Heterobimetallic complexes of cobalt(IV) porphyrin-corrole dyads. Synthesis, physicochemical properties, and X-ray structural characterization

Article abstract of DOI:10.1021/ic0501622

The synthesis of a novel family of heterobinuclear cofacial biphenylene (B), anthracene (A), 9,9-dimethylxanthene (X), or dibenzofuran (O) bridged porphyrin-corrole complexes, (PCY)MClCoCl, is reported, M being either an iron(III) or manganese(III) ion. Each complex was characterized by electrochemistry, mass spectrometry, UV-vis, IR, and electron spin resonance spectroscopy. Unlike previously examined biscobalt porphyrin-corrole dyads, the cobalt ion of the corrole moiety is present in a high-valence +4 oxidation state, as proven by electrochemistry, spectroelectrochemistry, and an X-ray diffraction study of (PCB)FeClCoCl, which shows the presence of a bound Ch anion on the cobalt corrole. Structural data: (PCB)FeClCoCl·0.5(C ₇H₁₆)·0.5(CH₂Cl₂) ·2H₂O, triclinic, space group P1^-, a = 13.8463(3) A, b = 16.8164(5) A, c = 17.9072(6) A, α = 93.780(1)°, β= 111.143(1)°, γ = 97.463(2)°, Z=2.

Full text of DOI:10.1021/ic0501622

Inorg. Chem. 2005, 44, 3972−3983
Heterobimetallic Complexes of Cobalt(IV) Porphyrin−Corrole Dyads.
Synthesis, Physicochemical Properties, and X-ray Structural
Characterization
Roger Guilard,*,† Fabien Burdet,† Jean-Michel Barbe,† Claude P. Gros,† Enrique Espinosa,†
Jianguo Shao,‡ Zhongping Ou,‡ Riqiang Zhan,‡ and Karl M. Kadish*,‡
Faculte´ des Sciences Gabriel, UniVersite´ de Bourgogne, LIMSAG UMR 5633, 6 BouleVard
Gabriel, 21000 Dijon, France, and Department of Chemistry, UniVersity of Houston,
Houston, Texas 77204-5003
Received January 31, 2005
The synthesis of a novel family of heterobinuclear cofacial biphenylene (B), anthracene (A), 9,9-dimethylxanthene
(X), or dibenzofuran (O) bridged porphyrin corrole complexes, (PCY)MClCoCl, is reported, M being either an
iron(III) or manganese(III) ion. Each complex was characterized by electrochemistry, mass spectrometry, UV vis,
IR, and electron spin resonance spectroscopy. Unlike previously examined biscobalt porphyrin corrole dyads, the
cobalt ion of the corrole moiety is present in a high-valence 4 oxidation state, as proven by electrochemistry,
spectroelectrochemistry, and an X-ray diffraction study of (PCB)FeClCoCl, which shows the presence of a bound
Cl- anion on the cobalt corrole. Structural data: (PCB)FeClCoCl
0.5(C7H16) 0.5(CH2Cl2) 2H2O, triclinic, space group
17.9072(6) Å, R ) 93.780(1) â ) 111.143(1) γ ) 97.463(2)
−
−
−
+
‚
‚
‚
P1h
, a
)
13.8463(3) Å, b
)
16.8164(5) Å, c
)
°
,
°
,
°,
Z
)
2.
Introduction
Johnson and co-workers in the early 1970s.26-28 The
Co(III) oxidation state is the most favored in corrole
complexes, and theoretical calculations have shown that the
Cobalt corroles are, by far, the most studied metallocorrole
complexes. Numerous papers relative to cobalt corroles have
appeared in the literature1-25 since the pioneering work of
(11) Hitchcock, P. B.; McLaughlin, G. M. J. Chem. Soc., Dalton Trans.
1976, 1927-1930.
(12) Ichimori, K.; Ohya-Nishiguchi, H.; Hirota, N.; Yamamoto, K. Bull.
Chem. Soc. Jpn. 1985, 58, 623-630.
(13) Je´roˆme, F.; Gros, C. P.; Tardieux, C.; Barbe, J. M.; Guilard, R. J.
Chem. Soc., Chem. Commun. 1998, 2007-2008.
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Will, S.; Erben, C.; Vogel, E. J. Am. Chem. Soc. 1998, 120, 11986-
11993.
(15) Kadish, K. M.; Koh, W.; Tagliatesta, P.; Sazou, D.; Paolesse, R.;
Licoccia, S.; Boschi, T. Inorg. Chem. 1992, 31, 2305-2313.
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F.; Bolze, F.; Burdet, F.; Guilard, R. Inorg. Chem. 2002, 41, 3990-
4005.
(17) Kadish, K. M.; Shao, J.; Ou, Z. P.; Gros, C. P.; Bolze, F.; Barbe,
J.-M.; Guilard, R. Inorg. Chem. 2003, 42, 4062-4070.
(18) Licoccia, S.; Tassoni, E.; Paolesse, R.; Boschi, T. Inorg. Chim. Acta
1995, 235, 15-20.
(19) Murakami, Y.; Yamada, S.; Matsuda, Y.; Sakata, K. Bull. Chem. Soc.
Jpn. 1978, 51, 123-129.
(20) Rovira, C.; Kunc, K.; Hutter, J.; Parrinello, M. Inorg. Chem. 2001,
40, 11-17.
* To whom correspondence should be addressed. E-mail:
Roger.Guilard@u-bourgogne.fr (R.G.), kkadish@uh.edu (K.K.).
† Universite´ de Bourgogne.
‡ University of Houston.
(1) Guilard, R.; Barbe, J. M.; Stern, C.; Kadish, K. M. In The Porphyrin
Handbook; Kadish, K. M., Smith, K. M., Guilard, R., Eds.; Elsevier:
New York, 2003; Vol. 116, pp 303-348.
(2) Erben, C.; Will, S.; Kadish, K. M. In The Porphyrin Handbook;
Kadish, K. M., Smith, K. M., Guilard, R., Eds.; Academic Press: New
York, 2000; Vol. 2, pp 233-300.
(3) Paolesse, R. In The Porphyrin Handbook; Kadish, K. M., Smith, K.
M., Guilard, R., Eds.; Academic Press: New York, 2000; Vol. 2, pp
201-232.
(4) Licoccia, S.; Paolesse, R. Struct. Bonding (Berlin) 1995, 84, 71-133.
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J.; Weiss, R.; Kadish, K. M. Inorg. Chem. 2001, 40, 4845-4855.
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(9) Gryko, D. T. Eur. J. Org. Chem. 2002, 1735-1743.
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Fischer, J.; Weiss, R.; Kadish, K. M. Inorg. Chem. 2001, 40, 4856-
4865.
(21) Will, S.; Lex, J.; Vogel, E.; Adamian, V. A.; Van Caemelbecke, E.;
Kadish, K. M. Inorg. Chem. 1996, 35, 5577-5583.
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Chem. 2000, 39, 2704-2705.
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7, 4259-4265.
3972 Inorganic Chemistry, Vol. 44, No. 11, 2005
10.1021/ic0501622 CCC: $30.25
© 2005 American Chemical Society
Published on Web 04/28/2005

