Synthesis, crystal structure, and kinetics of the thermal decomposition of the nickel(II) complex of the Schiff base 2-[(4-methylphenylimino)methyl]-6- methoxyphenol

Article abstract of DOI:10.3390/molecules14072582

A new dinuclear complex, [Ni₂(H₂O)L ₄]·5H₂O, consisting of chelating bidentate and bridging tridentate coordinated 2-[(4-methylphenylimino)methyl]-6-methoxyphenol (HL) Schiff base ligands and water molecules has

Full text of DOI:10.3390/molecules14072582

Molecules 2009, 14, 2582-2593; doi:10.3390/molecules14072582
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molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Synthesis, Crystal Structure, and Kinetics of the Thermal
Decomposition of the Nickel(II) Complex of the Schiff Base
2-[(4-Methylphenylimino)methyl]-6-methoxyphenol
Yan-Fang Wang 1,2, Jian-Feng Liu 1, Hui-Duo Xian 1 and Guo-Liang Zhao 1,*
1
Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces, Institute of Physical
Chemistry, College of Chemistry and Life Science, Zhejiang Normal University, Jinhua, 321004,
China
2
Ningbo Tian Yi College of Occupation and Technology, Ningbo, Zhejiang 315100, China;
E-mails: yfw901@163.com (Y-F.W.); liujianfeng23@163.com (J-F.L.);
hdxian@163.com (H-D.X.)
* Author to whom correspondence should be addressed; E-mail: sky53@zjnu.cn;
Tel.: +86-579-82283925, Fax: +86-579-82282595
Received: 25 May 2009; in revised form: 29 June 2009 / Accepted: 13 July 2009 /
Published: 15 July 2009
Abstract: A new dinuclear complex, [Ni2(H2O)L4]·5H2O, consisting of chelating bidentate
and bridging tridentate coordinated 2-[(4-methylphenylimino)methyl]-6-methoxyphenol
(HL) Schiff base ligands and water molecules has been synthesized using a traditional
method. The structure of this complex was characterized by FTIR and UV/Vis
spectroscopy and thermogravimetric analyses (TG-DTG) and further confirmed by single-
crystal X-ray diffraction. Its crystal structure is of monoclinic system, space group P21/c
with a = 13.2837(5) Å, b = 27.3886(10) Å, c = 17.5415(6) Å, α = 90 º, β = 108.429(2) º, γ
= 90 º, V = 6054.7(4) Å3, Z = 4. The crystal structure reveals that there is a Ni·Ni core,
with a separation of 3.183 Å. Its thermal decomposition kinetics were also studied.
Keywords: dinickel complex; crystal structure; Schiff base

Molecules 2009, 14
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1. Introduction
Polynuclear transition metal complexes have been receiving considerable attention for many years,
due to their interesting characteristics in the fields of material science and biological systems [1,2]. o-
Vanillin is considered a safe food flavoring and can be used as a pharmaceutical intermediate [3,4],
and because of the wide applications o-vanillin derivatives and their complexes have drawn much
attention [5-8]. Schiff base ligands which usually contain O, N donor atoms have played an important
role in coordination chemistry since the late 19th century. Metal complexes with these ligands are
becoming increasingly important as biochemical, analytical and antimicrobial reagents, in the design
of molecular magnets, materials chemistry and so on [9~14]. The versatile properties of the ligand 2-
[(4-methyl-phenylimino)methyl]-6-methoxyphenol (HL) in the formation of diverse transition metal
complexes are well known. We have synthesized some complexes from HL, with discrete, dinuclear
and polynuclear structures [15~17]. In continuation of the research in our group, we now describe a
detailed investigation on the synthesis, single X-ray crystallographic and kinetics of the thermal
decomposition of [Ni2(H2O)L4]·5H2O (1).
2. Results and Discussion
2.1. IR spectra
Important information obtained from the IR spectra of HL and complex 1 is summarized in Table 1.
The broad absorption bands at about 3,444 cm-1, attributed to the v(O-H), indicate the presence of
water in this compound. In addition, the band appearing at 615 cm-1 and resulting from δ(O-H) bends
also supports this conclusion. Some sharp bands appearing at about 2,962 cm-1 and 1,380 cm-1 belong
to the v(C-H) and δ(C-H) of methyl group and methoxyl groups. The characteristic absorption bands
resulting from the skeletal vibrations of the aromatic rings from the Schiff base ligands are in the
1,400-1,600 cm-1 region (1,597 cm-1, 1,508 cm-1 and 1,470 cm-1). The typical v(C=N) band at
1,641 cm-1 in the spectrum of HL changes to 1,619 cm-1 after the imine N bonds to the metal ion. The
shift of the C–O stretching vibration of the phenolic part of o-vanillin from 1,257 cm-1 to 1,238 cm-1
also supports the coordination of phenolic oxygen atoms. At last, the new band appearing at 509 cm-1
is attributed to M–O stretching vibration, which is absent in ligand spectra [18].
Table 1. Values of IR spectra for complex 1 and HL (cm-1).
Compound
HL
v OH
v C=N
1614 (s)
1619 (s)
v C-O
1257 (s)
1238 (s)
v M-O
—
3468 (w)
3444 (m)
[Ni2(H2O)L4]·5H2O
509 (w)
* Note: s: strong, m: middle, w: weak.
2.2. UV/Vis spectra
The absorptions in the UV/Vis spectra of HL and complex 1 are similar (Figure 1). There are three
absorption peaks in the range of 200~500 nm at 317.8, 276.0 and 228.0 nm in the spectra of HL. The
counterparts of the complex appear at 301.4, 292.0 and 229.8 nm. The first peak is assigned to n-π*

