Crystal structure and thermodecomposition kinetics of a three-dimensional supramolecular Mn complex with 8-hydroxyquinoline

Article abstract of DOI:10.1134/S1070328406070074

A three-dimensional supramolecular complex, [Mn(8-OHQ)₃] ? CH₃OH (8-OHQ is 8-hydroxyquinoline), C₂₈H ₂₂MnN₃O₄, was synthesized in methanol, and its crystal structure was determined by X-ray crystallography. The crystals are triclinic, space group P P 1, a = 10.823(2) A, b = 13.222(3) A, c = 17.283(3) A, α = 90.03(3)°, β = 93.15(3)°, γ = 92.58(3)°, V = 2467.0(8) A³, Z = 4, F(000) = 1072, ρ = 1.399 g/cm³, μ = 0.575 mm^-1. Hydrogen bonds and intermolecular interactions, which are observed in the complex, stabilize its structure. The thermal decomposition kinetics of the complex was investigated under nonisothermal conditions using the Achar differential method and the Coats-Redfern integral method. Pleiades Publishing, Inc., 2006.

Full text of DOI:10.1134/S1070328406070074

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2006, Vol. 32, No. 7, pp. 504–510. © Pleiades Publishing, Inc., 2006.
Crystal Structure and Thermodecomposition Kinetics
of a Three-Dimensional Supramolecular Mn Complex
with 8-Hydroxyquinoline1
L. R. Yang, C. F. Bi, Y. H. Fan, S. Q. Liu, F. Guo, and X. K. Ai
College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao, China
Received July 4, 2005
Abstract—A three-dimensional supramolecular complex, [Mn(8-OHQ)3] · CH3OH (8-OHQ is 8-hydroxy-
quinoline), C28H22MnN3O4, was synthesized in methanol, and its crystal structure was determined by X-ray
crystallography. The crystals are triclinic, space group P P1 , a = 10.823(2) Å, b = 13.222(3) Å, c = 17.283(3) Å,
α = 90.03(3)°, β = 93.15(3)°, γ = 92.58(3)°, V = 2467.0(8) Å3, Z = 4, F(000) = 1072, ρ = 1.399 g/cm3, µ =
0.575 mm–1. Hydrogen bonds and intermolecular interactions, which are observed in the complex, stabilize its
structure. The thermal decomposition kinetics of the complex was investigated under nonisothermal conditions
using the Achar differential method and the Coats–Redfern integral method.
DOI: 10.1134/S1070328406070074
INTRODUCTION
teristic results of IR spectra, elemental analysis, and
crystal structure are reported.
Manganese is essential in the metabolic processes of
organisms as a micronutrient. Reports have shown that
Mn affects several fundamental processes in the mobi-
lization and activation of immunoactive haemocytes.
Manganese plays an important role in antioxidant de-
fences, being a necessary component of mitochondria
enzymes, such as superoxide dismutase (MnSOD), and
activates a large number of other enzymes. It also af-
fects the central nervous system and causes the disorder
manganism [1–3]. Manganese peroxidase is considered
to catalyze the H2O2-dependent oxidative degradation
of lignin. Experiments have proved that the Mn2+/Mn3+
couple serves as a redox mediator in the oxidation phen-
olic lignin substructures [4]. As an excellent and useful
ligand, 8-hydroxyquinoline (8-OHQ) presents many
bioactivities and pharmacological activities, such as an-
tibacterial, antitumor, antiphlogistic, and adjusting the
metabolism of organism, etc. [5–7]. It is widely used in
the separation and analysis of metal ions as well [8].
EXPERIMENTAL
Reagents. Taurine was BR (Biochemical Reagent).
Manganese acetate, potassium hydroxide, 8-hydroxy-
quinoline, methanol, and other solvents were AR
(Analysis Reagent) grade and were used without fur-
ther purification.
Preparation of the Schiff base ligand. Taurine
(0.01 mol) and potassium hydroxide were added to
methanol (15 ml) to make a pellucid solution. At 50°C,
it was slowly dripped into the methanol solution (15 ml)
containing 2-thenyl formaldehyde (0.01 mol). The mix-
ture was stirred for 0.5 h to give a silvery white and
flake-shape precipitate. The product was collected by
filtration, washed several times with anhydrous ethanol,
and dried under vacuum. Thus, the taurine-2-thenyl
formaldehyde Schiff base (TTFS, C7H8NS2O3K · H2O)
ligand was produced. The yield of TTFS was 88.6%.
