Alkyl and aryl substituted corroles. 2. Synthesis and characterization of linked face-to-face biscorroles. X-ray structure of (BCA)Co2(py)3, where BCA represents a biscorrole with an anthracenyl bridge

Article abstract of DOI:10.1021/ic0101782

The synthesis, spectroscopic properties, and electrochemistry of (BCA)C_O2 and (BCB)C_O2 are described where BCA and BCB represent biscorroles linked by an anthracenyl (A) or a biphenylenyl (B) bridge. The pyridine and CO binding properties of (BCA)C_O2 and (BCB)C_O2 are also presented, and one of the compounds in its pyridine-ligated form, (BCA)C_O2(py)₃, is structurally characterized. The data on the biscorroles are compared on one hand to the monocorrole having the same substitution pattern and on the other hand to bisporphyrins having two C_O(II) ions and the same anthracenyl or biphenylenyl linkers in order to better understand the interaction which occurs between the two corrole macrocycles. A parallel study on five different C_O(III) phenyl-substituted corroles showed that bis-pyridine and mono-CO adducts are readily formed from the complexes in CH₂Cl₂. This present paper examines how the ligand binding properties and electrochemistry of these Co(III) corroles are modified by the anthracenyl or biphenylenyl bridge which links the two macrocycles in a face to face orientation. An X-ray crystal structure was obtained for the tris-pyridine adduct of the anthracenyl bridged derivative, (BCA)C_O2(py)₃, and gives the following results: C₁₂₇H₉₉C_O2N₁₁ ·2CHCl₃, M = 2135.90, triclinic, space group P1, a = 13.2555(5) A, b = 18.6406(8) A, c = 22.2140(9) A, α = 94.186(9)°, β = 102.273(9)° γ = 94.205(9)° V = 5326.8(4) A³, 9293 independent reflections collected, R(F) = 0.066.

Full text of DOI:10.1021/ic0101782

4856
Inorg. Chem. 2001, 40, 4856-4865
Alkyl and Aryl Substituted Corroles. 2. Synthesis and Characterization of Linked
“Face-to-Face” Biscorroles. X-ray Structure of (BCA)Co2(py)3, Where BCA Represents a
Biscorrole with an Anthracenyl Bridge
Roger Guilard,*,† Franc¸ois Je´roˆme,† Jean-Michel Barbe,† Claude P. Gros,† Zhongping Ou,‡
Jianguo Shao,‡ Jean Fischer,§ Raymond Weiss,*,§ and Karl M. Kadish*,‡
LIMSAG UMR 5633, Faculte´ des Sciences Gabriel, Universite´ de Bourgogne, 6, Boulevard Gabriel,
21000 Dijon, France, Department of Chemistry, University of Houston, Houston, Texas 77204-5641,
and Institut Le Bel, Universite´ Louis Pasteur, 4, Rue Blaise Pascal, 67000 Strasbourg, France
ReceiVed February 9, 2001
The synthesis, spectroscopic properties, and electrochemistry of (BCA)Co2 and (BCB)Co2 are described where
BCA and BCB represent biscorroles linked by an anthracenyl (A) or a biphenylenyl (B) bridge. The pyridine and
CO binding properties of (BCA)Co2 and (BCB)Co2 are also presented, and one of the compounds in its pyridine-
ligated form, (BCA)Co2(py)3, is structurally characterized. The data on the biscorroles are compared on one hand
to the monocorrole having the same substitution pattern and on the other hand to bisporphyrins having two Co(II)
ions and the same anthracenyl or biphenylenyl linkers in order to better understand the interaction which occurs
between the two corrole macrocycles. A parallel study on five different Co(III) phenyl-substituted corroles showed
that bis-pyridine and mono-CO adducts are readily formed from the complexes in CH2Cl2. This present paper
examines how the ligand binding properties and electrochemistry of these Co(III) corroles are modified by the
anthracenyl or biphenylenyl bridge which links the two macrocycles in a face to face orientation. An X-ray
crystal structure was obtained for the tris-pyridine adduct of the anthracenyl bridged derivative, (BCA)Co2(py)3,
and gives the following results: C127H99Co2N11‚2CHCl3, M ) 2135.90, triclinic, space group P1h, a ) 13.2555(5)
Å, b ) 18.6406(8) Å, c ) 22.2140(9) Å, R ) 94.186(9)°, â ) 102.273(9)°, γ ) 94.205(9)°, V ) 5326.8(4) Å3,
9293 independent reflections collected, R(F) ) 0.066.
Introduction
Among these latter derivatives are the cofacial bisporphyrin
systems with anthracenyl or biphenylenyl spacers, the so-called
“Pacman” porphyrin systems (DPA)H4 and (DPB)H4, where
DPA and DPB represent bisporphyrins with anthracenyl (A) or
biphenylenyl (B) bridges.8-15,20,21
Model cofacial bisporphyrins can generally be grouped into
two types of compounds, those linked on opposite sides of each
macrocycle with two flexible strapping units1-7 and those linked
on only one side of each macrocycle by a rigid linking unit.8-19
The great importance assumed by bisporphyrins in oxygen
activation9,22-28 and the parallel development of corrole
† Universite´ de Bourgogne.
‡ University of Houston.
§ Universite´ Louis Pasteur.
(13) Guilard, R.; Lopez, M. A.; Tabard, A.; Richard, P.; Lecomte, C.;
Brande`s, S.; Hutchison, J. E.; Collman, J. P. J. Am. Chem. Soc. 1992,
114, 9877-9889.
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10.1021/ic0101782 CCC: $20.00 © 2001 American Chemical Society
Published on Web 08/17/2001

Linked “Face-to-Face” Biscorroles
Inorganic Chemistry, Vol. 40, No. 19, 2001 4857
Chart 1
chemistry29-47 have provided a stimulation to synthesize corrole
dyads with transition metals.30,48,49 Indeed, corroles can be
considered as intermediates between corrins and porphyrins
since they present a direct link between two pyrroles and retain
an 18 π-electron aromatic system.
Recently, we reported, in a preliminary communication, the
first synthesis of sterically hindered cofacial biscorroles (BCA)-
H6 and (BCB)H6, where BCA and BCB represent biscorroles
with anthracenyl (A) or biphenylenyl (B) bridges.48,49 We now
report the full synthesis and spectroscopic properties of these
face-to-face biscorroles, which are shown in Chart 1. The ligand
binding and electrochemical properties of (BCB)Co2, 8b, and
(BCA)Co2, 8a, are also presented, and one of the compounds
in its pyridine-ligated form, (BCA)Co2(py)3, is structurally
characterized. These data are then compared to a related
monocorrole having the same substitution pattern in order to
better understand the interaction between the two sets of
macrocycles. A parallel study on five different Co(III) phenyl-
substituted corroles shows that bis-pyridine and mono-CO
adducts are readily formed in CH2Cl2.50 This present paper
examines how ligand binding properties for a specific Co(III)
corrole are modified by the anthracenyl or biphenylenyl bridge
which links the two macrocycles in a face to face orientation.
(26) Le Mest, Y.; L'Her, M.; Saillard, J. Y. Inorg. Chim. Acta 1996, 248,
181-191.
(27) Le Mest, Y.; Inisan, C.; Laouenan, A.; L'Her, M.; Talarmin, J.; El
Kalifa, M.; Saillard, J.-Y. J. Am. Chem. Soc. 1997, 119, 6095-6106.
(28) Liu, H.-Y.; Abdalmuhdi, I.; Chang, C. K.; Anson, F. C. J. Phys. Chem.
1985, 89, 665-670.
(29) Erben, C.; Will, S.; Kadish, K. M. In The Porphyrin Handbook; Kadish,
K. M., Smith, K. M., and Guilard, R., Eds.; Academic Press: San
Diego, CA, 2000; Vol. 2, pp 233-300.
(30) Paolesse, R. In The Porphyrin Handbook; Kadish, K. M., Smith, K.
