Synthesis, oxygenation and catalytic oxidation performance of crown ether-containing schiff base-transition metal complexes

Article abstract of DOI:10.1002/adsc.200404094

Mono-Schiff bases containing a crown ether ring (HL¹, HL ², HL³ and HL⁴) and their transition metal complexes were synthesized and characterized by ¹H NMR, IR, and mass spectroscopy as well as element

Full text of DOI:10.1002/adsc.200404094

FULL PAPERS
Synthesis, Oxygenation and Catalytic Oxidation Performance of
Crown Ether-Containing Schiff Base-Transition Metal Complexes
Wei Zeng,a Jianzhang Li,a Zhihua Mao,b Zhou Hong,b Shengying Qina,*
a
Department of Chemistry, Sichuan University, 610064 Chengdu, P. R. China
E-mail: zengwei109@hotmail.com
Analytic Testing Center, Sichuan University, 610064 Chengdu, P. R. China
b
Received: March 23, 2004; Accepted: July 2, 2004
Abstract: Mono-Schiff bases containing a crown ether carried out with 100% selectivity. Comparison of
ring (HL1, HL2, HL3 and HL4) and their transition this complex with analogues not containing a crown
metal complexes were synthesized and characterized ether moiety clearly demonstrated the influence of
1
by H NMR, IR, and mass spectroscopy as well as el- crown ether ring on the dioxygen affinities and biomi-
emental analysis. The oxygenation constants (KO ) of metic catalytic oxidation performance of the Schiff
2
Schiff base-Co(II) complexes were measured over base complexes.
the range of ꢀ5 to þ258C, and the values of DH8
and DS8 were calculated based on these KO values. Keywords: aza-15-crown-5; benzo-15-crown-5; cata-
Using Mn(III)-Schiff base complexes, the bio2mimetic lytic oxidation; dioxygen affinity; transition metal-
catalytic oxidation of styrene to benzaldehyde was Schiff base complexes
Introduction
groups and orderly arrangement of the inner oxygen
atoms.[7] Of course, crown ether-containing Schiff bases
Studies on dioxygen binding to transition metal com- are known to bind cations in the crown ether cavity in
plexes are of intrinsic importance, and provide opportu- addition to the coordination of a transition metal center
nities to address the fundamental issues of biological through the N2O2 donor atoms. Co-complexation of a
oxygen carriers and oxygenases. In recent years, dioxy- hard cation close to the transition metal center is be-
gen binding complexes containing Fe(II), Cu(I), Ni(II) lieved to play an important role in perturbing its oxygen
and Mn(II) have been reported,[1] but chelates of cobalt- binding properties. Herein, as part of a research pro-
(II) offer the greatest promise because of the wide range gram aimed at studying the effects of crown ether rings
of stabilities of cobalt-dioxygen complexes.[2] In 1938 and their alkali metal complexes on the dioxygen affin-
Tsumaki reported that Schiff base-Co(II) complexes ities and biomimetic catalytic oxidation performance of
possess the ability to activate various molecules, espe- such transition metal complexes, we have developed a
cially molecular oxygen coordinated to the axial posi- series of novel Schiff base complexes bearing crown
n
tions of the complexes.[3] Tsuchida demonstrated that ether rings [ML2 , M¼Co(II) or Mn(III)Cl, n¼1–5;
Co-Salophen, with an elegant steric component, could see Figure 1].
form a stable 1:1 oxygen adduct because it avoids being
The route for the synthesis of key intermediate of HL2
oxidized to the m-oxodimer via dimerization after ab- is shown in Scheme 1.
sorbing the oxygen molecule.[4] Moreover, the selective
oxidation of various organic compounds utilizing mo-
lecular oxygen (the most basic and abundant naturally Reslts and Discussion
occurring oxidant) is one of the most challenging topics
in the fields of chemical and biological catalysis.[5] In the The Schiff-base ligands HLn (n¼1–5) were convenient-
past decades, Schiff base complexes designed as cyto- ly prepared by the reaction of aromatic amines with sal-
chrome P-450 models have been employed in the cata- icylaldehyde or crown ether-functionalized salicylalde-
lytic oxidation of olefins with PhIO, NaClO or H2O2 as hyde. Unfortunately, due to their sterically hindered na-
terminal oxidants.[6] However, to date no studies on ture, the yields of the complexes were low (<63%). In
crown ether ring-containing Schiff base complexes as the IR spectra of HLn, the characteristic frequency of
ꢀ1
ꢀ
catalysts for such reactions have been reported. Crown Ar OH at 3320–3220 cm was observed, as was that
ether rings endow special performance and characteris- for CH N at 1620–1618 cmꢀ1. In the case of ML2, the
¼
tics due to the hydrophobicity of the outer ethylene nCH N of CoL2 shifts ca. 10 cmꢀ1 to shorter wavelength,
¼
Adv. Synth. Catal. 2004, 346, 1385–1391
DOI:10.1002/adsc.200404094
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1385

Wei Zeng et al.
