78
C. Xu et al. / Journal of Molecular Catalysis A: Chemical 383–384 (2014) 77–82
Toluene, THF, hexane and dichloromethane were treated with sol-
vent purification MB SPS-800 prior to use. Styrene was dried over
CaH2 under stirring for 48 h and distilled before use. The purified
styrene was stored in the refrigerator under nitrogen and used
within a week. Modified methylaluminoxane (MMAO-3A) was pur-
chased from Akzo Chemical as 1.88 M heptane solution.
Molecular weight (Mw and Mn) and molecular weight distribu-
tion (Mw/Mn) of sPS were determined with a PL-220 GPC at 150 ◦C
(using polystyrene calibration, 1,2,4-trichlorobenzene as the sol-
vent at a flow rate of 1.0 mL/min). 1H NMR and 13C NMR spectra
were recorded on a Varian XL-300 MHz and Varian XL-400 MHz
spectrometer. Mass spectra were obtained using a HP5959A spec-
trometer. Elemental analysis was performed by the Analytical
vent at 25 ◦C. X-ray crystallographic data were collected using a
SMART APEXII X-ray diffractometer. Compounds 4d–e were pur-
chased from ACROS, and 4f was purchased from TCI. Compounds 2,
[13] 3, [13] and 5c–e [14a] were prepared according to literature.
2.5 M in hexane, 3.3 mmol) over a 5 min period at −78 ◦C. The
solution was allowed to warm to room temperature and stirred
for 2 h. The resulting solution was added dropwise within 15 min
to TiCl4(THF)2 (1.08 g, 3.3 mmol) in toluene (20 mL) at −78 ◦C with
stirring. The mixture was warmed to room temperature and stirred
overnight. The dark-red solution was filtered, concentrated and
cooled to −30 ◦C to give dark-red solid. Yield: 1.4 g (72%). 1H NMR
(400 MHz, CDCl3): ı (ppm) = 7.40–7.38 (m, 4H), 7.27–7.23 (m, 6H),
6.96 (s, 2H), 4.47 (brs, 4H), 4.44 (s, 4H), 2.24 (s, 3H), 1.97 (brs, 4H).
13C NMR (100 MHz, CDCl3): ı (ppm) = 134.6, 133.9, 130.6, 130.1,
129.8, 128.9, 127.9, 125.9, 76.3, 36.4, 25.5, 20.9. Anal. Calcd for
C25H26Cl3O2S2Ti (576.83): C 52.05, H 4.54; Found: C 51.77, H 4.62.
[2,6-Bis((diisopropylamino)methyl)-4-methylphenolate
Ti(IV)Cl3(THF)] (5b). A same procedure as that for the prepa-
ration of 5a was used. Yield dark-red solid, 2.90 g (61%). 1H NMR
(300 MHz, CDCl3): ı 7.29 (s, 2H), 4.38 (s, 4H), 4.10 (s, 4H), 3.09
(pent, J = 6.5 Hz, 4H), 2.36 (s, 3H), 2.08 (m, 4H), 1.05 (d, J = 6.3 Hz,
24H). 13C NMR (75 MHz, CDCl3): 13C NMR (100 MHz, CDCl3): ı
(ppm) = 162.9, 128.0, 126.4, 124.9, 76.3,49.9, 45.2, 26.8, 22.1, 21.4.
Anal. Calcd for C25H44Cl3N2O2Ti (558.86): C 53.73, H 7.94, N 5.01;
Found: C 52.98, H 8.18, N 4.73.
