of 72
1
Supporting Information for
Acrylate
-
Induced
β
-
H Elimination in
Coordination
Insertion
Cop
olymerization
Catalyzed by Nickel
Shuoyan Xiong
a
, Alexandria Hong
a
,
Priyabrata Ghana
a
,
Brad C. Bailey
b
, Heather A. Spinney
b
, Hannah
Bailey
b
, Briana S. Henderson
b
, Steve Marshall
b
, Theodor Agapie*
a
*
To whom correspondence should be addressed, E
-
mail: agapie@caltech.edu
a
Division of Chemistry and Chemical Engineering, California Institute of
Technology, Pasadena, California 91125, United States.
b
Chemical Science, Core R&D, The Dow Chemical Company, Midland, Michigan 48667.
1. Procedures for synthesis of ligands and metal complexes
S2
2. Topographical analyses
S5
3. Procedures for polymerization and polymer characterization
S7
4. Supplemental data for ethylene/tBA copolymerization
S11
5. Characterization of ethylene/tBA copolymers
S1
6
6
.
Catalyst comparison
S
19
7
. Investigations of acrylate
-
induced reactions
S
2
2
8
. Quantitative kinetic studies of acrylate
-
induced reactions S
4
7
9
. Discussion of
pathways of
β
-
H elimination S
5
6
10
. Cryst
al
lographic information
S
5
9
1
1
. NMR spectra of ligands and organometallic complexes S
6
3
References
S
6
8
2
1
.
Procedures for Synthesis of Ligands and Metal Complexes
1.
1
.
General Considerations
All air
-
and water
-
sensitive compounds were manipulated under N
2
or Ar
using standard Schlenk or glovebox
techniques. The solvents for air
-
and moisture
-
sensitive reactions were dried over sodium benzophenone/ketyl,
calcium hydride, or by the method of Grubbs.
1
Deuterated solvents were purchased from Cambridge Isotopes
Lab, Inc.; C
6
D
6,
was dried over a purple suspension wi
th Na/benzophenone ketyl and vacuum transferred. t
-
Butyl acrylate was dried over 4 Å sieves for greater
than 72h.
2.5 M
n
BuLi in hexanes were purchased from
Sigma
-
Aldrich
and
used
without
further
purification.
1,3
-
D
ibromo
-
5
-
(tert
-
butyl)
-
2
-
(methoxymethoxy
)benzene,
2
b
is(dimethoxyphenyl)phosphine chloride,
3
b
is(di
phen
oxyphenyl)phosphine
chloride,
4
py
2
Ni(CH
2
SiMe
3
)
2
5
and
2
-
bromo
-
4
-
tertbutyl
-
5
-
bis(dimethoxyphenyl)phosphino)phenol
6
were
synthesized according to literature procedures. All
1
H,
13
C, and
31
P spectra of organic and organometallic
compounds were recorded on Varian INOVA
-
400, or Bruker Cryopr
obe 400 spectrometers.
1
H and
13
C
chemical shifts are reported relative to residual solvent resonances.
1
.2
.
Synthesis of Ligands and Metal Complexes
Ligand
P
hO
P
OBrH
:
A Schlenk flask fitted with a screw
-
in Teflon stopper was charged with a solution of
1,3
-
dibromo
-
5
-
(tert
-
butyl)
-
2
-
(methoxymethoxy)benzene (3.52 g, 10.0 mmol) in THF (40 mL) and cooled to
-
78
°C
under nitrogen. A hexane solution of
n
-
butyllithium (4 mL, 2.5 M, 10.0 mmol) was added dropwise via syringe.
