Synthesis of a tin-functionalized cyclopentadiene derivative

Article abstract of DOI:10.1016/j.jorganchem.2004.06.065

A 3-tert-butyl-1-(stannylpropyl)-functionalized cyclopentadienyl ligand precursor 6 is readily available in 64% overall yield from allylic alcohol 1 by a three-step reaction sequence including Pd-catalyzed hydrostannylation with Ph₃SnH. Treatment with FeCl₂ and ZrCl₄ · 2THF afforded corresponding ferrocene and zirconocene derivatives. Transmetallation of Sn-Ph with Li-Bu was observed under these reaction conditions by using BuLi as a base.

Full text of DOI:10.1016/j.jorganchem.2004.06.065

Journal of Organometallic Chemistry 689 (2004) 3550–3555
www.elsevier.com/locate/jorganchem
Synthesis of a tin-functionalized cyclopentadiene derivative
*
Jens Christoffers , Thomas Werner, Angelika Baro, Peter Fischer
Institut fu¨r Organische Chemie, Universita¨t Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany
Received 7 April 2004; accepted 25 June 2004
Available online 17 September 2004
Abstract
A 3-tert-butyl-1-(stannylpropyl)-functionalized cyclopentadienyl ligand precursor 6 is readily available in 64% overall yield from
allylic alcohol 1 by a three-step reaction sequence including Pd-catalyzed hydrostannylation with Ph3SnH. Treatment with FeCl2
and ZrCl4 Æ 2THF afforded corresponding ferrocene and zirconocene derivatives. Transmetallation of Sn–Ph with Li–Bu was
observed under these reaction conditions by using BuLi as a base.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Cyclopentadienyl ligand; Ferrocenes; Zirconocene; Pendant alkyl groups; Tin compounds; Hydrostannylation
1. Introduction
olefin polymerisation [7]. Furthermore, our concept fo-
cussed on the application of tin–alkyl moieties in the side
chain of cyclopentadienyl ligands, allowing subsequent
transmetallation reactions to form C,C-chelates [8] as
well as heteropolymetallic compounds.
In this note, we would like to report on a straight-
forward synthesis of a new alkyl- and tin–alkyl-
functionalized cyclopentadienyl derivative which does
further implicate the generation of a plane of chirality
when coordinating to a metal center. Our report in-
cludes the access to ferrocenes and a zirconocene bear-
ing this 1,3-disubstituted cyclopentadienyl ligand.
Cyclopentadienyl ligands are ubiquitous in organome-
tallic chemistry. In the recent years functionalized cyclo-
pentadienyl ligands with pendant donor atoms and metal
complexes derived thereof have been synthesized in order
to obtain chelate metal complexes [1–5] or to prepare
heterobi- or polymetallic compounds by intermolecular
coordination of the additional donor function [6]. Group
15 and group 16 elements are most common donor atoms
in this field: oxygen [2] and nitrogen [3] as r- and p-do-
nors, sulfur [4] and phosphorus [4b,5] as r-donors and
p-acceptors. We envisioned pendant alkyl groups as pure
r-donor functions in a coordinating cyclopentadienyl
side chain in order to form metal–carbon r-bonds with-
out additional lone pairs at the donor atom. In contrast
to the above mentioned donor atoms (N, O, P, S) alkyl
donors do not show Lewis basic character. Thus, they
are not capable of interacting with strong Lewis acids
such as boron or aluminium compounds, commonly em-
ployed to activate metal–chloro bonds in precatalysts for
2. Results and discussion
The synthetic route to target cyclopentadienyl ligand
precursor 6 is shown in Scheme 1. Allylic alcohol 1 was
considered as the building block for the C3-side chain.
First, the tin function was introduced into 1 by hydro-
stannylation with Ph3SnH. Following a literature pro-
cedure without any catalyst or radical promoter [9],
the yield of product 2 was less than 20%, whereas at-
tempts completely failed to react 1 in the presence of
AIBN as a radical initiator at a temperature of 50 ꢁC.
*
Corresponding author. Tel.: +49 711 685 4283; fax: +49 711 685
4269.
E-mail address: jchr@oc.uni-stuttgart.de (J. Christoffers).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.06.065

J. Christoffers et al. / Journal of Organometallic Chemistry 689 (2004) 3550–3555
3551
OH
the reaction mixture with FeCl2. Along the chromato-
graphic purification, a red zone was eluted whose
NMR spectra indicate a nonuniform species. Mass
spectrometric investigations of this material exhibit se-
ven signals at m/z = 1080, 1060, 1040, 1020, 1000, 980,
and 960, all showing the typical FeSn2 isotope pattern,
and thus, were interpreted as the M+ signals of seven
species of the general formula 8 shown in Scheme 2.
