Inorganic Chemistry
Article
Syntheses. The free-base triarylcorroles (H3TArC) 1−6 were
prepared according to published procedures.4,6,15−17 The iron
complexes were then prepared following two similar procedures,
referred to as Method A and Method B, which differ from each other
by the amount of iron chloride in the nitration reaction medium.
Method A. H3TArC (1 mmol) and FeCl2 (20 mmol) were
dissolved in DMF (30 mL), and the resulting mixture was heated to
reflux; water was added to precipitate the product after formation of
the complex was evidenced by UV−vis spectrophotometry and TLC.
The precipitate was then filtered, dissolved in CH2Cl2, and dried over
anhydrous Na2SO4, and after evaporating the solvent under vacuum,
the residue was used without further purification for the nitration
reaction. For this purpose, the iron complex was dissolved in DMF,
and NaNO2 (150 mmol) was added. The progress of the reaction was
monitored by TLC and UV−vis spectrophotometry, following the
disappearance of the starting material. After precipitation by addition
of water and filtration, the crude mixture was dissolved in CH2Cl2 and
dried over anhydrous Na2SO4, and the solvent was evaporated.
Purification by chromatography on a silica gel column using CH2Cl2
(or CHCl3 for TNPC and TF5PC) as eluant, followed by
recrystallization from CH2Cl2/MeOH (1:2), afforded the desired
compounds.
Method B. H3TArC (1 mmol) was dissolved in DMF (30 mL);
FeCl2 (5 mmol) was added, and the resulting solution was refluxed for
90 min. During this period the color changed from purple to brown,
indicating formation of the corresponding iron complex, which was
confirmed by UV−vis spectrophotometry. NaNO2 (150 mmol) was
then added to the hot solution and the progress of the reaction
monitored by TLC and UV−vis spectrophotometry. After allowing the
reaction to proceed for 45 to 120 min (the exact time depending on
the specific starting corrole), water was added and the precipitate was
collected after filtration. The subsequent reaction workup was
performed as described in Method A.
3,17-(NO2)2-(TF5PC)FeNO 21. 1H NMR (300 MHz, CDCl3, J
[Hz]): δ = 8.98, (s, 2H, β-pyrrole), 7.86 (d, 2H, J = 4.8, β-pyrrole),
7.75 (d, 2H, J = 4.8, β-pyrrole). UV−vis CH2Cl2): λmax = 396, 613 nm.
MS (FAB): m/z 939 (M+ − NO). Anal. Calcd for C37H6F15FeN7O5:
C, 45.85; H, 0.62; N, 10.12. Found: C, 45.79; H, 0.68; N, 10.15.
3,17-(NO2)2-(TCl2PC)FeNO 22. 1H NMR (300 MHz, CDCl3, J
[Hz]): δ = 8.79, (s, 2H, β-pyrrole), 7.66−7.61 (m, 11H, phenyl and β-
pyrrole), 7.49 (d, 2H, J = 5.0 β-pyrrole). UV−vis (CH2Cl2): λmax (log
ε) = 393 (4.7), 620 nm (4.5). MS (FAB): m/z 876 (M+ − NO). Anal.
Calcd for C37H15Cl6FeN7O5: C, 49.04; H, 1.67; N, 10.82. Found: C,
48.97; H, 1.62; N, 10.78.
[3,17-(NO2)2-(TTC)Fe]2O 23. 1H NMR (300 MHz, CDCl3, J [Hz]):
