Hydrometallation (M = Al, Ga) of Silicon- And Germanium-centred Oligoalkynes

Article abstract of DOI:10.5560/ZNB.2014-4151

Treatment of a variety of alkyl- And arylsilanes, R_4-nSi(C≡C-R′)n, and -germanes, R_4-nGe(C≡CR 0)n (1-7), with equimolar quantities of the dialkylmetal hydrides HMR″2 (M = Al, Ga; R″ = CMe₃, CH₂CHMe₂)

Full text of DOI:10.5560/ZNB.2014-4151

Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred
Oligoalkynes
Werner Uhl, Jörg Bohnemann, Benedikt Kappelt, Kira Malessa, Martina Rohling,
Jens Tannert, Marcus Layh, and Alexander Hepp
Institut für Anorganische und Analytische Chemie der Universität Münster, Corrensstraße 30,
48149 Münster, Germany
Reprint requests to Prof. Werner Uhl. E-mail: uhlw@uni-muenster.de
Z. Naturforsch. 2014, 69b, 1333 – 1347 / DOI: 10.5560/ZNB.2014-4151
Received July 11, 2014
Dedicated to Professor Hubert Schmidbaur on the occasion of his 80th birthday
Treatment of a variety of alkyl- and arylsilanes, R4−nSi(C≡C-R0)n, and -germanes, R4−nGe(C≡C-
R0)n (1–7), with equimolar quantities of the dialkylmetal hydrides HMR00 (M = Al, Ga;
2
R00 = CMe3, CH2CHMe2) yielded by reduction of a single alkynyl group a series of
mixed alkenyl-alkynyl compounds R4−nSi(C≡C-R0)n−1{C(MR002) =CHR0} (n = 2, 3) and
R2Ge(C≡C-R0){C[M(CMe3)2]=CHR0} (8–13). Reactions with two equivalents of the hydrides af-
forded the dialkenyl compounds R2E{C[(M(CMe3)2]=CHR0}2 (E = Si, Ge, 14–17), Ge(C≡C–
CMe3)2{C[Ga(CMe3)2]=CH–CMe3}2 (18) and MeSi(C≡C-p-Tol){C[Ga(CMe3)2]=CH-p-Tol}2
(19) [R = Ph, Mes, Me, C6F5; R0 = CMe3, Ph). Most of the products were characterised by X-
ray crystallography which for the alkenyl-alkynyl derivatives revealed short intramolecular contacts
between the coordinatively unsaturated metal atoms and the α-C atoms of unreacted ethynyl groups
Cα ≡C-R0.
Key words: Hydroalumination, Hydrogallation, Silicon, Germanium, Alkynes
Introduction
tion between the coordinatively unsaturated aluminium
and gallium atoms and the α-carbon atoms of the
Treatment of oligoalkynylsilanes and -germanes, C≡C triple bonds bearing a relatively high partial
R4−nE(C≡C-R0)n (E = Si, Ge), with equimolar quan- negative charge [1, 2, 4 – 7]. Only in the case of the
tities of dialkylaluminium or -gallium hydrides, H– very bulky bis(trimethylsilyl)methylaluminium deriva-
MR00 (M = Al, Ga), have been shown to afford tives an approach of the functional groups is pre-
2
mixed alkenyl-alkynylsilicon and -germanium com- vented by strong steric repulsion [1, 3]. These in-
pounds [1 – 7] by addition of an E–H bond to a C≡C teractions activate the E–C bonds, and as a conse-
triple bond (hydroalumination, hydrogallation [8]; quence a thermally induced rearrangement resulted in
Scheme 1). These reactions are highly regio- and the formation of sila- and germacyclobutene deriva-
stereoselective with the aluminium and gallium atoms tives by 1,1-carbametallation [3, 5] (Scheme 1). The
in the products exclusively localised in a geminal po- obtained heterocycles show an interesting fluorescence
sition to silicon or germanium and a cis-arrangement behaviour upon irradiation with UV light. Correspond-
of the metal and vinylic hydrogen atoms across the re- ing 1,1-carbaboration reactions have been observed
sulting C=C double bonds as the kinetically favoured for similar boron compounds by the group of Wrack-
orientation [9]. Rearrangement to yield the thermody- meyer [10 – 18]. Hydroalumination or hydrogallation
namically favoured trans-products has been observed of two C≡C triple bonds of the oligoalkynylsilanes and
only for very few compounds with relatively small -germanes has afforded compounds with two unsatu-
alkyl groups attached to the metal atoms [1]. As rated aluminium or gallium atoms in a single molecule
a particularly interesting structural motif these alkenyl- which proved to be effective chelating Lewis acids and
alkynyl derivatives exhibit an intramolecular interac- coordinated halide atoms in a chelating fashion [4, 5]
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1334
W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
C6H5, p-C6H4-Me (p-Tol)) with n-BuLi at –78◦C af-
forded the corresponding lithium alkynides which in
situ were reacted with the appropriate element halides
R4−nECln (E = Si, Ge) to generate the alkynylelement
compounds by salt elimination. Only the preparation
of the pentafluorophenylgermanium compound 7 re-
quired a different strategy to avoid problems associated
with the synthesis and purity of the (F5C6)2ECl2 or
Cl2E(C≡C-R0)2 precursors due to non-stoichiometric
reactions and the formation of inseparable mixtures of
(F5C6)4−nECln or Cl4−nE(C≡C-R0)n (n = 0 – 4). Mak-
ing use of an amine protecting group was found to min-
imize these problems [7]. GeCl4 was therefore treated
with two equivalents of LiNEt2 to give Cl2Ge(NEt2)2
which was reacted with Me3C–C≡C–Li to yield the
dialkynylgermane (Et2N)2Ge(C≡C–CMe3)2. The lat-
Scheme 1. Hydrometallation of dialkynylsilanes and
-germanes: alkenyl-alkynyl compounds, cyclisation and
chelating Lewis acid (E = Si, Ge; M = Al, Ga).
ter was deprotected with HCl to afford Cl2Ge(C≡C–
CMe3)2 which in the final step was converted with in
situ-formed F5C6Li to (F5C6)2Ge(C≡C–CMe3)2 (7) in
54% yield (Eq. 2).
(Scheme 1). Functionalisation of the alkynylsilanes
and -germanes by Lewis-basic amino groups or halo-
gen atoms resulted after hydrometallation in strong in-
tramolecular Al–X or Ga–X interactions which by ac-
tivation of Si–X or Ge–X bonds allowed the obser-
vation of interesting secondary reactions [19 – 21]. In
this article we report on the continuation of our sys-
tematic studies in this field. In particular we were in-
terested in the electronic influence of the substituents
attached to silicon or germanium on the strength of
the intramolecular M···C interactions and replaced,
for instance, phenyl by strong electron-withdrawing
pentafluorophenyl groups. We further used a silane
with a bulky mesityl group to study the influence of
steric interactions on structure, spectroscopic proper-
ties and reactivity, since secondary reactions such as
cyclisation or the hypothetical release of dialkylele-
ment alkynides strongly depend on the substituents.
These studies are crucial for a concise understanding
of the unique properties of these highly important new
classes of compounds.
+nBuLi
R0−C≡C−H −−−−→ R0−C≡CLi
(1)
0
+nR −C≡CLi
R4−nECln −−−−−−−−→ R4−nE(C≡C−R0)n
1−6
1, R = Ph, E = Si, R0 = CMe3, n = 2
2, R = Mes, E = Si, R0 = CMe3, n = 3
3, R = Me, E = Si, R0 = pTol, n = 3 [6]
4, R = Ph, E = Ge, R0 = CMe3, n = 2 [7]
5, R = Ph, E = Ge, R0 = Ph, n = 2 [2]
6, E = Ge, R0 = CMe3, n = 4
GeCl4 +2LiNEt2 −−−−→ Cl2Ge(NEt2)2
−2LiCl
2Me C−C≡CLi
3
−−−−−−−−−→ (Et2N)2Ge(C≡C−CMe3)2
−2LiCl
(2)
4HCl/Et O
2
−−−−−−−−→ Cl2Ge(C≡C−CMe3)2
−2[Et NH ]Cl
2
2
2F C Li
5
6
−−−−−→ (F5C6)2Ge(C≡C−CMe3)2
−2LiCl
7
Results and Discussion
The hydrometallation of these alkynylsilanes and -ger-
manes proceeded as expected and followed the previ-
The alkynylsilanes and -germanes R2Si(C≡C-R0)2, ously established rules in terms of reactivity and selec-
R-Si(C≡C-R0)3, R2Ge(C≡C-R0)2, and Ge(C≡C-R0)4 tivity. Stirring one equivalent of the metal hydride H–
(1 to 6; Eq. 1) were synthesised conveniently following MR00 (M = Al, Ga; R00 = CMe3, CH2CHMe2) with
2
standard literature procedures [7, 22 – 26]. The lithia- the alkynylsilanes or -germanes 1 to 7 at room tem-
tion of the terminal alkynes R0-C≡C–H (R0 = CMe3, perature in toluene or n-hexane (synthesis of 10) be-
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W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
1335
tween 30 min and 12 h yielded the corresponding 1 : 1 adopts the trans-configuration is bonded to a coordina-
addition products 8 to 13 (E = Si, Ge) in yields above tively unsaturated metal atom.
63% [(i) in Eqs. 3 and 4]. The addition was in all in-
stances strictly regioselective with the electropositive
metal atom binding exclusively to the negatively po-
larised alkenyl C atom attached to silicon or germa-
nium and stereospecific with a cis arrangement of the
metal and H atoms in the resulting olefin substituents.
