Large ultra-high molecular weight polyethylene spherical particles produced by AlR3 activated half-sandwich chromium(iii) catalysts

Article abstract of DOI:10.1039/c1dt10659g

A series of half-sandwich pentamethylcyclopentadienyl chromium(iii) complexes bearing a salicylaldiminato ligand, Cp*[2-R¹-4-R ²-6-(CHNR³)C₆H₂O]CrCl [R¹ = ⁱPr (1, 4), ^tBu (2, 3, 5), Ad (6); R² = H (1, 2, 3), ^tBu (4, 5, 6); R³ = ⁱPr (1, 2, 5, 6), ^tBu (3, 4)], were synthesized. All complexes were characterized by elemental analyses and the structures of complexes 1-4 and 6 were determined by X-ray diffraction analysis. These complexes adopt a pseudo-octahedral coordination environment with a three-legged piano stool geometry. Upon activation with a small amount of AlR₃, complexes 1-6 all catalyze the polymerization of ethylene in a quasi living fashion with good to high catalytic activity under mild conditions and produce ultra-high molecular weight polyethylene as spherical particles with a diameter of 1-6 mm. The catalytic activity of these complexes and the molecular weight of the produced polyethylene can be tuned in a broad range by changing the R¹, R ², and R³ groups as well as the AlR₃ cocatalyst. It was found that complex 6 with R¹ = Ad, R² = ^tBu, and R³ = ⁱPr shows the highest catalytic activity and produces polyethylene with the highest molecular weight. The Royal Society of Chemistry 2011.

Full text of DOI:10.1039/c1dt10659g

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PAPER
Large ultra-high molecular weight polyethylene spherical particles produced
by AlR3 activated half-sandwich chromium(III) catalysts†
Mingtai Sun,a Tieqi Xu,a,b Wei Gao,a Yang Liu,a Qiaolin Wu,a Ying Mu*a and Ling Yea
Received 14th April 2011, Accepted 22nd July 2011
DOI: 10.1039/c1dt10659g
A series of half-sandwich pentamethylcyclopentadienyl chromium(III) complexes bearing a
i
salicylaldiminato ligand, Cp*[2-R1-4-R2-6-(CH NR3)C6H2O]CrCl [R1 = Pr (1, 4), tBu (2, 3, 5), Ad
i
(6); R2 = H (1, 2, 3), tBu (4, 5, 6); R3 = Pr (1, 2, 5, 6), tBu (3, 4)], were synthesized. All complexes were
characterized by elemental analyses and the structures of complexes 1–4 and 6 were determined by
X-ray diffraction analysis. These complexes adopt a pseudo-octahedral coordination environment with
a three-legged piano stool geometry. Upon activation with a small amount of AlR3, complexes 1–6 all
catalyze the polymerization of ethylene in a quasi living fashion with good to high catalytic activity
under mild conditions and produce ultra-high molecular weight polyethylene as spherical particles with
a diameter of 1–6 mm. The catalytic activity of these complexes and the molecular weight of the
produced polyethylene can be tuned in a broad range by changing the R1, R2, and R3 groups as well as
t
i
the AlR3 cocatalyst. It was found that complex 6 with R1 = Ad, R2 = Bu, and R3 = Pr shows the highest
catalytic activity and produces polyethylene with the highest molecular weight.
and some other single-site catalysts. Thus, there is a great need
Introduction
to develop new metallocene and other single-site catalyst systems
which can provide equivalent catalytic activity and polymer prop-
erties with no need for large amounts of expensive cocatalyst.2c,12
Among the homogeneous chromium-based catalysts with various
ligands, the monocyclopentadienyl chromium(III) complexes with
a pendant nitrogen-donor, such as dialkylamino, quinolinyl,
N,N-dimethylanilinyl, alkylamido, pyridyl, imidazolin-imino, and
isopropylimino have been extensively studied for ethylene homo-
or co-polymerization.13 To our knowledge, a few half-sandwich
type chromium catalyst systems have been reported to show
reasonable catalytic activities for ethylene polymerization in the
presence of aluminum alkyls. In 1998, Jolly and co-workers
reported the Cp*Cr(acac)Cl/Et3Al (Al/Cr = 300) system showing
a catalytic activity of 4.2 ¥104 g polyethylene (PE) mol Cr-1
h-1 under 50 atm of ethylene at room temperature.14 Later in
2004, a similar catalyst system, Cp*Cr(C6F5)(N3-Bz)/Et3Al (Bz =
benzyl, Al/Cr = 90), was reported by Gabbai et al.15 to produce
oligomers with a catalytic activity of 2.1 ¥ 105 g PE mol Cr-1
h-1 under 1.1 atm of ethylene at room temperature. Recently,
our group reported a new half-sandwich type of chromium(III)
catalyst systems, Cp*Cr[2,4-tBu2-6-(CH NR)-C6H2O]Cl/AlR¢3
Since Kaminsky and Sinn’s initial discovery that extremely ac-
tive catalysts for olefin polymerization can be obtained when
titanocene and zirconocene complexes are combined with a hy-
drated form of trimethylaluminum-methylaluminoxane (MAO),1
intensive research works have been focused on developing
new metallocene catalysts for improving catalytic activities and
polymer properties.2,3 Metallocene catalysts and related other
single-site catalysts have allowed the preparation of a wide
array of high performance polyolefin products, including highly
isotactic,4 syndiotactic,5 and atactic6 polypropylene, linear high-
density polyethylene,7 linear low-density polyethylene,8 syndiotac-
tic polystyrene,9 ethylene/styrene copolymers10 and cyclo-olefin
copolymers.11 However, metallocene catalysts have to be activated
with large amounts of MAO or expensive fluorinated borates,
such as Ph3C+B(C6F5)4 and Ph3C+B[C6H3(CF3)2]4 , to achieve
high catalytic activities. For some olefin polymerization systems,
the cost of the cocatalyst is more than that of the catalyst. In fact,
the high cost of MAO and the fluorinated borate cocatalysts has
in some extent limited the industrial application of metallocene
-
-
t
[R = Bu, Ph, 2,6-iPr2C6H3; R¢ = Me, Et, iBu], which show excellent
aState Key Laboratory for Supramolecular Structure and Materials, School
of Chemistry, Jilin University, 2699 Qianjin Street, Changchun, 130012,
People’s Republic of China. E-mail: ymu@jlu.edu.cn; Fax: (86)-431-
85193421; Tel: (86)-431-85168376
catalytic properties for ethylene polymerization and produce high
molecular weight polyethylene (Mh = 1.00–1.45 ¥ 106 g mol-1)
in high catalytic activity (~ 4.0 ¥106 g PE mol Cr-1 h-1) upon
activation with only a small amount of AlR3 (Al/Cr ª 25).16
Jin et al. also reported some similar half-sandwich chromium(III)
complexes bearing b-ketoiminato, b-diketiminato and hydrox-
yindanimine ligands which exhibit good catalytic activities
bDepartment of Chemistry, Dalian University of Technology, Dalian 116023,
People’s Republic of China
† CCDC reference numbers 756686 (1), 756687 (2), 756688 (3), 756690 (4)
and 756691 (6). For crystallographic data in CIF or other electronic format
see DOI: 10.1039/c1dt10659g
10184 | Dalton Trans., 2011, 40, 10184–10194
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The Royal Society of Chemistry 2011
©

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(~1.5 ¥105 g PE mol Cr-1 h-1) for ethylene polymerization in
the presence of a small amount of triethylaluminium.17 We have
now carried out further investigations on the half-sandwich sali-
cylaldiminato chromium(III) catalyst systems, and obtained more
interesting results. Especially, these catalyst systems were found to
catalyze the polymerization of ethylene in a quasi living fashion
and produce ultrahigh molecular weight polyethylenes as spherical
particles with a diameter of 1–6 mm. To the best of our knowledge,
it is unprecedented for polyethylene to be produced as such large
spherical particles with unsupported catalysts. Herein we report
the detailed results on the synthesis and structural characterization
of the chromium(III) complexes of this type and their catalytic
performance in the ethylene polymerization reaction, as well as
the characterization of the obtained polyethylenes.
