Alkenyl-alkynylgermanes functionalised by lewis acids: Intramolecular aluminium- and gallium-alkyne interactions and potential GE-C bond activation

Article abstract of DOI:10.1002/ejic.201402132

Treatment of various diethynylgermanes, (R¹)₂Ge(C≡C-R²)₂ (R¹ = C₆H₅, CH₃; R¹-R¹ = C₆H₄-C₆H₄; R^2<

Full text of DOI:10.1002/ejic.201402132

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DOI:10.1002/ejic.201402132
Alkenyl-Alkynylgermanes Functionalised by Lewis Acids:
Intramolecular Aluminium– and Gallium–Alkyne
Interactions and Potential Ge–C Bond Activation
Werner Uhl,*[a] Stefan Pelties,[a] Martina Rohling,[a] and
Jens Tannert[a]
Keywords: Germanium / Aluminum / Alkynes / Metalation / Lewis acids
Treatment of various diethynylgermanes, (R1)2Ge(CϵC–R2)2
(R1 = C6H5, CH3; R1–R1 = C6H4–C6H4; R2 = CH3, CMe3, nBu,
C6H5), with equimolar quantities of di(tert-butyl)aluminium
or -gallium hydride, R2E–H (E = Al, Ga), afforded mixed alk-
enyl-alkynylgermanes, (R1)2Ge(CϵC–R2)[C{E(CMe3)2}=C-
(H)–R2], by reduction of one of their CϵC triple bonds. The
alkenyl groups have a cis arrangement of H and Al or Ga
atoms across the C=C double bonds, which reflects the kinet-
ically favoured situation. The cis/trans isomerisation is prob-
ably prevented from yielding thermodynamically favoured
trans isomers; this is a result of an intramolecular bonding
interaction between the α-carbon atoms of the remaining
ethynyl groups and the coordinatively unsaturated metal
atoms. The higher Lewis acidity of Al compared to Ga results
in relatively short Al···C(ethynyl) contacts (Ͼ231.2 pm) and a
concomitant lengthening of the Ge–C bonds.
germane with a sterically shielded hydride R2Al–H [R =
CH(SiMe3)2] and heating of the resulting dialkenyl-dialk-
ynylgermane to 260 °C for 10 min. The latter compound
had two GeC3 heterocycles joint by a germanium atom in
a spiro position.[7] Inspired by the facile access to such
heterocycles through hydrometallation of oligoalkynes fol-
lowed by the thermally induced rearrangement of alkenyl-
alkynyl intermediates we started systematic investigations
into the synthesis and the properties of a broad variety of
alkenyl-alkynylgermanes. The results, including the synthe-
sis of important dialkynylgermanes, are reported in this ar-
ticle. This data may help to identify promising starting com-
pounds for an application in 1,1-carbometallation or other
secondary reactions.
Introduction
Silacyclobutenes exhibit pronounced photoluminescent
properties[1] that, compared to silicon-free organic unsatu-
rated compounds, resulted in a redshift of the fluorescence
maxima, an increase of the Stokes’ shifts and a decrease in
quantum yields. 1,1-Carbaboration[2,3] and 1,1-carbalumin-
ation reactions[4] starting with alkynylsilanes proved to be
powerful methods for their facile synthesis. These reactions
proceeded by means of the insertion of the α-carbon atom
of an alkynyl group into a B–C or Al–C bond and the con-
comitant formation of a Si–C bond to the β-carbon atom
of the alkyne.[4] Although 1,1-carbaboration is a relatively
common method for the synthesis of organoboranes,[2,3]
1,1-carbalumination has been reported for the first time
only recently. Hydroalumination[5] of (H5C6)2Si(CϵC–
C6H5)2 with H–Al(CMe3)2 afforded a mixed alkenyl-alk-
ynylsilane (1) (Scheme 1), which in toluene at reflux slowly
rearranged to yield silacyclobutene 2.[4] Compound 2 was
isolated as a THF adduct and had an unsaturated SiC3 het-
erocycle with conjugated endocyclic and exocyclic C=C
bonds and a dialkylaluminium group bonded to one of its
ring carbon atoms (Scheme 1). Similar germacyclobutenes
with unsaturated GeC3 heterocycles are rare. One has been
synthesised by treatment of an acetylene-bridged bis-
(germaethene) with 1,2-dicyanoethene,[6] the other one was
obtained by dual hydroalumination of a tetraalkynyl-
Scheme 1. Generation of a silacyclobutene; the arrows show the
movement of the carbon atoms.
Results and Discussion
Dialkynylgermanes R2Ge(CϵC–RЈ)2
[a] Institut für Anorganische und Analytische Chemie der
Universität Münster,
Dialkyl- and diaryl-dialkynylgermanes were obtained by
standard procedures published previously for the synthesis
of alkynylsilanes.[8] Treatment of dialkyl- or diarylgerma-
Corrensstrasse 30, 48149 Münster, Germany
E-mail: uhlw@uni-muenster.de
www.uni-muenster.de/chemie.ac/uhl/index.html
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nium dichlorides with in situ generated lithium alkynides lated as a colourless solid in high purity and 90% yield
(2 equiv.) afforded the dialkynyl derivatives 3 to 8 by salt (55% overall yield based on GeCl4). The dialkynylgermanes
elimination in high yields (Scheme 2). The syntheses of 3 showed the expected spectroscopic parameters. The stretch-
and 6 have been reported by our group previously.[9]
ing vibrations of the CϵC triple bonds were observed in
the IR spectra at about 2185 and 2150 cm–1, and two reso-
nances of ethynyl C atoms were detected in the characteris-
tic range of the 13C NMR spectra (δ ≈ 115 and 80 ppm).
The molecular structure of 4 (Figure 1) revealed the stan-
dard CϵC bond lengths (120.0 pm on average) and almost
linear Ge–CϵC–C groups (GeCC: 174.6°; CCC: 179.1°).
Scheme 2. Syntheses of dialkynylgermanes.
The synthesis of 9-germafluorene-9,9-dichloride by treat-
ment of GeCl4 with equimolar quantities of biphenyl-2,2Ј-
diyldilithium was reported in the literature,[10] but we were
not able to reproduce this procedure and to obtain the pure
chloride on this route. Instead we isolated mixtures with the
spiro compound 9,9Ј-bis(germafluorene) that could not be
separated by repeated recrystallisation. Therefore, we
started with the dialkynyl-bis(diethylamine)germane 10
(Scheme 3), which is accessible by treatment of dichloride 9
with LiCϵC–CMe3.[11] Compound 10 was transformed to
dichloride 11 by reaction with HCl (yield 94%). Addition
of biphenyl-2,2Ј-diyldilithium resulted in the formation of
dialkynyl-9-germafluorenyl compound 12, which was iso-
Figure 1. Molecular structure and numbering scheme of 4; the ther-
mal ellipsoids are drawn at the 40% probability level; hydrogen
atoms are omitted. Selected bond lengths [pm] and angles [°]: Ge1–
C11 190.0(1), C11–C12 120.0(2), Ge1–C21 190.0(1), C21–C22
120.0(2); C11–Ge1–C21 109.59(5).
Hydroalumination and Hydrogallation of
Dialkynylgermanes
The dialkynylgermanes were treated with H–E(CMe3)2
(E = Al, Ga) in a stoichiometric 1:1 ratio to yield the mixed
alkenyl-alkynyl derivatives by addition of an E–H bond to
one of the alkynyl groups (Scheme 4). The reactions pro-
ceeded in toluene under mild conditions and were finished
within 3 to 21 h at room temperature. Recrystallisation of
the crude products yielded the colourless alkenyl-alk-
ynylgermanes in yields higher than 62%. The dimethylger-
manium compounds 15 and 16 and the n-hexyne derivative
23 were generally isolated as highly viscous liquids. They
were directly obtained in high purity, could be characterised
unambiguously by spectroscopic methods and are appli-
cable in secondary reactions without further purification.
Crystals of 15 were obtained in a low yield of only 15% by
crystallisation from 1,2-difluorobenzene. They were ex-
tremely air sensitive, pyrophoric and difficult to handle.
Compounds 19, 20 and 22 have been published by our
group only recently.[9]
Scheme 3. Synthesis of the fluorenyl compound 12.
