Synthesis, crystal structures and catalytic abilities of new macrocyclic bis-pyridineamido MnIII and FeIII complexes

Article abstract of DOI:10.1016/j.jorganchem.2009.03.019

A new macrocyclic ligand H₂L (H₂L = 1,2-[bis(6′-pyridine-2′-carboxamido)-ethane]benzene) has been designed and synthesized by condensation of pyridine-carboxylic acid and diamine. Its Mn(III) and Fe(III) complexes, [Mn(L)Cl (DMF)] an

Full text of DOI:10.1016/j.jorganchem.2009.03.019

Journal of Organometallic Chemistry 694 (2009) 2421–2426
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, crystal structures and catalytic abilities of new macrocyclic
bis-pyridineamido MnIII and FeIII complexes
Li Yang a,b, Zhiqing Wu a, Lei Liang a, Xiangge Zhou a,
*
a Institute of Homogeneous Catalysis, College of Chemistry, Sichuan University, Chengdu 610064, China
b Department of Chemical Engineering, Yibin University, Yibin 640000, China
a r t i c l e i n f o
a b s t r a c t
A new macrocyclic ligand H2L (H2L = 1,2-[bis(60-pyridine-20-carboxamido)-ethane]benzene) has been
designed and synthesized by condensation of pyridine-carboxylic acid and diamine. Its Mn(III) and Fe(III)
complexes, [Mn(L)Cl (DMF)] and [Fe(L)Cl], were prepared and respectively characterized by IR, UV–Vis,
ESI-Mass, elemental analysis and X-ray single crystal diffraction. The catalytic abilities of them were
examined, and up to 95% yield was achieved in epoxidation of styrene. The preliminary investigation
of catalytic mechanism by manganese complex was carried out, suggesting the involvement of Mn(V)
oxo species during catalysis.
Article history:
Received 13 January 2009
Received in revised form 25 February 2009
Accepted 13 March 2009
Available online 20 March 2009
Keywords:
Macrocyclic
Catalytic epoxidation
Catalytic mechanism
Bis-pyridineamido ligand
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
in is described the synthesis of novel macrocyclic bis-pyridineam-
ido complexes with cheap and relatively nontoxic Mn(III) and
Macrocyclic metal complexes have attracted considerable
attention as biomimetic models due to their similarities to oxida-
tion metalloenzymes found in biological systems [1,2]. There have
been numerous reports on the catalytic oxidation of organic sub-
strates by porphyrin complexes [3,4]. Meanwhile, development
of other planar tetradentate ligands, such as Schiff base and amido
ligands is highly desirable attributing to their facility in modifica-
tion [5–12].
As one of amido ligands, bis-pyridineamide seems to be a good
candidate for catalytic oxidation studies because of its stability to
resist oxidation. The negative charges might be highly delocalized,
which resembles the porphyrinato ligand to some extent as shown
in Scheme 1. Both Che [13–15] and us [16] reported recently that
bis-pyridineamide Mn(III)/Fe(III) complexes exhibited moderate
to high catalytic abilities in epoxidation of alkenes.
On the other hand, the mechanism studies revealed the high-
valent transition intermediates to be active oxidizing species
formed in metal-catalyzed oxidation reactions [17–19]. The forma-
tion of metal-oxo species by porphyrin- or salen-complex with oxi-
dant such as PhIO was also reported [20,21]. Aroused by the
research of Collins and co-workers, who described the macrocyclic
tetraamido ligands to be capable of stabilizing unusual high-valent
transition metal ions such as cobalt(IV) and iron(IV) [22–24], here-
Fe(III) ions [25], which exhibited higher catalytic abilities in epox-
idation than the non-annular analogs. The preliminary investiga-
tion of the catalytic mechanism is also reported.