yields were lower than those for the reactions with the in situ
formed Cp*CrCl2(THF) as the starting material. All chromium
complexes 1–6 were characterized with elemental analyses and
the structures of complexes 1–4 and 6 were determined by X-
ray diffraction analysis. The free salicylaldimine ligands HL1–
HL6 were all characterized with elemental analyses and 1H NMR
spectroscopy.
Crystal structures
Single crystals of complexes 1–4 and 6 suitable for X-ray diffrac-
tion studies were obtained from either n-hexane–dichloromethane
or n-hexane–chloroform mixed solvent. The crystal structures
of these complexes have been determined by X-ray diffraction
analysis. The ORTEP drawings of the complexes 1–4 and 6
are shown in Fig. 1–5, respectively, and the selected bond
lengths and angles of these complexes are listed in Table 1.
For comparison purpose, the corresponding bond lengths and
angles of previously communicated complexes Cp*Cr[2,4-tBu2-6-
Results and discussion
Synthesis and characterization
t
(CH NR)-C6H2O]Cl [R = Bu (7), Ph (8), 2,6-iPr2C6H3 (9)]16 are
A series of new half-sandwich pentamethylcyclopentadienyl
chromium(III) complexes bearing a salicylaldiminato ligand,
also given in Table 1. X-Ray crystallographic analysis† reveals
that all these complexes have a pseudo-octahedral coordination
environment in their solid state structures and adopt a three-
legged piano stool geometry with the O, N, Cl atoms being the
three legs and the Cp* ring being the seat. In these complexes,
the Cr–C bond lengths are in line with those observed in related
monocyclopentadienyl13,20 chromium(III) complexes, and the Cr–
i
Cp*[2-R1-4-R2-6-(CH NR3)C6H2O]CrCl [R1 = Pr (1, 4), tBu (2,
i
3, 5), Ad (6); R2 = H (1, 2, 3), tBu (4, 5, 6); R3 = Pr (1, 2, 5, 6), tBu
(3, 4)], were synthesized via the reaction of Cp*CrCl2(THF) with
the lithium salt of the corresponding salicylaldiminato ligand L1–
L6 in THF in a way similar to the one communicated previously16
as shown in Scheme 1. The free salicylaldimine ligands HL1–HL6
were synthesized in high yields by the condensation reaction of a
substituted salicylaldehyde with 2 equiv. of an aliphatic amine
in hexane or an aromatic amine in methanol as described in
the literature.18 Of these free ligands, HL3 and HL5 are known
compounds.18 To make the condensation reaction to go to com-
pletion, anhydrous MgSO4 was added into the reaction mixture to
remove the formed water during the reaction. The condensation
reactions with the aromatic amines were carried out in methanol
because the products are more soluble in methanol and can be
easily isolated. The salicylaldehyde derivatives were synthesized in
high yields by treatment of the corresponding phenol derivatives
with paraformaldehyde in the presence of magnesium chloride and
triethylamine according to a literature procedure.19 The chromium
complexes were synthesized by the reaction of Cp*CrCl2(THF)
with the lithium salt of the corresponding salicylaldiminato ligand
in 60–70% isolated yields with complex 6 being obtained in a
little bit lower yield (56%). Considering that nucleophilic addition
to the imino C N bond may take place during the lithiation
reaction of the free salicylaldimine ligands with butyllithium,
all lithiation reactions were carried out at -78 ◦C to make sure
the lithium salts of the salicylaldiminato ligands were formed
in high yields. The synthesis of complexes 1–6 was also tested
with [Cp*CrCl2]2 as the starting material. However, the isolated
˚
˚
Cl (2.296(4)–2.323(1) A) and Cr–O (1.914(2)–1.931(2) A) bond
lengths are close to those reported for salicylaldiminato21 and
b-ketoiminato17 chromium(III) complexes. The lengths of these
bonds do not seem to change very much with the change in R1–R3
groups while the Cr–N bond length is obviously affected by the R3
˚
group on N, being shorter (2.033(5)–2.049(4) A) for complexes 1,
2, 6 and 8 with R3 = Pr or Ph, and being longer (2.071(4)–2.097(2)
A) for complexes 3, 4, 7 and 9 with R = Bu or 2,6- Pr2C6H3. The
i
3
t
i
˚
˚
short imine C N bond length (1.268(8)–1.303(5) A) indicates the
retention of its double bond character in these complexes.
Fig. 1 Perspective view of complex 1 with thermal ellipsoids drawn at the
30% probability level. Hydrogens are omitted for clarity.
The O–Cr–Cl and N–Cr–Cl bond angles in these com-
plexes change in the ranges of 92.40(1)–97.51(17)◦ and
Scheme 1 The synthetic procedure for complexes 1–6.