The quantitative structure activity relationship
(QSAR) shows that planar molecules can selectively
be intercalated in certain sites in nucleic acid, whose
complexes can be used as the structural probes of nu-
cleic acid to expose the mechanism of metal–enzyme
acting on nucleic acid [9]. 8-OHQ gives a nearly pla-
nar structure with conjugation, and its complexes
can have potential applications as mentioned above.
The [Mn(8-OHQ)3] · CH3OH complex was synthe-
Anal. calcd (%): C, 30.50; H, 3.62; N, 5.11; S, 19.00
For C7H8NS2O3K · H2O
found (%):
C, 30.44; H, 3.58; N, 5.18; S, 19.53.
IR data (KBr pellets; ν, cm–1): 3438 (O–H), 1640
(C=N), 1044.3, 1165.2, 1186.7 (SO3).
Preparation of the complex. TTFS (0.5 mmol) in
MeOH (15 ml) was dripped into the solution of
sized through a special method, for which the charac- Mn(CH3COO)2 · 4H2O (the same molar ratio with the
anterior) in MeOH (15 ml). The reaction mixture was
stirred at 50°C. Two hours later, 8-OHQ (0.5 mmol in
1
The text was submitted by the authors in English.
504

CRYSTAL STRUCTURE AND THERMODECOMPOSITION KINETICS
505
Table 1. Summary of crystallographic data for the complex
10 ml of anhydrous ethanol) was dripped into the mix-
ture, continuously to be stirred at the same temperature
for 8 h. The brown solution obtained was filtered, and the
filtrate was left to stand for slow evaporation at room
temperature. After 7 days, deep brown crystals were
formed. Single crystals suitable for X-ray analysis were
obtained by recrystallization from anhydrous ethanol.
[Mn(8-OHQ)3] · CH3OH
Empirical formula
Formula weight
Crystal system
Space group
a, Å
C28H22MnN3O4
2077.70
Triclinic
P1
Anal. calcd (%):
For [Mn(8-OHQ)3] · CH3OH
found (%): C, 64.27; H, 4.19; N, 8.13.
C, 64.69; H, 4.24; N, 8.09.
10.823(2)
13.222(3)
17.283(3)
90.03(3)
92.58(3)
4
b, Å
c, Å
α, deg
β, deg
Physical measurements. Elemental analyses were
performed on a Perkin−Elmer 240C elemental analy-
zer. IR spectra were recorded in the 4000–400 cm–1 re-
gion using KBr pellets on an AVATAR 360 FT-IR
spectrometer, and the crystal structure was determined
on a SMART CCD diffractometer. Thermogravimeter-
ic measurements were made using a Perkin−Elmer
TGA7 thermogravimeter. The heating rate was pro-
grammed to be 10 K/min with the protecting stream of
N2 flowing at 40 ml/min.
Z
Volume, Å3
2467.0(8)
1020
F(000)
Limiting indices
0 ≤ h ≤ 12, –15 ≤ k ≤ 0,
–20 ≤ l ≤ 20
Reflections collected/unique
4747/4747; (Rint = 0.0054)
Refinement method
Full-matrix least-squares
on F2
X-Ray crystallographic determination. The se-
lected crystal of dimensions 0.40 × 0.32 × 0.24 mm was
mounted on a Bruker Smart CCD X-ray single-crystal
diffractometer. Reflection data were at 293(2) K using
Data/restraints/parameters
Goodness-of-fit on F2
4747/21/681
1.216
graphite monochromated MoKα-radiation (λ
=
R indices (all data)
Largest diff. peak and hole, eÅ–3
R1 = 0.0852, wR2 = 0.1787
0.428 and –0.359
0.71073 Å), ω/2θ scan mode. All 4747 independent re-
flections were collected in a range of 1.18° ≤ θ ≤ 27.16°,
of which 3216 reflections with I = 2σ(I) were consid-
ered to be observed and used in the subsequent refine-
ment. The correction for Lp factors and empirical ab-
sorption were applied to the data. The structure were
solved by direct methods and Fourier syntheses. Posi-
tional and thermal parameters were refined by the full-
matrix least-squares method on F2 using the SHELXTL
software package [10]. The final least-square cycle of
refinement gave R = 0.0489, wR = 0.1598, the weight-
and manganese acetate was performed under the same
conditions. As a result, the complex was not obtained.
