Synthesis and characterization of new metallophthalocyanines containing O4S2 mixed-donor substituted macrocyclic groups

Article abstract of DOI:10.3906/kim-1306-10

New phthalocyanine compounds containing mixed-donor substituted macrocyclic groups were synthesized. The complexes of metal phthalocyanines 3-5 were prepared by the reaction of 2 to get dinitrile derivative complexes by means of the corresponding anhydrou

Full text of DOI:10.3906/kim-1306-10

Turk J Chem
Turkish Journal of Chemistry
(2014) 38: 317 – 327
¨
http://journals.tubitak.gov.tr/chem/
˙
c
⃝ TUBITAK
doi:10.3906/kim-1306-10
Research Article
Synthesis and characterization of new metallophthalocyanines containing O4 S2
mixed-donor substituted macrocyclic groups
∗
˙
Meltem Betu¨l KILIC¸ ASLAN, Halit KANTEKIN
Department of Chemistry, Faculty of Sciences, Karadeniz Technical University, Trabzon, Turkey
Received: 04.06.2013
•
Accepted: 29.09.2013
•
Published Online: 14.03.2014
•
Printed: 11.04.2014
Abstract: New phthalocyanine compounds containing mixed-donor substituted macrocyclic groups were synthesized.
The complexes of metal phthalocyanines 3–5 were prepared by the reaction of 2 to get dinitrile derivative complexes by
means of the corresponding anhydrous metal salts.
Structures of the new compounds were characterized by IR, 1 H NMR, 13 C NMR, elemental analysis, and MS
spectral data.
Key words: Phthalonitrile, cyclotetramerization, dicarbonitrile, phthalocyanine
1. Introduction
Phthalocyanines (Pcs) comprise 2-dimensional, well-conjugated, planar macrocyclics with a delocalized 18π
electron system.1 This structure provides them with strong nonlinear optical properties and numerous applica-
tion areas. Phthalocyanines emit a visible light and so the blue and green colors, because of these properties,
are often used as colorants.2−4 Initially known as dye compounds, phthalocyanines are now used in many
branches of industry, and in particular in many areas of medicine such as photodynamic therapy (PDT) of
cancer.5−8 They exhibit very interesting features in terms of molecular spectroscopy. Furthermore, the optical,
photochemical, and photobiological as well as crystal properties of these compounds are interesting and impor-
tant. These photochromic materials are investigated in such advanced technology, e.g., speed data transfer and
high-capacity data storage applications, nonlinear optics, solar cells, and liquid crystals9−16 Phthalocyanines
have been applied as photoconducting agents in photocopiers and laser printers.
Industrial development is associated with emission of toxic substances, such as pesticides, toxic organic
compounds, and heavy metals, and inevitably air pollution.17 Keeping air pollution under control, especially
in terms of environmental quality, and continuous monitoring of changes are vital in terms of any measures
to be taken. In recent years, rates of toxic gases in the atmosphere have significantly increased and so it
is very important to develop precise sensors for determination and continuous monitoring of these gases.18
Metallophthalocyanines are very important in this respect. This class of compounds can be highly sensitive
and selective to many poisonous gases. A further advantage of these compounds is that they allow for the
synthesis of molecules with desired characteristics by replacing the metal atom or substituents. A recent study
demonstrated that thin films produced from nickel phthalocyanines can behave as a good sensor against ozone
in a wide temperature range.19−22
∗Correspondence: halit@ktu.edu.tr
317