Heterobimetallic Complexes of Co(IV) Porphyrin-Corrole Dyads
Chart 1
electronic ground state is an intermediate spin state (S ) 1),
lower in energy by 6.1 kcal/mol than the low spin state
arrangement (S ) 0).20 Therefore, both spin states might be
easily observed in solution for Co(III), depending on the
solvent nature.2,29 Two examples of high-valence cobalt(IV)
corroles have, nevertheless, been reported,7,21 and the struc-
ture of one of the derivatives has been determined by X-ray
diffraction.21 Despite this small number of Co(IV) deriva-
tives, electrochemistry experiments, carried out on a large
variety of cobalt metallocorroles, have demonstrated that the
+4 oxidation state is easily available.2,6,7
Our own research has been directed towards the study of
alkyl- and aryl-substituted corroles in their mononuclear and
binuclear forms.1,5,10,16,17,30,31 In the latter series of compounds,
two corroles or a corrole and a porphyrin can be linked
through a rigid spacer leading to face-to-face dyads.
Heterobimetallic complexes in organometallic chemistry
are, a priori, promising catalysts that result from the
cooperative effect of the two metals, but there are very few
examples of powerful catalysts based on this phenomenon.
The heterobimetallic complexes examined in the present
study were synthesized as possible models that favor the
cooperative effect of the metal ions within the two macro-
cycles; the face-to-face configuration of the two macrocycles
is favorable for inducing an endo coordination of small
molecules, and the low and high oxidation states of the
central metal ions can be stabilized in the porphyrin and
corrole rings, respectively, by the application of a potential
or by the selective use of specific chemical oxidizing or
reducing agents. Last, but not least, we have already shown
that biscobalt porphyrin-corrole dyads with the same linker
groups as those in the current study are efficient catalysts
for the 4e reduction of oxygen to water,31 and a similar type
of catalytic reactivity may be possible for the currently
investigated dyads containing an Fe(III) or Mn(III) porphyrin
and a Co(III) or Co(IV) corrole.
by a chloride ion and is stabilized in a high oxidation state
in nonaqueous media, as proven by electrochemistry, electron
spin resonance (ESR) spectroscopy, and an X-ray diffraction
study of (PCB)FeClCoCl.
Experimental Section
Instrumentation. UV-visible spectra were recorded on a Varian
Cary 50 spectrophotometer. Mass spectra were obtained on a Bruker
ProFLEX III spectrometer in the MALDI/TOF mode using dithranol
as a matrix. ESR spectra were recorded at the X band (9.6 GHz)
in solution on a Bruker ESP 300 spectrometer, from the “Centre
de Spectrome´trie Mole´culaire de l’Universite´ de Bourgogne”,
equipped with a liquid-nitrogen cooling accessory. ESR spectra are
referenced to 2,2-diphenyl-1-picrylhydrazyl (DPPH, g ) 2.0036).
Cyclic voltammetry was carried out with an EG&G Model 173
potentiostat. A three-electrode system was used and consisted of a
glassy carbon or platinum disk working electrode, a platinum wire
counter electrode, and a saturated calomel reference electrode
(SCE). The SCE electrode was separated from the bulk of the
solution by a fritted-glass bridge of low porosity that contained
the solvent/supporting electrolyte mixture. Half-wave potentials
were calculated as E1/2 ) (Epa + Epc)/2 and are referenced to the
SCE. UV-visible spectroelectrochemical experiments were per-
formed with an optically transparent platinum thin-layer electrode.
Potentials were applied with an EG&G Model 173 potentiostat.
X-ray Data Collection and Structure Determination Details
for (PCB)FeClCoCl (6). Single crystals suitable for X-ray dif-
fraction analysis were obtained from methylene chloride/heptane,
exhibiting an approximate prismatic morphology and dark-brown
color. The dimensions of the selected specimen were 0.37 × 0.18
× 0.13 mm3. It was mounted on a Nonius KappaCCD diffracto-
meter, and data were collected32a at a low temperature (T ) 110
K), using Mo KR graphite monochromatic radiation (λ ) 0.710 73
Å) from a sealed tube. Lattice parameters were obtained by a least-
In this paper, we focus on the synthesis, physicochemical
properties, and X-ray structural characterization of the eight
heterobimetallic face-to-face complexes of porphyrin-cor-
role dyads shown in Chart 1. These compounds are repre-
sented as (PCY)MClCoCl, where PCY ) PCB, PCX, PCA,
or PCO and M ) Fe(III) or Mn(III) [Y being the biphen-
ylenyl (B), 9,9-dimethylxanthenyl (X), anthracenyl (A), or
dibenzofuranyl (O) spacer]. Surprisingly, the cobalt atom of
the corrole moiety in the complexes is axially coordinated
(24) Melent’eva, T. A. Russ. Chem. ReV. 1983, 52, 641-661.
(25) Genokhova, N. S.; Melent’eva, T. A.; Berezovskii, V. M. Russ. Chem.
ReV. 1980, 49, 1056-1067.
(26) Conlon, M.; Johnson, A. W.; Overend, W. R.; Rajapaksa, D.; Elson,
C. M. J. Chem. Soc., Perkin Trans. 1 1973, 2281-2288.
(27) Dolphin, D.; Johnson, A. W.; Leng, J.; van den Broek, P. J. Chem.
Soc. C 1966, 880-884.
(28) Johnson, A. W.; Kay, I. T. J. Chem. Soc. 1965, 1620-1629.
(29) Barbe, J. M.; Burdet, F.; Espinosa, E.; Guilard, R. Eur. J. Inorg. Chem.
2005, 1032-1041.
(30) Guilard, R.; Gros, C. P.; Barbe, J.-M.; Espinosa, E.; Je´roˆme, F.; Tabard,
A.; Shao, J.; Ou, Z. P.; Latour, J.-M.; Kadish, K. M. Inorg. Chem.
2004, 43, 7441-7455.
(31) Kadish, K. M.; Fremond, L.; Ou, Z.; Shao, J.; Shi, C.; Anson, F. C.;
Burdet, F.; Gros, C. P.; Barbe, J.-M.; Guilard, R. J. Am. Chem. Soc.
2005, 127, 5625-5631.
Inorganic Chemistry, Vol. 44, No. 11, 2005 3973