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˚
Table 1 Selected bond lengths (A) and angles (deg) of complexes 1–9
1
2
3
4
6
7
8
9
Cr(1)–O(1)
Cr(1)–N(1)
Cr(1)–C(1)
Cr(1)–C(2)
Cr(1)–C(3)
Cr(1)–C(4)
Cr(1)–C(5)
Cr(1)–Cl(1)
1.926(3)
2.046(3)
2.270(4)
2.275(4)
2.227(4)
2.236(3)
2.248(3)
2.3172(13)
1.313(4)
1.284(5)
88.66(12)
97.47(9)
95.10(9)
121.2
1.923(3)
2.048(4)
2.253(5)
2.258(5)
2.279(5)
2.243(5)
2.241(4)
2.3222(15)
1.316(6)
1.291(7)
87.96(16)
96.99(11)
96.81(13)
121.9
1.9311(19)
2.087(3)
2.264(3)
2.222(3)
2.254(3)
2.287(3)
2.297(3)
2.3229(10)
1.309(3)
1.290(4)
88.01(9)
93.52(7)
100.20(8)
120.7
1.914(2)
2.081(3)
2.226(4)
2.265(4)
2.279(4)
2.267(3)
2.262(4)
2.3103(10)
1.314(4)
1.299(4)
89.34(10)
93.82(8)
97.54(8)
118.5
1.921(5)
2.033(5)
2.263(7)
2.242(7)
2.243(7)
2.262(7)
2.267(7)
2.298(2)
1.317(7)
1.268(8)
91.5(2)
97.51(17)
92.31(16)
120.5
1.927(3)
2.071(4)
2.243(5)
2.377(4)
2.288(5)
2.280(5)
2.246(5)
2.296(4)
1.306(5)
1.291(5)
87.44(1)
92.40(1)
100.60(1)
122.7
1.923(3)
2.049(4)
2.233(5)
2.237(5)
2.255(5)
2.259(4)
2.220(5)
2.305(9)
1.308(5)
1.303(5)
89.45(1)
93.72(1)
99.33(1)
121.7
1.918(5)
2.097(2)
2.283(2)
2.251(3)
2.257(3)
2.241(3)
2.260(3)
2.306(8)
1.318(3)
1.295(3)
88.48(7)
93.85(6)
93.50(6)
120.3
O(1)–C(11)
N(1)–C(17)
O(1)–Cr(1)–N(1)
O(1)–Cr(1)–Cl(1)
N(1)–Cr(1)–Cl(1)
Cp*–Cr(1)–O(1)
Cp*–Cr(1)–N(1)
Cp*–Cr(1)–Cl(1)
Cp*-[phenoxide]
Cp*–[O–Cr–N]
124.9
121.5
18.5
49.0
123.6
121.5
20.8
48.6
125.1
121.0
19.9
46.9
127.2
121.7
17.7
48.8
127.1
120.3
61.2
52.9
124.0
121.3
5.5
48.2
123.2
121.6
34.0
48.4
132.2
118.9
83.7
56.5
Fig. 3 Perspective view of complex 3 with thermal ellipsoids drawn at the
30% probability level. Hydrogens are omitted for clarity.
Fig. 2 Perspective view of complex 2 with thermal ellipsoids drawn at the
30% probability level. Hydrogens are omitted for clarity.
R1 and R3 groups does not seem to follow a simple rule. The angle
between the Cp* ring and the plane through Cr, O, and N atoms
are in the range of 46.9–49.0◦ for most of these complexes with R1
and R3 being either iPr or tBu except for complexes 6 (52.9◦) with
R1 = Ad and 9 (56.5◦) with R3 = 2,6-iPr2Ph. In comparison, the
impact of the steric bulk of R1 and R3 groups on the angle between
the Cp* ring and the phenoxy ring is much more remarkable as
seen for complexes 7 (5.5◦), 8 (34.0◦) and 9 (83.7◦).
92.31(16)–100.60(1)◦, respectively, with the variation in R1 and
R3 groups. For most of these complexes, with a bulkier R1 and
a less bulky R3, the O–Cr–Cl bond angle would be larger and
the N–Cr–Cl bond angle would be smaller. Otherwise, with a
bulkier R3 and a less bulky R1, the O–Cr–Cl bond angle should be
smaller and the N–Cr–Cl bond angle should be larger. However,
the changes in the two bond angles do not always follow the
same rule (comparing these bond angles in 1 and 2, 4 and 7). It
is possible that the electronic effect of the substituents and the
packing force in some cases could also be important factors to
affect the bond parameters. The Cp* (centroid)–Cr–O and Cp*–
Cr–N bond angles in these complexes are also dependent on the
steric bulk of R1 and R3 groups. For most of these complexes,
a bulkier R1 or R3 group corresponds to a larger Cp*–Cr–O or
Cp*–Cr–N bond angle, respectively. The angle between the Cp*
ring and the plane through Cr, O, and N atoms and the angle
between the Cp* ring and the phenoxy ring in these complexes are
also affected by the R1 and R3 groups as seen in Table 1. However,
the variation of both angles with the changes in the steric bulk of
Ethylene polymerization studies
For comparison purpose, the new chromium(III) complexes 1–
6 and the previously communicated complexes 7, 8 and 916
were all studied as ethylene polymerization catalysts activated
with AlMe3, AlEt3 and AliBu3. The experimental results are
summarized in Tables 2, 3 and 4. Upon activation with a small
amount of AlR3 (Al/Cr molar ratio = 25), complexes 1–9 all show
reasonable to high catalytic activity for ethylene polymerization
to produce ultra-high molecular weight polyethylene. However,
these complexes display relatively low catalytic activity for ethylene
polymerization when activated with methylaluminoxane (MAO).
10186 | Dalton Trans., 2011, 40, 10184–10194
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Table 2 Summary of ethylene polymerization results with 1–9/AlMe3 catalyst systemsa
T/◦C
Yield/g
Activityb
Mh (¥104)
Tmd/◦C
Xce (%)
Sizef/mm
c
Entry
Complex
Al/Cr
1
2
3
4
5
6
7
8
1
2
3
4
5
6
6
6
6
6
6
7
8
9
25
25
25
25
25
25
25
25
12
50
100
25
25
25
20
20
20
20
20
0
20
40
20
20
20
20
20
20
Trace
10.82
8.06
—
—
84
—
—
—
2.8
4328
3224
48
139.2
138.8
137.5
138.6
137.5
138.8
139.1
139.2
138.8
137.6
136.8
134.5
138.4
72.5
68.5
63.1
70.6
65.1
69.5
70.5
71.2
68.5
65.3
60.3
70.0
77.1
104
100
101
115
108
101
112
96
2.2
h
0.12
10.67
10.82
12.26
6.72
4.23
9.96
4268
4328
4904
2688
1692
3984
2724
4044
2108
324
1.8
2.2
2.6
2.9
3.1
1.5
1.2
2.3
2.4
2.2
9
10
11
12
13g
14g
6.81
75
10.11
10.54
1.62
101
126
145
a Polymerization conditions: solvent 60 ml of toluene; catalyst 5 umol; time 30 min; ethylene pressure 5 bar. b kg PE mol Cr-1 h-1. c Measured in
◦
decahydronaphthalene at 135 ◦C. d Determined by DSC at a heating rate of 10 k min-1. e Crystallinity Xc = DHf/DHf◦, DHf = 273 J g-1 for completely
crystalline PE. f Average particle size. g Catalyst 10 umol. h Not spherical particles.