After stirring for an additional 30 mi
n at
-
78
°C
, a solution of bis(2,6
-
di
phenoxy
phenyl)phosphine chloride (
5.89
g,
10.0 mmol) in THF (20 mL) was added dropwise via cannula. After complete addition, the reaction was allowed
to warm up to room temperature and stirred for an additional 3 h, yiel
ding a yellow solution. The
solution was
then concentrated to ~20 mL and
degassed MeOH (10 mL)
and
concentrated aqueous HCl (
10
mL
, degassed by
three freeze
-
pump
-
thaw cycles
with a liquid nitrogen bath
prior to usage
)
were added
. After stirring for
12
h un
der
room temperature, volatiles were removed under vacuum. In a N
2
-
filled glovebox (no exclusion of water), the
resulting yellow residue was taken up in CH
2
Cl
2
(
2
0 mL), washed with saturated aqueous solutions of K
2
CO
3
(3 x
3
10 mL) and NH
4
Cl (3 x 10 mL), dri
ed over MgSO
4
, and filtered through Celite. The volatiles were removed under
reduced pressure. In a glovebox (exclusion of water and oxygen), the resulting pale
-
yellow solid was
was washed
by
cold pentane
(3 x
20
mL)
, then
dissolved in
Et
2
O
and filtered through Celite. The volatile materials were
removed once more under vacuum,
yielding
P
hO
POBr
H
(
3.82
g,
95% purity
) as
gel
-
like
solids
.
This material was
then used in metalation as the proligand without further purification.
1
H NMR (400 MHz, C
6
D
6
,
note: only resonances
assigned to protons of the desired product
were
listed
):
δ
7.69 (dd,
J
= 9.7, 2.3 Hz, 1H
, ArH
), 7.33 (d,
J
= 2.3 Hz, 1H
, ArH
),
6.98
6.92 (m,
8
H
, ArH
), 6.85
6.75 (m, 12H
, ArH
), 6.72
6.64 (m,
3
H
, ArH + ArOH
), 6.44 (dd,
J
= 8.2
, 2.8
Hz, 4H
, ArH
), 0.99 (s,
9
H
,
-
Si(CH
3
)
3
)
;
31
P{
1
H} NMR (1
62
MHz, C
6
D
6
):
δ
-
5
1
.
70
(s).
Complex
1
Ph
:
In the glove box, to a solution of Py
2
Ni(CH
2
SiMe
3
)
2
(
44
mg, 0.
119
mmol) in benzene (
4
ml) in a
vial was added a solution of
PhO
POBr
H
(
92.9
mg, 0.
119
mmol) in benzene (
8
ml). The mixture was stirred for 2
h under room temperature, forming a red
-
brown solution. Volatile materials were removed under vacuum
. T
he
residue was extracted with
pentane (
3 x
5
mL)
, then
washed by
cold
pentane
(3 x
15
mL)
, pentan
e
(3 x
5
mL)
and
hexanes (3 x
2
mL)
,
T
he solid was collected via vacuum filtration,
and redissolved in Et
2
O,
filtered through Celite.
The volatile materials were removed once more under vacuum, yielding
spectroscopically
pure
1
Ph
(
50
mg,
45
%)
as
yellow
-
orange
solid
s
.
1
H NMR (400 MHz, C
6
D
6
):
δ
8.76 (dd,
J
= 4.9, 1.6 Hz,
2
H
, ArH
), 7.71
7.65 (m,
1
H
,
ArH
), 7.51 (d,
J
= 2.3 Hz,
1
H
, ArH
), 7.12
7.07 (m,
8
H
, ArH
), 7.06
6.99 (m,
8
H
, ArH
), 6.88
6.79 (m,
5
H
,
ArH
), 6.77
6.70 (m,
2
H
, ArH
), 6.56
6.4
8 (m,
5
H
, ArH
), 0.90 (s,
9
H
,
-
t
Bu
),
-
0.00 (s,
9
H
,
-
SiMe
3
),
-
0.61 (d,
J
=
9.8 Hz,
2
H
,
NiCH
2
Si
).
13
C{
1
H} NMR (101 MHz, C
6
D
6
):
δ
168.74 (d,
J
= 25.2 Hz,
1C, ArC
),
160.01
(s,
4
C
,
ArC),
155.86
(s,
4
C, ArC)
, 151
.68
(s, 2C, ArC)
,
136.44
(s, 1C, ArC)
,
135.97 (d,
J
= 7.6 Hz
, 1C, ArC
),
132.80
(s,
1
C, ArC)
,
130.45
(s, 2C, ArC)
,
129.92
(s, 8C, ArC)
,
128.59
(s,
1
C, ArC)
,
126.45 (d,
J
= 2.8 Hz
,
1
C, ArC
),
124.06
(s,
4
C, ArC)
,
123.27
(s, 2C, ArC)
,
123.20 (d,
J
= 52.4 Hz, 1C, ArC),
120.56
(s, 8C, ArC)
,
114.06 (d,
J
= 44.4 Hz
, 2C, ArC
), 110
.72
(d,
J
= 4.0 Hz
, 4C, ArC
),
33.73
(s, 1C,
-
C
(CH
3
)
3
)
, 31.65
(s, 3C,
-
C
(
C
H
3
)
3
)
, 2.64
(s,
3
C,
SiMe
3
)
,
-
16.11 (d,
J
= 27.2
Hz
,
1
C, NiCH
2
Si
)
;
31
P{
1
H} NMR (121 MHz, C
6
D
6
):
δ
-
2.49
(
s
,
1
P
)
.
