276
R.L. Jones Jr. et al. / Inorganica Chimica Acta 364 (2010) 275–281
Catalysts: W.R. Grace SylopolÒ 5917 was used for comparison.
Metallocene catalysts were purchased from Boulder Scientific
(Boulder CO), or Aldrich; supporting methods have been reviewed
[12] and protocols applied as previously reported [5]. The phen-
oxy-imine catalysts used in these studies were synthesized using
standard methods described in the literature [13,14] with some
modification (described below).
added to the solution. The cooling bath was removed and the
solution was stirred overnight. The solution was pumped dry
in vacuo and the remaining solid was dissolved in CH2Cl2
(50 mL). This solution was filtered through Celite and the filtrate
pumped dry in vacuo. Pentanes (50 mL) were added and the slurry
was stirred rapidly for 2 h. The solid was allowed to settle and
the solution decanted off. This solid was pumped dry leaving a
powder as product (Ti: red, Zr: yellow/orange). Yield = 60–65%;
Typical 1H NMR (Ti complex, isomers): d (ppm) (CDHCl2): 9.06 (s,
2H), 9.3–9.1 (m, 2H), 8.5–7.7 (m, 2H), 4.5–3.2 (m, 12H), 2.5–1.0
(m, 20H).
2.2. Synthesis of FI catalysts
2.2.1. N-(3,5-Diiodo-salicylidene)-2,6-difluoroaniline
3,5-Diiodo-salicylaldehyde (10 g, 27 mmol) and 2,6-difluoroan-
iline (3.5 g, 27 mmol) were added to a 50 mL round bottom flask
affixed with a toluene filled Dean-Stark trap and condenser fitted
with a N2 adapter. Toluene (100 mL) was added to the flask and
the solution was heated to reflux and stirred overnight. The solu-
tion is concentrated to ꢀ25 mL and heptanes (ꢀ150 mL) are added
with stirring to precipitate the product as an orange solid. The solid
was collected by filtration, dried under vacuum and used to make
the complexes. The solid was characterized by GC/MS which had
one peak with a m/z 485. 1H NMR (CDHCl2): d = 14.1 (s, 1H),
d = 8.7 (s, 1H), d = 8.1 (s, 1H), d = 7.6 (s, 1H), d = 7.3 (s, 1H), d = 7.0
(m, 2H).
2.2.5. Hf metal complex
N-(3,5-Diiodo-salicylidene)cycloheptylamine (10 g, 21 mmol)
and THF (100 mL) were added to a Schlenk flask under N2. The
solution was cooled to À78 °C and 2.5 M n-BuLi (9.0 mL, 22.5
mmol) was added dropwise through a septum. The cooling bath
was removed and the yellow solution becomes orange as it was al-
lowed to come to room temperature. The solution was stirred for
2 h and then the THF was removed in vacuo. Anhydrous toluene
(50 mL) was then added to the flask which was cooled to À78 °C.
HfCl4 (6.7 g) was added to the solution. The cooling bath was re-
moved and the solution was stirred overnight. The solution was
pumped dry in vacuo and the remaining solid was dissolved in
CH2Cl2 (50 mL). This solution was filtered through Celite and the
filtrate pumped dry in vacuo. Pentane (50 mL) was added and
the slurry was stirred rapidly for 2 h. The solid was allowed to set-
tle and the solution decanted off. This solid was pumped dry leav-
ing the product as a yellow powder. Yield = 70 %. Typical 1H NMR
(isomers): d (ppm) (CDHCl2): 8.06 (s, 2H), 8.03 (d, 2H), 7.5 (d,
2H), 3.8–3.3 (m, 12H), 2.2–1.2 (m, 20H).