M., and Guilard, R., Eds.; Academic Press: San Diego, CA, 2000;
Vol. 2, pp 201-232.
(31) Kadish, K. M.; Will, S.; Adamian, V. A.; Walther, B.; Erben, C.; Ou,
Z.; Guo, N.; Vogel, E. Inorg. Chem. 1998, 37, 4573-4577.
(32) Kadish, K. M.; Adamian, V. A.; Van Caemelbecke, E.; Gueletii, E.;
Will, S.; Erben, C.; Vogel, E. J. Am. Chem. Soc. 1998, 120, 11986-
11993.
(33) Autret, M.; Will, S.; Van Caemelbecke, E.; Lex, J.; Gisselbrecht, J.-
P.; Gross, M.; Vogel, E.; Kadish, K. M. J. Am. Chem. Soc. 1994,
116, 9141-9149.
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Gisselbrecht, J.-P.; Gross, M.; Vogel, E.; Kadish, K. M. Inorg. Chem.
1996, 35, 184-192.
Experimental Section
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E.; Paolesse, R.; Boschi, T.; Kadish, K. M. Inorg. Chem. 1995, 34,
532-540.
Instrumentation. 1H NMR spectra were recorded on a Bruker AC
200 Fourier transform spectrometer at the Centre de Spectrome´trie
Mole´culaire de l’Universite´ de Bourgogne; chemical shifts are expressed
in parts per million relative to chloroform (7.258 ppm). Microanalyses
were performed at the Universite´ de Bourgogne on a Fisons EA 1108
CHNS instrument. UV-visible spectra were recorded on a Varian Cary
1 spectrophotometer. Mass spectra were obtained with a Kratos Concept
32 S spectrometer in EI or LSIMS (m-NBA as matrix) modes. 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 was
separated from the bulk of the solution by a fritted-glass bridge of low
porosity which contained the solvent/supporting electrolyte mixture.
All potentials are referenced to the SCE.
(36) Kadish, K. M.; Lin, X. Q.; Han, B. C. Inorg. Chem. 1987, 26, 4161-
4167.
(37) Kadish, K. M.; Koh, W.; Tagliatesta, P.; Sazou, D.; Paolesse, R.;
Licoccia, S.; Boschi, T. Inorg. Chem. 1992, 31, 2305-2313.
(38) Will, S.; Lex, J.; Vogel, E.; Adamian, V. A.; Van Caemelbecke, E.;
Kadish, K. M. Inorg. Chem. 1996, 35, 5577-5583.
(39) Kadish, K. M.; Erben, C.; Ou, Z.; Adamian, V. A.; Will, S.; Vogel,
E. Inorg. Chem. 2000, 39, 3312-3319.
(40) Cho, W.-S.; Lee, C.-H. Tetrahedron Lett. 2000, 41, 697-701.
(41) Ghosh, A.; Wondimagegn, T.; Parusel, A. B. J. J. Am. Chem. Soc.
2000, 122, 5100-5104.
(42) Gross, Z.; Simkhovich, L.; Galili, N. Chem. Commun. 1999, 599-
600.
(43) Gross, Z.; Galili, N.; Saltsman, I. Angew. Chem., Int. Ed. Engl. 1999,
38, 1427-1429.
(44) Gross, Z.; Galili, N. Angew. Chem., Int. Ed. Engl. 1999, 38, 2366-
UV-visible spectroelectrochemical experiments were performed
with an optically transparent platinum thin-layer electrode of the type
described in the literature.51 Potentials were applied with an EG&G
model 173 potentiostat. Time-resolved UV-visible spectra were
recorded with a Hewlett-Packard model 8453 diode array rapid-scanning
spectrophotometer. Infrared spectra were recorded on an FTIR Nicolet
2369.
(45) Gross, Z.; Galili, N.; Simkhovich, L.; Saltsman, I.; Botoshansky, M.;
Bla¨ser, D.; Boese, R.; Goldberg, I. Org. Lett. 1999, 1, 599-602.
(46) Simkhovich, L.; Goldberg, I.; Gross, Z. J. Inorg. Biochem. 2000, 80,
235-238.
(47) Simkhovich, L.; Galili, J.; Saltsman, I.; Goldberg, I.; Gross, Z. Inorg.
Chem. 2000, 39, 2704-2705.
(48) Je´roˆme, F.; Gros, C. P.; Tardieux, C.; Barbe, J.-M.; Guilard, R. Chem.
Commun. 1998, 2007-2008.
(50) Guilard, R.; Gros, C. P.; Bolze, F.; Je´roˆme, F.; Ou, Z.; Shao, J.; Fischer,
J.; Weiss, R.; Kadish, K. M. Inorg. Chem. 2001, 40, 4845-4855.
(51) Lin, X. Q.; Kadish, K. M. Anal. Chem. 1985, 57, 1498-1501.
(49) Guilard, R.; Je´roˆme, F.; Gros, C. P.; Barbe, J. M.; Ou, Z.; Shao, J.;
Kadish, K. M. C. R. Acad. Sci., Se´r. 2 2001, 245-254.

4858 Inorganic Chemistry, Vol. 40, No. 19, 2001
Guilard et al.
3
3
Magna-IR 550 spectrometer. The background was obtained by recording
the IR spectrum of CH2Cl2 saturated with CO and the IR spectrum of
the compound under CO was obtained after bubbling CO through the
solution for 10-15 min.
Chemicals and Reagents. Absolute dichloromethane (CH2Cl2) and
pyridine (py) were obtained from Fluka Chemical Co. and used as
received. 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. Compounds 1a, 1b, 2, and 5 were
synthesized as described elsewhere.21,48
1,8-Bis(5,5′-ethoxycarbonyl-4,4′-diethyl-3,3′-dimethyldipyrro-
methan-5-yl)anthracene (3a). A mixture of 1 g of 1,8-diformylan-
thracene (1a) (4.3 mmol) and 3.25 g of 5-ethoxycarbonyl-4-ethyl-3-
methylpyrrole (2) (18 mmol) was dissolved in 60 mL of hot ethanol.
A 3 mL aliquot of concentrated hydrochloric acid were then added,
and the mixture was stirred under reflux for 5 h. The reaction medium
was cooled to room temperature, and the resulting solid was filtered
and washed by cold methanol and then dried to give the title product
3a (3.35 g, 85%). 1H NMR: δ 8.49 (s, 4H), 8.48 (s, 1H), 8.32 (s, 1H),
7.95 (d, 2H, 3JH-H ) 8.0 Hz), 7.33 (dd, 2H, 3JH-H ) 8.0 Hz), 6.92 (d,
2H, 3JH-H ) 8.0 Hz), 5.85 (s, 2H), 4.19 (q, 8H, 3JH-H ) 6.0 Hz), 3.68
(q, 8H, 3JH-H ) 8.0 Hz), 1.60 (s, 12H), 1.24 (t, 12H, 3JH-H ) 8.0 Hz),
1.05 (t, 12H, 3JH-H ) 8.0 Hz). MS: m/z ) 922 [M]•+. Anal. Calcd for
C56H66N4O8: C, 72.86; H, 7.21; N, 6.07. Found: C, 72.76; H, 7.29;
N, 5.99.
14.7 Hz, JH-H ) 7.5 Hz), 1.95 (s, 12H), 1.31 (t, 12H, JH-H ) 7.5
Hz), -2.83 (s, 4H), -3.00 (s, 2H). MS: m/z ) 1549 [M + H]+. IR
(KBr): ν 3482 (NH), 3401 (NH), 2961(CH), 2923 (CH), 2870 (CH)
cm-1. UV-vis (CH2Cl2; λmax, nm (ꢀ, L mol-1 cm-1)): 416 nm (131
500), 572 (35 400), 608 (29 000). Anal. Calcd for C112H90N8‚2H2O:
C, 84.92; H, 5.98; N, 7.07. Found: C, 84.96; H, 6.00; N, 6.98.