FULL PAPERS
Figure 1.
Scheme 1.
Figure 3. The crystal structure of HL4.
and the nCH of MnL2 Cl shifts ca. 10 cmꢀ1 to longer
n
¼
N
wavelength. Moreoꢀve1 r the characteristic vibration of
ꢀ
Ar OH at 3300 cm disappeared, but that for the vi-
bration of nC-O-C did not change. These facts indicate
that the Co2þ and Mn3þ ions only interact with the
ꢀ
¼
Ar OH and CH N groups.
The crystal structures of HL1, HL4,[8] and CoL2 are
shown in Figures 2, 3 and 4, respectively. The conforma-
tions of the ligands HL1 and HL4 suggest that the aza
crown ring does come closer to the coordination group
compared to the benzo-crown ring. Moreover, the nitro-
1
¼
gen atom of the CH N moiety interacts with hydrogen
ꢀ
atom of the Ar OH group through an H-bond,
CH N· · ·H-O-Ar. The crystal structure of CoL21 indi-
¼
cates the formation of a 1:2 (Co/HL) Co(II)-Schiff
base complex, and the geometry of Co is a pseudo-tetra-
hedral conformation. The molecular structure of CoL2
1
Figure 4. The crystal structure of CoL2 .
1
can be compared to that of a flying bird where the two
aza-crown ether rings resemble the wings that extend (KO ) of Mn(III)-Schiff base complexes cannot be deter-
2
from the coordination center. This indicates that the mined accurately.[9] Therefore we only studied the di-
aza-crown ether rings do control the coordination envi- oxygen affinities of transition metal complexes by di-
ronment.
oxygen binding to cobalt(II) complexes. The oxygena-
Since at ambient temperature, pyridine (Py) solutions tion equilibrium constants (KO ) and thermodynamic
of manganese complexes are oxidized in air to yield parameters (DH8 and DS8) of2 the above cobalt(II)-
(Py)L2Mn(III)-O-Mn(III)L2(Py), the oxygenation constant Schiff base complexes are listed in Table 1. As seen in
Table 1, the dioxygen affinities of the cobalt(II) com-
plexes were influenced greatly by both temperature
and the structure of the Schiff base. Higher temperature
results in a smaller oxygenation constant. This may be
due to higher temperatures resulting in poor solubility
1
of O2. The oxygenation constants (KO ) of CoL2 ,
2
2
3
4
CoL2 , CoL2 and CoL2 with crown ether rings are larger
than that of the uncrowned analogue (CoL2 ), especially
in the case of CoL2 that contains four crown ether rings,
5
4
which shows the highest dioxygen affinity. This observa-
tion could be due to a macrocycle effect of the crown
Figure 2. The crystal structure of HL1.
1386
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
Adv. Synth. Catal. 2004, 346, 1385–1391

Crown Ether-Containing Schiff Base-Transition Metal Complexes
FULL PAPERS
Table 1. Oxygenation constants (KO ) and thermodynamic parameters (DH8 and DS8) of Co(II)-Schiff base complexes.
2
Complexes
B
T [8C]
Ln KO [mmꢀ1
]
DH8 [KJ·molꢀ1
]
DS8 [J·Kꢀ1 ·molꢀ1
]
2
1
CoL2
Py
ꢀ5
0
15
25
ꢀ5
0
15
25
ꢀ5
0
15
25
ꢀ5
0
15
25
ꢀ5
0
15
25
ꢀ4.22 (ꢀ4.01*)
ꢀ4.56 (ꢀ4.36*)
ꢀ5.49 (ꢀ5.28*)
ꢀ6.06 (ꢀ5.86*)
ꢀ4.03 (ꢀ3.83*)
ꢀ4.43 (ꢀ4.22*)
ꢀ5.57 (ꢀ5.35*)
ꢀ6.27 (ꢀ6.06*)
ꢀ4.27 (ꢀ4.09*)
ꢀ4.59 (ꢀ4.42*)
ꢀ5.48 (ꢀ5.29*)
ꢀ6.02 (ꢀ5.85*)
ꢀ4.02 (ꢀ3.77*)
ꢀ4.38 (ꢀ4.14*)
ꢀ5.41 (ꢀ5.19*)
ꢀ6.03 (ꢀ5.81*)
ꢀ5.62 (ꢀ5.60*)
ꢀ5.78 (ꢀ5.79*)
ꢀ6.22 (ꢀ6.23*)
ꢀ6.48 (ꢀ6.47*)
ꢀ40.85
ꢀ228.19
2
CoL2
Py
Py
Py
Py
ꢀ49.52
ꢀ38.75
ꢀ44.50
ꢀ258.96
ꢀ220.77
ꢀ240.15
3
CoL2
4
CoL2
5
CoL2
ꢀ19.25
ꢀ159.21
* The values of KO2 for the mixture of CoL2 and NaNO3 (1: 2, mol/mol, CoL2: NaNO3) were determined.
