Dimeric and polymeric silver(I) saccharinato complexes of two bis(pyridine) ligands: Synthesis, structural, spectroscopic, fluorescent and thermal properties

Article abstract of DOI:10.1016/j.poly.2010.01.019

The reaction of silver(I) with 1,2-bis[1-(pyridin-2-yl)ethylidene]hydrazine (bpeh) and N,N-bis(pyridin-2-ylmethyl)amine (bpma) in the presence of Na(sac) (sac = saccharinate) yielded [Ag₂(sac)₂(bpeh)] (1) and [Ag(sac)(bpma)]_n (2) with conformational chirality. Both complexes have been characterized by elemental analysis, IR, thermal analysis and X-ray single crystal diffraction. Complex 1 displays a binuclear composition, in which each silver(I) ion is bound to one monodentate sac ligand and one of the bidentate pyridylimino groups of the bpeh ligand in a distorted trigonal coordination geometry. Complex 2 is a one-dimensional helical polymer, in which silver(I) centers are bridged by tridentate bpma ligands, and each silver(I) ion is coordinated in a distorted tetrahedral geometry by one monodentate sac ligand, a bidentate pyridylamine group of one bpma ligand, and a py group of another bpma ligand. Weak intermolecular C-H?O hydrogen bonds and C-H?π interactions lead to assembly of 1 and 2 into three-dimensional supramolecular frameworks. Spectral and thermal analysis data for 1 and 2 are in agreement with the crystal structures. In addition, both complexes in the solid state display intraligand π-π* fluorescence.

Full text of DOI:10.1016/j.poly.2010.01.019

Polyhedron 29 (2010) 1437–1442
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Dimeric and polymeric silver(I) saccharinato complexes of two bis(pyridine)
ligands: Synthesis, structural, spectroscopic, fluorescent and thermal properties
b
Emel Guney a, Veysel T. Yilmaz a, , Orhan Buyukgungor
*
a Department of Chemistry, Faculty of Arts and Sciences, Uludag University, 16059 Bursa, Turkey
b Department of Physics, Faculty of Arts and Sciences, Ondokuz Mayis University, 55139 Samsun, Turkey
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction of silver(I) with 1,2-bis[1-(pyridin-2-yl)ethylidene]hydrazine (bpeh) and N,N-bis(pyridin-2-
ylmethyl)amine (bpma) in the presence of Na(sac) (sac = saccharinate) yielded [Ag2(sac)2(bpeh)] (1) and
[Ag(sac)(bpma)]n (2) with conformational chirality. Both complexes have been characterized by elemen-
tal analysis, IR, thermal analysis and X-ray single crystal diffraction. Complex 1 displays a binuclear com-
position, in which each silver(I) ion is bound to one monodentate sac ligand and one of the bidentate
pyridylimino groups of the bpeh ligand in a distorted trigonal coordination geometry. Complex 2 is a
one-dimensional helical polymer, in which silver(I) centers are bridged by tridentate bpma ligands,
and each silver(I) ion is coordinated in a distorted tetrahedral geometry by one monodentate sac ligand,
a bidentate pyridylamine group of one bpma ligand, and a py group of another bpma ligand. Weak inter-
Received 16 November 2009
Accepted 13 January 2010
Available online 18 January 2010
Keywords:
Saccharinate
1,2-Bis[1-(pyridin-2-
yl)ethylidene]hydrazine
N,N-bis(pyridin-2-ylmethyl)amine
Chirality
Coordination polymer
Silver(I)
molecular C–HÁ Á ÁO hydrogen bonds and C–HÁ Á Á
p interactions lead to assembly of 1 and 2 into three-
dimensional supramolecular frameworks. Spectral and thermal analysis data for 1 and 2 are in agreement
with the crystal structures. In addition, both complexes in the solid state display intraligand
fluorescence.
p–p*
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
studies. The crystal structures of the complexes were determined
by X-ray diffraction. Complex 1 is obtained in a dinuclear form,
while complex 2 adopts a one-dimensional helical zig-zag poly-
meric chain. Some solid state properties of the complexes such
as thermal decomposition and photoluminescence were also
studied.
