Synthesis of carbaalane halogen derivatives

Article abstract of DOI:10.1021/ic035460i

The carbaalane halogen derivatives [(AlX)₆(AlNMe ₃)₂(CCH₂CH₂SiMe₃) ₆] (X = F (9), Cl (7), Br (10), I (11)) were prepared in toluene from [(AlH)₆(AINMe₃)₂(CCH₂CH ₂SiMe₃)₆] (6) and BF₃· OEt₂, BX3 (X = Br, I), Me₃SnF, and Me₃SiX (X = Cl, Br, I), respectively. A partially halogenated product [(AlH) ₂(AlX)₄(AlNMe₃)₂(CCH ₂CH₂SiMe₃)₆] (12) (X = Cl (～40%), Br (～60%)) was obtained from 5 and impure BBr₃. [(AlH)₆(AlNMe₃)₂(CCH₂Ph) ₆] (5) was converted to [(AlX)₆(AINMe₃) ₂(CCH₂Ph)₆] (X = F (13), Cl (14), Br (15), I (16)) using BF₃·OEt₂ and Me₃SiX (X = Cl, Br, I), respectively. The X-ray single-crystal structures of 11·C ₆H₆, 12·3C₇H₈, 13·6C₇H₈, and 15·4C₇H ₈ were determined. Compounds 7 and 9-11 are soluble in benzene/toluene and could be well characterized by NMR spectroscopy and MS (EI) spectrometry. The results demonstrate the facile substitution of the hydridic hydrogen atoms in 5 and 6 by the halides with different reagents.

Full text of DOI:10.1021/ic035460i

Inorg. Chem. 2004, 43, 3625−3630
Synthesis of Carbaalane Halogen Derivatives
Andreas Stasch, Herbert W. Roesky,* Denis Vidovic, Jo1rg Magull, Hans-Georg Schmidt, and
Mathias Noltemeyer
Institut fu¨r Anorganische Chemie der Georg-August-UniVersita¨t Go¨ttingen,
Tammannstrasse 4, D-37077 Go¨ttingen, Germany
Received December 19, 2003
The carbaalane halogen derivatives [(AlX)6(AlNMe3)2(CCH CH SiMe3)6] (X ) F (9), Cl (7), Br (10), I (11)) were
2
2
prepared in toluene from [(AlH)6(AlNMe3)2(CCH CH SiMe3)6] (6) and BF ‚OEt2, BX (X ) Br, I), Me3SnF, and
2
2
3
3
Me3SiX (X ) Cl, Br, I), respectively. A partially halogenated product [(AlH)2(AlX)4(AlNMe3)2(CCH CH SiMe3)6] (12)
2
2
(X ) Cl (∼40%), Br (∼60%)) was obtained from 5 and impure BBr3. [(AlH)6(AlNMe3)2(CCH Ph)6] (5) was converted
2
to [(AlX)6(AlNMe3)2(CCH Ph)6] (X ) F (13), Cl (14), Br (15), I (16)) using BF ‚OEt2 and Me3SiX (X ) Cl, Br, I),
2
3
respectively. The X-ray single-crystal structures of 11‚C H , 12‚3C H , 13‚6C H , and 15‚4C H were determined.
6
6
7
8
7
8
7 8
Compounds 7 and 9−11 are soluble in benzene/toluene and could be well characterized by NMR spectroscopy
and MS (EI) spectrometry. The results demonstrate the facile substitution of the hydridic hydrogen atoms in 5 and
6 by the halides with different reagents.
Introduction
(CCH2CH2SiMe2Cl)6] (8), demonstrating the stepwise func-
tionalization and the stability of the cluster.2e Very recently,
we obtained the first carbaalanate from the reaction of tBu-
CtCLi with a mixture of ClAlH2‚NMe3 and AlH3‚NMe3.4
Compounds containing aluminum hydrogen bonds can be
substituted by halides using various reagents.2e,3,5 Recently,
we have converted polyhedral compounds from hydro-
alumination reactions to halogen derivatives.6 In this paper
we report on the synthesis and characterization of new
halogen-substituted carbaalanes, which are key derivatives
of carbaalane chemistry.
Since the first structural characterization of the carbaalane
[(AlMe)8(CCH2Ph)5H] (1) in 1999 by Uhl and Breher,1
numerous carbaalanes have been prepared.2 Three halogen-
substituted carbaalanes [(AlEt)7(CdCPh)2(CCH2Ph)3F] (2),
having a µ3-bridged fluorine atom, [(AlMe)8(CCH2Ph)5F] (3),
and [(AlMe)7(AlCl)(CCH2Ph)5H] (4) with a terminal chlorine
atom and unreacted hydride were prepared by treatment of
the parent carbaalane (e.g. 1 for the preparation of 3 and 4)
with HBF4 and HCl, respectively. The crystal structures of
2 and 4 were determined.3 We synthesized the carbaalane
[(AlH)6(AlNMe3)2(CCH2R)6] (R ) Ph (5), CH2SiMe3 (6))
in a facile reaction from the corresponding terminal alkyne
and 3 equiv of the alane trimethylamine adduct in boiling
toluene.2e Using compound 6 and BCl3 under varying
conditions, we obtained the chlorinated species [(AlCl)6-
(AlNMe3)2(CCH2CH2SiMe3)6] (7) and [(AlCl)6(AlNMe3)2-
Results and Discussion
Preparation and Spectroscopic Characterization. For
hydride metathesis, the toluene-soluble carbaalane [(AlH)6-
(4) Stasch, A.; Roesky, H. W.; Schleyer, P. v. R.; Magull, J. Angew. Chem.
