Hydroalumination and hydrogallation reactions with tri(ethynyl)silanes - Generation of compounds with up to three coordinatively unsaturated aluminium atoms

Article abstract of DOI:10.1002/zaac.201100418

Hydroalumination or hydrogallation of tri(ethynyl)silanes, RSi(C≡C-Ar)₃ (1a, R = Ph, Ar = Ph; 1b, R = Me, Ar = Ph; 1c, R = Me, Ar = C₆H₄Me), with the element hydrides H-EtBu ₂ (E = Al, Ga) in stoichiometric rati

Full text of DOI:10.1002/zaac.201100418

ARTICLE
DOI: 10.1002/zaac.201100418
Hydroalumination and Hydrogallation Reactions with Tri(ethynyl)silanes –
Generation of Compounds with up to Three Coordinatively Unsaturated
Aluminium Atoms
Werner Uhl,*[a] Jörg Bohnemann,[a] Denis Heller,[a] Alexander Hepp,[a] and
Marcus Layh[a]
Keywords: Aluminium; Silanes; Alkynes; Hydroalumination; Hydrogallation; Lewis acids
Abstract. Hydroalumination or hydrogallation of tri(ethynyl)silanes, a relatively close interaction between the coordinatively unsaturated
RSi(CϵC-Ar)3 (1a, R = Ph, Ar = Ph; 1b, R = Me, Ar = Ph; 1c, R = aluminium or gallium atoms and one of the Cα(ϵC) atoms of unre-
Me, Ar = C6H4Me), with the element hydrides H-EtBu2 (E = Al, Ga) acted alkyne substituents [245 (E = Al) and 266 pm (E = Ga)] that
in stoichiometric ratios of 1:1 to 1:3 at ambient temperature yielded stabilises the kinetically favoured cis addition products with E and
the addition products (PhCϵC)2(R)Si[(tBu2E)C=C(H)Ph] (2, R = Ph, hydrogen on the same side of the resulting C=C double bonds. In
E = Ga; 3a, R = Me, E = Al; 3b, R = Me, E = Ga), (PhCϵC)(Me) the absence of these stabilising effects the compounds were found to
Si[(tBu2E)C=C(H)Ph]2 (4a, E = Al, 4b, E = Ga) and (Me)Si[(tBu2Al)
isomerise to the thermodynamically favoured trans isomers.
C=C(H)Ar]3 (5, Ar = Ph; 6, Ar = C6H4Me). Compounds 2–4 show
to prevent these reactions by stabilisation of the primary ad-
dition products. Another important aspect of these hydride ad-
dition reactions is cis/trans isomerisation of the resulting al-
kenes which has been found in particular with trimethysilyl-
substituted alkynes. The trans isomer (Al or Ga trans to H)
was calculated to be thermodynamically favoured. Rearrange-
ment of the primarily formed and kinetically favoured cis iso-
mer seems to require intermolecular activation.[11,12] cis/trans
Isomerisation is in most cases fast but may be precluded for
steric reasons or as a result of inter- or intramolecular coordi-
nation of the three-coordinate metal atom (for examples see
below).
The hydride addition products of oligofunctional alkynes are
of potential interest as effective chelating Lewis acids.[13] Par-
ticularly impressive was the recent synthesis of unusual zwitter-
ionic carbocations,[14] that were stabilised by the chelating co-
ordination of the hydride ion and the formation of Al–H–Al
bridges. These reactions show proof of concept for the potential
of these compounds for the mobilisation of anions in organic
solvents and as phase-transfer catalysts. Only recently we
started with investigations into the hydroalumination of bis-
(alkynyl)silanes or -germanes.[15–17] Novel functional com-
pounds were isolated which beyond their propensity to act as
oligoacceptors showed interesting reactions such as dismu-
tation[16] or thermal rearrangement to yield silacyclobutene and
spirogermanium derivatives by 1,1-carbalumination.[17] Fol-
lowing these investigations we now present reactions of tri-
(ethynyl)silanes with tBu2AlH and tBu2GaH that give access to
the respective addition products with one, two or three coordi-
natively unsaturated aluminium or gallium atoms in single mo-
lecules.
Introduction
The addition of dialkylaluminium hydrides to the CϵC tri-
ple bonds of alkynes (hydroalumination) is a well established
method for the synthesis of a wide range of organometallic
compounds.[1,2] In contrast, systematic investigations into
strongly related hydrogallation reactions[2,3] started only re-
cently with the elaboration of facile methods for the synthesis
of the corresponding dialkylgallium hydrides by our group.[4,5]
In many cases the simple addition reactions are followed by
secondary processes which yield unique compounds with un-
precedented molecular structures. The hydroalumination of
aluminium alkynides, R2Al-CϵCRЈ, for instance, was found to
result in the elimination of trialkylaluminium species and the
formation of stable carbaalanes with clusters of aluminium and
carbon atoms[6] that are structurally and electronically related
to the well described carbaborane cluster compounds. Het-
eroadamantane cages with localised Ga–C bonds were isolated
instead from the analogous reactions of gallium alkynides with
dialkylgallium hydrides.[7] Similar condensation reactions have
been observed with oligoalkynes (tBuCϵC)xC6H6–x (x = 2, 3)
which gave compounds with a cyclophane-type molecular
structure.[8,9] Steric shielding in the case of the bulky
CH(SiMe3)2 substituent[10] or coordinative saturation via
bridging vinyl groups in the case of small substituents[9] seem
* Prof. Dr. W. Uhl
Fax: +49-251-8336660
E-Mail: uhlw@uni-muenster.de
[a] Institut für Anorganische und Analytische Chemie
Universität Münster
Corrensstraße 30
48149 Münster, Germany
68
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Hydroalumination and Hydrogallation Reactions with Tri(ethynyl)silanes
Results and Discussion
Reactions of Tri(ethynyl)silanes with Dialkylaluminium or
-gallium Hydrides
The reactions of the triethynyl compounds 1a–1c with
tBu2AlH or tBu2GaH in different stoichiometric ratios are
summarised in Equation (1). Treatment of 1a and 1b with equi-
molar quantities of tBu2GaH at room temperature yielded the
mono-addition products 2 and 3b as a colourless solid or a
yellowish, highly viscous liquid in good yields of 69 and 82%.
Surprisingly, the pure mono-hydroalumination product 3a was
only accessible by using a large excess (two equivalents) of
the alkyne 1b, which then had to be separated by fractional
crystallisation, whereas a stoichiometric 1:1 ratio of the start-
ing materials yielded the product of dual hydroalumination
(4a) in close to quantitative yield together with surplus alkyne.