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larger charge separation in the tert-butylethynyl com-
pounds,[12] which may essentially be caused by the strong
inductive (+I) effect of the tert-butyl groups. Quantum
chemical calculations with tert-butyl- and phenylethynyldi-
mesitylphosphines[13] confirmed this hypothesis and gave
natural bond orbital (NBO) charges of –0.49/+0.03 and
–0.35/–0.004 for the α- and β-carbon atoms of the tert-butyl
and phenyl compounds, respectively. The knowledge of the
different charge distributions in the C=C and CϵC bonds
of the alkenyl-alkynylgermanes (and the related silanes)
may be highly valuable for their future application in
secondary reactions and the prediction and evaluation of
specific reactivity patterns. The chemical shifts of the α-
carbon atoms of the tert-butylethenyl and -ethynyl groups
of 13 to 18 are systematically shifted to a higher field, and
those of the β-carbon atoms to a lower field relative to the
values observed for compounds 19 to 24. Most of the vin-
ylic H atoms have chemical shifts in a narrow range be-
tween δ = 6.6 and 7.3 ppm. Only the phenylethynyl deriva-
tives 19 to 22 deviate significantly and show stronger low-
field shifts (δ = 7.7 to 8.3 ppm), which may be influenced
by the ring current of the phenyl groups or mesomeric inter-
actions. Usually two absorptions were observed for the
stretching vibrations of the CϵC bonds in the IR spectra
in narrow ranges at about 2150 and 2100 cm–1. A single
absorption was observed only for compounds 14, 21 and 23
at 2122 to 2151 cm–1. Compared to the starting dialk-
ynylgermanes (2185 and 2150 cm–1) a slight shift to smaller
wavenumbers was observed, which may be indicative of the
bridging positions of the alkynyl groups and their interac-
tion to aluminium or gallium atoms. Accordingly, absorp-
tions at 2164 and 2151 cm–1 were found in an alkenyl-alk-
ynylgermanium compound (see the Introduction) in which
bulky bis(trimethylsilyl)methyl groups prevented the inter-
action between Al atoms and the ethynyl groups.[7,9]
Scheme 4. Synthesis of alkenyl-alkynylgermanes.
The NMR spectroscopic characterisation verified the re-
duction of a single alkynyl group of each bis-alkyne. 13C
NMR spectroscopic resonances were observed in the char-
acteristic ranges of ethynyl (Ge–CϵC: δ = 79 to 95 ppm;
Ge–CϵC: δ = 107 to 136 ppm; Table 1) and ethenyl
moieties (Ge–C=C: δ = 136 to 159 ppm; Ge–C=C: δ = 148
to 169 ppm). However, the differences between the reso-
nances of the α- (attached to Ge) and β-carbon atoms (Δδ)
are more pronounced than in the starting bis-alkynes. A
comparison based on all compounds (13 to 24) gave two
clearly separated areas for the ethynyl and ethenyl groups.
The tert-butylethyne derivatives 13 to 18 have relatively
large differences (Δδ) of 38 to 55 ppm between the α- and
β-carbon atoms of the ethynyl and 16 to 33 ppm for the
ethenyl groups. In pairs of aluminium and gallium com-
pounds the Δδ values of the aluminium compounds are
larger. Smaller differences Δδ resulted for the phenyl-, meth-
yl- and n-butylethynyl derivatives 19 to 24 (Δδ = 14 to
28 ppm and 2 to 10 ppm, respectively). These data reflect a
Seven compounds have been characterised by crystal
structure determinations (13–15, 17, 18, 21 and 24; Fig-
ures 2 and 3); the structures of the phenylethyne derivatives
19, 20 and 22 have been reported in a previous publica-
tion.[9] The Ge atoms have a distorted-tetrahedral coordina-
tion sphere and are bound to two alkyl or aryl groups, an
intact alkynyl substituent (CϵC: ≈120 pm) and a C=C
Table 1. Selected chemical shifts of the alkenyl-alkynylgermanium compounds 13 to 24 (δ in ppm).
Element
Ge–CϵC
α-C
Ge–CϵC
β-C
Δδ
Ge–C=C
α-C
Ge–C=C
β-C
Δδ
Vinylic–H
C=C–H
Ref.
13
14
15
16
17
18
Al
Ga
Al
Ga
Al
81.0
81.4
81.2
82.7
78.8
79.4
135.6
121.5
134.7
120.8
133.6
120.4
54.6
40.1
53.5
38.1
54.8
41.0
136.5
141.2
140.6
144.6
135.8
139.2
166.7
163.8
164.0
161.0
169.0
165.9
30.2
22.6
23.4
16.4
33.2
26.7
7.31
6.85
7.04
6.63
7.26
6.83
Ga
[9]
[9]
19
20
21
22
23
24
Al
Al
Ga
Al
Ga
Ga
92.5
93.6
94.8
95.4
83.6
83.1
117.6
116.4
108.4
115.7
111.4
106.8
25.1
22.8
13.6
20.3
27.8
23.7
150.0
155.2
159.2
153.0
148.7
150.0
154.2
152.1
149.7
154.9
154.5
148.2
4.2
3.1
9.5
1.9
5.8
1.8
8.29
8.02
7.71
8.27
6.72
6.70
[9]
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double bond (C=C: ≈134 pm, Table 2). The Al or Ga atoms vance of the E···C interactions is underscored by additional
are in geminal positions to Ge. The high regioselectivity of structural details: (i) The torsion angles across the Ge–C-
these reactions is caused by the electronegativity difference (vinyl) bonds are close to 0° (Table 2), which indicates a
between Ge and the sp-hybridised C atoms, which induces coplanar arrangement of the four atoms AlGeC2 or Ga-
a relatively high negative partial charge at the α-carbon GeC2 and allows an optimum metal–carbon interaction.
atoms of the alkynyl groups. Similar results were obtained (ii) The angles C–Ge–C [94.3 (E = Al) and 97.0° (E = Ga),
upon hydroalumination or hydrogallation of trimethyl- on average] deviate considerably from the tetrahedral angle
silylalkynes.[14–16] Al or Ga atoms and the vinylic H atoms and indicate some steric strain in the molecules. (iii) The Al
are in cis positions across the C=C double bonds, which and Ga atoms do not have a planar environment but are
represent the kinetically favoured arrangement and result situated above the plane of the directly bonded C atoms
from a concerted mechanism of the addition reaction.[15] (34.8 and 24.0 pm, respectively). Similar interactions have
Close intramolecular contacts were observed between the been determined by NMR spectroscopy or crystal structure
Al or Ga atoms and the α-carbon atoms of the ethynyl determination for the hydroboration or hydroalumination
groups. They are considered in the schematic drawing of products of silicon-centred bis-alkynes.[2,17] The intramolec-
Scheme 4 and in Figures 2 and 3 as dashed lines. In accord- ular interactions may help to stabilise the kinetically fa-
ance with the higher Lewis acidity of Al and the larger voured cis-addition products and prevent cis/trans re-
charge separation in the Al–C bonds, the Al···C(ethynyl) arrangement to form the thermodynamically favoured trans
distances [231.2(2) to 244.6(1) pm] are expectedly shorter products.[15]
than the Ga···C(ethynyl) distances (269 pm on average,
Table 2). The Al–C and Ga–C bond lengths to the terminal
tert-butyl groups are about 200 pm. Particularly noteworthy
is the short Al···C distance of 231.2(2) pm in 13
[238.1(2) pm in 15], which represents the shortest distance
detected so far in alkenyl-alkynylsilicon[17] or -germanium
compounds.[9] Although usually these Al···C or Ga···C in-
teractions do not significantly affect the linearity of the Si–
CϵC or Ge–CϵC groups [angles Ͼ170°; 163.3(1)° for 15],
a relatively small angle of 154.4(1)° resulted for 13 [Al–
CϵC 119.4(1)°]. This structural motif resembles that of a
particular form of dimeric dialkylaluminium or -gallium
alkynides with a short Al–C or Ga–C bond to the first
metal atom (Ge–C in 13 to 24), an almost linear E–CϵC
group and a pseudo-side-on coordination of the ethynyl
group to the second metal atom with a relatively long E–C
distance to the α-carbon atom of the triple bond.[18] The
Ge–C distances to the ethynyl group of 13 and 15 are
slightly lengthened compared to biphenyl compound 17
[198.4(1) and 198.5(2) vs. 195.8(1) pm], which may indicate
an activation of the Ge–C bond and may facilitate interest-
ing secondary processes such as insertion or cyclisation re-
actions. Sterically demanding substituents attached to ger-
Figure 2. Molecular structure and numbering scheme of 13; the
thermal ellipsoids are drawn at the 40% probability level; hydrogen
atoms with the exception of the vinylic hydrogen atom are omitted.
