FULL PAPER
acetonitrile. Dark red, single crystals suitable for X-ray analysis
were obtained (28 mg, 69%). C28H30FeN3O3 (512.41): calcd. C
65.63, H 5.90, N 8.20; found C 65.45, H 5.99, N 8.05. ESI-MS
(negative mode in MeOH + 0.1% HCOOH): m/z (%) = 475.0 (100)
[FeL1 HCOO]–, 465.0 (58) [FeL1Cl]–, 543.0 (47) [FeL1CF3COO]–.
(MIUR) – (PRIN-2010-11 2010CX2TLM_002) E. B. fellowship.
The work has been carried out in the frame of COST Action
CM1003 Biological oxidation reactions – mechanisms and design of
new catalysts and Action CM1205 CARISMA, Catalytic Routines
for Small Molecules Activation. Dr. Andrea Sartorel and Dr. Elisa-
betta Benazzi are acknowledged for catalase oxygen evolution ex-
periments.
[FeIIIL2(1-Meim)] (2): An identical procedure to that described
above for 1 was employed by using H3L2 (20 mg, 0.040 mmol) and
dry triethylamine (0.017 mL, 0.12 mmol) in dry methanol (2 mL),
followed by a solution of FeCl3 (0.10 mL, 0.040 mmol) and 1-N-
methylimidazole (0.01 mL, 0.12 mmol). The precipitate was filtered
out. Brownish crystals not suitable for X-ray analysis were obtained
by re-crystallization from a mixture of acetonitrile and dichloro-
methane (18 mg, 70%). C37H48FeN3O3 (638.65): calcd. C 69.58, H
7.56, N 6.58; found C 69.51, H 7.70, N 6.67. ESI-MS (negative
mode in MeOH + 0.1% HCOOH): m/z (%) = 669.4 (100)
[FeL2CF3COO]–, 591.5 (89) [FeL2Cl]–, 601.5 (37) [FeL2HCOO]–.
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[FeIIIL3(1-Meim)] (3): An identical procedure to that described
above for 1 was employed by using H3L3 (55.4 mg, 0.098 mmol)
and dry triethylamine (0.042 mL, 0.30 mmol) in dry dichlorometh-
ane (5 mL), followed by a solution of FeCl3 (0.25 mL, 0.098 mmol)
and 1-N-methylimidazole (0.24 mL, 0.30 mmol). The mixture was
stirred for 2 hours at room temperature. The solvent was evapo-
rated in vacuo, and the residue was redissolved in methanol. The
purple precipitate was filtered out and recrystallized from a mixture
of acetonitrile and dichloromethane. Red–brown crystals suitable
for X-ray analysis were obtained (50 mg, 73%). C43H36FeN3O3
(698.62): calcd. C 73.93, H 5.19, N 6.01; found C 74.02, H 5.06, N
6.15. ESI-MS (negative mode in MeOH + 0.1% HCOOH): m/z
(%) = 661.2 (100) [FeL3HCOO]–, 651.2 (96) [FeL3Cl]–, 729.1 (67)
[FeL3CF3COO]–.
General Procedure for the Catalytic Activity Study Towards Oxid-
ation of 3,5-Di-tert-buthylcatechol: A mixture of 3,5-di-tert-buthyl-
catechol (0.02 mmol), piperidine (0.04 mmol) and p-dinitrobenzene
as internal standard (0.02 mmol) was prepared in CDCl3 (0.5 mL)
in a screw-capped NMR tube. Molecular oxygen was bubbled
through the solution for 5 min. The conversion was monitored by
1H NMR spectroscopy at room temperature. The experiment was
repeated by adding the iron(III) complexes 1–3 (0.002 mmol
10 mol-%) to the mixture above in the presence and in the absence
of piperidine.
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General Procedure for Hydrogen Peroxide Dismutase Experiments:
The catalytic dismutation of hydrogen peroxide was performed in
12 mL glass vials with pressure/voltage transducers mounted into
the reaction headspace. The evolution of O2 was monitored by
using a home-made interface designed in LabView. In a typical
experiment, a freshly prepared 10 mL of solution of catalyst (3, 15
or 30 μm) in sodium phosphate buffer (50 mm, pH = 7.0) was al-
lowed to equilibrate at 25 °C while stirring for 10 min. Data collec-
tion over 3 min showed equilibration of the system. When a steady
baseline was achieved, an aliquot of H2O2 (0.330 mmol) was in-
jected into the reactor. Oxygen evolution started immediately and
was monitored until a plateau was observed. The amount of oxygen
dissolved in solution was assumed to be negligible. UV/Vis spectra
of the final reaction mixtures show signals superimposable with
those of the fresh catalysts.
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Acknowledgments
The research was funded by: Università di Padova (PRAT-
CPDA123307 and Progetto Attrezzature Scientifiche finalizzate
alla Ricerca 2010), Ministero dellЈUniversità e della Ricerca
Eur. J. Inorg. Chem. 2015, 3478–3484
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