1,6-Bis(7,13-diethyl-8,12-dimethyl-2,3,17,18-tetraphenylcorrol-10-
yl)biphenylene (7b). This compound was prepared in 20% yield (0.25
g), as described for 7a, starting from 4b (0.5 g, 0.82 mol) and 5 (0.85
1
3
g, 3.4 mol). H NMR: δ 9.59 (s, 4H), 7.98 (d, 2H, JH-H ) 6.5 Hz),
7.61 (dd, 2H, 3JH-H ) 6.5 Hz) 7.47 (d, 2H, 3JH-H ) 6.5 Hz), 7.10 (m,
40H), 3.54 (m, 8H), 2.07 (s, 12H), 1.52 (t, 12H, 3JH-H ) 7.3 Hz), -5.49
(s, 6H). MS: m/z ) 1523 [M + H]+. UV-vis (CH2Cl2; λmax, nm (ꢀ, L
mol-1 cm-1)): 404 nm (141 000), 578 (44 500), 607 (37 000). Anal.
Calcd for C110H88N8: C, 86.81; H, 5.83; N, 7.36. Found: C, 86.64; H,
5.98; N, 7.45.
1,8-Bis[cobalt(III) 7,13-diethyl-8,12-dimethyl-2,3,17,18-tetraphen-
ylcorrol-10-yl]anthracene (8a). Compound 7a (0.2 g, 0.13 mmol) was
added to a solution of cobalt(II) acetate (0.16 g, 0.65 mmol) in pyridine
(20 mL). The solution was heated at 80 °C, and the reaction was
monitored by UV-visible spectroscopy. The solvent was then evapo-
rated under vacuum, and the residue was chromatographed on a Florisil
column (CH2Cl2 + 1% methanol as eluent). The second red band
afforded the title product (8a) which was recrystallized from CH2Cl2/
methanol (82 mg, 41%). MS: m/z ) 1660 [M]•+. UV-vis (CH2Cl2;
λ
max, nm (ꢀ, L mol-1 cm-1)): 402 nm (90 000), 527 (26 000). Anal.
Calcd. for C112H84N8Co2‚CH3OH: C, 80.22; H, 5.24; N, 6.62. Found:
C, 79.99; H, 5.21; N, 6.54.
1,6-Bis(5,5′-ethoxycarbonyl-4,4′-diethyl-3,3′-dimethyldipyrro-
methan-5-yl)biphenylene (3b). This compound was prepared in 89%
yield (3.83 g), as described above for 3a, starting from 1b (1 g, 4.8
mmol) and 2 (3.25 g, 20 mmol). 1H NMR: δ 8.24 (s, 4H), 6.92
1,6-Bis[cobalt(III) 7,13-diethyl-8,12-dimethyl-2,3,17,18-tetraphen-
ylcorrol-10-yl]biphenylene (8b). This compound was obtained in
45% yield, as described for 8a, starting from 7b (0.2 g, 0.13 mmol).
MS: m/z ) 1634 [M]•+. UV-vis (CH2Cl2; λmax, nm (ꢀ, L mol-1 cm-1)):
390 nm (88 100), 521 (27 200). Anal. Calcd for C110H82N8Co2.2CH3-
OH: C, 79.23; H, 5.34; N, 6.60. Found: C, 79.02; H, 5.41; N, 6.48.
Equilibrium Measurements. The binding of pyridine to (BCA)-
Co2, 8a, and (BCB)Co2, 8b, was carried out at 296 K in CH2Cl2 and
the reaction monitored by UV-visible spectroscopy. The absorbance
was fitted to the Hill equation52
3
3
(d, 2H, JH-H ) 8.0 Hz), 6.71 (dd, 2H, JH-H ) 8.0 Hz), 6.61 (d, 2H,
3JH-H ) 8.0 Hz), 5.28 (s, 2H), 4.24 (q, 8H, JH-H ) 6.0 Hz), 2.68 (q,
3
3
3
8H, JH-H ) 6.0 Hz), 2.16 (s, 12H), 1.33 (t, 12H, JH-H ) 6.0 Hz),
1.01 (t, 12H, 3JH-H ) 6.0 Hz). MS: m/z ) 897 [M]•+. Anal. Calcd for
C54H64N4O8: C, 72.30; H, 7.19; N, 6.25. Found: C, 72.41; H, 7.15;
N, 6.09.
1,8-Bis(4,4′-diethyl-3,3′-dimethyldipyrromethan-5-yl)anthra-
cene (4a). A suspension of 2.86 g of 3a (3 mmol) in diethylene glycol
(150 mL) containing KOH (15 g) was heated at 190 °C under N2 for
3 h and then allowed to cool to room temperature. The mixture was
poured into ice water (500 mL), and the resulting solid was filtered,
washed with water, and then dried to give the title product 4a (1.76 g,
90%). 1H NMR: δ 8.68 (s, 1H), 8.44 (s, 1H), 7.88 (d, 2H, 3JH-H ) 8.5
log((Ai - A0)/(Af - Ai)) ) log K + p log [py]
(1)
where Ai ) absorbance at a specific concentration of pyridine; A0 )
initial absorbance where [py] ) 0, and Af ) final absorbance where
the fully ligated corrole is the only species present and p represents
the number of ligands bound to cobalt center. Values for log K were
3
3
Hz), 7.32 (dd, 2H, JH-H ) 8.5 Hz), 7.02 (d, 2H, JH-H ) 8.5 Hz),
3
6.93 (s, 4H), 6.31 (d, 2H, JH-H ) 2.5 Hz), 5.99 (s, 2H), 2.41 (q, 8H,
3JH-H ) 7.3 Hz), 1.72 (s, 12H), 1.15 (t, 12H, JH-H ) 7.3 Hz). MS:
3
m/z ) 634 [M]•+. Anal. Calcd for C56H66N4O8: C, 83.24; H, 7.94; N,
8.82. Found: C, 83.58; H, 7.71; N, 8.61.
obtained from the intercept of the line for a plot of log((Ai A0)/
-
(Af Ai)) vs log [py]. The concentration of the biscorroles for these
-
1,6-Bis(4,4′-diethyl-3,3′-dimethyldipyrromethan-5-yl)biphen-
ylene (4b). This compound was prepared in 92% yield (1.25 g), as
measurements was 1 × 10-5 M, and that of pyridine was in the range
of 10-5 to 0.5 M.
1
described for 4a, starting from 3b (2 g, 2.2 mmol). H NMR: δ 7.07
A calibrated gas tight syringe was used to introduce CO into CH2-
Cl2 solutions containing the examined corroles. The pressure of CO
within the gas tight syringe (Pinjected) was read from a barometer before
each injection. The volume of the titration vessel above the solution
(Vvessel) was 175 mL. Thus, by systematically injecting a known volume
(Vinjected) of CO gas into the vessel, we were able to calculate the partial
pressure of CO (PCO) at each step in the titration as (Vinjected/Vvessel)-
(s, 4H), 6.44 (m, 5H), 6.11 (d, 1H, 3JH-H ) 2.4 Hz), 5.11 (s, 2H), 2.48
(q, 8H, 3JH-H ) 7.3 Hz), 1.87 (s, 12H), 1.24 (t, 12H, 3JH-H ) 7.3 Hz).
MS: m/z ) 608 [M]•+. Anal. Calcd for C42H48N4: C, 82.85; H, 7.95;
N, 9.20. Found: C, 82.76; H, 7.31; N, 9.68.
1,8-Bis(7,13-diethyl-8,12-dimethyl-2,3,17,18-tetraphenylcorrol-10-
yl)anthracene (7a). A mixture of 0.55 g (0.86 mmol) of 4a and 0.9 g
(3.6 mmol) of 3,4-diphenyl-2-formylpyrrole 5 was dissolved in
methanol (500 mL). HBr/CH3CO2H (2.2 mL) was then added, and the
resulting mixture was stirred at room temperature for 4 h after which
NaHCO3 (2.2 g) was added and the mixture stirred again for 10 min.
p-Chloranil (0.075 g) and hydrazine hydrate (3.5 mL) were then added
and stirring continued for 20 min after which the solvent was evaporated
under vacuum and the solid dissolved in CH2Cl2. The organic layer
was washed with water, dried over MgSO4, and evaporated. The solid
was chromatographed on basic alumina (grade III, CH2Cl2 as eluent),
and the first violet band was collected to give the title biscorrole 7a. It
P
injected. Each solution was vigorously shaken for 3 min after introducing
CO to ensure equilibrium before recording the UV-visible spectrum.
