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L.V. Parfenova et al. / Journal of Organometallic Chemistry 694 (2009) 3725–3731
chloride or toluene (benzene), 2–100 mmol of hexene-1 and 2–
3. Conclusion
120 mmol of AlR3. The reaction mixture was stirred for 24 h at
22 °C. Then the mixture was decomposed with 10% HCl or DCl at
0 °C. The products were extracted with benzene; further, the or-
ganic layer was dried over Na2SO4 and analyzed by GC or GC–MS.
The influence of the organoaluminium compound nature, Zr p-
ligand environment, solvent type and reagent ratio on the che-
moselectivity of reactions of trialkylalanes (AlMe3, AlEt3) with al-
kenes, catalyzed with L2ZrCl2 has been studied. In the case of
AlMe3, the hydro- and carboalumination products, and alkene di-
mers are formed. The catalytic reaction of AlEt3 with the olefins
yields aluminacyclopentanes altogether with the hydro- and car-
boalumination products, and the dimers. It was shown that the
4.2.1. 1-Dimethylalumina-2-methylhexane (2a)
2
1H NMR (C7D8) d 0.09, 0.11 (AB, dd, JHH = 14.2 Hz, 2H, AlCH2);
3
1.60–1.72 (m, 1H, CH); 0.96 (d, JHH = 6.8 Hz, 3H, CH3); 1.18–1.41
3
(m, 6H, CH2); 0.92 (t, JHH = 6.9 Hz, 3H, CH3); ꢄ0.27 (s, 6H, MeAl).
13C NMR (C6D6) d 20.89 (br, C1), 30.54 (C2), 41.79 (C3), 29.88 (C4),
23.02 (C5), 14.02 (C6), 24.52 (C7), ꢄ7.40 (MeAl). 27Al NMR (C6D6)
d 155.9.
OAC nature and Zr
p-complex structure exhibit the most effect
on the reactions pathway.
The reaction of alkenes with AlMe3, which runs in chlorinated sol-
vents (CH2Cl2) in the presence of Zr complexes with small
(Cp and Cp0), yields mainly dimers. The use of Zr complexes substi-
tuted with more bulky
-ligands (Cp*, Ind) and chlorine-containing
solvents (CH2Cl2) increases the carboalumination products yield.
The chlorinated solvent replacement with hydrocarbons in reaction
with AlEt3 substantially increases the yield of aluminacyclopentanes.
We found that reaction of hexene-1 with AlMe3 in the presence
p-ligands
4.2.2. 1-Diethylalumina-2-ethylhexane (3a)
1H NMR (C7D8) d 0.48 (m, 2H, AlCH2CH), 1.59–1.62 (m, 1H, CH),
1.21–1.49 (m, 8H, CH2), 0.90–0.95 (m, 6H, CH3), 0.24–0.31 (m, 4H,
p
3
AlCH2CH3), 1.14 (t, JHH = 8.0 Hz, 6H, AlCH2CH3). 13C NMR (C6D6) d
18.56 (br, C1), 36.58 (C2), 38.51 (C3), 31.21 (C4), 23.09 (C5), 13.95
(C6), 29.52 (C7), 11.23 (C8), 7.59 (CH3CH2Al), 2.40 (br., CH2Al).
27Al NMR (C6D6) d 166.9.
´
of either L2ZrH2 or L2ZrHCl (L = Cp, Cp) both under the catalytic and
stoichiometric conditions results in the same products as in the
case of L2ZrCl2. This fact implies participation of zirconcene hy-
drides as intermediates in the reaction of alkenes with AlR3, cata-
lyzed with L2ZrCl2.
The probable reaction mechanism is proposed. The mechanism
includes four catalytic cycles A–D, where the complex
[L2ZrRClꢂAlR3] is the key intermediate of the whole process.
4.2.3. 1-Deuterio-2-methylhexane (7a)
1H NMR (CDCl3)
d 0.90–0.93 (m, 2H, CH2D), 0.94 (d,
3
3JHH = 6.8 Hz, 3H, CH3CH), 0.96 (t, JHH = 6.0 Hz, 3H, CH3), 1.48–
1.52 (m, 1H, CH), 1.18–1.21 (m, 4H, CH2), 1.32–1.36 (m, 2H,
CH2CH3). 13C NMR (CDCl3) d 22.53 (t, C1, JC–D = 18.9 Hz), 29.90
(C2), 38.95 (C3), 31.46 (C4), 23.19 (C5), 14.35 (C6), 22.83 (C7). MS
m/z: 101 [M+].