These reactions were complete after relatively short times of
less than 4 h. In contrast, the hydroalumination of 1b or 1c
with two or three equivalents of tBu2EH gave the correspond-
ing products 4, 5, and 6 only in moderate to poor yields and
required long reaction times of up to 9 d. The synthesis of
compound 6 under optimised reaction conditions was finally
carried out by heating a solution in toluene to 75 °C for 4 h.
The comparatively poor yields of the latter compounds do not
reflect an incomplete or non-uniform reaction but are instead
the result of their high solubility in non-polar solvents and the
resulting difficulties in purifying the products by crystallisa-
tion. Reactions of 1a with two or three equivalents of tBu2EH
or treatment of the tri(ethynyl)silanes with sterically less
shielded element hydrides such as Me2AlH gave inseparable
mixtures of unknown components.
The NMR spectra of the products are characterised by a low
field signal for the vinylic hydrogen atom (about 8 ppm) in the
1H NMR spectra and a significant low field shift of the 29Si
NMR signals in comparison to the free tri(alkynyl)silane. This
shift correlates to the increasing number of vinyl groups of aluminium and hydrogen. The surprising stability of the cis
bonded to the silicon atom and the associated deshielding ef- configuration in 2–4 may be rationalised by an interaction be-
fect on atoms in the plane of the olefin and ranges from below tween the coordinatively unsaturated aluminium or gallium
δ = –60 (1a, δ = –68.8; 1b, δ = –63.9; 1c, δ = –64.2) in the atoms with an α-carbon atom of an ethynyl substituent which
free alkynylsilanes over about δ = –54 (2, 3a, 3b), –32 (4a, is schematically shown in Equation (1) and is discussed in
4b) to –18 (5, 6). The configuration of the olefinic substituents detail below. Interestingly, compounds 4a and 4b showed three
(hydrogen cis or trans relative to the silicon atom) was easily different resonances of tert-butyl groups in the 1H and 13C
3
determined from the JSi–H coupling constants, that are NMR spectra in an intensity ratio of 2:1:1. Temperature de-
1
Ͻ15 Hz with hydrogen and silicon atoms on the same side and pendent H NMR experiments with solutions of 4b (E = Ga)
Ͼ20 Hz with hydrogen and silicon atoms on different sides of in toluene did not result in a significant change at elevated
the C=C double bonds.[10,11] The latter case reflects the kinet- temperatures, apart from some more or less pronounced
ically favoured but thermodynamically disfavoured product of changes of the chemical shifts of these three resonances (300
cis addition of the element hydrides to the alkynes with alu- K: δ = 1.39, 1.27 and 1.04; 360 K: δ = 1.34, 1.21 and 1.03).
minium and hydrogen on the same side.[11] The coupling con- At lower temperatures the resonance at a low field became
stants in compounds 2–6 [25.8 Hz (2); 27.2 Hz (3a); 25.0 Hz broad and finally split into two narrow singlet signals (220 K:
(3b); 25.2 and 14.4 Hz (4a); 24.0 and 13.0 Hz (4b); 11.0 Hz δ = 1.51 and 1.47; δ = 1.31 and 1.05 for the remaining two
(5); 10.5 Hz (6)] are indicative of the cis arrangement of E and resonances). The coalescence temperature was at about 260 K,
hydrogen in 2 and 3a/b. In the case of the doubly reduced and the rotational barrier was estimated to be only 13
compounds 4a and 4b only one alkenyl group has the cis con- kcal·mol–1.[18] Interestingly, careful analysis of the spectra
figuration, whereas the other one is rearranged with aluminium gave clear evidence that the alkenyl group with a trans-ar-
or gallium and hydrogen in trans positions. In compounds 5 rangement of gallium and hydrogen showed two signals for the
and 6 all three vinylic substituents adopt a trans arrangement tert-butyl resonances over the complete range of temperatures
Z. Anorg. Allg. Chem. 2012, 68–75
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69

W. Uhl, J. Bohnemann, D. Heller, A. Hepp, M. Layh
ARTICLE
which indicates a relatively high rotational barrier about the ECSiC heterocycles with torsion angles close to 0°. The signif-
Ga–C(vinyl) bond in this case. In this part of the molecule the
phenyl and GatBu2 substituents are on the same side of the
C=C double bond and the resulting close contact between both
groups clearly prevents the equilibration of the tert-butyl
groups. In contrast the almost free rotation of the dialkylgal-
lium moiety in the second alkenyl group (cis-arrangement of
gallium and hydrogen), which is hindered only at low tempera-
ture is in accordance with a relatively weak interaction be-
tween the coordinatively unsaturated gallium atom and the α-
carbon atom of the remaining CϵC triple bond. However, in
spite of its obvious weakness this interaction seems to be
strong enough to influence the molecular configuration.
icantly shorter contacts in the case of aluminium reflect the
higher Lewis acidity of aluminium in comparison to gallium
atoms. The E–Cα(ϵC) interaction causes relatively acute endo-
cyclic C–Si–C angles between the vinylic and alkynyl carbon
atoms (97 to 101°). Further, the nominally three-coordinate
Group 13 elements deviate from a planar coordination sphere
as evident from the distances between the metal atoms and the
plane of the three directly bound carbon atoms that range from
32 pm in the aluminium compound 4a to about 22 pm in the
vinylgallium derivatives 2 and 4b. Similar structures have been
observed for the hydroalumination products of silicon or ger-
manium centered dialkynes.[15–17] cis/trans Rearrangement fol-
lowing the primary cis addition of the E–H bonds to alkynes
requires intermolecular activation by an increased coordination
number of the α-carbon atoms in order to reduce the rotational
barrier about the C=C double bonds of the alkenyl groups.[11]
The interaction between the metal atoms and the alkynyl
groups in 2, 3, and 4 stabilises the kinetically favoured cis
addition products (E to H) and prevents the generally rapid
isomerisation. Interestingly, the remaining vinyl groups in
compounds 4a and 4b as well as those in 5 and 6 lack the
described stabilisation by E–C interactions and adopt the ther-
modynamically more stable trans configuration which is stabi-
lised by an approach of the bond angles to ideal values and a
weak interaction between the Group 13 element and one of the
ortho-carbon atoms of the adjacent phenyl rings [approxi-
mately 269 pm (Al) and 287 pm (Ga)].[11] The latter causes a
relatively small deviation from planarity of the metal coordina-
tion sphere in the range of 13 to 18 pm (Al) or 9 pm (Ga) (cf.
