New linked di-germanocenes and di-stannocenes

Article abstract of DOI:10.1016/S0022-328X(02)01221-4

New bridged di-germanocenes and di-stannocenes 2 have been synthesized from a reaction between (pentamethylcyclopentadienyl)metal chloride and the dilithium salts of the corresponding linked cyclopentadienyl ligands (spacer: phenylene, biphenylene, thiophene) in good yields. These di-metallocenes react easily with catechol giving preferentially the substitution reaction. With iodine or with metal 14 dichloride (M = Ge, Sn), the oxidative products are unstable and rapidly loose the linked cyclopentadienyl ligand. Starting from SnCl₂, the ionic half-sandwich compound [Cp*Ge][SnCl₃] 8, so obtained, was characterized by X-ray diffraction analysis which reveals a polymeric form in the solid state. The reaction of the di-germanocenes with o-quinone leads to the expected cycloadducts, stable in the case of permethylated compounds. An unusual single electron transfer reaction takes place with [Cp₂Fe][BF₄] and the transient cation radical rapidly gives [Cp*Ge][BF₄]. Mass spectra measurements and electrochemistry study confirm the weak stability of this cationic species.

Full text of DOI:10.1016/S0022-328X(02)01221-4

Journal of Organometallic Chemistry 651 (2002) 44–51
www.elsevier.com/locate/jorganchem
New linked di-germanocenes and di-stannocenes
J. Rouzaud a, M. Joudat a, A. Castel a, F. Delpech a, P. Rivie`re a,*, H. Gornitzka a,
J.M. Manriquez b, I. Chavez b
a Laboratoire d’He´te´rochimie Fondamentale et Applique´e, UMR No 5069, Uni6ersite´ Paul Sabatier, 118 Route de Narbonne,
31062 Toulouse Ce´dex 4, France
b Departamento Quimica Organica, Pontificia Uni6ersidad Catolica de Chile, Facultad de Quimica, Casilia 306, Correo 22, Santiago, Chile
Received 17 December 2001; accepted 29 January 2002
Abstract
New bridged di-germanocenes and di-stannocenes 2 have been synthesized from a reaction between (pentamethylcyclopentadi-
enyl)metal chloride and the dilithium salts of the corresponding linked cyclopentadienyl ligands (spacer: phenylene, biphenylene,
thiophene) in good yields. These di-metallocenes react easily with catechol giving preferentially the substitution reaction. With
iodine or with metal 14 dichloride (M=Ge, Sn), the oxidative products are unstable and rapidly loose the linked cyclopentadienyl
ligand. Starting from SnCl2, the ionic half-sandwich compound [Cp*Ge][SnCl3] 8, so obtained, was characterized by X-ray
diffraction analysis which reveals a polymeric form in the solid state. The reaction of the di-germanocenes with o-quinone leads
to the expected cycloadducts, stable in the case of permethylated compounds. An unusual single electron transfer reaction takes
place with [Cp2Fe][BF4] and the transient cation radical rapidly gives [Cp*Ge][BF4]. Mass spectra measurements and electrochem-
istry study confirm the weak stability of this cationic species. © 2002 Published by Elsevier Science B.V.
Keywords: Germanocene; Stannocene; Germanate; Cycloaddition; SET reaction
1. Introduction
as spacer with moderate yield using a slightly modified
[6] method described by Manriquez [5] (Scheme 1). The
procedure consists of two successive additions of
methyl-substituted cyclopent-2-en-1-one to the lithiated
spacers followed by a deshydratation reaction with
p-toluenesulfonic acid. When the reaction was per-
formed with 2,5-dilithiothiophene [7], the one-step addi-
tion of two equivalents of the conjugated ketone
slightly decreases the percentage of product and the
usual method of two steps was preferentially used.
Since the discovery of ferrocene in 1951 and the
description of a new type of bonding in this complex
[1], the metallocene chemistry has been widely devel-
oped. Some years after, the first Group 14 sandwich
compound [Cp2Pb] [2] was synthesized forming the
starting point of a large study upon Group 14 metal-
locenes [3]. In contrast, bridged di-germanocenes are
still unknown. Recently, we described the preparation
of the first p-phenylene and p-biphenylene bridged di-
germanocenes [4]. We report herein the syntheses of
new linked di-germanocenes and di-stannocenes with
various bridging groups (thienyl, phenyl…) and some
aspects of their reactivity.
2. Results and discussion
The syntheses of 1a–c were previously reported [5].
We prepare two new products 1d,e with a thienyl group
* Corresponding author. Tel.: +33-561-55-8348; fax: +33-561-55-
8204.
Scheme 1.
0022-328X/02/$ - see front matter © 2002 Published by Elsevier Science B.V.
