Synthesis and structures of cobalt(II) complexes of meso-tetraphenyloctaphyrin(1.0.1.0.1.0.1.0)s

Article abstract of DOI:10.1016/j.jorganchem.2006.04.045

Some meso-tetraphenyloctaphyrin(1.0.1.0.1.0.1.0)s and their Co(II) complexes were prepared and characterized on the basis of the ¹H NMR spectra and X-ray crystallography. These octaphyrins have a figure eight structure. The methyl and methylene

Full text of DOI:10.1016/j.jorganchem.2006.04.045

Journal of Organometallic Chemistry 692 (2007) 166–174
www.elsevier.com/locate/jorganchem
Synthesis and structures of cobalt(II) complexes
of meso-tetraphenyloctaphyrin(1.0.1.0.1.0.1.0)s
*
Jun-ichiro Setsune , Megumi Mori, Toshifumi Okawa, Satoshi Maeda, Juha M. Lintuluoto
Department of Chemistry, Faculty of Science, and Graduate School of Science and Technology, Kobe University, Nada-ku, Kobe 657-8501, Japan
Received 1 March 2006; received in revised form 5 April 2006; accepted 7 April 2006
Available online 30 August 2006
Abstract
Some meso-tetraphenyloctaphyrin(1.0.1.0.1.0.1.0)s and their Co(II) complexes were prepared and characterized on the basis of the 1H
NMR spectra and X-ray crystallography. These octaphyrins have a figure eight structure. The methyl and methylene protons directly
1
bound to the bipyrrole b-position at the crossing point of the figure eight loop were very close to Co(II) and showed their H NMR
resonances in the range of 30–300 ppm. The insertion of Co(II) into the octaphyrin with mixed 2,20-bipyrrole units of different substi-
tution pattern induced transposition of the sterically more congested 2,20-bipyrrole unit from the crossing point of the figure eight loop to
the periphery.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Cobalt complex; Porphyrinoid; Octaphyrin
1. Introduction
substituents at the 3,30-position is preferable. In view of
the efficiency in the cyclization reaction we planned to pre-
pare octaphyrin(1.0.1.0.1.0.1.0) containing mixed bipyrrole
units. Selective syntheses of porphyrinoids with an alter-
nate ABAB arrangement of two different building blocks
are problematic especially in the case of meso-aryl type por-
phyrinoids, because the acid catalyzed reaction conditions
generally used for the cyclization cause scrambling of the
two building blocks [10]. We describe in this paper the syn-
thesis of meso-tetraphenyloctaphyrin(1.0.1.0.1.0.1.0) with-
out substituents at the 3,30-position of the 2,20-bipyrrole
units by using bis(azafulvene) under neutral conditions
[3a,3c,11]. It is of interest to see how the variation of the
alkyl substituents at the pyrrole b-positions influences the
structure not only of the octaphyrin(1.0.1.0.1.0.1.0) free
base but also of the corresponding metal complexes.
Whereas the electrochemical properties of Co(II) octaphy-
rins have been studied by Vogel and coworkers [9], their
structures and spectroscopic properties have not been well
understood. Thus, we have decided to investigate
the Co(II) complexes of meso-tetraphenyloctaphy-
rin(1.0.1.0.1.0.1.0)s in this work.
A number of reports on the expanded porphyrins have
been appearing and their properties are discussed from
the viewpoints of photochemistry, supramolecular chemis-
try, and coordination chemistry [1,2]. We have recently
developed efficient synthetic methods for meso-tetraaryloc-
taphyrin(1.0.1.0.1.0.1.0)s [3]. Octaphyrin(1.0.1.0.1.0.1.0) is
composed of four parts of 2,20-bipyrrole linked by four
meso-carbons. Although bulky substituents at the 3,30-
position of 2,20-bipyrrole are favored for the efficient cycli-
zation reaction to take place [3a], they are expected to
make steric hindrance in the metal insertion and the axial
coordination of the metal complexes of octaphyrin. Metal
complexes of octaphyrins have been drawing great atten-
tion due to their unique stereochemical and electrochemical
features [4–9]. In order to prepare octaphyrins suitable for
studying coordination chemistry, 2,20-bipyrrole without
*
Corresponding author. Fax: +81 78 803 5770.
E-mail address: setsunej@kobe-u.ac.jp (J.-i. Setsune).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.04.045

J.-i. Setsune et al. / Journal of Organometallic Chemistry 692 (2007) 166–174
167
2. Results and discussion
obtained similarly in 28% yield (see Scheme 1). Since bipyr-
role is an electron donor and bis(azafulvene) is an electron
acceptor in this addition reaction, the combination of 1c
and 3a should be better than the reverse combination of
2,20-bipyrrole 1a and bis(azafulvene) derived from 1c. Tet-
raalkylated bipyrrole 1c is more reactive as a donor than
the dialkylated bipyrrole 1a.
