Synthesis of novel single site tin porphyrin complexes and the catalytic activity of tin tetrakis(4-fluorophenyl)porphyrin over -caprolactone

Article abstract of DOI:10.1142/S1088424617500407

Tin tetrakis(4-fluorophenyl)porphyrin, tin tetrakis(4-chlorophenyl)porphyrin and tin tetrakis(4-bromophenyl)porphyrin complexes were prepared by reaction of butyltin trichloride with tetrakis(4-fluorophenyl)porphyrin, tetrakis(4-chlorophenyl)porphyrin, and tetrakis(4-bromophenyl)porphyrin in tetrahydrofuran and toluene, respectively. These novel complexes were characterized by 1H, 13C NMR, FTIR, mass spectroscopy and elemental analysis. The single site tin complex including fluoride was tested as a catalyst in polymerization of -caprolactone and was very effective. Polycaprolactone was characterized by 1H, 13C NMR, and gel permeation chromatography.

Full text of DOI:10.1142/S1088424617500407

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2017; 21: 1–7
DOI: 10.1142/S1088424617500407
Published at http://www.worldscinet.com/jpp/
Synthesis of novel single site tin porphyrin complexes
and the catalytic activity of tin tetrakis(4-fluorophenyl)
porphyrin over e-caprolactone
HanifiYaman and Asgar Kayan*◊
Department of Chemistry, Kocaeli University, Kocaeli 41380, Turkey
Received date: 6 March, 2017
Accepted date: 30 April, 2017
ABSTRACT: Tin tetrakis(4-fluorophenyl)porphyrin, tin tetrakis(4-chlorophenyl)porphyrin and tin
tetrakis(4-bromophenyl)porphyrin complexes were prepared by reaction of butyltin trichloride with
tetrakis(4-fluorophenyl)porphyrin, tetrakis(4-chlorophenyl)porphyrin, and tetrakis(4-bromophenyl)por-
1
13
phyrin in tetrahydrofuran and toluene, respectively. These novel complexes were characterized by H, C
NMR, FTIR, mass spectroscopy and elemental analysis. The single site tin complex including fluoride
was tested as a catalyst in polymerization of e-caprolactone and was very effective. Polycaprolactone
1
13
was characterized by H, C NMR, and gel permeation chromatography.
KEYWORDS: butyltin trichloride; porphyrin; ring-opening; single site catalyst; e-caprolactone.
opening polymerization of hetereocyclic compounds [10].
INTRODUCTION
Therefore, it is important to prepare new single site tin
porphyrin complexes having catalytic properties.
The first goal of the present work was to report the
synthesis of single site tin(IV) porphyrin complexes. The
second goal was their use as catalysts in a polymerization
reaction of e-caprolactone monomer.
The complexes of porphyrins with different metals have
beensynthesizedandcharacterized[1,2].Electrondeficient
metalloporphyrins such as Cr(TPP)Cl, Fe(TTP)OTf and
Cr(TTP)OTf have been used as mild Lewis acid catalysts
in polymerization reactions of lactides and caprolactone
[2, 3]. Tin(IV) porphyrins have attracted attention in recent
years due to successful utilization in catalysis, biomedicine
and synthesis of biomaterials [4, 5]. The spectroscopic
properties of tin(IV) porphyrin complexes make them
convenient for chemical study. The Sn(IV) center is usually
six-coordinate with two axial ligands and many derivatives
have been synthesized with variety of anions such as
carbanions, aryloxide, carboxylate and halides [6, 7]. We
have previously shown that various tin compounds can be
used for ring opening polymerization (ROP) of epoxides
and caprolactone [8, 9]. However, there is no study about
butyltin trichloride with tetrakis(4-fluorophenyl)porphyrin
EXPERIMENTAL SECTION
Materials and instruments
Butyltin trichloride (95%, Aldrich) pyrrole (97%,
,
Merck), propionic acid (99%, Merck), e-caprolactone
(99%, Alfa Aesar), 4-fluorobenzaldehyde (98%, Sigma–
Aldrich), 4-bromobenzaldehyde (99%, Sigma-Aldrich)
and 4-chlorobenzaldehyde (97%, Sigma–Aldrich) were
used as received. Tetrahydrofuran (THF) (99.9%, Merck),
methanol (99.9%, Merck), and toluene (99.7%, Sigma-
Aldrich) were dried over activated 4 Å molecular sieves
before use. Polymer syntheses were carried out under
nitrogen atmosphere. Tin porphyrin complexes and
(
TFPPH ), tetrakis(4-chlorophenyl)porphyrin (TCPPH )
2
2
and tetrakis(4-bromophenyl)porphyrin (TBPPH ). The
2
other tin(IV) porphyrin compounds have been used as
mild Lewis acid catalysts in polymer synthesis. The
single site catalyst is regio- and stereoselective in the ring
1
polymers were characterized by HNMR (Bruker DPX,
13
4
1
00 MHz) and C-NMR spectroscopy (Bruker DPX,
00 MHz). Infrared spectra of complexes were recorded on
◊
SPP full member in good standing
*
Correspondence to: akayan@kocaeli.edu.tr (A. Kayan)
a Shimadzu 8201/86601 PC spectrometer. The elemental
Copyright © 2017 World Scientific Publishing Company

2
H. YAMAN AND A. KAYAN
analysis was carried out with a LECO CHNS-932
elemental analyzer. Bruker Microflex LT MALDI-TOF
MS and Waters SYNAPT HRMS (ESI±) systems were
used to obtain molecular weight of TXPP-Sn complexes.