P1/2CO, the pressure of CO when the reaction has proceeded halfway,
is used to represent the formation constants. The solubility coefficient
of CO in CH2Cl2 was taken as 6.7 × 10-3 M/atm53 and used to calculate
the formation constant, K.
Collection of the X-ray Data and Structure Determination for
the py adduct of 8a. Single crystals suitable for X-ray diffraction were
obtained from CHCl3/CH3OH plus a few drops of pyridine. Data were
collected on a Nonius KappaCCD diffractometer at -100 °C using
Mo-KR graphite monochromated radiation (λ ) 0.7107 Å), φ scans.
1
was recrystallized from CH2Cl2/methanol (0.41 g, 23%). H NMR: δ
8.86 (s, 4H), 8.79 (s, 1H), 8.36 (d, 2H, 3JH-H ) 6.5 Hz), 7.98 (s, 1H),
7.80 (m, 8H, Ph), 7.65 (d, 2H, 3JH-H ) 6.5 Hz), 7.57 (dd, 2H, 3JH-H
)
(52) Ellis, J.; Linard, P. E.; Szymanski, T.; Jones, R. D.; Budge, J. R.;
Basolo, F. J. Am. Chem. Soc. 1980, 102, 1889-1896.
(53) Rougee, M.; Brault, D. Biochemistry 1975, 14, 4100-4106.
6.5 Hz), 7.52 (m, 8H, Ph), 7.29 (m, 8H, Ph), 7.01 (m, 16H, Ph), 3.27
2
3
2
(dq, 4H, JH-H ) 14.7 Hz, JH-H ) 7.5 Hz), 3.22 (dq, 4H, JH-H
)

Linked “Face-to-Face” Biscorroles
Inorganic Chemistry, Vol. 40, No. 19, 2001 4859
Scheme 1
The structure was solved using direct methods and refined against |F|.
For all computations, the OpenMoleN package was used.54
performed by adding a small amount of p-chloranil and the
excess oxidant was reduced by addition of 50% hydrazine in
water.59 The progress of each step in this latter reaction was
monitored by UV-visible spectroscopy.
Crystal Data for 8a (py)3. Red crystals, crystal dimensions 0.20 ×
0.20 × 0.15 mm3: C129H101Co2Cl6N11 ) C127H99Co2N11‚2CHCl3, M )
2135.90, triclinic, space group P1h, a ) 13.2555(5) Å, b ) 18.6406(8)
Å, c ) 22.2140(9) Å, R ) 94.186(9)°, â ) 102.273(9)°, γ ) 94.205-
(9)°, V ) 5326.8(4) Å3, Z ) 2, Dc ) 1.33 g cm-3, µ(Mo-KR) ) 0.520
mm-1. A total of 9293 independent reflections were collected, 2.5° <
θ < 26.4°, 9075 reflections having I >3σ(I). One ethyl has its terminal
methyl group disordered over two positions and also one of the two
CHCl3 molecules has the chlorines disordered over two positions. The
hydrogen atoms were introduced as fixed contributors (dC-H ) 0.95
Å, BH ) 1.3Bequiv(C) Å2) with the exception of those of the disordered
atoms. All non-hydrogen atoms, with the exception of the disordered
atoms, were refined anisotropically. Final results R(F) ) 0.066,
Rw(F) ) 0.084, GOF ) 1.173, maximum residual electronic density
1.007 e Å-3. Data for this structure have been deposited with the
Cambridge Crystallographic Data Centre as Supplementary publication
no. CCDC-168248.
meso-Aryl substituted corroles are generally unstable and
decompose in the presence of air and light when left in
solution.60 One decomposition product has a biliverdin type
structure which results from addition of dioxygen across the
1,19-double bond of the corrole ring.60 The same instability is
observed for linear biscorroles having methyl and ethyl sub-
stituents and a linear bisbiliverdin was isolated as a final
product.61 Bisbiliverdins are not found when phenyl groups are
introduced at the â-pyrrole positions 2, 3, 17, and 18 of the
corrole (see Chart 1 for numbering), and no ring opening occurs
at the direct pyrrole-pyrrole 1,19-double bond.60 The tetra-
phenyl free base corroles are quite stable in solution when in
the dark but exhibit slow degradation of the macrocycle when
left in the light over a period of several days. Results on a series
of free base and Co(III) monocorroles with phenyl substituents
at the â-positions show that the highest stability is obtained in
the case of the Me4Ph5Cor derivative,50 and this macrocycle
was therefore used in synthesis of the two biscorroles (BCA)-
H6 and (BCB)H6.
Results and Discussion
Synthesis. The free base anthracenyl and biphenylenyl
biscorroles 7a and 7b were synthesized in four steps starting
from the corresponding diformyl spacer (Scheme 1).48
The condensation of 4 equiv of 2 on the diformyl spacer 1a
or 1b under acidic conditions gave 3a or 3b in 80% yield (step
i in Scheme 1). In a second step, 3a or 3b were simultaneously
saponified and decarboxylated in diethylene glycol containing
KOH at 190 °C to give 4a or 4b (step ii in Scheme 1). The free
base cofacial biscorrole products, 7a and 7b, were obtained from
condensation of 4 equiv of pyrrole 5 on 4a or 4b to give 6a
and 6b (step iii in Scheme 1) which were not isolated and
immediately cyclized by addition of sodium hydrogen car-
bonate.55-58 The final macrocycle oxidation (step iv) was
The free base “face-to-face” biscorroles 7a and 7b were
identified by LSIMS mass spectrometry which showed the
(56) Dolphin, D.; Harris, R. L. N.; Huppatz, J. L.; Johnson, A. W.; Kay,
I. T.; Leng, J. J. Chem. Soc. C 1966, 98-106.
(57) Johnson, A. W.; Kay, I. T. Proc. Chem. Soc. 1964, 89-90.
(58) Johnson, A. W.; Kay, I. T. Proc. R. Soc. London A 1965, 288, 334-
341.
(59) Murakami, Y.; Matsuda, Y.; Sakata, K.; Yamada, S.; Tanaka, Y.;
Aoyama, Y. Bull. Chem. Soc. Jpn. 1981, 54, 163-169.
(60) Tardieux, C.; Gros, C. P.; Guilard, R. J. Heterocycl. Chem. 1998, 35,
965-970.
(61) Paolesse, R.; Sagone, F.; Macagnano, A.; Boschi, T.; Prodi, L.;
Montalti, M.; Zaccheroni, N.; Bolletta, F.; Smith, K. M. J. Porphyrins
Phthalocyanines 1999, 364-370.
(54) OpenMoleN, I. S. S.; Nonius B. V.: Delft, The Netherlands, 1997.
(55) Genokhova, N. S.; Melent’eva, T. A.; Berezovskii, V. M. Russ. Chem.
ReV. 1980, 49, 1056-1067.

4860 Inorganic Chemistry, Vol. 40, No. 19, 2001
Guilard et al.
Table 1. Selected Absorption Maxima (ꢀ) of Representative Free Base Biscorroles and Bisporphyrins in CH2Cl2
λ
max, nm (ꢀ × 103 L mol-1 cm-1
)
macrocycle
corrole
compound
Soret band
Visible-bands
refa
(BCA)H6 (7a)
(BCB)H6 (7b)
(Me4Ph5Cor)H3
(DPA)H4
(DPB)H4
(Me6Et2PhP)H2
416 (131.5)
404 (141.0)
419 (85.0)
395 (190.5)
379 (173.9)
404 (186.4)
572 (35.4)
608 (29.0)
607 (37.0)
607 (13.0)
631 (3.3)
632 (1.8)
623 (2.7)
tw
tw
50
21
21
64
578 (44.5)
567 (15.0)
578 (6.0)
580 (3.4)
570 (7.2)
porphyrin
506 (14.1)
511 (6.3)
501 (15.6)
539 (5.1)
540 (2.0)
535 (7.8)
a tw ) this work.
pseudo-molecular ion [M + H]+ (see Experimental Section).