ether ring that probably facilitates the oxygen molecule Table 2. Schiff base complexes biomimetically catalyze the
oxidation of styrene to benzaldehyde.
to approach the coordination center of the cobalt(II)
complexes and stabilize the Co O2 bond through the hy-
ꢀ
Catalyst
Conversion
[wt. %)
TOF
Selectivity (wt. %)
(hꢀ1
)
drophobicity of the outer ethylene groupand the orderly
arrangement of the inner oxygen atoms. It was also ob-
A
B
2
served that the oxygenation constant for CoL2 is larger
1
1
CoL2
7.5
32
8.2
38.5
5
21.4
7.8
36
1.2
8
5.6
24
100
100
100
100
100
100
100
100
5.8
0
0
0
0
0
0
0
0
than that of CoL2 , which indicates that the flexibility of
1
MnL2 Cl
the polyether-bridged chain bonded to aza-crown ether
ring may make the aza-crown ring control the coordina-
tion environment and this results in a stronger dioxygen
2
CoL2
6.2
28.9
3.7
16.0
5.9
27
2
MnL2 Cl
3
CoL2
2
3
affinity for CoL2 . It is interesting that the addition of the
MnL2 Cl
4
alkali metal salt NaNO3 enhances the dioxygen affinities
of crowned Schiff base-Co(II) complexes, but has little
CoL2
4
MnL2 Cl
5
5
CoL2
1.0
6
94.2
93.7
effect on that of uncrowned analogue CoL2 (see Ta-
5
ble 1), this may be due to the alkali metal cation (Naþ),
which matches well with crown ether ring and locates
near to the coordination center, resulting in higher di-
oxygen affinity.
MnL2 Cl
6.3
Legend: A¼benzaldehyde, B¼epoxy product, TOF¼turn-
over frequency (mole styrene converted per mole catalyst
per hour).
In order to investigate the effect of the crown ether
ring on the performance of complexes as mimics of mon-
n
ooxygenases in catalytic oxidation reactions, the above
As illustrated in Table 2, MnL2 Cl (n¼1–5) possess
n
n
ML2 [M¼Co(II) or Mn(III)Cl, n¼1–5] were em- higher catalyticoxidation activities thanCoL2 (n¼1–5)
ployed to catalyze the model oxidation of styrene under under the same reaction conditions. This may be due to
the conditions of normal pressure and 258C (see the inner electronic structures of the cobalt and manga-
Scheme 2).
nese atoms. The data indicate that crown ether rings
bonded to transition metal complexes affected the re-
sults of the oxidation of styrene. The major product of
5
oxidation of styrene catalyzed by ML2 [M¼Co(II) or
Mn(III)Cl] is the epoxide, and the selectivity for benzal-
5
dehyde is only ca. 5.8–6.3%. But for catalysts ML2
[M¼Co(II) or Mn(III)Cl, n¼1–4], the only oxidation
¼
Scheme 2.
product observed comes from oxidative C C cleavage
Adv. Synth. Catal. 2004, 346, 1385–1391
asc.wiley-vch.de
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1387

Wei Zeng et al.