Similar structures were observed for compounds 14, 15, 21 and 24
manium may help to further activate these bonds. The rele- (Table 2).
Table 2. Selected structural parameters of the mixed alkenyl-alkynylgermanes 13, 14, 15, 17, 18, 21 and 24.
Element
CϵC
[pm]
C=C
[pm]
E···C
[pm]
C–Ge–C–E
[°]
Ge–CϵC
C–Ge–C
[°][a]
EC3
[°]
[pm][b]
13
14
15
17
18
21
Al
Ga
Al
Al
Ga
Ga
120.5(2)
120.3(2)
120.6(2)
121.0(2)
120.2(3)
120.6(3)
120.9(3)
120.2(2)
119.4(2)
134.0(2)
133.8(2)
133.4(2)
133.7(2)
133.7(2)
133.6(3)
133.5(3)
133.8(2)
133.5(2)
231.2(2)
272.7(2)
238.1(2)
244.6(1)
273.3(2)
261.6(2)
268.2(2)
267.6(2)
272.1(2)
0.80(6)
–7.61(6)
3.0(2)
–0.81(6)
–0.99(7)
0.2(1)
–2.4(1)
3.96(8)
0.83(8)
154.4(1)
171.1(1)
163.3(1)
169.4(1)
175.0(2)
175.9(2)
177.5(2)
175.5(1)
172.6(1)
93.95(6)
98.38(5)
94.24(6)
94.57(5)
98.24(8)
95.71(9)
96.64(8)
96.73(7)
96.52(7)
32.9
23.7
35.5
36.0
25.4
24.1
23.2
23.6
23.8
24
Ga
[a] Angle between the α-carbon atoms of the double and triple bonds. [b] Deviation of E from the plane formed by three directly bonded
carbon atoms.
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mally induced formation of germacyclobutenes and show a
strong correlation between reactivity and 13C NMR spec-
troscopic shift differences.
Experimental Section
General: All procedures were carried out under an atmosphere of
purified argon in dried solvents (n-hexane, n-pentane and cyclopen-
tane with LiAlH4; 1,2-difluorobenzene with molecular sieves; tolu-
ene, diethyl ether and THF with Na/benzophenone). (Me3C)2Al–
H,[19] (Me3C)2Ga–H,[20] Cl2Ge(NEt2)2 (9)[11] and (Et2N)2Ge(CϵC–
CMe3)2 (10)[11] were obtained according to literature procedures.
Commercially available GeCl4 (99.9%, ABCR), Cl2Ge(C6H5)2
(95%, ABCR), Cl2GeMe2 (99%, ABCR), tert-butylethyne, 2,2Ј-di-
brombiphenyl, 1-hexyne, Br–Mg–CϵC–CH3 and diethylamine
were employed as purchased. The assignment of the NMR spectra
is based on HMBC, heteronuclear single quantum coherence
(HSQC), ROESY and distortionless enhancement by polarization
transfer (DEPT135) data.
Figure 3. Molecular structure and numbering scheme of the bi-
phenyl derivative 18; the thermal ellipsoids are drawn at the 40%
probability level; hydrogen atoms with the exception of the vinylic
hydrogen atom are omitted. A similar structure was observed for
compound 17 (Table 2).
(H5C6)2Ge(CϵC–CMe3)2 (4): A solution of n-butyllithium in n-
hexane (1.6 m, 11.0 mL, 17.6 mmol, a small excess amount) was
added slowly to a solution of tert-butylethyne (2.06 mL, 1.38 g,
16.8 mmol) in diethyl ether (50 mL) at –78 °C. The resulting solu-
tion was warmed slowly to room temperature (16 h) and again co-
oled to –78 °C. A solution of diphenylgermanium dichloride
(2.50 g, 8.4 mmol) in diethyl ether (10 mL) was added slowly. The
mixture was stirred for 2 h, slowly warmed to room temperature
and treated with a solution of HCl in water (10%) to dissolve the
precipitate of LiCl. The organic phase was separated, and the aque-
ous phase was extracted three times with diethyl ether (20 mL). The
combined organic phases were dried with MgSO4. The solvent was
removed under vacuum, and the remaining yellow oil was recrystal-
lised from cyclopentane (20/–20 °C) to yield 4 as a colourless solid,
Conclusion
Hydroalumination of various dialkynylgermanes with
H–E(CMe3)2 (E = Al, Ga) afforded a broad variety of
mixed alkenyl-alkynylgermanes (13 to 24). Their structures
exhibit an intramolecular interaction of the coordinatively
unsaturated Al and Ga atoms with the α-carbon atoms of
the remaining alkynyl groups. These interactions are
stronger in the Al compounds, reflect the higher Lewis acid-
ity of Al compared to Ga and result in relatively short Al–
C distances. A lengthening of the Ge–C(alkynyl) bond was
observed in some cases. It may help to activate the Ge–
alkynyl bond and to facilitate secondary reactions such as
the 1,1-carbometallation, which was discussed above (see
the Introduction). Similar compounds with an amine group
bonded to Ge and coordinatively unsaturated Ga atoms
showed a strong intramolecular Ga–N interaction by means
of the lone pair of electrons at N. The significant weakening
of the Ge–N bond was derived from quantum chemical cal-
culations and resulted in a facile amine-alkynyl exchange by
C–H and Ge–N bond activation.[11] Systematic investi-
gations of the spectroscopic properties of the alkenyl-alk-
ynylgermanes 13 to 24 revealed remarkable tendencies in
the 13C NMR spectra. The chemical-shift differences be-
tween both carbon atoms of the C=C and CϵC bonds
strongly depend on the substituents in the β position. Rela-
tively large differences of 25 and 47 ppm were observed for
the tert-butylalkynyl derivatives, whereas almost indepen-
dently of the substituents in the β position (nBu, Me, Ph) all
other compounds showed differences of only 4 and 22 ppm.
These results indicate a larger charge separation in the tert-
butylalkynyl derivatives, which may considerably influence
the reactivity of these compounds and may allow the pre-
diction of specific reaction courses. Preliminary results
1
yield 2.58 g (79%), m.p. (argon; sealed capillary) 78 °C. H NMR
3
(400 MHz, C6D6): δ = 1.13 [s, 18 H, C(CH3)3], 7.13 (t, JH,H
=
7.4 Hz, 2 H, para-H Ph), 7.19 (t, 3JH,H = 7.2 Hz, 4 H, meta-H Ph),
3
4
7.96 (dd, JH,H = 8.0 Hz, JH,H = 1.4 Hz, 4 H, ortho-H Ph) ppm.
13C NMR (100 MHz, C6D6): δ = 28.5 [C(CH3)3], 30.9 [C(CH3)3],
76.1 (GeCϵC), 117.7 (GeCϵC), 128.7 (meta-C Ph), 129.8 (para-C
Ph), 134.2 (ortho-C Ph), 136.3 (ipso-C Ph) ppm. IR (CsI, nujol): ν
˜
= 2181 (s), 2147 (s) [ν(CϵC)]; 2113 (m), 1989 (vw), 1964 (m), 1946
(vw), 1909 (w), 1890 (m), 1847 (sh), 1826 (m), 1775 (m), 1711 (vw),
1661 (m), 1618 (w), 1597 (vw), 1570 (vw), 1558 (vw) (phenyl); 1481
(vw), 1466 (sh), 1454 (vs), 1433 (sh), 1377 (vs) (nujol); 1361 (vs),
1308 (m), 1252 (vs) [δ(CH3)]; 1204 (s), 1186 (m), 1156 (w), 1091
(vs), 1026 (s), 999 (m), 974 (w), 918 (vs), 860 (vw), 779 (w) [ν(CC)];
750 (s), 735 (s) (phenyl); 721 (m) (nujol); 696 (vs) (phenyl); 673 (m),
617 (w), 549 (w), 486 (s), 463 (s) [ν(GeC)] cm–1. MS (EI, 20 eV,
298 K): m/z (%) = 390 (8) [M+], 375 (23) [M+ – CH3], 333 (90)
[M+ – C(CH3)3], 309 (100) [M+ – CCC(CH3)3], 228 (26) [M+ – 2
CCC(CH3)3]. C24H28Ge (389.1): calcd. C 74.1, H 7.3; found C 74.5,
H 7.4.