Anal. Calcd(%)
for C
5
5
H
53
BrNNiO
5
PSi
: C,
65.69
; H,
5.31
; N, 1.
39
. Found(%): C,
66.12
; H,
5.40
; N, 1.1
1
.
Complex
1
Me
:
In the glove box, to a solution of Py
2
Ni(CH
2
SiMe
3
)
2
(
44
mg, 0.
119
mmol) in benzene (
4
ml) in a
vial was added a solution of
Me
O
POBr
H
(
63.3
mg, 0.
119
mmol) in benzene (
8
ml). The mixture was stirred for 2
4
h under room temperature, forming a red
-
brown solution. Volatile materials were removed under vacuum
. T
he
residue was extracted with
pentane (
3 x
5
mL)
, then
washed by
pentane
(3 x
1
0
mL)
,
hexanes (3 x
5
mL)
and Et
2
O
(2
x
2 mL).
T
he solid was collected via vacuum filtration,
and redissolved in
benzene
,
filtered through Celite. The
volatile materials were removed once more under vacuum, yielding
1
Me
(
50
mg,
45
%) as
brown
solid
s
.
1
H NMR
(400 MHz, C
6
D
6
):
δ
9.19 (d,
J
= 6.5 Hz, 2H
, ArH
), 7.68 (d,
J
= 2.3 Hz,
1
H
, ArH
), 7.62 (dd,
J
= 11.1, 2.4 Hz,
1
H
,
ArH
), 7.10 (t,
J
= 8.3 Hz,
2
H
, ArH
), 6.93
6.81 (m,
1
H
, ArH
), 6.60 (t,
J
= 7.3 Hz,
2H, ArH
), 6.28 (dd,
J
= 8.3,
3.7 Hz,
4
H
, ArH
), 3.27 (s,
12
H
,
-
OCH
3
), 1.13 (s,
9
H
,
-
t
Bu
),
-
0.13 (s,
9
H
,
-
SiMe
3
),
-
0.59 (d,
J
= 9.2 Hz,
2
H
,
NiCH
2
Si
).
13
C{
1
H} NMR (101 MHz, C
6
D
6
):
δ
168.17 (d,
J
= 24.5 Hz
,
2
C, ArC
), 161.73
(s, 4C, ArC)
, 151.60
(s, 2C, ArC)
,
136.61
(s, 1C, ArC)
, 135.60 (d,
J
= 7.4 Hz
, 1C, ArC
), 131.52
(s, 1C, ArC),
130.81
(s,
2
C, ArC)
, 128.60
(s,
1
C, ArC)
,
126.33 (d,
J
= 2.8 Hz
, 1C, ArC
), 123.75
(s,
2
C, ArC)
, 112.74 (d,
J
= 15.2 Hz
, 1C, ArC
), 110.85 (d,
J
= 48.5 Hz
, 1C,
ArC
), 104.69 (d,
J
= 4.6 Hz
, 4C, ArC
), 55.51
(s, 4C,
-
OMe)
, 33.81
(s, 1C,
-
C
(CH
3
)
3
)
, 32.02
(s, 3C,
-
C
(
C
H
3
)
3
)
,
2.30
(s, 3C,
SiMe
3
)
,
-
17.74 (d,
J
= 30.0 Hz
, 1
C, NiCH
2
Si
)
;
31
P{
1
H} NMR (121 MHz, C
6
D
6
):
δ
-
5.08
(
s
,
1
P
)
.
Anal.
Calcd(%)
for C
35
H
45
BrNNiO
5
PSi
: C,
55.50
; H,
5.99
; N, 1.
85
. Found(%): C,
55.02
; H,
5.77
; N, 1.
72
.
5
2
.