PII: S0022-328X(02)01221-4

J. Rouzaud et al. / Journal of Organometallic Chemistry 651 (2002) 44–51
45
ring centers but are slightly displaced. Moreover, the
GeꢀC centroid distances are different according to the
cyclopentadienyl planes indicating a higher interaction
between the germanium atom and the C5Me5 ring. This
The reaction of stoichiometric amounts of the
dilithium salts of 1 [5] with [Cp*GeCl] [8] or [Cp*SnCl]
[9] at low temperature in THF as solvent affords the
corresponding di-germanocenes and di-stannocenes 2
(1).
(1)
is in agreement with the easy cleavage of the
metalꢀbridging ligand bond in the cationic form of
these di-germanocenes during mass measurements.
Cyclic voltammetry (in CH2Cl2 with Bu4NBF4 as
supporting electrolyte) of 2c reveals one irreversible
oxidation peak at +0.4 V (vs. SCE) similar to those
obtained for decamethyl Group 14 metallocenes (Si,
Ge, Sn) with the same experimental conditions [11]. As
previously observed in mass spectrometry, the radical
cation of 2c is unstable and probably looses the diradi-
cal of the bridging ligand with formation of
[(C5Me5)Ge]+. Further irreversible oxidation peaks are
present in the region 0.9–1.5 V corresponding to the
area of the oxidation peaks of the starting product 1c
(1.1, 1.3 and 1.6 V) but the evolution of the fragments
of the 2c cation is uncertain and unambiguous attribu-
tions cannot be made for these secondary oxidation
peaks.
These di-germanocenes and di-stannocenes, as most
of the known Group 14 metallocenes, can act as diva-
lent species leading to oxidative-addition reactions with
halogen or o-quinone. Due to the weakness of the
germaniumꢀ(cyclopentadienyl) p-bond, they can also
undergo bond cleavage with electrophiles.
Differences in the reactivity of di-germanocenes and
di-stannocenes appear from the reaction with two
equivalents (one equivalent per metal atom) of 3,5-di-
tert-butylcatechol. Within the tin series, a substitution
process [12] takes place leading to the cyclic divalent
species 3 (2) which was prepared separately by the
dehydrochlorination reaction of catechol with tin
dichloride in presence of triethylamine.
These compounds are isolated as pale yellow or red
powders in good yields (60–95%). They are very air-
sensitive and must be stored at low temperature. In
solution, a redistribution reaction takes place with for-
mation of the symmetrical species [Cp*2 M] (M=Ge,
Sn) [10]. In all cases, the permethylated compounds are
the most stable within the series. They were perfectly
characterized by physical and chemical measurements.
1
The H-NMR spectra show equivalent methyl groups
for the C5Me5 ligands in accord with rapidly rotating
pentamethylcyclopentadienyl rings [3b,11]. For the
same reason, two signals corresponding to the non-
equivalent pairs of methyl groups of the C5Me4 ligands
are observed. In the 13C-NMR spectra, chemical shifts
of the ring carbon atoms of the cyclopentadienyl
groups are near to those of the spacers (phenyl, thienyl)
but they were unambiguously assigned by HMBC (1H/
13C–3J) and HSQC (1H/13C–1J) experiments. This 13C-
NMR study confirms the equivalence of the methyl
groups and ring carbon atoms. 119Sn-NMR data for
di-stannocenes reveal high-field chemical shifts (2f, −
2110 ppm; 2g, −2128 ppm; 2h, −2129 ppm) which
correspond to the observed shift for decamethylstan-
nocene [3a] indicating a probable p-linked structure for
these compounds. The EI and CI (CH4) mass spectra
show the only presence of the cations [(C5Me5)M]+
(M=Ge, m/z: 209; M=Sn, m/z: 255) besides the
ligand 1. This behavior seems characteristic of the
metallocene series (M=Si, Ge) where the molecular
peak was never observed [3b].
The solid state structure of 2a has been investigated
by X-ray crystallography [4]. The most important infor-
mation, which have been revealed are the following
ones. First, the two Cp*Ge moieties coordinate to the
opposite faces of the bridging spacer. Then, the germa-
nium atoms do not reside over the cyclopentadienyl
(2)

46
J. Rouzaud et al. / Journal of Organometallic Chemistry 651 (2002) 44–51
The di-germanocenes give both the cyclic germylene
Such ionic half sandwich compounds [(C5Me5)Ge][X]
4 [13] and the spiro-compound 5 (3) [13] in various
(X=GeCl3, AlCl4, C5(CO2Me)5, BF4) [3a,14–16]] have
amounts (Section 3).
(3)
The formation of this by-product 5 can be explained
by a similar process of oxidative addition and subse-
quent H2-elimination (4) as previously described with
silicocene and leading in this case to the di(pen-
tamethylcyclopentadienyl)siladioxolane [3c,12].
been previously described but only one of them have
been structurally characterized to our knowledge. With
trichloride metal 14 as counter ion, only the structure
of the complex [(Me4C5H)Me2Si(Me4C5)Ge][Cl3Ge] in
(4)
Interestingly, the expected germadioxolane 9a has
not been observed. This is presumably due to the
weakness of the germaniumꢀbridging ligand p-bond,
revealed by the X-ray and electrochemical analyses.
