Manganese Complexes
FULL PAPER
O) moiety (Figure 2). The electrophilic character of 2 and 3
(40 mL) was added to the resulting solution to yield a dark green
powder, which was collected by filtration, washed with Et O, and dried
2
under vacuum. Yield: 0.02 g (69%). Spectroscopic data including UV/
Vis, resonance Raman, and ESI-MS are reported in Figure 3. Resonance
2
was tested in the oxidation of PPh and xanthene. Upon ad-
3
dition of the substrates to 2 and 3 in CF CH OH at 208C,
3
2
the intermediates remained intact without showing any ab-
sorption spectral change, and product analysis of the reac-
tion solutions revealed that no oxygenated products were
formed in the reactions. These results demonstrate that 2
and 3 are not capable of conducting an electrophilic oxida-
Raman spectra of 3 were measured in CH OH on
3
CN instead of CF
3
CH
2
III
account of an overlap with intense solvent bands. [Mn ACHTUNGTRENNUNG( 12-TMC)-
1
8
2+
18
18
A
H
U
G
R
N
N
2
was prepared by adding H
2
O
2
(5 equiv; 525 mL, 90% O-en-
in water) to a solution that contained 1 (30 mm) and
CH OH (2 mL) at ambient temperature.
1
8
2
O
2
3
2
[20]
tion reaction.
8
tific Instruments for low-temperature experiments or with a circulating
water bath. Electrospray ionization mass spectra were collected using a
Thermo Finnigan (San Jose, CA, USA) LCQ Advantage MAX quadru-
pole ion-trap instrument, by infusing samples directly into the source
using a manual method. The spray voltage was set at 4.2 kV and the ca-
pillary temperature at 808C. Resonance Raman spectra were obtained
Conclusion
We have shown the formation of two different intermediates
in the reaction of a manganese complex that bears a 12-
TMC ligand and H O depending on the concentration of
the starting Mn complex (i.e., a mononuclear Mn –peroxo
complex at a low concentration and a dinuclear bis(m-oxo)-
complex at a high concentration). DFT-optimized
structures agree with the crystal structures with RMSD
values of 0.03 and 0.11 ꢁ for 2 and 3, respectively. The ex-
cellent agreement of the former species gives credibility to
the DFT-calculated structure of the latter one, which is in
good agreement with the crystal structure even as it suffers
using
a liquid-nitrogen-cooled CCD detector (Symphony 1024ꢂ256,
HORIBA) attached to a 1 m single polychromator (MC-100DG, Ritsu
2
2
À1
II
III
Oyo Kogaku) with a 1200 groovesmm holographic grating. An excita-
+
tion wavelength of 363.8 nm was provided by an Ar laser (Spectra Phys-
AHCTUNGTRENNUNG
ics, BeamLok 2080) with 20 mW power at the sample point. All measure-
ments were carried out with a spinning cell (400 rpm) at À208C. Raman
shifts were calibrated with indene, and the accuracy of the peak positions
III
ACHTUNGTRENNUNGM n
2
À1
of the Raman bands was Æ1 cm . Product analysis was performed using
an Agilent Technologies 6890N gas chromatograph and Thermo Finnigan
(
Austin, Texas, USA) FOCUS DSQ (dual stage quadrupole) mass spec-
trometer interfaced with a Finnigan FOCUS gas chromatograph (GC-
MS).
III
from severe disorder. In reactivity studies, only the Mn –
X-ray crystallography: Single crystals of 2-(ClO ) were picked from solu-
4
peroxo complex showed nucleophilic character in the defor-
mylation of aldehydes.
tions by a nylon loop (Hampton Research Co.) on a handmade copper
plate mounted inside a liquid N
2
Dewar vessel at approximately À408C
and mounted on a goniometer head in a N
2
cryostream. Data collections
were carried out using a Bruker SMART APEX II CCD diffractometer
equipped with a monochromator in the MoKa (l=0.71073 ꢁ) incident
beam. The CCD data were integrated and scaled using the Bruker-
SAINT software package, and the structure was solved and refined using
Experimental Section
[
23]
4
SHELXTL V6.12. Compound 2-(ClO ) crystallized with two crystallo-
Materials: All chemicals obtained from Aldrich Chemical Co. were the
best available purity and used without further purification unless other-
wise indicated. Solvents were dried according to published procedures
graphically independent but virtually identical cations in the asymmetric
unit (denoted “A” and “B”). Two oxygen atoms in 2A and 2B were
found to be disordered over two positions. Hydrogen atoms were located
[
21]
18
18
and distilled under Ar prior to use.