Non-hydrogen fractional atomic coordination and
equivalent isotropic temperature factors, selected bond
lengths, band angles, and intermolecular interaction
distances of the complex are listed in Tables 2 and 3, re-
spectively. The crystal structure and molecular packing
drawing of the complex are shown in Figs. 1 and 2.
Structural units in the crystal are two crystallo-
graphically independent monomeric complex mole-
cules [Mn(8-OHQ)3] and solvate methanol molecules.
The structures and geometric parameters of two com-
plexes with the Mn(1) and Mn(2) atoms are similar.
Further descriptions are for molecule with the Mn(1)
atom.
ing scheme w = 1/[σ2(F2o) + (0.0910P)2 + 1.4692P],
where P = (F2o + 2Fc2 )/3. A summary of the key crys-
tallographic information is given in Table 1.
RESULTS AND DISCUSSION
Description of crystal structure. Our anticipative
Figure 1 shows that the central Mn(III) atom is
product was the complex of Mn(III) with taurine-2-thenyl bound by the O and N atoms belonging to 8-OHQ
formaldehyde Schiff base (TTFS)-Mn(III)-8-OHQ. (O(1), N(1), O(2), N(2), O(3), N(3)) to form a six-coor-
Accidentally, the [Mn(8-OHQ)3] · CH3OH complex dinate complex with three five-membered chelate rings
and its crystal were obtained, owing to the following (ring 1: Mn(1)–O(1)–C(6)–C(5)–N(1); ring 2: Mn(1)–
facts: a) the weaker coordination ability of –SO3H in O(2)–C(15)–C(14)–N(2); ring 3: Mn(1)–O(3)–C(24)–
TTFS; b) the steric effect of 8-OHQ and its stronger co- C(23)–N(3)). The Mn atoms in the five-membered che-
ordination ability (compared to the former). TTFS late rings deviate from the plane for a mean value of
might be substituted by 8-OHQ to form the complex, 0.0051 Å. The central Mn(III) atom adopts a distorted
and TTFS acts as a dropping-out group. Here, TTFS octahedron geometry with O(1), O(2), O(3), N(3), ly-
presented a chemically modification action in the reaction. ing on the equatorial plane. The corresponding bond
To validate our conclusion, a reaction between 8-OHQ angles are O(1)Mn(1)O(2) 94.73(3)°, O(1)Mn(1)N(3)
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 7 2006

506
YANG et al.
Table 2. Non-hydrogen fractional atomic coordination (×104) and equivalent isotropic temperature factors (×103)
* *
(Ueq = (1/3)ΣiΣjUij ai aj aiaj) for complex [Mn(8-OHQ)3] · CH3OH
Atom
x
y
z
Ueq, Å2
Atom
x
y
z
Ueq, Å2
Mn(1)
4268(1)
9812(1)
14814(1)
9936(5)
8486(4)
9841(5)
14929(4)
13481(4)
14844(4)
15499(7)