Molecules 2009, 14
2584
transition of conjugation between lone-pair electron N atom in the C=N group and big π bond of
benzene ring. The hypsochromic shift of about 16 nm is caused by the coordination of N atom to Ni
ion, which can also provide the conclusion evidence for the coordination. The other two peaks are
attributed to π-π* transition of the conjugation system of Schiff base and they are similar in HL and in
the complex.
Figure 1. The UV/vis spectra of the complex 1 and the ligand HL.
2.3. Crystal structure
The complex is an asymmetric dinuclear nickel complex and there is no significant metal-metal
interaction between the two nickel centers considering of the separation of Ni(1)···Ni(2) is 3.1831(3) Å,
which is longer than that of previously reported dinickel complexes [19]. The environments of the two
nickel atoms are very similar to each other; both are six-coordinate, coordinated to four oxygen and
two nitrogen atoms in a slightly distorted octahedron, although there are still some differences such as
Ni(1) is bound by four O atoms (O4, O7, O10, O1w) coming from three different phenolic groups of
Schiff base (L1, L2, L3) ligands and a coordinated water molecule, where the Ni–O bond distances
range from 1.9410(10) to 2.3389(10) Å, whereas the four O atoms that surround Ni(2) come from
three Schiff base molecules (L1, L3, L4), and the bond distances are from 2.0048(10) to 2.2876(9) Å.
To the best of our knowledge, this is the first example of a crystallographically characterized complex
with four 2-[(4-methylphenylimino)methyl]-6-methoxyphenol Schiff base ligands with three types of
coordination modes in one complex: (i) simple N,O-chelating bidentate [Figure 3 (a)] L2 and L4
belong to this mode, and they chelate to Ni(1) and Ni(2) respectively, the coordinated atoms are both
phenolic O and imino N; (ii) bidentate [Figure 3 (b)] L3 chelates to Ni(2) with phenolic O and imino N,
and the phenolic O also bridges to Ni(1); (iii) bridging quadridentate [Figure 3 (c)], this mode is
adopted by L1. In addition to the phenolic O and imino N, the methoxyl O is also involved in the
coordination to Ni. These are apparently important for rational design and constitution of new
framework structures. The main bond lengths and bond angles are listed in Table. 7. Two methoxy-
phenol rings of the L2 and L3 ligand are almost parallel to each other with a dihedral angels 13.91°,
and the center distance of which is 3.85 Å indicated a weak π···π stacking interaction[20]. There are

Molecules 2009, 14
2585
several water molecules involved in O–H···O intramolecular hydrogen-bonding interactions, which
help to stabilize this structure.
Figure 2. Molecular structure of the complex 1 (probability of ellipsoid is 30%). All the
non-coordinated water molecules are omitted for clarity.
Figure 3. The three coordinate modes of L in complex 1.
2.4. Thermal analysis
The TG-DTG curve of complex 1 is shown in Figure 4. There are three main weight loss stages for
◦
◦
the decomposition process. In the first stage, from 76 C~152 C, 9.14% of the weight is lost, which
corresponds to the loss of six water molecules, which coincides with the calculated value 9.10%. The