˙
KILIC¸ASLAN and KANTEKIN/Turk J Chem
The importance of phthalocyanine compounds is increasing and nowadays alternative synthetic methods
for the synthesis of these compounds are being developed. One of them is the synthesis of phthalocyanine using
microwave radiation.23 Briefly the benefits of microwave radiation are as follows: a very fast reaction takes
place, high purity products can be obtained, by-products can be reduced according to the methods of synthesis,
and the classic products with high efficiency are achieved in less time and with less expenditure of energy.24,25
Optically active 1,1’-binaphthyl phthalocyanines bearing a crown ether unit were synthesized.26,27 To
date, few reports have explored the process of combining chiral binaphthol groups with a phthalocyanine core.28
Since the first report on the use of chiral binaphthy-based crown ethers as hosts for molecular recognition, chiral
binaphthol has attracted much attention. Chiral macrocycles, metal complexes, linear oligomers, and polymers
based on the 1,1’-binaphthyl structure have been synthesized for use in molecular recognition and asymmetric
catalysis and as new functional materials.29
In the present study, we describe the synthesis and characterization of new 1,1’-binaphthyl phthalocya-
nines bearing O4 S2 macrocyclic moieties.
2. Experimental
2.1. Synthesis of 2,2’-[1,1’-Binaphtalene-2,2’-diyl bis(oxy)]diethanol (1)
1,1’-Binaphthalene-2,2’-diol (10 g, 35 mmol) was dissolved in 60 mL of absolute ethanol under a nitrogen
atmosphere and NaOH (35 g, 87.5 mmol) was added. The mixture was heated at 50 ◦ C and 2-chloroethanol
(6 mL, 87.4 mmol) and 17 mL of absolute ethanol were added dropwise over 15 min. After the addition was
completed, the reaction mixture was refluxed for 2 days under nitrogen. The reaction was controlled with
a chloroform/methanol (9.5:0.5) solvent system and then ended. The cream-like mixture was cooled to room
temperature and filtered before evaporating it to dryness under vacuum to obtain a viscous liquid product. This
product was redissolved in chloroform (200 mL) after washing it with 10% NaOH and water, consecutively. The
combined organic extracts were dried with anhydrous MgSO4 and evaporated to dryness. The product was
isolated as a cream-like solid following recrystallization of the crude residue from ethanol. Yield: 7 g (54%).
mp: 100–102 ◦ C. Anal. Calcd for C24 H22 O4 : C: 77.01; H: 5.88. Found: C: 77.20; H: 5.76%. IR (KBr tablet),
νmax /cm−1 : 3516–3240 (OH), 3055 (Ar–H), 2917 (Aliph. C–H), 1619, 1456, 1242 (Ar–O–C), 1141–1082 (–
OCH2), 972. 1 H NMR (CDCl3), (δ: ppm): 8.06–7.87 (m, 4H, ArH), 7.47–7.11 (m, 8H, ArH), 4.19–4.03 (m,
4H, O–CH2), 3.57 (br s, 4H, O–CH2), 2.29 (s, 2H, OH). 13 C NMR (CDCl3), (δ: ppm): 155.03, 134.02, 130.12,
129.87, 127.66, 126.92, 124.44, 123.69, 117.84, 111.14, 71.96, 61.46. MS (FAB) (m/z): 374 [M]+ .
’
’
2.2. Synthesis of 6,7,9,10,25,26,28,29-Octahydrobenzo[h]dinaphtho [1,2-s:2 ,1 - α] [1,4, 13,16,7,10]
tetraoxacyloicosine-2,3-dicarbonitrile (2)
Compound 1 (3 g, 8.02 mmol), 192 mL of dry acetonitrile, anhydrous K2 CO3 (5.58 g, 40.08 mmol), NaI (6.12
g, 40.08 mmol), and 1,2- bis (2-iodoethyl mercapto)-4,5-dicyanobenzene (4.08 g, 8.16 mmol)30−32 were refluxed
under nitrogen atmosphere for 7 days. The reaction was controlled with chloroform/methanol (9.5:0.5) solvent
system and then ended. The yellow-orange mixture was cooled to room temperature and filtered. Then it
was evaporated to dryness under vacuum to obtain a viscous liquid product. This product was redissolved
in chloroform (200 mL) and washed with water. The combined organic extracts were dried with anhydrous
MgSO4 and until 10 mL were evaporated and filtered. The product was isolated as a yellow solid following
318