GPC analysis was performed at 30°C on a Shimadzu
prominence GPC system equipped with a RID-10A
refractive index detector, a LC-20AD solvent delivery unit,
a CTO-10AS column oven and a set of two columns, PSS
SDV 5 µL 1000 Å and PSS SDV 5 µL 50 Å. THF (HPLC
grade) was used as the mobile phase at 1.0 mL/min. The
sample concentration was 2 mg/mL, and the injection
volume was 50 µL. The calibration curve was made with
seven polystyrene standards covering the molecular weight
range from 162 to 67000 Da.
obtained with yield 25%. Microanalysis (C H Br N ,
44 26 4 4
M = 930.32 g/mol), Calcd.: C, 56.81; H, 2.82; N, 6.02%.
w
Found: C, 56.74; H, 2.92; N 6.02%. MALDI-MS: 930.89
+
Da for [C H Br N +H] . HRMS, ESI(+): 930.89 Da for
4
4
26
4
+
4
1
[C H Br N +H] . H NMR (400 MHz; CDCl ; Me Si):
4
4
26
4
4
3
4
dH, ppm8.86 (s, 8H, porphyrin), 8.08 (d, 8H, J = 8.26 Hz,
Ph), 7.92 (d, 8H, J = 8.24 Hz, Ph), -2.84 (brd, 2H, NH,
1
3
porphyrin). C NMR (CDCl ): d , ppm 140.83, 135.83,
3
C
-1
130.00, 122.65, 110.00. FTIR: n, cm 3310 (N-H,
secondary amine), 3057 (C-H, phenyl), 1591, 1547, 1471
(C=C, C=N), 1344 (C-N), 966 (C-H, b-pyrrole), 796
(pyrrole).
Preparation of butyl(5,10,15,20-tetrakis(4-
fluorophenyl)porphyrinato)tin(IV) chloride,
[Bu(TFPP)SnCl]
Preparation of 5,10,15,20-tetrakis(4-fluorophenyl)
porphyrin (TFPPH2)
Butyltin trichloride (0.073 g, 0.24 mmol) was added
TFPPH was prepared according to the reported pro-
gradually to a solution of TFPPH (0.11 g, 0.16 mmol)
2
2
cedure by the reaction of 4-fluorobenzaldehyde (2.53 g,
in 5 mL of THF. The reaction mixture was stirred for 3 h
at reflux temperature under nitrogen atmosphere. Then
the volatile parts were removed by vacuum evaporator
2
0 mmol) with pyrrole (1.34 g, 20 mmol) in 20 mL of hot
propionic acid [11, 12]. The reaction mixture was stirred for
0 min at reflux temperature. Then, the mixture was cooled
o
3
at 40 C and dried. The product was washed with hexane
at room temperature and filtered. The filtrate was washed
with methanol and hot distilled water and then dried at
furnace. The purple product was obtained with yield 20%.
Elementalanalysis(C H F N , M =686.70g/mol), Calcd.:
and then dried by vacuum evaporator. The blue product
was obtained with yield 60%. Elemental analysis
(C H ClF N Sn, M = 895.96 g/mol), Calcd.: C, 64.35;
4
8
33
4
4
w
H, 3.71; N, 6.25%. Found: C, 64.01; H, 4.03; N 6.18%.