Table 3 Summary of ethylene polymerization results with 1–9/AlEt3 catalyst systemsa
◦
Activityb
Mh (¥104)
Tm ( C)
Xc (%)
Sizef/mm
c
d
e
Entry
Complex
Time/min
Yield/g
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
1
2
3
4
5
6
6
6
6
6
6
6
7
8
9
30
30
30
30
30
5
10
15
20
30
45
60
30
30
30
0.28
5.27
3.86
0.53
4.82
2.52
4.16
5.10
5.96
6.54
6.72
6.88
4.26
3.14
2.35
112
144
146
154
168
162
126
177
196
212
220
224
226
120
158
192
138.4
139.7
138.6
138.5
137.6
138.2
139.3
138.6
138.5
139.1
139.6
139.4
139.6
139.4
139.5
63.2
65.6
68.4
70.6
63.5
61.2
63.1
62.2
64.4
65.6
67.9
67.7
57.6
61.1
65.1
3.2
3.4
3.3
2.2
2108
1244
212
1928
6048
4992
4080
3576
2616
2016
1376
1704
1256
940
2.6
g
1.3
1.8
2.2
2.9
3.1
3.2
2.9
3.0
2.6
a Polymerization conditions: solvent 60 ml o◦f toluene; catalyst 5 umol; Al : Cr ratio 25; temperature 20 ◦C; ethylene pressure 5 bar. b kg PE mol Cr-1 h-1.
◦
c Measured in decahydronaphthalene at 135 C. d Determined by DSC at a heating rate of 10 k min-1. e Crystallinity Xc = DHf/DHf◦, DHf = 273 J g-1 for
completely crystalline PE. f Average particle size. g Not spherical particles.
With the best 6/MAO catalyst system (5 umol catalyst, 30 min
polymerization time, 5 bar ethylene pressure), no polyethylene was
formed when the Al/Cr molar ratio is 25 and 100, and 0.416, 3.13,
and 3.46 g of polymer was obtained with the Al/Cr molar ratio
being 250, 500, and 1000, respectively. The molecular weight of
the polyethylene from the MAO activated catalyst systems is also
relatively low (Mh = 10–15 ¥ 104). When activated with AlMe3
or AlEt3, most of these half-sandwich chromium(III) complexes
were found to produce polyethylene as uniform spherical particles
with a diameter of 1–6 mm and a bulk density about 0.36 g
cm-3 as shown in Fig. 6a–c. To the best of our knowledge,
it is unprecedented for polyethylene to be produced as such
large spherical particles in homogeneous polymerization system
with unsupported catalysts, including metallocene and non-
metallocene catalysts, although it is well known that polyethylene
can be produced as large particles from heterogeneous supported
catalyst systems.22 The morphology of the obtained polyethylene
is dependant on the experimental conditions. By examining the
polyethylene samples from different catalyst systems, it was seen
that the polyethylene particles produced by the AlEt3 activated
catalyst systems are generally larger in size than the ones produced
by the AlMe3 activated catalyst systems. In contrast to the
AlMe3 and AlEt3 activated catalyst systems, the AliBu3 activated
catalyst systems were found to produce polyethylene as a gel
in toluene, which converted to a solid felt-like sheet after the
solvent was removed. It was also observed that the particle size
of the polyethylene samples produced by the AlMe3 and AlEt3
activated catalyst systems increases slightly with the elevation in
polymerization temperature from 0 to 40 ◦C (entries 6–8 in Table
2) and the extension in polymerization time from 5 to 60 min
(entries 20–26 in Table 3). To avoid large temperature jumps during
the polymerization caused by the exothermic polymerization
reaction, all polymerization experiments were carried out in a
stainless steel autoclave kept in a water bath at the corresponding
temperature. Usually, a temperature elevation of 10–15 ◦C was
observed in 30 min for most polymerization reactions. Typical
temperature profiles for the polymerization reactions catalyzed by
6/AlMe3, 6/AlEt3 and 6/AliBu3 catalyst systems, respectively, are
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Table 4 Summary of ethylene polymerization results with 1–9/AliBu3 catalyst systemsa
Tmd/◦C
Xc (%)
c
e
Entry
Complex
Yield/g
Activityb
Mh (¥104)
30
31
32
33
34
35
36
37
38
1
2
3
4
5
6
7
8
9
0.52
1.65
1.27
0.98
1.82
2.14
1.57
0.82
0.17
208
660
508
392
728
856
314
164
34
118
114
118
123
116
120
109
135
156
139.6
139.2
139.4
139.2
139.6
139.0
138.0
138.2
139.6
65.7
61.2
63.4
71.9
70.3
60.0
62.7
64.6
66.8
a Polymerization conditions: solvent 60 ml of toluene; cat◦alyst 5 umol; Al : Cr ratio 25; time 30 min; temperature 20 ◦C. ethylene pressure 5 bar. b kg PE
◦
mol Cr-1 h-1. c Measured in decahydronaphthalene at 135 C. d Determined by DSC at a heating rate of 10 k min-1. e crystallinity Xc = DHf/DHf◦, DHf
=
273 J g-1 for completely crystalline PE.
Table 5 Effect of solvent and stirring rate on polymer morphology for reactions with 6/AlEt3 catalyst systema
Entry
Solvent
AlR3
Stirring rate (r/min)
Activityb
Sizec/mm
d
1
2
3
4
5
6
7
Toluene
Toluene
Toluene
Toluene
Toluene
CH2Cl2
Hexane
AlEt3
AlEt3
AlEt3
AlEt3
AlEt3
AlEt3
AlEt3
0
1280
1948
2362
2616
2734
1634
1868
100
400
700
1000
700
700
3.3
3.1
2.9
2.1
1.9
d
a Polymerization conditions: solvent 60 ml; catalyst complex 6; 5 umol; Al : Cr ratio 25; time 30 min; temperature 20 ◦C; ethylene pressure 5 bar. b kg PE
mol Cr-1 h-1. c Average particle size. d Not spherical particles.
Fig. 5 Perspective view of complex 6 with thermal ellipsoids drawn at the
30% probability level. Hydrogens are omitted for clarity.