2. Results and discussion
2.1. Synthesis of ligand and complexes
Ligand 5 and corresponding Mn(III) and Fe(III) complexes 6 and
7 were prepared starting from 2-methylpyridine as shown in
Scheme 2. 2-Methylpyridine was reacted with n-butyllithium and
1,2-dibromoethane to give a coupled pyridine 1. Peracid oxidation
followed by treatment with N,N-dimethylcarbamonyl chloride and
trimethylsilyl cyanide gave dinitrile derivative 3. After hydrolysis,
dicarboxylic acid 4 was obtained and then condensed with diamine
to give the ligand 5 with total yield of 31%. The manganese(III) and
iron(III) complexes 6 and 7 were then obtained by the reaction of
ligand 5 and corresponding metal ion in DMF.
The new tetradentate ligand 5 and corresponding complexes 6
and 7 are in general air- and moisture-stable. All the complexes
were characterized by MS, IR, UV–Vis, and elemental analysis,
the single crystal structures of the compounds 5, 6 and 7 have also
been determined. The infrared spectra of the ligand and complexes
displayed, in general, a large number of intense peaks in the range
of 1600–600 cmꢀ1
. Disappearance of N–H stretching bands
(3291 cmꢀ1) in IR spectra supported the formation of Mn(III) and
Fe(III) complexes.
* Corresponding author. Tel./fax: +86 28 85412026.
E-mail address: zhouxiangge@scu.edu.cn (X. Zhou).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.03.019

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L. Yang et al. / Journal of Organometallic Chemistry 694 (2009) 2421–2426
Table 1
Selected bond lengths (Å), bond angles (°).
Ligand 5
N(1)–C(1)
C(11)–C(12)
1.407(3)
1.394(4)
N(1)–C(7)
C(14)–C(15)
1.350(3)
1.491(4)
C(7)–N(1)–C(1)
C(12)–C(13)–C(14)
N(1)–C(7)–C(8)
129.9(2)
113.6(2)
111.1(2)
N(4)–C(20)–C(19)
C(20)–N(4)–C(2)
C(15)–C(14)–C(13)
112.9(3)
127.6(3)
114.0(3)
Scheme 1. Some of usually used planar tetradentate ligands.
Complex 6
Mn(1)–N(1)
1.947(3)
Mn(1)–N(3)
1.998(3)
Mn(1)–N(2)
Mn(1)–O(3)
1.943(2)
2.428(3)
Mn(1)–N(4)
Mn(1)–O(3)
2.011(2)
2.428(3)
Mn(1)–Cl(1)
2.4934(12)
80.90(13)
161.35(12)
81.53(13)
89.37(11)
82.56(11)
84.67(10)
99.98(9)
N(1)–Mn(1)–N(4)
N(2)–Mn(1)–N(4)
N(3)–Mn(1)–N(4)
N(2)–Mn(1)–O(3)
N(4)–Mn(1)–Cl(1)
N(2)–Mn(1)–Cl(1)
N(3)–Mn(1)–Cl(1)
O(3)–Mn(1)–Cl(1)
82.56(12)
159.94(11)
113.20(13)
83.88(10)
91.67(8)
102.29(8)
89.84(8)
169.45(8)
N(1)–Mn(1)–N(2)
N(1)–Mn(1)–N(3)
N(2)–Mn(1)–N(3)
N(1)–Mn(1)–O(3)
N(3)–Mn(1)–O(3)
N(4)–Mn(1)–O(3)
N(1)–Mn(1)–Cl(1)
Complex 7
Fe(1)–N(1)
Fe(1)–N(2)
Fe(1)–N(3)
N(1)–Fe(1)–N(4)
N(1)–Fe(1)–N(2)
N(4)–Fe(1)–N(3)
N(1)–Fe(1)–Cl(1)
N(3)–Fe(1)–Cl(1)
1.871(2)
2.032(2)
2.016(2)
82.38(10)
82.39(10)
82.51(9)
101.67(8)
93.53(7)
Fe(1)–N(4)
Fe(1)–Cl(1)
1.889(2)
2.3080(8)
161.28(10)
155.32(10)
107.69(10)
108.32(8)
93.71(7)
N(1)–Fe(1)–N(3)
N(4)–Fe(1)–N(2)
N(3)–Fe(1)–N(2)
N(4)–Fe(1)–Cl(1)
N(2)–Fe(1)–Cl(1)
Scheme 2. Synthetic routine of ligand and complexes.