2003, 115, 5665; Angew. Chem., Int. Ed. 2003, 42, 5507.
(5) (a) No¨th, H.; Wolfgardt, P. Z. Naturforsch. 1976, 31B, 697. (b)
Wehmschulte, R. J.; Power, P. P. Inorg. Chem. 1996, 35, 3262. (c)
Avent, A. G.; Chen, W.-Y.; Eaborn, C.; Gorrell, I. B.; Hitchcock, P.
B.; Smith, J. D. Organometallics 1996, 15, 4343. (d) Al-Juaid, S. S.;
Eaborn, C.; Gorrell, I. B.; Hawkes, S. A.; Hitchcock, P. B.; Smith, J.
D. J. Chem. Soc., Dalton Trans. 1998, 2411. (e) Wehmschulte, R. J.;
Power, P. P. Polyhedron 2000, 19, 1649. (f) Zheng, W.; Hohmeister,
H.; Mo¨sch-Zanetti, N. C.; Roesky, H. W.; Noltemeyer, M.; Schmidt,
H.-G. Inorg. Chem. 2001, 40, 2363. (g) Zhu, H.; Chai, J.; Roesky, H.
W.; Noltemeyer, M.; Schmidt, H.-G.; Vidovic, D.; Magull, J. Eur. J.
Inorg. Chem. 2003, 3113.
(6) (a) Reddy, N. D.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G.
Inorg. Chem. 2002, 41, 2374. (b) Reddy, N. D.; Kumar, S. S.; Roesky,
H. W.; Vidovic, D.; Magull, J.; Noltemeyer, M.; Schmidt, H.-G. Eur.
J. Inorg. Chem. 2003, 442. (c) Peng, Y.; Rong, J.; Vidovic, D.; Roesky,
H. W.; Labahn, T.; Magull, J.; Noltemeyer, M.; Schmidt, H.-G. J.
Fluorine Chem. 2004, in press.
* Author to whom correspondence should be addressed. E-mail: hroesky@
gwdg.de.
(1) Uhl, W.; Breher, F. Angew. Chem. 1999, 111, 1578; Angew. Chem.,
Int. Ed. 1999, 38, 1477.
(2) (a) Uhl, W.; Breher, F. Eur. J. Inorg. Chem. 2000, 1. (b) Uhl, W.;
Breher, F.; Lu¨tzen, A.; Saak, W. Angew. Chem. 2000, 112, 414; Angew.
Chem., Int. Ed. 2000, 39, 406. (c) Uhl, W.; Breher, F.; Grunenberg,
J.; Lu¨tzen, A.; Saak, W. Organometallics 2000, 19, 4536. (d) Uhl,
W.; Breher, F.; Mbonimana, A.; Gauss, J.; Haase, D.; Lu¨tzen, A.;
Saak, W. Eur. J. Inorg. Chem. 2001, 3059. (e) Stasch, A.; Ferbinteanu,
M.; Prust, J.; Zheng, W.; Cimpoesu, F.; Roesky, H. W.; Magull, J.;
Schmidt, H.-G.; Noltemeyer, M. J. Am. Chem. Soc. 2002, 124, 5441.
(3) Uhl, W.; Breher, F.; Neumu¨ller, B.; Lu¨tzen, A.; Saak, W.; Grunenberg,
J. Organometallics 2001, 20, 5478.
10.1021/ic035460i CCC: $27.50 © 2004 American Chemical Society
Published on Web 05/15/2004
Inorganic Chemistry, Vol. 43, No. 12, 2004 3625

Stasch et al.
Scheme 1
the starting material 6 in the correct isotope pattern.
Incomplete halogenation, especially for the fluorine and
chlorine derivatives, can be detected by EI mass spectra of
the crude products showing the intermediates as molecular
ion peaks. The crude products of 9 and 10 exhibit small peaks
for the pentasubstituted halogen derivatives. The NMR data
for compounds 9-11 show results similar to those of 7. The
NMR resonances are in agreement with a symmetric
structure, and the CH2CH2 groups show the typical multipli-
city (2 × ddd) in the 1H NMR spectrum. In general, the 1H
NMR resonances are shifted downfield within the series F,
Cl, Br, and I. The 13C NMR spectra exhibit the resonances
for the cluster carbon atoms (δ 33.1 (9), δ 32.0 (10), and δ
29.4 (11)), which are close to those of the chlorine
compounds 7 (δ 32.1) and 8 (δ 30.2) and are shifted
downfield when compared to 6 (δ 16.8). The 27Al NMR
resonances of 10 (δ 143.9) and 11 (δ 144.9) are in the region
of the previously characterized compounds (6, δ 142.3; 7, δ
140.9; 8, δ 141.4). However, the value for the fluorine
derivative 9 is strongly shifted upfield to δ 122.3. The latter
compound exhibits a broad resonance in the 19F NMR
spectrum at δ -181.5 with a shoulder at δ -178, which
could result from a small amount of the pentafluorinated
species. This resonance is in the high-field region for terminal
Al-F bonds, and only the resonance of [Me4N][AlF4] (δ
-194.9) is shifted more upfield than 9 for tetracoordinated
aluminum compounds.7 Fluorinated cage compounds having
AlN or AlCH2N cores from hydroalumination reactions with
terminal Al-F bonds show 19F NMR resonances around δ
-163 and -155.7.6c The fluorinated carbaalane 3 exhibits a
resonance at δ -121.4 in the 19F NMR spectrum, while the
corresponding resonance for 2 was not observed.