No rearrangement of the kinetically favoured cis ad-
dition products to the thermodynamically favoured
trans products was observed. There is a short con-
tact between the metal atom and the α-C atom of
an unreacted alkynyl substituent (see discussion be-
low) which as a consequence becomes unavailable
for the bimolecular transition state required for the
cis/trans isomerisation [9]. The 1 : 2 addition prod-
ucts 14 to 19 [(ii) in Eqs. 3 and 4] were obtained
in a similar fashion from the corresponding element
alkynide and two equivalents of H–M(CMe3)2. The
reactions of a second equivalent of metal hydride re-
quired, with the exception of 18, much longer reaction
times (3 – 20 days) to reach completion and in some in-
stances repeated fractional recrystallisation to remove
small quantities of the 1 : 1 addition products. Warm-
ing of the solutions to accelerate the transformations
resulted in decomposition with the formation of in-
separable mixtures of unknown components. The dual
hydroalumination of Ph2Si(C≡C–CMe3)2, Si(C≡C–
CMe3)4 and Ph2Ge(C≡C-Ph)2 was not successful. In
case of Ph2Si(C≡C–CMe3)2 a mixture of the 1 : 1 (8)
and 1 : 2 addition products (14) was obtained that could
not be separated into its components. 14 was, how-
(3)
1
ever, identified unequivocally in the H NMR spec-
trum by comparison with the spectra of the analyti-
cally pure compounds 8 and 15. The reactions were
again regiospecific (geminal arrangement of Si/Ge and
Al/Ga) and stereoselective (cis-addition) as discussed
for the mono-addition products 8 to 13. Only in case of
the dialkenyl-alkynylsilicon compound 19 one of the
alkenyl groups showed a spontaneous rearrangement
to yield the thermodynamically favoured trans-product
with the metal and the H atom on different sides of the
C=C bond. The stereoselectivity (cis) is again influ-
enced by an interaction between the Ga and α-C atom
of the remaining alkynyl moiety in the cases of com- The molecular structures of the bisalkynes 2 and 7
pounds 18 and 19 or a similar interaction between the are shown in Figs. 1 and 2. The Group 14 element is
metal atoms and one or more carbon atoms or C–H coordinated in a distorted tetrahedral fashion, bond
bonds of phenyl substituents in compounds 14 to 17. lengths and angles are unexceptional (C≡C 118.4(3)
Interestingly, the alkenyl group of compound 19 that to 120.1(2) pm; Table 1). Representative examples of
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1336
W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
(4)
Fig. 1. Molecular structure in the crystal and atomic num-
bering scheme of compound 2. Displacement ellipsoids are
drawn at the 40% level. Hydrogen atoms have been omitted
for clarity.
the molecular structures of the 1 : 1 addition products
8 to 13 are shown in Figs. 3 and 4. The key feature of
the structures is a short distance between the coordina-
tively unsaturated metal atoms and the α-C atoms of
one alkynyl substituent with average M···C distances
of about 250 pm in the case of Al and 270 pm in the
case of Ga. The significance of these interactions be-
comes evident from the formation of essentially planar
four-membered M-Cvinyl-E-Cethynyl heterocycles with
the respective torsion angles between 0 and 9◦ (Ta-
ble 1). The atoms of the associated alkyne and alkene
Fig. 2. Molecular structure in the crystal and atomic num-
bering scheme of compound 7. Displacement ellipsoids are
drawn at the 40% level. Hydrogen atoms have been omitted
for clarity.
substituents are in the same plane, and the MR00 and marginally longer than in the alkynylelement starting
2
ER2 groups adopt a perpendicular arrangement to this materials. It is noteworthy that there is no significant
plane. Another consequence of the M···Cα ≡C interac- difference between the bond lengths of the coordinated
tion is a pyramidalisation of the coordination sphere and the “free” alkyne in 12, while in the case of 13
of the metal atoms as evident from a 23 – 37 pm devi- there is a small lengthening [120.1(2) versus 121.7(2)]
ation from the planes defined by the directly bonded which is associated with the shortest M··· Cα ≡C con-
carbon atoms (Table 1). There is only little influence tact (244.9 pm) and the largest deviation from planarity
on the lengths of the C≡C triple bonds which are only (37 pm) in the presented series of compounds.
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W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
Table 1. Selected structural parameters (pm, deg) of compounds 2, 7–13 and 15–18.
1337
Compound
C≡C
C=C
M···C≡C (Ph)a
Torsion angle
M–C(=)–El–Cα
d (M···C3)c
b
2
7
119.6(2)/120.1(2)/119.8(2)
–
–
–
–
–
–
–
–
118.4(3)/118.9(3)
8 (M = Al)
9 (M = Ga)
10 (M = Ga)
11 (M = Al)
12 (M = Al)
13 (M = Al)
15 (M = Ga)
16 (M = Ga)
17 (M = Ga)
18 (M = Ga)
120.6(2)
120.6(2)
119.8(3)
120.7(2)
133.9(2)
134.1(2)
134.1(3)
133.4(2)
133.7(2)
134.2(2)
249.5
271.1
264.5
251.2
253.1
244.9
7.15(7)
8.47(7)
0.12(2)
8.3(1)
4.92(8)
5.22(6)
32
24
25
36
23
37
24/25
22/22
21/28
26/26
120.3(2)/120.6(2)
120.1(2)/121.7(2)
–
–
–
134.9(2)/134.6(1)
133.9(3)/133.7(3)
135.3(2)/135.2(2)
133.2(4)/134.2(4)
278.1/285.0a
287.8/290.4a
276.8/290.7a
281.0/284.5
18.4(1)/19.0(1)
15.3(2)/13.4(2)
18.7(1)/11.4(1)
9.3(2)/10.0(3)
120.0(4)/120.0(4)
a
Shortest Ga–Cortho(Ph) contacts; b absolute values, sign ignored; Cα is the α-C atom of an ethynyl group or the ipso-C atom of a phenyl
group; c deviation of M from the average plane of the directly connected carbon atoms.
Fig. 4. Molecular structure in the crystal and atomic num-
bering scheme of compound 13. Displacement ellipsoids are
drawn at the 40% level. Hydrogen atoms (except H7, arbi-
trary radius) have been omitted for clarity.
Fig. 3. Molecular structure in the crystal and atomic num-
bering scheme of compound 11. Displacement ellipsoids are
ular to each other. In the absence of uncoordinated
drawn at the 40% level. Hydrogen atoms (except H22, arbi-
“free” alkynyl substituents the short Ga···Cα ≡C con-
trary radius) have been omitted for clarity.
tacts are replaced in compounds 15, 16 and 17 by
interactions between the metal atom and the ortho-C
Representative diagrams of the four 1 : 2 addi- atoms (277 – 291 pm) and to a lesser degree the ipso-
tion products which were crystallographically char- C atoms (310 – 328 pm) of the adjacent phenyl sub-
acterised are shown in Fig. 5 (17) and 6 (18). The stituents leading to two nearly planar Ga-Cvinyl-E-Cipso
molecular structure of the dialkenyldialkynylgerma- heterocycles that are perpendicular to each other. The
nium compound 18 shows the same features as the phenyl substituents are rotated towards the Ga atoms
already discussed 1 : 1 addition products. There are to minimise the Ga-Cortho distance. This interaction
two relatively short Ga···Cα ≡C distances (281 and is also associated with a deviation from planarity for
285 pm) resulting in two essentially planar Ga-Cvinyl
-
the Ga atoms as observed in the above discussed com-
Ge-Cα heterocycles that are approximately perpendic- pounds (see Table 1).
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1338
W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
are further connected to an infinite chain by an inter-
action between the m-H atom of one dimer with o-, m-
and p-C atoms [GePh, 288, 277, 282 pm].
The spectroscopic characterisation is consistent
with the results of the crystal structure determinations.
Selected IR- and NMR-spectroscopic parameters are
summarised in Table 2. In accordance with a few pre-
viously reported observations [19] the crystallograph-
ically detected M···Cα ≡C contacts in the hydrometal-
lation products 8 to 13 and 19 correlate to a lowering
of the ν(C≡C) stretching frequency in the IR spec-
trum by 30 – 50 cm−1 (Table 2) relative to the “free”
alkynes 1 to 7. In compounds 12 and 13 we found
three νC≡C stretching vibrations covering the entire
range observed for coordinated and free ethynyl groups
(2200 to 2120 cm−1) which obviously reflect the struc-
Fig. 5. Molecular structure in the crystal and atomic num-
bering scheme of compound 17. Displacement ellipsoids are
drawn at the 40% level. Hydrogen atoms (except H12 and
H22, arbitrary radii) have been omitted for clarity.
tural speciality with the presence of “free” and coordi-
nated alkynyl groups in a single molecule.
1
In the H NMR spectra all hydrometallation prod-
ucts 8 to 19 showed a characteristic signal in the region
of 6.4 – 8.3 ppm for the olefinic hydrogen atoms, and in
case of the silicon compounds 3JSiH coupling constants
> 24 Hz were observed. Coupling constants > 20 Hz
have been shown to be characteristic of cis isomers (Al
and H on the same side, Si and H on different sides of
the C=C bond), while constants < 15 Hz are indica-
tive of the trans isomer [9]. Only in case of the 1 : 2
addition product 19 there is one of the two coupling
constants < 15 Hz, and the corresponding alkene sub-
stituent was consequently identified as the thermody-
namically favoured trans isomer. Although we do not
have direct evidence by crystal structure determination
in this case these findings verify unambiguously the
unique molecular structure of 19. One alkenyl group
has the kinetically preferred cis-arrangement of Ga and
H atoms while the second one adopted the thermody-
namically favoured trans-configuration.
Fig. 6. Molecular structure in the crystal and atomic num-
bering scheme of compound 18. Displacement ellipsoids are
drawn at the 40% level. Hydrogen atoms (except H32 and
H42, arbitrary radii) have been omitted for clarity.
The chemical shifts of the CMe3 groups in the
1H NMR spectra of compounds 8, 9, 11, 12, 13,
and 18 followed the sequence δ(MCMe3) > δ(C≡C–
The crystal structures of all compounds with phenyl CMe3) ≥ δ(C=C–CMe3) (Table 2). The low-field
substituents feature intermolecular C–H···π interac- shift of the MCMe3 group (δ = 1.3 – 1.4 ppm) may
tions [27 – 29] that lead to the formation of loosely be a consequence of the higher coordination num-
bonded dimers with short m-H···m-C [287 pm (8); ber of the metal atoms as a result of the discussed
285 pm (9)], m-H···m-C [CHPh, 282 pm (10)], m- M···Cα ≡C interaction. In compounds 15 to 17 that
H···o-C [289 pm (15)] or m-H···centroid contacts do not have such an interaction the trend was re-
[277 pm (16)] or alternatively the formation of a chain versed, and δ(MCMe3) was shifted to higher field (δ
structure with short m-H···o-C and m-H···ipso-C con- = 1.03 – 1.06 ppm). For the mixed cis/trans compound
tacts [266, 285 pm (17)]. The dimers of compound 15 19 we observe resonances in two different ranges (δ
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W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
Table 2. Selected spectroscopic parameters of compounds 1–13 and 15–19.