2.1. Synthesis and structures of octaphyrin(1.0.1.0.1.0.1.0)s
Vogel and coworkers reported that octaphyrin-
(1.0.1.0.1.0.1.0) was prepared by MacDonald [2+2]-type
condensation reaction of bipyrrole dialdehyde with bipyr-
role dicarboxylic acid or a-free bipyrrole under acidic con-
ditions [2c,4]. We have previously reported that the
addition reaction of a-free bipyrrole and bis(azafulvene)
under neutral conditions gives octaphyrin as a principal
product along with larger cyclopolypyrroles after oxidative
work-up [3a,11]. This is a versatile synthetic method for
meso-tetraaryloctaphyrin(1.0.1.0.1.0.1.0)s. 4,40-Dipropyl-
2,20-bipyrrole 1a was converted to the dialdehyde by Vils-
meier reaction and then to 5,50-bis(phenylhydroxy-
methyl)-2,20-bipyrroles 2a by using phenyllithium. The
bipyrrole dicarbinol 2a was then reacted with di-t-butyl
dicarbonate (Boc2O) in the presence of N,N-dimethylami-
nopyridine (DMAP) to give 82% yield of bis(azafulvene)
3a. Bis(azafulvene) 3b was prepared from 4,40-diethyl-
3,30-dimethyl-2,20-bipyrrole 1b in 60% total yield by way
of the corresponding bipyrrole dicarbinol 2b. The reaction
of 1b and 3b under neutral conditions afforded
2,7,11,16,20,25,29,34-octaethyl-3,6,12,15,21,24,30,33-octa-
methyl-9,18,27, 36-meso-tetraphenyloctaphyrin(1.0.1.0.1.0.1.0)
4b in 39% yield after oxidation with 2,3-dichloro-5,6-di-
cyanobenzoquinone (DDQ) (see Scheme 1). This reaction
did not afford hexapyrrolic macrocycle called rosarin which
was synthesized by the acid catalyzed condensation of 1b with
benzaldehyde in 70% yield [2a]. When bis(azafulvene) 3a was
allowed to react with 3,30-di-iso-butyl-4,40-dimethyl-2,20-
bipyrrole [11] 1c at room temperature for 24 h, 2,7,20,25-tetra-
propyl-11,16,29,34-tetramethyl-12,15,30,33-tetra-iso-butyl-9,
18,27,36-meso-tetraphenyloctaphyrin(1.0.1.0.1.0.1.0) 4a was
X-ray crystallography of 4a showed a figure eight type
structure previously reported by Vogel and coworkers for
2,3,6,7,11,12,15,16,20,21,24,25,29,30,33,34-hexadecaethyl-
octaphyrin(1.0.1.0.1.0.1.0) 4 where two bipyrrole units in a
trans N–Ca–Ca–N conformation are at the crossing point
of the figure eight loop and two bipyrrole units in a cis
N–Ca–Ca–N conformation are at the periphery [2c]. The
iso-butyl-substituted bipyrrole is positioned at the crossing
point of the figure eight loop of 4a, probably because the
steric constraint between the bulky 3,30-di-iso-butyl groups
renders the bipyrrole conformation trans. Table 1 shows
that the N–Ca–Ca–N torsion angles in the cis-4,40-dipro-
pyl-2,20-bipyrrole units of 4a (12.0ꢁ and 1.9ꢁ) are smaller
than those in the cis-3,30,4,40-tetraethyl-2,20-bipyrrole units
of 4 (34.8ꢁ and 34.0ꢁ) and the N–Ca–Ca–N torsion angles
in the trans-3,30-di-iso-butyl-4,40-dimethyl-2,20-bipyrrole
units of 4a (162.8ꢁ and 164.1ꢁ) are larger than those
in the trans-3,30,4,40-tetraethyl-2,20-bipyrrole units of 4
Table 1
Torsion angles (ꢁ) of the bipyrrole units (N–Ca–Ca–N) and of the
dipyrrylmethene units (Ca–Cmeso–Ca–N and N–Ca–Cmeso–Ca) for 4a and
4a
4a
4
N–Ca–Ca–N
12.0 162.8
1.9 164.1 34.8 151.8 34.0 150.8
Ca–Cmeso–Ca–N 15.3
N–Ca–Cmeso–Ca 26.2
12.5 14.3
15.0 12.5
13.0
13.7
7.5
1.8
3.9
6.4
4.0
5.8
1.8
6.8
a
The data of 4 were taken from Ref. [2c].
Ph
Ph
24 h
N
HN
HN
N
DDQ
+
N
N
N
NH
NH
N
CH2Cl2 CH2Cl2
NH HN
Ph
Ph
Ph
Ph
1b
3b
4b (Y = 39%)
Ph
Ph
24 h
N
HN
N
HN
N
N
DDQ
+
N
N
NH
NH
CH2Cl2 CH2Cl2
NH HN
Ph
Ph
Ph
Ph
1c
3a
Scheme 1. Synthesis of octaphyrin(1.0.1.0.1.0.1.0) 4a and 4b.
4a (Y = 28%)

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J.-i. Setsune et al. / Journal of Organometallic Chemistry 692 (2007) 166–174
(151.8ꢁ and 150.8ꢁ). This leads to the rectangle shaped cav-
ity for 4a in contrast to the rhombus shape for 4 as shown
in Fig. 1. Table 1 also summarizes the torsion angles Ca–
for the iso-butyl group strongly indicates that the figure
eight conformation with the 3,30-di-iso-butyl-4,40-
dimethyl-2,20-bipyrrole units at the crossing point of the
figure eight loop is predominant in solution and that the
iso-butyl group comes closer to the propyl-substituted
bipyrrole as temperature goes down probably by rotating
around the C(butyl)–C(pyrrole-b) bond.
Cmeso–Ca–N and N–Ca–Cmeso–Ca which are diagnostic of
the planarity of the dipyrrylmethene units. While the pla-
narity of the dipyrrylmethene units is kept to the sacrifice
of the planarity of the bipyrrole units in the case of 4,
the planarity of the bipyrrole units are kept to the sacrifice
of the planarity of the dipyrrylmethene units in the case of
4a. The iso-butyl groups are directed inwards the molecular
cavity and the methine proton of the iso-butyl group is
close to the pyrrole nitrogen of the propyl-substituted
2.2. Co(II) complexes of octaphyrin(1.0.1.0.1.0.1.0)s
Mononuclear Co(II) complexes of meso-tetraphenyloc-
taphyrin(1.0.1.0.1.0.1.0)s were readily prepared when a
methanol solution of Co(II) acetate was reacted with a
˚
bipyrrole with an estimated distance of 2.77 A.