˙
KILIC¸ASLAN and KANTEKIN/Turk J Chem
recrystallization of the crude residue from ethanol. Yield: 4.27 g (66%). mp: 124–126 ◦ C. Anal. Calcd for
C36 H30 N2 O4 S2 : C: 69.90; H: 4.85; N: 4.53. Found: C: 70.00; H: 4.81; N: 4.46%. IR (KBr tablet), νmax /cm−1
:
3065 (Ar–H), 2923–2852 (Aliph. C–H), 2231 (C≡N), 1619, 1462, 1260 (Ar–O–C), 1120–1085 (–OCH2), 749.
1 H NMR (CDCl3), (δ: ppm): 8.05–7.87 (m, 6H, ArH), 7.55–7.15 (m, 8H, ArH), 4.22–4.02 (m, 12H, –OCH2),
3.34–3.19 (m, 4H, –SCH2). 13 C NMR (CDCl3), (δ: ppm): 153.74, 142.85, 138.35, 134.05, 130.97, 129.89,
128.43, 127.02, 124.43, 123.53, 120.53, 117.61, 115.42, 112.82, 71.95, 71.33, 70.41, 32.70. MS (FAB) (m/z): 618
[M]+ .
2.3. Co(II) phthalocyanine (3)
A mixture of 2 (0.5 g, 0.8 mmol) and anhydrous CoCl2 (0.052 g, 0.4 mmol) was ground in a microwave oven
and 2-(dimethylamino)ethanol (5 mL) was added. The reaction mixture was irradiated in a microwave reaction
oven at 175 ◦ C and 350 W for 6 min. After cooling to room temperature, the reaction mixture was refluxed with
ethanol to precipitate the product, which was filtered off and washed with hot ethanol and dried under vacuum.
The solid product was purified by preparative thin layer chromatography (TLC) using an ethanol/ethyl acetate
(10.0:0.5) solvent system. Yield: 0.26 g (51%) mp: >300 ◦ C. Anal. Calc. for C144 H120 N8 O16 S8 Co: C: 68.27;
H: 5.10; N: 4.43. Found: C: 68.31; H: 5.16; N: 4.40%. IR (KBr tablet), νmax /cm−1 : 3035 (Ar–H), 2922–
2851 (Aliph. C–H), 1464, 1266 (Ar–O–C), 1121–1071 (–OCH2), 964, 751. UV-vis (chloroform): λmax /nm:
[(10−5 ε dm3 mol−1 cm−1)]: 701 (5.20), 656 (5.00), 320 (5.12). MS (FAB) (m/z): 2553 [M+Na–H]+ .
2.4. Cu(II) phthalocyanine (4)
A mixture of 2 (0.5 g, 0.8 mmol) and anhydrous CuCl2 (0.054 g, 0.4 mmol) was ground in a microwave oven
and 2-(dimethylamino)ethanol (5 mL) was added. The reaction mixture was irradiated in a microwave reaction
oven at 175 ◦ C and 350 W for 7 min. After cooling to room temperature, the reaction mixture was refluxed
with ethanol to precipitate the product, which was filtered off and washed with hot ethanol and dried under
vacuum. The solid product was purified by preparative TLC using a chloroform/methanol (7:3) solvent system.
Yield: 0.21 g (41%) mp: >300 ◦ C. Anal. Calc. for C144 H120 N8 O16 S8 Cu: C: 68.15; H: 4.73; N: 4.42. Found:
C: 68.02; H: 4.75; N: 4.50%. IR (KBr tablet), νmax /cm−1 : 3043 (Ar–H), 2918–2862 (Aliph. C–H), 1378, 1283
(Ar–O–C), 1075–1068 (–OCH2), 745. UV-vis (chloroform): λmax /nm: [(10−5 ε dm3 mol−1 cm−1)]: 713
(5.27), 659 (5.03), 341 (5.02). MS (FAB) (m/z): 2535 [M]+ .
2.5. Ni(II) phthalocyanine (5)
A mixture of 2 (0.5 g, 1 mmol) and anhydrous NiCl2 (0.051 g, 0.4 mmol) was ground in a microwave oven
and 2-(dimethylamino)ethanol (5 mL) was added. The reaction mixture was irradiated in a microwave reaction
oven at 175 ◦ C and 350 W for 8 min. After cooling to room temperature, the reaction mixture was refluxed
with ethanol to precipitate the product, which was filtered off and washed with hot ethanol and dried under
vacuum. The solid product was purified by preparative TLC using a chloroform/acetone (8:2) solvent system.
Yield: 0.18 g (35%) mp: >300 ◦ C. Anal. Calc. for C144 H120 N8 O16 S8 Ni: C: 68.27; H: 4.74; N: 4.43. Found:
C: 68.19; H: 4.70; N: 4.38%. IR (KBr tablet), νmax /cm−1 : 3087 (Ar–H), 2919–2875 (Aliph. C–H), 1413, 1268
(Ar–O–C), 1126–1072 (–OCH2), 743. 1 H NMR (CDCl3), (δ: ppm): 7.68–7.64 (m, 28H, Ar–H), 7.49–7.30 (m,
28H, Ar–H), 4.03–4.00 (m, 48H, –OCH2), 3.73–3.66 (m, 16H, –SCH2). 13 C NMR (CDCl3), (δ: ppm): 167.94,
319