1339
Compound
C=CH
(1H, δ)
3JSiH
(Hz)
C≡C–R
C≡C–R
CMe3
CMe3
ν(C≡C)
(
13C, δ)
(
13C, δ)
(
13C, δ)a
(1H, δ)a
(IR, cm−1
)
1
2
3 [6]
4 [7]
5 [2]
6
7
8
9
10
11
12
13
15
16
17
18
19
–
–
–
–
–
–
77.6
80.4
88.4
76.1
87.8
75.8
72.8
81.7
81.3
93.0
77.7
83.7
82.9
–
119.8
116.9
107.5
117.7
107.9
114.3
118.2
131.6
122.4
110.0
n. o.
122.2
123.9
–
–
–
–/28.6/–
–/28.5/–
1.11
1.07
–
1.13
–
2201, 2156
2201, 2158, 2125
2214, 2160, 2126
2181, 2147
2162
2187, 2153, 2126
2195, 2160
2154, 2114
2156, 2127
2154, 2132
2193, 2158, 2120
2196, 2156, 2116
2197, 2156, 2126
–
–
–/28.5/–
–
–
–
7.35
6.84
7.94
6.94
6.95
6.99
6.43
6.46
7.63
6.49
–
–
–
27.8
25.1
–
–
–/28.3/–
–/28.6/–
1.04
1.14
39.9/29.4/19.0
39.8/28.8/29.4
–/–/29.5
40.4/29.0/17.8
39.6/28.9/27.0b
40.3/29.0/18.7
39.2/–/30.2
38.8/–/30.1
–/–/30.4
1.01/1.05/1.33
1.10/1.15/1.29
–/–/1.38
1.02/1.14/1.21
1.09/1.13/–b
1.09/1.23/1.43
1.33/–/1.03
1.31/–/1.04
–/–/1.06
1.21/1.17/1.44
–/–/1.36, 1.13
–/–/1.47
–
29.8
30.4
24.2
–
–
–
–
–
84.7
93.6
–
–
119.5
111.5
38.4/28.8/29.2
–/–/29.0, 28.8
–/–/29.2
2160, 2131
2147, 2133
8.33 (trans)
7.98 (cis)
<13
24.3
a
Sequence: C=C–CMe3/C≡C–CMe3/MCMe3; b AlCH2CHMe2.
= 1.47 and 1.25(av) ppm) which in accordance with Ga(CMe3)2 groups broadened, then disappeared in the
the above assignment may be interpreted in terms base line at a coalescence temperature of 270 K and
of the presence of four-coordinated (δ = 1.47; Ga– on further cooling split into two well-defined singlets
Cα interaction; cis-alkenyl) and three-coordinated Ga at 1.27 and 0.88 ppm. Similarly the doublet for the o-
atoms (trans-alken). The quaternary carbon atoms of H atoms broadened and disappeared in the baseline at
the CMe3 substituents were found to have very simi- 210 K. This behaviour is consistent with a hindered ro-
lar chemical shifts in the 13C NMR spectra, around δ tation at lower temperature due to the Ga···o-C interac-
= 40 ppm for C=C–CMe3 and δ = 29 ppm for C≡C– tion that was observed in the solid state. Based on the
CMe3 and GaCMe3. The more electron-rich AlCMe3 NMR data the activation barrier for the rotation was es-
carbon atoms were observed at about δ = 18 ppm.
timated to ∆G# = 53 kJ mol−1 [30] which is very simi-
The M(CMe3)2 and EAr2 groups in the 1 : 1 addi- lar to values reported for M···Cα ≡C interactions in the
tion products were found to be magnetically equiva- literature (54 kJ mol−1) [6].
lent in solution which is in accordance with the molec-
ular symmetry and an almost planar four-membered Conclusion
heterocycle. In case of compound 19 the CMe3 sub-
stituents of the Ga(CMe3)2 group trans to H were
Hydroalumination and hydrogallation of oligo-
found to be magnetically inequivalent at room tem- alkynylsilanes and -germanes with dialkylmetal hy-
1
perature in the H and 13C NMR spectra which may drides afforded either alkenyl-alkynyl- or dialkenyl
be caused by the cis-arrangement of the bulky sub- compounds depending on the stoichiometric ratio of
stituents and a comparatively high barrier of rotation. the starting compounds. It is interesting to note that
The Al and Ga analogues of 19 with phenyl instead despite the larger polarity of Al–H compared to Ga–
of tolyl substituents showed similar NMR data [6]. H bonds dual hydroalumination was not successful in
To study the influence of temperature on the solution most cases, while dual hydrogallation resulted in the
behaviour of the 1 : 2 adducts the NMR spectra of formation of dialkenyl compounds after relatively long
compound 17 were recorded at variable temperatures. reaction times. The different behaviour may reflect the
When a sample of 17 in toluene was slowly cooled relatively strong Al–H–Al three-centre bonds in usu-
to 210 K, the singlet for the magnetically equivalent ally oligomeric dialkylaluminium hydrides which re-
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1340
W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
sults in a lower reactivity in hydrometallation reac- mesityl groups in 12 and 13 seem also not to have
tions. The results reported in this article allow a sys- a measurable influence. From these results it may be
tematic interpretation of some interesting spectro- concluded that the substituents at the central silicon or
scopic findings. The difference of the chemical shifts germanium atoms do not influence the properties of
between both ethynyl carbon atoms in the 13C NMR these highly functionalised compounds significantly
spectra is a measure for the polarity of the triple bonds. (see for comparison our results with alkyl-substituted
In the case of the alkenyl-alkynyl derivatives it depends silanes or germanes [1, 2]). In contrast the metal
essentially on the substituents attached to the β-carbon atoms (Al versus Ga) and the terminal substituents
atoms. For tert-butyl groups there is a large differ- of the alkynyl groups are important for the prediction
ence between the shifts of both carbon atoms of 39 to of specific properties and the course of secondary
50 ppm, while phenyl or p-tolyl groups lead to much reactions such as the thermal rearrangement to yield
smaller differences of only about 18 ppm. A compari- heterocyclic compounds.
son between 8 and 9 suggests that the presence of alu-
minium atoms result in a higher polarity of the ethynyl Experimental Section
group. A second alkynyl group attached to the cen-
tral Si or Ge atoms does not seem to influence these
All procedures were carried out under an atmosphere
of purified argon in dried solvents (n-hexane, c-pentane
data significantly. Similar observations were made for
the alkenyl groups of these mixed-substituted com-
pounds (∆δ = 25 to 35 ppm versus about 2 ppm). In-
and n-pentane with LiAlH4; Et2O and toluene with
Na/benzophenone; 1,2 difluorobenzene and pentafluoroben-
zene with molecular sieves). NMR spectra were recorded
terestingly the chemical shift differences of those di- in C6D6 at ambient probe temperature or C7D8 for vari-
able temperature studies (15) using the following Bruker
instruments: Avance I (1H, 400.13; 13C, 100.62; 29Si,
79.49 MHz) or Avance III (1H, 400.03; 13C, 100.59; 29Si
79.47 MHz) and referenced internally to residual solvent
resonances (chemical shift data in δ). 13C NMR spec-
tra were all proton-decoupled. IR spectra were recorded
of Nujol mulls between CsI plates on a Shimadzu Pres-
tige 21 spectrometer. HAl(CMe3)2 [31], HGa(CMe3)2 [31],
Mes-SiCl3 [32], Cl2Ge(C≡C–CMe3)2 [7], Ph2Ge(C≡C–
CMe3)2 [7], Ph2Ge(C≡C-Ph)2 [2, 22, 23], Me-Si(C≡C-
C7H7)3 [6], and Ge(C≡C–CMe3)4 [24] were obtained ac-
cording to literature procedures. Commercially available
HAl(CH2CHMe2)2, Me3C–C≡C–H, F5C6Br and n-BuLi
(1.6 M in n-hexane) were used without further purification.
The assignment of NMR spectra is based on HMBC, HSQC
and DEPT135 data.
alkenyl compounds (14 to 18) which do not have an
unreacted alkynyl unit are in a narrow range between 9
and 12 ppm and do not show a correlation to the sub-
stituents in β-position. The pentafluorophenyl group of
11 does not affect the NMR spectroscopic data signif-
icantly. But in the starting dialkynyl compound 7 we
observed the largest difference ∆δ between both car-
bon atoms of an ethynyl group (∆δ = 45.4 ppm) which
may reflect a slightly increased polarity of these bonds
induced by the electron-withdrawing group.
The molecular structures of the alkenyl-
alkynylsilanes and -germanes exhibit a bonding
interaction between the coordinatively unsaturated
aluminium and gallium atoms and the α-carbon atoms
of the unreacted ethynyl groups. Independently of the
central atom (Si or Ge) relatively close intramolecular
contacts are observed for the aluminium compounds
(245 to 253 pm) while longer ones result with gallium
(265 to 271 pm). This behaviour reflects the different
Lewis acidity of the metal atoms. In the absence of
unreacted alkynyl groups aluminium and gallium
atoms reach coordinative saturation by interactions
with aryl (15 to 17) (see also [19]) or, as reported
only recently, tert-butyl groups [19, 20]. Once again
the electron-withdrawing pentafluorophenyl group
in 11 does not significantly influence the structural
properties. Only in the starting compound 7 we
observed relatively short C≡C bonds which may be
Ph2Si(C≡C–CMe3)2 (1) [25, 26]
A solution of n-BuLi (40.0 mL, 64.0 mmol, 1.6 M in
n-hexane) was added dropwise at −78 ◦C over a period
of 1 h to a solution of Me3C–C≡C–H (5.24 g, 7.85 mL,
64.0 mmol) in Et2O (45 mL). The mixture was stirred for
2 h at this temperature and then allowed to warm to room
temperature overnight. The yellow solution was then treated
with Ph2SiCl2 (8.91 g, 7.40 mL, 35.2 mmol) at −78 ◦C over
a period of 90 min. The mixture was stirred for 2 h at the
same temperature and then allowed to warm to room tem-
perature overnight. The mixture was filtered, and the residue
was washed with n-hexane (20 mL). The solvent of the com-
bined filtrates was removed in vacuo. The solid residue
caused by a slightly increased charge separation. The was dissolved in a small quantity of n-pentane. Cooling to
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W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
1341
−30 ◦C gave Ph2Si(C≡C–CMe3)2 (1) as a colourless, air- EI; 30 eV; 323 K): m/z (%) = 390 (67) [M]+, 375 (11) [M–
stable solid. Spectroscopic data of the previously reported Me]+, 333 (100) [M–CMe3]+.
compound [6, 7] are incomplete, and for reasons of com-
Ge(C≡C–CMe3)4 (6) [24]
parison we have therefore included a full characterisation.