4
4
26
4
4
w
+
C, 76.96; H, 3.82; N, 8.16%. Found: C, 77.13; H, 4.00; N,
MALDI-MS: 918.4 Da for [C H SnCl(TFPP)+Na] ,
4
9
+
1
+
+
8
.29%. MALDI-MS: 687.20 Da for [C H F N +H] . H
861.8Dafor[C H Sn(TFPP)] , 803.4Dafor[Sn(TFPP)] .
44
26
4
4
4 9
1
NMR (400 MHz; CDCl ; Me Si): d , ppm 8.84 (s, 8H,
porphyrin), 8.17 (s, 8H, Ph), 7.47 (s, 8H, Ph), -2.85 (s,
H, NH, porphyrin). FTIR: n, cm 3307 (N-H, secondary
amine), 3041 (C-H, phenyl), 1597, 1550, 1467 (C=C, C=N),
348 (C-N), 966 (C-H, b-pyrrole), 788 (pyrrole).
H NMR (400 MHz; CDCl ; Me Si): d , ppm 8.59 (brd,
3
4
H
3
4
H
8H, porphyrin), 8.59 (brd, 8H, Ph), 7.74 (t, 8H, J =
-1
a
2
7.79 Hz, Ph), 1.40 (brd, 2H, Sn- CH ), 1.19 (brd, 2H,
2
b
g
d
13
CH ), 0.99 (brd, 2H, CH ), 0.65 (brd, 3H, CH ).
C
2
2
3
1
NMR (CDCl ): d , ppm 165.57, 163.56, 146.16, 140.45,
-1
3
C
1
28.34, 115.81, 33.24, 27.82, 6.17. FTIR: n, cm 3041
(
(
(
C-H, phenyl), 2958, 2928 (C-H, Bu), 1598, 1504, 1468
C=C, C=N), 1319 (C-N), 987 (C-H, b-pyrrole), 798
pyrrole). (Sn- CH CH CH CH ;brd: broad).
Preparation of 5,10,15,20-tetrakis(4-chlorophenyl)
porphyrin (TCPPH2)
a
b
g
d
2
2
2
3
Reaction between 4-chlorobenzaldehyde (2.90 g,
2
0 mmol) and pyrrole (1.34 g, 20 mmol) was conducted
Preparation of butyl(5,10,15,20-tetrakis(4-
chlorophenyl)porphyrinato)tin(IV) chloride,
similarly to that described above. The blue product
was obtained with yield 20%. Elemental analysis
[Bu(TCPP)SnCl]
(
C H Cl N , M = 752.52 g/mol), Calcd.: C, 70.23;
4
4
26
4
4
w
Butyltin trichloride (0.07 g, 0.25 mmol) was added
H, 3.48; N, 7.45%. Found: C, 71.46; H, 3.08; N 7.97%.
+
1
gradually to a solution of TCPPH (0.12 g, 0.16 mmol) in
2
MALDI-MS: 753.14 Da for [C H Cl N +H] .
NMR (400 MHz; CDCl ; Me Si): d , ppm 8.87 (s, 8H,
porphyrin), 8.15 (d, 8H, J = 7.96 Hz, Ph), 7.78 (d, 8H,
J = 7.93 Hz, Ph), -2.82 (brd, 2H, NH, porphyrin). FTIR: n,
cm 3312 (N-H, secondary amine), 3060 (C-H, phenyl),
H
4
4
26
4
4
5
9
mL of toluene. The reaction mixture was stirred for 3 h at
3
4
H
o
0 C under nitrogen atmosphere. Then, the volatile parts
o
were removed by vacuum evaporator at 60 C and dried.
The product was washed with hexane and then dried by
vacuum evaporator. The blue product was obtained with
yield 50%. Microanalysis (C H Cl N Sn, M = 961.78
-
1
1
592, 1545, 1472 (C=C, C=N), 1346 (C-N), 966 (C-H,
4
8
33
5
4
w
b-pyrrole), 796 (pyrrole).