˙
KILIC¸ASLAN and KANTEKIN/Turk J Chem
152.53, 144.99, 133.87, 132.58, 131.18, 130.01, 129.08, 124.56, 122.04, 118.89, 111.14, 105.00, 101.28, 72.03,
70.98, 69.40, 32.87. UV-vis (chloroform): λmax /nm: [(10−5ε dm3 mol−1 cm−1)]: 707 (4.96), 650 (4.89), 314
(5.04). MS (FAB) (m/z): 2570 [M+K]+ .
3. Results and discussion
1,2-Bis(2-iodoethylmercapto)-4,5-dicyanobenzene was synthesized according to the literature.30−32 The prepa-
ration of 1, 2, CoPc (3), CuPc (4), and NiPc (5) is shown in Figure 1.
NC
NC
S
I
ethanol
NaOH
OH
OH
O
O
OH
OH
Cl
OH
S
I
dry acetonitrile
dry K2CO3
(1)
CN
CN
S
O
O
O
O
S
(2)
O
O
O
O
O
O
O
S
O
S
S
S
N
N
N
N
N
N
N
M
N
S
S
S
S
O
O
O
O
O
O
O
O
Compound 3
Co
4
5
M
Cu
Ni
Figure 1. The synthesis of the metallophthalocyanines.
Compound 1 was prepared with 1,1’-binaphthalene-2,2’-diol and 2-chloroethanol reaction at 95 ◦ C in
absolute ethanol and the yield was 54%. In the IR spectrum (Figure 2) of 1 stretching vibrations of the O–H
320