9482(7)
9252(5)
10193(5)
11290(6)
14253(6)
15185(5)
16299(6)
8911(7)
8583(9)
–7423(1)
–7576(1)
–7629(2)
–6991(2)
–7370(3)
–7371(2)
–8010(2)
–7632(3)
–8352(6)
–3333(5)
–8653(3)
–6134(3)
–7736(3)
–6341(3)
–8859(3)
–7263(3)
–9136(4)
–9886(5)
36(1)
37(1)
47(2)
48(2)
51(3)
51(2)
46(2)
44(2)
122(5)
119(5)
45(3)
39(3)
38(3)
45(3)
41(3)
34(3)
65(4)
72(5)
85(6)
69(5)
51(4)
49(3)
C(7)
1146(10)
953(13)
1865(14)
3588(9)
3353(10)
3237(10)
3392(9)
3642(8)
3845(8)
3787(9)
3524(9)
3322(10)
3792(10)
9680(8) –8537(5)
9370(9) –9292(6)
8996(10) –9829(6)
11020(7) –5736(4)
11049(7) –4917(4)
10150(8) –4517(4)
9229(7) –4928(4)
9281(6) –5753(3)
8399(6) –6220(4)
7476(7) –5848(4)
7435(7) –5017(4)
8270(8) –4567(4)
11999(7) –7921(4)
69(5)
92(6)
104(7)
53(4)
60(4)
60(4)
50(4)
38(3)
45(3)
50(3)
62(4)
59(4)
52(4)
65(5)
60(4)
46(5)
36(4)
42(4)
52(5)
60(5)
58(5)
66(5)
Mn(2) 10731(1)
C(8)
O(1)
O(2)
O(3)
O(4)
O(5)
O(6)
O(7)
O(8)
N(1)
N(2)
N(3)
N(4)
N(5)
N(6)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
2579(5)
4098(6)
6017(7)
12429(5)
10906(5)
8984(6)
4539(9)
–404(9)
4467(7)
3737(7)
4575(7)
10545(7)
11273(7)
10420(7)
5399(10)
5303(12)
4168(14)
3114(12)
3318(9)
2320(9)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
4229(13) 12992(10) –8118(4)
5425(10)
6302(12)
5805(11)
6549(11)
7815(12)
8287(13)
13230(9) –8132(4)
12507(9) –7913(4)
11544(8) –7741(3)
10718(8) –7536(3)
10929(9) –7546(4)
11888(9) –7710(4)
8604(9) –10133(5)
8965(8)
9273(7)
9635(7)
–9630(4)
–8886(4)
–8327(4)
7570(10) 12672(10) –7895(4)
9586(11) 13913(8) –5870(4)
89.7(3)°, O(2)Mn(1)O(3) 94.3(3)°, and O(3)Mn(1)N(3) O(2)Mn(1)N(3) 171.7(2)°, which deviate from 180°.
81.9(3)°. The sum of bond angles (nearly 360°) indi- The bonds along the axis (Mn(1)–N(1) (2.275(5) Å)
cates that the four atoms (O(1), O(2), O(3), N(3)) are al- and Mn(1)–N(2) (2.390(5) Å)) are distinctly longer
most coplanar. The bond angles of those atoms situated than those of the equatorial plane (Mn(1)–O(1)
on the diagonals are O(1)Mn(1)O(3) 169.6(2)°, 1.857(5), Mn(1)–O(2) 1.911(6), Mn(1)–O(3) 1.890(8),
C(36)
C(30)
C(31)
C(32)
C(35)
C(34)
O(8)
C(29)
C(28)
C(18)
C(12)
C(14)
C(13)
C(56)
C(11)
C(10)
N(4)
C(33)
C(17)
C(16)
O(4)
N(2)
C(15)
O(2)
O(6)
Mn(2)
C(42)
N(5)
C(25)
C(26)
C(21)
O(3)
C(24)
O(5)
C(23)
Mn(1)
C(27)
O(7)
C(22)
N(3)
O(1)
C(37)
C(43)
C(19)
C(20)
C(41)
C(45)
N(1)
C(6)
C(40)
C(38)
C(39)
C(44)
C(55)
C(1)
C(2)
C(7)
C(8)
C(5)
C(4)
C(9)
C(3)
Fig. 1. Crystal structure of the complex [Mn(8-OHQ) ] · CH OH.