Guilard et al.
squares fit to the optimized setting angles of all measured reflections
in the full θ range data collection. Intensity data were recorded as
æ and ω scans with κ offsets. Data reduction was done using the
DENZO software.32b The structure was solved by a direct method
using the SIR97 program.33 Refinement was carried out by full-
matrix least squares on F2, with all data using the SHELXL97
program.34
17-diethyl-2,3,7,8,12,18-hexamethylporphyrin-5-yl)-8-[cobalt(III)-
7,8,12,13-tetramethyl-2,3,17,18-tetraphenylcorrol-10-yl]an-
thracene, (PCA)H2Co;35 4-(13,17-diethyl-2,3,7,8,12,18-hexameth-
ylporphyrin-5-yl)-6-[cobalt(III)-2,3,17,18-tetraphenyl-7,8,12,13-
tetramethylcorrol-10-yl]dibenzofuran, (PCO)H2Co;35 13,17-diethyl-
2,3,7,8,12,18-hexamethyl-5-phenylporphyrin, (Et2Me6PhP)H2;5 and
7,8,12,13-tetramethyl-2,3,10,17,18-pentaphenylcorrole, (Me4Ph5Cor)-
H3.5
Crystal Data for (PCB)FeClCoCl (6). C89H71(CoCl)(FeCl)N8‚
0.5(C7H16)‚0.5(CH2Cl2)‚2H2O: M ) 1566.81, triclinic, space group
) P1h, a ) 13.8463(3) Å, b ) 16.8164(5) Å, c ) 17.9072(6) Å, R
) 93.780(1)°, â ) 111.143(1)°, γ ) 97.463(2)°, V ) 3827.2(2)
Å3, Z ) 2, Dc ) 1.360 g cm-3, µ(Mo KR) ) 0.568 mm-1. A total
of 25 659 reflections were collected up to θmax ) 25.4° (complete-
ness 98.1%). After merging, 13 889 reflections were unique (Rint
) 0.0453). Anisotropic thermal parameters were used for non-H
atoms. All hydrogens, except those belonging to the water
molecules, which were not found, were placed at calculated
positions as riding atoms and refined with a global isotropic thermal
factor. Two water molecules separated by d(Ow‚‚‚Ow) ) 2.828 Å
and one CH2Cl2 solvent molecule were found to share the same
asymmetric unit region as one C7H16 molecule, and the site
occupation factors were fixed to 0.5 for all of them. An additional
water molecule was also found disordered over two sites in the
asymmetric unit and was refined with fixed site occupation factors
of 0.75/0.25. At convergence, the final agreement factors are R(F)
) 0.0812 and 0.1182 and Rw(F2) ) 0.2062 and 0.2273 for I >
2σ(I) and all data, respectively. The maximum and minimum
residual electron densities (1.86/-1.23 eÅ-3) were found at 1.19
Å from iron and at 0.56 Å from one of the chlorine atoms,
respectively.
Chemicals and Reagents. Absolute dichloromethane (CH2Cl2)
was obtained from Fluka Chemical Company and used as received.
Pyridine (py) was distilled over KOH under argon prior to use.
Tetrahydrofuran (THF) was distilled over a sodium-benzoquinone
complex under argon, and absolute methanol (MeOH) was distilled
over magnesium under argon prior to use. Benzonitrile (PhCN) was
purchased from Aldrich Chemical Company and distilled over P2O5
under a vacuum prior to use. Alumina (Merck; usually Grade III,
i.e., deactivated with 6% water) and silica gel (Merck; 70-120
mm) were used for column chromatography. Analytical thin-layer
chromatography was performed using Merck 60 F254 silica gel
(precoated sheets, 0.2 mm thick). Reactions were monitored by thin-
layer chromatography and UV-visible spectroscopy. Tetra-n-
butylammonium perchlorate (TBAP, Fluka Chemical Co.) was twice
recrystallized from absolute ethanol and dried in a vacuum oven at
40 °C for a week prior to use. Tetrabutylammonium chloride
(TBACl, Sigma-Aldrich) was used as received.
1-(Chloro-manganese-2,3,7,8,12,18-hexamethyl-13,17-dieth-
ylporphyrin-5-yl)-8-(chloro-cobalt-2,3,17,18-tetraphenyl-7,8,12,-
13-tetramethylcorrol-10-yl)biphenylene, (PCB)MnClCoCl (1).
Under argon and shielded from light, a solution of 150 mg (0.114
mmol) of (PCB)H2Co in 90 mL of dry THF and 61 mg (0.28 mmol,
2.5 equiv) of manganese(II) dibromide in 25 mL of methanol was
stirred and refluxed for 3 h in the presence of 12 drops of 2,6-
lutidine, the metalation reaction being monitored by UV-visible
spectroscopy. After the removal of the solvent in vacuo, the residue
thus obtained was redissolved in methylene chloride and chromato-
graphed on alumina using CH2Cl2/methanol (92/8) as the first eluent
and then CH2Cl2/methanol (90/10) as the second eluent. After the
evaporation of the solvent, the resulting solid was redissolved in
200 mL of methylene chloride and washed three times with 200
mL of 0.1 M HCl. The organic layer was then dried over MgSO4,
and the solvent was evaporated. The title product 1 was isolated in
53% yield (85 mg; 60 mmol) after its crystallization from
CH2Cl2/heptane, washing it with heptane and then pentane, and,
finally, drying it for 1 night under a vacuum at 40 °C. MS (MALDI/
TOF) m/z: 1365.06 [M - 2Cl]+, 1365.45 calcd for C89H71N8CoMn.
UV-vis (CH2Cl2), λmax (nm) (ꢀ × 10-3, mol-1 L cm-1): 359 (120),
400 (65.2), 478.5 (37.2), 531.4 (16.8). UV-vis (neat pyridine), λmax
(nm) (ꢀ × 10-3, mol-1 L cm-1): 362.9 (126), 477 (38.3), 577 (19.5).
IR (CsI) ν, cm-1: 3057 (C-H), 3026 (C-H), 2965 (C-H), 2927
(C-H), 2863 (C-H), 278 (Mn-Cl).
1-(Chloro-manganese-2,3,7,8,12,18-hexamethyl-13,17-dieth-
ylporphyrin-5-yl)-8-(chloro-cobalt-2,3,17,18-tetraphenyl-7,8,12,-
13-tetramethylcorrol-10-yl)anthracene, (PCA)MnClCoCl (2).
(PCA)MnClCoCl, 2, was prepared in 67% yield (39.5 mg, 0.027
mmol) as described for (PCB)MnClCoCl, 1, starting from (PCA)-
H2Co (60 mg, 0.040 mmol, 1 equiv) and MnBr2 (18 mg, 0.084
mmol, 1.2 equiv). MS (MALDI/TOF) m/z: 1390.76 [M - 2Cl]+•,
1391.47 calcd for C91H73N8CoMn. UV-vis (CH2Cl2), λmax (nm)
(ꢀ × 10-3, mol-1 L cm-1): 364.5 (85.7), 477.4 (54.1), 556.6 (17.0).
UV-vis (neat pyridine), λmax (nm) (ꢀ × 10-3, mol-1 L cm-1): 375.1
(98.7), 403.0 (80.5), 423.0 (80.7), 475.0 (58.6), 558.1 (22.5), 600.0
(34.1). IR (CsI) ν, cm-1
: 3053 (C-H), 3032 (C-H), 2965
(C-H), 2926 (C-H), 2864 (C-H), 279 (Mn-Cl).
4-(Chloro-manganese-2,3,7,8,12,18-hexamethyl-13,17-dieth-
ylporphyrin-5-yl)-5-(chloro-cobalt-2,3,17,18-tetraphenyl-7,8,12,-
13-tetramethylcorrol-10-yl)-9,9-dimethylxanthene, (PCX)Mn-
ClCoCl (3). (PCX)MnClCoCl, 3, was prepared in 55% yield (90
mg, 0.060 mmol) as described for (PCB)MnClCoCl, 1, starting from
(PCX)H2Co (150 mg, 0.109 mmol, 1 equiv) and MnBr2 (59 mg,
0.273 mmol, 2.5 equiv). MS (MALDI/TOF) m/z: 1423.38 [M -
2Cl]+, 1423.49 calcd for C92H77N8OCoMn. UV-vis (CH2Cl2), λmax
(nm) (ꢀ × 10-3, mol-1 L cm-1): 361.1 (91.1), 398.0 (59.9), 476.5
Starting Compounds. The following starting compounds were
synthesized according to previously described procedures:
1-(13,17-diethyl-2,3,7,8,12,18-hexamethylporphyrin-5-yl)-8-[cobalt-
(III)-2,3,17,18-tetraphenyl-7,8,12,13-tetramethylcorrol-10-yl]biphen-
ylene, (PCB)H2Co;35 4-(13,17-diethyl-2,3,7,8,12,13,18-hexa-
methylporphyrin-5-yl)-5-[cobalt(III)-2,3,17,18-tetraphenyl-7,8,12,13-
tetramethylcorrol-10-yl]-9,9-dimethylxanthene, (PCX)H2Co;35 1-(13,-
(43.9). UV-vis (neat pyridine), λmax (nm) (ꢀ × 10-3, mol-1
L
(32) (a) COLLECT software (COLLECT; data collection software; Nonius
B.V.: Delft, The Netherlands, 1998). (b) DENZO software
(Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307-326).
(33) SIR97 program (Altomare, A.; Burla, M. C.; Camalli, M.; Cascarano,
G. L.; Giacovazzo, C.; Guagliardi, A.; Moliterni, A. G. G.; Polidori,
G.; Spagna, R. J. Appl. Crystallogr. 1999, 32, 115-119).
(34) Sheldrick, G. M. SHELXL-97: Program for the Refinement of Crystal
Structures; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(35) Barbe, J.-M.; Burdet, F.; Espinosa, E.; Gros, C. P.; Guilard, R. J.
Porphyrins Phthalocyanines 2003, 7, 365-374.
cm-1): 366.1 (104), 421.0 (54.3), 475.0 (47.5), 560.0 (20.1), 600.0
(17.1). IR (CsI) ν, cm-1
: 3058 (C-H), 3025 (C-H), 2965
(C-H), 2927 (C-H), 2865 (C-H), 277 (Mn-Cl).
4-(Chloro-manganese-2,3,7,8,12,18-hexamethyl-13,17-dieth-
ylporphyrin-5-yl)-6-(chloro-cobalt-2,3,17,18-tetraphenyl-7,8,12,-
13-tetramethylcorrol-10-yl)dibenzofuran, (PCO)MnClCoCl (4).
(PCO)MnClCoCl, 4, was prepared in 50% yield (82 mg, 0.056
3974 Inorganic Chemistry, Vol. 44, No. 11, 2005