g/mol), Found: C, 59.94; H, 3.46; N, 5.83%. MS: 922.56
+
+ 1
Da for [C H (TCPP)Sn] , 753.09 Da for [(TCPP)+H] . H
4
9
Preparation of 5,10,15,20-tetrakis(4-bromophenyl)
porphyrin (TBPPH2)
NMR (400 MHz; CDCl ; Me Si): d , ppm 8.68 (s, 8H,
3
4
H
porphyrin), 8.58 (d, 8H, J = 8.14 Hz, Ph), 8.06 (d, 8H,
a
Reaction between 4-bromobenzaldehyde (3.74 g,
0 mmol) and pyrrole (1.34 g, 20 mmol) was carried out
J = 8.14 Hz, Ph), 1.34 (brd, 2H, Sn- CH ), 1.16 (brd, 2H,
2
b
g
d
2
CH ), 0.95 (m, 2H, CH ), 0.61 (t, 3H, CH ). FTIR: n,
-1
2
2
3
similarly to the preceding reactions. The blue product was
cm 3032 (C-H, phenyl), 2958, 2928, 2874 (C-H, Bu),
Copyright © 2017 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2017; 21: 2–7

SYNTHESIS OF NOVEL SINGLE SITE TIN PORPHYRIN COMPLEXES AND THE CATALYTIC ACTIVITY
3
O
1
588, 1482 (C=C, C=N), 1400, 1300 (C-N), 1093, 985
+
4
4
(
C-H, b-pyrrole), 802 (pyrrole).
X
N
H
H
Preparation of butyl(5,10,15,20-tetrakis(4-
bromophenyl)porphyrinato)tin(IV) chloride,
I
II
X
X
[
Bu(TBPP)SnCl]
Reaction between butyltin trichloride (0.07 g,
0
.25 mmol) and TBPPH (0.15 g, 0.16 mmol) was
2
N
conducted similarly to that described above. The blue
product was obtained with yield 50%. Microanalysis
NH
HN
(
C H ClBr N Sn, M = 1139.52 g/mol), Calcd.: C, 50.59;
48
33
4
4
w
H, 2.92; N, 4.92%. Found: C, 50.23; H, 3.18; N 4.78%.
N
HRMS ESI(+) (in methanol): 1171.29 Da for [Bu(TBPP)
SnCl+CH OH+H] . H NMR (400 MHz; CDCl ; Me Si):
+
1
3
3
4
dH, ppm 8.65 (s, 8H, porphyrin), 8.49 (d, 8H, J = 7.09 Hz,
Ph), 8.21 (d, 8H, J = 7.36 Hz, Ph), 1.35 (brd, 2H,
X
a
b
g
III
Sn- CH ), 1.16 (brd, 2H, CH ), 0.95 (m, 2H, CH ), 0.62
2
2
2
d
-1
X
(
t, 3H, CH ). FTIR: n, cm 3037 (C-H, phenyl), 2954,
3
2
1
930, 2872 (C-H, Bu), 1584, 1484 (C=C, C=N), 1400,
302 (C-N), 1094, 986 (C-H, b-pyrrole), 801 (pyrrole).
C H SnCl
4
9
3
Polymerization of e-caprolactone with the
X
X
[
Bu(TFPP)SnCl] catalyst
The catalyst (Bu(TFPP)SnCl, 20 mg) was mixed
with e-caprolactone (1.0 mL) in a vial under nitrogen.
The solvent free mixture was stirred at different
N
1
temperatures and times as indicated in Table 1. H NMR
Cl
Sn
N
(
400 MHz; CDCl ; Me Si): d , ppm 4.08 (t, J = 7.0 Hz,
N
C4H9
3
4
H
a
e
CH -O), 2.30 (t, J = 7.0 Hz, CH -C = O), 1.67 (m, J =
7
2
2
b,d
g
13
N
.0 Hz, CH ), 1.39 (m, J = 7.0 Hz, CH ). C NMR
2
2
e
(
(
CDCl ): d , ppm 173.80 (C = O), 64.37 ( CH O), 34.34
3
C
2
a
d
b
g
CH ), 28.56 ( CH ), 25.74 ( CH ), 24.80 ( CH ). [O =
2
2
2
2
a
b
g
d
e
X
C- CH CH CH CH CH O-].
2
2
2
2
2
IV
X
Scheme 1. Synthesis reactions of Bu(TXPP)SnCl complexes.
I: 4-fluorobenzaldehyde, 4-chlorobenzaldehyde, and 4-bromo-
benzaldehyde when X is F, Cl, and Br II: pyrrole III: 5,10,15,20-
tetrakis(4-halophenyl)porphyrins IV: butyl(5,10,15,20-tetrakis
(4-halophenyl)porphyrinato)tin(IV) chloride complexes.