Fig. 4 Perspective view of complex 4 with thermal ellipsoids drawn at the
conditions on the polymer morphology, ethylene polymerization
experiments in different solvents or with different stirring rates
were carried out with a typical 6/AlEt3 catalyst system and the
results are listed in Table 5. The polymerization reactions run
in toluene and CH2Cl2 produced polyethylene in the form of
spherical particles, while the reactions run in hexane gave only
powdery polyethylene. No spherical particle was formed when
the polymerization reaction was carried out without stirring,
while the spherical particles were always formed in the stirred
polymerization reactions. The particles tend to be more uniform
30% probability level. Hydrogens are omitted for clarity.
shown in Fig. 7. Such a relatively small temperature change does
not seem to be an important factor for causing the formation
of the spherical polyethylene particles. A kinetic study on the
polymerization reaction catalyzed by 6/AlMe3 demonstrates that
the lifetime of this catalyst system is relatively long and the
polymerization reaction rate is comparatively mild with a broad
ethylene consumption profile covering more than 30 min, as seen
in Fig. 8. To further examine the effect of the experimental
10188 | Dalton Trans., 2011, 40, 10184–10194
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Fig. 8 A typical ethylene consumption profile for the polymerization
reaction with the 6/AlMe3 catalyst system.
polymer chain). The character of producing ultra-high molecular
weight polyethylene in a moderate chain propagation rate for
these catalyst systems may also be an important factor for the
formation of the spherical particles. In toluene and CH2Cl2, the
solubility of the catalytically active species should be good when
the growing polymer chains are not very long, while it would get
lower and lower with the growth of the polymer chains and finally
the polymer chains would precipitate from the solution. If this
procedure is not very fast, there may be a stage during which the
polymer chains are in a quasi precipitating state and can be wound
together to form small spherical particles by the stirring movement
as shown in Scheme 2. Since the catalytically active species is still
live and the polymerization reaction continues after the formation
of the particles, the size of the particles grows with time. When the
polymerization was carried out in hexane, due to low solubility, the
growing polymer chains may precipitate from the solution too fast
to form the spherical particles and thus powdery polymer samples
were obtained. The reason for the AliBu3 activated catalyst systems
being different from the AlMe3 and AlEt3 activated ones is not
clear.
Fig. 6 The images of the polyethylene particles produced by (a) 6/AlMe3
and (b) 6/AlEt3 catalyst systems and the particle size distribution (PSD)
of polyethylene particles produced by 6/AlMe3 catalyst system (c).
Scheme 2 Illustration for the possible forming procedure of the large
polyethylene particles.
It is well known that the catalytic activity of metallocene
catalysts can be tuned by steric and electronic effects of the
substituents on their ligands. For complexes 1–9, it was found
that the R1, R2 and R3 groups on the salicylaldiminato ligand
show obvious steric and electronic effects on the catalytic activity
of these complexes. By comparing the catalytic activity data of
Fig. 7 Plots of reaction temperature vs. polymerization time for ethylene
polymerization reactions with 6/AlMe3, 6/AlEt3, and 6/AliBu3 catalyst
systems.
i
and the particle size decreases more or less with the increase in
the stirring rate from 100 r/min to 1000 r/min. Although the
detailed mechanism for the formation of the spherical particles is
not very clear, it seems apparent that the formation of the spherical
particles is related to the solubility and the stirring movement
of the catalytically active species (a catalytically active species
should be composed of a catalyst, a cocatalyst, and a growing
complexes 1 and 4 (R1 = Pr) with those of complexes 2, 3, 5, 7
t
(R1 = Bu) and 6 (R1 = Ad) in Tables 2, 3 and 4, it can be seen that the
catalytic activity of these complexes increases remarkably with the
increase in the steric bulk of R1 group, and the complex 6 with the
bulkiest R1 group shows the highest catalytic activity under similar
conditions. These results may be attributed to that a bulky R1 in
the ortho-position of the oxygen atom in the salicylaldiminato
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ligand could prevent the oxygen atom from coordinating to a
AlR3 cocatalyst or another chromium complex, and therefore
keep the active catalyst from bimolecular deactivation. Of course,
the high catalytic activity of the catalysts with bulky R1 group
may be simply due to the proper combination of the substituents
and their favorable cooperative effects. Similar results have also
been observed in a related half-sandwich chromium(III) catalyst
system.17 In comparison to the effect of the R1 group, the effect of
the R3 group on the catalytic activity is some what complicated.
(1.0 ~ 2.2 ¥ 106 Dalton). Their viscosity-average molecular wei◦ght
(Mh) values were measured in decahydronaphthalene at 135 C,
and the data are given in Tables 2–4. By examining the Mh data,
it can be seen that the molecular weight of the polyethylenes
produced by these catalysts is affected by several factors. In
general, catalysts with bulky R1 and/or R3 groups seem to
produce polyethylenes with relatively high molecular weight, while
polymerization reactions carried out at high temperatures or
with high Al/Cr molar ratios give polyethylenes with relatively
low molecular weight. These results are normal for metallocene
catalyst systems24 and similar results were also observed for related
half-sandwich chromium(III) catalysts bearing hydroxyindanimine
ligands.17b An interesting point to note is that the molecular weight
of the produced polyethylene increases with time until the end
of the polymerization although it increases more rapidly in the
beginning 20 min of the reaction, as seen in Table 3 (entries
20–26) and Fig. 9. The continual increase of the polyethylene
molecular weight with time implies that at least a part of the
polymer chains in the present system propagate over the full period
of the polymerization reaction. A plot of the Mh of the produced
polyethylene vs. the polymer yield shown in Fig. 10 also indicates
that the polymerization reaction takes place in a quasi living
fashion with the molecular weight of the polyethylene increasing
with the polymer yield during the full period of the polymerization.
The quasi living polymerization feature of these half-sandwich
chromium(III) catalyst systems should be related to their capability
to produce ultra-high molecular weight polyethylene.
t
The catalytic activity of complexes with R1 being Bu group
decreases remarkably with the increase in the steric bulk of the
R3 group while the catalytic activity of complexes with R1 being
iPr increases with the increase in the steric bulk of the R3 group as
seen in Table 2–4 (comparing the catalytic activity of complexes
1 with 4, 2 with 3, 5 and 7 with 9). It is obvious that the R3
group on the imine N atom could tune the space available for the
coordination of ethylene to the metal center. In addition, the fact
t
that the catalytic activity of complex 7 (R3 = Bu) is much higher
than that of complex 8 (R3 = Ph) implies the electronic effect of
the R3 group on the catalytic activity of these complexes also plays
an important role. An electron donating R3 group may improve
the coordination ability of the imine N atom to the metal center
and thus the stability of the catalytically active species. It has
previously been suggested that the catalytic activity of complexes
7–9 decreases with the increase in the angle between the Cp* ring
and the plane through Cr, O, and N atoms.16 By examining the data
of this angle in Table 1 and the catalytic activity data in Tables 2–4,
it is clear that no such relationship between the catalytic activity
and the mentioned angle can be seen for complexes 1–9 in the
present work.
