Synthesis and Spectral Characteristics of Sn(IV) Tetraphenylporphyrinates

Article abstract of DOI:10.1134/S1070363218120162

Coordination reactions of 5,10,15,20-tetraphenylporphyrin, 2-bromo-5,10,15,20-tetraphenylporphyrin, 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin, 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin and metal-exchange reactions of their c

Full text of DOI:10.1134/S1070363218120162

ISSN 1070-3632, Russian Journal of General Chemistry, 2018, Vol. 88, No. 12, pp. 2559–2563. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © N.V. Chizhova, A.V. Shinkarenko, N.Zh. Mamardashvili, 2018, published in Zhurnal Obshchei Khimii, 2018, Vol. 88, No. 12,
pp. 2044–2048.
Synthesis and Spectral Characteristics
of Sn(IV) Tetraphenylporphyrinates
N. V. Chizhovaa*, A. V. Shinkarenkob, and N. Zh. Mamardashvilia
a Krestov Institute of Solutions Chemistry, Russian Academy of Sciences, ul. Akademicheskaya 1, Ivanovo, 153045 Russia
*e-mail: nvc@isc-ras.ru
b Ivanovo State University of Chemistry and Technology , Ivanovo, Russia
Received May 24, 2018
Revised May 24, 2018
Accepted May 28, 2018
Abstract—Coordination reactions of 5,10,15,20-tetraphenylporphyrin, 2-bromo-5,10,15,20-tetraphenylporphyrin,
2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin, 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenyl-
porphyrin and metal-exchange reactions of their cadmium complexes with tin(II) chloride in dimethyl-
formamide are described. Optimum conditions for the synthesis of Sn(IV) tetraphenylporphyrinates have been
1
elaborated. The obtained substances have been identified by electron absorption spectroscopy, Н NMR
spectroscopy, and mass-spectroscopy.
Keywords: tetraphenylporphyrins, complexes with Cd(II) and Sn(IV), reaction of complex formation, metal
exchange reactions
DOI: 10.1134/S1070363218120162
The interest in synthesis and investigation of
porphine complexes with metals of variable valency
has been arisen due to their possible application in
catalysis and biomedicine [1]. Previously Sn(IV)Cl2
tetraphenylporphyrinate [2] has been synthesized by
mixing porphine 1 with SnCl2 in refluxing pyridine and
acetic acid. Column chromatography on alumina has
resulted in anion exchange of chloride anions with hyd-
roxyl ones. Tin complexes with benzene-substituted
phthalocyanine have been synthesized by refluxing of
the free bases with tin(II) chloride in 1-chloronaph-
thalene during 1.5 h [3].
under reflux proceeded up to conversion of 25% within
an hour [Eq. (1)]. The synthesis of Sn(OH)2 5,10,15,20-
tetraphenylphorphyrinate 9 required refluxing of a
solution of porphine 1 in DMF with excess of tin
chloride during 5–6 h .
→
H2P + MX2(Solv)n–2 ← (Solv)mMP + 2НX
+ (n–2–m)Solv,
(1)
where H2P is a porphyrin, MX2(Solv)n–2 is a solvated
metal salt, Solv is the solvent, MP is the metal
porphyrinate.
Sn(IV)(ОН)2 2-bromo-5,10,15,20-tetraphenylphor-
phyrinate 10 was obtained via the interaction of the
bromine-substituted porphyrine 2 with SnCl2 (molar
ratio 1 : 10) in DMF (reflux) within 20 min. Sn(IV)(ОН)2
2,3,12,13-tetrabromo-5,10,15,20-tetraphenylphor-
phyrinate 11 was synthesized under similar conditions
via refluxing of a mixture of tetrabromotertraphenyl-
porphyrin and SnCl2 in DMF during 5 min. Duration of
the synthesis of Sn(IV)(ОН)2 2,3,7,8,12,13,17,18-
octabromo-5,10,15,20-tetraphenylporphyrinate 12 in
boiling DMF was reduced to 2 min (molar ratio
4 : SnCl2 = 1 : 3). Electron absorption spectrum of the
obtained substance in DMF contained the bands with с
Aiming to develop efficient procedure of synthesis
of tin ms-β-substituted porphyrinates, we herein present
the approaches to prepare the following substances via
coordination reactions: 5,10,15,20 – tetraphenylpor-
phyrin 1, 2-bromo-5,10,15,20-tetraphenylporphyrin 2,
2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin
3, and 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetra-
phenylporphyrin 4 and metal exchange of their
cadmium complexes 5–8 with tin(II) chloride in DMF
(Scheme 1).
It was shown that the reaction of tetraphenyl-
porphyrin with tin chloride (molar ratio 1 : 10) in DMF
2559

2560
CHIZHOVA et al.