H
2
O
2
(95% O-enriched, 2%
in water) was purchased from ICON Services Inc. (Summit, NJ,
USA). The 12-TMC was prepared by treating an excess amount of form-
1
8
in the calculated positions for 2-(ClO ).
4
2 2
H O
Crystal data for 2-(ClO
4 4 6
): C12H28ClMnN O ; monoclinic, P21/n; Z=8;
[
22]
III
aldehyde and formic acid with 1,4,7,10-tetraazacyclododecane. [Mn
-
a=21.9331(6), b=7.6475(2), c=22.3583(6) ꢁ; b=98.958(2)8; V=
+
III
+
3
À1
À3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(13-TMC)(O
the literature methods.
Synthesis and characterization of [Mn
TMC (0.5 g, 2.19 mmol) was added to a solution of Mn
.19 mmol) in acetonitrile (0.5 mL). The mixture was stirred for several
hours, and then Et O (4 mL) was added to the resulting solution to yield
a white powder, which was collected by filtration, washed with Et O, and
dried under vacuum. Yield: 0.87 g (68%); UV/Vis (CH CN): see
Figure 1; ESI-MS (CH CN; Figure S1 in the Supporting Information):
m/z: 162.0 [Mn(12-TMC)
2
)] and [Mn
A
H
U
T
E
N
N
(14-TMC)(O
2
)] were prepared according to
1 2
3704.49(17) ꢁ ; m=0.891 mm ; 1calcd =1.487 gcm ; R =0.0531, wR =
[
7]
0.1534 for 7291 unique reflections, 477 variables. The crystallographic
II
data for 2-(ClO ) are listed in Table S1 of the Supporting Information,
A
H
U
G
R
N
U
G
A( OTf)
H
U
G
R
N
N
2
(1-
A
H
U
G
R
N
U
G
2
): 12-
4
II
and Table S2 of the Supporting Information lists the selected bond
lengths and angles.
A
H
U
G
R
N
U
G
2
2
4
CCDC-914131 (2-(ClO )) contains the supplementary crystallographic
2
data for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
2
3
3
2
+
+
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
A
H
U
G
R
N
U
G
3
CN)] , 432.2 [Mn AHCTUNGTRENNUNG( 12-TMC) ACHTUNGRTENNUNG( OTf)] .
DFT calculations: Calculations were carried out with the BP86 function-
III
+
[24]
Generation and characterization of [Mn
of 1 (1 mm) with H
equiv) in CF CH OH (2 mL) afforded the formation of a green solution
A
H
U
G
R
N
N
(12-TMC)(O
2
)] (2): Treatment
al. Although there are other functionals that are considered superior in
giving accurate energies (i.e., B3LYP), this functional is known to give
fairly good geometrical structures that many times surpass B3LYP. As
our main concern here is structural parameters rather than energies, this
functional was deemed to fit our purposes better. The basis set used was
2
O
2
(5 equiv) in the presence of triethylamine (TEA;
2
3
2
at 208C. Spectroscopic data including UV/Vis and ESI-MS are reported
III
18
+
18
in Figure 1. [Mn
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(12-TMC)
A
H
U
G
R
N
U
G
2
)] was prepared by adding H
2
O
2
1
8
18
[25]
[26]
(
5 equiv; 18 mL, 90% O-enriched, 2% H
of TEA (2 equiv) in CF CH
able crystals were obtained by slow diffusion of Et
the complex with an excess amount of NaClO . Caution: Perchlorate
salts are potentially explosive and should be handled with care!
2
O
2
in water) in the presence
TZVP (except on Mn) using the ORCA program. Mn atoms used a
[
27]
3
2
OH at 208C. X-ray crystallographically suit-
O into a solution of
triply polarized core-properties basis set CP
A( PPP)
H
U
G
R
N
U
G
as defined in
ORCA, with an enhanced integration grid in which the overall integra-
tion accuracy was increased to 7. Solvent (acetonitrile) effects were mod-
2
4
[
28]
eled with the COSMO scheme and was included in the optimizations.
[29]
III
2+
2
The RMSD values were calculated using VMD.
Generation and characterization of [Mn
ment of 1 (50 mm) with H (5 equiv) in the presence of TEA (2 equiv)
in CF CH OH (1 mL) afforded the formation of an olive green solution
at 208C. The mixture was stirred for several hours, and then Et
A
H
U
G
R
N
N
(12-TMC)(O)]
(3): Treat-
2
O
2
Kinetic measurements: All reactions were run by monitoring UV/Vis
3
2
spectral changes of reaction solutions, and rate constants were deter-
III
2
O
mined by fitting the changes in absorbance at 610 nm for [Mn ACHTUNGTRENNUNG( 12-
Chem. Eur. J. 2013, 19, 14119 – 14125
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
14123