RESULTS AND DISCUSSIONS
(
In this study, novel single site tin porphyrin complexes
were synthesized by reaction of BuSnCl with 1.5:1 mol
3
ratio of 5,10,15,20-tetrakis(4-fluorophenyl)porphyrin, 5,-
10,15,20-tetrakis(4-chlorophenyl)porphyrin, and 5,10,-
1
5,20-tetrakis(4-bromophenyl)porphyrin in THF at reflux
o
temperature (or in toluene at 90 C) in accordance with the
following reactions. The products were formulated to be
butyl-5,10,15,20(tetrakis(4-fluorophenyl)porphyrinato)
tin(IV)chloride, butyl(5,10,15,20-tetrakis(4-chlorophenyl)
porphyrinato)tin(IV) chloride, and butyl(5,10,15,20-tet-
rakis(4-bromophenyl)porphyrinato)tin(IV) chloride
spectrum of butyl-5,10,15,20-tetrakis(4-fluorophenyl)por-
phyrinatotin(IV) chloride complex, the bands at ~1598,
-1
1504, 1468 cm correspond to C=C, C=N vibrations. These
valuesare consistentwiththose detectedinanumberof metal
1
porphyrin complexes [14]. H NMR spectrum of studied
complex was given in the experimental section. The proton
resonance signals for phenyl groups of the TFPP ligand
appeared at 8.59 and 7.74 ppm as a broad singlet and a triplet
while the porphyrin protons of the TFPP ligand appeared at
8.59 ppm as a broad singlet. These results are comparable
to those published for the porphyrin-metal complexes [15].
The C NMR spectrum of Bu(TFPP)SnCl complex showed
characteristic peaks for ring carbon atoms of TFPP and butyl
group. Carbons for both rings and butyl group appeared at
(
Scheme 1).
The formulations of tin porphyrin complexes were
determined by elemental analysis, mass, FTIR, and NMR
measurements. For example, the FTIR spectrum of free
TFPPH ligand exhibited band at 3307 cm corresponding
to stretching vibrations of N–H secondary amine [13]. After
coordination of TFPP to butyltin trichloride, the band at
3
-1
2
13
-1
307 cm disappeared in the FTIR spectrum. In the FTIR
Copyright © 2017 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2017; 21: 3–7

4
H. YAMAN AND A. KAYAN
Fig. 1. MS spectrum of Bu(TFPP)SnCl complex
Fig. 2. MS spectrum of Bu(TFPP)SnCl complex (longer stirring times >3 h)
1
2
65.57, 163.56, 146.16, 140.45, 128.34, 115.81, 33.24,
7.82, 6.17 ppm. These values are very characteristic for
temperature, solvent THF also bonds to the tin center
as seen in the mass spectrum (Fig. 2). MS measurement
of Bu(TFPP)SnCl complex showed peaks at 970.54 Da
metal-bonded substituted porphyrin complexes [16, 17].
MS measurement of Bu(TFPP)SnCl (Mw = 895.96 g/mol)
complex showed peaks at 918.4 Da for [C H (TFPP)
+
for [C H (TFPP)SnCl+THF+H] , and 897.41 Da for
4
9
+
molecular ion [C H (TFPP)SnCl+H] . Similarly, the
reactions between BuSnCl and 5,10,15,20-tetrakis(4-
4
9
4
9
+
+
SnCl+Na] , 861.8 Da for [C H (TFPP)Sn] , 803.4 Da for
4
9
3
+
+
[(TFPP)Sn] , 747.1 Da for [(TFPP)Sn-3F] . MS spectrum of
chlorophenyl)porphyrin(TCPPH ) or 5,10,15,20-tetrakis-
2
Bu(TFPP)SnCl complex is given in Fig. 1.
It is also important to note that when the stirring
time increases from 3 h to longer stirring times at high
(4-bromophenyl)porphyrin(TBPPH ) in 1.5:1 mol ratio
were conducted in toluene at 90 C. The products, butyl-
(5,10,15,20-tetrakis(4-chlorophenyl)porphyrinato)tin(IV)
2
o
Copyright © 2017 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2017; 21: 4–7

SYNTHESIS OF NOVEL SINGLE SITE TIN PORPHYRIN COMPLEXES AND THE CATALYTIC ACTIVITY
5
Scheme 2. Reactions involved in the ring-opening polymerization of e-caprolactone
chloride and butyl(5,10,15,20-tetrakis(4-bromophenyl)
porphyrinato)tin(IV) chloride were obtained.