The high reactivity of this bond with protic compounds
results in the exclusive formation of 4 and 5, the
bridging-ligand acting as the leaving group in the first
step.
which the central germanium is h5-bonded to one of the
cyclopentadienyl ring and furthermore weakly h2-
bonded to one of the double bonds of the second
cyclopentadienyl ligand has been reported [17]. The
crystal structure of compound 8 (Fig. 1 and Table 1)
In the case of I2, the products expected from the
oxidative addition of the divalent germanium centre
were not obtained. The formation of Cp*GeI3 [14] and
1, resulting from the cleavage of the linked cyclopenta-
1
dienyl ligand, was observed by H-NMR. Furthermore
with compound 2d, a side reaction between iodine and
the thienyl group takes place leading to the degradation
of the thiophene spacer.
With germanium or tin dichloride which can act as
Lewis acid, an electrophilic attack at the p-system of
the bridging cyclopentadienyl ligands [14] occurs with
formation of the ionic complexes 7 [14] and 8. The
recovery of a stoichiometric amount of [Cp*GeCl] by
treatment of the reaction mixture by hexane, confirms
the cleavage of the metalꢀligand bond in the first step
of the reaction. The transient chlorodigermanocenes, so
formed, seem too unstable to be isolated. The com-
plexes 7 and 8 were identified by comparison with a
sample prepared directly by reaction of [Cp*GeCl] with
the metal dichloride (5).
Fig. 1. Crystal structure of the complex 8.
Table 1
,
Selected bond lengths (A) and bond angles (°) for 8
Bond lengths
Sn(1)ꢀCl(1)
Sn(1)ꢀCl(2)
Sn(1)ꢀCl(3)
Ge(1)ꢀC(1)
Ge(1)ꢀC(2)
Ge(1)ꢀC(3)
2.511(8)
2.495(16)
2.478(7)
2.258(7)
2.279(6)
2.302(7)
Ge(1)ꢀC(4)
Ge(1)ꢀC(5)
C(1)ꢀC(2)
C(2)ꢀC(3)
C(3)ꢀC(4)
C(1)ꢀC(5)
2.308(6)
2.281(7)
1.449(6)
1.438(4)
1.450(10)
1.447(8)
Bond angles
Cl(2)ꢀSn(1)ꢀCl(1)
Cl(3)ꢀSn(1)ꢀCl(1)
Cl(3)ꢀSn(1)ꢀCl(2)
C(1)ꢀGe(1)ꢀC(2)
92.7(2)
C(1)ꢀGe(1)ꢀC(4)
C(3)ꢀC(2)ꢀC(1)
C(5)ꢀC(1)ꢀC(2)
61.25(9)
107.4(4)
108.5(4)
92.42(8)
94.10(18)
37.24(16)
(5)

J. Rouzaud et al. / Journal of Organometallic Chemistry 651 (2002) 44–51
47
shows the half-sandwich cation [(C5Me5)Ge]+ and the
trigonal pyramidal anion [Cl3Sn]−. The Cp* group is
pentahapto coordinated to the germanium atom as
Within the thiophene series, a mixture of the cycload-
duct 9e and the spiro-compound 5 was obtained. The
less hindered di-germanocene 2a gives only the forma-
tion of the spiro-compound 5 (7).
(7)
shown by the GeꢀC ring bond lengths which range
This probably results from a redistribution reaction
of the transient cycloadduct 9a as previously observed
in the case of the halogenated germylenes [13]. The
same redistribution reaction has been obtained starting
from [Cp*MCl] (M=Ge, Sn) confirming the weakness
of the metalꢀcyclopentadienyl bonds.
Recently, we have shown a single electron transfer
mechanism as the first step of the reaction between the
germylene and the quinone [18]. In order to test the
ability of the di-germanocene to undergo single electron
transfer, the reaction with a ferrocenium salt was per-
formed. Treatment of these di-metallocenes with
[Cp2Fe][BF4] in CH2Cl2 gave the reduced product
[Cp2Fe] and confirms their reducing character. Depend-
ing on the nature of the used metallocenes various
results were observed. The di-germanocenes 2a–c led to
the well known species [Cp*Ge][BF4] [14,16] (8)
whereas in the case of tin analogues, the insolubility of
the products prevented their identification.
,
from 2.258(7) to 2.308(6) A. Comparable values were
obtained from the complex [Cp*Ge][BF4] [16]. The Cp*
ring is planar and the methyl groups are bent out of the
ring plane away from the germanium atom. Two coun-
ter ions [Cl3Sn]− units are associated by two weak
,
SnꢀCl interactions (3.38 A). Such interactions have
been previously observed in [Cp*SnCl] which has two
,
weak SnꢀCl interactions (3.086(1) and 3.444(3) A) [9].