2.2. Structures of the ligand and complexes
2.2.1. Ligand 5
The single crystal structure of 5 is shown in Fig. 1. The selected
bond distances and angles are listed in Table 1. The dihedral angle
between the 1,2-diaminobenzene unit and the pyridyl ring is about
34°, two pyridyl rings are nearly parallel to each other. The average
distance of N1–N3 and N2–N4 is around 4.0 Å, which is suitable for
the coordination with Fe(III)/Mn(III) metal ions.
2.2.2. [Mn(L)Cl(DMF)] (6)
The crystal structure of 6 is shown in Fig. 2, and selected bond
distances and angles are listed in Table 1. As shown in Fig. 2, depro-
tonated ligand 5 provides two neutral pyridine N and two anionic
carboxamido N donors in the equatorial plane for coordination,
while the two axial positions are occupied by DMF and Clꢀ leading
to a distorted octahedral configuration. The average distance of
Fig. 2. Molecular structure of 6 with thermal ellipsoids set at 30% probability.
Mn–Namide (1.945 Å) is shorter than that of Mn–Npyridine (2.00 Å).
Both the Mn–Cl and Mn–ODMF distances are slightly longer than
those of non-annular complexes such as H2bpc(1,2-bis(pyridine-
20-carboxamido)-4,5-dichloro-benzene) [26], H2bmpc(1,2-bis(40-
methylpyridine-20-carboxamido)-4,5-dichlorobenzene) reported
by us [27].
2.2.3. [Fe(L)Cl] (7)
A perspective view of compound 7 is depicted in Fig. 3. The
selected bond distances and angles are listed in Table 1.
As shown in Fig. 3, complex 7 adopts a five-coordinated structure
with two pyridine and two deprotonated amide N atoms in the
equatorial plane, the axial position is occupied by the Clꢀ ion. Inter-
estingly, dinuclear complexes were observed in the packing plot of
complex 7, crosslinked by the weak intermolecular Fe–Oamide
(3.011 Å) interactions compared with the normal Fe–Oamide dis-
tance of about 2.0 Å. The Fe(III)–Npyridine distances of 2.016–
Fig. 1. Molecular structure of 5 with thermal ellipsoid set at 30% probability.

L. Yang et al. / Journal of Organometallic Chemistry 694 (2009) 2421–2426
2423
separation of 139 mV between them (
D
Ep = Epa ꢀ Epc), indicating
a pseudo-reversible one-electron redox (FeIII–FeII) and E1/2[Epa
+
Epc/2] is equal to ꢀ0.82 mV (vs. SCE).
2.4. Catalytic epoxidation
The catalytic activities of complexes 6 and 7 were examined in
the epoxidation of styrene with oxidants such as PhIO, NaClO or
H2O2 as shown in Scheme 3.
In general, among these oxidants, PhIO showed to be beneficial
to the catalysis, while the other two oxidants H2O2 and NaClO re-
sulted in less than 15% yields in all cases under the reaction condi-
tions. The results of catalytic epoxidation of styrene by 6 and 7
with PhIO were listed in Table 2. It is observed that the yield in-
creased considerably within the first 3 h during reaction. After that,
the yields increased slightly, which results from the appearance of
the oxidative-cleavage product, namely benzaldehyde. Similar
with our previous study [16], central metal plays an important
role, and Mn(III) complex exhibited much higher catalytic ability
and selectivity than Fe(III) analogue (entries 1 and 11, or 3 and
13, Table 2). The same rule could also be observed in salen and por-
phyrin systems [32–34]. It is presumed that the easier formation of
high-valent Mn complex resulted in the higher catalytic ability
than Fe analogue during reaction [35].