The UV-visible spectral data of these cofacial biscorroles are
summarized in Table 1 and are not simply a superposition of
absorption bands for the two corrole macrocycles. (BCB)H6,
7b, has a Soret band at 404 nm, and this can be compared to
(Me4Ph5Cor)H3 which possesses the same substitution pattern
on the macrocycle but has a Soret band at 419 nm with about
half the Soret band molar absorptivity as that of the biscorrole
(see Table 1).
of the two compounds, and this can be compared to a difference
of 16 nm between the Soret band of (DPA)H4 and (DPB)H4.
1
The H NMR spectra of 7a and 7b exhibit the same ring
current effects as seen in the Pacman porphyrin series.24,65 Due
to the close proximity of the two corrole rings to each other in
7b, the NH signal of the free base macrocycles is shifted upfield
(δΝΗ ) -5.49 ppm) with respect to the two NH signals of the
anthracenyl compound (δΝΗ ) -3.00 and -2.83 ppm; see
Experimental Section).
As in the case of the “Pacman” porphyrins,21 the blue-shift
of the Soret band upon going from the monocorrole, (Me4Ph5-
Cor)H3, to the biscorrole 7b can be explained by a strong
electronic interaction between the two corrole rings which are
held in close proximity to each other by the biphenylenyl spacer.
This strong interaction between the two macrocycles leads to a
higher HOMO-LUMO gap for 7b than for the related mono-
corrole, and therefore the transitions occur at lower wavelengths
for (BCB)H6. This is also seen in the case of double decker
porphyrins.62,63
For example, the Soret band of (DPB)H4 in CH2Cl2 is located
at 379 nm, while its monoporphyrin analogue, 13,17-diethyl-
2,3,7,8,12,18-hexamethyl-5-phenylporphyrin, (Me6Et2PhP)H2,
has a Soret band at 404 nm.64 This 25 nm difference is larger
by 10 nm than the difference between the Soret bands of 7b
(404 nm) and the reference monocorrole, (Me4Ph5Cor)H3 (419
nm, Table 1). Conversely, the distance between the two corrole
rings in the anthracenyl derivative 7a is probably large enough
to avoid significant interaction between the two macrocycles,
and, as a consequence, the optical spectrum of 7a is character-
ized by absorption bands which are nearly identical in wave-
length to those of the monocorrole (Me4Ph5Cor)H3 (see Table
1). The difference in λmax between the Soret bands of 7a and
(Me4Ph5Cor)H3 is only 3 nm (see Table 1), and this is in contrast
to what is seen for (DPA)H4 and (Me6Et2PhP)H2 where a 9 nm
difference is observed between the Soret bands of the bispor-
phyrin and the related monoporphyrin with the same macrocycle
substitution pattern. In the case of the cofacial biscorroles, 7a
and 7b, a 12 nm difference is observed between the Soret band
The upfield shift of the NH protons results from the
superposition of the two ring currents of the corrole macrocycles
which is enhanced in 7b. The interaction of the two macrocycles
is weaker in the case of 7a than in the case of 7b, and the NH
signals therefore appear approximately in the same region as
the reference (Me4Ph5Cor)H3 monocorrole (δΝΗ ) -2.70
ppm).50
UV-visible and NMR data suggest that 7a can be considered
as containing two separate monocorrole systems, but this is not
the case for 7b which exhibits a strong electronic interaction
between the two macrocycles and can therefore be considered
as a single unit containing the two corrole macrocycles.
Interestingly, the two methylene protons of each â-pyrrole ethyl
group in (BCA)H6 and (BCB)H6 are diastereotopic and two
double quartets are seen at 3.27 and 3.22 ppm for (BCA)H6
and a multiplet at 3.54 ppm for (BCB)H6 (see Experimental
Section). This results from a slow rotation of the ethyl groups
of the biscorroles on the 1H NMR time scale as is also the case
for the Pacman porphyrins.
A standard procedure was employed to metalate the biscor-
roles 7a and 7b with cobalt.48,66-68 The free base biscorroles
were heated to 80 °C in pyridine containing excess cobalt(II)
acetate,69 and the progress of the metalation was monitored by
UV-visible spectroscopy. Purification by column chromatog-
raphy gave 8a or 8b, both of which, as shown in the following
section, contain axially coordinated pyridine.
A noticeable color change from green to red was observed
upon evaporating to dryness the pyridine solution. When
redissolved in CH2Cl2, both cobalt complexes have well-defined
Soret bands at 402 (8a) or 390 nm (8b) and a single Q-band at
527 (8a) or 521 nm (8b) (see Table 2). The spectrum of the
pyridine complex could be recovered by adding pyridine to the
previously evaporated compound, thus indicating a reversible
coordination of one or more pyridine molecules at each metal
center.
(62) Buchler, J. W.; Dennis, K. P. N. In The Porphyrin Handbook; Kadish,
K. M., Smith, K. M., and Guilard, R., Eds.; Academic Press: San
Diego, CA, 2000; Vol. 3, p 245.
(63) Kadish, K. M.; Moninot, G.; Hu, Y.; Dubois, D.; Ibnlfassi, A.; Barbe,
J.-M.; Guilard, R. J. Am. Chem. Soc. 1993, 115, 8153-8166.
(64) Synthesis of 13, 17-diethyl-2,3,7,8,12,18-hexamethyl-5-phenylpor-
phyrin. This compound was synthesized as described by Harris et al.
(Harris, D.; Johnson, A. W.; Gaete-Holmes, R. Bioorg. Chem. 1980,
9, 63-70) by condensation of 1 equiv of the corresponding a,
c-biladiene to 1 equiv of benzaldehyde. (Yield: 40%) 1H NMR: δ
10.15 (s, 2H, meso), 9.94 (s, 1H, meso), 8.02 (d, 2H, Ph), 7.71-7.75
(d+s, 2H+1H, Ph), 4.06 (q, 4H, -CH2CH3), 3.62 (s, 6H, -CH3),
3.52 (s, 6H, -CH3), 2.44 (s, 6H, -CH3), 1.87 (t, 6H, -CH2CH3),
-3.02 (s, 1H, NH), -3.12 (s, 1H, NH). MS: m/z ) 523 [M].+. UV-
vis (CH2Cl2; λmax, nm (ꢀ, L mol-1 cm-1)): 404 (186 400), 501
(15 600), 535 (7800), 570 (7200), 623 (2700). Anal. Calcd for
C36H38N4: C, 82.08; H, 7.28; N, 10.64. Found: C, 82.26; H, 7.59; N,
10.99.
(65) Chang, C. K. J. Heterocycl. Chem. 1977, 14, 1285-1288.
(66) Hitchcock, P. B.; McLaughlin, G. M. J. Chem. Soc., Dalton Trans.
1976, 1927-1930.
(67) Paolesse, R.; Licoccia, S.; Fanciullo, M.; Morgante, E.; Boschi, T.
Inorg. Chim. Acta 1993, 203, 107-114.
(68) Conlon, M.; Johnson, A. W.; Overend, W. R.; Rajapaksa, D. J. Chem.
Soc., Perkin Trans. 1 1973, 2281-2288.
(69) Murakami, Y.; Yamada, S.; Matsuda, Y.; Sakata, K. Bull. Chem. Soc.
Jpn. 1978, 51, 123-129.