(H3C)2Ge(CϵC–CMe3)2 (5): A solution of n-butyllithium in n-hex-
ane (1.6 m, 16.9 mL, 27 mmol, a small excess amount) was added
dropwise to
a solution of tert-butylethyne (3.2 mL, 2.13 g,
26 mmol) in diethyl ether (50 mL) at –80 °C. The mixture was
stirred for 1 h and warmed to room temperature. Stirring was con-
tinued for 3 h, and the mixture was cooled to –80 °C. A solution of
dimethylgermanium dichloride (1.5 mL, 2.26 g, 13 mmol) in diethyl
ether (10 mL) was added. After 1 h the mixture was warmed to
room temperature and further stirred for 18 h. The suspension was
verify the applicability of these compounds for the ther- treated with an aqueous solution of HCl (10%) to dissolve LiCl.
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The organic phase was separated, and the aqueous phase was ex-
tracted four times with diethyl ether (20 mL). The combined or-
ganic phases were dried with MgSO4 and filtered. The solvent was
removed under vacuum. Compound 5 was obtained as a colourless
solid after sublimation under vacuum, yield 2.13 g (62%), m.p.
(argon; sealed capillary) 47 °C. 1H NMR (400 MHz, C6D6): δ =
0.50 [s, 6 H, (CH3)2Ge], 1.15 [s, 18 H, C(CH3)3] ppm. 13C{1H}
NMR (100 MHz, C6D6): δ = 1.4 [(CH3)2Ge], 28.3 [GeCCC-
(CH3)3], 31.1 [GeCCC(CH3)3], 79.2 (GeCϵC), 114.6 (GeCϵC)
(w), 856 (w), 770 (w) [ν(CC)]; 739 (s) (nujol); 696 (m), 671 (m)
(phenyl); 619 (w), 468 (s), 430 (vw), 415 (w) [ν(Ge–C)] cm–1. MS
(EI, 20 eV, 313 K): m/z (%) = 306 (100) [M+], 292 (67) [M+ – CH3
+ H], 268 (14) [M+ – CCCH3 + H]. C18H16Ge (305.0): calcd. C
70.9, H 5.3; found C 70.7, H 5.3.
Cl2Ge(CϵC–CMe3)2 (11): A solution of HCl in diethyl ether
(1.0 m, 47 mL, 47 mmol) was added dropwise to a vigorously stirred
solution of 10 (4.50 mL, 4.06 g, 10.7 mmol) in n-hexane (50 mL)
at room temperature. A colourless solid precipitated immediately.
Stirring was continued for 16 h. The suspension was filtered, and
the solvent was removed under vacuum. Compound 11 was ob-
tained as a colourless solid in a high purity, yield 3.08 g (94%),
ppm. IR (CsI, nujol): ν = 2183 (s), 2151 (s) [ν(CϵC)]; 2116 (w),
˜
1861 (vw), 1840 (vw); 1458 (vs), 1375 (s), 1362 (s) (nujol); 1252 (s)
[δ(CH3)]; 1204 (m), 1169 (w), 1096 (w), 1030 (w), 918 (m), 839 (m),
816 (s), 750 (s) [ν(CC)]; 723 (m) (nujol); 617 (m), 594 (m), 550 (w),
480 (m), 401 (m) [ν(GeC)] cm–1. MS (EI, 20 eV, 298 K): m/z (%) =
266 (12) [M+], 251 (100) [M+ – CH3], 209 (13) [M+ – C(CH3)3].
C14H24Ge (265.0): calcd. C 63.5, H 9.1; found C 63.5, H 9.2.
1
m.p. (argon; sealed capillary) 66 °C. H NMR (400 MHz, CDCl3):
δ = 1.29 [s, 18 H, C(CH3)3] ppm. 13C{1H} NMR (100 MHz,
CDCl3): δ = 28.5 [GeCCC(CH3)3], 30.2 [GeCCC(CH3)3], 75.1
[GeCCC(CH ) ], 117.9 [GeCCC(CH ) ] ppm. IR (CsI, nujol): ν =
˜
3 3
3 3
(H5C6)2Ge(CϵC–C4H9)2 (7): Compound 7 was obtained by a pro-
cedure similar to that one given above for the synthesis of 5. It was
isolated as a slightly orange oil that was directly applied for further
reactions, yield 3.06 g (83%). 1H NMR (400 MHz, C6D6): δ = 0.72
2193 (s), 2158 (s), 2129 (sh) [ν(CϵC)]; 1458 (vs), 1377 (vs), 1364
(vs) (nujol); 1302 (w), 1252 (s) [δ(CH3)]; 1202 (m), 1153 (w), 1109
(w), 1030 (w), 964 (vw), 928 (m), 889 (vw), 845 (vw), 758 (s)
[ν(CC)]; 721 (m) (nujol); 556 (w), 505 (m), 490 (m), 424 (s), 415
(m) [ν(Ge–C)] cm–1. MS (EI, 20 eV, 300 K): m/z (%) = 289 (4), 291
(6), 293 (4) [M+ – CH3], 269 (7), 271 (9), 273 (4) [M+ – Cl], 162
(17) {[CCC(CH3)3]2+}, 81 (100) [CCC(CH3)3].
3
(t, JH,H = 7.1 Hz, 6 H, CH2CH2CH2CH3), 1.27 (m, 4 H,
CH2CH2CH2CH3), 2.06 (t, 3JH,H
=
6.8 Hz,
4
H,
=
3
CH2CH2CH2CH3), 7.14 (m, 2 H, para-H Ph), 7.20 (t, JH,H
7.2 Hz, 4 H, meta-H Ph), 7.97 (d, 3JH,H = 6.8 Hz, 4 H, ortho-H Ph)
(H4C6–C6H4)Ge(CϵC–CMe3)2 (12): 2,2Ј-Dibrombiphenyl (3.15 g,
10.1 mmol) was dissolved in diethyl ether (50 mL) and treated with
ppm. 13C{1H} NMR (100 MHz, C6D6):
(CH2CH2CH2CH3), 19.9 (CH2CH2CH2CH3),
δ
=
13.6
22.2
a
solution of n-butyllithium in n-hexane (1.6 m, 12.6 mL,
(CH2CH2CH2CH3), 30.8 (CH2CH2CH2CH3), 78.1 (GeCϵC),
109.6 (GeCϵC), 128.7 (meta-C Ph), 129.9 (para-C Ph), 134.2
20.2 mmol) at –80 °C. After 1 h the mixture was warmed to room
temperature and stirred for 5 h. The solution was added dropwise
to a cooled (–100 °C) solution of 11 (3.10 g, 10.1 mmol) in diethyl
ether (40 mL). After 1 h the mixture was slowly warmed to room
temperature (16 h). LiCl was dissolved by the addition of an aque-
ous solution of HCl (10%). The organic phase was separated, and
the aqueous phase was extracted four times with diethyl ether
(20 mL). The combined organic phases were dried with MgSO4.
After filtration the solvent was removed under vacuum. The residue
was recrystallised from 1,2-difluorobenzene (20/–30 °C) to yield
colourless crystals of compound 12, yield 3.51 g (90%), m.p. (ar-
gon; sealed capillary) 169 °C. 1H NMR (400 MHz, C6D6): δ = 1.05
(ortho-C Ph), 136.1 (ipso-C Ph) ppm. IR (CsI, nujol): ν = 2178 (s)
˜
[ν(CϵC)]; 1954 (w), 1896 (w), 1881 (w), 1815 (w), 1763 (w), 1647
(w), 1585 (w) (phenyl); 1483 (s), 1458 (vs), 1433 (vs), 1377 (vs)
(nujol); 1364 (s), 1354 (sh), 1321 (m), 1302 (m), 1267 (w), 1248 (w)
[δ(CH3)]; 1186 (m), 1157 (w), 1096 (s), 1065 (w), 1026 (m), 999 (m),
974 (w), 947 (m), 925 (w), 914 (w), 897 (w), 853 (m) [ν(CC)]; 735
(s) (nujol); 696 (s), 675 (m) (phenyl); 571 (m), 552 (m), 469 (s), 424
(w) [ν(Ge–C)] cm–1. MS (EI, 20 eV, 333 K): m/z (%) = 390 (36)
[M+], 362 (15) [M+ – ethene], 348 (75) [M+ – propene], 334 (100)
[M+ – butene].