Variation of the amount of catalyst was also studied. When 1%,
2%, 5%, 7% or 10% catalyst 6 was applied, styrene oxide was ob-
tained in the yields 88%, 90%, 94%, 94% or 95%, respectively. It sug-
gested that more catalyst than 5% was not necessary. Solvent, on
the other hand, exhibited significant influence on the results, here
acetonitrile (entries 1–3, Table 2) was chosen as the best. Polar
aprotic solvent seemed to be beneficial for the catalysis by Mn(III)
complex 6, while changing solvent seemed to be less effective on
the activity of 7 (entries 11–13, Table 2). Increasing the reaction
temperature resulted in the decline of yield (entries 3 and 10, Table
2).
More importantly, the novel designed macrocylic Mn(III) com-
plex showed much higher catalytic activity under similar condi-
tions than the non-annular analogue. For example, 6 gave the
yield of 94% in CH3CN (entry 3, Table 2), while only 69% was
achieved by non-annular analogue [Mn(bpc)Cl(DMF)] [15]. Thus,
the best result 95% yield could be obtained under the optimized
conditions by catalyst 6, which is comparable with about 90% by
Mn–porphyrin complex (2,8,12,18-tetrabutyl-3,7,13,17-tetra-
methyl-5,15-bis(4-pyridyl) porphyrinato manganese chloride)
[36], and much higher than 79% by Salen complex [37]. The other
two substrates cyclohexene and indene were also tried by this cat-
alytic system with moderate to high yields 72% and 85%,
respectively.
Fig. 3. Molecular structure of 7 with thermal ellipsoids set at 30% probability.
2.032 Å are comparable to those of 1.997–2.003 Å in the [Fe(bpc)(1-
MeIm)2]ClO4 [28], but considerably shorter than those of 2.170 and
2.174 Å in [Fe(bbpc)Cl2](Et4N) (H2bbpc = 1,2-bis(40-t-butylpyri-
dine-20-carboxamido)-4,5-dichlorobenzene) [29]. The Fe(III)–Namide
distances are 1.872–1.889 Å. Similar values (1.895–1.927 Å) in the
macrocylic Fe(IV)–tetraamide complex have also been reported
[30]. The Fe(III)–Cl distance of 2.308(1) Å was slightly shorter than
those of 2.330 and 2.388 Å in [Fe(bbpc)Cl2](Et4N) [29].
2.3. Electrochemistry
Complexes 6 and 7 were furthermore characterized by electro-
chemical study. The typical cyclic voltammograms recorded in
DMF with a glassycarbon working electrode are illustrated in
Fig. 4. The E1/2 and peak-to-peak separation (DEp) values of 6 were
ꢀ0.17 V (vs. SCE) and 80 mV, indicating a reversible one-electron
redox process (MnIII/MnII), which is in accordance with the
MnIII/MnII couple of non-annular complexes [Mn(bpc)X] (X = Cl,
N3,
NCS)(H2bpc = 1,2-bis(20-carboxamido)-4,5-dichlorobenzene)
[31]. Compared with 6, the cyclic voltammogram of 7 shows the
2.5. Catalytic mechanism study
The preliminary investigation in the mechanism of catalytic
epoxidation was then carried out with complex 6. The reaction be-
tween 6 and PhIO was monitored. During the reaction, the color of
solution slowly changed from brown to dark green, which was con-
sistent with Mn(V) porphyrin-oxo or nonporphyrin macrocyclic
tetraamido-oxo complexes [38,39]. The appearance of two new
peaks around 340 and 380 nm in UV–Vis spectrum is quite similar
Fig. 4. Cyclic voltammograms of a 1.0 ꢁ 10ꢀ3 M solution of 6 and 7 in anhydrous
DMF (0.1 M TBAP) at a glassy-carbon electrode (298 K), SCE at a reference electrode
with a scan rate of 200 mV Sꢀ1
.
Scheme 3. Catalytic epoxidation of styrene by catalyst 6 or 7.