Linked “Face-to-Face” Biscorroles
Inorganic Chemistry, Vol. 40, No. 19, 2001 4861
Table 2. Selected Absorption Maxima (%) of Representative Cobalt Biscorroles
λ
max, nm (%)
compound
solventa
Soret band
Visible bands
(BCA)Co2 (8a)
CH2Cl2
neat py
CH2Cl2
neat py
CH2Cl2
neat py
402 (100.0)
527 (28.3)
419 (96.3, shb), 433 (100.0)
390 (100.0)
514 (15.2)
521 (39.0)
517 (33.3)
555 (25.7)
599 (62.8)
603 (47.6)
598 (62.3)
(BCB)Co2 (8b)
417 (100), 435 (95.2, shb)
398 (100)
556 (28.6)
529 (35.5)
557 (27.3)
(Me4Ph5Cor)Co 50
412 (89.6, shb), 433 (100.0)
616 (50.0, sh)
a py ) pyridine. b sh ) shoulder peak.
Figure 2. Electronic absorption spectra of (top) (Me4Ph5Cor)Co in
neat pyridine and (bottom) 8a in CH2Cl2 containing 0.5 M pyridine.
The spectral changes of (BCB)Co2(py)2 as the pyridine
concentration was increased from 10-3 to 0.2 M are illustrated
in Figure 1b. As seen in the figure, the Soret band at 380 nm
and the visible band at about 519 nm decrease simultaneously
and this is accompanied by the appearance of a new Soret band
at 420 nm and a new visible band at 603 nm. Another linear
relationship with a slope of 1.0 is also obtained (inset of Figure
1b), and this ligand addition reaction is assigned to the
conversion of (BCB)Co2(py)2 to (BCB)Co2(py)3 as shown in
eq 3 (log K2 ) 1.10).
Figure 1. Electronic absorption spectral changes of 1.0 × 10-5 M 8b
upon (top) formation of (BCB)Co2(py)2 and (bottom) (BCB)Co(py)3
in CH2Cl2. The inset of each figure shows the Hill plot for each pyridine
addition. The pyridine concentration for the plots ranges (a) from
3.1 × 10-4 to 1.3 × 10-3 M and (b) from 5.2 × 10-2 to 0.16 M.
Ligand Binding Reactions of (BCA)Co2 and (BCB)Co2
with Pyridine and CO. The electronic absorption spectra of
8a and 8b were measured in CH2Cl2 during a titration with
pyridine. The spectral changes obtained as the concentration of
pyridine was varied from 10-4 to 10-3 M in a 1 × 10-5
M
solution of (BCB)Co2 are shown in Figure 1a. During the early
stages of the titration, the broad Soret band centered at about
388 nm and the single visible band at 521 nm both slightly
decrease in intensity. A Hill plot was constructed (see inset in
Figure 1a) and shows a linear relationship with a slope of 1.1
and a binding constant of log K1 ) 3.14 for conversion of
(BCB)Co2 to (BCB)Co2(py)2 (eq 2). (BCB)Co2 contains two
equivalent cobalt centers, and the slope of ca. 1.0 indicates that
each cobalt center binds one pyridine molecule.
(BCB)Co2(py)2 + py f (BCB)Co2(py)3
(3)
Similar types of spectral changes are seen for (BCA)Co2 in
CH2Cl2, and the values of log K1 and log K2 are calculated as
4.84 and 2.61. These data are also interpreted in terms of (BCA)-
Co2(py)2 and (BCA)Co2(py)3 formation in mixed CH2Cl2/py
solvents. The trispyridine adduct was structurally characterized
in the case of (BCA)Co2 (see following section).
Figure 2 compares the final spectrum in the pyridine titration
of 8a with the spectrum of (Me4Ph5Cor)Co(py)2. The mono-
corrole bispyridine complex (Figure 2a) exhibits a Soret band
(BCB)Co2 + 2py f (BCB)Co2(py)2
(2)

4862 Inorganic Chemistry, Vol. 40, No. 19, 2001
Guilard et al.
Table 3. Equilibrium Constants of Bis-Cobalt Corroles Binding
Pyridine or CO in CH2Cl2 at 296 K
pyridine
CO
log K1 log K2 P1/2CO (Torr) log Kb
ν
co (cm-1
)
a
a
compound
(Me4Ph5Cor)Co
(BCA)Co2 (8a)
(BCB)Co2 (8b)
4.90
4.84
3.14
2.10
2.61
1.10
7.1
15.0
31.3
4.2
3.9
3.6
2049
2047
2046
a K1 corresponds to eq 2 and K2 to eq 3. b K ) (P1/2COkH)-1; kH
6.7 × 10-3 M/atm in CH2Cl2.
)
at 436 nm, a shoulder at ca. 416 nm, and two visible bands at
555 and 599 nm. The intensity of the visible band at 599 nm is
much stronger than that of the second visible band at 555 nm.
A split Soret band (at 418 and 433 nm) and two visible bands
(at 558 and 599 nm) are also observed in the final spectrum of
titrated 8a (Figure 2b), but the intensity of the band at 418 nm
is stronger than that at 433 nm which appears as a shoulder of
the major peak. This difference in spectral properties between
the monocorrole and the biscorrole suggests that more than one
pyridine molecule may be bound within the cavity of (BCA)-
Co2 at very high pyridine concentrations. Therefore, the spec-
trum in Figure 2b could be assigned to a mixture of overlapping
spectra for five- and six-coordinate cobalt corrole complexes,
i.e., (BCA)Co2(py)3 and (BCA)Co2(py)4.
The pyridine binding constants of (BCA)Co2 and (BCB)Co2
are summarized in Table 3, where K1 is defined by eq 2 and K2
by eq 3. Comparison of formation constants for the two
biscorroles with those of the corresponding monocorrole
complex shows that log K1 for 8a is only a slightly smaller
than log K1 for the addition of py to (Me4Ph5Cor)Co. However,
a much smaller log K1 is seen for 8b as compared to the other
two compounds.
The titration of 8a and 8b with CO in CH2Cl2 was monitored
by measuring changes in the UV-visible spectra as a function
of CO partial pressure, and these results are illustrated in Figure
3 for the case of (BCB)Co2. The starting compound has a broad
Soret band at ca. 388 nm and a visible band at 521 nm. As CO
is introduced into solution, the intensity of the Soret band
decreases and a new visible band appears at 569 nm. No other
spectral changes are seen as the CO partial pressure is increased
up to 1 atm. The Hill plot (inset of Figure 3) shows a linear
relationship, and a slope of 1.0 is obtained. A comparison of
spectral changes for 8b upon CO binding with results for CO
binding to the corresponding monocorrole, (Me4Ph5Cor)Co,50
clearly indicates that each cobalt unit in the biscorrole binds a
single CO molecule as schematically shown in eq 4.
Figure 3. Electronic absorption spectral changes upon formation of
(BCB)Co2(CO)2 from 1.5 × 10-5 M (BCB)Co2. The Hill plot for the
CO binding reaction is shown as an inset where the CO partial pressure
ranges from 16 to 600 Torr for the plot.
monocorrole (Me4Ph5Cor)Co whose Co-CO stretch is located
at 2049 cm-1
.
Molecular Structure of (BCA)Co2(py)3. Side and front
views of the molecular structure of (BCA)Co2(py)3 are displayed
in Figure 4a,b, respectively. This figure also gives the labeling
scheme used for most of the non-hydrogen atoms. Crystal data
for (BCA)Co2(py)3‚2CHCl3 and details of the diffraction data
are listed in Table 4, and selected bond distances are summarized
in Table 5.
(BCA)Co2(py)3 is a homobimetallic complex of a face-to-
face biscorrole. The six-coordinate cobalt(III) cation, Co1, is
bound to the four pyrrole nitrogen atoms N21 to N24 of the
corrole ring Cor1 and also to the nitrogen atoms N45 and N51
of the two axially coordinated pyridine molecules Py1 and Py2.
Py2 lies in the cavity formed by both corrole rings of the face-
to-face biscorrole molecule, whereas Py1 lies outside this cavity.