FULL PAPERS
grade and were used without further purification. Syntheses
of the new ligands are given below.
of the olefinic moiety with the formation of benzalde-
hyde with up to 100% selectivity. The data in the Table 2
also indicate that crowned Schiff base complexes pos-
sess higher biomimetic catalytic activities compared to
uncrowned Schiff base complexes ML25 [M¼Co(II) or
2
4
Mn(III)Cl]. Complexes MnL2 Cl and MnL2 Cl exhibit
better performance in terms of conversion and TOF as
compared to other Schiff base complexes reported by
literature.[11] These results could be due to the macrocy-
cle effect of crown ether rings whose special conforma-
5-(4-Nitrophenyoxyl)-3-oxapentane-1-toslyate (2)
1-Hydroxy-5-(4-nitrophenyoxyl)-3-oxapentane (1; 22.70 g,
0.1 mol) was dissolved in pyridine (80 mL) and p-toluenesul-
fonyl chloride (19.30 g, 0.1 mol) added portionwise over 2 h
as a power to the stirred, ice-cooled solution. Stirring and cool-
ing were continued for another 4 h and then the mixture was
left overnight. It was then poured onto ice (110 g) and further
diluted with water (50 mL). The precipitated tosylate was fil-
tered off and washed with water (160 mL). Recrystallization
from ethanol (200 mL) gave the pure tosylate 2; yield: 26.70 g
n
tion in MnL2 Cl (n¼1–4) can offer large steric hin-
drance and a hydrophobic environment, and possibly fa-
¼
vor the formation of and stabilize the active Mn O spe-
cies. The possible mechanism of styrene oxidation in-
n
volves free radical processes since peroxide L2 M-
1
(70%); mp 67–708C; H NMR: d¼6.87–6.70 (8H, m, ArH),
OOH [M¼Co(II) or Mn (III)Cl, n¼1–5] could be
formed from an MO2 (M¼Co or Mn) complex in the
presence of acid,[12] and the above peroxide can oxidize
4.20–3.95 (8H, m, OCH2CH2O), 2.80 (3H, s, CH3); IR (KBr):
nmax ¼1570, 1358, 1182, 1124 cmꢀ1; MS: m/z¼380 (Mþ – 1);
anal. calcd. for C17H19NO7S: C 53.54, H 4.99, N 3.67; found: C
53.87, H 5.27, N, 3.44.
styrene to benzaldehyde through a free hydroxyl radical
.
intermediate, C(OOH)-C which is derived from inter-
action between a hydroperoxyl radical and the carbon-
carbon double bond.[13]
N-[-5-(4-Nitrophenyoxyl)-3-oxaamyl]-aza-15-crown-5
(3)
Conclusion
In a dry acetonitrile solution (100 mL) of monoaza-15-crown-5
(1.32 g, 6 mmol) was suspended Na2CO3 (12.50 mmol), and the
mixture was then refluxed while stirring under a nitrogen at-
mosphere. To the refluxing suspension was added dropwise a
dry acetonitrile solution (30 mL) of 2 (2.30 g, 6 mmol). After
the addition was complete, the mixture was refluxed and moni-
tored by TLC for 7 d. The mixture was then concentrated and
water (10 mL) was added. The solution was extracted with
chloroform (50 mLꢁ3) and the combined extract was dried
In conclusion, this study indicates that crown ether rings
exhibit great effects on the dioxygen affinities and bio-
mimetic catalytic performance of transition metal-
Schiff base complexes, and that the oxidation of styrene
to benzaldehyde (selectivity¼100%) with molecular
oxygen at 258C under a normal atmospheric pressure
of O2 occurs efficiently in the presence of crowned Schiff
base-transition metal complexes. Further studies into over Na2SO4. The solvent was then removed by rotary evapo-
ration. Chromatography of the crude product (silica gel, CH3
OH) afforded the oily product 3; yield: 0.40 g (15%); 1H
NMR: d¼6.81–6.73 (4H, m, ArH), 4.14–3.64 (22H, m, 11ꢁ
OCH2), 3.60–3.50 (6H, m, 3ꢁNCH2); IR (KBr): nmax ¼1601,
1564, 1368, 1225, 1124 cmꢀ1; MS: m/z¼428 (Mþ); anal. calcd.
for C20H32N2O8: C 56.07, H 7.48, N 6.54; found: C 56.35, H
7.59, N, 6.75.
the scope of this catalytic oxidation reaction are being
carried out in our laboratory.
Experimental Section
Apparatus and Reagents
Melting points were determined on a Yanaco MP-500 micro-
melting point apparatus and are uncorrected. IR spectra
were obtained on a Nicolet-1705X IR spectrometer. 1H
NMR spectra were recorded on a Bruker AC-200 MHz in
CDCl3 with tetramethylsilane, as the internal standard. Mass
spectra were obtained on a Finnigan LCQDECA spectrometer.