The m/z peaks at 1080 (M+) and 960 (M+) correspond
to the species with two triphenylstannyl moieties
(n,m = 0) and to the species with two tributylstannyl
groups (n,m = 3), respectively. Exchange of a phenyl
by a butyl residue results in a lowering of the molecular
mass by Dm/z = 20. From this result we therefore con-
cluded transmetallation of Sn–Ph with Li–Bu under
the reaction conditions used, giving a mixture of ferroce-
nes with the general formula 8. Interestingly, this trans-
metallation could be accomplished quantitatively by
treatment of 8 with an excess of BuLi at 0 ꢁC, finally
yielding the unique material 9. Derivative 9 gave both
sufficient mass spectrometric data [m/z = 960 (M+)]
and elemental analysis. The NMR spectra, however, re-
veal a doubled signal set obviously caused by the two
diastereomers (rac and meso) of this product.
1
Pd2(dba) 3 · CHCl 3 (5 mol%)
Ph3SnH, THF, 16 h, 23˚C
SnPh3
Ph3Sn
OH
OH
+
Me
2 (85%)
3 (5%)
TsCl, pyridine, 5 h, 23˚C
Ph3Sn
OTs
+
Ph3Sn
Cl
4 (81%)
5 (3%)
1) NaH (2 eq.), tBuCpH, THF, −78˚C
2) 12 h, 23˚C
tBu
tBu
+
Ph3Sn
tBu
6 (92%)
7 (12%)
Scheme 1.
Deprotonation of cyclopentadienyl derivative 6 with
PhLi at 0 ꢁC followed by reaction with FeCl2 resulted
in formation of ferrocene 10 bearing the two Ph3Sn sub-
stituents [m/z = 1080 (M+)]. Derivative 10 was obtained
as an analytically pure material in 47% yield. Again a
doubled signal set in the NMR spectra evidenced the
existence of two diastereomers (rac and meso).
Finally, we succeeded in preparing the zirconocene
dichloride 11 from derivative 6 by deprotonation with
PhLi at ꢀ78 ꢁC and subsequent treatment with
ZrCl4 Æ 2THF. Compound 11 was isolated as a colorless
oil, which shows the typical Cl2Sn2Zr isotope pattern in
the mass spectra and, not surprising, exists as an insep-
arable mixture of a rac- and a meso-diastereomer.
In conclusion, the tin-functionalized 1,3-disubstituted
cyclopentadienyl ligand precursor 6 is accessible in good
yields by a convenient synthesis starting from allylic
alcohol 1. Pd-catalyzed hydrostannylation introduced
the triphenylstannyl moiety. Compound 6 was success-
fully reacted with FeCl2 and ZrCl4 Æ 2THF to give two
ferrocene derivatives 9, 10 and one zirconocene 11,
respectively. A tin–lithium exchange with BuLi in the
coordination sphere of ferrocene 8 allow for transforma-
tion of Sn–Ph into Sn–Bu groups.
Therefore, we finally investigated three different Pd cat-
alysts for the formation of 2 [10]. Applying the Pearl-
man-catalyst [Pd(OH)2/C] and Pd(PPh3)4 alcohol 2
was obtained in 40% and 61% yield, respectively. The
system of Pd2(dba)3 Æ CHCl3 without any additional
ligating additives in THF as the solvent at ambient tem-
perature, however, turned out to be optimal. Apart from
major product 2 (85%), the regioisomeric hydrostanny-
lation product 3 was isolated in 5% yield after chroma-
tographic separation.
The primary alcohol function in 2 was activated as
p-toluenesulfonic ester by using standard conditions
[11] to give tosylate 4 in 81% yield and the chloro com-
pound 5 as a byproduct in 3% yield, which is presumably
formed from 4 and pyridinium chloride by Finkelstein
reaction and could be separated by column chromatogra-
phy. The synthesis was accomplished by conversion of
tosylate 4 with the sodium salt of tert-butylcyclopentad-
iene (tBuCpH) [12] affording the 1,3-disubstituted cyclo-
pentadienyl derivative 6 in high yields (92% reg. 4) when a
fourfold excess of tBuCpH was employed. In this case,
however, dimer 7 (12% reg. tBuCpH) was formed as a
byproduct by Diels–Alder reaction. The constitution
of the tricyclic hydrocarbon 7 was elucidated by H,H-
COSY, HMQC and HMBC NMR experiments. The
NMR spectra of target compound 6 exhibit a threefold
signal set which is caused by three C–C double bond
isomers.
