Zirconium and Hafnium Complexes
Organometallics, Vol. 24, No. 5, 2005 865
28.87 (2C, i-Bu CH3), 29.28 (1C, i-Bu CH), 29.44 (2C, i-Bu CH3),
29.74 (1C, i-Bu CH), 42.75 (1C, NCH3), 53.18 and 59.45
(2C each, ligand CH2), 90.00 and 91.24 (1C each, i-Bu CH2),
125.20, 128.47, 135.26, and 148.16 (12C, Ph). Anal. Calcd for
C25H35N3Cl4Hf: C, 43.03; H, 5.06; N, 6.02; Cl, 20.32. Found:
C, 42.87; H, 5.12; N, 6.09; Cl, 20.43.
standard Ph2CH2 (0.048 mmol) in C6D5Br (X, Y ) (1.0 - X -
H) mL, respectively; H ) volume of 1-hexene to be added later
in polymerization reactions only) were cooled to -30 °C and
mixed. Activation was almost immediate for the {Ph3C}-
{B(C6F5)4}, B(C6F5)3, and {PhNMe2H}{B(C6F5)4} activators and
accompanied by a change in color of the solution from deep
orange to yellow when {Ph3C}{B(C6F5)4} was the activator. The
reaction was transferred to an NMR tube, which was frozen
in liquid nitrogen, and the solution was thawed to 0 °C at time
) 0.
[ArClN2NMe]HfCl(i-Bu). [ArClN2NMe]HfCl2 (0.520 g, 0.793
mmol) was suspended in 25 mL of diethyl ether and cooled to
-30 °C. A diethyl ether solution (0.350 mL, 0.915 mmol) of
2.61 M (i-Bu)MgCl was cooled to -30 °C and added to the
reaction, which was stirred at room temperature for 1 h.
Dioxane (80 mg) was added and the reaction filtered through
Celite. The filtrate was concentrated in vacuo, and the result-
ing pale yellow solid was washed with 10 mL of pentane and
dried in vacuo; yield 0.487 g (91%). Two isomers are observed
in solution: 1H NMR (C6D6) δ 0.59 (d, 2H, i-Buanti CH2), 0.82
(d, 2H, i-Busyn CH2), 1.17 (d, 6H, i-Buanti CH3), 1.26 (d, 6H,
i-Busyn CH3), 2.24 (s, 3H, NCH3), 2.24 (s, 3H, NCH3), 2.16, 2.71,
3.27, and 3.53 (m, 2H each, ligand CH2 for i-Busyn isomer), 2.16,
2.71, 3.17, and 3.81 (m, 2H each, ligand CH2 for i-Buanti
isomer), 6.38 (t, 2H, p-CH), 6.38 (t, 2H, p-CH), 7.08 (d, 4H,
m-CH), 7.09 (d, 4H, m-CH). Anal. Calcd for C21H26N3Cl5Hf:
C, 37.30; H, 3.88; N, 6.21; Cl, 26.21. Found: C, 37.23; H, 3.95;
N, 6.12; Cl, 26.30.
General Procedure for Polymerization Reactions.
[ArClN2NMe]MR2 (M ) Hf, Zr) was activated as described
previously, and 1-hexene (50-500 equiv) was immediately
added to the vigorously stirred, cooled (-30 °C) solution. The
reaction was transferred to an NMR tube, which was frozen
in liquid nitrogen and then thawed in the NMR probe at 0 °C.
Upon complete consumption of 1-hexene, the reactions were
quenched with methanol. After solvent removal, the polymer
was dissolved in pentane and the solution filtered through
silica gel. The solvent was removed in vacuo to give poly[1-
hexene] in 100% yield.
1
{[ArClN2NMe]ZrMe}{B(C6F5)4}. H NMR (0 °C, C6D5Br):
δ 0.62 (s, 3H, HfCH3), 2.34 (s, 3H, NCH3), 2.65, 2.91, 3.76, and
3.83 (m, 2H each, ligand CH2), 6.50 (t, 2H, p-H), 6.96 (d, 4H,
m-H).
[ArClN2NMe]Hf13Me(i-Bu). [ArClN2NMe]HfCl(i-Bu) 0.126
g, 0.187 mmol) was suspended in 10 mL of diethyl ether and
cooled to -30 °C. A diethyl ether solution (0.205 mL, 0.306
mmol) of 0.8 M 13MeMgCl was cooled to -30 °C and added to
the reaction, which was stirred at room temperature for 1 h.