Table 1). Compounds 4a and 4b have both isomeric forms of
the alkenyl groups realised in a single molecule. The observed
E–C, C=C and CϵC bonds are unexceptional. The molecules
of compounds 4a and 4b are chiral as a consequence of four
different substituents attached to the silicon atom, the vinyl
substituents become non-equivalent as a result of their dif-
ferent configuration. The presence of racemic mixtures is evi-
dent from space group symmetry. Compounds 5 and 6 have
three alkenyl groups and three coordinatively unsaturated alu-
minium atoms. They show approximate C3 symmetry along
the Me–Si axis that corresponds with the observed chemical
equivalence of the three alkenyl fragments in the solution
NMR spectra. Compound 6 crystallises as a loosely bonded
dimer that is held together in the solid state by van der Waals
interactions and four C–H···π contacts between ortho-hydrogen
and ortho-carbon atoms of phenyl groups of the monomeric
fragments (C···H 282 pm, Figure 5). The formation of similar
weak dimers was observed in the structure of the phenyl deriv-
ative 5 (C···H 289 pm). 4a and 4b do not show comparably
short intermolecular interactions, whereas the alkenyl phenyl
group of 2 has short contacts between its ortho-carbon atom
C18 and two hydrogen atoms of different molecules to give a
pseudo-polymer (C···H 290 pm). The CH/π hydrogen bond as
a cooperative force and its significance for the structures of
organic molecules have been reviewed recently.[19]
Crystal Structure Determinations
The molecular structures of compounds 2 and 4–6 are
shown in Figure 1, Figure 2, Figure 3, and Figure 4 (the struc-
ture of 4b is very similar to that of 4a and is not shown sepa-
rately) with selected structural parameters being summarised
in Table 1. The molecular structures clearly confirm the re-
spective cis or trans configuration of the vinyl groups as pre-
dicted by NMR spectroscopy. Crystal data gives clear evidence
that intramolecular interactions influence cis/trans rearrange-
ment. The partially reduced species with intact CϵC triple
bonds (2 and 4a/b) show a close contact between the coordina-
tively unsaturated aluminium or gallium atoms and an α-car-
bon atom of the remaining alkynyl moieties which bear a rela-
tively high negative charge. Relatively short intramolecular
E···C distances result [267.4 pm (2, E = Ga); 244.4 and
244.6 pm (4a, E = Al); 264.2 and 265.0 pm (4b, E = Ga);
compared to about 200 pm for covalent E–C bonds], which
lead to the formation of almost ideally planar four-membered
Figure 1. Molecular structure and atomic numbering scheme of 2; dis-
placement ellipsoids are drawn at the 40% level. Hydrogen atoms
(H12 only) have been drawn with arbitrary radius.
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Hydroalumination and Hydrogallation Reactions with Tri(ethynyl)silanes
Figure 2. Molecular structure and atomic numbering scheme of 4a
(there are two independent molecules in the unit cell, only the S-en-
antiomer is shown); displacement ellipsoids are drawn at the 40%
level. Hydrogen atoms (H112, H122 only) have been drawn with arbi-
trary radius. An analogous structure was observed for compound 4b
(E = Ga).
Figure 4. Molecular structure and atomic numbering scheme of 6; dis-
placement ellipsoids are drawn at the 40% level. Methyl groups
(CMe3) have been omitted for clarity. Hydrogen atoms (H12, H22,
H32 only) have been drawn with arbitrary radius.
resonances (chemical shift data in δ). 13C NMR spectra were all pro-
ton-decoupled. The assignment of the NMR spectra is based on HSQC,
HMBC, H/Si-HMBC, ROESY and DEPT135 data. Elemental analyses
were determined by the microanalytic laboratory of the Westfälische
Wilhelms Universität Münster. IR spectra were recorded as Nujol mull
between KBr or CsI plates with a Shimadzu Prestige 21 spectrometer,
electron impact mass spectra with a Varian mass spectrometer. Only
the most intensive masses of a particular molecular fragment are given
in the description of the mass spectra; the isotopic patterns were in
agreement with the calculated ones. tBu2AlH,[4,20] tBu2GaH[3] and the
trialkynes 1a and 1b[21] were synthesised according to literature pro-
cedures. 1c was synthesised in analogy to 1a and 1b.
Synthesis
MeSi(CϵCC6H4Me)3 (1c): nBuLi (12.7 mmol, 7.9 mL, 1.6 m in hex-
ane) was added dropwise to a solution of p-tolylethyne (1.47 g,
12.7 mmol) in diethyl ether (50 mL) at –78 °C. The reaction mixture
was stirred for 2 h at this temperature and afterwards treated with
methyltrichlorosilane (0.63 g, 4.22 mmol). After stirring for 2 h at
–78 °C the mixture was allowed to warm to room temperature and
stirred for another 16 h. The suspension was treated with HCl (10%)
and twice extracted with toluene (20 mL). The organic phase was dried
with MgSO4 and filtered. The solvent was removed in vacuo and the
residue was dissolved in a small quantity of toluene. The product crys-
tallised when pentane was slowly added to the cooled solution
(–30 °C) and was isolated by removal of the solvent and drying in
Figure 3. Molecular structure and atomic numbering scheme of 5; dis-
placement ellipsoids are drawn at the 40% level. Methyl groups
(CMe3) have been omitted for clarity. Hydrogen atoms (H12, H22,
H32 only) have been drawn with arbitrary radius.
Experimental Section
General: All procedures were carried out under an atmosphere of puri-
vacuo. Yield: 1.44 g (88%). M.p. (argon, sealed capillary): 148 °C. 1H
3
fied argon in dried solvents (toluene over Na/benzophenone, n-pentane NMR (400 MHz, C6D6, 300 K): δ = 7.36 (d, JH,H = 8.0 Hz, 6 H,
3
and cyclopentane over LiAlH4, pentafluorobenzene over molecular si- ortho-H), 6.69 (d, JH,H = 8.0 Hz, 6 H, meta-H), 1.90 (s, 9 H, CH3
eves). NMR spectra were recorded in [D6]benzene at ambient probe p-Tol), 0.86 (s, 3 H, SiCH3). 13C NMR (100 MHz, C6D6, 300 K): δ =
temperature using the following Bruker instruments: Avance I (1H,
139.4 (para-C), 132.6 (ortho-C), 129.3 (meta-C), 120.0 (ipso-C), 107.5
400.13; 13C, 100.6; 29Si, 79.49 MHz) or Avance III (1H, 400.03; 13C, (Si-CϵC), 88.4 (Si-CϵC), 21.3 (Me p-Tol), 2.1 (SiMe). 29Si NMR
100.59; 29Si 79.47 MHz) and referenced internally to residual solvent (79.5 MHz, C6D6, 300 K): δ = 64.2. IR (KBr, paraffin): ν(bar) = 2214
Z. Anorg. Allg. Chem. 2012, 68–75
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71

W. Uhl, J. Bohnemann, D. Heller, A. Hepp, M. Layh
ARTICLE
Table 1. Selected bond lengths (pm) and angles (°) of compounds 2 and 4–6.