Yield: 8.72 g (79%); m. p. (argon, sealed capillary): 86◦C.
Preliminary data of Ge(C≡C–CMe3)4 (6) have been pub-
lished previously [5]. We modified the synthetic procedure
and conducted a complete characterisation. n-BuLi (1.6 M
in n-hexane) was added slowly to a solution of equimolar
quantities of Me3C–C≡CH in 100 mL of Et2O at −78 ◦C.
The reaction mixture was stirred for 2 h at this tempera-
ture, and a solution of GeCl4 (25 mol %) in Et2O (50 mL)
was added dropwise. The mixture was stirred for 2 h at this
temperature, the cooling bath was removed, and the sus-
pension was stirred at room temperature overnight. Inor-
ganic salts were dissolved in aqueous HCl (10%), the or-
ganic phase was separated and the aqueous phase was ex-
tracted three times with Et2O (20 mL). The combined or-
ganic phases were dried over MgSO4. After filtration the sol-
vent was removed in vacuo. Recrystallisation of the residue
from n-pentane at −30 ◦C yielded 6 as a colourless solid
(83%); m. p. (argon, sealed capillary): 175◦C. – IR (CsI,
paraffin): ν = 2187 s, 2153 s, 2126 w ν(C≡C); 1462 vs,
1375 vs (paraffin); 1302 w, 1252 vs δ(CH3); 1204 m, 1169
vw, 1153 vw, 1101 vw, 1084 vw, 1028 w, 968 vw, 922
s, 889 vw, 847 vw, 752 vs [δ(CH), ν(CC)]; 723 s (paraf-
fin); 552 vw, 492 s cm−1 [ν(GeC), δ(CC)]. – 1H NMR
(400.03 MHz, C6D6): δ = 1.04 ppm (s, 36 H, CMe3). –
13C NMR (100.6 MHz, C6D6): δ = 114.3 (C≡C–CMe3),
75.8 (C≡C–CMe3), 30.5 (C≡C–CMe3), 28.3 ppm (C≡C–
CMe3). – MS ((+)-EI; 30 eV; 323 K): m/z (%) = 397 (8)
[M–H]+, 383 (100) [M–Me]+, 341 (28) [M–CMe3]+, 317
(39) [M–CCCMe3]+. – C24H36Ge (397.1): calcd. C 72.6, H
9.1; found C 72.0, H 9.2.
– IR (CsI, paraffin): ν = 2201 s, 2156 vs ν(C≡C); 1979 w,
1958 w, 1910 w, 1888 m, 1832 w, 1819 m, 1771 w, 1661
w, 1620 vw, 1614 vw, 1589 s, 1566 w , 1557 vw (phenyl);
1454 vs, 1377 vs (paraffin); 1362 vs, 1321 vw, 1304 m, 1254
s δ(CH3); 1200 s, 1188 m, 1109 s, 1026 m, 997 s, 945 vs,
933 vs, 853 vw, 775 vs, 765 vs, 738 vs [δ(CH), ν(CC)];
712 vs (paraffin); 696 vs δ(Ph); 621 m, 583 vs, 563 vs,
544 vs, 494 vs, 455 s, 413 s cm−1 [ν(SiC), δ(CC)]. – 1H
NMR (400.13 MHz, C6D6): δ = 8.07 (d, 3JHH = 7.7 Hz, 4
3
H, o-H), 7.23 (pseudo-t, JHH = 7.7 Hz, 4 H,m-H), 7.16 (t,
3JHH = 7.7 Hz, 2 H,p-H), 1.11 ppm (s, 18 H, CMe3). – 13
C
NMR (100.6 MHz, C6D6): δ = 135.2 (o-C), 135.1 (ipso-
C), 130.2 (p-C), 128.3 (m-C), 119.8 (C≡C–CMe3), 77.6
(C≡C–CMe3), 30.6 (CMe3), 28.6 ppm (CMe3). – 29Si NMR
(79.49 MHz, C6D6): δ = −48.6 ppm. – MS ((+)-EI; 20 eV;
298 K): m/z (%) = 344 (33) [M]+, 329 (6) [M–CH3]+, 287
(100) [M–CMe3]+. – C24H28Si (344.1): calcd. C 83.8, H 8.2;
found C 83.4, H 8.2.
Mes-Si(C≡C–CMe3)3 (2)
n-BuLi (9.6 mL, 15.4 mmol, 1.6 M in n-hexane) was
added dropwise over a period of 15 min to a solution of
Me3C–C≡C–H (1.26 g, 15.4 mmol) in Et2O (50 mL) at
−78 ◦C. The mixture was allowed to warm to room temper-
ature overnight and added dropwise over a period of 20 min
to a solution of Mes-SiCl3 (1.29 g, 5.12 mmol) at −78 ◦C.
The mixture was stirred for 1 h at this temperature, allowed
to warm to room temperature and stirred overnight. Inor-
ganic salts were dissolved in aqueous HCl (10%), the or-
ganic phase was separated, and the aqueous phase was ex-
tracted three times with Et2O (20 mL). The combined or-
(F5C6)2Ge(C≡C–CMe3)2 (7)
n-BuLi (4.1 mL, 6.56 mmol, 1.6 M in n-hexane) was
ganic phases were dried over MgSO4 and filtered. The sol- added dropwise over a period of 5 min to a solution of
vent was removed in vacuo. Recrystallisation of the residue F5C6Br (1.62 g, 6.56 mmol) in Et2O (50 mL) at −78 ◦C. The
from c-pentane at −15 ◦C yielded 2 as a colourless solid mixture was stirred for 1 h at −78 ◦C. During this period the
(1.94 g, 97%); m. p. (argon, sealed capillary): 108◦C. – IR temperature must not exceed −50 ◦C to prevent elimination
(CsI, paraffin): ν = 2201 m, 2158 s, 2125 sh ν(C≡C); 1605 of LiF and the formation of explosive tetrafluorobenzyne.
m, 1578 m, 1555 w [ν(C=C), mesityl]; 1448 vs, 1375 vs A solution of Cl2Ge(C≡C–CMe3)2 [7] (1.00 g, 3.28 mmol)
(paraffin); 1304 w, 1254 m δ(CH3); 1202 m, 1153 w, 1109 in Et2O was then added over a period of 20 min at −78 ◦C.
w, 1070 m, 1028 m, 943 s, 889 w, 849 s, 773 s, 762 m [δ(CH), The reaction mixture was allowed to warm to room temper-
ν(CC)]; 721 s (paraffin); 687 w, 625 m, 584 m, 507 w, 435 m ature and stirred for 5 h. HCl (50 mL, 10%) was added, the
cm−1 [ν(SiC), δ(CC)]. – 1H NMR (400.03 MHz, C6D6): δ
aqueous phase was separated and extracted three times with
= 6.78 (s, 2 H, m-H), 3.01 (s, 6 H, o-Me), 2.09 (s, 3 H, p-Me), Et2O (50 mL). The combined organic phases were dried over
1.07 ppm (s, 27 H, CMe3). – 13C NMR (100.6 MHz, C6D6): MgSO4 and filtered. The solvent of the filtrate was removed
δ = 145.4 (o-C), 139.7 (p-C), 129.9 (m-C), 127.1 (ipso- in vacuo. Recrystallisation from n-pentane at −30 ◦C yielded
C), 116.9 (C≡C–CMe3), 80.4 (C≡C–CMe3), 30.3 (CMe3), compound 7 as a colourless oil (1.00 g, 54%). – IR (CsI,
28.5 (CMe3), 25.0 (o-Me), 21.1 ppm (p-Me). – MS ((+)- paraffin): ν = 2195 vs, 2160 vs ν(C≡C); 1957 vw, 1870
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W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
vw, 1724 w, 1699 vw, 1644 vs, 1634 vs, 1603 m, 1586 s, Ph2Si(C≡C–CMe3){C[Ga(CMe3)2]=CH–CMe3} (9)
1549 s, 1516 vs, [ν(C=C, aromatic ring]; 1471 vs (paraf-
Solid Ph2Si(C≡C–CMe3)2 (1) (0.383 g, 1.11 mmol) was
added to a solution of HGa(CMe3)2 (0.216 g, 1.17 mmol)
in toluene (25 mL) at room temperature. The mixture was
stirred for 30 min, and all volatiles were removed in vacuo.
The colourless residue was dissolved in 1,2-difluorobenzene
(12 mL). After filtration the filtrate was concentrated and
cooled to −15 ◦C to yield compound 9 as a colourless solid
(0.42 g, 71%); m. p. (argon, sealed capillary): 105◦C. – IR
(CsI, paraffin): ν = 2156 m, 2127 m ν(C≡C); 1969 vw,
1956 vw, 1898 vw, 1883 vw, 1819 w, 1655 vw, 1595 m,
1560 m, 1508 w [ν(C=C), phenyl]; 1458 vs, 1375 vs (paraf-
fin); 1300 w, 1252 m δ(CH3); 1198 m, 1169 w, 1155 w,
1109 s, 1013 w, 999 w, 986 vw, 972 vw, 937 w, 918 m,
901 w, 887 m, 851 vw, 806 m, 793 w, 758 w, 739 s [δ(CH),
ν(CC)]; 708 vs (paraffin); 648 m (phenyl); 619 w, 556 m,
546 s sh, 527 vs, 486 s, 469 m, 449 s cm−1 [ν(SiC), ν(GaC),
δ(CC)]. – 1H NMR (400.03 MHz, C6D6): δ = 7.96 (d, 3JHH
fin); 1419 m δ(CH3); 1385 vs (paraffin); 1364 vs, 1344 m;
1288 vs ν(CF); 1255 vs δ(CH3); 1205 s, 1143 s; 1086 vs,
1046 m, 1017 s, 974 vs, 927 s, 818 s, 756 vs [δ(CH), ν(CC),
ν(CF)]; 724 s (paraffin); 696 vw, 687 vw, 679 vw, 622 s,
583 m, 554 vw, 496 s, 485 s cm−1 [ν(SiC), δ(CC)]. – 1H
NMR (400.13 MHz, C6D6): δ = 1.14 (s, 18 H, CMe3). – 13
C
NMR (100.6 MHz, C6D6): δ = 148.8 (dm, 1JFC = 246 Hz,
1
1
o-C), 143.1 (dm, JFC = 256 Hz, p-C), 137.7 (dm, JFC
=
253 Hz, m-C), 118.2 (C≡C–CMe3), 106.8 (m, ipso-C), 72.8
(C≡C–CMe3), 30.2 (CMe3), 28.6 ppm (CMe3). – 19F NMR
(376.4 MHz, C6D6). δ = −127.6 (m, 4 F, o-F), −149.3 (tt,
3JFF = 20.7 Hz, 4JFF = 4.1 Hz, 2 F, p-F), −160.1 ppm (m,
4 F, m-F). – MS ((+)-EI; 20 eV; 353 K): m/z (%) = 570 (5)
[M]+, 555 (15) [M–CH3]+, 513 (8) [M–CMe3]+, 489 (7)
[M–CCCMe3]+, 403 (9) [M–C6F5]+.
