Thermal study of ruthenium(II) complexes containing pyridine-2,6-diimines

Article abstract of DOI:10.1007/s10973-007-8512-y

Thermal behaviors of mono-and binuclear Ru(II)-pydim complexes: [PydimCl₂RuL] (Pydim: pyridine-2,6-diimine; 2: L=NCMe; 3: L=PPh ₃) and [PydimCl₂Ru(L-L)RuCl₂Pydim] (4: L-L=pyrazine; 5: L-L=4,4'-bipyridine) have been studied in nitrogen atmosphere using TG/DTG and DTA techniques. The decompositions of complexes occur in stepwise. The values of activation energy, E _a, and reaction order, n of the thermal decomposition were calculated by means of several methods such as Coats-Redfern (CR), MacCallum-Tanner (MT), Horowitz-Metzger (HM), van Krevelen (vK), Madhusudanan-Krishnan-Ninan (MKN) and Wanjun-Yuwen-Hen-Cunxin (WYHC) based on the single heating rate. Most appropriate method was determined for each decomposition step according to the least-squares linear regression.

Full text of DOI:10.1007/s10973-007-8512-y

Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 3, 943–949
THERMAL STUDY OF RUTHENIUM(II) COMPLEXES CONTAINING
PYRIDINE-2,6-DIIMINES
1,2*
F. DoÈan , O. Dayan , M. Yürekli and B. †etinkaya
1
1
1
1Department of Chemistry, Faculty of Science, Ege University, zmir, Turkey
2Department of Chemistry, Faculty of Arts and Science, †anakkale Onsekiz Mart University, †anakkale, Turkey
Thermal behaviors of mono- and binuclear Ru(II)-pydim complexes: [PydimCl2RuL] (Pydim: pyridine-2,6-diimine; 2: L=NCMe;
3: L=PPh3) and [PydimCl2Ru(L–L)RuCl2Pydim] (4: L–L=pyrazine; 5: L–L=4,4’-bipyridine) have been studied in nitrogen atmo-
sphere using TG/DTG and DTA techniques. The decompositions of complexes occur in stepwise. The values of activation energy,
Ea, and reaction order, n of the thermal decomposition were calculated by means of several methods such as Coats–Redfern (CR),
MacCallum–Tanner (MT), Horowitz–Metzger (HM), van Krevelen (vK), Madhusudanan-Krishnan–Ninan (MKN) and
Wanjun–Yuwen–Hen–Cunxin (WYHC) based on the single heating rate. Most appropriate method was determined for each decom-
position step according to the least-squares linear regression.
Keywords: activation energy, ruthenium(II) complexes, thermal behaviour
Introduction
used to characterize materials from their thermal be-
havior standpoint. In addition, it enables to determine
apparent kinetic parameters of heterogeneous reac-
tions (the reaction order n, the activation energy E,
and the frequency factor A). Considerable attention is
paid to the kinetic parameters calculation from TG
curves. New calculation methods are still being pub-
lished [13, 14]. A number of papers are devoted to
comparing these methods [15] or to their critical as-
sessment [16]. Strezov [17] was investigated using
calorimetric technique the effect of heating rate on the
thermal properties of coal. Also, Kök [18, 19] was es-
timated the thermal analysis and kinetics of several
coal and oil shale samples by using the same method
based on the single heating rate. Takahashi [20] has
investigated the thermal stabilities of the Ni(II)-com-
plexes with 4-iodopyrazole. Kinetic analysis of ther-
mal decomposition of some Co-complexes of unsym-
metrical Vic-dioximes ligands have been studied by
Sahin et al. [21] using the various thermoanalytical
methods. The thermal stabilities of bis salicylidene
adipic dihydrazone derivatives were investigated by
Issa et al. [22] using thermal and elemental analytical
methods. Also, DoÈan et al. [23] have investigated
the thermal behavior, kinetic and thermodynamic pa-
rameters of imidazolinium and benzimidazolium bro-
mide salts with pentafluorobenzyl substitutents in a
nitrogen atmosphere with TG/DTG and DTA.