The 2D ROESY NMR spectrum of 4a at 20 ꢁC in tolu-
ene-d8 showed an intense correlation between the NH sig-
nal at 14.92 ppm and one of the two methyl signals of
the iso-butyl group at 1.01 ppm (see Supplementary mate-
rial). This NOE effect would be impossible to observe if
the iso-butyl groups were at the periphery of the figure
eight loop in solution. Variable temperature 1H NMR
spectra of 4a between +80 ꢁC and ꢀ60 ꢁC in toluene-d8
showed only one set of signals, which means that a single
conformational isomer is present or the interconversion
between some conformational isomers are very fast on
the NMR time scale even at ꢀ60 ꢁC. While the chemical
shifts of the propyl protons and the b-pyrrole proton are
only slightly affected by less than 0.05 ppm in the whole
temperature range, signals due to the iso-butyl group
underwent remarkable chemical shift changes with decreas-
ing temperature from +80 ꢁC to ꢀ60 ꢁC as shown in Fig. 2.
Two methyl doublets, a methine multiplet (Hc), and one of
the diastereotopic methylene multiplets (Ha) were shifted to
the higher frequency region by 0.58, 1.05, 1.54, and
0.66 ppm, respectively, while the other methylene proton
signal (Hb) moved to the lower frequency region by
0.73 ppm. On the other hand, the methyl singlet due to
the b-pyrrole position was not sensitive to temperature
with the total chemical shift change less than 0.1 ppm.
The remarkable temperature dependency specifically found
Fig. 2. Variable temperature 1H NMR spectra in the region of the iso-
butyl-CH2 (Ha and Hb) and the iso-butyl-CH (Hc) of 4a in toluene-d8 (left)
and a plot of the proton chemical shifts due to the 4-iso-butyl-3-
methylpyrrole moiety with temperature (right). open and filled circles: iso-
butyl-Me, cross: pyrrole-b-Me, open and filled squares: iso-butyl-CH2,
plus: iso-butyl-CH.
Fig. 1. A 50% level Ortep drawing of 4a (left); a side view of 4a without peripheral substituents (middle) in comparison with that of 4 (right).

J.-i. Setsune et al. / Journal of Organometallic Chemistry 692 (2007) 166–174
169
CHCl3 solution of octaphyrin. The monocobalt(II) com-
100
80
60
40
20
0
4b
plexes 4a-Co, 4b-Co, 4c-Co, and 4d-Co were obtained in
57%, 66%, 59%, and 45% yield from 4a, 4b, 2,7,11,16,-
20,25,29,34-octamethyl-3,6,12,15,21,24,30,33-octa-iso-butyl-
9,18,27,36-meso-tetraphenyloctaphyrin(1.0.1.0.1.0.1.0) 4c,
and 2,3,6,7,11,12,15,16,20,21,24,25,29,30,33,34-hexadeca-
ethyl-9,18,27,36-meso-tetraphenyloctaphyrin(1.0.1.0.1.0.1.0)
4d [3b], respectively (see Scheme 2). The insertion of the sec-
ond Co(II) required temperature more than 120 ꢁC in the
reaction of 4b and 4d with Co(II) acetylacetonate in phenol
and the dinuclear complexes, 4b-Co2 and 4d-Co2, were
obtained in 28% and 33% yield, respectively.
4bCo
4b-Co2
400
500
600
700
800
Wavelength / nm
The absorption band of the free base 4b at 578 nm
underwent red shift to 588 nm for the monocobalt complex
4b-Co and to 597 nm for the dicobalt complex 4b-Co2 as
depicted in Fig. 3. The 1H NMR spectrum of 4b-Co2
showed 13 signals in the 75 ppm total range (see Fig. 4)
and they were unambiguously assigned as summarized in
Fig. 3. UV–Vis spectra of 4b, 4b-Co, and 4b-Co2 in CH2Cl2.
1
high frequency shift. The H NMR signals of 4b-Co were
assigned on the basis of the 1H–1H COSY experiment
and the chemical shifts of the corresponding protons deter-
mined for 4b-Co2. The signal at ꢀ64.4 ppm due to the pyr-
role b-methyl protons close to Co(II) is by 13.4 ppm lower
frequency than the corresponding signal of 4b-Co2. There-
fore, the effect of Co(II) bound at the pyrrole nitrogen on
the b-methyl protons of the same pyrrole can be estimated
as 13.4 ppm to the high frequency region. A signal at
43.9 ppm of 4b-Co disappeared by adding a drop of D2O
and thus was associated with the NH proton of the mon-
1
Table 2 with the aid of H–1H COSY NMR experiment
(see Fig. 5). The signal at ꢀ51.0 ppm of 4b-Co2 is associ-
ated with the pyrrole b-methyl protons in the trans-bipyr-
role unit at the crossing point of the figure eight loop,
because these methyl protons are subject to very large dipo-
lar shift by Co(II) in the close proximity. The signal at
23.8 ppm is associated with the pyrrole b-methyl protons
in the cis-bipyrrole unit at the periphery and the contact
shift caused by Co(II) should be mainly responsible for this
Ph
Ph
R4R4
R4
R4
R3
R3
N
R3
R3
R3
R3
Co(OAc)2
N
N
HN
Co
CHCl3 - MeOH
Ph
Ph
N
N
NH
N
R
R4
4
R4
R4
R3
R3
R3
R3
R4
R4
R3
R3
R3
R3
R
R4
4
N
HN
N
HN
Ph
Ph
4b-Co (Y = 66%) 4c-Co (Y = 59%) 4d-Co (Y = 45%)
N
NH
R3
NH
N
R3
Ph
Ph
R4R4
R4
R4
R4
R4
R
R4
4
Ph
Ph
R3
N
R3
N
R3
R3
R3
R3
N
N
N
Co(acac)2
PhOH
4b (R3 = Me, R4 = Et)
4c (R3 = i-Bu, R4 = Me)
4d (R3 = Et, R4 = Et)
Co
Co
Ph
N
N
N
R3
R3
R4
R4
R
R4
4
Ph
4b-Co2 (Y = 28%) 4d-Co2 (Y = 33%)
Ph
Ph
Ph
Ph
NH
N
N
Co(OAc)2
N
NH
N
N
N
HN
N
N
Co
HN
N
HN
NH
N
CHCl3 - MeOH
Ph
Ph
Ph
Ph
4a
Scheme 2. Synthesis of Co(II) complexes of octaphyrin(1.0.1.0.1.0.1.0)s 4a, 4b, 4c, and 4d.
