Organometallics
Article
8.0 Hz}. Found, %: C, 92.19; H, 10.81. Calculated for C20H20, %: C,
92.26; H, 7.74.
solvent was eliminated under reduced pressure (residual volume
approximately 40 mL). The yellow precipitate was filtered out, washed
with pentane, and dried in vacuo to yield 8.9 g (55%) of product. Pure
(>98%) crystalline product was obtained by recrystallization from
Dimethylbis(2-methyl-4-phenyl-1,5,6,7-tetrahydro-s-inda-
cen-1-yl)silane (9). A solution of 6 (16.76 g, 68 mmol) in Et2O (200
mL) was cooled to −40 °C, and n-BuLi in hexane (1.6 M, 43.4 mL,
69.4 mmol) was added. The mixture was allowed to warm to room
temperature, stirred for 2 h, and cooled to −60 °C, and then CuCN
(183 mg, 2.04 mmol) was added. After 15 min, SiMe2Cl2 (4.1 mL, 34
mmol) was also added. The resulting mixture was allowed to warm to
room temperature and stirred for 16 h. Hexane (400 mL) and H2O
(10 mL) were added, and the organic phase was separated, dried over
MgSO4, then passed through silica gel and evaporated. The residue
1
pentane−CH2Cl2 (4:1). H NMR (CDCl3, 20 °C) δ: 1.33 (s, 6H, Si-
CH3), 1.95−2.05, 2.77−3.05 (group of m,12H, −CH2−), 2.26 (s, 6H,
C−CH3), 6.67 (s, 2H, −CH), 7.35 (t, 2H), 7.44 (t, 4H), 7.46 (s,
2H), 7.56 (d, 4H) {CAr-H}. 13C NMR (CDCl3, 20 °C) δ: 2.8, 18.4,
26.5, 32.0, 33.2 (aliphatic C), 118.2, 121.4, 127.2, 128.2, 129.1
(−CH), 126.7, 132.2, 132.9, 134.4, 138.5, 143.3, 144.5 (C<).
Found, %: C, 67.64; H, 5.43. Calculated for C40H38Cl2SiZr, %: C,
67.77; H, 5.40.
1
was dried in vacuo and used without purification. H NMR (CDCl3,
μ-{Bis-[η5-2-methyl-4-(4-methylphenyl)-1,5,6,7-tetrahydro-s-
indacen-1-yl] dimethylsilanediyl}dichlorozirconium(IV) (13).
Method B, as described above for the synthesis of 12, was also used
to prepare 13 with a yield of 52%. 1H NMR (CDCl3, 20 °C) δ: 1.32 (s,
6H, Si-CH3), 1.99−2.04, 2.83−3.01 (group of m, 12H, −CH2−), 2.23
(s, 6H), 2.40 (s, 6H) {C−CH3}, 6.67 (s, 2H, −CH), 7.24 (d, 4H),
7.43 (s, 2H), 7.45 (d, 4H), {CAr-H}. 13C NMR (CDCl3, 20°°C) δ: 2.7,
18.2, 21.2, 26.4, 31.9, 33.1 (aliphatic C), 117.9, 121.4, 126.6, 128.8,
128.9, 132.1, 132.9, 134.2, 135.5, 136.7, 143.0, 144.4 (C< and
−CH). Found, %: C, 68.31; H, 5.80. Calculated for C42H42Cl2SiZr,
%: C, 68.45; H, 5.74.
20 °C) δ: −0.05 (bs, 6H, Si-CH3), 2.18 (m), 2.90−3.11 (m) {12H,
−CH2−}, 2.28 (s), 2.34 (s) {6H, C−CH3}, 3.87 (s), 3.90 (s) {2H,
>CH−}, 6.68 (bs, 2H, −CH), 7.47 (m, 4H), 7.56 (m, 6H), {Ph}.
Found, %: C, 87.65; H, 7.44. Calculated for C40H40Si, %: C, 87.54; H,
7.35.