Heterobimetallic Complexes of Co(IV) Porphyrin-Corrole Dyads
mmol) as described for (PCB)MnClCoCl, 1, starting from (PCO)-
H2Co (150 mg, 0.113 mmol, 1 equiv) and MnBr2 (61 mg, 0.282
mmol, 2.5 equiv). MS (MALDI/TOF) m/z: 1381.60 [M - 2Cl]+,
1381.44 calcd for C89H71N8OCoMn. UV-vis (CH2Cl2), λmax (nm)
(ꢀ × 10-3, mol-1 L cm-1): 362.9 (117), 398 (84.9), 475.5 (61.6),
mg, 0.064 mmol) as described for (PCB)FeClCoCl, 6, starting from
(PCX)H2Co (150 mg, 0.109 mmol, 1 equiv) and FeBr2 (59 mg,
0.273 mmol, 2.5 equiv). MS (MALDI/TOF) m/z: 1460.11 [M -
Cl]+, 1459.46 calcd for C92H77N8OCoFeCl; 1425.04 [M - 2Cl]+,
1424.49 calcd for C92H77N8OCoFe. UV-vis (CH2Cl2), λmax (nm)
(ꢀ × 10-3, mol-1 L cm-1:377.1 (98.1), 513 (18.4), 641.5 (5.7).
UV-vis (neat pyridine), λmax (nm) (ꢀ × 10-3, mol-1 L cm-1): 401.9
563 (17.1). UV-vis (neat pyridine), λmax (nm) (ꢀ × 10-3, mol-1
L
cm-1): 375.1 (106), 415.9 (81.2), 473 (59.9), 554 (20.0), 598.9
(24.0). IR (CsI) ν, cm-1
:
3056 (C-H), 3026 (C-H), 2964
(125), 524.0 (15.6), 550.1 (15.8), 601.0 (23.3). IR (CsI) ν, cm-1
:
(C-H), 2927 (C-H), 2867 (C-H), 279 (Mn-Cl).
3057 (C-H), 3026 (C-H), 2927 (C-H), 2863 (C-H), 2865
(C-H), 351 (MnCl).
Chloro-manganese-13,17-diethyl-2,3,7,8,12,18-hexamethyl-5-
phenylporphyrin, (Et2Me6PhPor)MnCl (5). (Et2Me6PhPor)MnCl,
5, was prepared in 90% yield (105 mg, 0.171 mmol) as described
for (PCB)MnClCoCl, 1, starting from (Et2Me6PhPor)H2 (100 mg,
0.190 mmol, 1 equiv) and MnBr2 (102 mg, 0.475 mmol, 2.5 equiv).
MS (MALDI/TOF) m/z: 579.97 [M - Cl]+•, 579.23 calcd for
4-(Chloro-iron-2,3,7,8,12,18-hexamethyl-13,17-diethylpor-
phyrin-5-yl)-6-(chloro-cobalt-2,3,17,18-tetraphenyl-7,8,12,13-
tetramethylcorrol-10-yl)dibenzofuran, (PCO)FeClCoCl (9).
(PCO)FeClCoCl, 9, was prepared in 80% yield (132 mg, 0.091
mmol) as described for (PCB)FeClCoCl, 6, starting from (PCO)-
H2Co (150 mg, 0.113 mmol, 1 equiv) and FeBr2 (61 mg, 0.282
mmol, 2.5 equiv). MS (MALDI/TOF) m/z: 1417.23 [M - Cl]+,
1417.41 calcd for C89H71N8OCoFeCl; 1382.31 [M - 2Cl]+, 1382.44
C36H36N4Mn. UV-vis (CH2Cl2), λmax (nm) (ꢀ × 10-3, mol-1
L
cm-1): 361.5 (92.3), 425.5 (15.6), 475.0 (67.5), 564.0 (11.9). UV-
vis (neat pyridine), λmax (nm) (ꢀ × 10-3, mol-1 L cm-1): 374.0
calcd for C89H71N8OCoFe. UV-vis (CH2Cl2), λmax (nm) (ꢀ × 10-3
,
(86.6), 426 (18.0), 473.0 (58.9), 554.0 (12.9). IR (ATR) ν, cm-1
:
mol-1 L cm-1): 382.5 (118), 510.4 (21.4), 640.5 (7.7). UV-vis
(neat pyridine), λmax (nm) (ꢀ × 10-3, mol-1 L cm-1): 401.9 (160),
517.9 (14.7), 554 (15.2), 599 (28.9). IR (CsI) ν, cm-1: 3057 (C-
H), 3026 (C-H), 2963 (C-H), 2927 (C-H), 2867 (C-H), 354
(Fe-Cl).
3056 (C-H), 3021 (C-H), 2970 (C-H), 2909 (C-H), 2867 (CH),
271 (Mn-Cl).
1-(Chloro-iron-2,3,7,8,12,18-hexamethyl-13,17-diethylpor-
phyrin-5-yl)-8-(chloro-cobalt-2,3,17,18-tetraphenyl-7,8,12,13-
tetramethylcorrol-10-yl)biphenylene, (PCB)FeClCoCl (6). Under
argon and shielded from light, a solution of 150 mg (0.114 mmol)
of (PCB)H2Co in 90 mL of dry THF and 62 mg (0.28 mmol, 2.5
equiv) of iron(II) dibromide in 25 mL of methanol was stirred and
refluxed for 3 h in the presence of 12 drops of 2,6-lutidine, the
metalation reaction being monitored by UV-visible spectroscopy.
After the removal of the solvent in vacuo, the residue obtained
was redissolved in methylene chloride and chromatographed on
alumina using CH2Cl2 as a first eluent and then CH2Cl2/methanol
(98/2) as the second. After the evaporation of the solvent, the
resulting solid was redissolved in 200 mL of methylene chloride
and washed three times with 200 mL of 0.1 M HCl. The organic
layer was then dried over MgSO4, and the solvent was evaporated.
The title product 6 was isolated in 62% yield (102 mg; 70.9 mmol)
after its crystallization from CH2Cl2/heptane, washing it with
heptane and then pentane, and then drying it for 1 night under a
vacuum at 40 °C. MS (MALDI/TOF) m/z: 1401.79 [M - Cl]+•,
1401.41 calcd for C89H71N8CoFeCl; 1366.86 [M - 2Cl]+, 1366.44
Chloro-iron-13,17-diethyl-2,3,7,8,12,18-hexamethyl-5-
phenylporphyrin, (Et2Me6PhPor)FeCl (10). (Et2Me6PhPor)FeCl,
10, was prepared in 90% yield (105 mg, 0.171 mmol) as described
for (PCB)FeClCoCl, 6, starting from (Et2Me6PhPor)H2 (100 mg,
0.190 mmol, 1 equiv) and FeBr2 (102 mg, 0.475 mmol, 2.5 equiv).
MS (MALDI/TOF) m/z: 615.87 [M]+•, 615.20 calcd for C36H36N4-
FeCl; 580.74 [M - Cl]+, 580.23 calcd for C36H35N4Fe. UV-vis
(CH2Cl2), λmax (nm) (ꢀ × 10-3, mol-1 L cm-1): 383.4 (110), 508.5
(9.4), 535.0 (8.1), 639 (4.4). UV-vis (neat pyridine), λmax (nm) (ꢀ
× 10-3, mol-1 L cm-1): 403 (129), 521.9 (9.5), 634 (3.0). IR (ATR)
ν, cm-1: 3057 (C-H), 3026 (C-H), 2963 (C-H), 2927(C-H),
2861 (CH), 351 (FeCl).
Results and Discussion
A considerable number of different cobalt corroles have
been synthesized using macrocycles with different substitu-
tion patterns.1-3,5,9,10,16,17 Nearly all isolated cobalt corroles
contain a formal Co(III) central ion, and up until now, there
is only one example of a high-valence cobalt(IV) corrole
that has been isolated and structurally characterized.21 This
Co(IV) complex bears a phenyl axial ligand and is repre-
sented as (OEC)Co(C6H5). Other Co(IV) corroles have been
generated in situ and characterized by ESR, one example of
which is a singly electro-oxidized triphenylphosphine deriva-
tive,7 represented as [[Et8(p-ClPh)3Cor]CoIVPPh3]+. It is
worthy to note that a high-valence cobalt corrole was first
hypothesized in 1973 by Johnson and co-workers in the case
of (Et2Me6Cor)Co(C6H5).26 This latter derivative was pre-
pared by reaction of the cobalt(III) corrole with PhLi.
However, in the absence of spectroscopic and structural data,
the green isolated complex was erroneously interpreted as
the N(21)-phenyl derivative of the Co(II) species.26
calcd for C89H71N8CoFe. UV-vis (CH2Cl2), λmax (nm) (ꢀ × 10-3
,
mol-1 L cm-1): 371.9 (138), 519.5 (18.1), 643.4 (5.9). UV-vis
(neat pyridine), λmax (nm) (ꢀ × 10-3, mol-1 L cm-1): 376.0 (125),
522.0 (16.3), 541.9 (16.1). IR (CsI) ν, cm-1: 3048 (C-H), 3016
(C-H), 2966 (C-H), 2868 (C-H), 349 (Fe-Cl).
1-(Chloro-iron-2,3,7,8,12,18-hexamethyl-13,17-diethylpor-
phyrin-5-yl)-8-(chloro-cobalt-2,3,17,18-tetraphenyl-7,8,12,13-
tetramethylcorrol-10-yl)anthracene, (PCA)FeClCoCl (7). (PCA)-
FeClCoCl, 7, was prepared in 36% yield (36 mg, 0.024 mmol) as
described for (PCB)FeClCoCl, 6, starting from (PCA)H2Co (90 mg,
0.067 mmol, 1 equiv) and FeBr2 (36.2 mg, 0.168 mmol, 2.5 equiv).
MS (MALDI/TOF) m/z: 1427.18 [M - Cl]+•, 1427.43 calcd for
C91H73N8CoFeCl; 1392.01 [M - 2Cl]+, 1392.46 calcd for C91H73N8-
CoFe. UV-vis (CH2Cl2), λmax (nm) (ꢀ × 10-3, mol-1 L cm-1):
383.4 (106), 509.1 (19.4), 641.5 (7.98). UV-vis (neat pyridine),
λ
max (nm) (ꢀ × 10-3, mol-1 L cm-1): 405.9 (133), 512 (16.9), 551
(17.0), 601 (31.6). IR (CsI) ν, cm-1: 3055 (C-H), 2964 (C-H),
2926 (C-H), 2867 (C-H), 354 (Fe-Cl).
Synthesis of Pacman Heterobimetallic Porphyrin-
Corrole Dyads Containing a High-Valence Cobalt Cor-
role. The synthesis of the monocobalt precursors (PCY)H2Co
has been previously described.35 The (PCY)MClCoCl het-
erodinuclear derivatives, where Y ) B, X, A, or O and M
4-(Chloro-iron-2,3,7,8,12,18-hexamethyl-13,17-diethylpor-
phyrin-5-yl)-5-(chloro-cobalt-2,3,17,18-tetraphenyl-7,8,12,13-
tetramethylcorrol-10-yl)-9,9-dimethylxanthene, (PCX)FeCl-
CoCl (8). (PCX)FeClCoCl, 8, was prepared in 59% yield (96.2
Inorganic Chemistry, Vol. 44, No. 11, 2005 3975