These dimeric structures are then linked through ger-
manium atoms (four weak interactions, Ge1ꢀCl1A:
,
,
,
3.31 A, Ge1ꢀCl2B: 3.34 A, Ge1ꢀCl3D: 3.37 A,
,
Ge1ꢀCl3A: 3.45 A) leading to a polymeric form as
shown in Fig. 2.
To verify the presence of bivalent metallic sites in
these complexes, we tried oxidative cycloaddition reac-
tion with 3,5-di-tert-butyl-ortho-quinone; quinones be-
ing excellent reagents in the characterization of such
divalent species [13,18]. The addition of stoichiometric
quantity of ortho-quinone to 2b,c at room temperature
gave the corresponding cycloadducts 9b,c, which were
isolated in good yields (6).
(8)
The transient radical ion is unstable, as previously
observed in mass spectrometry and electrochemistry
and it looses the diradical bridging ligand, giving 10
and, 1 by abstraction of hydrogen atoms from the
solvent.
(6)

48
J. Rouzaud et al. / Journal of Organometallic Chemistry 651 (2002) 44–51
filtered, washed with successively water and methanol
and dried under vacuum.
1d: (dark orange powder): 2.2 g, (32%). Melting point
1
(m.p): 150–153 °C. H-NMR (CDCl3) l 1.85 and 1.93
(sl, 12H, C5H3Me2), 3.23 (sl, 4H, CH2), 6.41 (s, 2H,
CH), 6.75 (s, 2H, C4H2S). 13C-NMR (CDCl3) l 12.58
and 13.44 (C5Me2H3); 46.02 (CH2); 131.07 (CH);
122.38 (CH) and 138.29 (Cquat.) (C4H2S); 134.77,
135.61, 136.99 (Cquat.) (C5Me2H3). MS/IE: m/z 268
([M]+, 100%), 253 ([M]+ꢀMe, 50%). Anal. Calc. for
C18H20S: C, 80.55; H, 7.51. Found: C, 79.67; H, 7.34%.
1e: The same procedure was used starting from 6.17
g (25.51 mmol) of 2,5-dibromothiophene, 28.06 mmol
of n-BuLi, 3.52 g (25.51 mmol) of 2,3,4,5-tetramethyl-
cyclopent-2-en-1-one) except that after p-toluene sul-
fonic acid treatment the mixture was washed twice with
water and dried on Na2SO4. After evaporation of the
solvent, the residue was washed with ethanol, dried
under vacuum and recrystallized in pentane giving 1e:
Fig. 2. Polymeric organization of 8 in the solid state.
3. Experimental
All the reactions were performed under a dry nitro-
gen atmosphere using standard Schlenk techniques and
dry solvents. NMR spectra were recorded on Brucker
AC 80 (80.13 MHz) and ARX 400 (400.13 MHz) (1H),
AC 200 (50.32 MHz) and ARX 400 (100.62 MHz)
(13C), ARX 400 (111.93 MHz) (119Sn). Mass spectra
were measured with a Hewlett–Packard HP 5989A in
the electron impact mode (70 eV) or a Rybermag
R10-10 spectrometer operating in the electron impact
mode or by chemical desorption (DCI, CH4). Electro-
chemical measurements were performed under argon
with a Electro-kemat potentiostate using a platinum
electrode (diameter 1 mm) and Bu4NBF4 as supporting
electrolyte. Potentials reported are versus Ag/AgCl/
KCl(sat). M.p. were measured on a Leitz microscope or
Electrothermal apparatus (capillary). Elemental analy-
sis were performed by the Centre de Microanalyse de
l’Ecole Nationale Supe´rieure de Chimie de Toulouse.
The compounds 1a–c [5], [Cp*GeCl] [8] and [Cp*SnCl]
[9] were prepared according to the literature proce-
dures.
1
(brown powder): 0.62 g (8%). m.p.: 131–135 °C. H-
NMR (CDCl3) l 1.16 (d, 3J=7.6 Hz, 6H, CHMe),
1.84, 1.91, 2.13 and 2.15 (s, 18H, C5Me3); 3.08 (q,
3J=7.6 Hz, 2H, CHMe); 6.81 (s, 2H, C4H2S). 13C-
NMR (CDCl3) l 11.25, 12.16, 13.42, 16.66 (C5Me4);
50.50 (CHMe); 123.74 (CH) and 141.02 (Cquat.)
(C4H2S); 135.33, 136.64, 137.14, 137.81 (Cquat.)
(C5Me4). MS/IE: m/z 324 ([M]+, 100%), 309 ([M]+
ꢀMe, 61%). Anal. Calc. for C22H28S: C, 81.42; H, 8.69.
Found: C, 80.81; H, 8.11%.