Saccharin (sacH) is a well-known and the most widely used
sweetening agent. The imin hydrogen of sacH is readily deproto-
nated in solutions to give the corresponding monoanion sac. Fol-
lowing the discovery of the coordination ability of the sac anion
towards biologically important metal ions, different metal com-
plexes of sac in the presence of various co-ligands have been exten-
sively studied. Earlier work in this field has been summarized in a
recent review [1]. The sac ligand has several potential donor atoms
such as an imino nitrogen, a carbonyl and two sulfonyl oxygen
atoms. It usually coordinates in a monodentate fashion through
the negatively charged N atoms and also acts as a bi- or tridentate
bridging ligand, forming complexes from mononuclear to poly-
meric chains [1].
N
CH3
N
H
N
N
O
N
N
S
O
N
H3C
N
O
bpma
sac
bpeh
As continuation of our interest in the synthesis and properties
of metal complexes of the sac ligand, we synthesized two new sil-
ver(I) complexes of sac with 1,2-bis[1-(pyridin-2-yl)ethyli-
dene]hydrazine (bpeh) and N,N-bis(pyridin-2-ylmethyl)amine
(bpma, alternatively named bis(2-picolyl)amine) as co-ligands,
namely [Ag2(sac)2(bpeh)] (1) and [Ag(sac)(bpma)]n (2). Both
complexes have been characterized by elemental analyses and IR
2. Experimental
2.1. Materials and measurements
1,2-Bis[1-(pyridin-2-yl)ethylidene]hydrazine (bpeh) were pre-
pared according to the reported method by the reaction of hydra-
zine hydrate with 2-acetylpyridine [2]. Other chemicals were
purchased and used as supplied. Elemental analyses for C, H, and
N were performed using a Costech elemental analyser. IR spectra
were recorded with a Thermo Nicolet 6700 FTIR spectrophotometer
* Corresponding author.
E-mail address: vtyilmaz@uludag.edu.tr (V.T. Yilmaz).
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.01.019

1438
E. Guney et al. / Polyhedron 29 (2010) 1437–1442
Table 1
Crystallographic data and structure refinement for 1 and 2.
1
2
Formula
Molecular weight
T (K)
C28H22Ag2N6O6S2
818.38
296
C19H17AgN4O3S
489.30
296
Wavelength (Å)
Crystal system
Space group
0.71073
orthorhombic
Aba2
0.71073
orthorhombic
P212121
Unit cell dimensions
a (Å)
b (Å)
14.4445(11)
25.6574(14)
7.7734(5)
2880.9(3)
4
7.7968(3)
9.8671(5)
24.8118(12)
1908.82(15)
4
c (Å)
Volume (Å3)
Z
Calculated density (g/cm3)
1.887
1.560
1.708
1.194
l
(mmÀ1
)
F(0 0 0)
1624
784
Crystal size (mm3)
h Range (°)
0.36 Â 0.23 Â 0.03
1.59–26.49
À9/16; À31/32; À9/5
5537
2375 [Rint = 0.0271]
1981
0.58 Â 0.35 Â 0.11
1.64–26.50
À9/7; À11/12; À30/31
7132
3918 [Rint = 0.0404]
3461
Index ranges (h, k, l)
Reflections collected
Independent reflections
Reflections observed (>2
Absorption correction
Data/parameters
r
)
numerical
2375/200
numerical
3918/253
Flack parameter
0.39(4)
0.977
À0.03(3)
Goodness-of-fit on (GOF) F2
1.056
Final R indices [I > 2
r(I)]
R1 = 0.0321, wR2 = 0.0750
1.100 and À0.423
R1 = 0.0316, wR2 = 0.0747
0.472 and À0.659
Largest difference in peak and hole (e ÅÀ3
)
with samples as KBr pellets in the 4000–400 cmÀ1 range. Excitation
and emission spectra were recorded at room temperature with a
Varian Cary Eclipse spectrophotometer equipped with a Xe pulse
lamp of 75 kW. Thermal analysis curves (TGA and DTA) were ob-
tained using a Seiko Exstar 6200 thermal analyzer in a dynamic
air atmosphere with a heating rate of 10 °C minÀ1 and a sample size
of ca. 10 mg.