3. Experimental
3.1. General
Conversion of ligand precursor 6 to give the corre-
sponding ferrocene derivative was realized by deproto-
nation with BuLi at 0 ꢁC and subsequent treatment of
The commercial chemicals n-BuLi (Merck), NaH
(Merck), iron(II) chloride (Aldrich), phenyllithium

3552
J. Christoffers et al. / Journal of Organometallic Chemistry 689 (2004) 3550–3555
tBu
tBu
3SnBunPh(3
SnBu3
SnBu3
−
n)
BuLi, THF
3 d
Fe
Fe
SnBumPh(3
−
m)
tBu
tBu
3
9
8 (n,m = 0−3)
1) BuLi (1.5 eq.), THF, 0˚C
2) FeCl 2, 2 h, 23˚C
tBu
tBu
1) PhLi (1.2 eq.), THF
15 min, 0˚C
SnPh3
SnPh3
tBu
3SnPh3
Fe
2
2) FeCl 2, 3 h, 23˚C
6
10 (47%)
tBu
tBu
1) PhLi (2 eq.), THF
15 min, −78˚C
SnPh3
SnPh3
Cl Zr Cl
2) ZrCl 4 · 2 THF, 16 h, 23˚C
11 (39%)
Scheme 2.
(Fluka), triphenyltin hydride (Arcos), tris(dibenzyliden-
acetone)dipalladium chloroform adduct [Pd2dba3 Æ
CHCl3] (Arcos), ZrCl4 Æ 2THF (Aldrich), and THF
[absolute (H2O 6 0.005%), Fluka] were used as pur-
chased without further purification. Ethyl acetate (EA)
and hexanes (PE, bp 30–75 ꢁC) were distilled prior to
use for chromatography.
3J(13C,117,119Sn) = 33.0 Hz, 1-CH2], 128.38 [s, d,
2J(13C,117,119Sn) = 47.8
Hz,
o-CH],
128.73
[s,
d, 4J(13C,117,119Sn) = 11.7 Hz, p-CH], 136.88 [s, d,
3J(13C,117,119Sn) = 35.3 Hz, m-CH], 138.87 [s, d, d,
1
1J(13C,117Sn) = 463.0 Hz, J(13C,119Sn) = 488.0 Hz, i-C]
~
ppm. IR (ATR): m ¼ 3331 ðmÞ, 3061 (m), 3039 (m),
2935 (m), 2862 (m), 1480 (s), 1427 (s), 1074 (m), 730
(s), 699 (s), 659 (m) cmꢀ1. MS (EI, 70 eV): m/z
(%) = 410 (1) [M+], 351 (100) [Ph3Sn+], 333 (54)
[M+ ꢀ Ph], 291 (8), 197 (32) [PhSn+]. HRMS Calcd.
333.0301 (for C15H17O120Sn). Found: 333.0300
(M+ ꢀ Ph). Anal. Calcd. for C21H22OSn (409.12): C
61.66, H 5.42. Found: C 61.65, H 5.48%. Byproduct 3:
IR: attenuated total reflection (ATR).
3.2. 3-(Triphenylstannyl)-1-propanol (2)
Under exclusion of moisture and air Ph3SnH (5.04 g,
14.4 mmol), THF (10 cm3) and at ꢀ78 ꢁC
Pd2(dba)3 Æ CHCl3 (160 mg, 0.155 mmol) were added
to 1 (1.67 g, 28.8 mmol), and the stirred reaction mixture
was allowed to warm up to room temperature (16 h).
After removal of all volatile materials, the residue was
chromatographed (SiO2, gradient PE/EA from 5:1 to
1:1, followed by EA). In a first fraction [Rf(PE/
EA = 5:1) = 0.27] byproduct 3 (298 mg, 0.728 mmol,
5%) was obtained as a colorless solid. In a second frac-
tion [Rf(PE/EA = 5:1) = 0.16] product 2 (4.97 g, 12.2
mol, 85%) was isolated as a colorless solid, mp 103 ꢁC.