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L. Yang et al. / Journal of Organometallic Chemistry 694 (2009) 2421–2426
Table 2
Epoxidation of styrene with PhIO catalyzed by complex 6 and 7.a
Entry
Cat
T (h)
T (°C)
Dosage (mol%)
Solvent
Conversion (%)b
Yield (%)b
1
2
3
4
5
6
7
8
6
6
6
6
6
6
6
6
6
6
7
7
7
8
8
8
8
8
8
8
16
12
5
25
25
25
25
25
25
25
ꢀ10
0
40
25
25
25
5
5
5
1
2
7
10
5
5
5
CH2Cl2
ClCH2CH2Cl
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH3CN
CH2Cl2
ClCH2CH2Cl
CH3CN
86
85
95
90
90
94
97
95
95
88
78
75
80
78
74
94
88
90
94
95
95
94
85
37
32
39
9
10
11
12
13
8
8
8
5
5
5
a
Reactions were performed by using catalyst, substrate (0.5 mmol) and PhIO (0.1 mmol) in 5 mL solvent.
Determined by GC based on PhIO used.
b
observed than the reported planar non-annular complexes. The
preliminary studies of catalytic mechanism indicated the catalysis
by 6 might include Mn(V)@O species. A series of asymmetric catal-
ysis assay by corresponding analogs are currently in progress in
our laboratory.
4. Experimental
4.1. Materials and reagents
THF was dried over sodium benzophenone ketyl and distilled
under N2 before use. Methanol was dried over magnesium meth-
oxide and distilled before use. Olefins were purchased from
Aldrich or Lancaster and purified by standard procedures before
use [42]. All other chemicals were obtained commercially and
used as received. Iodosylbenzene was prepared by hydrolysis of
iodobenzene diacetate with sodium hydroxide solution [43]. So-
dium cyanide was dried in vacuum at 120 °C. 1,2-Bis(20-pyri-
dyl)-ethane (1) was synthesized according to the literature
procedures [44]. Unless otherwise indicated, standard Schlenk
techniques were used during all syntheses to avoid exposure to
dioxygen or water.
Fig. 5. Plot of log kre1 vs. (r+
, rJJ) for the epoxidation of substituted styrenes p-
YC6H4CH@CH2 (Y = MeO, Me, F, Cl) by PhIO catalyzed by [Mn(L)(DMF)Cl]. The R
value for the multiple regressions is indicated.
to Mn(V)@O corrole species [40]. The electrospray ionization mass
spectrum of the mixture of 6 and PhIO in CH2Cl2 further confirms
the existence of [O@MnV(L)]+(H2L = 5) with the peak at m/z 413.
Presumably, the color conversion from brown to dark green pro-
ceeds simultaneously with the formation of metal-oxo species.
To probe the nature of the intermediates formed in the rate-
limiting step during the catalytic epoxidation by 6, the substitution
effect was examined by measuring the rates (krel) of substituted
styrenes para-YC6H4CH@CH2 (Y = MeO, Me, F, H, Cl) relative to that
of styrene, which revealed that electron-donating substituents pro-
4.2. Instrumentation/analytical procedures
All melting points were measured by a micro-melting apparatus
and uncorrected. Ultraviolet–Visible (UV–Vis) spectra were re-
corded on a HP 8453 spectrometer. 1H NMR and 13C NMR spectra
were recorded on a Bruker AV-400 (400 or 100 MHz) spectrometer.
Chemical shifts were measured relative to tetramethylsilane as the
internal reference. Gas chromatography (GC) measurements were
carried out on an Agilent 6890 series chromatograph equipped
with a flame ionization detector. Mass spectra data were recorded
on a Finnigan MAT 4510 spectrometer. Elemental analysis were
performed on a Carlo Erba 1106 instrument. IR spectra were
mote the epoxidation process. A dual-parameter (r+
, rJJ) fitting of
log(kX/kH), as established by Jiang [41], through multiple regres-
sion gave rise to good linearity (R = 0.992) with q+ and qJJ values
of ꢀ0.92 and 0.14, respectively (Fig. 5), suggesting that polar ef-
fects are dominant during catalysis.