3.2. General procedure for the preparation of 2a–h
(1.9 mmol) of n-BuLi (1.6 M) in hexane were added
dropwise to a solution of (0.9 mmol) of 1 in 8 ml of
THF at −78 °C. The suspension was warmed to r.t.
and stirred over a period of 30 min. Then the mixture
was cooled to −78 °C and (1.8 mmol) of [Cp*MCl]
(M=Ge, Sn) in 5 ml of THF were slowly added. The
mixture was allowed to warm slowly to r.t. and stirred
for 2 h (for 2f–h, only 1 h). The solution was evapo-
rated in vacuo and the residue was extracted with 25 ml
of toluene and filtered. After removing the solvent in
vacuo, the residue was:
3.1. Preparation of 1d,e
To a solution of 2,5-dibromothiophene 6.17 g (25.51
mmol) in 50 ml of diethyl ether was added dropwise
35.23 mmol of n-BuLi in hexane (1.6 M). After the
solution was stirred for 20 min, the 3,4-dimethylcy-
clopent-2-en-1-one 3.37 g (30.61 mmol) was added. The
mixture was then refluxed for 1 h. After cooling at
room temperature (r.t.), 35.23 mmol of n-BuLi were
added. The white precipitate was stirred for 1 h, and
3.37 g (30.61 mmol) of the 3,4-dimethylcyclopent-2-en-
1-one was then added dropwise. The mixture was
stirred at r.t. for 30 min and then refluxed for 1 h. The
solution was quenched with aqueous (aq.) saturated
ammonium chloride, the layers were separated, and the
aq. phase extracted twice with diethyl ether. After
drying on Na2SO4, the solution was concentrated to 30
ml and 1.1 g of p-toluene sulfonic acid was added
under nitrogen. After 2 h of stirring, the precipitate was
– recrystallized from THF giving pale yellow crystals
for 2a.
– only dried for 2b–h. These compounds are unstable
in solution and cannot be recrystallized.
2a: Yield: 60%. m.p. (dec.): 215 °C. 1H-NMR
(CDCl3) l 1.75 (m, 8H, CH2CH2O); 1.80 (s, 30H,
C5Me5); 2.04 (s, 12H, C5H2Me2); 3.73 (m, 8H, CH2O);
6.06 (s, 4H, C5H2Me2); 7.28 (s, 4H, C6H4). 13C-NMR
(CDCl3) l 9.63, 12.42 (C5Me5 and C5H2Me2); 25.65,
68.01 (C4H8O); 106.48 (CH), 122.28, 124.41 (Cquat.)
(C5H2Me2); 118.92 (C5Me5); 124.91 (CH), 133.01
(Cquat.) (C6H4). MS/IE: m/z 209 ([(C5Me5)Ge]+,
100%); 262 ([1a]+, 64%). Anal. Calc. for C48H66Ge2O2:
C, 70.28; H, 8.11. Found: C, 69.49; H, 7.38%.

J. Rouzaud et al. / Journal of Organometallic Chemistry 651 (2002) 44–51
49
2b: Yield: 84%. m.p. (dec.): 235 °C. 1H-NMR
3.3. Reaction of 2f–h with 3,5-di-tert-butylcatechol
(CDCl3, 250 MHz) l 1.95 (s, 30H, C5Me5); 2.03 and
2.04 (s, 24H, C5Me4); 7.11 (s, 4H, C6H4). 13C-NMR
(CDCl3) l 9.95, 10.28, 11.01 (C5Me5 and C5Me4);
118.10, 118.44, 118.67, 127.08 (C5Me5 and C5Me4);
129.96 (CH); 133.80 (Cquat.) (C6H4). MS/IE: m/z 209
([(C5Me5)Ge]+, 100%); 318 ([1b]+, 4%).
A solution of 0.17 g (0.78 mmol) of 3,5-di-tert-butyl-
catechol in 4 ml of THF was added to a solution of
di-stannocenes 2f–h (0.39 mmol) in 8 ml of THF at r.t.
The mixture was stirred for 2 h. After evaporation of
the solvent, the residue was washed with Et2O (elimina-
tion of the ligands 1a–c), giving powders. The 1H-
NMR analyses of these residues show the formation of:
– 1a (10%), 3 (90%);
2c: Yield: 92%. m.p. (dec.): 300 °C. 1H-NMR
(CDCl3) l 1.95 (s, 30H, C5Me5); 2.03 and 2.04 (s, 24H,
3
C5Me4); 7.26 and 7.63 (syst. AB, JHH=8.4 Hz, 8H,
– 1b (8%), 3 (82%);
– 1c (17%), 3 (83%).
C6H4). 13C-NMR (CDCl3) l 9.95, 10.27, 10.92 (C5Me5
and C5Me4); 118.12, 118.58, 118.78, 126.91 (C5Me5 and
C5Me4); 126.15, 131.07 (CH), 135.80, 137.94 (Cquat.)
(C6H4). MS/IE: m/z 209 ([(C5Me5)Ge]+, 100%); 394
([1c]+, 24%).