Topographical Analyses
Results
Figure S1.
Topographical steric maps with %V
bur
of
POP
-
Ni
(left),
1
Me
(middle
),
and
1
Ph
(right)
. The Ni atom defines
the origin of xyz
coordinate system. Only the P,O
-
ligand included in calculation and steric visualization. Blue indicates
occupied space in the
-
z direction (toward back as drawn in a), where the phosphine
-
phenoxide ligands are located, and
red indicates +z direction. See
section S
3
for more details.
Details for topographical analyses
.
Topographical maps of
PO
P
-
Ni
,
1
Me
, and
1
Ph
and corresponding percent buried
volume data (%V
bur
) were generated by Cavallo's SambVca 2.1 (Salerno molecular buried volume calculation)
program.
7
-
10
More details for %V
bur
calculation and steric maps:
1) The nickel atom (Ni1) de
fines the center of the xyz coordinate system,
2)
Ni(PEt
3
)Ph fragment was excluded
;
3) Bondi radii was scaled by 1.17;
9
4) Mesh spacing for numerical integration was 0.10;
5) Sphere radius was set to 3.5
Å;
6) H atoms were excluded.
x
y
P
O
x
y
P
O
x
y
P
O
3.00
1.50
0
-
1.50
-
3.00
Å
1
Å
%V
bur
48.3
48.1
49.4
MeO
PO
Br
-
Ni
PhO
PO
Br
-
Ni
POP
-
Ni
6
7)
xz
-
P
lane was defined as shown in the figure below and the
y
-
axis was defined by the right
-
hand rule
(for
POP
-
Ni
) or the reverse (for the other two). This is to ensure
the larger axial shielding locates on the top
for easier
comparison
. Note that for a specific complex, the %Vbur remained the same with Ni1 in the origin even the xyz
coordination system rotated or flipped.
P1
O1
Ni1
C1
N1
C2
C3
O2
x
z
y
7
3
.
Procedures for
P
olymerization and
P
olymer
C
haracterization
3
.1.
General
procedure for high throughput parallel polymerization reactor (PPR) runs
.
Polyolefin catalysis screening was perfor med in a high throughput parallel polymerization reactor (PPR)
system. The PPR system was comprised of an array of 48 single cell (6 x 8 mat
rix) reactors in an inert
atmosphere glovebox. Each cell was equipped with a glass insert with an internal working liquid volume of
approximately 5 mL. Each cell had independent controls for pressure and was continuously stirred at
5
00
rpm.
Catalyst soluti
ons were prepared in toluene. All liquids (i.e., solvent, tBA, and catalyst solutions) were added via
robotic syringes. Gaseous reagents (i.e., ethylene) were added via a gas injection port. Prior to each run, the
reactors were heated to 50 °C, purged with
ethylene, and vented.
All desired cells were injected with
a solution of
tBA
in toluene
followed with a portion of toluene (This step
was skipped for ethylene homopolymerization).
Note
:
tBA was purified by pass
aging a plug of activated alumina
prior to use.
The
reactors were heated to the run temperature and then pressured to the appropriate psig with
ethylene. Catalyst solutions were then added to the cells. Each catalyst addition was chased with a small amount
of toluene so that after the final addition, a total reaction volume of 5 mL was reached. Upon addition of the
catalyst, the PPR software began monitoring the pressure of each cell. The desired pressure (within
approximately 2
-
6 psig) was maintained by th
e supplemental addition of ethylene gas by opening the valve at
the set point minus 1 psi and closing it when the pressure reached 2 psi higher. All drops in pressure were
cumulatively recorded as “Uptake” or “Conversion” of the ethylene for the duration o
f the run or until the
uptake or conversion requested value was reached, whichever occurred first. Each reaction was then quenched
by addition of 1% oxygen in nitrogen for 30 seconds at 40 psi higher than the reactor pressure. The pressure
of each cell was
monitored during and after the quench to ensure that no further ethylene consumption
happens. The shorter the “Quench Time” (the
durat
ion between catalyst addition and oxygen quench), the
more active the catalyst. In order to prevent the formation of too
much polymer in any given cell, the reaction
was quenched upon reaching a predetermined uptake level of 80 psig
for copolymerization reactions (60 psig
for ethylene homopolymerization)
. After all the reactors were quenched, they were allowed to cool to abo
ut 60
8
°C. They were then vented, and the tubes were removed. The polymer samples were then dried in a centrifugal
evaporator at 60 °C for 12 hours, weighed to determine polymer yield and used in subsequent IR (tBA
incorporation), GPC
,
DSC and NMR (copolyme
r microstructures) analysis.
