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(differential scanning calorimetry) measurements were performed
on a TA DSC Q2000 calorimeter. Single crystal X-ray crystallography
was carried out at the Department of Inorganic Chemistry at the
Technical University of Munich. Most of the chemicals and solvents
were utilized as received from commercial suppliers unless other-
wise stated. Propylene oxide applied in copolymerization reactions
was distilled with CaH2 and stored under argon atmosphere prior
to use.
(R,R)-SalenCoII: A two-necked Schlenk flask fitted with a reflux con-
denser was loaded with (R,R)-salenH2 (1.29 g, 2.4 mmol) in dry tolu-
ene (10 mL). A solution of Co(OAc)2 (0.41 g, 2.4 mmol) in dry meth-
anol (20 mL) was then transferred via a cannula under argon at-
mosphere to the Schlenk flask to afford a red precipitate. The mix-
ture was heated at reflux with stirring at 908C for 1 h. After the re-
action mixture was allowed to cool to 408C, the red precipitate
was filtered and washed with MeOH until the filtrate turned color-
less. The final product was dried at 408C under vacuum to a con-
stant weight, yielding the product as a red powder (1.2 g, 83%
yield). Elemental analysis calcd (%) for C36H52CoN2O2: C 71.62, H
8.68, N 4.64; found: C 71.68, H 8.42, N 4.53.
Synthetic procedures
[5,10,15,20-Tetraphenylporphyrin]cobalt(III) chloride: Tetraphe-
nylporphyrin ligand (100 mg, 0.14 mmol) was dissolved in DMF
(30 mL) in a 500 mL flask, and the solution was heated up to
110 8C. Cobalt(II) acetate tetrahydrate (61 mg, 0.25 mmol) was then
added as a solid, and the reaction system was stirred at 1108C for
one hour. After removal of the solvent under reduced pressure, the
remaining solid (TPPCoII) was utilized directly for the oxidation of
the metal center. Methanol (250 mL) was poured into the flask con-
taining TPPCoII, and concentrated aqueous HCl (ca. 7 mL) was
added. Afterwards, the reaction mixture became a dark red solu-
tion and was allowed to stir under air atmosphere overnight. After
removal of methanol under reduced pressure, the remaining sus-
pension in water was filtered, and the filtration cake was washed
with water (3ꢁ20 mL) and saturated aqueous NaHCO3 (3ꢁ20 mL),
followed again by water (5ꢁ20 mL). The purple porphyrin complex
product was air dried in the fume hood overnight and then redis-
solved in acetone (30 mL) and filtered. After removing the volatiles
under reduced pressure, the final product was obtained as
(R,R)-SalenCoIIIOTs: The synthetic procedure was adopted from
previous publications with a slight modification.[18b,22] A round-
bottom flask was loaded with a mixture of (R,R)-salenCoII complex
(6.0 g, 9.9 mmol) and p-toluenesulfonic acid monohydrate (1.89 g,
9.9 mmol) in CH2Cl2 (200 mL) and the solution was stirred under
dry oxygen atmosphere at room temperature for 3 h. Afterwards,
all volatiles were removed using rotary evaporation and the re-
maining solid was further dried under vacuum. The resulting solid
was suspended in hexane, re-collected by filtration, and washed
with a CH2Cl2/hexane (25:75) mixture. After drying at 408C under
vacuum to a constant weight, the product was obtained as a dark
1
green solid (6.6 g, 86% yield). H NMR ([D6]DMSO, 500 MHz, 258C):
d=7.82 (s, 2H), 7.46–7.41 (m, 6H), 7.07 (d, J=7.5 Hz, 2H), 3.57–
3.56 (m, 2H), 3.05–3.03 (m, 2H), 2.24 (s, 3H), 1.97–1.96 (m, 2H),
1.88–1.84 (m, 2H), 1.71 (s, 18H), 1.57–1.53 (m, 2H), 1.27 ppm (s,
18H); 13C{1H} NMR ([D6]DMSO, 125 MHz, 258C): d=163.79, 161.21,
140.87, 136.63, 134.93, 128.43, 127.90, 127.18, 124.67, 117.64, 68.38,
34.93, 32.69, 30.64, 29.54, 28.65, 23.41, 19.95 ppm; elemental analy-
sis calcd (%) for C43H59CoN2O5S: C 66.65, H 7.67, N 3.61, S 4.14;
found: C 64.45; H,7.57, N 3.39, S 4.81.