Ph2Si(C≡C–CMe3){C[Al(CMe3)2]=CH–CMe3} (8)
3
= 7.2 Hz, 4 H, o-H), 7.22 (pseudo-t, JHH = 7.4 Hz, 4 H,
3
m-H), 7.13 (t, JHH = 7.5 Hz, 2 H, p-H), 6.84 (s, 1 H,
Solid Ph2Si(C≡C–CMe3)2 (1) (1.09 g, 3.17 mmol) was
added to a solution of HAl(CMe3)2 (0.474 g, 3.34 mmol)
in toluene (50 mL) at room temperature. The mixture was
stirred for 30 min, and all volatiles were removed in vacuo.
The colourless residue was dissolved in a small quantity
of 1,2-difluorobenzene, the solution was concentrated and
cooled to −15 ◦C to yield compound 8 as a colourless solid
(1.27 g, 82%); m. p. (argon, sealed capillary): 117◦C. – IR
(CsI, paraffin): ν = 2154 m, 2114 s ν(C≡C); 1971 w, 1956
w, 1900 vw, 1884 w, 1819 w, 1769 vw, 1694 vw, 1657 vw,
1599 s, 1568 s, 1557 m, 1504 w ν(C=C), phenyl; 1454
vs (paraffin), 1377 vs (paraffin); 1366 vs, 1302 w, 1254 s
δ(CH3); 1244 s, 1198 s, 1188 m, 1155 w, 1107 vs, 1065
vw, 1028 w, 1007 m, 997 m, 972 vw, 940 m, 910 m, 899
m, 891 m, 851 vw, 808 vs, 793 s, 750 m, 739 s [δ(CH),
ν(CC)]; 719 vs (paraffin); 700 vs, 652 s (phenyl); 619 w,
3JSiH = 25.1 Hz, C=CH), 1.29 (s, 18 H, GaCMe3), 1.15 (s,
9 H, C≡C–CMe3), 1.10 ppm (s, 9 H, C=C–CMe3). – 13C
NMR (100.59 MHz, C6D6): δ = 166.7 (C=C–CMe3), 141.8
(C =C–CMe3), 138.7 (ipso-C), 135.2 (o-C), 129.8 (p-C),
128.6 (m-C), 122.4 (C≡C–CMe3), 81.3 (C≡C–CMe3), 39.8
(C=C–CMe3), 31.2 (GaCMe3), 30.8 (C≡C–CMe3), 30.0
(C=C–CMe3), 29.4 (GaCMe3), 28.8 ppm (C≡C–CMe3). –
29Si NMR (79.47 MHz, C6D6): δ = −38.1 ppm. – MS ((+)-
EI; 20 eV; 298 K): m/z (%) = 471 (100) [M–CMe3]+, 415
(5) [M–CMe3–H2C=CMe2]+, 344 (9) [M–HGa(CMe3)2]+.
– C32H47GaSi (529.53): calcd. C 72.6, H 8.9; found C 72.0,
H 9.0.
Ph2Ge(C≡C-Ph){C[Ga(CMe3)2]=CH-Ph} (10)
A solution of HGa(CMe3)2 (0.127 g, 0.69 mmol) in n-
590 m, 563 m, 529 vs, 490 s, 471 m, 463 m cm−1 [ν(SiC), hexane (10 mL) was added at room temperature dropwise
ν(AlC), δ(CC)]. – 1H NMR (400.03 MHz, C6D6): δ = 7.93 to a solution of Ph2Ge(C≡C-Ph)2 (5) (0.297 g, 0.69 mmol)
(d, 3JHH = 7.2 Hz, 4 H, o-H), 7.35 (s, 3JSiH = 27.8 Hz, 1 H, in n-hexane (10 mL). The mixture was stirred for 3 h, the
C=CH), 7.22 (pseudo-t, 3JHH = 7.2 Hz, 4 H m-H), 7.15 (t, volatiles were removed in vacuo, and the residue was re-
3JHH = 7.2 Hz, 2 H, p-H), 1.33 (s, 18 H, AlCMe3), 1.05 crystallised from n-pentane at −15 ◦C to yield compound
(s, 9 H, C≡C–CMe3), 1.01 ppm (s, 9 H, C=C–CMe3). – 10 as a colourless solid (0.267 g, 63%); m. p. (argon, sealed
13C NMR (100.59 MHz, C6D6): δ = 171.3 (C=C–CMe3), capillary): 134◦C. – IR (CsI, paraffin): ν = 2154 m, 2132
137.1 (ipso-C), 135.9 (C =C–CMe3 and o-C), 131.6 (C≡C– sh ν(C≡C); 1661 w, 1597 w, 1551 m [ν(C=C), phenyl];
CMe3), 130.0 (p-C), 128.3 (m-C), 81.7 (C≡C–CMe3), 39.9 1460 vs, 1377 vs (paraffin); 1304 vw, 1248 w δ(CH3);
(C=C–CMe3), 31.1 (AlCMe3), 30.4 (C≡C–CMe3), 29.6 1169 vw, 1090 m, 1026 m, 930 vw, 914 vw, 812 w, 756
(C=C–CMe3), 29.4 (C≡C–CMe3), 19.0 ppm (AlCMe3). – m [δ(CH), ν(CC)]; 733 m (paraffin); 694 δ(Ph); 621 vw,
1
29Si NMR (79.47 MHz, C6D6): δ = −32.4 ppm. – MS 577 w, 532 w, 463 m cm−1[ν(SiC), ν(GaC), δ(CC)]. – H
((+)-EI; 20 eV; 298 K): m/z (%) = 429 (8) [M–CMe3]+, NMR (400.13 MHz, C6D6): δ = 7.94 (s, 1 H, C=CH),
3
346 (9) [M–Al(CMe3)2+H]+, 289 (100) [M–Al(CMe3)2– 7.82 (d br, 4 H, JHH = 6.8 Hz, o-H, GePh2), 7.45 (d, 2
H2C=CMe2]+. – C32H47AlSi (486.8): calcd. C 79.0, H 9.7; H, JHH = 7.3 Hz, o-H, C≡C-Ph), 7.41 (d, 2 H, JHH
=
3
3
found C 78.2, H 9.7.
6.7 Hz, o-H, C=CHPh), 7.14 (m, 4 H, m-H, GePh2), 7.09
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W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
1343
(m, 2 H, p-H, GePh2), 6.96 (pseudo-t, 2 H, JHH = 6.7 −15 ◦C to yield compound 12 as a colourless solid (0.352 g,
Hz, m-H, C=CHPh), 6.92 (t, 1 H, p-H, C=CHPh), 6.89 (t, 98%); m. p. (argon, sealed capillary): 87◦C. – IR (CsI, paraf-
1 H, p-H, C≡C-Ph), 6.88 (pseudo-t, 2 H, m-H, C≡C-Ph), fin): ν = 2196 w, 2156 s, 2116 m ν(C≡C); 1644 w, 1603
1.38 ppm (s, 18 H, GaCMe3). – 13C NMR (100.62 MHz, s, 1566 m, 1556 m, 1533 s, 1511 m [ν(C=C), aromatic
C6D6): δ = 154.2 (C =C-Ph), 151.7 (C=C-Ph), 141.4 (ipso- ring]; 1454 vs (paraffin); 1411 w δ(CH3); 1382 vs (paraf-
C, C=CHPh), 137.3 (ipso-C, GePh2), 134.9 (o-C, GePh2), fin); 1365 s, 1305 w, 1287 w, 1253 s δ(CH3); 1202 m,
133.0 (o-C, C≡C-Ph), 129.7 (p-C, GePh2), 129.6 (p-C, 1179 m, 1138 w, 1112 w, 1071 m, 1044 m, 1030 w, 1006
C≡C-Ph), 128.8 (m-C, GePh2), 128.6 (m-C, C≡C-Ph and w, 999 w, 955 m, 940 s, 889 m, 850 m, 835 w, 808 m,
C=CHPh), 128.1 (o-C, C=CHPh), 127.9 (p-C, C=CHPh), 791 m, 767 s, 753 w [δ(CH), ν(CC)]; 720 vs (paraffin);
122.2 (ipso-C, C≡C-Ph), 110.0 (C≡C-Ph), 93.0 (C≡C-Ph), 677 m, 660 m (aromatic ring); 639 vw, 615 s, 573 m, 564
30.8 (GaCMe3), 29.5 ppm (GaCMe3). – MS ((+)-EI; 20 eV; m, 520 m, 502 w, 475 w, 448 m cm−1 [ν(SiC), ν(AlC),
351 K): m/z (%) = 557 (100) [M–CMe3]+, 501 (6) [M– δ(CC)]. – 1H NMR (400.03 MHz, C6D6): δ = 6.95 (s,
CMe3–butene]+. – C36H39GaGe (614.0): calcd. C 70.4, H 3JSiH = 29.8 Hz, 1 H, C=CH), 6.76 (s, 2 H, m-H), 2.89
3
6.4; found C 70.5, H 6.4.