Molecules 2009, 14
2586
temperature range of 226 °C~413 °C is the second stage, with a weight loss of about 59.46% and it
seems that three Schiff ligand molecules has burned off (calcd. 61.00%). The remaining one cannot
remain too long, and its loss accounts for the third stage with a loss of 15.60% in the temperature range
◦
◦
of 431 C ~460 C (the calculated value is 13.95%). The remaining mass of 15.50% seems likely to
correspond to NiO (calcd. 12.56%).
Figure 4. The TG-DTG curves of complex 1.
0
D T G
20
40
60
T G
80
100
100 200 300 400 500 600 700 800
Tem perature/oC
2.5. Non-isothermal kinetics for Steps 1 and 2
For the TG and DTG curves, the non-isothermal kinetic data in the steps 1 and 3 of the thermal
decomposition were analyzed by means of differential and integral methods. The differential equation
used was proposed by Achar et al [21,22]. The integral equation was Coats-Redfern equation [23]. The
used forms f(α) and g(α) are listed in Table 2. The original data for Steps 1 and 3 determined from the
TG-DTG curves are listed in Table 3.
Archar equation:
ln[(dα/dt)/f(α)] =lnA - E/(RT)
Coats-Redfern equation:
ln[g(α)/T2] = ln(AR)/(βE) - E/(RT)
In the above equations, α is the fraction of the reacted material, T is the absolute temperature and
f(α) and g(α) are differential and integral mechanism functions, respectively. E and A are the derived
apparent activation energy and pre-exponential factor, respectively, R is the gas constant and β is the
heating rate.
The kinetic analysis was performed by the linear least square method. The results of the kinetic
parameters E, A and correlation coefficients r for step 1 and 2 are shown in Table 3.
We fitted the kinetic parameters obtained (E and A) using the equations of Achar et al. and Coats-
Redfern (see Table 4). Comparing the results from the differential and integral methods, we found that
the values of E and A were acceptable and the linear correlation coefficients were also better when the
possible mechanism functions were rational selected.

Molecules 2009, 14
Table 2. Some integral and differential coefficient kinetic functions.
2587
Symbo Integral kinetic
function
Differential coefficient
kinetic function
Mechanism
l
D1
D2
α2
1/(2α)
One-dimensional diffusion
Two-dimensional diffusion
Three-dimensional diffusion
(cylindrical symmetry)
Three-dimensional diffusion
(spherical symmetry)
α+(1-α)ln(1-α)
[-ln(1-α)]-1
1D3
2D3
1-(2/3)α-(1-α)2/3
3/2[(1-α)-1/3-1]-1
[1-(1-α)1/3]2
3/2(1-α)2/3[1-(1-α)1/3]-1
3D3
4D3
[(1+α)1/3-1]2
3/2(1+α)2/3[(1+α)1/3-1]-1
3/2(1-α)4/3[1/(1-α)1/3-1]-1
Three-dimensional diffusion
Three-dimensional diffusion
[1/(1-α)1/3-1]1/2
Random nucleation and nuclei
growth (n=1)
Random nucleation and nuclei
growth (n=1.5)
Random nucleation and nuclei
growth (n=2)
Random nucleation and nuclei
growth (n=3)
Random nucleation and nuclei
growth (n=4)
Contracting sphere (cylindrical
symmetry)
A1
A1.5
A2
A3
A4
R2
-ln(1-α)
(1-α)
[-ln(1-α)]2/3
[-ln(1-α)]1/2
[-ln(1-α)]1/3
[-ln(1-α)]1/4
1-(1-α)1/2
3/2(1-α)[-ln(1-α)]1/3
2(1-α)[-ln(1-α)]1/2
3(1-α) [-ln(1-α)]2/3
4(1-α) [-ln(1-α)]3/4
2(1-α)1/2
Contractingsphere
R3
1-(1-α)1/3
3(1-α)2/3
(spherical symmetry)
Exponential nucleation
Exponential nucleation
Exponential nucleation
Exponential nucleation
Chemical reaction
P1
P2
P3
P4
C2
C1.5
α
1
α1/2
2α1/2
3α2/3
4α3/4
(1-α)2
2(1-α)3/2
α1/3
α1/4
(1-α)-1-1
(1-α)-1/2
Chemical reaction
Table 3. Kinetic compensation parameters for Step 1 and Step 2.
Step 1 Step 2
T/K
α
dα/dt
T/K
α
dα/dt
363.15
373.15
383.15
393.15
403.15
413.15
0.0204
0.0548
0.1163
0.2237
0.4937
0.9043
2.1941
1.8824
1.5496
1.6131
1.8258
0.6285
493.15
503.15
513.15
523.15
533.15
543.15
0.0158
0.0416
0.0930
0.1888
0.3547
0.6250
2.5213
1.3356
1.8930
1.6043
1.3785
1.2225