Complexes of transition metals with tridentate
triamine ligands are of considerable interest due to
their structural and material properties such as
terpyridine molecule (I) have been the subject of nu-
merous studies concerning analytical applications
[1, 2]. Various pyridine-2,6-diimines (II) (pydim)
which are analogs of terpyridine have also been stud-
ied as catalyst for many catalytic applications [3–9].
This family of catalysts has attracted great interest,
both in academia and in industry [10]. Although a lot
of pydim-based transition metal complexes have been
reported, examples of the related ruthenium com-
plexes are scarce. While their structural properties
have been examined extensively [7, 8, 11, 12], ther-
mal properties of these compounds are rare in the lit-
erature. There clearly remains much to investigate in
the area of thermal properties of Ru(II)-pydim com-
pounds. In materials science, thermal properties have
crucial importance.
N
N
R
N
N
R
N
N
R= aryl or alkyl
II
I
On the other hand, a similar study using isother-
mal function by various methods on rho-
The non-isothermal thermogravimetry (TG) with
a linear temperature growth is a method frequently
*
Author for correspondence: fatih.dogan@ege.edu.tr
1388–6150/$20.00
© 2007 Akadémiai Kiadó, Budapest
Akadémiai Kiadó, Budapest, Hungary
Springer, Dordrecht, The Netherlands

DO(AN et al.
dium(III)-pentamethylcyclopentadienyl and ruthe-
periments were performed twice for repeatability and
the results show good reproducibility with the smaller
variations in the kinetic parameters. a-Al2O3 is used
as a reference material.
nium(II)-arene derivatives has been reported [24, 25].
In this work, we described the thermal behaviors of
mono- and binuclear ruthenium(II)-pydim complexes
and determined the kinetic parameters such as the re-
action order, n and activation energy, Ea of the ther-
mal decomposition by means of CR, MC, HM, vK,
MKN and WYHC methods.
Results and discussion
Thermal stability
Pydims, the mono- and binuclear Ru(II)-pydim com-
plexes were studied by thermogravimetric analysis
from ambient temperature to 1000°C in nitrogen at-
mosphere. Typical TG/DTG and DTA curves for
compounds in the nitrogen atmosphere are present in
Figs 1–5. The initial and final temperatures and total
mass losses for each decomposition step in the ther-
mal decomposition of complexes are given Table 1,
together with temperatures of greatest rate of decom-
position (DTGmax), evolved moiety and the theoretical
percentage mass losses.
Experimental
All compounds have been described elsewhere
[26, 27]. Ru(II)-pydim complexes were synthesized
by the following general method (Scheme 1): an
ethanolic solution (15 mL) of 1.16 Eq. of the respec-
tive ligand (1 mmol) was mixed with [RuCl2(p-cy-
mene)]2 (306 mg; 0.5 mmol). The reaction mixture
was refluxed for 10 h. The resulting solution was
cooled to room temperature and added L (2:
L=NCMe; 3: L=PPh3) or L–L (4: L–L=pyrazine; 5:
L–L=4,4’-bipyridine). The mixture was heated under
reflux for further 2 h. The volatiles were removed.
The residue was dissolved in CH2Cl2 (10 mL) and was
precipitated by addition of ether (30 mL).