Elemental analyses were performed on a Carlo-Erbo 1160 ele-
mental analyzer. Absorption spectra were recorded on a UV-
Vis Tu-1901 spectrophotometer. Silica gel (60H for TLC, Qing-
dao, China) was used for flash column chromatography. N,N-
Dimenthyl-[4-(2-hydroxbenzylideneimino)]aniline (HL5),[14]
N-(4-aminophenyl)-aza-15-crown-5 (5),[15] 4’-aminobenzo-15-
crown-5 (6)[16] and 4’-formyl-5’-hydroxbenzo-15-crown-5 (7)
(crowned salicyclaldehyde)[17] were synthesized according to
published procedures. All other reagents were of analytical
N-[5-(4-Aminophenyoxyl)-3-oxaamyl]-aza-15-crown-5
(4)
Toa suspension of 0.10 gPd/C (10%) in 50 mL ethanolwas add-
ed 3 (0.73 g, 1.7 mmol), and the mixture was hydrogenated un-
der H2 at 50–558C for 20 h. The reaction mixture was then
cooled and filtered. The filtrate was evaporated to dryness
and the crude product was chromatographed (silica gel, CH3
OH) to afford the slightly reddish oily product 4; yield: 0.60 g
1
(85%); H NMR: d¼6.73–6.64 (4H, m, ArH), 5.31 (2H, s,
NH2), 4.14–3.60 (22H, m, 11ꢁOCH2), 3.60–3.50 (6H, m, 3ꢁ
NCH2); IR (neat): nmax ¼3279, 1601, 1564, 1225, 1124 cmꢀ1
;
MS: m/z¼398 (Mþ); anal. calcd. for C20H34N2O6: C 60.30, H
8.54, N 7.04; found: C 60.11, H 8.47, N 7.18.
1388
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
Adv. Synth. Catal. 2004, 346, 1385–1391

Crown Ether-Containing Schiff Base-Transition Metal Complexes
FULL PAPERS
N-[4-(2-Hydroxybenzylimine)]phenylaza-15-crown-5
General Methods for Synthesis of Cobalt(II)-Schiff
Base Complexes (CoL2)
(HL1)
Compound 5 (0.31 g, 1.0 mmol) was dissolved in 6 mL of
MeOH and the solution was mixed with a solution of
1.0 mmol of salicyclaldehyde (0.12 g, 1.0 mmol) in MeOH
(6 mL) and stirred under N2 for 2 h. The yellow precipitate
was collected and washed sequentially with water and ethanol.
After recrystallization from ethanol, the yellow product HL1
A solution of HLn (2.0 mmol) and Co(OAc)2 ·4 H2O or MnCl2 ·
4 H2O (1.1 mmol) in EtOH (15 mL) was stirred in EtOH for 2 h
under N2 at 708C. The mixture was then cooled, filtered, and
washed with methanol to afford the transition metal com-
plexes. Pure product was obtained after recrystallization
from ethanol.
1
1
was obtained; yield: 0.35 g (85%); mp 97–1008C; H NMR
CoL2 : dark brown; yield: 53%; mp 203–2068C; IR (KBr,
(CDCl3): d¼13.80 (s, 1H, OH), 8.60 (s, 1H, CH N), 7.36–
film): nmax ¼1610, 1123 cmꢀ1; anal. calcd. for CoC46H58N4O10:
¼
7.24 (m, 4H, Ar-H), 7.00–6.68 (m, 4H, Ar-H), 3.80–3.60 (m,
20H, OCH2 and NCH2); IR (KBr, film): nmax ¼3220, 1619,
1120 cmꢀ1; MS: m/z¼414 (Mþ); anal. calcd. for C23H30N2O5:
C 66.67, H 7.25, N 6.76; found: C 66.95, H 7.48, N 6.49.
C 62.37, H 6.55, N 6.32; found: C 62.55, H 6.49, N 6.18.
1
MnL2 Cl: purple; yield: 58%; mp 191–1948C; IR (KBr,
film): nmax ¼1637, 1126, 1121 cmꢀ1; anal. calcd. for MnC42H50
N4O8Cl: C 60.80, H 6.03, N 6.76; found: C 60.61, H 5.88, N 6.93.
2
CoL2 : dark brown; yield: 58%; mp 186–1888C; IR (KBr,
film): nmax ¼1611, 1123 cmꢀ1; anal. calcd. for CoC54H74N4O14:
C 64.48, H 7.36, N 5.57; found C 64.69, H 7.69, N 5.38.