Dimethylbis(2-methyl-4-(4-methylphenyl))-1,5,6,7-tetrahy-
dro-s-indacen-1-yl)silane (10). This was synthesized using the
method described for 9. The product was used without purification.
1H NMR (CDCl3, 20 °C) δ: −0.10 (s), −0.09 (s, double intensity),
−0.08 (s) {Si-CH3}, 2.25 (s, 3H), 2.32 (s, 3H), 2.52 (s, 6H) {C−
CH3}, 2.16 (m), 2.92−3.06 (m) {12H, −CH2−}, 3.84 (s), 3.87 (s)
{2H, >CH−}, 6.66 (broad, 2H, −CH), 7.36 (m, 4H), 7.43 (m, 4H),
7.45 (bs, 2H) {CAr-H}. Found, %: C, 87.49; H, 7.80. Calculated for
C42H44Si, %: C, 87.40; H, 7.69.
Dimethylbis(2-methyl-4-(4-tert-butylphenyl)-1,5,6,7-tetra-
hydro-s-indacen-1-yl)silane (11). This was synthesized using the
method described for 9. The product was used without purification.
1H NMR (CDCl3, 20 °C) δ: −0.10 (bs, 6H, Si-CH3), 1.50 (s, 18H,
μ-{Bis-[η5-2-methyl-4-(4-tert-butylphenyl)-1,5,6,7-tetrahy-
dro-s-indacen-1-yl]dimethylsilanediyl}dichlorozirconium(IV)
(14). Method B, as described above for the synthesis of 12, was also
used to prepare 14 with a yield of 67%. 1H NMR (CD2Cl2, 20 °C) δ:
1.30 (s, 6H, Si-CH3), 1.34 (s, 18H, −C(CH3)3), 1.91−2.00, 2.70−2.98
(group of m, 12H, −CH2−), 2.19 (s, 6H, C−CH3), 6.62 (s, 2H,
−CH), 7.44 (broad, 10H, CAr−H). Found, %: C, 70.01; H, 6.66.
Calculated for C48H54Cl2SiZr, %: C, 70.21; H, 6.63.
Synthesis of Zirconocenes Using ZrCl3(THF)2NH-tert-Bu,
Typical Experiment. A solution of n-BuLi in hexane (1.6 M, 12.5
mL, 20 mmol) was added to a cooled (−20 °C) solution of tert-
butylamine (2.2 mL, 20.5 mmol) and THF (1.65 mL, 20 mmol) in
toluene (20 mL). The mixture was allowed to warm to room
temperature, stirred for 2 h, and transferred into a dropping funnel.
The ZrCl4 × 2THF (7.6 g, 20 mmol) was suspended in toluene (20
mL) and cooled to 0 °C, and lithium tert-butyl amide was added
within 10 min. This mixture was allowed to warm to room
temperature and stirred for 2 h. The corresponding bis-indenyl ligand
was dissolved in a toluene (35 mL) and THF (3.30 mL, 40 mmol)