Molecules 2009, 14
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Table 4. The kinetic data of thermal decomposition of Step 1.
Achar method
A/s-1
Coats–Redfern method
No.
1
2
3
4
5
6
7
8
E/kJ mol-1
r
E/kJ mol-1
A/s-1
r
207.59
265.51
290.10
336.58
162.82
475.99
74.73
-35.34
36.58
-145.40
-172.92
5.02
2.18E+06 0.9548
4.98E-03 0.9914
8.78E+02 0.9947
8.53E-12 0.9905
4.90E-14 0.9032
2.52E+00 0.9573
1.27E+02 0.7679
1.16E-05 0.5499
2.58E-16 0.6520
6.08E-20 0.9530
8.57E-22 0.9683
4.07E+17 0.1679
4.70E+11 0.6219
1.16E-05 0.7463
2.58E-16 0.9640
6.08E-20 0.9761
8.57E-22 0.9799
4.07E+17 0.7969
4.70E+11 0.7922
171.38
181.63
185.89
194.64
161.29
224.61
101.24
65.41
47.49
29.57
20.61
90.98
94.19
82.55
38.14
23.34
15.94
127.51
16.21
3.37E+20
5.40E+21
5.06E+21
9.66E+22
1.20E+18
2.31E+27
3.26E+11
3.97E+06
1.25E+04
3.38E+01
1.55E+00
4.87E+09
9.74E+09
5.37E+08
4.51E+02
3.37E+00
2.54E-01
2.47E+15
6.03E-01
0.9989
0.9990
0.9986
0.9970
0.9980
0.9867
0.9926
0.9922
0.9918
0.9907
0.9894
0.9981
0.9969
0.9988
0.9986
0.9983
0.9979
0.9673
0.6840
9
10
11
12
13
14
15
16
17
18
19
28.25
-64.69
-200.83
-246.21
-268.90
214.14
144.43
Thus we deduced that the possible mechanism for the step 1 of thermal decomposition of the
complex was a 1D3 chemical reaction. The corresponding non-isothermal kinetic equation was:
f(α)=2/3[(1-α)-1/3-1]-1, g(α)=1-(2/3)α-(1-α)2/3
The average values of the apparent activation energy E and pre-exponential factor A were 239.00
kJ·mol-1 and 0.9967, respectively.
The possible mechanism for step 2 was 2D3 chemical reaction. The corresponding non-isothermal
kinetic equation was
f(α)=3/2(1-α)2/3[1-(1-α)1/3]-1, g(α)=[1-(1-α)1/3]2
The average values of the apparent activation energy E and pre-exponential factor A were 376.34
kJ·mol-1 and 0.9962, respectively.
From the thermal analysis, we can see the decomposition procession of the complex is complicated.
For infer the mechanism of the thermal decomposition, we analyzed the non-isothermal kinetic in two
decomposition steps by means of differential and integral methods. We have found the proper
mechanism functions of the two steps and their decomposition activation energy.