1H NMR (CDCl3, 200 MHz): d = 1.42 (s, br, 1H,
OH), 1.48–1.56 (m, 2H, 3-CH2), 1.91–2.06 (m, 2H, 2-
CH2), 3.65 (t, J = 6.3 Hz, 2H, 1-CH2), 7.37–7.41 (m,
9H, ArH), 7.55–7.72 (m, 6H, ArH) ppm. 13C{1H}
NMR (CDCl3, 50 MHz): d = 6.52 (s, 3-CH2), 29.14 [s,
d, 2J(13C,117,119Sn) = 21.4 Hz, 2-CH2], 65.28 [s, d,
1
m.p. 96–97 ꢁC. H NMR (CDCl3, 500 MHz): d = 1.41
[d, dd, dd, 3J(H,H) = 7.4 Hz, 3J(H,117Sn) = 73.4 Hz,
3J(H,119Sn) = 76.5 Hz, 3H, 3-CH3], 1.64 (t, 3J = 4.9
Hz, 1H, OH), 2.23–2.39 (m, 1H, 2-CH), 3.84–4.13
(m, 2H, 1-CH2), 7.35–7.39 (m, 9H, ArH), 7.53–7.63
(m, 6H, ArH) ppm. 13C{1H} NMR (CDCl3, 125
MHz): d = 15.69 [s, d, 2J(13C,117,119Sn) = 16.8 Hz,
3-CH3], 27.62 [s, d, d, 1J(13C,117Sn) = 396.2 Hz,
1J(13C,119Sn) = 414.2 Hz, 2-CH], 67.28 [s, d,
2J(13C,2117,119Sn) = 18.1 Hz, 1-CH2], 128.41 [s,
d, 2J(13C,117,119Sn) = 47.2 Hz, o-CH], 128.74 [s, d,
4J(13C,117,119Sn) = 10.7 Hz, p-CH], 137.27 [s, d,
3J(13C,117,119Sn) = 34.7 Hz, m-CH], 136.69 (s, i-C)
ppm. IR (KBr): ~m ¼ 3365 ðsÞ, 3060 (m), 3016 (m), 2985
(m), 2893 (m), 2857 (m), 1479 (m), 1427 (vs), 1380 (m),
1072 (s), 1022 (m), 984 (s), 730 (vs), 699 (vs), 656 (m)

J. Christoffers et al. / Journal of Organometallic Chemistry 689 (2004) 3550–3555
3553
1
cmꢀ1. MS (EI, 70 eV): m/z (%) = 410 (2) [M+], 351 (95)
[Ph3Sn+], 290 (100), 333 (54) [M+ ꢀ Ph], 291 (100), 197
(49) [PhSn+], 120 (33). Anal. Calcd. for C21H22OSn
(409.12): C 61.66, H 5.42. Found: C 61.87, H 5.41%.
1J(13C,117Sn) = 476.5 Hz, J(13C,119Sn) = 498.6 Hz, i-C]
~
ppm. IR (ATR): m ¼ 3062 ðmÞ, 1480 (s), 1428 (vs),
1306 (m), 1258 (m), 1074 (s), 1023 (m), 997 (m), 729
(vs), 699 (vs), 676 (s), 658 (m) cmꢀ1. MS (EI, 70 eV):
m/z (%) = 351 (100) [M+ ꢀ Ph], 309 (13), 197 (32)
[PhSn+], 154 (8), 120 (12). HRMS Calcd. 350.9962 (for
C15H16Cl120Sn). Found: 350.9962 (M+ ꢀ Ph). Anal.
Calcd. for C21H21ClSn (427.54): C 59.00, H 4.95.
Found: C 59.02, H 4.99%.
