For synthesis of cyclopentadienyl-fluorenyl zirconocenes (Fig. 32), a solution of
42 mmol of 2 in 300 mL of THF is cooled to À78
C. At this temperature, 56.33 mL
(84 mmol) of a 1.6 M solution of methyllithium in diethylether is added dropwise.
After 2 h, the cooling bath is removed and the red solution is stirred at room
temperature for 8 h. Then, the solvent is removed in vacuo, resulting in an orange
powder. This powder is suspended in 300 mL of pentane. Then 42 mmol of
zirconium tetrachloride suspended in 100 mL of pentane is added. The mixture is
stirred at room temperature for 6 h. Then, the insoluble red raw product is isolated
by filtration. To separate from the lithium chloride, the raw product is taken up in
500 mL of methylene chloride and the turbid solution filtered over dried kieselgur.
The resulting clear red solution is slowly evaporated and the product is isolated as a
red crystalline precipitate [187, 188].
In Fig. 32, for R ¼ Me the formula is C 21 H 18 Cl 2 Zr. Percentage composition by
analysis: C, 58.06; H, 4.14; Cl, 16.34; Zr, 20.99%. Percentage composition by
calculation: C, 58.17; H, 4.19; Cl, 16.34; Zr, 20.07%.
For R ¼Me, results of
1 H NMR (CD 2 Cl 2 ) ppm: δ ¼ 8.1 (2H, m, 4,5-Flu), 7.8
(2H, m, 1,8-Flu), 7.5 (2H, m, 3,6-Flu), 7.2 (2H, m, 2,7-Flu), 6. 3 (2H, t, 3,4-Cp), 5.7
(1H, t, 2,5-Cp), 2.3 (6H, s, bridge-CH 3 ), where m, t and s signify multiplet, triplet
and singlet, respectively.
For R ¼ Ph, results of
1 H NMR (CD 2 Cl 2 ) ppm: δ ¼ 8.19 (2H, m, 4,5-Flu), 7.95
(2H, m, 2-Ph), 7.88 (2H, m, 5-Ph) 7.56 (2H, m, 3,6-Flu), 7.47 (2H, m, 4-Ph), 7.35
(2H, m, 3-Ph), 6.99 (2H, m, 2,7-Flu), 6.43 (2H, m, 1,8-Flu), 6.37 (2H, t, 3,4-Cp),
5.80 (2H, t, 2,5-Cp).
+
2
R
R
R R
Li+
-
+ H 2 O
- LiOH
Fig. 31 General synthetic scheme for the preparation of bridged cyclopentadienyl-fluorenyl
ligand (2)
a) 2 MeLi
b) ZrCl 4
1
R
R
ZrCl 2
2
R
R
+ 2 LiCl
Fig. 32 General synthetic scheme for the preparation of bridged cyclopentadienyl-fluorenyl
zirconocenes (1)
108
A. Razavi
42 mmol of 2 in 300 mL of THF is cooled to À78
C. At this temperature, 56.33 mL
(84 mmol) of a 1.6 M solution of methyllithium in diethylether is added dropwise.
After 2 h, the cooling bath is removed and the red solution is stirred at room
temperature for 8 h. Then, the solvent is removed in vacuo, resulting in an orange
powder. This powder is suspended in 300 mL of pentane. Then 42 mmol of
zirconium tetrachloride suspended in 100 mL of pentane is added. The mixture is
stirred at room temperature for 6 h. Then, the insoluble red raw product is isolated
by filtration. To separate from the lithium chloride, the raw product is taken up in
500 mL of methylene chloride and the turbid solution filtered over dried kieselgur.
The resulting clear red solution is slowly evaporated and the product is isolated as a
red crystalline precipitate [187, 188].
In Fig. 32, for R ¼ Me the formula is C 21 H 18 Cl 2 Zr. Percentage composition by
analysis: C, 58.06; H, 4.14; Cl, 16.34; Zr, 20.99%. Percentage composition by
calculation: C, 58.17; H, 4.19; Cl, 16.34; Zr, 20.07%.
For R ¼Me, results of
1 H NMR (CD 2 Cl 2 ) ppm: δ ¼ 8.1 (2H, m, 4,5-Flu), 7.8
(2H, m, 1,8-Flu), 7.5 (2H, m, 3,6-Flu), 7.2 (2H, m, 2,7-Flu), 6. 3 (2H, t, 3,4-Cp), 5.7
(1H, t, 2,5-Cp), 2.3 (6H, s, bridge-CH 3 ), where m, t and s signify multiplet, triplet
and singlet, respectively.
For R ¼ Ph, results of
1 H NMR (CD 2 Cl 2 ) ppm: δ ¼ 8.19 (2H, m, 4,5-Flu), 7.95
(2H, m, 2-Ph), 7.88 (2H, m, 5-Ph) 7.56 (2H, m, 3,6-Flu), 7.47 (2H, m, 4-Ph), 7.35
(2H, m, 3-Ph), 6.99 (2H, m, 2,7-Flu), 6.43 (2H, m, 1,8-Flu), 6.37 (2H, t, 3,4-Cp),
5.80 (2H, t, 2,5-Cp).
+
2
R
R
R R
Li+
-
+ H 2 O
- LiOH
Fig. 31 General synthetic scheme for the preparation of bridged cyclopentadienyl-fluorenyl
ligand (2)
a) 2 MeLi
b) ZrCl 4
1
R
R
ZrCl 2
2
R
R
+ 2 LiCl
Fig. 32 General synthetic scheme for the preparation of bridged cyclopentadienyl-fluorenyl
zirconocenes (1)
108
A. Razavi