2.2. Synthesis of ligands and complexes
[2-tert-Butyl-4-methylphenolate Ti(IV)Cl3(THF)] (5e). To a solu-
tion of TiCl4 (0.52 mL, 4.7 mmol) in toluene (20 mL) at −78 ◦C was
added dropwise a solution of 4f (0.77 g, 4.7 mmol) in toluene/THF
(8 mL/1 mL) over 10 min, and the resulting mixture was allowed
to warm to 65 ◦C and stirred for 8 h. After removing the solvent
under reduced pressure, the brown-red solid was collected and
dried in vacuo to give dark-red solid. Yield: 0.74 g (97%) 1H NMR
(400 MHz, CDCl3): ı (ppm) = 7.60 (d, J = 8.0 Hz, 1H), 7.10–7.04 (m,
2H), 4.54 (t, J = 6.8 Hz, 4H), 2.37 (s, 3H), 2.12 (pent, J = 2.8 Hz, 4H),
1.53 (s, 9H). 13C NMR (75 MHz, CDCl3): ı (ppm) = 168.7, 137.6,
136.3, 128.2, 127.1, 126.6, 76.0, 35.0, 30.4, 25.7, 21.4. Anal. Calcd for
2,6-Bis(Phenylthiomethyl)-4-methylphenol (4a). Compound 3
(2.03 g, 10 mmol) in THF (30 mL) was added dropwise to a solution
of benzenethiol (2.10 mL, 20 mmol) and triethylamine (2.80 mL,
20 mmol) in THF (30 mL). After stirring for about 10 h, the solvent
was removed under vacuum. The residue was purified by column
chromatography on silica gel to give the product as a pale-yellow
oil (2.8 g, 80%). 1H NMR (300 MHz, CDCl3): ı (ppm) = 7.35–7.19
(m, 10H), 6.79 (s, 2H), 6.45 (s, 1H), 4.14 (s, 4H), 2.11(s, 3H). 13C
NMR (75 MHz, CDCl3): ı (ppm) = 150.4, 134.9, 130.1, 129.7, 129.1,
128.4, 126.2, 123.1, 34.3, 19.9. HRMS (EI): calcd for C21H20OS2 (M+)
352.0956; found 352.0956.
C15H23Cl3O2Ti (389.57): C 46.25, H 5.95; Found: C 45.86, H 6.30.
2,6-Bis((Diphenylamino)methyl)-4-methylphenol (4b). Com-
pound 3 (5.13 g, 25 mmol) in methanol (60 mL) was added dropwise
to a solution of diphenylamine (8.46 g, 50 mmol) and triethyl-
amine (7.00 mL, 50 mmol) in methanol (30 mL). After stirring 24 h
at room temperature, the precipitated product was filtered and
washed with methanol. White solid was obtained by recrystalliza-
tion from ethyl acetate/petroleum (1/10, v/v). Yield: 7.40 g (63%)
1H NMR (300 MHz, CDCl3): ı (ppm) = 8.90 (s, 1H), 7.27–7.22 (m,
8H), 7.09–7.07 (m, 8H), 7.02–6.97 (m, 4H), 6.87 (s, 2H), 4.87 (s,
4H), 2.13 (s, 3H). 13C NMR (100 MHz, CDCl3): ı (ppm) = 151.7, 148.6,
129.2, 128.7, 127.4, 123.4, 122.5, 121.8, 54.5, 20.8. IR (KBr, cm−1):
3036, 2930, 2064, 2496, 1589, 1490, 1448, 1366, 1246, 1223, 1195,
1153, 1098, 1085, 1074, 1034, 993, 865, 763, 746, 725, 698. MS (EI):
m/z = 470 (M+), 169 (Ph2N). HRMS (EI): calcd for C33H30N2O (M+)
470.2358; found 470.2358.
[2,6-Bis(phenylthiomethyl)-4-methyl-phenolate
Ti(IV)(NMe2)3] (6a). To a solution of Ti(NMe2)4 (0.32 g, 1.42 mmol)
in toluene (5 mL) at −78 ◦C was added dropwise a solution of 4a
(0.50 g, 1.42 mmol) in toluene (8 mL) over 5 min, and the resulting
mixture was allowed to warm up to room temperature and stirred
for 3 h. After removing the solvent under reduced pressure, red
solid was obtained and recrystallized in hexane at −30 ◦C to
give red crystal. Yield: 0.70 g (93%). 1H NMR (400 MHz, C6D6): ı
(ppm) = 7.32–7.30 (m, 4H), 7.04–6.92 (m, 8H), 4.24 (s, 4H), 3.12
(s, 18H), 2.04 (s, 3H). 13C NMR (100 MHz, C6D6): ı (ppm) = 159.2,
138.7, 130.6, 129.3, 129.1, 128.9, 125.8, 125.4, 44.6, 34.3, 20.6.