Guilard et al.
Scheme 1
) Fe(III) or Mn(III), were obtained according to Scheme 1.
The cobalt-manganese complexes were prepared starting
from monometallic (PCY)H2Co by using MnBr2 in refluxing
THF/MeOH. A similar reaction pathway was used for the
(PCY)FeClCoCl complexes. Unexpectedly, stable chloro-
cobalt(IV) derivatives were formed during the workup
process, as shown in Scheme 1. It is worthy to note that the
smooth conditions used during the metalation step (refluxing
the THF/MeOH mixture and using MnBr2 or FeBr2 as
metalation agents) prevent any transmetalation reaction. The
insertion of iron can also be carried out in acetic acid or
pyridine using Fe(OAc)2 or FeSO4, but in those latter cases,
the temperature must be increased up to 100 °C in order to
complete the metalation reaction, thus favoring concomitant
transmetalation reactions, that is, the formation of (PCY)-
Fe2 derivatives.
UV-Visible Spectroscopy. UV-visible data for the
cofacial porphyrin-corrole complexes are given in the
Experimental Section. As previously reported for the related
(PCY)Co2 complexes,16,36,37 the PCB and PCX derivatives
show electronic absorption spectra that are characterized by
a blue-shifted Soret band and red-shifted visible bands as
compared to the PCA and PCO analogues.16 These features
are in good agreement with the cofacial geometry of the
porphyrin and corrole rings and result from a larger interac-
tion between the two metal macrocycles in the case of the
PCB and PCX derivatives, which have a smaller interplanar
distance between the two metal centers.16 The overall
morphology of the UV-vis spectra of the (PCY)FeClCoCl
and (PCY)MnClCoCl complexes closely resembles that of
regular iron and manganese monoporphyrins. For example,
for the case of iron, the spectra in CH2Cl2 consist of a broad
Soret band (372-383 nm) and ill-defined Q bands at ca.
510 and 640 nm. No clear contribution of the corrole
macrocycle is observed because of the lower molar absorp-
tivities of the corrole ring compared to the much more
strongly absorbing porphyrin macrocycle.
are observed at 360-365 nm and 476-479 nm and are
characteristic of a d-type hyperporphyrin character for the
manganese porphyrin. A shoulder occurs at about 400 nm
in the spectra of (PCY)MnClCoCl and can be attributed to
the Soret band of the corrole ring. This is slightly shifted
from the 398 nm Soret band of the cobalt monocorrole, (Me4-
Ph5Cor)Co, under similar solution conditions.
Mass Spectrometry. Mass spectral data are reported in
the Experimental Section. For each complex, the [(PCY)-
MCo] fragment is systematically observed, corresponding
to the loss of the two halide axial ligands. Despite the smooth
ionization mode (MALDI), the molecular peak corresponding
to the presence of the two chloride axial ligands was not
observed, but in the case of the iron derivatives, a less intense
[(PCY)FeClCo] peak was observed. These mass spectrometry
data agree well with the proposed structural arrangement,
that is, the heterobimetallic nature of each compound.
Infrared Spectroscopy. Infrared data are given in the
Experimental Section and give information concerning the
coordination scheme of the Mn(III) and Fe(III) metals. The
bimetallic derivatives (PCY)MClCoCl show characteristic
Mn-Cl and Fe-Cl bands in the ranges 277-279 cm-1 and
349-354 cm-1, respectively, and these data agree well with
those reported for other manganese chloride38 and iron
chloride complexes.39 It is also important to note that the
vibrations of the Mn-Cl and Fe-Cl moieties appear at the
same wavenumbers as those for the mononuclear porphyrins
with the same substitution patterns. These results lead us to
postulate that the Cl- axial ligand is located, as expected,
outside the porphyrin-corrole cavity, a hypothesis which is
confirmed for one of the compounds, (PCB)FeClCoCl, by
an X-ray crystallographic investigation (see following sec-
tions).
ESR Characterization. Two extreme formulations are
possible to describe the heterobimetallic (PCY)MClCoCl
(where M ) Fe or Mn) complexes. The neutral species can
be formulated as a cobalt(IV) corrole, (PCY)MClCoIVCl,
whose unpaired electron is localized on the metal center, or
as a cobalt(III) corrole-cation radical (PC•+Y)MClCoIIICl,
where the unpaired electron is delocalized over the corrole
A similar trend in λmax can be noted for the (PCY)-
MnClCoCl derivatives in CH2Cl2. Two major Soret bands
(36) Guilard, R.; Je´roˆme, F.; Gros, C. P.; Barbe, J.-M.; Ou, Z.; Shao, J.;
Kadish, K. M. C. R. Acad. Sci., Ser. IIb 2001, 4, 245-254.
(37) Je´roˆme, F.; Gros, C. P.; Tardieux, C.; Barbe, J. M.; Guilard, R. New
J. Chem. 1998, 22, 1327-1329.
(38) Boucher, L. J. J. Am. Chem. Soc. 1970, 92, 2725-2730.
(39) Tabard, A. Ph.D. Thesis, Universite´ de Bourgogne, Dijon, 1985.
3976 Inorganic Chemistry, Vol. 44, No. 11, 2005

Heterobimetallic Complexes of Co(IV) Porphyrin-Corrole Dyads
signal at g ≈ 2.00 being overlapped by the main component
of the cobalt part of the spectrum.
It is important to note that the ESR spectra of (PCY)-
FeClCoCl in frozen solutions are quite different from those
of Co(III) porphyrin π-cation radicals, which generally
exhibit sharp isotropic signals (line widths of 50-80 G)
centered at g ≈ 2.00 and have hyperfine splittings due to
the cobalt nucleus of about 5-7 G under the same condi-
tions.12,45,46 Furthermore, the ESR spectra of (PCY)FeClCoCl
in frozen solutions are comparable to those of (OEC)Co-
(C6H5)21 and electrogenerated7 [(OMTP)Co(PPh3)]+, both of
which were proposed to contain a Co(IV) metal ion on the
basis of their respective ESR spectra. Thus, the ESR data
for (PCY)FeClCoCl are in agreement with a formulation of
the neutral complexes containing a Co(IV) central ion, and
this was further confirmed by the X-ray diffraction study
and electrochemical data described in the following sections
of this paper.
Figure 1. ESR spectrum of (PCX)FeClCoCl in toluene solution at 77 K.
Table 1. ESR Data for (PCY)MClCoCl Complexes in Toluene
Solutions at 77 K
(Por)FeIII
(Cor)CoIV
compound
g
g|
g
∆H
(PCB)FeClCoCl
(PCX)FeClCoCl
(PCA)FeClCoCl
(PCO)FeClCoCl
5.45
5.75
5.67
5.69
2.00
2.01
2.00
2.00
115
44
53
110
Only the Co(IV) signal is observed in the ESR spectra of
(PCY)MnClCoCl (Table 1). Indeed, ESR spectra of the
manganese(III) porphyrins are not detectable at the X band
because the microwave quantum is usually too small.47
Although the low intensity of the signals and the absence of
hyperfine splitting do not allow us to thoroughly assign the
ESR resonances, the absence of any signal at room temper-
ature is nevertheless in favor of the presence of a high-
valence Co(IV) corrole complex.
Description of the (PCB)FeClCoCl Molecular Struc-
ture. Lateral and apical views of the (PCB)FeClCoCl
molecular structure are given in Figure 2. Table 2 shows
crystal data and some experimental and refinement details
for the reported crystal structure. Selected bond distances
and angles concerning the coordination geometries of both
metals are summarized in Table 3. Geometrical parameters
describing the molecular conformation of the complex are
given in Table 4.
Macrocycle Conformation. The macrocycles are slightly
distorted in the complex. The largest and the mean atomic
deviations from the porphyrin least-squares mean plane are
0.33 and 0.14 Å, respectively, whereas for the corresponding
corrole moiety, they are 0.20 and 0.08 Å, respectively. The
alternative displacements of the meso carbon atoms (C-meso)
at both sides of the porphyrin mean plane (0.14, -0.20, 0.14,
and -0.09 Å) and those of all of the pyrrole nitrogen atoms
(Npyr) placed at the same side of the mean plane (-0.04,
-0.07, -0.01, and -0.02 Å) indicate a ruffled conformation
for this macrocycle. The corrole moiety shows a slight wave
conformation, exhibiting two adjacent C-meso atoms at the
same side of the least-squares mean plane and the third one
at the other side of the calculated plane (0.04, 0.01, and
-0.08 Å, respectively). For this macrocycle, the Npyr atoms
are also found at the same side of the calculated plane at
0.14, 0.07, 0.02, and 0.03 Å from the latter.
(PCB)MnClCoCl
(PCX)MnClCoCl
(PCA)MnClCoCl
(PCO)MnClCoCl
2.01
2.01
2.01
2.01
85
74
95
80
macrocycle. A mixture of the two states is also possible.
However, a reevaluation40 of the cobalt oxidation state in
(OEC)Co(C6H5) using pulse EPR and ENDOR ruled out an
initial assignment of the compound as being a resonance
hybrid between a Co(IV) corrole and a Co(III) cation
radical21 and suggested that the unpaired electron is delo-
calized both on the cobalt ion and on the macrocycle.40
ESR experiments on (PCY)MClCoCl were carried out at
room temperature and at liquid-nitrogen temperature. No
ESR signals were observed for the iron or manganese
derivatives at room temperature in toluene solutions, as might
be expected for a cation radical. However, ESR spectra could
be obtained in frozen solution, and an example is given in
Figure 1 for (PCX)FeClCoCl in toluene at 77 K, and data
for all of the (PCY)FeClCoCl complexes are given in Table
1.
Two major components are observed in the spectra, one
corresponding to g ) 5.45-5.75 and the other at g ) 2.00-
2.01. A resonance attributable to a Co(IV) metal ion is
observed at g ) 2.01 in the case of (PCX)FeIIIClCoCl with
partially resolved eight-line hyperfine splitting due to the
59Co nucleus. The value of the hyperfine splitting (A ) 16
G) is significantly smaller than the 100-200 G calculated
for a free cobalt(IV) ion41,42 but is comparable to values
reported for other cobalt(IV) complexes (15-25 G).41-44 The
second part of the signal in the low-field region of the
spectrum is attributed to the high-spin iron(III) porphyrin
(perpendicular contribution), the lower-intensity parallel
(40) Harmer, J.; Van Doorslaer, S.; Gromov, I.; Broering, M.; Jeschke,
G.; Schweiger, A. J. Phys. Chem. B 2002, 106, 2801-2811.
(41) Vol’pin, M. E.; Levitin, I. Y.; Sigan, A. L.; Nikitaev, A. T. J.
Organomet. Chem. 1979, 279, 263.
(42) Topich, J.; Halpern, J. Inorg. Chem. 1979, 18, 1339.
(43) Collins, T. J.; Powell, R. D.; Slebodnick, C.; Uffelman, E. S. J. Am.
Chem. Soc. 1991, 113, 9.
(45) Wolberg, A.; Manassen, J. J. Am. Chem. Soc. 1970, 92, 2982-2991.
(46) Kadish, K. M.; Lin, X. Q.; Han, B. C. Inorg. Chem. 1987, 26, 4161-
4167.
(47) Walker, F. A. In The Porphyrin Handbook; Kadish, K. M., Smith, K.
M., Guilard, R., Eds.; Academic Press: New York, 2000; Vol. 5, pp
81-183.
(44) Anson, F.; Collins, J. T.; Coots, R. J.; Gipson, S. L.; Richmond, T.
G. J. Am. Chem. Soc. 1984, 106, 5037.
Inorganic Chemistry, Vol. 44, No. 11, 2005 3977