Dioxane (80 mg) was added and the reaction filtered through
Celite. The filtrate was concentrated in vacuo to 4 mL and
stored for several days. The product precipitated as white
microcrystals containing dioxane, which were collected via
filtration and redissolved in toluene. The solvent was re-
moved in vacuo to yield a white powder; yield 0.089 g (73%).
[ArClN2NMe]HfMe(i-Bu) was also synthesized using a similar
1
{[ArClN2NMe]HfMe}{B(C6F5)4}. H NMR (0 °C, C6D5Br):
δ 0.49 (s, 3H, HfCH3), 2.36 (s, 3H, NCH3), 2.62, 2.95, 3.80, and
3.90 (m, 2H each, ligand CH2), 6.57 (t, 2H, p-H), 6.96 (d, 4H,
m-H).
{[ArClN2NMe]HfMe}{MeB(C6F5)3}. 1H NMR (20 °C,
C6D5Br): δ 0.80 (s, 3H, HfCH3), 1.12 (MeB(C6F5)3) 2.41 (s, 3H,
NCH3), 2.86, 2.23, 3.62, and 3.90 (m, 2H each, ligand CH2),
6.62 (t, 2H, p-H), 7.18 (d, 4H, m-H).
{[ArClN2NMe]HfMe(NMe2Ph)}{B(C6F5)4}. 1H NMR (0 °C,
C6D5Br): δ 0.18 (v br s, 3H, HfCH3), 2.39 (s, 3H, NCH3), 2.45
(m, 2H, ligand CH2), 2.58 (s, 6H, NMe2Ph), 2.95 and 3.46 (br
s, 2H each, ligand CH2), 3.30 (v br s, 2H, ligand CH2), 6.72 (t,
2H, p-H), 7.19 (d, 4H, m-H), 6.0-7.2 ppm (5H, NMe2Ph aryl
H’s).
1
method, and two isomers are observed in solution. H NMR
(C6D5Br): δ -0.13 (s, 3H, Meanti), 0.17 (d, 2H, i-Buanti CH2),
0.38 (s, 3H, Mesyn), 0.52 (d, 2H, i-Busyn CH2), 0.76 (d, 6H, i-Buanti
CH3), 0.95 (d, 6H, i-Busyn CH3), 1.52 (m, 1H, i-Buanti CH), 2.23
(m, 1H, i-Busyn CH), 2.41 (s, 3H, NCH3), 2.45 (s, 3H, NCH3),
2.48, 3.00, 3.57, and 3.61 (m, 2H each, ligand CH2 for i-Busyn
isomer), 2.48, 3.00, 3.45, and 3.70 (m, 2H each, ligand CH2 for
i-Buanti isomer), 6.64 (t, 2H, p-CH), 6.65 (t, 2H, p-CH), 7.12 (d,
4H, m-CH), 7.14 (d, 4H, m-CH). 13C NMR (C6D5Br): δ 28.48
(1C, i-Busyn CH), 28.85, (2C, i-Buanti CH3), 28.88 (1C, i-Buanti
CH), 29.16 (2C, i-Busyn CH3), 41.33 (1C, NCH3 for i-Busyn
isomer), 41.91 (1C, NCH3 for i-Buanti isomer), 53.06 and 57.29
(2C each, ligand CH2 for i-Busyn isomer), 53.26 and 56.92 (2C
each, ligand CH2 for i-Buanti isomer), 56.01 (1C, CH3 syn),
58.19 (1C, CH3 anti), 86.99 (1C, i-Busyn CH2), 89.60 (1C, i-Buanti
CH2), 125.18, 128.36, 135.21, and 147.73 (12C, Ph for
i-Buanti isomer), 125.22, 128.36, 135.42, and 147.57 (12C, Ph
for i-Busyn isomer). 13C NMR (C6D5CD3): δ 56.38 (1C, 13Mesyn),
59.19 (1C, 13Meanti). Anal. Calcd for C22H29N3Cl4Hf: C, 40.29;
H, 4.46; N, 6.41; Cl, 21.62. Found: C, 40.21; H, 4.38; N, 6.50;
Cl, 21.54.