Scheme 1.
R1
R3
R1
R3
R2
R2
R3
R3
N
N
N
N
N
NH
N
M
HN
R3
R3
R2
R2
R3
R2
R3
R2
1−4
5−12
R1 = R2 = R3 = H (1); R1 = Br, R2 = R3 =H (2); R1 = R2 = Br, R3 = H (3); R1 = R2 = R3 = Br (4); R1 = R2 = R3 = H, М = Сd(II)
(5); R1 = Br, R2 = R3 = H, M = Cd(II) (6), R1 = R2 = Br, R3 = H, M = Cd(II) (7); R1 = R2 = R3 = Br, M = Cd(II) (8); R1 = R2 =
R3 = H, М = Sn(IV)(OH)2 (9); R1 = Br, R2 = R3 = H, М = Sn(IV)(OH)2 (10); R1 = R2 = Br, R3 = H, М = Sn(IV)(OH)2 (11);
R1 = R2 = R3 = Br, М = Sn(IV)(OH)2 (12).
λmax = 671, 617, and 476 nm, while the signals of the
starting porphyrin 4 with λmax = 783, 662, 481, and
371 nm disappeared (Tables 1 and 2). Hence, the duration
of the synthesis of the corresponding tin porphyrinate
was significantly reduced in the case of mono-
brominated derivative 2 as compared to the parent tetra-
phenylporphyrin. That was probably due the electronic
effects of the substituents as well as the change of the
geometry of the molecule of porphyrine 2 compared to
that of compound 1 (better accordance of the reactive
site N4H2 to the size of the SnCl2(Solv)n–2) complex.
fact could be explained by the strengthening of
coordination interaction of the solvato complex cation
[MX2(Solv)n–2] with porphyrin in transition state [4]
due to an increase in the electron density at the tertiary
nitrogen atoms in the macrocycle (+C-effect of
bromine atoms).
According to the reference data [5–8], the use of
transmetalation of labile porphyrine complexes [9] to
synthesize these with doubly and triply charged metals
leads to significant decrease in the reaction duration
and increase in the products yield.
The porphyrines reactivity towards the coordination
with SnCl2 in DMF was increased with the increase in
the number of bromine atoms in the macrocycle. That
The transmetalation reaction can be generalized as
follows:
Table 1. Parameters of electron absorption spectra tetraphenylporphyrins 1–4 in CH2Cl2
λ, nm (log ε)
Compound
References
band I
band II
bands III, IV
Soret band
1
2
2
3
3
4
647 (3.84)
648 (3.67)
648 (3.79)
685 (4.02)
683 (4.06)
743 (3.87)
591 (3.96)
593 (3.70)
593 (3.81)
612 (3.58)
612 (3.70)
626 (4.12)
549 (4.08), 514 (4.40)
552 (3.72), 517 (4.27)
551 (3.78), 518 (4.33)
533 (4.30)
417 (5.61)
421 (5.55),
421 (5.58)
436 (5.52)
436 (5.46)
469 (5.29)
369 (4.48)
469 (5.29)
369 (4.48)
[10]
[11]
[15]
533 (4.31)
569 (3.96)
4
741 (3.85)
625 (4.11)
569 (3.95)
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SYNTHESIS AND SPECTRAL CHARACTERISTICS OF Sn(IV)
2561
Table 2. Parameters of electron absorption spectra of Cd(II) и Sn(IV) tetraphenylporphyrinates 5–12
λ, nm (log ε)
Complex
Solvent
band I
band II
Soret band
5
6
ДМФА
ДМФА
ДМФА
ДМФА
CHCl3
CHCl3
CHCl3
CHCl3
623 (3.88)
626 (4.16)
641(4.12)
732 (4.14)
599 (4.13)
601 (4.09)
607 (4.05)
660 (4.26)
580 (3.85)
584 (4.15)
593 (4.12)
661 (4.04)
560 (4.32)
563 (4.28)
569 (4.32)
610 (4.29)
438 (5.27), 417 (4.61)
442 (5.42), 419 (4.68)
449 (5.23), 420 (4.66)
491 (4.86), 460 (4.41)
425 (5.66), 404 (4.60)
429 (5.52), 408 (4.58)
437 (5.50), 416 (4.81)
469 (5.26)
7
8
9
10
11
12
→
MР + M'Xn(Solv)m–n ← M'Р + MXn(Solv)m–n
,
(2)
compared to the cadmium complexes was due to the
presence of strong π-dative interaction of the dπ-eg(π*)-
type between the metal ion and the porphyrin macrocycle.
where МP and M'P are metal porphyrinates,
MXn(Solv)m–n and M'Xn(Solv)m–n are the metals
solvato complexes.