The catalytic activity of these half-sandwich chromium(III)
catalysts is sensitive to the alkyl aluminium cocatalysts. It was
t
found that for complexes 2, 3 and 5–9 with the R1 = Bu or
Ad, their catalytic activity decreases in the order of AlMe3 >
AlEt3 > AliBu3 while the catalytic activity of complexes 1 and
i
4 (R1 = Pr) increases in the order of AlMe3 < AlEt3 < AliBu3.
The complicated effect of the alkyl aluminium cocatalysts on the
catalytic activity of these chromium(III) catalysts may be attributed
to the interaction between the catalyst and cocatalyst molecules
as discussed previously.16 These half-sandwich chromium(III)
complexes can all be effectively activated with only a small amount
of alkyl aluminium cocatalyst, and their catalytic activity reaches
the maximum with an Al/Cr molar ratio about 25. The catalytic
activity decreases considerably with the increase in the Al/Cr
molar ratio from 25 to 100 or with the decrease in the Al/Cr
molar ratio from 25 to 12 as seen in Table 4. Similar results
were also observed in other related half-sandwich chromium(III)
catalyst systems.15,19 To investigate the effect of polymerization
temperature on the catalytic activity of these catalyst systems,
ethylene polymerization experiments with a typical 6/AlMe3
catalyst system were carried out at 0, 20, and 40 ◦C, and the results
are listed in Table 2 (entries 6–8). It was found that the catalyst 6
Fig. 9 Plots of polymer yield and viscosity-average molecular weight
(Mh) vs. polymerization time for ethylene polymerization reactions with
the 6/AlEt3 catalyst system. (data from entries 20–26 in Table 3).
The obtained polyethylene samples were all analyzed by dif-
ferential scanning calorimetry (DSC), and the melting transition
temperature and crystallinity data are summarized in Tables 2–4.
Most of the samples show a sharp endothermic melting peak in the
range of 138–140◦ in their DSC diagrams with the crystallinity in
the range of 56.9–72.5%, which is typical for linear polyethylenes.25
13C NMR spectra of the polyethylene samples obtained at 130 ◦C
in C6D4Cl2 show no signals for branches,26 which confirms that
the polyethylenes are linear. The powder X-ray diffraction (XRD)
analysis on these polyethylene samples has been done and the
XRD diagrams of typical polyethylene samples are shown in Fig.
11. The peaks in the 2q region of 19–25◦ in the XRD diagram
can be assigned to the polyethylene’s orthorhombic (110 and 200)
◦
shows the highest catalytic activity at 20 C. It has been known
that the optimal polymerization temperature for a catalyst system
is determined by several factors, such as the thermal stability of
the catalytically active species, the polymerization reaction rate
and the monomer concentration at different temperatures.23
The polyethylenes produced by these catalysts with an Al/Cr
molar ratio of 25 or less possess ultra-high molecular weight
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the R1, R2 and R3 groups as well as the AlR3 cocatalyst. Upon
activation with AlMe3 or AlEt3, the polyethylenes produced with
these catalysts were obtained as spherical particles with a diameter
of 1–6 mm.
Experimental
General considerations
All manipulations for air- and moisture-sensitive compounds
were performed under an inert atmosphere of nitrogen using
standard Schlenk or glovebox techniques. Solvents were dried
and purified by known procedures and distilled under nitrogen
prior to use. CrCl3(THF)329 and Cp*Li30 were prepared according
to the literature procedures. All other reagents were purchased
1
Fig. 10 Plot of viscosity-average molecular weight (Mh) vs. polymer yield
for ethylene polymerization reactions with the 6/AlEt3 catalyst system
(data from entries 20–26 in Table 3).
from Aldrich or Acros and used as received. H NMR spectra
were measured using a Varian Mercury-300 NMR spectrometer
and the elemental analysis was performed on a Perkin–Elmer
2400 analyzer. The intrinsic viscosity [h] was measured in dec-
ahydronaphthalene at 135 ◦C using an Ubbelohde viscometer.
Viscosity average molecular weight (Mh) values of polyethylenes
were calculated by the following equation31: [h] = 6.77 ¥ 10-4 Mh
.
0.67
Melting transition temperature (Tm) and crsytallinity (Xc) of
the polymers were measured with a 204 differential scanning
calorimeter (DSC). The samples (5–10 mg) were heated from
◦
30 ◦C to 180 ◦C at a rate of 10 C min-1 and the data from
1
the second heating cycle were used. H and 13C NMR spectra of
polyethylene samples were measured on a Varian Unity 400-MHz
spectrometer at 130 ◦C in o-C6D4Cl2. Powder XRD was performed
on a Rigaku D/Max-2550 diffractometer using Cu-Ka radiation
operating at 50 KV and 200 mA, and the data were collected
in the 2q range of 15–30◦ with a scanning rate of 1 degree per
minute.
3-Isopropylsalicylaldehyde. To a stirred mixture of anhydrous
magnesium dichloride (9.52 g, 100 mmol) and solid paraformalde-
hyde (4.50 g, 150 mmol) in dried THF (200 ml) was added
triethylamine dropwise and the mixture was stirred at room
temperature for 10 min. 2-Isopropylphenol (6.80 g, 50.0 mmol)
was then added dropwise, resulting an opaque, light pink mixture.
This mixture was heated at gentle reflux temperature for 2 h, during
which time the color of the reaction mixture changes from light
pink to orange. After the reaction mixture was cooled to room
temperature, 100 mL of diethyl ether and 100 mL of 1 N HCl were
added. The organic phase was separated and washed with 1 N
HCl (2 ¥ 100 mL) and water (3 ¥ 100 mL), dried over MgSO4, and
filtered. The solvent was removed by rotatory evaporation to leave
the crude product which was purified by column chromatography
on silica gel using petroleum ether/ethyl acetate (90 : 10) mixture
as the eluent to give pure 3-isopropylsalicylaldehyde (7.02 g,
Fig. 11 XRD patterns of typical polyethylene samples obtained with the
6/AlMe3 catalyst system at (a) 0 ◦C, (b) 20 ◦C and (c) 40 ◦C.
diffractions at 21.32 and 23.72 and monoclinic (001, 200 and 201)
diffractions at 19.22, 22.94 and 24.96.27 As seen from Fig. 11,
the predominating crystalline form in these polyethylenes is the
thermodynamically most stable orthorhombic phase,28 while the
portion of the monoclinic phase increases remarkably with the
decrease in polymerization temperature from 20 to 0 ◦C.