N-{3-Oxa-5-[4-(2-hydroxybenzylidenimine)phenoxy]-
2
MnL2 Cl: purple; yield: 63%; mp 195–1988C; IR (KBr,
amyl}-aza-15-crown-5 (HL2)
film): nmax ¼1630, 1227, 1124 cmꢀ1
;
anal. calcd. for
MnC54H74N4O14Cl: C 62.48, H 7.14, N 5.40; found C 62.74,
H 7.03, N 5.19.
Compound 4 (0.40 g, 1.0 mmol) was dissolved in 6 mL of
MeOH, the solution was mixed with a solution of 1.0 mmol
of salicyclaldehyde (0.122 g, 1.0 mmol) in MeOH (6 mL) and
stirred under N2 for 2 h. The reaction mixture was concentrated
to dryness, and chromatographed (silica gel, MeOH) to afford
3
CoL2 : dark brown; yield: 45%; mp 171–1748C; IR (KBr,
film): nmax ¼1616, 1224, 1134 cmꢀ1
;
anal. calcd. for
CoC42H48N2O12: C 60.65, H 5.78, N 3.37; found C 60.89,
H 5.96, N 3.18.
1
the oily product HL2; yield: 0.45 g (89%); H NMR (CDCl3):
3
MnL2 Cl: purple. 59%yield. mp 191–1948C. IR (KBr, film)
¼
d¼13.52 (1H, s, OH), 8.59 (1H, s, CH N), 7.40–7.10 (4H, m,
nmax: 1636, 1227, 1134 cmꢀ1. Anal. calcd for Mn C42H48N2O12Cl:
Ar-H), 7.00–6.85 (4H, m, ArH), 4.14–3.65 (22H, m, 11ꢁ
OCH2), 3.60–3.50 (6H, m, 3ꢁNCH2); IR (neat): nmax ¼3327,
1620, 1225, 1140 cmꢀ1; MS: m/z¼502 (Mþ); anal. calcd. for
C27H38N2O7: C 64.54, H 7.57, N 5.58; found: C 64.21, H 7.81,
N 5.34.
C 58.40, H 5.56, N 3.24; found C 58.74, H 5.79, N, 3.48.
4
CoL2 : dark brown; yield: 47%; mp 189–1938C; IR (KBr,
film): nmax ¼1611, 1225, 1128, 1052 cmꢀ1; anal. calcd. for
CoC62H86N4O20: C 58.81, H 6.79, N 4.43; found: C 58.57, H
6.53, N 4.69.
4
MnL2 Cl: purple; yield: 43%; mp 248–2518C; IR (KBr,
film): nmax ¼1624, 1223, 1126, 1053 cmꢀ1; anal. calcd. for
MnC62H86N4O20Cl: C 57.39, H 6.63, N 4.32; found: C 57.63, H
6.95, N 4.17.
4-Hydroxy-5-benzyliminemethyl-benzo-15-crown-5
(HL3)
5
CoL2 : dark brown; yield: 62%; mp 251–2548C; IR (KBr,
HL3 was obtained in a similar way to HL1 by the reaction of 4’-
aminobenzo-15-crown-5 (6) and salicyclaldehyde; yield: 75%;
film): nmax ¼1610 cmꢀ1; anal. calcd. for CoC30H30N4O2: C
67.04, H 5.59, N 10.43; found: C 66.75, H 5.87, N 10.19.
1
mp 101–1038C; H NMR (CDCl3): d¼13.59 (1H, s, OH),
5
MnL2 Cl: purple; yield: 57%; mp 267–2718C; IR (KBr,
¼
8.44 (1H, s, CH N), 7.42–7.19 (5H, m, Ar-H), 6.86 (1H, s,
film): nmax ¼1619 cmꢀ1; anal. calcd. for MnC30H30N4O2Cl: C
ArH), 6.47 (1H, s, ArH), 4.17–4.07 (8H, m, 2ꢁArOCH2CH2O),
63.32, H 5.28, N 9.85; found: C 63.06, H 5.45, N 9.62.
3.93–3.75 (8H, m, 2ꢁOCH2CH2O); IR (KBr, film): nmax
¼
3227, 1628, 1225, 1140 cmꢀ1; MS: m/z¼387 (Mþ); anal. calcd.
for C21H25N2O6: C 65.12, H 6.46, N 3.62; found: C 65.34,
H 6.59, N 3.85.
X-Ray Crystallography Data
Crystallographic data and experimental details are listed in Ta-
ble 3.