Structural parameters
C=C /pm
2 (Ga)
4a (Al)
4b (Ga)
5 (Al)
6 (Al)
134.5(3)
134.9(3)
[134.8(3)]a) (cis)
133.9(3)
[134.0(3)] (trans)
–
120.9(3)
[120.6(3)]
198.6
134.5(4)
[134.7(4)]a) (cis)
134.1(4)
[134.3(4)] (trans)
–
120.9(4)
[120.5(4)]
200.1
135.2(4)
134.5(4)
134.5(4)
135.3(2)
134.4(2)
135.2(2)
CϵC /pm
CϵC(···E) /pm
120.6(3)
119.7(3)
–
–
–
–
E–C(av.) /pm
200.1
267.4(3)
21.1
199.2
199.5
[198.7]
[200.3]
E···α-CϵC /pm
244.4(2)
[244.6(2)]
32.1
[32.1]
268.2
264.1(3)
[264.9(3)]
23.3
[22.9]
286.8
–
–
–
–
distance (Eb)···C3 plane) /pm
E···o-C(Ph) /pm
–
268.3
268.8
268.9
13.8
266.8
263.7
262.2
18.0
[285.0]
[300.7]
distance (Ec)···C3 plane) /pm
–
16.8
[13.2]
10.3
[7.9]
13.6
14.7
16.3
14.5
Є (alkenyl)C–Si–C(alkynyl) /°
100.5(1)
–0.4(1)
96.6(1)
[96.6(1)]
0.7(1)
99.0(1)
[99.2(1)]
–0.9(2)
[1.4(2)]
107.7(1)d)
107.52(8)d)
torsion angle C–Si–C(alkenyl)–E /°
–
–
[–80.4(2)]
a) Values for the second molecule are given in parenthesis; b) E coordinated to CϵC; c) E with weak interaction to o-C of phenyl; d) smallest
C–Si–C angle.
(10 mL). The reaction mixture was stirred for 4 h at room temperature.
The solvent was removed in vacuo, the colourless residue was washed
with a small amount of n-pentane and then dissolved in cyclopentane.
Cooling to –15 °C yielded colourless crystals of 2. Yield: 0.278 g
(69%). M.p. (argon, sealed capillary): 106 °C (dec). 1H NMR
3
4
(400 MHz, C6D6, 300 K): δ = 8.07 (dd, JH,H = 8.2, JH,H = 1.5 Hz, 2
3
H, ortho-H PhSi), 7.93 (s, JH–Si = 25.8 Hz, 1 H, C=CHPh), 7.70 (d,
3JH,H = 7.2 Hz, 2 H, ortho-H C=CPh), 7.40 (dd, JHH = 8.4, JH,H
3
4
=
1.5 Hz, 4 H, ortho-H CϵCPh), 7.13 (m, 2 H, meta-H PhSi), 7.08 (m,
3
1 H, para-H PhSi), 7.06 (m, 2 H, meta-H C=CPh), 6.93 (tt, JH,H
=
4
7.4, JH,H = 1.2 Hz, 1 H, para-H C=CPh), 6.88 (m, 2 H, para-H
CϵCPh), 6.86 (m, 4 H, meta-H CϵCPh), 1.46 (s, 18 H, tBu). 13C
NMR (100 MHz, C6D6, 300 K): δ = 154.8 (C=CHPh), 150.8
(C=CHPh), 140.9 (ipso-C C=CPh), 135.2 (ortho-C PhSi), 133.2 (ipso-
C PhSi), 132.8 (ortho-C CϵCPh), 130.5 (para-C PhSi), 129.6 (para-
C CϵCPh), 128.9 (ortho-C C=CPh), 128.5 (meta-C CϵCPh and PhSi),
128.4 (meta-C C=CPh), 128.2 (para-C C=CPh), 122.3 (ipso-C
CϵCPh), 109.9 (PhCϵCSi), 90.3 (PhCϵCSi), 30.8 (CMe3), 29.6
(CMe3). 29Si NMR (79.5 MHz, C6D6, 300 K): δ = –58.5. IR (KBr,
paraffin): ν(bar) = 2160 m, 2141 m νCϵC; 2037 vw, 1973 vw, 1953
vw, 1908 vw, 1888 vw, 1807 vw, 1767 vw, 1682 w, 1595 w, 1555 w
νC=C, (phenyl); 1454 vs, 1377 vs. (paraffin); 1305 m, 1269 w δCH3;
1219 w, 1169 w, 1157 w, 1111 vw, 1070 vw, 1024 w, 968 w, 918 m,
883 m, 843 m, 810 w, 754 s δCH, νCC; 723 vs. (paraffin); 691 m, 654
w, 640 w, 615 vw, 598 w, 538 w, 513 w, 480 vw, 465 vw, 432 vw
Figure 5. Dimeric formula unit of compound 6 with CH/π hydrogen
bonds.
vw, 2160 vs, 2126 sh, 2077 w νCϵC; 1913 w, 1803 vw, 1655 w, 1605
m, 1562 vw, 1506 vs. (phenyl); 1458 vs, 1408 vw, 1377 vs. (paraffin);
1306 vw, 1250 m δCH3; 1225 s, 1209 w, 1179 w, 1153 vw, 1117 w, νGaC, νSiC, δCC, δ(phenyl) cm–1. MS (EI, 20 eV, 353 K): m/z (%) =
1107 m, 1036 m, 1020 m, 966 vw, 951 w, 918 vw νCC, δCH; 856 vs, 535 (100), 537 (80) (M+ tBu); 479 (12), 481 (8) (M+ tBu – butene).
818 vs, 799 vs, 768 vs. ρCH3(Si), (phenyl); 719 vs. (paraffin); 694 vw,
627 vw, 579 vs, 538 vs, 465 vw, 440 vw νAlC, νSiC, δCC cm–1. MS
(EI, 20 eV; 393 K): m/z (%) = 388 (69) (M+), 373 (100) (M+ – CH3).
CHN (C28H24Si) (388.6): calcd. C 86.5, H 6.2; found C 86.2,
H 6.2 %.
CHN (C38H39GaSi) (593.5): calcd. C 76.9, H 6.6; found C 75.9,
H 6.6 %.