Although it is difficult to delineate the accurate mechanism, on
the basis of our studies as well as references, it is suggested the
catalysis by 6 might include the Mn(V)@O species during reaction.
performed on
a NEXUS-670 FT-IR spectrophotometer in the
4000–400 cmꢀ1 region using KBr disks. Cyclic voltammetry of all
complexes was performed with a Autolab-Pgstat 302 electrochem-
ical analyzer, using a three-electrode system on conjunction with a
purged dinitrogen gas inlet and outlet. A saturated calomel refer-
ence electrode, a glassycarbon working electrode and a platinum
auxiliary electrode were used in this three-electrode measure-
ment. The complex was at 1.0 ꢁ 10ꢀ3 M concentration with tetra-
butylammonium percholrate (TBAP) (0.1 M) as the support
electrolyte in DMF solution. All solutions were purged with N2
prior to analysis.
3. Conclusion
Synthesis, structures and catalytic abilities in epoxidation of
olefins by novel macrocyclic bis-pyridineamido Mn(III) and Fe(III)
complexes have been reported. Higher catalytic abilities were

L. Yang et al. / Journal of Organometallic Chemistry 694 (2009) 2421–2426
2425
4.3. Synthesis of coupling pyridine bis(N-oxide) (2)
MS (EI): m/z = 344[M+]. Elemental Anal. Calc. for C20H16N4O2: C,
69.76; H, 4.65; N, 16.28. Found: C, 69.42; H, 4.78; N, 16.15%.
The method was similar with the literature procedure [45].
After removal of solvent, a slightly yellow solid was obtained with-
out further purification or characterization.
4.7. Synthesis of [Mn(L)Cl(DMF)] (6)
Two hundred and three milligrams ligand 5 (0.6 mmol) was dis-
solved in 50 mL hot DMF. 55 mg LiCl (1.3 mmol) and 160 mg
Mn(OAc)3 ꢂ 2H2O (0.6 mmol) were then added. The solution was
heated at 80 °C for 30 min. After removal of solvent under vacuum,
the brown solid product was obtained after recrystallization from
DMF/methanol. Yield: 170 mg (54%). Dark brown needles of 6 suit-
able for X-ray analysis were grown by diffusion of diethyl ether
into a DMF solution of the complex. Selected IR data (KBr, cmꢀ1):
4.4. Synthesis of 1,2-bis(2-(60-cyanopyridyl)-ethane (3)
Prepared by the modified method of Fife [46]. The solution of
coupling pyridine bis(N-oxide) 2 (8.6 g, 0.04 mol) in anhydrous
dichloromethane (150 mL) was added trimethylsilyl cyanide (8 g,
0.081 mol) at room temperature. Dimethylcarbamyl chloride
(8.7 mL, 0.08 mol) in dichloromethane (50 mL) was then added
dropwise with stirring over 30 min. The mixture was kept stirring
at room temperature for 6 days. A solution of 20% aqueous potas-
sium carbonate (80 mL) was added. The organic layer was sepa-
rated, and the aqueous layer was extracted twice with
dichloromethane (2 ꢁ 100 mL). The combined organic layers were
dried over anhydrous MgSO4, and concentrated in vacuo to obtain
the crude product. The off-white pure product was obtained by
washing with ethanol and dried in vacuo (7.1 g, 76%). M.p.
162.5–164 °C; 1H NMR (400 MHz, CDCl3): d = 3.34 (s, 4H,
–PyCH2CH2Py–), 7.41 (d, J = 8.0 Hz, 2H, HPy), 7.35(d, J = 7.6 Hz, 2H,
HPy), 7.73 (t, J = 7.6 Hz, 2H, HPy); 13CNMR (100 MHz, CDCl3):
d = 36.30, 117.42, 126.23, 127.02, 133.26, 137.23, 162.62.
m
= 1640 (C@O), 1598 (C–N), 1571, 1355, 1282, 1141, 1032, 1081,
759. Elemental Anal. Calc. for C23H21ClN5O3Mn: C, 54.61; H, 4.18;
N, 13.85. Found: C, 54.45; H, 4.34; N, 13.83%. MS (FAB): 397.3
([Mn(L)]+).