1Н NMR spectrum of Sn(IV)(OH)2 tetraphenyl-
porphyrinate contained the signals of pyrrole and
phenyl rings at 9.20, 8.32, and 7.83 ppm. The signals
of the hydroxyl protons were found in the strong field
region, at –7.44 ppm. 1Н NMR spectrum of the
octabromoporphyrinate Sn(IV) 12 did not contain any
signals of pyrrole rings. The signals of phenyl rings of
compound 12 were shifted upfield in comparison with
the non-substituted compound 9.
It was shown, that Sn(IV)(ОН)2 5,10,15,20-tetra-
phenylporphyrinate 9 and 2-bromo-5,10,15,20-tetra-
phenylporphyrinate 10 could be synthesized within 10–
15 min via the reaction of the corresponding Cd(II)
porphyrinates 6 and 7 with tin chloride (molar ratio
1 : 3) in DMF at room temperature. The tetrabromine-
substituted tin porphyrinate 11 was synthesized via
heating the mixture of complex 7 and tin chloride
(molar ratio 1 : 5) in DMF to boiling. Synthesis of tin
octabromotetraphenylporphyrinate 12 under the same
conditions required boiling of complex 8 with SnCl2 in
DMF during 3 min.
Mass spectrum of tin(IV) tetraphenylporphyrinate
showed the signals with m/z 732.2 and 749.2,
assignable to molecular ions appeared via dissociation
of the Sn–OH bonds. The signal with m/z 767.2 cor-
responded to the Sn(IV)P(OH)2 structure. Mass spectra
of tin(IV) porphyrinates 10–12 contained the signals
with m/z 845.3, 1083.3, and 1399.2, corresponding to
Sn(IV)(OH)2P.
Higher reactivity of cadmium porphyrinates
towards tin(II) chloride in DMF in comparison with
the complex formation could be explained by the fact
that the transannular NH bonds are not broken in the
former process. The reactivity of Cd(II) tetraphenyl-
porphyrinates was reduced with the increase in the
number of bromine atoms in the macrocycle. Probably,
that fact was due to conjugation of π-electron density
of bromine atom with the delocalized π-electron cloud
of the tetrapyrrole macrocycle.
In summary, β-bromo-substituted tetraphenylpor-
phyrins and their Cd(II) complexes were synthesized.
Coordination reaction of the tetraphenylporphyrins and
the metal exchange of their cadmium complexes with
tin(II) chloride in DMF was studied. It was shown that
the use of transmetalation approach significantly
reduced the reaction duration and increased the
product yield compared to the direct complex
formation route. Sn(IV) tetraphenylporphyrinates were
synthesized and identified .
Characteristics of electron absorption spectra of
cadmium and tin porphyrinates are given in Table 2.
As with porphyrinates of doubly and triply charged
metals, the increase in the number of the substituting
bromine atoms in tin porphyrinates 10–12 led to
bathochromic shift of the spectral bands in comparison
with the non-substituted complex 9. Hypsochromic
shift of the absorption bands of Sn(IV) porphyrinates
EXPERIMENTAL
5,10,15,20-Tetraphenylporphine (Porphychem), DMF,
chloroform (“chemically pure”), and aluminum oxide
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CHIZHOVA et al.
(Merck) were used as received. Tin(II) chloride
(“chemically pure”) was annealed at 135°С during 2 h
and dried over CaCl2. 2-Bromo-5,10,15,20-tetraphenyl-
porphyrin and 2,3,12,13-tetrabromo-5,10,15,20-tetra-
phenylporphyrin were synthesized via the procedures
adopted from [10–12]. 2,3,7,8,12,13,17,18-Octabromo-
5,10,15,20-tetraphenylporphyrin was obtained as
described in [13]. Сd(II) tetraphenylporphyrinates
were synthesized as described elsewhere [14] using
cadmium acetate instead of cadmium chloride. The
complex formation and metal exchange reactions were
monitored by means of spectrophotometry.
b. The target product was synthesized similarly to
compounds 9 from 0.02 g (0.0248 mmol) of complex
6 and 0.014 g (0.0745 mmol) of SnCl2 in 10 mL of
DMF, the reaction duration being 15 min. Yield: 0.016 g
(0.0190 mmol, 75%).
Sn(IV)(OH)2 2,3,12,13-tetrabromo-5,10,15,20-
tetraphenylporphyrinate (11). a. A mixture of 0.02 g
(0.0215 mmol) of porphyrin 3 and 0.041 g (0.215 mmol)
of SnCl2 in 10 mL of DMF was refluxed for 5 min and
then treated as described above. Yield 0.016 g
(0.0148 mmol, 70%). 1H NMR spectrum, δ, ppm: 8.99
s (4Н, pyrrole), 8.19 d (8Н, Phо, J = 7.7 Hz), 7.80–
7.77 m (12Н, Phm,p). Mass spectrum, m/z (Irel, %):
1065.3 (49) [M – ОН]+ [calculated for С44Н24N4Br4Sn
(OH): 1064.1].