3
4
(H5C6)2Ge(CϵC–CMe)2 (8): A solution of diphenylgermanium di-
chloride (2.0 mL, 2.8 g, 9.4 mmol) in diethyl ether (10 mL) was
added dropwise to a solution of 1-propynylmagnesium bromide in
THF (0.5 m, 38.0 mL, 19.0 mmol) at 0 °C. The solution was
warmed to room temperature, stirred for 1 h and heated under re-
flux conditions for 1 h. After cooling to room temperature the re-
sulting suspension was treated with diethyl ether (40 mL) and a
solution of HCl in water (10%) to dissolve MgX2. The organic
phase was separated, and the aqueous phase was extracted two
times with diethyl ether (20 mL). The combined organic phases
were dried with MgSO4. The solvent was removed under vacuum,
and the remaining brown oil was recrystallised from n-pentane/di-
ethyl ether (20/–30 °C) to yield 8 as a colourless solid, yield 2.10 g
(73%), m.p. (argon; sealed capillary) 74 °C. 1H NMR (400 MHz,
C6D6): δ = 1.50 (s, 1 H, CH3), 7.14 (m, 2 H, para-H Ph), 7.19 (m,
[s, 18 H, C(CH3)3], 7.06 (td, JH,H = 7.3 Hz, JH,H = 1.2 Hz, 2 H,
3
4
CHar), 7.12 (td, JH,H = 7.6 Hz, JH,H = 1.4 Hz, 2 H, CHar), 7.52
(d, 3JH,H = 7.6 Hz, 2 H, CHar), 7.85 (d, 3JH,H = 7.0 Hz, 2 H, CHar)
ppm. 13C{1H} NMR (100 MHz, C6D6): δ = 28.5 [GeCCC(CH3)3],
30.7 [GeCCC(CH3)3], 74.7 [GeCCC(CH3)3], 116.6 [GeCCC-
(CH3)3], 122.1 (Car), 128.7 (Car), 130.8 (C3), 133.4 (Car), 135.8 (C6),
146.3 (C ) ppm. IR (CsI, nujol): ν = 2181 (w), 2147 (w) [ν(CϵC)];
˜
ar
1651 (vw), 1589 (vw) (biphenyl); 1462 (s),1377 (m) (nujol); 1248
(w) [δ(CH3)]; 1200 (w), 1119 (w), 918 (w), 750 (m) [ν(CC)]; 723 (m)
(nujol); 673 (w) (biphenyl); 615 (w), 488 (m), 419 (m) [ν(Ge–C)]
cm–1. MS (EI, 20 eV, 300 K): m/z (%) = 388 (86) [M+], 373 (30)
[M+ – CH3], 331 (100) [M+ – C(CH3)3], 316 (5) [M+ – C(CH3)3 –
CH3]. C24H26Ge (387.1): calcd. C 74.5, H 6.8; found C 74.5, H 6.7.
Synthesis of the Mixed Alkenyl-Alkynylgermanium Compounds 13
to 24
3
4 H, meta-H Ph), 7.91 (d, JH,H = 7.4 Hz, 4 H, ortho-H Ph) ppm.
13C{1H} NMR (100 MHz, C6D6): δ = 4.6 (CϵCCH3), 77.5 General Procedure: Di(tert-butyl)aluminium or -gallium hydride
(CϵCCH3), 104.9 (CϵCCH3), 128.8 (meta-C Ph), 129.9 (para-C (ca. 1.5 to 2.5 mmol) was dissolved in toluene (50 mL) and cooled
Ph), 134.2 (ortho-C Ph), 135.8 (ipso-C Ph) ppm. IR (CsI, nujol): ν
= 2185 (vs), 2143 (m) [ν(CϵC)]; 2122 (sh), 2039 (m), 2012 (m),
1985 (w), 1965 (m), 1913 (w), 1892 (m), 1827 (m), 1775 (m), 1726
to 0 °C (–30 °C for 17). Equimolar quantities of the neat dialk-
ynylgermanium compound (≈1.5 to 2.5 mmol) were added. The
mixture was stirred at 0 °C for 5 min and at room temperature (13,
˜
(m), 1713 (w), 1661 (s), 1645 (m), 1630 (w), 1597 (w), 1566 (s), 1553 17, 18: 2 h; 14, 15, 24: 3 h; 16: 21 h; 23: 3.5 h). The solvent was
(s) (phenyl); 1489 (s) (nujol); 1431 (m), 1406 (w) [δ(CH3)]; 1381 (w)
(nujol); 1337 (vw), 1310 (m), 1267 (m) [δ(CH3)]; 1186 (m), 1168
removed under vacuum and the colourless residue was recrystal-
lised from 1,2-difluorobenzene (20/–30 °C) to yield colourless crys-
(w), 1155 (w), 1092 (s), 1065 (w), 1013 (m), 997 (m), 976 (w), 922 tals. Compounds 15, 16 and 23 were isolated as yellowish, highly
Eur. J. Inorg. Chem. 2014, 2809–2818
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viscous liquids that could not be purified by recrystallisation. The
synthesis of 21 followed a slightly modified procedure: Compound
6 (0.51 g, 1.66 mmol) was dissolved in toluene (10 mL) and added
to a cooled solution (0 °C) of tBu2GaH (0.34 g, 1.84 mmol) in tolu-
ene (25 mL). After 0.5 h the solution was warmed to room tem-
perature and stirred for 2.5 h. The solvent of the yellowish solution
was removed under vacuum. The oily residue was dissolved in
cyclopentane. Colourless compound 21 crystallised upon cooling
to –30 °C.
[CCC(CH3)3], 140.6 [CCHC(CH3)3], 164.0 [CCHC(CH3)3] ppm. IR
(CsI, nujol): ν = 2147 (m), 2097 (m) [ν(CϵC)]; 1605 (m) [ν(C=C)];
˜
1568 (w), 1539 (w); 1460 (vs), 1377 (vs) (nujol); 1362 (s), 1304 (w),
1248 (s) [δ(CH3)]; 1200 (m), 1175 (w), 1067 (w), 1028 (w), 1001
(m), 937 (m), 880 (w), 835 (m), 808 (m), 789 (sh), 750 (w) [ν(CC)];
721 (m) (nujol); 640 (m), 594 (m), 561 (sh), 532 (w), 471 (m), 419
(m) [ν(GeC), ν(AlC)] cm–1. MS (EI, 20 eV, 300 K): m/z (%) = 351
[M+ – CMe3], 268 (39) [M+ – Al{C(CH3)3}2 + H].
1
Characterisation of 16: Yield 0.65 g (100%). H NMR (400 MHz,
Characterisation of 13: Yield 1.11 g (82%), m.p. (argon; sealed
C6D6): δ = 0.66 [s, 6 H, (CH3)2Ge], 1.01 [s, 9 H, CCHC(CH3)3],
capillary) 133 °C. 1H NMR (400 MHz, C6D6): δ = 1.00 [s, 9 H, 1.16 [s, 9 H, CCC(CH3)3], 1.40 {s, 18 H, Ga[C(CH3)3]2}, 6.63 [s, 1
CCHC(CH3)3], 1.03 [s, 9 H, CCC(CH3)3], 1.37 {s, 18 H, Al[C- H, CCHC(CH3)3] ppm. 13C{1H} NMR (100 MHz, C6D6): δ = 4.3
3
3
(CH3)3]2}, 7.13 (t, JH,H = 7.4 Hz, 2 H, para-H Ph), 7.21 (t, JH,H [(CH3)2Ge], 28.2 {Ga[C(CH3)3]2}, 28.7 [CCC(CH3)3], 30.0
= 7.4 Hz, 4 H, meta-H Ph), 7.31 [s, 1 H, CCH(CH3)3], 7.86 (d, [CCHC(CH3)3], 30.7 {Ga[C(CH3)3]2}, 31.4 [CCC(CH3)3], 38.1
3JH,H = 7.4 Hz, 4 H, ortho-H Ph) ppm. 13C{1H} NMR (100 MHz, [CCHC(CH3)3], 82.7 [CCC(CH3)3], 120.8 [CCC(CH3)3], 144.6
C6D6): 18.6 {Al[C(CH3)3]2}, 29.5 [CCC(CH3)3], 29.6 [CCHC(CH ) ], 161.0 [CCHC(CH ) ] ppm. IR (CsI, nujol): ν =
[CCHC(CH3)3], 30.4 [CCC(CH3)3], 31.1 {Al[C(CH3)3]2}, 38.8
[CCHC(CH3)3], 81.0 [CCC(CH3)3], 128.7 (meta-C Ph), 129.7 (para- [ν(C=C)], 1460 (vs), 1360 (vs) (nujol); 1288 (vs) [δ(CH3)]; 1200 (vs),
C Ph), 135.1 (ortho-C Ph), 135.6 [CCC(CH3)3], 136.5 [CCHC- 1084 (m), 1049 (m), 1009 (s), 972 (w), 937 (vw), 893 (w), 808 (vs)
δ
=
˜
3 3
3 3
2156 (m), 2122 (m) [ν(CϵC)]; 1603 (m), 1566 (m), 1501 (w)
(CH3)3], 139.2 (ipso-C Ph), 166.7 [CCHC(CH3)3] ppm. IR (CsI, [ν(CC)]; 625 (m), 564 (m), 552 (m), 519 (s), 498 (m), 465 (s)
nujol): ν = 2145 (w), 2093 (m) [ν(CϵC)]; 1969 (vw), 1952 (vw),
[ν(GeC), ν(GaC)] cm–1. MS (EI, 20 eV, 300 K): m/z (%) = 393 (100)
˜
1879 (vw), 1813 (vw), 1761 (vw), 1649 (vw), 1599 (w), 1560 (w),
1506 (vw) [ν(C=C), phenyl]; 1458 (vs), 1377 (vs) (nujol); 1303 (m),
1244 (m) [δ(CH3)]; 1198 (m), 1155 (w), 1084 (m), 1024 (m), 999
(m), 935 (m), 916 (w), 895 (w), 876 (m), 808 (m), 733 (s) [ν(CC)];
725 (s) (nujol); 696 (m), 669 (w) (phenyl); 577 (s), 501 (m), 457 (m),
419 (m) [ν(GeC), ν(AlC)] cm–1. MS (EI, 20 eV, 300 K): m/z (%) =
474 (0.4) [M+ – C(CH3)3 – H], 392 (18) [M+ – Al{C(CH3)3}2 + H].