Molecules 2009, 14
2589
Table 5. The kinetic data of thermal decomposition of Step 2.
Achar method
A/s-1
Coats–Redfern method
No.
1
2
3
4
5
6
7
8
E/kJ mol-1
r
E/kJ mol-1
A/s-1
r
325.14
366.94
382.33
412.37
276.76
502.52
35.18
-105.45
2.73
-246.09
-281.25
-9.90
1.12E+21
3.70E+23
2.02E+24
9.59E+25
6.57E+16
1.16E+32
4.55E+02
3.05E-07
1.46E+00
1.53E-16
6.48E-19
2.07E-01
1.42E+00
3.76E-04
1.54E-16
9.63E-21
6.99E-23
5.51E+08
2.50E+05
0.9875
0.9927
0.9933
0.9932
0.9760
0.9872
0.4475
0.8205
0.0447
0.9545
0.9638
0.1732
0.0849
0.7347
0.9743
0.9820
0.9844
0.7525
0.6703
317.17
328.16
332.19
340.31
302.95
365.92
172.10
111.86
81.75
51.63
36.57
162.85
165.85
154.28
72.84
3.75E+28
2.72E+29
1.61E+29
1.16E+30
1.28E+26
5.83E+32
4.57E+14
4.83E+08
4.50E+05
3.63E+02
9.18E+00
2.34E+13
3.27E+13
5.67E+12
4.72E+04
7.71E+01
2.77E+00
7.18E+16
1.22E-02
0.9974
0.9985
0.9988
0.9992
0.9958
0.9994
0.9995
0.9995
0.9994
0.9994
0.9993
0.9988
0.9992
0.9972
0.9968
0.9963
0.9958
0.9979
0.7115
9
10
11
12
13
14
15
16
17
18
19
5.13
-54.97
-245.03
-308.38
-340.06
125.33
80.25
45.69
32.12
192.70
10.60
3. Experimental
3.1. Materials and general methods
NiCl2·6H2O, o-vanillin, p-toluidine, and other chemical reagents were obtained from commercial
sources and used without further purification. The metal contents were determined by EDTA
complexometric titration after decomposition a known amount of the complexes with concentrated
nitric acid. Elemental analyses for C, H and N were carried out on an Elementar Vario EL III
elemental analyzer. IR spectra of KBr pellets were recorded on a Nicolet NEXUS 670 FTIR
spectrophotometer in the range of 4,000-400 cm-1. Thermal analyses were carried out using Mettler-
Toludo TGA/SDTA851e thermal analyzer with a heating rate of 10 ◦C·min-1 from 30 ◦C to 800 ◦C in an
air atmosphere.
3.2. Syntheses
C15H15NO2(HL): Schiff base ligand was prepared by the direct solution reaction of p-toluidine (10.0
mmol, 1.07 g) and o-vanillin (0.01 mol, 1.52 g) refluxed in ethanol (~60 mL) on a water bath for 2 h.
The solution was cooled to room temperature, and then the red crystals were obtained, washed with
absolute ethanol and dried. Yield 1.93 g (80%), m.p.~100°C. It was recrystallized from methanol
before used.

Molecules 2009, 14
2590
Figure 5. Structure of Schiff base ligand.
H3C
N
HO
OCH3
[Ni2(H2O)L4]·5H2O(1): NiCl2·6H2O (1 mmol, 0.237 g) dissolved in anhydrous ethanol (10 mL) was
stirred with HL (0.57 g, 2 mmol) in anhydrous ethanol (20 mL) and refluxed for 2 h on a water bath,
then the solid that deposited after cooling to room temperature was washed with ethanol and dried.
Yield 0.80 g (70%). Green single crystals of complex 1 were obtained suitable for X-ray diffraction
from the mother liquor after five days of slow evaporation at room temperature.
3.3. Crystal structure determination
Single crystals of complex 1 was selected and was structurely mesured measured with a Rigaku R-
AXIS RAPID diffractometer with graphite-monochromated Mo-Kα radiation (λ = 0.71073 Å ) at 296
K. Empirical absorption corrections were applied by use of the ABSCOR program. The structures were
solved by direct methods and all calculations were performed with the aid of the SHELXL PC
program[24]. The structures were refined by full-matrix, least-squares minimization of Σ(Fo—Fc)2 with
anisotropic thermal parameters for all atoms except H atoms. The crystal data of the complex 1 is
summarized in Table 6, selected bond lengths and angles are show in Table 7.
Table 6. Crystallographic Data for Complex 1.
Empirical formula
Formula weight
T/ K
C60H68N4Ni2O14
1186.60
296(2)
Crystal system
Space group
monoclinic
P 21/c
a (Å)
b (Å)
c (Å)
α (°)
13.2837(5)
27.3886(10)
17.5415(6)
90
β (°)
108.429(2)
90
6054.7(4)
4
1.302
0.687
γ (°)
V (Å3)
Z
Density (g/cm3)
Μ (mm-1)
F (000)
2496
Absorption correction
Data/restrains/parameters
θ range /°
none
10668 / 18 / 748
1.43 to 25.00