Scheme 2
Scheme 3
(AlNMe3)2(CCH2CH2SiMe3)6] (6) was treated with at least
2 equiv of BF3‚OEt2, BBr3, and BI3, respectively, in toluene
at low temperature to yield the halogen derivative [(AlX)6-
(AlNMe3)2(CCH2CH2SiMe3)6] (X ) F (9), Br (10), I (11))
in good yield (Scheme 1).The reaction of 6 with the boron
halides proceeds at low temperature and is best performed
at -78 °C under slow warming to room temperature. When
the reaction mixture is conducted at ice bath temperature,
only partially substituted halogen derivatives are formed or
an excess of the boron halides is required. In the case of
preparing the fluorine derivative 9, 6 equiv of BF3‚OEt2 was
used for obtaining optimal results. In another attempt we
found that 2 equiv of BF3‚OEt2 was sufficient for this reaction
and that all the fluorine atoms can be transfered to aluminum
but this can increase the amount of partially fluorinated
byproducts. A large excess of boron halides (especially BX3,
X ) Cl, Br, I) and heating the reaction mixture must be
avoided, otherwise compound 8 (when BCl3 is used) and
oily byproducts are formed. Compound 9 can be alternatively
synthesized from 6 using Me3SnF in toluene over a period
of 3 d at room temperature or by stirring at room temperature
and slowly warming the mixture to its boiling point until all
the Me3SnF has reacted (Scheme 2).
For the preparation of compounds 7, 10, and 11 trimeth-
ylsilyl halides can be used alternatively (Scheme 3). For these
reactions, elevated reaction temperatures are necessary. In
general, the reagents are combined at room temperature and
the mixture is heated under reflux for up to 2 h. Compound
11 could not be prepared by slow addition of elemental iodine
in toluene at 0 °C/room temperature. The reaction mixture
is consuming far more than 6 equiv of I2. We assume that
intermediate HI is decomposing the cluster, which is sensitive
to protic reagents.
Recrystallization of the crude product (7, 9-11) afforded
some yellow crystals of 9, which were not suitable for X-ray
single crystal structure analysis. The previously published
compound 7 could be recrystallized from toluene or diethyl
ether at different temperatures forming large yellow blocks,
but the crystals become opaque either when the temperature
is changed or when the crystals are taken out of the solution.
Some yellow-green rods of 11‚C6H6 were obtained from a
concentrated benzene solution. However, the crude products
1
of 7 and 9-11 were of good purity as shown by their H
and 13C NMR spectra.
In one experiment, compound 6 was treated with an impure
sample of BBr3 at -78 °C under warming to room temper-
ature. The expected molecular ion peak M+ (m/z ) 1492)
of compound 10 is present in the EI mass spectrum of the
crude product. However, recrystallization from toluene (50
°C/-25 °C, 4 months) afforded a small number of pale
yellow single crystals of [(AlH)2(AlX)4(AlNMe3)2(CCH2CH2-
SiMe3)6]‚3toluene (12‚3C7H8) with a halogen ratio of X )
Cl (∼40%) and Br (∼60%) which was characterized by its
X-ray single-crystal structure.
In contrast to compound 6, compound 5 is much less
soluble, and therefore, derivatization was difficult. Compound
The compounds 9-11 provide molecular ion peaks in the
EI mass spectra like the chlorine derivatives 7 and 8 and
(7) Pinkas, J.; Roesky, H. W. J. Fluorine Chem. 2003, 122, 125 and
references therein.
3626 Inorganic Chemistry, Vol. 43, No. 12, 2004

Carbaalane Halogen DeriWatiWes
Table 1. Crystallographic Data
param
11‚C6H6
12‚3C7H8
13‚6C7H8
15‚4C7H8
diffractometer
empirical formula
fw
I
II
I
I
C54H108Al8I6N2Si6
1913.20
C63H122Al8Br2.38Cl1.62N2Si6 C96H108Al8F6N2
1539.62
C82H92Al8Br6N2
1800.88
1619.68
T/K
133(2)
200(2)
133(2)
140(2)
cryst system
space group
unit cell dimens/Å and deg
rhombohedral
R3h
a ) 15.4323(10)
b ) 15.4323(10)
c ) 29.624(2)
R ) 90
â ) 90
γ ) 120
6109.8(7)
3
1.575
2.494
2856
0.40 × 0.20 × 0.20
1.67-25.35
-18 e h e 18,
-18 e k e 18,
-35 e l e 35
22 379/2479
0.0427
monoclinic
P21/n
a ) 15.732(3)
b ) 12.9036(17)
c ) 21.286(7)
R ) 90
â ) 90.59(2)
γ ) 90
4320.9(16)
2
1.183
1.362
monoclinic
P21/n
a ) 11.642(2)
b ) 31.900(6)
c ) 11.986(2)
R ) 90
â ) 102.75(3)
γ ) 90
4341.5(15)
2
1.239
0.154
monoclinic
P21/n
a ) 11.822(2)
b ) 15.823(3)
c ) 21.216(4)
R ) 90
â ) 95.55(3)
γ ) 90
3949.9(14)
2
1.514
3.183
V/Å3
Z
F/Mg‚m-3
µ/mm-1
F(000)
1626
1712
1823
cryst size/mm3
θ/deg
0.50 × 0.40 × 0.40
3.51-22.44
-16 e h e 9,
0 e k e 13,
0 e l e 22
4701/4701
0.0000
0.40 × 0.30 × 0.30
1.86-24.78
-13 e h e 11,
-37 e k e 36,
-14 e l e 14
27 552/7294
0.1153
0.20 × 0.20 × 0.20
1.61-24.96
-13 e h e 13,
-18 e k e 18,
-24 e l e 24
57 236/6830
0.1936
index ranges
reflcns collcd/unique
Rint
completeness to θ/%
data/restraints/params
goodness-of-fit on F2
final R indices [I > 2σ(I)]
R indices (all data)
99.6
2479/0/128
1.089
83.9
4701/595/416
1.039
97.7
7294/0/575
0.956
98.6
6830/409/415
1.029
R1 ) 0.0153, wR2 ) 0.0374 R1 ) 0.0633, wR2 ) 0.1198 R1 ) 0.0587, wR2 ) 0.0841 R1 ) 0.0768, wR2 ) 0.1826
R1 ) 0.0168, wR2 ) 0.0380 R1 ) 0.1259, wR2 ) 0.1467 R1 ) 0.1282, wR2 ) 0.0946 R1 ) 0.1130, wR2 ) 0.2019
largest diff peak and hole/e‚Å-3 0.402, -0.421
0.429, -0.446
0.328, -0.252
1.025, -1.797
Scheme 4
were detected. The crystalline compounds are not soluble
in THF or acetonitrile, and moreover, they are not reacting
with the nitrile in the way the hydrided derivative does.