{[ArClN2NMe]Hf(i-Bu)}{B(C6F5)4}. 1H NMR (0 °C,
C6D5Br): δ 0.92 (br s, 6H, i-Bu CH3), 0.95 (br s, 2H, i-Bu
CH2), 2.55 (s, 3H, NCH3), 2.55 (br s, 1H, i-Bu CH), 2.62,
3.07, 3.76, and 3.86 (m, 2H each, ligand CH2), 6.53 to 7.20
(aryl H’s).
{[ArClN2NMe]Hf(i-Bu)}{HB(C6F5)3}. 1H NMR (0 °C,
C6D5Br): δ 0.91 (br s, 6H, i-Bu CH3), 0.96 (br s, 2H, i-Bu CH2),
2.58 (s, 3H, NCH3), 2.58 (br s, 1H, i-Bu CH), 2.66 and 3.10
and 3.71 and 3.81 (m, 2H each, ligand CH2), 6.55 (t, 2H, p-H),
1
6.95 (d, 4H, m-H). H NMR (0 °C, C6D5CD3): δ 0.88 (d, 6H,
i-Bu CH3), 1.02 (d, 2H, i-Bu CH2), 2.39 (s, 3H, NCH3), 2.39 (p,
1H, i-Bu CH), 2.88, 2.92, 3.49, and 3.54 (m, 2H each, m, ligand
CH2), 6.35 (t, 2H, p-H), 6.82 (d, 4H, m-H).
{[ArClN2NMe]Hf(C8H17)}{HB(C6F5)3} (isobutyl 1,2 in-
sertion product). 1H NMR (0 °C, C6D5Br): δ 0.57 (d, 6H,
CH3), 0.81 (s, 6H, CH3) 0.91 (d, 2H, CH2), 1.16 (s, 2H, CH2),
1.26 (p, 1H, CH), 2.60 (s, 3H, NCH3), 2.71, 3.11, 3.72, and
4.03 (m, 2H each, ligand CH2), 6.56 (t, 2H, p-H), 6.96 (d, 4H,
m-H).
The Meanti f Mesyn isomerization process in [ArClN2NMe]-
Hf(i-Bu)Me was studied by observing the disappearance of the
Meanti 1H NMR resonance and the growth of the Mesyn
resonance in relation to a known Ph3CH standard. Thermo-
dynamic parameters were calculated by employing Van’t Hoff
and Eyring plots. The data are the following: T ) 50 °C, K )
1.10, k1 ) 0.000593 s-1; 60 °C, 1.13, 0.00136 s-1; 65 °C, 1.15,
Asymmetric Product of the Reaction of {[ArClN2NMe]-
Hf(i-Bu)}{B(C6F5)4}
with
Dimethylaniline
and
{HNMe2Ph}{B(C6F5)4} Activation of {[ArClN2NMe]Hf(i-
Bu)2. 1H NMR (20 °C): δ 1.48 (s, 3H), 2.46 (s, 3H), 2.58 (s,
3H), 2.18, 2.31, 2.60, 3.20, 3.26, 3.34, 3.68, 4.32, 4.51 (m, 1H
each), 2.90 and 3.20 (dd, 2H), 3.16 (d, 1H), 5.85 (t, 1H), 6.59
(d, 2H), 6.62 and 6.72 (t, 1H each, m-H), 6.78-6.86 (m, 2H),
7.05 (d, 2H), 7.08-7.20 (m).
0.00268 s-1; 70 °C, 1.16, 0.00425 s-1; 75 °C, 1.18, 0.00699 s-1
80 °C, 1.20, 0.0990 s-1
;
.
General Procedure for Activation of [ArClN2NMe]MR2
(M ) Hf, Zr). Solutions of [ArClN2NMe]MR2 (0.003-0.012
mmol; 1 equiv) and {Ph3C}{B(C6F5)4} (0.003-0.012 mmol; 1
equiv), B(C6F5)3 (0.003-0.012 mmol; 1 equiv), or {HNMe2Ph}-
{B(C6F5)4} (0.003-0.012 mmol; 1 equiv) and the internal
Acknowledgment. We thank the Department of
Energy (DE-FG02-86ER13564) for supporting this re-
search.