3
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CRYSTAL STRUCTURE AND THERMODECOMPOSITION KINETICS
507
Table 3. Selected bond lengths (d) and angles (ω) for complex [Mn(8-OHQ)3] · CH3OH
Bond
d, Å
Bond
d, Å
Bond
d, Å
Mn(1)–O(1)
Mn(1)–O(3)
Mn(1)–O(2)
Mn(1)–N(3)
1.857(5)
1.890(8)
1.911(6)
2.046(9)
Mn(1)–N(1)
Mn(1)–N(2)
Mn(2)–O(4)
Mn(2)–O(6)
2.275(5)
2.390(5)
1.852(6)
1.890(6)
Mn(2)–O(5)
Mn(2)–N(6)
Mn(2)–N(4)
Mn(2)–N(5)
1.935(5)
2.083(7)
2.277(6)
2.370(6)
Angle
ω, deg
Angle
ω, deg
Angle
ω, deg
O(1)Mn(1)O(3)
O(1)Mn(1)O(2)
O(3)Mn(1)O(2)
O(1)Mn(1)N(3)
O(3)Mn(1)N(3)
O(2)Mn(1)N(3)
O(1)Mn(1)N(1)
O(3)Mn(1)N(1)
O(2)Mn(1)N(1)
N(3)Mn(1)N(1)
169.6(2)
94.7(3)
94.3(3)
89.7(3)
81.9(3)
171.7(2)
90.4(2)
83.8(2)
94.6(2)
92.3(2)
O(1)Mn(1)N(2)
O(3)Mn(1)N(2)
O(2)Mn(1)N(2)
N(3)Mn(1)N(2)
N(1)Mn(1)N(2)
O(4)Mn(2)O(6)
O(4)Mn(2)O(5)
O(6)Mn(2)O(5)
O(4)Mn(2)N(6)
O(6)Mn(2)N(6)
82.3(2)
104.5(2)
78.7(2)
95.0(2)
169.6(3)
169.9(2)
89.5(2)
99.2(3)
95.0(3)
77.0(3)
O(5)Mn(2)N(6)
O(4)Mn(2)N(4)
O(6)Mn(2)N(4)
O(5)Mn(2)N(4)
N(6)Mn(2)N(4)
O(4)Mn(2)N(5)
O(6)Mn(2)N(5)
O(5)Mn(2)N(5)
N(6)Mn(2)N(5)
N(4)Mn(2)N(5)
171.75(19)
88.3(2)
86.0(2)
94.8(2)
92.2(2)
83.0(2)
103.7(2)
77.5(2)
96.2(2)
168.41(17)
and Mn(1)–N(3) 2.046(9) Å) mainly due to the Jahn– are possible [13, 14], as can be deduced from the short
Teller effect [11].
contact distances 3.9521, 3.9050, and 3.9970 Å, re-
spectively (see Table 4). As a result, π–π stacking oc-
curs omnipresently, which stabilizes the structure of the
complex and is beneficial to the transmission of electric
charges [15]. In the unit cell, the four Mn atoms are co-
planar and occupy the parallelogram vertexes, respec-
tively.
Figure 2 illustrates a perspective view of the crystal
packing in the unit cell. The most prominent structural
feature of the complex is that it assembles a three-di-
mensional supramolecular network through potentially
weak C–H···O hydrogen bonds, intermolecular interac-
tions, and C–H···π (C(20)–H(20A)···Cg(5) and C(47)–
H(47A)···Cg(2), etc.) supramolecular interactions [12].
Spectroscopic studies. 8-OHQ owns 5 characteris-
Furthermore, the weaker π–π stacking interaction, such tic absorption peaks: ν(O–H) (3088), δ(O–H) (1210),
as Cg(2)–Cg(12), Cg(14)–Cg(12), and Cg(17)–Cg(9), ν(C=N) (1587), ν(C–O) (1104), and ν(C=C) (1476 cm–1).
x
z
0
y
Fig. 2. Packing drawing of the complex [Mn(8-OHQ) ] · CH OH.
3
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YANG et al.