3.4. Preparation of 3
To a solution of 3,5-di-tert-butylcatechol 0.35 g (1.58
mmol) and SnCl2 0.30 g (1.58 mmol) in 6 ml of toluene
was added dropwise Et3N 0.32 g (3.16 mmol) at r.t. The
mixture was stirred for 10 min then refluxed for 1 h.
After filtration (elimination of Et3N,HCl), the filtrate
was evaporated and the solid washed by pentane. After
drying under vacuo, a white powder of 3 was obtained:
2d: Yield: 49%. m.p. (dec.): 243 °C. 1H-NMR
(CDCl3) l 1.87 (s, 30H, C5Me5); 2.03 (s, 12H,
C5H2Me2); 5.94 (s, 4H, C5H2Me2); 6.67 (s, 2H, C4H2S).
13C-NMR (CDCl3)
l
9.65, 12.37 (C5Me5 and
C5H2Me2); 106.72, 106.95 (CH) (C5H2Me2); 117.22,
119.14, 123.82 (Cquat.) (C5Me5 and C5H2Me2); 120.36
(CH), 136.39 (Cquat) (C4H2S). MS/IE: m/z 209
([(C5Me5)Ge]+, 55%); 268 ([1d]+, 100%).
1
0.48 g (69%). m.p.: 194 °C (dec.). H-NMR (CDCl3/
DMSO d6) l 1.17, 1.34 (s, 18H, C(CH3)3); 1.19 (t,
3J=7.7 Hz, 9H, N(CH2CH3)); 2.96 (q, 3J=7.7 Hz, 6H,
N(CH2CH3)); 6.58, 6.75 (d, 4J=1.9 Hz, 2H, C6H2).
13C-NMR (CDCl3/DMSO d6) l 8.88 (N(CH2CH3));
29.79, 31.95 (C(CH3)); 34.07, 34.91 (C(CH3)); 46.04
(N(CH2CH3)); 111.32, 113.25 (CH), 135.83, 138.26,
148.43, 151.08 (C6H2). 119Sn-NMR (DMSO d6) l −63
ppm. MS/EI: m/z 340 ([M]+ꢀEt3N, 13%), 325 ([M]+
ꢀEt3NꢀCH3, 33%). Anal. Calc. for C14H20SnO2: C,
49.60; H, 5.95. Found: C, 48.96; H, 6.67%.
2e: Yield: 53%. m.p. (dec.): 290 °C. 1H-NMR
(CDCl3) l 1.97 (s, 30H, C5Me5), 2.05 and 2.12 (s, 24H,
C5Me4), 6.69 (s, 2H, C4H2S). 13C-NMR (CDCl3) l 9.86,
10.32, 11.15 (C5Me5 and C5Me4); 118.41, 118.82,
118.89, 119.03, (C5Me5 and C5Me4); 125.62 (CH),
136.72 (Cquat) (C4H2S).
2f: Yield: 92%. m.p. (dec.): 240 °C. 1H-NMR
(CDCl3) l 1.90 (s, 3J(Hꢀ117/119Sn)=3.2 Hz, 30H,
C5Me5); 2.10 (s, 12H, C5H2Me2); 6.16 (s, 4H,
C5H2Me2); 7.30 (s, 4H, C6H4). 13C-NMR (CDCl3) l
9.85, 12.51 (C5Me5 and C5H2Me2); 105.35 (CH)
(C5H2Me2); 117.67, 121.31, 123.50 (Cquat.) (C5Me5 and
C5H2Me2); 124.63 (CH), 132.93 (Cquat) (C6H4).
2g: Yield: 68%. m.p. (dec.): 188 °C. 1H-NMR
3.5. Reaction of 2a–c with 3,5-di-tert-butylcatechol
Using the same procedure described for 2f–h ex-
cepted the reaction time (20 h), 0.12 g (0.52 mmol) of
catechol and (0.26 mmol) of the di-germanocenes 2a–c
in 8 ml of THF give white solids after evaporation of
the solvents.
(CDCl3)
l
2.03 (s, 3J(Hꢀ117/119Sn)=3.6 Hz,
30H, C5Me5); 2.11 and 2.13 (s, 24H, C5Me4); 7.19 (s,
4H, C6H4). 13C-NMR (CDCl3) l 10.25, 10.55, 11.39
(C5Me5 and C5Me4); 117.02, 117.12, 117.54, 125.77
(C5Me5 and C5Me4); 130.06 (CH), 133.75 (Cquat)
(C6H4). MS/IE: m/z 255 ([(C5Me5)Sn]+, 14%); 318
([1b]+, 100%).
– from 2a: treatment of the residue by little THF
(elimination of 1a in the precipitate), decantation
1
and drying, the H-NMR analysis of the white pow-
der shows: 4 (64%), 5 (36%).
1
– from 2b: the H-NMR spectrum of the crude mix-
ture indicates the presence of 1b (27%), 4 (42%), 5
(31%).