Pydim ligands
From TG curves (Fig. 1), 1a–d exhibited one step de-
composition process. Also, exothermic thermal effect
at 143, 178, 155 and 190°C in DTA profiles corre-
spond to the melting point of 1a, b, c and d ligands, re-
spectively. The reaction orders and activation energies
for 1a–d pydim-ligands were found to be 1.90 and
132.96 kJ mol–1, 1.30 and 107.33 kJ mol–1, 0.4 and
Cl
Cl
Ru Ru
N
1
+
Ar
N
N
Ar
Cl
Cl
1. EtOH, 78 °C
2. L or L-L
N
N
N
N
100-
80-
60-
40-
20-
0-
L-L=
L-L=
L=CH CN
3
L= PPh
3
N
N
N
Cl
Ar N Ru N Ar
N
Cl
Cl
Cl
Ar N Ru
Cl
N
Ar Ar N Ru
Cl
N
Ar
Ru
Ar N
Cl
N Ar
Cl
N
NCCH
PPh
3
N
N
3
2
3
Cl
Ru
N
Ar N
Cl
N Ar
N
Cl
Ru
N
Ar N
Cl
N Ar
b
d
N
a
c
N
Ar =
4
5
Scheme 1 Pydims and Ru(II)-pydim complexes studied by
thermogravimetric methods
Apparatus
The DTA and TG curves were obtained with
TG-DTA Perkin-Elmer Diamond system apparatus.
The measurements were performed by using a dy-
namic nitrogen atmosphere at a flow rate of
200 mL min–1 up to 1000°C. The heating rate was
10°C min–1 and the sample sizes ranged in mass from
8 to 10 mg contained in platinum crucible. All the ex-
Temperature/°C
Fig. 1 TG/DTG and DTA curves of pydim ligands
944
J. Therm. Anal. Cal., 91, 2008

RUTHENIUM(II) COMPLEXES CONTAINING PYRIDINE-2,6-DIIMINES
Table 1 TG/DTG and DTA data for the binuclear and mononuclear Ru(II)-pydim complexes
DTAmax
°C
/
DTGmax
°C
/
Temperature
range/°C
Mass loss/%,
found (calc.)
Complexes Step
DTA
exo
Assignment
1a
1b
1c
1d
2a
I
178
333
220
310
301
275–362
184–261
227–316
198–315
85.1 (–)
81.8 (–)
98.2 (–)
residue
>362
143
I
exo
residue
>261
I
155,310
>316
exo, exo
residue
I
190,314
>315
endo, endo 99.8 (–)
residue
I
127
272
427
661
53–188
6.6 (6.5)
NCMe
2NMe2
1/2Ph
1/2Ph
II
261
416
661
>783
188–384
384–570
592–783
exo
exo
exo
14.3 (14.4)
13.0 (12.4)
13.3 (12.4)
52.8 (54.3)
5.80 (5.1)
IIIa
IIIb
residue
2b
I
55
44–140
NCMe
2NEt2
II
220
390
565
805
140–340
340–520
546–685
715–878
19.3 (20.6)
12.8 (12.5)
13.4 (12.5)
10.2 (11.4)
38.2 (37.9)
4.76 (4.75)
6.54 (5.81)
6.84 (5.81)
19.0 (19.5)
62.4 (64.1)
6.60 (6.80)
10.2 (11.9)
17.2 (19.9)
65.3 (68.4)
29.3 (31.4)
11.2 (10.5)
59.0 (58.1)
36.4 (37.5)
12.8 (12.0)
48.7 (50.5)
21.5 (20.7)
78.3 (79.3)
18.5 (19.5)
19.2 (19.5)
62.0 (61.0)
39.0 (39.1)
59.2 (60.9)
44.2 (44.5)
10.7 (10.0)
9.36 (9.7)
IIIa
400
exo
2PhCH3
2PhCH3
1/2Cl2
IIIb
IV
residue
>878
2c
I
32
35–63
NCMe
1/2Cl2
II
169
277
424
63–191
191–313
342–545
III
exo
1/2Cl2
IV
424
C6H2Me3
residue
>545
2d
I
141
278
410
55–216
NCMe
Cl2
II
216–299
299–552
III
404
exo
exo
4C6H3MeEt
residue
>552
343
3a
4a
I
328
416
294–377
377–490
PPh3
II
2NMe2
residue
>490
I
406
609
229–590
590–792
4PhNMe2
C10N2H8
II
residue
>792
372
4b
4c
I
372
302–446
exo
exo
4NEt2
residue
>449
I
189
374
97–274
1/2C6H2Me3
1/2C6H2Me3
II
364
274–441
residue
>441
402
4d
5b
I
371
331–440
exo
exo
4C6H3MeEt
residue
>440
409
I
423
611
775
282–446
497–705
719–888
4PhCH3NEt2
C10N2H8
2Cl2
II
III
residue
>888
37.3 (35.8)
J. Therm. Anal. Cal., 91, 2008
945

DO(AN et al.