to inductive effects of fluorine atoms. Due to the very
large electronegativity of fluorine atoms, the electrons
in the porphyrin ring and tin atom are pulled towards
it, leading to the inductive effect over Sn–Cl bond. In
other words, Sn(IV) center is more Lewis acidic with
the fluorinated porphyrin. Polymer samples obtained
from ring opening polymerization of e-CL were
The formulations of these complexes Bu(TCPP)SnCl
and Bu(TBPP)SnCl were also determined by elemental
analysis, FTIR, NMR, and mass measurements. The
1
comparison of the integral of the signals in H-NMR
spectra and the peak data in mass spectra confirmed the
1
13
suggested formulas. The N-H secondary amine peak
characterized by H, C NMR, FTIR and gel permeation
1
1
disappeared in the H-NMR spectra of the tin porphyrin
chromatography (GPC). In the H NMR spectrum
complexes while it was at ~ -2.82 ppm in free porphyrin
ligand. The disappearance of N–H peak can be attributed
to the formation of covalent bond between tin and
nitrogen atoms. These bromo- and chloro-substituted
porphyrin complexes were single-site catalysts, however,
they were not very effective in the polymerization
reactions of e-caprolactone. For example, polymers of
e-caprolactone prepared with Bu(TCPP)SnCl by stirring
of polycaprolactone (PCL), signals are assigned as
follows: d , ppm 4.08 (t, H, e-CH ), 2.30 (t, H, a-CH ),
H
2
2
1.67 (m, H, b-CH + d-CH ), and 1.39 (m, H, g-CH ),
2
2
2
which characterize the polymer chain. (e-Caprolactone
1
monomer: H NMR (CDCl ): d , ppm 4.23 (m, e-CH ),
3
H
2
2.64 (m, a-CH ), 1.86 (m, d-CH ), 1.77 (m, b-CH +
2
2
2
1
3
g-CH ). C NMR(CDCl ): d , ppm 176.66 (C=O), 69.50
2
3
H
e
a
d
b
( CH O), 34.64 ( CH ), 29.35 ( CH ), 29.00 ( CH ),
2
2
2
2
o
g
13
at 100 C for 10 h, the main peak appeared at 2300
23.00 ( CH ). In the C NMR spectrum of PCL, signals
2
e
Da for weight average molecular weight (M ) with a
are assigned as follows: 173.80 (C=O), 64.37 ( CH O),
w
2
a
d
b
g
conversion of 30%.
34.34 ( CH ), 28.56 ( CH ), 25.74 ( CH ), 24.80 ( CH )
2 2 2 2
a
b
g
d
e
13
The development of ‘‘single-site’’ catalysts has been
a key goal for producing polymers with controllable
molecular weights and polydispersities [18]. The
Bu(TFPP)SnCl complex was very effective in the
polymerization reactions of e-caprolactone when it
was used as a catalyst (see Table 1). For example,
e-caprolactone polymers prepared with Bu(TFPP)SnCl
ppm, [O=C- CH CH CH CH CH O-]. C NMR data
2
2
2
2
2
of PCL were different than data of e-caprolactone
monomer. For example, while e-caprolactone monomer
e
gave peaks at 176.66 for C=O and 69.50 for CH O,
2
PCL gave peaks at 173.80 for C=O and 64.37 ppm for
e
CH O respectively. These values are consistent with
2
those in the literature [19, 20]. Butyl(TFPP)tin chloride
is an octahedral complex. Only the axial chloride ligand
participates in the ring opening polymerization process
when it is used as a catalyst. The coordination of the
o
by stirring at 100 C for 10 h, the main peak appeared
at 35790 Da for weight average molecular weight (Mw)
with a conversion of 92%. This can be attributed solely
Copyright © 2017 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2017; 21: 5–7

6
H. YAMAN AND A. KAYAN
Table 1. Data for PCL obtained from GPC measurements
o
Catalyst
T, C
40
Time, h
2
Mw
420
Mn
420
(M /M ) Conversion (%)
w
n
Butyl(5,10,15,20-tetrakis(4-fluorophenyl)
1.00
38
porphyrinato)tin(IV) chloride, Bu(TFPP)SnCl
4
6
6
6
6
8
8
8
8
8
8
8
0
0
0
0
0
0
0
0
0
0
0
0
24
2
430
425
430
1.00
1.00
1.10
1.10
1.10
1.10
1.10
1.10
1.00
1.15
1.40
1.45
1.10
1.30
1.30
1.50
1.50
63
42
26
44
57
13
32
40
48
61
86
89
63
63
77
83
>92
420
1990
10
24
48
2
2130
4130
3820
7170
6380
2460
2290
4
5660
5030
6
7840
7170
8
9410
9000
10
24
48
2
12450
30640
37780
11800
27580
32270
32820
35790
10780
21940
25980
10550
21050
24860
21740
24010
1
1
1
1
1
00
00
00
00
00
4
6
8
10
o
Fig. 3. Gel permeation chromatogram of e-CL polymer prepared at 100 C for 10 h with the catalyst Bu(TFPP)SnCl
e-caprolactone to the tin center is one of the key steps.