solution and cooled to −40 °C, and then n-BuLi (1.6 M in hexane,
25.6 mL, 41 mmol) was added. This second mixture was allowed to
warm to room temperature, stirred for 3 h, and cooled to −40 °C, and
the mixture containing trichlorozirconium tert-butyl amide was added
within 20 min. The resulting solution was stirred for 16 h. The probe
from this mixture (ca. 0.2 mL) was evaporated to dryness in vacuo,
and CH2Cl2 (0.5 mL) and Me3SiCl (0.1 mL) were added. After 1 h,
the probe was evaporated, dried, dissolved in CDCl3, and analyzed by
−C(CH3)3), 2.14 (m), 2.89−3.12 (m) {12H, −CH2−}, 2.27 (s), 2.33
(s) {6H, C−CH3}, 3.86 (s), 3.87 (s) {2H, >CH−}, 6.72 (bs, 2H,
−CH), 7.30−7.60 {groups of m, 10H, aryl}. Found, %: C, 87.26; H,
8.64. Calculated for C48H56Si, %: C, 87.21; H, 8.54.
μ-{Bis-[η5-2-methyl-4-phenyl-1,5,6,7-tetrahydro-s-indacen-
1-yl]dimethylsilanediyl}dichlorozirconium(IV) (12). Method A
(9-Li2 + ZrCl4). Ligand 9 (10.12 g, 18.44 mmol) was dissolved in Et2O
(80 mL) and cooled to −40 °C, and n-BuLi (1.6 M in hexane, 23.8
mL, 38 mmol) was added. The mixture was allowed to warm to room
temperature, stirred for 3 h, and evaporated. The resulting orange-
yellow powder was suspended in pentane (150 mL) and cooled to
−60 °C, and ZrCl4 (4.43 g, 19 mmol) was added. After 5 min, Et2O (1
mL) was added, and the resulting mixture was allowed to warm to
room temperature with stirring, stirred for an additional 16 h, and
filtered. The orange-yellow powder was dried, DME (150 mL) and
LiCl (0.5 g) were added, and the solution was refluxed with stirring for
6 h. The solvent was then evaporated and the product was crystallized
from Et2O/hexane, producing a small amount (0.3 g, ∼5%) of the
meso form. Method B (9-Li2 + ZrCl3(THF)2NH-tert-Bu). A solution
of n-BuLi in hexane (1.6 M, 15 mL, 24 mmol) was added to a cooled
(−20 °C) solution of tert-butylamine (2.4 mL, 22.9 mmol) and THF
(1.85 mL, 23 mmol) in toluene (25 mL). The mixture was allowed to
warm to room temperature, stirred for 2 h, and transferred into a
dropping funnel. The ZrCl4 × 2THF (8.7 g, 23 mmol) was suspended
in toluene (20 mL) and cooled to 0 °C, and lithium tert-butyl amide
was added within 10 min. This mixture was allowed to warm to room
temperature and stirred for 2 h. A second solution with previously
prepared 9 (12.53 g, 22.8 mmol) was dissolved in a toluene (40 mL)
and THF (3.78 mL, 46.6 mmol) solution and cooled to −40 °C, and
then n-BuLi (1.6 M in hexane, 29.1 mL, 46.6 mmol) was added. This
second mixture was allowed to warm to room temperature, stirred for
3 h, and cooled to −20 °C, and the mixture containing
trichlorozirconium tert-butyl amide was added within 20 min. The
resulting orange solution was stirred for 16 h, filtered, and evaporated.
Hexane (100 mL) was added, and the precipitate of amide 16 was
filtered out and washed with pentane. The precipitate was dissolved in
CH2Cl2 (50 mL), and the resulting dark red solution was treated with
chlorotrimethylsilane (12.7 mL, 100 mmol). The mixture was stirred
for 1 h, after which hexane (100 mL) was added, and then most of the
1
NMR H spectroscopy; rac-selectivity was determined by comparison
of vinyl and/or Me2Si signals for rac and meso isomers. The yield of
the rac isomer was determined after its isolation by recrystallization.
X-ray Crystallography. Experimental intensities were measured
on a Bruker SMART APEX II diffractometer (graphite monochrom-
atized Mo Kα radiation, λ = 0.71073 Å) at 160 K using ω scan mode.
The structures were solved by direct methods and refined by full-
matrix least-squares on F2 with anisotropic thermal parameters for all
non-hydrogen atoms.21 All hydrogen atoms were placed in calculated
positions and refined using a riding model. The C(38) envelope atom
of the five-membered cycle is disordered over two positions with an
occupancy ratio of 0.57/0.43.
ASSOCIATED CONTENT
■
S
* Supporting Information
Details of crystal structure determinations, atomic coordinates,
isotropic and anisotropic displacement parameters, and bond
lengths and angles of complexes 12 and 16. Experimental
details for catalyst preparation, polymerization procedure, and
4347
dx.doi.org/10.1021/om300311k | Organometallics 2012, 31, 4340−4348
Nifant'ev, Ilya E.