Table 4. Intermolecular interaction distances (Å) for complex [Mn(8-OHQ)3] · CH3OH
D–H···A1
Symm. A
H···A, Å
D···A, Å
Angle D–H···A, deg
Cg–Cg, Å
C(12)–H(12A)···O(3)
C(25)–H(25A)···O(8)
C(27)–H(27A)···O(6)
C(39)–H(39A)···O(6)
C(48)–H(48A)···O(8)
C(52)–H(52A)···O(7)
C(54)–H(54A)···O(3)
C(20)–H(20A)···Cg(5)2
C(47)–H(47A)···Cg(2)
C(55)–H(55A)···Cg(7)
C(55)–H(55C)···Cg(7)
C(56)–H(56A)···Cg(10)
C(56)–H(56C)···Cg(8)
Cg(2)–Cg(12)# 3
1 – x, –y, 1 – z
1 + x, y, z
1 + x, y, z
–x, 1 – y, –z
x, 1 + y, z
–1 + x, y, z
–1 + x, 1 + y, z
x, y, z
2.51
2.52
2.36
2.50
2.44
2.56
2.47
3.01
2.85
3.31
3.38
3.04
3.18
3.31
3.18
3.21
3.32
3.15
3.20
3.33
3.87
3.70
3.65
3.65
3.68
3.85
145
128
152
148
133
126
154
154
152
106
100
130
133
x, 1 + y, z
x, 1 + y, z
x, 1 + y, z
x, y, z
x, y, z
x, –1 + y, z
x, –1 + y, z
x, y, z
3.95
3.91
4.00
Cg(14)–Cg(12)
Cg(17)–Cg(9)
1
2
D–H 0.93 Å.
Cg(2): Mn(1)–O(2)–N(2)–C(14)–C(15); Cg(5): Mn(2)–O(5)–N(5)–C(41)–C(42); Cg(7): N(1)–C(1)–C(2)–C(3)–C(4); Cg(8): N(2)–
C(10)–C(11)–C(12)–C(13)–C(14); Cg(9): N(3)–C(19)–C(20)–C(21)–C(22)–C(23); Cg(10): N(4)–C(28)–C(29)–C(30)–C(31)–C(32);
Cg(12): N(6)–C(46)–C(47)–C(48)–C(49)–C(50); Cg(14): C(13)–C(14)–C(15)–C(16)–C(17)–C(18); Cg(17): C(40)–C(41)–C(42)–C(43)–
C(44)–C(45); C(55), C(56): MeOH; C(20), Cg(2), Cg(7), Cg(8), Cg(9), and Cg(14) belong to Mn(1); C(47), Cg(5), Cg(10), and Cg(12)
belong to Mn(2).
3
#
The center-to-center distance between two adjacent rings; symmetry transformations used to generate equivalent atoms: x, –1 + y, z.
The bands ν(O–H) and δ(O–H) disappear after the for- participate in coordination. In addition, ν(C–O) shifts to
mation of the complex, which indicates that the hy- 1107 cm–1, which notarizes the result simultaneously [16].
droxy O atoms are coordinated with Mn, while ν(C=N)
Thermal decomposition kinetics studies. The TG
and DTG curves of the complex are shown in Fig. 3,
which indicates that the complex decomposes in two
shifts from 1587 to 1572 cm–1 showing that the N atoms
TG, %
100
DTG, %/min
0
85
70
65
50
35
20
–1
–2
–3
–4
–5
100
200
300
400
500
Temperature, °C
Fig. 3. TG−DTG curves of the complex [Mn(8-OHQ) ] · CH OH.
3
3
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 7 2006

CRYSTAL STRUCTURE AND THERMODECOMPOSITION KINETICS
509
Table 5. Data for step (2) of the thermodecomposition Table 6. Results of the analysis of the data for Step (2) in Ta-
of the complex [Mn(8-OHQ)3] · CH3OH obtained from the TG ble 5 by the differential method by Achar (I) and the integral
and DTG curves [19]
method by Coats–Redfern (II)
Ti, K
αi
(dα/dt)i
Num-
ber ki- kJ/mol
netic
func-
tion
E,
E,
lnA
r
lnA
r
kJ/mol
503
510
515
520
523
525
526
527
528
529
530
531
533
536
541
546
556
0.0239
0.1074
0.2176
0.3495
0.4145
0.4651
0.4900
0.5158
0.5421
0.5693
0.5965
0.6228
0.6759
0.7501
0.8447
0.8939
0.9406
0.0552
0.1419
0.1828
0.1991
0.2034
0.2058
0.2068
0.2077
0.2085
0.2074
0.2062
0.2031
0.1898
0.1653
0.1009
0.0469
0.0158
I
II
1
2
282.35 50.06 0.8691
89.54 18.24 0.4118
309.61 55.82 0.8920 141.62 29.84 0.6050
321.54 57.13 0.9018 164.82 33.78 0.6776
346.14 62.93 0.9194 208.20 43.99 0.7820
3
4
5
259.52 42.37 0.8545
57.01
8.21 0.2837
6
432.91 83.34 0.9621 338.37 74.61 0.9350
7
188.86 30.05 0.9399
122.98 15.19 0.9372
74.18 15.87 0.6718