(PhCϵC)2(Me)Si[(tBu2Al)C=C(H)Ph] (3a): A solution of an excess
of (PhCϵC)3SiMe (0.882 g, 2.55 mmol, 2 equivalents) in toluene
(10 mL) was added to a solution of tBu2AlH (0.181 g, 1.27 mmol) in
toluene (10 mL) at 50 °C. The mixture was allowed to warm to room
(PhCϵC)2(Ph)Si[(tBu2Ga)C=C(H)Ph] (2): A solution of (PhCϵC)3-
SiPh (0.276 g, 0.68 mmol) in toluene (10 mL) was added at room tem- temperature and stirred for 1 h. The solvent was removed in vacuo,
perature to a solution of tBu2GaH (0.125 g, 0.68 mmol) in toluene and the resulting pale yellow oil was dissolved in a small quantity of
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Hydroalumination and Hydrogallation Reactions with Tri(ethynyl)silanes
3
cyclopentane. The excess alkyne crystallised upon cooling the mixture cis-C=CPh), 7.07 (t, JH,H = 7.3 Hz, 1 H, para-H cis-C=CPh), 6.97
to –40 °C and was separated. Removal of the solvent in vacuo yielded (m, 4 H, ortho-H and meta-H trans-C=CPh), 6.90 (m, 3 H, meta-H
compound 3a as a pale yellow oil. Yield: 0.457 g (74%). 1H NMR and para-H CϵCPh), 6.87 (m, 1 H, para-H trans-C=CPh), 1.39 (s,
(400 MHz, C6D6, 300 K): δ = 8.10 (s, 3JH–Si = 27.2 Hz, 1 H, C=CHPh),
br., 18 H, cis-C=CAltBu2), 1.19 and 0.93 (each s, 9 H, trans-
3
7.72 (d, JH,H = 7.7 Hz, 2 H, ortho-H C=CPh), 7.45 (m, 4 H, ortho- C=CAltBu2), 0.86 (s, 3 H, SiMe). 13C NMR (100 MHz, C6D6, 300
3
H, CϵCPh), 7.21 (pseudo-t, JH,H = 7.7 Hz, 2 H, meta-H C=CPh), K): δ = 160.2 (trans-C=CHPh), 158.6 (trans-C=CHPh), 155.8 (cis-
3
7.08 (t, JH,H = 7.3 Hz, 1 H, para-H C=CPh), 6.91 (m, 2 H, para-H,
C=CHPh), 150.7 (cis-C=CHPh), 149.3 (ipso-C trans-C=CPh), 141.9
CϵCPh), 6.86 (m, 4 H, meta-H CϵCPh), 1.37 (s, 18 H, tBu), 0.68 (s, (ipso-C cis-C=CPh), 133.8 (ortho-C CϵCPh), 132.2 (meta-C trans-
3 H, SiMe). 13C NMR (100 MHz, C6D6, 300 K): δ = 156.8 (C=CHPh), C=CPh), 131.2 (para-C CϵCPh), 129.0 (para-C trans-C=CPh), 128.8
148.5 (C=CHPh), 142.1 (ipso-C C=CPh), 133.1 (ortho-C CϵCPh),
(meta-C CϵCPh), 128.7 (meta-C cis-C=CPh), 128.4 (ortho-C cis-
130.2 (para-C CϵCPh), 128.7 (meta-C C=CHPh), 128.6 (meta-C C=CPh), 128.0 (para-C cis-C=CPh), 122.2 (ortho-C trans-C=CPh),
CϵCPh), 128.5 (para-C C=CPh), 128.4 (ortho-C C=CPh), 121.5 120.4 (ipso-C CϵCPh), 117.1 (PhCϵCSi), 93.8 (PhCϵCSi), 30.9 (br.,
(ipso-C CϵCPh), 111.7 (PhCϵCSi), 90.7 (PhCϵCSi), 30.6 (CMe3), cis-CMe3), 29.9 and 29.8 (each trans-CMe3), 19.4 (cis-CMe3), 18.9
19.2 (CMe3), 0.4 (SiCH3). 29Si NMR (79.5 MHz, C6D6, 300 K): δ = and 18.8 (each br., trans-CMe3), 1.3 (SiMe). 29Si NMR (79.5 MHz,
–50.6. IR (CsI, paraffin): ν(bar) = 2160 vs, 2129 vs. νCϵC; 2054 vw,
C6D6, 300 K): δ = 30.3. IR (CsI, paraffin): ν(bar) = 2160 vs, 2118 vs.
1948 w, 1883 w, 1830 vw, 1803 w, 1755 vw, 1672 vw, 1651 vw, 1585 νCϵC; 2072 vw, 2018 vw, 1948 w, 1884 w, 1842 vw, 1823 vw, 1800
vs, 1548 vs, 1528 vw, 1487 vs. νC=C, (phenyl); 1462 vs. (paraffin); vw, 1755 vw, 1676 vw, 1630 vw, 1587 s, 1574 s, 1557 vs, 1526 m,
1443 vs. δCH3; 1381 m (paraffin); 1358 m, 1329 vw, 1294 vw, 1279
w, 1248 s δCH3; 1219 s; 1177 m, 1157 w, 1098 vw, 1070 m, 1047 vw,
1026 s, 999 m, 966 vw, 926 s, 885 m δCH, νCC; 847 s, 818 w, 787
m, 754 s ρCH3(Si); 721 m (paraffin); 689 vs, 654 m, 625 w, 611 m,
596 m, 569 m, 538 vs, 509 vs, 455 vs, 435 w νAlC, νSiC, δCC cm–1.
MS (EI, 20 eV, 298 K): m/z (%) = 431 (100) (M+ – tBu).
1491 s νC=C, (phenyl); 1462 vs. (paraffin); 1443 vs, 1402 vw δCH3;
1377 s (paraffin); 1312 w, 1269 vw, 1248 s δCH3; 1217 m, 1179 m,
1155 w, 1099 vw, 1072 s, 1043 sh, 1026 m, 997 m, 964 vw, 932 m,
893 m δCH, νCC; 845 w, 812 w, 783 vw, 754 vw ρCH3(Si); 721 s
(paraffin); 689 w, 638 w, 594 m, 559 w, 538 w, 501 s, 488 s, 447 s
νAlC, νSiC, δCC cm–1. MS (EI, 20 eV, 373 K): m/z (%) = 459 (3)
(M+ – 3tBu), 417 (55) (M+ – 2butene – CϵCPh), 403 (74) (M+
(PhCϵC)2(Me)Si[(tBu2Ga)C=C(H)Ph] (3b): A solution of tBu2GaH 3tBu Al(tBu)2C=CHPh). CHN
butene), 387 (17) (M+
(C41H56Al2Si) (631.0): calcd. C 78.0, H 8.9; found 77.1, H 8.7 %.