2.2.2. Ti, Zr, Hf metal complexes
N-(3,5-Diiodo-salicylidene)-2,6-difluoroaniline (4.85 g, 0.01
mol) and THF were added to a Schlenk flask under N2. The solution
was cooled to À78 °C and 2.5 M n-BuLi (0.01 mol) was added drop-
wise through a septum. The cooling bath was removed and the yel-
low solution becomes orange as it was allowed to come to room
temperature. The solution was stirred for 2 h and then cooled again
to À78 °C. MCl4 (0.005 mol); (M = Ti, Zr, Hf) was added to the solu-
tion. The cooling bath was removed and the solution was stirred
overnight. The solution was pumped dry in vacuo and the remain-
ing solid was dissolved in CH2Cl2. This solution was filtered
through Celite with the filtrate pumped dry in vacuo. Pentanes
were added and the slurry was stirred rapidly for 2 h. The solid
was allowed to settle and the solution decanted off. The solid
was pumped dry leaving a powder as product (Ti: red, Zr: yel-
low/orange, Hf: yellow). Yield ranged from 40% to 60%. 1H NMR
for Ti complex (isomers: spectral shifts were similar for Zr and
Hf complex; CDHCl2): d = 8.7 (s, 2H), d = 8.2 (m, 2H), d = 7.7 (m,
2H), d = 7.1 (m, 6H).
2.3. Polymerization methods and conditions
Polymerization protocols were similar to those previously de-
scribed [4]. Polymerizations were carried out in a jacketed 4 L
stainless steel stirred tank reactor, 2.5 L of heptane or hexane
was used as the solvent; 0.7 mmol triethyl aluminum (TEAl)
was used as a scavenger. Depending on the system, catalysts
were activated with diethylaluminum chloride (DEAC), triisobu-
tyl aluminum (TiBAl), or methylalumoxane (MAO) at the levels
indicated in the tables. Temperature was thermostatically con-
trolled as indicated; pressure remained constant during the cam-
paign (at levels indicated) with continuous monomer feeding.
Co-monomers used in these studies were purchased from Al-
drich or Boulder Scientific and used without further purification.
In all cases co-monomers were charged to the reactor during ini-
tial loading of the reactor (prior to catalyst loading): no addi-
tional co-monomer was added during the polymerization
campaign.
In a typical campaign, the reactor was heated to above 90 °C and
purged with nitrogen for a minimum of 30 min prior to cooling un-
der positive nitrogen pressure. Solvent (heptane) was added fol-
lowed by co-monomer (hexene) and scavenger. The temperature
was set at the desired set-point then polymerization grade ethyl-
ene gas was added to run pressure. Catalyst and activator solution
(prepared in a nitrogen dry box) were injected using a pressurized
stainless steel syringe pump or from a cylinder using nitrogen
pressure.
2.2.3. N-(3,5-Diiodo-salicylidene)cycloheptylamine (see Fig. 1)
3,5-Diiodo-salicylaldehyde (37.3 g, 100 mmol) and cycloheptyl-
amine (11.3 mL, 100 mmol) were added to a 1 L round bottom
flask. Pentanes (300 mL) and molecular sieves were added. The
solution was stirred at room temperature for 4 h and then filtered.
The yellow solid was dissolved in pentane and the resulting slurry
was filtered. The filtrates were combined and concentrated on the
rotovap leaving the product as a bright yellow solid that was fur-
ther dried in vacuo. The solid was characterized by GC/MS which
had one peak with a m/z = 469; 1H NMR (CDHCl2): d = 15.3 (s,
1H), d = 8.25 (s, 1H), d = 7.9 (s, 1H), d = 7.75 (d, 1H), d = 3.9–3.3
(m, 1H), d = 2.5–1.2, (m, 12H).
2.2.4. Ti and Zr metal complexes
N-(3,5-Diiodo-salicylidene)cycloheptylamine (10 g, 21 mmol)
and THF (100 mL) were added to a Schlenk flask under N2. The
solution was cooled to À78 °C and 2.5 M n-BuLi (9 mL, 22.5 mmol)
was added dropwise through a septum. The cooling bath was re-
moved and the yellow solution became orange as it was allowed
to come to room temperature. The solution was stirred for 2 h
and then cooled again to À78 °C. MCl4 (21 mmol, M = Ti, Zr) was
Molecular weight of the polymers was calculated from the
intrinsic viscosity (ASTM D4020); comonomer composition was
measured using FTIR (see ASTM D5576, D6248 and references
therein). 13C-MAS-NMR was carried out by Acorn NMR Inc. (Liver-
more, CA).