δ = 7.87 (s, 2H, β-pyrrole), 7.55−7.22 (m, 12H, phenyl and β-
pyrrole), 7.10 (d, 2H, J = 4.60, β-pyrrole), 6.84 (br d, 1 H, J = 6.9,
phenyl), 6.61 (br d, 1H, J = 7.0 phenyl), 2.59 (s, 6H, −CH3), 2.43 (s,
3H, −CH3). Anal. Calcd for C80H54Fe2N12O9: C, 66.77; H, 3.78; N,
11.68. Found: C, 66.73; H, 3.81; N, 11.62.
[3,17-(NO2)2-(TF5PC)Fe]2O 24. 1H NMR (300 MHz, CDCl3, J
[Hz]): δ = 7.95, (s, 2H, β-pyrrole), 6.96 (d, 2H, J = 4.8, β-pyrrole),
6.88 (d, 2H, J = 4.8, β-pyrrole). UV−vis CH2Cl2): λmax (log ε) = 416
(4.8), 579 (4.6), 646 nm (4.3). MS (FAB): m/z 939 (M+-3,17-
(NO2)2-(TF5PC)FeO). Anal. Calcd for C74H12F30Fe2N12O9: C, 46.91;
H, 0.64; N, 8.87. Found: C, 46.87; H, 0.57; N, 8.93.
Crystal Data for 3,17-(NO2)2-(TPC)FeNO 17. Crystals were grown
by slow diffusion of methanol in a concentrated dichloromethane
solution. Single crystal X-ray diffraction data was collected on a Nonius
KappaCCD diffractometer with a Mo Kα radiation source (λ =
0.71073 Å), graphite monochromator, and Oxford Cryosystems liquid
nitrogen cryostream cooler. The structure was solved by direct
methods using SIR9720 and refined using SHELXL97.21 All non-
hydrogen atoms were refined anisotropically for the two independent
Fe corroles in the unit cell, with H atoms in idealized positions with a
C−H bond length of 0.95 Å. Missing symmetry was sought using the
ADDSYM algorithm within the PLATON single-crystal structure
validation program.22 Crystal data: C37H21FeN7O5, Mr = 699.46 g
The yields of the products, for each of the two described methods,
are listed in Table 1.
mol−1, triclinic, space group P1, a = 10.4813 (15) Å, b = 14.3141 (15)
̅
(TArPC)FeNO. 7, 8, 9, 10, and 11 were characterized by comparison
with an authentic sample prepared according to literature methods,18
while 12 was isolated in trace amounts and identified by comparison
with literature UV−vis data.19 Spectroscopic data for 13, 14, 17, and
18 were in agreement with data reported earlier in the literature.12
Å, c = 21.830 (3) Å, α = 74.161 (5)°, β = 77.960 (4)°, γ = 80.100 (5)°,
V = 3058.5 (6) Å3, Z = 4, F(000) = 1432, Dx = 1.519 g cm−3, μ = 0.55
mm−1, T = 100 K, 35466 measured reflections, 17810 independent
reflections, 9725 reflections with I > 2σ(I), Rint = 0.064, θmax = 30.0°,
θmin = 2.8°, full-matrix least-squares refinement on F2, R1[F2 > 2σ(F2)]
= 0.058, wR2(F2) = 0.161, S = 1.03, 901 parameters, 0 restraints, w =
1
3-NO2-(TMOPC)FeNO 15. H NMR (300 MHz, CDCl3, J [Hz]): δ
2
1/[ σ2(Fo ) + (0.0765P)2], Δρmax = 0.94 e Å−3, and Δρmin = −0.34 e
= 8.47 (s, 1H, β-pyrrole), 7.98 (d, 1H, J = 4.6, β-pyrrole), 7.89 (d, 1H,
J = 4.5, β-pyrrole), 7.82 (d, 2H, J = 8.5, phenyl), 7.68 (m, 7H, β-
pyrrole and phenyl), 7.55 (d, 1H, J = 4.9, β-pyrrole), 7.15 (m, 6H,
phenyl), 4.01 (s, 3H, −OCH3), 3.99 (s, 3H, −OCH3) 3.97 (s, 3H,
−OCH3). UV−vis (CH2Cl2): λmax (log ε) = 431 (4.8), 568 nm (4.3).
MS (FAB): m/z 714 (M+ − NO). Anal. Calcd for C40H28FeN6O6: C,
64.53; H, 3.79; N, 11.29. Found: C, 64.44; H, 3.84; N, 11.18.