4. Experimental
4.2.4. Deuterio-2-ethylhexane (7b)
1H NMR (CDCl3) d 0.82–0.95 (m, 8H, CH3, CH2D); 1.22–1.39 (m,
5H, CH, CH2); 1.04–1.15, 1.26–1.35 (AB, m, 1H, CHCH2); 1.10–1.18,
4.1. General
1.24–1.35 (AB, m, 1H, CHCH2). 13C NMR (CDCl3) d 18.88 (t, C1, JC–D
=
All operations with organometallic compounds were carried out
under argon using Schlenk techniques. Solvents (benzene and tol-
uene) were dried by refluxing over i-Bu2AlH and freshly distilled
prior to use. Methylene chloride was dried over P2O5. Commer-
cially available 98% AlEt3 and 97% AlMe3 (Aldrich) were involved
into the reactions. The catalysts L2ZrCl2 were prepared using the
standard techniques from ZrCl4 (99.5%, Aldrich) (L = Cp [14a], Cp0
19.0 Hz), 34.30 (C2), 36.46 (C3), 29.50 (C4), 23.03 (C5), 14.22 (C6),
29.47 (C7), 11.36 (C8). MS m/z: 115 [M+].
Spectral data of products were identical to those of authentic
sample 2a [17], 2b [16], 3 [8], and 16 [4a].
4.3. Reaction of hexene-1 with AlR3 in the presence of L2ZrH2 (L = Cp,
Cp0)
[14b], Ind [14c], Flu [14d]). Cpꢀ ZrCl2 (97%) was purchased from Al-
2
drich. The Schwartz reagents Cp2ZrHCl and Cp2ZrH2 were prepared
as described previously in Refs. [15,7a].
A 10 ml flask equipped with a magnetic stirrer and filled with
argon was loaded with 1 mmol of L2ZrH2, 1.0 ml of toluene (ben-
zene), 2–60 mmol of AlR3 and 1–50 mmol of hexene-1. The reac-
tion mixture was stirred for 24 h at 22 °C. Then the mixture was
decomposed with 10% HCl or DCl at 0 °C. The products were ex-
tracted with benzene; further, the organic layer was dried over
Na2SO4 and analyzed by GC–MS.
The NMR spectra 1H, 13C and 27Al were recorded on spectrome-
ter Bruker AVANCE-400 (400.13 MHz (1H), 100.62 MHz (13C) and
104.23 MHz (27Al)). d6-Benzene, d8-toluene and d-chloroform were
used as solvents and internal standards. The samples were pre-
pared in standard tubes of 5 mm diameter. Chemical shifts are
internally referenced to the TMS signal. 27Al chemical shifts are ref-
erenced to the Al(H2O)6Cl3 signal. One- and two-dimensional NMR
spectra (COSY HH, HSQC, HMBC) were measured with standard
pulse sequences.
4.4. Reaction of hexene-1 with AlR3 in the presence of Cp2ZrHCl
A 10 ml flask equipped with a magnetic stirrer and filled with
argon was loaded with 1 mmol of Cp2ZrHCl, 1.0 ml of toluene (ben-
zene), 2–60 mmol AlR3 and 2–50 mmol of hexene-1. The mixture
was stirred for 24 h at 22 °C. The mixture was decomposed with
10% HCl or DCl at 0 °C. The products were extracted with benzene;
further, the organic layer was dried over Na2SO4 and analyzed by
GC–MS.
The yields of hydro-, carbo- and cycloalumination products
were determined from the yields of hydrolysis products, which
were calculated relative to amount of the initial olefin. The hydro-
lysis products of reaction mixture were analyzed on chromato-
graph Carlo Erba (He, column 50,000 ꢃ 0.32 mm, fixed phase
‘‘Ultra-1”, flame-ionizating detector). Mass spectra were obtained
on spectrometer MD 800, TRIO 1000 VG Masslab (Great Britain).
4.5. NMR study of the interaction of [Cp2ZrH2]2 with AlEt3
4.2. Reaction of hexene-1 with AlR3 (R = Me, Et) in the presence of
L2ZrCl2 (L = Cp, Cp0, Cp*, Ind, Flu)
An NMR tube filled with argon was loaded with 0.6 mmol
(134 mg) of Cp2ZrH2 and 0.4 ml of d8-toluene. AlEt3 (0.6 mmol,
0.11 ml) was added dropwise until the precipitate was dissolved.
Finally the formation of complex 16 was observed [7a]. The mix-
A 10 ml flask equipped with a magnetic stirrer and filled with
argon was loaded with 1–2 mmol of L2ZrCl2, 1.0 ml of methylene