4.8. Synthesis of [Fe(L)Cl] (7)
One hundred and thirty-two milligrams ligand 5 (0.38 mmol)
and sodium acetate (0.08 g, 0.76 mmol) were added to 20 mL
CH3OH solution of FeCl3 ꢂ 6H2O (244 mg, 0.9 mmol). The color of
the mixture turned into green immediately. After the mixture
was refluxed for 3 h, the dark green crystals were collected by fil-
tration, washed with methanol, and dried under vacuum (123 mg,
yield 75%). Crystals suitable for X-ray diffraction were grown via
diffusion of Et2O into a DMF solution of the complex. Selected IR
4.5. Synthesis of 1,2-bis(2-(60-carboxylpyridyl)-ethane (4)
data (KBr, cmꢀ1):
m = 1629 (C@O), 1602 (C–N), 1572, 1346, 1287,
A solution of 3 (2.34 g, 0.01 mol) in 70 mL hot ethanol was added
70 mL 3 N sodium hydroxide. The mixture was kept at 85 °C for
3 days. The pH was adjusted to ca. 3–4 by 6 N HCl. A white precip-
itate was formed and collected by filtration, washed with water and
dried in vacuo to give product 2.36 g (87%): m.p. 212 °C. 1HNMR
(400 MHz, DMSO): d = 3.23 (s, 4H, ꢀPyCH2CH2Py–), 7.53(m, 2H,
HPy), 7.87(m, 4H, HPy); 13CNMR (100 MHz, DMSO): d = 36.66,
122.29, 126.27, 137.68, 147.74, 160.73, 166.22. MS (EI): m/z =
272[M+]. Elemental Anal. Calc. for C14H12N2O4: C, 61.76; H, 4.44;
N, 10.29. Found: C, 61.52; H, 4.76; N, 10.10%.
1142, 1083, 1081, 762. Elemental Anal. Calc. for C20H14ClN4O2Fe:
C, 55.39; H, 3.25; N, 12.92. Found: C, 55.61; H, 3.15; N, 13.00%.
MS (FAB): 398.3 ([Fe(L)]+).
4.9. General procedure for catalytic epoxidation of styrene
Iron(III) or manganese(III) complex, PhIO (0.1 mmol) and sty-
rene (0.5 mmol) in solvent (5 mL) were stirred at room tempera-
ture for 8 h. After filtration, the residue was determined by GC
with 1,4-dichlorobenzene as internal standard and the yields were
calculated based on PhIO used.
4.6. Synthesis of 1,2-[bis(60-pyridine-20-carboxamido)-
ethane]benzene (5)
4.10. General procedure for the competition experiments [48,49]
The ligand was prepared according to the similar method
with modification [47]. A solution of the acid 4 1.36 g (5 mmol)
in 50 mL dry pyridine was slowly added to a solution of 0.54 g
(5 mmol) o-phenylenediamine in 15 mL pyridine. After heating
the solution to 50 °C, 2.61 mL (10 mmol) triphenylphosphite
was added dropwise with continuous stirring. The temperature
was then raised and kept at 100 °C for 9 h, the mixture was
cooled down. After removal of pyridine under reduced pressure,
the resulting brown oil was dissolved in dichloromethane,
washed with water and sodium bicarbonate solution, and then
dried over magnesium sulphate. After filtration and removal of
solvent, the residue was washed with ethanol and dried in vacuo
to afford off-white pure product 0.94 g (yield 55%). Crystals suit-
able for X-ray diffraction were grown via slow evaporation of a
solution of the ligand in xylene/pyridine. m.p. 218–219 °C; 1H
NMR (400 MHz, CDCl3): d = 3.22 (s, 4H, –PyCH2CH2Py–), 7.20
(m, 2H, Hbenzene), 7.31 (d, J = 7.6 Hz, 2H, HPy), 7.77 (t, J = 8.0 Hz,
2H, HPy), 8.04 (d, J = 7.6 Hz, 2H, HPy), 8.19 (m, 2H, Hbenzene),
10.72 (s, 2H, Hamide); 13C NMR (100 MHz, CDCl3): d = 35.00,
118.66, 121.03, 124.00, 125.10, 127.44, 137.41, 148.31, 160.11,
A
10 mL round bottom flask was charged with styrene
(52.6 mg, 0.5 mmol), p-substituted styrene (0.5 mmol), 1,4-dichlo-
robenzene (0.5 mmol, internal standard), complex 6 (12.3 mg,
0.025 mmol), PhIO (0.5 mmol) and acetonitrile (2.0 mL) under
nitrogen. The reaction mixture was stirred for 8 h at room temper-
ature. After filtration, conversion of each olefin was determined by
GC analysis.