(s, 6 H, o-Me), 2.37 (m, 2 H, AlCH2CHMe2), 2.05 (s, 3
H, p-Me), 1.32 (d, JHH = 6.5 Hz, 12 H, AlCH2CHMe2),
3
(F5C6)2Ge(C≡C–CMe3){C[Al(CMe3)2]=CH–CMe3} (11)
1.13 (s, 9 H, C=C–CMe3), 1.09 (s, 18 H, (C≡C–CMe3),
0.70 ppm (d, JHH = 7.0 Hz, 4 H, AlCH2CHMe2). – 13C
3
A solution of (F5C6)2Ge(C≡C–CMe3)2 (7) (0.430 g,
0.76 mmol) in toluene (10 mL) was added to a solution of
HAl(CMe3)2 (0.118 g, 0.83 mmol) at room temperature. The
mixture was stirred for 2 h. The solvent was removed in
vacuo, and the residue was recrystallised from n-pentane at
−30 ◦C to yield 11 as a colourless solid (0.473 g, 88%); m.
p. (argon, sealed capillary): 83◦C (dec.). – IR (CsI, paraffin):
ν = 2193 m, 2158 m, 2120 w ν(C≡C); 1942 vw, 1869 vw,
1719 vw, 1639 s, 1605 m, 1582 w, 1549 w, 1516 vs [ν(C=C),
aromatic ring]; 1456 vs, 1377 vs (paraffin); 1341 m, 1304 w;
NMR (100.59 MHz, C6D6): δ = 166.8 (C=C–CMe3), 144.9
(o-C), 140.9 (br. s, C =C–CMe3), 139.8 (p-C), 129.9 (m-C
and ipso-C), 122.2 (C≡C–CMe3), 83.7 (C≡C–CMe3), 39.6
(C=C–CMe3), 30.1 (C≡C–CMe3), 29.0 (C=C–CMe3), 28.9
(C≡C–CMe3), 28.8 (AlCH2CHMe2), 27.0 (AlCH2CHMe2),
26.6 (AlCH2CHMe2), 25.5 (o-Me), 21.1 ppm (p-Me). – 29Si
NMR (79.5 MHz, C6D6): δ = −63.1 ppm. – MS ((+)-EI;
20 eV; 298 K): m/z (%) = 475 (100) [M–CMe3]+.
1285 s ν(CF); 1254 s δ(CH3); 1219 m, 1204 m, 1179 w, Mes-Si(C≡C–CMe3)2{C[Al(CMe3)2]=CH–CMe3} (13)
1138 vw, 1084 vs, 1049 w, 1028 w, 1009 m, 972 vs, 934 m,
889 m, 845 w, 812 m, 773 w 752 m [ν(CF), δ(CH), ν(CC)];
A
solution of Mes-Si(C≡C–CMe3)3 (2) (0.316 g,
723 s (paraffin); 665 w, 635 w, 619 m, 583 m, 571 w, 557 w,
0.810 mmol) in toluene (10 mL) was added at room temper-
ature to a solution of HAl(CMe3)2 (0.115 g, 0.810 mmol)
in toluene (15 mL). The mixture was stirred overnight, the
volatiles were removed in vacuo, and the residue was recrys-
tallised from pentafluorobenzene at −20 ◦C to yield com-
pound 13 as a colourless solid (0.425 g, 98%); m. p. (ar-
gon, sealed capillary): 107◦C. – IR (CsI, paraffin): ν =
2197 w, 2156 m, 2126 w ν(C≡C); 1603 m ν(C=C); 1458
vs, 1375 s (paraffin); 1302 w, 1254 m δ(CH3); 1190 vw,
1169 w, 1153 w, 1067 vw, 1028 vw, 939 w, 891 w, 847
m, 773 m [δ(CH), ν(CC)]; 721 s (paraffin); 660 w, 615 w,
567 w, 530 vw, 472 vw cm−1 [ν(SiC), ν(AlC), δ(CC)]. –
1
536 w, 494 m cm−1 [ν(GeC), ν(AlC), δ(CC)]. – H NMR
(400.03 MHz, [D8]toluene): δ = 6.94 (s, 1 H, C=CH), 1.21
(s, 18 H, AlCMe3), 1.14 (s, 9 H, C≡C–CMe3), 1.02 ppm (s,
9 H, C=C–CMe3). – 13C NMR (100.59 MHz, [D8]toluene):
δ = 169.0 (C=CH), 148.6 (dm, 1JFC = 240 Hz, o-C), 142.8
(dm, 1JFC = 257 Hz, p-C), 137.9 (dm, 1JFC = 257 Hz, m-C),
134.6 (C =CH), 111.7 (ipso-C), 77.7 (C≡C–CMe3), C≡C–
CMe3 not observed, 40.4 ( C=C–CMe3), 30.4 (AlCMe3),
30.3 (C≡C–CMe3), 29.1 (C=C–CMe3), 29.0 (C≡C–CMe3),
17.8 ppm (AlCMe3). – 19F NMR (376.4 MHz, [D8]toluene):
3
δ = −128.9 (s br., 4 F, o-F), −148.9 (t, JFF = 20.3 Hz, 2
1H NMR (400.13 MHz, C6D6): δ = 6.99 (s, 1 H, JSiH
3
F, p-F), −159.1 ppm (s br., 4 F, p-F). – MS ((+)-EI; 20 eV;
343 K): m/z (%) = 655 (100) [M–CMe3]+.
= 30.4 Hz, C=CH), 6.76 (s, 2 H, m-H), 2.89 (s, 6 H, o-
Me), 2.05 (s, 3 H, p-Me), 1.43 (s, 18 H, AlCMe3), 1.23
(s, 9 H, C=C–CMe3), 1.09 ppm (s, 18 H, C≡C–CMe3). –
13C NMR (100.62 MHz, C6D6): δ = 167.8 (C=C–CMe3),
Mes-Si(C≡C–CMe3)2{C[Al(CH2CHMe2)2]=CH–CMe3}
(12)
A
solution of Mes-Si(C≡C–CMe3)3 (2) (0.264 g, 145.2 (o-C), 139.7 (p-C), 139.5 (br. s, C =C–CMe3), 129.9
0.677 mmol) in toluene (15 mL) was added at room tem- (m-C), 129.8 (ipso-C), 123.9 (C≡C–CMe3), 82.9 (C≡C–
perature to a solution of HAl(CH2CHMe2)2 (0.096 g, CMe3), 40.3 (C=C–CMe3), 31.3 (AlCMe3), 30.3 (C≡C–
0.676 mmol) in toluene (15 mL). The mixture was stirred CMe3), 29.0 (C≡C–CMe3), 28.6 (C=C–CMe3), 25.2 (o-
overnight, the volatiles were removed in vacuo and the Me), 21.0 (p-Me), 18.7 ppm (br. s, AlCMe3). – 29Si NMR
residue was recrystallised from 1,2-difluorobenzene at (79.5 MHz, C6D6): δ = −61.1 ppm. – MS ((+)-EI; 50 eV;
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W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
323 K): m/z (%) = 392 (24) [M–Al(CMe3)2+H]+, 335 (93) residue was washed twice at 0◦C with n-pentane (5 mL) to
[M–Al(CMe3)2–butene]+.
remove unreacted alkyne and recrystallised from pentaflu-
orobenzene at −30 ◦C to yield compound 16 (0.47 g, 71%
based on the alkyne); m. p. (argon, sealed capillary): 166◦C.
– IR (CsI, paraffin): ν = 1973 vw, 1958 w, 1902 vw, 1886
w, 1844 vw, 1829 w, 1775 vw, 1738 vw, 1686 vw, 1651
vw, 1593 s, 1555 vs [ν(C=C), phenyl]; 1464 vs (paraffin);
1427 m, 1418 vw δ(CH3); 1377 s (paraffin); 1358 s, 1302
m, 1267 m, 1248 s δ(CH3); 1200 s, 1169 w, 1153 vw, 1084
vs, 1063 w, 1043 vw, 1022 vw, 1013 w, 1001 m, 974 w,
939 w, 918 m, 895 m, 872 s, 860 m, 806 s, 793 s, 768
vw, 737 vs [δ(CH), ν(CC)]; 712 s (paraffin); 696 s, 665
m (phenyl); 619 w, 579 vs, 567 sh, 530 w, 503 s, 473 s,
Ph2Si{C[Al(CMe3)2]=CH–CMe3}2 (14)
A solution of HAl(CMe3)2 (0.589 g, 4.14 mmol) in
toluene (50 mL) was treated with solid Ph2Si(C≡C–CMe3)2
(1) (0.714 g, 2.07 mmol) at room temperature. The colourless
solution was stirred for 33 d. All volatiles were removed in
a vacuum. Repeated recrystallisation gave a colourless solid
which contained the monoaddition product 8 and 14 in a ratio
of 0.65 : 0.35. – 1H NMR data of 14 (400.03 MHz, C6D6): δ
= 7.74 (d, 3JHH = 7.9 Hz, 4 H, o-H), 7.35 (pseudo-t, 3JHH
=
7.9 Hz, 4 H, m-H), 7.03 (t, 3JHH = 7.9 Hz, 2 H, p-H), 6.86 (s,
3JSiH = 25.6 Hz, 2 H, C=CH), 1.26 (s, 18 H, C=C–CMe3),
0.97 ppm (s, br, 36 H, AlCMe3).
1
461 s, 447 s, 408 vs cm−1 [ν(GeC), ν(GaC), δ(CC)]. – H
3
NMR (400.13 MHz, C6D6): δ = 7.67 (d, JHH = 6.6 Hz,
3
4 H, o-H), 7.22 (pseudo-t, JHH = 7.5 Hz, 4 H, m-H), 7.06
Ph2Si{C[Ga(CMe3)2]=CH–CMe3}2 (15)
3
(t, JHH = 7.4 Hz, 2 H, p-H), 6.46 (s, 1 H, C=CH), 1.31
(s, 18 H, C=C–CMe3), 1.04 ppm (br, 36 H, GaCMe3). –
13C NMR (100.62 MHz, C6D6): δ = 158.5 (C=C–CMe3),
149.5 (C =C–CMe3), 148.3 (ipso-C), 133.0 (o-C), 130.7
(m-C), 129.5 (p-C), 38.8 (C=C–CMe3), 31.1 (GaCMe3),
30.1 (GaCMe3), 30.0 ppm (C=C–CMe3). – MS ((+)-EI;
20 eV; 353 K): m/z (%) = 701 (13) [M–CMe3]+, 517 (100)
[M–HGa(CMe3)2–CMe3]+. – C40H66Ga2Ge (759.0): calcd.