4-Hydroxy-5-[4-(N-aza-15-crown-5)-
benzyliminemethyl]-benzo-15-crown-5 (HL4)
Crystallographic data were collected using a CAD4 four-cir-
cle automated diffractometer, utilizing graphite monochro-
mated Moka radiation with DIFRAC. The structure was
solved using the direct method and refined on F2 using a full
matrix least-squares procedure. All non-hydrogen atoms
were refined anisotropically. Positions of all hydrogen atoms
for HL1 were calculated based on geometrical factors. These
hydrogens were allowed to ride on their neighboring heavy
atoms during refinement, and the rest hydrogen atoms of
HL1 were refined isotropically. The structure was solved, re-
fined and displayed using NRCVAX and SHELX-97 grogram
package.
HL4 was obtained in a similar way to HL1 by the reaction of 4’-
formyl-5’-hydroxybenzo-15-crown-5 (7) and N-(4-aminophen-
yl)-aza-15-crown-5 (6); yield: 83%; mp 114–1168C (lit.[8] mp
1
114–1178C); H NMR (CDCl3): d¼14.02 (1H, s, OH), 8.41
¼
(1H, s, CH N), 7.21–7.16 (2H, d, J¼8 Hz, Ar-H), 6.84 (1H, s,
ArH), 6.68–6.63 (2H, d, J¼10 Hz, ArH), 6.46 (1H, s, ArH),
4.16–4.07 (8H, m, 2ꢁArOCH2CH2O), 3.92–3.57 (28H, m,
5ꢁOCH2CH2O and 2ꢁNCH2CH2O); IR (KBr, film): nmax
¼
3224, 1618, 1220, 1124, 1050 cmꢀ1; MS: m/z¼603.3 (Mþ);
anal. calcd. for C31H44N2O10: C 61.59, H 7.28, N 4.64; found: C
61.79, H 7.12, N 4.53.
Adv. Synth. Catal. 2004, 346, 1385–1391
asc.wiley-vch.de
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1389

Wei Zeng et al.
FULL PAPERS
1
Table 3. Crystallographic data and experimental details for HL1 and CoL2 .
HL1 (C23H30N2O5)
CoL2 (CoC46H58N4O10)
1
Formula
Formula weight
Crystal system
Space group
a (ꢁ)
b (ꢁ)
c (ꢁ)
414.49
Orthorhombic
P21nb
885.89
Monoclinic
1a
8.514(3)
9.046(3)
27.921(7)
90.00(3)
90.00(3)
90.00(3)
2150.6(12)
4
14.539(4)
19.129(9)
16.539(5)
90.00(3)
92.58(3)
90.00(3)
4595(3)
4
a (8)
b (8)
g (8)
V (ꢁ3)
Z
F (000)
888
1.280
1876
1.281
Dx (g cmꢀ3
)
Crystal size (mm)
0.32ꢁ0.35ꢁ0.40
0.20ꢁ0.25ꢁ0.28
m (mmꢀ1
)
0.090
0.433
Temperature (K)
2qmax(8)
293(2)
48.1
293(2)
50.06
Total data
2000
4192
Independent data
Total parameters
Goodness of fit on F2
R [I>20ꢀ(I)]
R (all data)
1825(Rm ¼0.0000)
4018(Rm ¼0.0000)
365
4018
1.035
0.0448
0.1341
0.223, ꢀ0.193
0.980
0.0609
0.1738
0.298, ꢀ0.224
Largest diff peak and hole (eꢁ3)
(1.0ꢁ10ꢀ5 mol). The mixture was vigorous stirred at 258C un-
der O2 for 30 min, and the proton donor CH3COOH
(0.086 mL) was injected. The mixture was stirred for 4 h at
the same temperature and then analyzed by GC (PE-GC-
9000).
Oxygen uptake Measurements
The values of KO2 were determined by the quantities (volumes)
of dioxygen absorbed at equilibrium, as described in the liter-
ature.[18] Diethylene glycol dimethyl ether (saturated by O2)
was employed as solvent and pyridine (saturated by O2) was
employed as the axial base (B), which is necessary for the Schiff
base complexes investigated to combine with dioxygen.[18,19]
The concentration of Schiff base complexes was 3.5ꢁ
10ꢀ3 mol·dmꢀ3, and partial pressure of dioxygen was 97 Kpa.
DS8 and DH8 were calculated from the equations DG8¼
Acknowledgements
Financial support from the National Natural Science Founda-
tion of China (Grant No. 29572059) is gratefully acknowledged.