3
.2.
General procedure for batch reactor runs for preparation of ethylene/tBA copolymers
.
Polymerization reactions were conducted in a 2
-
L Parr batch reactor. The reactor was heated by an electrical
heating mantle and cooled b
y an internal serpentine cooling coil containing cooling water. The water was pre
-
treated by passing through an Evoqua water purification system. Both the reactor and the heating/cooling
system were controlled and monitored by a
LabVIEW
process computer. The bottom of the reactor was fitted
with a dump valve, which empties the reactor contents into a lidded dump pot, which was prefilled with a
catalyst
-
kill solution (typically 5 mL of an Irgafos / Irganox / toluene mixture). The lidded d
ump pot was
vented to a 15
-
gal. blowdown tank, with both the pot and the tank N
2
purged. All chemicals used for
polymerization or catalyst makeup are run through purification columns to remove any impurities that may
affect polymerization. The toluene was
passed through two columns, the first containing A2 alumina, the
second containing Q5 reactant. The tert
-
butyl acrylate was filtered through activated alumina. The ethylene was
passed through two columns, the first containing A204 alumina and 4 Å molecular
sieves, the second containing
Q5 reactant. The N2 used for transfers was passed through a single column containing A204 alumina, 4 Å
molecular sieves and Q5 reactant.
The reactor was loaded first from the shot tank that contained toluene and
tB
A. The shot
tank was filled to
the load set points by use of a differential pressure transducer. After solvent/acrylate addition, the shot tank
was rinsed twice with toluene. Then the reactor was heated up to the polymerization temperature set point. The
ethylene was
added to the reactor when the reaction temperature was reached to maintain the reaction pressure
set point. Ethylene addition amounts were monitored by a micro
-
motion flowmeter.
The catalysts were handled in an inert atmosphere glovebox and were prepared
as a solution in toluene. The
catalyst was drawn into a syringe and pressure
-
transferred into the catalyst shot tank. This was followed by 3
rinses of toluene, 5 mL each. Catalyst was added when the reactor pressure set point was reached.
9
Immediately after
catalyst addition the run timer was started. Ethylene was then added by the
LabVIEW
controller
to maintain reaction pressure set point in the reactor. These polymerizations were run for
60
min or
until 40 g of ethylene uptake. Then the agitator was stoppe
d, and the bottom dump valve was opened to empty
reactor contents into the lidded dump pot. The lidded dump pot was
closed,
and the contents were poured into
trays placed in a lab hood where the solvent was evaporated off overnight. The trays containing th
e remaining
polymer were then transferred to a vacuum oven, where they were heated up to 140 °C under vacuum to remove
any remaining solvent. After the trays cooled to ambient temperature, the polymers were weighed for
yield/efficiencies and submitted for
polymer testing if so desired.
3
.3.
P
rocedure for
g
el permeation chromatography (GPC)
.
High temperature GPC analysis was performed using a Dow Robot Assisted Delivery (RAD) system
equipped with a Polymer Char infrared detector (IR5) and Agilent PLgel
Mixed A columns. Decane (10
μ
L)
was added to each sample for use as an internal flow marker. Samples were first diluted in 1,2,4
-
trichlorobenzene
(TCB) stabilized with 300 ppm butylated hydroxyl toluene (BHT) at a concentration of 10 mg/mL and
dissolved b
y stirring at 160°C for 120 minutes. Prior to injection the samples are further diluted with TCB
stabilized with BHT to a concentration of 3 mg/mL. Samples (250
μ
L) are eluted through one PL
-
gel 20
μ
m
(50 x 7.5 mm) guard column followed by two PL
-
gel 20
μ
m
(300 x 7.5 mm) Mixed
-
A columns maintained at
160 °C with TCB stabilized with BHT at a flowrate of 1.0 mL/min. The total run time was 24 minutes. To
calibrate for molecular weight (MW) Agilent EasiCal polystyrene standards (PS
-
1 and PS
-
2) were diluted with
1.5 mL TCB stabilized with BHT and dissolved by stirring at 160 °C for 15 minutes. These standards are
analyzed to create a 3rd order MW calibration curve. Molecular weight units are converted from polystyrene
(PS) to polyethylene (PE) using a daily Q
-
fac
tor calculated to be around 0.4 using the average of 5 Dowlex
2045 reference samples.