8.25 0.60 0.1343
8
9
90.04 7.75 0.9343 –24.69 –7.12 0.4349
57.10 0.32 0.9278 –57.63 –14.96 0.8070
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
282.85 50.00 0.8691
159.69 22.48 0.9024
168.68 24.20 0.9156
89.54 18.24 0.4118
9.05 –0.14 0.0898
30.75
4.56 0.3106
136.78 17.76 0.8620 –56.03 –14.75 0.4236
64.00 1.61 0.8463 –128.81 –31.59 0.8433
39.74 –3.77 0.8280 –153.07 –37.38 0.9091
27.61 –6.46 0.8068 –165.20 –40.36 0.9318
266.95 48.38 0.9870 264.29 46.48 0.9716
56.30 0.77 0.9387 139.21 30.48 0.9076
88.26 6.99 0.8544 –104.55 –25.92 0.7421
steps. The first weight loss step has a decomposition
temperature range of 165–205°C with a weight loss of
6.13%, which corresponds to the loss of four molecules
of methanol (calcd 6.16%). The fact suggests that
methanol is closely bound to the complex by hydrogen
bonds. The second weight loss step has a decomposi-
tion temperature range of 205–500°C with a weight
loss of 81.71% corresponding to the loss of twelve mol-
ecules of 8-OHQ (calcd 83.17%). The fact that 8-OHQ
was lost at a higher temperature suggests that it is coor-
dinated with the metal ion. A value of 11.62% of the
original sample remained with its calculated weight
percentage of 10.59%, and Mn is the final residue.
386.50 74.63 0.9425
89.54 18.24 0.4118
584.15 119.22 0.9434 469.42 106.14 0.9089
781.79 163.81 0.9438 667.06 151.01 0.9204
251.54 46.70 0.9495 334.46 77.79 0.9923
173.44 25.03 0.9219
41.59
6.82 0.4158
On the basis of 30 kinetic functions, in both differ-
ential and integral forms commonly used in recent re-
ports [17, 18], the nonisothermal kinetics of the second
step was investigated using the Achar differential meth-
od [19] and the Coats–Redfern integral method [20].
105.10 10.91 0.7889 –186.19 –44.68 0.7591
85.04 6.49 0.7328 –316.35 –74.89 0.8449
71.31 3.44 0.6901 –446.51 –105.32 0.8798
73.95 4.83 0.9070 –201.60 –47.05 0.9723
75.45 3.97 0.8922 –71.43 –16.43 0.9164
The original kinetic data for step (2) obtained from
the TG and DTG curves are listed in Table 5, in which
Ti is the temperature at any point i on the TG and DTG
curves, and αi is the corresponding decomposition rate.
Equation (dα/dt)i = [β/(W0 – W1)](dW/dT)i in which
(dW/dT)i is the height of the peak in the DTG curve, β
is the heating rate, and W0 and W1 are the initial and fi-
nal weight at the stage, respectively.
pressed as follows: dα/dt = Ae–E/RT(1 – α)2, E =
265.62 kJ/mol, lnA = 47.43.
Supplementary materials. CCDC-273721 con-
tains the supplementary crystallographic data for this
*
paper.
The calculated kinetic parameters (E, A) and corre-
lation coefficients (r) of step (2) are listed in Table 6.
*These data can be obtained free of charge via
www.ccdc.cam.ac.uk/data_request/cif,
data_request@ccdc.cam.ac.uk, or by contacting The Cambridge
Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ,
UK; fax: +44-1223-336033.
or
by
e-mailing
The results obtained from the two different methods
are approximately the same when based on function
no. 18 for step (2) (Table 6). The kinetic equation is ex-
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 32 No. 7 2006

510
YANG et al.
11. Zhou Bei-chuan, Kou Hui-zhong, Gao Dong-zhao, et al.,
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