Anal. Calcd for C27H37N3OS2Ti (531.19): C 61.00, H 7.02, N 7.90;
Found: C 60.78, H 7.02, N 7.54.
2,6-Bis((diphenylamino)methyl)-4-methylphenolate
Ti(IV)(NMe2)3 (6b). The same procedure as that for the prepara-
tion of 6a was used. Yellow crystal 0.49 g (yield: 76%). 1H NMR
(300 MHz, C6D6): ı (ppm) = 7.39 (s, 2H), 7.28–7.08 (m, 17H),
6.85–6.82 (m, 3H), 5.26 (s, 4H), 3.00 (s, 18H), 1.99 (s, 3H). 13C NMR
(100 MHz, C6D6): ı (ppm) = 158.0, 148.9, 129.6, 129.1, 126.6, 126.4,
121.6, 120.9, 53.2, 44.5, 21.4. Anal. Calcd for C39H47N5OTi (649.69):
C 72.10, H 7.29, N 10.78; Found: C 72.16, H 7.56, N 10.59.
[2,6-di-tert-Butyl-4-methylphenolate Ti(IV)(NMe2)3 (6c). The
same procedure as that for the preparation of 6a was used. Yield yel-
low crystal, 0.37 g (92.6%). 1H NMR (400 MHz, C6D6): ı (ppm) = 7.21
(s, 2H), 3.08 (s, 18H), 2.31 (s, 3H), 1.57 (s, 18H). 13C NMR (100 MHz,
C6D6): ı (ppm) = 162.3, 139.6, 127.7, 125.9, 45.4, 35.2, 30.5, 21.5.
Anal. Calcd for C21H41N3OTi (399.44): C 63.15, H 10.35, N 10.52;
Found: C 62.60, H 10.10, N 9.87.
2,6-Bis((Diisopropylamino)methyl)-4-methylphenol
(4c).
Compound 3 (2.03 g, 10 mmol) in THF (30 mL) was added drop-
wise to a solution of diisopropylamine (7.00 mL, 50 mmol) and
triethylamine (4.20 mL, 30 mmol) in THF (30 mL). The solution
was refluxed for 10 h and then cooled to room temperature.
The triethylammonium salts were filtered and the solvent was
removed under vacuum. The residue was purified by column
chromatography on silica gel to give the product as a pale-yellow
solid. Yield: 2.8 g (84%). 1H NMR (300 MHz, CDCl3): ı (ppm) = 6.96
(s, 2H), 3.71 (s, 4H), 3.09 (m, J = 6.6 Hz, 4H), 2.25 (s, 3H), 1.08–1.06
(d, J = 6.0 Hz, 24H). 13C NMR (75 MHz, CDCl3): ı (ppm) = 153.5,
127.1, 126.8, 125.0, 47.8, 45.1, 20.7, 20.1. IR (cm−1): 2958, 2933,
2872, 2810, 1612, 1467, 1383, 1296, 1258, 1225, 1187, 1161, 1078,
1028, 985, 864, 840, 787, 747. MS (EI): m/z = 334 (M+). HRMS (EI):
calcd for C21H38N2O (M+) 334.2984; found 334.2984.
[2,6-Bis((diisopropylamino)methyl)-4-methylphenolate
Ti(IV)Bn3] (7). To a solution of TiBn4 (0.43 g, 1.0 mmol) in toluene
(10 mL) at −78 ◦C was added dropwise a solution of 4c (0.32 g,
1.0 mmol) in toluene (10 mL) over 10 min. The resulting mixture
was allowed to warm to room temperature and stirred for 3 h. The
[2,6-Bis(phenylthiomethyl)-4-methyl-
phenolate]Ti(IV)Cl3(THF) (5a). To a stirred solution of 4a (1.16 g,
3.3 mmol) in toluene (10 mL) was added n-BuLi solution (1.32 mL,