Corresponding to the parent compound 5, no molecular ion
was detected in the EI mass spectra of 13-16. For the
derivatives of 5, neither NMR and IR spectroscopy nor mass
spectrometry provides proof of their composition or struc-
tures. Obviously, only functionalization of the hydride takes
place as proven by the structural analysis of 13 and 15 and
the corresponding reactions using 6 as a starting material.
Scheme 5
Crystal Structures. The X-ray single-crystal structures
of 11‚C6H6, 12‚3C7H8, 13‚6C7H8, and 15‚4C7H8 were
determined, and the crystallographic data are summarized
in Table 1. ORTEP plots (50% thermal ellipsoids) of these
compounds are shown in the Figures 1-4 in different views
of the cluster core, and selected bond lengths and angles are
given in the Tables 2-5. Compounds 12‚3C7H8, 13‚6C7H8,
and 15‚4C7H8 crystallize in the monoclinic space group P21/
n, and their asymmetric units show half of the molecule along
with half of the solvent molecules, respectively. In contrast
to that, 11‚C6H6 crystallizes in the rhombohedral space group
R3h with one sixth of the molecule in the asymmetric unit
demonstrating the symmetry of the cluster. All compounds
have in common that the central cluster consists of a cube
of eight aluminum atoms where each face is occupied by a
carbon atom attached to an organic group. Two aluminum
atoms on opposite sides of the cluster are coordinating to a
NMe3 unit. The remaining aluminum atoms are bonded to
halogen atoms or to a mixture of halides and hydrides in
12‚3C7H8. In all compounds, the Al-C bond lengths (from
2.028(4) to 2.099(4) Å in 13‚6C7H8) and the Al-Al distances
(from 2.566(3) Å in 12‚3C7H8 to 2.632(3) Å in 15‚4C7H8)
5 was treated with an excess of BF3‚OEt2 in boiling toluene
(Scheme 4). Filtering the hot reaction mixture gave an impure
greenish crude product, and storing the solution at room
temperature resulted in shiny green-yellow rhombuses mainly
containing [(AlF)6(AlNMe3)2(CCH2Ph)6] (13). The unit cell
could not be refined due to disordering. Filtering off these
crystals and storing the resulting solution at -25 °C gave
another crop of crystals (plates) with the same color of
composition 13‚6C7H8.
Compound 5 reacts with an excess of Me3SiX (X ) Cl,
Br, I) in boiling toluene giving a crude product and a
crystalline material of [(AlX)6(AlNMe3)2(CCH2Ph)6] (X )
Cl (14), Br (15), I (16)) that precipitated from the reaction
mixture upon standing for a few days at room temperature
or lower temperatures (Scheme 5). The crystal structure of
15‚4C7H8 was determined. In these reactions, the color is
changing after a few minutes of refluxing. In general, the
products have an intense yellow or yellow-green color. Due
to the poor solubility of 13-16, no satisfying NMR spectra
could be recorded. Only traces of the reagents or impurities
Inorganic Chemistry, Vol. 43, No. 12, 2004 3627

Stasch et al.
Figure 1. ORTEP drawing of the crystal structure of 11‚C6H6. Hydrogen
atoms and solvent molecules are not shown.
Figure 3. ORTEP drawing of the crystal structure of 13‚6C7H8. Hydrogen
atoms and solvent molecules are not shown.
Figure 2. ORTEP drawing of the crystal structure of 12‚3C7H8. Only
hydrogen atoms on aluminum are depicted. Solvent molecules are not
shown.