Coordination to the Lewis acidic tin center (large ionic
radius) facilitates ring opening by both an S 2 and S 1
group, leading to oxygen-acyl scission. Subsequently,
e-caprolactone molecules coordinate to the tin center
and insert in to the tin-chloride bond, resulting in the
N
N
reaction pathways [17, 21, 22]. Transition metal and tin
compounds carry out ROP of lactides, epoxides, and
e-caprolactone via a coordination-insertion mechanism
formation of polycaprolactone. In the S 1 mechanism,
N
the leaving group chloride first leaves, whereupon
a tin cation compound forms that is attacked by the
e-caprolactone.
[
18, 23]. As seen from Scheme 2, in the S 2 mechanism
N
the tin ion first allows coordination of the e-caprolactone
to the tin center through the carbonyl oxygen atom. Then,
the labile chloride ligand attacks the activated carbonyl
As seen from Table 1, the conversion of monomer to
polymer depends on times and temperatures. For short
times and low temperatures, low conversions were
Copyright © 2017 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2017; 21: 6–7

SYNTHESIS OF NOVEL SINGLE SITE TIN PORPHYRIN COMPLEXES AND THE CATALYTIC ACTIVITY
7
obtained. The conversion increased with the temperature
5. Berg K, Selbo PK, Weyergang A, Dietze A,
Prasmickaite L, Bonsted A, Engesaeter BØ, Angell-
Petersen E, Warloe T, Frandsen N and Høgset A,
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6. Kumar AA, Giribabu L, Reddy DR and Maiya BG.
Inorg. Chem. 2001; 40: 6757–6766.
rising from 80°C (60%) to 100°C (92%) after 10 h
stirring (Fig. 3). Since the polymerization reactions were
conducted without solvent, it was difficult to reach 100%
conversion because of difficult stirring of viscous PCL.
As expected for acidic catalysts, the medium molecular
weights of polymers (~35000 Da) were obtained.
7. Arnold DP and Blok J. Coord. Chem. Rev. 2004;
2
48: 299–319.
. Yalçın G and Kayan A. Des. Monomers Polym.
012; 15: 405–416.
. Kayan A. Des. Monomers Polym. 2015; 18:
45–549.
0. KayanA. J. Appl. Polym. Sci. 2012; 123: 3527–3534.
1. Adler AD, Sklar L, Longo FR, Finarelli JD and
Finarelli MG. J. Heterocyclic. Chem. 1968; 5:
8
9
CONCLUSION
2
In this work, novel single site tin porphyrin
complexes were synthesized and characterized by a
combination of elemental analysis, FTIR, NMR and
mass spectroscopic methods. The fluoro-substituted
porphyrin tin complex (Bu(TFPP)SnCl) was used as
a catalyst for the polymerization of e-caprolactone at
different temperatures and time intervals. Polymers with
narrow molecular weight distribution (M /M = 1.0–1.5)
were obtained by using this single site tin catalyst. The
structure of polymers was characterized by NMR, FTIR
spectroscopy and GPC. In summary, this new fluoro-
substituted porphyrin tin complex was good catalyst
for ring opening polymerization of e-caprolactone
when compared to the known acid catalysts. In other
words, e-caprolactone polymers were produced with
controllable molecular weights and polydispersities by
using this single site tin porphyrin catalyst.
5
1
1
6
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1
2. Lindsey JS, Schreiman IC, Hsu HC, Kearnay PC
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27–836.
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1
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Acknowledgments
This work was supported by the research foundation
of Kocaeli University (project no: 2014/017).
3
9–48.
9. Yildiz BC and Kayan A, Des. Monomers Polym.
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