3.3. 3-Triphenylstannylpropyl p-toluenesulfonate (4)
A solution of p-TsCl (2.32 g, 12.2 mmol) in pyridine
(3.60 g, 45.5 mmol, 3.7 cm3) was slowly added to 2 (4.97
g, 12.2 mmol), and the reaction mixture stirred at room
temperature for 4 h. Then water (15 cm3) was added,
and the reaction mixture was acidified with 50%
H2SO4–H2O. The aqueous layer was extracted with
CH2Cl2 (4 · 20 cm3) and the combined organic layers
were dried (MgSO4). The solvent was distilled off, and
the remaining volatile materials were removed under
high vacuum. The residue was chromatographed
(SiO2, gradient PE/EA from 10:1 via 5:1 to 1:1, followed
by EA). In a first fraction a mixture of 4 and byproduct
5 in a molar ratio of 5.6:1.0 was obtained (total 1.45 g,
containing 178 mg, 0.401 mmol, 3% of 5, and 1.27 g,
2.25 mmol, 18% of 4). In a second fraction [Rf(PE/
EA = 5:1) = 0.29] product 4 (4.34 g, 7.70 mmol, 63%)
was isolated as a colorless solid, giving 81% overall yield
of 4, m.p. 75–76 ꢁC. 1H NMR (CDCl3, 200 MHz):
d = 1.37–1.60 (m, 2H, 3-CH2), 1.95–2.10 (m, 2H, 2-
CH2), 2.45 (s, 3H, CH3), 4.00–4.06 (t, J = 6.5 Hz, 2H,
1-CH2), 7.27–7.35 (m, 2H, tosyl), 7.35–7.44 (m, 10H,
Ph3Sn), 7.44–7.66 (m, 5H, Ph3Sn), 7.71–7.79 (m, 2H, to-
syl) ppm. 13C{1H} NMR (CDCl3, 50 MHz): d = 5.80 (s,
3-CH2), 21.57 (s, CH3), 26.03 (s, 2-CH2), 72.95 (s, 1-
CH2), 127.81 (s, tosyl-o-CH), 128.56 [s, d,
2J(13C,117,119Sn) = 50.0 Hz, o-CH], 129.02 [s, d,
4J(13C,117,119Sn) = 11.1 Hz, p-CH], 129.74 (s, tosyl-m-
3.4.
cyclopentadiene (6)
4-(tert-Butyl)-1-(3-triphenylstannylpropyl)-1,3-
Under exclusion of moisture and air tBuCpH (4.86 g,
39.8 mmol) was slowly added dropwise to NaH (2.38 g,
59.5 mmol, 60% suspension in paraffin) at ꢀ78 ꢁC, and
the stirred reaction mixture warmed to room tempera-
ture. After cooling to ꢀ78 ꢁC, a solution of 4 (5.60 g,
9.95 mmol) in THF (12 cm3) was added dropwise, and
the reaction mixture allowed to warm up to room tem-
perature (12 h). All volatile materials were removed,
and the residue was chromatographed (SiO2, PE/
EA = 5:1). In a first fraction [Rf(PE/EA = 1:1) = 0.68]
byproduct 7 (1.16 g, 4.75 mmol, 12% reg. tBuCpH)
was obtained as a colorless solid. In a second fraction
[Rf(PE) = 0.10] product 6 (4.68 g, 9.12 mmol, 92% reg.
1
4) was isolated as a redbrown oil. H NMR (CDCl3,
500 MHz): d = 0.92–1.35 (m, 9H, t-Bu), 1.53–1.67 (m,
2H, CH2), 1.84–2.15 (m, 2H, CH2), 2.21–2.59 (m, 2H,
CH2), 2.71–2.96 (m, 2H, CH2), 5.71–6.53 (m, 2H,
CH), 7.24–7.40 (m, 9H, ArH), 7.49–7.58 (m, 6H, ArH)
~
ppm. IR (ATR): m ¼ 3063 ðmÞ, 3047 (m), 2959 (s),
2905 (m), 2867 (m), 1711 (m), 1480 (m), 1429 (vs),
1364 (m), 1075 (s), 1022 (m), 997 (m), 728 (vs), 699
(vs), 659 (m) cmꢀ1. MS (EI, 70 eV): m/z (%) = 514 (2)
[M+], 437 (4) [M+ ꢀ Ph], 351 (100) [Ph3Sn+], 309 (45),
273 (4) [Ph2Sn+], 197 (37) [SnPh+], 154 (58), 120 (18)
½t-BuC5Hþ3 ꢁ, 77 (27) [Ph+], 57 (39) [t-Bu+]. HRMS Calcd.
514.1682 (for C30H34120Sn). Found: 514.1679 (M+).
CH),
133.14
(s,
tosyl-i-C),
136.88
[s,
d,
3J(13C,117,119Sn) = 35.7 Hz, m-CH], 137.89 (s, i-C),
~
144.56 (s, tosyl-p-CH) ppm. IR (ATR): m ¼ 3063 ðmÞ,
3046 (m), 1428 (s), 1359 (s), 1188 (s), 1176 (vs), 1096
(m), 1074 (m), 1021 (m), 997 (m), 955 (s), 895 (m), 815
(m), 772 (m), 728 (s), 699 (vs), 665 (m) cmꢀ1. MS (EI,
70 eV): m/z (%) = 487 (24) [M+ ꢀ Ph], 445 (42) [M+–
Bn – C2H4], 351 (100) [Ph3Sn+], 197 (24) [SnPh+], 132
(90). HRMS Calcd. 487.0389 (for C22H23O3S120Sn).