Figure 4. ORTEP drawing of the crystal structure of 15‚4C7H8. Hydrogen
are comparable to those reported in the literature,2e with the
exception of one long Al-C bond length (2.131(7) Å) in
12‚3C7H8. The Al-F bond lengths in 13‚6C7H8 range from
1.667(2) to 1.669(3) Å, the Al-Br bond lengths in
15‚4C7H8 range from 2.282(2) to 2.302(2) Å, and the Al-I
bond length is 2.5297(5) Å. In 12‚3C7H8, two aluminum
atoms on opposite sides of the cluster are each bearing a
datively bonded NMe3 unit (Al2 and Al2A) and a hydride
(Al4 and Al4A), respectively. The other four Al atoms are
carrying halogen atoms and were refined with Br (∼64%)
and Cl (∼36%) on Al1 and Al1A, as well as Br (∼55%)
and Cl (∼45%) on Al3 and Al3A. The Al-Br bond lengths
are around 2.30 Å, and the Al-Cl bond lengths are not exact
enough for the discussion.
atoms and solvent molecules are not shown.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 11‚C6H6
Al(1)-I(1)
2.5297(5)
2.0729(18)
2.005(3)
Al(1)-C(1)
Al(1)-C(1)#2
Al(2)-C(1)
Al(1)-Al(2)
2.0860(17)
2.0839(17)
2.0639(17)
2.5844(7)
Al(1)-C(1)#1
Al(2)-N(1)
Al(1)-Al(1)#1
2.6160(7)
C(1)-Al(1)-I(1)
I(1)-Al(1)-Al(2)
C(1)-Al(1)-C(1)#1
110.60(5)
113.68(2)
100.36(8)
C(1)#1-Al(1)-I(1)
I(1)-Al(1)-Al(1)#1
C(1)-Al(2)-C(1)#4
130.01(5)
130.78(2)
102.24(6)
Al(2)-Al(1)-Al(1)#1 89.149(16) Al(1)#1-Al(1)-Al(4)#3 90.14(3)
Al(1)#2-Al(2)-Al(1) 91.55(3)
strongly distorted tetrahedral arrangement and the Al-X
units are directing toward the NMe3 groups. For example,
the smallest I-Al-C angle in 11‚C6H6 is 110.60(5)° and
the largest is 130.01(5)° whereas the I-Al-Al angles range
from 113.68(2) to 130.78(2)° and the F-Al-C angles in
13‚6C7H8 are ranging from 110.98(15) to 129.51(12)° with
the F-Al-Al angles ranging from 115.42(9) to 131.98(11)°.
There are always two small and one large X-Al-C angles
(X ) halogen) around each Al(X) atom, while two large
and one small X-Al-Al angles are found around Al(X) in
every compound. The result is that the Al(X) atoms are in a
3628 Inorganic Chemistry, Vol. 43, No. 12, 2004

Carbaalane Halogen DeriWatiWes
Table 3. Selected Bond Lengths (Å) and Angles (deg) for 12‚3C7H8
in a bridging position. These compounds are key substances
for the fast growing field of carbaalanes.
Br(1)-Al(1)
Br(2)-Al(3)
Al(1)-C(1)
C(1)-Al(2)
Al(2)-C(4)#1
Al(3)-C(4)
Al(4)-C(1)#1
Al(1)-Al(2)#1
Al(1)-Al(4)#1
Al(2)-Al(4)#1
Al(2)-N(2)
2.30(2)
Cl(1)-Al(1)
Cl(2)-Al(3)
Al(1)-C(4)
Al(2)-C(3)
Al(3)-C(3)
C(3)-Al(4)
Al(4)-C(4)
Al(1)-Al(3)
Al(2)-Al(3)
Al(3)-Al(4)
2.24(9)
2.16(3)
2.309(11)
2.071(8)
2.041(7)
2.033(8)
2.052(8)
2.088(8)
2.581(3)
2.609(3)
2.570(3)
1.973(7)
2.043(7)
2.028(7)
2.071(7)
2.082(8)
2.131(7)
2.601(4)
2.566(3)
2.595(3)
Experimental Section
All manipulations were performed under a dry and oxygen-free
inert-gas atmosphere (N2 or Ar) using Schlenk line and glovebox
techniques. IR spectra were recorded in Nujol between KBr plates,
and melting points are not corrected. X-ray single-crystal structural
analyses were performed on the diffractometers Stoe-IPDS II
(diffractometer I) or Stoe-Siemens four circle (diffractometer II)
with Mo KR radiation (λ ) 0.710 73 Å). The structures were solved
by direct methods and refined by full-matrix least squares on F2
using the SHELX-97, G. M. Sheldrick, programs for crystal
structure refinement, Universita¨t Go¨ttingen, 1997.
[(AlF)6(AlNMe3)2(CCH2CH2SiMe3)6] (9). Method a. BF3‚OEt2
(150 µL, 165 mg, 1.17 mmol, 6.6 equiv) was added dropwise to a
-78 °C cooled solution of [(AlH)6(AlNMe3)2(CCH2CH2SiMe3)6]
(6) (0.18 g, 0.177 mmol, 1.0 equiv) in toluene (15 mL), and the
solution turned yellow. The mixture was slowly warmed to room
temperature and stirred for 30 min, and all volatiles were removed
in vacuo. The product was dried in vacuo at 50 °C giving a yellow
solid. Yield: 0.19 g (0.168 mmol, 95%). A sample could be
recrystallized from toluene.