Conclusion
A
number of half-sandwich pentamethylcyclopentadienyl
chromium(III) complexes bearing a salicylaldiminato ligand,
Cp*[2-R1-4-R2-6-(CH NR3)C6H2O]CrCl (1–6) were synthesized
in good yields. X-Ray crystallographic analysis indicates that
these half-sandwich chromium(III) complexes adopt a pseudo-
octahedral coordination environment with a three-legged piano
stool geometry. When activated with a small amount of proper
AlR3, these complexes exhibit good to high catalytic activity for
ethylene polymerization and produce ultra-high molecular weight
polyethylene in a quasi living fashion under mild conditions. The
catalytic activity of these complexes and the molecular weight
of the produced PE can be tuned in a broad range by changing
1
42.6 mmol, 85.2%) as a pale yellow oil. H NMR (CDCl3): d
1.24 (d, 6H, J = 7.2 Hz, CHMe2), 3.37 (m, 1H, J = 7.2 Hz,
CHMe2), 6.98 (t, J = 7.5 Hz, 1H, PhH), 7.39 (d, J = 7.5 Hz, 1H,
PhH), 7.47 (d, J = 7.5 Hz, 1H, PhH), 9.88 (s, 1H, CHO), 11.38
(s, 1H, OH).
3-tert-Butyl-5-isopropylsalicylaldehyde and 3-admantyl-5-tert-
butyl-salicylaldehyde were synthesized in the same manner as
3-isopropylsalicylaldehyde with different starting materials. The
experimental data are listed in Table 6.
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Table 6 Experimental data for the synthesis of salicylaldehydes and free ligands
Compounds
Starting materials
Yield
1H NMR (CDCl3)
3-tert-Butyl-5-
isopropyl-
salicylaldehyde
2-Isopropyl-4-tert-butylphenol
(9.62 g, 50.0 mmol), parafor-
maldehyde (4.50 g, 150 mmol)
9.47 g, 43.0 mmol, 86.0%
d 1.24 (d, J = 6.9 Hz, 6H, CHMe2), 1.30 (s, 9H, CMe3),
1.33 (s, 9H, CMe3), 3.38 (h, J = 2.4 Hz, 1H, CHMe2),
7.05 (d, J = 2.4 Hz, 1H, PhH), 7.24 (d, J = 2.4 Hz, 1H,
PhH), 9.86 (s, 1H, CHO), 11.46 (s, 1H, OH)
d 1.31 (s, 9H, CMe3), 1.78 (s, 6H, Ad–CH2), 2.07 (s, 3H,
Ad–CH), 2.16 (s, 6H, Ad–CH2), 7.10 (s, J = 2.4 Hz, 1H,
PhH), 7.29 (s, J = 2.4 Hz, 1H, PhH), 9.88 (s, 1H, CHO),
11.52 (s, 1H, OH)
d 1.31 (d, 6H, CHMe2), 1.45 (s, 9H, CMe3), 3.55 (h, J =
6.3 Hz, 1H, CHMe2), 6.82 (t, J = 7.5 Hz, 1H, PhH), 7.13
(t, J = 7.5 Hz, 1H, PhH), 7.33 (t, J = 7.5 Hz, 1H, PhH),
8.37 (s, 1H, CH N), 14.18 (s, 1H, OH)
d 1.25 (d, J = 6.9 Hz, 6H, CHMe2), 1.31 (s, 9H, CMe3),
1.34 (s, 9H, CMe3), 3.40 (h, J = 2.4 Hz, 1H, CHMe2),
7.09 (d, J = 2.4 Hz, 1H, PhH), 7.29 (d, J = 2.4 Hz, 1H,
PhH), 8.34 (s, 1H, CH N), 14.52 (s, 1H, OH)
d 1.28 (d, J = 6.9 Hz, 6H, CHMe2), 1.33 (s, 9H, CMe3),
1.80 (s, 6H, Ad–CH2), 2.10 (s, 3H, Ad–CH), 2.19 (s, 6H,
Ad–CH2), 3.51 (m, J = 6.3 Hz, 1H, CHMe2), 7.14 (s, J =
2.4 Hz, 1H, PhH), 7.34 (s, J = 2.4 Hz, 1H, PhH), 8.38 (s,
1H, CH N), 13.90 (s, 1H, OH)
3-Admantyl-5-tert-
butyl-salicylaldehyde
2-Adamantyl-4-tert-butylphenol
(14.2 g, 50.0 mmol), parafor-
maldehyde (4.50 g, 150 mmol)
12.7 g, 40.6 mmol, 81.3%
2.14 g, 9.62 mmol, 96.2%
2.66 g, 9.51 mmol, 95.1%
3.25 g, 9.20 mmol, 92.0%
HL2
HL4
HL6
3-tert-Butylsalicylaldehyde
(1.78 g, 10.0 mmol), isopro-
pylamine (1.20 g, 20.0 mmol)
3-Isopropyl-5-tert-butyl-
salicylaldehyde (2.20 g, 10.0 mmol),
tert-butylamine (1.46 g, 20.0 mmol)
3-Admantly-5-tert-butyl-
salicylaldehyde (3.13 g, 10.0 mmol),
isopropylamine (1.20 g, 20.0 mmol)
Table 7 Experimental data for the synthesis of complexes 2–6
Complex
Starting materials
Yield
Elemental analyses
2
HL2 (0.439 g, 2.00 mmol), n-BuLi (1.60 M,
2.05 mmol), Cp*Li (0.284 g, 2.00 mmol),
CrCl3(THF)3 (0.750 g, 2.00 mmol)
0.527 g, 1.20 mmol,
60.2%
Calcd for C24H33NOCrCl (438.97): C 65.67; H 7.58; N 3.19.
Found: C 65.40; H 7.64; N 3.12.
3
4
5
6
HL3 (0.469 g, 2.00 mmol), n-BuLi (1.60 M,
2.05 mmol), Cp*Li (0.284 g, 2.00 mmol)
and CrCl3(THF)3 (0.750 g, 2.00 mmol)
HL4 (0.551 g, 2.00 mmol), n-BuLi (1.60 M,
2.05 mmol), Cp*Li (0.284 g, 2.00 mmol)
and CrCl3(THF)3 (0.750 g, 2.00 mmol)
HL5 (0.551 g, 2.00 mmol), n-BuLi (1.60 M,
2.05 mmol), Cp*Li (0.284 g, 2.00 mmol)
and CrCl3(THF)3 (0.750 g, 2.00 mmol)
HL6 (0.707 g, 2.00 mmol), n-BuLi (1.60 M,
2.05 mmol), Cp*Li (0.284 g, 2.00 mmol)
and CrCl3(THF)3 (0.750 g, 2.00 mmol)
0.525 g, 1.16 mmol,
58.1%
Calcd for C25H35NOCrCl (453.00): C 66.28; H 7.79; N 3.09.