2h: Yield: 58%. m.p. (dec.): 180 °C. 1H-NMR
(CDCl3) l 2.01 (s, 3J(Hꢀ117/119Sn)=3.6 Hz, 30H,
C5Me5); 2.12 and 2.13 (s, 24H, C5Me4); 7.29, 7.61 (syst.
– from 2c: after treatment of the residue by a mixture
THF–pentane (elimination of 1c in the precipitate),
3
AB, JHH=7.7 Hz, 8H, C6H4). 13C-NMR (CDCl3) l
1
decantation and drying, the H-NMR spectrum indi-
10.41, 10.51, 10.95 (C5Me5 and C5Me4); 117.08, 117.15,
117.62, (C5Me5 and C5Me4); 126.18, 131.02 (CH),
135.21, 137.81 (Cquat) (C6H4).
cates the formation of 4 (44%), 5 (56%).
3.6. Reaction of 2a with Cl2Ge.dioxane
The compounds 2b–h are not stable in solution and
decompose slowly at r.t. Thus, they did not give repro-
ducible analyses.
To a solution of 2a 0.26 g (0.38 mmol) in 4 ml of
CH2Cl2 was added a solution of 0.18 g (0.77 mmol) of

50
J. Rouzaud et al. / Journal of Organometallic Chemistry 651 (2002) 44–51
Cl2Ge·dioxane in 4 ml of CH2Cl2 at −78 °C. The
mixture was slowly warmed to r.t. and the solvent
evaporated. The 1H-NMR analysis of the crude mixture
shows the formation of [Cp*Ge][Cl3Ge] [14] and 1a.
The treatment by CH2Cl2 allowed the extraction of 41%
of this complex which was identified by 1H- and
3.9. Reaction of 2b,c with
3,5-di-tert-butyl-ortho-quinone
3,5-di-tert-Butyl-ortho-quinone (0.80 mmol) in 4 ml
of THF was added to a solution of (0.40 mmol) of the
di-germanocene 2b or 2c dissolved in 6 ml of THF at
r.t. The mixture was stirred for 2 h. The solvent was
evaporated in vacuo to give white powders identified,
respectively, as 9b and 9c.
1
13C-NMR spectroscopies: H-NMR (CDCl3) l 2.13 (s,
15H, C5Me5). 13C-NMR (CDCl3) 9.62 (C5Me5); 121.26
(C5Me5).
9b: Yield: 63% after recrystallization from hexane.
1
m.p.: 104–106 °C. H-NMR (CDCl3) l 1.30, 1.31 and
3.7. Reaction of 2a with SnCl2
1.46 (s, 36H, C(CH3)3); 1.68, 1.72, 1.81, 1.82, 1.86 (s,
54H, C5Me4 and C5Me5); 6.72 and 6.94 (d, JHH=2.2
4
A solution of SnCl2 0.13 g (0.70 mmol) in 4 ml of
THF was added to a solution of 2a 0.53 g (0.78 mmol)
in 12 ml of THF at −78 °C. The mixture was stirring
at −40 °C for 1 h. After concentration of the solvent
under vacuo, the treatment of the residue by 2×7 ml
of hexane gave in the filtrate 0.17 g (91%) of [Cp*GeCl]
Hz, 4H, C6H2); 7.20 (s, 4H, C6H4). 13C-NMR (CDCl3)
l 12.24, 12.42, 13.31, 13.50 (C5Me4 and C5Me5); 29.77,
31.93 (C(CH3)3); 34.57, 34.72, (C(CH3)3); 108.93,
113.22 (CH) (C6H2); 128.89 (CH) (C6H4); 133.79,
133.90 (C5Me4 and C5Me5); 141.09, 147.07, 151.39
(Cquat., C6H2 and C6H4). MS/DCI,NH4: m/z 1172
([M+, 11%), 1157 ([MꢀCH3], 2%). Anal. Calc. for
C72H98Ge2O4: C, 73.74; H, 8.42. Found: C, 73.19; H,
8.38%.
1
identified by H-NMR (l=2.01 ppm) and mass spec-
trometry ([M]+: 244). The precipitate was treated by 8
ml of THF. The filtrate was concentrated and analyzed
1
by H-NMR: [Cp*Ge][Cl3Sn] (39%), 1a (61%).
9c: Yield: 96%. m.p.: 130–133 °C. 1H-NMR (CDCl3)
l 1.31, 1.32 and 1.48 (s, 36H, C(CH3)3); 1.69, 1.73, 1.77,
3.8. Preparation of [Cp*Ge][Cl3Sn] (8)
1.81, 1.85 (s, 54H, C5Me4 and C5Me5); 6.72 and 6.93 (d,
4JHH=2.1 Hz, 4H, C6H2); 7.30, 7.61 (syst. AB, JHH
=
3
To a solution of [Cp*GeCl] 0.31 g ( 1.29 mmol) in 7
ml of THF was slowly added a solution of SnCl2 0.25
g (1.29 mmol) in 7 ml of THF at −78 °C. The mixture
was warmed to −40 °C and stirred for 1 h at this
temperature. The solvent was reduced to 6 ml. After
cooling to −30 °C, colorless crystals appeared and
were isolated after decantation and drying: 0.36 g
(65%). m.p.: 290 °C (dec.). 1H-NMR (CDCl3) l 2.14 (s,
15H, C5Me5). 13C-NMR (CDCl3) l 9.60 (C5Me5);
121.23 (C5Me5). 119Sn-NMR (THF–ext. ref. D2O) l
−199 ppm. MS/EI: m/z 209 ([(C5Me5)Ge]+, 49%).