3-NO2-(TNPC)FeNO 16. 1H NMR (300 MHz, CDCl3, J [Hz]): δ =
8.71 (s, 1H, β-pyrrole), 8.53 (m, 6H, phenyl), 8.19 (d, 1H, J = 4.65, β-
pyrrole), 8.08 (d, 2H, J = 7.74, phenyl), 8.00 (d, 1H, J =8.1, phenyl),
7.91 (m, 4H, phenyl), 7.70 (d, 1H, J = 4.8, β-pyrrole), 7.63 (d, 1H, J =
4.9, β-pyrrole), 7.55 (d, 1H, J = 4.8, β-pyrrole), 7.49 (d, 1H, J = 5, β-
pyrrole). UV−vis (CH2Cl2): λmax (log ε) = 423 (4.9), 588 nm (4.5).
MS (FAB): m/z 759 (M+ − NO). Anal. Calcd for C37H19FeN9O9: C,
56.29; H, 2.43; N, 15.97. Found: C, 56.18; H, 2.61; N, 16.01.
Å−3.
RESULTS AND DISCUSSION
■
In a previous communication, we reported the nitration of
(TTC)FeCl in DMF by using an excess of NaNO2; in
particular, we observed the formation of three types of Fe(III)
nitrosyl corroles using a 1:100 molar ratio of corrole vs
NaNO2those with an unsubstituted macrocycle, those with
one β-pyrrole NO2 substituent, and those with two β-pyrrole
NO2 substituents (Scheme 1). Upon increasing the amount of
NaNO2 (1:500), the dinitro-substituted corrole became the
major product of the reaction (60% yield), and the other
corroles were formed in only trace amounts.
1
3,17-(NO2)2 -(TMOPC)FeNO 19. H NMR (300 MHz, CDCl3, J
[Hz]): δ = 8.48 (s, 2H, β-pyrrole), 7.89 (d, 2H, J = 5, β-pyrrole), 7.70
(m, 8H, β-pyrrole and phenyl), 7.15 (m, 6H, phenyl), 4.00 (s, 3H,
−OCH3), 3.98 (s, 6H, −OCH3). UV−vis (CH2Cl2): λmax (log ε) = 370
(4.6), 437 (4.6), 593 nm (4.4). MS (FAB): m/z 759 (M+ − NO).
Anal. Calcd for C40H27FeN7O8: C, 60.85; H, 3.45; N, 12.42. Found: C,
60.78; H, 3.61; N, 12.39.
Syntheses of the desired products were achieved using a
1:150 molar ratio of (TArPC)FeNO/NaNO2. We have now
modified the initially reported protocol,12 with the aim of using
the free-base corrole as starting material, thus avoiding the need
for purification of an intermediate iron corrole complex.
Following the procedure described in Method A, we obtained
all three products indicated in Scheme 1, while with Method B
synthesis of the dinitrocorrole was optimized as a unique
reaction product.
3,17-(NO2)2-(TNPC)FeNO 20. 1H NMR (300 MHz, CDCl3, J [Hz]):
δ = 8.75 (s, 2H, β-pyrrole), 8.56 (m, 6H, phenyl), 7.96 (m, 6H,
phenyl), 7.78 (d, 2H, J = 5.0, β-pyrrole), 7.63 (d, 2H, J = 5.0, β-
pyrrole). UV−vis (CH2Cl2): λmax (log ε) = 402 (4.9), 609 nm (4.6).
MS (FAB): m/z 804 (M+ − NO). Anal. Calcd for C37H18FeN10O11: C,
53.26; H, 2.17; N, 16.79. Found: C, 53.22; H, 2.21; N, 16.68.
The reaction yields, calculated with respect to the starting
free-base corrole, are comparable with those obtained from the
3912
dx.doi.org/10.1021/ic3002459 | Inorg. Chem. 2012, 51, 3910−3920