Mo Ka radiation (k = 0.71073 Å). The structures were solved by di-
rect methods and refined on F2 with the SHELX-97 program [3]. All
non-hydrogen atoms were found from the difference Fourier map
and refined anisotropically. All hydrogen atoms were included
using a riding model. The details of data collection, refinement
and crystallographic data are summarized in Table 1.
3. Results and discussion
2.2. Synthesis of the silver(I) complexes
3.1. Synthesis and characterization
The addition of Na(sac)Á2H2O (1 mmol, 0.24 g) dissolved in 5 ml
water to a solution of AgNO3 (0.17 g, 1 mmol) in 5 ml water re-
sulted in a white suspension, which is dissolved by the addition
of MeCN (5 ml). Then, a solution 1,2-bis[1-(pyridin-2-yl)ethyli-
dene]hydrazine (bpeh) (0.5 mmol, 0.12 g) in 5 ml MeOH was added
dropwise to the clear solution with stirring. Then, a pale yellow
suspension was formed and clarified by addition of 10 ml MeCN
and 10 ml isopropanol. The final solution was kept in darkness at
room temperature. Pale yellow crystals of [Ag2(sac)2(bpeh)] (1)
were obtained within a week. Yield 87.0%. M.p. 218–223 °C (with
decomp.). Anal. Calc. for C28H22Ag2N6O6S2: C, 41.1; H, 2.7; N,
10.3. Found: C, 40.9; H, 2.9; N, 10.5%. IR (Solid KBr pellet):
Complexes 1 and 2 were synthesized by the direct reaction of
Na(sac) with AgNO3 in the aqueous solution in the presence of
the bpeh and bpma ligands. They were obtained in high yields
(over 85%). Both complexes are air stable and soluble in MeCN
and a mixture of water, PriOH and MeCN (1:1.1).
Selected FTIR spectroscopic data for 1 and 2 are listed in Table 2.
The azine group (C@N) of bpeh and the NH group of bpma have
prominent IR bands centered at 1684 and 3281 cmÀ1. The CN band
of bpeh seems to couple with the m(C@O) band of sac, leading to a
most intense band centered at 1626 cmÀ1. The sac moiety gives
characteristic IR bands due to the absorption of the carbonyl and
sulfonyl groups. The carbonyl O atom of the sac ligand does not
m
(cmÀ1
) 3052vw, 3003vw, 2952vw, 1652vs, 1626vs, 1584s,
1462m, 1430w, 1360w, 1340w, 1271vs, 1252vs, 1168vs, 1154vs,
1115sh, 1054m, 964m, 952m, 772m, 743m, 670m, 637w, 605m,
543m.
[Ag(sac)(bpma)]n (2) was synthesized in a similar way, by
replacing the ligand bpeh with N,N-bis(pyridin-2-ylmethyl)amine
(bpma). Yield 90.0%. M.p. 189–192 °C. Anal. Calc. for C19H17Ag-
N4O3S (%): C, 46.6; H, 3.5; N, 11.5. Found: C, 46.3 H, 3.6; N,
11.7%. IR (cmÀ1): 3281m, 3060vw, 2923vw, 2848vw, 1659sh,
1626vs, 1592s, 1477w, 1435w, 1336w, 1259vs, 1152vs, 1120sh,
1052w, 1005vw, 953s, 850w, 761s, 677w, 636w, 604m, 543m.
Table 2
Selected FTIR spectral dataa for 1 and 2.