3
.4.
P
rocedure for
f
ourier
-
transform infrared spectroscopy (FTIR)
.
The 10 mg/mL samples prepared for GPC analysis are also utilized to quantify tert
-
butyl acrylate (tBA)
incorporation by Fourier Transform infrared spectroscopy (FTIR). A Dow robotic preparation station heated
10
and stirred the samples at 160°C for 60 minutes then deposited 130
μ
L portions into stainless wells promoted
on a silicon wafer. The TCB was evapora
ted off at 160°C under nitrogen purge. IR spectra were collected
using a Nexus 6700 FT
-
IR equipped with a DTGS KBr detector from 4000
-
400 cm
-
1 utilizing 128 scans with
a resolution of 4. Ratio of tBA (C=O: 1762
-
1704 cm
1) to ethylene (CH2: 736
-
709 cm
1)
peak areas were
calculated and fit to a linear calibration curve to determine total tBA.
3
.5.
Differential scanning calorimetry (DSC)
.
Differential scanning calorimetry analyses was performed on solid polymer samples using a TA Instruments,
Inc. Discovery
Series or TA Instruments, Inc., DSC2500, programmed with the following method:
Equilibrate
at 175.00 °C
;
Isothermal for 3 minutes
;
Ramp 30.00 °C/min to 0.00 °C
;
Ramp 10.00 °C/min to 175.00 °C
;
Data was analyzed using TA Trios software.
3
.6.
NMR
characterization
.
NMR spectra of ethylene/tBA copolymers were recorded on a Bruker 400 MHz using o
-
dichlorobenzene at
120 °C.
1
H NMR analysis of copolymers were done using a relaxation time (0.2 s), and an acquisition time (1.8
s) with the number of FID’s
collected per sample (512).
13
C{
1
H} NMR analysis of copolymers were done using
90° pulse of 17.2
μ
s, a relaxation time (22.0 s), an acquisition time (5.3 s), and inverse
-
gated decoupling with
the number of FID's collected per sample (1536). Analysis of th
e spectra was based on literature.
11
-
12
11
4
.
Supplemental Data for Ethylene/tBA Copolymerization
4
.1. Analysis of
turnover frequency of acrylate (
TOF
tBA
)
As shown
in
T
able
2
,
1
Ph
produces copolymers with lower acrylate incorporation compared to
1
Me
. However,
the former actually features a significantly higher turnover frequency of acrylate (TOF
tBA
) compared to the latter
under otherwise identical conditions (e.g. entry 2 vs 6, or 3 vs 7, or 8 vs 9). It's also notable that the temperature
shows significant impact on TOF
tBA
while the impact of tBA concentration is moderate.
4
.2. Supplemental ethylene
/acrylate copolymerization results.
Tabl e
S
1
.
Catalysis results for
Figure 5
and Table S
3
.
Entry
a
catalyst
T
/
ºC
E/psi
A
A/
M
Act.
b
Mw
c
Đ
%Mol A
Tm (ºC)
1
d
PO
P
-
Ni
90
400
tBA
0.05
660
55.1
2.2
2.1
111
2
1
Me
90
400
tBA
0.05
15
50
73.3
2.4
1.5
115
3
1
Ph
90
400
tBA
0.05
21
000
38.5
2.3
0.3
126
4
e
1
Ph
90
400
tBA
0.15
57
00
30.0
2.3
1.0
120
5
1
Ph
90
200
tBA
0.15
910
21.9
2.1
1.5
118
6
1
Ph
110
200
tBA
0.05
8300
15.9
2.4
0.7
123
[a] V = 5 mL, [Catalyst] = 0.05 mM
, ethylene pressure = 400 psi, toluene solvent; each entry represents multiple replicated runs (see
section
S3
for detailed procedure and
Table
S4
for original data). [b] Activity in kg/(mol
·
h). [c] kg/mol. [d] Reported in ref
1
. [e] Also
included in
T
able
1
as entry
8
.