Table 1 Continues
DTAmax
°C
/
DTGmax
°C
/
Temperature
Mass loss/%,
found (calc.)
Complexes Step
DTA
Assignment
range/°C
5c
5d
I
253
395
>481
381
259
384
172–296
296–481
exo
exo
19.7 (18.0)
18.2 (18.0)
63.2 (64.0)
34.9 (36.7)
11.7 (12.0)
52.7 (51.3)
1/2C6H2Me3
1/2C6H2Me3
II
residue
I
366
603
149–535
545–779
exo
exo
4C6H3MeEt
C10N2H8
II
residue
>779
105.1 kJ mol–1 according to MC method, and 0.3 and
89.10 kJ mol–1 according to HM method, respectively.
action order and activation energies for second and
third decomposition steps were 1.30, 69.80 kJ mol–1
according to MC method and 1.50, 102.10 kJ mol–1
according to vK method, respectively. In the fourth
step, a mass loss of 19.00% with the order of 1.60 and
62.70 kJ mol–1 activation energy involved the elimi-
nation of 2,4,6-Me3C6H2 on the pydim ligand in tem-
perature range 342–545°C. The 2d is more stable than
2c and decomposes at 55, 231, 308°C, respectively, to
give NCMe, 2xCl and 2-Me,6-EtC6H3. The first step
was order of 1.0 with 17.30 kJ mol–1 activation energy
according to WHYC method. The second step was or-
der of 0.6 with 96.70 kJ mol–1 activation energy ac-
cording to HM method and the third step was order of
1.0 with activation energy of 75.50 kJ mol–1 accord-
ing to WHYC method.
Ru(II)-pydim complexes
The decomposition processes of Ru(II)-pydim com-
plexes are similar for same type complexes. However
the thermal decomposition pattern of each complex
shows a different decomposition pattern due to the
different pydim ligand.
Type 2 complexes
From the TG curve for complex 2a (Fig. 2), it appears
that the sample decomposes in four stages over the
temperature range 53–783°C. The first decomposition
occurs between 53 and 188°C with a mass loss 6.6%
in mass due to the loss of NCMe ligand. This step re-
quired an activation energy of 35.29 kJ mol–1 with the
order of 1.4 according to WHYC method. In the sec-
ond decomposition step, a mass loss of 14.3% with
the order of 1.30 and 46.26 kJ mol–1 activation energy
according to MC involved the elimination of
4-NMe2C6H4 on the pydim ligand in temperature
range 195-384°C. In third decomposition step
(390–570°C) and fourth decomposition step
(592–783°C) 4-NMe2C6H4 on the pydim ligand were
evolved with mass losses of 13.0 and 13.3%, respec-
tively. 2b is less stable than 2a and decompose at 44,
167, 350, 546 and 715°C, respectively, to give
NCMe, 2-Me-4-NEt2C6H4, 2-Me-4-NEt2C6H4 and 2 x
Cl from the 2b. The reaction order and activation en-
ergies for the first and second decomposition steps of
2b were found to be 2.70 and 99.96 kJ mol–1, and 0.4
and 37.57 kJ mol–1, respectively according to MC
method. From the TG curve for 2c (Fig. 2), it appears
that the sample decomposes in four stages over the
temperature range 35–545°C. The first decomposition
occurs between 35 and 63°C with a mass loss 4.76%
in mass due to the loss of NCMe ligand. This reaction
was order of 1.1 with 54.3 kJ mol–1 activation energy
according to MC method. In second (111–191°C) and
third steps (222–313°C), 2xCl were evolved with
mass losses of 6.54 and 6.84%, respectively. The re-
From the DTA profile three exothermic peaks
for 2a are noted. The maximas of these peaks, which
are due to the formation of intermediate, are found to
be 261, 416 and 661 K, respectively. One exothermic
100-
80-
60-
40-