Found: C 66.12; H 7.88; N 3.05
0.572 g, 1.24 mmol,
62.6%
Calcd for C28H43NOCrCl (461.64): C 72.85; H 9.39; N 3.03.
Found: C 72.77; H 9.32; N 3.12
0.632 g, 1.37 mmol,
68.5%
Calcd for C28H43NOCrCl (461.64): C 72.85; H 9.39; N 3.03.
Found: C 72.53; H 9.47; N 3.12
0.644 g. 1.12 mmol,
56.0%
Calcd for C34H49NOCrCl (575.21): C 70.99; H 8.59; N 2.44.
Found: C 71.12; H 8.65; N 2.33
2-iPr-6-(CH NiPr)C6H3OH (HL1). To a stirred mixture of
3-isopropylsalicylaldehyde (1.64 g, 10.0 mmol) and anhydrous
MgSO4 (~1 g) in n-hexane (15 mL) was added isopropylamine
(1.20 g, 20.0 mmol) under nitrogen. After the mixture was heated at
reflux temperature for 8 h, the solvent was removed under reduced
pressure to give the crude imine product. The crude product was
purified by column chromatography on silica gel using petroleum
ether/ethyl acetate (95 : 5) as the eluent to afford pure 2-iPr-6-
(CH NiPr)C6H3OH (1.95 g, 9.50 mmol, 95.0%) as an orange oil.
1H NMR (CDCl3): d 1.27 (d, J = 9.6 Hz, 6H, CHMe2), 1.31 (d,
J = 9.6 Hz, 6H, CHMe2), 3.42 (h, J = 6.9 Hz, 1H, CHMe2), 3.56
(h, J = 6.3 Hz, 1H, CHMe2), 6.85 (t, J = 7.5 Hz, 1H, PhH), 7.09
(d, J = 7.5 Hz, 1H, PhH), 7.26 (d, J = 7.5 Hz, 1H, PhH), 8.36 (s,
1H, CH N), 14.10 (s, 1H, OH).
slowly added a suspension of Cp*Li (0.284 g, 2.00 mmol) in
THF (10 mL) at 0 ◦C. The mixture was allowed to warm to
room temperature and stirred overnight to get a blue solution.
In another flask, to a solution of 2-iPr-6-(CH NiPr)C6H3OH
(0.410 g, 2.00 mmol) in THF (15 mL) was added a solution of
n-BuLi (1.60 M, 2.05 mmol) in hexane by syringe at -78 ◦C. The
reaction mixture was allowed to warm to room temperature and
stirred for 1h, then added slowly to the above reaction mixture
◦
at -15 C. The obtained reaction mixture was allowed to warm
to room temperature and stirred overnight. During the reaction,
the color of the reaction mixture changes from blue to green.
Removal of the solvents under reduced pressure to give a dark-
green residue, followed by extraction with toluene (20 mL) to
remove the insoluble impurities. Pure product 1 was obtained
by recrystallization from CH2Cl2–n-hexane (v/v = 1 ~2 : 10) as
green crystals (0.540 g, 1.27 mmol, 63.5%). Anal. calcd for
C23H31NOCrCl (424.95): C 65.01; H 7.35; N 3.30. Found: C 65.16;
H 7.37; N 3.24.
The free ligands HL2, HL4, and HL6 were synthesized in
the same manner as HL1 with different starting materials. The
experimental data are listed in Table 6.
Complexes 2–6 were synthesized in the same manner as complex
1 with different starting materials. The experimental data are listed
in Table 7.
Cp*Cr[2-iPr-6-(CH NiPr)C6H3O]Cl (1). To a purple suspen-
sion of CrCl3(THF)3 (0.750 g, 2.00 mmol) in THF (20 mL) was
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Table 8 Crystal data and structural refinements details for complexes 1–4 and 6
Complexes
1
2
3
4
6
Formula
Fw
C23H33ClCrNO
426.95
0.71073
C24H35ClCrNO
440.98
0.71073
Monoclinic
P21/n
9.4593(19)
12.206(2)
21.386(4)
90
102.19(3)
90
2413.6(8)
4
1.214
C25H37ClCrNO
455.01
0.71073
Monoclinic
P21/n
9.4568(19)
12.286(3) A
21.323(4) A
90
100.68(3)
90
2434.5(9)
4
1.241
C28H43ClCrNO
497.08
0.71073
Monoclinic
P21/c
11.921(2)
19.965(4)
13.056(3)
90
113.69(3)
90
2845.5(10)
4
1.160
C34H49ClCrNO
575.19
0.71073
Monoclinic
C2/c
29.846(6)
8.7377(17)
26.532(5)
90
113.53(3)
90
˚
Wavelength/A
Crystal system
Space group
Triclinic
¯
P1
˚
a/A
7.9630(16)
8.3667(17)
19.261(4)
84.11(3)
˚
b/A
˚
c/A
a (◦)
b (◦)
g (◦)
86.97(3)
63.57(3)
1143.0(4)
2
1.241
3
˚
V/A
6344(2)
8
1.205
2472
Z
D/g-1 m-3
F(000)
454
0.629
940
0.598
972
0.595
1068
0.514
M/mm-1
0.471
Completeness to theta
Reflections collected/unique
Rint
98.9% (q = 27.48◦)
11336/5185
0.0693
99.4%(q = 27.48◦)
21508/5494
0.1268
99.5%(q = 27.46◦)
21973/5531
0.0685
97.5%(q = 27.48◦)
27139/6367
0.0753
99.4%(q = 27.48◦)
28394/7248
0.0973
Final R indices [I > 2s(I)]
R1 = 0.0629,
wR2 = 0.1265
R1 = 0.1208,
wR2 = 0.1537
1.048
R1 = 0.0925,
wR2 = 0.2334
R1 = 0.1406,
wR2 = 0.2663
1.053
R1 = 0.0555,
wR2 = 0.1263
R1 = 0.1027,
wR2 = 0.1453
1.038
R1 = 0.0610,
wR2 = 0.1415
R1 = 0.1043,
wR2 = 0.1606
1.035
R1 = 0.1017,
wR2 = 0.2678
R1 = 0.1499,
wR2 = 0.2873
1.112
R indices (all data)
GooF
-3
˚
Largest diff. peak and hole/e A
0.405 and -0.587
1.772 and -0.644
0.407 and -0.387
0.582 and -0.501
0.601 and -0.448
X-Ray crystallographic studies
Notes and references
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Acknowledgements
This work was supported by the Natural Science Foundation of
China (Nos. 21074043 and 20772044).
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