Molecules 2009, 14
2591
Table 6. Cont.
-15<=h<=15, -32<=k<=31, -
Limiting indices
20<=l<=20
Reflections collected/ unique
Rint
GOOF on F2
81485 / 10668
0.0950
1.032
R and wR (I > 2σ(I))
R indices (all data)
(Δρ)max, (Δρ)min (e·Å-3)
R = 0.0873, wR = 0.2594
R = 0.1287, wR = 0.3012
2.174 and -0.465
Table 7. Selected Bond Lengths (Å) and Bond Angles (°) for Complex 1.
Bond
(Å)
Bond
(Å)
Bond
(Å)
Ni(1)-O(4)
1.9734(10) C(7)-N(1)
1.9410(10) C(9)-N(1)
2.3389(10) C(22)-N(2)
1.2942(19) C(18)-O(5)
1.4138(19) C(23)-O(5)
1.3658(19)
1.450(2)
Ni(1)-O(7)
Ni(1)-O(10)
Ni(1)-O(1W)
Ni(1)-N(2)
1.310(2)
1.410(2)
C(32)-O(7)
C(33)-O(8)
1.3041(16)
1.3614(15)
1.436(2)
2.2364(8)
C(24)-N(2)
2.0680(11) C(39)-N(3)
2.0898(10) C(37)-N(3)
1.4309(18) C(38)-O(8)
Ni(1)-N(3)
1.287(2)
1.321(2)
1.428(2)
1.3079(18)
1.351(2)
1.451(2)
1.3049(16)
(°)
C(47)-O(10)
C(48)-O(11)
C(53)-O(11)
1.3431(16)
1.3759(15)
1.4333(19)
Ni(2)-O(1)
2.0253(8)
2.0602(10) C(54)-N(4)
2.2876(9) C(2)-O(1)
C(52)-N(4)
Ni(2)-O(4)
Ni(2)-O(5)
Ni(2)-O(10)
Ni(2)-N(1)
2.0048(10) C(3)-O(2)
2.0977(13) C(8)-O(2)
2.0545(10) C(17)-O(4)
Ni(2)-N(4)
Angle
(°)
Angle
Angle
(°)
O(4)-Ni(1)-O(10)
O(4)-Ni(1)-O(1W)
O(7)-Ni(1)-O(4)
O(7)-Ni(1)-O(10)
O(7)-Ni(1)-O(1W)
77.63(4)
86.08(4)
165.05(4)
89.40(4)
85.06(4)
N(3)-Ni(1)-O(4)
N(3)-Ni(1)-O(7)
N(3)-Ni(1)-O(10)
96.47(4)
91.81(4)
94.16(4)
O(10)-Ni(2)-O(4) 83.91(4)
N(1)-Ni(2)-O(1)
N(1)-Ni(2)-O(4)
83.81(4)
169.18(4)
N(3)-Ni(1)-O(1W) 176.05(4)
N(1)-Ni(2)-O(10) 103.13(4)
N(2)-Ni(1)-N(3)
O(1)-Ni(2)-O(4)
O(1)-Ni(2)-O(5)
O(4)-Ni(2)-O(5)
O(5)-Ni(2)-O(10)
O(10)-Ni(2)-O(1)
98.66(4)
87.80(4)
84.21(3)
72.08(4)
155.78(4)
91.85(4)
N(1)-Ni(2)-O(5)
N(4)-Ni(2)-O(1)
N(4)-Ni(2)-O(4)
N(4)-Ni(2)-O(5)
100.19(4)
176.94(5)
93.60(4)
93.62(4)
O(10)-Ni(1)-O(1W) 83.41(3)
N(2)-Ni(1)-O(4)
N(2)-Ni(1)-O(7)
N(2)-Ni(1)-O(10)
N(2)-Ni(1)-O(1W)
92.08(4)
98.97(4)
164.41(4)
84.23(4)
N(4)-Ni(2)-O(10) 91.00(4)
N(4)-Ni(2)-N(1) 94.47(5)
4. Supplementary Material
Supplementary crystallographic data have been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 731857. Copies of this information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (Fax: +44 1223 336033;
Email: deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).

Molecules 2009, 14
2592
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© 2009 by the authors; licensee Molecular Diversity Preservation International, Basel, Switzerland.
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Commons Attribution license (http://creativecommons.org/licenses/by/3.0/).