–
–
–
(0.151 g, 0.82 mmol) in toluene (25 mL) was treated at –40 °C with
(PhCϵC)3SiMe (0.283 g, 0.82 mmol). The colourless reaction mixture
was allowed to warm to room temperature and stirred for another [Ph(H)C=C(GatBu2)]2Si(Me)CϵCPh
(4b):
(PhCϵC)3SiMe
90 min, which resulted in a gradual colour change to yellow. The sol- (0.528 g, 1.53 mmol) was added to a solution of tBu2GaH (0.564 g,
vent was removed in vacuo to yield compound 3b as an NMR spectro-
3.05 mmol) in toluene (40 mL). The colourless reaction mixture was
stirred for 40 h at room temperature, which resulted in a gradual colour
scopically pure yellow oil (0.358 g, 82%). 1H NMR (400 MHz, C6D6,
3
3
300 K): δ = 7.78 (s, JH–Si = 25.0 Hz, 1 H, C=CHPh), 7.75 (d, JH,H change to yellow. The solvent was removed in vacuo to yield a mixture
= 7.2 Hz, 2 H, ortho-H CH=CPh), 7.45 (m, 4 H, ortho-H CϵCPh), of a yellow oil and a colourless solid. This residue was dissolved in a
3
7.22 (pseudo-t, JH,H = 7.7 Hz, 2 H, meta-H CH=CPh), 7.07 (br. s, 1 small quantity of cyclopentane and cooled to 2 °C to give colourless
H, para-H CH=CPh), 6.90 (m, 2 H, para-H CϵCPh), 6.87 (m, 4 H, crystals of compound 4b. Yield: 0.619 g (57%). M.p. (argon, sealed
2
meta-H CϵCPh), 1.43 (s, 18 H, tBu), 0.65 (s, JH–Si = 7.5 Hz, 3 H, capillary): 142 °C. 1H NMR (400 MHz, C6D6, 300 K): δ = 8.27 (s,
3
SiMe). 13C NMR (100 MHz, C6D6, 300 K): δ = 153.5 (C=CHPh),
153.4 (C=CHPh), 141.6 (ipso-C CH=CPh), 132.7 (ortho-C CϵCPh),
129.5 (para-C CϵCPh), 128.6 (meta-C CH=CPh and meta-C
CϵCPh), 128.5 (ortho-C CH=CPh), 128.1 (para-C CH=CPh), 122.4
3JH–Si = 13.0 Hz, 1 H, trans-C=CHPh), 7.95 (s, JH–Si = 24.0 Hz, 1 H,
cis-C=CHPh), 7.60 (m, 2 H, ortho-H CϵCPh), 7.58 (m, 2 H, ortho-H
cis-CH=CPh), 7.22 (pseudo-t, JH,H = 7.6 Hz, 2 H, meta-H cis-
CH=CPh), 7.07 (t, JH,H = 7.3 Hz, 1 H, para-H cis-CH=CPh), 6.99
3
3
(ipso-C CϵCPh), 108.9 (PhCϵCSi), 91.3 (PhCϵCSi), 30.7 (CMe3), (m, 2 H, meta-H trans-CH=CPh), 6.93 (m, 3 H, para-H CϵCPh and
29.2 (CMe3), 0.4 (SiCH3). 29Si NMR (79.5 MHz, C6D6, 300 K): δ = meta-H CϵCPh), 6.92 (m, 1 H, para-H trans-CH=CPh), 6.90 (m, 2
53.2. IR (CsI, paraffin): ν(bar) = 2158 vs, 2143 vs. νCϵC; 2054 vw,
1946 w, 1894 vw, 1881 vw, 1802 vw, 1751 vw, 1672 vw, 1582 s, 1557
H, ortho-H trans-CH=CPh), 1.43 (s, 18 H, cis-tBu), 1.30 and 1.07
(each s, 9 H, trans-tBu), 0.77 (s, 3 H, SiMe). 13C NMR (100 MHz,
vs, 1487 vs. νC=C, (phenyl); 1462 vs, 1377 s (paraffin); 1362 s, 1294 C6D6, 300 K): δ = 160.2 (trans-C=CHPh), 156.1 (trans-C=CHPh),
vw, 1288 vw, 1248 m δCH3; 1219 m, 1175 w, 1155 vw, 1098 vw, 1070 155.0 (cis-C=CHPh), 152.5 (cis-C=CHPh), 147.0 (ipso-C trans-
m, 1026 m, 1013 m, 966 vw, 920 m, 881 m δCH, νCC; 850 vs, 837 CH=CPh), 141.3 (ipso-C cis-CH=CPh), 133.0 (ortho-C CϵCPh),
vs, 791 v, 754 vs. ρCH3(Si); 716 w (paraffin); 691 vs, 646 m, 625 m, 130.5 (meta-C trans-CH=CPh), 130.0 (para-C CϵCPh), 128.7 (meta-
615 m, 536 vs, 507 s, 451 s, 420 m νSiC, νGaC, δCC cm–1. MS (EI, C cis-CH=CPh and meta-C CϵCPh), 128.5 (ortho-C cis-CH=CPh and
20 eV, 313 K): m/z (%) = 473 (100), 475 (85) (M+ tBu), 417 (11), para-C trans-CH=CPh), 127.9 (para-C cis-CH=CPh), 123.9 (ortho-
419 (8) (M+ butene – tBu).
C trans-CH=CPh), 122.0 (ipso-C CϵCPh), 111.1 (PhCϵCSi), 94.3
(PhCϵCSi), 31.0 (cis-CMe3), 30.3 and 30.2 (each trans-CMe3), 29.2
(cis-CMe3), 29.0 and 28.8 (trans-CMe3), 1.1 (SiCH3). 29Si NMR
[Ph(H)C=C(AltBu2)]2Si(Me)(CϵCPh) (4a): A solution of (PhCϵC)3-
SiMe (0.357 g, 1.03 mmol) in toluene (10 mL) was added at room tem- (79.5 MHz, C6D6, 300 K): δ = –34.2. IR (CsI, paraffin): ν(bar) = 2153
perature to a solution of tBu2AlH (0.293 g, 2.06 mmol) in toluene
(10 mL). The reaction mixture was stirred for 16 h at room tempera-
ture. The solvent was removed in vacuo to yield a yellow residue that
was dissolved in cyclopentane. Cooling to –15 °C afforded colourless
crystals of 4a. Yield: 0.261 g, 40%). M.p. (argon, sealed capillary):
w, 2129 m νCϵC; 2025 vw, 1946 w, 1883 vw, 1800 vw, 1755 vw,
1690 w, 1580 vs, 1558 vs. νC=C, (phenyl); 1462 vs, 1375 vs. (paraffin;
1306 w, 1246 m δCH3; 1209 w, 1171 s, 1155 m, 1099 w, 1070 s, 1026
w, 1003 w, 928 m, 885 s δCH, νCC; 843 w, 808 s, 775 w, 742 s
ρCH3(Si); 721 vs. (paraffin); 698 w, 687 m, 638 m, 611 w, 550 w, 536
m, 503 w, 482 m, 446 s νGaC, νSiC, δCC cm–1. MS (EI, 20 eV, 393
K): m/z (%) = 657 (42), 659 (62), 661 (27) (M+ – tBu); 473 (100),
475 (79) (M+ – HGatBu2 – tBu). CHN (C41H56Ga2Si) (716.4): calcd.