In contrast to Co1, the second cobalt atom, Co2 is five-
coordinate, bound to the four pyrrole nitrogen atoms N41 to
N44 of the corrole ring Cor2 and to the nitrogen atom N131 of
the single pyridine Py3, located as the Py1 molecule outside of
the molecular cavity. Thus, the coordination polyhedra of the
two cobalt atoms Co1 and Co2 of (BCA)Co2(py)3 are octahedral
and square-pyramidal, respectively.
The Co1-Np and Co2-Np (Np: pyrrole nitrogen atom) bond
distances are not significantly different, their mean value being
1.887(5) Å. Again, the shortest Co-Np bond distances (Co1-
N21 ) 1.879(4), Co1-N24 ) 1.883(5), and Co2-N41 ) 1.875-
(5) Å) correspond in each case to cobalt-pyrrole nitrogen bonds
involving two Nps belonging to the pyrrole rings linked directly
via the CR-CR bond. Similar features have been previously
observed in the structures of the cobalt corrole complex, (Me4-
The CO partial pressure when the binding reaction has
proceeded halfway, is obtained from the Hill equation, and the
CO
experimentally obtained value of P1/2 ) 31.3 Torr for 8b
corresponds to a log K ) 3.6. The value of P1/2CO is 15.0 Torr
for 8a, and log K ) 3.9. The CO binding ability of 8b is less
than that of (BCA)Co2 or (Me4Ph5Cor)Co, and this trend is also
seen in the pyridine binding constants (Table 3).
50
The CO stretching frequencies of both biscorrole complexes
were also measured in CH2Cl2 under a CO atmosphere (Table
3). The νCO are located at 2047 cm-1 for 8a and 2046 cm-1 for
8b, both of which are slightly lower than the νCO of the
Ph5Cor)Co(py)2 and other metallocorroles.29,30 The average
Co-Np bond distance of 1.887(5) Å found in (BCA)Co2(py)3
is not significantly different from the 1.899(6) Å seen in (Me4-
Ph5Cor)Co(py)2, a compound in which the cobalt(III) ion is six-

Linked “Face-to-Face” Biscorroles
Inorganic Chemistry, Vol. 40, No. 19, 2001 4863
Figure 4. (top) Side and (bottom) front views of the molecular structure and atom numbering of (BCA)Co2(py)3. Thermal ellipsoids enclose 30%
probability. Hydrogen atoms are omitted for clarity.
coordinate and low-spin. The similarity of Co-Np bond
distances betweenCo1 and Co2 in (BCA)Co2(py)3 and the cobalt
atom in (Me4Ph5Cor)Co(py)2 suggests that both cobalt(III) atoms
in (BCA)Co2(py)3, the six-coordinate Co1, and the five-
coordinate Co2, are each low-spin. The Co-Npy axial bond
distances are very similar to each other, although the Co2-
N131 bond distance of 1.946(5) Å, with the five-coordinate
cobalt Co2, is slightly shorter than the Co1-Npy bond lengths
of 1.976(5) (Co1-N45) and 1.979(5) Å (Co1-N51) involving
the six-coordinate cobalt atom, Co1. These Co-Npy bonds are
slightly tilted away from the two lines perpendicular to the
corrole mean planes going through each cobalt atom, the
corresponding angles being 5.2(2) (Co1-N51), 3.3(2) (Co1-
N45), and 2.9(2)° (Co2-N131). Moreover, the orientation of
the pyridine rings Py1 and Py2 around Co1 is almost staggered,
the dihedral angle between the mean planes of the two pyridine
rings being 88.3(2)°.
bond distances are 1.979 and 2.060 Å, respectively.70 As in
(Me4Ph5Cor)Co(py)2,50 the shortening of the Co-Np bond
lengths in (BCA)Co2(py)3 can be ascribed to the reduced hole
size of the two corrole rings occurring in [BCA]6- relative to
the tetraphenylporphyrin ligand [TPP]2-, since a similar decrease
of the M-Np bond lengths was also observed in several other
metallocorroles as different as (Me8Cor)Rh(AsPh3),71 (Me8Ph3-
Cor)CoPPh3,72 and (Me2Et6Cor)Mn.73
Both corrole rings, Cor1 and Cor2, of (BCA)Co2(py)3 are
slightly ruffled as indicated by the displacements of the meso
carbon atoms above and below the corrole-core mean plane.
For the Cor1 ring, the meso carbon C10 lies 0.023(1) Å above
the plane, whereas C5 and C15 lie on the average 0.019(1) Å
(70) Scheidt, W. R.; Cunningham, J. A.; Hoard, J. L. J. Am. Chem. Soc.
1973, 95, 8289-8294.
(71) Boschi, T.; Licoccia, S.; Paolesse, R.; Tagliatesta, P.; Azarnia Tehran,
M.; Pelizzi, G.; Vitali, F. J. Chem. Soc., Dalton Trans. 1990, 463-
468.
(72) Paolesse, R.; Licoccia, S.; Bandoli, G.; Dolmella, A.; Boschi, T. Inorg.
Chem. 1994, 33, 1171-1176.
(73) Licoccia, S.; Morgante, E.; Paolesse, R.; Polizio, F.; Senge, M. O.;
Tondello, E.; Boschi, T. Inorg. Chem. 1997, 36, 1564-1570.
The Co-Np and axial Co-Npy bond distances in (BCA)-
Co2(py)3 are significantly shorter than the corresponding
distances in the low-spin, six-coordinate cobalt(III) porphyrin,
[(TPP)Co(pip)2]+, where the average Co-Np and Co-N(pip)

4864 Inorganic Chemistry, Vol. 40, No. 19, 2001
Table 4. X-ray Experimental Data for Compound 8a
Guilard et al.
formula
C129H101Cl6Co2N11-
C
127H99Co2N11‚2CHCl3
MW
2135.90
cryst syst
space group
a (Å)
triclinic
P1h
13.2555(5)
b (Å)
18.6406(8)
c (Å)
22.2140(9)
94.186(9)
102.273(9)
94.205(9)
R (deg)
â (deg)
γ (deg)
V (Å3)
5326.8(4)
Z
color
2
red
crystl dimens (mm)
D
0.20 × 0.20 × 0.15
calc (g cm3)
1.33
F(000)
2216
0.520
173
µ (mm-1
)
temp (K)
wavelength (Å)
radiation
diffractometer
scan mode
0.71073
Mo KR graphite monochromated
KappaCCD
φ scans
0,16/-22,22/-27,27
2.5/26.39
9075
hkl limits
Θ limits (deg)
no. of data with I > 3σ(I)
no. of variables
R
Figure 5. Orientation and position of the corrole ring mean planes
relative to the anthracenyl spacer.
1321
0.066
Rw
GOF
0.084
1.173
1.007
interactions between the atoms of Cor2 and the pyridine
molecule Py2 which is axially bonded to Co1, the two rings
Cor1 and Cor2 are not stacked over one another but are
displaced in opposite directions, as seen in Figure 5. For each
ring, Cor1 and Cor2, the projection on a plane perpendicular to
the mean plane of the anthracenyl spacer of the two lines
connecting the meso-carbon opposite to the CR-CR bond with
the middle of this bond (C10‚‚‚C1/C19 and C30‚‚‚C21/C39 is
10(1)°). The dihedral angles between the mean-planes of the
two corrole rings Cor1 and Cor2 relative to the plane which is
perpendicular to the mean plane of the anthracenyl spacer are
5.9(1)° for Cor1 and 3.7(1)° for Cor2. This orientation leads to
an overall dihedral angle between the mean planes of Cor1 and
Cor2 of 36.3(1)° and a lateral shift of 1.839(1) Å between Ct2,
the center of the four pyrrole nitrogens lying in the 4Np mean
plane of ring Cor2, and the projection, H, of Co1 on the mean
plane of the corrole ring, Cor2 (Figure 5). The corresponding
Co1-Ct2, Co1-Co2, and Co1-H distances are 7.227(1),
7.457(1), and 6.989(1) Å, the slip angle being 14.7(3)°. Short
contact distances of 3.47, 3.50, and 3.54 occur between the
carbon atoms C47 and C48 of Py2 and the pyrrole nitrogen
N44. Other short contacts ranging from 3.64 to 3.75 occur
between C47 and C48 and the carbon atoms C34, C35, C36,
C37, C38, and C39 of Cor2.