Guilard et al.
Figure 2. ORTEP view of the heterobimetallic (PCB)FeClCoCl complex: (a) apical and (b) lateral views. Hydrogen atoms are omitted for clarity. Thermal
ellipsoids are drawn at 50% probability level.
Aromatic Spacer. The biphenylene spacer is almost
planar, the largest and the mean atomic deviations from the
calculated mean plane being 0.03 and 0.01 Å, respectively.
The torsion angle value τ(Cmeso,1-Canch,1-Canch,2-Cmeso,2) )
6.3°, where Cmeso,i and Canch,i are the bonded carbon atoms
belonging to the macrocycle i and the linking aromatic unit,
reflects the spacer rigidity in the complex. This lack of
deformation correlates with the relative positions of both
macrocycles, showing a closely eclipsed conformation (see
Figure 2), the average of the four smallest torsion angle
values τ(N1j-M1-M2-N2k) (j, k ) 1- 4) being 9.2°.
Bond Coordination Geometries. The iron and cobalt
atoms are both pentacoordinated, exhibiting a square-
pyramidal coordination where the pyrrole nitrogens occupy
the four basal positions and a chloride counterion is
coordinated in the apical position. In both cases, the metal
lies out of the four-Npyr mean plane, 4Npyr , at 0.13 and 0.42
Å for Co and Fe, respectively. The mean deviations of the
calculated 4Npyr planes are 0.02 and 0.01 Å, indicating their
planar conformation. The difference observed between the
Fe- 4Npyr and Co- 4Npyr distances (∼0.29 Å) correlates
with the expected ionic radii (ir) for Co(IV) and Fe(III)
{ir[Co(IV)] < ir[Fe(III)]}. Indeed, whereas the former ranges
from 0.40-0.53 Å for tetra- to hexa-coordinated complexes,
the latter exhibits ∼0.58 Å for pentacoordinated com-
pounds.48 Therefore, despite the largest porphyrin 4Npyr
cavity, the Fe(III) cation of the porphyrin lies further out of
the 4Npyr mean plane than the Co(IV) cation does in the
(48) Shannon, R. D. Acta Crystallogr., Sect. A 1976, A32, 751-767.
3978 Inorganic Chemistry, Vol. 44, No. 11, 2005

Heterobimetallic Complexes of Co(IV) Porphyrin-Corrole Dyads
Table 2. Crystallographic Data for (PCB)FeClCoCl (6)
105.0°, and an Fe- 4Npyr distance of 0.47 Å, all of them
very similar to those observed here. A slight difference
between the (OEP)Fe(III)Cl complex and the Fe(III)-por-
phyrin moiety of (PCB)FeClCoCl concerns the macrocyclic
conformation. Thus, whereas the former exhibits a closely
planar conformation (the largest and the mean atomic
deviations from the porphyrin mean plane are 0.14 and 0.05
Å, respectively), that of the latter is roughly ruffled, as
discussed above.
chemical formula
fw
(PCB)FeClCoCl‚0.5(C7H16)‚0.5(CH2Cl2)‚2H2O
1566.81
temp, K
wavelength, Å
crystal system
space group
a, Å
110(2)
0.71069
triclinic
P1h
13.8463(3)
16.8164(5)
17.9072(6)
93.780(1)
111.143(1)
97.463(2)
3827.2(2)
2
b, Å
c, Å
R, deg
â, deg
π-π Interactions. As expected, when using the biphen-
ylene group as a linking unit in the face-to-face complexes,
the a-b distance (see Table 4) remains almost constant
(∼3.79 Å) from one compound to another. Indeed, the rigid
nature of the spacer is responsible for this effect. Significant
differences between the d(c-d) and d(a-b) distances can
arise if the coordinated ligands or molecules are located
within the complex cavity, in particular when using either
nonrigid spacers or “longer” spacers such as dibenzofuran
or anthracene.10,30 For the compounds presented in Table 4,
the difference ∆d1 ) d(c-d) - d(a-b) is zero for the face-
to-face homobimetallic (PCB)Cu2 complex, 0.05 Å for the
monometallic (PCB)H2Co(py) complex, and -0.07 Å for the
heterobimetallic (PCB)FeClCoCl complex, indicating that
macrocycles are brought together in the latter case. Paral-
leling this result, the comparison between the other param-
eters characterizing the three molecular structures shows that
the shortest centroid-to-centroid and lateral shift distances
(3.60 and 0.80 Å, respectively) as well as the smallest
interplanar and slip angles (5.0 and 12.8°, respectively)
correspond to (PCB)FeClCoCl. These structural features
seem to indicate the interaction between the porphyrin-
Fe(III)Cl and the corrole-Co(IV)Cl units. As far as both
metal centers are displaced from their 4Npyr mean planes
in opposite directions from the (PCB)FeClCoCl complex
cavity, leading to an Fe‚‚‚Co distance (4.13 Å) greater than
that of Ct1‚‚‚Ct2 [∆d2 ) d(Fe‚‚‚Co) - d(Ct1‚‚‚Ct2) ) 0.53
Å], it seems to follow that the interactions between both
monometalated moieties are driven by π-π rather than by
metal-metal interactions. In addition, the eclipsed conforma-
tion between both face-to-face macrocyclic moieties ( τ )
9.2°, as reported above) and the interplanar angles observed
between the macrocycles’ mean planes and the rigid spacer
(66.5 and 69.0°), indicating the deviation from right angles
and therefore the approach between the macrocyclic units,
further support the consideration of π-π interactions in the
crystalline (PCB)FeClCoCl structure. However, in contrast
to the crystalline state no evidence for this interaction was
detected in the frozen solution ESR spectra.
γ, deg
vol, Å3
Z
µ, mm-1
cryst size, mm3
collected reflns
unique reflns
Rint
0.568
0.37 × 0.18 × 0.13
25 659
13 889
0.0453
θ
max, deg
25.44
refinement method
data/params
full-matrix least-squares on F2
13 889/1049
1.048
GOF on F2
R1/wR2a [I > 2σ(I)]
R1/wR2a (all data)
∆Fmax/∆Fmin, e Å-3
0.0812/0.2062
0.1182/0.2273
1.861/-1.231
2 2
a R1 ) Σ||Fo - Fc||/Σ |Fo| and wR2 ) {Σ [w(Fo2 - Fc2)2]/Σ [w(Fo ) ]}1/2
.
Table 3. Selected Bond Distances and Angles for (PCB)FeClCoCl
Co(1)-N(1)
1.868(4)
1.870(4)
1.876(4)
1.879(4)
2.275(2)
2.056(4)
2.063(4)
2.065(4)
2.074(4)
2.250(2)
96.6(1)
92.1(1)
94.9(1)
92.5(1)
101.3(1)
102.8(1)
99.8(1)
Co(1)-N(4)
Co(1)-N(2)
Co(1)-N(3)
Co(1)-Cl(1)
Fe(1)-N(8)
Fe(1)-N(6)
Fe(1)-N(7)
Fe(1)-N(5)
Fe(1)-Cl(2)
N(1)-Co(1)-Cl(1)
N(4)-Co(1)-Cl(1)
N(2)-Co(1)-Cl(1)
N(3)-Co(1)-Cl(1)
N(8)-Fe(1)-Cl(2)
N(6)-Fe(1)-Cl(2)
N(7)-Fe(1)-Cl(2)
N(5)-Fe(1)-Cl(2)
102.9(1)
corrole, leading to longer metal-Npyr distances in the former
case (2.06-2.07 Å compared to 1.87-1.88 Å). In addition,
although the Co-Cl and Fe-Cl distances remain close to
each other (2.275 and 2.250 Å, respectively), the Cl-metal-
Npyr angles are systematically larger for Fe(III) (99.8-102.9°
compared to 92.1-96.6°). The Co(IV)-Npyr distances and
Cl-Co(IV)-Npyr angles are similar to those found for the
unique Co(IV)-corrole structure reported in the literature,
(OEC)Co(C6H5),21 which also exhibits a pentacoordinated
geometry and shows 1.84 < d[Co(IV)-Npyr] < 1.87 Å and
93.9 < R[apical ligand-Co(IV)-Npyr] < 97.3°. In this latter
molecular structure, the macrocycle conformation is close
to that of the actual corrole moiety, and the cobalt to 4Npyr
plane distance is only 0.05 Å larger than that observed here.
On the other hand, closely related to the porphyrin-Fe(III)-
Cl unit is the (OEP)Fe(III)Cl complex,49 which shows Fe-
Npyr and Fe-Cl distances of 2.06-2.07 and 2.23 Å,
respectively, Cl-Fe-Npyr angles ranging from 100.3 to
Electrochemistry. The electrochemistry of the porphyrin-
corrole dyads was investigated in PhCN containing 0.1 M
TBAP, and comparisons were then made to that of the related
unlinked Co(III) corrole and Fe(III) or Mn(III) porphyrin
under the same solution conditions. An example of such a
comparison is shown in Figure 3, which illustrates cyclic
voltammograms for two of the four Co(IV) corrole dyads
(PCO and PCB) along with those of (Me4Ph5Cor)CoIII and
(Et2Me6PhPor)FeIIICl.
(49) Senge, M. O. Private communication to CCDC, 1997, CCDC-100243.
Inorganic Chemistry, Vol. 44, No. 11, 2005 3979