4a-Co (Y = 57%)

170
J.-i. Setsune et al. / Journal of Organometallic Chemistry 692 (2007) 166–174
Fig. 4. 1H NMR spectrum of 4b-Co2 in CDCl3 at 20 ꢁC.
Table 2
1H NMR chemical shifts of 4b-Co, 4b-Co2, and 4d-Co2 in CDCl3 at 20 ꢁC
Ph
Ph
Ph
Ph
Ph
Ph
N
N
N
N
N
N
N
N
HN
N
N
N
N
N
N
N
N
N
N
N
N
Co
Ph
Co
Co
Ph
Co
Ph
Co
NH
N
N
Ph
Ph
Ph
4b-Co
4b-Co2
4d-Co2
CH3
CH2CH3
25.6
16.6
11.0
1.8
10.5
7.3
18.8
4.6
4.0
2.8
9.1
7.3
7.4
3.5
ꢀ3.6
ꢀ0.5
ꢀ3.3
3.0
ꢀ64.4
23.8
18.3
12.2
4.4
ꢀ51.0
ꢀ2.6
ꢀ11.1
ꢀ9.1
ꢀ5.2
2.1
ꢀ2.4
ꢀ7.1
ꢀ5.6
ꢀ7.1
2.4
29.1
24.9
18.8
ꢀ0.9
2.9
18.8
15.5
3.5
ꢀ0.2
ꢀ9.5
ꢀ8.6
ꢀ30.5
ꢀ176
CH2CH3
C6H5-o
C6H5-m
C6H5-p
NH
ꢀ15.4
ꢀ1.7
ꢀ4.7
3.0
1.6
7.2
43.9
4.5
4.0
4.3
ocobalt complex. The 1H chemical shifts of 4d-Co2 are sim-
ilar to those of 4b-Co2 except for the pyrrole b-ethyl groups
that replaced the pyrrole b-methyl groups of 4b-Co2. The
signals at ꢀ176, ꢀ30.5, and ꢀ15.4 ppm with the 1:1:3 rela-
tive intensity of 4d-Co2 are associated with the pyrrole b-
ethyl protons close to Co(II), while the corresponding pyr-
role b-ethyl protons appeared at ꢀ205, ꢀ35.5, and
ꢀ19.3 ppm in the case of the monocobalt complex 4d-Co.
These very low frequency chemical shifts at around
ꢀ200 ppm indicate that one of the diastereotopic methy-
lene protons of the pyrrole b-ethyl group is very close to
Co(II). The extremely low frequency signals at ꢀ294 and
ꢀ54.5 ppm observed for 4c-Co are also associated with
the diastereotopic methylene protons of the iso-butyl group
close to Co(II). Since the ratio of the isotropic shifts for the
diastereotopic methylene protons is 5.5 for 4d-Co and 4d-
Co2 and 5.3 for 4c-Co, the stereochemical relationship of
these two protons with respect to Co(II) is similar for these
Co(II) complexes. This is because the dipolar shift depends
on the geometric factor (3cos2 h ꢀ 1)/r3 where r is the dis-
tance between Co(II) and H and h is the angle of the
Co(II)-to-H direction with respect to the principal axis of
the spin tensor [12]. The intense signals at ꢀ9.0, and
ꢀ13.8 ppm of 4c-Co are associated with the methyl proton
of the iso-butyl group close to Co(II). These low frequency
resonances are characteristic of the iso-butyl group at the
crossing point of the figure eight loop in the Co(II) octa-
phyrins. However, 4a-Co did not show these low frequency
resonances as depicted in Fig. 6. Therefore, the 4,40-dipro-
pyl-2,20-bipyrrole unit is at the crossing point of the figure
eight loop and 3,30-di-iso-butyl-4,40-dimethyl-2,20-bipyr-
role unit is at the periphery in the case of 4a-Co. It is of

J.-i. Setsune et al. / Journal of Organometallic Chemistry 692 (2007) 166–174
171
Fig. 7. 30% level Ortep drawings of 4b-Co (left) with its side view without
peripheral substituents (right). The Co atom is disordered between the two
sites.
interest that Co(II) was inserted into 4a with concomitant
transposition of the 4,40-dipropyl-2,20-bipyrrole units from
the periphery to the crossing point of the figure eight loop.
The X-ray crystallographic analysis of the monoco-
balt(II) complex 4b-Co indicated the figure eight loop
structure with Co(II) in a distorted tetragonal coordination
geometry, although the Co atom is disordered between the
two coordination sites made of four pyrrole nitrogens of
the figure eight loop (see Fig. 7). The four N–Co–N angles
are 84.39ꢁ, 86.49ꢁ, 86.30ꢁ, and 106.28ꢁ for the first coordi-
Fig. 5. 1H–1H COSY NMR spectrum of 4b-Co2 in the chemical shift
range of +20 to ꢀ20 ppm in CDCl3 at 20 ꢁC.