1
3
95 °C (dec). H NMR (400 MHz, C6D6, 300 K): δ = 8.30 (s, JH–Si
=
3
25.2 Hz, 1 H, cis-C=CHPh), 8.23 (s, JH–Si = 14.4 Hz, 1 H, trans-
3
C=CHPh), 7.64 (m, 2 H, ortho-H CϵCPh), 7.53 (d, JH,H = 7.5 Hz, 2
3
H, ortho-H cis-C=CPh), 7.21 (pseudo-t, JH,H = 7.7 Hz, 2 H, meta-H C 68.7, H 7.9; found 68.7, H 7.7 %.
Z. Anorg. Allg. Chem. 2012, 68–75
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
73

W. Uhl, J. Bohnemann, D. Heller, A. Hepp, M. Layh
ARTICLE
[Ph(H)C=C(AltBu2)]3Si(Me) (5): A solution of (PhCϵC)3SiMe
(0.205 g, 0.59 mmol) in toluene (10 mL) was added at room tempera-
ture to a solution of tBu2AlH (0.258 g, 1.82 mmol) in toluene (10 mL).
(C=C(H)p-tol), 146.8 (ipso-C), 138.8 (para-C), 132.8 (meta-C), 122.7
(ortho-C), 30.6 (CMe3), 20.8 (CH3 p-tol), 19.3 (CMe3), 4.1 (SiMe).
29Si NMR (79.5 MHz, C6D6, 300 K): δ = –17.7. IR (KBr, paraffin):
The reaction mixture was stirred for 9 d at room temperature. The ν(bar) = 1931 vw, 1910 vw, 1888 vw, 1805 vw, 1768 vw, 1659 vw,
solvent was removed in vacuo to yield a yellow, oily residue that was 1605 m, 1566 w, 1510 s, 1497 vs. νC=C, (phenyl); 1462 vs, 1377 vs.
dissolved in a small quantity of pentafluorobenzene and kept at 2 °C (paraffin); 1312 m, 1298 m, 1263 w, 1246 m δCH3; 1219 w, 1175 m,
to give colourless crystals of 5. Yield: 0.239 g (52%). M.p. (argon, 1155 w, 1112 m, 1069 w, 1043 m, 999 s, 988 m, 966 vw, 943 s, 908
1
sealed capillary): 146 °C (dec). H NMR (400 MHz, C6D6, 300 K): δ s, 893 m νCC, δCH3; 847 m, 810 vs, 762 w ρCH3(Si); 719 vs. (paraf-
3
3
= 8.27 (s, JH–Si = 11.0 Hz, 3 H, C=CHPh), 7.27 (d, JH,H = 7.1 Hz, 6 fin); 692 m, 663 vw, 642 m, 590 s, 577 s, 529 w, 505 s, 449 s νGaC,
H, ortho-H Ph), 7.12 (m, 6 H, meta-H Ph), 6.96 (t, JH,H = 7.1 Hz, 3 νSiC, δCC cm–1. MS (EI, 20 eV, 393 K): m/z (%) = 758 (33) (M+
H, para-H Ph), 1.08 (s, 54 H, tBu), 0.95 (s, 3 H, SiMe). 13C NMR H2C=CMe2); 615 (43), 616 (21) (M+ – tBu – HAltBu2); 501 (100),
(100 MHz, C6D6, 300 K): δ = 165.9 (C=CHPh), 157.3 (C=CHPh), H2C=CMe2 tBu2Al-C=CH-C6H4Me). CHN
502 (36) (M+
–
3
–
–
149.4 (ipso-C), 132.2 (meta-C), 128.8 (para-C), 122.7 (ortho-C), 30.5 (C52H81Al3Si) (815.3): calcd. C 76.6, H 10.0; found C 75.6, H 9.5 %.
(CMe3), 19.3 (CMe3), 4.0 (SiMe). 29Si NMR (79.5 MHz, C6D6, 300
K): δ = 17.8. IR (CsI, paraffin): ν(bar) = 1946 w, 1886 vw, 1807 w,
1715 vw, 1643 m, 1599 s, 1574 s, 1551 m, 1531 m νC=C, (phenyl);
Crystal Structure Determinations
Crystals suitable for X-ray crystallography were obtained by
recrystallisation from cyclopentane (2, 4a, 4b) or pentafluorobenzene
(5, 6). Intensity data was collected on a Bruker APEX II diffractometer
with monochromated Mo-Kα (2, 6) or Cu-Kα (4a, 4b, 5) radiation. The
collection method involved ω-scans. Data reduction was carried out
using the program SAINT+.[22] The crystal structures were solved by
direct methods using SHELXTL.[23] Non-hydrogen atoms were first
refined isotropically followed by anisotropic refinement by full-matrix
least-squares calculation based on F2 using SHELXTL. Hydrogen
1468 vs, 1375 vs. (paraffin); 1304 m, 1250 m δCH3; 1213 w, 1169 m,
1155 m, 1070 vs, 1043 vs, 1028 vs, 989 m, 978 w, 955 w, 918 m, 889
m νCC, δCH3; 843 m, 812 w, 773 vw ρCH3(Si); 721 vs. (paraffin);
665 vw, 629 m, 592 w, 536 m, 517 m, 472 s, 453 s, 415 m, 365 m,
357 s, 347 m νGaC, νSiC, δCC cm–1. MS (EI, 20 eV, 413 K): m/z (%)
= 715 (34), 716 (18) (M+ – tBu); 573 (34), 575 (12) (M+ – HAltBu2 –
tBu); 473 (100), 474 (36) (M+ – CH2=CMe2 – tBu2Al-C=CHPh). CHN
(C49H75Al3Si) (773.2): calcd. C 76.1, H 9.8; found C 75.5, H 9.8 %.
