8748 J. Am. Chem. Soc., Vol. 123, No. 36, 2001
Cheng et al.
1
(BDI-2)ZnEt. H NMR (C6D6, 300 MHz): δ 7.04 (6H, b, ArH),
revealed that the complex exists as a µ-methoxide-bridged dimer in
the solid state (see Supporting Information).
4.92 (1H, s, â-CH), 2.60 (4H, m, J ) 7.5 Hz, CH2CH3), 2.45 (4H, m,
J ) 7.5 Hz, CH2CH3), 1.62 (6H, s, R-Me), 1.16 (12H, t, J ) 7.5 Hz,
CH2CH3), 0.95 (3H, t, J ) 8.0 Hz, CH2CH3), 0.25 (2H, q, J ) 8.0 Hz,
CH2CH3). 13C{1H} NMR (C6D6, 75 MHz): δ 167.00, 146.83, 136.93,
126.74, 125.38, 95.42, 25.19, 22.99, 14.57, 12.12, -1.98.
[(BDI-3)Zn(µ-OMe)]2. To a solution of (BDI-3)ZnEt (0.475 g, 0.928
mmol, 1 equiv) in toluene (7 mL) was added methanol (0.040 mL,
0.988 mmol, 1.06 equiv) at room temperature. After being stirred for
1 h at room temperature, the clear solution was dried in vacuo (1H
NMR shows only 25% conversion). Excess methanol (0.20 mL, 4.9
mmol, 5.3 equiv) was then added at room temperature. After being
stirred for 1.5 h at room temperature, the clear solution was dried in
vacuo (1H NMR shows 100% conversion and decomposition to the
ligand) and then recrystallized from hexane at -20 °C to give clear
1
(BDI-3)ZnEt. H NMR (C6D6, 300 MHz): δ 7.04 (6H, b, ArH),
4.92 (1H, s, â-CH), 2.65 (4H, m, J ) 7.5 Hz, CH2CH2CH3), 2.45 (4H,
m, J ) 7.5 Hz, CH2CH2CH3), 1.68 (14H, m, CH2CH2CH3 + R-Me),
1.16 (15H, t, J ) 7.5 Hz, CH2CH3 + CH2CH2CH3), 0.26 (2H, q, J )
8.0 Hz, CH2CH3).
1
1
block crystals (0.070 g, 15%). H NMR (C6D6, 300 MHz): δ 7.05
(BDI-4)ZnEt. H NMR (C6D6, 300 MHz): δ 6.96 (6H, b, ArH),
(6H, m, ArH), 4.64 (1H, s, â-CH), 3.65 (3H, s, OCH3), 2.59 (4H, m,
J ) 7.5 Hz, CH2CH2CH3), 2.12 (4H, m, J ) 7.5 Hz, CH2CH2CH3),
1.61 (8H, sextet, J ) 7.5 Hz, CH2CH2CH3), 1.45 (6H, s, R-Me), 1.00
(12H, t, J ) 7.5 Hz, CH2CH2CH3).
4.91 (1H, s, â-CH), 2.10 (12H, s, o-CH3), 1.56 (6H, s, R-Me), 0.97
(3H, t, J ) 8.0 Hz, CH2CH3), 0.25 (2H, q, J ) 8.0 Hz, CH2CH3).
1
(BDI-5)ZnEt. H NMR spectroscopic analysis revealed only one
set of peaks which we have tentatively assigned to the cis isomer since
only the cis isomer of [(BDI-5)ZnOMe]2 is formed from (BDI-5)ZnEt
[(BDI-4)Zn(µ-OMe)]2. The conversion was quantitative. The color-
1
(vide infra). H NMR (toluene-d8, 300 MHz): δ 7.05 (6H, b, ArH),
less solid was recrystallized from toluene at 5 °C to give colorless block-
1
4.94 (1H, s, â-CH), 3.16 (2H, m, CHMe2), 2.60 (2H, m, CH2CH3),
2.46 (2H, m, CH2CH3), 1.66 (6H, s, R-Me), 1.21 (18H, m, CHMe2 +
CH2CH3), 0.85 (3H, t, J ) 8.0 Hz, CH2CH3), 0.16 (2H, q, J ) 8.0 Hz,
CH2CH3).