C 63.3, H 8.8; found C 62.9, H 8.7.
Solid Ph2Si(C≡C–CMe3)2 (1) (0.621 g, 1.80 mmol) was
added to a solution of HGa(CMe3)2 (0.667 g, 3.61 mmol)
in toluene (40 mL) at room temperature. The mixture was
stirred for 20 d. All volatiles were removed in vacuo. The
residue was dissolved in pentafluorobenzene (50 mL), the
solution concentrated to about 20 mL and stored at −30 ◦C
to yield compound 15 as a colourless solid (0.96 g, 75%);
m. p. (argon, sealed capillary): 157◦C. – IR (CsI, paraffin):
ν = 1558 s ν(C=C); 1456 vs, 1377 vs (paraffin); 1306 w,
1261 vw, 1250 m δ(CH3); 1200 m, 1169 w, 1156 w, 1098
s, 1063 w, 1013 w, 1003 w, 972 vw, 939 w, 920 w, 901 w,
876 m, 806 s, 799 s, 743 s, 737 s [δ(CH), ν(CC)]; 714 vs
(paraffin); 700 vs, 689 s δ(Ph); 656 m, 619 w, 610 m, 523
s, 480 m, 457 w, 434 w cm−1 [ν(SiC), ν(GaC), δ(CC)]. –
1H NMR (400.03 MHz, C6D6): δ = 7.69 (d, 3JHH = 7.2 Hz,
Ph2Ge{C[Ga(CMe3)2]=CH-Ph}2 (17)
A solution of Ph2Ge(C≡C-Ph)2 (5) (0.356 g, 0.83 mmol)
in toluene (10 mL) was added at room temperature to a so-
lution of HGa(CMe3)2 (0.327 g, 1.77 mmol) in toluene
(50 mL). The colourless mixture was stirred for 8 d at room
temperature whereupon the colour changed to yellow. The
volatiles were removed in vacuo to give a yellow foam,
which contained up to 50% of the mono-hydrogallation
product Ph2Ge(C≡CPh){C[Ga(CMe3)2]=CH-Ph} (10). Re-
peated recrystallization from pentafluorobenzene (45◦ C /
−30 ◦C) yielded 17 as a colourless solid (0.127 g, 19%); m.
p. (argon, sealed capillary): 184◦C (dec). – IR (CsI, paraf-
fin): ν = 1996 vw, 1940 vw, 1894 vw, 1883 vw, 1597
sh, 1584 w, 1547 m [ν(C=C), phenyl]; 1460 vs, 1375 vs
(paraffin); 1304 w, 1265 w, 1249 vw δ(CH3); 1171 m, 1082
m, 1027 w, 1009 w, 972 vw, 935 w, 916 w, 868 w, 841
w, 804 w [δ(CH), ν(CC)]; 728 m (paraffin); 692 m, 669
w δ(Ph); 621 w, 594 vw, 569 w, 532 m, 505 m, 471 m,
3
4 H, o-H), 7.22 (pseudo-t, JHH = 7.4 Hz, 4 H, m-H), 7.07
3
3
(t, JHH = 7.5 Hz, 2 H, p-H), 6.43 (s, JSiH = 24.2 Hz,
2 H, C=CH), 1.33 (s, 18 H, C=C–CMe3), 1.03 ppm (s,
br, 36 H, GaCMe3). – 13C NMR (100.59 MHz, C6D6): δ
= 160.3 (C=C–CMe3), 148.2 (C =C–CMe3), 145.6 (ipso-
C), 133.8 (o-C), 130.5 (m-C), 129.9 (p-C), 39.2 (C=C–
CMe3), 31.3 (GaCMe3), 30.2 (GaCMe3), 30.0 ppm (C=C–
CMe3). – 29Si NMR (79.47 MHz, C6D6): δ = −27.0 ppm.
– MS ((+)-EI; 20 eV; 298 K): m/z (%) = 657 (3) [M–
CMe3]+, 471 (100) [M–Ga(CMe3)2–HCMe3]+, 415 (12)
[M–Ga(CMe3)2–2 CMe3]+. – C40H66Ga2Si (714.5): calcd.
C 67.2, H 9.3; found C 67.1, H 9.4.
1
457 w, 432 m cm−1 [ν(GeC), ν(GaC), δ(CC)]. – H NMR
Ph2Ge{C[Ga(CMe3)2]=CH–CMe3}2 (16)
3
(400.03 MHz, C6D6): δ = 7.66 [d, JHH = 6.6 Hz, 4 H, o-
3
A
solution of Ph2Ge(C≡C–CMe3)2 (4) (0.337 g, H (GePh)], 7.63 (s, 2 H, C=CH), 7.53 [d, JHH = 7.5 Hz,
0.87 mmol) in toluene (5 mL) was added at room temper- 4 H, o-H (C=CPh)], 7.12 [m, m-H (C=CPh)], 7.10 [m, 4
ature to a solution of HGa(CMe3)2 (0.353 g, 1.91 mmol) H, m-H (GePh)], 7.03 [t, 3JHH = 7.4 Hz, 2 H, p-H (GePh)],
3
in toluene (50 mL). The resulting colourless mixture was 6.96 [t, JHH = 7.4 Hz, 2 H, p-H (C=CPh)], 1.06 ppm (s,
stirred for 6 d at room temperature to yield a pale-brown 18 H, GaCMe3). – 13C NMR (100.59 MHz, C6D6): δ =
solution. The volatiles were removed in vacuo, and the 160.5 (C =CHPh), 148.9 (C=CHPh), 145.1 [ipso-C (GePh)],
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W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
1345
140.0 [ipso-C (C=CPh)], 133.3 [o-C (GePh)], 130.8 [m-C 837 w, 816 s, 806 s, 785 w [δ(CH), ν(CC)]; 721 vs (paraf-
(GePh)], 130.0 [p-C (GePh)], 128.4 [m-C (C=CPh)], 127.84 fin); 694 w δ(Ph); 652 w, 615 m, 552 m, 536 s, 517 m,
1
[p-C (C=CPh)], 127.78 [o-C (C=CPh)], 30.7 (GaCMe3), 505 m, 455 w, 436 w cm−1[ν(SiC), ν(GaC), δ(CC)]. – H
30.4 ppm (GaCMe3). – MS ((+)-EI; 20 eV; 373 K): m/z NMR (400.13 MHz, C6D6): δ = 8.33 [s, 3JSiH <13 Hz, 1 H,
(%) = 741 (36) [M–CMe3]+, 557 (51) [M–HGa(CMe3)2– C=CH (trans)], 7.98 [s, 3JSiH = 24.3 Hz, 1 H, C=CH (cis)],
3
CMe3]+. – C44H58Ga2Ge (799.0): calcd. C 66.1, H 7.3; 7.57 [d, JHH = 8.0 Hz, 4 H,o-H (cis) and o-H (ethyne)],
3
3
found C 66.1, H 7.3.
7.08 [d, JHH = 8.0 Hz, 2 H, m-H (cis)], 6.87 [d, JHH =
3
2.6 Hz, 4 H, o- and m-H (trans)], 6.77 [d, JHH = 7.8 Hz,
2 H, m-H (ethyne)], 2.11 [s, 3 H, p-Me (cis)], 1.96 [s, 3 H,
p-Me (trans)], 1.89 [s, 3 H, p-Me (ethyne)], 1.47 [s, 18 H,
GaCMe3 (cis)], 1.36 and 1.13 [each s, 9 H, GaCMe3 (trans)],
0.83 ppm (s, 3 H, SiMe). – 13C NMR (100.62 MHz, C6D6):
δ = 158.6 [C =C-p-Tol (trans)], 156.1 [C=C-p-Tol (trans)],
153.3 [C =C-p-Tol (cis)], 152.4 [C=C-p-Tol (cis)], 144.4
[ipso-C (trans)], 140.4 [p-C (ethyne)], 138.9 [ipso-C (cis)],
138.4 [p-C (trans)], 137.4[p-C (cis)], 133.1 [o-C (ethyne)],
131.2 [m-C (trans)], 129.6 [m-C (ethyne)], 129.4[m-C
(cis)], 128.6 [o-C (cis)], 124.0 [o-C (trans)], 119.0 [ipso-
C (ethyne)], 111.5 (C≡C-p-Tol), 93.6 (C≡C-p-Tol), 31.1
[GaCMe3 (cis)], 30.4 and 30.3 [GaCMe3 (trans)], 29.2
[GaCMe3 (cis)], 29.0 and 28.8 [GaCMe3(2) (trans)], 21.3
(C≡C-C6H4Me), 21.2 [C=C-C6H4Me (cis)], 20.9 [C=C-
C6H4Me (trans)], 1.1 ppm (SiMe). – 29Si NMR (79.5 MHz,
C6D6): δ = −34.1 ppm. – MS ((+)-EI; 30 eV; 353 K): m/z
(%) = 701 (20) [M–CMe3]+, 517 (100) [M–2Tol–CMe3–2H
or M–Ga(CMe3)2–butene]+. – C44H62Ga2Si (758.5): calcd.
C 69.7, H 8.2; found C 68.9, H 8.2.
(Me3C–C≡C)2Ge{C[Ga(CMe3)2]=CH–CMe3}2 (18)
A solution of Ge(C≡C–CMe3)4 (6) (0.440 g, 1.11 mmol)
in toluene (10 mL) was added at 0◦C to a solution of
HGa(CMe3)2 (0.410 g, 2.22 mmol) in toluene (10 mL). The
mixture was stirred at this temperature for 30 min and then
warmed to room temperature over a period of 16 h. The
volatiles were removed in vacuo, and the residue was recrys-
tallised from 1,2-difluorobenzene to yield 18 as a colourless
solid (0.451 g, 53%); m. p. (argon, sealed capillary): 182◦C.