Fig. 6. 1H NMR spectra of 4a-Co (bottom) and 4c-Co (top) in CDCl3 at 20 ꢁC in the chemical shift range of +50 to ꢀ20 ppm. Region of ꢀ30 to ꢀ330 ppm
is shown in the inset for 4c-Co (top).

172
J.-i. Setsune et al. / Journal of Organometallic Chemistry 692 (2007) 166–174
nation site and 85.56ꢁ, 85.72ꢁ, 85.51ꢁ, and 106.86ꢁ for the
second coordination site, the total sum of which are
364.04ꢁ and 363.65ꢁ, respectively. The Co–N bond lengths
for the cis-bipyrrole units (1.848 (3), 1.856 (3), 1.842 (4),
methyl)-4,40-diethyl-3,30-dimethyl-2,20-bipyrrole 2b: Yield
91%. 1H NMR (d-value in CDCl3) 7.56 (br, 2H, NH);
7.38 (m, 4H, Ph–o-H); 7.34 (m, 4H, Ph–m-H); 7.28
(m, 2H, Ph–p-H); 5.96 (s, 2H, methine-H); 2.50 (m, 4H,
–CH2CH3); 2.05 (br, 2H, OH); 1.95 (s, 6H, b-pyrrole-
CH3); 1.09 (m, 6H, –CH2CH3). Anal. Calc. for
C28H32N2O2: C, 78.47; H, 7.52; N, 6.54. Found: C, 78.17;
H, 7.78; N, 6.31%.
˚
and 1.847 (4) A) are shorter than those for the trans-bipyr-
˚
role units (1.966 (3), 1.977 (3), 1.996 (4), and 2.003 (4) A).
The crystal structure of 4a-Co was also solved to give evi-
dence in support for the positional change of the 2,20-
bipyrrole units during Co(II) insertion (see Supplementary
material).
3.1.1.2. Bis(azafulvene)s 3a and 3b. To a mixture of the
bipyrrole dicarbinol 2a (270 mg, 0.633 mmol), di-t-butyl
dicarbonate (359 mg, 1.65 mmol, 2.6 equiv), and 4-dimeth-
ylaminopyridine (3.9 mg, 0.032 mmol) was added a dry
THF (10 ml) under argon. After stirring for 2 h at room
temperature, the solution turned yellow. Methanol
(30 ml) was added and the mixture was condensed to give
precipitates of 6,60-diphenyl-4,40-dipropyl-2,20-bis(azaful-
vene) 3a: Yield 82%. Mp 192 ꢁC. UV–Vis (kmax nm (loge)
3. Experimental
Melting points were measured with a YANACO micro-
1
melting point apparatus. H NMR spectra were recorded
on a Varian Inova 400 spectrometer (400 MHz). Chemical
shifts were referenced with respect to (CH3)4Si (0 ppm) as
an internal standard. The UV–visible spectra were mea-
sured on a JASCO V-570 spectrometer. Elemental analyses
of C, H, and N were made with a YANACO MT-5 CHN
recorder. ESITOF-MS spectra were measured with a
Applied Biosystems Mariner mass spectrometer. Solvents
were purified prior to use by conventional methods. CDCl3
was passed through basic Al2O3 before use. Other chemi-
cals were of reagent grade and used as received. 5,50-Di-
formyl-4,40-diethyl-3,30-dimethyl-2,20-bipyrrole and 5,50-
diformyl-4,40-dipropyl-2,20-bipyrrole were synthesized
according to the literature method [13].
1
in CH2Cl2) 416 (4.81). H NMR (d-value in CDCl3) 8.37
(d, 4H, Ph–o-H); 7.47 (m, 4H, Ph–m-H); 7.43 (m, 2H,
Ph–p-H); 7.19 (s, 2H, b-pyrrole-H); 7.08 (s, 2H, methine-
H); 2.70 (t, 4H, –CH2CH2CH3); 1.77 (m, 4H, –CH2-
CH2CH3); 1.06 (t, 6H, –CH2CH2CH3). Anal. Calc. for
C28H28N2: C, 85.67; H, 7.19; N, 7.14. Found: C, 85.39;
H, 7.12; N, 6.82%. A similar procedure using bipyrrole
dicarbinol 2b afforded 6,60-diphenyl-4,40-diethyl-3,30-
dimethyl-2,20-bis(azafulvene) 3b: Yield 94%. Mp 215 ꢁC.
1
UV–Vis (kmax nm (loge) in CH2Cl2) 413 (4.76). H NMR
(d-value in CDCl3) 8.34 (m, 4H, Ph–o-H); 7.43 (m, 4H,
Ph–m-H); 7.39 (m, 2H, Ph–p-H); 6.97 (s, 2H, methine-H);
2.64 (q, 4H, –CH2CH3); 2.50 (s, 4H, –CH3); 1.20 (t, 6H,
–CH2CH3). Anal. Calc. for C28H28N2: C, 85.67; H, 7.19;
N, 7.14. Found: C, 85.59; H, 7.18; N, 7.31%.
3.1. Syntheses
3.1.1. 2,20-Bipyrrole derivatives
3.1.1.1. 5,50-Bis(phenylhydroxymethyl)-2,20-bipyrroles 2a
and 2b. Phenyllithium in cyclohexane–diethyl ether
(5.7 ml; 5.34 mmol, 7 equiv) was added dropwise to a dry
THF solution (10 ml) of 5,50-diformyl-4,40-dipropyl-2,20-
bipyrrole (208 mg, 0.766 mmol) cooled at ꢀ50 ꢁC under
argon. After the reaction mixture was stirred at ꢀ50 ꢁC
for 2.5 h and then at room temperature for 1 h, the result-
ing yellow solution was quenched with water (10 ml) show-
ing color change to red and then to yellow. The reaction
mixture was repeatedly extracted with diethyl ether. The
organic layer was washed with water and then with brine.
After drying over anhydrous K2CO3, the solvent was
removed under reduced pressure and the residue was pre-
cipitated from cold diethyl ether–hexane to give yellow
powders of 5,50-bis(phenylhydroxymethyl)-4,40-dipropyl-
2,20-bipyrrole 2a as a mixture of a meso form and a dl form.
3.1.2. Octaphyrin(1.0.1.0.1.0.1.0)s 4a and 4b
A dry CH2Cl2 solution (10 ml) of bis(azafulvene) 3a
(40.4 mg, 0.103 mmol) and 3,30-di-iso-butyl-4,40-dimethyl-
2,20-bipyrrole 1c (28.6 mg, 0.100 mmol) was stirred for
20 h at room temperature. DDQ (95.3 mg, 0.42 mmol)
was added to the reaction mixture and the stirring was
continued for further 3 h at room temperature. The reac-
tion mixture was passed through Celite and the filtrate
was shaken with 10% aqueous NaOH solution for 3 min.
The organic layer was separated, washed with water, and
then dried over Na2SO4. The column chromatography on
alumina with CH2Cl2 afforded octaphyrin 4a as a purple
band. Yield 28%. UV–Vis (kmax nm (loge) in CH2Cl2)
377 (4.69); 553 (5.09). 1H NMR (d-value in toluene-d8)
14.99 (br, 4H, NH); 7.75, 6.70 (d, 4H · 2, meso-Ph–o-H);
7.19, 6.91 (t, 4H · 2, meso-Ph–m-H); 7.12 (t, 4H, meso-
Ph–p-H); 6.20 (s, 4H, b-pyrrole-H); 3.05, 2.95 (m, 4H · 2,
–CH2CH(CH3)2); 3.10 (br, 4H, –CH2CH(CH3)2); 1.38,
1.01 (d · 2, 12H · 2, J = 6.1, 5.8 Hz, –CH2CH(CH3)2);
1.52 (s, 12H, b-pyrrole-CH3); 1.65, 1.48 (m, 4H · 2, –CH2-
CH2CH3); 1.24, 1.23 (m, 4H · 2, –CH2CH2CH3); 0.59 (t,
12H, J = 6.0 Hz, –CH2CH2CH3) ESI-MS (found/calcd
for C92H104N8+H+) 1321.74/1321.85. Anal. Calc. for
1
2a: Yield 83%. H NMR (d-value in CDCl3) 8.00 (br, 2H,
NH); 7.36 (m, 4H, Ph–o-H); 7.34 (m, 4H, Ph–m-H); 7.28
(m, 2H, Ph–p-H); 5.96 (s, 2H, b-pyrrole-H); 5.95 (s, 2H,
methine-H); 2.40 (t, 4H, –CH2CH2CH3); 2.2 (br, 2H,
OH); 1.65 (m, 4H, –CH2CH2CH3); 0.98 (t, 6H, –CH2-
CH2CH3). Anal. Calc. for C28H32N2O2: C, 78.47; H,
7.52; N, 6.54. Found: C, 78.59; H, 7.56; N, 6.40%. A
similar procedure using 5,50-diformyl-4,40-diethyl-3,30-
dimethyl-2,20-bipyrrole afforded 5,50-bis(phenylhydroxy-

J.-i. Setsune et al. / Journal of Organometallic Chemistry 692 (2007) 166–174
173
C92H104N8 Æ C6H14: C, 83.59; H, 8.45; N, 7.96. Found: C,
83.72; H, 8.56; N, 7.90%. A reaction of 3b and 4,40-
diethyl-3,30-dimethyl-2,20-bipyrrole 1b was worked up
similarly. Column chromatography on silica gel afforded
octaphyrin 4b by elution with CH2Cl2–acetone (20/1).
Yield 39%. UV–Vis (kmax nm (loge) in CH2Cl2) 376
11.0 (–CH2CH(CH3)2); 10.2, 8.6, 7.3, 6.9, 6.6 (meso-Ph–
H); 17.9, 16.6, 9.0, 7.4, 6.8, 4.1, 4.0, 2.6, 1.7, ꢀ2.5, ꢀ5.4
(meso-Ph–H and alkyl-H); 8.4, 5.9, 4.9, 3.5, 3.1, 2.6, 0.9,
0.7, 0.5, ꢀ9.1, ꢀ13.9 (CH3); ꢀ54.5, ꢀ293.8 (–CH2CH-
(CH3)2). ESI-MS (found/calcd for C100H118N8Co+H+)
1490.73/1490.89. Anal. Calc. for C100H118N8Co: C, 83.46;
H, 7.49; N, 9.05. Found: C, 83.29; H, 7.36; N, 9.33%.
4d-Co: Yield 45%. UV–Vis (kmax nm (loge) in CH2Cl2)
1
(4.49); 578 (4.96). H NMR (d-value in toluene-d8) 15.75
(br, 4H, NH); 7.76, 7.19 (d, 4H · 2, meso-Ph–o-H); 7.47
(m, 8H, meso-Ph–m-H); 7.35 (t, 4H, meso-Ph–p-H); 2.55,
2.05 (br · 2, 12H · 2, b-pyrrole-CH3); 1.97, 1.71, 1.62,
1.34 (m, 4H · 4, –CH2CH3); 0.73, 0.61 (t, 12H · 2,
–CH2CH3). ESI-MS (found/calcd for C84H88N8+H+)
1210.69/1210.70. Anal. Calc. for C84H88N8: C, 83.40; H,
7.33; N, 9.26. Found: C, 83.52; H, 7.57; N, 8.99%.
1
580 (4.94). H NMR (d-value in CDCl3) 42.1 (NH); 27.8,
18.6, 16.8, 16.4, 11.5, 10.7, 6.5, 5.8, 5.3, 4.2, 2.2, ꢀ1.5,
ꢀ2.4, ꢀ3.1, ꢀ6.4, ꢀ7.4, ꢀ35.5, ꢀ205 (–CH2CH3 and
meso-Ph–H); 13.8, 7.9, 4.1, 3.0, 0.5, ꢀ1.5, ꢀ4.8, ꢀ19.3
(–CH2CH3); 10.1, 9.3 (Ph–o-H); 7.4, 7.2, 7.1, 4.7, 3.5, 2.7
(meso-Ph–m,p-H). ESI-MS (found/calcd for C92H102N8-
Co+H+) 1378.61/1378.76. Anal. Calc. for C92H102N8-
Co Æ 2CHCl3: C, 69.80; H, 6.48; N, 6.93. Found: C, 70.65;
H, 6.67; N, 7.09%.
3.1.3. Octaphyrin(1.0.1.0.1.0.1.0) 4c
Prepared by the Rothmund type reaction of 1c and
benzaldehyde in the presence of TFA according to the
synthesis of 4d [3b]. Yield 39%. UV–Vis (kmax nm (loge)
3.1.4.2. Dinuclear Co(II) complexes 4b-Co2 and 4d-
Co2. A mixture of octaphyrin 4b (20 mg, 0.017 mmol),
Co(acac)2 (39 mg, 0.13 mmol), and phenol (1.0 g) was
heated at reflux for 3 h under argon. The reaction mixture
was partitioned between CH2Cl2 and 0.5 N aqueous NaOH
solution. The organic layer was dried over Na2SO4 and
then evaporated to dryness. The residue was chromato-
graphed on alumina with CH2Cl2–acetone (2/1) to give a
blue fraction. Recrystallization from hexane–CH2Cl2 affor-
ded the dicobalt complex 4b-Co2. Yield 28%. UV–Vis (kmax
1
in CH2Cl2) 378 (4.31); 580 (4.81). H NMR (d-value in
CDCl3) 15.55 (br, 4H, NH); 7.59, 7.15 (d, 4H · 2, meso-
Ph–o-H); 7.51, 7.46, 7.40 (t · 3, 4H · 3, meso-Ph–m,p-H);
3.6, 1.8 (br · 2, 4H · 2, –CH2CH(CH3)2); 2.1 (br, 8H,
–CH2CH(CH3)2); 1.63, 1.46 (br · 2, 4H · 2, –CH2CH-
(CH3)2); 1.35, 1.23 (br · 2, 12H · 2, pyrrole-b-Me); 0.93,
0.77 (br · 2, 12H · 2, –CH2CH(CH3)2); 0.55 (br, 24H,
–CH2CH(CH3)2). ESI-MS (found/calcd for C100H120
-
N8+H+) 1434.01/1433.97. Anal. Calc. for C100H120N8: C,
83.75; H, 8.43; N, 7.81. Found: C, 83.38; H, 8.40; N, 7.65%.
1
nm (loge) in CH2Cl2) 392 (4.68); 597 (4.87). H NMR (d-
value in CDCl3) summarized in Table 2. ESI-MS (found/
calcd for C84H84N8Co2) 1322.35/1322.55. Anal. Calc. for
C84H84N8Co2 Æ CH2Cl2 Æ C6H14: C,73.13; H, 6.74; N, 7.50.
Found: C, 72.84; H, 6.46; N, 7.41%.
3.1.4. Co(II) complexes of octaphyrin(1.0.1.0.1.0.1.0)s
3.1.4.1. Mononuclear Co(II) complexes 4a-Co, 4b-Co, 4c-
Co, and 4d-Co. 4b-Co: A mixture of octaphyrin 4b (20 mg,
0.017 mmol), Co(OAc)2 Æ 4H2O (33 mg, 0.13 mmol), trieth-
ylamine (0.020 ll, 0.27 mmol), CHCl3 (1.5 ml), and MeOH
(0.5 ml) was stirred for 3 h at room temperature under
argon. The reaction mixture was partitioned between
CH2Cl2 and water. The organic layer was dried over
Na2SO4 and then evaporated to dryness. The residue was
chromatographed on alumina with hexane–CH2Cl2 (3/1)
to give a blue fraction. Recrystallization from hexane–
CH2Cl2 afforded the monocobalt complex 4b-Co. Yield
4d-Co2: Yield 33%. UV–Vis (kmax nm (loge) in CH2Cl2)
1
592 (4.74). H NMR (d-value in CDCl3) summarized in
Table 2. ESI-MS (found/calcd for C92H100N8Co2)
1435.55/1435.67. Anal. Calc. for C92H100N8Co2 Æ 2CHCl3:
C, 67.43; H, 6.14; N, 6.69. Found: C, 67.08; H, 6.07; N,
6.71%.
3.2. X-ray crystallography
1
66%. UV–Vis (kmax nm (loge) in CH2Cl2) 588 (4.91). H
Bruker Smart 1000 diffractometer equipped with a CCD
detector was used for data collection. An empirical absorp-
tion correction was applied using the SADABS program. The
structure was solved and refined by full-matrix least-
squares calculations on F2 using the SHELXTL 97 program
package [14]. The hydrogen atoms were included at stan-
dard positions but not refined.
NMR (d-value in CDCl3) summarized in Table 2. ESI-MS
(found/calcd for C84H86N8Co+H+) 1266.69/1266.64. Anal.
Calc. for C84H86N8Co Æ CH2Cl2 Æ C6H14: C,76.02; H, 7.15;
N, 7.79. Found: C, 75.54; H, 7.06; N, 7.63%.
4a-Co: Yield 57%. UV–Vis (kmax nm (loge) in CH2Cl2)
1
581 (4.85). H NMR (d-value in CDCl3) 40.5 (NH); 30.8,
11.3 (–CH2CH(CH3)2); 9.6, 8.2, 7.8, 7.7, 7.5 (meso-Ph–
H); 5.8, 5.0, 4.0, 3.8, 3.2, 2.8, 1.7, ꢀ1.4, ꢀ2.0, ꢀ2.8
(meso-Ph–H and alkyl-H); 5.3, 4.6 2.8, 2.2, 2.0, 1.6, 0.6,
ꢀ1.2 (CH3). ESI-MS (found/calcd for C92H102N8+H+)
1378.67/1378.76. Anal. Calc. for C92H102N8Co Æ 2H2O: C,
78.10; H, 7.55; N, 7.92. Found: C, 77.63; H, 7.38; N, 7.93%.
4c-Co: Yield 59%. UV–Vis (kmax nm (loge) in CH2Cl2)
Recrystallization from CH2Cl2/hexane gave crystals of
4a. Crystal data: C92H104N8 Æ C6H14, M = 1408.00, mono-
clinic, space group P2(1)/n, a = 16.856(2), b = 28.935(4),
3
˚
˚
c = 17.283(2) A, b = 92.182(2)ꢁ, V = 8423.6(18) A , Z = 4,
Dcalc = 1.110 Mg/m3, l(Mo-Ka) = 0.064 mmꢀ1, T = 293(2)
K, crystal size 0.60 · 0.40 · 0.30 mm. A total of 17,402
unique reflections were collected (2.8 < 2h < 54.7ꢁ) using
graphite-monochromated Mo-Ka radiation. 985 para-
1
584 (4.90). H NMR (d-value in CDCl3) 39.2 (NH); 29.0,

174
J.-i. Setsune et al. / Journal of Organometallic Chemistry 692 (2007) 166–174
meters were refined with all non-hydrogen atoms aniso-
tropically. All hydrogen atoms placed at ideal positions
were included but not refined. R1 = 0.975, wR2 = 0.2459
for 7281 reflections with I > 2.00r(I); R1 = 0.2125,
wR2 = 0.3183 for all data. GOF (on F2) = 1.005.
are 603485, 603486 and 603487, respectively. Copies of this
information may be obtained free of charge from The
director, CCDC, 12 Union Road, Cambridge, CB2 1EZ
UK (fax: +44 1223 336033; e-mail: deposit@ccdc.cam.a-
c.uk or www: http://www.ccdc.cam.ac.uk). Detailed crys-
tallographic data of 4a, 4b-Co, and 4a-Co with their
Ortep drawings and a 2D ROESY NMR spectrum of 4a
were included. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2006.04.045.
Recrystallization from CH2Cl2/pentane gave crystals
of 4b-Co. Crystal data: C84H86N8Co Æ 2C5H12, M =
ꢀ
1410.83, triclinic, space group P1, a = 13.9511(10), b =
˚
13.9536(10), c = 20.7904(15) A, a = 82.0170(10)ꢁ, b =
3
˚
82.0600(10)ꢁ, c = 86.0630(10)ꢁ, V = 3965.3(5) A , Z = 2,
Dcalc = 1.182 Mg/m3, l(Mo-Ka)= 0.268 mmꢀ1, T = 293(2)
K, crystal size 0.4 · 0.3 · 0.2 mm. A total of 15,040 unique
reflections were collected (2.0 < 2h < 54.4ꢁ) using graphite-
monochromated Mo-Ka radiation. 930 parameters were
refined with all non-hydrogen atoms for the octaphyrin
moiety anisotropically. C(85) to C(94) belonging to pen-
tane solvates were refined isotropically. All hydrogen
atoms placed at ideal positions were included but not
refined. Refined occupancies for the disordered Co(1)/
Co(2), C(39A)/C(39B), and C(59A)/C(59B) were 0.54/
0.46, 0.56/0.44, and 0.58/0.42, respectively. R1 = 0.0832,
wR2 = 0.2284 for 9272 reflections with I > 2.00r(I); R1 =
0.1355, wR2 = 0.2729 for all data. GOF (on F2) = 1.069.
References
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nyloctaphyrin(1.0.1.0.1.0.1.0)s were unambiguously char-
1
acterized on the basis of the H NMR spectra and X-ray
crystallography. The octaphyrin having alternate arrange-
ment of two 2,20-bipyrroles with different stereochemical
feature was synthesized without scrambling. Although the
iso-butyl-substituted 2,20-bipyrrole was at the crossing
point of the figure eight loop in the free base octaphyrin,
transposition of the 2,20-bipyrrole unit led to the exclusive
formation of the Co(II) complex where the propyl-substi-
tuted bipyrrole is at the crossing point. The structural fea-
ture of this Co(II) octaphyrin is preferable for studying
coordination chemistry because Co(II) is not covered by
alkyl groups at the pyrrole b-position.
Acknowledgements
This work was supported by Grant-in-Aid for Scientific
Research (Nos. 16350023 and 16033240) from the Ministry
of Education, Culture, Sports, Science and Technology, Ja-
pan. The author is also grateful to the CREST program
(the Japan Science and Technology Agent) and the VBL
project (Kobe University). The authors are also grateful
to Prof. K. Eda (Kobe Univ.) for his help in the X-ray crys-
tallographic analysis.
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Appendix A. Supplementary data
Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic Data
Center, CCDC reference numbers for 4a, 4b-Co, and 4a-Co