Found: 487.0389 (M+ ꢀ Ph). Anal. Calcd. for
C28H28O3SSn (563.30): C 59.70, H 5.01. Found: C
3.5.
(7)
1,4-Di-tert-butyltricyclo[5.2.1.01,7]deca-3,8-diene
Melting point 55–58 ꢁC. 1H NMR (CDCl3, 500
MHz): d = 0.95 (s, 9H, t-Bu), 0.98 (s, 9H, t-Bu), 1.18
[ddt, 2J(10-Hanti, 10-Hsyn) = 7.9 Hz, 3J(10-Hanti, 7-
H) = 1.4 Hz, 4J(10-Hanti, 8,9-H) = 0.8 Hz, 1H, 10-Hanti],
1.34 [dd, 2J(10-Hsyn, 10-Hanti) = 7.9 Hz, 3J(10-Hsyn
7-H) = 1.8 Hz, 1H, 10-Hsyn], 1.70 [dddd, 2J(5-Hendo
5-Hexo) = 16.7 Hz, 3J(5-Hendo, 6-H) = 3.3 Hz, 4J (5-Hendo
1
59.70, H 5.16%. Byproduct 5: m.p. 106 ꢁC. H NMR
(CDCl3, 200 MHz): d = 1.42–1.94 (m, 2H, 1-CH2),
2.10–2.49 (m, 2H, 2-CH2), 3.66 (t, J = 6.7 Hz, 2H, 3-
CH2), 7.44–7.63 (m, 9H, ArH), 7.66–7.88 (m, 6H,
ArH) ppm. 13C{1H} NMR (CDCl3, 50 MHz): d = 7.88
,
,
,
1
1
4
[s, d, d, J(13C,117Sn) = 364.6 Hz, J(13C,119Sn) = 381.5
2-H) = 3.6 Hz, J(5-Hendo, 3-H) = 2.0 Hz, 1H, 5-Hendo],
Hz, 1-CH2], 29.80 [s, d, J(13C,117,119Sn) = 16.1 Hz, 2-
2.15 [dddd, 2J(5-Hexo, 5-Hendo) = 16.7 Hz, 3J(5-Hexo
6-H) = 10.1 Hz, 4J(5-Hexo, 3-H) = 2.1 Hz, 4J(5-Hexo
,
,
2
CH2], 47.98 [s, d, J(13C,117,119Sn) = 83.9 Hz, 3-CH2],
3
128.55 [s, d, J(13C,117,119Sn) = 46.4 Hz, o-CH], 128.99
2-H) = 1.8 Hz, 1 H, 5-Hexo], 2.74–2.79 (m, 2H, 6,7-H),
2
3
3.17 [dddd, J(2-H,6-H) = 8.2 Hz, J(2-H,5-Hendo) = 3.6
4
[s, d, 4J(13C,117,119Sn) = 11.1 Hz, p-CH], 136.91 [s, d,
3J(13C,117,119Sn) = 35.6 Hz, m-CH], 138.12 [s, d, d,
3
4
Hz, J(2-H,3-H) = 2.0 Hz, J(2-H,5-Hexo) = 1.8 Hz, 1H,

3554
J. Christoffers et al. / Journal of Organometallic Chemistry 689 (2004) 3550–3555
2-H], 5.15–5.16 [ddd, 4J(3-H,5-Hendo) = 2.2 Hz, 3J(3-
H,2-H) = 2.0 Hz, 4J(3-H,5-Hexo) = 2.0 Hz, 1H, 3-H],
5.88 (s, 2H, 8,9-H) ppm. 13C{1H} NMR (CDCl3, 125
MHz): d = 27.83 (CH3), 29.39 (CH3), 31.41 (C), 32.77
(C), 33.38 (C-5), 44.35 (CH), 45.69 (CH), 49.45 (C-10),
53.52 (C-2), 65.24 (C-1), 123.35 (C-3), 130.87 (@CH),
137.59 (@CH) 155.48 (C-4) ppm. IR (KBr):
3.8. Bis[g5-1-(tert-butyl)-3-(3-triphenylstannylpropyl)-
cyclopentadienyl]iron(II) (10)
Under exclusion of moisture and air at 0 ꢁC PhLi (2.41
mmol, 1.50 cm3 of a 1.6 mol dm3 solution in cyclohex-
ane/Et2O = 70:30) was added dropwise to a solution of
6 (990 mg, 1.93 mmol) in THF (1.5 cm3), and the reaction
mixture stirred at room temperature for 15 min. Then
powdered iron(II) chloride (122 mg, 0.965 mmol) was
added, and the reaction mixture stirred for 3 h. After
acidifying with 20% citric acid–H2O (ice-cooling), the
aqueous layer was extracted with CH2Cl2 (4 · 10 cm3),