Anal. Calc. for C10H15Cl3GeSn: C, 27.74; H, 3.49.
Found: C, 27.73; H, 3.52%.
8.0 Hz, 8H, C6H4). 13C-NMR (CDCl3) l 12.29, 12.52,
13.26, 13.42 (C5Me4 and C5Me5); 29.85, 32.01
(C(CH3)3); 34.61, 34.79 (C(CH3)3); 109.01, 113.32 (CH)
(C6H2); 126.33, 130.06 (CH) (C6H4); 133.87, 135.27,
138.51, 141.17, 141.33, 142.15, 147.12, 151.42 (Cquat.,
C6H2, C6H4, C5Me4 and C5Me5). MS/DCI,CH4: m/z
1249 ([M+H]+, 3%). Anal. Calc. for C78H102Ge2O4: C,
75.02; H, 8.23. Found: C, 74.44; H, 8.15%.
3.10. Reaction of 2e with 3,5-di-tert-butyl-ortho-quinone
Following the same procedure, a mixture of 1e
(27%), 9e (41%), and 5 (32%) (relative% calculated from
the NMR spectrum) was obtained. The compound 9e
could not be extracted in a pure form from this residue
whatever the techniques of separation (crystallization,
chromatotron…) may be used.
3.8.1. Crystal data for 8
C10H15Cl3GeSn, M=432.85, monoclinic, C2/c, a=
,
,
,
10.24(8) A, b=7.91(7) A, c=16.70(11) A, i=
3
−3
1
,
111.6(2)°, V=2979(23) A , Z=8, zc=1.930 Mg m
,
9e: H-NMR (CDCl3) l 1.32, 1.33 and 1.50, 1.52 (s,
,
F(000)=1664, u=0.71073 A, T=173(2) K, v(Mo–
Ka)=4.202 mm−1, crystal size 0.5×0.5×0.6 mm3,
1.81°5q532.30°, 17 895 reflections (4982 indepen-
dent, Rint=0.0326), Tmin=0.589313, Tmax 1.0, 141
36H, C(CH3)3). 1.61, 1.63, 1.65, 1.68, 1.86 (s, 54H,
4
C5Me4 and C5Me5), 6.73, 6.96 (d, JHH=2.1 Hz, 4H,
C6H2), 7.33 (s, 2H, C4H2S). MS/DCI,NH3: m/z 1196
([M+NH4]+, 12%), 1179 ([M+H]+, 3%).
parameters, R1 [I\2s(I)]=0.0265, wR2 [all data]=
−3
,
0.0710, largest electron density residue: 0.677 e A
.
3.11. Reaction of 2a with 3,5-di-tert-butyl-ortho-quinone
Data were collected at low temperature using oil-coated
shock-cooled crystals on a Bruker-AXS CCD 1000
diffractometer. Semi-empirical absorption corrections
were employed [19]. The structure was solved by direct
methods (SHELXS-97) [20] and refined using the least-
squares method on F2. [21] R1=ꢀꢁꢁFoꢁ−ꢁFcꢁꢁ/ꢀꢁFoꢁ and
The same procedure was followed, except 5 was
isolated from a mixture THF–pentane and identified
by H-NMR [13] (61% yield). H-NMR (CDCl3) l 1.24
and 1.36 (s, 36H, CH3), 1.75 (m, 8H, CH2, THF), 3.83
(m, 8H, OCH2, THF), 6.75 (d, J=2 Hz, 2H, C6H2),
6.98 (d, J=2 Hz, 2H, C6H2).
1
1
wR2=(ꢀw(F2o−Fc2)2/ꢀw(F2o)2)0.5
.

J. Rouzaud et al. / Journal of Organometallic Chemistry 651 (2002) 44–51
51
3.12. Reaction of 2a–c with [Cp2Fe][BF4]
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4. Supplementary material
Crystallography data have been deposited with the
Cambridge Crystallography Data Centre as supplemen-
tary publications CCDC no. 176098 for 8. Copies of the
data can be obtained free of charge on application to
The Director, CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (Fax: +44-1223-336033; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
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The authors thank the ECOS-CONYCIT program
(No. C98E02 and No. C01E06) and the Comite´ Mixte
Interuniversitaire Marocain for the ‘Action Inte´gre´e
Franco-Marocaine No. 216/SM/00’ for partial financial
support and D. de Montauzon for electrochemical
studies.