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a purple solid. H NMR (CD2Cl2, 300 MHz, 258C): d=8.79 (br), 8.26
(br), 7.81 ppm (br); 13C{1H} NMR ([D8]THF, 75.5 MHz, 258C): d=
135.1, 126.6, 125.4, 118.4, 115.6, 114.1, 113.8 ppm; MS (ESI) m/z:
671.5 (TPPCo+); UV/Vis (DCM): lmax =406.0, 542.9 nm (br); elemen-
tal analysis calcd (%) for C44H28N4CoCl: C 74.74, H 3.99, N 7.92;
found: C 74.21, H 4.04, N 7.93.
(R,R)-SalenCoIIICl: The synthetic procedure was adopted from pre-
vious publications with
a
slight modification.[18b,22] (R,R)-
SalenCoIIIOTs (5.68 g, 7.33 mmol) was dissolved in CH2Cl2 (200 mL)
and transferred into a 500 mL separating funnel. The solution was
washed with saturated brine solution (3ꢁ400 mL) and the organic
layer was collected and dried over anhydrous Na2SO4 powder fol-
lowed by removal of the volatiles under reduced pressure. The re-
maining solid was suspended in hexane under vigorous stirring
and a precipitate was formed and isolated. After repeating the
above hexane wash, the collected solid was dried at 408C under
vacuum to a constant weight, affording the product as a dark
(R,R)-(À)-N,N’-Bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanedi-
amine [(R,R)-salenH2]: A three-necked flask fitted with a reflux con-
denser and a dropping funnel was loaded with (R,R)-1,2-diammo-
niumcyclohexane mono-(+)-tartrate salt (5 g, 18.9 mmol), K2CO3
(5.2 g, 37.6 mmol), and distilled water (10 mL) and the reaction
mixture was stirred at room temperature until full dissolution had
occurred, followed by addition of ethanol (100 mL). The reaction
system was heated to 808C, and a solution of 3,5-di-tert-butyl-2-hy-
droxybenzaldehyde (8.9 g, 37.6 mmol) in ethanol (50 mL) was
added dropwise. The dropping funnel was then rinsed with small
amounts of ethanol (20 mL in total), and the yellow slurry was
stirred at 808C for an additional 2 h. Afterwards, the reaction mix-
ture was allowed to cool to ambient temperature followed by fur-
ther cooling in an ice water bath with vigorous stirring for 2 h. The
product was collected by vacuum filtration and the filtration cake
was washed with ethanol (100 mL). The crude solid was again dis-
solved in CH2Cl2 (100 mL) and washed with water (2ꢁ100 mL) and
brine solution (100 mL). After drying over anhydrous Na2SO4, the
solution was filtered and all volatiles were removed from the fil-
trate under reduced pressure to afford the product as a yellow
powder (10.9 g, 98% yield). M.p. 207–2088C; 1H NMR (300 MHz,
CDCl3, 258C): d=13.74 (s, 2H), 8.33 (s, 2H), 7.33 (d, J=2.5 Hz, 2H),
7.01 (d, J=2.5 Hz, 2H), 3.36–3.33 (m, 2H), 1.98–1.48 (m, 8H), 1.44
(s, 18H), 1.26 ppm (s, 18H); 13C{1H} NMR (75 MHz, CDCl3, 258C): d=
165.94, 158.13, 139.99, 136.45, 126.86, 126.17, 117.97, 72.56, 35.09,
34.17, 33.42, 31.57, 29.58, 24.5 ppm; elemental analysis calcd (%)
for C36H54N2O2: C 79.07, H 9.95, N 5.12; found: C 79.32, H 9.43, N
5.10.
1
green solid (3.98 g, 85%). H NMR ([D6]DMSO, 300 MHz, 258C): d=
7.83 (s, 2H), 7.44 (s, 2H), 7.32 (s, 2H), 3.84–3.63 (m, 2H), 3.09–3.06
(m, 2H), 2.02–1.97 (m, 2H), 1.97–1.83 (m, 2H), 1.72 (s, 18H), 1.63–
1.52 (m, 2H), 1.31 ppm (s, 18H); elemental analysis calcd (%) for
C36H52ClCoN2O2: C 67.65, H 8.20, N 4.38; found: C 67.25, H 8.26, N
4.28.
Sodium methyl carbonate: In an autoclave, a solution of sodium
methoxide (5 g) in methanol (30 mL) was pressurized with CO2 gas
(20 bar). After stirring the reaction mixture overnight at room tem-
perature, the CO2 pressure was released and all volatiles were re-
moved via rotary evaporation under reduced pressure, affording
the product as a white solid (quantitative yield).
General procedure for PO/CO2 copolymerization
A 100 mL or 200 mL autoclave was dried in the oven at 1028C
overnight prior to use. The autoclave was allowed to cool to room
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Chem. Eur. J. 2015, 21, 1 – 8
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