Method b. Toluene (15 mL) was added to a mixture of [(AlH)6-
(AlNMe3)2(CCH2CH2SiMe3)6] (6) (0.12 g, 0.106 mmol, 1.0 equiv)
and finely powdered Me3SnF (0.16 g, 0.87 mmol, 8.2 equiv). The
suspension was roughly stirred 3 d at room temperature. The
mixture turned yellow after several hours. The solution was filtered,
all volatiles were removed in vacuo, and the residue was dried in
vacuo at 40 °C. Yield: 0.11 g (97 µmol, 91%). Mp: 270-280 °C,
color changed to orange (until 400 °C no complete dec). 1H NMR
(200 MHz, C6D6): δ ) 0.05 (s, 54 H, Si(CH3)3), 1.56 (ddd, J )
9.1, 4.3, 4.3 Hz, 12 H; Me3SiCH2), 2.18 (s, 18 H, N(CH3)3), 2.31
(ddd, J ) 9.1, 4.3, 4.3 Hz, 12 H; CCH2). 13C NMR (126 MHz,
C6D6): δ ) -1.65 (Si(CH3)3), 23.5 (Me3SiCH2), 28.0 (CH2C), 33.1
(broad, cluster-C), 47.4 (N(CH3)3). 19F NMR (126 MHz, C6D6): δ
) -181.5 (s, broad, shoulder at ca -178). 27Al NMR (65.2 MHz,
C6D6): δ ) 122.3 (s, W1/2 ) 750 Hz). 29Si NMR (99.4 MHz,
C6D6): δ ) -0.65. MS (EI) [m/z (%)]: 1226.2 (8, M+). IR: ν˜ )
1412, 1319, 1259, 1247, 1183, 1103, 1020, 976, 956, 917, 864,
835, 807, 766, 690, 657, 608, 493, 370 cm-1. Anal. Calcd for
C42H96Al8F6N2Si6: C, 44.74; H, 8.58; N, 2.48. Found: C, 45.32;
H, 8.82; N, 2.33.
C(4)-Al(1)-C(1)
C(4)-Al(1)-Al(2)#1
C(1)-Al(1)-Al(2)#1
99.6(3)
50.5(2)
114.9(2)
C(1)-Al(1)-C(3)#1
Al(1)-C(4)-Al(3)
Al(1)-C(4)-Al(4)
100.6(3)
78.9(3)
126.1(3)
90.18(10)
91.44(11)
Al(2)#1-Al(4)-Al(1)#1 89.38(10) Al(3)-Al(4)-Al(1)#1
Al(2)#1-Al(4)-Al(3)
Al(2)#1-Al(1)-Al(3)
Al(3)-Al(1)-Al(4)#1
Al(3)-Al(2)-Al(1)#1
Al(2)-Al(3)-Al(4)
Al(4)-Al(3)-Al(1)
88.21(10) Al(4)-Al(3)-Al(1)
87.86(10) Al(2)#1-Al(1)-Al(4)#1 88.85(10)
89.66(10) Al(3)-Al(2)-Al(4)#1
91.31(11)
91.47(10) Al(4)#1-Al(2)-Al(1)#1 92.47(11)
89.49(10) Al(2)-Al(3)-Al(1)
89.65(10)
90.18(10)
91.44(11) Al(3)-Al(4)-Al(1)#1
Table 4. Selected Bond Lengths (Å) and Angles (deg) for 13‚6C7H8
Al(2)-F(2)
Al(4)-F(1)
Al(1)-C(1)
Al(1)-C(17)
Al(2)-C(9)
Al(3)-C(1)#1
Al(3)-C(17)
Al(4)-C(9)#1
Al(1)-Al(2)
Al(1)-Al(4)
Al(2)-Al(4)#1
1.668(2)
1.669(3)
2.052(4)
2.049(4)
2.075(4)
2.070(4)
2.085(4)
2.063(4)
2.583(2)
2.579(2)
2.623(2)
Al(3)-F(3)
1.667(3)
1.982(3)
2.028(4)
2.079(4)
2.073(4)
2.099(4)
2.092(4)
2.084(4)
2.573(2)
2.629(2)
2.625(2)
N(1)-Al(1)
Al(1)-C(9)
Al(2)-C(1)
Al(2)-C(17)#1
Al(3)-C(9)
Al(4)-C(1)
Al(4)-C(17)
Al(1)-Al(3)
Al(2)-Al(3)#1
Al(3)-Al(4)#1
C(9)-Al(1)-C(1)
C(9)-Al(1)-C(17)
F(2)-Al(2)-C(9)
F(3)-Al(3)-C(1)#1
F(3)-Al(3)-C(9)
F(1)-Al(4)-C(9)#1
N(1)-Al(1)-C(1)
N(1)-Al(1)-C(17)
Al(3)-Al(1)-Al(4)
Al(1)-Al(2)-Al(4)#1
Al(1)-Al(2)-Al(3)#1
Al(1)-Al(3)-Al(4)#1
102.14(17) C(17)-Al(1)-C(1)
103.24(16) F(2)-Al(2)-C(1)
115.10(13) F(2)-Al(2)-C(17)#1
128.01(15) F(3)-Al(3)-C(17)
111.97(13) F(1)-Al(4)-C(1)
129.51(12) F(1)-Al(4)-C(17)
115.84(15) N(1)-Al(1)-C(9)
114.45(16) Al(3)-Al(1)-Al(2)
92.31(6) Al(4)-Al(1)-Al(2)
102.82(15)
111.12(15)
127.52(16)
113.84(16)
110.98(15)
112.12(16)
116.43(13)
92.93(6)
92.34(5)
88.03(6) Al(4)#1-Al(2)-Al(3)#1 90.04(5)
88.61(5) Al(1)-Al(3)-Al(2)#1
88.18(6) Al(1)-Al(4)-Al(2)#1
88.80(6)
88.83(6)
Al(4)#1-Al(3)-Al(2)#1 90.24(5) Al(2)#1-Al(4)-Al(3)#1 90.84(6)
Al(1)-Al(4)-Al(3)#1
Table 5. Selected Bond Lengths (Å) and Angles (deg) for 15‚4C7H8
88.79(5)
[(AlCl)6(AlNMe3)2(CCH2CH2SiMe3)6] (7). A solution of Me3-
SiCl (0.52 mL, 0.45 g, 4.12 mmol, 15 equiv) and [(AlH)6-
(AlNMe3)2(CCH2CH2SiMe3)6] (6) (0.28 g, 0.275 mmol, 1.0 equiv)
in toluene (20 mL) was stirred 1 h at room temperature and refluxed
for 2 h. All volatiles were removed in vacuo, and the product was
dried at 40 °C in vacuo. Yield: 0.34 g (0.275 mmol, 100%), Mp:
233 °C (dec with color change); 250 °C (rapid dec with gas
formation). Spectroscopic data: see ref 2e.