(BDI-6)ZnEt. 1H NMR spectroscopic analysis revealed a 1:1 mixture
of the cis and trans isomers, although assignment of the shifts was not
possible.1H NMR (C6D6, 300 MHz): δ 7.01-7.14 (12H, m, ArH), 4.94
(1H, s, â-CH), 4.93 (1H, s, â-CH), 3.18 (4H, m, J ) 7.0 Hz, CHMe2),
2.52 (8H, m, CH2CH2CH3), 1.67 (20H, b, R-Me + CH2CH2CH3), 1.26
(6H, d, J ) 7.0 Hz, CHMeMe), 1.24 (6H, d, J ) 7.0 Hz, CHMeMe),
1.18 (6H, d, J ) 7.0 Hz, CHMeMe), 1.14 (6H, d, J ) 7.0 Hz,
CHMeMe), 0.95 (18H, m, CH2CH2CH3 + CH2CH3), 0.24 (4H, q, J )
8.0 Hz, CH2CH3).
(BDI-7)ZnEt. 1H NMR spectroscopic analysis revealed a 1:1 mixture
of the cis and trans isomers, although assignment of the shifts was not
possible.1H NMR (C6D6, 300 MHz): δ 7.07 (12H, m, ArH), 4.95 (1H,
s, â-CH), 4.94 (1H, s, â-CH), 3.16 (4H, m, CHMe2), 2.13 (12H, s,
o-Me), 1.62 (12H, s, R-Me), 1.20 (12H, d, J ) 7.0 Hz, CHMeMe),
1.14 (12H, d, J ) 7.0 Hz, CHMeMe), 0.95 (6H, t, J ) 8.0 Hz, CH2CH3),
0.24 (4H, q, J ) 8.0 Hz, CH2CH3).
shape crystals (52% yield). H NMR (C6D6, 300 MHz): δ 7.01 (6H,
b, ArH), 4.65 (1H, s, â-CH), 3.59 (3H, s, OCH3), 1.99 (12H, s, o-CH3),
1.39 (6H, s, R-Me). X-ray analysis of the crystals revealed that the
complex exists as a µ-methoxide-bridged dimer in the solid state (see
Supporting Information).
[(BDI-5)Zn(µ-OMe)]2. To a solution of (BDI-5)ZnEt (0.528 g, 1.09
mmol) in toluene (10 mL) was added methanol (0.15 mL, 3.4 mmol,
3.4 equiv) at room temperature. After being stirred for 1 h at room
temperature, the suspension was filtered over a frit, and the clear
solution was dried in vacuo and then recrystallized from toluene at
-30 °C to give colorless needle-shape crystals (0.201 g, 38%). 1H NMR
(toluene-d8, 300 MHz): δ 7.07 (6H, b, ArH), 4.94 (1H, s, â-CH), 3.28
(3H, s, OCH3), 2.97 (2H, m, CHMe2), 2.46 (2H, m, CHHCH3), 2.35
(2H, m, CHHCH3), 1.56 (6H, s, R-Me), 1.20 (18H, m, CHMe2 and
CH2CH3). X-ray analysis of the crystals revealed that the complex exists
as a µ-methoxide-bridged dimer in the solid state, where the ligand
adopts a cis geometry and the dimer is of C2h symmetry (see Supporting
Information).
[(BDI-7)Zn(µ-OMe)]2. The crude material was recrystallized from
toluene at -30 °C to give colorless needle-shape crystals (49% yield).
1H NMR (C6D6, 300 MHz): δ 7.08 (6H, m, ArH), 4.56 (1H, s, â-CH),
3.65 (3H, s, OCH3), 3.41 (2H, m, CHMe2), 1.75 (6H, s, o-Me), 1.45
(6H, s, R-Me), 1.35 (6H, d, J ) 7.0 Hz, CHMeMe), 1.28 (6H, d, J )
7.0 Hz, CHMeMe). X-ray analysis of the crystals revealed that the
complex exists as a µ-methoxide-bridged dimer in the solid state, where
the ligand adopts a cis geometry and the dimer is of C2h symmetry
(see Supporting Information).
[(BDI-11)Zn(µ-OMe)]2. The crude material was recrystallized from
toluene at -30 °C to give colorless block-shape crystals (59% yield).
1H NMR (C6D6, 300 MHz): δ 7.16 (2H, d, R-H), 7.06 (6H, m, ArH),
4.40 (1H, t, â-CH), 3.64 (3H, s, OCH3), 3.31 (4H, m, CHMe2), 1.13
(12H, d, J ) 7.0 Hz, CHMeMe), 0.91 (12H, d, J ) 7.0 Hz, CHMeMe).
13C{1H} NMR (C6D6, 100 MHz): δ 163.69, 142.28, 125.61, 125.45,
123.38, 88.30, 55.61, 27.94, 25.31, 22.62. X-ray analysis of the crystals
revealed that the complex exists as a µ-methoxide-bridged dimer in
the solid state (see Supporting Information).
