9310 Inorganic Chemistry, Vol. 48, No. 19, 2009
Palmer et al.
Sigma-Aldrich and used without further purification. Electro-
des for CV were obtained from CH Instruments.
5,10,15-Tris-pentafluorophenylcorrolato-iridium(III) Triphe-
nylphosphine, 1-Ir(PPh3). H3tpfc (40 mg), [Ir(cod)Cl]2
(170 mg), and K2CO3 (70 mg) were dissolved/suspended in 75
mL of degassed THF, and the mixture was heated at reflux
under argon for 90 min. Triphenylphosphine (260 mg dissolved
in 5 mL THF) was added, and the solution was heated at reflux
for another half hour under laboratory atmosphere before being
allowed to cool to room temperature. Column chromatography
of the deep green mixture (silica, 3:1 hexanes/CH2Cl2) afforded
a bright red-orange solution, which could be evaporated to give
(tpfc)Ir(III)(PPh3) (30 mg, 64% yield) as a ruby-colored solid.
1H NMR (CDCl3): δ 8.67 (d, 2H, J = 4.5), 8.36 (d, 2H, J = 5.1),
8.18 (d, 2H, J = 5.1), 8.00 (d, 2H, J = 4.5), 6.98 (t, 3H, J = 7.2),
Syntheses. The synthesis of 5,10,15-tris-pentafluorophenyl-
corrole (the H3tpfc ligand) was accomplished by a simplified
version of the standard procedure outlined in reference 1c. 25
The cobalt(III) and rhodium(III) corroles were available from
previous studies.15,26 Compounds 1-tma and 2-tma have only been
reported in a previous communication,18 hence their syntheses are
summarized below along with those of the new corroles.
5,10,15-Tris-pentafluorophenylcorrolato-iridium(III) Bis-tri-
methylamine, 1-Ir(tma)2. H3tpfc (80 mg), [Ir(cod)Cl]2 (335 mg),
and K2CO3 (140 mg) were dissolved/suspended in 150 mL of
degassed THF, and the mixture was heated at reflux under
argon for 90 min (until corrole fluorescence was negligible to the
eye upon long-wavelength irradiation with a hand-held lamp).
Tma N-oxide (110 mg) was added, and the solution was allowed
to slowly cool to room temperature while open to the laboratory
atmosphere. Column chromatography of the black mixture
(silica, 4:1 hexanes/CH2Cl2) provided an auburn solution, from
which purple crystals of (tpfc)Ir(III)(tma)2 (30 mg, 27% yield)
could be grown by slow evaporation. 1H NMR (CDCl3): δ 8.90
(d, 2H, J= 4.2), 8.50 (d, 2H, J= 5.1), 8.38 (d, 2H, J=4.5),8.09(d,
2H, J = 4.2), -2.95 (s, 18H). 19F NMR (CDCl3): δ -138.38 (m,
6F), -154.89 (m, 3F), -163.27 (m, 6F). MS (ESI): 1105.1 ([M+]),
1046.0 ([M+-tma]), 986.5 ([M+-2tma]). UV-vis (CH2Cl2, nm, ε Â
10-3 M-1 cm-1): 388 (47), 412 (56), 572 (14), 640 (5.3).
3
6.69 (t, 6H, J = 6.9), 4.52 (d/d, 6H, J = 19.5, 4J = 3.6). 19F
NMR (CDCl3): δ -137.44 (m, 6F), -154.05 (m, 3F), -162.54
(m, 3F). MS (ESI): 1248.1 ([M+]). UV-vis (CH2Cl2, nm, ε Â
10-3 M-1 cm-1): 398 (66), 554 (8.8), 588 (6.7).
Nuclear Magnetic Resonance Spectroscopy. 1H and 19F NMR
data were obtained on CDCl3 solutions of each compound at
room temperature using a Varian Mercury 300 MHz NMR
spectrometer. 1H chemical shifts are reported relative to solvent
peaks and 19F chemical shifts are reported relative to a saved,
external CFCl3 standard.
Mass Spectrometry. Measurements were made on CH3OH
solutions of each compound by electrospray ionization into a
Thermofinnigan LCQ ion trap mass spectrometer.
2,3,7,8,12,13,17,18-Octabromo-5,10,15-tris-pentafluorophe-
nylcorrolato-iridium(III) Bis-trimethylamine, 1b-Ir(tma)2. Com-
pound 1-Ir(tma)2 (15 mg) and Br2 (70 μL) were dissolved in 20
mL of MeOH and stirred overnight. Column chromatography
(silica, 4:1 hexanes/CH2Cl2) of the red mixture provided a ruddy
solution from which purple crystals of (Br8-tpfc)Ir(III)(tma)2
(15 mg, 63% yield) could be grown by addition of methanol
X-ray Crystallography. Concentrated CH2Cl2/CH3OH solu-
tions of corroles 1-Ir(tma)2, 1b-Ir(tma)2, and 1- Ir(py)2 were
allowed to undergo slow evaporation from scintillation vials.
The resultant crystals were mounted on a glass fiber using
Paratone oil and then placed on a Bruker Kappa Apex II
diffractometer under a nitrogen stream at 100 K. The
SHELXS-97 program was used to solve the structures.
1
followed by slow evaporation. H NMR (CDCl3): δ -2.60 (s,
Cyclic Voltammetry. CV measurements were made with a
WaveNow USB Potentiostat/Galvanostat (Pine Research Ins-
trumentation) using Pine AfterMath Data Organizer software.