[(p-MeC6H4)(H)C=C(AltBu2)]3Si(Me) (6):
A solution of (p- atoms were positioned geometrically and allowed to ride on their re-
MeC6H4CϵC)3SiMe (0.206 g, 0.53 mmol) in toluene (10 mL) was spective parent atoms with U = 1.2Ueq(C). Compound 4a and 4b are
added at room temperature to a solution of tBu2AlH (0.226 g, chiral and there are two independent molecules [R, S (4a); R, R (4b)]
1.59 mmol) in toluene (10 mL). The reaction mixture was stirred for in the asymmetric unit. The respective enantiomers are created by the
4 h at 75 °C. The solvent was removed in vacuo to yield a yellow, oily inversion centre of the space group. Compound 5 incorporates a mole-
residue that was dissolved in a small quantity of pentafluorobenzene cule of pentafluorobenzene in the asymmetric unit which is disordered
and kept at 2 °C to give colourless crystals of 6. Yield: 0.140 g (32%).
across the inversion centre. A fluorine atom was refined with an occu-
M.p. (argon, sealed capillary): 170 °C (dec). 1H NMR (400 MHz, pancy factor of 0.5; the hydrogen atom was not considered. A tBu
3
C6D6, 300 K): δ = 8.31 (s, JH–Si = 10.5 Hz, 3 H, C=C(H)p-tol), 7.24
group of 5 (C32) was disordered; the respective atoms were refined in
3
3
(d, JH,H = 7.6 Hz, 6 H, ortho-H), 7.01 (d, JH,H = 7.6 Hz, 6 H, meta- split positions (0.5:0.5). A tBu group (C22) was disordered in com-
H), 1.98 (s, 9 H, Me p-Tol), 1.13 (s, 54 H, tBu), 0.98 (s, 3 H, SiMe). pound 6 (0.54:0.46). Further crystallographic data is summarised in
13C NMR (100 MHz, C6D6, 300 K): δ = 164.7 (C=C(H)p-tol), 157.0 Table 2.
Table 2. Crystal data and structure refinement for compounds 2, 4a, 4b, 5 and 6.
Compound
2
4a
4b
5·0.5C6F5H
6
Empirical formula
Crystal system
Space group
C38H39GaSi
monoclinic
P21/c
C41H56Al2Si
triclinic
P1
C41H56Ga2Si
triclinic
P1
C52H75Al3F2.50Si
triclinic
P1
C52H81Al3Si
triclinic
P1
¯
¯
¯
¯
Z
4
4
4
2
2
T /K
153(2)
1.173
153(2)
1.068
153(2)
1.207
153(2)
1.090
153(2)
1.029
Density (calc) /g·cm–3
a /pm
b /pm
c /pm
α /°
1759.9(4)
1080.2(2)
1768.1(4)
90
90.54(3)
90
1219.29(2)
1358.14(2)
241.49(4)
100.451(1)
101.376(1)
90.682(1)
3.9250(1)
1.135
1220.51(2)
1363.41(3)
2461.15(5)
100.653(1)
101.243(1)
90.364(1)
3.9438(1)
1.207
1371.10(3)
1371.46(3)
1541.49(4)
102.094(2)
98.415(2)
108.832(1)
2.6099(1)
1.195
1438.67(6)
1506.97(6)
1547.1(1)
105.789(1)
104.408(1)
112.404(1)
2.6315(2)
0.125
β /°
γ /°
Volume /nm3
3.361(1)
0.877
μ /mm–1
Radiation
Theta range /°
Independent reflections
Mo-Kα
2.21–29.32
Cu-Kα
Cu-Kα
Cu-Kα
3.01–72.37
8851 (Rint
0.0382)
582
Mo-Kα
1.86–72.37
13352 (Rint
0.0297)
819
3.30–72.42
13297 (Rint
0.0268)
819
1.55–30.04
15233 (Rint
0.0310)
552
9074 (Rint
0.0491)
367
=
=
=
=
=
Parameters
R1 [I Ͼ 2σ(I)]
wR2(all data)
0.0421 (4654)
0.0721
0.0498 (9822)
0.1394
0.0409 (10652)
0.1082
0.0582 (6443)
0.1677
0.0522 (9926)
0.1523
Max./ min. residual electron density / 402/–226
428/–289
539/–382
505/–230
481/–387
e·nm–3
R1 = Σ||Fo|–|Fc||/Σ|Fo|, wR2 = {Σ [w(Fo –Fc ) ]/Σ [(Fo ) ]}1/2
2
2 2
2 2
74 www.zaac.wiley-vch.de
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 68–75

Hydroalumination and Hydrogallation Reactions with Tri(ethynyl)silanes
406; W. Uhl, F. Breher, J. Grunenberg, A. Lützen, W. Saak, Orga-
nometallics 2000, 19, 4536; W. Uhl, F. Breher, A. Mbonimana, J.
Gauss, D. Haase, A. Lützen, W. Saak, Eur. J. Inorg. Chem. 2001,
3059; A. Stasch, M. Ferbinteanu, J. Prust, W. Zheng, F. Cim-
poesu, H. W. Roesky, J. Magull, H.-G. Schmidt, M. Noltemeyer,
J. Am. Chem. Soc. 2002, 124, 5441; S. S. Kumar, J. Rong, S.
Singh, H. W. Roesky, D. Vidovic, J. Magull, D. Neculai, V. Chan-
drasekhar, M. Baldus, Organometallics 2004, 23, 3496; W. Uhl,
H. W. Roesky, in: Molecular Clusters of the Main Group Ele-
ments (Eds.: M. Driess, H. Nöth), Wiley-VCH Verlag, Weinheim,
2004, p. 357.
The crystallographic data was deposited as supplementary publication
no. CCDC-840609 (for 2), -840610 (for 4a), -840611 (for 4b), -840612
(5⋅0.5C6F5 H) and -840613 (for 6). These data can be obtained free of
charge from the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, Great Britain (Fax: +44-1223-336-033;
E-mail: deposit@cccd.cam.ac.uk).
Acknowledgement
We are grateful to the Deutsche Forschungsgemeinschaft for generous
financial support.
[7] W. Uhl, L. Cuypers, B. Neumüller, F. Weller, Organometallics
2002, 21, 2365.
[8] W. Uhl, A. Hepp, M. Matar, A. Vinogradov, Eur. J. Inorg. Chem.
2007, 4133; W. Uhl, F. Breher, S. Haddadpour, Organometallics
2005, 24, 2210.
[9] W. Uhl, M. Claesener, S. Haddadpour, B. Jasper, A. Hepp, Dalton
Trans. 2007, 417; W. Uhl, S. Haddadpour, M. Matar, Organome-
tallics 2006, 25, 159; W. Uhl, M. Claesener, A. Hepp, B. Jasper,
A. Vinogradov, L. van Wüllen, T. K.-J. Köster, Dalton Trans.
2009, 10550.
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Received: September 20, 2011
Published Online: October 28, 2011
Z. Anorg. Allg. Chem. 2012, 68–75
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www.zaac.wiley-vch.de
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