Synthesis, characterization and thermal stability of complex cis-[Co(bipy)2(CN)2] and its interaction with NO 2 Gas1

Article abstract of DOI:10.1134/S0036023611030181

cis-[Co(bipy)₂(CN)₂] complex was successfully prepared from the reaction of [Co(CN)₂] with 2,2'- bipyridine in ethanol 96%. The product of complex synthesized was light brown crystal with percent yield of 75.86%. The IR spectrum of this complex showed strong characteristics vibration band at 1471.9 and 1442.75 cm^-1 for C=N stretching, 1664.57 cm^-1 for C=C aromatic, 1600.9 cm^-1 1 for HC=CH aromatic, 653.87 cm^-1 for pyridine ring on 2,2'-bipyridine ligand, 3109.25 and 3080.32 cm^-1 for C-H of aromatic ring. The thermogram of DTA-TG analysis showed 4 endothermic peaks at temperature of 53.4, 323.2, 444.2, and 526.4°C, where the bond breaking of the complex occurred at different temperatures. The result of moment magnet measurement of the complex showed that it was a high spin complex with moment magnet value of 3.68 BM, so it is a paramagnetic complex. Pleiades Publishing, Ltd., 2011.

Full text of DOI:10.1134/S0036023611030181

ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2011, Vol. 56, No. 3, pp. 418–421. © Pleiades Publishing, Ltd., 2011.
PHYSICAL METHODS
OF INVESTIGATION
Synthesis, Characterization and Thermal Stability
1
of Complex cisꢀ[Co(bipy) (CN) ] and Its Interaction with NO Gas
2
2
2
Mita Rilyanti and Sutopo Hadi
Department of Chemistry, University of Lampung Bandar Lampung 35145 Indonesia
eꢀmail: mita_rilyanti@yahoo.com; sutopohadi@unila.ac.id
Received October 8, 2009
Abstract
bipyridine in ethanol 96%. The product of complex synthesized was light brown crystal with percent yield of
5.86%. The IR spectrum of this complex showed strong characteristics vibration band at 1471.9 and
—cisꢀ[Co(bipy) (CN) ] complex was successfully prepared from the reaction of [Co(CN)2] with 2,2'ꢀ
2 2
7
–1
–1
–1
1
442.75 cm for C=N stretching, 1664.57 cm for C=C aromatic, 1600.9 cm 1 for HC=CH aromatic,
53.87 cm–1 for pyridine ring on 2,2'ꢀbipyridine ligand, 3109.25 and 3080.32 cm for C–H of aromatic ring.
The thermogram of DTA–TG analysis showed 4 endothermic peaks at temperature of 53.4, 323.2, 444.2, and
26.4 , where the bond breaking of the complex occurred at different temperatures. The result of moment
magnet measurement of the complex showed that it was a high spin complex with moment magnet value of
.68 BM, so it is a paramagnetic complex.
–1
6
5
°C
3
DOI: 10.1134/S0036023611030181
1
Cobalt, a member of the first transition row eleꢀ in their reaction has cis geometry. Hamza et al. [10]
ment, is a unique element where it can form a variety have also reported the similar phenomena by substiꢀ
2+
of colour complexes when it is reacted with some speꢀ tuting B12 coenzyme in transꢀ[Co(en) (Me)H O]
,
2
2
cific ligands. There were many reports on the synthesis where the substitution occurred into H O by cyano
2
of Co complexes and their application, such as the and they also studied the kinetic of the substitution.
kinetic and equilibrium studies of B12 coenzyme with Tornroos et al. [11] have studied the crystalisation of cis
imidazol and cyanide ligands [1], synthesis and charꢀ and trans isomer of dichlorobis(2ꢀpicolilamine)iron(II)
acterization of cobalt complex with pyrimidine nucleꢀ in 1ꢀbutanol. The preparation and structural study on
oside (uridine) and amino acids [2], synthesis of cobalt iron(II) complex with carbonyl cyanides by substitutꢀ
–
complex with
n
ꢀisonicotinamidoꢀ2',4'ꢀdichlorobenꢀ ing CN by CO produced two cis and trans isomers of
zalaldimine for antifungal and antibacterial [3] and this complex [12].
physicoꢀchemical study of the interaction of
NO2 gas is part of nitrogen oxides (NOx), a pollutꢀ
cobalt(II) ion with ciprofloxacin [4].
ant gas, where 10% of air pollutant annually is nitroꢀ
gen oxides [13]. Besides as a pollutant, NO2 ligand is
one of quite strong ligand in the spectrochemical
series, so it can substitute other weaker ligands. In this
paper, we report the synthesis and characterization
and thermal analysis of cisꢀ[Co(bipy) (CN) ] complex
Other researchers have found that in complexes of
n+
the type of [MLm] , where L is either 1,10ꢀphenanꢀ
throline ligand or a modified phen ligand, are mainly
attractive species for developing new diagnostic and
theraupectic agents that can recognize and cleave
n+
2
2
DNA [5, 6]. The metals and the ligands in [MLm]
and study its ability to react with NO2 gas through
trans effect.
system can be varied easily in a controlled manner, so
it facilitates their individual application, subsequently
providing easy access for understanding details
involved in DNA bonding and cleavage [7].
EXPERIMENTAL
The substitution reaction by other ligands in
complex compound can normally be done in an
easy way. In this reaction, the substitution reaction
of a ligand by a stronger ligand to produce other
complex can be achieved by trans effect [8]. Based
on this phenomena, Jian et al. have successfully preꢀ
pared cisꢀ[Co(phen) (CN) ] complex by reacting
Starting materials. CoCl2
6% p.a., 2,2'ꢀbipyridine p.a., copper powder, HNO3
⋅ 6H O, KCN, ethanol
2
9
,
DMSO, were used as supplied by Sigma–Aldrich
Chemical Company without further purification.
Synthesis of the complex. The complex was syntheꢀ
sized using the modified method done by Jian et al.
9]. In this study, the bidentate ligand used was 2,2'ꢀ
bipyridine rather than 1,10ꢀphenantroline.
2
2
phen ligand with Co(CN)2 [9]. The complex prepared
[
1
The article is published in the original.
418

SYNTHESIS, CHARACTERIZATION AND THERMAL STABILITY
419
T, %
00
1
9
8
7
6
5
4
3
0
0
0
0
0
0
0
4
000
3500
3000
2500
2000
1500
1000
500
/cm
1
Fig. 1. The IR spectrum of [Co(bipy) (CN) ].
2
2
Synthesis of [Co(CN)2]. [Co(CN)2] was synthesized
Determination of thermal decomposition. Determiꢀ
by mixing the solution of 1.1897 g (0.005 mol; 1.25 M) nation of thermal decomposition of the complexes was
CoCl · 6H O in 4 mL aquabidest and a solution conꢀ done with Differential Thermal Analysis and Thermoꢀ
2
2
taining 0.6512 g (0.01 mol; 3.3 M) KCN in 3 mL warm gravimetric (DTA–TG) methods. This method is one
aquabidest. The mixtures were then stirred until they of the ways to find whether the [Co(bipy) (CN)2] comꢀ
2
were homogen. The solid produced was then filtered plex has geomethrical isomer cis or trans
.
off and washed with aquabidest and wind dry till ready
for further reaction [9].
The following method was used: the complex was
measured with DTA–TG is N2 gas (80 mL/min) and
Synthesis of [Co(bipy) (CN) ] complex. 1.0052
g
2
2
(
0.005 mol) solid [Co(CN)2] was added stepwise to
solution containing 2,2'ꢀbipyridine (1.8719 g;
.012 mol) in 70 mL of ethanol 96%. The mixture was
0.5 s
100
0
44
31
then stirred for 2 h. This mixture was then evaporated
at room temperature for 4–5 days until the crystal was
obtained [9]. The crystal obtained was then washed
with ethanol 50% three times to get the pure crystal.
The crystal was then placed in a disk and left it to dry
at room temperature.
3
14.3°C
7.9%
75
50
25
0
6
18
The characterization of the complexes. Determinaꢀ
tion of the UVꢀvis spectra: 0.125 g of the complex is
dissolved in 25 mL of the solvent used (aquabidest for
2
7 uv.s/mg
73 uv.s/mg
5
323.2°C
[
Co(CN)2], DMSO for [Co(bipy) (CN)2] and the
444.2°C
3.68 uv
2
6.17 uv
548.9°C
product of reaction between [Co(bipy) (CN)2] and
2
1
6.9%
NO2 gas) and then scan in the wave length of 200–400 nm
–8
for [Co(CN)2] and 400–700 nm for [Co(bipy) (CN)2])
30
160
290
420
550
2
to find the λ
max.
T, °C (Heating)
Determination of functional groups of the comꢀ
plexes. The determination of the functional groups of
the complexes was done with IR spectra.
Fig. 2. The DTA–TG curve of [Co(bipy) (CN)2] complex.
2
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 3 2011

420
RILYANTI, HADI
range of 30–550
°
C
with the rate of 10 C/min. By the
°
use of DTA–TG, the heat and mass contents due to
the heating (change of temperature) against the comꢀ
pound used was measured. This method is valuable in
determining the formula of thermal decomposition.
N
N
N
N
CN
CN
Co
The thermogram of the [Co(bipy) (CN)2] complex
2
(
Fig. 2). The thermogram DTA–TG in Fig. 2 showed
four transition peaks of crystalline phase at temperaꢀ
ture of 53.4, 323.2, 444.2, and 526.4 shown by the
°
C
endothermic peaks. These peaks represent the physiꢀ
cal change of the compound analyzed and the peaks
found represent the crystal change by the melting
process.
Fig. 3. The structure of cisꢀ[Co(bipy) (CN) ] complex.
2
2
The thermogram of [Co(bipy) (CN)2] complex
2
showed three weight loss. The first stage loss was at
heated at temperature of 30–550
of 10
tion of
changed of the sample is observed.
Determination of magnetic moment of the complex. where the weight loss was 6%. This loss is attributed to
Determination of magnetic moment of the complex the loss of (calcd. 5.65%). The third loss was at
was done with Magnetic Susceptibility Balance temperature range of 323–548.5 , where the weight
MSB). The measurement was done at room temperꢀ loss was 63.5%, and it is equal with the loss of two bipy
ature (298 K). The empty, clean and dry MSB tube is group (calcd. 63.05%). At temperature of 548.5 the
weighted out and the magnetic susceptibility is meaꢀ residual weight of the complex was 1.15 mg (16.9%)
sured, the crystal is then placed in the MSB tube with which is equal to one molecule of CoC (calcd.
the height of 1.5–2.5 cm, to obtain the weight of the 16.75%). The melting point of [Co(bipy) (CN) ] comꢀ
. The release of two
°
C
with heating rate temperature range of 100–160
as funcꢀ was 13.6%. This percent loss is equal to the loss of four
is indication of energy lost and the mass hydrated water molecules (calculated 14.55%). The
second loss was at temperature range of 200–323
°
C where the weight loss
°
C
/min. The scanning result between T
Δ
T
°
C
N
2
°
C
(
°
C
2
2
2
sample and tube [14, 15].
plex is predicted more than 550 C
°
subsequent N atom and followed by the loss of two bipy
group might be assumed that the complex has formula of
Study of reaction between cisꢀ[Co(bipy) (CN) ] and
2
2
NO gas. 0.45 g of the solid cisꢀ[Co(bipy) (CN) ] is
2
2
2
cisꢀ[Co(bipy) (CN) ] · 4H O (Fig. 3). This result is
reacted with NO2 gas in a closedꢀtube. NO2 gas is proꢀ
duced from the reaction of 0.25 g powder copper with
.5 mL of conc. HNO3. The reaction was done for 2–
h till the colour change of the complex was observed.
2
2
2
similar by previous result reported by Jian et al. for
cisꢀ[Co(fen) (CN) ] EtOH 2H O compound [9].
Determination of magnetic moment of
cisꢀ[Co(bipy) (CN) ] 4H O complex. Based on the
⋅
⋅
2
3
2
2
2
⋅
2
2
2
measurement of magnetic moment with magnetic susꢀ
ceptibility balance, cisꢀ[Co(bipy) (CN) ] 4H O comꢀ
RESULTS AND DISCUSSION
⋅
2
2
2
Determination of functional groups of the comꢀ plex has magnetic moment of 3.68 BM. Thus this
plexes. The IR spectrum of the [Co(bipy) (CN)2] is complex is paramagnetic. The result of measurement
2
shown in Fig. 1. From this figure, it is clear that the has been corrected against the diamagnetic susceptiꢀ
complex showed some strong characteristic bonds at bility as in the magnetic moment measurement, the
the region of 1471.69 and 1442.75 cm–1 for C=N vibraꢀ value observed was combined values of paramagnetic
tion stretch, 1664.57 cm–1 for C=C aromatic stretch, and diamagnetic susceptibilities of the complex meaꢀ
–1
1
600.9 cm–1 (HC=CH aromatic stretch), 653.87 cm
sured.
Characterization of product obtained from interacꢀ
tion of cisꢀ[Co(bipy) (CN) ] with gas NO2 The solid
complex of cisꢀ[Co(bipy) (CN) ] is light brown,
after being bubbled with NO2 gas for 3 hours, the
color of the solid turn orange. This color change is
for pyridine ring on 2,2'ꢀbipyridine ligand, 3109.25
–1
and 3080.32 cm for C–H in aromatic ring. The
.
2
2
stretch at 2127.48 cm–1 showed characteristic stretch
2
2
–1
for
C
≡
N and at 3336.85 cm showed the present of
O–H from hydrated water molecule as well as at
1
639.49 cm–1 characteristic for O–H of crystallized an indication of the substitution reaction has
water molecule. By the presence of O–H bond from
hydrated and crystallized water molecules, it can be
assumed that the compound synthesized is a hydrated
complex and similar to complex previously reported [9].
Determination of thermal decomposition. Determiꢀ showed a
occurred into cisꢀ[Co(bipy) (CN) ] complex. NO2
2
2
acts as stronger ligand than bipy although it is weaker
than CN, than the substitution might occur to bipy.
The Uv spectrum of cisꢀ[Co(bipy) (CN) ] complex
2
2
λ
max
at 484.5 nm with absorbance of 0.303,
nation of decomposition thermal was done by heating while the spectrum of complex from the interaction of
the sample in the amount of 6.8 mg at the temperature cisꢀ[Co(bipy) (CN) ] with NO2 gas has at 692.5 nm
λ
max
2
2
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 3 2011

SYNTHESIS, CHARACTERIZATION AND THERMAL STABILITY
421
be undertaken through PNB DIPA University of Lamꢀ
pung with contract number of 394/H.26/8/KU/2008,
b
a
1
0
8
September 2008. Thank also goes to R.A. Tri Handayꢀ
ani who help us in the preparation of the samples.
REFERENCES
4
00
500
600
700
nm
1
2
3
. V. Sridhar and S. Satyanarayana, Proc. Ind. Acad. Sci.
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(J. Chem. Sci.) 112, 593 (2000).
Fig. 4. The UVꢀvis spectra of cisꢀ[Co(bipy) (CN) ] (a);
2
2
cisꢀ[Co(bipy)(NO ) (CN) ] (b).
2
2
2
. R. K. Agarwal, D. Sharma, L. Singh, and H. Agarwal,
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shifting before and after interaction (208 nm) which
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7
8
9
. K. Naing, M. Takahashi, M. Taniguchi, and A. Yamagꢀ
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2
which can shift to the longer max. This is because NO2
λ
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is one of auxochrome which chromofore substituent
that can shift to the red shift (batochromic). This
auxochorme can intensify the color of a complex comꢀ
pound which can be observed visually by the change of
the colour where in this reaction this occur from light
brown to orange.
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3
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1
1
0. M. S. A. Hamza, C. D. Benfer, and R. van Eldik, Inorg.
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interaction between cisꢀ[Co(bipy) (CN) ] and NO ,
2 2 2
–
1
11. K. W. Tornroos, D. Chernyshov, M. Hostettler, and
H. B. Burgi, Acta Crystallogr., Sect. C: Cryst. Struct.
Comm., 450 (2005).
showed characteristic of M–NO2 bond at 1386.82 cm
and 1761.01 cm– , this is an indication that the Co
1
metal ion is directly attached to NO2 ligand. This
result agreed to the report by Feltham [16] that the
absorption of asymmetric NO2 was observed at
1
2. S. M. Contakes, S. C. N. Hsu, T. B. Rauchfuss, and
S. R. Wilson, Inorg. Chem. 41, 1670 (2002).
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Pollution) Rineka Cipta (Jakarta), 165 (1991) (in Indoꢀ
nesian).
1
at 1320 cm–1, in which N acts as electron pair donor in
M–NO2 structure.
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J. Ilmiah MIPA, VIII, 1 (2005) (in Indonesian).
ACKNOWLEDGMENTS
15. A. R. West, Basic Solid State Chemistry. (Wiley,
England, 1999), p. 177.
The authors would like to thank to the University of
Lampung, Indonesia that provide fund for this project to 16. D. Feltham, Pure Appl. Chem. 61, 943 (1989).
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 3 2011