˙
KILIC¸ASLAN and KANTEKIN/Turk J Chem
band at 3516–3240 cm−1 seemed to shift after the reaction. In addition, stretching vibrations of O–CH2 were
observed at 1141–1047 cm−1 . A singlet peak at δ = 5.00 ppm of OH protons of compound 1,1’-binaphthalene-
2,2’-diol was seen at δ = 2.29 ppm for compound 1 and it disappeared after addition of D2 O. The 1 H NMR
spectrum of 1 indicated aromatic protons at 8.06–7.87 and 7.47–7.11 and aliphatic protons at 4.19–4.03 and
3.57 ppm. The 13 C NMR spectrum of 1 indicated the presence of carbon resonance at δ = 71.96 and δ =
61.46 ppm. The MS spectrum of 1 displayed the [M]+ parent ion peak at m/z = 374, confirming the structure.
The elemental analysis was satisfactory.
Figure 2. IR spectrum of compound 1.
’
Compound 2 was prepared with 2,2′ -[1,1’-binaphthalene-2,2 -diyl bis(oxy)]diethanol and 1,2-bis(2-
iodoethylmercapto)-4,5-dicyanobenzene reaction at 85 ◦ C in dry acetonitrile and the yield was 66%. In the IR
spectrum (Figure 3) of 2 stretching vibrations of the –OH band at 3516–3240 cm−1 disappeared and C≡N
groups were observed at 2231 cm−1 . In the 1 H NMR spectrum (Figure 4) of 2, signals belonging to OH groups
at δ = 2.29 ppm disappeared to give the proposed structure. In addition, the 1 H NMR spectrum of 2 indicated
aromatic protons at 8.05–7.87 and 7.55–7.15 ppm and aliphatic protons at 4.22–4.02 (–OCH2) and 3.34–3.19
(–SCH2) ppm. The 13 C NMR spectrum of 2 indicated the presence of nitrile carbon atoms (C≡N) in 2 at
115.42 ppm. The MS spectrum (Figure 5) of 2 displayed the [M]+ parent ion peak at m/z = 618, confirming
the structure. The elemental analysis was satisfactory.
The metallophthalocyanines of CoPc (3), CuPc (4), and NiPc (5) were obtained from anhydrous metal
salts (CoCl2 , CuCl2 , NiCl2) in 2-(dimethylamino)ethanol by microwave irradiation. We used a 350-W domestic
oven at 175 ◦ C for synthesis of 3–5.
321

˙
KILIC¸ASLAN and KANTEKIN/Turk J Chem
Figure 3. IR spectra of compound 2.
Figure 4. 1 H NMR spectrum of compound 2.
In the IR spectrum of metallophthalocyanines 3 (Figure 6)–5, phthalocyanines 3–5 were confirmed by
the disappearance of the sharp –C≡N vibration at 2231 cm−1 . The 1 H NMR spectra of 3–5 were almost
identical, except for broad signals of 3–5, from aggregation of planar phthalocyanines at the high concentration
used for NMR measurements, and the 1 H NMR spectra of CoPc (3) and CuPc (4) were precluded owing to
their paramagnetic nature. The 1 H NMR spectrum (Figure 7) of 5 indicated aromatic protons at 7.68–7.64 and
7.49–7.30 and aliphatic protons at 4.03–4.00 and 3.73–3.66 ppm. The inner core protons N–H of this compound
322

˙
KILIC¸ASLAN and KANTEKIN/Turk J Chem
5 could not be observed because of the probable strong aggregation of the molecule. The 13 C NMR spectrum
of NiPc (5) was confirmed by the disappearance of the sharp –C≡N vibration at 5 at 115.42 ppm (C≡N).
The MS spectra of 3 (Figure 8), 4 (Figure 9), and 5 (Figure 10) show molecular ion peaks at m/z = 2553
[M+Na–H]+ , 2535 [M]+ , and 2070 [M+K]+ , respectively, confirming the proposed structure. The elemental
analysis data were satisfactory.32,33
Figure 5. Mass spectrum of compound 2.
Figure 6. IR spectrum of compound 3.
323

˙
KILIC¸ASLAN and KANTEKIN/Turk J Chem
Figure 7. 1 H NMR spectrum of compound 5.
Figure 8. Mass spectrum of compound 3.
The spectra of metallophthalocyanines complexes consist of an intense absorption band in the visible
region traditionally near 670 nm called the Q band and a generally weaker band near 340 nm called the Soret
or B band, both being π − π* transitions. Metalation, which maintains the planarity of the molecule, increases
35,36
the symmetry D4h
.
The introduction of a metal ion inside the cavity results in a slightly blue shift in the
wavelength of the Q band as the introduction of a metal ion reduces electron density. It has been demonstrated
that a more electronegative metal ion in the phthalocyanine cavity causes a greater blue shift for the wavelength
of the Q band of phthalocyanines.35,36
The UV-vis absorption spectra of 3–5 in chloroform at room temperature are shown in Figure 11. The
UV-vis absorption spectra of metallophthalocyanines 3–5 had intense Q band absorptions at λmax = 701, 713,
324