Guilard et al.
Table 4. Selected Structural Data for (PCB)FeClCoCl, 6, and Related Complexesa
compound
d(Ct1-Ct2) (Å)
d(M-M)
R (deg)
L (Å)
â (deg)
d(a-b) (Å)
d(c-d) (Å)
∆d1
ref
(PCB)FeClCoCl, 6
(PCB)H2Co(py)
(PCB)Cu2
3.60
4.19
3.73
4.13
-
3.63
12.8
33.1
23.5
0.80
2.29
1.49
5.0
6.4
5.3
3.78
3.79
3.79
3.71
3.84
3.79
-0.07
0.05
0
this work
35
30
a Macrocyclic centers (Cti) were calculated as the barycenters of the 4N planes for each macrocycle. The slip angle (R) was calculated as the average
angle between the Ct1-Ct2 vector joining the two rings and the unit vectors normal to the two macrocyclic CMP and PMP least-squares planes [R ) (R1
+ R2)/2]. The lateral shift (L) is defined as sinR × d(Ct1-Ct2). The interplanar angle â was measured as the angle between the two macrocyclic CMP and
PMP least-squares planes. The a-b and c-d distances are defined on the other side. ∆d1 ) d(c-d) - d(a-b).
The unlinked Co(III) and Fe(III) macrocycles exhibit two
or three oxidations and two or three reductions, as shown in
Figure 3a,b. The same electrode processes occur for (PCO)-
FeClCoIVCl and (PCB)FeClCoIVCl, which exhibit four or five
redox couples between 0.0 and 1.6 V and four or five redox
couples between 0.0 and -2.0 V (Figure 3c,d). The one-
electron reduction of the Co(IV) dyad to Co(III) and its one-
electron oxidation to give a Co(IV) π-cation radical are
located at E1/2 ) 0.49 and 0.77 V (PCO) and E1/2 ) 0.44
and 0.70 V (PCB), respectively, and can be compared with
similar oxidation potentials for the Co(III) monocorrole at
E1/2 ) 0.47 and 0.72 V, thus indicating that these oxidation/
reduction processes of the dyads occur on the cobalt corrole
unit.
Additional one-electron oxidations of the PCO and PCB
complexes are located between 0.97 and 1.37 V and are close
to the half-wave potentials for the oxidation of (Et2Me6-
PhPor)FeCl, that is, 1.03 and 1.34 V (Figure 3b). Slightly
easier oxidations are seen for (PCB)FeClCoCl (0.97 and 1.24
V) than for (PCO)FeClCoCl (1.04 and 1.34 V), but in both
cases, these two processes clearly occur on the iron porphyrin
part of the dyad.
Half-wave potentials for the reductions of the Co(III)
corrole dyads electrogenerated at 0.00 V are also similarly
combined to overlapped E1/2 values for the reduction of the
Co(III) monocorrole and the reduction of the Fe(III)
monoporphyrin, and on the basis of this similarity, the
stepwise sites for these electron additions can unambiguously
be assigned, in the case of (PCO)FeClCoCl, as the Co(III)/
Co(II) reaction of the corrole (-0.17 V), the Fe(III)/Fe(II)
reaction of the porphyrin (-0.42 V), further reduction of
the porphyrin (-1.22 V), and then further reduction of the
corrole (-1.65 V). The same order of electron additions is
also seen for (PCB)FeClCoCl, which undergoes an additional
one-electron reduction at -1.76 V. This latter reversible
reaction can be compared to a similar porphyrin-centered
redox reaction of (Et2Me6PhPor)FeCl, which is located at
-1.96 V versus SCE (see Figure 3b).
Comparative cyclic voltammograms are shown in Figure
4 for two of the four Mn(III) porphyrin dyads (PCA and
PCB). The voltammograms for the manganese porphyrins
are generally less well-defined because of several equilibria
involving Cl- (see discussion below), but the trends are
similar between the two series of Mn(III) and Fe(III) dyads,
especially as they apply to the Co(III)/Co(II) and Co(IV)/
Co(III) processes of these face-to-face complexes. As
observed earlier in the case of (PCY)Co2, the Co(III)/Co(II)
process is shifted toward more negative potentials as
compared to what is seen for the monomeric Co(III)
macrocycle,5,17 with the easiest metal-centered reduction
being observed for dyads with the dibenzofuran (O) bridge
and the hardest for those with the biphenylenyl (B) bridge
(see E1/2 values in Table 5).
Perhaps the most significant point that emerges from the
data in Figures 3 and 4 is the fact that the Co(IV)/Co(III)
process occurs in two steps for the investigated dyads. The
more positive Co(IV) reduction process is reversible and
located at E1/2 values between 0.43 and 0.49 V [as compared
to 0.47 V for the oxidation of the Co(III) monomer]. In
contrast, the more negative Co(IV)/Co(III) process is ir-
Figure 3. Cyclic voltammograms of (a) (Me4Ph5Cor)Co, (b) (Et2Me6-
PhPor)FeCl, (c) (PCO)FeClCoCl, and (d) (PCB)FeClCoCl in PhCN
containing 0.1 M TBAP.
3980 Inorganic Chemistry, Vol. 44, No. 11, 2005

