc. 1982, 104, 5063–
5070; b) B. P. Klaholz, D. Moras, Structure 2002, 10, 1197–1204;
c) R. Vargas, J. Garza, D. A. Dixon, B. Hay, J. Am. Chem. Soc.
2000, 122, 4750–4755.
[29] R. Patra, D. Sahoo, S. Dey, D. Sil, S. P. Rath, Inorg. Chem. 2012,
51, 11294–11305.
References
[1] E. A. Meyer, R. K. Castellano, F. Diederich, Angew. Chem. Int.
Ed. 2003, 42, 1210–1250.
[2] J. Vojtechovsky, K. Chu, J. Berendzen, R. M. Sweet, I. Schlicht-
ing, Biophys. J. 1999, 77, 2153–2174.
[3] G. I. Berglund, G. H. Carlsson, A. T. Smith, H. Szöke, A. Hen-
riksen, J. Hajdu, Nature 2002, 417, 463–468.
[4] M. Gajhede, D. J. Schuller, A. Henriksen, A. T. Smith, T. L.
Poulos, Nat. Struct. Biol. 1997, 4, 1032–1038.
[5] R. Bhattacharyya, U. Samanta, P. Chakrabarti, Protein Eng. 2002,
15, 91–100.
[30] R. Shang, Y. Fu, J. B. Li, S. L. Zhang, Q. X. Guo, L. Liu, J. Am.
Chem. Soc. 2009, 131, 5738–5739.
[31] F. A. Walker in The Porphyrin Handbook (Eds.: K. Kadish, K.
Smith, R. Guilard), Academic Press, New York, 2000, vol. 5, ch.
36.
[6] N. Kannan, S. Vishveshwara, Protein Eng. 2000, 13, 753–761.
[7] F. A. Quiocho, G. Hu, P. D. Gershon, Curr. Opin. Struct. Biol.
2000, 10, 78–86.
[8] a) V. Shanthi, R. Sethumadhavan, Int. J. Chem. Tech. Res. 2011,
3, 348–356; b) M. Brandl, K. Lindauer, M. Meyer, J. Sühnel,
Theor. Chem. Acc. 1999, 101, 103–113; c) Y. Mandel-Gutfreund,
H. Margalit, R. L. Jernigan, V. B. Zhurkin, J. Mol. Biol. 1998,
277, 1129–1140; d) Y. Gu, T. Kar, S. Scheiner, J. Am. Chem. Soc.
1999, 121, 9411–9422.
[32] P. Basu, N. V. Shokhirev, J. H. Enemark, R. A. Walker, J. Am.
Chem. Soc. 1995, 117, 9042–9055.
[33] F. A. Walker, B. H. Huynh, W. R. Scheidt, S. R. Osvath, J. Am.
Chem. Soc. 1986, 108, 5288–5297.
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
7

Job/Unit: Z13136
/KAP1
Date: 06-05-13 10:50:42
Pages: 9
Y. Zhang, J. Jiang, C. Hu
[36] A. L. Spek, J. Appl. Crystallogr. 2003, 36, 7–13.
Received: March 2, 2013
ARTICLE
[34] R. Quinn, C. E. Strouse, J. S. Valentine, Inorg. Chem. 1983, 22,
3934–3940.
[35] G. M. Sheldrick, SHELXL-97, Program for Crystal Structure Re-
finement, University of Göttingen, Germany, 1997.
Published Online: ᭿
8
www.zaac.wiley-vch.de
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 0000, 0–0

Job/Unit: Z13136
/KAP1
Date: 06-05-13 10:50:42
Pages: 9
Iron(III) Complexes of 5-(8-Carboxy-1-naphthyl)-10,15,20-tritolyl Porphyrin
Y. Zhang, J. Jiang, C. Hu* ............................................... 1–9
Synthesis and Characterization of Iron(III) Complexes of
5-(8-Carboxy-1-naphthyl)-10,15,20-tritolyl Porphyrin
Z. Anorg. Allg. Chem. 0000, 0–0
© 0000 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
9