–RT ln KO and TDS8¼DH8ꢀDG8. The equilibrium con-
2
stants (KO ) were calculated (see Figure 5). B, pO represent ax-
2
ial base and partial pressure of oxygen, respecti2vely. Thermo-
dynamic parameters DH8, DS8 were determined from variation
of KO and K’O over a range of temperature.
References
2
2
[1] a) M. G. Simmons, C. L. Merrill, L. J. Wilson, J. Chem.
Soc. Dalton Trans. 1980, 1827; b) L. H. Vogt, H. M. Fai-
genbaum, S. Wiberly, Chem. Rev. 1963, 63, 269; c) B. M.
Hoffman, C. L. Weschler, F. Basolo, J. Am. Chem. Soc.
1976, 98, 5473; d) T. G. Traylor, P. S. Traylor, Annu.
Rev. Biophys. Bioeng. 1982, 11, 105.
[2] a) R. D. Jones, D. A. Summerville, F. Basolo, Chem. Rev.
1979, 79, 139; b) E. L. Niederhoffer, J. H. Timmons, A. E.
Martell, Chem. Rev. 1984, 84, 137.
[3] T. Tsumaki, Bull. Chem. Jpn. 1938, 13, 252.
[4] E. Tsuchida, J. Macromol. Sci., Chem. 1979, A13, 545.
[5] Y. Sun, Z. W. Xi, G. Y. Cao, J. Mol. Catal A: Chem. 2001,
166, 219.
[6] a) W. Zhang, E. N. Jacobson, J. Org. Chem. 1991, 56, 229
6; b) P. Pietikainen, Tetrahedron Lett. 1994, 35, 941; c) R.
Irie, N. Hosoya, T. Katsuki, Synlett 1991, 55.
Figure 5.
Biomimetic Catalytic Oxidation of Styrene
The biomimetic system of manganese-Schiff base complexes-
catalyzed oxidation of styrene is similar to that of manganese
porphyrins-catalyzed oxidation of alkene.[20] To a solution of
the imidazole co-catalyst (0.1 mmol), styrene (0.5 mmol), the
reducing agent Zn (0.5 mmol), CH3CN:CH2Cl2 (10 mL,
9.5:0.5, v/v) was added Co(II) or Mn (III) complex catalyst
1390
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
Adv. Synth. Catal. 2004, 346, 1385–1391

Crown Ether-Containing Schiff Base-Transition Metal Complexes
FULL PAPERS
[7] a) H. Hochisako, H. Ihara, J. Kamiya, C. Hirayama, K.
Yamnda, Chem. Commun. 1997, 19; b) A. Galon, D. An-
dreu, A. M. Echavarren, P. Prades, J. de. Mendoza, J.
Am. Chem. Soc. 1992, 114, 1511.
[8] W. Zeng, Z. H. Mao, J. Z. Li, S. Y. Qin, Synthesis 2004, 7,
1011.
[9] L. H. Vogt, A. Zalkin, D. H. Templeton, Inorg. Chem.
1967, 6, 1725.
[10] K. Srinivasan, P. Michaud, J. K. Kochi, J. Am. Chem. Soc.
1986, 108, 2309.
[13] D. E. Hamilton, R. S. Drago, A. Zombeck, J. Am. Chem.
Soc. 1987, 109, 374.
[14] B. Erk, Y. Baran, Synth. React. Inorg. Met-Org. Chem.
1991, 21, 1321.
[15] P. Dix, F. Vꢂgtle, Angew. Chem. Int. Ed. Eng. 1978, 90,
893.
[16] R. Ungaro, B. Elhaj, J. Smid, J. Am. Chem. Soc. 1976, 95,
5198.
[17] S. Can, O. Bekaroglu, J. Chem. Soc. Dalton Trans. 1988,
2831.
[18] D. Chen, A. E. Martell, Inorg. Chem. 1987, 26, 1026.
[19] D. Chen, A. E. Martell, Y. Sun, Inorg. Chem. 1989, 28,
2647.
[11] R. M. Wang, C. L. Hao, Y. F. He, C. G. Xia, J. R. Wang,
Y. P. Wang, J. Appl. Polym. Sci. 2000, 75, 1138.
[12] J. J. Pignatello, F. R. Jensen, J. Am. Chem. Soc. 1979, 101,
5929.
[20] P. Battioni, J. F. Bartoli, D. Ledue, M. Fonte cave, D.
Mansuy, J. Chem. Soc. Chem. Commun. 1987, 791.
Adv. Synth. Catal. 2004, 346, 1385–1391
asc.wiley-vch.de
ꢀ 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
1391