and the combined organic layers were dried (MgSO4)
and concentrated. The residue was purified by chroma-
tography (SiO2, PE/EA = 20:1). In a first fraction start-
ing material 6 (268 mg, 0.522 mmol, 27%) was
reisolated. In a second fraction [Rf(PE/EA = 20:1) =
0.00–0.05] product 10 (488 mg, 0.452 mmol, 47%) was
isolated as a red oil. 1H NMR (CDCl3, 300 MHz):
d = 1.12–1.18 (m, 18H, t-Bu), 1.40–1.58 (m, 4H, 3-
CH2), 1.69–2.01 (m, 4H, 2-CH2), 2.15–2.55 (m, 4H, 1-
CH2), 3.39–3.88 (m, 6H, CpH), 7.31–7.38 (m, 18H,
ArH), 7.44–7.63 (m, 12H, ArH) ppm. IR (film):
~
m ¼ 3064 ðmÞ, 2961 (vs), 2900 (vs), 2864 (vs), 1474 (m),
1460 (m), 1391 (m), 1362 (s), 1248 (m), 862 (m), 837
(s), 809 (m), 744 (m), 725 (s) cmꢀ1. MS (EI, 70 eV): m/
z (%) = 244 (5) [M+], 122 (79) ½C9Hþ ꢁ, 107 (100)
14
½C8Hþꢁ, 91 (14), 57 (12) [t-Bu+]. Anal. Calcd. for
7
C18H28 (244.42): C 88.45, H 11.55. Found: C 88.28, H
11.61%.
3.6. Preparation of ferrocene 8
At 0 ꢁC n-BuLi (4.00 mmol, 2.5 cm3 of a 1.6-
mol dmꢀ3 solution in hexane) was added dropwise to a
solution of 6 (1.639 g, 3.194 mmol) in THF (2 cm3) fol-
lowed by addition of FeCl2 (204 mg, 1.60 mmol), and
the reaction mixture was stirred for 1.5 h. After addition
of ice (20 g), the reaction mixture was neutralized with
20% citric acid–H2O and extracted with CH2Cl2
(3 · 15 cm3). The combined organic layers were dried
(MgSO4) and concentrated. The residue was chromato-
graphed (SiO2, PE/EA = 20:1) to give a red-colored frac-
tion containing 8 (383 mg, red oil) as a mixture of
several species.
~
m ¼ 3062 ðmÞ, 3012 (s), 2953 (m), 2858 (m), 1428 (s),
1074 (m), 727 (vs), 698 (vs), 658 (m) cmꢀ1. MS (EI, 70
eV): m/z (%) = 1082 (82) [M+], 731 (4) [M+ ꢀ Ph3Sn],
674 (18) [M+ ꢀ Ph3Sn ꢀ C5H9], 569 (18) [C30H33FeSn+],
351 (100) [Ph3Sn+], 279 (19), 197 (22) [PhSn+], 78 (100)
½C6Hþ6 ꢁ. Anal. Calcd. for C60H66FeSn2 (1080.45): C
66.70, H 6.16. Found: C 66.70, H 6.15%.
3.7.
Bis[g5-1-(tert-butyl)-3-(3-tributylstannylpropyl)-
cyclopentadienyl]iron(II) (9)
3.9. Bis[g5-1-(tert-butyl)-3-(3-triphenylstannylpropyl)-
cyclopentadienyl]dichlorozirconium(IV) (11)
Under N2 atmosphere and exclusion of moisture at
0 ꢁC n-BuLi (8.00 mmol, 5.0 cm3 of a 1.6-mol dmꢀ3
solution in hexane) was added dropwise to a solution
of 8 (383 mg) in THF (1.0 cm3), and the reaction mix-
ture was stirred at room temperature for 3 days. After
acidifying with 20% citric acid–H2O, the aqueous layer
was extracted with CH2Cl2 (3 · 10 cm3). The combined
organic layers were dried (MgSO4) and concentrated.
