Dialkyl and Methyl-Alkyl Zirconocenes
Organometallics, Vol. 26, No. 12, 2007 3029
CH2Ph, 2H, J ) 5.4 Hz), 2.58 (s, CH2C(CH3)2CH2Ph, 2H), 1.54
(t, OH, 1H, J ) 5.4 Hz), 0.89 (s, CH2C(CH3)2CH2Ph, 6H). 13C{1H}
NMR (75 MHz, CDCl3): δ 138.95, 130.68, 128.03, 126.13, 71.41,
44.97, 36.77, 24.35. DEPT (75 MHz, CDCl3): δ 138.95, 36.77
(quaternary C), 130.68, 128.02, 126.12 (CH), 71.40, 44.98 (CH2),
24.51 (CH3).
precipitate washed three times with recycled solvent. The solvent
was removed, yielding a yellow oil, which was dried in vacuo.
(Note: this compound was generally isolated as a diethyl etherate.)
1
Yield: 0.185 g (90%). H NMR (300 MHz, C6D6): δ 7.05-7.25
(m (partially obscured by C6D6), C6H5, 5H), 2.55 (s, CH2C-
(CH3)2CH2Ph, 2H), 1.07 (s, CH2C(CH3)2CH2Ph, 6H), -1.01 (br s,
CH2C(CH3)2CH2Ph, 2H).
(2,2-Dimethyl-3-phenyl)propyl Mesylate (17). A 250 mL
round-bottom flask was charged with 16 (5.82 g, 35.4 mmol) and
purged with argon. CH2Cl2 (110 mL) was added via cannula. NEt3
(7.6 mL, 54.5 mmol) was added by syringe, and the mixture was
cooled to 0 °C. CH3SO2Cl (3.2 mL, 41.3 mmol) was added
dropwise. The solution became pale yellow and a precipitate
formed. The reaction mixture stirred at this temperature for 1 h.
For workup, additional CH2Cl2 was added and the organics were
washed with ice water (250 mL), chilled 10% HCl (250 mL),
saturated NaHCO3, and saturated NaCl. After drying over Na2SO4
the solvent was removed under reduced pressure to yield a yellow
liquid that was >95% pure by NMR. Yield: 8.50 g (quantitative).
1H NMR (300 MHz, CDCl3): δ 7.28 (m, m- and p-PhH, 3H), 7.14
(dd, o-PhH, 2H, J ) 2.1, 7.35 Hz), 3.87 (s, CH2C(CH3)2CH2Ph,
2H), 3.02 (s, CH3, 3H), 2.62 (s, CH2C(CH3)2CH2Ph, 2H), 0.98 (s,
CH2C(CH3)2CH2Ph, 6H). 13C{1H} NMR (75 MHz, CDCl3): δ
137.47, 130.66, 128.26, 126.61, 77.05, 44.81, 37.47, 35.67, 24.39.
DEPT (75 MHz, CDCl3): δ 137.47, 35.67 (quaternary C), 130.65,
128.25, 126.60 (CH), 77.05, 44.79 (CH2), 37.46, 24.39 (CH3).
Synthesis of (η5-C5H5)(η5-C5Me5)Zr(CH3)(CH2C(CH2CH3)3)
(20) (CpCp*Zr(CH3)(CH2CEt3)). In an inert atmosphere glovebox,
(η5-C5H5)(η5-C5Me5)Zr(CH3)Cl (0.129 g, 0.38 mmol) was added
to the 25 mL round-bottom flask equipped with a stir bar containing
LiCH2CEt3 (0.045 g, 0.38 mmol) and attached to a small swivel
frit assembly. On the vacuum line, diethyl ether (12 mL) was
vacuum transferred onto the reaction mixture at -78 °C. The
apparatus was backfilled with Ar, and the yellow solution was
allowed to warm to room temperature over 14 h with stirring. A
yellow solution with a white precipitate was observed. The solvent
was removed, and the oily residue was dried in vacuo. Pentane
(10 mL) was added to the oil by vacuum transfer, and the reaction
mixture was stirred briefly at room temperature to break up the
solids. The resulting white precipitate was filtered away from the
yellow filtrate and washed once with recycled solvent. Removal
of all volatiles and drying in vacuo resulted in a yellow-brown oil
(0.130 g) that was 59% product 20 as judged by 1H NMR
spectroscopy. Repeated attempts to purify this material by crystal-
lization or precipitation from concentrated pentane solutions at -35
°C failed. 1H NMR (500 MHz, C6D6): δ 5.89 (s, C5H5, 5H), 1.69
(s, C5(CH3)5, 15H), 1.43 (m, CH2C(CH2CH3)3, 3H, J ) 7.8 Hz),
1.35 (m, CH2C(CH2CH3)3, 3H, J ) 7.8 Hz), 0.83 (t, CH2C-
(CH2CH3)3, 9H, J ) 7.4 Hz), -0.13 (d, CH2C(CH2CH3)3, 1H, J )
13.4 Hz), -0.16 (d, CH2C(CH2CH3)3, 1H, J ) 13.4 Hz), -0.28 (s,
CH3, 3H).