C32H47AlGe (531.3): calcd. C 72.3, H 8.9; found C 71.8, H 8.7.
[M+ – C(CH3)3], 268 (4) [M+ – Ga{C(CH3)3}2 + H].
Characterisation of 17: Yield 1.30 g (90%), m.p. (argon; sealed
capillary) 135 °C. 1H NMR (400 MHz, C6D6): δ = 0.77 [s, 9 H,
CCHC(CH3)3], 0.83 [s, 9 H, CCC(CH3)3], 1.51 {s, 18 H, Al[C-
3
(CH3)3]2}, 7.26 [s, 1 H, CCHC(CH3)3], 7.13 (t, JH,H = 7.2 Hz, 2
3
3
H, CHar), 7.18 (t, JH,H = 7.4 Hz, 2 H, CHar), 7.64 (d, JH,H
=
3
7.6 Hz, 2 H, CHar), 7.95 (d, JH,H = 6.9 Hz, 2 H, CHar) ppm.
13C{1H} NMR (100 MHz, C6D6): δ = 18.9 {Al[C(CH3)3]2}, 29.0
[CCHC(CH3)3], 29.3 [CCC(CH3)3], 30.2 [CCC(CH3)3], 30.7
Characterisation of 14: Yield 1.07 g (82%), m.p. (argon; sealed
capillary) 107 °C. 1H NMR (400 MHz, C6D6): δ = 1.06 [s, 9 H, {Al[C(CH3)3]2}, 39.0 [CCHC(CH3)3], 78.8 [CCC(CH3)3], 122.2
CCHC(CH3)3], 1.13 [s,
Ga[C(CH3)3]2}, 6.85 [s, 1 H, CCH(CH3)3], 7.12 (t, JH,H = 7.4 Hz,
9 H, CCC(CH3)3], 1.37 {s, 18 H, (Car), 129.0 (Car), 130.6 (Car), 132.9 (Car), 133.6 [CCC(CH3)3],
3
135.8 [CCHC(CH3)3], 140.5 (Car), 145.0 (Car), 169.0 [CCHC-
3
2 H, para-H Ph), 7.21 (t, JH,H = 7.2 Hz, 4 H, meta-H Ph), 7.90 (CH ) ] ppm. IR (CsI, nujol): ν = 2145 (m), 2100 (m) [ν(CϵC)];
˜
3 3
3
(d, JH,H = 6.8 Hz, 4 H, ortho-H Ph) ppm. 13C{1H} NMR 1911 (w), 1607 (m), 1568 (w), 1506 (m) [ν(C=C), biphenyl]; 1466
(100 MHz, C6D6): δ = 28.8 [CCC(CH3)3], 29.1 {Ga[C(CH3)3]2}, (vs), 1448 (vs), 1377 (vs) (nujol); 1302 (w), 1271 (vw), 1246 (m)
29.9 [CCHC(CH3)3], 31.0 {Ga[C(CH3)3]2}, 31.1 [CCC(CH3)3], 39.1 [δ(CH3)]; 1200 (m), 1153 (m), 1119 (w), 1049 (w), 1028 (w), 999
[CCHC(CH3)3], 81.4 [CCC(CH3)3], 121.5 [CCC(CH3)3], 128.7 (m), 970 (w), 935 (m), 895 (w), 866 (w), 806 (m), 745 (s) [ν(CC)];
(meta-C Ph), 129.4 (para-C Ph), 134.7 (ortho-C Ph), 140.0 (ipso-C
723 (s) (nujol); 671 (w) (phenyl); 615 (w), 586 (m), 557 (w), 534
Ph), 141.2 [CCHC(CH3)3], 163.8 [CCHC(CH3)3] ppm. IR (CsI, (vw), 486 (m), 464 (w), 414 (m) [ν(GeC), ν(AlC)] cm–1. MS (EI,
nujol): ν = 2122 (m) [ν(CϵC)]; 1969 (vw), 1953 (vw), 1894 (vw),
20 eV, 300 K): m/z (%) = 473 (20) [M+ – C(CH3)3], 390 (100) [M+
–
˜
1879 (vw), 1815 (vw), 1759 (vw), 1688 (vw), 1645 (vw), 1599 (m),
1583 (m), 1566 (m) [ν(C=C), phenyl]; 1458 (vs), 1377 (vs) (nujol);
1362 (s), 1301 (w), 1265 (vw), 1249 (s) [δ(CH3)]; 1197 (m), 1186
(w), 1169 (w), 1155 (w), 1078 (s), 1066 (sh), 1062 (w), 1012 (w),
1001 (w), 970 (vw), 937 (w), 895 (w), 846 (w), 806 (m) [ν(CC)]; 734
(s) (paraffin); 698 (s), 671 (m) (phenyl); 582 (m), 549 (w), 538 (sh),
501 (w), 466 (s), 399 (s) [ν(GeC), ν(GaC)] cm–1. MS (EI, 20 eV,
Al{C(CH3)3}2 + H]. C32H45AlGe (529.3): calcd. C 72.6, H 8.6;
found C 72.4, H 8.5.
Characterisation of 18: Yield 0.52 g (76%), m.p. (argon; sealed
capillary) 146 °C. 1H NMR (400 MHz, C6D6): δ = 0.79 [s, 9 H,
CCHC(CH3)3], 0.95 [s,
9 H, CCC(CH3)3], 1.53 {s, 18 H,
Ga[C(CH3)3]2}, 6.83 [s, 1 H, CCHC(CH3)3], 7.15 (t, 3JH,H = 7.1 Hz,
3
4
2 H, CHar), 7.18 (dt, JH,H = 7.3 Hz, JH,H = 1.3 Hz, 2 H, CHar),
7.64 (d, 3JH,H = 7.3 Hz, 2 H, CHar), 7.93 (dd, 3JH,H = 6.7 Hz, 4JH,H
= 1.3 Hz, 2 H, CHar) ppm. 13C{1H} NMR (100 MHz, C6D6): δ =
28.7 [CCC(CH3)3], 29.3 {Ga[C(CH3)3]2}, 29.3 [CCHC(CH3)3], 30.8
{Ga[C(CH3)3]2}, 31.0 [CCC(CH3)3], 38.9 [CCHC(CH3)3], 79.4
[CCC(CH3)3], 120.4 [CCC(CH3)3], 122.3 (Car), 128.8 (Car), 130.3
(Car), 132.9 (Car), 139.2 [CCHC(CH3)3], 140.9 (Car), 145.5 (Car),
333 K): m/z (%) = 517 (100) [M+ – C(CH3)3], 309 (6) [M+
–
(CH3)3CH=CGa{C(CH3)3}2;
Ph2GeCϵCCMe3+],
232
(8)
[PhGeCϵCCMe3+]. C32H47GaGe (574.1): calcd. C 66.9, H 8.3;
found C 66.7, H 8.3.