The residue was chromatographed (SiO2, PE,
Rf = 0.54–0.63) to give 9 (300 mg, 0.312 mmol) as a
red oil. 1H NMR (CDCl3, 300 MHz): d = 0.77–0.85
PhLi (1.51 mmol, 0.84 cm3 of a 1.8 mol dm3 solution
in cyclohexane/Et2O = 70:30) was added dropwise to a
solution of 6 (776 mg, 1.51 mmol) in THF (3 cm3) at
ꢀ78 ꢁC, and the reaction mixture stirred for 15 min.
Then a solution of ZrCl4 Æ 2THF in THF [prepared by
adding ZrCl4 Æ 2THF (285 mg, 0.755 mmol) to THF (5
cm3) at ꢀ78 ꢁC and warming the suspension to room
temperature] was added dropwise at ꢀ78 ꢁC, and the
reaction mixture allowed to warm up to room tempera-
ture (16 h). After removal of all volatile materials, the
residue was extracted with boiling toluene (15 cm3).
Concentration of the extract gave 11 (349 mg, 0.294
3
(m, 16H, CH2), 0.89 (t, J = 7.2 Hz, 18H, CH3), 0.86–
0.91 (m, 4H, CH2), 1.19–1.21 (m, 6H, CH2), 1.23–1.36
1
(m, 26H, t-Bu, CH2), 1.42–1.55 (m, 14H, CH2), 3.60–
~
mmol, 39%) as a colorless oil. H NMR (CDCl3, 300
4.04 (m, 6H, CpH) ppm. IR (film): m ¼ 2956 ðsÞ, 2924
MHz): d = 1.03–1.27 (m, 18H, t-Bu), 1.37–1.68 (m,
4H, CH2), 1.75–2.12 (m, 4H, CH2), 2.38–2.61 (m, 2H,
CH2), 2.65–2.80 (m, 2H, CH2), 5.56–6.21 (m, 6H,
CpH), 7.32–7.37 (m, 20H, Ph), 7.41–7.61 (m, 10H, Ph)
(s), 2854 (m), 2360 (m), 2341 (m), 1459 (m), 1376 (w),
1359 (w), 1131 (m), 1109 (m) cmꢀ1. MS (EI, 70 eV):
m/z (%) = 962 (<1) [M+], 671 (<1) [M+ ꢀ SnBu3], 382
(4) [C19H34Sn+], 291 (100) ½SnBuþ3 ꢁ, 234 (63)
~
ppm. IR (film) m ¼ 3063 ðmÞ, 3047 (m), 2959 (s), 2905
½HSnBuþꢁ, 179 (71) [H2SnBu+], 121 (31) [HSn+], 57 (5)
(m), 2866 (m), 1462 (m), 1428 (s), 1362 (m), 1259 (m),
1201 (m), 1074 (m) cmꢀ1. MS (EI, 70 eV): m/z
(%) = 1109 (20) [M+ ꢀ Ph], 1067 (7), 723 (23), 633
(41), 436 (65), 308 (100), 274 (43), 196 (40), 154 (95),
2
½C4Hþ9 ꢁ. HRMS Calcd. 962.4436 (for C48H9056Fe120Sn2).
Found: 962.4457 (M+). Anal. Calcd. for C48H90FeSn2
(960.51): C 60.02, H 9.44. Found: C 60.60, H 9.60%.

J. Christoffers et al. / Journal of Organometallic Chemistry 689 (2004) 3550–3555
3555
12
[5] B.E. Bosch, G. Erker, R. Fro¨hlich, O. Meyer, Organometallics 16
(1997) 5449–5456.
119 (39). HRMS Calcd. 1109.1236 (for
35Cl2120Sn290Zr). Found: 1109.1233 (M+ ꢀ Ph).
C H61-
48
[6] T.K. Hollis, L.-S. Wang, F. Tham, J. Am. Chem. Soc. 122 (2000)
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Acknowledgements
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(c) C. Janiak, K.C.H. Lange, P. Marquardt, J. Mol. Catal. A:
Chem. 180 (2002) 43–58;
We gratefully acknowledge financial support from
the Fonds der Chemischen Industrie.
´
(d) J.-N. Pedeutour, K. Radhakrishnan, H. Cramail, A. Deffieux,
Macromol. Rapid Commun. 22 (2001) 1095–1123;
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