2-Methyl-2-benzyl-1-iodopropane (18). A 50 mL flask with
condenser was charged with 17 (1.86 g, 7.67 mmol) and anhydrous
NaI (5.75 g, 38.4 mmol) and was purged with argon. N-Methylpyr-
rolidinone (16 mL) was added via syringe. The reaction mixture
was heated to 140 °C for 7 h under argon. The reaction mixture
was cooled, and water and pentane were added. The phases were
separated and the aqueous layer was extracted with pentane. The
combined organic phases (250 mL) were washed with saturated
Na2S2O3, twice with saturated CuSO4, and water. After drying over
MgSO4, the pentane was removed under reduced pressure. The
yellow liquid was purified by column chromatography on silica
with hexanes, and the product was a clear liquid that was
homogeneous by TLC. Yield: 1.77 g (84%). 1H NMR (300 MHz,
CDCl3): δ 7.25 (br m, o-, m-, and p-PhH, 5H), 3.13 (s,
CH2C(CH3)2CH2Ph, 2H), 2.65 (s, CH2C(CH3)2CH2Ph, 2H), 1.04
(s, CH2C(CH3)2CH2Ph, 6H). 13C{1H} NMR (75 MHz, CDCl3): δ
138.36, 130.46, 128.15, 126.50, 46.63, 35.08, 27.44, 24.53. DEPT
(75 MHz, CDCl3): δ 138.46, 35.08 (quaternary C), 130.45, 128.14,
126.49 (CH), 46.62, 24.67 (CH2), 27.44 (CH3).
Synthesis of (η5-C5H5)(η5-C5Me5)Zr(CH3)(CH2CMe2CH2Ph)
(21) (CpCp*Zr(CH3)(CH2CMe2CH2Ph)). In an inert atmosphere
glovebox, (η5-C5H5)(η5-C5Me5)Zr(CH3)Cl (0.410 g, 1.19 mmol) was
added to the 25 mL round-bottom flask equipped with a stir bar
containing LiCH2CMe2CH2Ph (0.185 g, 1.19 mmol) and attached
to a small swivel frit assembly. On the vacuum line, diethyl ether
(18 mL) was vacuum transferred onto the reaction mixture at -78
°C. The apparatus was backfilled with Ar, and the reaction mixture
was allowed to warm to room temperature. After stirring for 36 h
a yellow-brown solution with an off-white precipitate was observed.
The solvent was removed, and the oily residue was dried for 1 h in
vacuo. Pentane (15 mL) was added to the oil by vacuum transfer,
and the reaction mixture was stirred briefly at room temperature to
break up the solids. The resulting white precipitate was filtered
away from the dark brown filtrate and washed once with recycled
solvent. Removal of all volatiles and drying in vacuo for 1.5 h at
50 °C resulted in a dark brown oil (0.396 g) that was 71% product
21 as judged by 1H NMR spectroscopy. Repeated attempts to purify
this material by crystallization or precipitation from concentrated
Synthesis of Li(CH2C(CH3)2CH2Ph) (19) (LiCH2CMe2CH2Ph).
2-Methyl-2-benzyl-1-iodopropane (0.365 g, 1.33 mmol) was weighed
into a 25 mL round-bottom flask equipped with a 180° needle valve
and was degassed with two freeze-pump-thaw cycles at 77 K on
the high-vacuum line. Pentane and then diethyl ether were added
by vacuum transfer at -78 °C in a 3:1 ratio, respectively, to give
a total solvent volume of 12 mL. The apparatus was backfilled
with Ar and stirred briefly at room temperature. The Kontes needle
valve was replaced by a septum using a positive Ar counterflow.
The solution was then cooled to -78 °C, and a 1.7 M solution of
tert-butyllithium (1.80 mL, 2.92 mmol) was added dropwise using
an Ar-flushed syringe. A white precipitate was observed im-
mediately following the addition. The reaction mixture was stirred
at -78 °C for 35 min. The dry ice-acetone bath was removed,
and the reaction mixture was allowed to warm to room temperature
with stirring for 45 min, during which time the solution turned
yellow. The septum was replaced with a Kontes needle valve, the
solvent was removed, and the oily residue was dried in vacuo. In
the glovebox the reaction flask was attached to a small swivel frit
assembly. On the vacuum line, pentane (12 mL) was vacuum
transferred onto the oil at -78 °C. Warming to room temperature
and stirring to break up the solids resulted in a yellow solution
with a white precipitate. This solution was filtered and the
1
pentane solutions at -35 °C have failed. H NMR (300 MHz,
C6D6): δ 7.15-7.25 (m (partially obscured by C6D6), C6H5, 5H),
5.82 (s, C5H5, 5H), 2.58 (d, CH2C(CH3)2CH2Ph, 1H, J ) 12.6 Hz),
2.54 (d, CH2C(CH3)2CH2Ph, 1H, J ) 12.1 Hz), 1.64 (s, C5(CH3)5,
15H), 1.15 (s, CH2C(CH3)2CH2Ph, 3H), 0.92 (s, CH2C(CH3)2CH2-
Ph, 3H), 0.44 (d, CH2C(CH3)2CH2Ph, 1H, J ) 12.0 Hz), -0.27 (s,
CH3, 3H), -0.33 (d, CH2C(CH3)2CH2Ph, 1H, J ) 12.7 Hz).
Synthesis of (η5-C5H5)2Zr(CH3)(CH2C(CH2CH3)3) (22) (Cp2Zr-
(CH3)(CH2CEt3)). 2,2-Diethyl-1-iodobutane (0.274 g, 1.14 mmol)
was weighed into a 25 mL round-bottom flask equipped with a
180 ° needle valve and was degassed at 77 K on the high-vacuum
line. Pentane (8 to 10 mL) and then diethyl ether (2 to 4 mL) were
added by vacuum transfer at -78 °C. The apparatus was backfilled
with Ar and stirred briefly at room temperature. The Kontes needle
valve was replaced by a septum using a positive Ar counterflow.
The solution was then cooled to -78 °C, and a 1.7 M solution of