A three electrode system consisting of a platinum wire working
electrode, a platinum wire counter electrode, and an Ag/AgCl
reference electrode, was employed. The CV measurements were
made using dichloromethane solutions, 0.1 M in tetrabutylammo-
nium perchlorate (TBAP, Fluka, recrystallized twice from abso-
lute ethanol), and 10-3 M substrate under an argon atmosphere at
ambient temperature. The scan rate was 0.1 V/s and the E1/2 value
for oxidation of ferrocene under these conditions was 0.55 V.
UV-visible spectroelectrochemical measurements were made
on dichloromethane solutions, 0.5 M in TBAP, and 0.1-0.3 mM
in substrate with an optically transparent platinum thin-layer
electrode working electrode, a platinum wire counter electrode,
and an Ag/AgCl reference electrode under an argon atmosphere
at ambient temperature. Potentials were applied with a Wave-
Now USB Potentiostat/Galvanostat. Time-resolved UV-visible
spectra were recorded with a Hewlett-Packard Model 8453 diode
array rapid-scanning spectrophotometer.
18H). 19F NMR (CDCl3): δ -137.78 (d/d, 2F, 3J = 35.1, 4J =
18.3), -138.54 (d/d, 4F, 3J = 33.9, 4J = 17.1), -152.89 (m, 3F),
-163.38 (m, 4F), -163.70 (m, 2F). MS (ESI): 1616.4 ([M+
-
2tma]). UV-vis (CH2Cl2, nm, ε Â 10-3 M-1 cm-1): 404 (61),
424 (70), 580 (16), 654 (7.3).
5,10,15-Tris-pentafluorophenylcorrolato-iridium(III) Bis-pyr-
idine, 1-Ir(py)2. H3tpfc (40 mg), [Ir(cod)Cl]2 (170 mg), and
K2CO3 (70 mg) were dissolved/suspended in 75 mL of degassed
THF, and the mixture was heated at reflux under argon for 90
min. Pyridine (1 mL) was added, and the solution was allowed to
slowly cool to room temperature while open to the laboratory
atmosphere. Column chromatography of the forest green mix-
ture (silica, 4:1 hexanes/CH2Cl2 followed by 3:2 hexanes/
CH2Cl2) afforded a bright green solution, from which thin,
green crystals of (tpfc)Ir(III)(py)2 (26 mg, 50% yield) could be
grown by addition of methanol followed by slow evaporation.
1H NMR (CDCl3): δ 8.84 (d, 2H, J = 4.5), 8.53 (d, 2H, J = 4.8),
8.32 (d, 2H, J = 4.8), 8.17 (d, 2H, J = 4.5), 6.21 (t, 2H, J = 7.8),
5.19 (t, 4H, J = 7.0), 1.72 (d, 4H, J = 5.1). 19F NMR (CDCl3): δ
-138.68 (m, 6F), -154.84 (t, 2F, J = 22.2), -155.20 (t, 1F, J =
22.2), -163.28 (m, 4F), -163.65 (m, 2F). MS (ESI): 1144.1
([M+]). UV-vis (CH2Cl2, nm, ε Â 10-3 M-1 cm-1): 390 (28),
412 (43), 582 (12), 619 (6.5).
EPR Spectroscopy. Solutions for EPR were prepared
by adding 50 μL of a 10 mM CH2Cl2 solution of iodine to 100
μL of a 1 mM CH2Cl2 solution of the corrole being examined,
ensuring complete one-electron oxidation of the substrate. To
rule out side reactions with iodine, sub-stoichiometric amounts
of the radical cation tris(4-bromophenyl)aminium hexachlor-
oantimonate (t-4bpa) also were employed for oxidations. Spec-
tra taken of the products obtained from reactions with both
oxidants were virtually identical. EPR spectroscopy was per-
formed using a Bruker EMX Biospin instrument, with a Gunn
diode microwave source. Solutions were pre-cooled by rapid
freezing in liquid nitrogen; spectra of samples at 20 K were
obtained using liquid helium as a coolant. The SPINCOUNT
package was used to simulate EPR parameters.27
(25) A 140 μL portion of a solution of 0.5 mL of trifluoroacetic acid in 5
mL of CH2Cl2 was added to 1.73 mL of warm (liquid) pentafluorobenzal-
dehyde, with rapid stirring. Addition of 1.46 mL of freshly distilled pyrrole
resulted in the rapid formation of a viscous red solution. After 10 min, 20 mL
of CH2Cl2 was added and the mixture was allowed to stir briefly, followed by
slow addition of 3.84 g of DDQ to oxidize the newly formed macrocycle.
Purification was accomplished by successive chromatographic treatments
with 6.5:3.5 CH2Cl2/hexanes and 8.5:1.5 CH2Cl2/hexanes on silica, followed
by recrystallization from hot pentane.
(26) (a) Simkhovich, L.; Galili, N.; Saltsman, I.; Goldberg, I.; Gross, Z.
Inorg. Chem. 2000, 39, 2704–2705. (b) Mahammed, A.; Giladi, I.; Goldberg, I.;
Gross, Z. Chem.;Eur. J. 2001, 7, 4259–4265.
(27) Golombek, A. P.; Hendrich, M. P. J. Magn. Reson. 2003, 165, 33–48.