5754 Organometallics, Vol. 28, No. 19, 2009
Ren et al.
Chart 1. Bonding Interactions between Zr and o-C2B10H10 or
Benzyne
crystals after this solution stood at room temperature for 2 days
1
(431 mg, 73%). H NMR (benzene-d6): δ 3.48 (m, 8H, THF),
2.02 (s, 15H, CH3), 1.54 (m, 8H, THF). 13C{1H} NMR
(benzene-d6): δ 125.8 (C5(CH3)5), 95.8 (cage carbon), 68.4,
25.4 (THF), 12.2 (C5(CH3)5). 11B NMR (benzene-d6): δ -1.5
(d, J=156 Hz, 2B), -3.6 (d, J=165 Hz, 2B), -9.1 (d, J=140 Hz,
4B), -14.8 (d, J=150 Hz, 2B). IR (KBr, cm-1): ν 2565 (BH).
Anal. Calcd for C20H41B10Cl2LiO2Zr (1): C, 40.67; H, 7.00.
Found: C, 40.73; H, 6.84.
Preparation of Cp*(η3-C2B10Me8H2)Zr(μ-Cl)2Li(OEt2)2 (2).
To a stirred solution of o-C2B10Me8H4 (256 mg, 1.00 mmol) in
diethyl ether (30 mL) at 0 °C was slowly added nBuLi (1.3 mL,
2.08 mmol, 1.6 M in hexane), and the mixture was stirred at
room temperature overnight. The resulting Li2C2B10Me8H2
solution was then cooled to -78 °C, to which was added
Cp*ZrCl3 (333 mg, 1.00 mmol). The reaction mixture was then
stirred for 4 h at room temperature, giving a yellow suspension.
After removal of the precipitate by filtration, the clear yellow
solution was concentrated to about 5 mL. Complex 2 was
isolated as pale yellow crystals after this solution stood at room
temperature overnight (460 mg, 65%). 1H NMR (benzene-d6):
δ 3.25 (q, J=6.9 Hz, 8H, CH2), 2.07 (s, 15H, C5(CH3)5), 0.97
(t, J=6.9 Hz, 12H, CH2CH3), 0.56 (br, 18H, BCH3), 0.36 (br,
6H, BCH3). 13C{1H} NMR (benzene-d6): δ 126.5 (C5(CH3)5),
95.4 (cage carbon), 65.8, 14.8 (OEt2), 12.7 (C5(CH3)5), -2.2 (br,
BCH3). 11B NMR (benzene-d6): δ 8.9 (s, 2B), 4.5 (s, 2B), -2.4
(s, 4B), -13.7 (d, J=150 Hz, 2B). IR (KBr, cm-1): ν 2613, 2453
(BH). Anal. Calcd for C26H56B10Cl2LiO1.5Zr (2 - 0.5OEt2):
C, 46.62; H, 8.43. Found: C, 46.85; H, 8.21.
ligands have significant effects on the types of resultant
complexes (neutral versus ionic complexes). The bonding
interactions between Zr and o-C2B10H10 are best described as
a resonance hybrid of both Zr-C σ and Zr-C π bonding
forms. These complexes should have a rich reaction chem-
istry, in view of the chemical properties of Cp2Zr(μ-Cl)
(μ-C2B10H10)Li(OEt2)29,10 and (Ph3P)2Ni(η2-C2B10H10).6-8
Experimental Section
General Procedures. All reactions were performed under an
atmosphere of dry nitrogen with the rigid exclusion of air and
moisture using standard Schlenk or cannula techniques or in a
glovebox. All organic solvents were freshly distilled from so-
1
Preparation of Cp*[η2-CyNC(Me)NCy]Zr(η2-C2B10H10) (3).
To a stirred solution of o-C2B10H12 (144 mg, 1.00 mmol) in
diethyl ether (30 mL) at 0 °C was slowly added nBuLi (1.3 mL,
2.08 mmol, 1.6 M in hexane), and the mixture was stirred at
room temperature for 1 h. The resulting Li2C2B10H10 suspen-
sion was then cooled to -30 °C, to which was added Cp*Zr-
[CyNC(Me)NCy]Cl2 (495 mg, 1.00 mmol). The reaction mixture
was then stirred for 1 h at room temperature, giving a pale
orange suspension. After removal of the precipitate by filtra-
tion, the clear yellow solution was concentrated to about 10 mL.
Complex 3 was isolated as orange crystals after this solution
stood at room temperature overnight (295 mg, 51%). 1H NMR
(benzene-d6): δ 2.97 (m, 2H, Cy), 2.14 (m, 2H, Cy), 1.79 (s, 15H,
C5(CH3)5), 1.61 (m, 6H, Cy), 1.46 (s, 3H, CH3), 1.22 (m, 12H,
Cy). 13C{1H} NMR (benzene-d6): δ 166.2 (NCN), 124.9
(C5(CH3)5), 98.0 (cage C), 57.8 (NCH), 35.3, 34.5, 26.0, 25.7,
13.1, 12.3 (CH2 and CH3). 11B NMR (benzene-d6): δ -0.8 (d, J=
162 Hz, 2B), -2.3 (d, J=170 Hz, 2B), -7.9 (d, J=130 Hz, 4B),
-15.0 (d, J=140 Hz, 2B). IR (KBr, cm-1): ν 2582 (BH). Anal.
Calcd for C26H50B10N2Zr (3): C, 52.93; H, 8.54; N, 4.75. Found:
C, 52.86; H, 8.66; N, 4.59.
dium benzophenone ketyl immediately prior to use. H NMR
spectra were recorded on either a Bruker DPX 300 spectrometer
at 300 MHz or Bruker DPX 400 spectrometer at 400 MHz.
13C{1H} NMR spectra were recorded on either a Bruker DPX
300 spectrometer at 75 MHz or a Bruker DPX 400 spectrometer
at 100 MHz. 11B{1H} NMR spectra were recorded on either a
Bruker DPX 300 spectrometer at 96 MHz or a Varian Inova 400
spectrometer at 128 MHz. All chemical shifts are reported in
δ units with reference to the residual protons and carbons of the
deuterated solvents for proton and carbon chemical shifts and to
external BF3 OEt2 (0.00 ppm) for boron chemical shifts. Infra-
3
red spectra were obtained from KBr pellets prepared in the
glovebox on a Perkin-Elmer 1600 Fourier transform spectro-
meter. Elemental analyses were performed by the Shanghai
Institute of Organic Chemistry, CAS, People’s Republic of
China. Cp*ZrCl3,21 Cp*[η2-CyNC(Me)NCy]ZrCl2,22 [η2-CyN-
C(R)NCy]2ZrCl2 (R = Me, Ph),23 and o-C2B10Me8H4 were
24
prepared according to literature methods. All other chemicals
were purchased from either Aldrich or Acros Chemical Co. and
used as received unless otherwise specified.
Preparation of Cp*(η2-C2B10H10)Zr(μ-Cl)2Li(THF)2 (1). A
n
1.6 M solution of BuLi in hexane (1.3 mL, 2.08 mmol) was
Preparation of [η2-CyNC(CH3)NCy]2Zr(η2-C2B10H10) (4).
To a stirred solution of o-C2B10H12 (0.72 g, 5.00 mmol) in
diethyl ether (30 mL) at 0 °C was slowly added nBuLi (6.3 mL,
10.00 mmol, 1.6 M in hexane), and the mixture was stirred at
room temperature for 1 h. After removal of the solvent under
vacuum, the residue was suspended in toluene (30 mL), to which
was slowly added a toluene solution (20 mL) of [η2-CyNC-
(CH3)NCy]2ZrCl2 (2.90 g, 5.00 mmol) at 0 °C. The reaction
mixture was then stirred at room temperature for 24 h. After
filtration, the precipitate was washed with hot toluene (3ꢀ5 mL).
Removal of the solvent gave a crude product. Recrystallization
from diethyl ether/hexane (30 mL, 10/1 in v/v) at room tem-
perature afforded 4 as yellow crystals (3.08 g, 91%). 1H NMR
(benzene-d6): δ 3.00 (m, 4H, NCH), 1.71 (m, 28H, CH2), 1.52
(s, 6H, CH3), 1.17 (m, 12H, CH2). 13C{1H} NMR (benzene-d6):
δ 177.6 (NCN), 103.9 (cage C), 57.9 (NCH), 34.8, 26.0, 25.6, 12.3
(CH2 and CH3). 11B{1H} NMR (benzene-d6): δ -0.7 (4B), -7.1
(4B), -14.8 (2B). IR (KBr, cm-1): ν 2569 (BH). Anal. Calcd for
C30H60B10N4Zr (4): C, 53.29; H, 8.94; N, 8.29. Found: C, 53.65;
H, 9.18; N, 7.92.
slowly added to a stirred solution of o-C2B10H12 (144 mg, 1.00
mmol) in diethyl ether (30 mL) at 0 °C, and the mixture was
stirred at room temperature for 1 h. The resulting Li2C2B10H10
suspension was then cooled to -30 °C, to which was added
Cp*ZrCl3 (333 mg, 1.00 mmol). The reaction mixture was then
stirred for 4 h at room temperature, giving a yellow suspension.
After removal of the precipitate by filtration, several drops of
THF were added and the resulting clear yellow solution was
concentrated to about 10 mL. Complex 1 was isolated as yellow
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G. P. A.; Brown, S. J. Organometallics 1998, 17, 446. (b) Sun, J.-F.; Chen,
S.-J.; Duan, Y.; Li, Y.-Z.; Chen, X.-T.; Xue, Z.-L. Organometallics 2009, 28,
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