˙
KILIC¸ASLAN and KANTEKIN/Turk J Chem
and 707 nm, respectively, with weaker absorptions at λmax = 656, 659, and 650 nm, respectively. The single Q
band in metallo derivatives 3–5 was characteristic. This result is typical of metal complexes of substituted and
unsubstituted metallophthalocyanines with D4h symmetry.35,36 The other bands (B) in the UV region for 3–5
were observed at λmax = 320, 341, and 314 nm due to transition from deeper π levels to the LUMO.
Figure 9. Mass spectrum of compound 4.
Figure 10. Mass spectrum of compound 5.
325

˙
KILIC¸ASLAN and KANTEKIN/Turk J Chem
2
1.5
1
0.5
0
200
300
400
500
600
λ (nm)
700
800
900
Figure 11. UV-vis spectra of compounds 3(-),4(—),5(-..-) in chloroform.
4. Conclusion
We demonstrated the synthesis and characterization of new metallophthalocyanines 3–5 containing mixed-donor
substituted macrocyclic groups.
Structures of the new compounds were characterized by IR, 1 H NMR, 13 C NMR, elemental analysis,
and MS spectral data.
Acknowledgment
This study was supported by the Research Fund of Karadeniz Technical University.
References
1. Leznoff, C. C.; Lever, A. B. P. Phthalocyanines: Properties and Applications, vol. 4, VCH Publishers: New York,
NY, USA, 1996.
2. Kalkan, A.; Bayır, Z. A. Polyhedron 2006, 25, 39–42.
¨
3. Kula¸c, D.; Bulut, M.; Altındal, A.; Ozkaya, A. R.; Salih, B.; Bekarog˘lu, O. Polyhedron 2007, 26, 5432–5440.
¨
4. Akdemir, N.; Erdem, G. Synth. React. Inorg. Metal-Org. Nano-Metal Chem. 2005, 35, 819–824.
5. McKeown, N. B. Phthalocyanine Materials, Synthesis, Structure and Function, Cambridge University Press:
Boston, MA, USA, 1998.
6. Kadish, K.; Smith, K. M.; Guilard, R. The Porphrin Handbook, vol. 15–20, Academic Press: San Diego, CA, USA,
2003.
7. C¸akmak, Y.; Koleman, S.; Duman, S.; Dede, Y.; Dolen, Y.; Kılı¸c, B.; K¨osterelli, Z.; Yıldırım, L. T.; Do˘gan, A. L.;
Gu¨c¸, D. et al. Angew Chem. Int. Ed., 2011, 50, 11937–11941.
8. Rosenthal, I. Photochem. Photobiol. 1991, 53, 859–870.
9. Leznoff, C. C.; Lever, A. B. P. Phthalocyanines: Properties and Applications, vol. 3; VCH Publishers: New York
NY, USA, 1993.
10. De La Torre, G.; Vazquez, P.; Agullo-Lopez, F.; Torres, T. J. Mat. Chem. 1998, 8, 1671–1683.
11. Yang, F.; Forrest, S. R. Am. Chem. Soc. Nano 2008, 2, 1022–1032.
12. Forrest, S. R. Chem. Rev. 1997, 97, 1793–1896.
13. Bilgin, A.; Ertem, B.; G¨ok, Y. Polyhedron 2005, 24, 117–124.
14. Leznoff, C. C.; Lever, A. B. P. Phthalocyanines: Properties and Applications, vol. 2; VCH Publishers: New York,
NY, USA, 1993.
15. Emmelius, M.; Pawlowski, G.; Vollmann, H. W. Angewandte Chemie International Edition 1989, 28, 1445–1471.
326