4.11. Crystallography
Diffraction data for 5, 6, and 7 were collected at 296 K on a Bru-
ker SMART 1000 system. Mo K
a (0.71073 Å) radiation was used,
and the data were corrected for absorption. A solution was pro-
vided by direct method with SHELXS-97, refined by full-matrix
least-squares on F2 using SHELXL-97 and analyzed with PLATON [50].
All non-H atoms were refined with anisotropic thermal parame-
ters. Aryl and alkyl H atoms were included at estimated positions
using a riding model. Crystal and refinement data are summarized
in Table 3. In these three crystal structures, the crystal sample of 6
is very small (0.18 ꢁ 0.06 ꢁ 0.06 mm3), its diffraction intensity are
very week. Some of atoms have errors on anisotropic parameters
and less weight, its Flack parameter is ꢀ0.03(3).
161.39. Selected IR data (KBr, cmꢀ1):
1674 (C@O), 1585 (C–N), 1566, 1319, 1296, 1223, 1078, 764.
m = 3291(N–H), 1700,

2426
L. Yang et al. / Journal of Organometallic Chemistry 694 (2009) 2421–2426
Table 3
Crystallographic data.
5
6
7
Empirical Formula
M
C20H16N4O2 ꢂ 1/2 (C6H4(CH3)2)
MnCl(HCONMe2)(C20H14N4O2)
505.84
Fe(Cl)(C20H14N4O2)
433.65
397.45
Crystal system
Space group
a (Å)
b (Å)
c (Å)
Monoclinic
P2(1)/n
8.9987(2)
16.1908(4)
12.8798(3)
90
Monoclinic
P2(1)
8.6974(7)
8.3283(6)
15.1408(11)
90
Monoclinic
P2(1)/n
11.8532(2)
8.20280(1)
19.3507(3)
90
R (°)
90.359(2)
90
1876.50(8)
4
91.194(4)
90
1096.48(14)
2
106.8890(1)
90
1800.31(5)
4
V (Å3)
Z
T (K)
296(2)
1.407
296(2)
1.532
296(2)
1.600
Dcalcd, (g cmꢀ3
)
Number of data
13641
9779
24687
Number of unique data
Number of parameters
4272
272
0.092
0.0696
0.0717, 0.1912
0.1613, 0.2415
4253
298
0.761
0.1225
0.0489, 0.0694
0.1772, 0.0951
4142
253
1.011
0.0406
0.0397, 0.1192
0.0515, 0.1263
l
(Mo K
R(int)
Final R indices [I > 2
a
) (mmꢀ1
)
r(I)] R1, wR2
R indices (all data) R1, wR2
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Acknowledgements
This project was supported by grants from the Natural Science
Foundation of China (Nos. 20672075 and 20771076) and the Sich-
uan Provincial Foundation for Young Scientists (08ZQ026-041).
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CCDC 208392, 208393, 208394 contain the supplementary crys-
tallographic data for 5, 6, and 7. These data can be obtained free of
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www.ccdc.cam.ac.uk/data_request/cif. Supplementary data associ-
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