Characterisation of 15: Yield 0.35 g (100%). Recrystallisation from
1,2-difluorobenzene at –45 °C afforded colourless single crystals of
15 in a low yield of only 15%. These crystals were extremely air
165.9 [CCHC(CH ) ] ppm. IR (CsI, nujol): ν = 2154 (m), 2122
˜
3 3
1
sensitive and ignited spontaneously on contact with air. H NMR
(m) [ν(CϵC)]; 1948 (vw), 1911 (vw), 1614 (w), 1564 (w), 1508 (m)
[ν(C=C)], biphenyl; 1464 (vs), 1377 (vs) (nujol); 1300 (vw), 1269
(400 MHz, C6D6): δ = 0.70 [s, 6 H, (CH3)2Ge], 0.98 [s, 9 H,
CCHC(CH3)3], 1.09 [s, 9 H, CCC(CH3)3], 1.34 {s, 18 H, Al[C- (m), 1246 (m) [δ(CH3)]; 1202 (m), 1157 (w), 1119 (w), 1099 (w),
(CH3)3]2}, 7.04 [s, 1 H, CCHC(CH3)3] ppm. 13C{1H} NMR
(100 MHz, C6D6): δ = 5.6 [(CH3)2Ge], 18.1 {Al[C(CH3)3]2}, 29.4
[CCC(CH3)3], 29.7 [CCHC(CH3)3], 30.6 {Al[C(CH3)3]2}, 30.7
1009 (w), 970 (vw), 934 (m), 899 (w), 856 (w), 841 (w), 745 (s)
[ν(CC)]; 721 (s) (nujol); 671 (w) (biphenyl); 617 (w), 584 (m), 548
(w), 488 (m), 453 (w) [ν(GeC), ν(GeC)] cm–1. MS (EI, 20 eV,
[CCC(CH3)3], 38.2 [CCHC(CH3)3], 81.2 [CCC(CH3)3], 134.7 300 K): m/z (%) = 515 (100) [M+ – C(CH3)3], 459 (3) [M+
–
Eur. J. Inorg. Chem. 2014, 2809–2818
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C(CH3)3 – butene], 433 (4) [M+ – C(CH3)3 – CCC(CH3)3 – H].
C32H45GaGe (572.1): calcd. C 67.2, H 7.9; found C 67.7, H 7.5.
para-H Ph), 7.21 (t, 3JH,H = 7.3 Hz, 4 H, meta-H Ph), 7.83 (d, 3JH,H
= 6.9 Hz, 4 H, ortho-H Ph) ppm. 13C{1H} NMR (100 MHz, C6D6):
δ = 13.6 (CCCH2CH2CH2CH3), 14.1 (CCHCH2CH2CH2CH3),
20.5 (CCCH2CH2CH2CH3), 22.2 (CCCH2CH2CH2CH3), 22.6
Characterisation of 21: Yield 0.50 g (62%), m.p. (argon; sealed
capillary) 81 °C. 1H NMR (400 MHz, C6D6): δ = 0.58 (s, 6 H,
GeCH3), 1.38 {s, 18 H, Ga[C(CH3)3]2}, 6.93 (m, 3 H, meta-H Ph-
alkyne/para-H Ph-alkyne), 7.06 (t, 3JH,H = 7.2 Hz, 1 H, para-H Ph-
(CCHCH2CH2CH2CH3),
(CCCH2CH2CH2CH3),
28.6
31.0
{Ga[C(CH3)3]2},
{Ga[C(CH3)3]2},
31.0
31.9
(CCHCH2CH2CH2CH3), 40.8 (CCHCH2CH2CH2CH3), 83.6
(CCCH2CH2CH2CH3), 111.4 (CCCH2CH2CH2CH3), 128.7 (meta-
C Ph), 129.5 (para-C Ph), 134.8 (ortho-C Ph), 137.7 (ipso-C Ph),
148.7 (CCHCH2CH2CH2CH3), 154.5 (CCHCH2CH2CH2CH3)
3
alkene), 7.14 (t, JH,H = 7.5 Hz, 2 H, meta-H Ph-alkene), 7.20 (d,
3JH,H = 7.2 Hz, 2 H, ortho-H Ph-alkene), 7.51 (m, 2 H, ortho-H
Ph-alkyne), 7.71 (s, 1 H, GeC=CH) ppm. 13C{1H } NMR
(100 MHz, C6D6): δ = 1.5 (GeCH3), 28.9 {Ga[C(CH3)3]2}, 30.6
{Ga[C(CH3)3]2}, 94.8 (PhCCGe), 108.4 (PhCCGe), 127.3 (ortho-C
Ph-alkene), 127.5 (para-C Ph-alkene), 128.6 (meta-C Ph-alkyne/
meta-C Ph-alkene), 129.5 (para-C Ph-alkyne), 132.9 (ortho-C Ph-
alkyne), 142.2 (ipso-C Ph-alkene), 149.7 (PhCHC), 159.2 (PhCHC)
ppm. IR (CsI, nujol): ν = 2151 (m) [ν(CϵC)]; 1950 (w), 1892 (w),
˜
1879 (w), 1815 (w), 1595 (m), 1568 (w) [ν(C=C), phenyl]; 1481 (m),
1464 (vs) (nujol); 1431 (s) [δ(CH3)]; 1377 (m) (nujol); 1362 (m),
1301 (w), 1244 (w) [δ(CH3)]; 1184 (m), 1175 (m), 1090 (s), 1047
(w), 1024 (m), 1013 (m), 1001 (m), 970 (w), 941 (w), 899 (w), 851
(w), 808 (s) [ν(CC)]; 733 (vs) (nujol); 698 (vs), 673 (w) (phenyl); 594
(w), 521 (m), 467 (vs), 430 (m) [ν(GeC), ν(GaC)] cm–1. MS (EI,
ppm. IR (CsI, nujol): ν = 2131 (s) [ν(CϵC)]; 1940 (w), 1892 (vw),
˜
1796 (vw), 1746 (vw), 1595 (w), 1582 (sh) [ν(C=C), phenyl]; 1489
(w), 1468 (s) (nujol); 1445 (s), 1412 (m) [δ(CH3)]; 1381 (vs) (nujol);
1359 (m), 1308 (vw), 1271 (vw), 1238 (s) [δ(CH3)]; 1211 (m), 1173
(w), 1101 (vw), 1170 (s), 1028 (m), 1009 (vw), 964 (vw), 939 (w),
914 (w), 872 (m), 841 (m), 808 (vs), 756 (s) [ν(CC)]; 737 (s) (nujol);
691 (s), 665 (vw) (phenyl); 606 (s), 584 (m), 563 (m), 534 (m), 507
(w), 489 (vw), 461 (w), 426 (m) [ν(GeC), ν(GaC)] cm–1. MS (EI,
20 eV, 298 K): m/z (%) = 518 (100) [M+ – butene], 494 (2) [M+
CCCMe3 + H], 462 (5) [M+ – 2 butene], 310 (54) [M+
Ga{C(CH3)3}2 – CCCH2CH2CH2CH3].
–
–
Characterisation of 24: Yield 0.57 g (70%), m.p. (argon; sealed cap-
illary) 139 °C. 1H NMR (400 MHz, C6D6): δ = 1.33 {s, 18 H,
Ga[C(CH3)2]}, 1.52 (s, 3 H, CCCH3), 1.81 (d, 3JH,H = 6.1 Hz, 3 H,
20 eV, 353 K): m/z (%) = 433 (100) [M+ – C(CH3)3], 307 (6) [M+
–
Ga{C(CH3)3}2], 204 (70) [Me2Ge(H)CϵCPh+]. C26H35GaGe
3
CCHCH3), 6.70 (q, JH,H = 6.1 Hz, 1 H, CCHCH3), 7.14 (m, 2 H,
(489.9): calcd. C 63.7, H 7.2; found C 63.2, H 7.2.