[(AlBr)6(AlNMe3)2(CCH2CH2SiMe3)6] (10). Method a. BBr3
(0.43 mL of a 1.0 M hexane solution, 0.43 mmol, 2.2 equiv) was
added dropwise to a -78 °C cooled solution of [(AlH)6-
(AlNMe3)2(CCH2CH2SiMe3)6] (6) (0.20 g, 0.196 mmol, 1.0 equiv)
in toluene (15 mL) and slowly warmed to room temperature. All
volatiles were removed in vacuo, and the product was dried at 40
°C in vacuo. Yield: 0.27 g (0.182 mmol, 95%).
Al(1)-Br(1)
Al(3)-Br(3)
Al(1)-C(1)
2.302(2)
2.286(2)
2.067(8)
2.060(8)
2.054(8)
2.607(3)
2.583(3)
Al(2)-Br(2)
N(1)-Al(4)
Al(1)-C(2)
Al(2)-C(2)
Al(4)#1-C(2)
Al(2)-Al(3)
Al(2)-Al(4)#1
2.282(2)
1.981(7)
2.064(8)
2.098(7)
2.041(8)
2.632(3)
2.574(3)
Al(1)-C(3)#1
Al(2)-C(3)
Al(1)-Al(2)#1
Al(1)-Al(4)#1
Br(1)-Al(1)-C(1)
132.2(2)
Br(1)-Al(1)-C(2)
110.5(2)
112.15(10)
131.92(12)
Br(1)-Al(1)-C(3)#1 109.9(2)
Br(1)-Al(1)-Al(4)#1
Br(1)-Al(1)-Al(2)#1 131.28(12) Br(1)-Al(1)-Al(3)
Al(1)#1-Al(2)-Al(3) 90.33(10) Al(2)#1-Al(4)-Al(1)#1 92.30(10)
Al(4)#1-Al(2)-Al(3) 88.46(10)
In summary, we have prepared the halogen derivatives
[(AlX)6(AlNMe3)2(CCH2R)6] (X ) F, Cl, Br, I; R ) Ph, CH2-
SiMe3) and one partially substituted species using various
reagents and compared their spectroscopic data and proper-
ties. It is surprising that in the fluorine-containing carbaalane
9 the fluorine atoms are arranged in a terminal rather than
Method b. A solution of Me3SiBr (0.34 mL, 0.40 g, 2.59 mmol,
12 eqiuv) and [(AlH)6(AlNMe3)2(CCH2CH2SiMe3)6] (6) (0.22 g,
0.216 mmol, 1.0 equiv) in toluene (15 mL) was stirred 10 min at
room temperature and slowly heated to its boiling point. The
Inorganic Chemistry, Vol. 43, No. 12, 2004 3629

Stasch et al.
mixture was refluxed for 1 h. All volatiles were removed in vacuo,
and the product was dried at 40 °C in vacuo. Yield: 0.30 g (0.203
mmol, 94%). Mp: 225 °C (dec with color change); 245 °C (further
dec with gas and foam formation). 1H NMR (200 MHz, C6D6): δ
) 0.10 (s, 54 H, Si(CH3)3), 1.58 (ddd, J ) 9.1, 4.3, 4.3 Hz, 12 H;
Me3SiCH2), 2.23 (s, 18 H, N(CH3)3), 2.39 (ddd, J ) 9.1, 4.3, 4.3
Hz, 12 H; CCH2). 13C NMR (126 MHz, C6D6): δ ) -1.52 (Si-
(CH3)3), 28.0 (Me3SiCH2), 28.6 (CH2C), 32.0 (broad, cluster-C),
48.7 (N(CH3)3). 27Al NMR (65.2 MHz, C6D6): δ ) 143.9 (s, W1/2
≈ 1500 Hz). 29Si NMR (99.4 MHz, C6D6): δ ) 0.2. MS (EI) [m/z
(%)]: 1492 (89, M+). IR: ν˜ ) 1268, 1086, 1022, 802, 728, 605
cm-1. Anal. Calcd for C42H96Al8Br6N2Si6: C, 33.79; H, 6.48; N,
1.88. Found: C, 34.64; H, 6.63; N, 1.75.
for several weeks afforded intensive green-yellow crystals of 13
with toluene and a B-F compound. Filtering these crystals off and
storing the solution at -25 °C afforded another crop of crystals
(plates) of 13‚6toluene with the same color. The crystals were dried
in vacuo at 40 °C. Yield: ca. 100 mg (ca. 94 µmol, ca. 45%) and
ca. 120 mg crude product. Mp: slow change of color above 280
°C, no melting or full dec until 400 °C. Anal. Calcd for C54H60-
Al8F6N2: C, 62.79; H, 5.67; N, 2.63. Found: C, 63.44; H, 5.99;
N, 2.43.