Electron absorption spectra were recorded using a
Cary-100 (Varian) spectrophotometer. Mass spectra
were recorded using a Shimadzu Biotech Axima
Confidence MALDI TOF mass spectrometer (matrix –
b. 0.0182 g (0.0961 mmol) of SnCl2 was added to a
solution of 0.02 g (0.0192 mmol) of complex 7 in
10 mL of DMF. The reaction mixture was heated to
boiling, cooled, and treated as was described above.
Yield 0.017 g (0.0157 mmol, 80%).
1
dihydroxybenzoic acid). Н NMR spectra (500 MHz,
CDCl3) were recorded with a Bruker AV III-500
spectrometer (internal reference – TMS).
Sn(IV)(OH)2 5,10,15,20-tetraphenylporphyrinate
(9). A solution of 0.02 g (0.0276 mmol) of complex 5
in 10 mL of DMF was mixed with 0.0157 g
(0.0827 mmol) of SnCl2. The reaction mixture was
kept at room temperature during 10 min; then the
mixture was poured into water and NaCl was added.
The precipitate was filtered off, washed with water,
dried, and purified by column chromatography on
alumina (eluent—chloroform–ethanol, 5 : 1). Yield
Sn(IV)(OH)2 2,3,7,8,12,13,17,18-octabromo-
5,10,15,20-tetraphenylporphyrinate (12). a. 0.0092 g
(0.0483 mmol) of SnCl2 was added to a solution of
0.02 g (0.0161 mmol) porphyrin 4 in 10 mL of DMF.
The reaction mixture was refluxed during 2 min,
cooled, and treated as described above. The product
was purified by chromatography on alumina (eluent –
dichloromethane). Yield 0.015 g (0.011 mmol, 75%).
1H NMR spectrum, δ, ppm: 8.22 d (8Н, Phо, J =
7.7 Hz), 7.82–7.78 m (12Н, Phm,p). Mass spectrum,
m/z (Irel, %): 1399.2 (79) [M]+ [calculated for
C44Н20N4Br8Sn(OH)2: 1396.7].
1
0.016 g (0.0210 mmol, 77%). H NMR spectrum, δ,
ppm: 9.20 s (8Н, pyrrole), 8.32 d (8Н, Phо, J =
7.7 Hz), 7.83–7.81 m (12Н, Phm,p), –7.44 s (2H, OH).
Mass spectrum, m/z (Irel, %): 732.2 (36) [M – 2ОН]+
(calculated for С44Н28N4Sn: 731.4).
b. 0.014 g (0.0735 mmol) of SnCl2 was added to a
solution of 0.02 g (0.0147 mmol) of complex 8 in
10 mL of DMF. The reaction mixture was refluxed
during 3 min, cooled, and treated as described above.
Yield 0.015 g (0.011 mmol, 75%).
Sn(IV)(OH)2 2-bromo-5,10,15,20-tetraphenylpor-
phyrinate (10). a. A mixture of 0.02 g (0.0288 mmol)
of porphyrin 2 and 0.055 g (0.288 mmol) of SnCl2 in
10 mL of DMF was refluxed during 20 min; then the
mixture was cooled and poured into water. NaCl was
added, the precipitate was filtered off, washed with
water, dried, and purified by column chromatography
on alumina (eluent—chloroform). Yield 0.015 g
ACKNOWLEDGMENTS
This study was financially supported by the Russian
Foundation for Basic Research (project no. 18-03-
00048_а) and performed using the equipment of the
Upper Volga Regional Center for Physico-Chemical
Studies.
1
(0.0178 mmol, 63%). Н NMR spectrum, δ, ppm:
9.072–9.06 m (2Н, pyrrole), 9.04 s (1Н, pyrrole), 9.03–
9.00 m (2Н, pyrrole), 8.98–8.93 m (2Н, pyrrole), 8.31–
8.25 m (6Н, Phо), 8.18–8.15 m (2Н, Phо), 7.83–7.77 m
(12Н, Phm,p), –7.02 s (2H, OH). Mass spectrum,
m/z (Irel, %): 845.3 (98) [M]+ [calculated for
С44Н27N4BrSn(OH)2: 844.4].
CONFLICT OF INTEREST
No conflict of interest was declared by the authors.
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SYNTHESIS AND SPECTRAL CHARACTERISTICS OF Sn(IV)
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