Heterobimetallic Complexes of Co(IV) Porphyrin-Corrole Dyads
Figure 4. Cyclic voltammograms of (a) (Et2Me6PhPor)MnCl, (b) (PCA)MnClCoCl, and (c) (PCB)MnClCoCl in PhCN containing 0.1 M TBAP.
Table 5. Half-Wave Potentials (V vs SCE) for Metal-Centered Reactions of Corroles and Porphyrin-Corrole Dyads in PhCN Containing 0.1 M TBAP
reactions of cobalt corrole
CoIVCl/CoIII
reactions of porphyrina
compound
spacer
CoIV(ClO4)/CoIII
0.47
CoIII/CoII
MIII/MII
MII/MIII
(Me4Ph5Cor)Cob
(Me2Et6PhPor)FeCl
(PCO)FeClCoCl
(PCA)FeClCoCl
(PCB)FeClCoCl
(Me2Et6PhPor)MnCl
(PCO)MnClCoCl
(PCA)MnClCoCl
(PCX)MnClCoCl
(PCB)MnClCoCl
-0.16
-0.44
-0.42
-0.57
-0.44
-0.49
O
A
B
0.49
0.43
0.44
0.15c
0.14c
0.07c
-0.17
-0.24
-0.35
-0.34
-0.34
-0.43
O
A
X
B
0.46
0.44
0.43
0.46
0.18c
0.22c
0.11c
0.10c
-0.17
-0.22
-0.30
-0.29
-0.65
a Listed potentials are reversible E1/2 values for Fe/Co complexes, whereas listings for the Mn/Co derivatives give the cathodic and anodic peak potentials,
Epc and Epa, for a scan rate of 0.1 V/s (see Figures 3 and 4). b Data taken from ref 16. c Peak potentials at a scan rate of 0.1 V/s.
reversible, significantly reduced in current, and located at
Ep values from 0.07 to 0.22 V for a scan rate of 0.1 V/s (see
Table 5). As will be demonstrated, the reversible couple
corresponds to a Co(IV)/Co(III) process where Cl- on the
original compound has been dissociated and most likely
replaced by ClO4- from the supporting electrolyte, whereas
the more negative peak process at Ep ) 0.07 to 0.22 V is
assigned to a reduction of CoIVCl to CoIII from the initial
(PCY)MClCoCl species added to the solution. The fact that
the current for the irreversible reaction is reduced in
magnitude compared to that of the more positive Co(IV)/
Co(III) processes can be accounted for, in part, because the
reducing the concentration of (PCY)FeClCoCl at the elec-
trode surface.
(PCY)MClCoCl + ClO4- h (PCY)MClCoClO4 + Cl-
(1)
To further investigate the effect of Cl- on the electrode
reactions of (PCY)MIIIClCoIVCl, we limited our scan range
to potentials where only the Co(IV)/Co(III) and Co(III)/
Co(II) processes are seen (+0.6 to -0.4 V) and then
characterized the electrochemistry of the dyads in PhCN,
containing 0.1 M TBAP, before and after the addition of
excess Cl- in the form of TBACl. These results are discussed
below and provide clear evidence for the binding of Cl- to
the Co(IV) of (PCY)MClCoCl as well as, in some cases, to
the electrogenerated Co(III) form of the corrole.
-
ClO4 -bound species is easier to reduce than the Cl-
derivative by over 300 mV and, thus, preferentially occurs,
and in part because ClO4- (from the supporting electrolyte)
is present in an excess concentration 100 times that of Cl-,
thus shifting the equilibrium given by eq 1 to the right and
Electrochemistry of Co(IV) Dyads With and Without
Added Cl-. The electrochemistry of all Co(IV) dyads
Inorganic Chemistry, Vol. 44, No. 11, 2005 3981

Guilard et al.
Figure 5. Cyclic voltammograms of (PCO)MClCoCl, (PCA)MClCoCl, and (PCB)MClCoCl derivatives in PhCN containing 0.1 M TBAP.
known to bind halide axial ligands.50 In the present case,
the reduction of (PCY)MClCoCl proceeds via the top
pathway in Scheme 2 and is followed by a rapid loss of Cl-
to give the four-coordinate Co(III) corrole, which is then
reoxidized via the lower pathway to give CoIVClO4 (an
electrochemical EC mechanism).51 This gives rise to the
cyclic voltammograms shown in Figure 5.
Scheme 2
containing Mn(III) or Fe(III) porphyrins are generally similar
to each other as far as the Co(IV)/Co(III) processes are
concerned, and the cyclic voltammograms resemble, in large
part, what has been described above for the (PCY)FeClCoCl
and (PCY)MClCoCl derivatives in Figures 3 and 4. Two
distinct Co(IV)/Co(III) processes are observed in each case,
the first of which corresponds to the reduction of a Co(IV)
ion not containing Cl- (here, assigned as CoIVClO4) and the
second corresponds, at more negative potentials, to a CoIV-
Cl/CoIII process. In all cases, the anodic oxidation peak
potential for the CoIII/CoIVClO4 process ranges from 0.46 to
0.49 V and varies little with the type of spacer. This is not
the case for the cathodic peak assigned to CoIVCl/CoIII. Here,
Ep ranges between 0.20 and 0.07 V (for a scan rate of 0.1
V/s) and varies with the type of metal ion and type of spacer
in the complexes. This is seen by the cyclic voltammograms
illustrated in Figure 5.
The dyads added to the solution, (PCY)MClCoCl, initially
contain CoIVCl, but significant amounts of CoIVClO4 may
be formed after reduction to Co(III) and reoxidation to
Co(IV). Significant amounts of CoIVClO4 may also be formed
prior to electron transfer, as described in eq 1 and also shown
by the left-hand equilibria in Scheme 2.
The equilibrium in eq 1 and Scheme 2 can also be shifted
toward CoIVCl by the addition of excess Cl- in the form of
TBACl, and this is demonstrated by the voltammograms
shown in Figure 6 for the case of (PCB)MnClCoCl. As seen
in this figure, the addition of 1.0 equiv of TBACl to the
solution leads to a complete disappearance of the first
reduction peak at ∼0.40 V, and this is replaced by a well-
defined Co(IV)/Co(III) process peak at Ep ) 0.09 V. Under
these solution conditions, the electroreduction primarly
(50) Kadish, K. M.; Royal, G.; Van Caemelbecke, E.; Gueletti, L. In The
Porphyrin Handbook; Kadish, K. M., Smith, K. M., Guilard, R., Eds.;
Academic Press: San Diego, CA, 2000; Vol. 9, pp 1-219.
(51) Bard, A. L.; Faulkner, L. R. Electrochemicals Methods and Funda-
mentals and Applications, 2nd ed.; John Wiley & Sons: New York,
2000.
The data in Figure 5 is easily interpretable in terms of the
classic “box pathway” shown in Scheme 2 for the reduction
and reoxidation of the Co(IV) corrole center and has been
observed for the reduction of a large number of porphyrins
3982 Inorganic Chemistry, Vol. 44, No. 11, 2005

Heterobimetallic Complexes of Co(IV) Porphyrin-Corrole Dyads
Figure 6). Similar Co(IV)/Co(III) potentials are observed for
all of the dyads in PhCN containing excess Cl-, and here,
the electrode reactions occur as shown in eq 2 or eq 3,
depending upon the specific macrocycle and the concentra-
tion of added Cl-.
(PCY)MClCoIVCl + e- h [(PCY)MClCoIIICl]- (2)
[(PCY)MClCoIVCl2]- + e- h [(PCY)MClCoIIICl]- + Cl-
(3)
A detailed study of chloride binding by the dyads is
beyond the scope of the present paper, but it should here be
pointed out that in all cases, the Co(IV)/Co(III) reductions
become reversible and are located at potentials between 0.09
and 0.12 V versus SCE in PhCN solutions containing 0.1 M
TBAP and excess Cl- in the form of TBACl. At the same
time, there remains no evidence for a process involving the
conversion of CoIVClO4 to CoIII, because the equilibrium in
eq 1 has been shifted completely to the form of the Co(IV)
corrole containing one or two bound Cl- ions.
In summary, we have utilized electrochemistry, ESR
spectroscopy, and X-ray crystallography to unambiguously
characterize a series of linked dyads containing a Co(IV)
corrole and an Fe(III) or Mn(III) porphyrin. These com-
pounds may possess properties quite different from those
containing Co(III) corroles, and these types of species are
now being investigated with respect to their reactions with
small molecules.
Acknowledgment. The support of the Robert A. Welch
Foundation (K.M.K., Grant E-680) and the French Ministry
of Research (MENRT), CNRS (UMR 5633), are gratefully
acknowledged. The “Re´gion Bourgogne” and “Air Liquide”
company are acknowledged for scholarships (F.B.), and the
authors are also grateful to M. Soustelle for the synthesis of
pyrrole and dipyrromethane precursors.
Figure 6. Cyclic voltammograms of 4.5 × 10-4 M (PCB)MnClCoCl in
PhCN containing 0.1 M TBAP with 0-40 equiv of TBACl.
follows the upper pathway in Scheme 2, that is, CoIVCl f
CoIIICl, and this is followed by a slow loss of Cl- on the
electrochemical time scale to give CoIII. The four-coordinate
species is then reoxidized at Ep ) 0.39 V to give [CoIV]+,
or CoIVClO4, which then rapidly binds Cl- to reform CoIV-
Cl, as shown in Scheme 2.
Further additions of TBACl to the solution result in a more
reversible CoIVCl/CoIIICl process and the complete dis-
appearance of the couple assigned to CoIVClO4/CoIII (see
Supporting Information Available: The X-ray crystallographic
file in CIF format for the structure determination of (PCB)-
FeClCoCl‚0.5(C7H16)‚0.5(CH2Cl2)‚2H2O has been deposited at the
CCDC, and is available upon request from the Director of the
Cambridge Crystallographic Data Center, 12 Union Road, GB-
Cambridge CN2 1EZ, U. K., upon quoting the full journal citation.
This material is available free of charge via the Internet at
http://pubs.acs.org.
IC0501622
Inorganic Chemistry, Vol. 44, No. 11, 2005 3983