[(AlX)6(AlNMe3)2(CCH2Ph)6] (X ) Cl (14), Br (15), I (16)).
A mixture of [(AlH)6(AlNMe3)2(CCH2Ph)6] (5) and an excess of
Me3SiX in toluene was stirred, refluxed for 2 h, and filtered hot
giving crude products of 14-16 and green-yellow solutions from
which the compounds precipitated as crystalline solids at room
temperature and lower temperatures. Obtained crystalline products
were dried in vacuo for several h at 40 °C.
[(AlI)6(AlNMe3)2(CCH2CH2SiMe3)6] (11). Method a. BI3 (0.22
g, 0.56 mmol, 2.5 equiv) was cooled to -196 °C, and a solution of
[(AlH)6(AlNMe3)2(CCH2CH2SiMe3)6] (6) (0.23 g, 0.225 mmol, 1.0
equiv) in toluene (20 mL) was added. The mixture was brought to
-78 °C, stirred at this temperature for 30 min, and slowly warmed
to room temperature. All volatiles were removed, and the product
was dried at 50 °C in vacuo. Yield: 0.36 g (0.203 mmol, 90%).
Method b. A mixture of Me3SiI (0.265 mL, 0.37 g, 1.86 mmol,
10 equiv) and [(AlH)6(AlNMe3)2(CCH2CH2SiMe3)6] (0.19 g, 0.186
mmol, 1.0 equiv) in toluene (20 mL) was stirred 1 h at room
temperature and refluxed for 30 min. All volatiles were removed
in vacuo, and the product was dried at 50 °C in vacuo. Yield: 0.315
14: 5 (0.29 g, 0.303 mmol, 1.0 equiv), Me3SiCl (1.00 mL, 0.86
g, 7.92 mmol, 26 equiv), toluene (35 mL); yield ca. 90 mg (ca. 77
µmol, 26%) and ca. 220 mg of crude product; mp 280 °C (dec).
Anal. Calcd for C54H60Al8Cl6N2: C, 55.64; H, 5.19; N, 2.40.
Found: C, 56.46; H, 5.05; N, 2.19.
15: 5 (0.22 g, 0.23 mmol, 1.0 equiv), Me3SiBr (0.42 mL, 0.49
g, 3.22 mmol, 14 equiv), toluene (25 mL); yield ca. 100 mg (ca.
75 µmol, 33%) and ca. 210 mg of crude product; mp 262 °C (dec).
Anal. Calcd for C54H60Al8Br6N2: C, 45.28; H, 4.22; N, 1.96.
Found: C, 43.56; H, 4.40; N, 2.08.
1
g (0.177 mmol, 95%). Mp: 262 °C (dec). H NMR (200 MHz,
C6D6): δ ) 0.15 (s, 54 H, Si(CH3)3), 1.60 (ddd, J ) 9.1, 4.3, 4.3
Hz, 12 H; Me3SiCH2), 2.25 (s, 18 H, N(CH3)3), 2.39 (ddd, J )
9.1, 4.3, 4.3 Hz, 12 H; CCH2). 13C NMR (126 MHz, C6D6): δ )
-1.30 (Si(CH3)3), 29.1 (Me3SiCH2), 29.4 (broad, cluster-C), 32.6
(CH2C), 49.1 (N(CH3)3). 27Al NMR (65.2 MHz, C6D6): δ ) 144.9
(s, W1/2 ≈ 2300 Hz). 29Si NMR (99.4 MHz, C6D6): δ ) 0.3. MS
(EI) [m/z (%)]: 1774 (3, M+). IR: ν˜ ) 1268, 1086, 1022, 802,
728, 605 cm-1. Anal. Calcd for C42H96Al8I6N2Si6: C, 28.42; H,
5.45; N, 1.58. Found: C, 29.14; H, 5.69; N, 1.47.
[(AlF)6(AlNMe3)2(CCH2Ph)6] (13). BF3‚OEt2 (0.18 mL, 0.20
g, 1.41 mmol, 6.7 equiv) was added to a fine suspension of [(AlH)6-
(AlNMe3)2(CCH2Ph)6] (5) (0.20 g, 0.209 mmol, 1.0 equiv) in
toluene (20 mL) and stirred for 3 h. The mixture was refluxed for
30 min followed by hot filtration giving a greenish crude product
and a yellow solution. Storing the solution at room temperature
16: 5 (0.20 g, 0.21 mmol, 1.0 equiv), Me3SiI (0.30 mL, 0.42 g,
2.09 mmol, 10 equiv), toluene (25 mL); yield: ca. 150 mg (ca. 88
µmol, 42%) and ca. 170 mg of crude product; mp 232 °C (dec).
Anal. Calcd for C54H60Al8I6N2: C, 37.83; H, 3.53; N, 1.63.
Found: C, 38.13; H, 3.62; N, 1.55.
Acknowledgment. This work was supported by the
Deutsche Forschungsgemeinschaft and the Go¨ttinger Aka-
demie der Wissenschaften.
Supporting Information Available: Crystallographic data in
CIF format. This material is available free of charge via the Internet
at http://pubs.acs.org.
IC035460I
3630 Inorganic Chemistry, Vol. 43, No. 12, 2004