20-
0-
Temperature/°C
Fig. 2 TG/DTG and DTA curves of type 2 complexes
946
J. Therm. Anal. Cal., 91, 2008

RUTHENIUM(II) COMPLEXES CONTAINING PYRIDINE-2,6-DIIMINES
-–3.525
0.07523-
–0.5-
100-
80-
60-
40-
20-
0-
-0
DTG
-10
-20
-30
-40
–1.0-
TG
–1.5-
–2.0-
–2.5-
–3.0-
DTA
–3.5-
-50
-53.24
–3.985-
0 100 200 300 400 500 600 700800 900 1000
Temperature/°C
Fig. 3 TG/DTG and DTA curves of type 3 complex
peak for 2b, 2c and 2d are noted. The maximas of
these peaks are found to be 400, 424 and 404°C, re-
spectively.
4a
4b
4c
4d
Type 3 complex
3a exhibited two-step decomposition processes. In the
first step PPh3 was eliminated in the temperature
range 294–367°C with a 29.30% mass loss. This reac-
tion was in an order of 0.3 with an activation energy
of 64.63 kJ mol–1 according to HM method. The sec-
ond decomposition step occurs in the temperature
range 396–490°C with 11.20% mass loss and corre-
sponds to the formation of 4-NMe2C6H4 on the pydim
ligand. Exothermic thermal effect at 343°C corre-
sponds to the formation of PPh3 which is decomposi-
tion product of complex.
Fig. 4 TG/DTG and DTA curves of type 4 complexes
is decomposition product of complex. 4d shows one de-
composition step between 331 and 440°C correspond-
ing to the elimination of 2-Me,6-EtC6H3 with a 39.0%
mass loss. The order and activation energies for this
steps were 1.4, 335.5 kJ mol–1 according to vK method.
From the DTA profile one exothermic peak for 4b and d
are noted. The maximas of these peaks, which is due to
the formation of intermediate, are found to be 372 and
371°C, respectively.
Type 4 complexes
As seen in Fig. 4, the complex 4a is thermally stable up
to 229°C. The first decomposition step occurs in the
temperature range 229–573°C corresponding to the
elimination of 4-NMe2C6H4. This stage was in order of
1.2 with an activation energy of 40.91 kJ mol–1 accord-
ing to vK method. The next decomposition step occurs
in the temperature range 604–792°C and corresponding
to the formation of C10H8N2. Complex 4b shows one de-
composition step between 575 and 719 K corresponding
to the elimination of 2-Me,4-NEt2C6H4 on the pydim
ligand with a 21.5% mass loss. The order and activation
energy for this decomposition step were 1.0 and
86.85 kJ mol–1 according to WHYC method. 4c exhib-
ited two-step decomposition processes. In the first step
1/2 molecule 2,4,6-Me3C6H2 was eliminated in the tem-
perature range 97–274°C with 18.5% mass loss. This
step required 62.20 kJ mol–1 activation energy with the
order of 1.0 according to MC method. The second de-
composition step occurs in the temperature range
260–441°C with a 19.2% mass loss and corresponds to
the formation of 2,4,6-Me3C6H2. This step was order of
1.5 with 77.60 kJ mol–1 activation energy according to
vK method. Exothermic thermal effect at 364°C corre-
sponds to the formation of 2,4,6-Me3C6H2 moiety which
Type 5 complexes
5c is thermally stable up to 172°C (Fig. 5). The mass
loss at the first stage in the temperature range
172-286°C corresponds to the formation of
2,4,6-Me3C6H2 with the order of 0.7 and
103.4 kJ mol–1 activation energy according to MC
method. The next decomposition step occurs in the
temperature range 314–481°C and corresponds to the
formation of 2,4,6-Me3C6H2. 5d again involved two
types of decomposition which is similar to 5c.
Kinetic parameters
The six methods investigated in this paper are those
by CR, HM, vK, MC, MKN and WHYC.
• The Coats–Redfern method [28]
g(a )
éAR 2RT ù
(1-
E
æ ö
é
ù
ln
=ln
) -
(1)
ç
÷
RT
è ø
ê
ú
2
ê
ë
ú
û
bE
E
T
ë
û
J. Therm. Anal. Cal., 91, 2008
947

DO(AN et al.
Q=T -Tm
If the reaction order is 1, Tm is defined as the
temperature at which (1–a)m=1/e=0.368 and the final
expression is:
Eq
lnlng(a )=
2
RTm
If the reaction order is unknown, Tm is defined
for the maximum heating rate.
When Q=0, (1–a)=(1–a)m and (1–a)m=n1/1–n and
2
ARTm
E
Eq
lng(a )=ln
-
+
(6)
2
RTm
bE
RTm
A plot of lng(a) vs. Q can yield activation en-
In the equations above, a, g(a), b, Tm, E, A, R are
ergy.
the degree of reaction, integral function of conver-
sion, heating rate, DTG peak temperature, activation
energy (kJ mol–1), pre-exponential factor (min–1) and
gas constant (8.314 J mol–1 K–1), respectively. The ki-
netic parameters were calculated from the linear plots
of the left-hand side of kinetic equations (Eqs (1)–(4)
and (6)) vs. 1/T , for van Krevelen equation (Eq. (5))
the left-hand side is plotted vs. lnT. The values E and
A were calculated from the slope and intercept of the
straight lines, respectively.
Fig. 5 TG/DTG and DTA curves of type 5 complexes
• The Madhusudanan–Krishnan–Ninan method [29]
g(a )
æ AE ö
=ln +3.7678-
ç
ç
é
ù
ln
÷
÷
1.9206
ê
ë
ú
û
bR
T
In this study, the several methods based on a sin-
gle heating rate were used in the thermal analysis. The
linearization curves of each decomposition step of the
complexes were obtained using the least squares
method. From the TG/DTG and DTA curves, the re-
action order, n and activation energy, Ea of the de-
composition have been elucidated by the first one of
the methods mentioned above which has higher linear
regression coefficient [34] obtained for Arrhenius
plots. The kinetic and thermodynamic parameters re-
lated to the ligands and complexes were calculated by
the software developed in our laboratory using PHP
Web programming language [35].
è
ø
E
æ
ö
÷
-1.9206lnE-0.12040
(2)
(3)
(4)
ç
T
è
ø
• The MacCallum–Tanner method [30]
æ AE ö
ç
0.4351
logg(a )=log
-0.4828E
÷
÷
–
ç
bR
è
ø
0.449+0.217E
10–3T
æ
-
ç
ö
÷
è
ø
• Wanjun–Yuwen–Hen–Cunxin method [31]
g(a )
é
= ln
AR
ù
+3.6350-1.8946lnE –
é
ù
ln
On the other hand, the value of correlation coef-
ficients of linearization curves of ruthenium com-
plexes are approximately 1.00 and values of reaction
orders are around 1.00 for complexes. It is very close
to zero for 1c and d ligands. The kinetic data obtained
by different methods agree with each other. The ther-
mal stabilities of ligands increase in the following or-
der: 1b<1d<1c<1a. This result shows that 1a are more
stable than others. It was found that the thermal stabil-
ities and activation energies of the complexes for the
first decomposition stage follow the order
2c<2b<2a<2d<4c<5d<3a<4a<4b<1b<5c<1d<5b<1c
<1a<4d and E2d<E2a<E4a<E5d<E2c<E4c<E3a<E5b<E4b
<E1d<E2b<E5c<E1c<E1b<E1a<E4d, respectively. The
highest thermal stability and activation energy for the
ê
ú
û
1.8946
ê
ë
ú
û
bE
T
ë
E
æ
ö
÷
-1.0014
ç
RT
è
ø
• The van Krevelen method [32]
é
ê
ê
ê
ê
ù
Ea
ú
ú
ú
ú
A(0.368/Tm )RT
æ Ea
+ç
ö
+1÷lnT (5)
÷
m
lng(a )=ln
ç
è
RTm
æ Ea
bç
ö
+1÷
ø
ç
÷
ø
RTm
ê
ë
ú
û
è
• Horowitz–Metzger
Horowitz–Metzger method introduced a character-
istic temperature Tm and a parameter Q such that
method
[33].
The
948
J. Therm. Anal. Cal., 91, 2008

RUTHENIUM(II) COMPLEXES CONTAINING PYRIDINE-2,6-DIIMINES
12 K. Ertekin, S. Kocak, O. M. Sabih, S. Aycan and
first decomposition stage is displayed by the 4d com-
B. Cetinkaya, Talanta, 61 (2003) 573.
13 J. Madarasz, G. Pokol and S. Gal, J. Thermal Anal.,
42 (1994) 539.
plex. The stabilities of mononuclear complexes with
NCMe are very low and consequently, low energy is
required for their decomposition. Generally,
dinuclear complexes required lower energy than
mononuclear complexes to decompose in the first
step. 1d ligand increases the stability in mononuclear
complexes while it decreases that in binuclear ones.
Thermal stability increases from mononuclear com-
plexes to dinuclear ones. Activation energies exhibit a
trend of increases for multistep decomposition such
as 2a, 2b, 3a, 5b, 4c, 4a, 5d.
14 I. L. Lapides, J. Thermal Anal., 50 (1997) 269.
15 F. Carrasco, Thermochim. Acta, 213 (1993) 115.
16 J. Zsako, J. Thermal Anal., 46 (1996) 1854.
17 V. Strezov, J. A. Lucas, T. J. Evans and L. Strezov,
J. Therm. Anal. Cal., 78 (2004) 385.
18 M. V. Kök and E. Okutan, J. Thermal Anal.,
46 (1996) 1657.
19 M. V. Kök, J. Therm. Anal. Cal., 79 (2005) 175.
20 P. M. Takahashi, R. C. G. Frem, A. V. G. Netto,
A. E. Mauro and J. R. Matos, J. Therm. Anal. Cal.,
87 (2007) 797.
21 O. Ÿahin, E. Taê and H. Dolas, J. Therm. Anal. Cal.,
89 (2007) 123.
Conclusions
22 R. M. Issa, S. A. Amer, I. A. Mansour and
A. I. Abel-Monsef, J. Therm. Anal. Cal., 87 (2007) 691.
23 F. DoÈan, S. Gülcemal, M. Yürekli and B. Cetinkaya,
J. Therm. Anal. Cal., 91 (2008) 395.
In conclusion, i) Pydim Ligands are more stable than
their corresponding Ru(II) complexes except for 4d and
5b; ii) the binuclear complexes appear to be more stable
than mononuclear analogs; iii) structurally similar com-
plexes have similar thermal decomposition curves;
iv) the intermediates of different steps are not stable and
decompose immediately after their formation.
24 G. S´nchez, I. Solano, M. D. Santana, G. García, J. G´lvez
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25 G. S´nchez, J. García, J. Pérez, G. García, G. López and
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26 N. Ozdemir, M. Dincer, O. Dayan and B. Cetinkaya, Acta
Cryst., C63 (2007) m77.
27 O. Dayan and B. Cetinkaya, J. Mol. Cat. A., 2007,
in press.
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