(BDI-8)2Zn. Refer to the general synthetic procedure for [(BDI)-
Zn(µ-OMe)]2. After being stirred for 1 h at room temperature, the
suspension was filtered over a frit. The clear solution was dried in vacuo
and then recrystallized from pentane at 5 °C to give light yellow block-
shaped crystals (41%). 1H NMR (C6D6, 300 MHz): δ 6.80-7.60 (16H,
m, ArH), 4.71 (2H, s, â-CH), 3.24 (2H, m, J ) 7.0 Hz, CHMe2), 2.75
(2H, m, J ) 7.0 Hz, CHMe2), 1.82 (6H, s, R-Me), 1.41 (6H, s, R-Me),
1.29 (6H, d, J ) 7.0 Hz, CHMeMe), 1.12 (6H, d, J ) 7.0 Hz,
CHMeMe), 0.94 (6H, d, J ) 7.0 Hz, CHMeMe), 0.43 (6H, d, J ) 7.0
Hz, CHMeMe). X-ray analysis of the crystals revealed that the complex
exists as a bis-ligated structure in the solid state, where the ligand adopts
a cis geometry (see Supporting Information).
(BDI-8)ZnEt. 1H NMR spectroscopic analysis revealed an ap-
proximately 1:1 mixture of the cis and trans isomers, although
assignment of the shifts was not possible. 1H NMR (C6D6, 300 MHz):
δ 7.17 (4H, m, ArH), 7.00 (8H, m, ArH), 6.78 (4H, m, ArH), 4.95
(1H, s, â-CH), 4.89 (1H, s, â-CH), 3.19 (4H, m, CHMe2), 1.72 (6H, s,
R-Me), 1.69 (6H, s, R-Me), 1.19 (12H, m, CHMeMe), 1.11 (12H, m,
CHMeMe), 1.02 (3H, m, CH2CH3), 0.97 (3H, m, CH2CH3), 0.35 (2H,
m, CH2CH3), 0.28 (2H, m, CH2CH3).
1
(BDI-11)ZnEt. H NMR (C6D6, 300 MHz): δ 7.19 (2H, d, R-H),
7.12 (6H, b, ArH), 4.81 (1H, t, â-CH), 3.28 (4H, m, CHMe2), 1.22
(12H, d, J ) 7.0 Hz, CHMeMe), 1.14 (12H, d, J ) 7.0 Hz, CHMeMe),
1.05 (3H, t, J ) 8.0 Hz, CH2CH3), 0.42 (2H, q, J ) 8.0 Hz, CH2CH3).
General Procedure for [(BDI)Zn(µ-OMe)]2. To a solution of (BDI-
2)ZnEt (1.35 g, 2.97 mmol, 1 equiv) in toluene (10 mL) was added
methanol (0.13 mL, 3.20 mmol, 1.1 equiv) at room temperature. After
being stirred for 1 h at room temperature, the clear solution was dried
in vacuo. This procedure is used throughout unless otherwise noted.
[(BDI-1)Zn(µ-OMe)]2. Instead of the normal 1.1 equiv of methanol,
5 equiv was added, and the clear solution was dried in vacuo after
being stirred for 1 h at room temperature, giving a quantitative yield
of the desired compound as a colorless oily solid. 1H NMR (C6D6, 300
MHz): δ 7.13 (6H, m, ArH), 4.87 (1H, s, â-CH), 3.30 (3H, s, OCH3),
2.97 (4H, m, CHMe2), 1.53 (6H, s, R-Me), 1.20 (12H, d, J ) 6.5 Hz,
CHMeMe), 1.16 (12H, d, J ) 6.5 Hz, CHMeMe). Despite several
attempts, X-ray diffraction quality crystals of this compound were not
obtained.
[(BDI-2)Zn(µ-OMe)]2. The crude material was recrystallized from
toluene at -30 °C to give colorless block-shape crystals (0.98 g, 72%).
1H NMR (C6D6, 300 MHz): δ 7.09 (6H, m, ArH), 4.64 (1H, s, â-CH),
3.53 (3H, s, OCH3), 2.55 (4H, m, J ) 7.5 Hz, CH2CH3), 2.20 (4H, m,
J ) 7.5 Hz, CH2CH3), 1.41 (6H, s, R-Me), 1.13 (12H, t, J ) 7.5 Hz,
CH2CH3). 13C{1H} NMR (C6D6, 75 MHz): δ 168.32, 147.48, 137.12,
126.12, 124.67, 94.34, 55.42, 23.62, 13.95. X-ray analysis of the crystals
(BDI-2)2Zn. Refer to the synthetic procedure for [(BDI-2)Zn(µ-
OAc)]2; however, 0.5 equiv of Zn(OAc)2 is used. 1H NMR (C6D6, 300
MHz): δ 6.98 (12H, b, ArH), 4.74 (2H, s, â-CH), 3.11 (2H, b, CH2-
CH3), 2.55 (2H, b, CH2CH3), 2.15 (2H, b, CH2CH3), 1.85 (2H, b, CH2-
CH3), 1.60 (8H, b, CH2CH3), 1.26 (12H, b, R-Me), 1.26 (12H, b,