para-H Ph), 7.19 (m, 4 H, meta-H Ph), 7.80 (m, 4 H, ortho-H Ph)
ppm. 13C{1H} NMR (100 MHz, C6D6): δ = 5.1 (CCCH3), 25.9
(CCHCH3), 28.6 {Ga[C(CH3)3]2}, 30.7 {Ga[C(CH3)3]2}, 83.1
1
Characterisation of 23: Yield 1.280 g (100%). H NMR (400 MHz,
3
C6D6): δ = 0.70 (t, JH,H = 7.1 Hz, 3 H, CCHCH2CH2CH2CH3),
3
0.72 (t, JH,H = 7.1 Hz, 3 H, CCCH2CH2CH2CH3), 1.10 (m, 2 H, (CCCH3), 106.8 (CCCH3), 128.7 (meta-C Ph), 129.6 (para-C Ph),
CCHCH2CH2CH2CH3), 1.22 (m, 2 H, CCCH2CH2CH2CH3), 1.24 134.9 (ortho-C Ph), 137.2 (ipso-C Ph), 148.2 (CCHCH3), 150.0
(m,
2
H, CCHCH2CH2CH2CH3), 1.34 (m,
2
H, (CCHCH ) ppm. IR (CsI, nujol): ν = 2178 (w), 2151 (w) [ν(CϵC)];
˜
3
CCCH2CH2CH2CH3), 1.38 {s, 18 H, Ga[C(CH3)3]2}, 2.13 (t, 3JH,H
1599 (w) [ν(C=C)]; 1454 (vs), 1375 (vs) (nujol); 1304 (w), 1269 (w)
[δ(CH3)]; 1169 (w), 1155 (w), 1090 (m), 1026 (w), 1009 (w), 991
3
= 7.1 Hz, 2 H, CCCH2CH2CH2CH3), 2.21 (dt, JH,H = 7.7 Hz,
3JH,H = 7.1 Hz, 2 H, CCHCH2CH2CH2CH3), 6.72 (t, JH,H
=
(w), 935 (w), 918 (w), 889 (w), 847 (w), 821 (sh), 808 (w), 754 (w)
3
3
6.5 Hz, 1 H, CCHCH2CH2CH2CH3), 7.13 (t, JH,H = 7.7 Hz, 2 H, [ν(CC)]; 696 (m), 673 (w) (phenyl); 627 (w), 527 (w), 490 (w), 463
Table 3. Crystal data and structure refinement for compounds 4, 13, 14 and 15.[a]
4
13
14
15
Empirical formula
Temperature [K]
Crystal system
Space group
a [pm]
b [pm]
c [pm]
C24H28Ge
153(2)
C32H47AlGe
153(2)
C32H47GaGe
153(2)
C22H43AlGe
153(2)
monoclinic
P21/c (no. 14)
932.18(5)
1445.81(8)
1908.2(1)
90
95.829(2)
90
2.5585(2)
4
monoclinic
P21/c (no. 14)
1758.30(6)
1022.55(4)
1163.99(4)
90
91.242(2)
90
2.0923(1)
4
triclinic
triclinic
¯
¯
P1 (no. 2)
P1 (no. 2)
911.35(1)
913.06(4)
1297.79(2)
1334.88(2)
81.8557(7)
85.7151(7)
84.3400(7)
1.55231(4)
2
1121.05(4)
1741.56(7)
71.3369(5)
79.2417(6)
72.9041(5)
1.6058(1)
α [°]
β [°]
γ [°]
V [nm3]
Z
2
Dcalcd. [gcm–3]
1.235
1.137
1.187
1.057
μ [mm–1]
1.467 (Mo-Kα)
0.47ϫ0.35ϫ0.18
2.30 Յ 30.01
–24 Յ h Յ 24
–14 Յ k Յ 14
–16 Յ l Յ 16
6101 (Rint = 0.0225)
232
1.032 (Mo-Kα)
0.39ϫ0.28ϫ0.18
2.06 Յ 30.01
–12 Յ h Յ 12
–18 Յ k Յ 18
–18 Յ l Յ 18
8992 (Rint = 0.0240)
350
1.791 (Mo-Kα)
0.30ϫ0.28ϫ0.15
1.24 Յ 30.14
–12 Յ h Յ 12
–15 Յ k Յ 15
–24 Յ l Յ 24
9363 (Rint = 0.0135)
319
1.233 (Mo-Kα)
0.34ϫ0.12ϫ0.05
2.20 Յ 30.09
–13 Յ h Յ 13
–20 Յ k Յ 20
–26 Յ l Յ 26
7472 (Rint = 0.0290)
231
Crystal size [mm]
Θ range [°]
Index ranges
Independent reflections
Parameters
R1 [IϾ2σ(I)]
wR2 (all data)
0.0213 (5543)
0.0582
0.0310 (8007)
0.0820
0.0238 (7913)
0.0633
0.0307 (6187)
0.0798
Max./min. residual electron
+0.436/–0.183
+0.935/–0.360
+0.350/–0.349
+0.373/–0.251
density [1030 em–3]
[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|; wR2 = {Σ[w(F2o – Fc2)2]/Σ[w(F2o)2]}1/2. Programme SHELXL-97.[20]
2816
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FULL PAPER
Table 4. Crystal data and structure refinement for compounds 17, 18, 21 and 24.[a]
17
18
21
24
Empirical formula
Temperature [K]
Crystal system
Space group
a [pm]
b [pm]
c [pm]
C32H45AlGe
153(2)
C35H47FGaGe
153(2)
C26H35GaGe
153(2)
orthorhombic
P212121 (no. 19)[b]
1100.91(9)
1389.9(1)
3370.3(3)
90
90
90
C26H35GaGe
153(2)
triclinic
triclinic
triclinic
¯
¯
¯
P1 (no. 2)
P1 (no. 2)
P1 (no. 2)
884.13(2)
917.54(7)
1121.49(8)
1676.8(1)
90.225(6)
94.100(6)
104.283(6)
1.6674(2)
2
820.0(2)
1248.17(2)
1421.49(3)
79.4098(8)
87.3022(9)
87.6891(9)
1.53945(5)
2
1435.4(3)
2147.8(4)
88.37(3)
81.13(3)
87.08(3)
2.4940(9)
4
1.305
2.294 (Mo-Kα)
0.25ϫ0.08ϫ0.08
1.70 Յ 28.29
–10 Յ h Յ 10
–19 Յ k Յ 19
–28 Յ l Յ 28
80565[c]
α [°]
β [°]
γ [°]
V [nm3]
5.1571(7)
8
1.262
Z
Dcalcd. [gcm–3]
1.142
1.253
μ [mm–1]
1.040 (Mo-Kα)
0.51ϫ0.15ϫ0.06
1.46 Յ 30.10
–12 Յ h Յ 12
–17 Յ k Յ 17
–20 Յ l Յ 20
8960 (Rint = 0.0244)
319
1.735 (Mo-Kα)
0.30ϫ0.25ϫ0.05
1.87 Յ 27.94
–12 Յ h Յ 12
–14 Յ k Յ 14
–22 Յ l Յ 21
7939 (Rint = 0.0447)
364
2.218 (Mo-Kα)
0.46ϫ0.27ϫ0.24
1.58 Յ 30.23
–15 Յ h Յ 15
–19 Յ k Յ 19
–47 Յ l Յ 47
15237 (Rint = 0.0362)
521
Crystal size [mm]
Θ range [°]
Index ranges
Independent reflections
Parameters
522
R1 [IϾ2σ(I)]
wR2 (all data)
0.0276 (7934)
0.0812
0.0280 (6157)
0.0685
0.0297 (13026)
0.0634
0.0487
0.1183
Max./min. residual electron density
+0.375/–0.246
+0.584/–0.492
+0.434/–0.326
+1.731/–0.982
[1030 em–3]
[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|; wR2 = {Σ[w(F2o – Fc2)2]/Σ[w(F2o)2]}1/2. Programme SHELXL-97;[20] solutions by direct methods, full-matrix
refinement with all independent structure factors. [b] Flack parameter: 0.051(6). [c] Twinned crystal; HKLF-5 refinement without averag-
ing of reflections.
(m), 432 (w) [ν(GeC), ν(GaC)] cm–1. MS (EI, 20 eV, 300 K): m/z
Acknowledgments
(%) = 432 (91) [M+ – C(CH3)3 – H], 376 (4) [M+ – 2 C(CH3)3], 308
(11) [M+ – Ga{C(CH3)3}2 + H]. C26H35GaGe (489.9): calcd. C
The authors are grateful to the Deutsche Forschungsgemeinschaft
63.7, H 7.2; found C 63.5, H 7.1.
(DFG) for generous financial support.
Crystal Structure Determinations: Single crystals were obtained di-
rectly from the reaction mixtures as described above. Crystals of
compound 15 were obtained by recrystallisation from 1,2-difluo-
robenzene at –45 °C. They are extremely air sensitive and could
be mounted on the diffractometer only with great difficulty. The
crystallographic data were collected with a Bruker QUAZAR and
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Eur. J. Inorg. Chem. 2014, 2809–2818
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Received: March 5, 2014
Published Online: May 8, 2014
Eur. J. Inorg. Chem. 2014, 2809–2818
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© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim