A synthetic equivalent of a germanone derivative

Article abstract of DOI:10.1002/ejic.200800494

Reaction of two molar equivalents of 2,6-bis(diisopropylaminomethyl) phenyllithium (ArLi) with tetramethoxygermane afforded the colourless crystalline dimethoxy bis[2,6-bis(diisopropylaminomethyl)phenyl]germane Ar ₂Ge(OMe)₂ (1) in good yield. Treatment of 1 with AgF/H₂O led to the fluorohydroxy derivative Ar₂Ge(F)OH (2), which was characterized, among other techniques, by single-crystal structure analysis. The corresponding lithio compound Ar₂Ge(F)OLi (3) obtained from 2 by reaction with tBuLi behaves as a synthetic equivalent of the heavier analogue of ketone [Ar₂Ge=O, 5]. Germanone 5 could not be isolated even at low temperature due to the impossibility of dissociating it from LiF. Treatment of 3 with various reactants on the basis of the known reactivity of ketones led to the expected products. The reaction of 3 with H₂O led, as expected, quantitatively to the germanium gem-diol Ar₂Ge(OH)₂ (6) as colourless crystals. Such gem-diols are scarce compounds and only a few are structurally known; in our case, 6 is stabilized by a hydrogen linkage between the hydrogen atoms of the alcohol functionalities and the nitrogen atoms. Other trapping reactions of 3 were investigated with tBuLi and methanol, and the corresponding germanols Ar ₂Ge(tBu)OH (7) and Ar₂Ge(OMe)OH (8) were isolated after hydrolysis in good yields. Attempts to eliminate LiF from 3 by using the chelating agent 1,4,7,10-tetraoxacyclododecane (12-crown-4) allowed us to isolate lithio complex 9. Generation of germanones from fluorohydroxygermanes and their lithio derivatives appears to be a new promising method.

Full text of DOI:10.1002/ejic.200800494

FULL PAPER
DOI: 10.1002/ejic.200800494
A Synthetic Equivalent of a Germanone Derivative
Eric Bonnefille,[a] Stéphane Mazières,*[a] Christine Bibal,[a] Nathalie Saffon,[b]
Heinz Gornitzka,[a] and Claude Couret*[a]
Keywords: Germanium / Alcohols / Fluorine / Germanone / Germanolate
Reaction of two molar equivalents of 2,6-bis(diisopropyl-
aminomethyl)phenyllithium (ArLi) with tetramethoxyger-
mane afforded the colourless crystalline dimethoxy bis[2,6-
bis(diisopropylaminomethyl)phenyl]germane Ar2Ge(OMe)2
(1) in good yield. Treatment of 1 with AgF/H2O led to the
fluorohydroxy derivative Ar2Ge(F)OH (2), which was charac-
terized, among other techniques, by single-crystal structure
analysis. The corresponding lithio compound Ar2Ge(F)OLi
tively to the germanium gem-diol Ar2Ge(OH)2 (6) as colour-
less crystals. Such gem-diols are scarce compounds and only
a few are structurally known; in our case, 6 is stabilized by a
hydrogen linkage between the hydrogen atoms of the
alcohol functionalities and the nitrogen atoms. Other trap-
ping reactions of 3 were investigated with tBuLi and meth-
anol, and the corresponding germanols Ar2Ge(tBu)OH (7)
and Ar2Ge(OMe)OH (8) were isolated after hydrolysis in
(3) obtained from 2 by reaction with tBuLi behaves as a syn- good yields. Attempts to eliminate LiF from 3 by using the
thetic equivalent of the heavier analogue of ketone
[Ar2Ge=O, 5]. Germanone 5 could not be isolated even at
low temperature due to the impossibility of dissociating it
from LiF. Treatment of 3 with various reactants on the basis
of the known reactivity of ketones led to the expected prod-
ucts. The reaction of 3 with H2O led, as expected, quantita-
chelating agent 1,4,7,10-tetraoxacyclododecane (12-crown-
4) allowed us to isolate lithio complex 9. Generation of ger-
manones from fluorohydroxygermanes and their lithio deriv-
atives appears to be a new promising method.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
their vibrational spectra.[6,7] During the last decade, many
attempts were made to obtain more stable germanones. In
spite of the use of bulky substituents, almost all of them
were unsuccessful. The oxidation of the hindered amido-
Introduction
Due to the rich chemistry of organic unsaturated func-
tionalities, the study of their metallated analogues presents
a very high interest for organometallic chemists. In the field
of group 14 metal derivatives, the first evidence for ger-
mylated analogues of ketones containing the Ge=O moiety
was reported in 1971.[1] Since then, several synthetic routes
to germanones have been described. Nevertheless up until
recently only indirect evidence was available to suggest their
transient existence.[2–10]
Many starting materials leading to these highly elusive
species are often heterocycles with a germanium–oxygen
linkage: 2-germaoxetanes,[1,4] 2-germa-1,5-dioxanes,[11] vari-
ous seven-membered rings,[12] oxazagermetanes[8a] and di-
oxagermetanes.[9] Other sources of transient germanones in-
clude the thermal decomposition of germanium oxides[7,12]
or germa-epoxides[7] and oxidation of germylenes.[3,10] Ele-
mentary germanones with R = H or Me were trapped at
low temperature in argon matrices and were identified by
germylene precursor [(Me3Si)2N]2Ge afforded the dimeric
[10a]
dioxadigermetane {[(Me3Si)2N]2GeO}2
and an attempt
to synthesize Mes*2GeO (Mes* = 2,4,6-tBu3C6H2) by the
same method led, after C–H insertion, to a germaindan-
ol.[10c] The gem-diol derivative Ar2Ge(OH)2 (Ar = 2,6-
Mes2C6H3; Mes = 2,4,6-Me3C6H2) was isolated as a prod-
uct from the corresponding germanone.[13] In order to get
more stable derivatives especially by kinetic stabilization,
the use of very bulky aryl ligands (tip = 2,4,6-iPr3C6H2 and
tbt = 2,4,6-[CH(SiMe3)2]3C6H2) allowed Tokitoh et al. to
generate the germanone (tip)(tbt)Ge=O, stable for a few
minutes in solution.[14] In contrast, the oxidation of the li-
gand-protected strain-free diarylgermylenes Ge(bisap)2 and
Ge(triph)2 [bisap = 2,6-bis(1Ј-naphthyl)phenyl and triph =
2,4,6-triphenylphenyl] led to the germanones (bisap)2Ge=O
and (triph)2Ge=O as solids that were characterized by spec-
troscopic methods but without any structural determination
to confirm a monomeric structure.[15]
[a] Laboratoire Hétérochimie Fondamentale et Appliquée, UMR
5069 (CNRS), Université Paul Sabatier,
In this paper we present a novel route to germanones
from fluorohydroxygermanes. The lithio derivative Ar2Ge-
(F)OLi can be seen as a synthetic equivalent of the ger-
manone Ar2Ge=O complexed with LiF, where Ar is the 2,6-
bis(diisopropylaminomethyl)phenyl ligand, previously suc-
118 route de Narbonne, 31062 Toulouse Cedex 9, France
Fax: +33-5-61558204
E-mail: mazieres@chimie.ups-tlse.fr
[b] Structure Fédérative Toulousaine en Chimie Moléculaire, FR
2599, Université Paul Sabatier,
118 route de Narbonne, 31062 Toulouse Cedex 9, France
4242
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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A Synthetic Equivalent of a Germanone Derivative
cessfully used for the stabilization of an arylchlorogermyl-
ene[16] and a diazogermylene, precursor of the first germaal-
kyne.[17]
Results and Discussion
Synthesis
Diaryldimethoxygermane (1) Ar2Ge(OMe)2 {Ar = 2,6-
[CH2N(iPr)2]2C6H3} was synthesized by reaction between
the tetramethoxygermane and two equivalents of ArLi in
accordance with that outlined in Scheme 1. Among various
fluorination agents such as HF, SbF3, Me3SnF or AgF, sil-
ver fluoride led to the best results. Thus, warming 1, AgF
and H2O in toluene to 110 °C for several hours leads solely
to fluorodiarylhydroxygermane 2 in high yield (Scheme 2).
Compound 2 probably arises from the hydrolysis of the pre-
viously formed Ar2Ge(F)OMe but we cannot exclude the
fluorine substitution of Ar2Ge(OH)2 obtained by the total
hydrolysis of 1.
Figure 1. Structure of 2 (thermal ellipsoid level 50%); nonrelevant
H atoms are omitted and iPr groups are simplified for clarity. Se-
lected bonds and angles: Ge1–O1 1.7363(12) Å, Ge1–F1
1.7543(10) Å, N1–O1 2.709(2) Å, O1–Ge1–F1 104.80(6)°.
The reaction of 2 with an equimolar amount of tert-bu-
tyllithium in diethyl ether at 0 °C affords the expected
lithiogermanolate 3 (Scheme 3). Compound 3 was charac-
terized by quenching the reaction with chlorotrimethyl-
silane, leading nearly quantitatively to the fluorosiloxyger-
mane Ar2Ge(F)OSiMe3 (4).
Scheme 3.
Warming 3 to room temperature and up to 70 °C did not
cause the elimination of lithium fluoride and did not al-
lowed us to isolate the expected germanone Ar2Ge=O (5)
or an oligomeric form (Ar2GeO)n. Indeed, Lappert et al.
obtained the dimer {[(Me3Si)2N]2GeO}2 when they tried to
synthesize [(Me3Si)2N]2Ge=O.[10a] In addition, the reaction
of one equivalent of water with 3 at room temperature led
to the dihydroxydiarylgermane Ar2Ge(OH)2 (6; Figure 2,
Table 2) in nearly quantitative yield. This product can be
Scheme 1.
Scheme 2.
As expected, 2 exhibits high acidity through the hydroxy seen as the water adduct of the germanone (Scheme 4).
hydrogen atom (1H NMR: δ(OH) = 9.72 ppm in C6D6), as
gem-Diols such as 6 are scarce compounds in germanium
a result of the strong withdrawing effect from the fluorine chemistry. To the best of our knowledge, only five have been
atom. The important acidic character of the OH hydrogen structurally described: (2,6-Mes2C6H3)2Ge(OH)2,[13] tBu2-
atom was first established in solution by the infrared spec- Ge(OH)2,[20,21] [(Me3Si)2N]2Ge(OH)2,[22] HN(CH2CH2O)2-
trum, where a strong associated absorption is observed at Ge(OH)2,[23] (tpp)Ge(OH)2 (tpp = meso-tetraphenylporphy-
3638 cm–1. Due to the prochirality of the germanium atom, rinato);[24] some others, that is, Mes2Ge(OH)2,[25] (2,6-
1
[27]
benzylic protons appear in the H NMR spectra as a well- Me2C6H3)2Ge(OH)2,[26] (C6Cl5)2Ge(OH)2
and tbt(tip)-
[9]
defined AB system. Moreover, the X-ray structure analysis Ge(OH)2 have been characterized by usual spectroscopic
of 2 (Figure 1, Table 2) shows a coordinative N···H interac- methods.
tion in the solid state. This hydrogen bonding between the
We have also synthesized 6 by direct treatment of 1 with
OH hydrogen atom and the nitrogen atom of an arm is a solution of Bu4NF in thf containing ca. 5% water (see
evidenced by a N···O distance of 2.709(2) Å, which indi- Experimental Section, method B).
cates a quite strong N···H interaction in the solid state,[18]
In the X-ray structure of 6, the Ge–O bonds
but this system is dynamic in solution and involves the ni- [1.7522(11) Å] are slightly shorter than the lengths usually
trogen atoms of the four arms. The germanium–oxygen observed for this kind of compound.[19a] This is probably
[1.7363(12) Å] and the germanium–fluorine [1.7543(10) Å] related to the hydrogen bonds between the nitrogen atoms
bonds are in the average range for typical single bonds.[19]
of the side chain and OH hydrogen atoms (see below),
Eur. J. Inorg. Chem. 2008, 4242–4247
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E. Bonnefille, S. Mazières, C. Bibal, N. Saffon, H. Gornitzka, C. Couret
FULL PAPER
groups. This is quite different to Power’s gem-diol,[13] where
a nonclassical hydrogen-bonding interaction of the OH
groups with the mesityl ring substituents was reported.
With gem-diol 6, the observed distance between the nitro-
gen and oxygen atoms [2.737(3) Å] is appreciably shorter
than the van der Waals distance for such a N···H–O linkage
(2.80 Å)[18] and confirms strong interactions that lead to
this monomeric bicyclic structure. A summary of crystallo-
graphic data for 1, 2 and 6 is gathered in Table 2.
In 1 (Figure 3), due to the absence of hydrogen bonding
the strain-free arrangement of O–Ge–O allows a less wide
angle [106.76(10)°] than for 6, and in addition, the C–Ge–
C angle is smaller [116.43(9)°].
Figure 2. Structure of 6 (thermal ellipsoid level 50%); nonrelevant
H atoms are omitted and iPr groups are simplified for clarity. Se-
lected bonds and angles: Ge1–O1 and Ge1–O1A 1.7522(11) Å,
Ge1–C1 and Ge1–C1A 1.9668(16) Å, N1–O1 and N1A–O1A
2.737(3) Å, O1–Ge1–O1A 107.84(9)°, C1–Ge1–C1A 118.46(10)°.
Figure 3. Structure of 1 (thermal ellipsoid level 50%); nonrelevant
H atoms are omitted and iPr groups are simplified for clarity. Se-
lected bonds and angles: Ge1–O1 1.779(1) Å, Ge1–C1 1.965(2) Å,
O1–Ge1–O1A 106.76(10)°, C1–Ge1–C1A 116.43(9)°.
Germanone reactivity of lithio derivative 3 was been evi-
denced by a trapping reaction with tert-butyllithium
(Scheme 4). Indeed, the addition of two equivalents of
tBuLi to 2 leads, after warming to room temperature and
Scheme 4.
which lock the geometry. These values are among the short- hydrolysis, to germanol 7 in 60% yield.
est Ge–O bond lengths in relation to the five other known
Actually, the germanone reactivity of 3 only occurs at ca.
germadiol structures (Table 1). As for the Ge–C bonds, 10 °C. Indeed, quenching the reaction mixture with meth-
their lengths [1.966(16) Å] for 6 are close to the average anol at 0 °C leads to starting material 2. Under similar con-
bond lengths observed for the other diols.
ditions, quenching with chlorotrimethylsilane gives siloxy-
For compound 6, the C–Ge–C angle [118.46(10)°] is sig- germane Ar2Ge(F)OSiMe3 (4) (Scheme 3). In contrast, at
nificantly smaller than the C–Ge–C angles observed in room temperature, the addition of one equivalent of meth-
tBu2Ge(OH)2 [122.5(3)°] and in (2,6-Mes2C6H3)2Ge(OH)2 anol to a solution of 3 reveals a germanone reactivity and
[122.3(1)°]. Similar differences occur for the O–Ge–O leads to germanol 8 with 80% yield (Scheme 4). This mis-
angles: 6 presents the largest angle [107.84(9)°] in relation cellaneous reactivity allows us to present lithiogermanolate
to the two other structures: 103.5(2) and 105.31(8)°, respec- 3 as a synthetic equivalent of germanone 5. Indeed, prod-
tively. This observation could be also related to the main ucts 6, 7 and 8 can be considered as germanone adducts
feature of this compound, which is the presence of strong from the reactants H2O, tBuLi/H2O and MeOH, respec-
hydrogen bonds (three-centre, four-electron linkage) be- tively. Unfortunately, it was not possible to grow single crys-
tween nitrogen atoms of the side chains and the hydroxy tals of 3, but we did enhance its germanone character by
Table 1. Comparative bond lengths (Å) and angles (°) for structurally characterized gem-germanediols R2Ge(OH)2.
[20]
[13]
[22]
[23]
R2
[2,6-(iPr2NCH2)2C6H3]2 (6)
(tBu)2
(2,6-Mes2C6H3)2
[(Me3Si)2N]2
[HN(CH2CH2O)2]2
(tpp)[24]
1.809(3)
Ge–O
1.7522(11)
1.781(4)
1.779(4)
1.966(7)
122.5(3)
103.5(2)
1.802(2)
1.782(2)
1.978(2)
122.3(1)
105.31(8)
1.779(5)
1.751(5)
–
1.793(3)
1.762(4)
–
Ge–C
C–Ge–C
O–Ge–O
1.9668(16)
118.46(10)
107.84(9)
–
–
111.4(4)
96.80(2)
180.0(1)
4244
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 4242–4247

A Synthetic Equivalent of a Germanone Derivative
chelating the lithium metal in order to bring about the eli-
mination of LiF. Using the chelating agent 1,4,7,10-tetra-
oxacyclododecane (12-crown-4), which is specific for this
purpose, we obtained lithio complex 9 in quantitative yield
(Scheme 5).
Experimental Section
General Procedures: All reactions were carried out by using stan-
dard Schlenk and high-vacuum-line techniques under an inert at-
mosphere (Ar or N2). All solvents were purified by conventional
methods, distilled and degassed immediately before use. The lithio
compound ArLi [Ar = 2,6-bis(diisopropylaminomethyl)phenyl][16]
[29]
and the tetramethoxygermane Ge(OMe)4
were synthesized ac-
cording to literature procedures. NMR spectra were recorded with
a
Bruker AVANCE-300 spectrometer at 300.1 MHz (1H),
75.4 MHz (13C) and 282.4 MHz (19F) for samples in C6D6 at 25 °C
(except for 9: 35 °C). Chemical shifts are reported relative to SiMe4
or CCl3F. Infrared data were recorded with a Perkin–Elmer FT
1600 instrument. Mass spectra were recorded with a Nermag R10–
10H mass spectrometer [chemical ionization (CI), NH3 or CH4].
Elemental analyses were performed at the analytical laboratory of
the Laboratoire de Chimie de Coordination, Toulouse, France.
Scheme 5.
Single crystals of [Ar2Ge(F)O–] (Li+12-crown-4) (9) were
obtained but not of sufficient quality for satisfactory X-ray
analysis. However, this analysis should indicate a lengthen-
ing of the Ge–F bond and a marked shortening of the Ge–
O bond.
{2,6-[CH2N(iPr)2]2C6H3}2Ge(OMe)2 (1): Two equivalents of the
lithio compound ArLi (4.70 mmol) in thf (15 mL) were added
dropwise to a solution of Ge(OMe)4 (0.46 g, 2.35 mmol) in thf
(15mL) at ca. –78 °C. The orange solution was stirred for 1 h to
room temperature. After filtration through Celite, the mixture was
concentrated under reduced pressure and crystallized in pentane
(30 mL) at –20 °C to give 2 (1.21 g, 70% yield) as colourless crys-
tals. M.p. 144–146 °C. 1H NMR: δ = 1.02 [d, 3JHH = 6.7 Hz, 48 H,
Spectroscopic analyses of 3 and 9 give also very interest-
ing information about their structures. The 19F NMR spec-
tra of compounds 2 and 4 present sharp singlet peaks at
–138.03 and –139.20 ppm, respectively, which are usual sig-
nals for these kinds of compounds. For 3, the signal be-
comes broad, which could be related to a lengthening of
the Ge–F bond, concurrent to the stronger effect of the
oxygen atom, which is closer to the germanium, giving
more electronic charge to the fluorine atom. Thus, when the
3
CH3(iPr)], 3.03 [sept, JHH = 6.7 Hz, 8 H, CH(iPr)], 3.69 [s, 6 H,
3
(OMe)], 4.09 (s, 8 H, CH2N), 7.44 (t, JHH = 7.6 Hz, 2 H, 4-aryl
chelating agent (12-crown-4) is added, the signal becomes H), 8.04 (d, JHH = 7.6 Hz, 4 H, 3,5-aryl H) ppm. 13C NMR: δ =
3
21.08 [CH3(iPr)], 49.41 [CH(iPr)], 49.72 (CH2N), 51.92 (OMe),
126.14 (3,5-aryl C), 130.60 (4-aryl C), 132.68 (1-aryl C), 146.56
(2,6-aryl C) ppm. MS (CI, NH3): m/z (%) = 743 (100) [M + H]+,
711 (6) [M + H – MeOH]+. C42H76N4O2Ge (742.52): calcd. C
68.01, H 10.33, N 7.56; found C 68.24, H 10.54, N 7.50.
again broader such that it cannot be detected even by using
various temperature and solvent conditions for NMR spec-
troscopic analyses. This phenomenon has already been de-
scribed for the naked fluorine ion.[28] This suggests also that
in solution the fluorine is quite far from the germanium
and that compound 9 can be seen as a germanone–lithium
fluoride complex (Scheme 5). The germanone is thus ther-
modynamically stabilized by LiF complexation.
Compound 9 is very sensitive to oxygen and moisture, as
predicted for such an unusual compound. H2O and MeOH
reactions lead almost quantitatively to the corresponding
gem-germanediol 6 and germanol 8, respectively.
{2,6-[CH2N(iPr)2]2C6H3}2Ge(F)OH (2): A solution of 1 (0.66 g,
0.89 mmol), H2O (20µL, 1.1 mmol) and AgF (0.16 g,1.26 mmol) in
toluene (10 mL) were heated in a sealed tube at 110 °C for 6 h. The
solvent was removed in vacuo and pentane (30 mL) was added to
the residue. Insoluble silver salts were eliminated by filtration. After
removal of the solvent, white crystals (0.50 g, 78% yield) were ob-
1
3
tained. M.p. 139–141 °C. H NMR: δ = 0.94 [d, JHH = 6.7 Hz, 24
3
H, CH3(iPr)], 0.97 [d, JHH = 6.7 Hz, 24 H, CH3(iPr)], 2.99 [sept,
3JHH = 6.7 Hz, 8 H, CH(iPr)], 4.08, 4.15 (AB system, JHH
=
2
3
16.5 Hz, 8 H, CH2N), 7.35 (t, JHH = 7.6 Hz, 2 H, 4-aryl H), 7.80
(d, JHH = 7.6 Hz, 4 H, 3,5-aryl H), 9.72 (s, 1 H, OH) ppm. 13C
3
Conclusions
4
NMR: δ = 21.17 [CH3(iPr)], 48.40 [CH(iPr)], 50.94 (d, JCF
=
2
2.6 Hz, CH2N), 128.34 (3,5-aryl C), 135.96 (d, JCF = 14.7 Hz 1-
A dehydrofluorination reaction of fluorohydroxyger-
manes may appear as a novel and convenient route to ger-
manones. The lithio germanolate Ar2Ge(F)OLi (3) can be
presented as a synthetic equivalent of the corresponding
germanone complexed with lithium fluoride. Miscellaneous
aryl C), 147.42 (2,6-aryl C) ppm. 19F NMR: δ = –138.03 ppm. MS
(CI, NH3): m/z = 717 [M + H]+. IR [CHCl3, 85ϫ10–3 ]: ν = 3638
˜
(OH) cm–1. C40H71N4FOGe (716.48): calcd. C 67.13, H 10.00, N
7.83; found C 67.28, H 10.15, N 7.71.
trapping reaction with H2O, tBuLi and methanol revealed {2,6-[CH2N(iPr)2]2C6H3}2GeFOLi (3): A solution of tBuLi (1.7 
in pentane, 51 µL, 0.08 mmol) was added to a solution of 2 (59 mg,
germanone reactivity. This complexation with lithium fluo-
ride can be seen as a thermodynamic stabilization of the
germanone. The polar character of the germanium–oxygen
bond is enhanced by the electronic effect of the fluorine,
which increases the electrophilicity of the germanium and
assists nucleophilic additions. Introduction of suitable li-
gands for the lithiogermanolate in addition to the use of a
chelating agent such as 12-crown-4 to remove the lithium
appeared to be a promising way to isolate a monomeric
germanium–oxygen double-bond compound.
3
0.08 mmol) in C6D6 (0.7 mL). 1H NMR: δ = 0.87 [d, JHH
=
3
6.4 Hz, 24 H, CH3(iPr)], 0.89 [d, JHH = 6.4 Hz, 24 H, CH3(iPr)],
3.05 [br., 8 H, CH(iPr)], 4.05, 4.21 (br. AB system, 2JHH = 15.0 Hz,
3
3
8 H, CH2N), 7.35 (t, JHH = 7.5 Hz, 2 H, 4-aryl H), 7.85 (d, JHH
= 7.5 Hz, 4 H, 3,5-aryl H) ppm. 13C NMR: δ = 20.49 [CH3(iPr)],
20.75 [CH3(iPr)], 47.44 [CH(iPr)], 48.07 [CH(iPr)], 49.90 (br.,
2
CH2N), 125.38 (3,5-aryl C), 128.61 (4-aryl C), 139.21 (d, JCF
=
15.1 Hz, 1-aryl C), 147.64 (2,6-aryl C) ppm. 19F NMR: δ =
–129.37 ppm. Compound 3 was not isolated and only characterized
in solution.
Eur. J. Inorg. Chem. 2008, 4242–4247
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E. Bonnefille, S. Mazières, C. Bibal, N. Saffon, H. Gornitzka, C. Couret
FULL PAPER
{2,6-[CH2N(iPr)2]2C6H3}2Ge(F)OSiMe3 (4):
A
solution of
2
was heated at reflux for 3 h. After removal of the solvent under
vacuum, the residue was solubilized in pentane (10 mL) and crys-
tallized at –20 °C. Then, white crystals (0.20 g, 30% yield) were
obtained. M.p. 167 °C (dec.). 1H NMR: δ = 0.97 [d, 3JHH = 6.7 Hz,
(0.10 g, 0.14 mmol) in diethyl ether (10 mL) was treated at 0 °C
with a solution of tBuli (1.7  in pentane, 0.15 mmol, 0.09 mL).
The orange reaction mixture was stirred for 30 min; then Me3SiCl
(0.14 mmol in 5 mL of diethyl ether, 0.016 g) was added, and the
solution was warmed to room temperature. After addition of pen-
tane (40 mL), the solution was filtered through Celite. Evaporation
3
48 H, CH3(iPr)], 3.06 [sept, JHH = 6.7 Hz 8 H, CH(iPr)], 4.12 (s,
3
3
8 H, CH2N), 7.28 (t, JHH = 7.6 Hz, 2 H, 4-aryl H), 7.62 (d, JHH
= 7.6 Hz, 4 H, 3,5-aryl H), 7.87 (s, 2 H, OH) ppm. 13C NMR: δ =
20.78 [CH3(iPr)], 48.21 [CH(iPr)], 51.50 (CH2N), 129.35 (3,5-aryl
of the volatiles under reduced pressure led to a waxy material
1
(0.082 g, 60% yield). H NMR: δ = 0.31 (s, 9 H, SiMe3), 0.97 [d, C), 129.55 (4-aryl C), 140.21 (1-aryl-C), 146.29 (2,6-aryl C) ppm.
3
3JHH = 6.4 Hz, 24 H, CH3(iPr)], 1.0 [d, JHH = 6.4 Hz, 24 H,
MS (CI, NH3): m/z = 715 [M + H]+. IR (CHCl3, 112ϫ10–3 ): ν
˜
CH3(iPr)], 3.01 [sept, 3JHH = 6.4 Hz, 8 H, CH(iPr)], 4.09, 4.15 (AB = 3640 (OH) cm–1. C40H72N4O2Ge (714.49): calcd. C 67.32, H
2
3
system, JHH = 16.2 Hz, 8 H, CH2N), 7.43 (t, JHH = 7.6 Hz, 2 H,
4-aryl H), 8.06 (d, 3JHH = 7.6 Hz, 4 H, 3,5-aryl H) ppm. 13C NMR:
δ = 20.97 [CH3(iPr)], 48.53 [CH(iPr)], 49.70 (CH2N), 126.65 (3,5-
10.17, N 7.85; found C 67.43, H 10.29, N 7.73.
{2,6-[CH2N(iPr)2]2C6H3}2Ge(tBu)OH (7): A solution of tBuLi
(1.7  in pentane, 0.15 mL, 0.26 mmol) was added dropwise to a
solution of 2 (0.096 g, 0.13 mmol) in diethyl ether (10 mL). After
stirring for 30 min, the solution was quenched with water. The sol-
vent was evaporated under reduced pressure, and pentane (40 mL)
was added. After filtration of the salts, the solvent was then re-
2
aryl C), 131.06 (4-aryl C), 133.85 (d, JCF = 13.4 Hz, 1-aryl C),
148.37 (2,6-aryl C) ppm. 19F NMR: δ = –139.20 ppm. MS (CI,
NH3): m/z (%) = 787 (100) [M + NH4 – F]+, 717 (30) [M + NH4 –
OSiMe3]+.
moved under reduced pressure, and the residue (59 mg, 60% yield)
{2,6-[CH2N(iPr)2]2C6H3}2Ge(OH)2 (6)
3
was obtained as a waxy material. 1H NMR: δ = 1.0 [d, JHH
=
=
Method A: A solution of tBuLi (1.7  in pentane, 0.2 mL,
0.35 mmol) was added dropwise at 0 °C to a solution of 2 (0.252 g,
0.35 mmol) in diethyl ether. After warming the solution to room
temperature, H2O (8 µL, 0.44 mmol) was added, and the solution
was stirred for 30 min. The solvent was removed in vacuo, pentane
was added and 6 was isolated after filtration as a white powder
(0.23 g, 91% yield).
3
6.4 Hz, 48 H, CH3(iPr)], 1.55 (s, 9 H, tBu), 3.01 [sept, JHH
2
6.4 Hz, 8 H, CH(iPr)], 3.79, 4.04 (AB system, JHH = 15.0 Hz, 8
3
3
H, CH2N), 7.43 (t, JHH = 7.6 Hz, 2 H, 4-aryl H), 8.11 (d, JHH
=
7.6 Hz, 4 H, 3,5-aryl H), 8.17 (s, 1 H, OH) ppm. 13C NMR: δ =
21.43 [CH3(iPr)], 21.62 [CH3(iPr)], 24.44 [C(tBu)], 28.97
[CH3(tBu)], 48.14 [CH(iPr)], 50.96 (CH2N), 126.67 (3,5-aryl C),
129.40 (4-aryl C), 139.57 (1-aryl C), 147.94 (2,6-aryl C) ppm. MS
(CI, CH4): m/z (%) = 755 (100) [M + H]+, 737 (42) [M + H –
Method B: A solution of 1 (0.34 g, 0.46 mmol) and Bu4NF (1  in
thf containing ca. 5% water, 0.6 mL, 0.6 mmol) in toluene (10 mL)
H2O]+. IR (CHCl3, 156ϫ10–3 ): ν = 3644 (OH) cm–1.
˜
Table 2. Summary of crystallographic data for 1, 2 and 6.
1
2
6
Empirical formula
Fw
Crystal colour, form
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C47H88GeN4O2
813.80
block, colourless
monoclinic
C2/c
22.1986(8)
16.4261(6)
13.6740(5)
90
92.4860(10)
90
4981.3(3)
4
1.085
0.652
1784
C40H71FGeN4O
715.6
C40H72GeN4O2
713.61
block, colourless
orthorhombic
P21212
13.0868(8)
14.4285(9)
11.0654(7)
90
90
90
2089.4(2)
2
1.134
block, colourless
triclinic
¯
P1
12.1473(7)
13.0526(7)
13.0930(7)
94.4580(10)
90.9340(10)
97.7170(10)
2050.2(2)
2
γ [°]
V [Å3]
Z
Density [gcm–3]
Abs. µ [mm–1]
F(000)
1.159
0.785
776
0.768
776
Crystal size [mm]
Temperature [°C]
Scan mode
Detector
0.3ϫ0.4ϫ0,4
–100
ω and φ
Bruker-CCD
26.370
0.4ϫ0.6ϫ0,8
–100
ω and φ
Bruker-CCD
26.398
0.2ϫ0.3ϫ0,8
–80
ω and φ
Bruker-CCD
26.367
θ max [°]
No. observed reflections
No. unique reflections
Rmerge
14545
5088
0.0249
322
12022
8290
0.0173
441
12350
4270
0.0247
222
No. parameters
S[b]
1.067
1.013
1.041
R indices [I Ͼ 2s(I)][a]
wR2 = 0.0851
R1 = 0.0333
wR2 = 0.0894
R1 = 0.0407
0.498, –0.262
wR2 = 0.0754
R1 = 0.0313
wR2 = 0.0801
R1 = 0.0403
0.585, –0.380
wR2 = 0.0691
R1 = 0.0274
wR2 = 0.0717
R1 = 0.0321
0.381, –0.159
R indices (all data)[a]
Max.diff peak, hole [eÅ–3]
[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|, wR2 = {Σ [w(Fo – Fc ) ]/Σ [w(Fo2)2]}1/2 (sometimes denoted as Rw2). [b] GooF = S = {Σ [w(Fo – Fc ) ]/(n –
2
2 2
2
2 2
p)}1/2, where n is the number of reflections, and p is the total number of refined parameters.
4246
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 4242–4247

A Synthetic Equivalent of a Germanone Derivative
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{2,6-[CH2N(iPr)2]2C6H3}2Ge(OMe)OH (8): A solution of tBuLi
(1.7  in pentane, 0.14 mL, 0.24 mmol) was added to a solution of
2 (0.162 g, 0.23 mmol) in diethyl ether (2 mL). After 30 min, meth-
anol was added (0.16 mL, 0.23 mmol, 1 equiv). After 30 min stir-
ring, the solvent was then removed under reduced pressure and
pentane was added. After filtration of the salts, the solvent was
removed under reduced pressure, and the residue (134 mg, 80%
yield) was obtained as a waxy material. 1H NMR: δ = 0.97 [d, 3JHH
= 6.0 Hz, 48 H, CH3(iPr)], 3.01 [sept, 3JHH = 6.0 Hz, 8 H, CH(iPr)],
[9] K. Kishikawa, N. Tokitoh, R. Okazaki, Chem. Lett. 1996, 695–
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2
3.74 (s, 3 H, OMe), 4.03, 4.15 (AB system, JHH = 15.0 Hz, 8 H,
3
CH2N), 7.35 (t, JHH = 7.6 Hz, 2 H, 4-aryl-H), 7.71 (s, 1 H, OH),
7.83 (d, 3JHH = 7.6 Hz, 4 H, 3,5-aryl-H) ppm. 13C NMR: δ = 20.44
[CH3(iPr)], 47.70 (OMe), 47.96 [CH(iPr)], 50.30 (CH2N), 127.54
(3,5-aryl-C), 129.68 (4-aryl-C), 136.38 (1-aryl-C), 147.40 (2,6-aryl-
C) ppm. MS (CI, NH3): m/z (%) = 729 (20) [M + H]+.
[12] H. Lavayssière, J. Barrau, G. Dousse, J. Satgé, M. Bouchaut,
J. Organomet. Chem. 1978, 154, C9–C12.
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{2,6-[CH2N(iPr)2]2C6H3}2GeFOLi·12-crown-4 (9): 1,4,7,10-Tetra-
oxacyclododecane (12-crown-4; 17 µL, 0.10 mmol) was added to a
solution of 3 (0.09 mmol) in C6D6 (0.7 mL). Crystals (64 mg, 79%
yield) were isolated after 2 h from C6D6. M.p. 43 °C (dec.). 1H
5105–5109.
[14]
[15]
[16]
[17]
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3
3
NMR: δ = 1.03 [d, JHH = 6.4 Hz, 24 H, CH3(iPr)], 1.12 [d, JHH
= 6.4 Hz, 12 H, CH3(iPr)], 1.13 [d, 3JHH = 6.0 Hz, 12 H, CH3(iPr)],
3.32 (s, 16 H, CH2, 12-crown-4), 3.17 [sept, JHH = 6.0 Hz, 8 H,
3
CH(iPr)], 4.19, 4.61 (AB system, 2JHH = 15.0 Hz, 8 H, CH2N), 7.48
(t, 3JHH = 7.5 Hz, 2 H, 4-aryl H), 8.10 (d, 3JHH = 7.5 Hz, 4 H, 3,5-
aryl H) ppm. 13C NMR: δ = 20.94 [CH3(iPr)], 20.83 [CH3(iPr)],
48.48 [CH(iPr)], 49.49 (CH2N), 71.13 (CH2, 12-crown-4), 125.47
(3,5-aryl C), 128.13 (4-aryl C), 141.66 (1-aryl C), 148.44 (2,6-aryl
C) ppm. C48H86N4FO5GeLi (898.60): calcd. C 64.21, H 9.66, N
6.24; found C 65.03, H 9.85, N 6.67.
W. C. Hamilton, J. A. Ibers, Hydrogen Bonding in Solids: Meth-
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1.839 Å); c) P. D. Prince, G. S. McGrady, J. W. Steed, New J.
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All data for all structures represented in this paper were collected
at low temperature by using an oil-coated shock-cooled crystal with
a Bruker-AXS CCD diffractometer with Mo-Kα radiation (λ =
0.71073 Å). The structures were solved by direct methods[30a] and
all non-hydrogen atoms were refined anisotropically by using the
least-squared method on F2.[30b] A summary of crystallographic
data for 1, 2 and 6 is gathered in Table 2.
[20]
[21]
[22]
[23]
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CCDC-682034 (for 1), -682035 (for 2), -682036 (for 6), -692989
(for 9) contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
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Received: May 19, 2008
Published Online: August 19, 2008
Eur. J. Inorg. Chem. 2008, 4242–4247
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4247