˙
KILIC¸ASLAN and KANTEKIN/Turk J Chem
¨
16. Yılmaz, F.; Ozer, M.; Kani, I.; Bekarog˘lu, O. Cataly. Lett. 2009, 130, 642–647.
¨
17. Yantasee, W.; Lin, Y. H.; Hongsirikarn, K.; Fryxell, G. E.; Addleman, R.; Timchalk, C. Environ. Health. Persp.
2007, 115, 1683–1690.
18. Barile, F. A. Principles of Toxicology Testing; CRC Press: Boca Raton, FL, USA, 2008.
19. Chaabane, R. F. Mat. Sci. Eng. C. 2006, 26, 551–554.
20. Simon, J.; Andre, J. J. Molecular Semiconductors; Springer: Berlin, Germany, 1985.
21. G¨opel, W. Philos. Trans. R. Soc. Lond. 1995, 353, 333–354.
22. Mack, J.; Stillman M. J. Coordination Chem. Rev. 2001, 219–221, 993–1032.
23. Hayes, B. L. Microwave Synthesis: Chemistry at the Speed of Light; CEM Publishing: Matthews, NC, USA, 2002.
24. Seven, O.; Dindar, B.; Gu¨ltekin, B. Turk. J. Chem. 2009, 33, 123–134.
25. Shaabani, A.; Moghaddam, R. M.; Maleki, A.; Rezayan, A. H. Dyes Pigments 2007, 74, 279–282.
26. Wu, L.; Wang, Q.; Bian, Y.; Jiang, J.; Zhang, X. Langmuir 2010, 26, 7489–7497.
27. Liu, H. W.; Chen, C. F.; Ai, M.; Gong, A. J.; Jiang, J.; Xi, F. Tetrahedron Asymmetr. 2000, 11, 4915–4922.
28. Lu, J.; Deng, Y.; Zhang, X.; Kobayashi, N.; Jiang, J. Inorg. Chem. 2011, 50, 2532–2537.
29. Lv, W.; Zhang, X.; Lu, J.; Zhnag, Y. Eur. J. Inorg. Chem. 2008, 27, 4255–4261.
30. Liu, H.; Liu, Y.; Liu, M.; Chen, C.; Xi, F. Tetrahedron Lett. 2001, 42, 7083–7086.
31. Nemykin, V. N.; Koposov, A. Y.; Subbotin, R. I.; Sharma, S. Tetrahedron Lett. 2007, 48, 5425–5428.
32. Kobayashi, N.; Higashi, R.; Titeca, B. R.; Lamote, F.; Ceulemans, A. J. Am. Chem. Soc. 1999, 121, 12018–12028.
33. Kobayashi, N. Coordin. Chem. Rev. 2001, 219–221, 99–123.
34. Pu, L. Chemical Reviews 1998, 98, 2405–2494.
¨
35. Gu¨rek, A. G.; Bekarog˘lu, O. J. Porphyr. Phthalocya. 1997, 1, 227–237.
36. W¨ohrle, D.; Eskes, M.; Shigehara, K.; Yamada, A. Synthesis 1993, 2, 194–196.
37. G¨ok, Y.; Kantekin, H.; Bilgin, A.; Mendil, D.; De˘girmenciog˘lu, I. J. Chem. Soc. Chem. Commun. 2001, 3, 285–286.
38. Nostrum, C. F. van; Picken, S. J.; Schouten, A. J.; Nolte, R. J. M. J. Am. Chem. Soc. 1995, 117, 9957–9965.
39. Nostrum, C. F. van; Picken, S. J.; Schouten, A. J.; Nolte, R. J. M. Angew. Chem. Int. Ed. Engl. 1994, 33,
2173–2175.
40. Pullen, A. E.; Faulmann, C.; Cassoux, P. Eur. J. Inorg. Chem. 1999, 2, 269–276.
41. Takahashi, K.; Kawashima, M.; Tomita, Y.; Itoh, M. Inorg. Chim. Acta. 1995, 232, 69–73.
327

Copyright of Turkish Journal of Chemistry is the property of Scientific and Technical
Research Council of Turkey and its content may not be copied or emailed to multiple sites or
posted to a listserv without the copyright holder's express written permission. However, users
may print, download, or email articles for individual use.