The anthracenyl spacer is almost planar, the largest deviation
from its mean plane is 0.070(7) Å (C66), and the mean-deviation
is 0.035(7) Å. Two molecules are packed together in a head to
tail manner around the inversion centers of space group P1h.
The corresponding shortest intermolecular contacts occur be-
tween two Py1 pyridines of two molecules assembled in this
way. The corresponding distances range from 3.41(1) to 3.95(1)
Å. One of the two chloroform solvation molecules lies in the
molecular cavity and is surrounded by phenyl groups and Py2
of different molecules. Two of its chlorine atoms are in contact
with the carbon atoms C89, C93, C94, C102, C108, C117, and
C123 of different phenyl groups and with C49 of Py2. The
corresponding distances range from 3.689 to 3.987(1) Å. The
second chloroform molecule in (BCA)Co2(py)3‚2CHCl3 lies in
a cleft of the structure and is disordered.
largest peak in final (e Å3)
Table 5. Selected Bond Distances, Angles, and Averages for
Compound 8a
Co1-N21
Co1-N22
Co1-N23
Co1-N24
1.879(4)
1.898(5)
1.905(4)
1.883(5)
Co1-N45
Co1-N51
1.976(5)
1.979(5)
Co2-N131
1.946(5)
1.978(3)
<Co1-Np>
1.891(2)
<Co1-Npyridine>
Co2-N41
Co2-N42
Co2-N43
Co2-N44
1.875(5)
1.884(4)
1.880(5)
1.894(4)
<Np-CR>
<CR-Câ>
<Câ-Câ>
<CR-CR′>
<Cm-CR>
1.379(6)
1.442(6)
1.378(8)
1.432(1)
1.392(6)
<Co2-Np>
1.883(2)
<CR-Np-CR>
<Np-CR-Câ>
<CR-Câ-Câ>
108.7(6)
108.2(4)
107.4(5)
<Np-CR-CR′>
<Np-CR-Cm>
<CR-Cm-CR>
110.9(8)
122.8(9)
125.1(4)
below this mean plane. The corrole ring Cor2 is even less
ruffled, and C30 lies in the mean plane, whereas C25 and C35
are on the average displaced only by 0.09(1) Å above the corrole
mean plane.
Co1 is not significantly displaced from the 4Np mean plane
of Cor1. Its displacement relative to the Cor1-core mean plane
is also very small (0.009(1) Å), and no doming is displayed by
the Cor1 macrocycle. Five-coordinate Co2 lies 0.328(1) Å away
from the mean plane of Cor2 and is displaced in the same
direction by 0.252(1) Å from its 4Np mean plane. Thus, the
separation between these mean planes is 0.076(1) Å, and, due
to the five-coordination of Co2, the ring Cor2 is slightly domed.
As in the nickel(II) bisoxocorrole derivative, (BOCA)Ni2,74
the two corrole rings Cor1 and Cor2 are held together by a rigid
and planar anthracenyl spacer group. However, due to steric
(74) Je´roˆme, F.; Barbe, J. M.; Gros, C. P.; Guilard, R.; Fischer, J.; Weiss,
R. New J. Chem. 2001, 25, 93-101.
(75) Kadish, K. M.; Adamian, V. A.; Van Caemelbecke, E.; Gueletii, E.;
Will, S.; Erben, C.; Vogel, E. J. Am. Chem. Soc. 1998, 120, 11986-
11993.

Linked “Face-to-Face” Biscorroles
Inorganic Chemistry, Vol. 40, No. 19, 2001 4865
tions with half-wave potentials locating at 0.27, 0.44, and 0.83
V at a scan rate of 0.1 V/s. The first two oxidations represent
two overlapped electrochemical processes with a 170 mV
separation in E1/2 as compared with that of (Me4Ph5Cor)Co
(Table 6). These two processes correspond to the stepwise one-
electron abstraction from each macrocycle, leading to the
formation of the cation radical and dication species. In contrast
to this result, the first oxidation of 8a shows only one reversible
process.
(BCA)Co2 undergoes a single Co(III)/Co(II) process at -0.23
V, while (BCB)Co2 is reduced in two steps at E1/2 ) -0.31
and -0.60 V. These two reductions are assigned to a stepwise
one-electron addition to the cobalt centers.
The electrochemistry of several face-to-face cobalt bispor-
phyrins has been investigated.4,23,25-28,76-80 Among the bispor-
phyrin complexes, the Pacman derivatives (DPA)Co2 and
(DPB)Co2 have structures most similar to the two biscorrole
complexes investigated in this present paper. Previous studies77
have shown that (DPA)Co2 and (DPB)Co2 exhibit different
electrochemical behavior due to a different distance between
the porphyrin rings, and this is also the case for the two bis-
corroles (see Table 6). The two porphyrin units in (DPA)Co2
can be oxidized or reduced simultaneously at the same or at
very close potentials to each other. This distance between the
two porphyrins is much larger in this compound than in (DPB)-
Co2,8,17 thus leading to a weaker π-π electronic interaction
between the two porphyrin units. This differs from (DPB)Co2
where the first oxidation and the first reduction are split into
two discrete one-electron steps indicating a significant interac-
tion between the two redox active centers. Each porphyrin unit
in the (DPB)Co2 complexes is oxidized or reduced at a different
potential. A similar result is seen for the two biscorrole
complexes where (BCB)Co2 undergoes two one-electron oxida-
tions and two split one-electron reductions.
Figure 6. Cyclic voltammograms of 1.5 × 10-3 M (Me4Ph5Cor)Co,
3.0 × 10-3 M 8a, and 8b in PhCN, 0.2 M TBAP. Scan rate: 0.1 V/s.
Table 6. Half-Wave Potentialsa in PhCN Containing 0.2 M TBAP
for Corroles and 0.2 M TBAPF6 for Porphyrins
ox.
red.
second refc
Acknowledgment. The support of the Robert A. Welch
Foundation (K.M.K., Grant E-680) is gratefully acknowledged.
This work was supported by the French Ministry of Research
(MENRT) and CNRS (UMR 5633). These are gratefully
thanked for financial support. The “Re´gion Bourgogne” and “Air
Liquide” company are acknowledged for a scholarship (F.J.).
The authors are also grateful to M. Soustelle for the synthesis
of pyrrole and dipyrromethane precursors.
compound
third second
first
first
(Me4Ph5Cor)Co
(BCA)Co2 (8a)
(BCB)Co2 (8b) 0.83
(MPA)Co
(DPA)Co2
0.72
0.89
0.44
0.47
0.47
0.27
-0.16
-0.23
50
tw
tw
77
77
77
-0.31 -0.60
-0.06b -1.53
0.05
0.00
-1.60
(DPB)Co2
0.17
-1.71 -1.90
a V vs SCE for corrole complexes and V vs Fc/Fc+ for porphyrin
complexes. Epa, scan rate ) 0.1 V/s. c tw ) this work.
Supporting Information Available: Crystallographic data for
(BCA)Co2(py)3. This material is available free of charge via the Internet
at http://pubs.acs.org.
b
Electrochemistry of (BCA)Co2 (8a) and (BCB)Co2 (8b).
The electrochemistry of 8a and 8b was examined in PhCN
containing 0.2 M TBAP. The cyclic voltammograms are shown
in Figure 6, which also includes that for (Me4Ph5Cor)Co,50 and
the redox potentials of each process are listed in Table 6. Two
reversible to quasi-reversible oxidations are observed for 8a,
and the corresponding half-wave potentials are located at 0.47
and 0.89 V, respectively. Both E1/2 values are comparable
to those of the monocorrole complex, (Me4Ph5Cor)Co, with
E1/2 ) 0.47 and 0.72 V (see Figure 6 and Table 6). (BCB)Co2,
however, undergoes three reversible to quasi-reversible oxida-
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