Assignment
1
2
m
m
m
m
m
m
m
m
(NH)
(CH)
(CO)
(CC)
s(CNS)
as(SO2)
s(SO2)
as(CNS)
3281m
3052vw, 3003vw, 2952vw
1652vs, 1626vsb
1584vs, 1462m
1340w
1271vs
1154vs
3060vw, 2923vw, 2848vw
1659sh, 1626vs
1592s, 1477w
1336w
1259vs
1152vs
964m
953s
2.3. X-ray crystallography
a
Frequencies in cmÀ1
. b = broad; m = medium; w = weak; vw = very weak;
vs = very strong; s = strong.
The intensity data of the complexes 1 and 2 were collected
using a STOE IPDS 2 diffractometer with graphite-monochromated
b
Coupled with the m(C@N) vibration of bpeh.

E. Guney et al. / Polyhedron 29 (2010) 1437–1442
1439
Table 3
participate in metal bonding and produce two sharp bands at
around 1650 and 1625 cmÀ1. The asymmetric (
as) and symmetric
Selected bond lengths [Å] and angles [°] for 1 and 2.
m
(ms) stretchings of the SO2 group in the spectra of 1 and 2 are ob-
1
2
served as two strong IR bands at ca. 1265 and 1150 cmÀ1, respec-
tively. Moreover, the ms and mas stretching modes of the CNS
Ag1–N1
Ag1–N2
Ag1–N3
Ag1–N4
N1–Ag1–N2
N1–Ag1–N3
N1–Ag1–N4
N2–Ag1–N3
N2–Ag1–N4
N3–Ag1–N4
2.134(4)
2.291(4)
2.324(4)
2.303(3)
2.396(3)
2.360(3)
2.279(3)
109.36(13)
120.31(12)
98.06(12)
73.20(12)
130.37(11)
126.14(12)
fragment of the sac ligands appear at 1340 and 955 cmÀ1
respectively.
,
136.69(15)
150.02(14)
70.52(14)
3.2. Crystal structures
A view of the molecular structure of complex 1 is shown in
Fig. 1, together with the atom numbering scheme. Selected bond
distances and angles are listed in Table 3. Complex 1 is a binuclear
silver(I) complex consisting of two sac and one bpeh ligand. The
bpeh ligand acts as a bis(bidentate) (tetradentate in total) ligand
coordinating two silver(I) ions through both pyridyimine groups.
The distorted trigonal coordination sphere around each silver(I)
ion is completed by a N-bonded sac ligand. The bpeh ligand is flex-
ible, twisting about the central N–N bond. Therefore, it exhibits
several stereoisomers such as E–E (trans, trans), Z–E (cis, trans),
and Z–Z (cis, cis) [4]. In 1, the dihedral angle between the py rings
of bhep is 54.65(13)° and the ligand adopts the E–E arrangement.
On the other hand, it has been stated that binuclear composition
of 1 is consistent with the E–E isomer of the ligand [5]. The bpeh
ligand is known to generate helical silver(I) complexes with non-
coordinating counter-ions, formulated as {[Ag2(bpeh)2]X2}n
Table 4
Non-conventional hydrogen bonds in 1 and 2.
D–HÁ Á ÁA
D–H (Å)
HÁ Á ÁA (Å)
DÁ Á ÁA (Å)
D–HÁ Á ÁA (°)
1a
C2–H2Á Á ÁO2i
C14–H14BÁ Á ÁO3ii
C14–H14CÁ Á ÁO1iii
0.93
0.96
0.96
2.44
2.41
2.47
3.206(7)
3.160(8)
3.330(5)
140
134
149
2a,b
C5–H5Á Á ÁO3iv
C8–H8Á Á ÁO1v
C13–H13AÁ Á ÁO1vi
C2–H2Á Á ÁCg1vii
C9–H9Á Á ÁCg2viii
0.93
0.93
0.97
0.93
0.93
2.53
2.48
2.54
3.35
3.13
3.436(5)
3.151(6)
3.401(6)
3.064
163
129
148
134
162
3.081
a
Symmetry codes: (i) Àx + 2, Ày + 3/2, z À 1/2; (ii) Àx + 2, Ày + 1, z + 1; (iii) x + 1/
À
(X = ClO4À, BF4 and NO3À) [2]. In the present case, the ligand
2, Ày + 1, z + 1/2; (iv) x À 1, y, z; (v) x + 1, y, z; (vi) x + 1/2, Ày + 1/2, Àz + 1; (vii)
Àx + 1, y + 1/2, Àz + 1/2; (viii) x À 1/2, Ày + 5/2, Àz.
forms a binuclear complex of 1. It has been explained that upon
coordination as a bridge, the freedom of the ligand to rotate about
the N–N bond is restrained and as a result, the bpeh ligand can be
locked in a twisted chiral conformation [6]. Thus, the binuclear
b
Cg1 and Cg2 are the centroids of the pyridine rings (N4, C14–C18) and (N2, C8–
C12), respectively.
complex
1 is also chiral. Moreover, the Flack parameter of
molecules are connected by weak C–HÁ Á ÁO hydrogen bonds into a
three-dimensional network (Table 4).
0.39(4) indicates that the structure is racemically twinned, con-
taining a partial mix of enantiomers. The Ag–N(bpeh) bond dis-
tances are similar to those of the complexes of the same or
similar ligands [2,7], while the Ag–N(sac) bond distance of
2.134(4) Å is within the normal range observed in the reported
N-bonded sac complexes of silver(I) [8–15]. It is interesting to note
The asymmetric unit of complex 2 is shown in Fig. 2 and se-
lected bond lengths and angles are listed in Table 3. The structure
of 2 is chiral (P212121) and consists of one-dimensional helical
chains, in which silver(I) centers are bridged by the bpma ligands
as shown in Fig. 2. The bpma ligand acts as a tridentate ligand. Each
silver(I) ion is coordinated in a distorted tetrahedral geometry by a
that no obvious
p–p stacking interactions between the py rings of
bpeh in the adjacent molecules are present. Thus, the dimeric
Fig. 1. A view of the binuclear structure of 1. C–H hydrogen atoms were omitted for clarity.

1440
E. Guney et al. / Polyhedron 29 (2010) 1437–1442
Fig. 2. Coordination environment around silver(I) and views of the one-dimensional chain in 2. C–H hydrogen atoms were omitted for clarity.
monodentate (N) sac ligand, a bidentate (N,N) pyridylamine group
of a bpma ligand and a py N atom of the symmetrically equivalent
bpma ligand. As expected, the bpma ligand with the two py groups
is essentially planar, possessing C2 symmetry. Upon coordination,
it is twisted around the amine N atom with torsion angles C12–
C13–N3–C19 of 75.30(11)° and C18–C19–N3–C13 of 61.65(12)°.
Obviously, the twist of the ligand plays a crucial role in the gener-
ation of the molecular chirality [16–18]. The bpma ligand usually
acts as a tripodal ligand [19–23], and as in the present case, its
bridging behavior is rare. The Ag–N(bpma) bond distances are sim-
ilar to those found in the mononuclear complexes [Ag(bp-
ma)(PPh3)]ClO4 [21], [Ag(bpma)(P(o-tol)3)]ClO4 [20], and [Ag
(bpma)(P(o-tol)3)]NO3 [23], whereas the Ag–N(sac) bond distance
in complex 2 is slightly longer than that of complex 1. The bpma
ligand has an amine hydrogen atom, which is not involved in
hydrogen bonding because of geometrical constraints. Therefore,
the one-dimensional chains running along the axis a are linked into
a three-dimensional network by weak C–HÁ Á ÁO hydrogen bonds
3.3. Photoluminescence
The photoluminescent spectra of the ligands and their com-
plexes have been measured at room temperature, and the emission
spectra of the solid complexes are presented in Fig. 3. Na(sac) is
emissive at 399 nm in the solid state when excited either at 275
or at 300 nm. Upon excitation at 385 nm, the emission spectrum
of the bpeh ligand displays two main bands at 438 and 529 nm.
Upon complexation, the emissions of complex 1 are not shifted
compared to the free ligand, except for the decreased intensity of
the band at 438 nm. Therefore, the metal-to-ligand charge transfer
(MLCT) or metal centered (MC) d ? s transitions are not possible
due to the lack of appreciable red shifts and furthermore, the
resemblance of the emission spectrum of 1 with that of bpeh indi-
cates that the fluorescence of 1 is due to the ligand-based
p–p*
intraligand transitions at the excited state. On the other hand,
the bpma ligand in the liquid form fluoresces at ca. 442 nm when
excited at 350 nm, while the solid complex 2 features a distinct
and broad emission band centered at 472 nm upon excitation at
and C–HÁ Á Áp interactions as listed in Table 4.

E. Guney et al. / Polyhedron 29 (2010) 1437–1442
1441
ligands due to overlapping of decomposition reactions, the total
mass loss (73.2%) at 577 °C agrees well with the calculated total
mass of both ligands (73.6%). On the other hand, the DTA curves
clearly indicate that an exothermic peak at 241 °C corresponds to
the removal of bpeh, while highly exothermic peaks at 510 and
577 °C are characteristic for the decomposition of the sac moiety
[26]. Complex 2 decomposes in two stages. The first stage in the
temperature range 220–456 °C corresponds to the exothermic re-
moval of the bpma ligand with a DTA peak at 288 °C (mass loss:
found 40.4%, calcd. 40.7%). The degradation of the sac ligand takes
place between 460 and 623 °C with a violently exothermic DTA
peak centered at 581 °C (mass loss: found 37.5%, calcd. 37.2%).
The decomposition of both complexes yields metallic silver as a
decomposition product.
4. Conclusions
Fig. 3. Emission spectra of complex 1 (upon excitation at 385 nm) and complex 2
(upon excitation at 359 nm) in solid state at room temperature.
In conclusion, the use of two flexible achiral bis(pyridine) li-
gands as sources of conformational chirality leads to the formation
of two chiral complexes [Ag2(sac)2(bpeh)] (1) and [Ag(sac)(bp-
ma)]n (2). Both complexes are characterized spectroscopically
and crystallographically. The chirality of the molecular units is in-
duced by the coordination of the ligands in a twisted chiral confor-
mation. Weak, but significant intermolecular C–HÁ Á ÁO hydrogen
bonds and C–HÁ Á Á
p interactions play very important role in the
construction of three-dimensional supramolecular frameworks.
Both complexes exhibit high thermal stabilities and are fluorescent
at room temperature.
5. Supplementary material
CCDC 752881 and 752882 contain the supplementary crystallo-
graphic data for 1 and 2. These data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
References
[1] E.J. Baran, V.T. Yilmaz, Coord. Chem. Rev. 250 (2006) 1980.
[2] G. Dong, H. Cheng, D. Chun-Ying, Q. Chun-Qi, M. Qing-Jin, New J. Chem. 26
(2002) 796.
[3] G.M. Sheldrick, Acta Crystallogr., A 64 (2008) 112.
[4] R. Karmakar, C.R. Choudhury, S.R. Batten, S. Mitra, J. Mol. Struct. 826 (2007) 75.
[5] C.J. O’Connor, R.J. Romananch, D.M. Robertson, E.E. Eduok, F.R. Fronczek, Inorg.
Chem. 22 (1983) 449.
Fig. 4. DTA and TG curves of 1 and 2.
[6] E.-Q. Gao, Y.-F. Yue, S.-Q. Bai, Z. He, C.-H. Yan, J. Am. Chem. Soc. 126 (2004)
1419.
[7] F. Chen-Jie, D. Chun-Ying, M. Hong, H. Cheng, M. Qing-Jin, L. Yong-Jiang, M. Yu-
Hua, W. Zhe-Ming, Organometallics 20 (2001) 2525.
[8] S. Hamamci, V.T. Yilmaz, W.T.A. Harrison, C. Thone, Solid State Sci. 7 (2005)
423.
[9] S. Hamamci, V.T. Yilmaz, W.T.A. Harrison, Struct. Chem. 16 (2005) 379.
[10] V.T. Yilmaz, S. Hamamci, C. Kazak, Z. Anorg. Allg. Chem. 631 (2005) 1961.
[11] V.T. Yilmaz, S. Hamamci, S. Gumus, O. Buyukgungor, J. Mol. Struct. 794 (2006)
142.
359 nm. The observed red-shift of the emission maximum in 2 is
probably due to a ligand-centered
p–p* process including signifi-
cant charge transfer character induced by the silver(I) ion.
Commonly silver(I) complexes are weakly emissive at low temper-
atures [24,25] and the present results show that complexes 1 and 2
exhibit photoluminescence at ambient temperatures and their
emissions are mainly originated from the co-ligands instead of sac.
[12] V.T. Yilmaz, S. Hamamci, O. Buyukgungor, Z. Naturforsch. 61b (2006) 189.
[13] S. Gumus, S. Hamamci, V.T. Yilmaz, C. Kazak, J. Mol. Struct. 828 (2007) 181.
[14] S. Hamamci, V.T. Yilmaz, S. Gumus, O. Buyukgungor, Z. Naturforsch. 63b
(2008) 139.
[15] S. Hamamci, V.T. Yilmaz, S. Gumus, O. Buyukgungor, Struct. Chem. 19 (2008)
123.
[16] Y.-T. Wang, G.-M. Tang, Y.-Q. Wei, T.-X. Qin, T.-D. Li, J.-B. Ling, X.-F. Long, Inorg.
Chem. Commun. 12 (2009) 1164.
[17] Y.-T. Wang, M.-L. Tong, H.-H. Fan, H.-Z. Wang, X.-M. Chen, J. Chem. Soc., Dalton
Trans. (2005) 424.
3.4. Thermal decomposition
In order to characterize the complexes more fully in terms of
thermal stability, their thermal behaviors were studied by TG
and DTA at the atmosphere of air in the temperature range 25–
900 °C. The TG and DTA curves are illustrated in Fig. 4. Both com-
plexes are stable up to melting points (DTA peaks centered at
220 °C for 1 and 190 °C for 2). After melting, complex 1 displays
two-step decomposition between 195–361 °C and 362–577 °C
with mass losses 43.4% and 29.8%. Although the mass loss in each
stage is not consistent with individual mass of the bpeh and sac
[18] Y.-T. Wang, H.-H. Fan, H.-Z. Wang, X.-M. Chen, Inorg. Chem. 44 (2005) 4148.
[19] Z.D. Bugarcic, G. Liehr, R. van Eldik, J. Chem. Soc., Dalton Trans. (2002) 951.
[20] B. Pitteri, G. Annibale, G. Marangoni, V. Bertolasi, V. Ferretti, Polyhedron 21
(2002) 2283.
[21] K.-Y. Choi, B.-R. Kim, J. Ko, J. Chem. Crystallogr. 37 (2007) 847.

1442
E. Guney et al. / Polyhedron 29 (2010) 1437–1442
[22] Effendy, F. Marchetti, C. Pettinari, B.W. Skelton, A.H. White, Inorg. Chim. Acta
360 (2007) 1424.
[23] C. Di Nicola, Effendy, F. Marchetti, C. Pettinari, B.W. Skelton, A.H. White, Inorg.
Chim. Acta 360 (2007) 1433.
[24] D.H. Pierre, F. Daniel, Coord. Chem. Rev. 171 (1998) 351.
[25] M.L. Tong, X.M. Chen, B.H. Ye, L.N. Ji, Angew. Chem., Int. Ed. 38 (1999)
2237.
[26] H. Icbudak, V.T. Yilmaz, H. Olmez, J. Therm. Anal. 53 (1998) 843.