– IR (CsI, paraffin): ν = 2160 sh, 2131 m ν(C≡C); 1953
vw, 1906 vw, 1886 vw, 1821 vw, 1763 vw, 1676 vw, 1585
w, 1551 vw [ν(C=C), phenyl]; 1464 vs, 1377 vs (paraffin);
1306 w, 1279 vw, 1265 w, 1248 w sh δ(CH3); 1209 vw, 1182
w, 1159 w, 1084 s, 1070 m, 1026 w, 1001 w, 966 w, 937 w,
920 m, 876 w, 841 w, 808 m, 756 s [δ(CH), ν(CC)]; 733 vs
(paraffin); 694 s, 671 w δ(Ph); 621 vw, 565 m, 534 m, 501
m, 461 s, 422 m cm−1 [ν(GeC), ν(GaC), δ(CC)]. – 1H NMR
(400.03 MHz, C6D6): δ = 6.49 (s, 2 H, C=CH), 1.44 (s, 36
H, GaCMe3), 1.21 (s, 18 H, C=C–CMe3), 1.17 ppm (s, 18 H,
C≡C–CMe3). – 13C NMR (100.59 MHz, C6D6): δ = 160.3 X-Ray crystallography
(C=C–CMe3), 148.5 (C =C–CMe3), 119.5 (C≡C–CMe3),
Crystals suitable for X-ray crystallography were ob-
84.7 (C≡C–CMe3), 38.4 (C=C–CMe3), 31.6 (GaCMe3),
31.0 (C≡C–CMe3), 30.2 (C=C–CMe3), 29.2 (br, GaCMe3),
28.8 ppm (C≡C–CMe3). – MS ((+)-EI; 20 eV; 353 K): m/z
(%) = 709 (100) [M–CMe3]+, 525 (55) [M–HGa(CMe3)2–
CMe3]+. – C40H74Ga2Ge (767.1): calcd. C 62.6, H 9.7;
found C 62.5, H 9.7.
tained by recrystallisation from n-pentane (7, 10, 11), 1,2-
difluorobenzene (2, 8, 9, 12, 18) or pentafluorobenzene (13,
15, 16, 17). Intensity data were collected on a Bruker APEX
II diffractometer with monochromated MoKα or CuKα (10)
radiation. The collection method involved ω scans. Data re-
duction was carried out using the program SAINT+ [33].
The crystal structures were solved by Direct Methods using
SHELXTL [34, 35]. Non-hydrogen atoms were first refined
Me-Si(C≡C-p-Tol){C[Ga(CMe3)2]=CH-p-Tol}2 (19)
Solid Me-Si(C≡C-p-Tol)3 (3) (0.283 g, 0.73 mmol) was isotropically followed by anisotropic refinement by full ma-
added at room temperature to a solution of HGa(CMe3)2 trix least-squares calculations based on F2 using SHELXTL.
(0.270 g, 1.46 mmol) in toluene (25 mL). The colourless Hydrogen atoms were positioned geometrically and allowed
mixture was stirred for 3 d to give an orange solution. All to ride on their respective parent atoms. Compound 7 crys-
volatiles were removed in vacuo. The residue was recrys- tallised with one n-pentane molecule per unit cell, which
tallised from c-pentane at −15 ◦C to yield 19 as an amor- was disordered across the inversion centre, compound 2 crys-
phous solid (0.451 g, 81%). [Assignment of NMR spectra: tallised with one 1,2-difluorobenzene molecule per formula
signals in the alkenyl group are labelled cis (H cis to Ga) unit, which showed rotational disorder over two positions
or trans (H trans to Ga)]. – IR (CsI, paraffin): ν = 2147 (0.61 : 0.39). Similarly, 15 and 18 crystallised with half
s sh, 2133 vs ν(C≡C); 2058 m, 1904 w, 1790 w, 1650 w, a molecule of pentafluorobenzene each which were disor-
1643 w, 1607 m, 1580 m, 1573 m, 1556 m, 1542 w, 1504 dered across the inversion centre. Compounds 12, 16 and 18
vs [ν(C=C, phenyl]; 1462 vs, 1454 vs, 1377 vs (paraffin); had peripheral alkyl substituents that were disordered and re-
1366 vs, 1302 w, 1269 vw, 1246 m δ(CH3); 1219 w, 1177 fined in split positions (12, CMe3: C31 0.60 : 0.24 : 0.16,
m, 1109 w, 1070 w, 1038 w, 1020 m, 1015 m, 943 w, 897 m, C71 0.51 : 0.49; CMe2: C91 0.83 : 0.17; 16, CMe3: C04
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W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
Table 3a. Crystal data and structure refinement for compounds 1, 7–11.
2
7 · 0.5 pentane
8
9
10
11
Crystal data
Empirical formula
Mr
Crystal system
Space group
a, pm
C33H42F2Si
504.75
monoclinic
P21/c
1228.56(5)
1037.99(4)
2457.4(1)
90
96.705(1)
90
3111.6(2)
1.08
C26.5H24F10Ge C32H47AlSi
C32H47GaSi
529.50
triclinic
P1
911.49(1)
1113.17(1)
1731.42(2)
71.3133(6)
79.6900(7)
73.0344(7)
1584.64(3)
1.11
C36H39GaGe
613.98
triclinic
P1
851.95(1)
986.46(1)
2015.27(3)
87.9904(8)
87.5809(8)
66.9190(8)
1556.38(3)
1.31
C32H37AlF10Ge
711.18
monoclinic
C2/c
3690.9(1)
1049.48(4)
1822.45(8)
90
108.510(1)
90
6694.2(4)
1.41
605.05
triclinic
P1
486.76
triclinic
P1
963.84(7)
1088.69(8)
1473.9(1)
77.440(2)
89.546(2)
64.099(2)
1351.3(2)
1.49
910.46(2)
1115.99(2)
1722.41(3)
71.458(1)
78.985(1)
78.820(1)
1576.06(5)
1.03
b, pm
c, pm
α, deg
β, deg
γ, deg
V, × 10−30 m3
ρ
calcd., g cm−3
4
2
2
2
2
8
Z
F(000), e
1088
0.1
610
1.2
532
0.1
568
0.9
636
2.4
2912
1.0
µ, mm−1
Data collection
T, K
153
153
153
153
153
153
Unique reflections/Rint
Reflections I > 2 σ(I)
Refinement
7885/0.027
6758
7750/0.067
6695
9177/0.042
6419
9200/0.026
8102
5046/0.020
4471
9758/0.023
7922
Refined parameters
Final R1 [I > 2 σ(I)]a
Final wR2b (all data)
435
0.0564
0.1653
344
319
319
349
409
0.0412
0.1108
0.56/−0.64
0.0484
0.1309
0.30/−0.26
0.0294
0.0766
0.61,/−0.22
0.0309
0.0837
0.46/−0.39
0.0374
0.1004
0.56/−0.39
∆ρfin (max/min), e Å−3 0.44/−0.36
a
R1 = Σ k Fo|−|F k /Σ|Fo|; b wR2 = [Σw(Fo2 −F2)2/Σw(Fo2)2]1/2, w = [σ2(Fo2)+(AP)2 +BP]−1, where P = (Max(Fo2,0)+2F2)/3.
c
c
c
Table 3b. Crystal data and structure refinement for compounds 12, 13, 15–18.
12
13
15 · 0.5C6F5H
16
17
18 · 0.5C6F2H4
Crystal data
Empirical formula
Mr
Crystal system
Space group
a, pm
C35H57AlSi
532.87
monoclinic
P21/c
1114.73(3)
1941.94(4)
1710.49(4)
90
100.875(1)
90
3636.3(2)
0.97
C35H57AlSi
532.87
monoclinic
P21/n
1237.82(7)
1638.7(1)
1751.3(1)
90
90.520(2)
90
3552.2(4)
1.00
C44H66.5F2.5Ga2Si
798.49
monoclinic
P21/c
1563.74(2)
1298.79(2)
2129.10(3)
90
92.0049(8)
90
C40H66Ga2Ge C44H58Ga2Ge C43H76FGa2Ge
758.95
monoclinic
C2/c
798.93
triclinic
P1
824.06
monoclinic
C2/c
3216.45(8)
1774.27(3)
1478.34(4)
90
103.501(2)
90
993.94(6)
1452.48(9)
1494.24(9)
97.5976(9)
103.2638(9)
100.0523(9)
2033.8(2)
1.31
4928.4(3)
1067.88(6)
1870.2(1)
90
105.976(1)
90
b, pm
c, pm
α, deg
β, deg
γ, deg
V, × 10−30 m3
4321.5(1)
1.23
4
8203.5(2)
1.23
9462.7(9)
1.16
ρ
calcd., g cm−3
Z
4
4
8
2
8
F(000), e
1176
0.1
1176
0.1
1692
1.3
3200
2.1
832
2.1
3496
1.8
µ, mm−1
Data collection
T, K
233
153
153
153
153
153
Unique reflections/Rint
Reflections I > 2 σ(I)
Refinement
8671/0.033
6525
10436/0.025
8890
12587/0.027
11 146
9831/0.071
7566
9824/0.016
8431
13809/0.050
9024
Refined parameters
Final R [I > 2 σ(I)]a
Final wR2b (all data)
450
0.0509
0.1619
352
505
437
436
559
0.0459
0.1402
0.55/−0.42
0.0245
0.0689
0.53/−0.28
0.0397
0.0969
0.79/−0.74
0.0240
0.0641
0.51/−0.54
0.0439
0.1221
1.23/−0.70
∆ρfin (max/min), e Å−3 0.36/−0.20
a
R1 = Σ k Fo|−|F k /Σ|Fo|; b wR2 = [Σw(Fo2 −F2)2/Σw(Fo2)2]1/2, w = [σ2(Fo2)+(AP)2 +BP]−1, where P = (Max(Fo2,0)+2F2)/3.
c
c
c
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W. Uhl et al. · Hydrometallation (M = Al, Ga) of Silicon- and Germanium-centred Oligoalkynes
1347
0.84 : 0.16; 18, CMe3: C13 0.69 : 0.31, C01 0.46 : 0.54, C04 data for this paper. This data can be obtained free of charge
0.57 : 0.43). Further crystallographic data is summarised in from The Cambridge Crystallographic Data Centre via www.
Table 3.
ccdc.cam.ac.uk/data_request/cif.
CCDC 1002760 (7), 1002761 (2), 1002762 (8), 1002763
Acknowledgement
(9), 1002764 (11), 1002765 (12), 1002766 (13), 1002767
(15), 1002768 (16), 1002769 (17), 1002770 (18), and
1013176 (10) contain the supplementary crystallographic
We are grateful to the Deutsche Forschungsgemeinschaft
for generous financial support.
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